Angiogenesis contributes to the pathogenesis of many diseases including exudative age-related macular degeneration (AMD). It is normally kept in check by a tightly balanced production of pro- and anti-angiogenic factors. The up-regulation of the pro-angiogenic factor, vascular endothelial growth factor (VEGF), is intimately linked to the pathogenesis of exudative AMD, and its antagonism has been effectively targeted for treatment. However, very little is known about potential changes in expression of anti-angiogenic factors and the role they play in choroidal vascular homeostasis and neovascularization associated with AMD. Here, we will discuss the important role of thrombospondins and pigment epithelium-derived factor, two major endogenous inhibitors of angiogenesis, in retinal and choroidal vascular homeostasis and their potential alterations during AMD and choroidal neovascularization (CNV). We will review the cell autonomous function of these proteins in retinal and choroidal vascular cells. We will also discuss the potential targeting of these molecules and use of their mimetic peptides for therapeutic development for exudative AMD.

Introduction

Age-related macular degeneration (AMD) is a major cause of visual impairment in the elderly population worldwide. In 2010, macular degeneration (mainly age-related) was the third most common cause of blindness (8.69% of all cases in 2010) [1]. The global occurrence of AMD is expected to increase with nearly a 6-fold rise in aging population from 2010 to 2050. Despite the high prevalence of AMD, its etiology remains largely unknown. AMD is characterized by a progressive degeneration of the macula and severe vision loss. It presents in two major forms: the dry form that is associated with degeneration of retinal pigmented epithelium (RPE) and photoreceptors, and the exudative or wet form that presents the formation of choroidal neovascularization (CNV) [2,3]. Neovascularization in exudative AMD is classified to different subtypes including type 1 (sub-RPE), type 2 (sub-retinal), type 3 (intraretinal), and mixed neovascularization [4]. The detailed mechanisms underlying the pathogenesis of CNV are not well understood. Early phase of CNV is associated with the altered production of angioregulatory factors, and enhanced migration and proliferation of choroidal endothelial cells (ChEC) in the retina rupturing through the Bruch's membrane. In the active phase, CNV starts to expand, either by remaining beneath the RPE or by entering the sub-retinal space (Figure 1). Ultimately, in the end phase CNV becomes fibrotic and represents disciform scars [57]. The diameter and thickness of these disciform scars might be influenced by the degree of RPE and photoreceptor cell degeneration [7].

Factors associated with the pathogenesis of AMD and CNV

Figure 1
Factors associated with the pathogenesis of AMD and CNV

(A) Dysregulated production of angioregulatory factors will affect various aspects of angiogenesis contributing to vascular dysfunction and proliferation. (B) The organization of the RPE–choroid complex under normal conditions (top panel), and its disorganization in AMD and development of CNV (lower panel).

Figure 1
Factors associated with the pathogenesis of AMD and CNV

(A) Dysregulated production of angioregulatory factors will affect various aspects of angiogenesis contributing to vascular dysfunction and proliferation. (B) The organization of the RPE–choroid complex under normal conditions (top panel), and its disorganization in AMD and development of CNV (lower panel).

The increased production of vascular endothelial growth factor (VEGF), a potent pro-angiogenic factor, is identified as an essential factor in the development and progression of AMD and CNV. We and others have also proposed that changes in the expression of endogenous inhibitors of angiogenesis, including thrombospondin-1 (TSP1) and pigment epithelium-derived factor (PEDF), make significant contributions to the pathogenesis of AMD and CNV, and are major subjects of this review.

The choroidal vasculature plays a crucial role in retinal homeostasis and vision. It functions to dissipate heat and nourish the RPE and outer retinal photoreceptor cells through their fenestrated capillary endothelial cells (EC). Choroidal vascular dysfunction is now recognized as a critical early event in the development and progression of AMD and CNV. The choroid and its vascular system may also be affected by alterations in inner retinal vasculature as occurs in retinopathy of prematurity and diabetic retinopathy. However, the detailed mechanisms that affect ChEC function and the pathogenesis of AMD remain poorly understood, and may be influenced by the altered production of many pro- and anti-angiogenic factors including VEGF, PEDF, and TSP1, to name a few.

RPE cells are a major source of ocular angioregulatory proteins, which maintain ocular angiogenesis in check. The impairment of RPE cell function is an early and crucial event in the molecular pathways that lead to clinically relevant AMD changes, and alterations in the angiogenic balance that drives CNV. Neovascularization occurs as a result of the altered balanced production of pro- and anti-angiogenic factors, most likely by RPE cells, and may contribute to various eye diseases including diabetic retinopathy and exudative AMD [810]. Many studies have reported the impaired production of TSP1 and PEDF in these vascular retinopathies [11]. However, the underlying mechanisms, which contribute to these changes, remain largely unexplored.

In humans, TSP1 is present at high levels in the vitreous and aqueous humor, and is a major component of the Bruch's membrane [12,13]. A decreased TSP1 level in the Bruch's membrane and choroidal vessels during AMD is suggested to be a potential contributing factor favoring the formation of CNV [12]. PEDF, a glycoprotein (50 kDa), is also an endogenous inhibitor of angiogenesis and it is present in the vitreous at high levels [14]. A number of studies have demonstrated important roles for PEDF in the modulation of vascular leakage and angiogenesis in AMD and DR [15,16]. Patients with the dry form of AMD demonstrate a significant decrease in PEDF plasma levels. In contrast, patients with wet AMD demonstrate a strong positive correlation between VEGF and PEDF concentrations [17].

Drugs that antagonize VEGF activity are currently the standard of care for treatment of exudative AMD, and effectively delay disease progression in most patients. However, VEGF antagonists significantly improve vision in only 30% of patients, and 20% of treated patients still progress to severe vision loss, becoming legally blind. Combined therapeutic regimens incorporating a low-dosage of VEGF antagonists have been suggested as a potential therapy to provide more effective and safer treatment for AMD. Thus, a greater need for the development of alternative treatments is highly justified.

Here, we will review the physiological role and functional relevance of endogenous inhibitors of angiogenesis, namely TSP1 and PEDF, in ocular vascular homeostasis, and their potential contributions to pathologies of exudative AMD. Furthermore, we propose the potential use of short peptides that mimic the anti-angiogenic action of these molecules in the treatment of exudative AMD, alone or in combination with existing therapies.

AMD and endogenous inhibitors of angiogenesis

Ocular vascular homeostasis

Ocular vascular homeostasis is maintained by a balanced production of positive and negative angioregulatory factors. Different pathological conditions including inflammation, oxidative stress, and/or ischemia can disrupt this balance by inducing the production of pro-angiogenic factors while suppressing the production of anti-angiogenic factors in damaged cells [18,19]. The presence of several endogenous inhibitors of angiogenesis including, TSP1, PEDF, endostatin, and angiostatin has been reported in the eye [20,21]. Some of these anti-angiogenic factors need proteolytic processing for their activation [20]. For example, endostatin has anti-angiogenic activity only after proteolytic cleavage [21].

TSP1 and PEDF both inhibit angiogenesis through the selective induction of apoptosis of EC involved in the formation of new blood vessels, without a significant impact on the EC of existing mature blood vessels [22,23]. Decreased levels of TSP1, PEDF, and endostatin in the Bruch's membrane and choriocapillaris complex have been detected in ocular samples from patients with AMD. Furthermore, high levels of TSP1 and PEDF accumulate in disciform scars, a hallmark of CNV formation [5]. These studies suggest that alterations in the production of angiogenesis inhibitors by RPE cells, and their diminished presence in the Bruch's membrane and choriocapillaris may play a substantial role in the pathogenesis of exudative AMD. However, little is known about the physiological function of these inhibitors in the development and function of choriocapillaris, and how their alterations contribute to the pathogenesis of AMD and CNV.

Thrombospondins

TSP1 or platelet TSP was the first member of the TSP family identified at high levels in the α-granules of platelets [24]. It is a homotrimeric multi-domain and multifunctional calcium-binding extracellular matrix protein, produced by many cell types including ChEC and RPE cells [25]. TSP1 and TSP2 are the only members of the TSP subfamily with anti-angiogenic activity, but only TSP1 has been extensively studied [26]. TSP1 has six major motifs including an N-terminal heparin-binding domain, procollagen homology domain, type I repeats, type II repeats, type III repeats, and a C-terminal globular cell-binding domain. Domain organization of TSP1 and function of TSP1-derived peptides from these domains are shown in Figure 2. TSP2 also has a very similar multi-domain organization to TSP1, with the degree of homology with TSP1 increasing when moving from the N-terminus to C-terminus [27,28].

Domain organization of TSP1 and function of TSP1-derived peptides from these domains.

Figure 2
Domain organization of TSP1 and function of TSP1-derived peptides from these domains.
Figure 2
Domain organization of TSP1 and function of TSP1-derived peptides from these domains.

The different biological functions of TSP1 are attributed to its interactions with various cell surface receptors that are differentially expressed in a cell-type-specific manner [29]. Its anti-angiogenic activity was the first identified biological function of TSP1 demonstrated in the late 1980s [30,31]. TSP1 modulates proliferation, migration, differentiation, and apoptosis of various cell types including EC, pericytes, smooth muscle cells, fibroblasts, and macrophages [3133]. It also has a critical role in the regulation of various biological functions such as vascular homeostasis, immunity, and wound healing [31,3436]. Although TSP2 exhibits some unique biological functions, it also shares some of the same biological functions as TSP1. However, the majority of shared functions, such as wound healing, are not overlapping but specific to a TSP family member [37].

TSP1 and retinal vascularization

In eyes, TSP1 is present at high levels in the vitreous and aqueous humor from various species, and is a major component of the Bruch's membrane [12,13]. We have shown that TSP1 expression is required for adequate pruning and re-modeling of the developing retinal vasculature. TSP1 plays an active role in the elimination of excess blood vessels during the late stages of retinal vascularization [38]. This effect is mitigated under ischemic conditions when VEGF levels are high. Thus, Thbs1-deficient mice fail to undergo appropriate vascular pruning and as a result exhibit increased vascular density during postnatal retinal vascular development [39,40]. In addition, we showed that early and premature embryonic expression of TSP1 in the eye results in defective postnatal retinal vascular development and attenuation of retinal neovascularization during oxygen-induced ischemic retinopathy (OIR) [41].

Animal models have been extensively used in expanding our knowledge and understanding of the pathogenesis of exudative AMD and the development of new effective treatments [42]. Decreased TSP1 levels in the Bruch's membrane and choroidal vessels during AMD suggest a potential regulatory role for TSP1 in the pathogenesis of CNV [12]. We recently investigated the impact of TSP1 expression in a mouse model of laser-induced CNV. We showed that Thbs1−/− mice exhibit significantly larger neovascular lesions compared with wild-type (Thbs1 +/+) mice. The average CNV area per eye was significantly increased (∼8-fold) in TSP1 null mice (23,750±4,200 μm2, n=15 eyes) compared with wild-type mice (3235±910 μm2, n=15 eyes) [43]. The increased area of neovascularization was associated with the increased recruitment of macrophages in Thbs1−/− mice following laser rupture of the Bruch's membrane. These results are consistent with the anti-angiogenic and anti-inflammatory activity of TSP1 [4446] and support the hypothesis that the aberrant modulation of TSP1 expression contributes to the pathogenesis of exudative AMD [47].

Cell autonomous function of TSP1

Studies from our laboratory have demonstrated that TSP1 differentially affects the function of various ocular cell types that produce TSP1 including EC (Table 1). Retinal EC prepared from TSP1-deficient mice exhibit a pro-angiogenic phenotype through the sustained activation of pro-angiogenic signaling pathways [31]. TSP1 regulates VEGF-A-mediated Akt signaling and capillary survival during retinal vascular development [48]. We have shown that Thbs1−/− retinal EC are more proliferative and migratory [49]. In contrast, Thbs1−/− choroidal EC are less proliferative and migratory [50]. We also recently showed significant changes in several aspects of RPE cell function associated with TSP1 deficiency, which may contribute to AMD pathogenesis (Table 1). Thbs1−/− RPE cells exhibited increased proliferation and oxidative stress, and were less migratory. The increased proliferation rate of RPE cells in the absence of TSP1 suggests that TSP1 may negatively impact RPE cell proliferation, as in retinal EC, via CD47 and CD36 receptors, both of which are expressed in RPE cells. Increased macular densities of aging RPE cells are associated with higher apoptotic activity in the macula [5153]. This increased death of macular RPE cells may be compensated by migration of peripheral RPE cells [52,54]. We showed that TSP1 deficiency results in reduced migration of RPE cells. Thus, a decreased level of TSP1 during AMD may decrease migration of RPE cells and promote RPE atrophy and progression of the disease.

Table 1
Impacts of TSP1 expression on the function of various retinal cell types
Cell characteristicThbs1−/− RECThbs1−/− ChECThbs1−/− RPEThbs1−/− RPC
Morphology Normal Spindly morphology Normal Normal 
Specific markers  No significant difference in VE-CAD and PECAM-1 Decreased RPE65 expression No significant difference 
Proliferation Increased Decreased Increased Decreased 
Apoptosis basal
Challenged conditions 
Decreased pro-apoptotic signaling Increased
Increased 
No difference
Increased 
 
Migration Increased Decreased Decreased Decreased 
Adhesion  Less adherent to FN, VN, Col I, and Col IV More adherent to Col I and Col IV Less adherent to FN, VN
More adherent to Col I 
Junctional protein localization  No significant impact on junctional localization More ZO1 nuclear localization  
Oxidative stress   Increased  
VEGF expression  No difference Increased  
Capillary morphogenesis  Decreased – – 
Phagocytosis – – Decreased – 
Cell characteristicThbs1−/− RECThbs1−/− ChECThbs1−/− RPEThbs1−/− RPC
Morphology Normal Spindly morphology Normal Normal 
Specific markers  No significant difference in VE-CAD and PECAM-1 Decreased RPE65 expression No significant difference 
Proliferation Increased Decreased Increased Decreased 
Apoptosis basal
Challenged conditions 
Decreased pro-apoptotic signaling Increased
Increased 
No difference
Increased 
 
Migration Increased Decreased Decreased Decreased 
Adhesion  Less adherent to FN, VN, Col I, and Col IV More adherent to Col I and Col IV Less adherent to FN, VN
More adherent to Col I 
Junctional protein localization  No significant impact on junctional localization More ZO1 nuclear localization  
Oxidative stress   Increased  
VEGF expression  No difference Increased  
Capillary morphogenesis  Decreased – – 
Phagocytosis – – Decreased – 

The increased production of VEGF plays a substantial role in the development and progression of AMD and CNV. TSP1 deficiency resulted in significant changes in the level of VEGF produced by RPE cells further supporting a significant role for TSP1 changes in the development and progression of AMD. The roles of TSP1 in the regulation of angiogenic processes are complex and involve either direct or indirect effects on ocular vascular cells or their extracellular matrix composition. TSP1 conveys its anti-angiogenic effect via CD36, a scavenger receptor, and CD47 expressed on the EC [5558]. However, the contribution of these interactions to RPE and choroidal EC function need further investigation.

Another biological feature exhibited in mice lacking TSP1 was the increased infiltration of macrophages during the early stage of laser-induced CNV, a sign of enhanced inflammation [43]. TSP1 modulates retinal vascular hemostasis and perfusion by the regulation of nitric oxide (NO) signaling [31]. NO is a signaling molecule that plays a major role in vasodilatation and permeability [59]. Experimental findings indicated that increased NO production favors the formation of CNV leading to the development of AMD pathologies [60,61]. Our laboratory previously reported that Thbs1−/− choroidal EC exhibit a higher level of phosphorylated (active) eNOS and a significant increase in intracellular NO levels. In addition, Thbs1−/− choroidal EC showed significantly higher levels of iNOS, a marker of inflammation, compared with the wild-type cells. Elevated iNOS expression may result in significant induction of NO production and oxidative stress through the production of peroxynitrate [50,6264]. These observations are consistent with the pro-inflammatory phenotype observed in Thbs1−/− mice and enhanced laser-induced CNV [43].

TSP2 and retinal vascularization

The early studies examining TSP expression indicated that TSP2 is not expressed in mouse eyes [65]. However, we showed that TSP2 is not only expressed in retinal astrocytes but its level is increased in TSP1-deficient retinal astrocytes in culture [66]. We later showed that although TSP2 is undetectable in wild-type retinal EC, wild-type lung EC express a significant amount of TSP2 [67]. In addition, Cyp1b1-deficient retinal EC expressed high levels of TSP2. This was attributed to increased oxidative stress in Cyp1b1-deficient retinal EC, and it was reversed by re-expression of Cyp1b1 or incubation with the antioxidant N-acetylcysteine [6870]. These studies suggested an important anti-angiogenic role for TSP2 under oxidative stress. We later showed that the retinal pericytes also produce TSP2, and in fact showed that pericytes are the major source of TSP2 production in retinal vasculature using a TSP2 reporter mouse [71]. The Cyp1b1-deficient retinal pericytes expressed a higher TSP2 level and they were more proliferative and migratory [69].

Later, we showed that TSP2 is also expressed in the mouse retina at postnatal day 5 (P5) and its level increased by nearly 3-fold and remained high up to P42. This was further confirmed by using whole mount staining and Western blot analysis of TSP2-GFP reporter mice. However, TSP2 protein levels (GFP-reporter) were undetectable at P42 [72]. This is consistent with the limited expression of the TSP2 protein observed in adult retina. We also showed that choroidal EC, unlike retinal EC, express a significant amount of TSP2. Furthermore, the expression of TSP2 was increased in Thbs1-deficient ChEC [50]. RPE cells also expressed a low amount of TSP2, which was increased in Thbs1-deficient RPE cells [73]. However, the cell autonomous impact of TSP2 expression on choroidal EC and RPE cell functions remain a subject of future investigation.

We have examined the impact of TSP2 expression on the postnatal development of retinal vasculature, and retinal and CNV during OIR and laser-induced CNV respectively. We showed that the primary retinal vasculature develops at a faster rate in Thbs2−/− mice with a minimal impact on the rate of vascular cell proliferation and apoptosis. Thbs2 deficiency also minimally affected the degree of retinal and CNV [72]. However, the TSP2 level was significantly up-regulated in P17 mice subjected to OIR. This could be attributed to increased oxidative stress at this stage and needs further verification. We also showed that although lack of TSP1 had no effect on the expression of TSP2 level during normal development or OIR in the retina, the level of TSP1 was significantly lower in the absence of TSP2 [72]. Thus, lack of TSP2 expression in the retina does not cause a compensatory increase in TSP1 levels. These observations are consistent with the different roles proposed for TSP1 and TSP2 in the regulation of angiogenesis during normal development (TSP2) and reparative processes (TSP1).

The potential therapeutic use of TSP2 as an inhibitor of angiogenesis has not been extensively evaluated. Although the presence of similar anti-angiogenic domains and sequence homology suggest the presence of potential peptides from these regions that may have anti-angiogenic and thus therapeutic potential, the availability and utility of such peptides await further investigation. Studies evaluating comparable C-terminal peptides from these molecules suggest significant differences among peptides from TSP1 and TSP2 [74]. These results are consistent with the non-overlapping function of these members of the TSP family and await further studies of TSP2 mimetic peptides.

Pigment epithelium-derived factor

PEDF is a non-inhibitory serpin proteinase that was originally detected in the human fetal RPE cell [75,76]. PEDF is a broadly expressed multifunctional protein with crucial roles in various physiological and pathophysiological mechanisms involved in angiogenesis, neuroprotection, fibrogenesis, and inflammatory responses [77]. Neurotrophic or anti-angiogenic activity of PEDF is determined by its phosphorylation state via casein kinase (CK2) and protein kinase A (PKA) [78]. Phosphorylation of PEDF by CK2 on Ser24 and Ser114 results in anti-angiogenic activity and a conformational change in PEDF that inhibit PEDF phosphorylation by PKA and eliminate its neurotrophic activity. PKA phosphorylates PEDF at Ser227 resulting in the neurotrophic activity of PEDF and reduced anti-angiogenic activity [78]. Structural properties of PEDF and the function of PEDF-derived peptides from these domains are shown in Figure 3. PEDF exhibits a potent inhibitory activity toward the angiogenic activity of VEGF and fibroblast growth factor (FGF). PEDF is an endogenous inhibitor of angiogenesis, is present at high levels in the eye, and is capable of blocking the activity of pro-angiogenic factors. PEDF is postulated to have a major role in neurovascular homeostasis and the prevention of angiogenesis in healthy ocular tissue [79]. However, the detailed molecular and cellular mechanisms involved remain largely unknown.

Domain organization of PEDF and function of PEDF-derived peptides from these domains.

Figure 3
Domain organization of PEDF and function of PEDF-derived peptides from these domains.
Figure 3
Domain organization of PEDF and function of PEDF-derived peptides from these domains.

PEDF and retinal vascularization

The altered production of PEDF plays a critical role in retinal differentiation and the maintenance of retinal function as well as the survival of retinal neurons via its neurotrophic function [8082]. In the eye, PEDF modulates blood vessel growth by initiating a permissive environment for angiogenesis while the oxygen concentration is low (such as retinopathies and/or tumors) and an inhibitory environment when oxygen concentrations are normal or high [83]. Previous studies in our laboratory investigated the role of PEDF in normal postnatal vascularization of the retina and retinal neovascularization during OIR using PEDF-deficient (Serpinf1−/−) mice. High oxygen exposure during OIR results in down-regulation of pro-angiogenic factors and vessel obliteration, and halts further retinal vascular development [84]. When animals are returned to room air, the ischemic retina promotes excessive production of angiogenic factors and subsequent abnormal new blood vessel growth. We showed that the primary retinal vasculature developed at a faster rate in Serpinf1−/− mice. In addition, increased retinal microvessel density is reported in Serpinf1−/− mice at 3 weeks of age [84]. PEDF deficiency was also associated with more severe hyperoxia-mediated vessel obliteration during OIR with a significant effect on retinal neovascularization [84].

We also examined the impact of PEDF deficiency on CNV in a mouse model of laser-induced CNV. Our results showed no significant differences in the degree of CNV observed in Serpinf1−/− mice compared with Serpinf1 +/+ mice (Figure 4). Zhang and co-workers reported PEDF acts as a protective factor for retinal EC tight junctions [85]. They showed that the intravitreal injection of PEDF reduced retinal vascular permeability in rats with OIR and diabetes. In addition, overexpression of PEDF resulted in the dramatic suppression of retinal neovascularization during OIR [86]. Similarly, the intravitreal injection of adeno-associated virus encoding PEDF significantly inhibited retinal neovascularization during OIR and CNV during laser-induced CNV [87]. Thus, exogenously administrated PEDF has a dramatic anti-angiogenic activity and may have therapeutic potential for the inhibition of neovascularization.

PEDF deficiency minimally affects CNV

Figure 4
PEDF deficiency minimally affects CNV

(A) Serpinf1+/+ and Serpinf1−/− mice (6 weeks of age; female) were subjected to laser-induced photocoagulation. The area of neovascularization was assessed as previously described [183]. (B) The quantitative assessment of data. Please note there is no significant difference in areas of neovascularization in Serpinf1−/− mice compared with Serpinf1+/+ mice (P > 0.05; n=20 eyes); bar=50 μm.

Figure 4
PEDF deficiency minimally affects CNV

(A) Serpinf1+/+ and Serpinf1−/− mice (6 weeks of age; female) were subjected to laser-induced photocoagulation. The area of neovascularization was assessed as previously described [183]. (B) The quantitative assessment of data. Please note there is no significant difference in areas of neovascularization in Serpinf1−/− mice compared with Serpinf1+/+ mice (P > 0.05; n=20 eyes); bar=50 μm.

PEDF also plays an important neuroprotective role, and promotes the survival of rod photoreceptor cells under degenerative conditions. In vivo studies have indicated that PEDF treatment can drastically delay the progression of photoreceptor degeneration in rodents with retinal degeneration mutations [81,82,88]. Changes in and loss of photoreceptors are also reported during AMD, specifically in patients with geographic atrophy [89,90]. This may suggest a potential link between PEDF loss and photoreceptor degeneration during AMD development. However, we did not observe any sign of photoreceptor degeneration in PEDF-deficient mice up to a year of age (our unpublished data). The neuroprotective effect of PEDF is also reported by others [88,91,92]. Administration of exogenous PEDF decreases motor neuron death and protects the survival of neurons from atrophy in neonatal mice exposed to the sciatic nerve section [93]. However, we have observed a subtle, but not significant, increase in degenerative effect of PEDF deficiency on retinal ganglion cells (Figure 5). Thus, the lack of PEDF minimally affected the degeneration of retinal ganglion cells in an optic nerve crush model. Therefore, the impact of endogenous PEDF deficiency may be compensated by other developmental changes minimizing its effect on retinal neurovascular development and function.

PEDF deficiency does not exacerbate loss of retinal ganglion cells in response to nerve crush

Figure 5
PEDF deficiency does not exacerbate loss of retinal ganglion cells in response to nerve crush

Serpinf1 +/+ and Serpinf1−/− mice (8 weeks of age; male and female) were subjected to the nerve crush procedure (crush) or a procedure without crush (control) as described previously [184,185]. Animals were killed 2 weeks later and retinal flat mounts were evaluated for the number of brain-specific homeobox/POU domain protein 3A (BRN3A) positive cells per 100 μm2 [186]. (A) Representative images of retinal flatmounts stained with the BRN3A antibody. (B) The mean number of BRN3A positive cells per 100 μm2. Please note the dramatic decrease in cell number following nerve crush in Serpinf1+/+ and Serpinf1−/− mice. The differences between Serpinf1+/+ and Serpinf1−/− mice were not significant (P > 0.05; n=8). (C) The mean percentage of cells remaining, relative to control. There was no significant difference in percentage of cells remaining in Serpinf1+/+ compared with Serpinf1−/− mice (P > 0.05; n=8).

Figure 5
PEDF deficiency does not exacerbate loss of retinal ganglion cells in response to nerve crush

Serpinf1 +/+ and Serpinf1−/− mice (8 weeks of age; male and female) were subjected to the nerve crush procedure (crush) or a procedure without crush (control) as described previously [184,185]. Animals were killed 2 weeks later and retinal flat mounts were evaluated for the number of brain-specific homeobox/POU domain protein 3A (BRN3A) positive cells per 100 μm2 [186]. (A) Representative images of retinal flatmounts stained with the BRN3A antibody. (B) The mean number of BRN3A positive cells per 100 μm2. Please note the dramatic decrease in cell number following nerve crush in Serpinf1+/+ and Serpinf1−/− mice. The differences between Serpinf1+/+ and Serpinf1−/− mice were not significant (P > 0.05; n=8). (C) The mean percentage of cells remaining, relative to control. There was no significant difference in percentage of cells remaining in Serpinf1+/+ compared with Serpinf1−/− mice (P > 0.05; n=8).

Cell autonomous function of PEDF

PEDF was first identified as a secreted protein in a conditioned medium from RPE cells, which stimulated neuronal differentiation of Y79 retinoblastoma cells [94]. Soon after, PEDF was recognized as one of the major endogenous inhibitors of angiogenesis among other well-defined anti-angiogenic factors like TSP1, endostatin, and angiostatin [83]. PEDF conveys its anti-angiogenic activity via PEDF receptors mainly by targeting EC. PEDF has potent activity inhibiting the proliferation and migration of EC. PEDF as a trophic factor may also contribute to the attenuation of proliferation by decreasing the number of cells entering the S-phase of the cell cycle and increasing the number of cells entering G0 [88,95]. Dawson et al. [83] showed that PEDF inhibits EC migration toward different pro-angiogenic factors including VEGF, platelet-derived growth factor (PDGF), interleukin-8 (IL-8), acidic FGF, and lysophosphatidic acid. It is suggested that PEDF stimulates Fas ligand (FasL) expression and activates the FAS/FASL transduction cascade leading to EC death [96].

Studies from our laboratory demonstrated that PEDF differently affects the function of various cell types in the eye including EC and RPE cells (Table 2). PEDF also participates in RPE cell differentiation and maturation [97]. We recently showed that PEDF deficiency greatly affected RPE cell proliferation, migration, adhesion, oxidative state, and phagocytic activity with minimal effect on their basal rate of apoptosis [73]. The altered migration of RPE cells in the absence of PEDF supports its significant contribution in RPE cell degeneration and the pathogenesis of AMD. Similar to RPE cells, choroidal and retinal EC lacking PEDF demonstrated a decreased migratory phenotype (our unpublished data). This is consistent with the inability of Serpinf −/− choroidal and retinal EC to undergo capillary morphogenesis in Matrigel. Thus, expression of PEDF has a significant impact on the choroidal and retinal EC phenotype.

Table 2
Impact of PEDF expression on the function of various retinal cell types
Cell characteristicSerpinf1−/− RECSerpinf1−/− ChECSerpinf1−/− RPE
Morphology Normal Normal Abnormal (elongated cells) 
Specific markers Decreased PECAM-1 Decreased VE-CAD and PECAM-1 Decreased bestrophin expression 
Proliferation Increased Increased Increased 
Apoptosis basal
Challenged conditions 
No difference
Increased 
No difference
Increased 
No difference
Increased 
Migration Decreased Decreased Decreased 
Adhesion Less adherent to FN, VN, Col I, and Col IV Less adherent to FN, VN, Col I, and Col IV More adherent to FN and VN 
Junctional protein localization No significant impact on junctional localization No significant impact on junctional localization Loss of N-cadherin localization 
Oxidative stress Increased Increased Increased 
VEGF expression Decreased Increased Decreased 
Capillary morphogenesis Decreased Decreased – 
Phagocytosis – – Increased 
Cell characteristicSerpinf1−/− RECSerpinf1−/− ChECSerpinf1−/− RPE
Morphology Normal Normal Abnormal (elongated cells) 
Specific markers Decreased PECAM-1 Decreased VE-CAD and PECAM-1 Decreased bestrophin expression 
Proliferation Increased Increased Increased 
Apoptosis basal
Challenged conditions 
No difference
Increased 
No difference
Increased 
No difference
Increased 
Migration Decreased Decreased Decreased 
Adhesion Less adherent to FN, VN, Col I, and Col IV Less adherent to FN, VN, Col I, and Col IV More adherent to FN and VN 
Junctional protein localization No significant impact on junctional localization No significant impact on junctional localization Loss of N-cadherin localization 
Oxidative stress Increased Increased Increased 
VEGF expression Decreased Increased Decreased 
Capillary morphogenesis Decreased Decreased – 
Phagocytosis – – Increased 

The phagocytic function of RPE cells plays a critical role in the elimination of toxic metabolic waste as well as RPE cell survival [10,98,99]. We reported that PEDF deficiency results in enhanced accumulation of phagocytized materials inside RPE cells. This was associated with impaired proteasome activity of Serpinf1−/− RPE cells, including decreased caspase-like and trypsin-like activity [73]. Oxidative stress is identified as a crucial factor in the progression of AMD pathogenesis. Loss of RPE defensive mechanisms to cope with oxidative stress can advance retinal degeneration and/or ocular neovascularization [100,101]. PEDF inhibits apoptosis induced by oxidative stress in retinal pericytes preventing their dysfunction [102]. We showed elevated oxidative stress levels in Serpinf1−/− RPE cells [73] and choroidal and retinal EC (our unpublished data). Cao and co-workers showed that the pretreatment of retinal cultures with PEDF inhibited mitochondrial signal transduction and induced apoptosis when challenged with H2O2 [82]. PEDF can also activate the NF-κB signaling pathway resulting in induction of anti-apoptotic and/or neurotrophic factors involved in cell survival [88]. Thus, it appears that PEDF can modulate various signal transduction pathways, perhaps in a tissue-specific manner, through its interaction with different receptors on the cell surface.

PEDF ligand/receptor interactions are regulated by heparin and heparan sulfate that promote conformational changes allowing PEDF to bind to its receptor [103,104]. Two major PEDF receptors have been identified. ATGL (PEDFR) is an 80 kDa protein and is found on motor neurons with a high affinity for the 44-mer PEDF peptide, which is involved in neurotrophic activity. The laminin receptor (LR) is a 60 kDa protein that binds PEDF and is mainly localized on EC. LR has a high affinity for the 34-mer PEDF peptide involved in the inhibition of angiogenesis [105107]. Regulation of PEDF activity by its specific receptors suggests the use of these receptors and downstream events as a target for therapeutic activities. Retinal and choroidal EC, and RPE cells express both PEDF receptors, PEDFR and LR. However, the level of LR was (30–100-fold) higher than PEDFR in these cells (our unpublished data). RPE cells expressed higher levels of PEDF receptors compared with retinal and choroidal EC. Retinal EC also expressed other PEDF receptors including PLXDC2 and PLXDC1 at significantly lower levels (300–15,000-fold) than LR (our unpublished data). The development of antibodies or drugs targeting these receptors and their downstream effectors will provide new treatment modalities for diseases with a neovascular component including cancer and ocular vascular disease such as exudative AMD.

PEDF is also identified as a potent inhibitor of the canonical Wnt signaling pathway [108]. The importance of Wnt signaling in various biological processes including inflammation, angiogenesis, and fibrosis has been previously discussed [109,110]. Activation of Wnt signaling plays an important role in oxidative stress, inflammation, and neovascularization associated with diabetic retinopathy and exudative AMD [100,111]. The activation of Wnt signaling can be attenuated by the induced expression of PEDF or administration of exogenous PEDF, as well as other antagonists of this pathway with a significant impact on neovascularization. These observations further emphasize the important role of PEDF in the pathogenesis of AMD and its potential utilization as a target for the treatment of exudative AMD.

TSP1 as a potential therapeutic target for exudative AMD

We were the first to report the presence of TSP1 and its anti-angiogenic fragment in vitreous and aqueous humor samples of normal human, rat, mouse, and bovine eyes [13]. In addition, we showed a dramatic decrease in its level in samples from diabetic rats [13]. Since TSP1 is an endogenous inhibitor of angiogenesis with a potential significant clinical impact in the pathogenesis of many diseases with a neovascular component, many studies have explored its therapeutic applications providing us with a better understanding of the detailed mechanisms of TSP1 action. The results of these studies facilitated the design of therapeutic strategies to optimize TSP1 function and efficacy. Up-regulation of endogenous TSPs, synthetic TSP1 peptides, recombinant proteins derived from the angiogenic fragment of TSP1, or both, is used to evaluate TSP1 therapeutic effects [28,40,45,112]. Thus, it is important to know the specific function of the TSP1-derived peptides to gain insight into the biological, physiological, and pathological function of TSP1. TSP1 expression is required for adequate pruning and re-modeling of the retinal vasculature during the development and maintenance of the quiescent state of vasculature [31]. Therefore, alterations in TSP1 levels during AMD may significantly affect ocular vascular hemostasis.

The synthetic peptides from TSP1 have been extensively used in various tumor models in vitro and in vivo [40,113115]. Peptides derived from the properdin type1 and procollagen homology region of TSP1 attenuate CNV in mice [113]. Several investigators have suggested that TSP1 may also directly contribute to the suppression of cancer cell proliferation [33,40]. ABT-510 was developed to improve the pharmacodynamic and pharmacokinetic activity of the TSP1 type 1 repeat peptide [113]. ABT-510 is a non-apeptide analog of an anti-angiogenic sequence with a single D-amino-acid substitution that initiates 1,000-fold greater anti-angiogenic activity. TSP1 is reported as a protective factor in mice with inflammatory bowel disease (IBD) treated with ABT-510 [113]. ABT-510 affects angiogenesis mechanisms in a negative manner through competition with TSP1 for binding to EC, induction of FasL expression in EC, and inhibition of VEGF activity [113].

Synthetic manipulations have improved the serum half-life of ABT-510 (NAc SarGlyValDalloIleThrNvaIleArgProNHE) including substitution of the first Ile of GVITRIR with DIle or DalloIle, and the first Arg with norvaline, capping of the terminal amino- and carboxyl-residues [113]. Treatment with ABT-510 increases the apoptotic rate of bovine capillary EC, and human umbilical artery EC to inhibit capillary morphogenesis induced by VEGF, as well as inhibition of CNV induced by basic fibroblast growth factor (bFGF) [113,116]. Anti-angiogenic mimetic peptides from TSP1 have been extensively used in several pre-clinical tumor models [40,116119]. ABT-510 is a protective factor in mice with Lewis lung carcinoma, bladder, and prostate cancer [116,120,121]. ABT-898 is a more recent generation of a TSP1 mimic peptide, which successfully decreased the tumor size in mice with uveal melanoma [40]. Thus, TSP1 mimetic peptides are efficacious in attenuating angiogenesis and tumor growth.

Studies by our group and others support the strong mimicry activity of TSP1 peptides via normalizing angiogenesis with TSP1 deficiency due to loss or down-regulation. For example, the CNV area is approximately 8-fold larger in Thsp1−/− mice compared with wild-type mice [43]. This increase was abolished by the intravitreal administration of the TSP1 mimetic peptide ABT-898. ABT-898 is a TSP1 octapeptide, which has slower clearance, 10-fold greater potency, and no enzymatic cleavage [120]. Furthermore, systemic administration of ABT-898 effectively attenuated tumor growth in a mouse model of uveal melanoma. The average tumor volume in TSP1 peptide-treated mice decreased by approximately 10-fold compared with a control group [40].

Phase I trial results showed ABT-510 is well tolerated with biologically relevant plasma concentrations (>100 ng/ml lasting at least 3 h/d) and dose proportional, time-independent pharmacokinetics [121,123]. ABT-510 has been evaluated in Phase II clinical trials for the treatment of renal cell carcinoma, soft tissue sarcoma, lymphoma, non-small-cell lung cancer, and head and neck cancer [124]. The therapeutic benefits of ABT-510 were demonstrated in several malignancies [33]. However, the randomized ABT-510 treatment of patients with advanced renal cell carcinoma indicated limited clinical activity [116].

Combining ABT-510 with other standard treatments is feasible. ABT-510 combined with valporic acid (VPA, histone deacetylase inhibitor) effectively inhibited the growth of small neuroblastoma xenografts through the significant reduction of microvascular density, suggesting that this combined regimen may be an effective anti-angiogenic therapy for children with high-risk neuroblastoma [33]. The combination of ABT-510 with gemcitabine–cisplatin, 5-fluorouracil, and leucovorin (5-FU/LV) did not appear to increase toxicity and pharmacokinetic interactions [125]. Our studies indicated that TSP1 mimetic peptides (ABT-510 and ABT-898) attenuate CNV in pre-clinical models. TSP1 blocks angiogenesis through specific apoptosis mechanisms that do not duplicate that of VEGF antagonists. Thus, TSP1 mimetic peptides have the potential to act synergistically and to enhance activity of VEGF antagonists to mitigate CNV. Collectively, based on the promising pre-clinical data provided above, TSP1 peptides are a promising treatment to prevent or arrest CNV progression in patients with exudative AMD and await human trials.

PEDF as a potential therapeutic target for exudative AMD

The endogenous management of blood vessel growth is regulated through pro-angiogenic factors including the VEGF family and anti-angiogenesis factors including TSP1 and PEDF. PEDF is recognized as a major endogenous inhibitor of neovascularization. PEDF, a 50 kDa glycoprotein, is a member of the serpin superfamily with no serine protease inhibitor activity [76]. PEDF is a multifunctional protein that has a broad spectrum of activities including neurotrophic, neuroprotective, anti-inflammatory, anti-tumorigenic, anti-angiogenic, and anti-vasopermeability [79,83,126]. The inhibitory impact of PEDF on angiogenesis was demonstrated by the inhibition of VEGF and FGF activity, only on newly forming blood vessels without affecting pre-existing blood vessels. However, the molecular mechanisms that PEDF utilizes to convey its anti-angiogenesis activity are not very well understood. A recent study reported a direct interaction between PEDF and VEGF receptors that suggest a potential mechanism for the inhibition of angiogenesis [127]. The selective induction of apoptosis in EC of newly forming blood vessels, and its broad distribution and action in different cell types, make PEDF a suitable candidate for anti-angiogenesis therapy. Published PEDF patents have recommended the use of full-length PEDF, derived peptides, or PEDF gene delivery as anti-cancer drugs [128,129]. The therapeutic effects of PEDF in the prevention or treatment of melanoma and osteosarcoma cancers are shown in some patent applications [130,131].

Introducing exogenous PEDF to a neovascularized area results in the inhibition of both EC migration and proliferation through the induction of apoptosis of recruited EC [132134]. Re-expression of PEDF in the human esophageal squamous cell carcinoma that normally do not secrete endogenous PEDF, significantly inhibited their migration and proliferation and halted their growth by suppressing neovascularization [135]. Similarly, constitutive overexpression of PEDF decreased the size of ocular tumor metastasis associated with reduced microvascular density in pre-clinical models [136]. In addition, PEDF overexpression decreased migration and capillary morphogenesis of melanoma cells in vitro [136]. Thus, exogenous administration of PEDF is effective in attenuating angiogenesis and tumor growth.

PEDF is also efficacious in the attenuation of ocular neovascularization. Dawson et al. [83] showed that purified, as well as recombinant PEDF, attenuated corneal neovascularization in rats. In another study using a mouse model of ischemia-induced retinopathy, low doses of recombinant PEDF blocked retinal neovascularization without affecting the pre-existing blood vessels and retinal morphology [137]. The intravitreal injection of AdPEDF.11, an adenovirus encoding PEDF, showed significant inhibition of CNV that corresponded with induced apoptosis of EC within the neovascularized area [138]. AdPEDF.11D was tested in an open-label, dose escalation Phase I trial to identify the maximum tolerated dose (MTD) and assess safety and potential efficacy in patients with advanced exudative AMD [139]. The result of this study indicated that the intravitreal injection of AdPEDF.11D is a feasible approach for the treatment of ocular diseases, since no severe adverse effects in the patients were reported. However, further investigation to evaluate the efficacy of AdPEDF.11 in patients with exudative AMD is needed [140].

PEDF mimetic peptides derived from the N-terminal anti-angiogenic epitope showed potent anti-angiogenic activity and PEDF mimicry including apoptosis and major signaling pathways in models of tumor angiogenesis, wound healing, and CNV in mice. PEDF peptides have potent anti-angiogenic effects in orthotopics models of prostate and renal cancers [141,142]. PEDF and PEDF-derived peptide, 44mer, have inhibitory effects against hypoxia-induced apoptosis in cardiomyocytes [143]. Studies reported mimicry activity of PEDF 34 and PEDF 18 peptides could inhibit angiogenesis through cellular and molecular events characteristic of the anti-angiogenesis of PEDF [141,142,144]. In our preliminary studies, we have observed therapeutic efficacy of a PEDF18-derived peptide in a mouse CNV model (our unpublished data). Thus, for exudative AMD, faced with a lack of suitable options for lasting control over a progressive condition, along with adverse effects of current treatments on ocular function and systemic side effects, the use of endogenous biological agents provide great opportunity for new treatment modality [145147].

Endostatin

Endostatin is a 25 kDa protein derived from the C-terminal region of collagen XVIII, a heparin sulfate proteoglycan (HSPG) core protein [148,149]. It is a potent endogenous inhibitor of angiogenesis, which presents dual receptor antagonism resulting in anti-angiogenesis and pro-autophagy activity [149]. Endostatin was originally characterized by its inhibitory effect on EC and suppressive tumor-induced angiogenesis [21]. Endostatin conveys its biological activities through multiple interacting receptors. It can bind α5β1, and αvβ3/αvβ5 integrins and antagonize their activity on EC. Furthermore, direct interaction of endostatin with α5β1 integrin leads to induced autophagy in EC that enhances its anti-angiogenic activity [150]. Endostatin binds to cell surface HSPG glypican, VEGFR1 and VEGFR2, and fibronectin receptor α5β1 integrin [151154]. Endostatin inhibits VEGF-induced phosphorylation by binding directly to VEGFR2 [152]. The anti-angiogenic activity of endostatin was initially identified by its inhibitory impact on blood vessel formation in vivo and further confirmed by systemic administration of endostatin in tumor-bearing mice [21]. Endostatin utilizes broad mechanisms of action to exert its angiostatic activity on EC. The proposed mechanisms include inhibition of matrix metalloproteinase (MMP) activity, a facilitator of migration and invasion of EC and actin disassembly, inhibition of the FAK/Ras/p38-MAPK/ERK signaling cascade via binding to α5β1-integrin, suppression of HIF-1α/VEGFA, and Wnt signaling [155161].

Altered endostatin levels are associated with different diseases including cancers, vascular, and neurological diseases [21,148,162,163]. A decreased level of endostatin occurs in the Bruch's membrane and/or choriocapillaris during AMD and retinopathies [5]. The involvement of endostatin as an endogenous inhibitor of angiogenesis in the pathology of various diseases suggests its potential clinical applications through the development of novel therapeutics. Currently, clinical endostatin use in the US is in a Phase I trial in patients with advanced exudative AMD [164]. Several research groups suggest that the clinical applications of endostatin in a form of short peptides alone or in combination with other therapy regimens will be a great therapeutic option for the treatment of various diseases with a neovascular component [148].

Angiostatin

Angiostatin is an internal fragment of plasminogen and includes four kringle domains (k1–4) [165]. The kringle structure exists in various proteins and was originally described by a triple loop structure linked by three pairs of disulfide bonds [166]. These kringle domains show an anti-angiogenic effect only when cleaved indicating proteolysis plays an important role in the angiogenesis balance by the down-regulation of angiogenesis [165]. Angiostatin inhibits EC proliferation and EC capillary cell growth [167]. The suppressive impact of angiostatin on cell growth is mostly restricted to EC lineage [168]. Angiostatin has an inhibitory impact on metastatic tumor growth mainly through the blocking of angiogenesis [167]. Studies have reported that different proteases produced by tumor cells can cleave plasminogen to release angiostatin [165]. Several mechanisms of action are proposed as potential pathways for the anti-angiogenesis activity of angiostatin including the suppression of EC migration and proliferation via binding to ATPase and/or prevention of the G2/M transition, induced apoptosis of EC, and down-regulation of VEGF expression [152,167,169171]. Angiostatin has anti-tumor activity in different animal models, and has been clinically evaluated in Phase I and II clinical trials in patients with progressive metastatic cancer and non-small-cell lung cancer [172]. A decreased level of angiostatin in the Bruch's membrane and/or the choriocapillaris complex during AMD has been reported [5]. Currently, angiostatin is tested in an open-label, dose escalation Phase I trial to identify the MTD and assess safety and potential efficacy in patients with advanced exudative AMD [164].

Conclusions and future directions

AMD is a major cause of visual impairment in the elderly population worldwide. Despite the high prevalence of AMD, its etiology remains largely unknown. The increased production of VEGF is identified as an essential factor in the development and progression of AMD, and CNV. The intravitreal injection of VEGF antagonists is effective in delaying CNV and the pathological progression of the disease. However, safety concerns are emerging regarding the long-term blockade of VEGF, and loss of ocular integrity due to multiple intravitreal injections and systemic complications. Other major complications associated with the chronic use of anti-VEGF include intraocular inflammation, rhegmatogenous retinal detachment, intraocular pressure elevation, ocular hemorrhage, and vascular degeneration [173179]. In addition, there are several reports indicating RPE tears associated with intravitreal anti-VEGF delivery in patients with exudative AMD [180182]. Thus, safe and effective alternative treatments are needed. PEDF and TSP1 are major endogenous inhibitors of ocular angiogenesis, which are deficient in vascular retinopathies including human AMD. Small peptides derived from their active fragments are potently anti-angiogenic in pre-clinical models of ocular diseases and tumors, and restore a normal PEDF and TSP1 status. Our preliminary studies indicate that these peptides attenuate CNV in pre-clinical models of exudative AMD [40,41].

PEDF and TSP1 block angiogenesis through specific apoptosis mechanisms, which are different from the mechanisms of VEGF antagonists. Thus, PEDF and TSP1 mimetic peptides may act synergistically and enhance the effects of VEGF antagonists. Understanding the role of PEDF and TSP1, and their signaling pathways in ocular vascular homeostasis is instrumental in the development of new modalities for the treatment of exudative AMD. In addition, evaluation of the potential therapeutic action of TSP1and PEDF peptides for their mimicry activities of these natural endogenous inhibitors will provide further justification for the treatment of CNV. Further exploration into combination therapy of VEGF antagonists and PEDF and/or TSP1 peptides will allow the assessment of their synergistic effect on the inhibition of CNV. These approaches will provide an opportunity to identify potential new therapeutic targets for AMD treatment as well as identifying a single, most promising clinical candidate for human clinical trials.

We thank Dr Jack Lawler for providing the TSP1 null mice; Dr Kurt Hankinson for providing the TSP2 null and TSP2-GFP reporter mice; and Dr Stanley Wiegand for providing PEDF null mice.

Funding

This work was supported by an unrestricted award from Research to Prevent Blindness to the Department of Ophthalmology and Visual Sciences and Retina Research Foundation, and NIH grants P30 EY016665, P30 CA014520, EPA 83573701, EY022883 and EY012223. CMS is supported by the RRF/Daniel M. Albert Chair.

Competing interests

The authors declare that there are no competing interests associated with the manuscript.

Abbreviations

     
  • AMD

    age-related macular degeneration

  •  
  • BRN3A

    brain-specific homeobox/POU domain protein 3A

  •  
  • ChEC

    choroidal endothelial cells

  •  
  • CK2

    casein kinase

  •  
  • CNV

    choroidal neovascularization

  •  
  • EC

    endothelial cells

  •  
  • FGF

    fibroblast growth factor

  •  
  • HSPG

    heparin sulfate proteoglycan

  •  
  • IL-8

    interleukin-8

  •  
  • MTD

    maximum tolerated dose

  •  
  • NO

    nitric oxide

  •  
  • OIR

    oxygen-induced ischemic retinopathy

  •  
  • PEDF

    pigment epithelium-derived factor

  •  
  • PKA

    protein kinase A

  •  
  • RPE

    retinal pigmented epithelium

  •  
  • TSP1

    thrombospondin-1

  •  
  • VEGF

    vascular endothelial growth factor

References

References
1
Lally
,
D.R.
,
Gerstenblith
,
A.T.
and
Regillo
,
C.D.
(
2012
)
Preferred therapies for neovascular age-related macular degeneration
.
Curr. Opin. Ophthalmol.
23
,
182
188
[PubMed]
2
Ambati
,
J.
,
Ambati
,
B.K.
,
Yoo
,
S.H.
,
Ianchulev
,
S.
and
Adamis
,
A.P.
(
2003
)
Age-Related Macular Degeneration: Etiology, Pathogenesis, and Therapeutic Strategies
.
Surv. Ophthalmol.
48
,
257
293
[PubMed]
3
Hua
,
J.
,
Gross
,
N.
,
Schulze
,
B.
,
Michaelis
,
U.
,
Bohnenkamp
,
H.
,
Guenzi
,
E.
et al (
2012
)
In vivo imaging of choroidal angiogenesis using fluorescence-labeled cationic liposomes
.
Mol. Vis.
18
,
1045
1054
[PubMed]
4
Jung
,
J.J.
,
Chen
,
C.Y.
,
Mrejen
,
S.
,
Gallego-Pinazo
,
R.
,
Xu
,
L.
,
Marsiglia
,
M.
et al (
2014
)
The Incidence of Neovascular Subtypes in Newly Diagnosed Neovascular Age-Related Macular Degeneration
.
Am. J. Ophthalmol.
158
,
769
779.e762
[PubMed]
5
Bhutto
,
I.
and
Lutty
,
G.
(
2012
)
Understanding age-related macular degeneration (AMD): relationships between the photoreceptor/retinal pigment epithelium/Bruch's membrane/choriocapillaris complex
.
Mol. Aspects Med.
33
,
295
317
[PubMed]
6
Green
,
W.R.
(
1999
)
Histopathology of age-related macular degeneration
.
Mol. Vis.
5
,
27
[PubMed]
7
Green
,
W.R.
and
Enger
,
C.
(
1993
)
Age-related macular degeneration histopathologic studies. The 1992 Lorenz E. Zimmerman Lecture
.
Ophthalmology
100
,
1519
1535
[PubMed]
8
Campochiaro
,
P.A.
,
Shah
,
S.M.
,
Hafiz
,
G.
,
Heier
,
J.S.
,
Lit
,
E.S.
,
Zimmer-Galler
,
I.
et al (
2010
)
Topical Mecamylamine for Diabetic Macular Edema
.
Am. J. Ophthalmol.
149
,
839
851
[PubMed]
9
Duh
,
E.J.
,
Yang
,
H.S.
,
Haller
,
J.A.
,
De Juan
,
E.
,
Humayun
,
M.S.
,
Gehlbach
,
P.
et al (
2004
)
Vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor: Implications for ocular angiogenesis
.
Am. J. Ophthalmol.
137
,
668
674
[PubMed]
10
Sparrow
,
J.R.
,
Hicks
,
D.
and
Hamel
,
C.P.
(
2010
)
The retinal pigment epithelium in health and disease
.
Curr. Mol. Med.
10
,
802
823
[PubMed]
11
Wang
,
S.
,
Gottlieb
,
J.L.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2009
)
Modulation of thrombospondin 1 and pigment epithelium-derived factor levels in vitreous fluid of patients with diabetes
.
Arch. Ophthalmol.
127
,
507
513
[PubMed]
12
Uno
,
K.
,
Bhutto
,
I.A.
,
McLeod
,
D.S.
,
Merges
,
C.
and
Lutty
,
G.A.
(
2006
)
Impaired expression of thrombospondin-1 in eyes with age related macular degeneration
.
Br. J. Ophthalmol.
90
,
48
54
[PubMed]
13
Sheibani
,
N.
,
Sorenson
,
C.M.
,
Cornelius
,
L.A.
and
Frazier
,
W.A.
(
2000
)
Thrombospondin-1, a natural inhibitor of angiogenesis, is present in vitreous and aqueous humor and is modulated by hyperglycemia
.
Biochem. Biophys. Res. Commun.
267
,
257
261
[PubMed]
14
Karakousis
,
P.C.
,
John
,
S.K.
,
Behling
,
K.C.
,
Surace
,
E.M.
,
Smith
,
J.E.
,
Hendrickson
,
A.
et al (
2001
)
Localization of pigment epithelium derived factor (PEDF) in developing and adult human ocular tissues
.
Mol. Vis.
7
,
154
163
[PubMed]
15
Yamagishi
,
S.I.
,
Amano
,
S.
,
Inagaki
,
Y.
,
Okamoto
,
T.
,
Takeuchi
,
M.
and
Inoue
,
H.
(
2003
)
Pigment epithelium-derived factor inhibits leptin-induced angiogenesis by suppressing vascular endothelial growth factor gene expression through anti-oxidative properties
.
Microvasc. Res.
65
,
186
190
[PubMed]
16
Ma
,
X.Y.
,
Pan
,
L.
,
Jin
,
X.
,
Dai
,
X.D.
,
Li
,
H.R.
,
Wen
,
B.
et al (
2012
)
Microphthalmia-associated transcription factor acts through PEDF to regulate RPE cell migration
.
Exp. Cell Res.
318
,
251
261
[PubMed]
17
Machalińska
,
A.
,
Safranow
,
K.
,
Mozolewska-Piotrowska
,
K.
,
Dziedziejko
,
V.
and
Karczewicz
,
D.
(
2012
)
PEDF and VEGF plasma level alterations in patients with dry form of age-related degeneration–a possible link to the development of the disease
.
Klin. Oczna.
114
,
115
120
18
Folkman
,
J.
and
Klagsbrun
,
M.
(
1987
)
Angiogenic factors
.
Science
235
,
442
447
19
Gao
,
G.
,
Li
,
Y.
,
Zhang
,
D.
,
Gee
,
S.
,
Crosson
,
C.
and
Ma
,
J.
(
2001
)
Unbalanced expression of VEGF and PEDF in ischemia-induced retinal neovascularization
.
FEBS Lett.
489
,
270
276
20
Carmeliet
,
P.
and
Jain
,
R.K.
(
2000
)
Angiogenesis in cancer and other diseases
.
Nature
407
,
249
257
21
O'Reilly
,
M.S.
,
Boehm
,
T.
,
Shing
,
Y.
,
Fukai
,
N.
,
Vasios
,
G.
,
Lane
,
W.S.
et al (
1997
)
Endostatin: an endogenous inhibitor of angiogenesis and tumor growth
.
Cell.
88
,
277
285
22
Carron
,
J.A.
,
Hiscott
,
P.
,
Hagan
,
S.
,
Sheridan
,
C.M.
,
Magee
,
R.
and
Gallagher
,
J.A.
(
2000
)
Cultured human retinal pigment epithelial cells differentially express thrombospondin-1, -2, -3, and -4
.
Int. J. Biochem. Cell Biol.
32
,
1137
1142
23
Miyajima-Uchida
,
H.
,
Hayashi
,
H.
,
Beppu
,
R.
,
Kuroki
,
M.
,
Fukami
,
M.
,
Arakawa
,
F.
et al (
2000
)
Production and accumulation of thrombospondin-1 in human retinal pigment epithelial cells
.
Invest. Ophthalmol. Vis. Sci.
41
,
561
567
24
Baenziger
,
N.L.
,
Brodie
,
G.N.
and
Majerus
,
P.W.
(
1971
)
A thrombin-sensitive protein of human platelet membranes
.
Proc. Natl. Acad. Sci. U.S.A.
68
,
240
243
25
Adams
,
J.C.
(
2001
)
Thrombospondins: multifunctional regulators of cell interactions
.
Annu. Rev. Cell Dev. Biol.
17
,
25
51
26
Vailhe
,
B.
and
Feige
,
J.J.
(
2003
)
Thrombospondins as anti-angiogenic therapeutic agents
.
Curr. Pharm. Des.
9
,
583
588
27
Bornstein
,
P.
(
1992
)
Thrombospondins: structure and regulation of expression
.
FASEB J.
6
,
3290
3299
28
Armstrong
,
L.C.
and
Bornstein
,
P.
(
2003
)
Thrombospondins 1 and 2 function as inhibitors of angiogenesis
.
Matrix Biol.
22
,
63
71
29
Tolsma
,
S.S.
,
Volpert
,
O.V.
,
Good
,
D.J.
,
Frazier
,
W.A.
,
Polverini
,
P.J.
and
Bouck
,
N.
(
1993
)
Peptides derived from two separate domains of the matrix protein thrombospondin-1 have anti-angiogenic activity
.
J. Cell Biol.
122
,
497
511
30
Sheibani
,
N.
and
Frazier
,
W.A.
(
1999
)
Thrombospondin-1, PECAM-1, and regulation of angiogenesis
.
Histol. Histopathol.
14
,
285
294
31
Sheibani
,
N.
,
Kondo
,
S.
,
DiMaio
,
A.T.
,
Sorenson
,
C.M.
,
Scheef
,
E.
and
Tang
,
Y.A.
(
2007
)
Thrombospondin-1 Signal Transduction and Retinal Vascular Homeostasis
.
Signal Transduction in the Retina
CRC Press
,
329
345
32
Miyata
,
Y.
and
Sakai
,
H.
(
2013
)
Thrombospondin-1 in urological cancer: pathological role, clinical significance, and therapeutic prospects
.
Int. J. Mol. Sci.
14
,
12249
12272
33
Yang
,
Q.
,
Tian
,
Y.
,
Liu
,
S.
,
Zeine
,
R.
,
Chlenski
,
A.
,
Salwen
,
H.R.
et al (
2007
)
Thrombospondin-1 peptide ABT-510 combined with valproic acid is an effective antiangiogenesis strategy in neuroblastoma
.
Cancer Res.
67
,
1716
1724
34
Mochizuki
,
M.
,
Sugita
,
S.
and
Kamoi
,
K.
(
2013
)
Immunological homeostasis of the eye
.
Prog. Retin. Eye Res.
33
,
10
27
35
Zamiri
,
P.
,
Masli
,
S.
,
Kitaichi
,
N.
,
Taylor
,
A.W.
and
Streilein
,
J.W.
(
2005
)
Thrombospondin plays a vital role in the immune privilege of the eye
.
Invest. Ophthalmol. Vis. Sci.
46
,
908
919
36
Mochizuki
,
M.
(
2010
)
Regional immunity of the eye
.
Acta Ophthalmol.
88
,
292
299
37
Agah
,
A.
,
Kyriakides
,
T.R.
,
Lawler
,
J.
and
Bornstein
,
P.
(
2002
)
The lack of thrombospondin-1 (TSP1) dictates the course of wound healing in double-TSP1/TSP2-null mice
.
Am. J. Pathol.
161
,
831
839
38
Kisselev
,
O.G.
,
Fliesler
,
S.J.
,
Sheibani
,
N.
,
Kondo
,
S.
,
DiMaio
,
T.A.
,
Sorenson
,
C.M.
et al (
2007
)
Thrombospondin-1 Signal Transduction and Retinal Vascular Homeostasis
.
Signal Transduction in the Retina
CRC Press
,
329
345
39
Wang
,
S.
,
Wu
,
Z.
,
Sorenson
,
C.M.
,
Lawler
,
J.
and
Sheibani
,
N.
(
2003
)
Thrombospondin-1-deficient mice exhibit increased vascular density during retinal vascular development and are less sensitive to hyperoxia-mediated vessel obliteration
.
Dev. Dyn.
228
,
630
642
40
Wang
,
S.
,
Neekhra
,
A.
,
Albert
,
D.M.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2012
)
Suppression of thrombospondin-1 expression during uveal melanoma progression and its potential therapeutic utility
.
Arch. Ophthalmol.
130
,
336
341
41
Wu
,
Z.
,
Wang
,
S.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2006
)
Attenuation of retinal vascular development and neovascularization in transgenic mice over-expressing thrombospondin-1 in the lens
.
Dev. Dyn.
235
,
1908
1920
42
Evans
,
J.
and
Wormald
,
R.
(
1996
)
Is the incidence of registrable age-related macular degeneration increasing?
.
Br. J. Ophthalmol.
80
,
9
14
43
Wang
,
S.J.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2012
)
Lack of Thrombospondin 1 and Exacerbation of Choroidal Neovascularization
.
Arch. Ophthalmol.
130
,
615
620
44
Lawler
,
J.
(
2002
)
Thrombospondin-1 as an endogenous inhibitor of angiogenesis and tumor growth
.
J. Cell Mol. Med.
6
,
1
12
45
Zhang
,
X.
and
Lawler
,
J.
(
2007
)
Thrombospondin-based antiangiogenic therapy
.
Microvasc. Res.
74
,
90
99
46
Lopez-Dee
,
Z.
,
Pidcock
,
K.
and
Gutierrez
,
L.S.
(
2011
)
Thrombospondin-1: multiple paths to inflammation
.
Mediators Inflamm
2011
,
296069
47
Bhutto
,
I.A.
,
Uno
,
K.
,
Merges
,
C.
,
Zhang
,
L.
,
McLeod
,
D.S.
and
Lutty
,
G.A.
(
2008
)
Reduction of endogenous angiogenesis inhibitors in Bruch's membrane of the submacular region in eyes with age-related macular degeneration
.
Arch. Ophthalmol.
126
,
670
678
48
Sun
,
J.
,
Hopkins
,
B.D.
,
Tsujikawa
,
K.
,
Perruzzi
,
C.
,
Adini
,
I.
,
Swerlick
,
R.
et al (
2009
)
Thrombospondin-1 modulates VEGF-A-mediated Akt signaling and capillary survival in the developing retina
.
Am. J. Physiol. Heart Circ. Physiol.
296
,
H1344
H1351
49
Wang
,
Y.
,
Wang
,
S.
and
Sheibani
,
N.
(
2006
)
Enhanced proangiogenic signaling in thrombospondin-1-deficient retinal endothelial cells
.
Microvasc. Res.
71
,
143
151
50
Fei
,
P.
,
Zaitoun
,
I.
,
Farnoodian
,
M.
,
Fisk
,
D.L.
,
Wang
,
S.
,
Sorenson
,
C.M.
et al (
2014
)
Expression of thrombospondin-1 modulates the angioinflammatory phenotype of choroidal endothelial cells
.
PLoS One
9
,
e116423
51
Dorey
,
C.K.
,
Wu
,
G.
,
Ebenstein
,
D.
,
Garsd
,
A.
and
Weiter
,
J.J.
(
1989
)
Cell loss in the aging retina. Relationship to lipofuscin accumulation and macular degeneration
.
Invest. Ophthalmol. Vis. Sci.
30
,
1691
1699
[PubMed]
52
Harman
,
A.M.
,
Fleming
,
P.A.
,
Hoskins
,
R.V.
and
Moore
,
S.R.
(
1997
)
Development and aging of cell topography in the human retinal pigment epithelium
.
Invest. Ophthalmol. Vis. Sci.
38
,
2016
2026
[PubMed]
53
Del Priore
,
L.V.
,
Kuo
,
Y.H.
and
Tezel
,
T.H.
(
2002
)
Age-related changes in human RPE cell density and apoptosis proportion in situ
.
Invest. Ophthalmol. Vis. Sci.
43
,
3312
3318
[PubMed]
54
Pan
,
C.K.
,
Heilweil
,
G.
,
Lanza
,
R.
and
Schwartz
,
S.D.
(
2013
)
Embryonic stem cells as a treatment for macular degeneration
.
Expert Opin. Biol. Ther.
13
,
1125
1133
[PubMed]
55
Kaur
,
S.
,
Martin-Manso
,
G.
,
Pendrak
,
M.L.
,
Garfield
,
S.H.
,
Isenberg
,
J.S.
and
Roberts
,
D.D.
(
2010
)
Thrombospondin-1 inhibits VEGF receptor-2 signaling by disrupting its association with CD47
.
J. Biol. Chem.
285
,
38923
38932
[PubMed]
56
Brown
,
E.J.
and
Frazier
,
W.A.
(
2001
)
Integrin-associated protein (CD47) and its ligands
.
Trends Cell Biol
11
,
130
135
[PubMed]
57
Febbraio
,
M.
,
Hajjar
,
D.P.
and
Silverstein
,
R.L.
(
2001
)
CD36: a class B scavenger receptor involved in angiogenesis, atherosclerosis, inflammation, and lipid metabolism
.
J. Clin. Investig.
108
,
785
791
58
Clezardin
,
P.
,
Frappart
,
L.
,
Clerget
,
M.
,
Pechoux
,
C.
and
Delmas
,
P.D.
(
1993
)
Expression of thrombospondin (TSP1) and its receptors (CD36 and CD51) in normal, hyperplastic, and neoplastic human breast
.
Cancer Res.
53
,
1421
1430
[PubMed]
59
Moncada
,
S.
,
Palmer
,
R.M.
and
Higgs
,
E.A.
(
1991
)
Nitric oxide: physiology, pathophysiology, and pharmacology
.
Pharmacol. Rev.
43
,
109
142
[PubMed]
60
Ando
,
A.
,
Yang
,
A.
,
Mori
,
K.
,
Yamada
,
H.
,
Yamada
,
E.
,
Takahashi
,
K.
et al (
2002
)
Nitric oxide is proangiogenic in the retina and choroid
.
J. Cell. Physiol.
191
,
116
124
[PubMed]
61
Ando
,
A.
,
Yang
,
A.
,
Nambu
,
H.
and
Campochiaro
,
P.A.
(
2002
)
Blockade of nitric-oxide synthase reduces choroidal neovascularization
.
Mol. Pharmacol.
62
,
539
544
[PubMed]
62
Kibbe
,
M.
,
Billiar
,
T.
and
Tzeng
,
E.
(
1999
)
Inducible nitric oxide synthase and vascular injury
.
Cardiovasc. Res.
43
,
650
657
[PubMed]
63
Leal
,
E.C.
,
Manivannan
,
A.
,
Hosoya
,
K.
,
Terasaki
,
T.
,
Cunha-Vaz
,
J.
,
Ambrosio
,
A.F.
et al (
2007
)
Inducible nitric oxide synthase isoform is a key mediator of leukostasis and blood-retinal barrier breakdown in diabetic retinopathy
.
Invest. Ophthalmol. Vis. Sci.
48
,
5257
5265
[PubMed]
64
Nagareddy
,
P.R.
,
Xia
,
Z.
,
McNeill
,
J.H.
and
MacLeod
,
K.M.
(
2005
)
Increased expression of iNOS is associated with endothelial dysfunction and impaired pressor responsiveness in streptozotocin-induced diabetes
.
Am. J. Physiol. Heart Circ. Physiol.
289
,
H2144
H2152
[PubMed]
65
Suzuma
,
K.
,
Takagi
,
H.
,
Otani
,
A.
,
Oh
,
H.
and
Honda
,
Y.
(
1999
)
Expression of thrombospondin-1 in ischemia-induced retinal neovascularization
.
Am. J. Pathol.
154
,
343
354
[PubMed]
66
Scheef
,
E.
,
Wang
,
S.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2005
)
Isolation and characterization of murine retinal astrocytes
.
Mol. Vis.
11
,
613
624
[PubMed]
67
Shin
,
E.S.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2014
)
PEDF expression regulates the proangiogenic and proinflammatory phenotype of the lung endothelium
.
Am. J. Physiol. Lung Cell Mol. Physiol.
306
,
L620
634
[PubMed]
68
Tang
,
Y.
,
Scheef
,
E.A.
,
Gurel
,
Z.
,
Sorenson
,
C.M.
,
Jefcoate
,
C.R.
and
Sheibani
,
N.
(
2010
)
CYP1B1 and endothelial nitric oxide synthase combine to sustain proangiogenic functions of endothelial cells under hyperoxic stress
.
Am. J. Physio. Cell Physiol.
298
,
C665
C678
69
Palenski
,
T.L.
,
Gurel
,
Z.
,
Sorenson
,
C.M.
,
Hankenson
,
K.D.
and
Sheibani
,
N.
(
2013
)
Cyp1B1 expression promotes angiogenesis by suppressing NF-κB activity
.
Am. J. Physiol. Cell Physiol.
305
,
C1170
C1184
[PubMed]
70
Tang
,
Y.
,
Scheef
,
E.A.
,
Wang
,
S.
,
Sorenson
,
C.M.
,
Marcus
,
C.B.
,
Jefcoate
,
C.R.
et al (
2009
)
CYP1B1 expression promotes the proangiogenic phenotype of endothelium through decreased intracellular oxidative stress and thrombospondin-2 expression
.
Blood
113
,
744
754
[PubMed]
71
Scheef
,
E.A.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2009
)
Attenuation of proliferation and migration of retinal pericytes in the absence of thrombospondin-1
.
Am. J. Physiol. Cell Physiol.
296
,
C724
C734
[PubMed]
72
Fei
,
P.
,
Palenski
,
T.L.
,
Wang
,
S.
,
Gurel
,
Z.
,
Hankenson
,
K.D.
,
Sorenson
,
C.M.
et al (
2015
)
Thrombospondin-2 Expression During Retinal Vascular Development and Neovascularization
.
J. Ocu. Pharmacol. Ther.
31
,
429
444
73
Farnoodian
,
M.
,
Kinter
,
J.B.
,
Aghdam
,
S.Y.
,
Zaitoun
,
I.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2015
)
Expression of pigment epithelium-derived factor and thrombospondin-1 regulate proliferation and migration of retinal pigment epithelial cells
.
Physiol. Rep.
3
,
e12266
[PubMed]
74
Isenberg
,
J.S.
,
Annis
,
D.S.
,
Pendrak
,
M.L.
,
Ptaszynska
,
M.
,
Frazier
,
W.A.
,
Mosher
,
D.F.
et al (
2009
)
Differential interactions of thrombospondin-1, -2, and -4 with CD47 and effects on cGMP signaling and ischemic injury responses
.
J. Biol. Chem.
284
,
1116
1125
[PubMed]
75
Becerra
,
S.P.
,
Sagasti
,
A.
,
Spinella
,
P.
and
Notario
,
V.
(
1995
)
Pigment Epithelium-derived Factor Behaves Like a noninhibitory serpin neurotrophic activity does not require the serpin reactive loop
.
J. Biol. Chem.
270
,
25992
25999
[PubMed]
76
Becerra
,
S.P.
(
2006
)
Focus on molecules: pigment epithelium-derived factor (PEDF)
.
Exp. Eye Res.
82
,
739
740
[PubMed]
77
He
,
X.
,
Cheng
,
R.
,
Benyajati
,
S.
and
Ma
,
J.-x.
(
2015
)
PEDF and its roles in physiological and pathological conditions: implication in diabetic and hypoxia-induced angiogenic diseases
.
Clin. Sci.
128
,
805
823
[PubMed]
78
Maik-Rachline
,
G.
and
Seger
,
R.
(
2006
)
Variable phosphorylation states of pigment-epithelium–derived factor differentially regulate its function
.
Blood
107
,
2745
2752
[PubMed]
79
Bouck
,
N.
(
2002
)
PEDF: anti-angiogenic guardian of ocular function
.
Trends Mol. Med.
8
,
330
334
[PubMed]
80
Volpert
,
K.N.
,
Tombran-Tink
,
J.
,
Barnstable
,
C.
and
Layer
,
P.G.
(
2009
)
PEDF and GDNF are key regulators of photoreceptor development and retinal neurogenesis in reaggregates from chick embryonic retina
.
J. Ocul. Biol. Dis. Inform.
2
,
1
11
81
Cayouette
,
M.
,
Smith
,
S.B.
,
Becerra
,
S.P.
and
Gravel
,
C.
(
1999
)
Pigment epithelium-derived factor delays the death of photoreceptors in mouse models of inherited retinal degenerations
.
Neurobiol. Dis.
6
,
523
532
[PubMed]
82
Cao
,
W.
,
Tombran-Tink
,
J.
,
Chen
,
W.
,
Mrazek
,
D.
,
Elias
,
R.
and
McGinnis
,
J.
(
1999
)
Pigment epithelium-derived factor protects cultured retinal neurons against hydrogen peroxide-induced cell death
.
J. Neurosci. Res.
57
,
789
800
[PubMed]
83
Dawson
,
D.
,
Volpert
,
O.
,
Gillis
,
P.
,
Crawford
,
S.
,
Xu
,
H.-J.
,
Benedict
,
W.
et al (
1999
)
Pigment epithelium-derived factor: a potent inhibitor of angiogenesis
.
Science
285
,
245
248
[PubMed]
84
Huang
,
Q.
,
Wang
,
S.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2008
)
PEDF-deficient mice exhibit an enhanced rate of retinal vascular expansion and are more sensitive to hyperoxia-mediated vessel obliteration
.
Exp. Eye Res.
87
,
226
241
[PubMed]
85
Zhang
,
S.X.
,
Wang
,
J.J.
,
Gao
,
G.
,
Shao
,
C.
,
Mott
,
R.
and
Ma
,
J.-x.
(
2006
)
Pigment epithelium-derived factor (PEDF) is an endogenous antiinflammatory factor
.
FASEB J.
20
,
323
325
[PubMed]
86
Park
,
K.
,
Jin
,
J.
,
Hu
,
Y.
,
Zhou
,
K.
and
Ma
,
J.-x.
(
2011
)
Overexpression of Pigment Epithelium–Derived Factor Inhibits Retinal Inflammation and Neovascularization
.
Am. J. Pathol.
178
,
688
698
[PubMed]
87
Mori
,
K.
,
Duh
,
E.
,
Gehlbach
,
P.
,
Ando
,
A.
,
Takahashi
,
K.
,
Pearlman
,
J.
et al (
2001
)
Pigment epithelium-derived factor inhibits retinal and choroidal neovascularization
.
J. Cell. Physiol.
188
,
253
263
[PubMed]
88
Barnstable
,
C.J.
and
Tombran-Tink
,
J.
(
2004
)
Neuroprotective and antiangiogenic actions of PEDF in the eye: molecular targets and therapeutic potential
.
Prog. Retin. Eye Res.
23
,
561
577
[PubMed]
89
Curcio
,
C.A.
(
2001
)
Photoreceptor topography in ageing and age-related maculopathy
.
Eye (Lond)
15
,
376
383
[PubMed]
90
Curcio
,
C.A.
,
Sloan
,
K.R.
,
Kalina
,
R.E.
and
Hendrickson
,
A.E.
(
1990
)
Human photoreceptor topography
.
J. Comp. Neurol.
292
,
497
523
[PubMed]
91
Ogata
,
N.
,
Wang
,
L.
,
Jo
,
N.
,
Tombran-Tink
,
J.
,
Takahashi
,
K.
,
Mrazek
,
D.
et al (
2001
)
Pigment epithelium derived factor as a neuroprotective agent against ischemic retinal injury
.
Curr. Eye Res.
22
,
245
252
[PubMed]
92
Tombran-Tink
,
J.
and
Barnstable
,
C.J.
(
2003
)
PEDF: a multifaceted neurotrophic factor
.
Nat. Rev. Neurosci.
4
,
628
636
[PubMed]
93
Houenou
,
L.J.
,
D'Costa
,
A.P.
,
Li
,
L.
,
Turgeon
,
V.L.
,
Enyadike
,
C.
,
Alberdi
,
E.
et al (
1999
)
Pigment epithelium-derived factor promotes the survival and differentiation of developing spinal motor neurons
.
J. Comp. Neurol.
412
,
506
514
[PubMed]
94
Tombran-Tink
,
J.
and
Johnson
,
L.V.
(
1989
)
Neuronal differentiation of retinoblastoma cells induced by medium conditioned by human RPE cells
.
Investig. Ophthalmol. Vis. Sci.
30
,
1700
1707
95
Hjelmeland
,
L.M.
,
Cristofolo
,
V.
,
Funk
,
W.
,
Rakoczy
,
E.
and
Katz
,
M.L.
(
1999
)
Senescence of the retinal pigment epithelium
.
Mol. Vis.
5
,
33
37
[PubMed]
96
Volpert
,
O.V.
,
Zaichuk
,
T.
,
Zhou
,
W.
,
Reiher
,
F.
,
Ferguson
,
T.A.
,
Stuart
,
P.M.
et al (
2002
)
Inducer-stimulated Fas targets activated endothelium for destruction by anti-angiogenic thrombospondin-1 and pigment epithelium–derived factor
.
Nat. Med.
8
,
349
357
[PubMed]
97
Malchiodi-Albedi
,
F.
,
Feher
,
J.
,
Caiazza
,
S.
,
Formisano
,
G.
,
Perilli
,
R.
,
Falchi
,
M.
et al (
1998
)
PEDF (pigment epithelium-derived factor) promotes increase and maturation of pigment granules in pigment epithelial cells in neonatal albino rat retinal cultures
.
Int. J. Dev. Neurosci.
16
,
423
432
[PubMed]
98
Sparrow
,
J.R.
and
Boulton
,
M.
(
2005
)
RPE lipofuscin and its role in retinal pathobiology
.
Exp. Eye Res.
80
,
595
606
[PubMed]
99
Mustafi
,
D.
,
Kevany
,
B.M.
,
Genoud
,
C.
,
Bai
,
X.
and
Palczewski
,
K.
(
2013
)
Photoreceptor phagocytosis is mediated by phosphoinositide signaling
.
FASEB J.
27
,
4585
4595
[PubMed]
100
Zhou
,
T.
,
Hu
,
Y.
,
Chen
,
Y.
,
Zhou
,
K.K.
,
Zhang
,
B.
,
Gao
,
G.
et al (
2010
)
The pathogenic role of the canonical Wnt pathway in age-related macular degeneration
.
Invest. Ophthalmol. Vis. Sci.
51
,
4371
4379
[PubMed]
101
Dong
,
A.
,
Xie
,
B.
,
Shen
,
J.
,
Yoshida
,
T.
,
Yokoi
,
K.
,
Hackett
,
S.F.
et al (
2009
)
Oxidative stress promotes ocular neovascularization
.
J. Cell. Physiol.
219
,
544
552
[PubMed]
102
Amano
,
S.
,
Yamagishi
,
S.-i.
,
Inagaki
,
Y.
,
Nakamura
,
K.
,
Takeuchi
,
M.
,
Inoue
,
H.
et al (
2005
)
Pigment epithelium-derived factor inhibits oxidative stress-induced apoptosis and dysfunction of cultured retinal pericytes
.
Microvasc. Res.
69
,
45
55
[PubMed]
103
Valnickova
,
Z.
,
Petersen
,
S.V.
,
Nielsen
,
S.B.
,
Otzen
,
D.E.
and
Enghild
,
J.J.
(
2007
)
Heparin binding induces a conformational change in pigment epithelium-derived factor
.
J. Biol. Chem.
282
,
6661
6667
[PubMed]
104
Alberdi
,
E.M.
,
Weldon
,
J.E.
and
Becerra
,
S.P.
(
2003
)
Glycosaminoglycans in human retinoblastoma cells: heparan sulfate, a modulator of the pigment epithelium-derived factor-receptor interactions
.
BMC Biochem.
4
,
1
[PubMed]
105
Filleur
,
S.
,
Nelius
,
T.
,
De Riese
,
W.
and
Kennedy
,
R.
(
2009
)
Characterization of PEDF: a multi-functional serpin family protein
.
J. Cell. Biochem.
106
,
769
775
[PubMed]
106
Alberdi
,
E.
,
Aymerich
,
M.S.
and
Becerra
,
S.P.
(
1999
)
Binding of Pigment Epithelium-derived Factor (PEDF) to Retinoblastoma Cells and Cerebellar Granule Neurons evidence for a pedf receptor
.
J. Biol. Chem.
274
,
31605
31612
[PubMed]
107
Bernard
,
A.
,
Gao-Li
,
J.
,
Franco
,
C.-A.
,
Bouceba
,
T.
,
Huet
,
A.
and
Li
,
Z.
(
2009
)
Laminin receptor involvement in the anti-angiogenic activity of pigment epithelium-derived factor
.
J. Biol. Chem.
284
,
10480
10490
[PubMed]
108
Park
,
K.
,
Lee
,
K.
,
Zhang
,
B.
,
Zhou
,
T.
,
He
,
X.
,
Gao
,
G.
et al (
2011
)
Identification of a novel inhibitor of the canonical Wnt pathway
.
Mol. Cell. Biol.
31
,
3038
3051
[PubMed]
109
George
,
S.J.
(
2008
)
Wnt pathway a new role in regulation of inflammation
.
Arterioscler. Thromb. Vasc. Biol.
28
,
400
402
[PubMed]
110
Masckauchán
,
T.N.H.
and
Kitajewski
,
J.
(
2006
)
Wnt/Frizzled signaling in the vasculature: new angiogenic factors in sight
.
Physiology
21
,
181
188
111
Chen
,
Y.
,
Hu
,
Y.
,
Zhou
,
T.
,
Zhou
,
K.K.
,
Mott
,
R.
,
Wu
,
M.
et al (
2009
)
Activation of the Wnt pathway plays a pathogenic role in diabetic retinopathy in humans and animal models
.
Am. J. Pathol.
175
,
2676
2685
112
Ruegg
,
C.
,
Hasmim
,
M.
,
Lejeune
,
F.J.
and
Alghisi
,
G.C.
(
2006
)
Antiangiogenic peptides and proteins: from experimental tools to clinical drugs
.
Biochim. Biophys. Acta.
1765
,
155
177
113
Haviv
,
F.
,
Bradley
,
M.F.
,
Kalvin
,
D.M.
,
Schneider
,
A.J.
,
Davidson
,
D.J.
,
Majest
,
S.M.
et al (
2005
)
Thrombospondin-1 mimetic peptide inhibitors of angiogenesis and tumor growth: design, synthesis, and optimization of pharmacokinetics and biological activities
.
J. Med. Chem.
48
,
2838
2846
114
Gologorsky
,
D.
,
Thanos
,
A.
and
Vavvas
,
D.
(
2012
)
Therapeutic interventions against inflammatory and angiogenic mediators in proliferative diabetic retinopathy
.
Mediat. Inflamm.
2012
,
629452
115
Hoekstra
,
R.
,
de Vos
,
F.Y.
,
Eskens
,
F.A.
,
de Vries
,
E.G.
,
Uges
,
D.R.
,
Knight
,
R.
et al (
2006
)
Phase I study of the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 with 5-fluorouracil and leucovorin: a safe combination
.
Eur. J. Cancer
42
,
467
472
116
Ebbinghaus
,
S.
,
Hussain
,
M.
,
Tannir
,
N.
,
Gordon
,
M.
,
Desai
,
A.A.
,
Knight
,
R.A.
et al (
2007
)
Phase 2 study of ABT-510 in patients with previously untreated advanced renal cell carcinoma
.
Clin. Cancer Res.
13
,
6689
6695
117
Reiher
,
F.K.
,
Volpert
,
O.V.
,
Jimenez
,
B.
,
Crawford
,
S.E.
,
Dinney
,
C.P.
,
Henkin
,
J.
et al (
2002
)
Inhibition of tumor growth by systemic treatment with thrombospondin-1 peptide mimetics
.
Int. J. Cancer
98
,
682
689
118
Furrer
,
J.
,
Luy
,
B.
,
Basrur
,
V.
,
Roberts
,
D.D.
and
Barchi
,
J.J.
Jr.
(
2006
)
Conformational analysis of an alpha3beta1 integrin-binding peptide from thrombospondin-1: implications for antiangiogenic drug design
.
J. Med. Chem.
49
,
6324
6333
119
Garside
,
S.A.
,
Henkin
,
J.
,
Norvell
,
S.M.
,
Thomas
,
F.H.
and
Fraser
,
H.M.
(
2010
)
A Thrombospondin-Mimetic Peptide, ABT-898, Suppresses Angiogenesis and Promotes Follicular Atresia In Vivo in the Monkey
.
Biol. Reprod.
83
,
611
611
120
Garside
,
S.A.
,
Henkin
,
J.
,
Morris
,
K.D.
,
Norvell
,
S.M.
,
Thomas
,
F.H.
and
Fraser
,
H.M.
(
2010
)
A Thrombospondin-Mimetic Peptide, ABT-898, Suppresses Angiogenesis and Promotes Follicular Atresia in Pre- and Early-Antral Follicles in Vivo
.
Endocrinology
151
,
5905
5915
121
Hoekstra
,
R.
,
de Vos
,
F.Y.
,
Eskens
,
F.A.
,
Gietema
,
J.A.
,
van der Gaast
,
A.
,
Groen
,
H.J.
et al (
2005
)
Phase I safety, pharmacokinetic, and pharmacodynamic study of the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 in patients with advanced cancer
.
J. Clin. Oncol.
23
,
5188
5197
122
Hoekstra
,
R.
,
de Vos
,
F.Y.F.L.
,
Eskens
,
F.A.L.M.
,
Gietema
,
J.A.
,
van der Gaast
,
A.
,
Groen
,
H.J.M.
et al (
2005
)
Phase I Safety, Pharmacokinetic, and Pharmacodynamic Study of the Thrombospondin-1–Mimetic Angiogenesis Inhibitor ABT-510 in Patients With Advanced Cancer
.
J. Clin. Oncol.
23
,
5188
5197
123
Baker
,
L.H.
,
Rowinsky
,
E.K.
,
Mendelson
,
D.
,
Humerickhouse
,
R.A.
,
Knight
,
R.A.
,
Qian
,
J.
et al (
2008
)
Randomized, phase II study of the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 in patients with advanced soft tissue sarcoma
.
J. Clin. Oncol.
26
,
5583
5588
124
Sorbera
,
L.A.
and
Bayes
,
M.
(
2005
)
ABT-510
.
Drugs Fut.
30
,
1081
1086
125
Gietema
,
J.A.
,
Hoekstra
,
R.
,
de Vos
,
F.Y.F.L.
,
Uges
,
D.R.A.
,
van der Gaast
,
A.
,
Groen
,
H.J.M.
et al (
2006
)
A phase I study assessing the safety and pharmacokinetics of the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 with gemcitabine and cisplatin in patients with solid tumors
.
Ann. Oncol.
17
,
1320
1327
126
Amaral
,
J.
and
Becerra
,
S.P.
(
2010
)
Effects of human recombinant PEDF protein and PEDF-derived peptide 34-mer on choroidal neovascularization
.
Investig. Ophthalmol. Vis. Sci.
51
,
1318
1326
127
Johnston
,
E.K.
,
Francis
,
M.K.
and
Knepper
,
J.E.
(
2015
)
Recombinant pigment epithelium-derived factor PEDF binds vascular endothelial growth factor receptors 1 and 2
.
In Vitro Cell. Dev. Biol. Anim.
51
,
730
738
128
Volz
,
K.
,
Filleur
,
S.
,
Volpert
,
O.
and
Zaichuk
,
T.
(
2003
),
Anti-angiogenic fragments fo pigment epithelium-derived factor (pedf). Google Patents
129
Seger
,
R.
and
Maik-Rachline
,
G.
(
2012
),
Variants of pigment epithelium derived factor and uses thereof. Google Patents
130
Yamagishi
,
S.-i.
,
Imaizumi
,
T.
,
Shimizu
,
H.
and
Abe
,
R.
(
2005
),
Method for preventing or treating malignant melanoma. Google Patents
131
Yamagishi
,
S.-i.
and
Imaizumi
,
T.
(
2005
),
Method for preventing or treating osteosarcoma. Google Patents
132
Bouck
,
N.P.
,
Dawson
,
D.W.
and
Gillis
,
P.R.
(
2001
),
Methods and compositions for inhibiting angiogenesis. Google Patents
133
Ho
,
T.-C.
,
Chen
,
S.-L.
,
Yang
,
Y.-C.
,
Liao
,
C.-L.
,
Cheng
,
H.-C.
and
Tsao
,
Y.-P.
(
2007
)
PEDF induces p53-mediated apoptosis through PPAR gamma signaling in human umbilical vein endothelial cells
.
Cardiovasc. Res.
76
,
213
223
134
Gao
,
D.
,
Nolan
,
D.
,
McDonnell
,
K.
,
Vahdat
,
L.
,
Benezra
,
R.
,
Altorki
,
N.
et al (
2009
)
Bone marrow-derived endothelial progenitor cells contribute to the angiogenic switch in tumor growth and metastatic progression
.
Biochim. Biophys. Acta
1796
,
33
40
135
Kadoya
,
M.
,
Tamoto
,
E.
,
Shichinohe
,
T.
and
Hirano
,
S.
(
2015
)
Pigment epithelium-derived factor inhibits the growth of human esophageal squamous cell carcinoma by suppressing neovascularization
.
Hokkaido Igaku Zasshi
90
,
17
29
136
Yang
,
H.
and
Grossniklaus
,
H.E.
(
2010
)
Constitutive Overexpression of Pigment Epithelium–Derived Factor Inhibition of Ocular Melanoma Growth and Metastasis
.
Invest. Ophthalmol. Vis. Sci.
51
,
28
34
137
Stellmach
,
V.
,
Crawford
,
S.E.
,
Zhou
,
W.
and
Bouck
,
N.
(
2001
)
Prevention of ischemia-induced retinopathy by the natural ocular antiangiogenic agent pigment epithelium-derived factor
.
Proc. Natl. Acad. Sci. U.S.A.
98
,
2593
2597
138
Mori
,
K.
,
Gehlbach
,
P.
,
Ando
,
A.
,
McVey
,
D.
,
Wei
,
L.
and
Campochiaro
,
P.A.
(
2002
)
Regression of ocular neovascularization in response to increased expression of pigment epithelium–derived factor
.
Invest. Ophthalmol. Vis. Sci.
43
,
2428
2434
139
Rasmussen
,
H.
,
Chu
,
K.
,
Campochiaro
,
P.
,
Gehlbach
,
P.
,
Haller
,
J.
,
Handa
,
J.
et al (
2001
)
Clinical protocol. An open-label, phase I, single administration, dose-escalation study of ADGVPEDF. 11D (ADPEDF) in neovascular age-related macular degeneration (AMD)
.
Hum. Gene Ther.
12
,
2029
2032
140
Campochiaro
,
P.A.
,
Nguyen
,
Q.D.
,
Shah
,
S.M.
,
Klein
,
M.L.
,
Holz
,
E.
,
Frank
,
R.N.
et al (
2006
)
Adenoviral vector-delivered pigment epithelium-derived factor for neovascular age-related macular degeneration: results of a phase I clinical trial
.
Hum. Gene Ther.
17
,
167
176
141
Mirochnik
,
Y.
,
Aurora
,
A.
,
Schulze-Hoepfner
,
F.T.
,
Deabes
,
A.
,
Shifrin
,
V.
,
Beckmann
,
R.
et al (
2009
)
short pedf-derived peptide inhibits angiogenesis and tumor growth
.
Clin. Cancer Res.
15
,
1655
1663
142
Filleur
,
S.
,
Volz
,
K.
,
Nelius
,
T.
,
Mirochnik
,
Y.
,
Huang
,
H.
,
Zaichuk
,
T.A.
et al (
2005
)
Two Functional Epitopes of Pigment Epithelial–Derived Factor Block Angiogenesis and Induce Differentiation in Prostate Cancer
.
Cancer Res.
65
,
5144
5152
143
Gao
,
X.
,
Zhang
,
H.
,
Zhuang
,
W.
,
Yuan
,
G.
,
Sun
,
T.
,
Jiang
,
X.
et al (
2014
)
PEDF and PEDF-derived peptide 44mer protect cardiomyocytes against hypoxia-induced apoptosis and necroptosis via anti-oxidative effect
.
Sci. Rep.
4
,
5637
144
Longeras
,
R.
,
Farjo
,
K.
,
Ihnat
,
M.
and
Ma
,
J.-X.
(
2012
)
A PEDF-Derived Peptide Inhibits Retinal Neovascularization and Blocks Mobilization of Bone Marrow-Derived Endothelial Progenitor Cells
.
Exp. Diabet. Res.
2012
,
518426
145
Famiglietti
,
E.V.
,
Stopa
,
E.G.
,
McGookin
,
E.D.
,
Song
,
P.
,
LeBlanc
,
V.
and
Streeten
,
B.W.
(
2003
)
Immunocytochemical localization of vascular endothelial growth factor in neurons and glial cells of human retina
.
Brain Res.
969
,
195
204
146
Nishijima
,
K.
,
Ng
,
Y.-S.
,
Zhong
,
L.
,
Bradley
,
J.
,
Schubert
,
W.
,
Jo
,
N.
et al (
2007
)
Vascular Endothelial Growth Factor-A Is a Survival Factor for Retinal Neurons and a Critical Neuroprotectant during the Adaptive Response to Ischemic Injury
.
Am. J. Pathol.
171
,
53
67
147
Eremina
,
V.
,
Jefferson
,
J.A.
,
Kowalewska
,
J.
,
Hochster
,
H.
,
Haas
,
M.
,
Weisstuch
,
J.
et al (
2008
)
VEGF Inhibition and Renal Thrombotic Microangiopathy
.
N. Engl. J. Med.
358
,
1129
1136
148
Walia
,
A.
,
Yang
,
J.F.
,
Huang
,
Y.-h.
,
Rosenblatt
,
M.I.
,
Chang
,
J.-H.
and
Azar
,
D.T.
(
2015
)
Endostatin's emerging roles in angiogenesis, lymphangiogenesis, disease, and clinical applications
.
Biochim. Biophys. Acta
1850
,
2422
2438
149
Poluzzi
,
C.
,
Iozzo
,
R.V.
and
Schaefer
,
L.
(
2016
)
Endostatin and endorepellin: A common route of action for similar angiostatic cancer avengers
.
Adv. Drug Deliv. Rev.
97
,
156
173
150
Nguyen
,
T.M.B.
,
Subramanian
,
I.V.
,
Xiao
,
X.
,
Ghosh
,
G.
,
Nguyen
,
P.
,
Kelekar
,
A.
et al (
2009
)
Endostatin induces autophagy in endothelial cells by modulating Beclin 1 and β-catenin levels
.
J. Cell. Mol. Med.
13
,
3687
3698
151
Sudhakar
,
A.
,
Sugimoto
,
H.
,
Yang
,
C.
,
Lively
,
J.
,
Zeisberg
,
M.
and
Kalluri
,
R.
(
2003
)
Human tumstatin and human endostatin exhibit distinct antiangiogenic activities mediated by αvβ3 and α5β1 integrins
.
Proc. Natl. Acad. Sci.
100
,
4766
4771
152
Hajitou
,
A.
,
Grignet
,
C.
,
Devy
,
L.
,
Berndt
,
S.
,
Blacher
,
S.
,
Deroanne
,
C.F.
et al (
2002
)
The antitumoral effect of endostatin and angiostatin is associated with a down-regulation of vascular endothelial growth factor expression in tumor cells
.
FASEB J.
16
,
1802
1804
[PubMed]
153
Kim
,
Y.-M.
,
Hwang
,
S.
,
Kim
,
Y.-M.
,
Pyun
,
B.-J.
,
Kim
,
T.-Y.
,
Lee
,
S.-T.
et al (
2002
)
Endostatin blocks vascular endothelial growth factor-mediated signaling via direct interaction with KDR/Flk-1
.
J. Biol. Chem.
277
,
27872
27879
[PubMed]
154
Karumanchi
,
S.A.
,
Jha
,
V.
,
Ramchandran
,
R.
,
Karihaloo
,
A.
,
Tsiokas
,
L.
,
Chan
,
B.
et al (
2001
)
Cell surface glypicans are low-affinity endostatin receptors
.
Mol. Cell.
7
,
811
822
[PubMed]
155
Deryugina
,
E.I.
and
Quigley
,
J.P.
(
2015
)
Tumor angiogenesis: MMP-mediated induction of intravasation-and metastasis-sustaining neovasculature
.
Matrix Biol.
44
,
94
112
[PubMed]
156
Shay
,
G.
,
Lynch
,
C.C.
and
Fingleton
,
B.
(
2015
)
Moving targets: emerging roles for MMPs in cancer progression and metastasis
.
Matrix Biol.
44
,
200
206
[PubMed]
157
Wickström
,
S.A.
,
Alitalo
,
K.
and
Keski-Oja
,
J.
(
2002
)
Endostatin associates with integrin α5β1 and caveolin-1, and activates Src via a tyrosyl phosphatase-dependent pathway in human endothelial cells
.
Cancer Res.
62
,
5580
5589
158
Wickström
,
S.A.
,
Alitalo
,
K.
and
Keski-Oja
,
J.
(
2003
)
Endostatin associates with lipid rafts and induces reorganization of the actin cytoskeleton via down-regulation of RhoA activity
.
J. Biol. Chem.
278
,
37895
37901
159
Shichiri
,
M.
and
Hirata
,
Y.
(
2001
)
Antiangiogenesis signals by endostatin
.
FASEB J.
15
,
1044
1053
160
Wickström
,
S.A.
,
Veikkola
,
T.
,
Rehn
,
M.
,
Pihlajaniemi
,
T.
,
Alitalo
,
K.
and
Keski-Oja
,
J.
(
2001
)
Endostatin-induced modulation of plasminogen activation with concomitant loss of focal adhesions and actin stress fibers in cultured human endothelial cells
.
Cancer Res.
61
,
6511
6516
161
Hanai
,
J.-i.
,
Gloy
,
J.
,
Karumanchi
,
S.A.
,
Kale
,
S.
,
Tang
,
J.
,
Hu
,
G.
et al (
2002
)
Endostatin is a potential inhibitor of Wnt signaling
.
J. Cell Biol.
158
,
529
539
162
Damico
,
R.
,
Kolb
,
T.M.
,
Valera
,
L.
,
Wang
,
L.
,
Housten
,
T.
,
Tedford
,
R.J.
et al (
2015
)
Serum endostatin is a genetically determined predictor of survival in pulmonary arterial hypertension
.
Am. J. Respir. Crit. Care Med.
191
,
208
218
163
Sodha
,
N.R.
,
Clements
,
R.T.
,
Boodhwani
,
M.
,
Xu
,
S.-H.
,
Laham
,
R.J.
,
Bianchi
,
C.
et al (
2009
)
Endostatin and angiostatin are increased in diabetic patients with coronary artery disease and associated with impaired coronary collateral formation
.
Am. J. Physiol. Heart Circ. Physiol.
296
,
H428
H434
164
Del Moral
,
P.M.
,
Sala
,
F.G.
,
Tefft
,
D.
,
Shi
,
W.
,
Keshet
,
E.
,
Bellusci
,
S.
et al (
2006
)
VEGF-A signaling through Flk-1 is a critical facilitator of early embryonic lung epithelial to endothelial crosstalk and branching morphogenesis
.
Dev. Biol.
290
,
177
188
165
Cao
,
Y.
and
Xue
,
L.
(
2004
),
Angiostatin
. In
Semin. Thromb. Hemost.
ed. pp.
83
93
, Copyright© 2004 by
Thieme Medical Publishers, Inc.
, 333
Seventh Avenue, New York, NY 10001, USA
.
166
Magnusson
,
S.
,
Sottrup-Jensen
,
L.
,
Petersen
,
T.
and
Claeys
,
H.
(
Hemker
,
H.C.
and
Veltkamp
,
J.J.
, eds), (
1975
)
The primary structure of prothrombin, the role of vitamin K in blood coagulation and a thrombin-catalyzed ‘negative feed-back'control mechanism for limiting the activation of prothrombin
.
In Prothrombin and Related Coagulation Factors
Leiden, The Netherlands
Leiden University Press
,
25
46
167
Griscelli
,
F.
,
Li
,
H.
,
Bennaceur-Griscelli
,
A.
,
Soria
,
J.
,
Opolon
,
P.
,
Soria
,
C.
et al (
1998
)
Angiostatin gene transfer: inhibition of tumor growth in vivo by blockage of endothelial cell proliferation associated with a mitosis arrest
.
Proc. Natl. Acad. Sci. U.S.A.
95
,
6367
6372
168
Li
,
F.
,
Yang
,
J.
,
Liu
,
X.
,
He
,
P.
,
Ji
,
S.
,
Wang
,
J.
et al (
2000
)
Human glioma cell BT325 expresses a proteinase that converts human plasminogen to kringle 1–5-containing fragments
.
Biochem. Biophys. Res. Commun.
278
,
821
825
169
Moser
,
T.L.
,
Kenan
,
D.J.
,
Ashley
,
T.A.
,
Roy
,
J.A.
,
Goodman
,
M.D.
,
Misra
,
U.K.
et al (
2001
)
Endothelial cell surface F1-FO ATP synthase is active in ATP synthesis and is inhibited by angiostatin
.
Proc. Natl. Acad. Sci. U.S.A.
98
,
6656
6661
170
Moser
,
T.L.
,
Stack
,
M.S.
,
Asplin
,
I.
,
Enghild
,
J.J.
,
Højrup
,
P.
,
Everitt
,
L.
et al (
1999
)
Angiostatin binds ATP synthase on the surface of human endothelial cells
.
Proc. Natl. Acad. Sci. U.S.A.
96
,
2811
2816
171
Troyanovsky
,
B.
,
Levchenko
,
T.
,
Månsson
,
G.
,
Matvijenko
,
O.
and
Holmgren
,
L.
(
2001
)
Angiomotin an angiostatin binding protein that regulates endothelial cell migration and tube formation
.
J. Cell Biol.
152
,
1247
1254
172
Grunewald
,
M.
,
Avraham
,
I.
,
Dor
,
Y.
,
Bachar-Lustig
,
E.
,
Itin
,
A.
,
Yung
,
S.
et al (
2006
)
VEGF-induced adult neovascularization: recruitment, retention, and role of accessory cells
.
Cell.
124
,
175
189
173
Tolentino
,
M.
(
2011
)
Systemic and ocular safety of intravitreal anti-VEGF therapies for ocular neovascular disease
.
Surv. Ophthalmol.
56
,
95
113
174
Meyer
,
C.H.
,
Michels
,
S.
,
Rodrigues
,
E.B.
,
Hager
,
A.
,
Mennel
,
S.
,
Schmidt
,
J.C.
et al (
2011
)
Incidence of rhegmatogenous retinal detachments after intravitreal antivascular endothelial factor injections
.
Acta Ophthalmol.
89
,
70
75
175
Bakri
,
S.
,
Pulido
,
J.S.
,
McCannel
,
C.
,
Hodge
,
D.
,
Diehl
,
N.
and
Hillemeier
,
J.
(
2009
)
Immediate intraocular pressure changes following intravitreal injections of triamcinolone, pegaptanib, and bevacizumab
.
Eye
23
,
181
185
176
Gismondi
,
M.
,
Salati
,
C.
,
Salvetat
,
M.L.
,
Zeppieri
,
M.
and
Brusini
,
P.
(
2009
)
Short-term effect of intravitreal injection of Ranibizumab (Lucentis) on intraocular pressure
.
J. Glaucoma
18
,
658
661
177
Hoang
,
Q.V.
,
Mendonca
,
L.S.
,
Della Torre
,
K.E.
,
Jung
,
J.J.
,
Tsuang
,
A.J.
and
Freund
,
K.B.
(
2012
)
Effect on intraocular pressure in patients receiving unilateral intravitreal anti-vascular endothelial growth factor injections
.
Ophthalmology
119
,
321
326
178
Brouzas
,
D.
,
Koutsandrea
,
C.
,
Moschos
,
M.
,
Papadimitriou
,
S.
,
Ladas
,
I.
and
Apostolopoulos
,
M.
(
2009
)
Massive choroidal hemorrhage after intravitreal administration of bevacizumab (Avastin) for AMD followed by controlateral sympathetic ophthalmia
.
Clin. Ophthalmol.
3
,
457
459
179
Ladas
,
I.D.
,
Karagiannis
,
D.A.
,
Rouvas
,
A.A.
,
Kotsolis
,
A.I.
,
Liotsou
,
A.
and
Vergados
,
I.
(
2009
)
Safety of repeat intravitreal injections of bevacizumab versus ranibizumab: our experience after 2,000 injections
.
Retina
29
,
313
318
180
Chang
,
L.K.
,
Flaxel
,
C.J.
,
Lauer
,
A.K.
and
Sarraf
,
D.
(
2007
)
RPE tears after pegaptanib treatment in age-related macular degeneration
.
Retina
27
,
857
863
181
Smith
,
B.T.
,
Kraus
,
C.L.
and
Apte
,
R.S.
(
2009
)
Retinal pigment epithelial tears in ranibizumab-treated eyes
.
Retina
29
,
335
339
182
Shah
,
C.P.
,
Hsu
,
J.
,
Garg
,
S.J.
,
Fischer
,
D.H.
and
Kaiser
,
R.
(
2006
)
Retinal Pigment Epithelial Tear After Intravitreal Bevacizumab Injection
.
Am. J. Ophthalmol.
142
,
1070
1071.e1071
183
Wang
,
S.
,
Sorenson
,
C.M.
and
Sheibani
,
N.
(
2012
)
Lack of thrombospondin 1 and exacerbation of choroidal neovascularization
.
Arch. Ophthalmol.
130
,
615
620
184
Mac Nair
,
C.E.
,
Schlamp
,
C.L.
,
Montgomery
,
A.D.
,
Shestopalov
,
V.I.
and
Nickells
,
R.W.
(
2016
)
Retinal glial responses to optic nerve crush are attenuated in Bax-deficient mice and modulated by purinergic signaling pathways
.
J. Neuroinflamm.
13
,
93
185
Li
,
Y.
,
Schlamp
,
C.L.
and
Nickells
,
R.W.
(
1999
)
Experimental induction of retinal ganglion cell death in adult mice
.
Invest. Ophthalmol. Vis. Sci.
40
,
1004
1008
186
Schlamp
,
C.L.
,
Montgomery
,
A.D.
,
Mac Nair
,
C.E.
,
Schuart
,
C.
,
Willmer
,
D.J.
and
Nickells
,
R.W.
(
2013
)
Evaluation of the percentage of ganglion cells in the ganglion cell layer of the rodent retina
.
Mol. Vis.
19
,
1387
1396