Elafin and SLPI (secretory leucocyte protease inhibitor) have multiple important roles both in normal homoeostasis and at sites of inflammation. These include antiprotease and antimicrobial activity as well as modulation of the response to LPS (lipopolysaccharide) stimulation. Elafin and SLPI are members of larger families of proteins secreted predominantly at mucosal sites, and have been shown to be modulated in multiple pathological conditions. We believe that elafin and SLPI are important molecules in the controlled functioning of the innate immune system, and may have further importance in the integration of this system with the adaptive immune response. Recent interest has focused on the influence of inflamed tissues on the recruitment and phenotypic modulation of cells of the adaptive immune system and, indeed, the local production of elafin and SLPI indicate that they are ideally placed in this regard. Functionally related proteins, such as the defensins and cathelicidins, have been shown to have direct effects upon dendritic cells with potential alteration of their phenotype towards type I or II immune responses. This review addresses the multiple functions of elafin and SLPI in the inflammatory response and discusses further their roles in the development of the adaptive immune response.

INTRODUCTION

Adaptive immunity represents the body's most sophisticated, and some maintain most powerful, defence mechanism. The development of this system has permitted unparalleled evolutionary success in jawed vertebrates and, indeed, an analogous system has recently been suggested in surviving jawless vertebrates [1]. As such, in humans adaptive immunity appears crucial to prevent the establishment or progression of infections by bacteria, viruses and parasites. However, despite the apparent importance of adaptive immunity, it is the phylogenetically ancient system of inflammation/innate immunity that is responsible for the rapid initial defence against infection. For many years, this innate response was considered to merely provide temporary protection while the adaptive immune system developed a clonal response to a specific non-self pathogen. Within the last decade, however, the notion that adaptive immunity recognizes potential pathogens based on the mechanism of ‘self/non-self discrimination’ has been progressively eroded and replaced by the ‘danger hypothesis’ model, whereby an adaptive response is actually mounted against any pathogenic determinant that has the potential to cause harm to the host [2]. The decision as to whether a particular epitope is considered ‘dangerous’ or ‘safe’ seems to rest with the innate immune system.

Although the image of innate immunity is evolving towards a dextrous system interfacing with the adaptive immune response, the fact remains that the innate inflammatory effector mechanisms still have considerable potential to cause harm to host tissues. Indeed many major diseases, ranging from osteoarthritis to atherosclerosis, have an inflammatory basis. One group of innate immunity effectors responsible for such tissue damage are proteases. These enzymes are produced by a variety of phagocytic inflammatory cells, including the neutrophil, to degrade ingested pathogens and permit cell motility through the extracellular matrix [3,4]. In response to these enzymes the host secretes antiprotease molecules which serve to neutralize any excess protease load and protect host tissues. These antiproteases have been classified as either ‘systemic’ or ‘alarm’ [5] and their relationship in the lung is shown in Figure 1. Systemic antiproteases are produced by hepatocytes and reach the interstitium by diffusion from the circulation. They include α1-PI (α1-proteinase inhibitor) and α1-antichymotrypsin. Alarm antiproteases include SLPI (secretory leucocyte protease inhibitor) and elafin, two members of the four-disulphide core family [513]. Alarm antiproteases are synthesized and secreted by cells local to the site of inflammation in response to the same primary cytokines [IL (interleukin)-1 and TNF (tumour necrosis factor)] that drive the initial inflammatory response [14,15]. The notion that they provide a local inducible antiprotease defence is supported by evidence from conditions associated with excess protease activity, such as psoriasis and emphysema, which are also associated with increased alarm antiprotease levels [16,17]. Indeed, a localized decrease in elafin expression in the skin has been demonstrated to be linked to an increase in pustule formation in psoriatic skin due to an imbalance between elastase and its inhibitors [18,19].

Sources of systemic and alarm antiproteases

Figure 1
Sources of systemic and alarm antiproteases

Large green arrows signify diffusion of systemic antiproteases (α1-PI, α1-antichymotrypsin and α2-macroglobulin) from the bloodstream into the alveolus, whereas small green arrows indicate local release of alarm antiproteases (elafin and SLPI). PMN, polymorphonuclear leucocyte (neutrophil); AM, alveolar macrophage.

Figure 1
Sources of systemic and alarm antiproteases

Large green arrows signify diffusion of systemic antiproteases (α1-PI, α1-antichymotrypsin and α2-macroglobulin) from the bloodstream into the alveolus, whereas small green arrows indicate local release of alarm antiproteases (elafin and SLPI). PMN, polymorphonuclear leucocyte (neutrophil); AM, alveolar macrophage.

Altered expression of the alarm antiproteases SLPI and elafin has also been noted in pathologies which do not appear to have a direct relationship to excess antiprotease activity, such as HIV infection [20], lung cancer [21] and ischaemic heart disease [22]. These observations, combined with the characterization of SLPI and elafin as antimicrobial substances (reviewed in [23]), have led to the identification of the alarm antiproteases as key mediators in innate host defences. Moreover, exciting effects of elafin on adaptive immune responses are beginning to be described, suggesting that the alarm antiproteases may form part of the axis of communication that allows the innate immune system to recruit, or shape, the adaptive immune response.

This review will describe the characteristics of the alarm antiprotease molecules and discuss the evidence pertaining to their pleiotrophic functions in inflammation and immunity. After providing an overview of some other similar innate immune molecules, potential roles for the alarm antiproteases in the integration of the innate and adaptive immune systems will be examined in an attempt to tie in the available data and potentially expand the ‘danger’ model of immunity. Finally, the implications of these recent developments on vaccine design and the treatment of infective diseases will be discussed.

CHARACTERISTICS OF THE ALARM ANTIPROTEASES

SLPI

Human SLPI is an 11.7 kDa cationic non-glycosylated protein containing 107 amino acids, and orthologues have been demonstrated in mice, rats, pigs and sheep [2427]. It consists of two highly similar WAP (‘whey acid protein’)/four-disulphide core domains. The crystal structure of SLPI has been determined and shows SLPI to contain 16 cysteine residues which assemble into eight disulphide bridges (four in each WAP domain) [28]. SLPI is constitutively expressed at many mucosal surfaces and is produced by a variety of epithelial cells, including respiratory, intestinal and amniotic epithelia [15,2932]. Expression of SLPI by keratinocytes has also been well documented in both healthy and inflamed skin. Although expression at these sites fits with a model whereby SLPI provides an antiprotease shield, production of SLPI mRNA and protein has also been noted in various inflammatory cells, including mast cells [33], neutrophils [34] and macrophages [35]. Although it is true that SLPI expression in these latter cell types might represent autoprotection for armed inflammatory effector cells, it inevitably led to the suggestion that the true role of SLPI in these locations might be as a participant in the innate immune response (see below).

SLPI was first cast as an alarm reactant [5] as LPS (lipopolysaccharide) and early inflammatory cytokines appeared to augment [14,34,36], and anti-inflammatory/‘repair’-type cytokines limit, its production [37]. Indeed SLPI production in numerous epithelial cell types has been noted in response to LPS, IL-1, TNF-α, EGF (epidermal growth factor), α-defensins and HNE (human neutrophil elastase) [14,2931,3840]. However, expression of SLPI by myeloid cells has been shown to be subject to several additional regulations. For example, although LPS can induce SLPI expression in macrophages, TNF and IL-1 cannot [41]. Rather, anti-inflammatory cytokines such as IL-6 and IL-10 are capable of inducing SLPI production in macrophages with slowly rising kinetics comparable with that induced by LPS [41]. These findings are in agreement with later work ascribing a number of anti-inflammatory effects to SLPI, but are discordant with the finding that SLPI production by bronchial epithelial cells in vitro is inhibited by TGF-β (transforming growth factor-β) [37]. More recently, hormonal influences on SLPI production have been described. These effects are likely to be tissue specific. For instance, SLPI generation by the endometrium follows a cyclic pattern and is maximal at the time of menstruation (when circulating levels of progresterone and oestradiol are lowest) [42], whereas in a breast epithelial cell line in vitro SLPI mRNA expression was up-regulated by progesterone [43].

Although SLPI has been shown to inhibit a spectrum of proteases (including HNE, cathepsin G, trypsin, chymotrypsin and chymase), its main action in this regard is likely to be the inhibition of elastase, as indicated by its low dissociation constant and favourable kinetics of inhibition for this enzyme [5,44]. Of note is the observation that SLPI has been demonstrated in association with elastin fibres both in lung [45] and skin [46], indicating a potential role in the direct protection of elastin against proteolysis. SLPI represents a major antiprotease of the upper airways and compromise of the antiprotease activity of SLPI by cleavage or oxidation due to smoking [47] could be a contributor to the pathogenesis of emphysema [48]. Additionally, SLPI is cleaved and inactivated by the cysteine proteinases cathepsin B, S and L [49]. Although the serine proteases and MMPs (matrix metalloproteinases) do not have this property, a noticeable exception appears to be the Pseudomonas aeruginosa-derived metallo-elastase [50]. Although the exact regulating pathways remain elusive, it is worth noting that, at all tissue sites where SLPI is expressed, it seems to be constitutively expressed. As described, various microbial products, markers of inflammation and hormones have the capacity to up-regulate its production. Hence SLPI can be envisioned to provide a baseline antiprotease shield that can be up-regulated at times of inflammation or, as the latest hormone studies show [42,43], at times when inflammation or infection might be anticipated.

Elafin/SKALP/elastase-specific inhibitor

The elafin gene encodes a secreted 9.9 kDa protein consisting of 95 amino acids [51,11]. The protein is made up of two domains, a globular C-terminus structurally similar to the WAP/four-disulphide core domains of SLPI and a variably flexible NH2 domain referred to as ‘cementoin’, which provides a substrate for the enzyme transglutaminase [52,53]. This enzyme allows elafin to be cross-linked into polymers or with extracellular matrix components. Although the antiprotease activity of elafin was initially identified in both the intact 9.9 kDa molecule and a cleaved 6 kDa C-terminus (lacking the cementoin domain), elafin shows a reduced protective effect in an in vivo model of elastase-induced lung injury when it is cleaved of its cementoin domain [54]. These findings support the argument that intact elafin is maximally effective as an alarm antiprotease in protecting tissues from elastase-mediated inflammatory damage.

Elafin inhibits porcine pancreatic elastase, HNE and proteinase-3 with a low degree of reversibility [5,12,53] and, hence, has a more restricted spectrum of inhibition than SLPI. Similar to SLPI, elafin has no antigranzyme activity [55]. In skin, elafin expression is constitutive in the squamous epithelium (which is constantly exposed to inflammatory stimuli) suggesting that elafin contributes to tissue protection against inflammation and neutrophil elastase [10,56]. Indeed, raised elafin expression is well documented in the epidermis in inflammatory conditions such as psoriasis and this induction is correlated with the degree of neutrophil influx [16,57]. In addition to skin, elafin has been identified in bronchial secretions [11,58]. This production has been attributed not only to bronchial epithelial cells [14] and alveolar epithelial cells [32], but also, in line with SLPI production, to alveolar macrophages [35]. Other documented cell types producing elafin are intestinal epithelium in the large intestine [59] and endometrial epithelial cells [60]. Infiltrating neutrophils also provide a significant contribution to elafin release by endometrium during menstruation [60].

The regulation of elafin expression during inflammation has received much attention. In vitro bronchial and alveolar epithelial cells produce little elafin protein, but the quantity of elafin recovered from the supernatant can be greatly increased by addition of the inflammatory cytokines IL-1 and TNF-α [14]. These cytokines produce similar increases in expression of elafin from keratinocytes in vitro [61]. The c-jun, p38 MAPK (mitogen-activated protein kinase) and NF-κB (nuclear factor κB) pathways are thought to be implicated in the elafin response to inflammatory cytokines [6264]. Of note, the cytokine-mediated increase in elafin production by epithelial cells is greater than the increase in SLPI production [14]. Hence, whereas SLPI has been described as providing a baseline antiprotease shield and can be isolated from bronchial lavage samples from healthy individuals [65], elafin might be of greater significance during an inflammatory challenge to the lungs. In keeping with this notion elafin mRNA expression in bronchial epithelial cells is increased by free HNE, which is in abundance at times of inflammation [39,66]. Variable results have been obtained when attempting to demonstrate an increase in elafin protein production in response to HNE, possibly as elafin might remain cell-associated to provide local anti-elastase protection until delivery of the more potent systemic anti-elastases from the liver [39,66].

Elafin and SLPI have been described as members of the family of WAP-motif-containing proteins, with SLPI containing two WAP domains and elafin containing one WAP domain. It has been suggested, however, that elafin would more appropriately fit into a new family of proteins with a single WAP domain and a transglutaminase substrate domain, termed the ‘trappins’ [6,67]. WAP-containing trappins have been identified across species, including sheep, pig, peccary, cattle, hippopotamus and warthog [6,15,59,67,68]. Interestingly, no trappin family members (including elafin) have been demonstrated in rat or mouse tissues. Five human trappin family members (including elafin/trappin-2) have now been identified [67,69,70]. Aside from identifying mucosal surfaces as their major source, little is known about these other trappins. Interestingly, only elafin orthologues have been shown to have obvious antiprotease activity [11,15], suggesting the other trappin family members have alternative, currently undefined, functions.

ALARM ANTIPROTEASES IN THE INNATE IMMUNE RESPONSE

Although SLPI and elafin were initially discovered as a result of their antiprotease activity, it soon became clear that they have multiple functions (Table 1). Many of these bioactivities implicate SLPI and elafin as effector molecules in innate immunity and host defence, and are discussed under the headings below.

Table 1
Some functions of SLPI and elafin in addition to their antiprotease activity

PMN, polymorphonuclear leucocyte (neutrophil).

ActionReferences
SLPI  
 Antibacterial [73,76
 Antifungal [7678
 Inhibition of HIV transmission [8083
 Anti-inflammatory  
  Inhibition of inflammatory infiltrate recruitment [105,106
  Inhibition of NF-κB activation [116,117
  Inhibition of mast cell histamine release [107
  Inhibition of C5a production in the inflamed lung [71
 Priming of innate immunity  
  Inhibition of the neutrophil mediated down-regulation of C5a-induced activities in other PMNs [72
 Tissue repair  
  Augmented macrophage production of TGF-β/IL-10 [111
  Improved cutaneous and oral mucosal wound healing [128130
Elafin  
 Antibacterial [74,75,79,176
 Anti-inflammatory  
  Inhibition of inflammatory infiltrate recruitment [102104
  Inhibition of NF-κB activation [117
 Priming of innate immunity  
  Chemotaxis of neutrophils [121,122
  Inhibition of the neutrophil-mediated down-regulation of C5a-induced activities in other PMNs [72
  Enhancement of LPS response in vivo and in vitro [121123
 Tissue remodelling and cellular differentiation  
  Involvement in salivary gland development [124
 Augmentation of antiviral adaptive immunity [138
ActionReferences
SLPI  
 Antibacterial [73,76
 Antifungal [7678
 Inhibition of HIV transmission [8083
 Anti-inflammatory  
  Inhibition of inflammatory infiltrate recruitment [105,106
  Inhibition of NF-κB activation [116,117
  Inhibition of mast cell histamine release [107
  Inhibition of C5a production in the inflamed lung [71
 Priming of innate immunity  
  Inhibition of the neutrophil mediated down-regulation of C5a-induced activities in other PMNs [72
 Tissue repair  
  Augmented macrophage production of TGF-β/IL-10 [111
  Improved cutaneous and oral mucosal wound healing [128130
Elafin  
 Antibacterial [74,75,79,176
 Anti-inflammatory  
  Inhibition of inflammatory infiltrate recruitment [102104
  Inhibition of NF-κB activation [117
 Priming of innate immunity  
  Chemotaxis of neutrophils [121,122
  Inhibition of the neutrophil-mediated down-regulation of C5a-induced activities in other PMNs [72
  Enhancement of LPS response in vivo and in vitro [121123
 Tissue remodelling and cellular differentiation  
  Involvement in salivary gland development [124
 Augmentation of antiviral adaptive immunity [138

Alarm antiproteases are antimicrobial proteins

Both SLPI and elafin have demonstrable antimicrobial properties in vitro and in vivo [7377]. SLPI is antimicrobial against the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staph. epidermis [73,76] and group A Streptococcus [77], and the fungi Aspergillus fumigatus and Candida albicans [7678]. Elafin is antimicrobial against Staph. aureus and P. aeruginosa [74,75,79]. Although the biochemical mechanisms of these antimicrobial activities have not been fully elucidated, it has been suggested that, similarly to other antimicrobial peptides [21], the cationic nature of SLPI and elafin allows them to disruptively interact with the anionic cell membrane. SLPI also plays an important role in the prevention of HIV transmission [8082] by interrupting the interaction of the HIV virus with receptors on the host cell [83]. It has recently been shown that SLPI binds to annexin II on the surface of human macrophages hence disrupting the binding of the surface phosphatidylserine of the HIV membrane to this receptor [84].

Although it has been relatively easy to highlight in vitro antimicrobial effects of the alarm antiproteases, such studies indicate little about the in vivo biological relevance of such activities. However, the finding that cellfree supernatants of P. aeruginosa have the ability to induce elafin production by human keratinocytes [79] does suggest that the alarm antiproteases are functionally important antimicrobial substances. In contrast, SLPI expression was not inducible in primary human endometrial epithelial cells by the bacterial products LPS or LTA (lipoteichoic acid), but rather was expressed constitutively [85]. Although the same system could induce expression of a well-characterized antimicrobial molecule (human β-defensin 2), these results do not negate the possibility that some other bacterial determinant(s) could increase SLPI production as a primary antimicrobial defence. For conclusive proof of the functional importance of a bioactive molecule, genetic ‘knockout’ animal studies are frequently required. However, due to the complex interacting nature of the mucosal antimicrobial screen (for a review see [86]), the precise deletion of a single element may result in multiple downstream effects and such studies would be difficult to interpret.

Nevertheless, it is possible to collect circumstantial evidence pertaining to the importance of the alarm antiproteases’ antimicrobial function by examining their in vivo expression in infectious diseases. For example, salivary SLPI levels are increased in HIV patients with previous or current oral thrush [87], and increased infant SLPI salivary and vaginal fluid levels are associated with reduced maternal–infant HIV transmission through infected breast milk and at childbirth respectively [88,89]. Conversely low SLPI levels are found in individuals with frequently reported COPD (chronic obstructive pulmonary disease) exacerbations and in females with repeated lower genital tract infections [90,91]. The recent finding that HPV (human papillomavirus) E6 oncoprotein can down-regulate elafin transcription in human keratinocytes [92] provides evidence that the alarm antiproteases influence the host cell–virus interactions. Indeed, as shown above, SLPI has been shown to inhibit HIV infection of human monocytes [80,81].

Alarm antiproteases are anti-inflammatory

A number of in vivo studies have provided evidence for the action of the alarm antiproteases as anti-inflammatory mediators. For example, elafin can suppress inflammation in models of myocardial infarction, atherosclerosis and viral myocarditis [9395]. Similarly, SLPI can reduce tissue damage in several models of lung fibrosis and emphysema [9698], and this action cannot be entirely explained by SLPI's anti-elastase activity [98]. Furthermore, a variety of ‘real-life’ inflammatory pathologies provide evidence to suggest that SLPI has functionally important anti-inflammatory roles in vivo. For example, subjects with active Helicobacter pylori-induced gastritis show reduced SLPI secretion by the antral gastric mucosa [99], and patients with sepsis show elevated circulating SLPI levels, the degree of elevation correlating closely with disease severity markers such as multiple organ dysfunction scores [5,100]. In patients with acute ischaemic stroke, elevated circulating SLPI levels have been documented [22], and this finding has been repeated in a sophisticated animal study which demonstrated elevated brain SLPI mRNA expression after induction of ischaemic stroke in rats [101]. It is of great interest that adenoviral augmentation of SLPI in cortical tissue can directly limit such ischaemic brain injury and improve the functional outcome [101].

In line with these studies, much work has focussed on identifying the mechanisms by which the alarm antiproteases exert their anti-inflammatory effect. Several hypotheses have emerged. (i) Alarm antiproteases might inhibit recruitment of inflammatory cells. For example, elafin can reduce the influx of inflammatory cells into the lung or arterial wall in response to a variety of inflammatory stimuli [102104]. Likewise, SLPI has been shown to reduce eosinophil and neutrophil recruitment in models of eye and joint inflammation respectively [105,106]. (ii) Alarm antiproteases might inhibit the action of inflammatory cells. For example, SLPI has been shown to reduce histamine release from human lung, tonsil and skin mast cells [107]. Furthermore, SLPI reduced degranulation of eosinophils in a model of allergic conjunctivitis and inhibited neutrophil phagocytosis and oxidative burst in an immune complex-induced arthritis model [105,106]. (iii) Alarm antiproteases might act much later in the inflammatory cascade to promote resolution. The clearance of the inflammatory infiltrate through apoptosis and phagocytosis is well described [108], but the cellular mechanisms representing the switch to a resolution phenotype have proved elusive. SLPI might represent one such trigger device for the switch to resolution as murine macrophages engulfing apoptotic cells increase their production of SLPI [109]. Elafin could also participate in the resolution of inflammation by inhibiting cleavage of macrophage CD14 by HNE and, hence, facilitating phagocytosis of apoptotic leucocytes [110]. Furthermore, SLPI can up-regulate macrophage production of the anti-inflammatory/repair type cytokines TGF-β and IL-10 [111]. In this regard, it is notable that TGF-β can down-regulate SLPI production from cultured human bronchial epithelial cells [37] since this may represent an autoregulatory loop whereby SLPI directs production of a resolution-promoting cytokine milieu which, in turn, limits SLPI production to ensure a measured decline of inflammation. Intuitively a gradual decline of inflammation is desirable as it is most compatible with maintenance of an aseptic state and would additionally prevent overload of the clearance mechanisms for spent cells.

As patients with sepsis have elevated circulating SLPI levels and LPS is the key mediator in bacterial endotoxic shock, the interaction of LPS and SLPI has received some attention. SLPI knockout (SLPI−/−) mice show increased susceptibility to endotoxic shock, and macrophages and B-lymphocytes from the same mice show increased activation after administration of LPS when compared with control (SLPI+/+) mice [112]. One mechanism might be that SLPI can inhibit LPS binding to macrophage CD14, preventing the uptake of LPS and reducing subsequent release of inflammatory mediators [113]. However, an intracellular anti-inflammatory mechanism has been proposed by the finding that transfection of a non-secreted form of SLPI, but not the addition of recombinant SLPI, to cultured macrophages suppresses the LPS response [114]. In search of candidate intracellular targets to explain the anti-inflammatory properties of SLPI, we and others have identified the transcription factor NF-κB. NF-κB is thought to be pivotal in the genesis of the inflammatory response as it increases expression of a multitude of pro-inflammatory genes (for a review of the role of NF-κB in acute inflammation see [115]). Overexpression of the SLPI gene in macrophages or endothelial cells can suppress the LPS-, oxLDL (oxidized low-density lipoprotein)- and TNF-α-induced activation of NF-κB. [116,117]. SLPI may protect the NF-κB inhibitor, IκBβ, from proteosome-dependent [118] and -independent [119] degradation thereby explaining suppressed NF-κB activation. Analysis of SLPI mutants has shown that NF-κB activation is only inhibited in rat lungs by SLPI retaining antitrypsin activity [120]. Hence there is the potential that SLPI's anti-inflammatory action on the NF-κB axis may in fact relate to its antiprotease activity, perhaps this time directed against an intracellular protease. Recently, elafin has also been shown to reduce NF-κB signalling in endothelial cells in response to inflammatory stimuli such as oxLDL, LPS and TNF-α [117].

Alarm antiproteases prime the innate immune response

In contrast with the anti-inflammatory description of SLPI and elafin above, other results favour the hypothesis that elafin can recruit, or prime, innate immunity. We believe it is conceptually possible to reconcile these findings by suggesting that the alarm antiproteases will limit harmful inflammation while driving the development of protective innate immunity and related inflammation. This is compatible with the suggestion that SLPI's anti-inflammatory effect relates to its ability to promote gradual resolution of inflammation (described above) [37,109,111]. Furthermore, there is direct experimental evidence that the alarm antiproteases can augment the function of inflammatory cells in innate immunity. For example, expression of the human elafin gene in the murine lung results in an increased influx of inflammatory cells in response to LPS [121,122], and the interaction of elafin with LPS results in an augmentation of the LPS-induced TNF-α response in a murine macrophage cell line [123]. Interestingly, transgenic mice expressing human elafin show lower TNF-α serum levels in response to systemic LPS, adding support to the role of elafin as a dual mediator that is pro-inflammatory and primes innate immunity locally while suppressing systemic inflammation [122].

Although it may appear a paradox to describe the alarm antiproteases on one hand as anti-inflammatory and on the other as activators of innate immunity, it is important to appreciate that details of the cellular mechanisms of these effects are at present incomplete. Hence in one model [54,102] recombinant elafin reduced neutrophil motility whereas, in another [121,122], an LPS-induced neutrophil influx was increased by adenoviral-derived elafin. In proposing suggestions to reconcile these findings, details of the experimental model used must also be considered. For instance, although viral-derived protein gains access to intracellular compartments, administration of recombinant protein is likely to be limited to extracellular contact with the cell membrane. Studies using adenovirus to deliver elafin must also consider the ‘danger signals’ provided by the adenoviral vector.

Alarm antiproteases promote tissue remodelling and wound healing

In a more general sense, the alarm antiproteases have the capacity to enhance host defences by contributing to tissue remodelling and wound healing. For example, elafin seems to be important in the cellular differentiation of foetal to adult submandibular glands [124], and its degree of expression is related to the degree of differentiation in lung carcinomas [125,126]. Meanwhile, SLPI and elafin expression have been noted in response to cutaneous injury in humans [46,127], and SLPI has been shown to be an important endogenous factor in both cutaneous and oral mucosal wound healing [128130]. Moreover, in the search for mechanisms delineating dermal scarring from oral scar-free healing, SLPI has been suggested as an active mediator. For example, SLPI can inhibit fibroblast-mediated collagen gel contraction, an in vitro model of dermal scarring [131]. The molecular mechanisms by which SLPI promotes cellular proliferation have been elucidated using endometrial epithelial cells. SLPI seems to act at the level of gene expression to increase pro-proliferative signals (e.g. cyclin D1) and reduce anti-proliferative signals [e.g. IGFBP-3 (insulin-like growth factor binding protein-3) and lysyl oxidase which inhibits the Ras pathway] [132]. In addition, SLPI is able to augment HGF (hepatocyte growth factor) production by lung fibroblasts and this may contribute to the regulation of mesencymal cell division [133]. Hence a modicum of findings exist to show that the alarm antiproteases can regulate extracellular matrix production, cell growth and differentiation. Therefore, in addition to their protective functions in innate immunity, the alarm antiproteases seem to be involved in resolution and subsequent tissue repair reactions.

ALARM ANTIPROTEASES IN THE ADAPTIVE IMMUNE RESPONSE

The alarm antiproteases were first identified as being able to protect tissues from the damaging effects of proteases released during inflammation and, as discussed above, were later shown to be functionally active in the regulation of both inflammation and innate immunity. Very recently, our group has extended these findings with exciting results to show that the influence of elafin actually extends to include modulation of adaptive immune responses (Figure 2). Other recent findings have suggested mechanisms through which SLPI might be similarly functional in adaptive immunity. For example, prostaglandin E2 is a strong anti-apoptotic survival factor for DC (dendritic cells), skews T-helper lymphocyte cytokine production towards a Th2 immune response and reduces DC production of the monocyte and T-lymphocyte chemokines CCL3 and CCL4 [134136]. SLPI can inhibit LPS-induced production of prostaglandin E2 from monocytes [137] and hence in doing so could facilitate CCL3/4 production and favour a Th1-type immune response.

Roles of elafin in adaptive immunity

Figure 2
Roles of elafin in adaptive immunity

Active local elafin production by inflammatory and epithelial cells leads to modulation of DC phenotype (evidenced by altered morphology and cell-surface markers) hence recruiting adaptive immunity. Open and closed white arrows denote typical DC morphology (immature and mature respectively) after intrapulmonary administration of adenovirus control or adenovirus encoding human elafin, as indicated.

Figure 2
Roles of elafin in adaptive immunity

Active local elafin production by inflammatory and epithelial cells leads to modulation of DC phenotype (evidenced by altered morphology and cell-surface markers) hence recruiting adaptive immunity. Open and closed white arrows denote typical DC morphology (immature and mature respectively) after intrapulmonary administration of adenovirus control or adenovirus encoding human elafin, as indicated.

We have recently shown that elafin favours the development of a Th1-type immune response (A. Roghanian, S. E. Williams, T. A. Sheldrake, T. I. Brown, K. Oberheim, Z. Xing, S.E.M. Howie and J.-M. Sallenave, unpublished work). Overexpression of elafin (either provided as an adenoviral construct or in an elafin-transgenic model) resulted in an increased accumulation of lymphocytes in the lung in response to adenovirus (used as a model antigen). These lymphocytes (and also splenic lymphocytes) showed a Th1 phenotype as indicated by augmented production of TNF-α and IFN-γ (interferon-γ) (A. Roghanian, S. E. Williams, T. A. Sheldrake, T. I. Brown, K. Oberheim, Z. Xing, S. E. M. Howie and J.-M. Sallenave, unpublished work). Furthermore, levels of systemic anti-adenoviral IgG antibodies (and IgG2a, a subtype predominant in Th1 responses) and lung antiadenoviral IgA were increased in elafin-treated mice. Hence we have shown that elafin is a mediator which augments both humoral and cellular aspects of adaptive immunity. Early indications suggest that elafin may exert this effect through an action on DCs, since elafin-treated mice in our system demonstrated both increased numbers and increased activation of lung DCs. Specifically, elafintreated animals show a greater number of intra-pulmonary CD11chigh MHChigh cells, and these DCs have increased expression of the co-stimulatory molecules CD80 and CD86 (A. Roghanian, S. E. Williams, T. A. Sheldrake, T. I. Brown, K. Oberheim, Z. Xing, S. E. M. Howie and J.-M. Sallenave, unpublished work).

Clinical evidence to support a role for elafin in the augmentation of a Th1 phenotype is also available. For example, increased levels of elafin are found in pathological conditions associated with a type I immune response, such as in the bronchoalveolar lavage of farmer's lung sufferers [139] and psoriatic skin [140]. Our group is currently engaged in further studies in sheep to fully characterize elafin's influence on adaptive immunity.

Defensins and cathelicidins

Although we have used alarm antiproteases to show that mediators of innate immunity can exert influence on adaptive immunity, this finding is not without precedent. The alarm antiproteases make up a small part of the mucosal antimicrobial screen [86] and two other antimicrobial peptides are of note as regards adaptive immunity. (i) The defensins are short peptides with a characteristic β-sheet-rich fold and, similarly to SLPI and elafin, are cysteine-rich containing multiple disulphide bonds [141,142]. The position of these disulphide bonds distinguishes two main families of defensins, the α-defensins and β-defensins. The α-defensins are stored in large amounts in azurophilic granules of neutrophils and can be released into the phagolysosome or extracellularly upon neutrophil activation by inflammatory markers [143]. Other α-defensins are expressed by Paneth cells in the small intestine and contribute to the defence against intestinal infection [144]. The β-defensins are expressed by epithelial cells in the lung, intestine and skin as well as monocytes/macrophages and DCs [141,145]. (ii) The cathelicidins are a family of molecules consisting of a conserved N-terminal domain (which is similar to the porcine neutrophil molecule cathelin) and a C-terminal domain with broad spectrum antimicrobial activity [146]. The cathelin domain is cleaved from the pro-molecule to yield the mature species consisting of the C-terminal domain. Only one cathelicidin, hCAP-18/LL-37, is expressed in humans and is produced by neutrophils as well as epithelial cells of skin and lung and some lymphocyte, monocyte and mast cell populations [147151]. Proteinase-3 (which is inhibited by elafin) is mainly responsible for the processing of hCAP-18 in neutrophils [152].

β-Defensins are up-regulated in inflammatory states in response to mediators such as LPS or inflammatory cytokines. Although their role in innate immunity as broad-spectrum antimicrobial activity is well described, their role in adaptive immunity was first suggested in 1999 when Oppenheim and co-workers [153] demonstrated that β-defensins are selectively chemotactic for immature DCs and memory T-lymphocyes. These findings were furthered in 2002 when the same group reported the ability of β-defensin 2 to activate DCs and promote the development of a Th1-skewed immune response [154]. Meanwhile, a role for hCAP-18/LL-37 in adaptive immunity was suggested by the finding that it is not only chemotactic for neutrophils and monocytes, but also T-lymphocytes [155]. A recent study [156] has shown more profound effects of hCAP-18/LL-37 in adaptive immunity by demonstrating that it can modify several aspects of DC differentiation. Perhaps the most intriguing of these findings is that hCAP-18/LL-37-derived DCs secreted Th1-inducing cytokines and stimulated a Th1 polarized (IFN-γ-secreting) T-lymphocyte response in vitro [156].

POTENTIAL ROLES FOR THE ALARM ANTIPROTEASES IN THE INTEGRATION OF THE INNATE AND ADAPTIVE IMMUNE RESPONSES

Although it has long been recognized that the maintenance of self-tolerance is an essential function of the adaptive immune system, it is also evident that an intricate balance between self-tolerance and induction of immunity is essential for the preservation of a valuable immune system, that is one that does more good than harm. Hence a control system is required to determine when a substance is harmful and requires eliminating or when a substance is innocuous and better ignored. Much experimental evidence now exists to support Matzinger's ‘danger’ model as the mechanism by which the immune system makes such choices [2]. In this model, immune reactivity to antigen is dependent not only on the recognition of antigen by lymphocytes, but also on the presence of co-stimulatory signals from APCs (antigen-presenting cells) [2]. In turn, APCs only offer such co-stimulation if they are threatened by microbial stimulation (detected through pattern recognition receptors) or detect other danger (through for instance leakage of ‘alarm signals’ from damaged host cells). The nature of these alarm signals is highly variable, including exogenous (foreign) products as well as endogenous products released from dying cells, but the mechanism of their action is considered to be similar. For reviews on DC function in antigen presentation see [157159].

An additional requirement of these control mechanisms is to identify situations when a stimulus/substance is harmful but an immune response is potentially more dangerous and therefore undesirable. For example, cell-mediated immunity producing ‘delayed type hypersensitivity’ occurs in skin in response to infection but not in the eye where this would be harmful [160]. The danger model currently favours the notion that the APC acts as the key regulator in such decisions by passively collecting and integrating signals from the tissue milieu and then deciding whether to initiate immunity or tolerance. However, as an antigen-specific response develops from a limited number of APC–lymphocyte contacts, it is hard to see how these APCs can be placed to make such an ‘important decision’ for the entire tissue or indeed organism. As such, Matzinger [161] has recently suggested that the tissues themselves, not the APC, should be considered as the ultimate controllers of immunity. That tissue cells could actively secrete biochemical requests for immunity is a radical idea in contrast with the accepted image of immunity as a stand-alone system for protecting tissues. This view gains strong support, at least at epithelial surfaces, from the above-described influences of the antimicrobial peptides in general and the alarm antiproteases in particular on adaptive immunity. Supportive evidence is derived from the observation that the local micro-environment is of absolute importance in shaping DC phenotype [156,162].

Additional work has demonstrated organ-specific effects for a given APC population therein. For example, DCs in the lung produce significant levels of IL-6 which down-regulates IL-12 production, supporting the concept that pulmonary DCs drive a Th1-type response [163]. Hence it seems likely that all parenchymal cells will have the potential to contribute to the induction of immunity not merely by providing danger signals to facilitate co-stimulation by APCs, but rather by actively recruiting and regulating the generation of a specific immune response.

In addition to the micro-environment of the DC, the antigenic stimulus itself also has a bearing over whether the subsequent immune response follows a type 1 or type 2 pattern. Different microbial pathogens have been shown to polarize DCs to become stable secretors of type 1- or type 2-directing cytokines [164,165]. The observation described above that the adenoviral delivery of elafin promotes a Th1 response in the lungs of mice leads one to speculate that this response might be dependent upon the presence of the adenoviral vector itself as a type 1 ‘danger signal’ (even though such an effect has also been described in elafin transgenic mice, independently of the adenoviral mode of delivery) and does not necessarily indicate that elafin will always act as a type 1 adjuvant, regardless of the initiating signal. This could potentially result from a modulation of the IL-10 and/or IL-12 effects on DCs [166168] by the alarm antiproteases, although more experimentation needs to be done to answer this question directly.

We must not forget, however, that alarm antiproteases also have anti-inflammatory activities. In this regard, it is interesting that the supernatants of activated neutrophils can directly activate DCs in vitro [169]. These data suggest a role for the alarm antiproteases whereby they provide a switch to regulate the transition from innate to adaptive control of immunity. Hence, once produced in sufficient quantities within inflamed tissues, the alarm antiproteases could then apply a brake to neutrophil-derived inflammation while simultaneously recruiting adaptive immunity and modulating the genesis of the Th1/Th2 response.

THERAPEUTIC IMPLICATIONS

Vaccine design

The findings outlined above suggest the possibility that alarm antiproteases might be useful as endogenous adjuvants in immunization protocols. An attractive therapeutic approach for the induction of antitumour or antiinfective immunity is the ex vivo manipulation of DCs. This approach has received some attention, for example using GM-CSF (granulocyte/macrophage colony-stimulating factor) fusion proteins to target antigens to, and activate, DCs [170]. Similarly, the use of DNA vaccines encoding for fusion proteins containing murine β-defensin 2 or 3 linked to non-immunogenic tumour antigens have been shown to elicit both protective and therapeutic immune responses against lymphoma in vivo [171]. We have shown (A. Roghanian, S. E. Williams, T. A. Sheldrake, T. I. Brown, K. Oberheim, Z. Xing, S. E. M. Howie and J.-M. Sallenave, unpublished work) the potential efficacy of the alarm antiproteases in a serial immunization protocol whereby protective anti-adenovirus immunity generated in the presence of elafin was of equal magnitude to that generated in the presence of GM-CSF. The adenoviral delivery of GM-CSF has been demonstrated to result in enhanced protective immunity against such Th1-inducing pathogens as Chlamydia, Mycobacterium tuberculosis and human papilloma virus [170,172,173] and, as elafin potentially augments a Th1-type response, it might be of use in vaccine protocols against these intracellular pathogens. Furthermore, elafin might be more desirable as an adjuvant than molecules such as GM-CSF as it is likely to show a better safety profile (GM-CSF tends to stimulate fibrosis in the lung [174]) and might be suitable for direct administration to patients (hence avoiding the expense of ex vivo procedures).

Treatment of infections

As antibiotic resistance becomes more prevalent among all classes of micro-organisms, the search for alternative medicines is becoming increasingly important. The heterogeneous group of antimicrobial peptides represent interesting candidates for drug development and, indeed, several are in clinical trials [23,175]. The alarm antiproteases demonstrate a number of theoretical advantages over conventional antibiotics [23]. As their antimicrobial function probably involves interaction with the cell membrane, and membrane changes significantly impact upon an organism's chance of survival, the emergence of resistance is likely to be rare. Furthermore, the alarm antiproteases demonstrate a number of anti-inflammatory effects and can limit the systemic inflammatory response to bacterial products such as LPS and LTA [112114,116,118]. Members of the elafin family (and indeed other trappins [6]) contain a transglutaminase substrate domain of varying length. The presence of this domain may be of importance in their use as antimicrobial (or perhaps more accurately immunomodulating) compounds. Firstly, this domain allows cross-linking to extracellular proteins via transglutamination [52,53], hence potentially prolonging the period of activity of the protein at a local level. Secondly, this domain acts as a competitive inhibitor of transglutaminase and therefore as an indirect inhibitor of phospholipase A2 [172]. This leads to a decrease in the arachidonic acid cascade and a consequent anti-inflammatory effect locally.

We have shown directly that the adenoviral delivery of human elafin to the lung in murine models of both P. aeruginosa- and Staph. aureus-induced pneumonia significantly protected the lungs against bacterial damage [74,176]. Current work in our laboratory is concerned with the value of viral delivery of ovine elafin in a similar model in sheep.

CONCLUSIONS

In summary, the alarm antiproteases SLPI and elafin have been shown to have multiple bioactive functions, including inhibition of proteolytic enzymes at times of inflammation, suppression of harmful inflammation and stimulation of innate immune defences. Moreover elafin has been shown to actively recruit adaptive immunity and guide the generation of a Th1-skewed immune response. The magnitude of elafin's effect on immunity, and the demonstration that other antimicrobial molecules released by tissue cells can functionally alter adaptive immunity, lends support to the hypothesis that tissue cells themselves occupy a position of importance in directing adaptive immunity. In this context, further examination of the functions of the other elafin/trappin family members is eagerly awaited. The description of the alarm antiproteases as molecules with such pleiotropic functions suggests that they might, in the future, be candidate drugs for use in vaccination protocols or the treatment of infections.

Abbreviations

     
  • APC

    antigen-presenting cell

  •  
  • DC

    dendritic cell

  •  
  • GM-CSF

    granulocyte/macrophage colony-stimulating factor

  •  
  • HNE

    human neutrophil elastase

  •  
  • IFN-γ

    interferon-γ

  •  
  • IL

    interleukin

  •  
  • LPS

    lipopolysaccharide

  •  
  • NF-κB

    nuclear factor κB

  •  
  • oxLDL

    oxidized low-density lipoprotein

  •  
  • α1-PI

    α1-proteinase inhibitor

  •  
  • SLPI

    secretory leucocyte protease inhibitor

  •  
  • TGF-β

    transforming growth factor-β

  •  
  • TNF

    tumour necrosis factor

  •  
  • WAP

    ‘whey acid protein’

We thank the Wolfson Foundation for sponsoring S.E.W. The Wellcome Trust and the MRC are acknowledged for providing studentships to T.I.B. and A.R. respectively. We also thank the Norman Salvesen Emphysema Research Trust, the MRC and the Wellcome Trust for sponsoring research performed in J.-M.S.'s laboratory.

References

References
1
Pancer
 
Z.
Amemiya
 
C. T.
Ehrhardt
 
G. R. A.
, et al 
Somatic diversification of variable lymphocyte receptors in the agnathan sea lamrey
Nature (London)
2004
, vol. 
430
 (pg. 
174
-
180
)
2
Matzinger
 
P.
 
Tolerance, danger, and the extended family
Annu. Rev. Immunol.
1994
, vol. 
12
 (pg. 
991
-
1045
)
3
Dallegri
 
F.
Ottonello
 
L.
 
Tissue injury in neutrophilic inflammation
Inflamm. Res.
1997
, vol. 
46
 (pg. 
382
-
391
)
4
McElvaney
 
N. G.
Crystal
 
R. G.
 
Crystal
 
R. G.
West
 
J. B.
Weibel
 
E. R.
Barnes
 
P. J.
 
Proteases and Lung Injury
The Lung: Scientific Foundations
1997
Philadelphia
Lippincott-Raven
(pg. 
2205
-
2217
)
5
Sallenave
 
J. M.
 
The role of secretory leukocyte proteinase inhibitor and elafin (elastase-specific inhibitor/skin-derived antileukoprotease) as alarm antiproteases in inflammatory lung disease
Respir. Res.
2000
, vol. 
1
 (pg. 
87
-
92
)
6
Schalkwijk
 
J.
Wiedow
 
O.
Hirose
 
S.
 
The trappin gene family: proteins defined by an N-terminal transglutaminase substrate domain and a C-terminal four-disulphide core
Biochem. J.
1999
, vol. 
340
 (pg. 
569
-
577
)
7
Hochstrasser
 
K.
Albrecht
 
G. J.
Schonberger
 
O. L.
Rasche
 
B.
Lempart
 
K.
 
An elastase-specific inhibitor from human bronchial mucus. Isolation and characterization
Hoppe Seylers Z. Physiol. Chem.
1981
, vol. 
362
 (pg. 
1369
-
1375
)
8
Kramps
 
J. A.
Klasen
 
E. C.
 
Characterization of a low molecular weight anti-elastase isolated from human bronchial secretion
Exp. Lung Res.
1985
, vol. 
9
 (pg. 
151
-
165
)
9
Sallenave
 
J. M.
Ryle
 
A. P.
 
Purification and characterization of elastase-specific inhibitor. Sequence homology with mucus proteinase inhibitor
Biol. Chem. Hoppe Seyler
1991
, vol. 
372
 (pg. 
13
-
21
)
10
Wiedow
 
O.
Schroder
 
J. M.
Gregory
 
H.
Young
 
J. A.
Christophers
 
E.
 
Elafin: an elastase-specific inhibitor of human skin. Purification, characterization, and complete amino acid sequence
J. Biol. Chem.
1990
, vol. 
265
 (pg. 
14791
-
14795
)
11
Sallenave
 
J. M.
Silva
 
A.
 
Characterization and gene sequence of the precursor of elafin, an elastase-specific inhibitor in bronchial secretions
Am. J. Respir. Cell. Mol. Biol.
1993
, vol. 
8
 (pg. 
439
-
445
)
12
Molhuizen
 
H. O.
Alkemade
 
H. A.
Zeeuwen
 
P. L.
, et al 
SKALP/elafin: an elastase inhibitor from cultured human keratinocytes. Purification, cDNA sequence, and evidence for transglutaminase cross-linking
J. Biol. Chem.
1993
, vol. 
268
 (pg. 
12028
-
12032
)
13
Schalkwijk
 
J.
de Roo
 
C.
de Jongh
 
G. J.
 
Skin-derived antileukoproteinase (SKALP), an elastase inhibitor from human keratinocytes. Purification and biochemical properties
Biochim. Biophys. Acta
1991
, vol. 
1096
 (pg. 
148
-
154
)
14
Sallenave
 
J. M.
Shulmann
 
J.
Crossley
 
J.
Jordana
 
M.
Gauldie
 
J.
 
Regulation of secretory leukocyte proteinase inhibitor (SLPI) and elastase-specific inhibitor (ESI/elafin) in human airway epithelial cells by cytokines and neutrophilic enzymes
Am. J. Respir. Cell. Mol. Biol.
1994
, vol. 
11
 (pg. 
733
-
741
)
15
Brown
 
T. I.
Mistry
 
R.
Collie
 
D. D.
Tate
 
S.
Sallenave
 
J. M.
 
Trappin ovine molecule (TOM), the ovine ortholog of elafin, is an acute phase reactant in the lung
Physiol. Genomics
2004
, vol. 
19
 (pg. 
11
-
21
)
16
Alkemade
 
J. A.
Molhuizen
 
H. O.
Ponec
 
M.
, et al 
SKALP/elafin is an inducible proteinase inhibitor in human epidermal keratinocytes
J. Cell. Sci.
1994
, vol. 
107
 (pg. 
2335
-
2342
)
17
Betsuyaku
 
T.
Takeyabu
 
K.
Tanino
 
M.
Nishimura
 
M.
 
Role of secretory leukocyte protease inhibitor in the development of subclinical emphysema
Eur. Respir. J.
2002
, vol. 
19
 (pg. 
1051
-
1057
)
18
Kuijpers
 
A. L.
Zeeuwen
 
P. L.
de Jongh
 
G. J.
, et al 
Skin-derived antileukoproteinase (SKALP) is decreased in pustular forms of psoriasis. A clue to the pathogenesis of pustule formation?
Arch. Dermatol. Res.
1996
, vol. 
288
 (pg. 
641
-
647
)
19
Kuijpers
 
A. L.
Schalkwijk
 
J.
Rulo
 
H. F.
, et al 
Extremely low levels of epidermal skin-derived antileucoproteinase/elafin in a patient with impetigo herpetiformis
Br. J. Dermatol.
1997
, vol. 
137
 (pg. 
123
-
129
)
20
Lin
 
A. L.
Johnson
 
D. A.
Stephan
 
K. T.
Yeh
 
C. K.
 
Salivary secretory leukocyte protease inhibitor increases in HIV infection
J. Oral Pathol. Med.
2004
, vol. 
33
 (pg. 
410
-
416
)
21
Zelvyte
 
I.
Wallmark
 
A.
Piitulainen
 
E.
Westin
 
U.
Janciauskiene
 
S.
 
Increased plasma levels of serine proteinase inhibitors in lung cancer patients
Anticancer Res.
2004
, vol. 
24
 (pg. 
241
-
247
)
22
Ilzecka
 
J.
Stelmasiak
 
Z.
 
Increased serum levels of endogenous protectant secretory leukocyte protease inhibitor in acute ischemic stroke patients
Cerebrovasc. Dis.
2002
, vol. 
13
 (pg. 
38
-
42
)
23
Hiemestra
 
P. S.
Fernie-King
 
B. A.
McMichael
 
J.
Lachmann
 
P. J.
Sallenave
 
J. M.
 
Antimicrobial peptides: mediators of innate immunity as templates for the development of novel anti-infective and immune therapeutics
Curr. Pharm. Des.
2004
, vol. 
10
 (pg. 
2891
-
2905
)
24
Zitnik
 
R. J.
Zhang
 
J.
Kashem
 
M. A.
, et al 
The cloning and characterization of a murine secretory leukocyte protease inhibitor cDNA
Biochem. Biophys. Res. Commun.
1997
, vol. 
232
 (pg. 
687
-
697
)
25
Song
 
X. Y.
Zeng
 
L.
Wenwen
 
J.
, et al 
Secretory leukocyte protease inhibitor suppresses the inflammation and joint damage of bacterial cell wall-induced arthritis
J. Exp. Med.
1999
, vol. 
190
 (pg. 
535
-
542
)
26
Farmer
 
S. J.
Fliss
 
A. E.
Simmen
 
R. C.
 
Complementary DNA cloning and regulation of expression of the messenger RNA encoding a pregnancy-associated porcine uterine protein related to human antileukoproteinase
Mol. Endocrinol.
1990
, vol. 
4
 (pg. 
1095
-
1104
)
27
Brown
 
T. I.
Mistry
 
R.
Gray
 
R.
Imrie
 
M.
Collie
 
D. D.
Sallenave
 
J.-M.
 
Characterization of the ovine ortholog of secretory leukoprotease inhibitor
Mamm. Genome
2005
, vol. 
16
 (pg. 
621
-
630
)
28
Grütter
 
M. G.
Fendrich
 
G.
Huber
 
R.
Bode
 
W.
 
The 2.5 Å X-ray crystal structure of the acid-stable proteinase inhibitor from human mucous secretions analysed in its complex with bovine α-chymotrypsin
EMBO J.
1988
, vol. 
7
 (pg. 
345
-
351
)
29
Saitoh
 
H.
Masuda
 
T.
Shimura
 
S.
Fushimi
 
T.
Shirato
 
K.
 
Secretion and gene expression of secretory leukocyte protease inhibitor by human airway submucosal glands
Am. J. Physiol. Lung Cell. Mol. Physiol.
2001
, vol. 
280
 (pg. 
L79
-
L87
)
30
Si-Tahar
 
M.
Merline
 
D.
Sitaraman
 
S.
Madara
 
J. L.
 
Constitutive and regulated secretion of secretory leukocyte proteinase inhibitor by human intestinal epithelial cells
Gastroenterology
2000
, vol. 
118
 (pg. 
1061
-
1071
)
31
Zhang
 
Q.
Shimoya
 
K.
Moriyama
 
A.
, et al 
Production of secretory leukocyte protease inhibitor by human amniotic membranes and regulation of its concentration in amniotic fluid
Mol. Hum. Reprod.
2001
, vol. 
7
 (pg. 
573
-
579
)
32
Sallenave
 
J. M.
Silva
 
A.
Marsden
 
M. E.
Ryle
 
A. P.
 
Secretion of mucus proteinase inhibitor and elafin by Clara cell and type II pneumocyte cell lines
Am. J. Respir. Cell. Mol. Biol.
1993
, vol. 
8
 (pg. 
126
-
133
)
33
Westin
 
U.
Polling
 
A.
Ljungkrantz
 
I.
Ohlsson
 
K.
 
Identification of SLPI (secretory leukocyte protease inhibitor) in human mast cells using immunohistochemistry and in situ hybridisation
Biol. Chem.
1999
, vol. 
380
 (pg. 
489
-
493
)
34
Sallenave
 
J. M.
Si-Tahar
 
M.
Cox
 
G.
Chignard
 
M.
Gauldie
 
J.
 
Secretory leukocyte proteinase inhibitor is a major leukocyte elastase inhibitor in human neutrophils
J. Leukocyte Biol.
1997
, vol. 
61
 (pg. 
695
-
702
)
35
Mihaila
 
A.
Tremblay
 
G. M.
 
Human alveolar macrophages express elafin and secretory leukocyte protease inhibitor
Z. Naturforsch.
2001
, vol. 
56
 (pg. 
291
-
297
)
36
Maruyama
 
M.
Hay
 
J. G.
Yoshimura
 
K.
Chu
 
C. S.
Crystal
 
R. G.
 
Modulation of secretory leukoprotease inhibitor gene expression in human bronchial epithelial cells by phorbol ester
J. Clin. Invest.
1994
, vol. 
94
 (pg. 
368
-
375
)
37
Jaumann
 
F.
Elssner
 
A.
Mazur
 
G.
Dobmann
 
S.
Vogelmeirer
 
C.
 
Transforming growth factor-β1 is a potent inhibitor of secretory leukoprotease inhibitor expression in a bronchial epithelial cell line. Munich Lung Transplant Group
Eur. Respir. J.
2000
, vol. 
15
 (pg. 
1052
-
1057
)
38
Sorensen
 
O. E.
Cowland
 
J. B.
Theilgaard-Monch
 
K.
Liu
 
L.
Ganz
 
T.
Borregaard
 
N.
 
Wound healing and expression of antimicrobial peptides/polypeptides in human keratinocytes, a consequence of common growth factors
J. Immunol.
2003
, vol. 
170
 (pg. 
5583
-
5589
)
39
van Wetering
 
S.
van der Linden
 
A. C.
van Sterkenburg
 
M. A.
Rabe
 
K. F.
Schalkwijk
 
J.
Hiemestra
 
P. S.
 
Regulation of secretory leukocyte proteinase inhibitor (SLPI) production by human bronchial epithelial cells: increase in cell-associated SLPI by neutrophil elastase
J. Invest. Med.
2000
, vol. 
48
 (pg. 
359
-
366
)
40
van Wetering
 
S.
van der Linden
 
A. C.
van Sterkenburg
 
M. A.
, et al 
Regulation of SLPI and elafin release from bronchial epithelial cells by neutrophil defensins
Am. J. Physiol. Lung Cell. Mol. Physiol.
2000
, vol. 
278
 (pg. 
L51
-
L58
)
41
Jin
 
F.
Nathan
 
C. F.
Radzioch
 
D.
Ding
 
A.
 
Lipopolysaccharide-related stimuli induce expression of the secretory leukocyte protease inhibitor, a macrophage-derived lipopolysaccharide inhibitor
Infect. Immun.
1998
, vol. 
66
 (pg. 
2447
-
2452
)
42
Fleming
 
D. C.
King
 
A. E.
Williams
 
A. R.
Critchley
 
H. O.
Kelly
 
R. W.
 
Hormonal contraception can suppress natural antimicrobial gene transcription in human endometrium
Fertil. Steril.
2003
, vol. 
79
 (pg. 
856
-
863
)
43
King
 
A. E.
Morgan
 
K.
Sallenave
 
J.-M.
Kelly
 
R. W.
 
Differential regulation of secretory leukocyte protease inhibitor and elafin by progesterone
Biochem. Biophys. Res. Commun.
2003
, vol. 
310
 (pg. 
594
-
599
)
44
Boudier
 
C.
Bieth
 
J. G.
 
The proteinase: mucus proteinase inhibitor binding stoichiometry
J. Biol. Chem.
1992
, vol. 
267
 (pg. 
4370
-
4375
)
45
Kramps
 
J. A.
Te Boekhorst
 
A. H.
Fransen
 
A. H.
Ginsel
 
L. A.
Dijkman
 
J. H.
 
Antileukoprotease is associated with elastin fibres in the extracellular matrix of the human lung. An immunoelectron microscope study
Am. Rev. Respir. Dis.
1989
, vol. 
140
 (pg. 
471
-
476
)
46
Wingens
 
M.
van Bergen
 
B. H.
Hiemstra
 
P. S.
, et al 
Induction of SLPI (ALP/HUSI-I) in epidermal keratinocytes
J. Invest. Dermatol.
1998
, vol. 
111
 (pg. 
996
-
1002
)
47
Cavarra
 
E.
Lucattelli
 
M.
Gambelli
 
F.
, et al 
Human SLPI inactivation after cigarette smoke exposure in a new in vivo model of pulmonary oxidative stress
Am. J. Physiol. Lung Cell. Mol. Physiol.
2001
, vol. 
281
 (pg. 
L412
-
L417
)
48
Ayad
 
M. S.
Knight
 
K. R.
Burdon
 
J. G.
Brenton
 
S.
 
Secretory leukocyte proteinase inhibitor, α-1-antitrypsin deficiency and emphysema: preliminary study, speculation and an hypothesis
Respirology
2003
, vol. 
8
 (pg. 
175
-
180
)
49
Taggart
 
C. C.
Lowe
 
G. J.
Greene
 
C. M.
, et al 
Cathepsin B, L, and S cleave and inactivate secretory leucoprotease inhibitor
J. Biol. Chem.
2001
, vol. 
276
 (pg. 
33345
-
33352
)
50
Sponer
 
M.
Nick
 
H. P.
Schnebli
 
H. P.
 
Different susceptibility of elastase inhibitors to inactivation by proteinases from Staphylococcus aureus and Pseudomonas aeruginosa
Biol. Chem. Hoppe Seyler
1991
, vol. 
372
 (pg. 
963
-
970
)
51
Saheki
 
T.
Ito
 
F.
Hagiwara
 
H.
, et al 
Primary structure of the human elafin precursor preproelafin deduced from the nucleotide sequence of its gene and the presence of unique repetitive sequences in the prosegment
Biochem. Biophys. Res. Commun.
1992
, vol. 
185
 (pg. 
240
-
245
)
52
Francart
 
C.
Dauchez
 
M.
Alix
 
A. J.
Lippens
 
G.
 
Solution structure of R-elafin, a specific inhibitor of elastase
J. Mol. Biol.
1997
, vol. 
268
 (pg. 
666
-
677
)
53
Nara
 
K.
Ito
 
S.
Ito
 
T.
, et al 
Elastase inhibitor elafin is a new type of proteinase inhibitor which has transglutaminase-mediated anchoring sequence termed ‘cementoin’
J. Biochem. (Tokyo)
1994
, vol. 
115
 (pg. 
441
-
448
)
54
Tremblay
 
G. M.
Vachon
 
E.
Larouche
 
C.
Bourbonnais
 
Y.
 
Inhibition of human neutrophil elastase-induced acute lung injury in hamsters by recombinant human pre-elafin (trappin-2)
Chest
2002
, vol. 
121
 (pg. 
582
-
588
)
55
Tremblay
 
G. M.
Wolbink
 
A. M.
Cormier
 
Y.
Hack
 
C. E.
 
Granzyme activity in the inflammed lung is not controlled by endogenous serine proteinase inhibitors
J. Immunol.
2000
, vol. 
165
 (pg. 
3966
-
3969
)
56
Pfundt
 
R.
van Ruissen
 
F.
van Vlijment-Willems
 
I. M.
, et al 
Constitutive and inducible expression of SKALP/elafin provides anti-elastase defense in human epithelia
J. Clin. Invest.
1996
, vol. 
98
 (pg. 
1389
-
1399
)
57
Nonomura
 
K.
Yamanishi
 
K.
Yasuno
 
H.
Nara
 
K.
Hirose
 
S.
 
Up-regulation of elafin/SKALP gene expression in psoriatic epidermis
J. Invest. Dermatol.
1994
, vol. 
103
 (pg. 
88
-
91
)
58
Sallenave
 
J. M.
Marsden
 
M. D.
Ryle
 
A. P.
 
Isolation of elafin and elastase-specific inhibitor (ESI) from bronchial secretions. Evidence of sequence homology and immunological cross-reactivity
Biol. Chem. Hoppe Seyler
1992
, vol. 
373
 (pg. 
27
-
33
)
59
Suzuki
 
Y.
Furukawa
 
M.
Abe
 
J.
Kasiwagi
 
M.
Hirose
 
S.
 
Localization of porcine trappin-2 (SKALP/elafin) in trachea and large intestine by in situ hybridization and immunohistochemistry
Histochem. Cell. Biol.
2000
, vol. 
114
 (pg. 
15
-
20
)
60
King
 
A. E.
Critchley
 
H. O.
Sallenave
 
J. M.
Kelly
 
R. W.
 
Elafin in human endometrium: an antiprotease and antimicrobial molecule expressed during menstruation
J. Clin. Endocrinol. Metab.
2003
, vol. 
88
 (pg. 
4426
-
4431
)
61
Tanaka
 
N.
Fujioka
 
A.
Tajima
 
S.
Ishibashi
 
A.
Hirose
 
S.
 
Elafin is induced in epidermis in skin disorders with dermal neutrophilic infiltration: interleukin-1β and tumour necrosis factor-α stimulate its secretion in vitro
Br. J. Dermatol.
2000
, vol. 
143
 (pg. 
728
-
732
)
62
Pfundt
 
R.
van Vlijmen-Willems
 
I.
Bergers
 
M.
Wingens
 
M.
Cloin
 
W.
Schalkwijk
 
J.
 
In situ demonstration of phosphorylated c-jun and p38 MAP kinase in epidermal keratinocytes following ultraviolet B irradiation of human skin
J. Pathol.
2001
, vol. 
193
 (pg. 
248
-
255
)
63
Pfundt
 
R.
Wingens
 
M.
Bergers
 
M.
Zweers
 
M.
Frenken
 
M.
Schalkwijk
 
J.
 
TNF-α and serum induce SKALP/elafin gene expression in human keratinocytes by a p38 MAP kinase-dependent pathway
Arch. Dermatol. Res.
2000
, vol. 
292
 (pg. 
180
-
187
)
64
Bingle
 
T.
Tetley
 
T. D.
Bingle
 
C. D.
 
Cytokine-mediated induction of the human elafin gene in pulmonary epithelial cells is regulated by nuclear factor-κB
Am. J. Respir. Cell Mol. Biol.
2001
, vol. 
25
 (pg. 
84
-
91
)
65
van Seuningen
 
I.
Audie
 
J. P.
Gosselin
 
B.
Lafitte
 
J. J.
Davril
 
M.
 
Expression of human mucous proteinase inhibitor in respiratory tract: a study by in situ hybridization
J. Histochem. Cytochem.
1995
, vol. 
43
 (pg. 
645
-
648
)
66
Reid
 
P. T.
Marsden
 
M. E.
Cunningham
 
G. A.
Haslett
 
C.
Sallenave
 
J. M.
 
Human neutrophil elastase regulates the expression and secretion of elafin (elastase-specific inhibitor) in type II alveolar epithelial cells
FEBS Lett.
1999
, vol. 
457
 (pg. 
33
-
37
)
67
Zeeuwen
 
P. L.
Hendriks
 
W.
de Jong
 
W. W.
Schalkwijk
 
J.
 
Identification and sequence analysis of two new members of the SKALP/elafin and SPAI-2 gene family. Biochemical properties of the transglutaminase substrate motif and suggestions for a new nomenclature
J. Biol. Chem.
1997
, vol. 
272
 (pg. 
20471
-
20478
)
68
Furutani
 
Y.
Kato
 
A.
Yasue
 
H.
, et al 
Evolution of the trappin multigene family in the Suidae
J. Biochem. (Tokyo)
1998
, vol. 
124
 (pg. 
491
-
502
)
69
Furukawa
 
M.
Suzuki
 
Y.
Ghoneim
 
M. A.
Tachibana
 
S.
Hirose
 
S.
 
Cryptic origin of SPAI, a plasma protein with a transglutaminase substrate domain and the WAP motif, revealed by in situ hybridization and immunohistochemistry
J. Biol. Chem.
1996
, vol. 
271
 (pg. 
29517
-
29520
)
70
Tamechika
 
I.
Itakura
 
M.
Saruta
 
Y.
, et al 
Accelerated evolution in inhibitor domains of porcine elafin family
J. Biol. Chem.
1996
, vol. 
271
 (pg. 
7012
-
7018
)
71
Gipson
 
T. S.
Bless
 
N. M.
Shanley
 
T. P.
, et al 
Regulatory effects of endogenous protease inhibitors in acute lung inflammatory injury
J. Immunol.
1999
, vol. 
162
 (pg. 
3653
-
3662
)
72
Tralau
 
T.
Meyer-Hoffert
 
U.
Schroder
 
J. M.
Wiedow
 
O.
 
Human leukocyte elastase and cathepsin G are specific inhibitors of C5a-dependent neutrophil enzyme release and chemotaxis
Exp. Dermatol.
2004
, vol. 
13
 (pg. 
316
-
325
)
73
Hiemstra
 
P. S.
Maassen
 
R. J.
Stolk
 
J.
, et al 
Antibacterial activity of antileukoprotease
Infect. Immun.
1996
, vol. 
64
 (pg. 
4250
-
4254
)
74
Simpson
 
A. J.
Wallace
 
W. A.
Marsden
 
M. E.
, et al 
Adenoviral augmentation of elafin protects the lung against acute injury mediated by activated neutrophils and bacterial infection
J. Immunol.
2001
, vol. 
167
 (pg. 
1778
-
1786
)
75
Simpson
 
A. J.
Maxwell
 
A. I.
Govan
 
J. R.
Haslett
 
C.
Sallenave
 
J. M.
 
Elafin (elastase-specific inhibitor) has anti-microbial activity against Gram-positive and Gram-negative respiratory pathogens
FEBS Lett.
1999
, vol. 
452
 (pg. 
309
-
313
)
76
Wiedow
 
O.
Harder
 
J.
Bartels
 
J.
Streit
 
V.
Christophers
 
E.
 
Antileukoprotease in human skin: an antibiotic peptide constitutively produced by keratinocytes
Biochem. Biophys. Res. Commun.
1998
, vol. 
248
 (pg. 
904
-
909
)
77
Fernie-King
 
B. A.
Seilly
 
D. J.
Davies
 
A.
Lachmann
 
P. J.
 
Streptococcal inhibitor of complement inhibits two additional components of the mucosal innate immune system: secretory leukocyte proteinase inhibitor and lysozyme
Infect. Immun.
2002
, vol. 
70
 (pg. 
4908
-
4916
)
78
Tomee
 
J. F.
Hiemstra
 
P. S.
Heinzel-Wieland
 
R.
Kauffman
 
H. F.
 
Antileukoprotease: an endogenous protein in the innate mucosal defense against fungi
J. Infect. Dis.
1997
, vol. 
176
 (pg. 
740
-
747
)
79
Meyer-Hoffert
 
U.
Wichmann
 
N.
Schwichtenberg
 
L.
White
 
P. C.
Wiedow
 
O.
 
Supernatants of Pseudomonas aeruginosa induce the Pseudomonas-specific antibiotic elafin in human keratinocytes
Exp. Dermatol.
2003
, vol. 
12
 (pg. 
418
-
425
)
80
Shugars
 
D. C.
 
Endogenous mucosal antiviral factors of the oral cavity
J. Infect. Dis.
1999
, vol. 
179
 (pg. 
S431
-
S435
)
81
Wahl
 
S. M.
McNeely
 
T. B.
Janoff
 
E. N.
, et al 
Secretory leukocyte protease inhibitor (SLPI) in mucosal fluids inhibits HIV-1
Oral Dis.
1997
, vol. 
3
 (pg. 
S64
-
S69
)
82
McNeely
 
T. B.
Dealy
 
M.
Dripps
 
D. J.
, et al 
Secretory leukocyte protease inhibitor: a human saliva protein exhibiting anti-human immunodeficiency virus 1 activity in vitro
J. Clin. Invest.
1995
, vol. 
96
 (pg. 
456
-
464
)
83
McNeely
 
T. B.
Shugars
 
D. C.
Rosendahl
 
M.
, et al 
Inhibition of human immunodeficiency virus type 1 infectivity by secretory leukocyte protease inhibitor occurs prior to viral reverse transcription
Blood
1997
, vol. 
90
 (pg. 
1141
-
1149
)
84
Ma
 
G.
Greenwell-Wild
 
T.
Lei
 
K.
, et al 
Secretory leukocyte protease inhibitor binds to annexin II, a cofactor for macrophage HIV-1 infection
J. Exp. Med.
2004
, vol. 
200
 (pg. 
1337
-
1346
)
85
King
 
A. E.
Fleming
 
D. C.
Critchley
 
H. O.
Kelly
 
R. W.
 
Regulation of natural antibiotic expression by inflammatory mediators and mimics of infection in human endometrial epithelial cells
Mol. Hum. Reprod.
2002
, vol. 
8
 (pg. 
341
-
349
)
86
Levy
 
O.
 
Antimicrobial proteins and peptides: anti-infective molecules of mammalian leukocytes
J. Leukocyte Biol.
2004
, vol. 
76
 (pg. 
909
-
925
)
87
Chattopadhyay
 
A.
Gray
 
L. R.
Patton
 
L. L.
, et al 
Salivary secretory leukocyte protease inhibitor and oral candidiasis in human immunodeficiency virus type 1-infected persons
Infect. Immun.
2004
, vol. 
72
 (pg. 
1956
-
1963
)
88
Farquhar
 
C.
VanCott
 
T. C.
Mbori-Ngacha
 
D. A.
, et al 
Salivary secretory leukocyte protease inhibitor is associated with reduced transmission of human immunodeficiency virus type 1 through breast milk
J. Infect. Dis.
2002
, vol. 
186
 (pg. 
1173
-
1176
)
89
Pillay
 
K.
Coutsoudis
 
A.
Agadzi-Naqvi
 
A. K.
, et al 
Secretory leukocyte protease inhibitor in vaginal fluids and perinatal human immunodeficiency virus type 1 transmission
J. Infect. Dis.
2001
, vol. 
183
 (pg. 
653
-
656
)
90
Gompertz
 
S.
Bayley
 
D. L.
Hill
 
S. L.
Stockley
 
R. A.
 
Relationship between airway inflammation and the frequency of exacerbations in patients with smoking related COPD
Thorax
2001
, vol. 
56
 (pg. 
36
-
41
)
91
Draper
 
D. L.
Landers
 
D. V.
Krohn
 
M. A.
, et al 
Levels of vaginal secretory leukocyte protease inhibitor are decreased in women with lower reproductive tract infections
Am. J. Obstet. Gynaecol.
2000
, vol. 
183
 (pg. 
1243
-
1248
)
92
Duffy
 
C. L.
Phillips
 
S. L.
Klingelhutz
 
A. J.
 
Microarray analysis identifies differentiation-associated genes regulated by human papillomavirus type 16 E6
Virology
2003
, vol. 
314
 (pg. 
196
-
205
)
93
Ohta
 
K.
Nakajima
 
T.
Cheah
 
A. Y.
, et al 
Elafin-overexpressing mice have improved cardiac function after myocardial infarction
Am. J. Physiol. Heart Circ. Physiol.
2004
, vol. 
287
 (pg. 
H286
-
H292
)
94
O'Blenes
 
S. B.
Zaidi
 
S. H.
Cheah
 
A. Y.
McIntyre
 
B.
Kaneda
 
Y.
Rabinovitch
 
M.
 
Gene transfer of the serine elastase inhibitor elafin protects against vein graft degeneration
Circulation
2000
, vol. 
102
 (pg. 
III289
-
III295
)
95
Zaidi
 
S. H.
Hui
 
C.
Cheah
 
A. Y.
, et al 
Targeted overexpression of elafin protects mice against cardiac dysfunction and mortality following viral myocarditis
J. Clin. Invest.
1999
, vol. 
103
 (pg. 
1211
-
1219
)
96
Mulligan
 
M. S.
Desrochers
 
P. E.
Chinnaiyan
 
A. M.
, et al 
In vivo suppression of immune complex-induced alveolitis by secretory leukoproteinase inhibitor and tissue inhibitor of metalloproteinases 2
Proc. Natl. Acad. Sci. U.S.A.
1993
, vol. 
90
 (pg. 
11523
-
11527
)
97
Rudolphus
 
A.
Stolk
 
J.
Dijkman
 
J. H.
Kramps
 
J. A.
 
Inhibition of lipopolysaccharide induced pulmonary emphysema by intratracheally instilled recombinant secretory leukocyte proteinase inhibitor
Am. Rev. Respir. Dis.
1993
, vol. 
147
 (pg. 
442
-
447
)
98
Mitsuhashi
 
H.
Asano
 
S.
Nonaka
 
T.
Hamamura
 
I.
Masuda
 
K. I.
Kiyoki
 
M.
 
Administration of truncated secretory leukoprotease inhibitor ameliorates bleomycin-induced pulmonary fibrosis in hamsters
Am. J. Respir. Crit. Care Med.
1996
, vol. 
153
 (pg. 
369
-
374
)
99
Wex
 
T.
Treiber
 
G.
Nilius
 
M.
Vieth
 
M.
Roessner
 
A.
Malfertheiner
 
P.
 
Helicobacter pylori-mediated gastritis induces local downregulation of secretory leukocyte protease inhibitor in the antrum
Infect. Immun.
2004
, vol. 
72
 (pg. 
2383
-
2385
)
100
Grobmyer
 
S. R.
Barie
 
P. S.
Nathan
 
C. F.
 
Secretory leukocyte protease inhibitor, an inhibitor of neutrophil activation, is elevated in serum in human sepsis and experimental endotoxemia
Crit. Care Med.
2000
, vol. 
28
 (pg. 
1276
-
1282
)
101
Wang
 
X.
Li
 
X.
Xu
 
L.
, et al 
Up-regulation of secretory leukocyte protease inhibitor (SLPI) in the brain after ischemic stroke: adenoviral expression of SLPI protects brain from ischemic injury
Mol. Pharmacol.
2003
, vol. 
64
 (pg. 
833
-
840
)
102
Vachon
 
E.
Bourbonnais
 
Y.
Bingle
 
C. D.
Rowe
 
S. J.
Janelle
 
M. F.
Tremblay
 
G. M.
 
Anti-inflammatory effect of pre-elafin in lipopolysaccharide-induced acute lung inflammation
Biol. Chem.
2002
, vol. 
383
 (pg. 
1249
-
1256
)
103
Zaidi
 
S. H.
You
 
X. M.
Ciura
 
S.
O'Blenes
 
S.
Husain
 
M.
Rabinovitch
 
M.
 
Suppressed smooth muscle proliferation and inflammatory cell invasion after arterial injury in elafin-overexpressing mice
J. Clin. Invest.
2000
, vol. 
105
 (pg. 
1687
-
1695
)
104
Cowan
 
B.
Baron
 
O.
Crack
 
J.
Coulber
 
C.
Wilson
 
G. J.
Rabinovitch
 
M.
 
Elafin, a serine elastase inhibitor, attenuates post-cardiac transplant coronary arteriopathy and reduces myocardial necrosis in rabbits after heterotopic cardiac transplantation
J. Clin. Invest.
1996
, vol. 
97
 (pg. 
2452
-
2468
)
105
Murata
 
E.
Sharmin
 
S.
Shiota
 
H.
Shiota
 
M.
Yano
 
M.
Kido
 
H.
 
The effect of topically applied secretory leukocyte protease inhibitor on the eosinophil response in the late phase of allergic conjunctivitis
Curr. Eye Res.
2003
, vol. 
26
 (pg. 
271
-
276
)
106
Sehnert
 
B.
Cavcic
 
A.
Bohm
 
B.
, et al 
Antileukoproteinase: modulation of neutrophil function and therapeutic effects on anti-type II collagen antibody-induced arthritis
Arthritis Rheum.
2004
, vol. 
50
 (pg. 
2347
-
2359
)
107
He
 
S. H.
Xie
 
H.
Zhang
 
X. J.
Wang
 
X. J.
 
Inhibition of histamine release from human mast cells by natural chymase inhibitors
Acta Pharmacol. Sin.
2004
, vol. 
25
 (pg. 
822
-
826
)
108
Haslett
 
C.
 
Granulocyte apoptosis and its role in the resolution and control of lung inflammation
Am. J. Respir. Crit. Care Med.
1999
, vol. 
160
 (pg. 
S5
-
S11
)
109
Odaka
 
C.
Mizuochi
 
T.
Yang
 
J.
Ding
 
A.
 
Murine macrophages produce secretory leukocyte protease inhibitor during clearance of apoptotic cells: implications for resolution of the inflammatory response
J. Immunol.
2003
, vol. 
171
 (pg. 
1507
-
1514
)
110
Henriksen
 
P. A.
Devitt
 
A.
Kotelevtsev
 
Y.
Sallenave
 
J. M.
 
Gene delivery of the elastase inhibitor elafin protects macrophages from neutrophil elastase-mediated impairment of apoptotic cell recognition
FEBS Lett.
2004
, vol. 
574
 (pg. 
80
-
84
)
111
Sano
 
C.
Shimizu
 
T.
Sato
 
K.
Kawauchi
 
H.
Tomioka
 
H.
 
Effects of secretory leucocyte protease inhibitor on the production of the anti-inflammatory cytokines, IL-10 and transforming growth factor-β (TGF-β), by lipopolysaccharide-stimulated macrophages
Clin. Exp. Immunol.
2000
, vol. 
121
 (pg. 
77
-
85
)
112
Sano
 
C.
Shimizu
 
T.
Tomioka
 
H.
 
Effects of secretory leukocyte protease inhibitor on the tumor necrosis factor-α production and NF-κB activation of lipopolysaccharide-stimulated macrophages
Cytokine
2003
, vol. 
21
 (pg. 
38
-
42
)
113
Ding
 
A.
Thieblemont
 
N.
Zhu
 
J.
Jin
 
F.
Zhang
 
J.
Wright
 
S.
 
Secretory leukocyte protease inhibitor interferes with uptake of lipopolysaccharide by macrophages
Infect. Immun.
1999
, vol. 
67
 (pg. 
4485
-
4489
)
114
Zhu
 
J.
Nathan
 
C.
Ding
 
A.
 
Suppression of macrophage responses to bacterial lipopolysaccharide by a non-secretory form of secretory leukocyte protease inhibitor
Biochim. Biophys. Acta
1999
, vol. 
1451
 (pg. 
219
-
223
)
115
Lentsch
 
A. B.
Ward
 
P. A.
 
The NFκBb/IκB system in acute inflammation
Arch. Immunol. Ther. Exp.
2000
, vol. 
48
 (pg. 
59
-
63
)
116
Jin
 
F. Y.
Nathan
 
C.
Radzioch
 
D.
Ding
 
A.
 
Secretory leukocyte protease inhibitor: a macrophage product induced by and antagonistic to bacterial lipopolysaccharide
Cell
1997
, vol. 
88
 (pg. 
417
-
426
)
117
Henriksen
 
P. A.
Hitt
 
M.
Xing
 
Z.
, et al 
Adenoviral gene delivery of elafin and secretory leukocyte protease inhibitor attenuates NF-κB-dependent inflammatory responses of human endothelial cells and macrophages to atherogenic stimuli
J. Immunol.
2004
, vol. 
172
 (pg. 
4535
-
4544
)
118
Lentsch
 
A. B.
Jordan
 
J. A.
Czermak
 
B. J.
, et al 
Inhibition of NF-κB activation and augmentation of IκBβ by secretory leukocyte protease inhibitor during lung inflammation
Am. J. Pathol.
1999
, vol. 
154
 (pg. 
239
-
247
)
119
Taggart
 
C. C.
Greene
 
C. M.
McElvaney
 
N. G.
O'Neill
 
S.
 
Secretory leucoprotease inhibitor prevents lipopolysaccharide-induced IκBα degradation without affecting phosphorylation or ubiquitination
J. Biol. Chem.
2002
, vol. 
277
 (pg. 
33648
-
33653
)
120
Mulligan
 
M. S.
Lentsch
 
A. B.
Huber-Lang
 
M.
, et al 
Anti-inflammatory effects of mutant forms of secretory leukocyte protease inhibitor
Am. J. Pathol.
2000
, vol. 
156
 (pg. 
1033
-
1039
)
121
Simpson
 
A. J.
Cunningham
 
G. A.
Porteous
 
D. J.
Haslett
 
C.
Sallenave
 
J. M.
 
Regulation of adenovirus-mediated elafin transgene expression by bacterial lipopolysaccharide
Hum. Gene Ther.
2001
, vol. 
12
 (pg. 
1395
-
1406
)
122
Sallenave
 
J. M.
Cunningham
 
G. A.
James
 
R. M.
McLachlan
 
G.
Haslett
 
C.
 
Regulation of pulmonary and systemic bacterial lipopolysaccharide responses in transgenic mice expressing human elafin
Infect. Immun.
2003
, vol. 
71
 (pg. 
3766
-
3774
)
123
McMichael
 
J. W.
Roghanian
 
A.
Jiang
 
L.
Rammage
 
R.
Sallenave
 
J. M.
 
The antimicrobial antiprotease elafin binds to lipopolysaccharide and modulates macrophage responses
Am. J. Respir. Cell. Mol. Biol.
2005
, vol. 
32
 (pg. 
1
-
10
)
124
Lee
 
S. K.
Lee
 
S. S.
Hirose
 
S.
, et al 
Elafin expression in human fetal and adult submandibular glands
Histochem. Cell Biol.
2002
, vol. 
117
 (pg. 
423
-
430
)
125
Yoshida
 
N.
Egami
 
H.
Yamashita
 
J.
, et al 
Immunohistochemical expression of SKALP/elafin in squamous cell carcinoma of human lung
Oncol. Rep.
2002
, vol. 
9
 (pg. 
495
-
501
)
126
Westin
 
U.
Nystrom
 
M.
Ljungcrantz
 
I.
Eriksson
 
B.
Ohlsson
 
K.
 
The presence of elafin, SLPI, IL1-RA and STNFα RI in head and neck squamous cell carcinomas and their relation to the degree of tumour differentiation
Mediators Inflamm.
2002
, vol. 
11
 (pg. 
7
-
12
)
127
van Bergen
 
B. H.
Andriessen
 
M. P.
Spruijt
 
K. I.
van de Kerkhof
 
P. C.
Schalkwijk
 
J.
 
Expression of SKALP/elafin during wound healing in human skin
Arch. Dermatol. Res.
1996
, vol. 
288
 (pg. 
458
-
462
)
128
Ashcroft
 
G. S.
Lei
 
K.
Jin
 
W.
, et al 
Secretory leukocyte protease inhibitor mediates non-redundant functions necessary for normal wound healing
Nat. Med.
2000
, vol. 
6
 (pg. 
1147
-
1153
)
129
Angelov
 
N.
Moutsopoulos
 
N.
Jeong
 
M. J.
Nares
 
S.
Ashcroft
 
G.
Wahl
 
S. M.
 
Aberrant mucosal wound repair in the absence of secretory leukocyte protease inhibitor
Thromb. Haemostasis
2004
, vol. 
92
 (pg. 
288
-
297
)
130
Zhu
 
J.
Nathan
 
C.
Jin
 
W.
, et al 
Conversion of proepithelin to epithelins: roles of SLPI and elastase in host defense and wound repair
Cell
2002
, vol. 
111
 (pg. 
867
-
878
)
131
Sumi
 
Y.
Muramatsu
 
H.
Hata
 
K.
Ueda
 
M.
Muramatsu
 
T.
 
Secretory leukocyte protease inhibitor is a novel inhibitor of fibroblast-mediated collagen gel contraction
Exp. Cell Res.
2000
, vol. 
256
 (pg. 
203
-
212
)
132
Zhang
 
D.
Simmen
 
R. C.
Michel
 
F. J.
Zhao
 
G.
Vale-Cruz
 
D.
Simmen
 
F. A.
 
Secretory leukocyte protease inhibitor mediates proliferation of human endometrial epithelial cells by positive and negative regulation of growth-associated genes
J. Biol. Chem.
2002
, vol. 
277
 (pg. 
29999
-
30009
)
133
Kikuchi
 
T.
Abe
 
T.
Yaekashiwa
 
M.
, et al 
Secretory leukoprotease inhibitor augments growth factor production in human lung fibroblasts
Am. J. Respir. Cell Mol. Biol.
2000
, vol. 
23
 (pg. 
364
-
370
)
134
Vassiliou
 
E.
Sharma
 
V.
Jing
 
H.
Sheibanie
 
F.
Ganea
 
D.
 
Prostaglandin E2 promotes the survival of bone marrow-derived dendritic cells
J. Immunol.
2004
, vol. 
173
 (pg. 
6955
-
6964
)
135
Katamura
 
K.
Shintaku
 
N.
Yamauchi
 
Y.
, et al 
Prostaglandin E2 at priming of naïve CD4+ T cells inhibits acquisition of ability to produce IFN-γ and IL-2, but not IL-4 and IL-5
J. Immunol.
1995
, vol. 
155
 (pg. 
4604
-
4612
)
136
Jing
 
H.
Yen
 
J. H.
Ganea
 
D.
 
A novel signalling pathway mediates the inhibition of CCL3/4 expression by prostaglandin E2
J. Biol. Chem.
2004
, vol. 
279
 (pg. 
55176
-
55186
)
137
Zhang
 
Y.
DeWitt
 
D. L.
McNeely
 
T. B.
Wahl
 
S. M.
Wahl
 
L. M.
 
Secretory leukocyte protease inhibitor suppresses the production of monocyte prostaglandin H synthase-2, prostaglandin E2, and matrix metalloproteinases
J. Clin. Invest.
1997
, vol. 
99
 (pg. 
894
-
900
)
138
Reference deleted
139
Tremblay
 
G. M.
Sallenave
 
J. M.
Israel-Assayag
 
E.
Cormier
 
Y.
Gauldie
 
J.
 
Elafin/elastase-specific inhibitor in bronchoalveolar lavage of normal subjects and farmer's lung
Am. J. Respir. Crit. Care Med.
1996
, vol. 
154
 (pg. 
1092
-
1098
)
140
Schalkwijk
 
J.
van Vligmen
 
I. M.
Alkemade
 
J. A.
de Jongh
 
G. J.
 
Immunohistochemical localization of SKALP/elafin in psoriatic epidermis
J. Invest. Dermatol.
1993
, vol. 
100
 (pg. 
390
-
393
)
141
Schutte
 
B. C.
McCray
 
P. B.
 
β-Defensins in lung host defense
Annu. Rev. Physiol.
2002
, vol. 
64
 (pg. 
709
-
748
)
142
Ganz
 
T.
 
Defensins: antimicrobial peptides of innate immunity
Nat. Rev. Immunol.
2003
, vol. 
3
 (pg. 
710
-
720
)
143
Aarbiou
 
J.
Rabe
 
K. F.
Hiemstra
 
P. S.
 
Role of defensins in inflammatory lung disease
Ann. Med.
2002
, vol. 
34
 (pg. 
96
-
101
)
144
Wilson
 
C. L.
Ouellette
 
A. J.
Satchell
 
D. P.
, et al 
Regulation of intestinal α-defensin activation by the metalloproteinase matrilysin in innate host defense
Science
1999
, vol. 
286
 (pg. 
113
-
117
)
145
Duits
 
L. A.
Ravensbergen
 
B.
Rademaker
 
M.
Hiemstra
 
P. S.
Nibbering
 
P. H.
 
Expression of β-defensin 1 and 2 mRNA by human monocytes, macrophages and dendritic cells
Immunology
2002
, vol. 
106
 (pg. 
517
-
525
)
146
Zanetti
 
M.
Gennaro
 
R.
Romeo
 
D.
 
Cathelicidins: a novel protein family with a common proregion and a variable C-terminal antimicrobial domain
FEBS Lett.
1995
, vol. 
374
 (pg. 
1
-
5
)
147
Sorensen
 
O.
Arnljots
 
K.
Cowland
 
J. B.
Bainton
 
D. F.
Borregaard
 
N.
 
The human antibacterial cathelicidin, hCAP-18, is synthesized in myelocytes and metamyelocytes and localized to specific granules in neutrophils
Blood
1997
, vol. 
90
 (pg. 
2796
-
2803
)
148
Bals
 
R.
Wang
 
X.
Wu
 
Z.
, et al 
Human β-defensin 2 is a salt-sensitive peptide antibiotic expressed in human lung
J. Clin. Invest.
1998
, vol. 
102
 (pg. 
874
-
880
)
149
Frohm
 
M.
Agerberth
 
B.
Ahangari
 
G.
, et al 
The expression of the gene coding for the antibacterial peptide LL-37 is induced in human keratinocytes during inflammatory disorders
J. Biol. Chem.
1997
, vol. 
272
 (pg. 
15258
-
15263
)
150
Agerberth
 
B.
Charo
 
J.
Werr
 
J.
, et al 
The human antimicrobial and chemotactic peptides LL-37 and α-defensins are expressed by specific lymphocyte and monocyte populations
Blood
2000
, vol. 
96
 (pg. 
3086
-
3093
)
151
Di Nardo
 
A.
Vitiello
 
A.
Gallo
 
R. L.
 
Cutting edge: mast cell antimicrobial activity is mediated by expression of cathelicidin antimicrobial peptide
J. Immunol.
2003
, vol. 
170
 (pg. 
2274
-
2278
)
152
Sorensen
 
O. E.
Follin
 
P.
Johnsen
 
A. H.
, et al 
Human cathelicidin, hCAP-18, is processed to the antimicrobial peptide LL-37 by extracellular cleavage with proteinase 3
Blood
2001
, vol. 
97
 (pg. 
3951
-
3959
)
153
Yang
 
D.
Chertov
 
O.
Bykovskaia
 
S. N.
, et al 
β-defensins: linking innate and adaptive immunity through dendritic and T cell CCR6
Science
1999
, vol. 
286
 (pg. 
525
-
528
)
154
Biragyn
 
A.
Ruffini
 
P. A.
Leifer
 
C. A.
, et al 
Toll-like receptor 4-dependent activation of dendritic cells by β-defensin 2
Science
2002
, vol. 
298
 (pg. 
1025
-
1029
)
155
Yang
 
D.
Chen
 
Q.
Schmidt
 
A. P.
, et al 
LL-37, the neutrophil granule- and epithelial cell-derived cathelicidin, utilizes formyl peptide receptor-like 1 (FPRL1) as a receptor to chemoattract human peripheral blood neutrophils, monocytes and T cells
J. Exp. Med.
2000
, vol. 
192
 (pg. 
1069
-
1074
)
156
Davidson
 
D. J.
Currie
 
A. J.
Reid
 
G. S. D.
, et al 
The cationic antimicrobial peptide LL-37 modulates dendritic cell differentiation and dendritic cell-induced T cell polarization
J. Immunol.
2004
, vol. 
172
 (pg. 
1146
-
1156
)
157
Colaco
 
C. A.
 
Towards a unified theory of immunity: dendritic cells, stress proteins and antigen capture
Cell. Mol. Biol.
1998
, vol. 
44
 (pg. 
883
-
890
)
158
Jego
 
G.
 
Dendritic cells control B cell growth and differentiation
Curr. Dir. Autoimmun.
2005
, vol. 
8
 (pg. 
124
-
139
)
159
Knight
 
S. C.
Burke
 
F.
Bedford
 
P. A.
 
Dendritic cells, antigen distribution and the initiation of primary immune responses to self and non-self antigens
Semin. Cancer Biol.
2002
, vol. 
12
 (pg. 
301
-
308
)
160
Cespedes
 
I. S.
Toka
 
F. N.
Schollenberger
 
A.
Gierynska
 
M.
Niemialtowski
 
M.
 
Pathogenesis of mousepox in H-2d mice: evidence for MHC class I-restricted CD8+ and MHC class II-restricted CD4+ CTL antiviral activity in the lymph nodes, spleen and skin, but not in the conjunctivae
Microbes Infect.
2001
, vol. 
3
 (pg. 
1063
-
1072
)
161
Matzinger
 
P.
 
The danger model: a renewed sense of self
Science
2002
, vol. 
296
 (pg. 
301
-
305
)
162
Stumbles
 
P. A.
Thomas
 
J. A.
Pimm
 
C. L.
, et al 
Resting respiratory tract dendritic cells preferentially stimulate T helper cell type 2 (Th2) responses and require obligatory cytokine signals for induction of Th1 immunity
J. Exp. Med.
1998
, vol. 
188
 (pg. 
2019
-
2031
)
163
Dodge
 
I. L.
Carr
 
M. W.
Cernadas
 
M.
Brenner
 
M. B.
 
IL-6 production by pulmonary dendritic cells impedes Th1 immune responses
J. Immunol.
2003
, vol. 
170
 (pg. 
4457
-
4464
)
164
de Jong
 
E. C.
Vieira
 
P. L.
Kalinski
 
P.
, et al 
Microbial compounds selectively induce Th1 cell-promoting or Th2 cell-promoting dendritic cells in vitro with diverse Th cell-polarizing signals
J. Immunol.
2002
, vol. 
168
 (pg. 
1704
-
1709
)
165
Pulendram
 
B.
 
Modulating vaccine responses with dendritic cells and Toll-like receptors
Immunol. Rev.
2004
, vol. 
199
 (pg. 
227
-
250
)
166
Gan
 
Y.
Shi
 
Y. E.
Bu
 
L. Y.
, et al 
Immune responses against Schistosoma japonicum after vaccinating mice with a multivalent DNA vaccine encoding integrated membrane protein Sj23 and cytokine interleukin-12
Chin. Med. J.
2004
, vol. 
117
 (pg. 
1842
-
1846
)
167
Hogg
 
K. G.
Kumkate
 
S.
Mountford
 
A. P.
 
IL-10 regulates early IL-12-mediated immune responses induced by the radiation-attenuated schistosome vaccine
Int. Immunol.
2003
, vol. 
15
 (pg. 
1451
-
1459
)
168
Zhu
 
Y.
Da'dara
 
A.
Harn
 
D.
, et al 
The protective effect of a Schistosoma japonicum Chinese strain 23kDa plasmid DNA vaccine in pigs is enhanced with IL-12
Vaccine
2004
, vol. 
23
 (pg. 
78
-
83
)
169
Bennouna
 
S.
Bliss
 
S. K.
Curiel
 
T. J.
Denkers
 
E. Y.
 
Cross-talk in the innate immune system: neutrophils instruct recruitment and activation of dendritic cells during microbial infection
J. Immunol.
2003
, vol. 
171
 (pg. 
6052
-
6058
)
170
Lu
 
H.
Xing
 
Z.
Brunham
 
R. C.
 
GM-CSF transgene-based adjuvant allows the establishment of protective mucosal immunity following vaccination with inactivated Chlamydia trachomatis
J. Immunol.
2002
, vol. 
169
 (pg. 
6324
-
6331
)
171
Biragyn
 
A.
Surenhu
 
M.
Yang
 
D.
, et al 
Mediators of innate immunity that target immature, but not mature, dendritic cells induce antitumor immunity when genetically fused with non-immunogenic tumor antigens
J. Immunol.
2001
, vol. 
167
 (pg. 
6644
-
6653
)
172
Liu
 
D. W.
Chang
 
J. L.
Tsao
 
Y. P.
, et al 
Co-vaccination with adeno-associated virus vectors encoding human papillomavirus 16 L1 proteins and adenovirus encoding murine GM-CSF can elicit strong and prolonged neutralizing antibody
Int. J. Cancer.
2005
, vol. 
113
 (pg. 
93
-
100
)
173
Wang
 
J.
Zganiacz
 
A.
Xing
 
Z.
 
Enhanced immunogenicity of BCG vaccine by using a viral-based GM-CSF transgene adjuvant formulation
Vaccine
2002
, vol. 
20
 (pg. 
2887
-
2898
)
174
Xing
 
Z.
Tremblay
 
G. M.
Sime
 
P. J.
Gauldie
 
J.
 
Overexpression of granulocyte-macrophage colony-stimulating factor induces pulmonary granulation tissue formation and fibrosis by induction of transforming growth factor-β1 and myofibroblast accumulation
Am. J. Pathol.
1997
, vol. 
150
 (pg. 
59
-
66
)
175
Koczulla
 
A. R.
Bals
 
R.
 
Antimicrobial peptides: current status and therapeutic potential
Drugs
2003
, vol. 
63
 (pg. 
389
-
406
)
176
McMichael
 
J. W.
Maxwell
 
A. I.
Hayashi
 
K.
, et al 
Antimicrobial activity of murine lung cells against Staphylococcus aureus is increased in vitro and in vivo after elafin gene transfer
Infect. Immun.
2005
, vol. 
73
 (pg. 
3609
-
3617
)