Habitual aerobic exercise prevents age-related impairments in endothelium-dependent dilation (EDD). We have hypothesized that the pro-inflammatory transcription factor nuclear factor κB (NF-κB) impairs EDD with sedentary aging, and habitual aerobic exercise prevents this age-related suppression of EDD by NF-κB. To test this hypothesis, we have inhibited NF-κB signalling via oral salsalate administration in healthy older aerobic exercise-trained adults (OT, n =14, 58±2 years), older non-exercising adults (ON, n =16, 61±1 years) and young non-exercising controls (YN, n =8, 23±1 years). Salsalate reduced endothelial cell expression of NF-κB p65 by ~25% in ON ( P <0.05) but did not significantly change expression in OT or YN ( P >0.05). EDD, assessed by brachial artery flow-mediated dilation (FMD), was improved by salsalate in ON (4.0±0.7% compared with 6.8±0.7%, placebo compared with salsalate, P <0.001) but did not change with salsalate in OT or YN (OT: 7.2±0.7% compared with 7.7±0.6%; YN: 7.6±0.9% compared with 8.1±0.8%; placebo compared with salsalate, P >0.05). Endothelium-independent dilation was not affected by salsalate in any group ( P >0.05). In ON, vitamin C infusion improved FMD by ~30% during placebo ( P <0.001) but had no affect during salsalate ( P >0.05). In OT and YN, vitamin C infusion did not affect FMD during either placebo or salsalate ( P >0.05). Salsalate reduced endothelial cell nitrotyrosine content by ~25% and NADPH oxidase p47 phox expression by ~30% in ON ( P <0.05) but had no effect in OT or YN ( P >0.05). Our results suggest that endothelial NF-κB signalling is associated with oxidative stress-related impairment of EDD in healthy non-exercising but not aerobically exercising older adults. This may be a key mechanism by which regular aerobic exercise preserves endothelial function and reduces cardiovascular risk with aging.

The TGFβ (transforming growth factor β)/SMAD and NF-κB (nuclear factor κB) signalling pathways play a key role in hypertensive nephropathy. The present study examined whether targeting these pathways by SMAD7, a downstream inhibitor of both pathways, blocks AngII (angiotensin II)-induced hypertensive kidney disease in mice. A doxycycline-inducible SMAD7-expressing plasmid was delivered into the kidney by a non-invasive ultrasound-microbubble technique before and after AngII infusion. Results showed that pre-treatment with SMAD7 prevented AngII-induced progressive renal injury by inhibiting an increase in proteinuria and serum creatinine while improving the glomerular filtration rate. Similarly, treatment with SMAD7 in the established hypertensive nephropathy at day 14 after AngII infusion halted the progressive renal injury. These preventive and therapeutic effects of SMAD7 on hypertensive kidney injury were associated with inhibition of AngII-induced up-regulation of SMURF2 (SMAD-specific E3 ubiquitin protein ligase 2) and Sp1 (specificity protein 1), blockade of TGFβ/Smad3-mediated renal fibrosis and suppression of NF-κB-driven renal inflammation. Moreover, overexpression of SMAD7 also prevented AngII-induced loss of renal miR-29b , an miRNA with an inhibitory role in both TGFβ/Smad3 and NF-κB pathways. In conclusion, SMAD7 may be a therapeutic agent for AngII-mediated hypertensive nephropathy. Inhibition of the Sp1/SMAD3/NF-κB/ miR-29b regulatory network may be a mechanism by which SMAD7 inhibits hypertensive nephropathy.

Integrin-linked kinase predominantly localizes at focal adhesions to regulate actin cytoskeletal dynamics, including cell migration and matrix remodelling. Although recent studies have suggested both physiological and pathophysiological roles of integrin-linked kinase in the cardiovascular and renal system, its involvement in hypertensive organ dysfunctions, such as those that occur in kidney, has not been investigated. In the present issue of Clinical Science , Alique and co-workers have demonstrated that angiotensin II-induced renal inflammatory responses were attenuated in mice with conditional deficiency of integrin-linked kinase, which were associated with suppression of nuclear factor κB activation and reactive oxygen species generation but not hypertension. The significance, potential mechanisms and future direction are presented and discussed in this Commentary.

ILK (integrin-linked kinase) is an intracellular serine/threonine kinase involved in cell-matrix interactions. ILK dysregulation has been described in chronic renal disease and modulates podocyte function and fibrosis, whereas data about its role in inflammation are scarce. AngII (angiotensin II) is a pro-inflammatory cytokine that promotes renal inflammation. AngII blockers are renoprotective and down-regulate ILK in experimental kidney disease, but the involvement of ILK in the actions of AngII in the kidney has not been addressed. Therefore we have investigated whether ILK signalling modulates the kidney response to systemic AngII infusion in wild-type and ILK-conditional knockout mice. In wild-type mice, AngII induced an inflammatory response, characterized by infiltration of monocytes/macrophages and lymphocytes, and up-regulation of pro-inflammatory factors (chemokines, adhesion molecules and cytokines). AngII activated several intracellular signalling mechanisms, such as the NF-κB (nuclear factor κB) transcription factor, Akt and production of ROS (reactive oxygen species). All these responses were prevented in AngII-infused ILK-deficient mice. In vitro studies characterized further the mechanisms regulating the inflammatory response modulated by ILK. In cultured tubular epithelial cells ILK blockade, by siRNA, inhibited AngII-induced NF-κB subunit p65 phosphorylation and its nuclear translocation. Moreover, ILK gene silencing prevented NF-κB-related pro-inflammatory gene up-regulation. The results of the present study demonstrate that ILK plays a key role in the regulation of renal inflammation by modulating the canonical NF-κB pathway, and suggest a potential therapeutic target for inflammatory renal diseases.

Diabetic nephropathy is the leading cause of kidney failure and its increasing prevalence and incidence has imposed global socio-economic stress on healthcare systems worldwide. Although historically considered a metabolic disorder, recent studies have established that inflammatory responses are central to the pathogenesis of diabetic nephropathy. TLRs (Toll-like receptors) are a family of pattern recognition receptors responsible for the initiation of inflammatory and immune responses. The regulation of TLR2 and TLR4 have been implicated in the pathogenesis of various kidney diseases, and emerging evidence shows their involvement in the perpetuation of inflammation in the diabetic kidney. The present review focuses on the relative contributions of TLR2 and TLR4 in recognizing endogenous ligands relevant to diabetic nephropathy and their subsequent activation of NF-κB (nuclear factor κB), which results in the synthesis and secretion of pro-inflammatory cytokines and chemokines. Moreover, we discuss the pro-inflammatory signalling pathways of TLR2 and TLR4, in which their interruption or blockade may prove to be important therapeutic targets, potentially translated into clinical treatments for diabetic nephropathy. Currently, inhibitors to TLR2 and TLR4 are undergoing clinical trials in various inflammatory models of disease, but none in patients with diabetic nephropathy. Given the existing literature, there is a fundamental necessity to undertake trials in patients with diabetic nephropathy with a focus on renal end points.

We have reported previously that Ac-SDKP ( N -acetyl-seryl-aspartyl-lysyl-proline) reduces fibrosis and inflammation (in macrophages and mast cells). However, it is not known whether Ac-SDKP decreases collagen cross-linking and lymphocyte infiltration; lymphocytes modulate both collagen cross-linking and ECM (extracellular matrix) formation in hypertension. Thus we hypothesized that (i) in AngII (angiotensin II)-induced hypertension, Ac-SDKP prevents increases in cross-linked and total collagen by down-regulating LOX (lysyl oxidase), the enzyme responsible for cross-linking, and (ii) these effects are associated with decreased pro-fibrotic cytokine TGFβ (transforming growth factor β) and the pro-inflammatory transcription factor NF-κB (nuclear factor κB) and CD4 + /CD8 + lymphocyte infiltration. We induced hypertension in rats by infusing AngII either alone or combined with Ac-SDKP for 3 weeks. Whereas Ac-SDKP failed to lower BP (blood pressure) or LV (left ventricular) hypertrophy, it did prevent AngII-induced increases in (i) cross-linked and total collagen, (ii) LOX mRNA expression and LOXL1 (LOX-like 1) protein, (iii) TGFβ expression, (iv) nuclear translocation of NF-κB, (v) CD4 + /CD8 + lymphocyte infiltration, and (vi) CD68 + macrophages infiltration. In addition, we found a positive correlation between CD4 + infiltration and LOXL1 expression. In conclusion, the effect of Ac-SDKP on collagen cross-linking and total collagen may be due to reduced TGFβ1, LOXL1, and lymphocyte and macrophage infiltration, and its effect on inflammation could be due to lower NF-κB.

NF-κB (nuclear factor κB) is a heterodimeric transcription factor that is constitutively expressed in all cell types and has a central role as a transcriptional regulator in response to cellular stress. In the present review, we discuss the role of NF-κB signalling in the maintenance of liver homoeostasis as well as in the pathogenesis of a wide variety of conditions affecting the liver, including viral hepatitis, steatohepatitis, cirrhosis and hepatocellular carcinoma. Much of the current knowledge of NF-κB signalling in the liver relates to the canonical pathway, the IKK [IκB (inhibitor of κB) kinase] complex and the RelA subunit. We explore the weaknesses of the experimental approaches to date and suggest that further work is needed to investigate in detail the discreet functions of each of the Rel subunits in liver physiology and disease.

The NF-κB (nuclear factor κB) family of transcription factors are involved in a myriad of activities, including the regulation of immune responses, maturation of immune cells, development of secondary lymphoid organs and osteoclastogenesis. Fine tuning by positive and negative regulators keeps the NF-κB signalling pathway in check. Microbial products and genetic alterations in NF-κB and other signalling pathway components can lead to deregulation of NF-κB signalling in several human diseases, including cancers and chronic inflammatory disorders. NF-κB-pathway-specific therapies are being actively investigated, and these hold promises as interventions of NF-κB-related ailments.

In the present study, we have investigated the effect of (i) ET-1 (endothelin-1) and its precursor, big ET-1, on MMP (matrix metalloproteinase)-2 and MMP-9 synthesis and activity in osteosarcoma tissue, and (ii) ET-1 receptor antagonists on cell invasion. Using Western blotting, zymography, RT-PCR (reverse transcription–PCR), immunohistochemistry, immunofluorescence and Northern blotting, we have shown that ET-1 and ET-1 receptors (ET A and ET B ) were expressed in these cells. Additionally, we have demonstrated that ET-1 markedly induced the synthesis and activity of MMP-2, which was significantly increased when compared with MMP-9. Furthermore, inhibition of NF-κB (nuclear factor κB) activation blocked MMP-2 production and activity, indicating the involvement of NF-κB, a ubiquitous transcription factor playing a central role in the differentiation, proliferation and malignant transformation. Since ET-1 acts as an autocrine mediator through gelatinase induction and because inhibition of ET A receptor is beneficial for reducing both basal and ET-1-induced osteosarcoma cell invasion, targeting this receptor could be an attractive therapeutic alternative for the successful treatment of osteosarcoma.

The imbalance between NO (nitric oxide) and ROS (reactive oxygen species) is an important factor in the development of hypertension. The aim of the present study was to determine the preventive and therapeutic effects of NAC ( N -acetylcysteine) in SHRs (spontaneously hypertensive rats). Young and adult SHRs and WKY (Wistar–Kyoto) rats were treated with NAC (20 g/l in the drinking water). After 8 weeks of treatment, BP (blood pressure) and NOS (NO synthase) activity, conjugated dienes and GSH (reduced glutathione) in the kidney and left ventricle were determined. Protein expression of eNOS (endothelial NOS), inducible NOS and NF-κB (nuclear factor κB) were also determined in the left ventricle and kidney. Chronic NAC treatment partially attenuated the rise in BP in young SHRs (179±6 compared with 210±8 mmHg in untreated animals), but it had no significant effect on BP in adult SHRs. The antioxidant action of NAC, measured as a decrease of the concentration of conjugated dienes or inhibition of NF-κB expression, was greater in young than in adult SHRs. Similarly, eNOS protein expression was attenuated more in young than in adult SHRs, although NAC treatment increased NOS activity to a similar extent in both young and adult rats. In conclusion, both decreased ROS production and increased NOS activity appear to participate in the BP changes after NAC treatment in young SHRs. In adult SHRs with established hypertension, however, the secondary alterations (such as pronounced structural remodelling of resistance vessels) might attenuate the therapeutic effect of NAC.