Effect of simvastatin on expression of IL17, HMGB1 and TLR4 in LN kidney tissues of rats

Podocyte NADPH Oxidase 5 Promotes Renal Inflammation Regulated by the Toll-Like Receptor Pathway

AIMS

Oxidative stress associated with a proinflammatory state occurs in endothelial dysfunction, hypertension, chronic kidney disease, and diabetes. The NADPH oxidase (Nox) family of reactive oxygen species (ROS) generating enzymes is implicated in these processes, yet little information regarding the role of Nox5 is available. Our aim was to investigate the role of Nox5 in promoting renal inflammation and identify mechanisms regulating its activity.

RESULTS

Mice with podocyte-specific Nox5 (Nox5^pod+) expression demonstrated greater glomerular inflammation and increased expression of Toll-like receptors (TLRs) and proinflammatory cytokines. In a lipopolysaccharide (LPS) model of acute kidney injury, Nox5^pod+ and control littermates exhibited increased TLR and Nox1 expression. Compared with control littermates, Nox5^pod+ animals developed greater glomerular inflammation and ROS production. Immortalized human podocytes (hPODs) incubated with LPS demonstrated TLR induction, increased Nox5 expression, and enhanced ROS production. Inhibition of interleukin-1 receptor-associated kinases (IRAK)-1 and -4 that lie downstream of TLR inhibited LPS-induced ROS production. Interaction between IRAK1 and Nox5 was confirmed by coimmunoprecipitation. Furthermore, LPS treatment of hPODs resulted in phosphorylation of threonine residue(s) in Nox5 that was attenuated by an IRAK1/4 inhibitor. Innovation and Conclusion: These results are the first to demonstrate that Nox5 is a downstream target of the TLR pathway and that Nox5-derived ROS may be modulated by IRAK1/4 activity. Nox5-derived ROS in podocytes can promote a proinflammatory state in the kidney via induction of cytokine expression and upregulation of TLRs leading to a feed-forward loop in which TLR activation enhances Nox5-mediated ROS production.

CSTMP Exerts Anti-Inflammatory Effects on LPS-Induced Human Renal Proximal Tubular Epithelial Cells by Inhibiting TLR4-Mediated NF-κB Pathways

(E)-2-(2-chlorostyryl)-3,5,6-trimethylpyrazine (CSTMP), a novel stilbene derivative, have been shown to have cytoprotective effects against H2O2-induced oxidative stress in human endothelial cells. However, little is known about its anti-inflammatory effects in lupus nephritis (LN). In the present study, we investigated the anti-inflammatory effects of CSTMP on lipopolysaccharide (LPS)-induced human renal proximal tubular epithelial cells (hRPTECs) and elucidated its molecular mechanisms. CSTMP significantly attenuated the cytotoxicity and suppressed the release of proinflammatory mediators, including iNOS, COX-2, TNF-α, IL-6, IL-8, CCL-2, ICAM-1, IL-1β, and MCP-1 in LPS-induced hRPTECs. In addition, CSTMP decreased the expression of TLR4 and its adapter molecules (MyD88, phosphorylation of TAK1, TRAF6, and IRAK1) and abolished its interactions with these adapter molecules in LPS-induced hRPTECs, resulting in an inhibition of the TLR4/MyD88/TAK1/ TRAF6/IRAK1 complex. Moreover, CSTMP also attenuated phosphorylation of IκB and IKK-α/β, and P50-NF-κB and P65-NF-κB translocation to nucleus in LPS-induced hRPTECs. These findings provided new insights to understand the mode of action of CSTMP in treatment of inflammatory diseases, such as LN.