IL-18 mediates proapoptotic signaling in renal tubular cells through a Fas ligand-dependent mechanism (original) (raw)

IL-18 Stimulates a Positive Feedback Loop During Renal Obstruction via the IL-18 Receptor

2017

Background—IL-18 is a pro-inflammatory cytokine that has recently been demonstrated to be an important mediator of obstruction-induced renal tubulointerstitial fibrosis independent of TNFα and TGF-β1 activity. We hypothesized that IL-18 stimulates a positive feedback loop during obstruction via the IL-18 receptor (IL-18R) to increase both IL-18 gene expression and protein production. Methods—To study this, male C57BL6 IL-18R knockout (IL-18R-KO) and control (WT) mice were subjected to unilateral ureteral obstruction (UUO) vs. sham operation and sacrificed 1 week after surgery. Renal cortical tissue samples were harvested and analyzed for IL-18 protein levels (ELISA), and IL-18 and IL-18R gene expression (QPCR). The specific cellular localization of IL-18 and IL-18R expression during obstruction was assessed using dual labeling immunofluorescent staining (IFS). Results—Renal IL-18R expression increased significantly in WT mice in response to obstruction, but remained at sham levels i...

IL-18 deficiency ameliorates the progression from AKI to CKD

Cell Death and Disease, 2022

Inflammation is an important factor in the progression from acute kidney injury (AKI) to chronic kidney disease (CKD). The role of interleukin (IL)-18 in this progression has not been examined. We aimed to clarify whether and how IL-18 limits this progression. In a folic acid induced renal injury mouse model, we studied the time course of kidney injury and renal IL-18 expression. In wild-type mice following injection, renal IL-18 expression increased. In parallel, we characterized other processes, including at day 2, renal tubular necroptosis assessed by receptor-interacting serine/threonine-protein kinase1 (RIPK1) and RIPK3; at day 14, transdifferentiation (assessed by transforming growth factor β1, vimentin and E-cadherin); and at day 30, fibrosis (assessed by collagen 1). In IL-18 knockout mice given folate, compared to wild-type mice, tubular damage and necroptosis, transdifferentiation, and renal fibrosis were attenuated. Importantly, IL-18 deletion decreased numbers of renal M1 macrophages and M1 macrophage cytokine levels at day 14, and reduced M2 macrophages numbers and macrophage cytokine expression at day 30. In HK-2 cells, IL-18 knockdown attenuated necroptosis, transdifferentiating and fibrosis.In patients with tubulointerstitial nephritis, IL-18 protein expression was increased on renal biopsies using immunohistochemistry. We conclude that genetic IL-18 deficiency ameliorates renal tubular damage, necroptosis, cell transdifferentiation, and fibrosis. The renoprotective role of IL-18 deletion in the progression from AKI to fibrosis may be mediated by reducing a switch in predominance from M1 to profibrotic M2 macrophages during the process of kidney repair.

The pathological role of IL-18Rα in renal ischemia/reperfusion injury

Laboratory investigation; a journal of technical methods and pathology, 2015

Interleukin (IL)-18 is a proinflammatory cytokine produced by leukocytes and parenchymal cells (eg, tubular epithelial cells (TECs), mesangial cells, and podocytes). IL-18 receptor (IL-18R) is expressed on these cells in the kidney during ischemia/reperfusion injury (IRI), but its role in this injury is unknown. Fas/Fas ligand (FasL) is also involved in the pathogenesis of renal IRI via tubular apoptosis. In addition, IL-18 enhances the expression of FasL on TECs, but the mechanism underlying this enhancement is not known. Here we used IL-18Rα-deficient mice to explore the pathological role of IL-18Rα in renal IRI. We found that compared to wild-type (WT) mice with renal IRI as an acute kidney injury (AKI), the IL-18Rα-deficient mice demonstrated decreased renal function (as represented by blood urea nitrogen), tubular damage, an increased accumulation of leukocytes (CD4+ T cells, neutrophils, and macrophages), upregulated early AKI biomarkers (ie, urinary kidney injury molecule-1 l...

IL-18 induces profibrotic renal tubular cell injury via STAT3 activation

American Journal of Physiology-renal Physiology, 2013

is an important mediator of obstruction-induced renal fibrosis and renal tubular epithelial cell (TEC) injury. IL-18's proinflammatory properties have been attributed, in part, to NF-B activation and the stimulation of cytokine gene expression; however, STAT3 has increasingly been shown to mediate renal fibrotic injury. We therefore hypothesized that IL-18 mediates profibrotic TEC injury via STAT3 activation. Male C57BL6 wild-type mice and transgenic mice for human IL-18binding protein were subjected to unilateral ureteral obstruction or sham operation. The kidneys were harvested 1 or 2 wk afterward and analyzed for active STAT3 (p-STAT3) expression (Western blotting, immunohistochemistry) and suppressor of cytokine signaling 3 (SOCS3) expression. In a separate arm, renal tubular cells (HK-2) were directly stimulated with IL-18 for 2 days with or without the STAT3 inhibitor S3I-201 (50 M). Cell lysates were then analyzed for p-STAT3 and SOCS3 expression, profibrotic cellular changes (collagen and ␣-SMA expression), and tubular cell apoptosis. p-STAT3 and SOCS3 expression increased significantly in response to obstruction; however, a significant reduction in p-STAT3 and SOCS3 expression occurred following 1 wk, but not 2 wk, of obstruction in the presence of IL-18 neutralization. In vitro results similarly demonstrate increased p-STAT3, SOCS3, ␣-SMA, and collagen III expression, and increased collagen production and TEC apoptosis in response to IL-18 stimulation, but the response was significantly diminished in the presence of STAT3 inhibition. These results demonstrate that IL-18-induces profibrotic cellular changes and collagen production in TECs via STAT3 activation.

Deletion of IL-18 Expression Ameliorates Spontaneous Kidney Failure in MRLlpr Mice

PloS one, 2015

The role of IL-18 in the pathogenesis of systemic lupus erythematosus is still not definitively solved. In this study, we generated MRLlpr mice, which develop a disease resembling systemic lupus erythematosus, genetically devoid of IL-18 expression. These mice in comparison to IL-18-competent MRLlpr mice show reduced signs of renal pathogenesis, while other parameters such as mean survival time, lymphadenopathy, constitutive interferon-γ production, and frequency of CD3+B220+ abnormal T cells were without differences. We conclude that in the systemic lupus erythematosus syndrom IL-18 is involved specifically in the renal pathogenesis.

Physiological and molecular effects of interleukin-18 administration on the mouse kidney

Journal of translational medicine, 2018

The cytokine interleukin-18 was originally identified as an interferon-γ-inducing proinflammatory factor; however, there is increasing evidence to suggest that it has non-immunological effects on physiological functions. We previously investigated the potential pathophysiological relationship between interleukin-18 and dyslipidemia, non-alcoholic fatty liver disease, and non-alcoholic steatohepatitis, and suggested interleukin-18 as a possible novel treatment for not only these diseases but also for cancer immunotherapy. Before clinical application, the effects of interleukin-18 on the kidney need to be determined. In the current study, we examined the kidney of interleukin-18 knockout (Il18) mice and the effects of interleukin-18 on the kidney following intravenous administration of recombinant interleukin-18. Il18 male mice were generated on the C57Bl/6 background and littermate C57Bl/6 Il18 male mice were used as controls. To assess kidney damage, serum creatinine and blood urea ...

IL-18 Receptor Expression on Epithelial Cells is Upregulated by TNF Alpha

Inflammation, 2005

IL-18 is a multifunctional cytokine that augments both innate and acquired immunity and potentiates Th1 and Th2 reactions. We studied the expression of IL-18 receptor (IL-18R) on renal and respiratory epithelial cell lines. Both cell lines upregulated IL-18R mRNA and IL-18R membrane expression in response to TNF alpha and other proinflammatory cytokines. The function of IL-18R was confirmed by induction of IL-8 release from epithelial cells in response to recombinant IL-18. Epithelial cells may represent an important target for IL-18, mainly under inflammatory conditions associated with TNF alpha release.

Renal IL-18 Production Is Macrophage Independent During Obstructive Injury

PLoS ONE, 2012

Background: Interleukin 18 (IL-18) is a pro-inflammatory cytokine that mediates fibrotic renal injury during obstruction. Macrophages are a well-known source of IL-18; however, renal tubular epithelial cells are also a potential source of this cytokine. We hypothesized that IL-18 is predominantly a renal tubular cell product and is produced during renal obstruction independent of macrophage infiltration.

Differential effect of IL-18 on endothelial cell apoptosis mediated by TNF-α and Fas (CD95)

Cytokine, 2003

Interleukin-18 (IL-18) is a newly identified cytokine with proinflammatory activity. Numerous studies have shown that proinflammatory cytokines may regulate endothelial cells (EC) apoptosis mediated by members of the tumor necrosis factor (TNF) family, such as TNF-a and Fas. In this study we hypothesized that IL-18 may regulate the susceptibility of liver endothelial cells (LEC) to apoptosis induced by TNF and Fas. IL-18 increased the susceptibility of LEC to undergo apoptosis mediated by TNF but not by Fas. Since TNF-induced apoptosis is mediated by the type I TNF receptor (TNFRI), we investigated up-regulation of this receptor in IL-18-treated LEC. IL-18 induced up-regulation of the TNFRI on the surface of LEC. Partial blocking of LEC apoptosis induced by IL-18 and TNF was observed when the cells were pretreated with the broad-spectrum inhibitor of caspases z-VAD-fmk, suggesting involvement of the caspase pathway in apoptosis induced by these cytokines in these cells. Our results show that IL-18 differentially regulates apoptosis mediated by the death-inducing factors, TNF and Fas. To our knowledge, this is the first report that IL-18 may regulate endothelial cell apoptosis mediated by TNF. These results may have clinical implications in those clinical hepatic conditions associated with high levels of IL-18 and TNF.