Shoichi Hino

Signaling through the interleukin-18 receptor α attenuates inflammation in cisplatin-induced acute kidney injury

Interleukin (IL)-18 is produced by leukocytes and renal parenchymal cells (tubular epithelial cells, podocytes, and mesangial cells). The IL-18 receptor (IL-18R) is expressed on these cells in cisplatin-induced acute kidney injury, but the role of IL-18R is unknown. To help define this, we compared IL-18Rα knockout with wild-type mice in cisplatin-induced acute kidney injury and found deteriorated kidney function, tubular damage, increased accumulation of leukocytes (CD4(+) and CD8(+) T-cells, macrophages, and neutrophils), upregulation of early kidney injury biomarkers (serum TNF, urinary IL-18, and KIM-1 levels), and increased expression of pro-inflammatory molecules downstream of IL-18. In vitro, leukocytes from the spleen and kidneys of the knockout mice produced greater amounts of pro-inflammatory cytokines upon stimulation with concanavalin A compared to that in wild-type mice. Levels of the suppressor of cytokine signaling 1 and 3 (negative regulators of cytokine signaling) were reduced in the spleen and kidneys of IL-18Rα-deficient compared to wild-type mice. Adoptive transfer of wild-type splenocytes by IL-18Rα-deficient mice led to decreased cisplatin nephrotoxicity compared to control IL-18Rα-deficient mice. In contrast, anti-IL-18Rα and anti-IL-18Rβ antibody treatment tended to increase cisplatin nephrotoxicity in wild-type mice. Thus, signaling through IL-18Rα activates both inflammation-suppressing and pro-injury pathways in cisplatin-induced acute kidney injury.

Effect of combining ACE inhibitor and statin in lupus-prone mice.

MRL-Fas(lpr) mice spontaneously develop a systemic autoimmune disease resembling human systemic lupus erythematosus. The glomerulonephritis in MRL-Fas(lpr) mice is mediated by autoantibodies and autoreactive lymphocytes. To investigate the effect of combination therapy by angiotensin-converting enzyme inhibitor (ACEI) and hydroxymethylglutaryl-coenzyme A reductase inhibitor (statin) for lupus nephritis, we treated MRL-Fas(lpr) mice with imidapril, pravastatin or both agents. Compared with other groups, the mice treated by combination therapy survived longer and showed a significant reduction in proteinuria, renal pathology, including glomerular IgG deposit, and serum anti-DNA Ab. Furthermore, monocyte chemoattractant protein-1 (MCP-1) in the kidney was reduced significantly in the combination therapy group, compared with that in the control group. We conclude that combination therapy with ACEI and statin for MRL-Fas(lpr) mice significantly alleviates autoimmune renal disorder and prolongs survival. These results suggest that combination therapy by ACEI and statin may represent a new approach to the treatment of patients with lupus.

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

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 levels), and increased mRNA expressions of proinflammatory cytokines (IL-1β, IL-12p40, and IL-18) and chemokines (intercellular adhesion molecule-1 and CCL2/monocyte chemoattractant protein-1). The mRNA expression of FasL in the kidney was increased in the IL-18Rα-deficient mice compared to the WT mice. The adoptive transfer of splenocytes by WT mice led to decreased renal IRI compared to the IL-18Rα-deficient mice. In vitro, the mRNA expression of FasL on TECs was promoted in the presence of recombinant IL-18. These data reveal that IL-18Rα has an anti-inflammatory effect in IRI-induced AKI. Above all, IL-18 enhanced the inflammatory mechanisms and the apoptosis of TECs through the Fas/FasL pathway by blocking IL-18Rα.

Therapeutic Effect of Retinoic Acid on Unilateral Ureteral Obstruction Model

Background: Retinoic acids, a group of natural and synthetic vitamin A derivatives, have potent anti-proliferative, anti-inflammatory and anti-fibrotic properties. We investigated the therapeutic effect of all-trans-retinoic acid (ATRA) on unilateral ureteral obstruction (UUO) model mice. Methods: First, to evaluate the prophylactic effect, we administered 0.5 mg of ATRA for 3 days before UUO (UUO ATRA). Then, to evaluate the therapeutic effects, we administered 0.5 mg of ATRA 3 days after UUO (Day3 ATRA). We compared the histological changes and immunostaining of macrophages, α-smooth muscle actin (α-SMA) and collagen I, and mRNA expression of monocyte chemotactic protein-1 (MCP-1), transforming growth factor (TGF)-β1 and TGF-β R-II by RT-PCR 7 days after UUO. Results: In the UUO ATRA and Day3 ATRA groups, we observed a significant improvement in histological and immunological findings, including macrophage infiltration and improved expression of MCP-1, TGF-β1, α-SMA and collagen I compared with the UUO Day7 group. Conclusion: ATRA treatment is not only an effective prophylactic strategy, but also a therapeutic strategy for the treatment of progressive renal fibrosis in diseased kidneys.

Estimation of kidney injury molecule-1 (Kim-1) in patients with lupus nephritis.

Objective Biomarkers of disease activity in lupus nephritis (LN) are needed. Ideally, such biomarkers would be capable of detecting early sub-clinical disease and could be used to gauge response to therapy, thus obviating the need for serial renal biopsies. Much of the focus in the search for LN biomarkers has been on the measurement of urinary chemokines and cytokines in LN patients. However, these have yet to be widely implemented in clinical practice. Kidney injury molecule-1 (Kim-1) is expressed in damaged tubules, but whether urinary (u) and tubular (t)-Kim-1 could serve as a biomarker of active LN is unknown. To investigate the disease activity and histological findings in LN, we evaluated u-Kim-1 levels and t-Kim-1 cells in patients with systemic lupus erythematosus (SLE). Method We measured u-Kim-1 levels and stained t-Kim-1 expression in 57 patients with LN using an ELISA and immunohistochemistry staining. Patients were classified into two groups (active LN, n = 37; inactive LN, n = 20) based on the presence of active renal disease according to the renal SLE disease activity index. correlations of clinical, laboratory data, and histological findings with urinary and t-Kim-1 expression were assessed. Result The u-Kim-1 levels were significantly correlated with the expression of t-Kim-1 (R = 0.64; P = 0.004) in the SLE patients. The active LN patients exhibited elevated u-Kim-1 levels compared to the inactive LN patients. The number of t-Kim-1 cells was also correlated with histological findings (both glomerular and interstitial inflammation). The u-Kim-1 levels were also correlated with proteinuria and tubular damage in the active LN group. The number of t-Kim-1 cells at baseline was significantly correlated with the estimated glomerular filtration rate (R = 0.72; P = 0.005) and serum creatinine (R = 0.53; P = 0.005) after 6–8 months of treatment. Conclusion These data suggest the potential use of the u-Kim-1 levels to screen for active LN and for the estimation of t-Kim-1 expression in renal biopsies to predict renal damage, ongoing glomerular nephritis and tubulointerstitial inflammation, and tubular atrophy.

Signaling Rho-kinase mediates inflammation and apoptosis in T cells and renal tubules in cisplatin nephrotoxicity

Nephrotoxicity is a frequent complication of cisplatin-induced chemotherapy, in which T cells are known to promote acute kidney injury (AKI). Apoptosis and necrosis of tubules and inflammatory events also contribute to the nephrotoxicity. A delineation of the mechanisms that underlie the inappropriate renal and tubular inflammation can thus provide important insights into potential therapies for cisplatin-induced AKI. Rho-kinases are known to act as molecular switches controlling several critical cellular functions, including cell migration, cytokine production, and apoptosis. Here, we show that the Rho-kinase inhibitor fasudil attenuated cisplatin nephrotoxicity, resulting in less histological damage, improved renal function, and the infiltration of fewer leukocytes into the kidney. Renal nuclear factor-κB activation and apoptosis were reduced, and the expressions of proinflammatory renal cytokine and chemokine mRNA were decreased. Urinary and renal kidney injury molecule-1 (Kim-1) expression was also reduced, a finding that is consistent with diminished kidney injury. In the current study, we also showed that fasudil could be protective of the impaired tubules. In vitro, fasudil reduced the apoptosis (annexin-V+PI cells) and cytokine production (tumor necrosis factor+ cells) in T cells and the apoptosis (annexin-V+PI cells) and tubular damage (Kim-1+ cells) in proximal tubular cells by flow cytometric analysis. As Rho-kinase plays an important role in promoting cisplatin nephrotoxicity, inhibiting Rho-kinase may be a therapeutic strategy for preventing cisplatin-induced AKI.

Lipopolysaccharide-Induced Acute Kidney Injury Is Dependent on an IL-18 Receptor Signaling Pathway

The proinflammatory cytokine interleukin (IL)-18 is an important mediator of the organ failure induced by endotoxemia. IL-18 (known as an interferon-gamma (IFN-γ) inducing factor), and other inflammatory cytokines have important roles in lipopolysaccharide (LPS)-induced acute kidney injury (AKI). We investigated the effect of inflammatory cytokines and Toll-like receptor 4 (TLR4) expression, an event that is accompanied by an influx of monocytes, including CD4+ T cells and antigen-presenting cells (APCs) in IL-18Rα knockout (KO) mice and wild-type (WT) mice after LPS injection. In the acute advanced phase, the IL-18Rα KO mice showed a higher survival rate and a suppressed increase of blood urea nitrogen, increased levels of proinflammatory cytokines such as IFN-γ and IL-18, the infiltration of CD4+ T cells and the expression of kidney injury molecule-1 as an AKI marker. In that phase, the renal mRNA expression of the M1 macrophage phenotype and C-C chemokine receptor type 7 as the maturation marker of dendritic cells (DCs) was also significantly decreased in the IL-18Rα KO mice, although there were small numbers of F4/80+ cells and DCs in the kidney. Conversely, there were no significant differences in the expressions of mRNA and protein TLR4 after LPS injection between the WT and IL-18Rα KO groups. Our results demonstrated that the IL-18Rα-mediated signaling pathway plays critical roles in CD4+ T cells and APCs and responded more quickly to IFN-γ and IL-18 than TLR4 stimulation in the pathogenesis of LPS-induced AKI.