Knockout of the interleukin-36 receptor protects against renal ischemia-reperfusion injury by reduction of proinflammatory cytokines

IL-36, a newly named member of the IL-1 cytokine family, includes 3 isoforms, IL-36α, IL-36β, and IL-36γ, all of which bind to a heterodimer containing the IL-36 receptor (IL-36R). Little is known about the role of the IL-36 axis in acute kidney injury (AKI) pathogenesis. Therefore, we evaluated IL-36 function in the bilateral renal ischemia-reperfusion injury model of AKI using IL-36R knockout and wild-type mice. IL-36R was found to be expressed in the kidney, mainly in proximal tubules. In IL-36R knockout mice, plasma creatinine, blood urea nitrogen, and IL-6 levels after ischemia-reperfusion injury were significantly lower than those in wild-type mice. Immunohistological analysis revealed mild tubular injury. IL-36α/β/γ levels were increased after ischemia-reperfusion injury, and IL-36α was expressed in lymphocytes and proximal tubular cells, but post-ischemia-reperfusion injury mRNA levels of IL-6 and TNF-α were low in IL-36R knockout mice. In primary cultures of renal tubular epithelial cells, IL-36α treatment upregulated NF-κB activity and Erk phosphorylation. Notably, in patients with AKI, urine IL-36α levels were increased, and IL-36α staining in renal biopsy samples was enhanced. Thus, IL-36α/IL-36R blockage could serve as a potential therapeutic target in AKI.