Renal protective roles of macrophage matrix metalloproteinase‐12 in mice with obstructed kidneys

Abstract

AbstractMatrix metalloproteinase (MMP)‐12 has been reported to have diverse functions, including regulation of immune reactions and anti‐inflammatory effects, but the potential roles of MMP‐12 in kidney injury have not been fully elucidated. This study aimed to determine whether MMP‐12 contributes to tubulointerstitial injury in a unilateral ureteric obstruction (UUO) model. MMP‐12‐deficient (MMP‐12−/−) mice and C57BL/6J mice as controls (MMP‐12+/+) were subjected to UUO and analysed 7 days after UUO. To analyse the functions of MMP‐12 on monocytes/macrophages, we generated MMP‐12‐deficient, irradiated, chimeric mice (BM‐MMP‐12−/−) and performed UUO. Bone marrow‐derived macrophages (BMDMs) were isolated from both groups of mice and used for investigations. MMP‐12−/− mice showed exacerbation of macrophage accumulation and interstitial fibrosis in the UUO‐kidney compared with control mice. BM‐MMP‐12−/− mice also showed exacerbation of kidney injury. UUO induced accumulation of Ly6C+ macrophages in MMP‐12−/− mice compared with control mice. Increases in inflammatory cytokine (tumour necrosis factor α, interleukin [IL]‐1β, IL‐6) levels from BMDMs after lipopolysaccharide stimulation were higher in MMP‐12−/− mice than in MMP‐12+/+ mice. MMP‐12 may play protective roles against kidney injury by UUO in mice, decreasing inflammatory cytokines from BMDMs and macrophage accumulation.