The impact of PD-L1 blocking on immune status and renal protection in the models of diabetic mice with sepsis

Yang Li; Gao Qian; Yang Tiecheng; Guo Shubin

doi:10.3969/j.issn.1002-1949.2024.08.005

Abstract：Objective To investigate the mechanism of programmed death-ligand 1(PD-L1)blocking on the change of immune status and the improvement of renal function in diabetic mice with sepsis.Methods C57BL/6J male mice were randomly divided into 4 groups(n=6):non-diabetic mice sham group(Sham group),diabetic mice sham group(DMS group),diabetic mice cecal ligation and puncture(CLP)group(DMCLP group),PD-L1 antibody treatment group(anti-PD-L1 group).The diabetic mouse model was constructed by feeding a high-sugar and high-fat diet combined with streptozotoci(STZ)injection,the feeding after modeling continued for 28 d and CLP were performed for establishing the sepsis mouse model,PD-L1 antibody treatment group mice were intraperitoneally injected with anti-PD-L1 antibody 1 h after CLP(50 μg/mouse).Flow cytometry was used to observe the classical monocyte subset and major histocompatibility complex Ⅱ(MHC Ⅱ)expression on Ly6Chi monocytes surface in each group.The expressions of inflammatory factors interleukin-6(IL-6),tumor necrosis factor-α(TNF-α)and interleukin-10(IL-10)in each group were detected by enzyme-linked immunosorbent assay(ELISA),the blood urea nitrogen(BUN)and serum creatinine(SCr)in mice in each group were detected by automatic biochemical detector,the pathological damage of renal tissue was observed by hematoxylin-eosin(HE)staining.Results Compared with Sham group and DMS group respectively,the percentage of Ly6Chi monocytes in DMCLP group was significantly increased,the expression of MHC Ⅱ on the Ly6Chi monocytes surface was significantly decreased,the levels of inflammatory factors IL-6,TNF-α and IL-10 in peripheral blood were increased,BUN and SCr levels were significantly increased,the difference was statistically significant(all P＜0.05);The pathological damage of kidney was aggravated.Compared with DMCLP group,the percentage of Ly6Chi monocytes in anti-PD-L1 group was reduced,the expression of MHC Ⅱ on Ly6Chi monocytes significantly increased,the expression of inflammatory factors IL-6,TNF-α and IL-10 in peripheral blood decreased,BUN and SCr levels decreased,the difference was statistically significant(all P＜0.05);The renal pathological damage was ameliorated.Conclusions PD-Ll antibody changes the immune status of diabetic mice with sepsis by improving the function of inflammatory monocytes,and plays a protective role in renal function.