Microecological Dysbiosis Of Gut Microbiota Promotes Incipient Pathogenesis Of Diabetic Nephropathy

Background Diabetic nephropathy(DN)has become one of the major causes of diabetic mellitus(DM)developing to end-stage renal diseases(ESRD).However,the initiating factors and underlying mechanisms of incipient DN have not been fully elucidated.Some studies have shown that gut microbiota along with its metabolites are associated with a variety of metabolic diseases.Therefore,we have proposed that intestinal dysbiosis play an important role in incipient nephropathy of DN.This study aimed to investigate the role and mechanism of intrarenal renin-angiotensin system(RAS)activation mediated by disordered intestinal flora in renal injuries of early DN.Methods Eight-week old male Sprague-Dawley(SD)rats,weighed 150-200 g,were adaptively fed for 2 weeks and then randomly divided into three groups: Control group,diabetic group(DM group,induced by streptozotocin/STZ),and diabetic rats treated with antibiotics(DM+AB group).All the rats of the three groups were normally fed,while the DM+AB group were given compound antibiotic oral solution(ampicillin 1g/L+ vancomycin 0.5g/L+ neomycin 1g/L+ amphotericin B 0.1g/L).After 8 weeks,the rats were sacrificed,and blood,urine,feces and renal tissues were harvested.The fecal specimen of each group was analyzed by 16 S r DNA sequencing.The plasma acetate(Short chain fatty acids,one of the major metabolites of gut microbiota)was detected by gas chromatography.The level of circulating RAS was measured by radioimmunoassay.The degree of renal injuries was evaluated by PAS staining and electron microscopy.The expression of related proteins in tissues and cells was confirmed by immunofluorescent staining,and Western Blot.Result Compared with Control group,DM group showed a significant difference in the type and abundance of gut microbiota,and the level of plasma acetate in DM group was also remarkably increased.The glomeruli of DM group underwent obvious ultrastructural damages,while antibiotic treatment alleviated renal injuries caused by DM.In addition,the activation of circulating RAS was mitigated after antibiotic application.Compared with DM group,the corresponding protein expression of RAS in DM+AB group has been reduced,suggesting that antibiotics might inhibit the production of angiotensinⅡ(AngⅡ),thereby weakening the effect of AngⅡon renal injuries in early DN.Conclusion There is disturbance of gut microbiota in DN.Overproduction of acetate caused by gut microniota dybiosis might promote renal injuries in early DN through activating local renal RAS.