Experiment On The Expression And Significance Of SIRT1 And SIRT3 In Renal Allografts At The Early Stage Of Chronic Renal Allograft Dysfunction

Objective:To investigate the expression and significance of SIRT1 and SIRT3 in renal allografts at the early stage of CRAD.Methods:CRAD rat models were established using classical orthotopic F344-Lewis kidney transplantation model.F344 and Lewis uninephrectomized rats were used as controls.Twelve weeks after the operation,the blood samples and urine samples were collected for renal function examination.Then all anesthetized rats were harvested with 3%sodium pentobarbital.The levels of MDA and SOD activity were measured in the harvested kidney tissue.Histopathological staining was used to observe the pathological changes of rat renal tissue.And the expressions of SIRT1 and SIRT3 in the kidneys were detected by immunohistochemical staining,real-time quantitative PCR analysis and Western blot.Results:1.Oxidative stress was present in the kidneys at the early stage of CRAD in the model established in the study.24 hour urinary protein excretion,urine microalbumin/creatinine ratios,and the serum creatinine and urea nitrogen levels were significantly increased in the CRAD group,compared with the F344 and Lewis control groups(p<0.05).Histopathological staining showed that there were no significant histological changes in the glomeruli,tubulointerstitium,or arteries of the F344 and LEW control groups.Histological changes in CRAD rat kidney tissue included significant mononuclear cell infiltration,diffuse interstitial fibrosis,atrophy of tubules,proliferation of mesangial matrix and cells,and thickening of basal membrane segments;Banff score sums were higher than control groups.SOD activity was decreased while the levels of MDA were increased in the renal tissues in the allografts,compared with the F344 and Lew controls(p<0.05).2.The expression of SIRT1 in the kidney of different groups was different.The level of SIRT1 was down-regulated,and TGF-β1,MCP-1 and ICAM-1 were up-regulated in CRAD rat kdineys,compared with the F344 and Lew controls(P<0.05).Furthermore,the expression of SIRT1 was negatively correlated with the 24 hour urinary protein excretion,serum creatinine levels,Banff score sums,mononuclear cell infiltration,severity of IF and the expression levels of TGF-β1,MCP-1 and ICAM-1 respectively.3.The expression of SIRT3 in the kidney of different groups was different.Immunohistochemical analysis demonstrated the expression of SIRT3 was significantly decreased in the kidneys from the allograft group(P<0.05).The results of Western blot also demonstrated that the expression of SIRT3 was significantly decreased in the allograft,compared with the F344 and Lew controls(P<0.05).There were negative correlations between the expression of SIRT3 and 24h urinary protein excretion,serum creatinine levels,tubulointerstitial mononuclear cell infiltration,the number of SMCs in the vascular wall and the sum of Banff scores in allografts respectively(P<0.05).Conclusion:SIRT1 and SIRT3 might be involved in the pathogenic process of oxidative stress,inflammation and IF at the early stage of CRAD.Their decreased levels might play important roles in the pathogenesis of early stage of CRAD.The results of the study may provide a novel therapeutic strategies and targets for the early prevention and treatment of CRAD.