Celastrol Attenuates Renal Injury In Diabetic Rats By Inhibiting The MAPK/NF-κB Signaling Pathway

Objective: Celastrol(a pentacyclic-triterpene extract derived from Tripterygium wilfordii Hook F.),is also the main active ingredient.So far,only a few studies have shown the effects and mechanisms of innate immune alterations of celastrol on renal injury.The present study was aimed to investigate protective effects of celastrol on the renal injury in diabetic rats.The expression of MAPK/NF-κB signal pathway related protein was detected to further explore the possible mechanism of celastrol.Methods: A total of 60 SD rats were randomly selected as a blank control group(NC group,n = 8).All the other rats were injected with stz 50mg/kg via tail vein to make diabetic model.The diabetic rats were randomly assigned to five groups: diabetes mellitus group(DM group,n=8),and diabetic rats treated with low-dose CEL(DM+CL group,50ug/kg·d,n= 8),and diabetic rats treated with high-dose CEL(DM+CH group,100ug/kg·d,n=8),and diabetic rats treated TWP(DM+TWP,8mg/kg·d,n=8),and MAPK/NF-κB inhibitor group(DM+INH,SB203580 1mg/kg·d、PDTC 100 mg/kg·d,n=8).After 4 weeks of continuous administration,the general condition,body weight,kidney index,liver index,24 h urine volume and microalbuminuria,blood urea nitrogen,Serum creatinine content were observed and haematoxylin-eosin(HE)staining of the kidney and liver were evaluated in rats.Serum IL-8,FN,PAI-1 content in rats was identified by enzyme-linked immunosorbent assay.We also analyzed the protein expressions of MAPK/NF-κB by immunohistochemistry and Western Blotting,respectively.Results:(1)General indicators:(1)Biochemical indexes: The levels of blood glucose.BUN,Scr,24-hour urine and microalbuminuria in the DM group were significantly increased reported to the NC group(P<0.05).However,no significant changes were seen in blood glucose level between the treatment groups and the DM group(P>0.05).Compared with the DM group,the level of BUN,Scr,24-hour urine and microalbuminuria was raised significantly in the treatment groups(P<0.05).(2)Body weight and Renal index,Liver index: Compared with the NC group,the weight of the rats in DM group decreased significantly(P<0.05),the weight in the CL group were significantly increased compared with the DM group(P<0.05).The level of RW/BW and LW/BW not significantly changes in the DM group(P>0.05),and compared with the DM group,treatment groups not significantly changes(P<0.05).(2)Histopathological examination of kidney and liver tissues:(1)Renal histological changes: H&E staining showed that the sections from the NC group displayed normally sized structures without any abnormalities.Conversely,sections from the DM group displayed glomerular proliferation,glassy degeneration was seen in glomerular vascular wall,basement membrane thickened slightly and Mesangial matrix slightly increased.However,lesions in treatment groups were lower than that in the DM group,particularly in the CH group.(2)Liver histological changes: There was clear structure of hepatic lobule and hepatocytes,no obvious inflammatory cell infiltration in the NC group in H&E staining sections.Hepatic lobular structure generally disappeared,and cell arrangement disorder with obvious inflammatory cell infiltration in the DM group.However,lesions in celastrol-treated groups and TWP group were lower than that in the DM group,particularly in the CH group.(3)Serum levels of inflammatory factors: ELISA analysis showed serum IL-8,FN and PAI-1 levels in the DM group were significantly increased compared with those in the NC group(P<0.05),and FN,PAI-1 levels in celastrol-treated groups were decreased(P<0.05).(4)Effects of celastrol on expressions of MAPK/NF-κB signaling pathway of renal tissues in rats: Immunohistochemical and Western Blotting analysis showed p38 MAPK and NF-κBp65 protein levels in the renal tissues in the DM group were significantly increased compared with those in the NC group(P<0.05).Additionally,protein expressions were decreased in CH groups(P<0.05).Conclusion: Celastrol can protect the kidney of diabetic rats by regulating the signal pathway of MAPK/NF-κB,inhibiting inflammation and delaying renal injury.