Astragaloside IV Derivative Ameliorates Obesity-related Nephropathy By Regulating Perirenal Adipose Inflammation And Inhibiting The TGF-β1/Smads Signaling Cascade

Objective:Astragaloside IV plays the most important pharmacological role in many biological active components of traditional Chinese medicine Astragalus membranaceus.Previous studies have shown that astragaloside IV plays an important role in the control of early-and mid-stage diabetes and late diabetic nephropathy.However,it is disappointing that the in vivo solubility of astragaloside IV and its bioavailability after oral administration are very low.We recently obtained a new water-soluble derivative of astragaloside IV-astragaloside formic acid(LS-102),which has higher bioavailability than the parent compound.In our previous study,we found that there was a significant inflammatory response in the perirenal adipose tissue of mice with obesity-related nephropathy induced by a high-fat diet(HFD),which was related to macrophage infiltration.We hypothesized that in model mice with obesity-related nephropathy,LS-102 effectively regulated the inflammatory response and pathological changes in obesity-related nephropathy through macrophages in perirenal adipose tissue.If this hypothesis is true,the effects of LS-102 and astragaloside IV on TGF-β1/Smad signal transduction will be further investigated.Methods:In this study,HFD-induced obesity-related nephropathy mouse model were used to observe the regulatory effect of LS-102 on perirenal fat inflammation and the mechanism.The mechanism of action of LS-102 was further discussed.Male mice of similar weight were fed a high-fat diet(HFD)for 14 weeks.Male mice with similar body weight to those in the high-fat feeding group were fed a standard laboratory normal diet as the control group.The body weight of experimental mice in each group was measured every week.Three mice were randomly selected to remove kidney tissue and perirenal adipose tissue,and weigh the weight of perirenal adipose tissue.QRT-pcr was used to measure the m RNA expression of CD11 c,IL-6,IL-10 and CD206 in perirenal adipose tissue to confirm whether the modeling was successful.Obesity-related nephropathy mice were randomly divided into five groups: the HFD group,the LAS group(HFD+low concentration of astragaloside IV),the HAS group(HFD+high concentration of astragaloside IV),the L102 group(HFD+low concentration of LS-102)and the H102 group(HFD+high concentration of LS-102).Body weight was measured.And the levels of serum glucose,high-density lipoprotein(HDL),low-density lipoprotein(LDL),triglyceride(TG),total cholesterol(TC),serum creatinine(Crea)and blood urea were measured.Perirenal adipose tissue was stained with HE and the kidneys were stained with HE,PAS and Masson’s trichrome.Perirenal adipose tissue was harvested to examine the expression of CD68,LCA,CD11 C,TNF-a,TGF-β1,Fn1,Smad2,Smad3,Smad4,and Smad7 by immunohistochemical staining,and F4/80 was examined by immunofluorescence staining.Results: The body weights in the LAS group,HAS group,L102 group and H102 group were significantly lower than those in the HFD group(P<0.05).Except for that in the HFD group,the volume of perirenal adipocytes in the other groups was small and uniform(P<0.05).Compared with the LAS,HAS,L102 and H102 groups,the HFD group had a larger glomerular cross-sectional area,proliferation of mesangial cells and the mesangial matrix,and increased matrix area/glomerular area(P<0.05).The effect of LS-102 was better than that of astragaloside IV at the same concentration(P<0.05).Compared with those in the HFD group,glucose,HDL,LDL and urea levels in the LAS group,HAS group,L102 group and H102 group were significantly decreased(P<0.05).The expression of F4/80,CD68,LCA,TNF-a,CD11 C,and PAI-1 in perirenal adipose tissue in the HFD group was significantly higher than that in the LAS group,HAS group,L102 group and H102 group(P<0.05).Compared with those in the HFD group,the expression levels of TGF-β1 and Fn1 in the HAS group,L102 group and H102 group were significantly increased(P<0.05).Compared with the HFD group,the HAS group,L102 group and H102 group had decreased immunopositive rates of Smad2,Smad3 and Smad4(P<0.05).At the same concentration,the effect of LS-102 was better than that of astragaloside IV(P<0.05).There was no significant difference in the positive expression rate of Smad7 in perirenal adipose tissue of all experimental groups(P>0.05).Conclusion:Astragaloside IV and LS-102 improved the inflammatory reaction in perirenal adipose tissue and renal pathological changes in obesity-related nephropathy model mice and inhibited the TGF-β1/Smad signaling cascade.At the same concentration,the effect of LS-102 was better than that of astragaloside IV.These results suggest that LS-102 has a better protective effect against obesity-related nephropathy.LS-102 may be a new type of traditional Chinese medicine for the clinical treatment of obesity and its related metabolic diseases.