Protective Effects And Mechanismexplorations Of Tilapia Skin Peptides And Fucoxanthin On Experimental Diabetic Nephropathy

Objective:To explore the protective effects and mechanisms of marine bioactive substances tilapia skin peptides(TSPs)and fucoxanthin(Fx)on experimental diabetic nephropathy(DN).Methods:Research on TSPs consisted two parts.Firstly,animal model of DN was established:The diabetic model rats were induced by streptozotocin(STZ).The experimental rats were divided into normal control group,diabetic group,TSPs treatment group and metformin control group.At the end of the experiment period,HE,PAS and Masson staining were performed in kidney sections of rats in each group.Secondly,cell model of DN was established:The cell model was divided into normal glucose group,high glucose(HG)group and TSPs treatment group.The glomerular mesangial cells(GMCs)were cultured with 5.5 mM glucose in normal glucose group and 30 mM glucose in HG group.Western blot was used to detect the protein expressions of FN,collagen Ⅳ,ICAM-1,Bnip3,Nix in GMCs of each group.The distributions of FN and Bnip3 in GMCs of each group were detected by immunofluorescence staining.Fluorescent probe staining was used to observe mitochondrial morphology and detect the expressions of mitochondrial membrane potential,mitochondrial superoxide and cellular reactive oxygen species in GMCs of each group.Research on Fx also consisted two parts.Firstly,animal model of DN was established:The diabetic model rats were induced by STZ.The experimental rats were divided into normal control group,diabetic group,Fx treatment group and metformin control group.At the end of the experiment period,HE,PAS and Masson staining and immunohistochemistry staining of p62,Keapl and Nrf2 were performed in kidney sections of rats in each group.The expressions of FN,collagen Ⅳ,α-SMA and TGF-β in kidney of rats in each group were detected by western blot.Secondly,cell model of DN was established:The cell model was divided into normal glucose group,HG group and Fx treatment group.The GMCs were cultured with 5.5 mM glucose in normal glucose group and 30 mM glucose in HG group.Western blot was used to detect the protein expressions of p62,LC3,Keap1,Nrf2,SOD1,HO-1,FN and collagen Ⅳ in GMCs of each group.Fluorescent probe staining was used to observe mitochondrial morphology and detect the expression of mitochondrial membrane potential in GMCs of each group.Results:In the STZ-induced diabetic rats,TSPs decreased the levels of KW/BW,BUN,Cr,24 h urinary protein,TG,TC and LDL-C,and reduced the mesangial matrix index and collagen percentage of kidney.TSPs inhibited the expressions of FN,collagenⅣ and ICAM-1,upregulated the expressions of Bnip3 and Nix,improved the morphology of mitochondrial and the decrease of mitochondrial membrane potential,and decreased the levels of mitochondrial superoxide and cellular reactive oxygen species in HG-induced GMCs.In the STZ-induced diabetic rats,Fx decreased the levels of KW/BW,BUN,Cr,24 h urinary protein,TG,TC and LDL-C,reduced the mesangial matrix index and collagen percentage of kidney,and inhibited the expressions of FN,collagen Ⅳ,α-SMA and TGF-βin the kidney.Fx upregulated the expressions of p62 and Nrf2,and inhibited the expression of Keapl in the kidney of STZ-induce diabetic rats.Fx inhibited the expressions of Keapl,FN and collagen Ⅳ,upregulated the expressions of p62,LC3 Ⅱ/LC3 I,Nrf2,SOD1 and HO-1,and improved the morphology of mitochondrial and the decrease of mitochondrial membrane potential in HG-induced GMCs.Conclusion:TSPs can improve the pathological damage of experimental DN and alleviate DN renal fibrosis in vivo and in vitro,including metabolic parameters and renal pathology in STZ-induced diabetic rats and fibrosis in HG-induced GMCs.The mechanism may be related to the improvement of mitochondrial dysfunction by regulating mitophagy.Fx can improve the pathological damage of experimental DN and alleviate DN renal fibrosis in vivo and in vitro,including metabolic parameters and renal pathology in STZ-induced diabetic rats and fibrosis in HG-induced GMCs.The mechanism may be related to the regulation of p62/Keap1/Nrf2 pathway and the improvement of mitochondrial damage.Our study suggests that TSPs and Fx could be the potential therapeutic strategies for DN.