Effects of EPO on NK cell activation receptor and HMGB1/Beclin-1 signaling pathway in diabetic nephropathy rats
Objective:To explore the mechanism of EPO on activating receptors of NK cells in rats with diabetic nephropathy based on HMGB1/Beclin-1 signaling pathway.Methods:Forty SPF male SD rats were randomly divided into normal group(A),model group(B),metformin group(C)and EPO group(D),with 10 rats in each group.Diabetic nephropathy modeling was performed on groups B,C and D using high-fat diet and streptozotocin.After successful modeling,group C was given metformin 100 mg/kg by intra-gastric administration,and group D was intraperitoneal injection of EPO 100 U/kg.Group A and B were given normal saline at the same volume by intragastric administration simultaneously.After successful modeling,the remaining 20 rats were randomly divided into group E and group F.Group E was given 30 mg/kg HMGB1 inhibitor by intragastric administration,group F was given 30 mg/kg HMGB1 inhibitor by intragastric administration and 100 U/kg EPO by intraperitoneal injection.HK-2 cells were taken and divided into high glucose+HK-2 cells(HH)group,EPO+high glucose+HK-2 cells(EH)group,glycyrrhizin L+high glucose+HK-2 cells(LH)group,and cultured with glucose for cell experiment.Blood glucose was detected by glucose analyzer,biochemical indexes were de-tected by automatic biochemical analyzer,and renal pathological morphology of rats was detected by PAS staining.Expression of HMGB1/Beclin-1 protein was detected by Western blot,and expressions of NK cell activated receptors were detected by RT-PCR and immunohistochemistry.Results:Compared with group A,blood glucose,24 h urine volume,blood glucose curve,BUN,Scr,UAlb contents in blood and urine,mRNA and protein expressions of NKp30,NKp44,NKp46 in group B were significantly increased(P<0.05),while body weight was significantly decreased(P<0.05).Compared with group B,blood glucose,24 h urine volume,blood glucose curve,BUN,Scr,UAlb contents in blood and urine,mRNA and protein expression of NKp30,NKp44 and NKp46 in group C and group D were significantly decreased(P<0.05),while body weight was significantly increased(P<0.05),renal pathology was also significantly improved,the changes of group D was significantly higher than that of group C(P<0.05).Compared with group A,expression of HMGB1/Beclin-1 protein in renal tissues of rats in group B was significantly increased(P<0.05),and expression of HMGB1/Beclin-1 protein in renal tissues of rats in groups C,D,E and F was significantly decreased(P<0.05),expression of HMGB1/Beclin-1 protein in group D was significantly decreased compared with group C(P<0.05),there was no significant difference between group E and group D,and expression of HMGB1/Beclin-1 protein in group F was significantly decreased compared with group E.HMGB1/Beclin-1 protein expression was positively correlated with NKp30,NKp44 and NKp46 mRNA(P<0.05).Compared with HH group,proliferation rates of EH and LH groups were significantly increased(P<0.05),while apoptosis rate and HMGB1/Beclin-1 protein expression were significantly decreased(P<0.05),there was no significant difference between LH group and EH group(P>0.05).Conclusion:EPO can effectively reduce expressions of NK cell activated receptors and inhibit HMGB1/Beclin-1 signaling path-way in diabetic nephropathy rats,suggesting that EPO may exert its effect by regulating NK cell activated receptors and HMGB1/Beclin-1 signaling pathway.NK cell activation receptors expressions are positively correlated with HMGB1/Beclin-1 signaling pathway.
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