Association Of Chemerin/Chem R23 And Endothelial-mesenchymal Transition In Diabetic Nephropathy

ObjectiveChemerin is a novel adipocyte-derived factor which plays a variety of roles through its main receptor Chem R23. Chemerin is closely related to transdifferentiation stimulating factors. Under the action of transdifferentiation stimulating factors, endothelial cells can transdifferentiation to fibroblasts. While End MT play an significant role in the mechanism of diabetic nephropathy.This study aims to determine the expression of Chemerin/ Chem R23 in the kidney of diabetic rats during the progression of pathological process, and then analyze the association of Chemerin/Chem R23 expression with End MT. MethodsEighty male, 6-8 weeks and weight of 160-180 g Sprague-Dawley(SD)rats were randomly distributed to 2 groups: normal control group( n=40) and diabetic nephropathy model group(n=40). The rats in diabetic nephropathy model group were abrosia but can drink water for 12 hours, then injected STZ(streptozotocin)into abdomen of rats to establish diabetic SD rats model, while the rats in normal control group were injected citrate buffer solution. Random blood glucose were measured after 72 h of the injection for three days, the rat was classified as model rat when the random blood glucose was over 16.7mmol/l. Blood glucose、body weight and urinary albumin / creatinine ratio(UACR)were measured every week. The rats were sacrificed at the end of one week, two weeks, three weeks, four weeks and twelve weeks after STZ injection, 8 rats in normal control group and 8 rats in model group were sacrificed at each time point. The right kidney weight were measured when the rats were sacrificed and the kidney to body weight ratio(KBWR)were calculated. The morphological changes of renal tissues were observed under microscope after PAS histologicalstaining. Chemerin and Chem R23 expression were determined by immunohistochemical method. The cells co-expression of α-SMA and CD31 in kidney tissues were determined by immunofluorescence double labeling. The protein expression of Chemerin、Chem R23、CD31、α-SMA in kidney tissues were determined by Westem Blot. The genetic expression of Chemerin、Chem R23、transforming growth factor-β1(TGF-β1) in kidney tissues were determined by q RT-PCR. Spearman correlation analysis was performed to analyze the association of chemerin with chem R23、TGF-β1, CD31, α-SMA, the number of CD31 and α-SMA double positive cells. ResultsCompared with the normal control groups with the same age, model rats had higher random blood glucose, lighter body weight and appeared polydipsia, polydipsia and polyphagia. Compared with the normal control groups with the same age, UACR and KBWR bigan to signifieantly inereased in 4 weeks’ model rats, creatinine were signifieantly inereased in 12 weeks’ model rats. We could see that the glomerular mild hypertrophy in 4 weeks’ model group, glomerular basement membrane mild thicken and mesangial matrix mild roliferation in 12 weeks’ model with PAS stain; Immunohistochemistry showed that diabetic rats have remarkably higher expression levels of Chemerin and Chem R23 compared with the control group. Western Blot results showed that Chemerin、Chem R23、α-SMA expression continued to increase, while CD31 continued to decrease as the disease progresses. The q RT-PCR results showed that the genetic expression of Chemerin、Chem R23、transforming growth factor-β1 continued to increase. The co-expression of α-SMA and CD31 in kidney tissues started to appear in 4 weeks’ model rats and increased in the 12 weeks’ model rats. Spearman correlation analysis showed that Chemerin m RNA expression level was positively correlated with Chem R23 m RNA expression level、TGF-β1 m RNA expression level、α-SMA protein expression level、the number of CD31 and α-SMA double positive cells, while negatively correlated with CD31 protein expression level. ConclusionAs the progression of the diabetic nephropathy in the DM rats, Chemerin and Chem R23 continue to increase, the number of the fibroblasts transdifferentiated from endothelial cells also have an increase. Chemerin is relevant with End MT in diabetic nephrology rats.