| Objective: Diabetic nephropathy (DN) encompasses a complex of structure alterations, including the hypertrophy of glomerulus and renal tubule in early stage, and glomerulosclerosis, tubulointerstitial fibrosis (TIF) in late stage. It has been demonstrated that the development of TIF is more closely correlated with a progressive decline in renal function compared with glomerulosclerosis and is a common final pathway leading to end-stage renal failure. Myofibroblasts are a group of smooth-muscle-like fibroblasts. In the development of TIF they play a critical role. They can not only synthesis collagen but also expressα-smooth muscle actin(α-SMA) which is the marker of smooth muscle cell. Myofibroblast (Myof) can be identified by expression ofα-SMA. There is hardly any myofibroblast in normal renal tissue, but the number of myofibroblasts would increase obviously in the pathologic renal tissue. The origin of these cells remains poorly understood. It is considered that Myof may be derived from the differentiation of interstitial fibroblast, but other renal inherent cells are capable of transdifferentiation into myofibroblasts. Recently the tubular epithelial myofibroblast transdifferentiation at various renal diseases has been extensively paid more attention and considered as an important origin of Myof.In the past few years, there was great progress in the research of molecular mechanism of the chronic renal fibrosis. However the relation between hepatocyte growth factor (HGF) and chronic renal fibrosis has not been studied in detail. It is suggested that HGF is a kind of nutritional factor for kidney, which play a pivotal role in the process of tubule repair after injury and the process of renal regeneration. At present there are debates about the effect of HGF on TIF, which has close relation with chronic renal disease and chronic renal failure. In the present study, we investigate the tubular epithelial-myofibroblast transdifferentiation and the expression of HGF, further to clarify the role of these factors in diabetic nephropathy.Methods: Experimental diabetes was induced by injection of streptozotocin (STZ) in male Sprague Dawley (SD) rats. The animals were divided into two groups after unilateral nephrectomy: group A (control) and group B (diabetic). The rats of group B received a single intraperitoneal injection of STZ dissolved in 0.1mol/L sodium citrate (pH 4.5) at a dose of 65mg/kgWT. The rats of group A only received an injection of the same volume of 0.1mol/L sodium citrate. The model of diabetes was considered to be successful when the blood glucose was ≥16.7mmol/L and the glucose in urine was +++～++++ after 24 hours of the injection. Six animals were killed respectively at weeks 8, 16 and 24 after injection. Blood and urine were collected and used to assay biochemical parameters, then the residul kidney was removed and prepared for light microscopy, immunohistochemistry, flow cytometry, in situ hybridyzation and western blot. The protein expression of cytokeratin18,α-SMA, HGF was evaluated by immunohistochemistry or flow cytometry. The mRNA expression of HGF was detected by in situ hybridyzation. The protein expression of c-met was detected by western blot. All data were expressed as . F and T test was separately used to analyse the difference between the two groups and within one group, Correlation analysis between the different parameters were performed using the single Spearman cofficient,which was finished with SPSS10.0 software.Results: 1. Compared with that of control rats, the change of renal function in diabetic rats included the increase of blood sugar, blood urine nitrogen and urine protein. 2. Compared with that of control rats, the glomerular enlargement mesangial expansion and vacuole in some tubular cells were observed in diabetic rats. At week 24, the morphologic changes were more obvious, including tubular atrophy, hyaline casts in tubular lumen, basement membrane thickening, interstitial expension and fibrous tissue proliferation. 3. Immunohistochemically... |
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