| Objective: Diabetes mellitus is one of the most harmful disease for human health,Diabetic nephropathy is its major chronic microangiopathy which is the one of major cause of human diabete death.The prevalence of DN is predicted to increase in the decades ahead. DN is a major cause of end-stage renal disease, and new therapeutic approaches are required to limit its development. Evolution of these will depend on understanding the molecular mechanisms driving glomerulosclerosis and interstitial fibrosis in DN. This review surveys current understanding in this area.Diabetic nephropathy is characterized by excessive deposition of extracellular matrix proteins in the mesangium and basement membrane of the glomerulus and in the renal tubulointerstitium. Expansion of the mesangial matrix and thickening of the glomerular basement membrane (GBM) in DN could be due to either increased accumulation of proteins that are normally present in these structures or to deposition of proteins that are not present in normal tissue or to both. The basement membrane changes, accompanied by glomerular hyperfiltration, and increased glomerular hydrostatic pressure lead to microalbuminuria. However, the mesangial changes appear to be the main cause of declining renal function in DN. As the mesangial matrix expands, it impinges on glomerular capillaries, reducing the surface available for filtration and narrowing or occluding the lumen.According to recent studies,a number of Cytokines closely corelates with the pathophysiological mechanisms of diabetic nephropathy. In vitro and in vivo studies have shown that several different growth factors are upregulated in DN, and the signaling path-ways these activate ultimately regulate transcription factors affecting glomerular ECM accumulation. The principle factors and hormones involved are angiotensinⅡ(AngⅡ),TGF-βand insulin-like growth factors (IGF). A delicate balance between ECM synthesis and degradation under physiologic conditions prevents fibrosis. AngⅡinduces via AT1 receptors plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1). PAI-1 and TIMP-1 inhibit metalloproteinases and thereby matrix turnover, resulting in accumulation of ECM. Megsin is an mesangium-predominant gene,located in 18q21.3, binding with the serine protease,and play a serine protease inhibitor (serpin) activity. As a member of the serpin, involvement pathogenesis of diabetic nephropathy, megsin has been implicated in the regulation of mesangial matricx metabolizm of diabetic nephropathy,influences activities of matrix metalloproteinase, stimulates a number of cytokines and inflammatory factors.We are intended to explore the effects of angiotensinⅡon expression of Megsin,PAI-1 and IGF-1 in renal tissue of diabetic rats, whether AngⅡis initiating agent of the change.We constructed STZ-induced diabetic rats model, then with randomized control trial, divided in to three groups: control group, types 1 diabetes, ramipril intervention group.We examine the differential changes and the expression of megsin,PAI-1,IGF-1in renal tissue between three groups with immunohistochemistry and western- blot,to investigate the relation between AngⅡand megsin,PAI-1,IGF-1, which may provide an important therapeutic targets that can be translated into clinical treatments for diabetic nephropathy.Methods: 48 Healthy male SD-Rats, aged 12 weeks, of clean grade, weighing 200-220 g, were randomly divided to 3 groups.One of 3 groups was regarded as normal control group(A),then the others received a single intraperitoneal injection of STZ(dissolved in 0.1mol/L citrate buffer,pH 4.5)at a dose of 65mg/kg Wt.The diabetic model was considered to be successful when the blood glucose was 16.7mmol/L randomly after 72 hours of STZ injection.Among these divided in to types 1 diabetes group (B)and intervention group(C) with ramipril,3mg /kg/d.All rats were allowed free access to food and water during the experiment. At the end of 12 week,collecting the blood,24-hour urine and renal tissue samples,testing serum creatinine;24h urinary protein excretion rate, creatinine;kidney weight/body weight ratio; staining renal tissue by HE and MASSON , observed the changes in glomerular pathology in ordinary light microscope.The expression of megsin, PAI-1,IGF-1in renal cortex was measured with immunohistochemical method and Western-Blot.The results were semiquantitatively analyzed with an image-processing system. All the data were analysed by SPSS13.0 statistics software,P value<0.05 was considered to have statistical significance.Results:1. The rats of group B and C all presented polydipsia, polyuria and polyphagia after 4 or 5 days of STZ injection,but not in A. Kidney mass/body mass ratio,UP and Scr were higher in group B and C at 12 weeks(P<0.01),group B in those were highest(P<0.01).2. Light microscopy:at 4 weeks,the number of glomerular cells in group C was more than in group A (p<0.01),but less than group B (p<0.01),the number of glomerular cells decreased in group C at 12 weeks ,but still higher than in group A (p<0.01), less than group B (p<0.01) ; glomerular hypertrophy, thickening of GBM and accumulation of ECM in group C were significantly higher than those in group A ,but group B is the most serious.3. Immunohistochemistry and renal tissue protein Westen-bolt: The results of immunohistochemistry and Western blot showed that the expression of megsin, PAI-1, IGF-1, at the end of 8 weeks, was obviously increased in group B and C than group A ( (p<0.05,p<0.01),there was a significant difference (p<0.05,p<0.01). Changes of above-mentioned indicators were more significantly different among these groups at 12 weeks (p<0.05,p<0.01).Conclusion:1. The upregulation of megsin in renal tissue in diabetic rat, corelates with accumulation of ECM,thickening of GBM, mesangial cells hyperplasia, renal hypertrophy and renal dysfunction,suggesting that megsin may play a role in the development and progression of diabetic nephropathy.2. The study demonstrate that decreased renal AngⅡconcentration associated with decreased expression of megsin,PAI-1,IGF-1in renal tissue, implicated that AngⅡmay be the transcription activator of megsin, PAI-1, IGF-1. AngⅡinduces increased expression of megsin,PAI-1,IGF-1in renal tissue, although the mechanism of that has not been clear.3. Ramipril ameliorate glomerular mesangial matrix accumulation and tubulointerstitial fibrosis.
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