Effect Of P38mapk On Expression Of Mmp-9 And Timp-1 Induced By High Glucose In Glumeruli Mesangial Cells

Objective:Diabetic nephropathy (DN) is one of the most important microvascular complications of diabetes and occurs in 20-30% of diabetic patients, which results in end-stage renal disease(ESRD). The important pathological changes in DN are characterized by the thichening of glomerular basement membrane and increasing of extracellular matrix(ECM), leading to glomerular hyperfiltration and microalbuminuria. Mesangial cell plays important role in these pathological processes. Although many studies on the mechanism of DN have been performed in past years, the exact pathogenesis of DN remains largely unknown. Recently, more and more people pay attention to the important role of p38 mitogen-activated protein kinase (p38MAPK) signal transduction pathways in DN. The accumulation of glomerular ECM is due to imbalance of the synthesis and degradation of ECM. The previous researches mainly focus on the ECM sythesis, and decreasing of degeneration of ECM in DN is taken attention recently. Matrix metalloproteinase (MMPs) and their specific tissue inhibitors (TIMPs) play the key role in ECM degradation, many researches suggest that MMPs and TIMPs are involved in the pathogenesis of some renal diseases. But their effects on the development and progression of DN have not been fully explored, and the relationship between.MMPs/TIMPs and p38MAPK is less well defined. Therefore, we investigated the effect of high glucose and SB203580, inhibitor of p38MAPK, on the expression of p38MAPK and MMP-9/TIMP-1 in cultured SD rat glomerular mesangial cell and discuss the mechanism of p38MAPK signal transduction pathways in DN as well as the relation between p38MAPK and MMP-9/TIMP-1.Methods:SD rat glomerular mesangial cell in culture were divided into 6 groups, normal glucose group(5.6mmol/L), high glucose group(including different concentration gluclose:10 mmol/L,20mmol/L,30 mmol/L), SB203580 group(30 mmol/L glucose plus 10 u mol/L SB203580) and mannitol group(5.6mmol/L glucose +24.4mmol/L mannitol). After the cells were incubated in different conditions for 72 hours, total RNA was isolated with Trizol reagent. The expression of p38MAPK, MMP-9 and TIMP-1 mRNA were examined by Real time Quantitative PCR. Results:1. p38MAPK, MMP-9 and TIMP-1 mRNA expressed in normal glucose group; 2.the expression of p38MAPK mRNA was increased in high glucose group and mannitol group than that in normal glucose group, but the expression of p38MAPK mRNA in high glucose groups was much higher than mannitol group, which was in a concentration-dependent manner; 3.compared with normal glucose group, the expression of TIMP-1 mRNA was increased, but MMP-9 mRNA and MMP-9/TIMP-1 mRNA ratio in high glucose groups and in mannitol group were decreased; these changes in high glucose groups were more significantly than that in mannitol group, which were dependent of glucose concerntration; 4. the expression of MMP-9 mRNA and MMP-9/TIMP-1 mRNA ratio were higher in SB203580 group, and TIMP-1 mRNA was lower than that in high glucose group(30 mmol/L), whereas there was no significant difference between high glucose group and SB203580 group in the expression of p38MAPK mRNA.Conclusion:1. high glucose can increase significantly the expression of p38MAPK and TIMP-1 mRNA, and decrease the expression of MMP-9 mRNA and MMP-9/TIMP-1 mRNA ratio in cultured mesangial cells, and these changes are dependent of glucose concentration; 2. mannitol increase the expression of p38MAPK mRNA in mesangial cells, high osmitic pressure at least partly participates in increasing of p38MAPK mRNA induced by high glucose; 3. the inhibitor of p38MAPK can reverse the changes of MMP-9, TIMP-1 mRNA and MMP-9/TIMP-1 mRNA tatio induced by high glucose, but can not inhibit the increased expression of p38MAPK mRNA induced by high glucose; 4. p38MAPK is related to the expression of MMP-9 and TIMP-1 mRNA in diabetic nephropathy.