| Backgrounds: Renal tubulointerstitial fibrosis is the mutual pathological variation in the continuous progress of many chronic renal diseases, also is the key cause of giving rise to end-stage renal disease, what’ more, it brings about serious ‘disease burden’ for the society and family. All of these impelled ‘chronic renal diseases- renal tubulointerstitial fibrosis’ to be the more concerned focus in study of renal diseases. Renal tubulointerstitial fibrosis of chronic renal diseases was correlated with single nucleotide polymorphism, and the activation of multiple signal transduction pathway mediated its occurrence and development. As the main active ingredient of Tri pterygium wilfordii, triptolide was widely used in treatment of kinds of renal diseases,however, its mechanism was worthy of further study.Purpose: To clarify the effect of endothelial nitric oxide synthase(eNOS) 4b/a polymorphism on the susceptibility to renal tubulointerstitial fibrosis of diabetic nephropathy(DN); to investigate the effect of triptolide on signal transduction pathway of TSP1/TGF-β1 and TLR4/NF-κB in renal tubular cells.Methods: 1. Using method of meta-analysis, we performed a computerized search of PubMed, EMBASE, CBM, CSTJ, CJFD and WanFang to identity case-control studies on relationship between eNOS 4b/a polymorphism and susceptibility to renal tubulointerstitial fibrosis of DN. Statistic analysis and heterogeneity test were conducted by StataSE12; 2. After culturing human renal tubular epithelial cells, the effects of low, moderate and high concentrations of triptolide on signal transduction pathway of TSP1/TGF-β1 and TLR4/NF-κB were observed.Real Time PCR was used to detect the mRNA expression of. Western blot was used to detect the protein expression. ELISA was used to detect the level of total and active TGF-β1.Results: 1. The meta-analysis involved 26 studies for DN comparing with diabetes mellitus(DM) and 15 studies for DN comparing with healthy persons, which provided 6144/4900cases/controls and 2134/2348 cases/controls, respectively. Moderate heterogeneity was found among included studies. Meta-analysis derived a significant association between the eNOS 4b/aand the risk of developing renal tubulointerstitial fibrosis for DN. The sensitivity analysis(exclusion of studies not in Hardy-Weinberg equilibrium) produced non-significant changes.Compared with diabetes patients, the pre-allele model produced certain association in global populations(OR=1.26, 95% CI: 1.10-1.45), significant association in Asian population(OR=1.51,95% CI: 1.13-2.01) and certain association in type 2 DM patients(OR=1.29, 95% CI: 1.09-1.54).Only in the dominant model, the funnel plot and Egger’s test provided evidence of publication bias(P=0.024); 2. Our vitro experiment indicated: when compared to own negative control, the mRNA and protein expression of TSP1/TGF-β1, TLR4/NF-κB in positive group were up-regulated simultaneously; when compared to own positive control, moderate and high concentration triptolide inhibited the mRNA and protein expression of TSP1/TGF-β1 obviously,the same result for TLR4/NF-κB. And moderate and high triptolide could markedly reduce the expression of total and active TGF-β1.Conclusion: 1. The meta-analysis demonstrated a correlation of eNOS 4b/a polymorphism with susceptibility to renal tubulointerstitial fibrosis of DN, especially in Asian population.However, the more reliable findings need more rigorous and prospective studies; 2. Our vitro experiment indicated that triptolide could down-regulate the mRNA and protein expression of TSP1/TGF-β1 in renal tubular cells, so as to inhibit the activation of TSP1/TGF-β1 pathway and secretion of active TGF-β1, also, triptolide could down-regulate the mRNA and protein expression of TLR4/NF-κB in renal tubular cells to inhibit the activation of TLR4/NF-κB pathway. |
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