PTPN22基因-1123G/C多态性对溃疡性结肠炎Th17细胞分化的影响

Numerous studies have been performed to identify genetic risk factors for UC, and there are ethnic differences for distribution of genetic risk factors for UC. Our previous studies have shown that PTPN22 gene -1123G/C polymorphism was associated with UC and -1123G/C polymorphism can influence PTPN22.6 protein expression in intestinal mucosa in patients with UC. However, the mechanism of PTPN22 gene in the pathogenesis of intestinal inflammation in UC is unknown. Protein tyrosine phosphatase non-receptor 22 (PTPN22) gene encodes lymphoid-specific tyrosine phosphatase (LYP). LYP is involved in the negative regulation of T cell proliferation, and plays an important role in T cell immune regulation. Th17 cell immunity plays a pivotal role in the pathogenesis of intestinal inflammation in UC; however, the correlations of LYP with Th17 cell differentiation in UC need to be verified by further study. Based on the literature and our previous study, we hypothesize that PTPN22 gene -1123G/C polymorphism affects Th17 cell differentiation and was associated with UC. In present study, we investigate the relationship of PTPN22 gene polymorphisms with UC in central China, and evaluate the relationship of PTPN22 gene -1123G/C polymorphism with LYP mRNA stability and LYP protein expression, and study the polymorphisms’ effects on Th17 cell differentiation. The aim of the study is to investigate the role of PTPN22 gene in the pathogenesis of UC, and to provide a new strategy for target treatment of UC.

溃疡性结肠炎（UC）发病具有遗传易感性，且存在种族差异。前期研究提示，蛋白酪氨酸磷酸酶非受体型22基因（PTPN22）-1123G/C多态性与我国UC相关，其多态性影响肠黏膜PTPN22.6蛋白表达，但该基因在UC免疫学发病机制不明。PTPN22编码淋巴特异性酪氨酸磷酸酶（LYP）。LYP下调T细胞活化，在T细胞免疫中起重要作用。研究表明Th17细胞介导免疫反应与UC发病相关，但LYP与Th17细胞分化的关系是否存在关联尚待核实。基于文献报道及前期基础，提出如下假设，PTPN22基因-1123G/C多态性影响Th17细胞活化并与UC发病密切相关，基于此，本课题设计拟探讨PTPN22基因与UC的关系，-1123G/C多态性对LYP mRNA 稳定性及蛋白的调节，其多态性对Th17细胞分化及炎性因子水平的影响。通过研究对阐明PTPN22基因在UC发病中作用有重要意义，为其靶点治疗UC提供新策略

背景：前期研究提示，蛋白酪氨酸磷酸酶非受体型22基因（PTPN22）-1123G/C多态性与我国UC相关。方法：鉴定PTPN22基因-1123G/C基因型；分析其PTPN22 mRNA表达与-1123G/C多态性的关系。Western blot方法检测PBMCs中PTPN22和PTPN22.6蛋白表达；磁珠分选Naive CD4+ T细胞，加入重组细胞因子IL-6等，促使Naive CD4+ T向Th17细胞分化，收获细胞,研究-1123G/C多态性对Th17细胞下游炎性细胞因子及蛋白表达的影响。结果：UC患者-1123G/C位点C等位基因频率显著高于正常对照组（41.5% vs. 33.5%, P = 0.015, OR = 1.41, 95% CI: 1.07-1.86）。活动期UC患者肠黏膜PTPN22 mRNA水平显著高于缓解期UC患者，差异有统计学意义（t = -5.613, P = 0.005）。PTPN22蛋白的表达水平低于对照者，然而UC患者PTPN22.6蛋白的表达水平高于对照者，差异有统计学意义（t = -3.45，P <0.05；t =-1.24，P<0.05）。PTPN22基因-1123G/C多态性位点C等位基因携带者IL-17F细胞因子表达水平明显高于GG等位基因（6.7% vs. 3.8%, P <0.05）。UC患者磷酸化Lck、Fyn和Zap-70 蛋白表达水平明显高于健康对照者（P <0.05），且在UC患者中，PTPN22基因-1123G/C多态性位点C等位基因携带者Zap-70表达水平明显高于GG等位基因，差异有统计学意义（P <0.05）。UC患者RORγt蛋白表达水平明显高于健康对照者（P <0.05）；UC患者中，PTPN22基因-1123G/C多态性位点C等位基因携带者RORγt表达水平明显高于GG等位基因，差异有统计学意义（P <0.05）。结论：PTPN22基因-1123G/C多态性与我国溃疡性结肠炎相关，其多态性影响PTPN22 mRNA 和蛋白的表达，同时影响PBMC中Th17细胞下游炎性细胞因子表达，提示PTPN22基因-1123G/C多态性在UC遗传免疫学发病机制中具有一定作用。