转化生长因子β1基因多态性对乙型肝炎肝硬化的影响

目的探讨转化生长因子β1(TGFβ1)基因多态性与乙型肝炎肝硬化的关系及其对血浆TGFβ1浓度的影响.方法分别应用聚合酶链反应-扩增难控性突变系统(PCR-ARMS)和Lightcycler结合测序的方法,测定了92名健康对照者和134例肝硬化患者TGFβ1基因-988、-800、-509、codon10、codon25和codon263位点的单核苷酸多态性,并确定了其基因型和等位基因频率的分布;用ARLEQUN Ver2.0软件分析了-509位点和codon10位点等位基因之间是否存在连锁不平衡;用ELISA的方法检测了血浆中TGFβ1和Ⅳ型胶原的浓度,用放射免疫法检测了血浆中透明质酸和Ⅲ型前胶原N端肽.结果本研究中TGFβ1基因-988、-800、codon25和codon263位点不存在基因多态性;-509位点基因型及等位基因分布频率在肝硬化组和正常对照组中差异无统计学意义,codon10TT基因型及等位基因T在肝硬化组中的分布频率(0.313,0.537)明显高于对照组(0.196,0.440).把肝硬化患者按Child-Pugh分级分为A、B、C 3组,-509CC基因型在肝硬化C级组中的分布频率(0.631)明显高于TT基因型(0.325),codon10位点基因多态性在肝硬化的各个分级组中的分布频率差异无统计学意义.肝硬化组血浆TGFβ1、Ⅳ型胶原、透明质酸及Ⅲ型前胶原N端肽的浓度显著高于对照组.在对照组中,血浆TGFβ1浓度在-509位点两种基因型之间差异无统计学意义.在肝硬化组中,-509CC基因型者血浆TGFβ1浓度[(25±12) μg/L]显著高于TT基因型者[(8+4) μg/L];codon10位点各种基因型血浆TGFβ1浓度在对照组和肝硬化组中差异均无统计学意义.-509位点和codon10位点等位基因存在连锁不平衡,其单倍型形式主要是C-T和T-C,其中单倍型者C-T血浆TGFβ1浓度[(21±9) μg/L]明显高于其他人[(11±4) μg/L],且该单倍型在肝硬化组中的分布频率明显高于对照组.结论 TGFβ1基因-509 C>T多态性与肝硬化的发生没有密切关系,但与肝硬化的进展程度相关,该多态性影响肝硬化患者血浆中TGFβ1的浓度;codon10T>C多态性与肝硬化的发生有明显相关性,而与肝硬化的进展程度无关.-509位点和codon10位点等位基因存在连锁不平衡,其单倍型形式主要是C-T和T-C,其中单倍型C-T影响TGFβ1的血浆浓度,并且与肝硬化的发生有关.

Effect of polymorphism of transforming growth factor beta1 gene on HBV-induced liver cirrhosis

OBJECTIVE: To explore the effects of transforming growth factor beta1 (TGFbeta1) gene polymorphism on liver cirrhosis induced by HBV infection and on plasma concentration of TGFbeta1. METHODS: Peripheral blood samples were collected from 134 patients with HBV-induced liver cirrhosis, which were further classified into three groups (A, B and C groups) according to Child-Pugh classification and 92 healthy blood donors. The polymorphisms at position -988, -800, -509 and codon10, codon25, and codon263 of TGFbeta1 gene were determined by PCR-ARMS- and Lightcycler respectively, combined with sequence analysis. The concentrations of TGFbeta1 and collagen type IV were measured by ELISA, and the plasma concentrations of hyaluronan and N-terminal type III procollagen peptide were measured by RIA. ARLEQUIN Ver 2.0 software was used to analyze the linkage disequilibrium between -509C > T and codon10T > C polymorphisms. RESULTS: No polymorphism was found at positions -800, -988, codon25 and codon263. No significant difference for -509C > T polymorphism between the diseased and control groups was found, however, the frequencies of genotype TT and allele T at codon10 in the diseased group were 0.313 and 0.537 respectively, both significantly higher than those of the control group (0.916 and 0.440 respectively, both P < 0.05). In Child-Pugh C grade group the frequency of C allele at position -509 was 0.631, significantly higher than that of T allele (0.325), but there was no significant difference for codon10T > C polymorphism. The TGFbeta1 plasma concentration did not show any difference between the genotypes -509CC and TT in the control group, however, the TGFbeta1 plasma concentration was statistically lower in the those with TT genotype than in those with CC genotype in the diseased group. Linkage disequilibrium was found between -509C > T and codon10T > C polymorphisms and the major haplotypes were C-T and T-C, of which C-T frequency was significantly higher in the patients than in the control group. The plasma concentration of TGFbeta1 was significantly higher in the populations of haplotype C-T than in those of other haplotypes. CONCLUSION: No relationship is found between -509C > T polymorphism of TGFbeta1 and liver cirrhosis in Chinese populations, but the presence of C allele at position -509 may play an important role in the progression of liver cirrhosis and may influence plasma concentration of TGFbeta1 in liver cirrhosis patients. Codon10T > C polymorphism may play a significant role in development of liver cirrhosis, but has no correlation with plasma concentration of TGFbeta1 and progression of liver cirrhosis. The -509C > T and codon10T > C polymorphisms are in tight linkage disequilibrium, and the major haplotypes are C-T and T-C. The haplotype C-T influences plasma concentration of TGFbeta1 and is closely related to liver cirrhosis.