原卟啉IX合成通路遗传变异与抗结核药致肝损害易感性及其分子机制研究

抗结核药致肝损害是一种严重不良反应，其机制仍不清楚，近来动物实验提示可能与内源性毒性物质-原卟啉IX（PPIX）在肝细胞内蓄积有关。利福平通过孕烷X受体介导引起5-氨基酮戊酸合成酶1（ALAS1）和细胞色素P450表达上调；异烟肼引起ALAS1酶活性升高且抑制亚铁螯合酶表达，两者协同导致PPIX合成增加且不能转化，继而蓄积导致肝损害。本研究拟基于已有家庭抗结核治疗动态随访队列，监测肝功能和收集尿液，开展1:4匹配病例对照研究。以PPIX合成通路为基础，采用超深度目标区域捕获测序筛选和Sequenom平台验证相结合，分析遗传变异分布、相关合成酶和代谢产物水平与肝损害关系，探讨基因-环境-表型多重交互效应，构建肝损害遗传变异预测模型，鉴定相关基因野生型和突变型对转录调控的影响，从人群角度阐明PPIX合成通路遗传变异在肝损害发生中的作用及可能机制，为早期识别和预防肝损害及制定个体化治疗提供依据。

Anti-tuberculosis drug-induced liver injury (ATLI) is a serious adverse drug reaction, and its pathogenic mechanism is still largely unknown. Recent animal experiments indicated that ATLI may be related to the accumulation of endogenous toxic substance - protoporphyrin IX (PPIX) in liver cells. Rifampicin could upregulate the expression of 5-aminoketovalerate synthase 1 (ALAS1) and cytochrome P450 via pregnant X receptors. Isoniazid could increase ALAS1 enzyme activity and inhibit ferrochelatase expression. The synergistic effect of these factors resulted in increased synthesis of PPIX and its inability to be transformed, followed by PPIX accumulation and the occurrence of ATLI. This study is based on an existing family follow-up cohort of anti-tuberculosis treatment. The liver function of the patients will be monitored and their urine will be collected. After the occurrence of liver injury is judged, a 1: 4 individual-matched case-control study will be performed. Based on the PPIX biosynthesis pathway, the two-stage genetic variation detection combined with ultra-deep target region capture sequencing screening and further Sequenom MassArray platform verification will be conducted. The relationship between genetic variation distribution, related synthetase and metabolite levels and liver injury will be analyzed, and the multiple interaction effects of gene-environment-phenotypes will be explored. The predictive model of genetic variation of liver injury will be constructed based on these analyses. Cell experiments will be conducted to identify the influence of wild-type and mutant types of related genes on transcriptional regulation. The present study aims to investigate the role of genetic variation of the PPIX biosynthesis pathway in the development of liver injury from a population perspective and to explore the possible mechanism, which will provide a basis for early identification and prevention of liver injury and the development of individualized anti-tuberculosis treatments.