SPECIFICITY OF IN-VITRO COVALENT BINDING OF TIENILIC ACID METABOLITES TO HUMAN LIVER-MICROSOMES IN RELATIONSHIP TO THE TYPE OF HEPATOTOXICITY - COMPARISON WITH 2 DIRECTLY HEPATOTOXIC DRUGS
SPECIFICITY OF IN-VITRO COVALENT BINDING OF TIENILIC ACID METABOLITES TO HUMAN LIVER-MICROSOMES IN RELATIONSHIP TO THE TYPE OF HEPATOTOXICITY - COMPARISON WITH 2 DIRECTLY HEPATOTOXIC DRUGS
复制标题
DOI：
10.1021/tx00039a023
复制
发表时间：
1994-05-01
影响因子：
4.1
通讯作者：
BEAUNE, PH
中科院分区：
文献类型：
--
作者：
LECOEUR, S;BONIERBALE, E;BEAUNE, PH
为了更好地了解导致药物诱导的免疫过敏性肝炎的第一步，我们研究了在替尼酸诱导的肝炎中出现的抗LKM 2自身抗体的靶点，以及替尼酸反应性代谢产物的靶点。它被鉴定为细胞色素P450 2C 9（P450 2C 9）：实际上，抗LKM 2特异性识别P450 2C 9，但没有检测到其他P450（包括其他2C亚家族成员，2C 8和2C 18）。替尼酸反应性代谢物特异性结合P450 2C 9，并且用表达活性分离的P450的酵母进行的实验表明，P450 2C 9负责替尼酸反应性代谢物的产生。然后将替尼酸代谢产物与人肝微粒体的定性和定量共价结合结果与导致直接中毒性肝炎的两种药物（即对乙酰氨基酚和氯仿）的结果进行比较。测定了动力学常数（Km和V-max），并研究了代谢产物与人肝微粒体蛋白的共价结合特征。在药理学剂量下，替尼酸具有最低的K-m和最高的共价结合率。对乙酰氨基酚和氯仿，几个微粒体蛋白共价结合，而共价结合是高度特异性的替尼酸和双肼屈嗪，另一种药物导致免疫过敏性肝炎。虽然测试的药物数量较少，但这些结果使我们认为共价结合的特异性与肝毒性类型之间可能存在关系。
In order to better understand the first steps leading to drug-induced immunoallergic hepatitis, we studied the target of anti-LKM2 autoantibodies appearing in tienilic acid-induced hepatitis, and the target of tienilic acid-reactive metabolites. It was identified as cytochrome P450 2C9, (P450 2C9): indeed, anti-LKM2 specifically recognized P450 2C9, but none of the other P450s tested (including other 2C subfamily members, 2C8 and 2C18). Tienilic acid-reactive metabolite(s) specifically bound to P450 2C9, and experiments with yeast expressing active isolated P450s showed that P450 2C9 was responsible for tienilic acid-reactive metabolite(s) production. Results of qualitative and quantitative covalent binding of tienilic acid metabolite(s) to human liver microsomes were then compared to those obtained with two drugs leading to direct toxic hepatitis, namely; acetaminophen and chloroform. Kinetic constants (K-m and V-max) were measured, and the covalent binding profile of the metabolites to human liver microsomal proteins was studied. Tienilic acid had both the lowest K-m and the highest covalent binding rate at pharmacological doses. For acetaminophen and chloroform, several microsomal proteins were covalently bound, while covalent binding was highly specific for tienilic acid and dihydralazine, another drug leading to immunoallergic hepatitis. Although low numbers of drugs were tested, these results led us to think that there may exist a relationship between the specificity of covalent binding and the type of hepatotoxicity.