MECHANISMS OF DRUG-INDUCED TOXICITIES

今年，我们继续研究 吸入性肝炎的机制。我们的目标就是 确定肝毒性产生的分子基础 氟烷在豚鼠模型中的作用，并确定 免疫系统接触到三氟乙酰化的 （TFA）-与这种毒性相关的抗原。雄性远交哈特利 给豚鼠注射氟烷， 在8和48小时后收集。根据血清ALT水平， 肝脏组织学，给药动物可被指定为 对氟烷诱导的肝损伤敏感或不敏感。 免疫印迹和免疫组织化学研究表明， 氟烷在易感豚鼠肝脏中的代谢导致 在形成更高水平的TFA-蛋白质加合物方面， 那些有抵抗力的动物。大鼠肝脏中的TFA加合物水平为 大约一个数量级低于那些 敏感的豚鼠，这可能解释了为什么老鼠对 氟烷的肝毒性作用当TFA加合物 从血清中免疫纯化，发现一个敏感的 豚鼠血清中TFA-蛋白加合物水平高得多 比那些有抵抗力的动物更强这些加合物很可能是 从受损的肝细胞，因为存在的相关性， ALT和血清TFA加合物水平。令人惊讶的是，P4502 A水平， 而不是其他P450，与大量的 在两只豚鼠的肝脏中检测到TFA-蛋白加合物。 此外，当P4502 A6，豚鼠的人类直向同源物， p4502 A在HepG 2细胞中过表达， 代谢氟烷以形成TFA-抗原， 过表达P4502 E1。这些研究的结果强烈地表明， 表明TFA-加合物的水平是一个重要因素， 确定氟烷是否导致豚鼠肝损伤 并且可能存在于人类中，并且P4502 E1和P4502 A6都可能存在 在人类TFA-蛋白质加合物形成中具有重要作用。 发现相对高水平的完整TFA-蛋白加合物 在敏感豚鼠血清中，表明这些加合物 已经从受损的肝细胞中释放出来， 它们可能能够在远离的组织中诱导免疫反应， 从肝脏。

This year we have continued our studies on the mechanism of inhalation-induced hepatitis. Our goal has been to determine the molecular basis of the hepatotoxicity produced by halothane in the guinea pig model and to define the route by which the immune system comes into contact with the trifluoroacetylated (TFA)-antigens associated with this toxicity. Male outbred Hartley guinea pigs were administered halothane, and livers and blood were collected after 8 and 48 hours. Based on serum ALT levels and livers histology, treated animals could be designated as being either susceptible or nonsusceptible to halothane-induced liver injury. Immunoblot and immunohistochemistry studies indicated that the metabolism of halothane in livers of susceptible guinea pigs resulted in the formation of much higher levels of TFA-protein adducts than those of resistant animals. The level of TFA adducts in rat liver was approximately an order of magnitude lower than those of the susceptible guinea pigs which may explain why rats are resistant to the hepatotoxic effects of halothane. When TFA adducts were immunopurified from the sera, it was found that a susceptible guinea pig had much higher serum levels of TFA-protein adducts than those of a resistant animal. These adducts were likely derived from damaged hepatocytes because a correlation existed between ALT and serum TFA-adducts levels. Surprisingly, P4502A levels, but not those of other P450s, correlated with the high amounts of TFA-protein adducts detected in the livers of two guinea pigs. Moreover, when P4502A6, the human orthologue of guinea pig P4502A, was over-expressed in HepG2 cells, it was able to metabolize halothane to form TFA-antigens as were cells containing over-expressed P4502E1. The results of these studies strongly indicate that the level of TFA-adducts is an important factor in determining whether halothane causes liver damage in guinea pigs and possibly in humans, and that both P4502E1 and P4502A6 likely have an important role in TFA-protein adduct formation in humans. The finding of relatively high levels of intact TFA-protein adducts in the serum of susceptible guinea pigs, indicates that these adducts have been released from damaged hepatocytes and suggests that they may be able to induce immune reactions in tissues far removed from the liver.