MECHANISMS OF DRUG-INDUCED TOXICITIES

今年，我们继续研究了 吸入性肝炎的发病机制。我们的目标一直是 确定黄曲霉毒素肝毒性的分子基础 氟烷在豚鼠模型中的作用，并确定其途径 免疫系统与三氟乙酰化的 (TFA)-与这种毒性相关的抗原。雄性近交系哈特莱 给豚鼠注射氟烷，肝脏和血液 在8小时和48小时后收集。根据血清ALT水平和 肝脏组织学，处理过的动物可以被指定为 对氟烷引起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 在形成比TFA-蛋白质加合物更高水平的过程中 有抵抗力的动物。TFA加合物在大鼠肝脏中的含量为 大约比 易感的豚鼠，这可能解释了为什么大鼠对 氟烷的肝脏毒性作用。当TFA加合物被 从血清中免疫纯化后，发现一种易感病毒 豚鼠的血清TFA-蛋白加合物水平要高得多 而不是抵抗的动物。这些加合物很可能是从 从受损的肝细胞中分离出来，因为 ALT和血清TFA加合物水平。令人惊讶的是，P4502a水平， 但不是其他P450的那些，与高水平的 在两只豚鼠的肝脏中检测到TFA蛋白加合物。 此外，当P4502A6时，豚鼠的人类同源基因 P4502a，在HepG2细胞中过表达，能够 代谢氟烷以形成TFA抗原，因为细胞含有 过表达P4502E1。这些研究的结果有力地证明了 提示TFA加合物水平是影响TFA加合物水平的重要因素。 氟烷是否对豚鼠造成肝损伤 可能在人类身上，P4502E1和P4502A6都可能 在人类TFA-蛋白质加合物的形成中起着重要作用。 发现较高水平的完整TFA-蛋白质加合物 在易感豚鼠的血清中，表明这些加合物 已经从受损的肝细胞中释放出来，这表明 它们可能能够在远距离移除的组织中诱导免疫反应。 取自肝脏。

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.