Ware J A, Graf M L, Martin B M, Lustberg L R, Pohl L R
Molecular and Cellular Toxicology Section, Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland 20892, USA.
Chem Res Toxicol. 1998 Mar;11(3):164-71. doi: 10.1021/tx970182j.
Idiosyncratic adverse drug reactions are unpredictable, target multiple organ systems, and often become life-threatening events. Although the causes of idiosyncratic adverse drug reactions are not known in most cases, evidence suggests that they may be mediated through immunological mechanisms. It is generally thought that for a drug to lead to an immune response, it must first become covalently bound to a carrier protein. Since most drugs are unreactive, it is usually a reactive metabolite that is expected to form covalent adducts. However, it is not clear why more people do not develop immune reactions against drug-protein adducts. One possible explanation is that orally administered drugs may lead to oral tolerance in most individuals through mechanisms similar to that found with orally administered antigens. However, very little is known regarding the interaction of drugs with gut-associated lymphoid tissue of the small intestine, where oral tolerance can develop. As an initial step to test this hypothesis, we have investigated whether diclofenac, a commonly used nonsteroidal antiinflammatory drug, can lead to protein adducts in rat small intestine. Diclofenac was administered to rats by gastric gavage. Immunoblot analysis of small intestine homogenates and isolated enterocyte subcellular fractions with drug-specific antiserum revealed 142-, 130-, 110-, and 55-kDa protein adducts of diclofenac. The 142- and 130-kDa adducts of diclofenac were identified as aminopeptidase N (CD13) and sucrase-isomaltase, respectively, by amino acid sequence analyses and by their reactions with protein-specific antibodies. The adducts were localized by immunohistochemistry and found primarily in the mid-villus and villus-tip enterocytes and also in the dome overlying Peyer's patches. Similar adducts were detected immunochemically in villus-tip enterocytes of animals treated with halothane or acetaminophen. These results show that intestinal protein adducts of drugs can be formed in gut-associated lymphoid tissue where they may lead to the down-regulation of drug-induced allergic reactions in many individuals.
特异质性药物不良反应不可预测，可累及多个器官系统，且常演变为危及生命的事件。尽管大多数情况下特异质性药物不良反应的病因尚不清楚，但有证据表明其可能通过免疫机制介导。一般认为，药物要引发免疫反应，必须首先与载体蛋白共价结合。由于大多数药物无反应性，通常预期是反应性代谢物形成共价加合物。然而，尚不清楚为何更多人不会对药物 - 蛋白加合物产生免疫反应。一种可能的解释是，口服药物可能通过与口服抗原类似的机制，在大多数个体中导致口服耐受。然而，对于药物与小肠中与肠道相关的淋巴组织（口服耐受可在此处形成）的相互作用知之甚少。作为检验该假设的第一步，我们研究了常用的非甾体抗炎药双氯芬酸是否能在大鼠小肠中形成蛋白加合物。通过胃管饲法给大鼠施用双氯芬酸。用药物特异性抗血清对小肠匀浆和分离的肠细胞亚细胞组分进行免疫印迹分析，结果显示双氯芬酸有142 kDa、130 kDa、110 kDa和55 kDa的蛋白加合物。通过氨基酸序列分析以及它们与蛋白特异性抗体的反应，双氯芬酸的142 kDa和130 kDa加合物分别被鉴定为氨肽酶N（CD13）和蔗糖酶 - 异麦芽糖酶。通过免疫组织化学对加合物进行定位，发现其主要位于绒毛中部和绒毛顶端的肠细胞中，也位于派尔集合淋巴结上方的穹窿区。在用氟烷或对乙酰氨基酚处理的动物的绒毛顶端肠细胞中，通过免疫化学检测到了类似的加合物。这些结果表明，药物的肠道蛋白加合物可在与肠道相关的淋巴组织中形成，在许多个体中，它们可能导致药物诱导的过敏反应下调。
