Reilly T P, Lash L H, Doll M A, Hein D W, Woster P M, Svensson C K
Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, Wayne State University, Detroit, MI 48202, USA.
J Invest Dermatol. 2000 Jun;114(6):1164-73. doi: 10.1046/j.1523-1747.2000.00985.x.
Cutaneous reactions are the most common manifestation of delayed-type hypersensitivity caused by sulfamethoxazole and dapsone. In light of the recognized metabolic and immunologic activity of the skin, we investigated the potential role of normal human epidermal keratinocytes in the development of these reactions. Adult and neonatal normal human epidermal keratinocytes metabolized sulfamethoxazole and dapsone to N-4-hydroxylamine and N-acetyl derivatives in a time-dependent manner. The latter was catalyzed by N-acetyltransferase 1 alone as normal human epidermal keratinocytes did not express mRNA for N-acetyltransferase 2. Investigation of metabolism-dependent toxicity of sulfamethoxazole and dapsone, and subsequent incubation of normal human epidermal keratinocytes with the respective hydroxylamine metabolites, demonstrated that these cells were resistant to the cytotoxic effects of sulfamethoxazole hydroxylamine but not dapsone hydroxylamine. With prior depletion of glutathione, however, normal human epidermal keratinocytes became susceptible to the toxicity of sulfamethoxazole hydroxylamine. Covalent adduct formation by sulfamethoxazole hydroxylamine was detected in normal human epidermal keratinocytes, even in the absence of cell death, and was increased with glutathione depletion. Major protein targets of sulfamethoxazole hydroxylamine were observed in the region of 160, 125, 95, and 57 kDa. Dapsone hydroxylamine also caused covalent adduct formation in normal human epidermal keratinocytes. Together, these observations provide a basis for our hypothesis that normal human epidermal keratinocytes are involved in the initiation and propagation of a cutaneous hypersensitivity response to these drugs.
皮肤反应是由磺胺甲恶唑和氨苯砜引起的迟发型超敏反应最常见的表现形式。鉴于皮肤已被公认的代谢和免疫活性，我们研究了正常人表皮角质形成细胞在这些反应发生过程中的潜在作用。成人和新生儿的正常人表皮角质形成细胞能将磺胺甲恶唑和氨苯砜代谢为N - 4 - 羟胺和N - 乙酰衍生物，且呈时间依赖性。由于正常人表皮角质形成细胞不表达N - 乙酰转移酶2的mRNA，所以后者仅由N - 乙酰转移酶1催化。对磺胺甲恶唑和氨苯砜的代谢依赖性毒性进行研究，并随后将正常人表皮角质形成细胞与各自的羟胺代谢产物一起孵育，结果表明这些细胞对磺胺甲恶唑羟胺的细胞毒性作用具有抗性，但对氨苯砜羟胺不具有抗性。然而，在预先耗尽谷胱甘肽后，正常人表皮角质形成细胞对磺胺甲恶唑羟胺的毒性变得敏感。即使在没有细胞死亡的情况下，也能在正常人表皮角质形成细胞中检测到磺胺甲恶唑羟胺形成的共价加合物，并且随着谷胱甘肽的耗尽而增加。在160、125、95和57 kDa区域观察到磺胺甲恶唑羟胺的主要蛋白质靶点。氨苯砜羟胺也会在正常人表皮角质形成细胞中引起共价加合物的形成。总之，这些观察结果为我们的假设提供了依据，即正常人表皮角质形成细胞参与了对这些药物的皮肤超敏反应的起始和传播。
