Characterization of Peroxidases Expressed in Human Antigen Presenting Cells and Analysis of the Covalent Binding of Nitroso Sulfamethoxazole to Myeloperoxidase
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- 作者：Monday O. Ogese ; Rosalind E. Jenkins ; James L. Maggs ; Xiaoli Meng ; Paul Whitaker ; Daniel Peckham ; Lee Faulkner ; B. Kevin Park ; Dean J. Naisbitt
- 刊名：Chemical Research in Toxicology
- 出版年：2015
- 出版时间：January 20, 2015
- 年：2015
- 卷：28
- 期：1
- 页码：144-154
- 全文大小：595K
- ISSN：1520-5010
文摘
Drug hypersensitivity remains a major concern, as it causes high morbidity and mortality. Understanding the mechanistic basis of drug hypersensitivity is complicated by the multiple risk factors implicated. This study utilized sulfamethoxazole (SMX) as a model drug to (1) relate SMX metabolism in antigen presenting cells (APCs) to the activation of T-cells and (2) characterize covalent adducts of SMX and myeloperoxidase, which might represent antigenic determinants for T-cells. The SMX metabolite nitroso-SMX (SMX-NO) was found to bind irreversibly to APCs. Time- and concentration-dependent drug鈥損rotein adducts were also detected when APCs were cultured with SMX. Metabolic activation of SMX was significantly reduced by the oxygenase/peroxidase inhibitor methimazole. Similarly, SMX-NO-specific T-cells were activated by APCs pulsed with SMX, and the response was inhibited by pretreatment with methimazole or glutaraldehyde, which blocks antigen processing. Western blotting, real-time polymerase chain reaction (RT-PCR), and mass spectrometry analyses suggested the presence of low concentrations of myeloperoxidase in APCs. RT-PCR revealed mRNA expression for flavin-containing monooxygenases (FMO1鈥?), thyroid peroxidase, and lactoperoxidase, but the corresponding proteins were not detected. Mass spectrometric characterization of SMX-NO-modified myeloperoxidase revealed the formation of N-hydroxysulfinamide adducts on Cys309 and Cys398. These data show that SMX鈥檚 metabolism in APCs generates antigenic determinants for T-cells. Peptides derived from SMX-NO-modified myeloperoxidase may represent one form of functional antigen.