Molecular Medicine Program, Taiwan International Graduate Program, Taipei, Taiwan.
J Allergy Clin Immunol. 2012 Jun;129(6):1562-9.e5. doi: 10.1016/j.jaci.2011.12.990. Epub 2012 Feb 8.
Increasing studies have revealed that HLA alleles are the major genetic determinants of drug hypersensitivity; however, the underlying molecular mechanism remains unclear.
We adopted the HLA-B∗1502 genetic predisposition to carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) as a model to study the pathologic role of HLA in delayed-type drug hypersensitivity.
We in vitro expanded CBZ-specific cytotoxic T lymphocytes (CTLs) from patients with CBZ-induced SJS/TEN and analyzed the interaction between HLA-B and CBZ analogs based on CTL response, surface plasmon resonance, peptide-binding assay, site-directed mutagenesis, and computer modeling.
The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing. The HLA-B∗1502/peptide/β(2)-microglobulin protein complex showed binding affinity toward chemicals sharing 5-carboxamide on the tricyclic ring, as with CBZ. However, modifications of the ring structure of CBZ altered HLA-B∗1502 binding and CTL response. In addition to HLA-B∗1502, other HLA-B75 family members could also present CBZ to activate CTLs, whereas members of the HLA-B62 and HLA-B72 families could not. Three residues (Asn63, Ile95, and Leu156) in the peptide-binding groove of HLA-B∗1502 were involved in CBZ presentation and CTL activation. In particular, Asn63 shared by members of the B75 family was the key residue. Computer simulations revealed a preferred molecular conformation of the 5-carboxamide group of CBZ and the side chain of Arg62 on the B pocket of HLA-B∗1502.
This study demonstrates a direct interaction of HLA with drugs, provides a detailed molecular mechanism of HLA-associated drug hypersensitivity, and has clinical correlations for CBZ-related drug-induced SJS/TEN.
越来越多的研究表明，人类白细胞抗原（HLA）等位基因是药物过敏的主要遗传决定因素；然而，其潜在的分子机制尚不清楚。
我们采用 HLA-B∗1502 对卡马西平（CBZ）诱导的史蒂文斯-约翰逊综合征（SJS）/中毒性表皮坏死松解症（TEN）的遗传易感性作为模型，研究 HLA 在迟发型药物过敏中的病理作用。
我们从 CBZ 诱导的 SJS/TEN 患者中体外扩增 CBZ 特异性细胞毒性 T 淋巴细胞（CTL），并根据 CTL 反应、表面等离子体共振、肽结合试验、定点突变和计算机建模分析 HLA-B 与 CBZ 类似物之间的相互作用。
负载内源性肽的 HLA-B∗1502 分子将 CBZ 呈现给 CTL，而不涉及细胞内药物代谢或抗原加工。HLA-B∗1502/肽/β（2）-微球蛋白蛋白复合物对三环环上带有 5-羧酰胺的化学物质具有结合亲和力，与 CBZ 相似。然而，CBZ 环结构的修饰改变了 HLA-B∗1502 的结合和 CTL 反应。除 HLA-B∗1502 外，其他 HLA-B75 家族成员也可以将 CBZ 呈现给激活 CTL，而 HLA-B62 和 HLA-B72 家族成员则不能。HLA-B∗1502 肽结合槽中的 3 个残基（Asn63、Ile95 和 Leu156）参与 CBZ 呈递和 CTL 激活。特别是，B75 家族成员共享的 Asn63 是关键残基。计算机模拟显示了 CBZ 的 5-羧酰胺基团和 HLA-B∗1502 B 口袋中 Arg62 侧链的优先分子构象。
本研究证明了 HLA 与药物的直接相互作用，提供了 HLA 相关药物过敏的详细分子机制，并与 CBZ 相关药物引起的 SJS/TEN 具有临床相关性。
