Pathogenecity of autoantibody in bullous pemphigoid and development of epitope-decoy therapy

大疱性类天疱疮（BP）是一种自身免疫性皮肤病，其特征是皮肤和粘膜上出现疼痛性糜烂和水疱，并在组织学上表现出独特的表皮下裂开。患者基底膜区存在与180 kD BP抗原反应的IgG自身抗体。由于人与受体之间的表位差异，先前将IgG从BP患者被动转移到动物中的实验未能再现疾病。为了克服自身抗体和自身抗原之间的物种差异，我们开发了新的方法。我们首先产生了敲除小鼠的BP180基因，这揭示了水泡形成中发现的人类直系同源基因敲除，非Herliz交界性大疱性表皮细胞（EB）。接着，进行使用人BP180 cDNA转基因的转基因拯救实验，其导致敲除小鼠的异常表型的校正。BP180基因敲除小鼠的成功转基因拯救也为EB的基因治疗提供了巨大的希望。当被动转移来自BP患者的IgG时，这些具有人源化BP180的获救小鼠成功形成水疱。此外，用70聚体重组抗原肽处理显著防止水疱形成。本研究首次证明了BP抗体致病性的直接证据和表位诱饵治疗BP的可行性，也显示了EB矫正基因治疗的有效性。

Bullous pemphigoid (BP) is an autoimmune skin disease characterized by painful erosions and blisters arising on the skin and mucous membrane, and demonstrates distinctive subepidermal clefting histologically. The patients have lgG autoantibody that reacts 180-kD BP antigens in basement membrane zone. Previous passive transfer experiments with lgG from BP patients into animals fails reproducing disease due to the epitope differences between human and recipients. To overcome the species difference between autoantibody and autoantigen, we developed novel approach. We first generated knockout mouse of the BP180 gene, which revealed blister formation as found in human ortholog knockout, non-Herliz junctional epidermolysis bullosa (EB). Next, transgenic rescue experiment using human BP180 cDNA transgene was performed, which resulted in correction of abnormal phenotypes of the knockout mice. Successful transgenic rescue of BP180 KO mice also provides a great promise to gene therapy of EB. These rescued mice with humanized BP180 succeeded in blister formation when lgG from BP patients were passively transferred. Furthermore, treatment with 70 mer recombinant antigenic peptide prevented blister formation significantly. This study first demonstrated direct evidence of BP antibody pathogenicity and feasibility of epitope decoy therapy in BP, and also showed promising effectiveness of corrective gene therapy of EB.