Context-Dependent Regulation of Collagen XVII Ectodomain Shedding in Skin
Context-Dependent Regulation of Collagen XVII Ectodomain Shedding in Skin
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DOI：
10.1016/j.ajpath.2015.01.012
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发表时间：
2015-05-01
影响因子：
6
通讯作者：
Shimizu, Hiroshi
中科院分区：
文献类型：
--
作者：
Nishie, Wataru;Natsuga, Ken;Shimizu, Hiroshi
类天疱疮是一种常见的自身免疫性水疱性疾病，自身抗体靶向基底层角质形成细胞中半桥粒的跨膜型XVII胶原(COL17)。COL17的胞外结构域可以从细胞膜外的NC16A结构域的细胞表面切割出来，有趣的是，类天疱疮患者的某些自身抗体优先与脱落的胞外结构域发生反应。这些发现表明，COL17胞外结构域脱落在脱落形式上产生新的表位；然而，体内皮肤脱落的调节机制和新表位靶向抗体的致病性仍然不确定。为了解决这些问题，我们制造了与脱落的COL17胞外区的N端裂解位点特异反应的兔抗体。抗体表明，在体内皮肤中，一定量的人COL17胞外区在Gln(525)处被生理切割。相反，迁移的人角质形成细胞在Leu(524)处切割COL17，但在Gln(525)处不切割COL17。被动地将与小鼠COL17胞外区N端裂解位点反应的抗体转移到新生野生型小鼠体内，即使抗体结合到真皮-表皮连接处，也未能诱导水泡的形成，这表明裂解位点特异性抗体对水泡形成的致病性降低或消失。这项研究表明，COL17的胞外结构域脱落在活体人类皮肤中是一种生理学事件，可能在切割部位产生非病理性表位。
Pemphigoid is a common autoimmune blistering disorder in which autoantibodies target transmembrane collagen XVII (COL17), a component of hemidesmosomes in basal keratinocytes. The ectodomain of COL17 can be cleaved from the cell surface within the juxtamembranous extracellular NC16A domain, and, interestingly, certain autoantibodies of pemphigoid patients preferentially react with the shed ectodomain. These findings suggest that COL17 ectodomain shedding generates neoepitopes on the shed form; however, the regulatory mechanism of the shedding in in vivo skin and the pathogenicity of the neoepitope-targeting antibodies still are uncertain. To address these issues, we produced rabbit antibodies specifically reacting with N-terminal cleavage sites of the shed COL17 ectodomain. The antibodies showed that certain amounts of the human COL17 ectodomain are cleaved physiologically at Gln(525) in in vivo skin. In contrast, migrating human keratinocytes cleave COL17 at Leu(524) but not at Gln(525). The passive transfer of antibodies reacting with an N-terminal cleavage site of the mouse COL17 ectodomain into neonatal wild-type mice failed to induce blister formation, even though the antibodies bound to the dermal-epidermal junctions, indicating that cleavage site-specific antibodies have reduced or absent pathogenicity for blister formation. This study shows the ectodomain shedding of COL17 to be a physiological event in in vivo human skin that probably generates nonpathologic epitopes on the cleavage sites.