Plasmin Plays a Role in the In Vitro Generation of the Linear IgA Dermatosis Antigen LADB97

Silke C. Hofmann, Ursula Voith, Verena Schönau, Lydia Sorokin, Leena Bruckner-Tuderman, Claus-Werner Franzke
2009 Journal of Investigative Dermatology  
Collagen XVII (BP180) and its shed ectodomain represent major autoantigens in dermatoses of the pemphigoid group. The 120 kDa ectodomain is constitutively shed from the cell surface by disintegrin-metalloproteinases (ADAMs). Part of it is further processed to a 97 kDa fragment (LABD97), an autoantigen in linear IgA dermatosis (LAD), but the responsible proteinases remain elusive. In this study, we identified the 120 and the 97 kDa ectodomain in blister fluids of bullous pemphigoid patients
more » ... igoid patients using new mAbs. As blister fluids contain significant plasmin-like serine protease activity, HaCaT keratinocytes or purified 120 kDa ectodomain were incubated with several human serine proteases. In vitro, only plasmin generated a stable 97 kDa fragment that was also targeted by LAD sera. Characterization of the plasmin-derived 97 kDa fragment with domain-specific collagen XVII antibodies, heparin binding and N-glycosylation studies indicates that the N-terminus is located approximately at AA 515 and the C-terminus N-terminally from AA 1,421. Interestingly, plasmin-derived LABD97 was also generated in the presence of ADAM inhibitors and remained stable over more than 12 hours incubation at 37 1C, indicating that this disease relevant collagen XVII fragment can also arise in an ADAMindependent manner through direct action by plasmin. Abbreviations: AAs, amino acids; ADAM, a disintegrin and metalloproteinase; BP, bullous pemphigoid; LABD97, 97 kDa autoantigen of linear IgA
doi:10.1038/jid.2008.424 pmid:19158842 fatcat:25xbm4ifpbbf3ii6ur2ba2rqf4