Development of antigen-specific ELISA for circulating autoantibodies to extracellular matrix protein 1 in lichen sclerosus
Noritaka Oyama, … , Martin M. Black, John A. McGrath
Noritaka Oyama, … , Martin M. Black, John A. McGrath
Published June 1, 2004
Citation Information: J Clin Invest. 2004;113(11):1550-1559. https://doi.org/10.1172/JCI20373.
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Article Dermatology

Development of antigen-specific ELISA for circulating autoantibodies to extracellular matrix protein 1 in lichen sclerosus

Abstract

Lichen sclerosus is a common, acquired chronic inflammatory skin disease of unknown etiology, although circulating autoantibodies to the glycoprotein extracellular matrix protein 1 (ECM1) have been detected in most patients’ sera. We have examined the nature of ECM1 epitopes in lichen sclerosus sera, developed an ELISA system for serologic diagnosis, and assessed clinicopathological correlation between ELISA titer and disease. Epitope-mapping studies revealed that lichen sclerosus sera most frequently recognized the distal second tandem repeat domain and carboxyl-terminus of ECM1. We analyzed serum autoantibody reactivity against this immunodominant epitope in 413 individuals (95 subjects with lichen sclerosus, 161 normal control subjects, and 157 subjects with other autoimmune basement membrane or sclerosing diseases). The ELISA assay was highly sensitive; 76 of 95 lichen sclerosus patients (80.0%) exhibited IgG reactivity. It was also highly specific (93.7%) in discriminating between lichen sclerosus and other disease/control sera. Higher anti-ECM1 titers also correlated with more longstanding and refractory disease and cases complicated by squamous cell carcinoma. Furthermore, passive transfer of affinity-purified patient IgG reproduced some histologic and immunopathologic features of lichen sclerosus skin. This new ELISA is valuable for the accurate detection and quantification of anti-ECM1 autoantibodies. Moreover, the values may have clinical significance in patients with lichen sclerosus.

Authors

Noritaka Oyama, Ien Chan, Sallie M. Neill, Andrew P. South, Fenella Wojnarowska, Yoshio Kawakami, David D’Cruz, Kirti Mepani, Graham J. Hughes, Balbir S. Bhogal, Fumio Kaneko, Martin M. Black, John A. McGrath

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Figure 1

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Schematic representation of ECM1 protein and its five recombinant GST fu...
Schematic representation of ECM1 protein and its five recombinant GST fusion fragments. The distinct molecular domains comprise a signal peptide, a cysteine-free NH2-terminal domain, two tandem repeat domains, and a COOH-terminal domain. The position of the single cysteine residues and potential N-glycosylation sites are indicated. The full-length 1.8-kb ECM1 cDNA was initially divided into three different fragments, ΔNH2 (33 to 226 amino acids), ΔPx/COOH (226 to 499 amino acids), and ΔS/COOH (499 to 559 amino acids), designed to span almost the entire ECM1. Two further fragments were then synthesized. The ΔS/ex7 fragment encodes part of the ΔPx/COOH domain (226 to 359 amino acids), and the ΔDs/COOH fragment encodes the distal part of the second tandem repeat domain and COOH-terminus (359 to 559 amino acids). All fragments were fused with GST-encoded cDNA at the NH2-terminus of the recombinant proteins. The amino acid residue numbers are shown as described elsewhere (13). The predicted molecular weights (kDa) of each recombinant fusion fragment are shown on the right.