Launching new biomarkers for pemphigoid disorders
A group of severe and chronic autoimmune bullous skin disorders, affecting usually the elderly, is the pemphigoids (PEs). They are clinically characterized as burn-like lesions (blisters). Their incidence has been associated with defects in epithelial cells lining skin and mucous membranes and with autoimmune disorders. PEMPHIGOIDS & IMMUNITY consortium performed a systematic analysis on PEs employing state-of-the-art approaches to develop improved and novel diagnostics. Research efforts focused on antigens indicated by pemphigoid patient autoantibodies. Recombinant protein constructs (expressed in baculovirus) were prepared comprising critical subdomains of both BP180 (collagen XVII, transmembrane protein) and cytoplasmic BP230 antigens. The new constructs were validated with clinical tests involving large cohorts of patients' sera and nine novel diagnostic enzyme-linked immunosorbent assays (ELISA) were developed. The results revealed that BP180- and BP230-based methods have the potential to be further exploited as diagnostic markers for disease activity and course. Assays linked to BP180 antigenic domains were more efficient. To improve the currently marketed ELISA (based on a NC16A subdomain of BP180), prokaryotic recombinant constructs were prepared. Researchers successfully detected intramolecular epitope spreading events during the disease course, improving the performance of the existing assay. Six novel ELISAs were developed based on epitopes identified by screening of a BP180 random epitope lambda library against bullous pemphigoid patients' sera. Clinical tests were also performed in pemphigoid patients sera using ELISA based on laminin 5, an epithelial adhesion ligand. The ligand was purified from the conditioned medium squamous carcinoma cell line. The new assay detected anti-laminin 5 reactivity in some bullous and most mucous membrane pemphigoid sera examined. A correlation with clinical severity of the latter was established. The aforementioned novel diagnostic assays will shed light on PEs pathophysiology improving patients' management. With the distinctive features of high sensitivity and specificity, the new assays have great potential for commercial exploitation.
