Heat shock protein 90: a pathophysiological factor and novel treatment target in autoimmune bullous skin diseases.

The chaperone heat shock protein 90 (Hsp90), a cell stress-inducible molecule that regulates activity of many client proteins responsible for cellular growth, differentiation and apoptosis, has been proposed as an important therapeutic target in patients with malignancies. More recently, its active participation in (auto)immune processes has been recognized as evidenced by amelioration of inflammatory disease pathways through pharmacological inhibition of Hsp90 in rodent models of autoimmune encephalomyelitis, rheumatoid arthritis and systemic lupus erythematosus. Based on own current research results, this viewpoint essay provides important insights that Hsp90 is also involved as a notable pathophysiological factor in autoimmune blistering dermatoses including epidermolysis bullosa acquisita, bullous pemphigoid and possibly dermatitis herpetiformis. The observed in vitro, ex vivo and in vivo efficacy of anti-Hsp90 treatment in experimental models of autoimmune bullous diseases and its underlying multimodal anti-inflammatory mechanisms of interference with key contributors to autoimmune-mediated blister formation supports the introduction of selective non-toxic Hsp90 inhibitors into the clinical setting for the treatment of patients with these disorders.

Extracts of wheat gluten activate complement via the alternative pathway.

We studied the ability of wheat gluten and its subfractions to activate complement directly. A sensitive sandwich ELISA employing a monoclonal antibody (MoAb) to a C9 neoepitope exposed in the terminal complement complex (TCC), a functional haemolytic assay for C5b6 generation, and Laurell's electrophoretic method of estimating C3 conversion to C3bi were used. On a weight-for-weight basis, enzyme solubilized Frazer's fraction three of gluten (FIII) produced approximately 75% of the complement activation seen with the potent activator zymosan. By contrast, activation with whole insoluble undigested gluten was very weak and similar to that seen with ovalbumin or beta-lactoglobulin. The results were the same using normal human serum or sera from patients with coeliac disease, dermatitis herpetiformis, or hypogammaglobulinaemia as the complement source. Activation by both zymosan and FIII was blocked in 0.01 M EDTA, but not in 0.01 M EGTA with 0.0025 M magnesium chloride. Zymosan and FIII activated complement in a serum from a patient with an intact alternative pathway but classical pathway haemolytic activity (CH50) of zero. Preferential heat inactivation of the alternative pathway inhibited both zymosan- and FIII-induced activation. Our results confirm that FIII is a strong activator of the alternative pathway. We discuss how gluten enteropathy might be initiated by complement.

An analysis of 24 patients with IgA deposition at the BMZ.

A study of 24 patients with IgA deposition at the BMZ of the skin showed that five conditions could be recognized: 1) linear IgA bullous dermatosis in adults (LAD, 7 cases); 2) linear IgA and IgG bullous dermatosis in adults (LAGD, 10 cases); 3) chronic bullous disease of childhood (CBDC, 3 cases); 4) dermatitis herpetiformis (DH, 1 case), and 5) systemic lupus erythematosus (SLE, 3 cases). Histopathologically, 5 of 7 patients with LAD were similar to the DH group, but 7 of 10 patients with LAGD were similar to the BP group. Half the patients with LAD and LAGD had oral lesions, and most of them had excellent responses to dapsone and Tripterygium Wilfordii, but the patients with CBDC did not respond to these treatments. In the patients with LAD and LAGD, the positivity rates of IgA anti-BMZ antibodies examined by indirect immunofluorescence (IIF) on intact skin and NaCl split skin were 41% and 64%, respectively. The heterogeneity of the histopathologic pictures of LAD and LAGD, the incidence of DH, and the value of using NaCl split skin for IIF are discussed.