The molecular logic of pemphigus and impetigo: the desmoglein story.

Desmosomes are intercellular adhesive junctions of epithelial cells that contain two major transmembrane components, desmogleins (Dsg) and desmocollins; these are both cadherin-type cell-cell adhesion molecules. Pemphigus is an autoimmune blistering disease caused by IgG autoantibodies that target Dsg1 and Dsg3 in pemphigus foliaceus and pemphigus vulgaris respectively. Bullous impetigo is a common and highly contagious superficial skin infection caused by Staphylococcus aureus. Staphylococcal scalded skin syndrome (SSSS) is a generalized form of bullous impetigo. The blisters in bullous impetigo and SSSS are induced by exfoliative toxin that specifically cleaves Dsg1. Clinical and microscopic localization of blisters in pemphigus, bullous impetigo and SSSS are logically explained at the molecular level by the desmoglein compensation theory; the similarity of lesions among these diseases is underscored by a similar pathogenesis.