BP180/type XVII collagen: its role in acquired and inherited disorders or the dermal-epidermal junction

BP180 is a member of the collagen protein family and is also referred to as type XVII collagen or BP antigen 2. It is a transmembrane protein constituent of the dermal-epidermal anchoring complex. The long-held hypothesis that BP180 functions as a cell-matrix adhesion molecule has been supported by recent investigations of human disorders of the dermal-epidermal junction in which BP180 is either genetically defective or targeted by the immune system. In generalized atrophic benign epidermolysis bullosa, mutations of BP180 result in an inherited subepidermal blistering disease. In bullous pemphigoid, herpes/pemphigoid gestationis, cicatricial pemphigoid, lichen planus pemphigoides and linear IgA disease, autoantibodies are directed to different epitopes on the BP180 ectodomain. Recent molecular investigations have provided new insights, not only into the mechanism of autoantibody-mediated subepidermal blistering, but also into the biochemical structure and cell biological functions of BP180 and other components of the dermal-epidermal anchoring complex. These findings have suggested new directions for the development of diagnostic and therapeutic tools for these autoimmune and genetic diseases.