Complement and cutaneous autoimmune blistering diseases

Cutaneous autoimmune blistering diseases are associated with tissue injury and fluid accumulation within the skin. The initial trigger for the organ-specific damage is autoantibodies targeting skin autoantigens, which are involved in cell-cell or cell-matrix adhesion in the skin. Pemphigus autoantibodies bind to desmosomal antigens and cause intraepidermal blisters, while pemphigoid autoantibodies interact with hemidesmosomal or hemidesmosome-associated antigens and lead to dermal-epidermal junction separation. Local complement activation is a common feature for these skin blistering diseases and some complement components are readily detected in the lesional skin and blister fluids. This review summarizes the current knowledge on the role the complement system in skin blister formation. Characterization of the pathogenically relevant complement cascade and relative contribution of different pathways into complement activation provides new insights of disease pathology and may help develop better therapeutic strategies for these potentially fatal cutaneous blistering disorders.