Pemphigoid gestationis: current insights into pathogenesis and treatment

Normal pregnancy is characterized by a natural homeostasis between the mother and the fetus with the development of a tolerance for genetically and immunologically different tissues engrafted in the maternal organism. Upset of the fine mechanisms of the balance of this homeostasis leads to the development of different diseases. Pemphigoid gestationis is a self-limiting, autoimmune subepidermal bullous dermatosis of pregnancy that results from the recognition of placental proteins as foreign and the subsequent production of anti-placental antibodies that cross-react with the same proteins in skin. The main antigen of PG was found to be collagen XVII, present in both skin and placenta, that is exposed to the maternal immune system through an abnormal expression of MHC class II molecules in the placenta. The genetic predisposition determined by a specific HLA genotype combined with the aberrant presentation of collagen XVII triggers an inflammatory response resulting in the typical clinical phenotype. Immunofluorescence shows a linear deposition of C3 with or without concomitant IgG deposition, along the basement membrane zone (BMZ). The disease usually resolves within weeks to months after delivery and tends to recur with subsequent pregnancies. Treatment is challenging in that the disease is extremely rare to allow for controlled studies and most of the treatment options are based on case reports and clinical experience. Oral corticosteroids are the therapeutic mainstay both in pregnancy and postpartum, but several other modalities may be tried in recalcitrant disease. Further research is needed to clarify the exact pathogenic cascade and the interaction of its different components. The elucidation of the target antigens, the targeting antibodies and the mechanism of action of the inflammatory infiltrate may help for the development of new focused therapeutic agents. This review presents an overview of the current understanding of Pemphigoid gestationis and the latest scientific and clinical data in relation to the pathogenesis and treatment modalities.