Is peripartum cardiomyopathy an organ-specific autoimmune disease?

Peripartum cardiomyopathy (PPCM) is a rare and serious heart disease that exclusively afflicts women during childbearing years. Symptoms include rapid onset of cardiovascular insufficiency occurring during pregnancy, initiated anytime between the third trimester until 5 months post-partum in the absence of any other signs or history of heart disease. The rare incidence of PPCM and the absence of any relevant animal models have limited research and understanding of the pathogenic mechanisms involved. Several compelling sets of data support the view that PPCM is a form of autoimmune IDCM. However, PPCM differs from autoimmune IDCM in that (a) it is associated with unique sets of autoantibodies and autoantigens, (b) it has a relatively rapid onset, and (c) it exclusively affects pregnant women. Furthermore, the etiology of PPCM is dependent on the interaction of pregnancy associated factors, e.g. increased hemodynamic stress, vasoactive hormones and fetal microchimerism, that co-operate in the context of essential immune and genetic environments for disease progression. Our model of PPCM attempts to represent how multiple factors, e.g. pregnancy, genetics, immune dysregulation, and fetal microchimerism are held in a complex dynamic balance that can co-operate towards the maintenance of cardiovascular health or disease in the mother (Fig. 1). A more thorough study of the precise nature of the cardiac tissue autoantigens may lead to the identification of the mechanisms of breakdown of self-tolerance and perhaps also the putative etiologic agent(s). Further studies of the precise nature of the cardiac tissue autoantigens and the specific factors governing the balance between tolerance and autoimmunity in the periphery, e.g. expression of PD-L1 on cardiac tissues and the role of regulatory T cells, may help to elucidate the autoimmune mechanisms of PPCM. Fig. 1. Dynamic balance between the immune environment, pregnancy associated factors, e.g. vasoactive hormone levels and hemodynamic stress, genetics, and fetal microchimerism in the development of PPCM.