Modern aspects of immunopathogenesis of autoimmune myocarditis

Myocarditis (MC) is an inflammation of the cardiac muscle. Viral infections appear to be the most frequent cause for induction of MC. According to the I. Roitt's classification, autoimmune (AI) MC is an organ-specific form of AI pathology. Thus, autoreactive antibodies (auto-Abs) against myocardial antigens and autoreactive T cells are major pathogenic mechanisms, and they are a common cause of cardiac muscle disorder progression. The autoantigens from myocardial tissue (like cardiomyosin and etc.) and/or the phenomena of virus mimicry stimulate auto-Ab production and their cross-reactivity with myocardial antigens. Some auto-Abs in patients with AI diseases demonstrate DNA-hydrolytic or proteolytic abilities against autoantigen. We found both DNA-abzymes and protabzymes in some MC patients. They showed catalytic activity not only against non-specific polypeptide, but also specific activity against cardiomyosine. Proteolytic activities of protabzymes differ depending on the clinical form and activity of MC. This suggests a role of protabzymes in the pathogenesis of AI-MC. According to some authors, auto-Abs (including auto-Abs with catalytic ability) in patients with AI diseases can be additional regulatory factors of apoptosis.