The knowns and unknowns of cardiac autoimmunity in viral myocarditis

Myocarditis can result from various infectious and non-infectious causes that can lead to dilated cardiomyopathy (DCM) and heart failure. Among the infectious causes, viruses are commonly suspected. But the challenge is our inability to demonstrate infectious viral particles during clinical presentations, partly because by that point, the viruses would have damaged the tissues and be cleared by the immune system. Therefore, viral signatures such as viral nucleic acids and virus-reactive antibodies may be the only readouts pointing to viruses as potential primary triggers of DCM. Thus, it becomes hard to explain persistent inflammatory infiltrates that might occur in individuals affected with chronic myocarditis/DCM manifesting myocardial dysfunctions. In these circumstances, autoimmunity is suspected, and antibodies to various autoantigens have been demonstrated, suggesting that immune therapies to suppress the autoimmune responses may be necessary. From this perspective, we endeavoured to determine whether or not the known viral causes are associated with development of autoimmune responses to cardiac antigens that include both cardiotropic and non-cardiotropic viruses. If so, what their nature and significance are in developing chronic myocarditis resulting from viruses as primary triggers.

Automated summary

Myocarditis can be caused by infectious and non-infectious factors, leading to dilated cardiomyopathy and heart failure. Viruses are often suspected as the infectious causes, but it is challenging to detect viral particles during clinical presentations. Viral nucleic acids and virus-reactive antibodies may provide clues to the potential viral triggers of myocarditis. Persistent inflammatory infiltrates and autoantibodies to cardiac antigens suggest the involvement of autoimmunity in chronic myocarditis, requiring immune therapies to suppress autoimmune responses.