Rheumatic Fever and Rheumatic Heart Disease

Abstract

Rheumatic heart disease is a sequel of rheumatic fever that follows an untreated group A streptococcal infection of young susceptible individuals. The disease is mediated by inflammatory and autoimmune reactions. Several genes related to both innate and adaptive immune responses are involved and HLA class II alleles have also been associated with the disease. Both cellular and humoral immune responses take part in the autoimmune reactions, in which Th1 and Th17 inflammatory cytokines are mediators of the rheumatic heart lesions. Since humans are unique hosts for S. pyogenes infections, several studies have been done to find a suitable animal model in numerous different species including mice, rats, hamsters, rabbits, and primates. The in vitro analysis of heart tissue infiltrating T cells showed their ability to recognize several streptococcal-M protein peptides as well as self antigens by molecular mimicry mechanisms and demonstrated the contribution of CD4+ T cells in the pathogenesis of the disease.