Rheumatic fever and rheumatic heart disease: cellular mechanisms leading autoimmune reactivity and disease.
BACKGROUND
Rheumatic fever (RF) is an autoimmune disease caused by the gram-positive bacteria Streptococcus pyogenes that follows a nontreated throat infection in susceptible children. The disease manifests as polyarthritis, carditis, chorea, erythema marginatum, and/or subcutaneous nodules. Carditis, the most serious complication, occurs in 30% to 45% of RF patients and leads to chronic rheumatic heart disease (RHD), which is characterized by progressive and permanent valvular lesions. In this review, we will focus on the genes that confer susceptibility for developing the disease, as well as the innate and adaptive immune responses against S. pyogenes during the acute rheumatic fever episode that leads to RHD autoimmune reactions.


CONCLUSIONS
The disease is genetically determined, and some human leukocyte antigen class II alleles are involved with susceptibility. Other single nucleotide polymorphisms for TNF-alpha and mannan-binding lectin genes were reported as associated with RF/RHD. T cells play an important role in RHD heart lesions. Several autoantigens were already identified, including cardiac myosin epitopes, vimentin, and other intracellular proteins. In the heart tissue, antigen-driven oligoclonal T cell expansions were probably the effectors of the rheumatic heart lesions. These cells are CD4(+) and produced inflammatory cytokines (TNFalpha and IFNgamma).


CONCLUSIONS
Molecular mimicry is the mechanism that mediated the cross-reactions between streptococcal antigens and human proteins. The elucidation of chemokines and their receptors involved with the recruitment of Th1, Th2, and Th17 cells, as well as the function of T regulatory cells in situ will certainly contribute to the delineation of the real picture of the heart lesion process that leads to RHD.
Guilherme
Luiza
L
Heart Institute (InCor), School of Medicine, University of São Paulo, São Paulo, Brazil. luizagui@usp.br
Kalil
Jorge
J
D000942:Antigens, Bacterial / Q000276:immunology*; D001323:Autoantibodies / Q000378:metabolism; D001324:Autoantigens / Q000235:genetics / Q000276:immunology; D015551:Autoimmunity; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D024722:Cardiac Myosins / Q000276:immunology*; D002352:Carrier Proteins / Q000276:immunology*; D020022:Genetic Predisposition to Disease; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006801:Humans; D007797:Laminin / Q000276:immunology; D018716:Molecular Mimicry; D011110:Polymorphism, Genetic; D012214:Rheumatic Heart Disease / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D000942:Antigens, Bacterial; D001323:Autoantibodies; D001324:Autoantigens; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D000949:Histocompatibility Antigens Class II; D007797:Laminin; D014409:Tumor Necrosis Factor-alpha; C014689:streptococcal M protein; D024722:Cardiac Myosins