From the Guidelines
The autoimmune response in rheumatic fever is triggered by a streptococcal infection, leading to molecular mimicry where the immune system mistakenly attacks the body's own tissues, particularly in the heart, due to similarities between streptococcal antigens and human proteins 1. This autoimmune response occurs when the body's immune system produces antibodies against streptococcal antigens, which then cross-react with similar-looking proteins in human tissues, especially in the heart, joints, skin, and brain.
- The immune system's inability to distinguish between bacterial components and the body's own tissues is due to structural similarities between streptococcal M proteins and human cardiac myosin, laminin, and other proteins.
- T-cells also play a role in this autoimmune process by infiltrating cardiac tissue and causing damage, leading to inflammation in various organs, with the heart being most significantly affected through carditis. Key aspects of the autoimmune response in rheumatic fever include:
- Molecular mimicry as the primary mechanism
- Involvement of both antibodies and T-cells in the immune response
- The heart as the most significantly affected organ, leading to potential long-term complications like rheumatic heart disease The resulting inflammation can lead to long-term complications like rheumatic heart disease, characterized by valve damage, which can be managed with antibiotics, anti-inflammatory medications, and prophylactic antibiotics to prevent recurrent infections 1.
From the Research
Autoimmune Response in Rheumatic Fever
The autoimmune response in rheumatic fever is triggered by an infection with group A streptococcal bacteria, which activates the innate immune system and elicits autoimmune reactions targeting the heart, joints, brain, skin, and subcutaneous tissue 2.
Mechanisms of Autoimmune Response
- Molecular mimicry is a central hypothesis, where the immune system mistakes the host's own tissues for the streptococcal bacteria, leading to an autoimmune response 3, 4, 5.
- Autoantigens, such as cardiac myosin epitopes, vimentin, and other intracellular proteins, have been identified as targets of the autoimmune response 4.
- Antigen-driven oligoclonal T cell expansions, particularly CD4+ T cells, play a key role in causing rheumatic heart lesions and producing inflammatory cytokines 4.
Consequences of Autoimmune Response
- Repeated episodes of acute rheumatic fever can lead to rheumatic heart disease, characterized by valve regurgitation and/or stenosis, and complications such as arrhythmias, systemic embolism, infective endocarditis, pulmonary hypertension, heart failure, and death 2.
- The autoimmune response can also affect other tissues, including the brain, leading to conditions such as Sydenham chorea and pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections 5.