Inflammatory Responses Potentiate GAS M Protein Induced Cardiac Damage in an Experimental Model of Rheumatic Heart...

Area of Science:

• Immunology
• Cardiovascular Medicine
• Rheumatology

Background:

• Acute rheumatic fever (ARF) and Rheumatic Heart Disease (RHD) are autoimmune conditions following group A streptococcal infection.
• The autoimmune pathology involves genetic, inflammatory, and immune cell factors, but the role of inflammation in animal models remained unproven.
• Understanding these factors is critical for developing targeted therapies.

Purpose of the Study:

• To investigate the role of inflammatory responses in the development of cardiac damage in ARF/RHD.
• To demonstrate the requirement of inflammation in a validated animal model of RHD.

Main Methods:

• Utilized the Rat Autoimmune Valvulitis model of RHD.
• Administered group A streptococcal (GAS) M protein with Bordetella pertussis toxin (BPTx) as an adjuvant to enhance inflammatory responses.
• Assessed valvulitis, inflammatory cytokine levels, cardiac function (ECG), antibody production, and immune cell infiltration.

Main Results:

• Enhanced valvulitis and cardiac inflammation were observed in rats treated with GAS M protein and BPTx.
• Elevated circulating inflammatory cytokines and increased infiltration of IFN-γ+ and IL-17A+ leukocytes into cardiac tissues were detected.
• Prolonged P-R interval on ECG indicated functional cardiac impairment and increased cross-reactive antibodies against cardiac proteins were found.

Conclusions:

• Inflammatory responses are essential for promoting cardiac damage in ARF/RHD.
• BPTx accelerates autoimmune processes and cardiac damage in conjunction with GAS M protein exposure.
• Robust inflammation in susceptible individuals significantly facilitates ARF/RHD progression.