Revisiting QT prolongation in acute rheumatic fever - Relevance for hydroxychloroquine treatment

An acute rheumatic fever immune signature comprising inflammatory markers, IgG3, and Streptococcus pyogenes-specific antibodies

Understanding the immune profile of acute rheumatic fever (ARF), a serious post-infectious sequelae of Streptococcal pyogenes (group A Streptococcus [GAS]), could inform disease pathogenesis and management. Circulating cytokines, immunoglobulins, and complement were analyzed in participants with first-episode ARF, swab-positive GAS pharyngitis and matched healthy controls. A striking elevation of total IgG3 was observed in ARF (90% > clinical reference range for normal). ARF was also associated with an inflammatory triad with significant correlations between interleukin-6, C-reactive protein, and complement C4 absent in controls. Quantification of GAS-specific antibody responses revealed that subclass polarization was remarkably consistent across the disease spectrum; conserved protein antigens polarized to IgG1, while M-protein responses polarized to IgG3 in all groups. However, the magnitude of responses was significantly higher in ARF. Taken together, these findings emphasize the association of exaggerated GAS antibody responses, IgG3, and inflammatory cytokines in ARF and suggest IgG3 testing could beneficially augment clinical diagnosis.

Research priorities for the secondary prevention and management of acute rheumatic fever and rheumatic heart disease: a National Heart, Lung, and Blood Institute workshop report

Secondary prevention of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) involves continuous antimicrobial prophylaxis among affected individuals and is recognised as a cornerstone of public health programmes that address these conditions. However, several important scientific issues around the secondary prevention paradigm remain unresolved. This report details research priorities for secondary prevention that were developed as part of a workshop convened by the US National Heart, Lung, and Blood Institute in November 2021. These span basic, translational, clinical and population science research disciplines and are built on four pillars. First, we need a better understanding of RHD epidemiology to guide programmes, policies, and clinical and public health practice. Second, we need better strategies to find and diagnose people affected by ARF and RHD. Third, we urgently need better tools to manage acute RF and slow the progression of RHD. Fourth, new and existing technologies for these conditions need to be better integrated into healthcare systems. We intend for this document to be a reference point for research organisations and research sponsors interested in contributing to the growing scientific community focused on RHD prevention and control.

Cytokine imbalance in acute rheumatic fever and rheumatic heart disease: Mechanisms and therapeutic implications

Acute Rheumatic Fever (ARF) and Rheumatic Heart Disease (RHD) are autoimmune sequelae of Group A Streptococcus infection with significant global disease burden. The pathogenesis of these diseases is poorly understood, and no immune modulating therapies are available to stop progression from ARF to RHD. Cytokines and chemokines are immune signaling molecules critical to the development of autoimmune diseases. An increasing number of studies point to a central role for pro-inflammatory cytokines and chemokines in ARF and RHD pathogenesis, in particular IL-6, IL-8/CXCL8, and TNFα, which are elevated in circulation in both ARF and RHD patients. Histological studies of RHD valve tissue implicates Th1 and Th17 associated pro-inflammatory cytokines, chemokine CXCL9, and the fibrosis-associated cytokine TGF-β in progressive cycles of inflammatory damage and fibrotic repair. Taken together, this suggests immune molecules contribute to both the acute inflammatory disease stage of ARF, as well as cardiac remodeling and valve dysfunction in RHD. Monoclonal antibody blockade of pro-inflammatory cytokines IL-6 and TNFα are approved therapies for many autoimmune diseases and the most successful immunomodulating therapies for rheumatoid arthritis. Current evidence suggests possible benefit for ARF patients from IL-6 and TNFα blockade, in particular to interrupt progression to RHD, and warrants immediate investigation.