Appendectomy Mitigates Coxsackievirus B3-Induced Viral Myocarditis

Area of Science:

• Immunology
• Virology
• Gastroenterology

Background:

• The appendix harbors lymphatic cells and microbiota, influencing intestinal flora and IgA induction.
• Appendectomy has been linked to increased risks of cardiovascular diseases.
• The role of the appendix in viral myocarditis remains unclear.

Purpose of the Study:

• To investigate the effect of appendectomy on coxsackievirus B3 (CVB3)-induced viral myocarditis in a mouse model.
• To elucidate the underlying immunological mechanisms by which the appendix influences viral myocarditis.

Main Methods:

• Mice underwent appendectomy or sham operation before intraperitoneal inoculation with CVB3.
• Viral load and pro-inflammatory cytokine levels in the heart and intestine were quantified using RT-PCR.
• Immune cell infiltration (neutrophils, macrophages) and T cell responses (IFN-γ, IL-10) were analyzed.

Main Results:

• Appendectomized mice showed reduced cardiac inflammation, improved cardiac function, and lower systemic viral load compared to controls.
• A decrease in cardiac neutrophil and macrophage infiltration and pro-inflammatory cytokine production was observed in appendectomized mice.
• Appendectomy led to reduced intestinal IL-10 and regulatory T cell (Treg) frequency, enhancing anti-viral T cell responses (IFN-γ) and viral restriction.

Conclusions:

• The appendix modulates the immune response to CVB3 infection, influencing cardiac inflammation and viral myocarditis.
• Appendectomy alters the intestinal immune environment, specifically reducing IL-10 producing Tregs, which enhances anti-viral immunity.
• These findings suggest the appendix plays a critical role in regulating systemic viral infections through its influence on the gut immune system.