TNF and viral myocarditis: Studies have shown that mast cells are the primary source of TNF release in the myocardium, with cardiac mast cells secreting elevated levels of pro-inflammatory cytokines such as TNF, IL-1β, and IL-10 during CVB3 infection.186–188 The accumulation of mast cells has been linked to an increase in CCL2-mediated Ly6Chigh macrophages infiltrating the heart, exacerbating cardiac dysfunction and fibrosis in cases of viral myocarditis.186 The early stem cell factor derived from resident cardiac fibroblasts stimulates mast cell accumulation and the secretion of pro-inflammatory cytokines.