TLR4 and myocarditis: Innate immune factors that are critical in driving acute myocardial inflammation and progression to chronic inflammatory cardiomyopathy such as complement, Toll-like receptor (TLR)2 and TLR4, inflammasome components like NLR-family pyrin domain-containing protein 3 (NLRP3) and cytokines including IL-1β, IL-18, IL-6 and transforming growth factor (TGF)β1 are released from mast cells and macrophages (6, 19, 20).