Novel Insights into the Kallikrein–Kinin System in Fulminant Myocarditis: Physiological Basis and Potential Therapeutic Advances

Fulminant myocarditis (FM) is characterized by rapid cardiac deterioration often instigated by an inflammatory cytokine storm. The kallikrein-kinin system (KKS) is a metabolic cascade known for releasing vasoactive kinins, such as bradykinin-related peptides, possessing diverse pharmacological activities that include inflammation, regulation of vascular permeability, endothelial barrier dysfunction, and blood pressure modulation. The type 1 and type 2 bradykinin receptors (B1R and B2R), integral components of the KKS system, mediate the primary biological effects of kinin peptides. This review aims to offer a comprehensive overview of the primary mechanisms of the KKS in FM, including an examination of the structural components, regulatory activation, and downstream signaling pathways of the KKS. Furthermore, it explores the involvement of the tissue kallikrein/B1R/inducible nitric oxide synthase (TK/B1R/iNOS) pathway in myocyte dysfunction, modulation of the immune response, and preservation of endothelial barrier integrity. The potential therapeutic advances targeting the inhibition of the KKS in managing FM will be discussed, providing valuable insights for the development of clinical treatment strategies.