Cytokine cascade in Kawasaki disease versus Kawasaki-like syndrome.

Kawasaki disease (KD) is a medium vessel systemic vasculitis that predominantly occurs in children below five years of age. It is an acute febrile condition in which coronary artery aneurysms and myocarditis are the most common cardiovascular complications. It is most often characterized by hypercytokinemia. The etiopathogenesis of KD is not fully understood. The present review synthesizes the recent advances in the pathophysiology and treatment options of KD. According to different studies, the genetic, infections and autoimmunity factors play a major role in pathogenesis. Several susceptibility genes (e.g. caspase 3) and cytokines (e.g. IL-2, IL-4, IL-6, IL-10, IFN-gamma and TNF-alpha) have been identified in KD. Patients with high cytokine levels are predisposed to KD shock syndrome. The importance of respiratory viruses in the pathogenesis of the disease is unclear. Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may induce in children and adults an abnormal systemic inflammatory response. This syndrome shares characteristics with KD. It has been called by many terms like MIS-C (Multisystem Inflammatory Syndrome in Children), PIMS-TS (pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2), hyperinflammatory shock syndrome, cytokine storm (cytokine release syndrome) or simply, Kawasaki-like syndrome. The cytokine's role in the development of KD or Kawasaki-like syndrome being triggered by COVID-19 is controversial. The presences of the antiendothelial cell autoantibodies (AECAs) together with the newly developed hypothesis of immunothrombosis are considered potential pathogenic mechanisms for KD. In consequence, the diagnosis and treatment of KD and Kawasaki-like syndrome, one of the most common causes of acquired heart disease in developed countries, are challenging without a clearly defined protocol.