Kawasaki disease (KD) is a multisystem
vasculitis that predominantly targets the coronary arteries in children. Phenotypic similarities between KD and recurrent
fever syndromes point to the potential role of
inflammasome activation in KD. Mutations in NLRP3 are associated with recurrent
fever/autoinflammatory syndromes. We show that the KD-associated genetic polymorphism in
inositol-
triphosphate 3-kinase C (ITPKC) (rs28493229) has important functional consequences, governing ITPKC
protein levels and thereby intracellular
calcium, which in turn regulates NLRP3 expression and production of IL-1β and
IL-18. Analysis of transcript abundance,
protein levels, and cellular response profiles from matched, serial biospecimens from a cohort of genotyped KD subjects points to the critical role of ITPKC in mediating NLRP3
inflammasome activation. Treatment failure in those with the high-risk ITPKC genotype was associated with the highest basal and stimulated intracellular
calcium levels and with increased cellular production of IL-1β and
IL-18 and higher circulating levels of both
cytokines. Mechanistic studies using Itpkc-deficient mice in a disease model support the genomic, cellular, and clinical findings in affected children. Our findings provide the mechanism behind the observed efficacy of rescue
therapy with
IL-1 blockade in recalcitrant KD, and we identify that regulation of
calcium mobilization is fundamental to the underlying immunobiology in KD.