Reduced Platelet miR-223 Induction in Kawasaki Disease Leads to Severe Coronary Artery Pathology Through a miR-223/PDGFRβ Vascular Smooth Muscle Cell Axis

RATIONALE:Kawasaki disease (KD) is an acute vasculitis of early childhood that can result in permanent coronary artery structural damage. The cause for this arterial vulnerability in up to 15% of patients with KD is unknown. Vascular smooth muscle cell dedifferentiation play a key role in the pathophysiology of medial damage and aneurysm formation, recognized arterial pathology in KD. Platelet hyperreactivity is also a hallmark of KD. We recently demonstrated that uptake of platelets and platelet-derived miRNAs influences vascular smooth muscle cell phenotype in vivo. OBJECTIVE:We set out to explore whether platelet/vascular smooth muscle cell (VSMC) interactions contribute to coronary pathology in KD. METHODS AND RESULTS:We prospectively recruited and studied 242 patients with KD, 75 of whom had documented coronary artery pathology. Genome-wide miRNA sequencing and droplet digital PCR demonstrated that patient with KD platelets have significant induction of miR-223 compared with healthy controls (HCs). Platelet-derived miR-223 has recently been shown to promote vascular smooth muscle quiescence and resolution of wound healing after vessel injury. Paradoxically, patients with KD with the most severe coronary pathology (giant coronary artery aneurysms) exhibited a lack of miR-223 induction. Hyperactive platelets isolated from patients with KD are readily taken up by VSMCs, delivering functional miR-223 into the VSMCs promoting VSMC differentiation via downregulation of PDGFRβ (platelet-derived growth factor receptor β). The lack of miR-223 induction in patients with severe coronary pathology leads to persistent VSMC dedifferentiation. In a mouse model of KD (Lactobacillus casei cell wall extract injection), miR-223 knockout mice exhibited increased medial thickening, loss of contractile VSMCs in the media, and fragmentation of medial elastic fibers compared with WT mice, which demonstrated significant miR-223 induction upon Lactobacillus casei cell wall extract challenge. The excessive arterial damage in the miR-223 knockout could be rescued by adoptive transfer of platelet, administration of miR-223 mimics, or the PDGFRβ inhibitor imatinib mesylate. Interestingly, miR-223 levels progressively increase with age, with the lowest levels found in