Exploration of the expression and regulatory mechanisms of platelet miR-223-3p in hand, foot, and mouth disease (HFMD) complicated by encephalitis.

Background: Hand, foot, and mouth disease (HFMD) complicated by encephalitis is a severe condition with an acute onset, yet its pathogenesis remains incompletely understood. This study aimed to investigate the role of platelet miR-223-3p in HFMD complicated by encephalitis. We sought to determine its expression dynamics, verify its direct target F-box and WD repeat domain containing 7 ( Methods: We initially enrolled 20 children with HFMD complicated by encephalitis and 20 with uncomplicated HFMD. Platelet miRNA expression profiles were analyzed by high-throughput sequencing. Bioinformatics tools predicted key target genes, which were validated in a larger cohort (n=70) using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Gain- and loss-of-function models were established in SK-N-SH neuroblastoma cells by transfecting with an miR-223-3p mimic or inhibitor. A dual-luciferase reporter assay confirmed the direct targeting of Results: Platelet miR-223-3p was identified as the most significantly upregulated miRNA in the encephalitis group. Its expression was elevated in the acute phase but decreased during recovery (P<0.05). A significant negative correlation was observed between acute-phase miR-223-3p and whole-blood Conclusions: Our study demonstrates that platelet miR-223-3p is significantly upregulated in HFMD complicated by encephalitis. It promotes the pathogenesis of this condition by directly targeting