A miRNA upregulated in asthma airway T cells promotes T(H)2 cytokine production

MicroRNAs (miRNAs) exert powerful effects on immune function by tuning networks of target genes that orchestrate cell behavior. We sought to uncover miRNAs and miRNA-regulated pathways that control the T(H)2 responses that drive pathogenic inflammation in asthma. Profiling miRNA expression in human airway-infiltrating T cells revealed miR-19a elevation in asthma. Modulating miR-19 activity altered T(H)2 cytokine production in both human and mouse T cells, and T(H)2 cell responses were markedly impaired in cells lacking the entire miR-17∼92 cluster. miR-19 promotes T(H)2 cytokine production and amplifies PI(3)K, JAK-STAT, and NF-κB signaling by direct targeting of PTEN, SOCS1, and A20. Thus, miR-19a up regulation in asthma may be an indicator and a cause of increased T(H)2 cytokine production in the airways.