Long non-coding RNA GAS5 regulates Th17/Treg imbalance in childhood pneumonia by targeting miR-217/STAT5.

The imbalance of helper T (Th) 17 and regulatory T (Treg) cells plays an important role in the pathogenesis of pneumonia. This study aims to investigate the role and mechanism of long non-coding RNA growth arrest-specific 5 (GAS5) in the differentiation of Th17 cells and Tregs in childhood pneumonia. Expression of GAS5, miR-217, signal transducer and activator of transcription-5 (STAT5), receptor-related orphan receptor γt (RORγt), and transcription factor Forkhead box P3 (Foxp3) were examined by qRT-PCR and western blot. The percentage of Th17 cells and Tregs in CD4+ T cells were measured by flow cytometry. The interaction between miR-217 and GAS5 or STAT5 was analyzed by luciferase reporter assay. Downregulated GAS5 expression and Treg cell percentage, and upregulated Th17 cell percentage were observed in pneumonia patients when compared with the healthy controls. Furthermore, GAS5 overexpression corrected the imbalanced Th17/Treg in peripheral blood CD4+ T cells derived from pneumonia patients, and this effect was reversed by miR-217 mimic and STAT5 silencing. Mechanistically, GAS5 acted as a sponge of miR-217 to reduce binding of miR-217 to its target STAT5, leading to upregulation of STAT5 expression. Taken together, GAS5 corrects the Treg/Th17 imbalance by targeting the miR-217/STAT5 axis in childhood pneumonia.