MicroRNA-142-3p inhibits IFN-γ production via targeting of RICTOR in Aspergillus fumigatus activated CD4+ T cells

Background: Aspergillus fumigatus (AFE) is a well-adapted, opportunistic fungus that causes a severe and commonly fatal disease, wherein IFN-gamma is one of the most important protective cytokines. The aim of this study was to investigate the microRNA expression profile and explore the underlying mechanism during infection with AFE. Methods: CD4(+) T cells were activated by co-culturing with dendritic cells (DCs), which were pre-treated with AFE. Next, we performed microRNA microarray expression profiles of activated and control T cells, following which, miRNA-142-3P was selected. To explore the effect of miR-142-3P on T cell activation, miRNA-142-3P expression was disrupted by transient transfection with miR-142-3P mimic or inhibitor. Then, levels of RICTOR, phosphorylated AKT and IFN-gamma were detected via Western blotting and qPCR respectively. We further used siRNA to decrease RICTOR expression and determined the role played by RICTOR in miR-142-3P mediated-IFN-gamma expression by qPCR following AFE-mediated T cell activation. Results: The heat-map of miRNA expression profiles showed that 54 microRNAs (miRNAs) were filtered, the levels of which, were significantly different between CD4(+) T cells activated by AFE and control T cells, in which microRNA-142-3 was involved. Forced expression of miRNA-142-3P dramatically suppressed RICTOR levels, phosphorylated AKT and IFN-gamma in AFE activated T cells. Conversely, loss of miRNA-142-3P elevated RICTOR levels, phosphorylated AKT and IFN-gamma. Notably, RICTOR deficiency decreased AKT phosphorylation levels and IFN-gamma secretion. Conclusions: Observations indicated that down-regulation of microRNA-142-3p enhanced IFN-gamma expression, and did so by promoting RICTOR expression in CD4(+) T cells activated by AFE.