MiR-9-5p suppresses pro-fibrogenic transformation of fibroblasts and prevents organ fibrosis by targeting NOX4 and TGFBR2

© 2015 The Authors. Uncontrolled extracellular matrix (ECM) production by fibroblasts in response to injury contributes to fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Reactive oxygen species (ROS) generation is involved in the pathogenesis of IPF. Transforming growth factor-β1 (TGF-β1) stimulates the production of NADPH oxidase 4 (NOX4)-dependent ROS, promoting lung fibrosis (LF). Dysregulation of microRNAs (miRNAs) has been shown to contribute to LF. To identify miRNAs involved in redox regulation relevant for IPF, we performed arrays in human lung fibroblasts exposed to ROS. miR-9-5p was selected as the best candidate and we demonstrate its inhibitory effect on TGF-β receptor type II (TGFBR2) and NOX4 expression. Increased expression of miR-9-5p abrogates TGF-β1-dependent myofibroblast phenotypic transformation. In the mouse model of bleomycin-induced LF, miR-9-5p dramatically reduces fibrogenesis and inhibition of miR-9-5p and prevents its anti-fibrotic effect both in vitro and in vivo. In lung specimens from patients with IPF, high levels of miR-9-5p are found. In omentum-derived mesothelial cells (MCs) from patients subjected to peritoneal dialysis (PD), miR-9-5p also inhibits mesothelial to myofibroblast transformation. We propose that TGF-β1 induces miR-9-5p expression as a self-limiting homeostatic response.Ministerio de Economía y Competitividad (MINECO) SAF 2012-31338 (SL), SAF 2013-47611 (MLC) and CSD 2007-00020 (SL), Instituto de Salud Carlos III REDinREN RD12/0021/0009 (SL and LGB) and FIS PS12/00094 (LGB), Comunidad de Madrid “Fibroteam” S2010/BMD-2321 (SL and MLC) and Fundación Renal “Iñigo Alvarez de Toledo” (SL), all from Spain. Supported by European Cooperation in Science and Research COST actions BM-1203 (EU-ROS) and BM-1005 (ENOGAS) (SL). The CBMSO receives institutional support from Fundación “Ramón Areces”.Peer Reviewe