MicroRNA-326 Regulates Profibrotic Functions of Transforming Growth Factor-β in Pulmonary Fibrosis

Abstract

Idiopathic pulmonary fibrosis (IPF) is a fatal disorder resulting from the progressive remodeling of lungs, with no known effective treatment. Although transforming growth factor (TGF)-b has a wellestablished role in lung fibrosis, clinical experience with neutralizing antibodies to TGF-b has been disappointing, and strategies to directly suppress TGF-b1 secretion are needed. In this study we used a combination of in silico, in vitro, and in vivo approaches to identify microRNAs involved in TGF-b1 regulation and to validate the role of miR-326 in pulmonary fibrosis.We show that hsa-miR-326 regulates TGF-b1 expression and that hsa-miR-326 levels are inversely correlated to TGF-b1 protein levels in multiple human cell lines. The increase in TGF-b1 expression during the progression of bleomycin-induced lung fibrosis in mice was associated with loss of mmu-miR-326. Restoration of mmu-miR-326 levels by intranasal delivery of miR-326 mimics was sufficient to inhibit TGF-b1 expression and attenuate the fibrotic response. Moreover, human IPF lung specimens had markedly diminished miR-326 expression as compared with nonfibrotic lungs. Additional targets of miR-326 controlling TGF-b signaling and fibrosis-related pathways were identified, and miR-326 was found to down-regulate profibrotic genes, such as Ets1, Smad3, and matrix metalloproteinase 9, whereas it up-regulates antifibrotic genes, such as Smad7. Our results suggest for the first time that miR-326 plays a key role in regulating TGF-b1 expression and other profibrotic genes and could be useful in developing better therapeutic strategies for alleviating lung fibrosis.

MicroRNA-27a-3p Is a Negative Regulator of Lung Fibrosis by Targeting Myofibroblast Differentiation

“…There have been many successful efforts to harness miRs in treating human diseases, such as infectious and metabolic maladies (41,42). The roles of miRs in respiratory diseases, including pulmonary fibrosis, have also attracted a great deal of interest in recent years (23,25,26,30,(43)(44)(45). By targeting pro-or antifibrotic mediators, miRs can act as either negative or positive players in the pathogenesis of this disorder.…”

“…There is a growing list of miRs that has been shown to regulate the pathogenesis of pulmonary fibrosis (25,26,30,(43)(44)(45). For example, miR-26a and miR-21 regulates TGF-b1 activity through targeting Smad4 and Smad7, respectively, in lung fibroblasts (25,44).…”

Idiopathic pulmonary fibrosis and sleep disorders: no longer strangers in the night

“…The first report revealing the potential role of miRNAs in IPF demonstrated impressively by array analysis that 10% of the miRNAs were significantly different between IPF and control samples [121]. A series of elegant studies followed evaluating the miRNAs expression levels in IPF, such as the downregulation of members of Let-7, miR-29, miR-30, miR-31, miR-200, miR-326 and the miR-17-92 cluster, and the upregulation of miR-155 and miR-21 [121][122][123][124][125][126][127].…”

miR-18a-5p Inhibits Sub-pleural Pulmonary Fibrosis by Targeting TGF-β Receptor II

“…Approximately 10% of miRNAs expressed in the lungs of IPF patients show significant deregulation. 17 It has been found that miRNA-326, 18 let-7d, miRNA-29, miRNA-18a, 17 miRNA-26a, [18][19][20] and miRNA-200 21 are downregulated and miRNA-21, 22 miRNA-199a, 23 and miRNA-145 24 are upregulated in lungs of IPF patients. Alterations in these miRNAs have also been demonstrated in lung fibroblasts or alveolar epithelial cells from IPF patients and pulmonary fibrosis animal models.…”

“…Alterations in these miRNAs have also been demonstrated in lung fibroblasts or alveolar epithelial cells from IPF patients and pulmonary fibrosis animal models. 17,18,[21][22][23][24] However, changes in miRNAs in PMCs and their roles in PMC EMT and sub-pleural fibrosis have not been described. In the present study, we used cultured PMCs and a mouse pulmonary fibrosis animal model to explore the role of miRNA in PMC EMT and sub-pleural pulmonary fibrosis.…”