RESUMO
BACKGROUND: Lung fibroblasts are involved in extracellular matrix homeostasis, which is mainly regulated by transforming growth factor-beta (TGF-ß), and are therefore crucial in lung tissue repair and remodeling. Abnormal repair and remodeling has been observed in lung diseases like COPD. As miRNA levels can be influenced by TGF-ß, we hypothesized that TGF-ß influences miRNA expression in lung fibroblasts, thereby affecting their function. MATERIALS AND METHODS: We investigated TGF-ß1-induced miRNA expression changes in 9 control primary parenchymal lung fibroblasts using miRNA arrays. TGF-ß1-induced miRNA expression changes were validated and replicated in an independent set of lung fibroblasts composted of 10 controls and 15 COPD patients using qRT-PCR. Ago2-immunoprecipitation followed by mRNA expression profiling was used to identify the miRNA-targetomes of unstimulated and TGF-ß1-stimulated primary lung fibroblasts (n = 2). The genes affected by TGF-ß1-modulated miRNAs were identified by comparing the miRNA targetomes of unstimulated and TGF-ß1-stimulated fibroblasts. RESULTS: Twenty-nine miRNAs were significantly differentially expressed after TGF-ß1 stimulation (FDR<0.05). The TGF-ß1-induced miR-455-3p and miR-21-3p expression changes were validated and replicated, with in addition, lower miR-455-3p levels in COPD (p<0.05). We identified 964 and 945 genes in the miRNA-targetomes of unstimulated and TGF-ß1-stimulated lung fibroblasts, respectively. The TGF-ß and Wnt pathways were significantly enriched among the Ago2-IP enriched and predicted targets of miR-455-3p and miR-21-3p. The miR-455-3p target genes HN1, NGF, STRADB, DLD and ANO3 and the miR-21-3p target genes HHEX, CHORDC1 and ZBTB49 were consistently more enriched after TGF-ß1 stimulation. CONCLUSION: Two miRNAs, miR-455-3p and miR-21-3p, were induced by TGF-ß1 in lung fibroblasts. The significant Ago2-IP enrichment of targets of these miRNAs related to the TGF-ß and/or Wnt pathways (NGF, DLD, HHEX) in TGF-ß1-stimulated fibroblasts suggest a role for these miRNAs in lung diseases by affecting lung fibroblast function.
