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Matrix remodeling is a salient feature of idiopathic pulmonary fibrosis (IPF). Targeting cells driving matrix production and remodeling could be a promising avenue for IPF treatment. Analysis of public transcriptomic database identified paired-related homeobox protein-1 (PRRX1) as an upregulated mesenchymal transcription factor (TF) in IPF. We confirmed that PRRX1 isoforms were upregulated in IPF lung tissue and strongly expressed by lung fibroblasts. In vitro, PRRX1 expression was up-regulated by cues associated with proliferative and anti-fibrotic properties in lung fibroblasts, while IPF fibroblast-derived matrix increased PRRX1 TFs expression in a PDGFR dependent manner in control ones. Meanwhile, signals promoting myofibroblastic differentiation decreased PRRX1 TF. We demonstrated that PRRX1 inhibition decreased fibroblast proliferation by downregulating the expression of S phase cyclins. PRRX1 inhibition also impacted TGF-{beta} driven myofibroblastic differentiation by inhibiting SMAD2/3 phosphorylation through phosphatase PPM1A upregulation and TGFBR2 downregulation, leading to a TGF-{beta} response global decrease. Finally, targeted inhibition of Prrx1 TFs attenuated fibrotic remodeling both in vivo with intra-tracheal antisense oligonucleotides in the bleomycin mice model of lung fibrosis and ex vivo using mouse and Human precision-cut lung slices stimulated with fibrosis cytokine cocktail. Altogether, our results identified PRRX1 as a mesenchymal transcription factor driving myofibroblastic phenotype and lung fibrogenesis. Brief SummaryInhibition of a single fibroblast-associated transcription factor, namely paired-related homeobox protein 1, is sufficient to dampen lung fibrogenesis.

BACKGROUND Ischemia-reperfusion injury (IRI) is associated with morbidity and mortality. MicroRNAs (miRNAs) have emerged as regulators of IRI, and they are involved in the pathogenesis of organ rejection. Lidocaine has proven anti-inflammatory activity in several tissues but its modulation of miRNAs has not been investigated. This work aims to investigate the involvement of miRNAs in lung IRI in a lung auto-transplantation model and to investigate the effect of lidocaine. METHODS Three groups (sham, control, and Lidocaine), each comprising 6 pigs, underwent a lung autotransplantation. All groups received the same anesthesia. In addition, animals of lidocaine group received a continuous intravenous administration of lidocaine (1.5 mg/kg/h) during surgery. Lung biopsies were taken before pulmonary artery clamp, before reperfusion, 30 minutes postreperfusion (Rp-30), and 60 minutes postreperfusion (Rp-60). Samples were analyzed for different miRNAs (miR-122, miR-145, miR-146a, miR-182, miR-107, miR-192, miR-16, miR-21, miR-126, miR-127, miR142-5p, miR152, miR155, miR-223, and let7) via the use of reverse-transcription quantitative polymerase chain reaction. Results were normalized with miR-103. RESULTS The expression of miR-127 and miR-16 did not increase after IRI. Let-7d, miR-21, miR-107, miR-126, miR-145, miR-146a, miR-182, and miR-192 significantly increased at the Rp-60 (control versus sham P < .001). miR-142-5p, miR-152, miR-155, and miR 223 significantly increased at the Rp-30 (control versus sham P < .001) and at the Rp-60 (control versus. sham P < .001). The administration of lidocaine was able to attenuate these alterations in a significant way (control versus Lidocaine P < .001). CONCLUSIONS Lung IRI caused dysregulation miRNA. The administration of lidocaine reduced significantly miRNAs alterations.

IPF is characterized by a reactivation of signaling pathways involved in lung development, such as Fibroblast Growth Factors (FGF). FGFR4 is a FGF receptor activated by endocrine FGFs, such as FGF19, in the presence of the co-receptor s klotho. Recent evidence indicates that complete deletion of FGFR4 and Fgf15 (murine orthologue of FGF19) leads to increased liver fibrosis suggesting that the FGFR4/FGF19 axis has some antifibrotic properties. The aim of this work was to study the regulation of FGFR4 expression and to assess the effect of its activation/inibition on the lung fibroblast phenotype. Material and Methods: We assessed FGFR4, s klotho and FGF19 expression by immunohistochemistry RT-PCR in lung tissue from controls and IPF patients. Human lung fibroblasts from IPF and control patients were stimulated in vitro with pro- or anti-fibrotic factors with or without FGF19 (20 ng/mL) during 48 hours. We studied the expression of FGFR4 at mRNA level and assessed the effect of FGF19 on fibroblast differentiation, proliferation and migration. Results: FGFR4 and s klotho were expressed by alveolar epithelial cells and by lung fibroblast in IPF lung, while FGF19 was not detected. FGFR4 mRNA expression by control and IPF fibroblasts was downregulated by pro fibrotic factors (TGFβ, CTGF, ET-1) and up-regulated by HGF. FGF9 prevented the TGFs- induced myofibroblast differentiation by significantly decreasing αSMA, Collagen1 , fibronectin, PAI-1 and CTGF at mRNA and protein levels. FGF19 increased fibroblast migration but didn9t influence proliferation. Conclusion: FGF19 inhibits TGFβ-induced differentiation in vitro. FGF19 may have anti-fibrotic properties in the lung which need to be documented in vivo.

Introduction Fibroblast differentiation in myofibroblasts is a key feature of idiopathic pulmonary fibrosis (IPF). Paired-related homeobox (PRRX) transcription factors (TF) regulate mesenchymal cells during development and are key TF at the center of a network coordinating fibroblast differentiation. We hypothesized that PRRX1 modulates fibroblast phenotype in IPF. Material and methods Immunohistochemistry (IHC) and real-time quantitative PCR for PRRX were performed on human lung samples and primary human lung fibroblasts (HLF) cultured from IPF and controls. PRRX1 overexpression was obtained in HLF with plasmid transfection. Functional experiments were performed by seeding HLF on dishes with an elastic modulus (EM) of 1.5 or 28 kPa or on a rigid dish. The effects of the ROCK and PTGS2 inhibitors Fasudil and NS398 on PRRX1 expression were evaluated. Results PRRX1 was upregulated in IPF lung and HLF as compared to controls and was mostly detected in fibroblast foci. PRRX1 expression was controlled by soluble factors and by the extracellular matrix stiffness: Profibrotic factors TGF-β and ET-1 downregulated PRRX1 expression in HLF, while PDGF-AA and PGE2 increased PRRX1 expression only in HLF from IPF patients. Soft matrix (EM 1.5 kPa) enhanced PRRX1 expression in HLF through the activation of PTGS2, while a rigid matrix inhibited PRRX1 expression through ROCK activation. PRRX1 overexpression inhibited PDGF-dependent migration, increased the expression of phosphorylated ERK and promoted control and IPF HLF survival after serum deprivation or FAS-L activation. Conclusion These results indicate that PRRX1 is regulated by the fibrotic environment in the lung and controls lung fibroblast migration and survival.