Collagen Production In Lung Fibroblasts Research Articles

Baicalein alleviated TGF β1-induced type I collagen production in lung fibroblasts via downregulation of connective tissue growth factor

Although we have reported that baicalein ameliorated bleomycin-induced pulmonary fibrosis in rats and inhibited fibroblast-to-myofibroblast differentiation, the mechanisms of the capability of baicalein to suppress the production of type I collagen in fibroblasts remains unclear. Here, we showed that baicalein suppressed transforming growth factor β1 (TGF β1)-stimulated the production of type I collagen in lung fibroblast MRC-5 cells. By applying SILAC-based proteomic technology, 158 proteins were identified as baicalein-modulated proteins in TGF β1-stimulated the accumulation of type I collagen in MRC-5 cells. Our proteomic and biochemical analysis demonstrated that baicalein decreased the expression levels of connective tissue growth factor (CTGF) in TGF β1-stimulated MRC-5 cells. In addition, CTGF overexpression elevated the levels of type I collagen in baicalein-treated fibroblasts. Moreover, our results demonstrated that baicalein-downregulated CTGF expression might be related with the decrease of Smad2 phosphorylation, but not SP1. This work not only linked CTGF to TGF β1-stimulated the production of type I collagen in its attribution to the effects of baicalein, but also might provide valuable information for enhancing the knowledge of the pharmacological inhibition of collagen production, which might represent a promising strategy for the treatment of pulmonary fibrosis.

YAP1/Twist promotes fibroblast activation and lung fibrosis that conferred by miR-15a loss in IPF.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic parenchymal lung disease of unknown etiology and lack effective interventions. Using a combination of in vitro and in vivo studies, we found that overexpression of YAP1, a key effector in the Hippo pathway, promoted cell proliferation, migration, and collagen production in lung fibroblasts. Furthermore, the pro-fibrotic action of YAP1 was mediated by transcriptional activation of Twist1 through interacting with its partner TEAD. In contrast, knockdown of YAP1 inhibited extracellular matrix (ECM) deposition, which ultimately ameliorated lung fibrosis in vitro and in vivo. Additionally, we constructed a dysregulated miRNA regulatory network that affects the expression of the Hippo pathway effectors in IPF and identified miR-15a, which is significantly down-regulated in IPF patients, as one of the most essential miRNAs regulating this pathway. Moreover, knockdown of miR-15a resulted in fibroblast activation and lung fibrosis through promoting Twist expression by targeting inhibition of YAP1. In contrast, therapeutic restoration of miR-15a inhibits fibrogenesis in lung fibroblast and abrogated BLM-induced lung fibrosis in mice. These results highlight a role for miR-15a/YAP1/Twist axis in IPF that offer novel strategies for the prevention and treatment of lung fibrosis.

Heparin-binding epidermal growth factor contributes to COPD disease severity by modulating airway fibrosis and pulmonary epithelial–mesenchymal transition

Although airway fibrosis and epithelial–mesenchymal transition (EMT) contribute to airway remodeling in chronic obstructive pulmonary disease (COPD), the mechanisms underlying their development have not been fully elucidated. In the present study, we aimed to assess heparin-binding epidermal growth factor (HB-EGF) expression in the airways of patients with COPD and to elucidate the possible role of HB-EGF in the pathology of COPD. Sputum and lung tissue HB-EGF expression was evaluated in control subjects and patients with COPD. The relationships between HB-EGF expression, disease severity, collagen deposition (fibrosis), and EMT were investigated. In vitro, human bronchial epithelial (HBE) cells and lung fibroblast cells exposed to the recombinant HB-EGF, collagen deposition and EMT were assessed. We found that sputum HB-EGF expression was significantly increased in patients with COPD compared with non-smokers and smokers without COPD. There was a significant positive correlation between sputum HB-EGF and COPD assessment test (CAT) score. HB-EGF expression was significantly increased in the lung tissue samples of patients with COPD and associated with collagen deposition and N- and E-cadherin, and vimentin expression. In vitro, HB-EGF promoted collagen production in lung fibroblasts. Moreover, HB-EGF induced the EMT process through induction of N-and E-cadherin, and vimentin expression in HBE cells. Collectively, HB-EGF induces airway remodeling by modulating airway fibrosis and pulmonary EMT, and contributes to the COPD severity. The current data may provide insight into the underlying pathogenesis of COPD, in which HB-EGF has an important pathogenic role.This paper describes the relationship between heparin-binding epidermal growth factor (HB-EGF) and chronic obstructive pulmonary disease (COPD). HB-EGF expression is significantly increased in lung tissue of patients with COPD. In vitro, HB-EGF promotes collagen production in lung fibroblasts and induces epithelial-mesenchymal transition through induction of N-and E-cadherin, and vimentin expression. These results may provide insight into the underlying pathogenesis of COPD.

Glycopyrronium bromide inhibits lung inflammation and small airway remodeling induced by subchronic cigarette smoke exposure in mice

The effects of long-acting muscarinic receptor antagonists (LAMAs) have not been evaluated in a model with simultaneous lung inflammation and small airway remodeling induced by cigarette smoke (CS). We exposed the mice to CS for four weeks with daily treatment with a LAMA (glycopyrronium bromide, NVA237) or its vehicle. Human bronchial epithelial cells (PBECs) and lung fibroblasts were exposed to CS extract (CSE) or acetylcholine with or without NVA237 treatment. We found that NVA237, but not its vehicle, suppressed elevations in inflammatory score, epithelial thickness, and peribronchial collagen deposition in CS-exposed mice. NVA237 alleviated CS-induced increased levels of chemokines, inflammatory cells, and total protein in the bronchoalveolar lavage fluid. NVA237 suppressed acetylcholine- or CSE-induced elevations in IL-8 production in PBECs and elevations in proliferation and collagen production in lung fibroblasts. These phenomena were also prevented by a p44/42 MAPK inhibitor. In conclusion, NVA237 exerted a potent suppressive effect on lung inflammation and small airway remodeling induced by subchronic CS exposure.

Mogroside IIIE, a Novel Anti-Fibrotic Compound, Reduces Pulmonary Fibrosis through Toll-Like Receptor 4 Pathways.

Idiopathic pulmonary fibrosis is a progressive fibrotic lung disease, and eventually most patients develop respiratory failure with a median survival rate of 2 to 3 years after diagnosis due to the lack of clinically effective therapies. Mogroside IIIE (MGIIIE), a cucurbitane-type compound, was isolated from Siraitia grosvenorii MGIIIE has shown the strongest inhibition of nitric oxide release, a crucial inflammatory factor, from lipopolysaccharide (LPS)-treated RAW264.7 cells compared with other mogrosides. In the pulmonary fibrosis mouse model induced by bleomycin, MGIIIE treatment attenuated pulmonary fibrosis, indicated as a reduction in myeloperoxidase activity, collagen deposition, and pathologic score. MGIIIE also significantly suppressed expression of several important fibrotic markers, e.g., α-smooth muscle actin, collagen I, transforming growth factor-β (TGF-β) signal, and metalloproteinases-9/tissue inhibitor of metalloproteinase-1. Furthermore, MGIIIE blocked tansdifferentiation of lung resident fibroblasts into myofibroblast-like cells induced by TGF-β or LPS and subsequently inhibited collagen production in lung fibroblasts. These data indicate that MGIIIE is a potent inhibitor for pulmonary fibrosis. In vitro and in vivo mechanistic studies have shown that MGIIIE significantly decreased expression of toll-like receptor 4 (TLR4) and its downstream signals of myeloid differentiation factor 88 (MyD88)/mitogen-activated protein kinase (MAPK), an inflammatory signal essential for extracellular matrix (ECM) deposition in pulmonary fibroblasts. Taken together, these results demonstrate that MGIIIE significantly prevents pulmonary fibrosis by inhibiting pulmonary inflammation and ECM deposition through regulating TLR4/MyD88-MAPK signaling. Our study suggests that MGIIIE may have therapeutic potential for treating pulmonary fibrosis in clinical settings.

Identification of TGF-β receptor-1 as a key regulator of carbon nanotube-induced fibrogenesis.

Carbon nanotubes (CNTs) induce rapid interstitial lung fibrosis, but the underlying mechanisms are unclear. Previous studies indicated that the ability of CNTs to penetrate lung epithelium, enter interstitial tissue, and stimulate fibroblasts to produce collagen matrix is important to lung fibrosis. In this study, we investigated the activation of transforming growth factor-β receptor-1 [TGF-β R1; i.e., activin receptor-like kinase 5 (ALK5) receptor] and TGF-β/Smad signaling pathway in CNT-induced collagen production in human lung fibroblasts. Human lung fibroblasts and epithelial cells were exposed to low, physiologically relevant concentrations (0.02-0.6 μg/cm(2)) of single-walled CNTs (SWCNT) and multiwalled CNTs (MWCNT) in culture and analyzed for collagen, TGF-β1, TGF-β R1, and SMAD proteins by Western blotting and immunofluorescence. Chemical inhibition of ALK5 and short-hairpin (sh) RNA targeting of TGF-β R1 and Smad2 were used to probe the fibrogenic mechanism of CNTs. Both SWCNT and MWCNT induced an overexpression of TGF-β1, TGF-β R1 and Smad2/3 proteins in lung fibroblasts compared with vehicle or ultrafine carbon black-exposed controls. SWCNT- and MWCNT-induced collagen production was blocked by ALK5 inhibitor or shRNA knockdown of TGF-β R1 and Smad2. Our results indicate the critical role of TGF-β R1/Smad2/3 signaling in CNT-induced fibrogenesis by upregulating collagen production in lung fibroblasts. This novel finding may aid in the design of mechanism-based risk assessment and development of rapid screening tests for nanomaterial fibrogenicity.

Fibroblast's Phenotypic Changes in Chronic Heart Failure‐induced Pulmonary Fibrosis

Chronic heart failure (HF) leads to irreversible changes in the lung architecture including tissue remodeling and the development of pulmonary fibrosis. Data from our rat model show that left‐sided HF induces pulmonary edema, triggering fibroblast remodeling and fibrosis development. We hypothesized that fibroblasts undergo phenotypic changes with chronic exposure to cytokines secreted by neutrophils and/or macrophages in chronic HF. We used our chronic HF rat model and primary cell cultures to determine phenotypic changes related to fibrosis development in pulmonary fibroblasts including increased proliferation and collagen production. Lung fibroblasts isolated from rat lung after 7 days of HF were significantly more proliferative compared to cells isolated from control rat lungs. Collagen production in lung fibroblasts isolated from HF group more than doubled compared to collagen production in control lung fibroblasts. The increased proliferative state of lung fibroblasts in HF group combined with increased collagen production per cell, would translate into a great enhanced fibrogenic phenotype in HF group compared to control group. Lung fibroblasts from HF group also expressed more smooth muscle actin indicating differentiation to a more myofibroblast phenotype. Our data are essential to facilitate the identification of drug targets and treatment strategies to improve outcomes in HF patients.

EM703 improves bleomycin-induced pulmonary fibrosis in mice by the inhibition of TGF-β signaling in lung fibroblasts

BackgroundFourteen-membered ring macrolides have been effective in reducing chronic airway inflammation and also preventing lung injury and fibrosis in bleomycin-challenged mice via anti-inflammatory effects. EM703 is a new derivative of erythromycin (EM) without the bactericidal effects. We investigated the anti-inflammatory and antifibrotic effects of EM703 in an experimental model of bleomycin-induced lung injury and subsequent fibrosis in mice.MethodsSeven-week-old male ICR mice were used. All experiments used eight mice/group, unless otherwise noted in the figure legends. Bleomycin was administered intravenously to the mice on day 0. EM703 was orally administered daily to mice. All groups were examined for cell populations in the bronchoalveolar lavage (BAL) fluid and for induction of messenger RNA (mRNA) of Smad3 and Smad4 in the lung tissues by reverse transcriptase (RT)-polymerase chainreaction (PCR) on day 7. Fibroblastic foci were assessed histologically, and the hydroxyproline content was chemically determined in the lung tissues on day 28. We performed assay of proliferation and soluble collagen production, and examined the induction of mRNA of Smad3 and Smad4 by RT-PCR in murine lung fibroblast cell line MLg2908. We also examined Smad3, Smad4 and phosphorylated Smad2/3 (p-Smad2/3) protein assay by western blotting in MLg2908.ResultsBleomycin-induced lung fibrosis, and the infiltration of macrophages and neutrophils into the airspace were inhibited by EM703. The expression of Smad3 and Smad4 mRNA was clearly attenuated by bleomycin, but was recovered by EM703. EM703 also inhibited fibroblast proliferation and the collagen production in lung fibroblasts induced by Transforming growth factor-beta (TGF-β). The expression of Smad3 and Smad4 mRNA in murine lung fibroblasts disappeared due to TGF-β, but was recovered by EM703. EM703 inhibited the expression of p-Smad2/3 and Smad4 protein in murine lung fibroblasts induced by TGF-β.ConclusionThese findings suggest that EM703 improves bleomycin-induced pulmonary fibrosis in mice by actions of anti-inflammation and regulation of TGF-β signaling in lung fibroblasts.

CCL18‐stimulated upregulation of collagen production in lung fibroblasts requires Sp1 signaling and basal Smad3 activity

A CC chemokine CCL18 stimulates collagen production in pulmonary fibroblasts through an unknown signaling mechanism. In this study, involvement of Sp1 and Smad3 in CCL18 signaling in primary human pulmonary fibroblast cultures was investigated. Phosphorylation of Sp1, DNA-binding by Sp1, and the activity of an Sp1-dependent reporter were all increased in response to CCL18 stimulation. CCL18 did not stimulate a detectable increase in Smad3 phosphorylation or Smad3/4 DNA-binding activity, although some basal phosphorylation and DNA binding by Smad3/4 were noted. Transient overexpression of dominant negative mutants of Sp1 and Smad3 abrogated CCL18-dependent upregulation as well as basal production of collagen. These observations suggested that CCL18 activates collagen production in pulmonary fibroblasts through an Sp1-dependent pathway that also requires basal Smad3 activity. Possible involvement of autocrine TGF-beta in CCL18 signaling was considered. CCL18 stimulated increases in collagen mRNA and protein production without detectable changes in TGF-beta1, -beta2, and -beta3 mRNA or protein levels. Neutralizing anti-TGF-beta antibodies, latency-associated peptide, ALK5-specific inhibitor SD431542, and an inhibitor of the protease-dependent TGF-beta activation aprotinin, each failed to block CCL18-stimulated collagen production. These observations suggest that both CCL18 signaling in pulmonary fibroblasts and basal Smad3 activity are independent of autocrine TGF-beta.

Pulmonary and activation-regulated chemokine stimulates collagen production in lung fibroblasts.

Levels of pulmonary and activation-regulated chemokine (PARC) mRNA and protein are increased in the lungs of patients with pulmonary fibrosis. The purpose of this study was to establish whether PARC could be directly involved in development of pulmonary fibrosis by stimulating collagen production in lung fibroblasts. Exposure to PARC increased production of collagen mRNA and protein by 3- to 4-fold in normal adult lung and dermal fibroblast cells. Collagen mRNA transiently increased after 3-6 h of activation with PARC, with an increase in collagen protein detected after 24 h of activation. At the same time, PARC had less pronounced effect on fibroblast proliferation, not exceeding 50% increase over control nonstimulated cells. PARC intracellular signaling led to activation of ERK1/2, but not p38, in fibroblasts; pharmacologic inhibition of ERK, but not p38, also blocked PARC's effect on collagen production. Inhibition experiments with pertussis toxin suggested that PARC receptor is G protein-coupled. Thus, PARC is a member of the CC chemokine family that acts directly as a profibrotic factor.

Molecular cross-talk between the TRAIL and TGF-β pathways in human lung fibroblasts

Tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) has been closely associated with regulation of the immune response and pathogenesis of autoimmune diseases. The expression of TRAIL was found in CD8 T cells that had undergone oligoclonal expansion in the lungs of patients with systemic sclerosis and were able to stimulate collagen production in lung fibroblasts. Soluble, multimerized TRAIL and normal human lung fibroblasts were used as a model of selective TRAIL influence on fibroblasts. TRAIL was found to increase both α2(I) collagen mRNA expression and total soluble collagen secretion, with peak response at 1 ng/ml TRAIL. DNA microarray analysis suggested that fibroblast response to TRAIL might be mediated by c-Jun N-terminal kinase (JNK). The increase in JNK1 expression and phosphorylation as well as phosphorylation of its specific substrate were confirmed by Western blotting. The treatment of fibroblasts with TRAIL also enhanced the expression of a number of genes involved in tissue remodeling, including those related to the transforming growth factor (TGF) beta pathway. The increase in TGF-β1 mRNA level was confirmed by Northern blotting and by measurements of active TGF-β1 in culture supernatants. In addition, antibody-mediated blocking of TGF-β was shown to abrogate TRAIL-induced collagen synthesis. These data suggest that TRAIL can enhance extracellular matrix production in fibroblasts by triggering expression of TGF-β, which acts in an autocrine manner. If this process continues uncontrolled, it may contribute to the development of fibrosis, particularly in the lungs of patients with systemic sclerosis.

TRAIL-mediated enhancement of collagen production by human lung fibroblasts

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family that induces apoptosis in a variety of transformed cell lines and in normal human hepatocytes in vitro. The expression of TRAIL was found in CD8 T cells that had undergone oligoclonal expansion in the lungs of patients with systemic sclerosis (scleroderma) and were able to stimulate collagen production in lung fibroblasts in vitro. Among the family members, TRAIL displays highest homology to CD95 ligand, a receptor of which may not only mediate apoptosis of T cells, but also mediate the proliferation of normal human fibroblasts. Considering structural and functional similarities between TRAIL and CD95 ligand, we examined the effects of soluble TRAIL on normal human lung fibroblasts. Collagen α2(I) mRNA expression was assessed by real-time RT-PCR, with ribosomal protein S9 as an internal standard. Total soluble collagen was measured in culture supernatants using the Sircol Biocolor Assay. Both normalized α2(I) collagen mRNA expression and total soluble collagen secretion were increased upon TRAIL stimulation, with peak response (>5-fold increase) at 10 ng/ml TRAIL. DNA microarray hybridization revealed 78 genes involved in signal transduction, DNA transcription, and tissue remodeling, whose expression level increased, and 8 genes whose expression level decreased >2.5-fold in comparison with quiescent fibroblasts. Augmented expression of a number of genes involved in the TGFβ pathway suggested that TRAIL might induce TGFβ-mediated autocrine and/or paracrine stimulation of fibroblasts. This was confirmed by the ability of anti-TGFβ antibody to inhibit the effects of TRAIL on collagen production by fibroblasts. DNA mobility shift assay also revealed TRAIL-induced increase in protein binding to the collagen promoter that was substantially inhibited by consensus oligonucleotide for Smad3/4, mediators of TGFβ signaling. These data suggest that TRAIL can enhance extracellular matrix synthesis in fibroblasts by triggering TGFβ production, which acts in autocrine manner.

Human eosinophils regulate human lung- and skin-derived fibroblast properties in vitro: a role for transforming growth factor beta (TGF-beta).

Eosinophils have been associated with fibrosis. To investigate their direct role in fibrosis, human peripheral blood eosinophil sonicate was added to human lung or dermal fibroblasts, and proliferation ([(3)H]thymidine) and collagen synthesis ([(3)H]proline) were evaluated. Proliferation was enhanced significantly in the monolayers in a dose-dependent manner. The activity of the eosinophil fibrogenic factor(s) remained unaltered when heated (56 degrees C, 30 min). Supernatants of cultured eosinophils (20 min or 18 hr) also enhanced lung fibroblast proliferation, indicating that the preformed mitogenic factor(s) can be released both promptly and with a long kinetic. Eosinophils significantly decreased collagen production in lung fibroblasts while increasing it in dermal fibroblasts. However, eosinophils containing matrix metalloproteinase 9 (zymography) in latent form and tissue inhibitors of metalloproteinases 1 and 2 (reverse zymography) did not influence either fibroblast matrix metalloproteinases or tissue inhibitors of metalloproteinases. Eosinophil sonicate added to skin and lung fibroblasts in tridimensional collagen lattices significantly enhanced lattice contraction. Transforming growth factor beta (TGF-beta) is a major fibrogenic cytokine produced by eosinophils. Therefore, to assess its role, eosinophil sonicate was preincubated with anti-TGF-beta neutralizing antibodies. This treatment partially inhibited proliferation of lung and collagen synthesis of dermal fibroblasts and suppressed the stimulation of lattice contraction, indicating the fibrogenic role of eosinophil-associated TGF-beta. In conclusion, we have shown that eosinophils act as direct modulatory cells in fibroblast proliferation, collagen synthesis, and lattice contraction, in part, through TGF-beta. These data corroborate the importance of eosinophils in skin and lung fibrosis.

Retinoic acid inhibition of transforming growth factor-beta-induced collagen production by human lung fibroblasts.

Transforming growth factor-beta (TGF-beta)-stimulated collagen production plays an important role in the pathogenesis of the fibrotic response seen in chronic inflammatory lung disorders. Retinoids are vitamin A analogues that are potent immunomodulators and have been shown to modulate stromal cell collagen production in a variety of nonpulmonary systems. We hypothesized that retinoids might also modulate lung fibroblast collagen production. To test this hypothesis, we determined whether all-trans retinoic acid (RA) and several other retinoid compounds regulate the production of types I and III collagen by unstimulated and TGF-beta 1-stimulated human lung fibroblasts. Unstimulated cells produced modest quantities of types I and III collagen, and TGF-beta 1 increased the production of these matrix molecules 2- to 4-fold. Preincubation with 10(-5) M RA caused a significant decrease in the basal levels of types I and III collagen produced by these cells. RA preincubation also totally abrogated the collagen inductive effects of TGF-beta 1. At 10(-5) M, RA preincubation caused a 97% decrease in the stimulation of type I collagen and a 115% decrease in the stimulation of type III collagen caused by TGF-beta 1. These inhibitory effects were dose dependent. Significant inhibition of type I and III collagen production was appreciated with doses of RA as low as 10(-9) and 10(-8), respectively. These inhibitory effects were not unique to RA since 13-cis-retinoic acid, 9-cis-retinoic acid, etretinate, all-trans etretin, and the water-soluble retinoids, retinoyl beta-glucuronide and retinyl-beta-glucuronide, also inhibited TGF-beta 1-stimulated type I collagen production.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of the effects of alveolar macrophages on lung fibroblast collagen production rate.

Alveolar macrophages (AM) may function as effector cells that can either stimulate or inhibit lung fibroblast collagen production. However, conditions that determine the predominant effect of AM on fibroblasts are not well understood. To delineate factors that modulate the effects of AM on lung fibroblasts, we studied the interaction of AM products and fibroblasts in vitro. The AM were obtained by bronchoalveolar lavage of hamsters with bleomycin-induced pulmonary fibrosis. Conditioned medium (CM) from the AM cultures was incubated in varying amounts with lung fibroblast (IMR-90) cultures. After metabolic labeling with [3H]proline, fibroblast collagen production based on procollagen-specific radioactivity was determined (Anal Biochem 1984; 140:478). Macrophage CM in concentrations greater than 5% suppressed collagen production, an event attributed to the macrophage-derived suppressive factor that we have previously characterized (J Clin Invest 1983; 72:2082). Macrophages were also determined to produce PGE2 in culture (500 pg/10(6) cells). Authentic PGE2 at concentrations found in CM was found to suppress fibroblast collagen production, indicating that AM-derived PGE2 contributes to the suppressive activity in CM. To examine possible stimulatory factors in CM, the fibroblasts were preincubated with indomethacin. This approach was based on our previous observation that AM-derived suppressive factor increases endogenous fibroblast PGE2 and that its activity can be blocked by indomethacin. Macrophage CM in a concentration of 20% did not suppress the collagen production of indomethacin-treated fibroblasts. However, CM concentrations of 5 and 10% increased collagen production (173 and 143% of control values, respectively), indicating the presence of stimulatory factor(s) in macrophage-conditioned medium.(ABSTRACT TRUNCATED AT 250 WORDS)