B Cells Are Not Involved in the Regulation of Adenoviral TGF-ß1- or Bleomycin-Induced Lung Fibrosis in Mice.

Idiopathic pulmonary fibrosis (IPF) is an irreversible, age-related diffuse parenchymal lung disease of poorly defined etiology. Many patients with IPF demonstrate distinctive lymphocytic interstitial infiltrations within remodeled lung tissue with uncertain pathogenetic relevance. Histopathological examination of explant lung tissue of patients with IPF revealed accentuated lymphoplasmacellular accumulations in close vicinity to, or even infiltrating, remodeled lung tissue. Similarly, we found significant accumulations of B cells interfused with T cells within remodeled lung tissue in two murine models of adenoviral TGF-ß1 or bleomycin (BLM)-induced lung fibrosis. Such B cell accumulations coincided with significantly increased lung collagen deposition, lung histopathology, and worsened lung function in wild-type (WT) mice. Surprisingly, B cell-deficient µMT knockout mice exhibited similar lung tissue remodeling and worsened lung function upon either AdTGF-ß1 or BLM as for WT mice. Comparative transcriptomic profiling of sorted B cells collected from lungs of AdTGF-ß1- and BLM-exposed WT mice identified a large set of commonly regulated genes, but with significant enrichment observed for Gene Ontology terms apparently not related to lung fibrogenesis. Collectively, although we observed B cell accumulations in lungs of IPF patients as well as two experimental models of lung fibrosis, comparative profiling of characteristic features of lung fibrosis between WT and B cell-deficient mice did not support a major involvement of B cells in lung fibrogenesis in mice.

Role of matrix metalloprotease-2 and MMP-9 in experimental lung fibrosis in mice.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a diffuse parenchymal lung disease characterized by exuberant deposition of extracellular matrix (ECM) proteins in the lung interstitium, which contributes to substantial morbidity and mortality in IPF patients. Matrix metalloproteinases (MMPs) are a large family of zinc-dependent endopeptidases, many of which have been implicated in the regulation of ECM degradation in lung fibrosis. However, the roles of MMP-2 and -9 (also termed gelatinases A and B) have not yet been explored in lung fibrosis in detail. METHODS: AdTGF-ß1 was applied via orotracheal routes to the lungs of WT, MMP-2 KO, MMP-9 KO and MMP-2/-9 dKO mice on day 0 to induce lung fibrosis. Using hydroxyproline assay, FlexiVent based lung function measurement, histopathology, western blot and ELISA techniques, we analyzed MMP-2 and MMP-9 levels in BAL fluid and lung, collagen contents in lung and lung function in mice on day 14 and 21 post-treatment. RESULT: IPF lung homogenates exhibited significantly increased levels of MMP-2 and MMP-9, relative to disease controls. Enzymatically active MMP-2 and MMP-9 was increased in lungs of mice exposed to adenoviral TGF-ß1, suggesting a role for these metalloproteinases in lung fibrogenesis. However, we found that neither MMP-2 or MMP-9 nor combined MMP-2/-9 deletion had any effect on experimental lung fibrosis in mice. CONCLUSION: Together, our data strongly suggest that both gelatinases MMP-2 and MMP-9 play only a subordinate role in experimental lung fibrosis in mice.

Regulatory T Cells Limit Pneumococcus-Induced Exacerbation of Lung Fibrosis in Mice.

Patients with idiopathic pulmonary fibrosis (IPF) can experience life-threatening episodes of acute worsening of their disease, termed acute exacerbation of IPF, which may be caused by bacterial and/or viral infections. The potential for regulatory T cells (Tregs) to limit disease progression in bacterially triggered fibrosis exacerbation has not been explored so far. In the current study, we show that the number of Tregs was significantly increased in mice with established AdTGF-ß1-induced lung fibrosis and further increased in mice with pneumococcal infection-induced lung fibrosis exacerbation. Diphtheria toxin-induced depletion of Tregs significantly worsened infection-induced fibrosis exacerbation as determined by increased lung collagen deposition, lung histology, and elevated pulmonary Th1/Th2 cytokine levels. Conversely, IL-2 complex-induced Treg expansion in wild-type mice with established lung fibrosis completely inhibited pneumococcal infection-induced fibrosis exacerbation as efficaciously as antibiotic treatment while preserving lung antibacterial immunity in mice. Collectively, these findings demonstrate the efficacy of Tregs as "silencers," suppressing infection-induced exacerbation of lung fibrosis in mice, and their expansion may offer a novel adjunctive treatment to limit acute exacerbations in patients with IPF.

Role of the COX2-PGE2 axis in S. pneumoniae-induced exacerbation of experimental fibrosis.

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease (ILD) associated with high morbidity and mortality. Patients with ILD frequently develop an acute exacerbation of their disease, which may be triggered by viral and/or bacterial infections. Prostaglandin E2 (PGE2) is an eicosanoid released in a cyclooxygenase-2 (COX2)-dependent manner and is considered to contribute to regulation of lung fibrosis. However, its role in infection-induced exacerbation of lung fibrosis is poorly defined. We found significantly increased levels of PGE2 in lung tissue of patients with ILD. Increased levels of PGE2 were also found in lung tissue of mice with AdTGF-ß1-induced lung fibrosis and even more so in Streptococcus pneumoniae exacerbated lung fibrosis. Type II alveolar epithelial cells (AT II cells) and alveolar macrophages (AM) contributed to PGE2 release during exacerbating fibrosis. Application of parecoxib to inhibit PGE2 synthesis ameliorated lung fibrosis, whereas intratracheal application of PGE2 worsened lung fibrosis in mice. Both interventions had no effect on S. pneumoniae-exacerbated lung fibrosis. Together, we found that the COX2-PGE2 axis has dual roles in fibrosis that may offset each other: PGE2 helps resolve infection/attenuate inflammation in fibrosis exacerbation but accentuates TGF-ß/AT II cell-mediated fibrosis. These data support the efficacy of COX/PGE2 interventions in the setting of non-exacerbating lung fibrosis.

The importance of interventional timing in the bleomycin model of pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a complex disease of unknown aetiology, which makes drug development challenging. Single administration of bleomycin directly to the lungs of mice is a widely used experimental model for studying pulmonary fibrogenesis and evaluating the effect of therapeutic antifibrotic strategies. The model works by inducing an early inflammatory phase, which transitions into fibrosis after 5-7 days. This initial inflammation makes therapeutic timing crucial. To accurately assess antifibrotic efficacy, the intervention should inhibit fibrosis without impacting early inflammation.Studies published between 2008 and 2019 using the bleomycin model to investigate pulmonary fibrosis were retrieved from PubMed, and study characteristics were analysed. Intervention-based studies were classified as either preventative (starting <7 days after bleomycin installation) or therapeutic (>7 days). In addition, studies were cross-referenced with current major clinical trials to assess the availability of preclinical rationale.A total of 976 publications were evaluated. 726 investigated potential therapies, of which 443 (61.0%) were solely preventative, 166 (22.9%) were solely therapeutic and 105 (14.5%) were both. Of the 443 preventative studies, only 70 (15.8%) characterised inflammation during the model's early inflammatory phase. In the reported 145 IPF clinical trials investigating 93 compounds/combinations, only 25 (26.9%) interventions had any preclinical data on bleomycin available on PubMed.Since 2008, we observed a shift (from <5% to 37.4%) in the number of studies evaluating drugs in the therapeutic setting in the bleomycin model. While this shift is encouraging, further characterisation of early inflammation and appropriate preclinical therapeutic testing are still needed. This will facilitate fruitful drug development in IPF, and more therapeutic strategies for patients with this devastating disease.

Surfactant dysfunction and alveolar collapse are linked with fibrotic septal wall remodeling in the TGF-ß1-induced mouse model of pulmonary fibrosis.

In human idiopathic pulmonary fibrosis (IPF), collapse of distal airspaces occurs in areas of the lung not (yet) remodeled. Mice lungs overexpressing transforming growth factor-ß1 (TGF-ß1) recapitulate this abnormality: surfactant dysfunction results in alveolar collapse preceding fibrosis and loss of alveolar epithelial type II (AE2) cells' apical membrane surface area. Here we examined whether surfactant dysfunction-related alveolar collapse due to TGF-ß1 overexpression is linked to septal wall remodeling and AE2 cell abnormalities. Three and 6 days after gene transfer of TGF-ß1, mice received either intratracheal surfactant (Surf-groups: Curosurf®, 100 mg/kg bodyweight) or 0.9% NaCl (Saline-groups). On days 7 (D7) and 14 (D14), lung mechanics were assessed followed by design-based stereology at light and electron microscopic level to quantify structures. Compared with Saline, Surf showed significantly improved tissue elastance, increased numbers of open alveoli, as well as reduced alveolar size heterogeneity on D7. Deterioration in lung mechanics was highly correlated to the loss of open alveoli. On D14, lung mechanics, number of open alveoli, and alveolar size heterogeneity remained significantly improved in the Surf-group. Volumes of extracellular matrix and collagen fibrils in septal walls were significantly reduced, whereas the apical membrane surface area of AE2 cells was increased in Surf compared with Saline. In remodeled tissue with collapsed alveoli, three-dimensional reconstruction of AE2 cells based on scanning electron microscopy array tomography revealed that AE2 cells were trapped without contact to airspaces in the TGF-ß1 mouse model. Similar observations were made in human IPF. Based on correlation analyses, the number of open alveoli and of alveolar size heterogeneity were highly linked with the loss of apical membrane surface area of AE2 cells and deposition of collagen fibrils in septal walls on D14. In conclusion, surfactant replacement therapy stabilizes alveoli and prevents extracellular matrix deposition in septal walls in the TGF-ß1 model.

Mechanical stress-induced mast cell degranulation activates TGF-ß1 signalling pathway in pulmonary fibrosis.

BACKGROUND: The role of mast cells accumulating in idiopathic pulmonary fibrosis (IPF) lungs is unknown. OBJECTIVES: We investigated the effect of fibrotic extracellular matrix (ECM) on mast cells in experimental and human pulmonary fibrosis. RESULTS: In IPF lungs, mast cell numbers were increased and correlated with disease severity (control vs 60%90% vs 60%90% vs FVC<60%, mean difference=-268.6, 95% CI of difference -441.0 to -96.17, p=0.0007). Plasma tryptase levels were increased in IPF and negatively correlated with FVC (control vs FVC<60%, mean difference=-17.12, 95% CI of difference -30.02 to -4.22, p=0.006: correlation curves R=-0.045, p=0.025). In a transforming growth factor (TGF)-ß1-induced pulmonary fibrosis model, chymase-positive and tryptase-positive mast cells accumulated in fibrotic lung. Lung tissue was decellularised and reseeded with bone marrow or peritoneum-derived mast cells; cells on fibrotic ECM released more TGF-ß1 compared with normal ECM (active TGF-ß1: bone marrow-derived mast cell (BMMC)-DL vs BMMC-TGF-ß1 p=0.0005, peritoneal mast cell (PMC)-DL vs PMC-TGF-ß1 p=0.0003, total TGF-ß1: BMMC-DL vs BMMC-TGF-ß1 p=0.013, PMC-DL vs PMC-TGF-ß1 p=0.001). Mechanical stretch of lungs caused mast cell degranulation; mast cell stabilisers inhibited degranulation (histamine: cont vs doxantrazole p=0.004, ß-hexosaminidase: cont vs doxantrazole, mean difference=1.007, 95% CI of difference 0.2700 to 1.744, p=0.007) and TGF-ß1 activation (pSmad2/Smad2: cont vs dox p=0.006). Cromoglycate attenuated pulmonary fibrosis in rats (collagen: phosphate-buffered saline (PBS) vs cromoglycate p=0.036, fibrotic area: PBS vs cromoglycate p=0.031). CONCLUSION: This study suggests that mast cells may contribute to the progression of pulmonary fibrosis.

The FMS-like tyrosine kinase-3 ligand/lung dendritic cell axis contributes to regulation of pulmonary fibrosis.

RATIONALE: Dendritic cells (DC) accumulate in the lungs of patients with idiopathic lung fibrosis, but their pathogenetic relevance is poorly defined. OBJECTIVES: To assess the role of the FMS-like tyrosine kinase-3 ligand (Flt3L)-lung dendritic cell axis in lung fibrosis. MEASUREMENTS AND MAIN RESULTS: We demonstrate in a model of adenoviral gene transfer of active TGF-ß1 that established lung fibrosis was accompanied by elevated serum Flt3L levels and subsequent accumulation of CD11bpos DC in the lungs of mice. Patients with idiopathic pulmonary fibrosis also demonstrated increased levels of Flt3L protein in serum and lung tissue and accumulation of lung DC in explant subpleural lung tissue specimen. Mice lacking Flt3L showed significantly reduced lung DC along with worsened lung fibrosis and reduced lung function relative to wild-type (WT) mice, which could be inhibited by administration of recombinant Flt3L. Moreover, therapeutic Flt3L increased numbers of CD11bpos DC and improved lung fibrosis in WT mice exposed to AdTGF-ß1. In this line, RNA-sequencing analysis of CD11bpos DC revealed significantly enriched differentially expressed genes within extracellular matrix degrading enzyme and matrix metalloprotease gene clusters. In contrast, the CD103pos DC subset did not appear to be involved in pulmonary fibrogenesis. CONCLUSIONS: We show that Flt3L protein and numbers of lung DC are upregulated in mice and humans during pulmonary fibrogenesis, and increased mobilisation of lung CD11bpos DC limits the severity of lung fibrosis in mice. The current study helps to inform the development of DC-based immunotherapy as a novel intervention against lung fibrosis in humans.

Lysyl Oxidase-Like 1 Protein Deficiency Protects Mice from Adenoviral Transforming Growth Factor-ß1-induced Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease characterized by excessive deposition of extracellular matrix (ECM) in the lung parenchyma. The abnormal ECM deposition slowly overtakes normal lung tissue, disturbing gas exchange and leading to respiratory failure and death. ECM cross-linking and subsequent stiffening is thought to be a major contributor of disease progression and also promotes the activation of transforming growth factor (TGF)-ß1, one of the main profibrotic growth factors. Lysyl oxidase-like (LOXL) 1 belongs to the cross-linking enzyme family and has been shown to be up-regulated in active fibrotic regions of bleomycin-treated mice and patients with IPF. We demonstrate in this study that LOXL1-deficient mice are protected from experimental lung fibrosis induced by overexpression of TGF-ß1 using adenoviral (Ad) gene transfer (AdTGF-ß1). The lack of LOXL1 prevented accumulation of insoluble cross-linked collagen in the lungs, and therefore limited lung stiffness after AdTGF-ß1. In addition, we applied mechanical stretch to lung slices from LOXL1+/+ and LOXL1-/- mice treated with AdTGF-ß1. Lung stiffness (Young's modulus) of LOXL1-/- lung slices was significantly lower compared with LOXL1+/+ lung slices. Moreover, the release of activated TGF-ß1 after mechanical stretch was significantly lower in LOXL1-/- mice compared with LOXL1+/+ mice after AdTGF-ß1. These data support the concept that cross-linking enzyme inhibition represents an interesting therapeutic target for drug development in IPF.

Macitentan reduces progression of TGF-ß1-induced pulmonary fibrosis and pulmonary hypertension.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with an unknown cause. Two drugs, nintedanib and pirfenidone, have been shown to slow, but not stop, disease progression. Pulmonary hypertension (PH) is a frequent complication in IPF patients and is associated with poor prognosis. Macitentan is a dual endothelin receptor antagonist that is approved for pulmonary arterial hypertension treatment. We hypothesised that using macitentan to treat animals with pulmonary fibrosis induced by adenoviral vector encoding biologically active transforming growth factor-ß1 (AdTGF-ß1) would improve the PH caused by chronic lung disease and would limit the progression of fibrosis.Rats (Sprague Dawley) which received AdTGF-ß1 were treated by daily gavage of macitentan (100 mg·kg-1·day-1), pirfenidone (0.5% food admix) or a combination from day 14 to day 28. Pulmonary artery pressure (PAP) was measured before the rats were killed, and fibrosis was subsequently evaluated by morphometric measurements and hydroxyproline analysis.AdTGF-ß1 induced pulmonary fibrosis associated with significant PH. Macitentan reduced the increase in PAP and both macitentan and pirfenidone stopped fibrosis progression from day 14 to day 28. Macitentan protected endothelial cells from myofibroblast differentiation and apoptosis whereas pirfenidone only protected against fibroblast-to-myofibroblast differentiation. Both drugs induced apoptosis of differentiated myofibroblasts in vitro and in vivoOur results demonstrate that dual endothelin receptor antagonism was effective in both PH and lung fibrosis whereas pirfenidone only affected fibrosis.

Fibroblast growth factor-1 attenuates TGF-ß1-induced lung fibrosis.

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive fibroblast and myofibroblast proliferation, and extensive deposition of extracellular matrix (ECM). Fibroblast growth factor-1 (FGF-1) belongs to the FGF family and has been shown to inhibit fibroblast collagen production and differentiation into myofibroblasts, and revert epithelial-mesenchymal transition by inhibiting TGF-ß1 signalling pathways. However, the precise role of FGF-1 in pulmonary fibrosis has not yet been elucidated. In this study, we explore the mechanisms underlying the anti-fibrogenic effect of FGF-1 in pulmonary fibrosis in vitro and in vivo by prolonged transient overexpression of FGF-1 (AdFGF-1) and TGF-ß1 (AdTGF-ß1) using adenoviral vectors. In vivo, FGF-1 overexpression markedly attenuated TGF-ß1-induced pulmonary fibrosis in rat lungs when given both concomitantly, or delayed, by enhancing proliferation and hyperplasia of alveolar epithelial cells (AECs). AdFGF-1 also attenuated the TGF-ß1 signalling pathway and induced FGFR1 expression in AECs. In vitro, AdFGF-1 prevented the increase in α-SMA and the decrease in E-cadherin induced by AdTGF-ß1 in normal human lung fibroblasts, primary human pulmonary AECs, and A549 cells. Concomitantly, AdTGF-ß1-induced Smad2 phosphorylation was significantly reduced by AdFGF-1 in both cell types. AdFGF-1 also attenuated the increase in TGFßR1 protein and mRNA levels in fibroblasts. In AECs, AdFGF-1 decreased TGFßR1 protein by favouring TGFßR1 degradation through the caveolin-1/proteasome pathway. Furthermore, FGFR1 expression was increased in AECs, whereas it was decreased in fibroblasts. In serum of IPF patients, FGF-1 levels were increased compared to controls. Interestingly, FGF-1 expression was restricted to areas of AEC hyperplasia, but not α-SMA-positive areas in IPF lung tissue. Our results demonstrate that FGF-1 may have preventative and therapeutic effects on TGF-ß1-driven pulmonary fibrosis via inhibiting myofibroblast differentiation, inducing AEC proliferation, regulating TGF-ß1 signalling by controlling TGFßR1 expression and degradation, and regulating FGFR1 expression. Thus, modulating FGF-1 signalling represents a potential therapy for the treatment of pulmonary fibrosis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Stretch-induced Activation of Transforming Growth Factor-ß1 in Pulmonary Fibrosis.

RATIONALE: Recent findings suggesting transforming growth factor (TGF)-ß1 activation by mechanical stimuli in vitro raised the question of whether this phenomenon was relevant in vivo in the context of pulmonary fibrosis. OBJECTIVES: To explore the effect of mechanical stress on TGF-ß1 activation and its signaling pathway in rat and human fibrotic lung tissue using a novel ex vivo model. METHODS: Rat lung fibrosis was induced using transient gene expression of active TGF-ß1. Lungs were harvested at Day 14 or 21 and submitted to various stimuli in a tissue bath equipped with a force transducer and servo-controlled arm. MEASUREMENTS AND MAIN RESULTS: Fibrotic lung strips responded to tensile force by releasing active TGF-ß1 from latent stores with subsequent increase in tissue phospho-Smad2/3. In contrast, measurable active TGF-ß1 and phospho-Smad2/3 were not induced by mechanical stress in nonfibrotic lungs. Protease inhibition did not affect the release of active TGF-ß1. A TGF-ß1 receptor inhibitor, Rho-associated protein kinase inhibitor, and αv integrin inhibitor all attenuated mechanical stretch-induced phospho-Smad2/3 in fibrotic lung strips. Furthermore, the induction of phospho-Smad2/3 was enhanced in whole fibrotic rat lungs undergoing ventilation pressure challenge compared with control lungs. Last, tissue slices from human lung with usual interstitial pneumonia submitted to mechanical force showed an increase in TGF-ß1 activation and induction of phospho-Smad2/3 in contrast with human nonfibrotic lungs. CONCLUSIONS: Mechanical tissue stretch contributes to the development of pulmonary fibrosis via mechanotransduced activation of TGF-ß1 in rodent and human pulmonary fibrosis.

Surfactant dysfunction during overexpression of TGF-ß1 precedes profibrotic lung remodeling in vivo.

Transforming growth factor-ß1 (TGF-ß1) is involved in regulation of cellular proliferation, differentiation, and fibrogenesis, inducing myofibroblast migration and increasing extracellular matrix synthesis. Here, TGF-ß1 effects on pulmonary structure and function were analyzed. Adenovirus-mediated gene transfer of TGF-ß1 in mice lungs was performed and evaluated by design-based stereology, invasive pulmonary function testing, and detailed analyses of the surfactant system 1 and 2 wk after gene transfer. After 1 wk decreased static compliance was linked with a dramatic alveolar derecruitment without edema formation or increase in the volume of septal wall tissue or collagen fibrils. Abnormally high surface tension correlated with downregulation of surfactant proteins B and C. TTF-1 expression was reduced, and, using PLA (proximity ligand assay) technology, we found Smad3 and TTF-1 forming complexes in vivo, which are normally translocated into the nucleus of the alveolar epithelial type II cells (AE2C) but in the presence of TGF-ß1 remain in the cytoplasm. AE2C show altered morphology, resulting in loss of total apical surface area per lung and polarity. These changes of AE2C were progressive 2 wk after gene transfer and correlated with lung compliance. Although static lung compliance remained low, the volume of septal wall tissue and collagen fibrils increased 2 wk after gene transfer. In this animal model, the primary effect of TGF-ß1 signaling in the lung is downregulation of surfactant proteins, high surface tension, alveolar derecruitment, and mechanical stress, which precede fibrotic tissue remodeling and progressive loss of AE2C polarity. Initial TTF-1 dysfunction is potentially linked to downregulation of surfactant proteins.

A novel profibrotic mechanism mediated by TGFß-stimulated collagen prolyl hydroxylase expression in fibrotic lung mesenchymal cells.

Idiopathic pulmonary fibrosis is a severe chronic lung disease with a high mortality rate. Excessive TGFß signalling is recognized as a central player in lung fibrosis. However, the related mechanisms remain unclear. Herein we used a novel Tbx4 lung enhancer-driven Tet-On transgenic system to inhibit TGFß signalling in mouse lung-resident mesenchymal cells at different stages of bleomycin-induced fibrosis, by conditionally knocking out TGFß receptor II or expressing a dominant-negative TGFß receptor II. Abrogation of mesenchymal TGFß signalling markedly attenuated bleomycin-induced fibrotic pathology, which was independent of altered early inflammation. Furthermore, a novel TGFß downstream target gene P4HA3 (an α-subunit of collagen prolyl hydroxylase) was identified, and its expression was significantly increased in fibroblastic foci of both bleomycin-induced fibrotic mouse lungs and idiopathic pulmonary fibrosis patients' lungs. The relationship between activated TGFß signalling, up-regulation of P4HA3 and increased hydroxyproline/collagen production was further verified in cultured lung fibroblasts. Moreover, inhibition of collagen prolyl hydroxylase by pyridine-2,5-dicarboxylate attenuated TGFß-stimulated collagen production in both cultured fibroblasts and bleomycin-induced mouse lung fibrosis. These data indicate that increased expression and activity of collagen prolyl hydroxylase is one of the important mechanisms underlying TGFß-mediated profibrotic effects. Inhibition of collagen prolyl hydroxylase may be a new, promising approach for preventing and treating pulmonary fibrosis.

Modulation of pulmonary fibrosis by IL-13Rα2.

Pulmonary fibrosis is a progressive and fatal disease that involves the remodeling of the distal airspace and the lung parenchyma, which results in compromised gas exchange. The median survival time once diagnosed is less than three years. Interleukin (IL)-13 has been shown to play a role in a number of inflammatory and fibrotic diseases. IL-13 modulates its effector functions via a complex receptor system that includes the IL-4 receptor (R) α, IL-13Rα1, and the IL-13Rα2. IL-13Rα1 binds IL-13 with low affinity, yet, when it forms a complex with IL-4α, it binds with much higher affinity, inducing the effector functions of IL-13. IL-13Rα2 binds IL-13 with high affinity but has a short cytoplasmic tail and has been shown to act as a nonsignaling decoy receptor. Transfection of fibroblasts and epithelial cells with IL-13Rα2 inhibited the IL-13 induction of soluble collagen, TGF-ß, and CCL17. Adenoviral overexpression of IL-13Rα2 in the lung reduced bleomycin-induced fibrosis. Our work shows that overexpression of IL-13Rα2 inhibits the IL-13 induction of fibrotic markers in vitro and inhibits bleomycin-induced pulmonary fibrosis. In summary our study highlights the antifibrotic nature of IL-13Ra2.

Streptococcus pneumoniae triggers progression of pulmonary fibrosis through pneumolysin.

RATIONALE: Respiratory tract infections are common in patients suffering from pulmonary fibrosis. The interplay between bacterial infection and fibrosis is characterised poorly. OBJECTIVES: To assess the effect of Gram-positive bacterial infection on fibrosis exacerbation in mice. METHODS: Fibrosis progression in response to Streptococcus pneumoniae was examined in two different mouse models of pulmonary fibrosis. MEASUREMENTS AND MAIN RESULTS: We demonstrate that wild-type mice exposed to adenoviral vector delivery of active transforming growth factor-ß1 (TGFß1) or diphteria toxin (DT) treatment of transgenic mice expressing the DT receptor (DTR) under control of the surfactant protein C (SPC) promoter (SPC-DTR) to induce pulmonary fibrosis developed progressive fibrosis following infection with Spn, without exhibiting impaired lung protective immunity against Spn. Antibiotic treatment abolished infection-induced fibrosis progression. The cytotoxin pneumolysin (Ply) of Spn caused this phenomenon in a TLR4-independent manner, as Spn lacking Ply (SpnΔply) failed to trigger progressive fibrogenesis, whereas purified recombinant Ply did. Progressive fibrogenesis was also observed in AdTGFß1-exposed Ply-challenged TLR4 KO mice. Increased apoptotic cell death of alveolar epithelial cells along with an attenuated intrapulmonary release of antifibrogenic prostaglandin E2 was found to underlie progressive fibrogenesis in Ply-challenged AdTGFß1-exposed mice. Importantly, vaccination of mice with the non-cytotoxic Ply derivative B (PdB) substantially attenuated Ply-induced progression of lung fibrosis in AdTGFß1-exposed mice. CONCLUSIONS: Our data unravel a novel mechanism by which infection with Spn through Ply release induces progression of established lung fibrosis, which can be attenuated by protein-based vaccination of mice.

The small heat-shock protein αB-crystallin is essential for the nuclear localization of Smad4: impact on pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by the proliferation of myofibroblasts and the accumulation of extracellular matrix (ECM) in the lungs. TGF-ß1 is the major profibrotic cytokine involved in IPF and is responsible for myofibroblast proliferation and differentiation and ECM synthesis. αB-crystallin is constitutively expressed in the lungs and is inducible by stress, acts as a chaperone and is known to play a role in cell cytoskeleton architecture homeostasis. The role of αB-crystallin in fibrogenesis remains unknown. The principal signalling pathway involved in this process is the Smad-dependent pathway. We demonstrate here that αB-crystallin is strongly expressed in fibrotic lung tissue from IPF patients and in vivo rodent models of pulmonary fibrosis. We also show that αB-crystallin-deficient mice are protected from bleomycin-induced fibrosis. Similar protection from fibrosis was observed in αB-crystallin KO mice after transient adenoviral-mediated over-expression of IL-1ß or TGF-ß1. We show in vitro in primary epithelial cells and fibroblasts that αB-crystallin increases the nuclear localization of Smad4, thereby enhancing the TGF-ß1-Smad pathway and the consequent activation of TGF-ß1 downstream genes. αB-crystallin over-expression disrupts Smad4 mono-ubiquitination by interacting with its E3-ubiquitin ligase, TIF1γ, thus limiting its nuclear export. Conversely, in the absence of αB-crystallin, TIF1γ can freely interact with Smad4. Consequently, Smad4 mono-ubiquitination and nuclear export are favoured and thus TGF-ß1-Smad4 pro-fibrotic activity is inhibited. This study demonstrates that αB-crystallin may be a key target for the development of specific drugs in the treatment of IPF or other fibrotic diseases.

Inflammation induced by MMP-9 enhances tumor regression of experimental breast cancer.

Matrix metalloproteinases (MMPs) have been suggested as therapeutic targets in cancer treatment, but broad-spectrum MMP inhibitors have failed in clinical trials. Recent data suggest that several MMPs including MMP-9 exert both pro- and antitumorigenic properties. This is also the case of the natural inhibitors of MMPs, tissue inhibitor of metalloproteinases (TIMPs). The inhibitor of MMP-9 is TIMP-1, and high levels of this enzyme have been associated with decreased survival in breast cancer. Inflammation is one hallmark of cancer progression, and MMPs/TIMPs may be involved in the local immune regulation. We investigated the role of MMP-9/TIMP-1 in regulating innate antitumor immunity in breast cancer. Breast cancers were established in nude mice and treated with intratumoral injections of adenoviruses carrying the human TIMP-1 or MMP-9 gene (AdMMP-9). In vivo microdialysis for sampling of cancer cell-derived (human) and stroma-derived (murine) proteins, immunostainings, as well as cell cultures were performed. We report a dose-dependent decrease of tumor growth and angiogenesis after AdMMP-9 treatment. In addition to increased generation of endostatin, AdMMP-9 promoted an antitumor immune response by inducing massive neutrophil infiltration. Neutrophil depletion prior to gene transfer abolished the therapeutic effects of AdMMP-9. Additionally, AdMMP-9 activated tumor-infiltrating macrophages into a tumor-inhibiting phenotype both in vivo and in vitro. AdMMP-9 also inhibited tumor growth in immune-competent mice bearing breast cancers. Adenoviruses carrying the human TIMP-1 gene had no effect on tumor growth or the immune response. Our novel data identify MMP-9 as a potent player in modulating the innate immune response into antitumor activities.

Matrix metalloproteinase-19 promotes metastatic behavior in vitro and is associated with increased mortality in non-small cell lung cancer.

RATIONALE: Lung cancer is the leading cause of cancer death in both men and women in the United States and worldwide. Matrix metalloproteinases (MMPs) have been implicated in the development and progression of lung cancer, but their role in the molecular pathogenesis of lung cancer remains unclear. We have found that MMP19, a relatively novel member of the MMP family, is overexpressed in lung tumors when compared with control subjects. OBJECTIVES: To test the hypothesis that MMP19 plays a significant role in the development and progression of non-small cell lung cancer (NSCLC). METHODS: We have analyzed lung cancer gene expression data, immunostained lung tumors for MMP19, and performed in vitro assays to test the effects of MMP19 in NSCLC cells. MEASUREMENTS AND MAIN RESULTS: We found that MMP19 gene and protein expression is increased in lung cancer tumors compared with adjacent and histologically normal lung tissues. In three independent datasets, increased MMP19 gene expression conferred a poorer prognosis in NSCLC. In vitro, we found that overexpression of MMP19 promotes epithelial-mesenchymal transition, migration, and invasiveness in multiple NSCLC cell lines. Overexpression of MMP19 with a mutation at the catalytic site did not impair epithelial-mesenchymal transition or expression of prometastasis genes. We also found that miR-30 isoforms, a microRNA family predicted to target MMP19, is markedly down-regulated in human lung cancer and regulates MMP19 expression. CONCLUSIONS: Taken together, these findings suggest that MMP19 is associated with the development and progression of NSCLC and may be a potential biomarker of disease severity and outcome.

Inhibition of HSP27 blocks fibrosis development and EMT features by promoting Snail degradation.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by myofibroblast proliferation. Transition of epithelial/mesothelial cells into myofibroblasts [epithelial-to-mesenchymal transition (EMT)] occurs under the influence of transforming growth factor (TGF)-ß1, with Snail being a major transcription factor. We study here the role of the heat-shock protein HSP27 in fibrogenesis and EMT. In vitro, we have up- and down-modulated HSP27 expression in mesothelial and epithelial cell lines and studied the expression of different EMT markers induced by TGF-ß1. In vivo, we inhibited HSP27 with the antisense oligonucleotide OGX-427 (in phase II clinical trials as anticancer agent) in our rat subpleural/pulmonary fibrosis models. We demonstrate that HSP27 is strongly expressed during the fibrotic process in patients with IPF and in different in vivo models. We showed that HSP27 binds to and stabilizes Snail and consequently induces EMT. Conversely, HSP27 knockdown leads to Snail proteasomal degradation, thus inhibiting TGF-ß1-induced EMT. Inhibition of HSP27 with OGX-427 efficiently blocks EMT and fibrosis development. Controls in vivo were an empty adenovirus that did not induce fibrosis and a control antisense oligonucleotide. The present work opens the possibility of a new therapeutic use for HSP27 inhibitors against IPF, for which there is no conclusively effective treatment.