Interstitial fibrosis and growth factors

Plumbagin attenuates Bleomycin-induced lung fibrosis in mice

Background

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease with limited treatment options. Plumbagin (PL) is an herbal extract with diverse pharmacological effects that have been recently used to treat various types of cancer. This study aims to explore the anti-fibrotic effect of PL and possible underlying mechanisms in IPF.

Methods

We used a bleomycin-induced experimental mouse model of lung fibrosis to assess the potential anti-fibrotic effect of PL. Histological analysis of lung tissue samples by H&E and Masson’s trichrome staining and hydroxyproline assay was performed to evaluate the fibrotic alterations. ELISA and real-time quantitative PCR were conducted to determine the amount of tumor necrosis factor-alpha (TNFα), tumor growth factor-beta (TGF-β), connective tissue growth factor (CTGF), and endothelin-1 (ET-1).

Results

Bleomycin exposure induced lung fibrosis, which was indicated by inflammation, collagen deposition, and structural damage. PL remarkably prevented bleomycin-induced lung fibrosis. Furthermore, PL significantly inhibited TNF-α and TGF-β production. PL also diminished the upregulated expression of CTGF and ET-1 induced by bleomycin.

Conclusion

Overall, our findings suggest PL as an anti-fibrotic agent acting via down-regulation of TGF-β/CTGF or ET-1 axis, as well as TNF-α, to improve lung fibrosis.

Nintedanib-Containing Dual Conjugates Targeting αVβ6 Integrin and Tyrosine Kinase Receptors as Potential Antifibrotic Agents

αVβ6 Integrin plays a fundamental role in the activation of transforming growth factor-β (TGF-β), the major profibrotic mediator; for this reason, αVβ6 ligands have recently been forwarded to clinical phases for the therapy of fibrotic diseases. Herein, we report the synthesis and in vitro biological evaluation as antifibrotic agents of three new covalent conjugates, constituted by c(AmpLRGDL), an αVβ6 integrin-recognizing small cyclopeptide, and nintedanib, a tyrosine kinase inhibitor approved for idiopathic pulmonary fibrosis (IPF) treatment. One of these conjugates recapitulates optimal in vitro antifibrotic properties of the two active units. The integrin ligand portion within the conjugate plays a role in inhibiting profibrotic stimuli, potentiating the nintedanib effect and favoring the selective uptake of the conjugate in cells overexpressing αVβ6 integrin. These results may open a new perspective on the development of dual conjugates in the targeted therapy of IPF.

Proteomic analysis of serum samples of paracoccidioidomycosis patients with severe pulmonary sequel

Background

Pulmonary sequelae (PS) in patients with chronic paracoccidioidomycosis (PCM) typically include pulmonary fibrosis and emphysema. Knowledge of the molecular pathways involved in PS of PCM is required for treatment and biomarker identification.

Methodology/Principal findings

This non-concurrent cohort study included 29 patients with pulmonary PCM that were followed before and after treatment. From this group, 17 patients evolved to mild/ moderate PS and 12 evolved severe PS. Sera from patients were evaluated before treatment and at clinical cure, serological cure, and apparent cure. A nanoACQUITY UPLC-Xevo QT MS system and PLGS software were used to identify serum differentially expressed proteins, data are available via ProteomeXchange with identifier PXD026906. Serum differentially expressed proteins were then categorized using Cytoscape software and the Reactome pathway database. Seventy-two differentially expressed serum proteins were identified in patients with severe PS compared with patients with mild/moderate PS. Most proteins altered in severe PS were involved in wound healing, inflammatory response, and oxygen transport pathways. Before treatment and at clinical cure, signaling proteins participating in wound healing, complement cascade, cholesterol transport and retinoid metabolism pathways were downregulated in patients with severe PS, whereas signaling proteins in gluconeogenesis and gas exchange pathways were upregulated. At serological cure, the pattern of protein expression reversed. At apparent cure pathways related with tissue repair (fibrosis) became downregulated, and pathway related oxygen transport became upregulated. Additionally, we identified 15 proteins as candidate biomarkers for severe PS.

Conclusions/Significance

Development of severe PS is related to increased expression of proteins involved in glycolytic pathway and oxygen exchange), indicative of the greater cellular activity and replication associated with early dysregulation of wound healing and aberrant tissue repair. Our findings provide new targets to study mechanisms of PS in PCM, as well as potential biomarkers.

Pulmonary fibrosis is the main sequel of paracoccidioidomycosis (PCM), a fungal disease that affects mainly men, rural workers. The development of pulmonary fibrosis is complex and involves several mechanisms that culminate in aberrant collagen production and deposition in the lungs making it became stiff and blocking the air passages. These changes lead to difficulty in breathing and in PCM patients dyspnea in response to high or low levels of exertion is common. Therefore, these patients show incapacity to work and the decreased quality of life. With the possibility of identifying some marker, for example, it could help the indication of respiratory physiotherapy, professional rehabilitation, or therapeutic intervention. This is the first study to examine the pulmonary sequelae (PS) in patients with paracoccidioidomycosis using an approach combining proteomics with bioinformatics. Here, we identify the specific proteome pattern found in PCM patients with severe sequelae that distinguishes these patients from that with mild/moderate sequelae. Our results showed that time points immediately before treatment and at clinical cure are key moments at which PS can progress to severe PS due a dysregulation in wound healing with consequent delayed in the healing processes resulting in an aberrant scar. As such, we suggest that the prognoses for severe PS should be considered as soon as possible and as early as diagnosis of PCM. Furthermore, we used proteomics to identify possible serum biomarkers with which to predict the likely development of severe PS, to be validated in future studies.

Efficacy of Water-Soluble Pearl Powder Components Extracted by a CO2 Supercritical Extraction System in Promoting Wound Healing

Pearl powder is a biologically active substance that is widely used in traditional medicine, skin repair and maintenance. The traditional industrial extraction processes of pearl powder are mainly based on water, acid or enzyme extraction methods, all of which have their own drawbacks. In this study, we propose a new extraction process for these active ingredients, specifically, water-soluble components of pearl powder extracted by a CO2 supercritical extraction system (SFE), followed by the extraction efficiency evaluation. A wound-healing activity was evaluated in vitro and in vivo. This demonstrated that the supercritical extraction technique showed high efficiency as measured by the total protein percentage. The extracts exhibited cell proliferation and migration-promoting activity, in addition to improving collagen formation and healing efficiency in vivo. In brief, this study proposes a novel extraction process for pearl powder, and the extracts were also explored for wound-healing bioactivity, demonstrating the potential in wound healing.

Air Pollution-An Overlooked Risk Factor for Idiopathic Pulmonary Fibrosis

Air pollution is a major environmental risk to health and a global public health concern. In 2016, according to the World Health Organization (WHO), ambient air pollution in cities and rural areas was estimated to cause 4.2 million premature deaths. It is estimated that around 91% of the world’s population lives in places where air pollution exceeds the limits recommended by the WHO. Sources of air pollution are multiple and context-specific. Air pollution exposures are established risk factors for development and adverse health outcomes in many respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), or lung cancer. However, possible associations between air pollution and idiopathic pulmonary fibrosis (IPF) have not been adequately studied and air pollution seems to be an underrecognized risk factor for IPF. This narrative review describes potential mechanisms triggered by ambient air pollution and their possible roles in the initiation of the pathogenic process and adverse health effects in IPF. Additionally, we summarize the most current research evidence from the clinical studies supporting links between air pollution and IPF.

Exosomes: From Potential Culprits to New Therapeutic Promise in the Setting of Cardiac Fibrosis

Fibrosis is a significant global health problem associated with many inflammatory and degenerative diseases affecting multiple organs, individually or simultaneously. Fibrosis develops when extracellular matrix (ECM) remodeling becomes excessive or uncontrolled and is associated with nearly all forms of heart disease. Cardiac fibroblasts and myofibroblasts are the main effectors of ECM deposition and scar formation. The heart is a complex multicellular organ, where the various resident cell types communicate between themselves and with cells of the blood and immune systems. Exosomes, which are small extracellular vesicles, (EVs), contribute to cell-to-cell communication and their pathophysiological relevance and therapeutic potential is emerging. Here, we will critically review the role of endogenous exosomes as possible fibrosis mediators and discuss the possibility of using stem cell-derived and/or engineered exosomes as anti-fibrotic agents.

Transforming growth factor beta induces fibroblasts to express and release the immunomodulatory protein PD-L1 into extracellular vesicles

Transforming growth factor-beta (TGFβ) is an enigmatic protein with various roles in healthy tissue homeostasis/development as well as the development or progression of cancer, wound healing, fibrotic disorders, and immune modulation, to name a few. As TGFβ is causal to various fibroproliferative disorders featuring localized or systemic tissue/organ fibrosis as well as the activated stroma observed in various malignancies, characterizing the pathways and players mediating its action is fundamental. In the current study, we found that TGFβ induces the expression of the immunoinhibitory molecule Programed death-ligand 1 (PD-L1) in human and murine fibroblasts in a Smad2/3- and YAP/TAZ-dependent manner. Furthermore, PD-L1 knockdown decreased the TGFβ-dependent induction of extracellular matrix proteins, including collagen Iα1 (colIα1) and alpha-smooth muscle actin (α-SMA), and cell migration/wound healing. In addition to an endogenous role for PD-L1 in profibrotic TGFβ signaling, TGFβ stimulated-human lung fibroblast-derived PD-L1 into extracellular vesicles (EVs) capable of inhibiting T cell proliferation in response to T cell receptor stimulation and mediating fibroblast cell migration. These findings provide new insights and potential targets for a variety of fibrotic and malignant diseases.

Gastric Acid and Pepsin Work Together in Simulated Gastric Acid Inhalation Leading to Pulmonary Fibrosis in Rats

Background

The clinical association between gastroesophageal reflux disease (GERD) and idiopathic pulmonary fibrosis (IPF) has been known for many years, but it is still unclear. The present study investigated the association between experimentally simulated aspiration and pulmonary fibrosis.

Material/Methods

A total of 120 male Sprague-Dawley rats were randomly divided into a negative control group, a bleomycin group, and 3 simulated aspiration groups. The bleomycin group was administered a one-time intratracheal injection of bleomycin, whereas the 3 simulated aspiration groups were treated either with an intratracheal instillation of gastric fluid combined with pepsin, with pepsin alone, or with hydrochloric acid, all twice a week, and the negative control group was administered normal saline twice a week. Lung tissues were collected to evaluate pathological changes and the mRNA expression levels of connective tissue growth factor (CTGF), type I collagen, and transforming growth factor.

Results

The results demonstrated that the degree of fibrosis in the early stage was low in each of the 3 simulated aspiration groups, but gradually increased over time. The expression levels of the downstream factor of fibrosis, CTGF, and type I collagen also reflected this trend.

Conclusions

The study demonstrates that aspiration of gastric contents can cause pulmonary fibrosis, and mixed aspiration of pepsin and gastric fluid can accelerate this process. This study provides strong evidence in support of a potential association between human GERD and IPF.

TGF-beta signalling in bovine mammary gland involution and a comparative assessment of MAC-T and BME-UV1 cells as in vitro models for its study

The goal of the dairy industry is ultimately to increase lactation persistency, which is the length of time during which peak milk yield is sustained. Lactation persistency is determined by the balance of cell apoptosis and cell proliferation; when the balance is skewed toward the latter, this results in greater persistency. Thus, we can potentially increase milk production in dairy cows through manipulating apoptogenic and antiproliferative cellular signaling that occurs in the bovine mammary gland. Transforming growth factor beta 1 (TGFβ1) is an antiproliferative and apoptogenic cytokine that is upregulated during bovine mammary gland involution. Here, we discuss possible applications of TGFβ1 signaling for the purposes of increasing lactation persistency. We also compare the features of mammary alveolar cells expressing SV-40 large T antigen (MAC-T) and bovine mammary epithelial cells-clone UV1 (BME-UV1) cells, two extensively used bovine mammary epithelial cell lines, to assess their appropriateness for the study of TGFβ1 signaling. TGFβ1 induces apoptosis and arrests cell growth in BME-UV1 cells, and this was reported to involve suppression of the somatotropic axis. Conversely, there is no proof that exogenous TGFβ1 induces apoptosis of MAC-T cells. In addition to TGFβ1's different effects on apoptosis in these cell lines, hormones and growth factors have distinct effects on TGFβ1 secretion and synthesis in MAC-T and BME-UV1 cells as well. MAC-T and BME-UV1 cells may behave differently in response to TGFβ1 due to their contrasting phenotypes; MAC-T cells have a profile indicative of both myoepithelial and luminal populations, while the BME-UV1 cells exclusively contain a luminal-like profile. Depending on the nature of the research question, the use of these cell lines as models to study TGFβ1 signaling should be carefully tailored to the questions asked.

Respiratory Toxicity of Polyhexamethylene Guanidine Phosphate Exposure in Zebrafish

Humidifier disinfectants containing polyhexamethylene guanidine phosphate (PHMG-P) can induce pulmonary toxicity and has caused human casualties in South Korea since 2006. Thereby, the safety evaluation of household chemicals such as PHMG-P has garnered increased importance. However, many limitations, such as the lack of specialized facilities and animal welfare concerns associated with the use of murine models, persist. Zebrafish gills have high functional and structural similarity to mammalian lungs. Moreover, zebrafish are sensitive to toxic substances, resulting in changes in behavioral or ventilatory patterns. Based on these facts, in this study, we aimed to evaluate the pulmonary toxicity of PHMG-P in zebrafish. Zebrafish exposed to PHMG-P showed an increase in mRNA levels of inflammatory factors persisting for 28 days along with histopathologic changes in the gills. An exposure time-dependent alteration in infiltration of inflammatory cells and destruction of gill lamellae was observed. In addition, an increase in mRNA levels of fibrosis factors was observed in gills exposed to PHMG-P for 28 days, as assessed by collagen staining with Masson's trichrome. These results supported the cellular level results. Taken together, our results reveal pulmonary toxic effects of PHMG-P and suggest useful markers for evaluating pulmonary toxicity.

Serum Cytokine in Response to Chemo-Radiotherapy for Hodgkin's Disease

Aims and Background

Mediastinal radiotherapy and multiple-drug chemotherapy, including bleomycin employed in the treatment of Hodgkin's disease, can produce lung toxicity leading to fibrosis. There is increasing evidence of the involvement in the fibrosing process of different cytokines and growth factors such as TNF-alfa, IL-1 beta, TGF-beta and PDGF.

Material and Methods

In a pilot study, we evaluated lung function in 20 patients suffering from Hodgkin's disease, mainly in stage II A, submitted to multiple-drug chemotherapy including bleomycin (ABVD) and mediastinal radiotherapy and correlated its modifications with serum concentration of the cytokines determined by immunoenzymatic assay. Spirometry and transfer lung function for carbon monoxide (DLCO) were performed before, at the end of chemotherapy, at the end of radiotherapy and after a follow-up of 6 and 12 months.

Results

DLCO decreased at the end of the combined treatment and then remained constantly decreased. TNF-alfa, TGF-beta and PDGF-alfa concentrations did not change, whereas IL-1 beta significantly increased after the completion of the combined treatment and after a follow-up of 6–months and then declined to normal values after 12 months. The serum concentration of the cytokine was significantly higher in patients who had a DLCO <75% of predicted after 1 year than in patients with a DLCO >75%.

Conclusions

The results indicate a potential role of IL-1 beta in the pathogenesis of chemoradiotherapy-induced lung toxicity, which needs to be confirmed in a larger patient population.

Effects and mechanisms of pirfenidone, prednisone and acetylcysteine on pulmonary fibrosis in rat idiopathic pulmonary fibrosis models

CONTEXT

Previous studies have reported that caveolin-1 (Cav-1) is associated with lung fibrosis. However, the role of Cav-1 expression in pirfenidone-treated idiopathic pulmonary fibrosis (IPF) is unknown.

OBJECTIVE

This study investigated Cav-1 expression in pirfenidone-treated IPF, and compared the effects of pirfenidone with acetylcysteine and prednisone on IPF.

MATERIALS AND METHODS

Rat IPF model was established by endotracheal injection of 5 mg/kg bleomycin A5 into the specific pathogen-free Wistar male rats. Pirfenidone (P, 100 mg/kg once daily), prednisone (H, 5 mg/kg once daily) and acetylcysteine (N, 4 mg/kg 3 times per day) were used to treat the rat model by intragastric administration for 45 consecutive days, respectively. The normal rats without IPF were used as the controls. After 15, 30 and 45 days of drug treatment, lung histopathology was assessed. The expression of Cav-1 was determined using real-time quantitative PCR and Western blot; the expression of tumour necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor (PDGF) was determined by enzyme-linked immunosorbent assay.

RESULTS

After 15, 30 and 45 days of drug treatment, comparison of the three drug-treated groups with the model group showed significantly lower (p < 0.05) significance of airsacculitis and fibrosis scores of lung tissues, as well as expression of TGF-β1, TNF-α and PDGF, but the expression of Cav-1 was higher (p < 0.05). Compared with the N group, the fibrosis score was significantly lower and the protein expression of Cav-1 was significantly higher in the P group (p < 0.05). Additionally, the expression of Cav-1 was negatively correlated with the airsacculitis and fibrosis scores (r = -0.506, p < 0.01; r = -0.676, p < 0.01) as well as expression of TGF-β1, TNF-α and PDGF (r = -0.590, p < 0.01; r = -0.530, p < 0.01; r = -0.553, p < 0.01).

DISCUSSION AND CONCLUSION

Pirfenidone, prednisone and acetylcysteine can inhibit airsacculitis and pulmonary fibrosis in rat IPF models, which may be related with enhanced caveolin-1, reduced TNF-α, TGF-β1, PDGF.

Identification of novel inhibitors of DDR1 against idiopathic pulmonary fibrosis by integrative transcriptome meta-analysis, computational and experimental screening

Idiopathic pulmonary fibrosis (IPF) is a kind of a chronic and fatal lung disease leading to progressive lung function decline. Although several RNA microarray studies on IPF patients have been reported, their results were merely specific to each study with distinct platforms or sample types. In the current study, an integrative transcriptome meta-analysis of IPF was performed to explore regulated pathways, based on four independent expression profiling microarrays of IPF datasets, including 73 samples from IPF tissues or lung fibroblast cells. The results suggested the discoidin domain receptor 1 (DDR1) and downstream c-Jun N-terminal kinases (JNK) pathway may play important roles in the progression of IPF. To our knowledge, discoidin domain receptor 1 (DDR1) is a kind of receptor tyrosine kinase (RTK) with a unique ability to bind both fibrillar and non-fibrillar collagens. Based on the crystallographic structures of DDR1, the combination of molecular dynamics simulation and a hybrid protocol of a virtual screening method, comprised of PBVS (multicomplex-pharmacophore based virtual screening) and DBVS (docking based virtual screening) methods were used for retrieving novel DDR1 inhibitors from the SPECS database. Twelve hit compounds were selected from the hit compounds and shifted to experimental validations, and the most potent compound was evaluated for its anti-IPF capacity on murine IPF models. Thus, these results may provide valuable information for further discovery of potential lead compounds for IPF therapy.

Time-dependent effects of HJP272, an endothelin receptor antagonist, in bleomycin-induced pulmonary fibrosis

Using a lipopolysaccharide (LPS) model of acute lung injury, we have previously shown that endothelin-1 (ET-1), a potent mediator of vasoconstriction, may act as a "gatekeeper" for the influx of inflammatory cells into the lung. To further investigate the potential of ET-1 to limit the progression of lung injury, hamsters were treated with an endothelin receptor antagonist (ERA), HJP272, either 1 h prior to intratracheal instillation of bleomycin (BLM) or 24 h afterwards. Lung injury and repair were examined by measuring the following parameters: 1) histopathological changes; 2) neutrophil content in bronchoalveolar lavage fluid (BALF); 3) lung collagen content; 4) tumor necrosis factor receptor 1 (TNFR1) expression by BALF macrophages; 5) BALF levels of: a) transforming growth factor beta-1 (TGF-β1), b) stromal cell-derived factor 1 (commonly referred to as CXCL12), and c) platelet-derived growth factor BB (PDGF-BB); 6) alveolar septal cell apoptosis (as measured by the TUNEL assay). For each of these parameters, animals pretreated with HJP272 showed significant reductions compared to those receiving BLM alone. In contrast, post-treatment with HJP272 was either ineffective or produced only marginally significant changes. The efficacy of a single pretreatment with HJP272 prior to induction of lung injury suggests that subsequent features of the disease are determined at a very early stage. This may explain why ERAs are not an effective treatment for human pulmonary fibrosis. Nevertheless, our findings suggest that they may be useful as prophylactic agents when given in combination with drugs that have fibrogenic potential.

Myofibroblast repair mechanisms post-inflammatory response: a fibrotic perspective

INTRODUCTION

Fibrosis is a complex chronic disease characterized by a persistent repair response. Its pathogenesis is poorly understood but it is typically the result of chronic inflammation and maintained with the required activity of transforming growth factor-β (TGFβ) and extracellular matrix (ECM) tension, both of which drive fibroblasts to transition into a myofibroblast phenotype.

FINDINGS

As the effector cells of repair, myofibroblasts migrate to the site of injury to deposit excessive amounts of matrix proteins and stimulate high levels of contraction. Myofibroblast activity is a decisive factor in whether a tissue is properly repaired by controlled wound healing or rendered fibrotic by deregulated repair. Extensive studies have documented the various contributing factors to an abrogated repair response. Though these fibrotic factors are known, very little is understood about the opposing antifibrotic molecules that assist in a successful repair, such as prostaglandin E2 (PGE₂) and ECM retraction. The following review will discuss the general development of fibrosis through the transformation of myofibroblasts, focusing primarily on the prominent profibrotic pathways of TGFβ and ECM tension and antifibrotic pathways of PGE₂ and ECM retraction.

CONCLUSIONS

The idea is to understand the ways in which the cell, after an injury and inflammatory response, normally controls its repair mechanisms through its homeostatic regulators so as to mimic them therapeutically to control abnormal pathways.

Haploinsufficiency of the folliculin gene leads to impaired functions of lung fibroblasts in patients with Birt-Hogg-Dubé syndrome

Birt–Hogg–Dubé syndrome (BHDS) is an autosomal dominant inherited disorder caused by germline mutations in the FLCN gene, and characterized by skin fibrofolliculomas, multiple lung cysts, spontaneous pneumothorax, and renal neoplasms. Pulmonary manifestations frequently develop earlier than other organ involvements, prompting a diagnosis of BHDS. However, the mechanism of lung cyst formation and pathogenesis of pneumothorax have not yet been clarified. Fibroblasts were isolated from lung tissues obtained from patients with BHDS (n = 12) and lung cancer (n = 10) as controls. The functional abilities of these lung fibroblasts were evaluated by the tests for chemotaxis to fibronectin and three‐dimensional (3‐D) gel contraction. Fibroblasts from BHDS patients showed diminished chemotaxis as compared with fibroblasts from controls. Expression of fibronectin and TGF‐β1 was significantly reduced in BHDS fibroblasts when assessed by qPCR. Addition of TGF‐β1 in culture medium of BHDS lung fibroblasts significantly restored these cells' abilities of chemotaxis and gel contraction. Human fetal lung fibroblasts (HFL‐1) exhibited reduced chemotaxis and 3‐D gel contraction when FLCN expression was knocked down. To the contrary, a significant increase in chemotactic activity toward to fibronectin was demonstrated when wild‐type FLCN was overexpressed, whereas transduction of mutant FLCN showed no effect on chemotaxis. Our results suggest that FLCN is associated with chemotaxis in lung fibroblasts. Together with reduced TGF‐β1 expression by BHDS lung fibroblasts, a state of FLCN haploinsufficiency may cause lung fibroblast dysfunction, thereby impairing tissue repair. These may reveal one mechanism of lung cyst formation and pneumothorax in BHDS patients.

miR-877-3p targets Smad7 and is associated with myofibroblast differentiation and bleomycin-induced lung fibrosis

Myofibroblast differentiation of lung resident mesenchymal stem cells (LR-MSC) plays an important role in idiopathic pulmonary fibrosis. By comparing the expression profiles of miRNAs before and after myofibroblast differentiation of LR-MSC, we identified miR-877-3p as a fibrosis-related miRNA. We found that miR-877-3p sequestration inhibited the myofibroblast differentiation of LR-MSC and attenuates bleomycin-induced lung fibrosis by targeting Smad7. Smad7, as an inhibitory smad in the TGF-β1 signaling pathway, was decreased in the myofibroblast differentiation of LR-MSC and up-regulation of Smad7 could inhibit the differentiation process. Our data implicates a potential application of miR-877-3p as a fibrosis suppressor for pulmonary fibrosis therapy and also as a fibrosis marker for predicting prognosis.

Prostaglandin E2-Dependent Phosphorylation of RAS Inhibition 1 (RIN1) at Ser 291 and 292 Inhibits Transforming Growth Factor-β-Induced RAS Activation Pathway in Human Synovial Fibroblasts: Role in Cell Migration

Prostaglandin E2 (PGE2 )-stimulated G-protein-coupled receptor (GPCR) activation inhibits pro-fibrotic TGFβ-dependent stimulation of human fibroblast to myofibroblast transition (FMT), though the precise molecular mechanisms are not fully understood. In the present study, we describe the PGE2 -dependent suppression and reversal of TGFβ-induced events such as α-sma expression, stress fiber formation, and Ras/Raf/ERK/MAPK pathway-dependent activation of myofibroblast migration. In order to elucidate post-ligand-receptor signaling pathways, we identified a predominant PKA phosphorylation motif profile in human primary fibroblasts after treatment with exogenous PGE2 (EC50 30 nM, Vmax 100 nM), mimicked by the adenyl cyclase activator forskolin (EC50 5 μM, Vmax 10 μM). We used a global phosphoproteomic approach to identify a 2.5-fold difference in PGE2 -induced phosphorylation of proteins containing the PKA motif. Deducing the signaling pathway of our migration data, we identified Ras inhibitor 1 (RIN1) as a substrate, whereby PGE2 induced its phosphorylation at Ser291 and at Ser292 by a 5.4- and 4.8-fold increase, respectively. In a series of transient and stable over expression studies in HEK293T and HeLa cells using wild-type (wt) and mutant RIN1 (Ser291/292Ala) or Ras constructs and siRNA knock-down experiments, we showed that PGE2 -dependent phosphorylation of RIN1 resulted in the abrogation of TGFβ-induced Ras/Raf signaling activation and subsequent downstream blockade of cellular migration, emphasizing the importance of such phosphosites in PGE2 suppression of wound closure. Overexpression experiments in tandem with pull-down assays indicated that specific Ser291/292 phosphorylation of RIN1 favored binding to activated Ras. In principal, understanding PGE2 -GPCR activated signaling pathways mitigating TGFβ-induced fibrosis may lead to more evidence-based treatments against the disease. J. Cell. Physiol. 232: 202-215, 2017. © 2016 Wiley Periodicals, Inc.

TGF-β1 promotes bovine mammary fibroblast proliferation through the ERK 1/2 signalling pathway

The abnormal proliferation of bovine mammary fibroblasts (BMFBs) impairs mammary gland development and lactation. Severe manifestations develop into breast fibrosis, leading to the culling of cows and causing serious losses to the dairy industry. Transforming growth factor β1 (TGF-β1) is an important modulator of cell proliferation and extracellular matrix formation; however, limited information is available on BMFBs. In this study, a convenient and stable culture method for BMFBs was established. Treatment with 5 ng/mL of TGF-β1 significantly promoted the proliferation of BMFBs and accelerated the cell cycle. TGF-β1 stimulation for up to 12 h significantly increased the relative ERK1/2 mRNA expression and enhanced the protein expression of p-ERK1/2 and cyclin D1. Conversely, the ERK1/2 inhibitor PD98059 blocked these TGF-β1 effects. Further exploration using a mouse model showed that TGF-β1 significantly increased the proportion of fibroblasts and accelerating the cell transition from the G1 to G2/M phases. In addition, TGF-β1 enhanced the expression of fibrosis markers, α-SMA and I Collagen, which could be blocked efficiently by the PD98059 in mouse mammary gland. Finally, immunofluorescence analysis confirmed that TGF-β1 promoted fibroblast proliferation in healthy dairy cows after normal long-term dietary corn straw roughage supplementation. It is suggested that the diet may promote mammary fibroblast proliferation by raising the level of TGF-β1. Our study provides new insights into how nutrition causes undesirable changes in mammary gland structure.

Expression of WNT5A in Idiopathic Pulmonary Fibrosis and Its Control by TGF-β and WNT7B in Human Lung Fibroblasts

The wingless (Wnt) family of signaling ligands contributes significantly to lung development and is highly expressed in patients with usual interstitial pneumonia (UIP). We sought to define the cellular distribution of Wnt5A in the lung tissue of patients with idiopathic pulmonary fibrosis (IPF) and the signaling ligands that control its expression in human lung fibroblasts and IPF myofibroblasts. Tissue sections from 40 patients diagnosed with IPF or UIP were probed for the immunolocalization of Wnt5A. Further, isolated lung fibroblasts from normal or IPF human lungs, adenovirally transduced for the overexpression or silencing of Wnt7B or treated with TGF-β1 or its inhibitor, were analyzed for Wnt5A protein expression. Wnt5A was expressed in IPF lungs by airway and alveolar epithelium, smooth muscle cells, endothelium, and myofibroblasts of fibroblastic foci and throughout the interstitium. Forced overexpression of Wnt7B with or without TGF-β1 treatment significantly increased Wnt5A protein expression in normal human smooth muscle cells and fibroblasts but not in IPF myofibroblasts where Wnt5A was already highly expressed. The results demonstrate a wide distribution of Wnt5A expression in cells of the IPF lung and reveal that it is significantly increased by Wnt7B and TGF-β1, which, in combination, could represent key signaling pathways that modulate the pathogenesis of IPF.

Role of caveolae in high glucose and TGF-β₁ induced fibronectin production in rat mesangial cells

Accumulation of extracellular matrix (ECM) in glomerular mesangium correlates with loss of renal function in diabetic nephropathy. However, the mechanisms underlying are still incompletely known. In the present study, we explored the role of caveolae in ECM production in rat mesangial cells (MCs) stimulated by high glucose or transforming growth factor-β1 (TGF-β1), and investigated the possible mechanisms. High glucose (HG) or TGF-β1 significantly increased collagen-1 and fibronectin expression at both mRNA and protein levels in time- course dependent manners, and simultaneously induced caveolin-1 tyrosine phosphorylation. Disruption of caveolae with Methyl-β-cyclodextrin (β-MCD) prevented HG and TGF-β1 induced caveolin-1 tyrosine phosphorylation, and attenuated fibronectin but not collagen-1 production. This effect of β-MCD on fibronectin production could be abolished by cholesterol, which restored HG and TGF-β1 induced caveolin-1 tyrosine phosphorylation. In addition, HG and TGF-β1 induced fibronectin production was attenuated by a caveolin-1 scaffold domain peptide. These findings indicate that mesangial cell caveolae regulate fibronectin production at least partly through caveolin-1 phosphorylation.

Detecting splicing variants in idiopathic pulmonary fibrosis from non-differentially expressed genes

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease of unknown cause that lacks a proven therapy for altering its high mortality rate. Microarrays have been employed to investigate the pathogenesis of IPF, but are presented mostly at the gene-expression level due to technologic limitations. In as much as, alternative RNA splicing isoforms are increasingly identified as potential regulators of human diseases, including IPF, we propose a new approach with the capacity to detect splicing variants using RNA-seq data. We conducted a joint analysis of differential expression and differential splicing on annotated human genes and isoforms, and identified 122 non-differentially expressed genes with a high degree of "switch" between major and minor isoforms. Three cases with variant mechanisms for alternative splicing were validated using qRT-PCR, among the group of genes in which expression was not significantly changed at the gene level. We also identified 35 novel transcripts that were unique to the fibrotic lungs using exon-exon junction evidence, and selected a representative for qRT-PCR validation. The results of our study are likely to provide new insight into the pathogenesis of pulmonary fibrosis and may eventuate in new treatment targets.

Pathogenesis, current treatments and future directions for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease (ILD) of unknown origin characterized by epithelial cell dysfunctions, accumulation of fibroblasts and myofibroblasts and relentless deposition of extracellular matrix (ECM). Improved diagnostic accuracy and better trial design have provided important insights from recent clinical trials. Perhaps the most important insight was the realization that 'standard therapy' was actually harmful! This review summarizes the current understanding of the cell types that are altered in IPF and the pathogenic mechanisms that have been identified. It also reviews recent clinical trial results and interpretations. Finally, we highlight attractive biologic targets and therapies in development with recommendations for future therapeutic avenues.

Phenotypical differences in connective tissue cells emerging from microvascular pericytes in response to overexpression of PDGF-B and TGF-β1 in normal skin in vivo

Fibrosis is a deleterious consequence of chronic inflammation in a number of human pathologies ultimately leading to organ dysfunction and failure. Two growth factors that are important in blood vessel physiology and tissue fibrosis, platelet-derived growth factor (PDGF)-B and transforming growth factor (TGF)-β1, were investigated. Adenoviral vectors were used to induce transient overexpression of these growth factors in mouse skin. Changes in tissue structure and protein and mRNA expressions were investigated. Both PDGF-B and TGF-β1 could initiate but neither could sustain angiogenesis. Instead, vascular regression was observed. Overexpression of both TGF-β1 and PDGF-B led to a marked macrophage influx and an expansion of the connective tissue cell population. Over time, this effect was sustained in mice treated with TGF-β1, whereas it was partially reversible in mice treated with PDGF-B. On the basis of structure and expression of phenotypical markers, the emerging connective tissue cell population may originate from microvascular pericytes. TGF-β1 induced expansion of connective tissue cells with a myofibroblast phenotype, whereas PDGF-B induced a fibroblast phenotype negative for α-smooth muscle actin. TGF-β1 and PDGF-B overexpressions mediated distinct effects on mRNA transcript levels of fibrillar procollagens, their modifying enzymes, small leucin-rich repeat proteoglycans, and matricellular proteins affecting both the composition and the quantity of the extracellular matrix. This study offers new insight into the effects of PDGF-B and TGF-β1 on the vasculature and connective tissue in vivo.

Update on models of pulmonary fibrosis therapy for preclinical drug research

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease with high morbidity and mortality for which current medications are not effective. Therefore, identification of potential therapies is of paramount importance. The preclinical evaluation of novel compounds in animal models represents a critical step in drug development.

OBJECTIVE

To describe features and limitations of common animal models of pulmonary fibrosis and discuss relevant preclinical and clinical data on novel potential IPF therapies.

METHODS

Review of the existing literature on such models with a special focus on the bleomycin model and its usefulness for the IPF preclinical drug testing.

CONCLUSIONS

The model of bleomycin-induced pulmonary fibrosis has the advantages of being well established, reproducible and both time- and cost-efficient. However, it has major limitations as it only mimics some features of human IPF. Most importantly, it is initiated by acute lung injury and is at least partially reversible, which is strikingly different from IPF. The failure in establishing effective IPF therapies despite strong efforts in the last decade is partly attributable to our uncritical trust in the models of lung fibrosis and the false belief that they truly reflect what is going on in human disease.

Treatments in idiopathic pulmonary fibrosis: time for a more targeted approach?

Idiopathic pulmonary fibrosis (IPF) is a progressive age-related lung disease, the cause of which is not been fully understood. IPF is a devastating disease with mortality worse than many cancers, and treatment options are limited. IPF is thought to occur after recurrent injury to the alveolar epithelium followed by abnormal repair characterized by the formation of fibroblast and myofibroblast foci and excessive deposition of extracellular matrix. An updated classification of the idiopathic interstitial pneumonias has encouraged a large number of clinical trials. On the whole, these have disappointed. Improvements in molecular techniques have developed our understanding of IPF and with it identified new pathways and potential targets for therapeutic intervention. These insights are leading to interest in biomarkers of disease progression and prognosis and to novel anti-fibrotic agents and a more targeted approach to the treatment of IPF.

Association between proinflammatory responses of respirable silica dust and adverse health effects among dust-exposed workers

OBJECTIVE

To evaluate proinflammatory responses induced by respirable silica dust samples and to analyze the role of those responses in explaining adverse health effects among dust-exposed workers in pottery factoryies and tungsten and tin mines.

METHODS

Proinflammatory cytokines of cells were determined after being treated with silica dust samples. Adverse health effects of workers were calculated on the basis of a cohort study.

RESULTS

Incidence and mortality of silicosis among tungsten miners were higher than those in other workers. The incidence of interleukin-1β levels was highest in tungsten mines, which was consistent with the incidence of silicosis in tungsten miners. The higher levels of TNF-α and interleukin-6 released from macrophages might be helpful in explaining increased mortalities from lung cancer among tin miners.

CONCLUSIONS

Interleukin-1β could be a sensitive biomarker in predicting fibrogenic potential of silica dust and the risk of silicosis among dust-exposed workers.

CYLD negatively regulates transforming growth factor-β-signalling via deubiquitinating Akt

Lung injury, whether induced by infection or caustic chemicals, initiates a series of complex wound-healing responses. If uncontrolled, these responses may lead to fibrotic lung diseases and loss of function. Thus, resolution of lung injury must be tightly regulated. The key regulatory proteins required for tightly controlling the resolution of lung injury have yet to be identified. Here we show that loss of deubiquitinase CYLD led to the development of lung fibrosis in mice after infection with Streptococcus pneumoniae. CYLD inhibited transforming growth factor-β-signalling and prevented lung fibrosis by decreasing the stability of Smad3 in an E3 ligase carboxy terminus of Hsc70-interacting protein-dependent manner. Moreover, CYLD decreases Smad3 stability by deubiquitinating K63-polyubiquitinated Akt. Together, our results unveil a role for CYLD in tightly regulating the resolution of lung injury and preventing fibrosis by deubiquitinating Akt. These studies may help develop new therapeutic strategies for preventing lung fibrosis.

Endogenous annexin A1 counter-regulates bleomycin-induced lung fibrosis

Background

The balancing functions of pro/anti-inflammatory mediators of the complex innate responses have been investigated in a variety of experimental inflammatory settings. Annexin-A1 (AnxA1) is one mediator of endogenous anti-inflammation, affording regulation of leukocyte trafficking and activation in many contexts, yet its role in lung pathologies has been scarcely investigated, despite being highly expressed in lung cells. Here we have applied the bleomycin lung fibrosis model to AnxA1 null mice over a 21-day time-course, to monitor potential impact of this mediator on the control of the inflammatory and fibrotic phases.

Results

Analyses in wild-type mice revealed strict spatial and temporal regulation of the Anxa1 gene, e.g. up-regulation in epithelial cells and infiltrated granulocytes at day 7, followed by augmented protein levels in alveolar macrophages by day 21. Absence of AnxA1 caused increases in: i) the degree of inflammation at day 7; and ii) indexes of fibrosis (assessed by deposition of hydroxyproline in the lung) at day 7 and 21. These alterations in AnxA1 null mice were paralleled by augmented TGF-β1, IFN-γ and TNF-α generation compared to wild-type mice. Finally, treatment of wild type animals with an AnxA1 peptido-mimetic, given prophylactically (from day 0 to 21) or therapeutically (from day 14 onward), ameliorated both signs of inflammation and fibrosis.

Conclusion

Collectively these data reveal a pathophysiological relevance for endogenous AnxA1 in lung inflammation and, more importantly, fibrosis, and may open new insights for the pharmacological treatment of lung fibrosis.

Myofibroblast differentiation and survival in fibrotic disease

During wound healing, contractile fibroblasts called myofibroblasts regulate the formation and contraction of granulation tissue; however, pathological and persistent myofibroblast activation, which occurs in hypertrophic scars or tissue fibrosis, results in a loss of function. Many reviews outline the cellular and molecular features of myofibroblasts and their roles in a variety of diseases. This review focuses on the origins of myofibroblasts and the factors that control their differentiation and prolonged survival in fibrotic tissues. Pulmonary fibrosis is used to illustrate many key points, but examples from other tissues and models are also included. Myofibroblasts originate mostly from tissue-resident fibroblasts, and also from epithelial and endothelial cells or other mesenchymal precursors. Their differentiation is influenced by cytokines, growth factors, extracellular matrix composition and stiffness, and cell surface molecules such as proteoglycans and THY1, among other factors. Many of these effects are modulated by cell contraction. Myofibroblasts resist programmed cell death, which promotes their accumulation in fibrotic tissues. The cause of resistance to apoptosis in myofibroblasts is under ongoing investigation, but many of the same stimuli that regulate their differentiation are involved. The contributions of oxidative stress, the WNT-β-catenin pathway and PPARγ to myofibroblast differentiation and survival are increasingly appreciated.

Mesenchymal cell survival in airway and interstitial pulmonary fibrosis

Fibrotic reactions in the airways of the lung or the pulmonary interstitium are a common pathologic outcome after exposure to a wide variety of toxic agents, including metals, particles or fibers. The survival of mesenchymal cells (fibroblasts and myofibroblasts) is a key factor in determining whether a fibroproliferative response that occurs after toxic injury to the lung will ultimately resolve or progress to a pathologic state. Several polypeptide growth factors, including members of the platelet-derived growth factor (PDGF) family and the epidermal growth factor (EGF) family, are prosurvival factors that stimulate a replicative and migratory mesenchymal cell phenotype during the early stages of lung fibrogenesis. This replicative phenotype can progress to a matrix synthetic phenotype in the presence of transforming growth factor-β1 (TGF-β1). The resolution of a fibrotic response requires growth arrest and apoptosis of mesenchymal cells, whereas progressive chronic fibrosis has been associated with mesenchymal cell resistance to apoptosis. Mesenchymal cell survival or apoptosis is further influenced by cytokines secreted during Th1 inflammation (e.g., IFN-γ) or Th2 inflammation (e.g., IL-13) that modulate the expression of growth factor activity through the STAT family of transcription factors. Understanding the mechanisms that regulate the survival or death of mesenchymal cells is central to ultimately developing therapeutic strategies for lung fibrosis.

Abnormal expression of IGF-binding proteins, an initiating event in idiopathic pulmonary fibrosis?

For significant improvements to occur in the survival of patients with idiopathic pulmonary fibrosis (IPF), it is necessary to develop novel and more precisely targeted therapies. The selection of future appropriate regimens must critically depend on improved characterization of the molecules driving the pathogenesis of IPF. It is well defined that IPF is characterized by the expression of genes indicating an active tissue remodeling program, including extracellular matrix (ECM) and basement membrane components, as well as myofibroblast-associated and epithelial cell-related genes. A few recent advances are worth mentioning. Pulmonary research demonstrates abnormal expression of insulin-like growth factor (IGF) binding proteins (IGFBPs) in IPF, including human IPF bronchoalveolar lavage (BAL) cells and BAL fluids, human IPF fibroblasts, as well as fibrotic lung tissues of bleomycin-induced mice and IPF patients, analyzed by microarray, reverse transcription-polymerase chain reaction (RT-PCR), ribonuclease protection assay (RPA), Western blot, immunohistochemistry, or enzyme-linked immunosorbent assay (ELISA). Simultaneously, in vitro and in vivo studies indicate the involvement of IGFBPs in the initiation and development of the fibrosis process, including fibroblast activation and transdifferentiation to a myofibroblast phenotype, epithelial-mesenchymal transition (EMT), increased ECM production, and decreased ECM degradation, possibly contributing to the final lung fibrosis. These observations suggest that dysregulation of IGFBPs may be a key factor responsible for the initiation and perpetuation of IPF. Such efforts could lead to potential candidate molecules being exploited for therapeutic manipulation.

Inhibition of type III TGF-β receptor aggravates lung fibrotic process

Transforming growth factor-beta (TGF-β) is a multifunctional cytokine that regulates cell proliferation, death, development or differentiation. In addition, TGF-β is considered a key mediator in fibrogenic processes, and signals either directly or indirectly through types I, II and III (TβRI, II, and III) receptor complexes. The type III TGF-β (TβRIII or betaglycan) is a transmembrane proteoglycan without a functional kinase domain, and is considered as a coreceptor to increase the affinity of ligand binding to TβRII. Little is studied on TGF-β and TβRIII (or betaglycan) signaling, while it is well known about TGF-β ligand and TβRII signaling. In this study, we investigated the effects of TβRIII expression on TGF-β induced differentiation, in view of the finding that TβRIII is significantly downregulated during TGF-β-induced differentiation in fibroblasts. TGF-beta induced alpha-SMA and Procollagen Type I expression were markedly inhibited in fibroblasts stably expressing TβRIII. Endogenous TβRIII expression did not alter the TβRI or TβRII levels, but inhibited Smad 2/3, Akt and ERK phosphorylation. The molecular mechanism of TβRIII action in TGF-β-induced differentiation is associated with both Smad-dependent and Smad-independent pathways. Our results suggest that TβRIII is a novel molecular target for regulation of TGF-β signaling in myofibroblast differentiation.

Small interfering RNAs (siRNAs) targeting TGF-beta1 mRNA suppress asbestos-induced expression of TGF-beta1 and CTGF in fibroblasts

Interstitial lung disease (ILD) afflicts millions of people worldwide. ILD can be caused by a number of agents, including inhaled asbestos, and may ultimately result in respiratory failure and death. Currently, there are no effective treatments for ILD. Transforming growth factor-beta1 (TGF-beta1) is thought to play an important role in the development of pulmonary fibrosis, and asbestos has been shown to induce TGF-beta1 expression in a murine model of ILD. To better define the role of TGF-beta1 in ILD, we developed several small interfering RNAs (siRNAs) that target TGF-beta1 mRNA for degradation. To assess the efficacy of each siRNA in reducing asbestos-induced TGF-beta1 expression, Swiss 3T3 fibroblasts were transfected with TGF-beta1 siRNAs and then treated with chrysotile asbestos for 48 h. Two independent siRNAs targeting TGF-beta1 mRNA knocked-down asbestos-induced expression of TGF-beta1 mRNA by 72-89% and protein by 70-84%. Interestingly, siRNA knockdown of TGF-beta1 also reduced asbestos-induced expression of connective tissue growth factor (CTGF). CTGF can be upregulated by TGF-beta1 and appears to play an important role in the development of pulmonary fibrosis. These results suggest that siRNAs could be effective in preventing or possibly arresting the progression of pulmonary fibrosis. Studies are underway in vivo to test this postulate.

Spaceflight modulates expression of extracellular matrix, adhesion, and profibrotic molecules in mouse lung

NASA has reported pulmonary abnormalities in astronauts on space missions, but the molecular changes in lung tissue remain unknown. The goal of the present study was to explore the effects of spaceflight on expression of extracellular matrix (ECM), cell adhesion, and pro-fibrotic molecules in lungs of mice flown on Space Shuttle Endeavour (STS-118). C57BL/6Ntac mice housed in animal enclosure modules during a 13-day mission in space (FLT) were killed within hours after return; ground controls were treated similarly for comparison (GRD). Analysis of genes associated with ECM and adhesion molecules was performed according to quantitative RT-PCR. The data revealed that FLT lung samples had statistically significant transcriptional changes, i.e., at least 1.5-fold, in 25 out of 84 examined genes (P < 0.05); 15 genes were upregulated and 10 were downregulated. The genes that were upregulated by more than twofold were Ctgf, Mmp2, Ncam1, Sparc, Spock1, and Timp3, whereas the most downregulated genes were Lama1, Mmp3, Mmp7, vcam-1, and Sele. Histology showed profibrosis-like changes occurred in FLT mice, more abundant collagen accumulation around blood vessels, and thicker walls compared with lung samples from GRD mice. Immunohistochemistry was used to compare expression of six selected proteins associated with fibrosis. Immunoreactivity of four proteins (MMP-2, CTGF, TGF-beta1, and NCAM) was enhanced by spaceflight, whereas, no difference was detected in expression of MMP-7 and MMP-9 proteins between the FLT and GRD groups. Taken together, the data demonstrate that significant changes can be readily detected shortly after return from spaceflight in the expression of factors that can adversely influence lung function.

Modulation of reactive oxygen species by Rac1 or catalase prevents asbestos-induced pulmonary fibrosis

The release of reactive oxygen species (ROS) and cytokines by alveolar macrophages has been demonstrated in asbestos-induced pulmonary fibrosis, but the mechanism linking alveolar macrophages to the pathogenesis is not known. The GTPase Rac1 is a second messenger that plays an important role in host defense. In this study, we demonstrate that Rac1 null mice are protected from asbestos-induced pulmonary fibrosis, as determined by histological and biochemical analysis. We hypothesized that Rac1 induced pulmonary fibrosis via generation of ROS. Asbestos increased TNF-alpha and ROS in a Rac1-dependent manner. TNF-alpha was elevated only 1 day after exposure, whereas ROS generation progressively increased in bronchoalveolar lavage cells obtained from wild-type (WT) mice. To determine whether ROS generation contributed to pulmonary fibrosis, we overexpressed catalase in WT monocytes and observed a decrease in ROS generation in vitro. More importantly, administration of catalase to WT mice attenuated the development of fibrosis in vivo. For the first time, these results demonstrate that Rac1 plays a crucial role in asbestos-induced pulmonary fibrosis. Moreover, it suggests that a simple intervention may be useful to prevent progression of the disease.

Naringenin: a potential immunomodulator for inhibiting lung fibrosis and metastasis

Patients with idiopathic pulmonary fibrosis have a high incidence of lung cancer and a worse prognosis for clinical treatment. A few molecules with antifibrosis properties have been shown promoting cancer progression in clinical trials. The objective of this study was to determine whether there is a similar tendency in mice as in human beings and whether these mice models may be used to find new therapeutic agents with antifibrotic properties but not cancer-promoting properties. We used bleomycin to induce pulmonary fibrosis in mice with or without naringenin treatment and measured the immune-associated lymphocytes and their secreted cytokines using flow cytometry and ELISA from lung tissue. Both passive and spontaneous metastatic models in bleomycin-treated C57BL/6 and BALB/c mice were used to test the hypothesis that mice with pulmonary fibrosis could have an increased risk of lung cancer and associated cancer progression. Here, we show that mice with lung fibrosis challenged using tumors show an increased incidence of lung metastasis and shorter life spans compared with the mice without lung fibrosis. A fibrotic environment in the lung results in increased abundance of transforming growth factor-beta1 and CD4(+)CD25(+)Foxp3(+) regulatory T cells and a decreased proportion of activated effector T cells. This grave immunosuppressive environment favors tumor localization and growth. Naringenin significantly reduces lung metastases in mice with pulmonary fibrosis and increases their survival by improving the immunosuppressive environment through down-regulating transforming growth factor-beta1 and reducing regulatory T cells. Naringenin could be an ideal therapeutic agent in the treatment of both cancer and fibrosis.

PDE4 inhibitors roflumilast and rolipram augment PGE2 inhibition of TGF-{beta}1-stimulated fibroblasts

Fibrotic diseases are characterized by the accumulation of extracellular matrix together with distortion and disruption of tissue architecture. Phosphodiesterase (PDE)4 inhibitors, by preventing the breakdown of cAMP, can inhibit fibroblast functions and may be able to mitigate tissue remodeling. Transforming growth factor (TGF)-beta1, a mediator of fibrosis, can potentially modulate cAMP by altering PGE(2) metabolism. The present study assessed whether PDE4 inhibitors functionally antagonize the profibrotic activity of fibroblasts stimulated by TGF-beta1. The PDE4 inhibitors roflumilast and rolipram both inhibited fibroblast-mediated contraction of three-dimensional collagen gels and fibroblast chemotaxis toward fibronectin in the widely studied human fetal lung fibroblast strain HFL-1 and several strains of fibroblasts from adult human lung. Roflumilast was approximately 10-fold more potent than rolipram. There was a trend for PDE4 inhibitors to inhibit more in the presence of TGF-beta1 (0.05 < P < 0.08). The effect of the PDE4 inhibitors was mediated through cAMP-stimulated protein kinase A (PKA), although a PKA-independent effect on gel contraction was also observed. The effect of PDE4 inhibitors depended on fibroblast production of PGE(2) and TGF-beta1-induced PGE(2) production. PDE4 inhibitors together with TGF-beta1 resulted in augmented PGE(2) production together with increased expression of COX mRNA and protein. The present study supports the concept that PDE4 inhibitors may attenuate fibroblast activities that can lead to fibrosis and that PDE4 inhibitors may be particularly effective in the presence of TGF-beta1-induced fibroblast stimulation.

EM703, a new derivative of erythromycin, inhibits transforming growth factor-beta signaling in human lung fibroblasts

Long-term, low-dose macrolide therapy has been proven to improve survival in patients with diffuse panbronchiolitis and cystic fibrosis, although the mechanisms by which it does so remain unknown. To elucidate the molecular mechanisms of the anti-inflammatory effects of macrolides, the authors examined the effects of erythromycin (EM-A) and new derivative EM703 on transforming growth factor (TGF)-beta /Smad signaling fibroblasts. EM-A and EM703 each inhibited fibroblast proliferation and the collagen production in human lung fibroblasts induced by TGF-beta. EM-A and EM703 inhibited the augmentation of Smad3 mRNA induced by TGF-beta. Smad7 mRNA was inhibited by TGF-beta, but augmented by coincubation with EM-A or EM703. EM-A and EM703 each inhibited p-Smad2/3 proteins induced by TGF-beta. Smad7 protein inhibited by TGF-beta restored beyond basal level by EM-A and EM703. These findings suggest that EM-A and EM703 inhibit TGF-beta signaling in human lung fibroblasts via inhibition of p-Smad2/3 through recovery of Smad7 level.

Transforming growth factor-beta1 induces heparan sulfate 6-O-endosulfatase 1 expression in vitro and in vivo

Transforming growth factor (TGF)-beta1 plays an important role in the development of pulmonary fibrosis. In this study we examined the relationship between TGF-beta1 stimulation and the expression of heparan sulfate (HS) 6-O-endosulfatase 1 (Sulf1) in cultured normal human lung fibroblasts (NHLFs) and in murine lungs in vivo. By removing 6-O-sulfates from specific HS intrachain sites on the cell surface, Sulf1 has been shown to modulate the activities of many HS binding growth factors and morphogens including fibroblast growth factor (FGF)-2. Real time reverse transcription-PCR analysis revealed that TGF-beta1 increased Sulf1 expression in NHLFs in a dose- and time-dependent manner which was accompanied by a decrease in 6-O-sulfated disaccharides as revealed by high performance liquid chromatography analysis. Decreased ERK activation after FGF-2 stimulation was observed in TGF-beta1-treated NHLFs compared with control cells without changes in HS-dependent FGF-2 binding or FGF-2.FR1c complex formation. To study the function of Sulf1, negative control or Sulf1-specific small interference RNA (siRNA)-transfected NHLFs were stimulated with TGF-beta1. Enhanced Smad2/3 phosphorylation and elevated total Smad2 protein level were observed in Sulf1 siRNA-transfected cells and were accompanied by enhanced expression of alpha-smooth muscle actin and fibronectin. In addition, Sulf1 siRNA transfection enhanced the anti-proliferative effect of TGF-beta1. Finally Sulf1 expression was up-regulated in the lungs of mice treated with adenovirus encoding active TGF-beta1. Taken together, our data indicate that Sulf1 is a TGF-beta1-responsive gene both in vitro and in vivo and may function as a negative regulator of TGF-beta1-induced fibrogenesis.

Laser capture microdissection reveals dose-response of gene expression in situ consequent to asbestos exposure

The genes that mediate fibroproliferative lung disease remain to be defined. Prior studies from our laboratory showed by in situ hybridization and immunohistochemistry that the genes coding for tumour necrosis factor alpha, transforming growth factor beta, the platelet-derived growth factor A and B isoforms, and alpha-1 pro-collagen are expressed in fibroproliferative lesions that develop quickly after asbestos inhalation. These five genes, along with matrix metalloproteinase 9, a collagenase found to be increased in several lung diseases, are known to control matrix production and cell proliferation in humans and animals. Here we show by laser capture microdissection that (i) The six genes are expressed at significantly higher levels in the asbestos-exposed mice when comparing the same anatomic regions 'captured' in unexposed mice. (ii) The bronchiolar-alveolar duct (BAD) junctions, where the greatest number of fibres initially deposit, were always significantly higher than the other anatomic regions for each gene. The first alveolar duct bifurcation (ADB) generally was higher than the second ADB, the ADBs were always significantly higher than the airway walls and pleura, and the airway walls and pleura were generally higher than the unexposed tissues. (iii) Animals exposed for 3 days always exhibited significantly higher levels of gene expression at the BAD junctions and ADBs than animals exposed for 2 days. To our knowledge, this is the first demonstration of a dose-response to a toxic particle in situ, and this response appears to be dependent on the number of fibres that deposits at the individual anatomic site.

Fibrosis in connective tissue disease: the role of the myofibroblast and fibroblast-epithelial cell interactions

Fibrosis, characterized by excessive extracellular matrix accumulation, is a common feature of many connective tissue diseases, notably scleroderma (systemic sclerosis). Experimental studies suggest that a complex network of intercellular interactions involving endothelial cells, epithelial cells, fibroblasts and immune cells, using an array of molecular mediators, drives the pathogenic events that lead to fibrosis. Transforming growth factor-beta and endothelin-1, which are part of a cytokine hierarchy with connective tissue growth factor, are key mediators of fibrogenesis and are primarily responsible for the differentiation of fibroblasts toward a myofibroblast phenotype. The tight skin mouse (Tsk-1) model of cutaneous fibrosis suggests that numerous other genes may also be important.

Treatment with chondroitinase ABC alleviates bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is characterized by an accumulation of inflammatory cells in the lung interstitium, followed by an increased deposition of extracellular matrix. Macrophages play a vital role in this disease by mediating the progression from inflammation to fibrosis, but the mechanisms by which macrophages are retained at these sites are not fully understood. Although the transmigration of leukocytes is regulated by chemokines, glycosaminoglycans modulate the function of chemokines and the migration of leukocytes. Accordingly, we investigated the role of chondroitin sulfate proteoglycans (CSPGs) in a murine bleomycin-induced pulmonary fibrosis models. After intratracheal injection of bleomycin or saline, mice were randomized to receive one intravenous injection and continuous infusion of the CSPG-digesting enzyme chondroitinase ABC (ChABC), or vehicle, for 7 days. CSPGs were readily induced and progressively augmented after the bleomycin challenge. Although CSPGs inhibited the early CCL2-dependent recruitment of macrophages, deposited CSPGs retained macrophages in fibrotic interstitium in a CD44-dependent manner. Treatment with ChABC in vivo dramatically increased survival of the mice and reduced collagen deposition by inhibiting persistent macrophage accumulation. These results indicate a pivotal role for CSPGs in macrophage-mediated lung fibrogenesis and suggest a possible new therapeutic role for ChABC in pulmonary fibrosis.