Increase In Transforming Growth Factor-beta Research Articles

Impaired Myofibroblast Proliferation is a Central Feature of Pathologic Post-Natal Alveolar Simplification.

Premature infants with bronchopulmonary dysplasia (BPD) have impaired alveolar gas exchange due to alveolar simplification and dysmorphic pulmonary vasculature. Advances in clinical care have improved survival for infants with BPD, but the overall incidence of BPD remains unchanged because we lack specific therapies to prevent this disease. Recent work has suggested a role for increased transforming growth factor-beta (TGFβ) signaling and myofibroblast populations in BPD pathogenesis, but the functional significance of each remains unclear. Here, we utilize multiple murine models of alveolar simplification and comparative single-cell RNA sequencing to identify shared mechanisms that could contribute to BPD pathogenesis. Single-cell RNA sequencing reveals a profound loss of myofibroblasts in two models of BPD and identifies gene expression signatures of increased TGFβ signaling, cell cycle arrest, and impaired proliferation in myofibroblasts. Using pharmacologic and genetic approaches, we find no evidence that increased TGFβ signaling in the lung mesenchyme contributes to alveolar simplification. In contrast, this is likely a failed compensatory response, since none of our approaches to inhibit TGFb signaling protect mice from alveolar simplification due to hyperoxia while several make simplification worse. In contrast, we find that impaired myofibroblast proliferation is a central feature in several murine models of BPD, and we show that inhibiting myofibroblast proliferation is sufficient to cause pathologic alveolar simplification. Our results underscore the importance of impaired myofibroblast proliferation as a central feature of alveolar simplification and suggest that efforts to reverse this process could have therapeutic value in BPD.

Androgen receptor inhibition suppresses anti-tumor neutrophil response against bone metastatic prostate cancer via regulation of TβRI expression

Bone metastatic disease of prostate cancer (PCa) is incurable and progression in bone is largely dictated by tumor-stromal interactions in the bone microenvironment. We showed previously that bone neutrophils initially inhibit bone metastatic PCa growth yet metastatic PCa becomes resistant to neutrophil response. Further, neutrophils isolated from tumor-bone lost their ability to suppress tumor growth through unknown mechanisms. With this study, our goal was to define the impact of metastatic PCa on neutrophil function throughout tumor progression and to determine the potential of neutrophils as predictive biomarkers of metastatic disease. Using patient peripheral blood polymorphonuclear neutrophils (PMNs), we identified that PCa progression dictates PMN cell surface markers and gene expression, but not cytotoxicity against PCa. Importantly, we also identified a novel phenomenon in which second generation androgen deprivation therapy (ADT) suppresses PMN cytotoxicity via increased transforming growth factor beta receptor I (TβRI). High dose testosterone and genetic or pharmacologic TβRI inhibition rescued androgen receptor-mediated neutrophil suppression and restored neutrophil anti-tumor immune response. These studies highlight the ability to leverage standard-care ADT to generate neutrophil anti-tumor responses against bone metastatic PCa.

Cadherin-11 Influences Differentiation in Human Mesenchymal Stem Cells by Regulating the Extracellular Matrix Via the TGFβ1 Pathway

For regenerative medicine, directing stem cell fate is one of the key aims. Human mesenchymal stem cells (hMSCs) are versatile adult stem cells that have been proposed for several clinical applications, making directing their fate of utmost importance. For most clinical applications, their differentiation toward the adipogenic lineage is an undesired outcome. Understanding the mechanisms that regulate hMSC commitment toward the adipogenic lineage might help open up new avenues for fine-tuning implanted hMSCs for regenerative medicine applications. We know that cadherin-11 is required for hMSC commitment to the adipogenic lineage; therefore, we sought to investigate the mechanisms through which cadherin-11 regulates adipogenic differentiation. We observed that hMSCs lacking cadherin-11 had decreased expression of type VI collagen and increased expression of fibronectin. We provide evidence of increased transforming growth factor beta 1 and the subsequent translocation of phosphorylated SMAD2/3 into the nucleus by cells that lack cadherin-11, which could be attributed to the changes in extracellular matrix composition. Taken together, our study implicates cadherin-11 in regulating extracellular matrix production and thereby helping improve cell- and material-based regenerative medicine approaches.

Involvement of Cellular Prion Protein in Invasion and Metastasis of Lung Cancer by Inducing Treg Cell Development.

The cellular prion protein (PrPC) is a cell surface glycoprotein expressed in many cell types that plays an important role in normal cellular processes. However, an increase in PrPC expression has been associated with a variety of human cancers, where it may be involved in resistance to the proliferation and metastasis of cancer cells. PrP-deficient (Prnp0/0) and PrP-overexpressing (Tga20) mice were studied to evaluate the role of PrPC in the invasion and metastasis of cancer. Tga20 mice, with increased PrPC, died more quickly from lung cancer than did the Prnp0/0 mice, and this effect was associated with increased transforming growth factor-beta (TGF-β) and programmed death ligand-1 (PD-L1), which are important for the development and function of regulatory T (Treg) cells. The number of FoxP3+CD25+ Treg cells was increased in Tga20 mice compared to Prnp0/0 mice, but there was no significant difference in either natural killer or cytotoxic T cell numbers. In addition, mice infected with the ME7 scrapie strain had decreased numbers of Treg cells and decreased expression of TGF-β and PD-L1. These results suggest that PrPC plays an important role in invasion and metastasis of cancer cells by inducing Treg cells through upregulation of TGF-β and PD-L1 expression.

Developmental abnormalities in the cornea of a mouse model for Marfan syndrome

Elastic fibres provide tissues with elasticity and flexibility. In the healthy human cornea, elastic fibres are limited to the posterior region of the peripheral stroma, but their specific functional role remains elusive.Here, we examine the physical and structural characteristics of the cornea during development in the mgΔloxPneo dominant-negative mouse model for Marfan syndrome, in which the physiological extracellular matrix of its elastic-fibre rich tissues is disrupted by the presence of a dysfunctional fibrillin-1 glycoprotein. Optical coherence tomography demonstrated a reduced corneal thickness in the mutant compared to wild type mice from embryonic day 16.5 until adulthood. X-ray scattering and electron microscopy revealed a disruption to both the elastic fibre and collagen fibril ultrastructure in the knockout mice, as well as abnormally low levels of the proteoglycan decorin. It is suggested that these alterations might be a result of increased transforming growth factor beta signalling. To conclude, this study has demonstrated corneal structure and ultrastructure to be altered when fibrillin-1 is disrupted and has provided insights into the role of fibrillin-1 in developing a functional cornea.

Fingolimod reduces CXCR4-mediated B cell migration and induces regulatory B cells-mediated anti-inflammatory immune repertoire

BackgroundFingolimod, an oral therapy for patients with relapsing Multiple Sclerosis (MS), traps CC chemokine receptor type 7 (CCR7)-expresssing lymphocytes within lymphoid tissues in the periphery, thereby supposedly reducing the infiltration of pathogenic cells into the central nervous system. Additional immunomodulatory effects of Fingolimod, involving cell function, B and T cells interactions and cross-regulation, have scarcely been studied. The objective of this study was to assess how Fingolimod therapy affects B cells functions, namely cell migration, immunoglobullin production and T cell stimulation. MethodsB cells from 36 patients with relapsing MS were obtained before and after 3 months Fingolimod therapy, while CD4 T cells were collected pre-treatment. Clinical follow-up was performed for 1 year. For in-vitro validation, Lymphoblastoid cell-lines from 16 patients were cultured with Fingolimod. B cell migration towards C-X-C Motif Chemokine Ligand 12 (CXCL12) was assessed using a transwell system. C-X-C chemokine receptor 4 (CXCR4) expression was assessed by flow cytometry and western blot. Plasma immunoglobullins and Brain-derived Neurotrophic Factor (BDNF) were assessed by ELISA or RT-PCR. Drug effect on interacting co-cultured B and T cells on cytokine profiles and T cell proliferation was explored by flow cytometry. ResultsLymphocyte count reduction did not predict clinical response of patients. Fingolimod therapy reduced CXCR4 expression and B cell migration towards CXCL12. No effect was found on immunoglobulins and BDNF. B cells from Fingolimod-treated patients induced a reduction in pro-inflammatory cytokines in T cells, while increased transforming growth factor beta (TGFβ)+ B and T cells, and downregulated IL2-secretion from proliferative T cells. ConclusionsFingolimod promotes anti-inflammatory cytokine profiles of B and T cells, through induction of regulatory B cells. Reduced B cell migration capacity in Fingolimod-treated patients leading to decreased cerebral inflammatory infiltration, may be part of the mechanism by which Fingolimod reduces disease activity in MS.

Abstract 425: Doxorubicin Upregulation of the Fibrotic Transforming Growth Factor-beta Pathway

Childhood cancer survivors are at an increased risk of heart disease as a result of their cancer treatments. Drugs like doxorubicin (DOX) are an effective part of treatment regimens, but have been proven to cause acute and chronic cardiotoxicity (DOX tox). An under-investigated aspect of DOX tox is the interstitial fibrosis that the majority of patients develop. This project aims to better understand the pathology of DOX-induced cardiac fibrosis and the role of the pro-fibrotic transforming growth factor-beta (TGFb) signaling pathway. Research in the area of fibrosis and the effect of DOX on cardiac fibroblasts will increase our understanding of DOX tox. This understanding will allow for improved treatment of pediatric cancer patients by reducing the cardiotoxic sequelae of many standard chemotherapy regimens. Cardiac fibroblasts, isolated from 3 week old mice and treated with 5 μM DOX, showed an increase in nuclear pSMAD compared to control cells via fluorescent immunocytology (2.06 ± 0.26 vs 1.13 ± 0.15, p<0.05). Mice treated with 3 mg/kg DOX injections from 2 weeks to 6 weeks of age showed increased TGFb staining in the left ventricle (1.83 ± 0.34 vs 0.87 ± 0.28, p<0.05) a week after treatment ceased. A subset of mice were followed into old age and sacrificed at 80 weeks. A clear increase in TGFb was seen with age. However, 80 week mice that were exposed to DOX early in life showed a greater increase in TGFb staining compared to untreated 80 week old mice (44.50 ± 2.48 vs 30.93 ± 2.30, p<0.001). Early DOX exposure causes chronic molecular changes as evidenced by acute and chronic changes in signaling molecules in cardiac tissue. Changes in collagen seen in earlier studies and increases in MMP-2 from the literature suggest a cardiac remodeling phenotype in DOX-exposed animals. This project demonstrates that DOX initiates changes to pro-fibrotic pathways, seemingly driven by the TGFb signaling pathway.

Mitigation of myocardial fibrosis by molecular cardiac surgery–mediated gene overexpression

ObjectiveHeart failure is accompanied by up-regulation of transforming growth factor beta signaling, accumulation of collagen and dysregulation of sarcoplasmic reticulum calcium adenosine triphosphatase cardiac isoform 2a (SERCA2a). We examined the fibrotic response in small and large myocardial infarct, and the effect of overexpression of the SERCA2a gene. MethodsIschemic cardiomyopathy was induced via creation of large or small infarct in 26 sheep. Animals were divided into 4 groups: small infarct; large infarct with heart failure; gene-treated (large infarct with heart failure followed by adeno-associated viral vector, serotype 1.SERCA2a gene construct transfer by molecular cardiac surgery with recirculating delivery); and control. ResultsHeart failure was significantly less pronounced in the gene-treated and small-infarct groups than in the large-infarct group. Expression of transforming growth factor beta signaling components was significantly higher in the large-infarct group, compared with the small-infarct and gene-treated groups. Both the angiotensin II type 1 receptor and angiotensin II were significantly elevated in the small- and large-infarct groups, whereas gene treatment diminished this effect. Active fibrosis with de novo collagen synthesis was evident in the large-infarct group; the small-infarct and gene-treated groups showed less fibrosis, with a lower ratio of de novo to mature collagen. ConclusionsThe data presented provide evidence that progression of fibrosis is mediated through increased transforming growth factor beta and angiotensin II signaling, which is mitigated by increased SERCA2a gene expression.

Abstract 12501: Abnormal Activation of TGFβ Signaling as a Pathogenesis of Left Ventricular Non-compaction Cardiomyopathy

Left ventricular non-compaction (LVNC) is the third most prevalent cardiomyopathy in children and has a unique phenotype with characteristically extensive hypertrabeculation of the left ventricle, similar to the embryonic left ventricle, suggesting a developmental defect of the embryonic myocardium. However, in-depth investigation of this disease has been challenging due to the lack of animal models that can faithfully recapitulate the clinical phenotype of LVNC. In this study, we demonstrated that patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from LVNC patients carrying a mutation in cardiac transcription factor TBX20 recapitulated a developmental defect consistent with the LVNC phenotype at the single-cell level. We first performed genetic tests and identified two TBX20 mutations, Y317* and T262M from multiple members in a family with LVNC history and one isolated patient. We then utilized iPSC-CMs to show that increased transforming growth factor beta (TGFβ) signaling is one of the central mechanisms underlying the pathogenesis of LVNC caused by TBX20 mutation. LVNC iPSC-CMs demonstrated decreased proliferative capacity due to abnormal activation of TGFβ signaling (Figs. A-B). TBX20 regulated the expression of TGFβ signaling modifiers including ITGAV and the Smad cofactor, PRDM16, which is a known genetic cause of LVNC. Genome editing of PRDM16 in control iPSC-CMs led to proliferation defects as seen in LVNC iPSC-CMs. Inhibition of abnormal TGFβ signaling by TGFβ receptor-1 inhibitors or ITGAV inhibitor, or genetic correction of the TBX20 mutation using TALEN reversed the proliferation defects seen in LVNC iPSC-CMs (Figs. C-D). Our results demonstrate that iPSC-CMs are a useful tool for the exploration of novel mechanisms underlying poorly understood cardiomyopathies such as LVNC. Here we provide the first evidence of activation of TGFβ signaling as playing a role in the pathogenesis of LVNC.

Abstract 248: Aberrant TGFβ Signaling as an Etiology of Left Ventricular Non-compaction Cardiomyopathy

Left ventricular non-compaction (LVNC) is the third most prevalent cardiomyopathy in children and has a unique phenotype with characteristically extensive hypertrabeculation of the left ventricle, similar to the embryonic left ventricle, suggesting a developmental defect of the embryonic myocardium. However, studying this disease has been challenging due to the lack of an animal model that can faithfully recapitulate the clinical phenotype of LVNC. To address this, we showed that patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) generated from a family with LVNC history recapitulated a developmental defect consistent with the LVNC phenotype at the single-cell level. We then utilized hiPSC-CMs to show that increased transforming growth factor beta (TGFβ) signaling is one of the central mechanisms underlying the pathogenesis of LVNC. LVNC hiPSC-CMs demonstrated decreased proliferative capacity due to abnormal activation of TGFβ signaling (Figs A-B). Exome sequencing demonstrated a mutation in TBX20, which regulates TGFβ signaling through upregulation of ITGAV, contributing to the LVNC phenotype. Inhibition of abnormal TGFβ signaling or genetic correction of the TBX20 mutation (Figs C-D) using TALEN reversed the proliferation defects seen in LVNC hiPSC-CMs. Our results demonstrate that hiPSC-CMs are a useful tool for the exploration of novel mechanisms underlying poorly understood cardiomyopathies such as LVNC. Here we provide the first evidence of activation of TGFβ signaling as playing a role in the pathogenesis of LVNC.

Connective tissue disorders and cardiovascular complications: the indomitable role of transforming growth factor-beta signaling.

Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that cosegregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic root dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. Given the evidence of increased transforming growth factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in this relationship. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, heritable connective tissue syndromes related to TGF-β receptor (TGFBR) mutations, and discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system.

Comprehensive Clinical and Molecular Analysis of 12 Families with Type 1 Recessive Cutis Laxa

Autosomal recessive cutis laxa type I (ARCL type I) is characterized by generalized cutis laxa with pulmonary emphysema and/or vascular complications. Rarely, mutations can be identified in FBLN4 or FBLN5. Recently, LTBP4 mutations have been implicated in a similar phenotype. Studying FBLN4, FBLN5, and LTBP4 in 12 families with ARCL type I, we found bi-allelic FBLN5 mutations in two probands, whereas nine probands harbored biallelic mutations in LTBP4. FBLN5 and LTBP4 mutations cause a very similar phenotype associated with severe pulmonary emphysema, in the absence of vascular tortuosity or aneurysms. Gastrointestinal and genitourinary tract involvement seems to be more severe in patients with LTBP4 mutations. Functional studies showed that most premature termination mutations in LTBP4 result in severely reduced mRNA and protein levels. This correlated with increased transforming growth factor-beta (TGFβ) activity. However, one mutation, c.4127dupC, escaped nonsense-mediated decay. The corresponding mutant protein (p.Arg1377Alafs(*) 27) showed reduced colocalization with fibronectin, leading to an abnormal morphology of microfibrils in fibroblast cultures, while retaining normal TGFβ activity. We conclude that LTBP4 mutations cause disease through both loss of function and gain of function mechanisms.

Effect of feeding whey peptide fractions on the immune response in healthy and Escherichia coli infected mice

The antimicrobial and immunomodulatory activities of whey proteins and peptides make them promising candidates for protection against pathogens. To test this hypothesis, a whey protein isolate and three peptide fractions obtained from its trypsin/chymotrypsin digestion were given orally to mice for 7 days. Half the mice were then infected with Escherichia coli O157:H7 and serum cytokines and total immunoglobulin A (IgA) were measured over the next 7 days. All whey products strongly stimulated total IgA production in non-infected mice, suggesting a potential adjuvant role. The peptide fractions produced contrasting immunomodulatory effects: the neutral fraction (4.5 < pH < 7) stimulated serum interferon-gamma (IFN-γ), whereas the acidic fraction (pH < 4.5) inhibited it. In the infected model, only the basic fraction (pH > 7) induced a sustained serum IgA secretion, which coincided with increased transforming growth factor-beta 1 (TGF-β1) levels. These results indicate that some whey peptides modulate immune parameters in healthy mice, whereas the basic peptide fraction increased immune vigilance during the infection.

C-Met Confers Protection Against Chronic Liver Tissue Damage and Fibrosis Progression After Bile Duct Ligation in Mice

The hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (c-Met) system is an essential inducer of hepatocyte growth and proliferation. Although a fundamental role for the HGF receptor c-Met has been shown in acute liver regeneration, its cell-specific role in hepatocytes during chronic liver injury and fibrosis progression has not been determined. Hepatocyte-specific c-Met knockout mice (c-Met(Delta hepa)) using the Cre-loxP system were studied in a bile duct ligation (BDL) model. Microarray analyses were performed to define HGF/c-Met-dependent gene expression. Two strategies for c-Met deletion in hepatocytes to generate hepatocyte-specific c-Met knockout mice were tested. Early deletion during embryonic development was lethal, whereas post-natal Cre expression was successful, leading to the generation of viable c-Met(Delta hepa) mice. BDL in these mice resulted in extensive necrosis and lower proliferation rates of hepatocytes. Gene array analysis of c-Met(Delta hepa) mice revealed a significant reduction of anti-apoptotic genes in c-Met-deleted hepatocytes. These findings could be tested functionally because c-Met(Delta hepa) mice showed a stronger apoptotic response after BDL and Jo-2 stimulation. The phenotype was associated with increased expression of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-6) and an enhanced recruitment of neutrophils. Activation of these mechanisms triggered a stronger profibrogenic response as evidenced by increased transforming growth factor-beta(1), alpha-smooth muscle actin, collagen-1alpha messenger RNA expression, and enhanced collagen-fiber staining in c-Met(Delta hepa) mice. Our results show that deletion of c-Met in hepatocytes leads to more liver cell damage and fibrosis in a chronic cholestatic liver injury model because c-Met triggers survival signals important for hepatocyte recovery.

TGF‐β and smad signalling in fibrosis

TGF‐β and smad signalling in fibrosis

The immunologic effect of TGF-beta1 chitosan nanoparticle plasmids on ovalbumin-induced allergic BALB/c mice

Studies suggested that an increased transforming growth factor-beta (TGF-beta) level in the intestinal tract helps to alleviate symptoms of food allergy. An efficient method for in vivo delivery of TGF-beta is yet to be developed. In this report, we investigated some DNA-based therapeutic strategies. Our results demonstrate that a sustainable increase of TGF-beta protein in mouse intestinal tissue can be induced after oral administration by gavage of a TGF-beta expressing DNA vector that was packed in chitosan nanoparticles. Concomitantly, a significant amelioration of ovalbumin-induced food allergy symptoms was observed. Thus, our study supports this therapy being perhaps a better alternative to the previously reported protein-based strategies.

151 A “Traffic Control” Role for TGF-Beta in Skin Cell Motility During Wound Healing

Skin wound healing requires temporally and spatially coordinated motility of multiple skin cell types. The limited success of current skin wound care is due to lack of understanding about how the healing processes begin, progress, and complete. One of the most dramatic environmental changes in an acute wound is the transition from plasma to serum. The cells in the wound come into contact with serum, instead of a filtrate of plasma, for the first time. We report here that this transition differentially regulates the migration of various skin cell types. Plasma promotes dermal fibroblast and endothelia cell, but not keratinocyte and melanocyte, motility. In contrast, serum selectively promotes keratinocyte motility and inhibits fibroblast and endothelial cell motility. The key regulators are the increased transforming growth factor-beta (TGF-beta) in serum and the distinct TGF-beta receptor (I, II and III) profiles in different cell types. TGF-beta selectively inhibits fibroblast and endothelial cell, but not keratinocyte and melanocyte, migration. Neutralization of TGF-beta function in serum eliminates the differential effects between serum and plasma. Manipulations of the TGF-beta receptor profiles in the cells, especially TGF-beta receptor II and III, convert TGF-beta-insensitive cell types to sensitive cell types and vice versa, and their responses to plasma and serum. This is the first study that reveals a molecular mechanism for coordinating multiple skin cell-type motility in wounds.

A Thrombospondin-1 Antagonist of Transforming Growth Factor-β Activation Blocks Cardiomyopathy in Rats with Diabetes and Elevated Angiotensin II

In diabetes and hypertension, the induction of increased transforming growth factor-beta (TGF-beta) activity due to glucose and angiotensin II is a significant factor in the development of fibrosis and organ failure. We showed previously that glucose and angiotensin II induce the latent TGF-beta activator thrombospondin-1 (TSP1). Because activation of latent TGF-beta is a major means of regulating TGF-beta, we addressed the role of TSP1-mediated TGF-beta activation in the development of diabetic cardiomyopathy exacerbated by abdominal aortic coarctation in a rat model of type 1 diabetes using a peptide antagonist of TSP1-dependent TGF-beta activation. This surgical manipulation elevates initial blood pressure and angiotensin II. The hearts of these rats had increased TSP1, collagen, and TGF-beta activity, and cardiac function was diminished. A peptide antagonist of TSP1-dependent TGF-beta activation prevented progression of cardiac fibrosis and improved cardiac function by reducing TGF-beta activity. These data suggest that TSP1 is a significant mediator of fibrotic complications of diabetes associated with stimulation of the renin-angiotensin system, and further studies to assess the blockade of TSP1-dependent TGF-beta activation as a potential antifibrotic therapeutic strategy are warranted.

Comparison of Airway Remodeling in Acute, Subacute, and Chronic Models of Allergic Airways Disease

The relationship between airway inflammation and structural changes of airway remodeling, and their relative effects on airway function, are poorly understood. Remodeling is thought to result from chronic repetitive injury to the airway wall caused by airway inflammation; however, the mechanisms regulating remodeling changes have not been clearly defined. We examined the sequence of events in remodeling using three commonly used mouse models of allergic airways disease in which mice are exposed to nebulized ovalbumin for four consecutive days (acute), seven consecutive days (subacute), or three times a week for 6 wk (chronic). Surprisingly, we found that a very short period of exposure to ovalbumin was sufficient to elicit early changes of remodeling. Goblet cell hyperplasia and epithelial thickening were evident after just 4 d. In chronically challenged mice, these changes persisted and, in addition, subepithelial collagen deposition was significantly increased. This collagen deposition was associated with a failure to upregulate matrix metalloproteinase (MMP)-2, in conjunction with increased transforming growth factor-beta and MMP-9 expression. The relationship between inflammation, remodeling changes, and airway hyperresponsiveness (AHR) were examined. The acute and subacute models exhibited marked airway inflammation, whereas the chronic model had very modest inflammation. Conversely, airway fibrosis was only evident in the chronic model. AHR was present in all three models; however, it was significantly higher in the chronic model compared with the acute (P<0.05) and subacute (P<0.05) models. These data demonstrate that both airway inflammation and airway fibrosis may contribute to AHR, with airway fibrosis leading to the greatest increases in AHR.

Molecular mechanisms of TGF-(beta) antagonism by interferon (gamma) and cyclosporine A in lung fibroblasts.

Lung fibrosis is a fatal condition of excess extracellular matrix (ECM) deposition associated with increased transforming growth factor beta (TGF-beta) activity. Although much is known about its pathological features, our understanding of the signal transduction pathways resulting in increased ECM and collagen deposition in response to TGF-beta is still incompletely defined. We have previously reported that a JunD homodimer of the transcription factor AP-1 is specifically activated by TGF-beta in lung fibroblasts. Here we demonstrate that JunD is also specifically required for TGF-beta-induced effects. Antisense against JunD, but not c-fos or c-jun, significantly inhibited collagen deposition in response to TGF-beta in primary human lung fibroblasts. We then investigated the ability of pharmacological agents to inhibit TGF-beta-induced signaling and collagen deposition. Cs-A and IFN-gamma, but not glucocorticoids, cyclophosphamide, or azathioprine, inhibited TGF-beta-induced signaling, as assessed by luciferase reporter gene assays, and collagen deposition. TGF-beta antagonism by Cs-A was associated with direct inhibition of JunD activation, as demonstrated by electrophoretic mobility shift analyses. In contrast, the effects of IFN-gamma required signal transducer and activator of transcription (STAT)-1. We thus identify the JunD isoform of AP-1 as an essential mediator of TGF-beta-induced effects in lung fibroblasts. TGF-beta-induced signaling and collagen deposition are efficiently antagonized by Cs-A and IFN-gamma treatment, both of which exhibit distinct molecular mechanisms of action. These observations therefore offer novel targets for future therapy of fibrotic lung disease.