endothelin-1 and Pulmonary-Fibrosis

The endothelin system participates in a number of critical biologic pathways, including normal wound healing. In addition, emerging basic science, and animal and human data all suggest that endothelin-1 (EDN1, also known as ET-1) is a potentially important contributor in the pathobiology of fibrosing disorders, including those that affect the lung. For example, EDN1 drives fibroblast activation, proliferation, as well as differentiation into myofibroblasts - processes that lead to excessive collagen deposition. Patients with idiopathic pulmonary fibrosis (IPF) have increased levels of EDN1 in both their bronchoalveolar lavage fluid and lung tissue. Beyond this, rodent models suggest that endothelin receptor antagonists can limit bleomycin-induced lung fibrosis. This suggests a biologic rationale for the blockade of EDN1 to limit the evolution of lung fibrosis in humans. Initial results from a trial examining the efficacy of a dual endothelin receptor antagonist suggest that this approach may delay disease progression in a subset of patients with IPF.

Topics: Animals; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Endothelin-1; Endothelins; Humans; Lung; Pulmonary Fibrosis; Wound Healing

Idiopathic pulmonary fibrosis (IPF) is a debilitating, fatal, chronic fibrosing lung disease with no known effective therapy. Endothelin-1 may underlie the pathogenesis of lung fibrosis, therefore it was hypothesized that the oral dual endothelin receptor antagonist bosentan may have efficacy for the treatment of IPF. The BUILD-1 study evaluated the efficacy, safety and tolerability of bosentan in patients with IPF. Bosentan was associated with a trend toward delayed time to disease progression or death and improvement in quality-of-life, both of which were more pronounced in patients with a biopsy-confirmed IPF diagnosis. These observations are being investigated in the ongoing BUILD-3 trial.

Topics: Animals; Bosentan; Endothelin Receptor Antagonists; Endothelin-1; Humans; Hypertension, Pulmonary; Pulmonary Fibrosis; Randomized Controlled Trials as Topic; Sulfonamides

Since the identification of endothelin as a key mediator in the pathogenesis of several diseases, including pulmonary arterial hypertension (PAH), the pharmacologic control of the activated endothelin system with endothelin receptor antagonists (ETRA) has been a major therapeutic achievement for the treatment of patients with PAH. To date, dual ET(A)/ET(B) and selective ET(A) receptor antagonists have clinically been evaluated. To answer the question of whether selective or dual ETRA is preferable in patients with PAH, experimental and clinical data with relevance to the pulmonary circulation are reviewed in this article. Whereas experimental and clinical data provide unambiguous evidence that ET(A) receptors mediate the detrimental effects of ET-1, such as vasoconstriction and cell proliferation, the elucidation of the role of ET(B) receptors has been more complex. It has been shown that there is a subpopulation of ET(B) receptors on smooth muscle cells and fibroblasts mediating vasoconstriction and proliferation. On the contrary, there is clear evidence that endothelial ET(B) receptors continue to mediate vasodilation, vasoprotection and ET-1 clearance despite the pathology associated with pulmonary hypertension. More difficult to assess is the net effect of these mechanisms in patients to be treated with ETRA. When considering the available data from controlled clinical trials, nonselectivity does not appear to carry a relevant clinical benefit for the treatment of patients with PAH when compared with selective ET(A) receptor antagonism.

Topics: Antihypertensive Agents; Bosentan; Cell Division; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin Receptor Antagonists; Endothelin-1; Humans; Hypertension, Pulmonary; Isoxazoles; Lung; Pulmonary Fibrosis; Sulfonamides; Thiophenes; Vasoconstriction; Vasodilation

Idiopathic pulmonary fibrosis (IPF) is a progressive, fibrosing disease of the distal air spaces of the lung of unknown aetiology. IPF is usually fatal with a median survival of < 3 years. There are currently no effective pharmacotherapeutic agents for the treatment of IPF. In this review, unifying concepts on the pathogenesis of IPF based on understanding of host responses to tissue injury are presented. These host responses involve tightly regulated and contextually orchestrated inflammatory and repair processes. Dysregulation of either of these processes can lead to pathological outcomes. Fibrosis results from an exaggerated or dysregulated repair process that proceeds 'uncontrolled' even after inflammatory responses have subsided. Disease heterogeneity may arise when inflammation and repair are in different (dys)regulatory phases, thus accounting for regional disparity. Usual interstitial pneumonia (UIP), the histopathological correlate of clinical IPF, represents a more fibrotic tissue reaction pattern and for which anti-inflammatory agents are ineffective. Emerging 'antifibrotic' drugs and strategies for UIP/IPF are discussed. The importance of accurately phenotyping a highly heterogeneous disease process that may require individualised and 'combined' therapies is emphasised.

Topics: Acetylcysteine; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antibodies, Monoclonal; Connective Tissue Growth Factor; Eicosanoids; Endothelin-1; Humans; Immediate-Early Proteins; Intercellular Signaling Peptides and Proteins; Interferon-gamma; Molybdenum; Protein Kinase Inhibitors; Proteins; Pulmonary Fibrosis; Pyridones; Recombinant Proteins; Relaxin; Renin-Angiotensin System; Tumor Necrosis Factor-alpha

Topics: Angiotensin II; Animals; Cell Division; Collagen; Endothelin-1; Extracellular Matrix; Fibroblast Growth Factor 2; Fibroblasts; Glomerulosclerosis, Focal Segmental; Humans; Hypertension; Liver Cirrhosis; Myoblasts, Cardiac; Myocardial Infarction; Pulmonary Fibrosis; Receptors, Endothelin; Transforming Growth Factor beta; Ventricular Remodeling

Idiopathic pulmonary fibrosis (IPF) is a chronic and usually progressive lung disorder of unknown aetiology. Conventional management of patients with IPF has been primarily based on the concept that suppressing inflammation would prevent progression to fibrosis. Although the pathogenesis is incompletely understood, it is here suggested that IPF is a disease of abnormal wound repair and remodelling in the lung rather than an inflammatory disease. Therefore, treatment strategies are no longer aimed at reducing inflammation, but rather at preventing or inhibiting the fibroproliferative responses and enhancing efficient alveolar epithelial repair. So far, no cell-specific drugs for these purposes are clinically available. However, novel promising molecules or drugs are being studied in experimental models or ongoing clinical trials in patients with IPF. Evolving hypotheses on the pathogenesis of IPF are reviewed, focusing on possible implications for future therapies. A better understanding of the sequence of the pathogenic mechanisms that control the fibrotic response will hopefully lead to efficient therapies and finally a favourable outcome in patients with this disease.

Topics: Animals; Apoptosis; Cytokines; Endothelin-1; Epithelium; Fibrinolysis; Fibroblasts; Humans; Inflammation; Plasminogen Activator Inhibitor 1; Pulmonary Alveoli; Pulmonary Fibrosis; Signal Transduction; Wound Healing

Topics: Animals; Cytokines; Endothelin-1; Humans; Inflammation; Lung; Mice; Mice, Transgenic; Pulmonary Fibrosis; Receptors, Endothelin; T-Lymphocyte Subsets

Pulmonary fibrosis can complicate diverse pulmonary and systemic pathologies. In many cases the underlying cause remains unidentified. Mortality from the disease is increasing steadily in the UK and USA. The clinical features are well-described, but patients frequently present at an advanced stage, and current treatments have not improved the poor prognosis. There is a compelling need to identify the fibrotic process earlier and to develop new therapeutic agents. Increased collagen deposition is central to the pathology and interest over the last decade has focused on the role of cytokines in this process. These polypeptide mediators are believed to be released from both circulating inflammatory and resident lung cells in response to endothelial and epithelial injury. Key cytokines currently implicated in the fibrotic process are transforming growth factor-beta, tumour necrosis factor-alpha and endothelin-1. This article outlines the evidence implicating these mediators in the pathogenesis of pulmonary fibrosis and also considers the possible role of cytokines with antifibrotic effects, such as interferon-gamma. The "balance" of positively and negatively regulating cytokines is discussed, and the potential for interaction with other factors including viruses, hormones and altered antioxidant status is also considered. Finally, potential novel therapeutic approaches are discussed, together with suggestions for future studies and clinical trials. As the outcomes of different avenues of research over the last ten years are brought together, it is clear that there is now a hitherto unrivalled opportunity to begin to tackle the treatment of this devastating disease.

Topics: Animals; Cytokines; Endothelin-1; Humans; Pulmonary Fibrosis; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Reduction of histone deacetylase (HDAC) 2 expression and activity may contribute to amplified inflammation in patients with severe asthma. Connective tissue growth factor (CTGF) is a key mediator of airway fibrosis in severe asthma. However, the role of the HDAC2/Sin3A/methyl-CpG-binding protein (MeCP) 2 corepressor complex in the regulation of CTGF expression in lung fibroblasts remains unclear.. The role of the HDAC2/Sin3A/MeCP2 corepressor complex in endothelin (ET)-1-stimulated CTGF production in human lung fibroblasts (WI-38) was investigated. We also evaluated the expression of HDAC2, Sin3A and MeCP2 in the lung of ovalbumin-induced airway fibrosis model.. HDAC2 suppressed ET-1-induced CTGF expression in WI-38 cells. ET-1 treatment reduced HDAC2 activity and increased H3 acetylation in a time-dependent manner. Furthermore, overexpression of HDAC2 inhibited ET-1-induced H3 acetylation. Inhibition of c-Jun N-terminal kinase, extracellular signal-regulated kinase, or p38 attenuated ET-1-induced H3 acetylation by suppressing HDAC2 phosphorylation and reducing HDAC2 activity. Overexpression of both Sin3A and MeCP2 attenuated ET-1-induced CTGF expression and H3 acetylation. ET-1 induced the disruption of the HDAC2/Sin3A/MeCP2 corepressor complex and then prompted the dissociation of HDAC2, Sin3A, and MeCP2 from the CTGF promoter region. Overexpression of HDAC2, Sin3A, or MeCP2 attenuated ET-1-stimulated AP-1-luciferase activity. Moreover, Sin3A- or MeCP2-suppressed ET-1-induced H3 acetylation and AP-1-luciferase activity were reversed by transfection of HDAC2 siRNA. In an ovalbumin-induced airway fibrosis model, the protein levels of HDAC2 and Sin3A were lower than in the control group; however, no significant difference in MeCP2 expression was observed. The ratio of phospho-HDAC2/HDAC2 and H3 acetylation in the lung tissue were higher in this model than in the control group. Overall, without stimulation, the HDAC2/Sin3A/MeCP2 corepressor complex inhibits CTGF expression by regulating H3 deacetylation in the CTGF promoter region in human lung fibroblasts. With ET-1 stimulation, the HDAC2/Sin3A/MeCP2 corepressor complex is disrupted and dissociated from the CTGF promoter region; this is followed by AP-1 activation and the eventual initiation of CTGF production.. The HDAC2/Sin3A/MeCP2 corepressor complex is an endogenous inhibitor of CTGF in lung fibroblasts. Additionally, HDAC2 and Sin3A may be of greater importance than MeCP2 in the pathogenesis of airway fibrosis.

Topics: Asthma; Co-Repressor Proteins; Connective Tissue Growth Factor; Endothelin-1; Fibroblasts; Histone Deacetylase 2; Humans; Luciferases; Lung; Ovalbumin; Pulmonary Fibrosis; Transcription Factor AP-1

Heart failure with reduced ejection fraction (HFrEF) causes lung remodelling with myofibroblasts proliferation and fibrosis leading to a restrictive lung syndrome with pulmonary hypertension (PH) and right ventricular (RV) dysfunction. PBI-4050 is a first-in-class anti-fibrotic, anti-inflammatory, and anti-proliferative compound. The present study evaluated the therapeutic impact of PBI-4050 on PH in an HFrEF model.. HFrEF was induced after myocardial infarction (MI) in rats. Two weeks later, sham-operated and MI groups received PBI-4050 (200 mg/kg/day by gavage) or saline for 3 weeks. Animals were analysed according to infarct size as large (≥30% left ventricle) or medium MI (<30%). Large MI caused PH and RV hypertrophy (RVH) with a restrictive lung syndrome. PBI-4050 did not adversely affect left ventricular (LV) function but markedly reduced PH and RVH and improved RV dysfunction. PBI-4050 reduced lung remodelling and improved respiratory compliance with decreased lung fibrosis, alveolar wall cellular proliferation and α-smooth muscle actin expression. The increased expression of endothelin-1 (ET-1), transforming growth factor beta (TGF-β), interleukin-6 (IL-6) and of tissue inhibitor of metalloprotease-1 in the lungs from HFrEF were reduced with PBI-4050 therapy. Activation of isolated human lung fibroblasts (HLFs) to a myofibroblastic pro-fibrogenic phenotype was markedly reduced by PBI-4050. The fatty acid receptor GPR84 was increased in HFrEF lungs and in activated HLFs, and reduced by PBI-4050. GPR84 agonists activated fibrogenesis in HLFs and finally, PBI-4050 reduced ERK1/2 phosphorylation.. PBI-4050 reduces PH and RVH in HFrEF by decreasing lung fibrosis and remodelling. This novel agent decreases the associated restrictive lung syndrome and recovers RV function. A contributing mechanism involves reducing the activation of lung fibroblasts by IL-6, TGF-β, and ET-1 by antagonism of GPR84 and reduced ERK1/2 phosphorylation. PBI-4050 is a novel promising therapy for targeting lung remodelling in group II PH.

Topics: Acetates; Animals; Cells, Cultured; Disease Models, Animal; Endothelin-1; Extracellular Signal-Regulated MAP Kinases; Fibroblasts; Fibrosis; Heart Failure; Heart Ventricles; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Interleukin-6; Lung; Male; Phosphorylation; Pulmonary Fibrosis; Rats, Wistar; Receptors, G-Protein-Coupled; Signal Transduction; Transforming Growth Factor beta; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling

A number of studies indicate that endothelin-1 (ET-1) may act as an inflammatory cell "gatekeeper," by regulating the influx of neutrophils following pulmonary injury. To further examine the role of ET-1 in modulating lung inflammation, hamsters were treated with an endothelin receptor antagonist (ERA), HJP272, either 1 h prior to intratracheal instillation of amiodarone (AM) or 24 h afterwards.. In both cases, the extent of lung injury and repair was determined by (1) histopathological changes; (2) neutrophil content in bronchoalveolar lavage fluid (BALF); (3) lung collagen content; (4) tumor necrosis factor receptor 1 expression by BALF macrophages; (5) BALF levels of (a) transforming growth factor beta-1, (b) stromal cell-derived factor 1 (commonly referred to as CXCL12), and (c) platelet-derived growth factor BB; (6) alveolar septal cell apoptosis.. For each parameter, pretreatment with HJP272 resulted in a significant reduction compared to AM alone, whereas post-treatment was either ineffective or produced only a marginally significant change, suggesting that the course of lung inflammation and repair is programmed at a very early stage.. This finding may explain why ERAs are not an effective treatment for human pulmonary fibrosis. Nevertheless, they may be useful as an adjunct to therapeutic regimens involving drugs that have fibrogenic potential.

Topics: Amiodarone; Animals; Apoptosis; Becaplermin; Bronchoalveolar Lavage Fluid; Chemokine CXCL12; Collagen; Endothelin Receptor Antagonists; Endothelin-1; Female; Hydroxyquinolines; Lung; Macrophages; Mesocricetus; Neutrophils; Pulmonary Alveoli; Pulmonary Fibrosis; Receptors, Tumor Necrosis Factor, Type I; Transforming Growth Factor beta1; Vasodilator Agents

Endothelin-1 (ET-1) induces pulmonary vascular remodeling and pulmonary hypertension secondary to pulmonary fibrosis. Given that endothelial cells are the main source of ET-1 and ET-1 from other cells may encounter difficulty penetrating vascular compartments, we hypothesize that endothelial-derived ET-1 promotes vascular remodeling secondary to pulmonary fibrosis. We used vascular endothelial ET-1 knock-out (VEETKO) and Wild type mice for this research. They were given intratracheal bleomycin and euthanized at day 28. We quantified pulmonary fibrosis, measured lung ET-1 and its receptors' expression, and assessed pulmonary vascular remodeling by calculating medial wall index, muscularization index, adventitial collagen and adventitial fibroblast and macrophage accumulation. Right ventricle remodeling was also assessed. Both VEETKO and Wild type mice developed comparable pulmonary fibrosis and similar fibrosis-related gene expression. Compared to Wild type mice, bleomycin-induced VEETKO mice had lower ET-1 peptide levels (15.4 pg/mg vs. 31.2 pg/mg, p<0.01). Expression of both ET-1 receptors mRNAs were increased in fibrosis models. Bleomycin-induced fibrosis VEETKO mice had significantly less muscularized arterioles, lower muscularization index and attenuated adventitial collagen, fibroblast and macrophage accumulation as compared to that of Wild type mice. Right ventricular pressure, hypertrophy and fibrosis did not increase both in VEETKO and Wild type mice despite the more enhanced vascular remodeling in Wild type. In conclusion, endothelial-derived endothelin-1 promotes pulmonary vascular remodeling secondary to bleomycin-induced pulmonary fibrosis.

Topics: Animals; Bleomycin; Endothelin-1; Endothelium, Vascular; Mice; Mice, Knockout; Mice, Transgenic; Pulmonary Artery; Pulmonary Fibrosis; Vascular Remodeling

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.

Topics: Acute Lung Injury; Animals; Bleomycin; Bronchoalveolar Lavage Fluid; Cricetinae; Disease Models, Animal; Endothelin-1; Female; Humans; Hydroxyquinolines; In Situ Nick-End Labeling; Lipopolysaccharides; Macrophages; Mesocricetus; Neutrophils; Pulmonary Fibrosis; Time Factors

Limited literature sources implicate mast-cell mediator chymase in the pathologies of pulmonary hypertension and pulmonary fibrosis. However, there is no evidence on the contribution of chymase to the development of pulmonary hypertension associated with lung fibrosis, which is an important medical condition linked with increased mortality of patients who already suffer from a life-threatening interstitial lung disease.The aim of this study was to investigate the role of chymase in this particular pulmonary hypertension form, by using a bleomycin-induced pulmonary hypertension model.Chymase inhibition resulted in attenuation of pulmonary hypertension and pulmonary fibrosis, as evident from improved haemodynamics, decreased right ventricular remodelling/hypertrophy, pulmonary vascular remodelling and lung fibrosis. These beneficial effects were associated with a strong tendency of reduction in mast cell number and activity, and significantly diminished chymase expression levels. Mechanistically, chymase inhibition led to attenuation of transforming growth factor β1 and matrix-metalloproteinase-2 contents in the lungs. Furthermore, chymase inhibition prevented big endothelin-1-induced vasoconstriction of the pulmonary arteries.Therefore, chymase plays a role in the pathogenesis of pulmonary hypertension associated with pulmonary fibrosis and may represent a promising therapeutic target. In addition, this study may provide valuable insights on the contribution of chymase in the pulmonary hypertension context, in general, regardless of the pulmonary hypertension form.

Topics: Animals; Bleomycin; Chymases; Disease Models, Animal; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Hemodynamics; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Lung; Mast Cells; Matrix Metalloproteinase 2; Mesocricetus; Pulmonary Artery; Pulmonary Fibrosis; Radioimmunoassay; Random Allocation; Transforming Growth Factor beta1

Combined pulmonary fibrosis and emphysema (CPFE) is a computed tomography (CT)-defined syndrome of combined pulmonary fibrosis and emphysema, characterized by subnormal spirometry, impairment of gas exchange, and high prevalence of pulmonary hypertension. Although endothelin-1 (ET-1) plays an important role in the development of lung fibrosis as well as in pulmonary hypertension, no ET-1-targeted therapy is currently recommended. Here we report a case of CPFE successfully treated with ambrisentan, an endothelin-A receptor antagonist, and also discuss the biologic mechanisms underlying the observed therapeutic effects. A 79-year-old man with chronic obstructive pulmonary disease (COPD) was referred to our respiratory unit as an outpatient for dyspnea. Clinical, radiologic, and laboratory findings suggested a diagnosis of chronic hypoxemic, type 1 respiratory failure, due to combined pulmonary fibrosis and emphysema, complicated by severe, precapillary pulmonary hypertension. Pharmacologic treatment with ambrisentan induced an initial improvement in clinical symptoms that proved to be very relevant 9 months later. In order to investigate the biologic mechanisms underlying the clinical effects of ambrisentan, we performed an "in vitro" study on primary cultures of fibrotic human lung fibroblasts, as well as on human umbilical vein endothelial cells, incubated for 24 and 48 h with ET-1, in the absence or presence of an overnight treatment with ambrisentan. ET-1 significantly increased cell proliferation and mitogen-activated protein kinase activation (P < 0.01). These effects were significantly (P < 0.01) inhibited by ambrisentan in both cell cultures. In conclusion, we hypothesize that the clinical benefits induced by ambrisentan in this patient with CPFE can be attributed to its vasodilator and anti-proliferative actions, exerted on pulmonary the vascular bed and lung fibroblasts.

Topics: Aged; Emphysema; Endothelin A Receptor Antagonists; Endothelin-1; Human Umbilical Vein Endothelial Cells; Humans; Hypertension, Pulmonary; Male; Phenylpropionates; Pulmonary Disease, Chronic Obstructive; Pulmonary Fibrosis; Pyridazines; Severity of Illness Index; Tomography, X-Ray Computed; Treatment Outcome

Pulmonary fibrosis is a chronic disease. Urotensin II (U-II) is a new peptide with angiogenic and profibrotic features. Therefore, we aim to evaluate the antagonism of U-II with palosuran in an animal model and plan to measure U-II, endothelin-1 (ET-1), and transforming growth factor-β1 (TGF-β1) and their association with lung fibrosis. Thirty Wistar male rats were used in the study and were divided into three groups: group 1, control; group 2, bleomycin-induced lung fibrosis group; and group 3, bleomycin-induced lung fibrosis with treatment palosuran group. U-II level (nanograms per milliliter) was 2.957 ± 0.159 in group1, 3.188 ± 0.122 in group 2, and 2.970 ± 0.165 in group 3 (p = 0.002). The ET-1 level (picograms per milliliter) was 4.486 ± 0.376 in group 1, 9.086 ± 1.850 in group 2, and 4.486 ± 0.376 in group 3 (p < 0.001). The TGF-β1 (nanograms per milliliter) level was 73.143 ± 9.96 in group 1, 84.81 ± 4.73 in group 2, and 77.86 ± 5.77 in group 3 (p = 0.006). Finally, the fibrosis score was 0.7 ± 0.48 in group 1, 4.4 ± 1.34 in group 2, and 3.2 ± 0.63 in group 3 (p < 0.001). There is a statistically significant positive relationship between fibrosis scores and the UT-II, ET-1, and TGF-β1 levels of the experimental lung fibrosis model. We believe U-II is an important mediator in lung fibrosis models, and its antagonism with palosuran could be a new treatment choice for interstitial lung fibrosis, but further studies need to be conducted to verify the findings of the current study.

Topics: Animals; Bleomycin; Endothelin-1; Lung; Male; Pulmonary Fibrosis; Quinolines; Random Allocation; Rats; Rats, Wistar; Transforming Growth Factor beta1; Urea; Urotensins

Development of pulmonary hypertension is a common and deadly complication of interstitial lung disease. Little is known regarding the cellular and molecular mechanisms that lead to pulmonary hypertension in patients with interstitial lung disease, and effective treatment options are lacking. The purpose of this study was to examine the adenosine 2B receptor (A(2B)R) as a regulator of vascular remodeling and pulmonary hypertension secondary to pulmonary fibrosis. To accomplish this, cellular and molecular changes in vascular remodeling were monitored in mice exposed to bleomycin in conjunction with genetic removal of the A(2B)R or treatment with the A(2B)R antagonist GS-6201. Results demonstrated that GS-6201 treatment or genetic removal of the A(2B)R attenuated vascular remodeling and hypertension in our model. Furthermore, direct A(2B)R activation on vascular cells promoted interleukin-6 and endothelin-1 release. These studies identify a novel mechanism of disease progression to pulmonary hypertension and support the development of A(2B)R antagonists for the treatment of pulmonary hypertension secondary to interstitial lung disease.

Topics: Adenosine-5'-(N-ethylcarboxamide); Animals; Bleomycin; Cells, Cultured; Endothelin-1; Endothelium, Vascular; Humans; Hypertension, Pulmonary; Interleukin-6; Lung Diseases, Interstitial; Male; Mice; Mice, Inbred C57BL; Pulmonary Fibrosis; Purinergic P1 Receptor Agonists; Purines; Pyrazoles; Receptor, Adenosine A2B

Small airway narrowing is an important pathology which impacts lung function in chronic obstructive pulmonary disease (COPD). The accumulation of fibroblasts and myofibroblasts contribute to inflammation, remodeling and fibrosis by production and release of mediators such as cytokines, profibrotic factors and extracellular matrix proteins. This study investigated the effects of the phosphodiesterase 4 inhibitor roflumilast, combined with the long acting β2 adrenergic agonist indacaterol, both approved therapeutics for COPD, on fibroblast functions that contribute to inflammation and airway fibrosis.. The effects of roflumilast and indacaterol treatment were characterized on transforming growth factor β1 (TGFβ1)-treated normal human lung fibroblasts (NHLF). NHLF were evaluated for expression of the profibrotic mediators endothelin-1 (ET-1) and connective tissue growth factor (CTGF), expression of the myofibroblast marker alpha smooth muscle actin, and fibronectin (FN) secretion. Tumor necrosis factor-α (TNF-α) was used to induce secretion of chemokine C-X-C motif ligand 10 (CXCL10), chemokine C-C motif ligand 5 (CCL5) and granulocyte macrophage colony-stimulating factor (GM-CSF) from NHLF and drug inhibition was assessed.. Evaluation of roflumilast (1-10 μM) showed no significant inhibition alone on TGFβ1-induced ET-1 and CTGF mRNA transcripts, ET-1 and FN protein production, alpha smooth muscle expression, or TNF-α-induced secretion of CXCL10, CCL5 and GM-CSF. A concentration-dependent inhibition of ET-1 and CTGF was shown with indacaterol treatment, and a submaximal concentration was chosen for combination studies. When indacaterol (0.1 nM) was added to roflumilast, significant inhibition was seen on all inflammatory and fibrotic mediators evaluated, which was superior to the inhibition seen with either drug alone. Roflumilast plus indacaterol combination treatment resulted in significantly elevated phosphorylation of the transcription factor cAMP response element-binding protein (CREB), an effect that was protein kinase A-dependent. Inhibition of protein kinase A was also found to reverse the inhibition of indacaterol and roflumilast on CTGF.. These results demonstrate that addition of roflumilast to a LABA inhibits primary fibroblast/myofibroblast function and therapeutically this may impact lung fibroblast proinflammatory and profibrotic mediator release which contributes to small airway remodeling and airway obstruction in COPD.

Topics: Actins; Adrenergic beta-2 Receptor Agonists; Aminopyridines; Benzamides; Cells, Cultured; Chemokine CCL5; Chemokine CXCL10; Connective Tissue Growth Factor; Cyclopropanes; Endothelin-1; Fibroblasts; Fibronectins; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Indans; Inflammation; Lung; Phosphodiesterase 4 Inhibitors; Pulmonary Fibrosis; Quinolones; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha

Enhanced adhesive signaling, including activation of focal adhesion kinase (FAK), is a hallmark of fibroblasts from lung fibrosis patients, and FAK has therefore been hypothesized to be a key mediator of this disease. This study was undertaken to characterize the contribution of FAK to the development of pulmonary fibrosis both in vivo and in vitro.. FAK expression and activity were analyzed in lung tissue samples from lung fibrosis patients by immunohistochemistry. Mice orally treated with the FAK inhibitor PF-562,271, or with small interfering RNA (siRNA)-mediated silencing of FAK were exposed to intratracheally instilled bleomycin to induce lung fibrosis, and lungs were harvested for histologic and biochemical analysis. Using endothelin 1 (ET-1) as a stimulus, cell adhesion and contraction, as well as profibrotic gene expression, were studied in fibroblasts isolated from wild-type and FAK-deficient mouse embryos. ET-1-mediated FAK activation and gene expression were studied in primary mouse lung fibroblasts, as well as in wild-type and β1 integrin-deficient mouse fibroblasts.. FAK expression and activity were up-regulated in fibroblast foci and remodeled vessels from lung fibrosis patients. Pharmacologic or siRNA-mediated targeting of FAK resulted in marked abrogation of bleomycin-induced lung fibrosis in mice. Loss of FAK impaired the acquisition of a profibrotic phenotype in response to ET-1. Profibrotic gene expression leading to myofibroblast differentiation required cell adhesion, and was driven by JNK activation through β1 integrin/FAK signaling.. These results implicate FAK as a central mediator of fibrogenesis, and highlight this kinase as a potential therapeutic target in fibrotic diseases.

Topics: Animals; Cell Adhesion; Cells, Cultured; Disease Models, Animal; Endothelin-1; Enzyme Inhibitors; Female; Focal Adhesion Protein-Tyrosine Kinases; Gene Silencing; Humans; Indoles; Lung; Male; Mice; Middle Aged; Myofibroblasts; Pulmonary Fibrosis; RNA, Small Interfering; Sulfonamides; Up-Regulation

Endothelin-1 (ET-1) has been implicated in the development of pulmonary fibrosis, based on its capacity in vitro to promote extracellular matrix (ECM) production and contraction, and on studies showing elevated expression of ET-1 and its receptors in patients with pulmonary fibrosis. However, the in vivo fibrogenic effect of ET-1 is not well characterized. We used the adenoviral-mediated gene transfer of ET-1 to overexpress ET-1 transiently in murine lungs by intratracheal administration. An increased expression of ET-1 for 3 to 10 days after injection resulted in a moderate but reversible fibrotic response, peaking on Day 14 after infection and characterized by the deposition of ECM components, myofibroblast formation, and a significant inflammatory infiltrate, mainly in the peribronchiolar/perivascular region. Adenoviral-mediated ET-1 overexpression activated focal adhesion kinase (FAK) both in vitro, using primary murine lung fibroblasts, and in vivo, intratracheally administered in the lungs of mice. The inhibition of FAK with the compound PF-562,271 prevented ET-1-mediated collagen deposition and myofibroblast formation, thereby preventing the development of lung fibrosis. In conclusion, we demonstrate that the overexpression of ET-1 directly in the lungs of mice can initiate a fibrogenic response characterized by increased ECM deposition and myofibroblast formation, and that this effect of ET-1 can be prevented by inhibition of FAK. Our data suggest that the ET-1/FAK axis may contribute importantly to the pathogenesis of fibrotic disorders, and highlight FAK as a potential therapeutic target in these devastating diseases.

Topics: Adenoviridae; Animals; B-Lymphocytes; Cell Differentiation; Cells, Cultured; Endothelin-1; Enzyme Activation; Focal Adhesion Protein-Tyrosine Kinases; Genetic Vectors; Humans; Indoles; Lung; Mice; Mice, Inbred C57BL; Myofibroblasts; Phosphorylation; Protein Processing, Post-Translational; Pulmonary Fibrosis; Recombinant Proteins; Scleroderma, Systemic; Sulfonamides; T-Lymphocytes

Alteration in the control of bone morphogenetic protein (BMP)-regulated genes and increased expression of endothelin (ET)-1 are both believed to play important roles in the still incompletely understood pathobiology of pulmonary vascular remodeling and fibrosis. Recent studies have drawn attention to the contribution of adventitial fibroblast activation in these phenomena. Because chloride channels are involved in the control of physiological function of fibroblasts, we hypothesized that these channels are differentially regulated by BMPs and ET. We measured chloride ion currents by whole-cell path-clamping in cultured primary human pulmonary fibroblasts. The application of BMP2 prevented activation of these currents by hypotonic challenge in a time- and dose-dependent manner, partially via protein kinase C signaling. Maximal inhibition was observed after 45-minute incubation of cells in the presence of 10 ng/ml of BMP2. ET-1 did not activate chloride channels acutely; however, prolonged treatment of cells with ET-1 (100 nM, 2 h) induced the appearance of lysophosphatidic acid-activated chloride currents (a marker of differentiated myofibroblasts), and this induction could be effectively blocked by BMP2 pretreatment (10 ng/ml). BMP2 also prevented stimulation of α-smooth muscle actin gene expression and cell migration of fibroblasts induced by ET-1. We conclude that ET-1 and BMP2 have opposing effects on chloride channel activity in human fibroblasts. This is a potentially relevant mechanism involved in pulmonary vascular remodeling and fibrosis.

Topics: Actins; Antigens, Differentiation; Bone Morphogenetic Protein 2; Cell Line; Chlorides; Endothelin-1; Fibroblasts; Gene Expression Regulation; Humans; Ion Transport; Protein Kinase C; Pulmonary Fibrosis; Signal Transduction

In this study, we evaluated the potential anti-fibrotic property of neferine, a bisbenzylisoquinline alkaloid extracted from the seed embryo of Nelumbo mucifera Gaertn. Intratracheal bleomycin administration resulted in pulmonary fibrosis 14 and 21 days posttreatment, as evidenced by increased hydroxyproline content in bleomycin group (255.77+/-97.17 microg/lung and 269.74+/-40.92 microg/lung) compared to sham group (170.78+/-76.46 microg/lung and 191.24+/-60.45 microg/lung), and the hydroxyproline was significantly suppressed (193.07+/-39.55 microg/lung and 201.08+/-71.74 microg/lung) by neferine administration (20mg/kg, b.i.d). The attenuated-fibrosis condition was also validated by histological observations. Biochemical measurements revealed that bleomycin caused a significant decrease in lung superoxidae dismutase (SOD) activity, which was accompanied with a significant increase in malondialdehyde (MDA) levels and myeloperoxidase (MPO) activity on the 7th and 14th days. However, neferine reversed the decrease in SOD activity as well as the increase in MDA and MPO activity. Enzyme-linked immunosorbent assay and radio-immunity assay showed that treatment with neferine alleviated bleomycin-induced increase of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and endothelin-1 in plasma or in tissue. Additionally, neferine blocked bleomycin-induced increases of NF-kappaB in nuclear extracts and TGF-beta(1) in total protein extracts of murine RAW264.7 macrophages. In summary, neferine attenuates bleomycin-induced pulmonary fibrosis in vitro and in vivo. The beneficial effect of neferine might be associated with its activities of anti-inflammation, antioxidation, cytokine and NF-kappaB inhibition.

Topics: Animals; Benzylisoquinolines; Bleomycin; Cell Line; Cell Proliferation; Cytokines; Endothelin-1; Gene Expression Regulation; Hydroxyproline; Inflammation; Interleukin-6; Mice; NF-kappa B; Oxidative Stress; Pulmonary Fibrosis; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha

Exposure to allergens or air pollutants often leads to asthma exacerbations associated with aggravation of airway inflammation. Although, repeated allergen challenge often induces chronic allergic airway inflammation (CAAI) and airway remodelling, yet, the effects of brief exposure to air pollutants such as SO(2) on development of CAAI and airway remodelling remain to be clarified.. The aim of the experiment was to investigate the effects of acute neutrophilic airway inflammation induced by brief exposure to SO(2) on development of CAAI and subepithelial fibrosis (SEF) in a murine model of asthma.. Acute airway inflammation was induced by brief exposure to 50 p.p.m. SO(2) (1 h/d, 3 days). CAAI and SEF in BALB/c mice were induced by repeated challenge with ovalbumin (OVA) for 5 or 9 weeks with or without prior exposure to SO(2). Bronchoalveolar lavage fluid (BALF) eosinophilia as index of CAAI, BALF endothelin-1 (ET-1) and TGF-beta1 levels, morphometric evaluation of fibrotic area beneath subbasement membrane and lung hydroxyproline content (Hyp) as indexes of SEF were monitored.. Exposure to SO(2) led to acute neutrophilic inflammation and epithelial sloughing with profound elevation of BALF ET-1. Repeated OVA challenge resulted in CAAI and SEF along with elevation of Hyp, increase of fibrotic area beneath subbasement membrane and elevation of BALF TGF-beta1. Preceding SO(2) exposure exaggerated BALF eosinophilia, facilitated and enhanced SEF with more significant elevation of BALF ET-1 and TGF-beta1 levels compared with OVA-challenged mice without prior exposure to SO(2). The increase of Hyp was positively correlated with elevation of BALF TGF-beta1 during CAAI (r=0.842, P<0.01).. This data demonstrated that SEF developed in parallel with severity and time course of CAAI following repeated OVA challenge. SO(2)-induced acute epithelial injury and neutrophilic inflammation could enhance CAAI and promote SEF, probably through overexpression of ET-1 and TGF-beta1.

Topics: Air Pollutants; Allergens; Animals; Bronchitis; Bronchoalveolar Lavage Fluid; Chronic Disease; Endothelin-1; Female; Lung; Mice; Mice, Inbred BALB C; Neutrophils; Ovalbumin; Pulmonary Fibrosis; Respiratory Mucosa; Sulfur Dioxide; Transforming Growth Factor beta

Growth of fibroblasts from bronchoalveolar lavage fluid (BALF) in patients with systemic sclerosis (SSc) has previously been described. The purpose of the present study was to characterise fibroblasts from BALF and bronchial biopsies from SSc patients with alveolitis and from controls, to analyse fibroblast proliferation, migration, stress fibres and proteoglycan production. BALF and bronchial biopsies were collected from 10 patients with SSc and alveolitis and from 15 controls. Outgrowth of fibroblasts was observed from the BALF of four patients, particularly in those with a markedly increased percentage of eosinophils in BALF, but not in any member of the control group. Increased levels of granulocyte-macrophage colony-stimulating factor, correlating with the percentage of eosinophils in BALF, were found in patients when compared with controls. Fibroblasts from BALF showed an elongated, mobile phenotype and increased proteoglycan production compared to the corresponding biopsy fibroblasts. In conclusion, outgrowth of fibroblasts with an altered phenotype is reported from bronchoalveolar lavage fluid in systemic sclerosis patients with alveolitis and an increased percentage of eosinophils in the bronchoalveolar lavage fluid. These findings indicate a possible role for eosinophil-fibroblast interaction in pulmonary fibrosis in systemic sclerosis.

Topics: Adult; Aged; Biopsy; Bronchi; Bronchoalveolar Lavage Fluid; Cell Division; Cell Movement; Endothelin-1; Female; Fibroblasts; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Lung Volume Measurements; Male; Middle Aged; Proteoglycans; Pulmonary Fibrosis; Scleroderma, Systemic; Stress Fibers

Endothelin-1 (ET-1) is implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF), but the cellular mechanisms underlying the role it plays in this disease are not well characterized. Epithelial-mesenchymal transition (EMT), which was recently demonstrated in alveolar epithelial cells (AEC), may play an important role in the pathogenesis of IPF and other forms of pulmonary fibrosis. Whether ET-1 contributes to the induction of EMT in AEC is unknown. The aims of this study were to evaluate AEC production of ET-1 and to determine if ET-1 induces EMT in AEC. We demonstrate that ET-1 is produced at physiologically relevant levels by primary AEC and is secreted preferentially toward the basolateral surface. We also demonstrate that AEC express high levels of endothelin type A receptors (ET-A) and, to a lesser extent, type B receptors (ET-B), suggesting autocrine or paracrine function for alveolar ET-1. In addition, ET-1 induces EMT through ET-A activation. Furthermore, TGF-beta1 synthesis is increased by ET-1, ET-1 induces Smad3 phosphorylation, and ET-1-induced EMT is attenuated by a TGF-beta1-neutralizing antibody. Thus, ET-1 is an important mediator of EMT in AEC, acting through ET-A-mediated TGF-beta1 production. These findings increase our basic understanding of the role of ET-1 in pulmonary fibrosis and suggest potential roles for AEC-derived ET-1 in the pathogenesis of other alveolar epithelial-mediated lung diseases.

Topics: Animals; Apoptosis; Endothelin-1; Epithelium; Gene Expression Regulation; Lung; Lung Injury; Male; Mesoderm; Models, Biological; Phenotype; Pulmonary Fibrosis; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Transforming Growth Factor beta1

Topics: Animals; Apoptosis; Disease Models, Animal; Endothelin-1; Epithelium; Humans; Lung; Mesoderm; Mice; Mice, Transgenic; Models, Biological; Phenotype; Pulmonary Fibrosis

Fibrosis is excessive scarring caused by the accumulation and contraction of extracellular matrix proteins and is a common end pathway in many chronic diseases, including scleroderma (systemic sclerosis [SSc]). Indeed, pulmonary fibrosis is a major cause of death in SSc. Transforming growth factor beta (TGFbeta) induces endothelin 1 (ET-1) in human lung fibroblasts by a Smad-independent, JNK-dependent mechanism. The goal of this study was to assess whether ET-1 is a downstream mediator of the profibrotic effects of TGFbeta in lung fibroblasts.. We used a specific endothelin receptor antagonist to determine whether ET-1 is a downstream mediator of TGFbeta responses in lung fibroblasts, using microarray technology, real-time polymerase chain reaction, and Western blot analyses.. The ability of TGFbeta to induce the expression of a cohort of profibrotic genes, including type I collagen, fibronectin, and CCN2, and to contract a collagen gel matrix, depends on ET-1.. ET-1 contributes to the ability of TGFbeta to promote a profibrotic phenotype in human lung fibroblasts, consistent with the notion that endothelin receptor antagonism may be beneficial in controlling fibrogenic responses in lung fibroblasts.

Topics: Bosentan; Cells, Cultured; Collagen Type I; Connective Tissue Growth Factor; Endothelin Receptor Antagonists; Endothelin-1; Extracellular Matrix; Fibroblasts; Fibronectins; Gene Expression Profiling; Humans; Immediate-Early Proteins; Intercellular Signaling Peptides and Proteins; Lung; Phenotype; Pulmonary Fibrosis; Sulfonamides; Transforming Growth Factor beta

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease associated with a wide range of extra-articular manifestations. Recent studies emphasise a key inflammatory role of the endothelial cells, either by overexpression of inflammatory mediators or by the proliferation of new blood vessels, in the disease process leading to the systemic organ involvement. To evaluate the relationship between internal organ manifestations and immunological markers of endothelial activation, serum levels of vascular endothelial growth factor (VEGF) and endothelin-1 (ET-1) were determined by an enzyme-linked immunosorbent assay in 64 RA patients and in 32 healthy controls. In comparison with a control group, higher serum concentrations of VEGF and ET-1 (p<0.001) in RA patients were demonstrated. A comparison between both RA groups with (20 patients) and without systemic involvement (44 patients) showed significantly higher concentrations of VEGF (p<0.05) and ET-1 (p<0.01) in the sera of patients with systemic manifestation. Moreover, a significant positive correlation between VEGF and ET-1 (r=0.475, p<0.001) in RA patients was found. A positive correlation between VEGF and Disease Activity Score (DAS) 28 index (r=0.39, p<0.005) as well as erythrocyte sedimentation rate (ESR) (r=0.564, p<0.0001) and C-reactive protein was found. ET-1 serum level correlated significantly with ESR (r=0.326, p<0.05) and DAS 28 index (r=0.307, p<0.05). These results suggest that the elevated serum levels of VEGF and ET-1 are associated with systemic organ involvement in RA patients and may play a key role in the pathogenesis of extra-articular manifestation of the disease.

Topics: Amyloidosis; Arthritis, Rheumatoid; Blood Sedimentation; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Glomerulonephritis; Health Status; Humans; Male; Middle Aged; Neovascularization, Pathologic; Pulmonary Fibrosis; Severity of Illness Index; Vascular Endothelial Growth Factor A

The signal transduction mechanisms generating pathological fibrosis are almost wholly unknown. Endothelin-1 (ET-1), which is up-regulated during tissue repair and fibrosis, induces lung fibroblasts to produce and contract extracellular matrix. Lung fibroblasts isolated from scleroderma patients with chronic pulmonary fibrosis produce elevated levels of ET-1, which contribute to the persistent fibrotic phenotype of these cells. Transforming growth factor beta (TGF-beta) induces fibroblasts to produce and contract matrix. In this report, we show that TGF-beta induces ET-1 in normal and fibrotic lung fibroblasts in a Smad-independent ALK5/c-Jun N-terminal kinase (JNK)/Ap-1-dependent fashion. ET-1 induces JNK through TAK1. Fibrotic lung fibroblasts display constitutive JNK activation, which was reduced by the dual ETA/ETB receptor inhibitor, bosentan, providing evidence of an autocrine endothelin loop. Thus, ET-1 and TGF-beta are likely to cooperate in the pathogenesis of pulmonary fibrosis. As elevated JNK activation in fibrotic lung fibroblasts contributes to the persistence of the myofibroblast phenotype in pulmonary fibrosis by promoting an autocrine ET-1 loop, targeting the ETA and ETB receptors or constitutive JNK activation by fibrotic lung fibroblasts is likely to be of benefit in combating chronic pulmonary fibrosis.

Topics: Actins; Activin Receptors, Type I; Animals; Cells, Cultured; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Enzyme Activation; Fibroblasts; Humans; JNK Mitogen-Activated Protein Kinases; Mice; Models, Biological; Protein Serine-Threonine Kinases; Pulmonary Fibrosis; Receptor, Endothelin A; Receptor, Endothelin B; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Smad Proteins; Transcription Factor AP-1; Transforming Growth Factor beta

The phenotype of alveolar-associated fibroblasts (Afb) in sarcoidosis (SA) and idiopathic pulmonary fibrosis (IPF) is unclear. In the present study, we characterized the cytoskeletal proteins and the contraction properties in alveolar-associated fibroblasts recovered by bronchoalveolar lavage (BAL) in the two diseases. Afb were studied from BAL cells in eight IPF and seven SA patients. Cytoskeletal proteins were identified by ELISA and immunofluorescent methods. Biochemical measurements were done by dry chemistry. Contraction was performed by a gel contraction assay. Afb alpha-SM actin measured by ELISA was higher in IPF than in SA (p = 0.042). Vimentin, desmin, myosin, and fibroblast markers were expressed equally. Only in IPF did the Afb reveal the myofibroblast phenotype showing alpha-SM actin immunofluorescence labeling and, by electron microscopy, filaments with associated dense bodies with rough endoplasmic reticulum. Gel contraction showed that cells in IPF contracted significantly more than in SA (p = 0.046 IPF versus SA). The addition of ET-1 increased contraction in all groups. Dry chemistry analysis showed higher levels (p = 0.0065) of creatine phosphokinase (CPK), lower levels of glucose (p = 0.0082), and similar levels of Ca(2+) and lactate in the IPF and SA Afb. Dinitrofluorobenzene (DNFB), a potent inhibitor of CPK, completely abolished spontaneous cell contraction. Afb differentiates into myofibroblasts with different biochemical and energetic properties in IPF. Moreover, Afb from IPF patients showed increased contractile properties. This may explain the difference in the behavior patterns and outcomes of the two diseases.

Topics: Adult; Aged; Bronchoalveolar Lavage Fluid; Calcium; Cell Count; Cells, Cultured; Collagen; Creatine Kinase; Cytoskeletal Proteins; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Fibroblasts; Fluorescent Antibody Technique; Gels; Glucose; Humans; Lactic Acid; Male; Pulmonary Alveoli; Pulmonary Fibrosis; Sarcoidosis, Pulmonary

The pulmonary endothelin (ET) system has been implicated in the pathogenesis of chronic lung diseases such as pulmonary hypertension, asthma, chronic obstructive lung disease, idiopathic pulmonary fibrosis, and bronchiolitis obliterans. However, the etiologic role of ET-1 in these diseases has not yet been established. We recently demonstrated that ET-1 transgenic mice, generated using the human prepro-ET-1 expression cassette including the cis-acting transcriptional regulatory elements, had predominant transgene expression in lung, brain, and kidney. We used these mice in the present study to analyze the pathophysiologic consequences of long-term pulmonary overexpression of ET-1. We found that ET-1 overexpression in the lungs did not result in significant pulmonary hypertension, but did result in development of a progressive pulmonary fibrosis and recruitment of inflammatory cells (predominantly CD4-positive cells). Our study provides evidence that a long-term activated pulmonary ET system, without any other stimuli, produces chronic lymphocytic inflammation and lung fibrosis. This suggests that overexpression of ET-1 may be a central event in the pathogenesis of lung diseases associated with fibrosis and chronic inflammation, such as pulmonary fibrosis and bronchiolitis.

Topics: Animals; Apoptosis; Blood Gas Analysis; Bronchi; CD4-Positive T-Lymphocytes; Cell Division; Chronic Disease; Endothelin-1; Humans; Hypertension, Pulmonary; Immunohistochemistry; Inflammation; Lung; Male; Mice; Mice, Transgenic; Neovascularization, Physiologic; Organ Size; Organ Specificity; Pulmonary Artery; Pulmonary Fibrosis; Receptors, Endothelin; Transgenes; Ventricular Pressure

Endothelin-1 (ET-1) is a potent constrictor and mitogen peptide which is expressed in several pulmonary diseases. To elucidate the involvement of ET-1 in lung interstitial pathologic events, we assessed ET-1 secretion by alveolar macrophages (AM) and fibroblasts recovered from the bronchoalveolar lavage (BAL) of patients with idiopathic pulmonary fibrosis (IPF), sarcoidosis (SA) and from control subjects. We characterized in vitro alveolar fibroblasts of all subjects using monoclonal antibody specific to alpha-smooth muscle actin (alpha-SM actin) and human fibroblast marker. We also examined the effect of ET-1 on the fibroblasts' mitogenesis and on their cytoskeletal phenotype. The AM recovered from IPF patients showed increased spontaneous secretion of ET-1 compared with cells from SA and control subjects. The expression of alpha-SM actin in the fibroblasts from IPF patients was significantly higher than in SA fibroblasts and normal lung fibroblasts. Assessing alveolar fibroblasts purity revealed a negative staining for alpha-SM actin in all SA and control fibroblasts, while alveolar fibroblasts recovered from IPF were 100% positive for alpha-SM actin, a reliable differentiation marker of myofibroblastic cells. Exposure of SA alveolar fibroblasts to ET-1 resulted in an increased expression of alpha-SM actin. Addition of exogenous ET-1 to alveolar fibroblasts culture stimulated DNA synthesis and proliferation in all groups. Moreover, neutralization of ET-1 by monoclonal antibody was shown to decrease 3H-thymidine incorporation in fibroblasts cultured with AM supernatants. These results suggest possible interactions between AM, myofibroblasts and fibroblasts in interstitial lung diseases (ILD). By modulating alpha-SM actin expression and exertion of the mitogenic effect on alveolar fibroblasts, ET-1 might play an important role in the fibrogenesis of ILD.

Topics: Actins; Adult; Aged; Bronchoalveolar Lavage Fluid; Cell Division; Cells, Cultured; Endothelin-1; Female; Fibroblasts; Humans; Male; Middle Aged; Mitogens; Muscle, Smooth; Pulmonary Fibrosis; Sarcoidosis

To evaluate the roles of the Endothelin-1 (ET-1) in pathogenesis of the patients with interstitial lung disease (ILD).. The ET-1 activities in the serum and BALF from 10 patients with sarcoidosis, 7 with idiopathic pulmonary fibrosis (IPF) and 8 normal subjects non-smokers were determined using the radio-immunoassay.. In the activities of ET-1 in the serum and BALF in the patients with sarcoiosis (62 +/- 29 and 17.0 +/- 2.4) ng/L and in the IPF (77 +/- 71 and 10 +/- 3) ng/L. was higher than those in the normal control subjects (20 +/- 8 and 4.0 +/- 0.6) ng/L. The activities of ET-1 in serum was negative correlated with PaO2 (r = -0.538, P < 0.01). The level of ET-1 in the BALF of the patient was positive correlated with total cells in BALF (r = 0.649, P < 0.01). The levels of ET-1 in the BALF in the sarcoidosis was positive correlated with the percentage of lymphocyte (r = 0.712, P < 0.01) but in patients with IPF was positive correlated with the percentage of neutrophil (r = 0.813, P < 0.01).. ET-1 might play an important role in pathogenic of the patients with sarcoidosis and IPF. The levels of ET-1 can act as the markers of activity of disease.

Topics: Adult; Bronchoalveolar Lavage Fluid; Cell Count; Endothelin-1; Female; Humans; Lymphocytes; Male; Middle Aged; Neutrophils; Pulmonary Fibrosis; Sarcoidosis, Pulmonary

Endothelin-1 (Et-1) has been implicated in the pathogenesis of pulmonary fibrosis with increased levels in the lung tissue of patients with pulmonary fibrosis and profibrotic effects in vitro. In this study we have investigated the temporal changes in lung Et-1 levels and immunohistochemical localization in relation to collagen deposition during the development of bleomycin-induced pulmonary fibrosis in rats. Lung Et-1 content doubled by 3 d following the intratracheal instillation of bleomycin, and continued to increase up to 7 d when values were about threefold greater than controls. Thereafter, the values for bleomycin-treated animals remained constant up to 21 d. There was no change in collagen content at 3 d but after 7 d there was a 25% increase and by 21 d levels were almost double those of the controls. In normal lung, Et-1 was predominantly associated with epithelial cells of conducting and nonconducting airways. Following bleomycin administration, intense staining of macrophages and conducting airway and alveolar epithelial cells was observed with marked staining of perivascular, peribronchiolar, and alveolar septal connective tissue, as well as the venular and arterial intima and media. These results demonstrate elevation of Et-1 levels prior to an increase in collagen content which, along with its localization within developing fibrotic lesions, provides further evidence of a profibrotic role for Et-1 in the pathogenesis of pulmonary fibrosis.

Topics: Animals; Antimetabolites, Antineoplastic; Bleomycin; Collagen; Cross Reactions; Endothelin-1; Epithelial Cells; Leukocytes; Pulmonary Fibrosis; Rats; Rats, Inbred Lew

Endothelin-1 (ET-1) is a vasoconstrictor, bronchoconstrictor, and mitogenic peptide which is enzymatically converted from a biologically inactive big ET to mature ET (21 amino acid) by the ET-converting enzyme (ECE). Here, we investigate the expression of ECE-1, big ET-1, and ET-1 in the lungs of patients with idiopathic pulmonary fibrosis (IPF) and compare it to those of normal subjects using immunohistochemistry and in situ hybridization. In normal lungs, focal moderate expression of all three molecules is localized to airway epithelium, pulmonary endothelium, and airway and vascular smooth muscle cells. Serous bronchial glands also expressed ET-1 and ECE-1. In IPF, strong diffuse expression of ECE-1 was seen in airway epithelium, proliferating type II pneumocytes, and in endothelial and inflammatory cells. ECE-1 immunostaining was colocalized to big ET-1 and ET-1 immunostaining, and correlated with disease activity (P < 0.05). To study regulatory mechanisms of ET-1 and ECE-1 expression, human normal bronchial epithelial (NBE) cells were treated with cytokines and analyzed by radioimmunoassay and Northern blot. Incubation of human NBE cells with IL-1alpha and -beta or tumor necrosis factor alpha (TNFalpha) resulted in a significant increase in ET-1 release and mRNA expression. TNFalpha resulted in a significant increase in ECE-1 mRNA expression. These findings demonstrated the colocalization of the precursor and active ET-1, and ECE-1 in the same cell, and that ECE-1 expression is elevated in IPF. In addition, increased expression of ET-1 and ECE-1 in IPF may be mediated by proinflammatory cytokines.

Topics: Aspartic Acid Endopeptidases; Blotting, Northern; Endothelin-1; Endothelin-Converting Enzymes; Female; Humans; Immunohistochemistry; Inflammation Mediators; Male; Metalloendopeptidases; Pulmonary Fibrosis; Radioimmunoassay; RNA, Messenger

Idiopathic pulmonary fibrosis (IPF) is characterized by an alveolitis with epithelial and endothelial damage progressing to fibrosis. Numerous mediators have been implicated in this complex process. Studies in humans have shown that endothelin-1 (ET-1), a vasoconstrictor and mitogenic peptide, is a mediator in IPF. To determine the role of ET-1 and endothelin-converting enzyme (ECE)-1 and the effect of Bosentan, an ET receptor antagonist, in an animal model of IPF, we studied three groups of rats (n = 6 each): Group 1, control, received saline; Group 2, fibrosis, received 1.5 U bleomycin intratracheally; Group 3, fibrosis-Bosentan treated, received bleomycin and Bosentan daily by gavage. After 28 d, right upper lobes were fixed for immunohistochemistry (IHC) and sections were stained with antisera to ET-1 and ECE-1 and graded semiquantitatively. Sections from left lungs were embedded in paraffin and stained for light microscopic morphometry to quantitate the fibrosis. By IHC, we found increased ET-1 immunoreactivity (ir) in airway epithelium and inflammatory cells, and ECE-1-ir in airway epithelium, type II pneumocytes and endothelial cells (p < 0.05). By morphometry, the volume fraction (Vv) of connective tissue (CT) increased and the Vv of air decreased in the fibrosis group compared with that in the control group. Bosentan reduced the Vv of CT and increased the Vv of air compared with that in the fibrosis group (p < 0.05). These results indicate that ET-1 is involved in the pathogenesis of pulmonary fibrosis in the rodent model and that blockage of its receptors reduces the fibrosis.

Topics: Animals; Anti-Bacterial Agents; Aspartic Acid Endopeptidases; Bleomycin; Bosentan; Drug Evaluation, Preclinical; Endothelin Receptor Antagonists; Endothelin-1; Endothelin-Converting Enzymes; Immunohistochemistry; Lung; Male; Metalloendopeptidases; Pulmonary Fibrosis; Rats; Rats, Inbred F344; Sulfonamides

In addition to their vasoactive action, endothelins are potent peptides in the regulation of both cell proliferation and the turnover of extracellular matrix. Using immunohistochemical, autoradiographic, and molecular analyses, we have studied the localization and expression of endothelin-1 and endothelin A (ETA) and B (ETB) receptors in scleroderma-associated fibrotic lung disease. Increased ET-1 immunoreactivity was found in sclerotic tissue compared with control and was associated with the vasculature, pulmonary interstitium, and bronchial and alveolar epithelium. Microautoradiographic analysis after 125I-labeled ET-1 binding showed a two- to threefold increase in the expression of total ET-1 receptors in scleroderma lung tissue localized to the alveolar epithelium and the pulmonary interstitium which was composed of mainly fibroblastic cells with macrophages and some microvessels. RNAse protection assay revealed significantly reduced ETA receptor and slightly raised ETB message levels in systemic sclerosis lung. Surface expression of functional ET receptors was examined by targeted receptor blocking using mixed and receptor-subtype-selective ligands. A consistent decrease in ETA receptor binding sites was noted primarily within the interstitium and vasculature, in contrast to a slight increase in ETB receptors. Elevated ET-1 and the cell-specific pattern of endothelin receptor expression suggest that the endothelins may represent important mediators that influence the pathology of scleroderma-associated lung disease and other fibrotic conditions.

Topics: Adult; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Endothelin-1; Female; Gene Expression Regulation; HLA-DR Antigens; Humans; Immunohistochemistry; Lung; Middle Aged; Pulmonary Fibrosis; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Scleroderma, Systemic