Bruno Crestani

NOX4/NADPH oxidase expression is increased in pulmonary fibroblasts from patients with idiopathic pulmonary fibrosis and mediates TGFbeta1-induced fibroblast differentiation into myofibroblasts.

Background Persistence of myofibroblasts is believed to contribute to the development of fibrosis in idiopathic pulmonary fibrosis (IPF). Transforming growth factor β1 (TGFβ1) irreversibly converts fibroblasts into pathological myofibroblasts, which express smooth muscle α-actin (α-SMA) and produce extracellular matrix proteins, such as procollagen I (α1). Reactive oxygen species produced by NADPH oxidases (NOXs) have been shown to regulate cell differentiation. It was hypothesised that NOX could be expressed in parenchymal pulmonary fibroblasts and could mediate TGFβ1-stimulated conversion of fibroblasts into myofibroblasts. Methods Fibroblasts were cultured from the lung of nine controls and eight patients with IPF. NOX4, α-SMA and procollagen I (α1) mRNA and protein expression, reactive oxygen species production and Smad2/3 phosphorylation were quantified, in the absence and in the presence of incubation with TGFβ1. Migration of platelet-derived growth factor (PDGF)-induced fibroblasts was also assessed. Results It was found that (1) NOX4 mRNA and protein expression was upregulated in pulmonary fibroblasts from patients with IPF and correlated with mRNA expression of α-SMA and procollagen I (α1) mRNA; (2) TGFβ1 upregulated NOX4, α-SMA and procollagen I (α1) expression in control and IPF fibroblasts; (3) the change in α-SMA and procollagen I (α1) expression in response to TGFβ1 was inhibited by antioxidants and by a NOX4 small interfering RNA (siRNA); (4) NOX4 modulated α-SMA and procollagen I (α1) expression by controlling activation of Smad2/3; and (5) NOX4 modulated PDGF-induced fibroblast migration. Conclusion NOX4 is critical for modulation of the pulmonary myofibroblast phenotype in IPF, probably by modulating the response to TGFβ1 and PDGF.

Altered Nrf2/Keap1-Bach1 equilibrium in pulmonary emphysema

Background: Oxidative stress, resulting from the increased oxidative burden and decreased level of antioxidant proteins, plays a role in the pathophysiology of smoking-related pulmonary emphysema. Expression of several antioxidant proteins, such as heme oxygenase-1 (HO-1), glutathione peroxidase 2 (GPX2) and NAD(P)H:quinone oxidoreductase 1 (NQO1), results from an equilibrium created by positive or negative regulation by the transcription factors Nrf2, Keap1 and Bach1, respectively. However, whether the expression of these transcription factors is altered in emphysema and could account for decreased expression of antioxidant proteins is not known. A study was undertaken to investigate the expression and subcellular localisation of Nrf2, Keap1 and Bach1 as potential regulators of HO-1, GPX2 and NQO1 in alveolar macrophages, a key cell in oxidative stress, in lung surgical specimens from non-smokers without emphysema and smokers with and without emphysema. Methods and results: Western blot, immunohistochemical and laser scanning confocal analysis revealed that the Nrf2 protein level decreased significantly in whole lung tissue and alveolar macrophages (cytosol and nucleus) in patients with emphysema compared with those without emphysema. Conversely, Bach1 and Keap1 levels were increased in patients with emphysema. These modifications were associated with a parallel decrease in the expression of HO-1, GPX2 and NQO1 at the cellular level, which was inversely correlated with airway obstruction and distension indexes, and increased macrophage expression of the lipid peroxidation product 4-hydroxy-2-nonenal. Silencing RNA experiments in vitro in THP-1 cells were performed to confirm the cause-effect relation between the loss of Nrf2 and the decrease in HO-1, NQO1 and GPX2 expression. Nrf2/Keap1-Bach1 equilibrium was altered in alveolar macrophages in pulmonary emphysema, which points to a decreased stress response phenotype. Conclusions: This finding opens a new view of the pathophysiology of emphysema and could provide the basis for new therapeutic approaches based on preservation and/or restoration of such equilibrium.

The MUC5B variant is associated with idiopathic pulmonary fibrosis but not with systemic sclerosis interstitial lung disease in the European Caucasian population.

A polymorphism on the MUC5B promoter (rs35705950) has been associated with idiopathic pulmonary fibrosis (IPF) but not with systemic sclerosis (SSc) with interstitial lung disease (ILD). We genotyped the MUC5B promoter in the first 142 patients of the French national prospective cohort of IPF, in 981 French patients with SSc (346 ILD), 598 Italian patients with SSc (207 ILD), 1383 French controls and 494 Italian controls. A meta-analysis was performed including all American data available. The T risk allele was present in 41.9% of the IPF patients, 10.8% of the controls (Pu200a=u200a2×10–44), OR 6.3 [4.6–8.7] for heterozygous patients and OR 21.7 [10.4–45.3] for homozygous patients. Prevalence of the T allele was not modified according to age, gender, smoking in IPF patients. However, none of the black patients with IPF presented the T allele. The prevalence of the T risk allele was similar between French (10%) and Italian (12%) cohorts of SSc whatever the presence of an ILD (11.1% and 13.5%, respectively). Meta-analysis confirmed the similarity between French, Italian and American cohorts of IPF or SSc-ILD. This study confirms 1) an association between the T allele risk and IPF, 2) an absence of association with SSc-ILD, suggesting different pathophysiology.

ANCA-associated lung fibrosis: Analysis of 17 patients

In this retrospective study, we analyzed 17 patients presenting with pulmonary fibrosis and a positive ANCA testing. This group was compared with a control group of 12 patients with IPF and negative ANCA testing. Patients were 15 males and 2 females, with a mean age of 66 years. Eight patients were past smokers, 3 current smokers and 6 non-smokers. Lung function tests at diagnosis were as follows (% predicted): total lung capacity 73%+/-18, vital capacity 82%+/-23, forced expiratory volume in 1 s (FEV(1)) 88%+/-24, carbon monoxide diffusion capacity of the lung 49%+/-2 (% predicted). Bronchoalveolar lavage results showed an increased cellularity with increased neutrophils counts. High resolution computed tomography of the chest showed prominent fibrosis with some degree of ground-glass attenuation in all patients. These characteristics were similar to the control group. Microscopic polyangiitis (MPA) was a major complicating event in ANCA-positive patients, occurring in 7 patients (anti-myeloperoxidase specificity in 5 patients). Pulmonary fibrosis predated occurrence of MPA in 6 patients and was diagnosed concomitantly with MPA in 1 patient. During the follow-up, 10/17 patients died. The death was directly related to vasculitis in 3 patients. We conclude that patients with pulmonary fibrosis should be evaluated for the presence of ANCA. Patients with positive ANCA testing, particularly if anti-myeloperoxidase, should be carefully monitored to detect the occurrence of microscopic polyangiitis.

Signalling pathways from NADPH oxidase-4 to idiopathic pulmonary fibrosis

This review focuses on the roles of NADPH oxidase/NOX proteins in idiopathic pulmonary fibrosis (IPF) pathophysiology and in the signalling pathways involved in IPF. NOX proteins are membrane-associated multi-unit enzymes that catalyze the reduction of oxygen using NADPH as an electron donor. Recent studies indicate that NOX4 is induced in pulmonary fibroblasts in response to TGF-β. TGF-β or PDGF induce myofibroblast proliferation, differentiation, migration, contractility and extracellular matrix production, through NOX4 and reactive oxygen species dependent SMAD2/3 phosphorylation. NOX4 is increased in pulmonary fibroblasts from IPF patients and deletion of Nox4 in mice prevents bleomycin-induced pulmonary fibrosis. These data strongly suggest that targeting of NOX4 could be a step forward in the treatment of fibrotic lung diseases, by specifically targeting myofibroblasts, a major player in this disease.

Hepatocyte Growth Factor and Lung Fibrosis

Idiopathic pulmonary fibrosis is currently believed to be driven by alveolar epithelial cells, with abnormally activated alveolar epithelial cells accumulating in an attempt to repair injured alveolar epithelium (1). Thus, targeting the alveolar epithelium to prevent or inhibit the development of pulmonary fibrosis might be an interesting therapeutic option in this disease. Hepatocyte growth factor (HGF) is a growth factor for epithelial and endothelial cells, which is secreted by different cell types, especially fibroblasts and neutrophils. HGF has mitogenic, motogenic, and morphogenic properties and exerts an antiapoptotic action on epithelial and endothelial cells. HGF has also proangiogenic effect. In vitro, HGF inhibits epithelial-to-mesenchymal cell transition and promotes myofibroblast apoptosis. In vivo, HGF has antifibrotic properties demonstrated in experimental models of lung, kidney, heart, skin, and liver fibrosis. Hence, the modulation of HGF may be an attractive target for the treatment of lung fibrosis.

Severe chronic bronchiolitis as the presenting feature of primary Sjogren's syndrome

Sjögrens syndrome is a frequent auto-immune disorder with a pulmonary location in almost 10% of the patients. Although bronchial involvement is very common, most patients only complain of cough and this involvement rarely results in severe symptoms or chronic respiratory failure are rarely observed. We describe here 5 patients with severe chronic bronchiolitis revealing primary Sjögrens syndrome. The lung involvement resulted in chronic bronchorrhea, recurrent sinusitis, diffuse bronchiolar nodules with bronchiectasis on the CT scan, and a severe obstructive airway pattern on lung function tests. Improvement was obtained in 4 patients with combination of inhaled corticosteroids, inhaled long acting beta-agonists, and a low dose of erythromycin.

Detection of alveolar fibrocytes in idiopathic pulmonary fibrosis and systemic sclerosis.

Background Fibrocytes are circulating precursors for fibroblasts. Blood fibrocytes are increased in patients with idiopathic pulmonary fibrosis (IPF). The aim of this study was to determine whether alveolar fibrocytes are detected in broncho-alveolar lavage (BAL), to identify their prognostic value, and their potential association with culture of fibroblasts from BAL. Methods We quantified fibrocytes in BAL from 26 patients with IPF, 9 patients with Systemic Sclerosis(SSc)-interstitial lung disease (ILD), and 11 controls. BAL cells were cultured to isolate alveolar fibroblasts. Results Fibrocytes were detected in BAL in 14/26 IPF (54%) and 5/9 SSc patients (55%), and never in controls. Fibrocytes were in median 2.5% [0.4–19.7] and 3.0% [2.7–3.7] of BAL cells in IPF and SSc-ILD patients respectively. In IPF patients, the number of alveolar fibrocytes was correlated with the number of alveolar macrophages and was associated with a less severe disease but not with a better outcome. Fibroblasts were cultured from BAL in 12/26 IPF (46%), 5/9 SSc-ILD (65%) and never in controls. The detection of BAL fibrocytes did not predict a positive culture of fibroblasts. Conclusion Fibrocytes were detected in BAL fluid in about half of the patients with IPF and SSc-ILD. Their number was associated with less severe disease in IPF patients and did not associate with the capacity to grow fibroblasts from BAL fluid.

Severe Pulmonary Fibrosis as the First Manifestation of Interferonopathy (TMEM173 Mutation)

We report three cases of pulmonary disease suggesting fibrosis in two familial and one sporadic case. Pulmonary symptoms were associated with various clinical features of systemic inflammation and vasculitis involving the skin, and appeared at different ages. A strong interferon signature was found in all three cases. Disease was not responsive to corticosteroids, and lung transplantation was considered for all three subjects at an early age. One of them underwent double-lung transplantation, but she immediately experienced a primary graft dysfunction and died soon after. Recognized causes of familial interstitial lung disease were all excluded. All three subjects had a mutation in the previously described autoinflammatory disease called SAVI (stimulator of interferon genes [STING]-associated vasculopathy with onset in infancy). These cases emphasize the need to consider this possibility in children and young adults with lung fibrosis after common causes have been ruled out.

Clonality and phenotyping analysis of alveolar lymphocytes is suggestive of pulmonary MALT lymphoma.

BACKGROUNDnMucosa-associated lymphoid tissue (MALT) lymphoma, a low-grade B-cell extranodal lymphoma, is the most frequent subset of primary pulmonary lymphoma (PPL). It often associates with connective tissue disease (CTD). We aimed to evaluate the impact of concomitant CTD on diagnostic value of flow cytometry and genetic clonality analyses for the diagnostic of MALT lymphoma.nnnMETHODSnAll chest disease and pathology departments of teaching hospitals in Paris were contacted to identify patients with a histological diagnosis of PPL of the MALT subtype with or without associated CTD. We identified 44 patients in the lymphoma group; 11 had a CTD and were matched to 11 patients with CTD but without lymphoma.nnnRESULTSnResults of BAL analyses of MALT-PPL showed normal cellularity (370 cells/mm(3) [range 21-2300]) but increased proportion of lymphocytes (31.5% [80-2]) of the B-cell subtype (20% [1-88]). A B-cell clone was detected in 82% of cases, and specificity of clonality was 90%. Interestingly, BAL analysis results different by presence or not of a CTD. The frequency of B lymphocyte alveolitis was significantly greater in MALT patients without than with CTD (34% vs 6.5%, p = 0.007). However, BAL results for patients with CTD did not differ between those with and without lymphoma.nnnCONCLUSIONnBAL results may be highly suggestive of pulmonary MALT lymphoma. The proportion of B-cells may vary depending on the presence of an associated CTD, but clonality analyses remained informative for the diagnostic of MALT lymphoma.