Carbonylated proteins in bronchoalveolar lavage of patients with sarcoidosis, pulmonary fibrosis associated with systemic sclerosis and idiopathic pulmonary fibrosis

Oxygen-derived free radicals produced by phagocytes have been postulated to contribute to lung tissue damage occurring during diffuse lung diseases (DLD). The two-dimensional electrophoretic (2-DE) analysis of bronchoalveolar lavage (BAL) protein composition revealed different protein profiles in sarcoidosis (S), idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc) with a significant increase of low molecular weight proteins in IPF. Some of these proteins are involved in antioxidant processes. The aims of this report were to analyse the oxidative stress occurring in patients with DLD through determination of BAL protein carbonyl content and to identify target proteins of oxidation by a proteomic approach (2-DE combined with immunoblotting with specific antibodies for carbonyl groups). Carbonylated proteins detected by enzyme-linked immunosorbent assay (ELISA) were increased in BAL of patients with S, IPF and SSc compared to healthy controls with a significant difference for S and IPF. The proteomic approach to the analysis of BAL revealed that protein carbonylation was a process involving specific carbonylation-sensitive proteins and that in IPF a greater number of proteins target of oxidation were present. In conclusion, to our knowledge, this is the first report providing a database of proteins target of oxidation in BAL of patients with sarcoidosis, idiopathic pulmonary fibrosis and systemic sclerosis.     

Depressed urokinase activity in bronchoalveolar lavage fluid from patients with sarcoidosis,silicosis or idiopathic pulmonary Rbrosis: relationship to disease severity

Intraalveolar fibrinolysis, is regulated by the concerted actions of plasmin, plasminogen activators (PAs), and their specific inhibitors (PAIs). This event is considered as a critical step in the pathogenesis of pulmonary fibrosis. The aim of this study was to evaluate whether local PA activity can be held as a marker of fibrosis in chronic interstitial lung disorders (ILD). Changes in both PA activity and PA-related proteins (urokinase-type PA (uPA), tissue-type PA (tPA), PAI-1 and PAI-2) were assessed in bronchoalveolar fluid (BALF) of 60 subjects: 18 healthy controls, 18 non-fibrotic sarcoidosis patients, 16 patients with idiopathic pulmonary fibrosis (IPF) and eight silicotic patients with established fibrosis. We observed a significant decrease of BALF PA activity in the three groups of patients as compared with controls. Reduction in BALF PA activity was compatible with lower uPA protein levels associated, especially in IPF patients, with an increased occurrence of PAI-1 and PAI-2 antigens. Soluble tPA antigen was never detected either in control subjects or in patients. Most importantly, the reduction in BALF PA activity and uPA protein levels was found to be most severe in patients with advanced fibrotic disease, namely IPF, while moderate and only weak alterations were found in silicosis and non-fibrotic sarcoidosis, respectively. In addition, significant positive correlations were found between BALF PA activity and functional impairment as assessed by TLC % and DL_CO%. Finally, the reduction in uPA and PA activity levels observed in BALF from sarcoidosis patients was found to be proportional to the degree of BAL lymphocytosis. These findings indicate that an intense reduction in BALF PA activity is associated with severe stages of the parenchymal disease, possibly reflecting the degree of the fibrotic process.     

Expression of bcl-2 protein in bronchoalveolar lavage cell populations from patients with idiopathic pulmonary fibrosis.

OBJECTIVE: To investigate changes in the expression of the antiapoptotic protein bcl-2 in bronchoalveolar lavage fluid (BALF) cell populations in patients with idiopathic pulmonary fibrosis (IPF). STUDY DESIGN: Ten patients with IPF underwent fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) in the area of maximal radiographic shadowing (based on high-resolution computed tomography findings). Results were compared with those of 10 normal people in the control group. Cellular bcl-2 expression was identified using an immunoperoxidase staining method. RESULTS: A statistically significant (P < .001) increase in the expression of bcl-2 in BALF neutrophils and eosinophils was observed in patients with IPF as compared with controls. BAL macrophages exhibited only a slight (statistically insignificant) increase in bcl-2 expression in IPF patients. No bcl-2 expression was observed in BAL lymphocytes from IPF patients in contrast to the control group. CONCLUSION: The overexpression of bcl-2 on BALF neutrophils and eosinophils, cells that characterize the special cellular profile of alveolitis in IPF, could be one of the pathophysiologic mechanisms of this disease.     

Systemic and pulmonary oxidative stress in idiopathic pulmonary fibrosis.

An oxidant/antioxidant imbalance has been proposed in patients with idiopathic pulmonary fibrosis (IPF). We tested this hypothesis by measuring various parameters of the oxidant/antioxidant balance in the plasma of 12 patients with IPF (7 nonsmokers and 5 smokers); in the bronchoalveolar lavage fluid (BALF) of 24 patients with IPF (17 nonsmokers and 7 smokers) and 31 healthy subjects (23 nonsmokers and 8 smokers). The trolox equivalent antioxidant capacity (TEAC) in plasma and BALF was lower in nonsmoking patients with IPF (plasma 0.55+/-0.1 mM, p<.001; BALF 4.8+/-1.2 microM, mean +/-SEM, p<.01), compared with healthy nonsmokers (plasma 1.33+/-0.03 mM; BALF 10+/-2 microM). Similar trends in plasma and BALF TEAC were observed in smoking patients with IPF in comparison with healthy smokers. The decrease in BALF TEAC was concomitant with a decrease in BALF protein thiol levels, but the decrease TEAC levels in plasma in IPF patients was not accompanied by a decrease in protein thiol levels. Reduced glutathione (GSH) was lower in BALF in nonsmoking patients with IPF (1.0+/-0.1 microM) compared with healthy nonsmokers (2.3+/-0.2 microM, p<.001). In contrast, GSH levels were higher in smoking patients with IPF (5.2+/-1.1 microM, p<.001) than in nonsmoking patients. GSSG levels were not different in any of the groups. The levels of products of lipid peroxidation measured as thiobarbituric acid reactive substances (TBARS) in plasma and BALF were significantly increased in both smoking (plasma 2.2+/-0.5 microM, p<.01; BALF 0.18+/-0.04 microM, p<.001), and nonsmoking (plasma 2.1+/-0.3 microM, p<.01; BALF 0.22+/-0.05 microM, p<.001) IPF patients, compared with healthy nonsmokers (plasma 1.4+/-0.3 microM; BALF 0.05+/-0.004 microM). These data show evidence of oxidant/antioxidant imbalance in the lungs of patients with IPF, which is also reflected as systemic oxidant stress.     

Analysis of bronchoalveolar lavage fluid proteome from systemic sclerosis patients with or without functional, clinical and radiological signs of lung fibrosis

Lung fibrosis is a major cause of mortality and morbidity in systemic sclerosis (SSc). However, its pathogenesis still needs to be elucidated. We examined whether the alteration of certain proteins in bronchoalveolar lavage fluid (BALF) might have a protective or a causative role in the lung fibrogenesis process. For this purpose we compared the BALF protein profile obtained from nine SSc patients with lung fibrosis (SScFib+) with that obtained from six SSc patients without pulmonary fibrosis (SScFib-) by two-dimensional gel electrophoresis (2-DE). Only spots and spot-trains that were consistently expressed in a different way in the two study groups were taken into consideration. In total, 47 spots and spot-trains, corresponding to 30 previously identified proteins in human BALF, showed no significant variation between SScFib+ patients and SScFib- patients, whereas 24 spots showed a reproducible significant variation in the two study groups. These latter spots corresponded to 11 proteins or protein fragments, including serum albumin fragments (13 spots), 5 previously recognized proteins (7 spots), and 4 proteins (3 spots) that had not been previously described in human BALF maps, namely calumenin, cytohesin-2, cystatin SN, and mitochondrial DNA topoisomerase 1 (mtDNA TOP1). Mass analysis did not determine one protein-spot. The two study groups revealed a significant difference in BALF protein composition. Whereas levels of glutathione S-transferase P (GSTP), Cu-Zn superoxide dismutase (SOD) and cystatin SN were downregulated in SScFib+ patients compared with SScFib- patients, we observed a significant upregulation of alpha1-acid glycoprotein, haptoglobin-alpha chain, calgranulin (Cal) B, cytohesin-2, calumenin, and mtDNA TOP1 in SScFib+ patients. Some of these proteins (GSTP, Cu-Zn SOD, and cystatin SN) seem to be involved in mechanisms that protect lungs against injury or inflammation, whereas others (Cal B, cytohesin-2, and calumenin) seem to be involved in mechanisms that drive lung fibrogenesis. Even if the 2-DE analysis of BALF did not provide an exhaustive identification of all BALF proteins, especially those of low molecular mass, it allows the identification of proteins that might have a role in lung fibrogenesis. Further longitudinal studies on larger cohorts of patients will be necessary to assess their usefulness as predictive markers of disease.     

Lung infection with gamma-herpesvirus induces progressive pulmonary fibrosis in Th2-biased mice

Idiopathic pulmonary fibrosis (IPF) is a progressive, fibrotic lung disease of unknown etiology. A viral pathogenesis in IPF has been suggested since >95% of IPF patients have evidence of chronic pulmonary infection with one or more herpesviruses. To determine whether pulmonary infection with herpesvirus can cause lung fibrosis, we infected mice with the murine gamma-herpesvirus 68 (MHV68). Because IPF patients have a T helper type 2 (Th2) pulmonary phenotype, we used IFN-gammaR-/-, a strain of mice biased to develop Th2 responses. Chronic MHV68 infection of IFN-gammaR-/- mice resulted in progressive deposition of interstitial collagen as shown by light and electron microscopy. A significant decrease in tidal volume paralleled the collagen deposition. Five features typically seen in IPF, increased transforming growth factor-beta expression, myofibroblast transformation, production of Th2 cytokines, hyperplasia of type II cells, and increased expression of matrix metalloproteinase-7, were also present in chronically infected IFN-gammaR-/- mice. There also was altered synthesis of surfactant proteins, which is seen in some patients with familial IPF. MHV68 viral protein was found in type II alveolar epithelial cells, especially in lung areas with extensive alveolar remodeling. In summary, chronic herpesvirus pulmonary infection in IFN-gammaR-/- mice causes progressive pulmonary fibrosis and many of the pathological features seen in IPF.     

Yin Yang-1(YY-1) expression in idiopathic pulmonary fibrosis

Context: Yin Yang-1 (YY-1) is implicated in the pathogenesis of lung cancer which can be complicated with idiopathic pulmonary fibrosis (IPF).

Objective: The aim of the study was to investigate whether YY-1 is involved in the pathogenesis of IPF and whether represents a common pathogenetic pathway which could explain the coexistence of these disorders.

Materials and methods: Lung tissue from 52 patients (37 with IPF and 15 controls) and bronchoalveolar lavage fluid (BALF) from 34 patients (25 with IPF and 9 controls) were studied and YY-1 mRNA expression was evaluated by real-time PCR.

Results: YY-1 was expressed in 8% (3/37) of IPF patients and in 6% (1/15) of healthy controls in tissue samples. In addition, 12% (3/25) of IPF patients and 33% (3/9) of healthy controls have expressed YY-1 gene in BALF samples. However, no statistical significant difference in mRNA expression between patients and controls has been detected in both tissue and BAL fluid samples.

Discussion and conclusion: Our results do not support the hypothesis of YY-1 involvement in IPF. However, similar expression of YY-1 gene in two biological samples cannot exclude a possible role of this polymorphic gene in the pathway of IPF. Further studies in a larger scale of patients are needed.     

RNA interference as a gene silencing therapy for mutant MYOC protein in primary open angle glaucoma

Bronchoalveolar lavage (BAL) is a useful diagnostic tool in interstitial lunge diseases (ILD). However, differential cell counts are often non specific and immunocytochemistry is time consuming. Staining of glyoproteins by periodic acid Schiff (PAS) reaction may help in discriminating different forms of ILD. In addition, PAS staining is easy to perform. BAL cells from patients with idiopathic pulmonary fibrosis (IPF) (n = 8), sarcoidosis (n = 9), and extrinsic allergic alveolitis (EAA) (n = 2) were investigated. Cytospins from BAL cells were made and cells were stained using Hemacolor quick stain and PAS staining. Lymphocytic alveolitis was found in sarcoidosis and EAA whereas in IPF both lymphocytes and neutrophils were increased. PAS positive cells were significantly decreased in EAA compared to IPF and sarcoidosis (25.5% ± 0.7% vs 59.8% ± 25.1% and 64.0% ± 19.7%, respectively) (P < 0.05). No significant correlation between PAS positive cells and inflammatory cells was observed. These results suggest that PAS staining of BAL cells may provide additional information in the differential diagnosis of ILD. Further studies ware warranted to evaluate PAS staining in larger numbers of BAL from patients with ILD.     

Analysis of bronchoalveolar lavage fluid proteome from systemic sclerosis patients with or without functional, clinical and radiological signs of lung fibrosis

Lung fibrosis is a major cause of mortality and morbidity in systemic sclerosis (SSc). However, its pathogenesis still needs to be elucidated. We examined whether the alteration of certain proteins in bronchoalveolar lavage fluid (BALF) might have a protective or a causative role in the lung fibrogenesis process. For this purpose we compared the BALF protein profile obtained from nine SSc patients with lung fibrosis (SSc_Fib+) with that obtained from six SSc patients without pulmonary fibrosis (SSc_Fib-) by two-dimensional gel electrophoresis (2-DE). Only spots and spot-trains that were consistently expressed in a different way in the two study groups were taken into consideration. In total, 47 spots and spot-trains, corresponding to 30 previously identified proteins in human BALF, showed no significant variation between SSc_Fib+ patients and SSc_Fib- patients, whereas 24 spots showed a reproducible significant variation in the two study groups. These latter spots corresponded to 11 proteins or protein fragments, including serum albumin fragments (13 spots), 5 previously recognized proteins (7 spots), and 4 proteins (3 spots) that had not been previously described in human BALF maps, namely calumenin, cytohesin-2, cystatin SN, and mitochondrial DNA topoisomerase 1 (mtDNA TOP1). Mass analysis did not determine one protein-spot. The two study groups revealed a significant difference in BALF protein composition. Whereas levels of glutathione S-transferase P (GSTP), Cu–Zn superoxide dismutase (SOD) and cystatin SN were downregulated in SSc_Fib+ patients compared with SSc_Fib- patients, we observed a significant upregulation of α1-acid glycoprotein, haptoglobin-α chain, calgranulin (Cal) B, cytohesin-2, calumenin, and mtDNA TOP1 in SSc_Fib+ patients. Some of these proteins (GSTP, Cu–Zn SOD, and cystatin SN) seem to be involved in mechanisms that protect lungs against injury or inflammation, whereas others (Cal B, cytohesin-2, and calumenin) seem to be involved in mechanisms that drive lung fibrogenesis. Even if the 2-DE analysis of BALF did not provide an exhaustive identification of all BALF proteins, especially those of low molecular mass, it allows the identification of proteins that might have a role in lung fibrogenesis. Further longitudinal studies on larger cohorts of patients will be necessary to assess their usefulness as predictive markers of disease.     

Determinants of bronchoalveolar lavage cellularity in idiopathic pulmonary fibrosis.

To investigate factors that determine bronchoalveolar lavage (BAL) cellularity in patients with idiopathic pulmonary fibrosis (IPF), we compared BAL cells in patients with IPF (n = 83) to both nonsmoking (n = 111) and smoking (n = 19) normal volunteers. Patients with IPF had higher concentrations of BAL total cells and alveolar macrophages than nonsmoking volunteers and more BAL neutrophils and eosinophils than normal volunteers regardless of smoking status. Among patients with IPF, the numbers of alveolar macrophages, neutrophils, or eosinophils were strongly associated with either smoking status or pack-years of cigarette smoking. In fact, after accounting for cigarette smoking, using multivariate analysis, the only additional factors that were found to be associated with BAL cellularity were age (macrophages and eosinophils) and the percent predicted forced expired volume in 1 s (neutrophils). Additional multivariate models failed to identify a significant relationship between BAL cellularity and either the type of immunosuppressive therapy or other physiological measures of lung function. We conclude that cigarette smoking strongly influences BAL cellularity in patients with IPF. These findings suggest that cigarette smoking may have a role in the pathogenesis of IPF or may adversely affect the prognosis in patients with IPF.     

Macrophage derived chemokine (CCL22), thymus and activation-regulated chemokine (CCL17), and CCR4 in idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronically progressive interstitial lung disease of unknown etiology. Previously, we have demonstrated the selective upregulation of the macrophage-derived chemokine CCL22 and the thymus activation-regulated chemokine CCL17 among chemokines, in a rat model of radiation pneumonitis/pulmonary fibrosis and preliminarily observed an increase in bronchoalveolar (BAL) fluid CCL22 levels of IPF patients.

Methods

We examined the expression of CCR4, a specific receptor for CCL22 and CCL17, in bronchoalveolar lavage (BAL) fluid cells, as well as the levels of CCL22 and CCL17, to elucidate their pathophysiological roles in pulmonary fibrosis. We also studied their immunohistochemical localization.

Results

BAL fluid CCL22 and CCL17 levels were significantly higher in patients with IPF than those with collagen vascular diseases and healthy volunteers, and there was a significant correlation between the levels of CCL22 and CCL17 in patients with IPF. CCL22 levels in the BAL fluid did not correlate with the total cell numbers, alveolar lymphocytes, or macrophages in BAL fluid. However, the CCL22 levels significantly correlated with the numbers of CCR4-expressing alveolar macrophages. By immunohistochemical and immunofluorescence analysis, localization of CCL22 and CCR4 to CD68-positive alveolar macrophages as well as that of CCL17 to hyperplastic epithelial cells were shown. Clinically, CCL22 BAL fluid levels inversely correlated with DLco/VA values in IPF patients.

Conclusion

We speculated that locally overexpressed CCL22 may induce lung dysfunction through recruitment and activation of CCR4-positive alveolar macrophages.     

Immunoglobulin free light chains are increased in hypersensitivity pneumonitis and idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF), a devastating lung disorder of unknown aetiology, and chronic hypersensitivity pneumonitis (HP), a disease provoked by an immunopathologic reaction to inhaled antigens, are two common interstitial lung diseases with uncertain pathogenic mechanisms. Previously, we have shown in other upper and lower airway diseases that immunoglobulin free light chains (FLCs) are increased and may be involved in initiating a local inflammation. In this study we explored if such a mechanism may also apply to HP and IPF.

Methods

In this study we examined the presence of FLC in serum and BAL fluid from 21 IPF and 22 HP patients and controls. IgG, IgE and tryptase concentrations were measured in BAL fluid only. The presence of FLCs, plasma cells, B cells and mast cells in lung tissue of 3 HP and 3 IPF patients and 1 control was analyzed using immunohistochemistry.

Results

FLC concentrations in serum and BAL fluid were increased in IPF and HP patients as compared to control subjects. IgG concentrations were only increased in HP patients, whereas IgE concentrations were comparable to controls in both patient groups. FLC-positive cells, B cells, plasma cells, and large numbers of activated mast cells were all detected in the lungs of HP and IPF patients, not in control lung.

Conclusion

These results show that FLC concentrations are increased in serum and BAL fluid of IPF and HP patients and that FLCs are present within affected lung tissue. This suggests that FLCs may be involved in mediating pathology in both diseases.     

Increased levels of free circulating DNA in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is difficult to diagnose because of numerous interstitial lung diseases with similar symptoms. As serum DNA has proven useful for early lung cancer detection, we aimed to define the relevance of this marker in discriminating IPF from other fibrotic and nonfibrotic/nonmalignant lung diseases. DNA was quantified in 191 subjects: 64 healthy individuals, 58 patients with IPF, 17 patients with nonspecific pulmonary fibrosis (13 idiopathic nonspecific interstitial pneumonia, 4 chronic hypersensitivity pneumonitis), and 52 patients with other diffuse/nonmalignant lung diseases. The median value of free DNA in IPF patients was 61.1 ng/mL (range 7.1-405), which was significantly higher than that of healthy donors (median 6.8, range 2.2-184) (p<0.001) and that of patients with other diffuse/nonmalignant lung diseases (median 28.0, range 4.2-281) (p=0.004). The area under the ROC curve was 0.926 (95% CI 0.879-0.973) when IPF patients were compared with healthy donors, and 0.702 (95% CI 0.609-0.796) when a comparison was made with non-IPF pulmonary diseases. In conclusion, we observed significantly higher levels of free circulating DNA in patients with IPF than in those with other fibrotic or diffuse/nonmalignant lung diseases.     

Activation of discoidin domain receptor 1 on CD14-positive bronchoalveolar lavage fluid cells induces chemokine production in idiopathic pulmonary fibrosis

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase activated by collagen. We previously reported the functional expression of DDR1 on human monocyte-derived macrophages in vitro; however, information regarding its role in diseases is limited. Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease, and the lesions contain an abundance of collagen. In this study, we examined DDR1 expression on bronchoalveolar lavage fluid (BALF) cells and investigated its functionality using samples obtained from 28 IPF patients, 13 chronic obstructive pulmonary disease patients, and 14 healthy volunteers. The DDR1 expression level in CD14-positive BALF cells was higher in IPF patients than in chronic obstructive pulmonary disease patients or healthy volunteers. The predominant isoform was DDR1b in the IPF group, while DDR1a was predominant in the other two groups. Using immunohistochemical analysis, we also detected DDR1 expression on infiltrating inflammatory cells in the IPF lesion. In IPF patients, DDR1 activation induced the production of MCP-1, IL-8, MIP-1 alpha, and matrix metalloproteinase-9 (MMP-9) from CD14-positive BALF cells in a p38 MAPK-dependent manner. In contrast, DDR1 activation of CD14-positive BALF cells in the other groups did not induce the production of these chemokines or MMP-9. These chemokines and MMP-9 contribute to the development of IPF and, therefore, we suggest that DDR1 might be associated with the pathogenesis of IPF in the tissue microenvironment.     

Targeting anti-aging protein sirtuin (Sirt) in the diagnosis of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severe, incurable, age-associated respiratory disorder that has gained significance because of its unknown etiology and lack of therapeutic approaches. IPF causes maximum damage to the alveolar epithelial cells, thereby leading to lung remodeling and initiating epithelial to mesenchymal transition (EMT). The actual molecular mechanisms underlying IPF still remain unclear, and knowledge about these mechanisms would be helpful in its diagnosis. Sirtuins (Sirt) are class of NAD+-dependent proteins, widely known to exert positive and protective effects on age-related diseases such as diabetes, cancer, and so on, and are also involved in regulating IPF. The sirtuin family comprises of seven members (Sirt1 to Sirt7), out of which Sirt1, Sirt3, Sirt6, and Sirt7 exert positive effects on IPF. Sirt1 is associated with aging and inhibits cellular senescence and fibrosis. Sirt1 is well recognized in controlling pulmonary fibrosis and is also considered as a prime positive mediator of EMT. The expressions of Sirt3 protein tend to decline in IPF patients; hence it is known as an anti-fibrotic protein. Sirt6 indeed has been proven to reduce EMT during IPF. Decreased levels of Sirt7 during IPF regulate lung fibroblasts. Hence, active levels of Sirt1, Sirt3, Sirt6, and Sirt7 can be attractive target models to elucidate a novel potential therapeutic approach for IPF. In this prospect, we have discussed the role of Sirtuins in pulmonary fibrosis by exploring the recent research evidence that highlight the role of sirtuins and also describes their protective effects.     

Surfactant protein A and B genetic variants predispose to idiopathic pulmonary fibrosis

Derangement in pulmonary surfactant or its components and alveolar collapse are common findings in idiopathic pulmonary fibrosis (IPF). Surfactant proteins play important roles in innate host defense and normal function of the lung. We examined associations between IPF and genetic polymorphic variants of surfactant proteins, SP-A1, SP-A2, SP-B, SP-C, and SP-D. One SP-A1 (6A⁴) allele and single nucleotide polymorphisms (SNPs) that characterize the 6A⁴ allele, and one SP-B (B1580_C) were found with higher frequency (P0.01) in nonsmoker and smoker IPF (n=84) subgroups, respectively, compared with healthy controls (n=194). To explore whether a tryptophan (present in 6A⁴) or an arginine (present in other SP-A1 alleles and in all SP-A2 alleles) at amino acid 219 alters protein behavior, two truncated proteins that varied only at amino acid 219 were oxidized by exposure to ozone. Differences in the absorption spectra (310–350 nm) between the two truncated recombinant SP-A proteins were observed both before and after protein oxidation, suggesting allele-specific aggregation differences attributable to amino acid 219. The SP-B SNP B1580_C (odds ratio:7.63; confidence interval:1.64–35.4; P0.01), to be a risk factor for IPF smokers, has also been shown to be a risk factor for other pulmonary diseases. The SP-C and SP-D SNPs and SP-B-linked microsatellite markers studied did not associate with IPF. These findings indicate that surfactant protein variants may serve as markers to identify subgroups of patients at risk, and we speculate that these contribute to IPF pathogenesis.     

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.     

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a non-neoplastic pulmonary disease that is characterized by the formation of scar tissue within the lungs in the absence of any known provocation. IPF is a rare disease which affects approximately 5 million persons worldwide. The prevalence is estimated to be slightly greater in men (20.2/100,000) than in women (13.2/100,000). The mean age at presentation is 66 years. IPF initially manifests with symptoms of exercise-induced breathless and dry coughing. Auscultation of the lungs reveals early inspiratory crackles, predominantly located in the lower posterior lung zones upon physical exam. Clubbing is found in approximately 50% of IPF patients. Cor pulmonale develops in association with end-stage disease. In that case, classic signs of right heart failure may be present. Etiology remains incompletely understood. Some environmental factors may be associated with IPF (cigarette smoking, exposure to silica and livestock). IPF is recognized on high-resolution computed tomography by peripheral, subpleural lower lobe reticular opacities in association with subpleural honeycomb changes. IPF is associated with a pathological lesion known as usual interstitial pneumonia (UIP). The UIP pattern consists of normal lung alternating with patches of dense fibrosis, taking the form of collagen sheets. The diagnosis of IPF requires correlation of the clinical setting with radiographic images and a lung biopsy. In the absence of lung biopsy, the diagnosis of IPF can be made by defined clinical criteria that were published in guidelines endorsed by several professional societies. Differential diagnosis includes other idiopathic interstitial pneumonia, connective tissue diseases (systemic sclerosis, polymyositis, rheumatoid arthritis), forme fruste of autoimmune disorders, chronic hypersensitivity pneumonitis and other environmental (sometimes occupational) exposures. IPF is typically progressive and leads to significant disability. The median survival is 2 to 5 years from the time of diagnosis. Medical therapy is ineffective in the treatment of IPF. New molecular therapeutic targets have been identified and several clinical trials are investigating the efficacy of novel medication. Meanwhile, pulmonary transplantation remains a viable option for patients with IPF. It is expected that, during the next decade, considerable progress will be made toward the understanding and treatment of this devastating illness.