Cigarette smoke exposure potentiates bleomycin-induced lung fibrosis in guinea pigs

Environmental tobacco smoke exposure exaggerates bleomycin-induced collagen overexpression during pulmonary fibrogenesis

Environmental tobacco smoke (ETS) is known to cause lung inflammatory and injurious responses. Smoke exposure is associated with the pathobiology related to lung fibrosis, whereas the mechanism that ETS exposure augments pulmonary fibrogenesis is unclear. We hypothesized that ETS exposure could exacerbate fibrotic responses via collagen dynamic dysregulation and complement activation. C57BL/6J and p16-3MR mice were exposed to ETS followed by bleomycin administration. ETS exposure exacerbated bleomycin-induced collagen and lysyl oxidase overexpression in the fibrotic lesion. ETS exposure also led to augmented bleomycin-induced upregulation of C3 and C3AR, which are pro-fibrotic markers. Moreover, overexpressed collagens and C3 levels were highly significant in males than females. The old mice (17 months old) were exposed to ETS and treated with bleomycin to induce fibrogenesis which is considered as an aging-associated disease. Fewer gene and protein dysregulations trends were identified between ETS exposure with the bleomycin group and the bleomycin alone group in old mice. Based on our findings, we suggested that ETS exposure increases the risk of developing severe lung fibrotic responses via collagen overexpression and lysyl oxidase-mediated collagen stabilization in the fibrotic lesion, and potentially affected the complement system activation induced by bleomycin. Further, male mice were more susceptible than females during fibrogenesis exacerbation. Thus ETS and bleomycin induced lung fibrotic changes via collagen-lysyl oxidase in an age-dependent mechanism.

Environmental tobacco smoke exposure exaggerates bleomycin- induced collagen overexpression during pulmonary fibrogenesis

Environmental tobacco smoke (ETS) is known to cause lung inflammatory and injurious responses. Smoke exposure is associated with the pathobiology related to lung fibrosis, whereas the mechanism by which ETS exposure augments lung fibrogenesis is unclear. We hypothesized that ETS exposure could exacerbate fibrotic responses via collagen dynamic dysregulation and complement activation. C57BL/6J and p16-3MR mice were exposed to ETS followed by bleomycin administration. ETS exposure exacerbated bleomycin-induced collagen and lysyl oxidase overexpression in the fibrotic lesion. ETS exposure also led to augmented bleomycin-induced upregulation of C3 and C3AR, which are pro-fibrotic markers. Moreover, overexpressed collagens and C3 levels were highly significant in males than females. The old mice (17 months old) were exposed to ETS and treated with bleomycin to induce fibrogenesis, since fibrogenesis is an aging-associated disease. Fewer gene and protein dysregulations trends were identified between ETS exposure with the bleomycin group and the bleomycin alone group in old mice. Based on our findings, we suggested that ETS exposure increases the risk of developing severe lung fibrotic responses via collagen overexpression and lysyl oxidase-mediated collagen stabilization in the fibrotic lesion. ETS exposure also potentially affected the complement system activation induced by bleomycin. Further, male mice were more susceptible than females during fibrogenesis exacerbation.

Targeting the AXL Receptor in Combating Smoking-related Pulmonary Fibrosis

Tobacco smoking is a well-known risk factor for both fibrogenesis and fibrotic progression; however, the mechanisms behind these processes remain enigmatic. RTKs (receptor tyrosine kinases) have recently been reported to drive profibrotic phenotypes in fibroblasts during pulmonary fibrosis (PF). Using a phospho-RTK array screen, we identified the RTK AXL as a top upregulated RTK in response to smoke. Both expression and signaling activity of AXL were indeed elevated in lung fibroblasts exposed to tobacco smoke, whereas no significant change to the levels of a canonical AXL ligand, Gas6 (growth arrest-specific 6), was seen upon smoke treatment. Notably, we found that smoke-exposed human lung fibroblasts exhibited highly proliferative and invasive activities and were capable of inducing fibrotic lung lesions in mice. Conversely, genetic suppression of AXL in smoke-exposed fibroblasts cells led to suppression of AXL downstream pathways and aggressive phenotypes. We further demonstrated that AXL interacted with MARCKS (myristoylated alanine-rich C kinase substrate) and cooperated with MARCKS in regulating downstream signaling activity and fibroblast invasiveness. Pharmacological inhibition of AXL with AXL-specific inhibitor R428 showed selectivity for smoke-exposed fibroblasts. In all, our data suggest that AXL is a potential marker for smoke-associated PF and that targeting of the AXL pathway is a potential therapeutic strategy in treating tobacco smoking-related PF.

Mesenchymal-Epithelial Transition in Fibroblasts of Human Normal Lungs and Interstitial Lung Diseases

In passages above ten and growing very actively, we observed that some human lung fibroblasts cultured under standard conditions were transformed into a lineage of epithelial-like cells (ELC). To systematically evaluate the possible mesenchymal–epithelial transition (MET) occurrence, fibroblasts were obtained from normal lungs and also from lungs affected by idiopathic interstitial diseases. When an unusual epithelial-like phenotypic change was observed, cultured cells were characterized by confocal immunofluorescence microscopy, immunoblotting, immunocytochemistry, cytofluorometry, gelatin zymography, RT-qPCR, and hybridization in a whole-transcript human microarray. Additionally, microvesicles fraction (MVs) from ELC and fibroblasts were used to induce MET, while the microRNAs (miRNAs) contained in the MVs were identified. Pattern-gene expression of the original fibroblasts and the derived ELC revealed profound changes, upregulating characteristic epithelial-cell genes and downregulating mesenchymal genes, with a marked increase of E-cadherin, cytokeratin, and ZO-1, and the loss of expression of α-SMA, collagen type I, and Thy-1 cell surface antigen (CD90). Fibroblasts, exposed to culture media or MVs from the ELC, acquired ELC phenotype. The miRNAs in MVs shown six expressed exclusively in fibroblasts, and three only in ELC; moreover, twelve miRNAs were differentially expressed between fibroblasts and ELC, all of them but one was overexpressed in fibroblasts. These findings suggest that the MET-like process can occur in human lung fibroblasts, either from normal or diseased lungs. However, the biological implication is unclear.

Metabolic reprogramming: A driver of cigarette smoke-induced inflammatory lung diseases

Cigarette smoking is a well-known risk factor for pulmonary diseases, including chronic obstructive pulmonary disease (COPD), asthma and pulmonary fibrosis. Despite major progress in dissecting the mechanisms associated with disease development and progression, findings only represent one aspect of multifaceted disease. A crucial consequence of this approach is that many therapeutic treatments often fail to improve or reverse the disease state as other conditions and variables are insufficiently considered. To expand our understanding of pulmonary diseases, omics approaches, particularly metabolomics, has been emerging in the field. This strategy has been applied to identify putative biomarkers and novel mechanistic insights. In this review, we discuss metabolic profiles of patients with COPD, asthma, and idiopathic pulmonary fibrosis (IPF) with a focus on the direct effects of cigarette smoking in altering metabolic regulation. We next present cell- and animal-based experiments and point out the therapeutic potential of targeting metabolic reprogramming in inflammatory lung diseases. In addition, the obstacles in translating these findings into clinical practice, including potential adverse effects and limited pharmacological efficacy, are also addressed.

Inhalation exposure by cigarette smoke: Effects on the progression of bleomycin- and lipopolysaccharide-induced lung injuries in rat models

The toxic substances of cigarette smoke (CS) induce inflammatory responses in the lung by recruiting inflammatory cells. In this study, we investigated the effects of CS on the progression of lung disease in bleomycin (BLM) and lipopolysaccharide (LPS)-induced lung injury rat models. Briefly, rats were exposed to CS via inhalation (nose-only) for 28 consecutive days, for 4 h per day. Using an automatic video instillator, rats were administered a single dose of 2.5 mg/kg BLM (day 1) or 0.5 mg/kg LPS (day 26), prepared in 50 μL phosphate-buffered saline (PBS) solution. Examination of the bronchoalveolar lavage fluid (BALF) revealed that the number of neutrophils increased in a concentration-dependent manner of CS. Exposure to CS also enhanced the expression of cytokines, i.e., CCL2 (MCP-1), CCL3 (MIP-1α), CXCL2 (CINC3), CXCL10 (IP-10), TNF-α, IFN-γ, IL-2, IL-4 in the BALF of the vehicle (VC) and BLM groups in a concentration-dependent manner. In particular, the expressions of CCL2, CXCL10 and TNF-α were remarkably upregulated in the BLM + CS 300 treatment as compared to VC, while there were no differences in these cytokine levels in the serum following CS exposure. Exposure to CS resulted in compacted alveolar spaces and macrophage aggregation in the lung tissues following BLM and LPS treatments. Compared to VC, pulmonary fibrosis and chronic inflammation of bronchioloalveoli were observed in the BLM + CS treatment and inflammatory cell infiltration of bronchioloalveoli was observed in the LPS + CS treatment in a concentration-dependent manner by CS. The expression levels of CCL2 and IFN-γ in the lung tissues were increased similar to the levels obtained in BALF, in a concentration-dependent manner by CS. Taken together, these results indicate that repeated exposure to CS may exacerbate the lung injury initially caused by BLM and LPS.

Toxicological implication of prostaglandin transporter SLCO2A1 inhibition by cigarette smoke in exacerbation of lung inflammation

We reported that bleomycin (BLM)-induced pulmonary fibrosis was exacerbated in the prostaglandin transporter gene (Slco2a1)-deficient mice (Slco2a1(-/-)). Because cigarette smoke (CS) contributes to creating a profibrotic milieu in the respiratory region, the present study aimed to investigate the impact of CS on SLCO2A1-associated pathogenesis in the lungs of BLM-instilled mice. Bronchoalveolar lavage (BAL) fluid cell analysis indicated more severe inflammation in Slco2a1(-/-) on day 5 after BLM intratracheal instillation, and Slco2a1 deletion increased mRNA expression of pro-inflammatory cytokines (Tnf-α and Il-1β) and chemokine (Ccl5) in BAL cells. Male Slco2a1(-/-) exhibited significantly higher amounts of released Il-1β in BAL fluid, compared with female Slco2a1(-/-), male or female Slco2a1(+/+) group. The amount of PGE₂ collected in BAL fluid tended to increase in Slco2a1(-/-) compared with Slco2a1(+/+) group, whereas the PGE₂ concentrations in lung tissues were comparable between both groups. Besides, PGE₂ accumulated more in BAL fluid of male than that of female mice. Therefore, Slco2a1-deficient male mice were found to be more susceptible to BLM-treatment. Moreover, CS extracts (CSE) significantly reduced initial PGE₂ uptake by rat type1 alveolar epithelial cell-like (AT1-L) cells and human SLCO2A1-transfected cells. Exposure of AT1-L cells to CSE resulted in decreased mRNA expression of Slco2a1, suggesting that CS modulates SLCO2A1 function. These results indicate that exacerbated lung inflammation is attributed to an increase in Il-1β peptide and PGE₂ accumulation in the alveolar space, which exhibits a male predominance. SLCO2A1 inhibition by CSE is considered to be a new rationale for the lung toxicity of CS.

Identification of apoptosis-associated protein factors distinctly expressed in cigarette smoke condensate-exposed airway bronchial epithelial cells

Smoking is associated with an increased risk of respiratory diseases, including lung cancer and asthma. However, the mechanisms or diagnostic markers for smoking-related diseases remain largely unknown. Here we investigated the role of cigarette smoke condensate (CSC) in the regulation of human bronchial epithelial cell (BEAS-2B) behavior. We found that exposure to CSC significantly inhibited BEAS-2B cell viability, impaired cell morphology, induced cell apoptosis, triggered oxidative damage, and promoted inflammatory response, which suggests a deleterious effect of CSC on bronchial epithelial cells. In addition, CSC markedly altered the expression of apoptosis-associated protein factors, including p21, soluble tumor necrosis factor receptor 1, and Fas ligand. In sum, our study identified a panel of novel protein factors that may mediate the actions of CSC on bronchial epithelial cells and have a predictive value for the development and progression of smoking-related diseases, thus providing insights into the development of potential diagnostic and therapeutic strategies against these diseases.

Idiopathic Pulmonary Fibrosis: Epidemiology, Natural History, Phenotypes

Idiopathic pulmonary fibrosis (IPF) is the most common of the idiopathic interstitial pneumonias. It is characterized by a chronic, progressive, fibrotic interstitial lung disease of unknown cause that occurs primarily in older adults. Its prevalence and incidence have appeared to be increasing over the last decades. Despite its unknown nature, several genetic and environmental factors have been associated with IPF. Moreover, its natural history is variable, but could change depending on the currently suggested phenotypes: rapidly progressive IPF, familial, combined pulmonary fibrosis and emphysema, pulmonary hypertension, and that associated with connective tissue diseases. Early recognition and accurate staging are likely to improve outcomes and induce a prompt initiation of antifibrotics therapy. Treatment is expected to be more effective in the early stages of the disease, while developments in treatment aim to improve the current median survival of 3⁻4 years after diagnosis.

Modelling the asthma phenotype: impact of cigarette smoke exposure

Background

Asthmatics that are exposed to inhaled pollutants such as cigarette smoke (CS) have increased symptom severity. Approximately 25% of adult asthmatics are thought to be active smokers and many sufferers, especially in the third world, are exposed to high levels of inhaled pollutants. The mechanism by which CS or other airborne pollutants alter the disease phenotype and the effectiveness of treatment in asthma is not known. The aim of this study was to determine the impact of CS exposure on the phenotype and treatment sensitivity of rodent models of allergic asthma.

Methods

Models of allergic asthma were configured that mimicked aspects of the asthma phenotype and the effect of CS exposure investigated. In some experiments, treatment with gold standard asthma therapies was investigated and end-points such as airway cellular burden, late asthmatic response (LAR) and airway hyper-Reactivity (AHR) assessed.

Results

CS co-exposure caused an increase in the LAR but interestingly attenuated the AHR. The effectiveness of LABA, LAMA and glucocorticoid treatment on LAR appeared to be retained in the CS-exposed model system. The eosinophilia or lymphocyte burden was not altered by CS co-exposure, nor did CS appear to alter the effectiveness of glucocorticoid treatment. Steroids, however failed to reduce the neutrophilic inflammation in sensitized mice exposed to CS.

Conclusions

These model data have certain parallels with clinical findings in asthmatics, where CS exposure did not impact the anti-inflammatory efficacy of steroids but attenuated AHR and enhanced symptoms such as the bronchospasm associated with the LAR. These model systems may be utilised to investigate how CS and other airborne pollutants impact the asthma phenotype; providing the opportunity to identify novel targets.

Plasma membrane wounding and repair in pulmonary diseases

Various pathophysiological conditions such as surfactant dysfunction, mechanical ventilation, inflammation, pathogen products, environmental exposures, and gastric acid aspiration stress lung cells, and the compromise of plasma membranes occurs as a result. The mechanisms necessary for cells to repair plasma membrane defects have been extensively investigated in the last two decades, and some of these key repair mechanisms are also shown to occur following lung cell injury. Because it was theorized that lung wounding and repair are involved in the pathogenesis of acute respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF), in this review, we summarized the experimental evidence of lung cell injury in these two devastating syndromes and discuss relevant genetic, physical, and biological injury mechanisms, as well as mechanisms used by lung cells for cell survival and membrane repair. Finally, we discuss relevant signaling pathways that may be activated by chronic or repeated lung cell injury as an extension of our cell injury and repair focus in this review. We hope that a holistic view of injurious stimuli relevant for ARDS and IPF could lead to updated experimental models. In addition, parallel discussion of membrane repair mechanisms in lung cells and injury-activated signaling pathways would encourage research to bridge gaps in current knowledge. Indeed, deep understanding of lung cell wounding and repair, and discovery of relevant repair moieties for lung cells, should inspire the development of new therapies that are likely preventive and broadly effective for targeting injurious pulmonary diseases.

Cigarette Smoke Enhances the Expression of Profibrotic Molecules in Alveolar Epithelial Cells

Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal disease of unknown etiology. A growing body of evidence indicates that it may result from an aberrant activation of alveolar epithelium, which induces the expansion of the fibroblast population, their differentiation to myofibroblasts and the excessive accumulation of extracellular matrix. The mechanisms that activate the alveolar epithelium are unknown, but several studies indicate that smoking is the main environmental risk factor for the development of IPF. In this study we explored the effect of cigarette smoke on the gene expression profile and signaling pathways in alveolar epithelial cells. Lung epithelial cell line from human (A549), was exposed to cigarette smoke extract (CSE) for 1, 3, and 5 weeks at 1, 5 and 10% and gene expression was evaluated by complete transcriptome microarrays. Signaling networks were analyzed with the Ingenuity Pathway Analysis software. At 5 weeks of exposure, alveolar epithelial cells acquired a fibroblast-like phenotype. At this time, gene expression profile revealed a significant increase of more than 1000 genes and deregulation of canonical signaling pathways such as TGF-β and Wnt. Several profibrotic genes involved in EMT were over-expressed, and incomplete EMT was observed in these cells, and corroborated in mouse (MLE-12) and rat (RLE-6TN) epithelial cells. The secretion of activated TGF-β1 increased in cells exposed to cigarette smoke, which decreased when the integrin alpha v gene was silenced. These findings suggest that the exposure of alveolar epithelial cells to CSE induces the expression and release of a variety of profibrotic genes, and the activation of TGF-β1, which may explain at least partially, the increased risk of developing IPF in smokers.

Associations of MMP1, MMP2 and MMP3 Genes Polymorphism with Coal Workers' Pneumoconiosis in Chinese Han Population

Coal workers’ pneumoconiosis (CWP) has been associated with abnormalities in the extracellular matrix remodeling, as well as aberrant matrix metalloproteinases (MMPs) in lung tissues. We investigated the association of three functional polymorphisms in MMP gene promoters (MMP1 rs1799750, MMP2 rs2285053 and MMP3 rs522616) with the risk of CWP. A total of 693 CWP cases and 690 controls were included in a case-control study. Genotype analysis was performed by the TaqMan method. Statistically significant differences were found in distributions of MMP3 rs522616 under a recessive model (p = 0.047) between CWP cases and controls. In the stratification analysis, individuals with MMP3 rs522616 GG genotype decreased the risk of CWP (adjusted OR = 0.72, 95% CI = 0.52–0.99) compared to those with AA/AG genotype obviously, particularly among subgroups of no smokers (adjusted OR = 0.64, 95% CI = 0.41–1.00). Furthermore, serum MMP3 protein levels measured with enzyme-linked immune-sorbent assay in the control group was significantly lower than that in the CWP groups (p = 0.02). Extremely lower MMP3 among subjects with the rs522616 GG or AG genotype compared with the AA genotype carriers (p < 0.05, p < 0.01 respectively) in the normal serum. These findings indicate that the MMP3 rs522616 polymorphism may contribute to the etiology of CWP in the Chinese population and MMP3 might be a potential diagnostic biomarker for CWP, additional independent studies are warranted to validate our findings in different populations as well as in a larger series.

Effects of the Interactions between Dust Exposure and Genetic Polymorphisms in Nalp3, Caspase-1, and IL-1β on the Risk of Silicosis: A Case-Control Study

Objectives

To evaluate the effects of the interactions between polymorphisms in Nalp3, caspase-1, and interleukin(IL)-1β genes and occupational dust exposure on the risk of silicosis.

Methods

We conducted a population-based case-control study in a large iron mine in China. Between January 2006 and December 2009, we identified 179 patients with silicosis to evaluate as cases and 201 individuals without silicosis to evaluate as controls. We estimated cumulative dust exposure (CDE) for all subjects and we genotyped polymorphisms in Nalp3, caspase-1, and IL-1β genes. We estimated odds ratios(ORs), 95% confidence intervals(95%CIs), and p-values using logistic regression models adjusted for selected confounders.

Results

After adjusting for age, smoking status, and CDE, subjects with the CT genotype of Ex4-849C>T in Nalp3 and the GA genotype of Ex2+37G>A in caspase-1 had increased risks of silicosis (adjusted ORs[95%CIs] = 2.40 [1.12–5.12] and 3.62 [1.63–8.02], respectively). Among subjects younger than 70 years old, those with the CC genotype of IVS8-7652A>C in Nalp3 had a lower risk of silicosis than those with other genotypes (adjusted OR[95%CI] = 0.24[0.06–0.88]). Among subjects aged 70 years and older, those with the CT genotype of Ex4-849C>T in Nalp3 and those with the GA genotype of Ex2+37G>A in caspase-1 had a higher risk of silicosis than those with other genotypes (adjusted ORs [95%CI] = 2.52[1.04–6.12] and 5.19[1.88–14.35], respectively). Among subjects with CDE greater than 120 mg/m³×year and among smokers, those with the GA genotype of Ex2+37G>A in caspase-1 had a higher risk of silicosis than those with other genotypes (adjusted ORs[95%CIs] = 26.37[3.35–207.39] and 3.47[1.40–8.64], respectively).

Conclusions

Genetic polymorphisms in Nalp3 and caspase-1 may be associated with individual susceptibility to silicosis, especially when the polymorphisms interact with age, CDE, or smoking status.

Enhanced cough reflex in a model of bleomycin-induced lung fibrosis in guinea pigs

Fibrotic lung diseases, such as idiopathic pulmonary fibrosis, are associated with spontaneous dry cough and hypersensitivity to tussive agents. Understanding the pathophysiology driving enhanced cough may help us to define better therapies for patients. We hypothesized that lung fibrosis induced by intratracheal bleomycin would exacerbate the cough reflex induced by tussive agents in guinea pigs. Disease progression in the lungs was characterized at days 1, 7, 14, 21 and 28 after bleomycin administration. Inflammatory and fibrotic markers, as well as neurotrophin levels, were assessed in bronchoalveolar lavage fluid and/or lung tissue. Cough sensitivity to citric acid, capsaicin and allylisothiocyanate was evaluated in conscious animals at days 14 and 21 after bleomycin administration. Pulmonary lesions evolved from an early inflammatory phase (from day 1 to day 7) to a fibrotic stage (between days 14 and 28). Fibrosis was related to increased levels of matrix metalloproteinase-2 in bronchoalveolar lavage fluid (day 21: saline, 0.26 ng/ml; bleomycin, 0.49 ng/ml). At day 14, we also observed increased cough reflexes to citric acid (163%), capsaicin (125%) and allylisothiocyanate (178%). Cough exacerbation persisted, but at a lower extent, by day 21 for capsaicin (100%) and allylisothiocyanate (54%). Moreover, bronchoalveolar lavage fluid concentrations of brain-derived neurotrophic factor, suggested to induce nerve remodelling in chronic cough, were also enhanced (day 1: saline, 14.21 pg/ml; bleomycin, 30.09 pg/ml). In summary, our model of bleomycin-induced cough exacerbation may be a valuable tool to investigate cough hypersensitivity and develop antitussive therapies for fibrotic lung diseases.

Different profiles of notch signaling in cigarette smoke-induced pulmonary emphysema and bleomycin-induced pulmonary fibrosis

OBJECTIVE

Different profiles of Notch signaling mediate naive T cell differentiation which might be involved in pulmonary emphysema and fibrosis.

METHODS

C57BL/6 mice were randomized into cigarette smoke (CS) exposure, bleomycin (BLM) exposure, and two separate groups of control for sham exposure to CS or BLM. The paratracheal lymph nodes of the animals were analyzed by real-time PCR and immunohistochemistry. Morphometry of the lung parenchyma, measurement of the cytokines, and cytometry of the bronchoalveolar lavage fluid (BALF) were also done accordingly.

RESULTS

In comparison with controls, all Notch receptors and ligands were upregulated by chronic CS exposure, especially Notch3 and DLL1 (P < 0.01), and this was in line with emphysema-like morphology and Th1-biased inflammation. While Notch3 and DLL1 were downregulated by BLM exposure (P < 0.01), those was in line with fibrotic lung remodeling and Th2 polarization.

CONCLUSIONS

This founding implies that the CS exposure but not the BLM exposure is capable of initiating Notch signaling in lymphoid tissue of the lung, which is likely relevant to the pathogenesis of pulmonary emphysema. Unable to initiate the Th1 response or inhibit it may lead to Th2 polarization and aberrant repair.

MUC5B promoter polymorphisms and risk of coal workers' pneumoconiosis in a Chinese population

Coal workers' pneumoconiosis (CWP) is characterized by fibrosing nodular lesions that eventually develop into progressive pulmonary fibrosis. Genetic variations have been recognized to be involved in the multi-factorial susceptibility to CWP, and MUC5B is a candidate lung fibrosis susceptibility gene. In the present study, we investigated possible genetic associations between three single nucleotide polymorphisms in MUC5B promoter region and CWP in a case-control study including 686 CWP patients and 680 controls. Genotyping was carried out by TaqMan method. Only rs2672794 allele and genotype frequencies distributions were significantly different between CWP patients and controls (P = 0.017 and 0.046 for allele and genotype, respectively). The MUC5B rs2672794 CC genotype was associated with a significantly increased risk of CWP, compared with the TT genotype. Moreover, individuals with TC/CC genotype had an obviously increased risk of CWP than those with TT genotype, particularly among subgroups of dust exposure <27 years and smokers. This is the first report showing an association between the MUC5B rs2672794 polymorphism and CWP, and our results suggest that MUC5B rs2672794 CC genotype could increase the risk of CWP. Further studies are warranted to confirm our findings.

Syndecan-2 exerts antifibrotic effects by promoting caveolin-1-mediated transforming growth factor-β receptor I internalization and inhibiting transforming growth factor-β1 signaling

RATIONALE

Alveolar transforming growth factor (TGF)-β1 signaling and expression of TGF-β1 target genes are increased in patients with idiopathic pulmonary fibrosis (IPF) and in animal models of pulmonary fibrosis. Internalization and degradation of TGF-β receptor TβRI inhibits TGF-β signaling and could attenuate development of experimental lung fibrosis.

OBJECTIVES

To demonstrate that after experimental lung injury, human syndecan-2 confers antifibrotic effects by inhibiting TGF-β1 signaling in alveolar epithelial cells.

METHODS

Microarray assays were performed to identify genes differentially expressed in alveolar macrophages of patients with IPF versus control subjects. Transgenic mice that constitutively overexpress human syndecan-2 in macrophages were developed to test the antifibrotic properties of syndecan-2. In vitro assays were performed to determine syndecan-2-dependent changes in epithelial cell TGF-β1 signaling, TGF-β1, and TβRI internalization and apoptosis. Wild-type mice were treated with recombinant human syndecan-2 during the fibrotic phase of bleomycin-induced lung injury.

MEASUREMENTS AND MAIN RESULTS

We observed significant increases in alveolar macrophage syndecan-2 levels in patients with IPF. Macrophage-specific overexpression of human syndecan-2 in transgenic mice conferred antifibrotic effects after lung injury by inhibiting TGF-β1 signaling and downstream expression of TGF-β1 target genes, reducing extracellular matrix production and alveolar epithelial cell apoptosis. In vitro, syndecan-2 promoted caveolin-1-dependent internalization of TGF-β1 and TβRI in alveolar epithelial cells, which inhibited TGF-β1 signaling and epithelial cell apoptosis. Therapeutic administration of human syndecan-2 abrogated lung fibrosis in mice.

CONCLUSIONS

Alveolar macrophage syndecan-2 exerts antifibrotic effects by promoting caveolin-1-dependent TGF-β1 and TβRI internalization and inhibiting TGF-β1 signaling in alveolar epithelial cells. Hence, molecules that facilitate TβRI degradation via endocytosis represent potential therapies for pulmonary fibrosis.

Antineoplastic therapy-induced pulmonary toxicity

Pulmonary complications of antineoplastic therapy are common and are an important cause of respiratory morbidity. The pulmonary toxicity should be taken into account in every patient with respiratory problems who is or has been treated with antineoplastic agents. The diagnosis of drug-induced pulmonary toxicity is complex and should be based on the medical history, clinical, radiological and pathological findings. None of them are specific but they can guide the diagnostic process. The treatment of pulmonary abnormalities caused by chemotherapy is mostly supportive and based on cessation of the causative agent. However, the therapeutic options in oncology setting are usually limited thus the decision about changing the treatment should be taken with caution.

Vaccination with recombinant Mycobacterium tuberculosis PknD attenuates bacterial dissemination to the brain in guinea pigs

Background

We have previously identified Mycobacterium tuberculosis PknD to be an important virulence factor required for the pathogenesis of central nervous system (CNS) tuberculosis (TB). Specifically, PknD mediates bacillary invasion of the blood-brain barrier, which can be neutralized by specific antisera, suggesting its potential role as a therapeutic target against TB meningitis.

Methodology/Principal Findings

We utilized an aerosol challenge guinea pig model of CNS TB and compared the protective efficacy of recombinant M. tuberculosis PknD subunit protein with that of M. bovis BCG against bacillary dissemination to the brain. BCG vaccination limited the pulmonary bacillary burden after aerosol challenge with virulent M. tuberculosis in guinea pigs and also reduced bacillary dissemination to the brain (P = 0.01). PknD vaccination also offered significant protection against bacterial dissemination to the brain, which was no different from BCG (P>0.24), even though PknD vaccinated animals had almost 100-fold higher pulmonary bacterial burdens. Higher levels of PknD-specific IgG were noted in animals immunized with PknD, but not in BCG-vaccinated or control animals. Furthermore, pre-incubation of M. tuberculosis with sera from PknD-vaccinated animals, but not with sera from BCG-vaccinated or control animals, significantly reduced bacterial invasion in a human blood-brain barrier model (P<0.01).

Conclusion

Current recommendations for administering BCG at birth are based on protection gained against severe disease, such as TB meningitis, during infancy. We demonstrate that vaccination with recombinant M. tuberculosis PknD subunit offers a novel strategy to protect against TB meningitis, which is equivalent to BCG in a guinea pig model. Moreover, since BCG lacks the PknD sensor, BCG could also be boosted to develop a more effective vaccine against TB meningitis, a devastating disease that disproportionately affects young children.

Polymorphisms in inflammasome genes and risk of coal workers' pneumoconiosis in a Chinese population

Background

Coal workers' pneumoconiosis (CWP), resulting from the inhalation of silica-containing coal mine dust, is characterized by fibrosing nodular lesions that eventually develop into progressive pulmonary fibrosis. Recently, it has been hypothesized that inflammasomes could have a crucial role in the host response to silica and recent studies show that the inflammasome contributes to inflammation and pulmonary fibrosis. NLRP3, CARD8 are components of the NLRP3 inflammasome, which triggers caspase 1-mediated IL-1β and IL-18 release. In the present study, we investigated whether common single nucleotide polymorphisms (SNPs) in inflammasome genes are associated with CWP.

Methods

We performed an association study analyzing 3 NLRP3, 1 CARD8, 1 IL-1β, 2 IL-18 SNPs in a case-control study of 697 CWP and 694 controls. Genotyping was carried out by the TaqMan method.

Results

The NLRP3 rs1539019 TT genotype was associated with a significantly increased risk of CWP (adjusted odds ratio (OR) = 1.39, 95% confidence interval (CI) = 1.07–1.81), compared with the GG/GT genotype, in particular among smokers (adjusted OR = 1.67, 95%CI = 1.15–2.42). In addition, the polymorphism was significantly associated with risk of CWP patients with stage I.

Conclusions

This is the first report showing an association between the NLRP3 rs1539019 polymorphism and CWP, and suggests that this polymorphism may confer increased risk for the development of the disease. Further studies are warranted to confirm our findings.

Cigarette smoke and bleomycin-induced pulmonary oxidative stress in rats

Bleomycin causes pulmonary fibrosis by increasing free oxygen radicals. Cigarette smoke is a strong oxidant which adversely affects pulmonary tissue. We evaluated the effects of cigarette smoke administered with intratracheal bleomycin on pulmonary tissue. We studied 3 groups of rats (n=10): one group received intratracheal saline and served as a control; one received intratracheal bleomycin (IT) (0.5 U/100 g body weight, single dose on the first day), and one group received intratracheal bleomycin (single dose on first day) and tobacco smoke (two times per day) (IT-S). After 4 weeks, the levels of malondialdehyde (MDA) and nitric oxide (NO) and the activities of superoxide dismutase (SOD) and xanthine oxidase (XO) were assayed in the homogenate of the lung tissue samples. The severity of interstitial fibrosis was assessed using the grading system described by Ashcroft. There was more intensive fibrosis in the IT and IT-S than in the control samples (P<0.001). The levels of MDA, NO and activity of XO were significantly increased (P<0.001, <0.002 and <0.002, respectively), and SOD activity (P<0.001) was significantly decreased in the IT group when compared to these values in the control group. The concentration of NO was significantly decreased (P<0.002), and SOD activity was significantly increased (P<0.05) in the lung tissue samples of the IT-S group. Theoretically, the combination of cigarette smoke and bleomycin may have a synergistic effect on oxidative lung injury. In conclusion, we showed that inhalation of cigarette smoke provides protection against oxidative stress in the lung tissue of rats with bleomycin-induced pulmonary fibrosis.

Smoking and idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology with considerable morbidity and mortality. Cigarette smoking is one of the most recognized risk factors for development of IPF. Furthermore, recent work suggests that smoking may have a detrimental effect on survival of patients with IPF. The mechanism by which smoking may contribute to the pathogenesis of IPF is largely unknown. However, accumulating evidence suggests that increased oxidative stress might promote disease progression in IPF patients who are current and former smokers. In this review, potential mechanisms by which cigarette smoking affects IPF, the effects of cigarette smoking on accelerated loss of lung function in patients with IPF, key genetic studies evaluating the potential candidate genes and gene-environment (smoking) interaction, diagnosis, and treatment with emphasis on recently closed and ongoing clinical trials are presented.

Associations of IL-4, IL-4R, and IL-13 gene polymorphisms in coal workers' pneumoconiosis in China: a case-control study

BACKGROUND

The IL-4, IL-4 receptor (IL4R), and IL-13 genes are crucial immune factors and may influence the course of various diseases. In the present study, we investigated the association between the potential functional polymorphisms in IL-4, IL-4R, and IL-13 and coal workers' pneumoconiosis (CWP) risk in a Chinese population.

METHODS

Six polymorphisms (C-590T in IL-4, Ile50Val, Ser478Pro, and Gln551Arg in IL-4R, C-1055T and Arg130Gln in IL-13) were genotyped and analyzed in a case-control study of 556 CWP and 541 control subjects.

RESULTS

Our results revealed that the IL-4 CT/CC genotypes were associated with a significantly decreased risk of CWP (odds ratio (OR) = 0.74, 95% confidence interval (CI) = 0.58-0.95), compared with the TT genotype, particularly among subgroups of age <65 years (OR = 0.68, 95%CI = 0.46-0.99) and dust exposure years ≥26 years (OR = 0.69, 95%CI = 0.50-0.94). Moreover, the polymorphism was significantly associated with risk of CWP patients with stage I. In addition, a combined effect was observed in a dose-dependent manner with increasing numbers of risk variant alleles (P(trend) = 0.023), and individuals with 11-12 risk alleles had a 47% higher risk of CWP than those with 0-8 risk alleles (OR = 1.47, 95% CI = 1.05-2.05).

CONCLUSIONS

Our results suggest that the IL-4 C-590T polymorphism is involved in the etiology of CWP and susceptibility to this disease. Larger studies are warranted to validate our findings.

Workshop on idiopathic pulmonary fibrosis in older adults

Idiopathic pulmonary fibrosis (IPF), a heterogeneous disease with respect to clinical presentation and rates of progression, disproportionately affects older adults. The diagnosis of IPF is descriptive, based on clinical, radiologic, and histopathologic examination, and definitive diagnosis is hampered by poor interobserver agreement and lack of a consensus definition. There are no effective treatments. Cellular, molecular, genetic, and environmental risk factors have been identified for IPF, but the initiating event and the characteristics of preclinical stages are not known. IPF is predominantly a disease of older adults, and the processes underlying normal aging might significantly influence the development of IPF. Yet, the biology of aging and the principles of medical care for this population have been typically ignored in basic, translational, or clinical IPF research. In August 2009, the Association of Specialty Professors, in collaboration with the American College of Chest Physicians, the American Geriatrics Society, the National Institute on Aging, and the National Heart, Lung, and Blood Institute, held a workshop, summarized herein, to review what is known, to identify research gaps at the interface of aging and IPF, and to suggest priority areas for future research. Efforts to answer the questions identified will require the integration of geriatrics, gerontology, and pulmonary research, but these efforts have great potential to improve care for patients with IPF.

BAL in the diagnosis of smoking-related interstitial lung diseases: review of literature and analysis of our experience

The group of interstitial lung diseases (ILDs) is formed by respiratory tract disorders, whose aetiology is unknown in the majority of cases, the clinical course differs and the prognosis is generally serious. Some of the ILDs have a potential relation to tobacco smoking and are known as smoking-related ILDs (sr-ILD). Bronchoalveolar lavage fluid (BALF) examination is one of the initial procedures in the diagnosis of ILD. Despite the fact that histological confirmation is the gold standard in ILD diagnosis in many studies, the number of reported biopsies was low. In this review we present the results of BALF examinations of patients with sr-ILD and discuss their value in the differential diagnosis with other types of ILD. An extremely high total cell count (about 50 x 10(6) cells) with significant predominance of pigmented alveolar macrophages is a characteristic pattern of BALF in sr-ILD. The greatest challenge in BALF cytology interpretation is to distinguish sr-ILD and idiopathic pulmonary fibrosis (IPF). IPF is characterised by an elevated proportion and absolute count of lymphocytes and neutrophils; in addition, BALF lymphocytosis is higher in non-specific interstitial pneumonia than in usual interstitial pneumonia (UIP). The population of alveolar macrophage of patients with sr-ILD differs markedly from the foamy and vacuolated cells that predominate in IPF/UIP. Thus, the absence of pigmented cells rather excludes sr-ILD and indicates other types of ILD. To summarise, the place of BALF in the diagnosis of sr-ILD seems to be established.

Cigarette smoking is associated with subclinical parenchymal lung disease: the Multi-Ethnic Study of Atherosclerosis (MESA)-lung study

RATIONALE

Cigarette smoking is a risk factor for diffuse parenchymal lung disease. Risk factors for subclinical parenchymal lung disease have not been described.

OBJECTIVES

To determine if cigarette smoking is associated with subclinical parenchymal lung disease, as measured by spirometric restriction and regions of high attenuation on computed tomography (CT) imaging.

METHODS

We examined 2,563 adults without airflow obstruction or clinical cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis, a population-based cohort sampled from six communities in the United States. Cumulative and current cigarette smoking were assessed by pack-years and urine cotinine, respectively. Spirometric restriction was defined as a forced vital capacity less than the lower limit of normal. High attenuation areas on the lung fields of cardiac CT scans were defined as regions having an attenuation between -600 and -250 Hounsfield units, reflecting ground-glass and reticular abnormalities. Generalized additive models were used to adjust for age, gender, race/ethnicity, smoking status, anthropometrics, center, and CT scan parameters.

MEASUREMENTS AND MAIN RESULTS

The prevalence of spirometric restriction was 10.0% (95% confidence interval [CI], 8.9-11.2%) and increased relatively by 8% (95% CI, 3-12%) for each 10 cigarette pack-years in multivariate analysis. The median volume of high attenuation areas was 119 cm(3) (interquartile range, 100-143 cm(3)). The volume of high attenuation areas increased by 1.6 cm(3) (95% CI, 0.9-2.4 cm(3)) for each 10 cigarette pack-years in multivariate analysis.

CONCLUSIONS

Smoking may cause subclinical parenchymal lung disease detectable by spirometry and CT imaging, even among a generally healthy cohort.

Association of cytokine gene polymorphisms in CWP and its severity in Turkish coal workers

BACKGROUND

Cytokines appear to play a key role in some inflammatory reactions affecting the interactions among pro- and anti-inflammatory mechanisms that result in several diseases such as coal workers' pneumoconiosis (CWP). In this study, to determine the cytokine gene profiles of Turkish coal miners, we performed genotyping analysis to investigate the polymorphisms of CWP-related pro-inflammatory (TNFA, IL1A, IL1B, and IL6) and anti-inflammatory cytokines (IL-1RN and TGFB1). An additional goal was to observe whether these cytokine gene polymorphisms influence the development risk and severity of.

METHODS

Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

RESULTS

TNFA (-238) gene polymorphism principally affected CWP development and severity (OR = 3.47: 95% CI, 1.12-10.77 and OR = 4.30: 95% CI, 1.25-14.74, respectively) and also risk of CWP (OR = 3.79: 95% CI, 1.37-10.46). The TNFA (-308) variant was associated with a risk for the CWP severity (OR = 2.84: 95% CI, 1.08-7.39). A protective effect of IL6 was found on the development (OR = 0.48: 95% CI, 0.21-0.93) and severity of CWP (OR = 0.37: 95% CI, 0.15-0.91).

CONCLUSIONS

We suggest that TNFA (-238) variant may be a risk factor in both development and the severity of CWP, while TNFA (-308) variant seems to be important only in disease severity. On the other hand, IL6 variant may have a protective effect on the development and disease severity.

The role of inflammation in the pathogenesis of idiopathic pulmonary fibrosis

The role of inflammation in idiopathic pulmonary fibrosis (IPF) is controversial. If inflammation were critical to the disease process, lung pathology would demonstrate an influx of inflammatory cells, and that the disease would respond to immunosuppression. Neither is true. The classic pathology does not display substantial inflammation, and no modulation of the immune system is effective as treatment. Recent data suggest that the pathophysiology of the disease is more a product of fibroblast dysfunction than of dysregulated inflammation. The role of inflammation in disease pathogenesis comes from pathology from atypical patients, biologic samples procured during exacerbations of the disease, and careful examination of biologic specimens from patients with stable disease. We suggest that inflammation is indeed a critical factor in IPF and propose five potential nontraditional mechanisms for the role of inflammation in the pathogenesis of IPF: the direct inflammatory hypothesis, the matrix hypothesis, the growth factor-receptor hypothesis, the plasticity hypothesis, and the vascular hypothesis. To address these, we review the literature exploring the differences in pathology, prognosis, and clinical course, as well as the role of cytokines, growth factors, and other mediators of inflammation, and last, the role of matrix and vascular supply in patients with IPF.

Accelerated variant of idiopathic pulmonary fibrosis: clinical behavior and gene expression pattern

Background

Idiopathic pulmonary fibrosis (IPF) is characterized by the insidious onset of dyspnea or cough. However, a subset of patients has a short duration of symptoms with rapid progression to end-stage disease. In this study, we evaluated clinical and molecular features of “rapid” and “slow” progressors with IPF.

Methods and Findings

26 patients with <6 months of symptoms before first presentation [rapid progressors] and 88 patients with >24 months of symptoms [slow progressors] were studied. Survival was analyzed by the Kaplan-Meyer method and proportional hazard's model. Lung microarrays and tissue proteins were measured in a subset of patients. No differences were found in age, physiologic impairment and bronchoalveolar lavage (BAL) cellular profile. There were more males (OR = 6.5; CI:1.4-29.5; p = 0.006) and smokers (OR = 3.04; CI:1.1-8.3; p = 0.04) in the rapid progressors group. Survival from the beginning of symptoms was significantly reduced in rapid progressors (HR = 9.0; CI:4.48-18.3; p<0.0001) and there was a tendency for decreased survival from the time of diagnosis (HR = 1.5; CI:0.81-2.87; p = 0.18). We identified 437 differentially expressed genes. Lungs of rapid progressors overexpressed genes involved in morphogenesis, oxidative stress, migration/proliferation, and genes from fibroblasts/smooth muscle cells. Upregulation of two of these genes, adenosine-2B receptor and prominin-1/CD133, was validated by immunohistochemistry and were expressed by alveolar epithelial cells. BAL from rapid progressors showed a >2-fold increase of active matrix metalloproteinase-9, and induced a higher fibroblast migration compared with slow progressors and controls [238±98% versus 123±29% (p<0.05) and 30±17% (p<0.01)].

Conclusions/Significance

A subgroup of IPF patients, predominantly smoking males, display an accelerated clinical course and have a gene expression pattern that is different from those with slower progression and longer survival. These findings highlight the variability in the progression of IPF, and may explain, in part, the difficulty in obtaining significant and reproducible results in studies of therapeutic interventions in patients with IPF.

Antithetical effect of tumor necrosis factor-alphagene polymorphism on coal workers' pneumoconiosis (CWP)

BACKGROUND

Inter-individual variation in the severity of pneumoconiosis has been described, even with the same environmental exposure. We hypothesized that TNF-alpha promoter polymorphisms associate with lung responses to environmental exposure in coal worker's pneumoconiosis (CWP) patients.

METHODS

We examined polymorphisms at -238, -308, and -376 in 124 patients with CWP who had similar dust exposure history and in 122 non-exposed controls. CWP patients were divided into two groups: (1) nodular CWP (n = 84); (2) progressive massive fibrosis (PMF) (n = 44).

RESULTS

The -308 A allele frequency was higher in patients with CWP compared to controls (6.35% and 2.05%, P < 0.01). It was also higher in patients with nodular CWP compared to PMF (P < 0.05). Logistic regression analysis revealed that patients with the -308 A allele were 3.8 times (P = 0.036) and those with smoking habit were 2.3 times (P < 0.002) more likely to have nodular CWP than PMF.

CONCLUSION

TNF-alpha-308 A allele might interact with smoking to enhance susceptibility to nodular CWP.