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Increased senescence and expression of profibrotic genes in old lung fibroblasts contribute to disrepair responses. We reported that primary lung fibroblasts from old mice have lower expression and activity of the cystine transporter Slc7a11/xCT than cells from young mice, resulting in changes in both the intracellular and extracellular redox environments. This study examines the hypothesis that low Slc7a11 expression in old lung fibroblasts promotes senescence and profibrotic gene expression. The levels of mRNA and protein of Slc7a11, senescence markers, and profibrotic genes were measured in primary fibroblasts from the lungs of old (24 mo) and young (3 mo) mice. In addition, the effects of genetic and pharmacological manipulation of Slc7a11 were investigated. We found that decreased expression of Slc7a11 in old cells was associated with elevated markers of senescence (p21, p16, p53, and β-galactosidase) and increased expression of profibrotic genes (Tgfb1, Smad3, Acta2, Fn1, Col1a1, and Col5a1). Silencing of Slc7a11 in young cells replicated the aging phenotype, whereas overexpression of Slc7a11 in old cells decreased expression of senescence and profibrotic genes. Young cells were induced to express the senescence and profibrotic phenotype by sulfasalazine, a Slc7a11 inhibitor, whereas treatment of old cells with sulforaphane, a Slc7a11 inducer, decreased senescence without affecting profibrotic genes. Like aging cells, idiopathic pulmonary fibrosis fibroblasts show decreased Slc7a11 expression and increased profibrotic markers. In short, old lung fibroblasts manifest a profibrotic and senescence phenotype that is modulated by genetic or pharmacological manipulation of Slc7a11.

Lung cancer remains the leading cause of cancer death in the United States. Since most lung cancers occur in aged individuals with chronic lung disorders characterized by inflammation and/or fibrosis, we hypothesized that aging and tissue inflammation/remodeling act in concert to promote lung cancer progression. To test this, we engaged in studies using young and aged C57BL/6 mice in conjunction with bleomycin treatment in a syngeneic model of lung cancer. Wildtype young (3 months) and aged (9 months) C57BL/6 mice were injected with Lewis Lung Carcinoma (LLC) cells at day 14 after injection with phosphate-buffered saline or bleomycin. Untreated aged mice were found to develop more lung metastases than young mice. Bleomycin induced weight loss and lung inflammation/remodeling in both young and aged mice, and it increased the number of lung metastases in aged lungs, but not in young lungs. Since aged lungs show alterations in the expression of fibronectin EDA, we repeated studies in aged WT and aged FN EDA KO mice. In the absence of tissue remodeling/inflammation, WT and FN EDA KO mice developed the same number of metastases when injected with LLC cells. However, the increase in lung metastasis due to bleomycin treatment was abolished in FN EDA KO mice, but only in aged and injured lungs. Together, these studies show increased lung cancer metastasis in aging animals and point to the influence of FN EDA and injury in this process.

Background Gastroesophageal reflux (GER) in recipients of lung transplant (LTX) is associated with chronic allograft rejection, presumably via microaspiration that damages airway epithelium. Most LTX programs perform a single post-LTX esophageal study to evaluate for GER; the efficacy of this test is unclear. Methods Patients with 1 year of post-LTX follow-up, including routine bronchoscopies with bronchoalveolar lavage fluid (BALF) samples as well as high-resolution esophageal manometry and pH probe monitoring (HREMpH), were evaluated. BALF samples were analyzed with competitive enzyme-linked immunosorbent assay to detect bile salts, which are indicative of aspiration. These results were compared to results of HREMpH studies post LTX. Results Ninety BALF samples were analyzed for bile salts and acted as disease positive for this evaluation. Of the 13 HREMpH cases, 8 were positive for GER, but only 3 were positive for bile salts via assay. Of the 5 HREMpH-negative cases, 2 experienced aspiration. A solitary HREMpH study had 60.0% sensitivity and 37.5% specificity with positive and negative likelihood ratios: 0.96 and 1.07, respectively. Conclusion Microaspiration appears to be an intermittent phenomenon, and HREMpH screening poorly correlates with BALF evidence of aspiration; which may not be adequate. As aspiration detection is crucial in this population, further analysis is warranted.

Introduction Alcohol use disorders are major risk factors for the development of and susceptibility to acute respiratory distress syndrome. Although these risks of alcohol consumption on the lung are well described, mechanisms by which alcohol abuse promotes acute lung injury are poorly understood. These gaps in our understanding are due, at least in part, to limitations of animal models to recapitulate human alcohol consumption. Recently, a new model of chronic plus binge alcohol exposure was developed that is hypothesized to better model drinking patterns of individuals with alcohol use disorders. Specifically, this paradigm models chronic consumption coupled with periodic bouts of heavy drinking. The impacts of this alcohol-exposure regimen on the lung are uncharacterized. Therefore, the goal of this study was to examine lung injury and inflammation in a well-characterized experimental model of chronic + binge alcohol exposure. Methods 10-week-old male C57Bl6/J mice were administered ethanol-containing (or isocaloric control) liquid diet for 10 days, followed by a single ethanol gavage (5 g/kg). Lung inflammation and pulmonary function were assessed. Results Ten days of ethanol-containing liquid diet alone (chronic) did not detectably affect any variables measured. However, ethanol diet plus gavage (chronic + binge) caused neutrophils to accumulate in the lung tissue and in the bronchoalveolar lavage fluid 24 h post-binge. This inflammatory cell recruitment was associated with airway hyper-responsiveness to inhaled methacholine, as indicated by elevated resistance, Newtonian resistance, and respiratory resistance. Conclusions Taken together, the novel findings reveal that ethanol alone, absent of any secondary inflammatory insult, is sufficient to produce inflammation in the lung. Although these changes were relatively mild, they were associated with functional changes in the central airways. This animal model may be useful in the future for identifying mechanisms by which alcohol abuse sensitizes at-risk individuals to lung injury.

Chronic obstructive pulmonary disease (COPD) is prevalent in patients infected with HIV. The purpose of this study was to test the hypothesis that systemic oxidation correlates with loss of lung function in subjects with COPD, and that HIV infection can contribute to creating such an environment. Subjects were recruited at the University of Louisville in the following groups: HIV-infected (n = 36), COPD (n = 32), HIV and COPD (n = 28), and uninfected controls with normal lung function (n = 34). HIV infection was assessed by viral load and CD4 cell counts. Pulmonary function was determined by spirometry, and plasma was collected for measurement of cysteine (Cys), cystine (CySS), glutathione (GSH) and GSH disulfide (GSSG) by HPLC followed by estimation of redox potentials (Eh) using the Nernst equation. Results showed that patients with COPD had more oxidized plasma Eh Cys/CySS than patients with normal lung function, but plasma Eh GSH/GSSG was unaltered. In addition, there was a correlation between the extent of plasma Eh Cys/CySS oxidation and loss of lung function, and this correlation remained even after correcting for age, sex, race and body mass index. HIV infection per se was not associated with increased oxidation of plasma Eh Cys/CySS, but plasma Eh Cys/CySS was more oxidized in patients with lower CD4-positve T cell counts. In patients with both HIV infection and COPD, there was a significant correlation between CD4 cell counts and lung function. Thus, systemic oxidation correlated with decreased lung function in subjects with COPD and decreased CD4 counts in subjects infected with HIV. Thus, factors contributing to plasma Eh Cys/CySS may represent novel mechanisms underlying the increased prevalence of COPD in people living with HIV.

Lung transplantation remains a therapeutic option in end-stage lung disease. However, despite advances in the field, early allograft function can be compromised by the development of primary graft dysfunction (PGD); this being the leading cause of morbidity and mortality immediately following the lung transplant procedure. Several recipient factors have been associated with increased risk of PGD, but less is known about donor factors. Aging, tobacco, and chronic alcohol use are donor factors implicated, but how these factors promote PGD remains unclear. Herein, we discuss the available clinical data that link these donor factors with outcomes after lung transplantation, and how they might render the recipient susceptible to PGD through a two-hit process. This article is protected by copyright. All rights reserved.

Recent studies point to the important role of in utero malnutrition in gene programming and in the development of vascular diseases. We hypothesize that maternal undernutrition affects vascular function in the offspring by promoting epigenetic changes that drive the differential expression of genes involved in endothelial function. To test this, we exposed mice to nutrient deprivation in utero and analyzed its effect on global DNA methylation and expression of endothelium-specific genes in the pulmonary endothelium of the adult progeny. Mice were kept either on ad libitum (AL) or energy-restricted (ER) diet during the second and third trimesters of gestation. Mice in the ER group received 65% of energy compared to mice in the AL diet group. Pulmonary endothelial cells were isolated from 6-week-old male offspring mice (AL-F1 and ER-F1). The expression of genes in the pulmonary endothelium was analyzed using quantitative reverse-transcription polymerase chain reaction array and confirmed by qRT-PCR. Several genes including fibronectin 1 and plasminogen activator inhibitor 1 were upregulated in the endothelium of male ER-F1 mice, whereas the expression of genes involved in regulation of histone acetylation was significantly attenuated. At the same time, the global DNA methylation did not change in pulmonary endothelial cells of ER-F1 mice compared to AL-F1 mice. Overall, we found that maternal undernutrition during pregnancy affects the expression of genes involved in regulation of endothelial cell function in the pulmonary vasculature of male progeny, which could potentially promote pulmonary vascular remodeling.

Coronaviruses are a well-known cause of upper and lower respiratory disease, and since 2002 have been a recognized source of potential pandemic spread. Over the past two decades, since the Severe Acute Respiratory Syndrome (SARS) outbreak, a large body of research has accumulated on the virology, clinical symptoms and signs, and experimental treatments of Coronaviruses. In 2020, a new form of Coronaviruses (SARS-CoV-2) emerged and spread rapidly throughout the globe. Given the wide-ranging clinical presentations of those infected with SARS-CoV-2, other viruses might be overlooked when evaluating at-risk patients. Furthermore, due to suboptimal testing capabilities, an early clinical diagnosis is not always possible. Here, we present a case of a patient with pneumonia thought to be caused by SARS-CoV-2 only to be found to have another Coronavirus. This emphasizes the need to be vigilant when evaluating patients with viral-like respiratory infections.

Slc7a11 is the key component of system Xc-, an antiporter that imports cystine (CySS) and exports glutamate. It plays an important role in cellular defense against oxidative stress because cysteine (Cys), reduced from CySS, is used for and limits the synthesis of glutathione (GSH). We have shown that downregulation of Slc7a11 is responsible for oxidation of extracellular Cys/CySS redox potential in lung fibroblasts from old mice. However, how age-related change of Slc7a11 expression affects the intracellular redox environment of mouse lung fibroblasts remains unexplored. The purpose of this study is to evaluate the effects of aging on the redox states of intracellular proteins and to examine whether Slc7a11 contributes to the age-dependent effects. Iodoacetyl Tandem Mass Tags were used to differentially label reduced and oxidized forms of Cys residues in primary lung fibroblasts from young and old mice, as well as old fibroblasts transfected with Slc7a11. The ratio of oxidized/reduced forms (i.e., redox state) of a Cys residue was determined via multiplexed tandem mass spectrometry. Redox states of 151 proteins were different in old fibroblasts compared to young fibroblasts. Slc7a11 overexpression restored redox states of 104 (69%) of these proteins. Ingenuity Pathway Analysis (IPA) showed that age-dependent Slc7a11-responsive proteins were involved in pathways of protein translation initiation, ubiquitin-proteasome-mediated degradation, and integrin-cytoskeleton-associated signaling. Gene ontology analysis showed cell adhesion, protein translation, and organization of actin cytoskeleton were among the top enriched terms for biological process. Protein-protein interaction network demonstrated the interactions between components of the three enriched pathways predicted by IPA. Follow-up experiments confirmed that proteasome activity was lower in old cells than in young cells and that upregulation of Slc7a11 expression by sulforaphane restored this activity. This study finds that aging results in changes of redox states of proteins involved in protein turnover and cytoskeleton dynamics, and that upregulating Slc7a11 can partially restore the redox states of these proteins.

Interstitial lung diseases comprise a family of progressive pulmonary disorders that are often idiopathic or associated with various systemic diseases and that is characterized by bilateral lung involvement with inflammation and tissue remodeling or fibrosis. The impact of sex, including the anatomic and physiologic traits that one is born with, on the development and progression of interstitial lung diseases is not entirely clear. Variances between men and women are driven by differences in male and female biology and sex hormones, among other differences, but their role remains uncertain. In this review, we summarize sex-related differences in the epidemiology and progression of certain interstitial lung diseases with a focus on the connective tissue related interstitial lung diseases, idiopathic pulmonary fibrosis, and sarcoidosis. We also discuss cellular and pre-clinical studies that might shed light on the potential mechanisms responsible for these differences in the hope of unveiling potential targets for intervention and stimulating research in this needed field of investigation.

Aging is associated with progressive oxidation of the extracellular environment. The redox state of human plasma, defined by the concentrations of cysteine (Cys) and cystine (CySS), becomes more oxidized as we age. Recently, we showed that fibroblasts isolated from the lungs of young and old mice retain this differential phenotype; old cells produce and maintain a more oxidizing extracellular redox potential (E(h)(Cys/CySS)) than young cells. Microarray analysis identified down-regulation of Slc7a11, the light subunit of the CySS/glutamate transporter, as a potential mediator of age-related oxidation in these cells. The purpose of the present study was to investigate the mechanistic link between Slc7a11 expression and extracellular E(h)(Cys/CySS). Sulforaphane treatment or overexpression of Slc7a11 was used to increase Slc7a11 in lung fibroblasts from old mice, and sulfasalazine treatment or siRNA-mediated knock down was used to decrease Slc7a11 in young fibroblasts. Slc7a11 mRNA levels were measured by real-time PCR, Slc7a11 activity was determined by measuring the rate of glutamate release, Cys, CySS, glutathione (GSH) and its disulfide (GSSG) were measured by HPLC, and E(h)(Cys/CySS) was calculated from the Nernst equation. The results showed that both E(h)(Cys/CySS) and E(h)(GSH/GSSG) were more oxidized in the conditioned media of old cells than in young cells. Up-regulation of Slc7a11 via overexpression or sulforaphane treatment restored extracellular E(h)(Cys/CySS) in cultures of old cells, whereas down-regulation reproduced the oxidizing E(h)(Cys/CySS) in young cells. Only sulforaphane treatment was able to increase total GSH and restore E(h)(GSH/GSSG), whereas overexpression, knock down and sulfasalazine had no effect on these parameters. In addition, inhibition of GSH synthesis with buthionine sulfoximine had no effect on the ability of cells to restore their extracellular redox potential in response to an oxidative challenge. In conclusion, our study reveals Slc7a11 is the key regulator of age-dependent changes in extracellular E(h)(Cys/CySS) in primary mouse lung fibroblasts, and its effects are not dependent on GSH synthesis.

Chronic alcohol exposure is a clinically important risk factor for the development of acute respiratory distress syndrome, the most severe form of acute lung injury (ALI). However, the mechanisms by which alcohol sensitizes the lung to development of this disease are poorly understood. We determined the role of the antifibrinolytic protein plasminogen activator inhibitor-1 (PAI-1) in alcohol enhancement of experimental endotoxin-induced ALI. Wild-type, PAI-1−/−, and integrin β3−/− mice were fed ethanol-containing Lieber-DeCarli liquid or a control diet for 6 weeks, followed by systemic LPS challenge. LPS administration triggered coagulation cascade activation as evidenced by increased plasma thrombin-antithrombin levels and pulmonary fibrin deposition. Ethanol-exposed animals showed enhanced PAI-1 expression and pulmonary fibrin deposition with coincident exaggeration of pulmonary inflammatory edematous injury. PAI-1 deficiency markedly reduced pulmonary fibrin deposition and greatly reduced inflammation and injury without impacting upstream coagulation. Interestingly, pulmonary platelet accumulation was effectively abolished by PAI-1 deficiency in ethanol/LPS-challenged mice. Moreover, mice lacking integrin αIIBβ3, the primary platelet receptor for fibrinogen, displayed a dramatic reduction in early inflammatory changes after ethanol/LPS challenge. These results indicate that the mechanism whereby alcohol exaggerates LPS-induced lung injury requires PAI-1–mediated pulmonary fibrin accumulation, and suggest a novel mechanism whereby alcohol contributes to inflammatory ALI by enhancing fibrinogen-platelet engagement.

Background Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by oculocutaneous albinism and platelet dysfunction and can sometimes lead to a highly aggressive form of pulmonary fibrosis that mimics the fatal lung condition called idiopathic pulmonary fibrosis (IPF). Although the activities of various matrix metalloproteinases (MMPs) are known to be dysregulated in IPF, it remains to be determined whether similar changes in these enzymes can be detected in HPS. Results Here, we show that transcript and protein levels as well as enzymatic activities of MMP-2 and -9 are markedly increased in the lungs of mice carrying the HPS Ap3b1 gene mutation. Moreover, immunohistochemical staining localized this increase in MMP expression to the distal pulmonary epithelium, and shRNA knockdown of the Ap3b1 gene in cultured lung epithelial cells resulted in a similar upregulation in MMP-2 and -9 expression. Mechanistically, we found that upregulation in MMP expression associated with increased activity of the serine/threonine kinase Akt, and pharmacological inhibition of this enzyme resulted in a dramatic suppression of MMP expression in Ap3b1 deficient lung epithelial cells. Similarly, levels and activity of different MMPs were also found to be increased in the lungs of mice carrying the Bloc3 HPS gene mutation and in the bronchoalveolar lavage fluid of subjects with HPS. However, an association between MMP activity and disease severity was not detected in these individuals. Conclusions In summary, our findings indicate that MMP activity is dysregulated in the HPS lung, suggesting a role for these proteases as biological markers or pathogenic players in HPS lung disease. Electronic supplementary material The online version of this article (10.1186/s13023-019-1143-0) contains supplementary material, which is available to authorized users.

Background HIV-positive patients on anti-retroviral therapy (ART) are at higher risk of developing many non-AIDS related chronic diseases, including chronic obstructive pulmonary disease (COPD), compared to HIV-negative individuals. While the mechanisms are not clear, a persistent pro-inflammatory state appears to be a key contributing factor. The aims of this study were to investigate whether HIV-positive patients without COPD present evidence of potentially predisposing abnormal pulmonary cytokine/chemokine environment and to explore the relationship between pulmonary and systemic cytokine levels. Methods This study included 39 HIV-seropositive and 34 HIV-seronegative subjects without COPD. All were subjected to outpatient bronchoscopy with bronchoalveolar lavage fluid (BALF) aspiration and blood sample collection. The levels of 21 cytokines and chemokines were measured in plasma and BALF using a bead-based multi-analyte assay. Results In plasma, HIV-infected patients showed significantly increased circulating levels of pro-inflammatory (TNFα) and Th1-associated cytokines (IL-12p70) as well as several chemokines (CXCL11 and CX3CL1). However, no statistically significant differences were found in the numbers of cells, the concentrations of protein and urea as well as cytokine levels in the BALFs of HIV-positive patients when compared to controls. Correlation analysis indicated a potential modulatory effect of the BMI in HIV-seropositive individuals. Conclusions While our results are consistent with the existence of a systemic pro-inflammatory state in HIV-infected patients, they did not detect significant differences in cytokine levels and other inflammatory markers in the lungs of HIV-positive individuals when compared to HIV-negative controls.

Background Work-place exposure to silica dust may lead to progressive lung inflammation culminating in the development of silicosis, an irreversible condition that can be complicated by onset of pulmonary hypertension (PH). The molecular mechanisms leading to the development of PH and lung fibrosis in response to silica are not well understood. Oxidant/antioxidant imbalance in the lung may promote fibroproliferation and vascular smooth muscle proliferation, ultimately leading to the development of PH. Herein, we analyze the development of PH and lung fibrosis in mice deficient in extracellular superoxide dismutase (SOD3), an enzyme with anti-oxidant activity. Methods PH and silicosis were induced in wild-type and Sod3−/− mice through intratracheal injection of crystalline silica at dose 0.4 g/kg. Pulmonary hypertension and lung fibrosis were characterized by changes in right ventricular systolic pressure (RVSP) and collagen deposition 28 days following silica injections. Vascular remodeling was analyzed using immunohistochemistry and morphometric analysis. The expression of genes were analyzed using qRT-PCR and Western blot. Results C57BL6 mice exposed to silica showed attenuated expression of Sod3 in the lung suggesting a protective role for Sod3. Consistent with this, Sod3−/− mice developed more severe fibrotic inflammatory nodules with increased collagen deposition. Furthermore, the expression of genes involved in tissue remodeling (Timp1), fibrotic lesion formation (Fsp1) and inflammatory response (Mcp1) were significantly elevated in Sod3−/− mice compared to Sod3+/+ mice treated with silica. Infiltration of neutrophils and activated macrophages into affected lung was significantly higher in Sod3 deficient mice. In addition, silica produced more profound effects on elevation of RVSP in Sod3−/− compared to wild-type littermate. Increase in RVSP was concomitant with hypertrophy of pulmonary arteries located in silicotic nodules of both mouse strains, however, vascular remodeling in unaffected areas of lung was detected only in Sod3−/− mice. Conclusions Our data suggest that Sod3 and extracellular oxidative stress may play an important role in the development of pneumoconiosis and pulmonary vascular remodeling following exposure to environmental and occupational silica.

Pulmonary fibrosis affects millions worldwide and, even though there has been a significant investment in understanding the processes involved in wound healing and maladaptive repair, a complete understanding of the mechanisms responsible for lung fibrogenesis eludes us, and interventions capable of reversing or halting disease progression are not available. Pulmonary fibrosis is characterized by the excessive expression and uncontrolled deposition of extracellular matrix (ECM) proteins resulting in erosion of the tissue structure. Initially considered an ‘end-stage’ process elicited after injury, these events are now considered pathogenic and are believed to contribute to the course of the disease. By interacting with integrins capable of signal transduction and by influencing tissue mechanics, ECM proteins modulate processes ranging from cell adhesion and migration to differentiation and growth factor expression. In doing so, ECM proteins help orchestrate complex developmental processes and maintain tissue homeostasis. However, poorly controlled deposition of ECM proteins promotes inflammation, fibroproliferation, and aberrant differentiation of cells, and has been implicated in the pathogenesis of pulmonary fibrosis, atherosclerosis and cancer. Considering their vital functions, ECM proteins are the target of investigation, and oxidation–reduction (redox) reactions have emerged as important regulators of the ECM. Oxidative stress invariably accompanies lung disease and promotes ECM expression directly or through the overproduction of pro-fibrotic growth factors, while affecting integrin binding and activation. In vitro and in vivo investigations point to redox reactions as targets for intervention in pulmonary fibrosis and related disorders, but studies in humans have been disappointing probably due to the narrow impact of the interventions tested, and our poor understanding of the factors that regulate these complex reactions. This review is not meant to provide a comprehensive review of this field, but rather to highlight what has been learned and to raise interest in this area in need of much attention., Graphical abstract fx1

Respiratory disorders like asthma, emphysema, and pulmonary fibrosis affect millions of Americans and many more worldwide. Despite advancements in medical research that have led to improved understanding of the pathophysiology of these conditions and sometimes to new therapeutic interventions, these disorders are for the most part chronic and progressive; current interventions are not curative and do not halt disease progression. A major obstacle to further advancements relates to the absence of animal models that exactly resemble the human condition, which delays the elucidation of relevant mechanisms of action, the unveiling of biomarkers of disease progression, and identification of new targets for intervention in patients. There are currently many induced animal models of human respiratory disease available for study, and even though they mimic features of human disease, discoveries in these models have not always translated into safe and effective treatments in humans. A major obstacle relates to the genetic, anatomical, and functional variations amongst species, which represents the major challenge to overcome when searching for appropriate models of respiratory disease. Nevertheless, rodents, in particular mice, have become the most common species used for experimentation, due to their relatively low cost, size, and adequate understanding of murine genetics, among other advantages. Less well known is the fact that domestic animals also suffer from respiratory illnesses similar to those found in humans. Asthma, bronchitis, pneumonia, and pulmonary fibrosis are among the many disorders occurring naturally in dogs, cats, and horses, among other species. These models might better resemble the human condition and are emphasized here, but further investigations are needed to determine their relevance.

Acute exacerbation of interstitial lung disease (ILD) is associated with a poor prognosis and high mortality. Numerous studies have documented acute exacerbation in idiopathic pulmonary fibrosis (IPF), but less is known about these events in other ILDs that may present a progressive-fibrosing phenotype. We propose defining acute exacerbation as an acute, clinically significant respiratory deterioration, typically less than 1 month in duration, together with computerised tomography imaging showing new bilateral glass opacity and/or consolidation superimposed on a background pattern consistent with fibrosing ILDs. Drawing on observations in IPF, it is suspected that epithelial injury or proliferation and autoimmunity are risk factors for acute exacerbation in ILDs that may present a progressive-fibrosing phenotype, but further studies are required. Current acute exacerbation management strategies are based on recommendations in IPF, but no randomised controlled trials of acute exacerbation management have been performed. Although there are no formal strategies to prevent the development of acute exacerbation, possible approaches include antifibrotic drugs (such as nintedanib and pirfenidone), and minimising exposure to infection, airborne irritants and pollutants. This review discusses the current knowledge of acute exacerbation of ILDs that may present a progressive-fibrosing phenotype and acknowledges limitations of the data available., SCOPUS: re.j, info:eu-repo/semantics/published

Background Tobacco-related chronic lung diseases are characterized by alterations in lung architecture leading to decreased lung function. Knowledge of the exact mechanisms involved in tobacco-induced tissue remodeling and inflammation remains incomplete. We hypothesize that nicotine stimulates the expression of extracellular matrix proteins, leading to relative changes in lung matrix composition, which may affect immune cells entering the lung after injury. Methods Pulmonary fibroblasts from wildtype and α7 nicotinic acetylcholine receptor knockout (α7KO) mice were exposed to nicotine and examined for collagen type 1 mRNA and protein expression. Testing the potential role on immune cell function, pulmonary fibroblasts were retained in culture for 120 h. The fibroblasts were eliminated by osmotic lysis and the remaining matrix-coated dishes were washed thoroughly. U937 cells were incubated on the matrix-coated dishes for 24 h followed by evaluation of IL-1β gene expression. Wildtype or α7KO C57BL/6 mice (female, 8–12 weeks) were fed normal diet and exposed to nicotine in their drinking water (100 μg/ml) for 8-12weeks. Lungs were processed for mRNA, protein, and histology. Statistical significance was determined at p ≤ .05 by two-tailed test or 2-way ANOVA with Bonferroni posttest. Results We found that nicotine stimulated collagen type I mRNA and protein expression in a dose-dependent manner and up to 72 h in primary lung fibroblasts. The stimulatory effect of nicotine was inhibited in α7KO primary lung fibroblasts. Testing the potential role of these events on immune cell function, U937 monocytic cells were cultured atop matrices derived from nicotine-treated lung fibroblasts. These cells expressed more IL-1β than those cultured atop matrices derived from untreated fibroblasts, and antibodies against the α2β1 collagen integrin receptor inhibited the effect. Nicotine also stimulated fibroblast proliferation via MEK-1/ERK, unveiling a potentially amplifying pathway. In vivo, nicotine increased collagen type I expression was detected in wildtype, but not in α7KO mice. Wildtype mice showed increased collagen staining in lung, primarily around the airways. Conclusions These observations suggest that nicotine stimulates fibroblast proliferation and their expression of collagen type I through α7 nAChRs, thereby altering the relative composition of the lung matrix without impacting the overall lung architecture; this may influence inflammatory responses after injury.

Lung disorders characterized by fibroproliferation and excessive deposition of extracellular matrices occur in late adulthood, and their pathological manifestations become more prominent with aging. The exact mechanisms linking aging and fibroproliferative disorders are unknown, but increased oxidative stress resulting in the accumulation of damaged proteins, DNA, and lipids is considered a major factor. In the lung, and especially in the pulmonary fibroblasts, the extracellular superoxide dismutase (EC-SOD) is a major antioxidant enzyme that has been implicated in pulmonary fibrosing disorders, among others. Here, we investigate the regulation of EC-SOD in pulmonary lung fibroblasts derived from young (up to 3 month) and old (24 month) C57BL6 mice. We found that old fibroblasts have marginally elevated levels of reactive oxidant species (ROS), which coincides with attenuated expression a number of antioxidant enzymes including EC-SOD. Exposure of old fibroblasts to the DNA methyltransferase inhibitor 5-aza-dC did not restore expression of EC-SOD. On the other hand, repression of EC-SOD expression was associated with deacetylation of lysine 9 on histone H3 and lysines 5, 8, 12 and 16 on histone H4 located at the gene promoter. Interestingly, the repressive tri-methylation of lysine 27 on histone H3 was elevated in old compared to young fibroblasts. In addition, exposure of old lung fibroblasts to HDAC class 1 and class 2 inhibitors restored EC-SOD expression to the level observed in young fibroblasts. While the exact mechanism of age-dependent downregulation of EC-SOD is yet to be defined, our studies indicate a potential role of epigenetic mechanisms including histone deacetylation in this process.

Lung fibrosis can be observed in systemic sclerosis and in idiopathic pulmonary fibrosis, two disorders where lung involvement carries a poor prognosis. Although much has been learned about the pathogenesis of these conditions, interventions capable of reversing or, at the very least, halting disease progression are not available. Recent studies point to the potential role of micro messenger RNAs (microRNAs) in cancer and tissue fibrogenesis. MicroRNAs are short non-coding RNA sequences (20–23 nucleotides) that are endogenous, evolutionarily conserved and encoded in the genome. By acting on several genes, microRNAs control protein expression. Considering the above, we engaged in a systematic review of the literature in search of overlapping observations implicating microRNAs in the pathogenesis of both idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc). Our objective was to uncover top microRNA candidates for further investigation based on their mechanisms of action and their potential for serving as targets for intervention against lung fibrosis. Our review points to microRNAs of the -29 family, -21-5p and -92a-3p, -26a-5p and let-7d-5p as having distinct and counter-balancing actions related to lung fibrosis. Based on this, we speculate that readjusting the disrupted balance between these microRNAs in lung fibrosis related to SSc and IPF may have therapeutic potential.

A hallmark of idiopathic pulmonary fibrosis (IPF) is excessive and disordered deposition of extracellular matrix. Although the lung extracellular matrix normally plays an essential role in development and maintenance of lung tissue through reciprocal interactions with resident cells, the disordered matrix in the diseased lung is increasingly recognized as an active and important contributor to IPF pathogenesis. This working group summary from a recently conducted National Heart, Lung, and Blood Institute strategic planning workshop for IPF research highlights recent advances, challenges, and opportunities in the study of matrix biology in IPF. Particular attention is given to the composition and mechanical properties of the matrix in normal and diseased lungs, and the biochemical and biomechanical influences exerted by pathological matrix. Recently developed model systems are also summarized as key tools for advancing our understanding of matrix biology in IPF. Emerging approaches to therapeutically target the matrix in preclinical and clinical settings are discussed, as are important concepts, such as alterations of the matrix with aging and the potential for the resolution of fibrosis. Specific recommendations for future studies in matrix biology of IPF are also proposed.

Background Although liver is the organ most often associated with the damaging effects of chronic alcohol abuse, other organs may also be affected. In the past decade, data emerged linking chronic alcohol intake to lung dysfunction. However, the mechanisms by which alcohol affects the lung remain incompletely elucidated. Methods In this issue, Sueblinvong and colleagues explore the effect of chronic alcohol intake in the well-known rodent model of bleomycin-induced lung injury. This represents a review of their article and a commentary on its findings in relation to current knowledge in the field. Results The investigators found that chronic alcohol intake increased lung fibrosis in the bleomycin-model of lung injury. This effect was related to increased production of transforming growth factor β (TGFβ) and expression of α-smooth muscle actin. Diet supplementation with S-adenosylmethionine greatly reduced the effect. These data strengthen published reports linking chronic alcohol intake with TGFβ overproduction and lung disrepair after injury, while implicating oxidant stress as a critical mediator of these effects. Conclusions A review of Sueblinvong and colleagues' article and the literature strongly suggests that the lung is a target for alcohol, and that chronic alcohol intake may predispose the lung to disrepair after injury. The overexpression of pro-fibrotic growth factors and pro-inflammatory cytokines, and the generation of oxidant stress may lead to lung cellular dysfunction, aberrant tissue remodeling, and loss of lung function. These events may represent targets for intervention, but translational studies evaluating their role in humans are desperately needed.

Background: Gastroesophageal reflux disease has been associated with allograft dysfunction in lung transplant (LTX) recipients. While the mechanisms are unclear it is postulated that microaspiration of gastrointestinal material (GIM) leads to inflammation and airway remodeling that culminates in obliterative bronchiolitis. Expression of the glycoprotein fibronectin has been shown to be an early marker of lung fibroproliferative disease, thus, its induction could suggest a causal mechanism for allograft dysfunction in LTX recipients experiencing microaspiration. Methods: De-identified bronchoalveolar lavage fluid (BALF) samples sequentially collected during surveillance bronchoscopies throughout the first post-transplant year were analysed. Microaspiration was defined by the detection of bile salts in the BALF via an ELISA assay. An in vitro bioassay then measured fibronectin expression as a marker of activation of airway remodeling via incorporation of murine NIH/3T3 fibroblasts transfected with the human fibronectin promoter connected to the luciferase reporter vector. Fibroblasts were cultured with BALF for 24 hours and the ability of the BALF to stimulate fibronectin induction was measured via luciferase activity units. Results: Sequential bronchoscopies on 15 LTX recipients yielded 101 BALF samples for analysis. Six recipients had at least one BALF ‘positive’ for bile salts indicating GIM aspiration while the remaining nine recipients had no ‘positive” analyses. Fibronectin induction in the recipients experiencing aspiration was significantly greater than in the samples from those recipients who did not aspirate (1.05 + 0.19 vs. 0.92 + 0.28 luciferase activity units/µg protein) [p< 0.02]. Furthermore, the amount of fibronectin induction correlated with the amount of bile salts recovered from the allografts (r2 =0.20, p=0.04) suggesting that the amount of aspirated material influenced the degree of fibronectin production in the lower airways. Conclusions: Fibronectin induction is increased in LTX recipients who experience microaspiration suggesting possible early airway remodeling that may lead to later allograft dysfunction.

Pulmonary disease remains a primary source of morbidity and mortality in persons living with HIV (PLWH), although the advent of potent combination antiretroviral therapy has resulted in a shift from predominantly infectious to noninfectious pulmonary complications. PLWH are at high risk for COPD, pulmonary hypertension, and lung cancer even in the era of combination antiretroviral therapy. The underlying mechanisms of this are incompletely understood, but recent research in both human and animal models suggests that oxidative stress, expression of matrix metalloproteinases, and genetic instability may result in lung damage, which predisposes PLWH to these conditions. Some of the factors that drive these processes include tobacco and other substance use, direct HIV infection and expression of specific HIV proteins, inflammation, and shifts in the microbiome toward pathogenic and opportunistic organisms. Further studies are needed to understand the relative importance of these factors to the development of lung disease in PLWH.

Background Occupational and environmental exposure to crystalline silica may lead to the development of silicosis, which is characterized by inflammation and progressive fibrosis. A substantial number of patients diagnosed with silicosis develop pulmonary hypertension. Pulmonary hypertension associated with silicosis and with related restrictive lung diseases significantly reduces survival in affected subjects. An animal model of silicosis has been described previously however, the magnitude of vascular remodeling and hemodynamic effects of inhaled silica are largely unknown. Considering the importance of such information, this study investigated whether mice exposed to silica develop pulmonary hypertension and vascular remodeling. Methods C57BL6 mice were intratracheally injected with either saline or crystalline silica at doses 0.2 g/kg, 0.3 g/kg and 0.4 g/kg and then studied at day 28 post-exposure. Pulmonary hypertension was characterized by changes in right ventricular systolic pressure and lung histopathology. Results Mice exposed to saline showed normal lung histology and hemodynamic parameters while mice exposed to silica showed increased right ventricular systolic pressure and marked lung pathology characterized by a granulomatous inflammatory reaction and increased collagen deposition. Silica-exposed mice also showed signs of vascular remodeling with pulmonary artery muscularization, vascular occlusion, and medial thickening. The expression of pro-inflammatory genes such as TNF-α and MCP-1 was significantly upregulated as well as the expression of the pro-remodeling genes collagen type I, fibronectin and the metalloproteinases MMP-2 and TIMP-1. On the other hand, the expression of several vasculature specific genes involved in the regulation of endothelial function was significantly attenuated. Conclusions We characterized a new animal model of pulmonary hypertension secondary to pulmonary fibrosis induced by crystalline silica. Our data suggest that silica promotes the damage of the pulmonary vasculature through mechanisms that might involve endothelial dysfunction, inflammation, and vascular remodeling.

Aging is associated with progressive oxidation of plasma cysteine (Cys)/cystine (CySS) redox state, expressed asEhCySS. Cultured cells condition their media to reproduce physiologicalEhCySS, but it is unknown whether aged cells produce a more oxidized extracellular environment reflective of that seen in vivo. In the current study, we isolated primary lung fibroblasts from young and old female mice and measured the mediaEhCySSbefore and after challenge with Cys or CySS. We also measured expression of genes related to redox regulation and fibroblast function. These studies revealed that old fibroblasts produced a more oxidizing extracellularEhCySSthan young fibroblasts and that old fibroblasts had a decreased capacity to recover from an oxidative challenge due to a slower rate of reduction of CySS to Cys. These defects were associated with 10-fold lower expression of the Slc7a11 subunit of the xCT cystine-glutamate transporter. Extracellular superoxide dismutase (Sod3) was the only antioxidant or thiol-disulfide regulating enzyme among 36 examined that was downregulated in old fibroblasts by more than 2-fold, but there were numerous changes in extracellular matrix components. Thus, aging fibroblasts not only contribute to remodeling of the extracellular matrix but also have a profound effect on the extracellular redox environment.

The mechanisms that control fibroproliferation and matrix deposition in lung fibrosis remain unclear. We speculate that vitamin D deficiency may contribute to pulmonary fibrosis since vitamin D deficiency has been implicated in several diseases. First, we confirmed the presence of vitamin D receptors (VDRs) in cultured NIH/3T3 and lung fibroblasts. Fibroblasts transfected with a vitamin D response element-reporter construct and exposed to the active vitamin D metabolite, 1,25(OH)(2)D(3), showed increased promoter activity indicating VDR functionality in these cells. Testing the effects of 1,25(OH)(2)D(3) on fibroblasts treated with transforming growth factor beta1 (TGFbeta1), considered a driver of many fibrotic disorders, we found that 1,25(OH)(2)D(3) inhibited TGFbeta1-induced fibroblast proliferation in a dose-dependent fashion. 1,25(OH)(2)D(3) also inhibited TGFbeta1 stimulation of alpha-smooth muscle actin expression and polymerization and prevented the upregulation of fibronectin and collagen in TGFbeta1-treated fibroblasts. Finally, we examined how 1,25(OH)(2)D(3) affects epithelial-mesenchymal transformation of lung epithelial cells upon exposure to TGFbeta1. We showed that the TGFbeta1-induced upregulation of mesenchymal cell markers and abnormal expression of epithelial cell markers were blunted by 1,25(OH)(2)D(3). These observations suggest that under TGFbeta1 stimulation, 1,25(OH)(2)D(3) inhibits the pro-fibrotic phenotype of lung fibroblasts and epithelial cells.

Several lines of evidence indicate that depletion of glutathione (GSH), a critical thiol antioxidant, is associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, GSH synthesis depends on the amino acid cysteine (Cys), and relatively little is known about the regulation of Cys in fibrosis. Cys and its disulfide, cystine (CySS), constitute the most abundant low-molecular weight thiol/disulfide redox couple in the plasma, and the Cys/CySS redox state (EhCys/CySS) is oxidized in association with age and smoking, known risk factors for IPF. Furthermore, oxidized EhCys/CySS in the culture media of lung fibroblasts stimulates proliferation and expression of transitional matrix components. The present study was undertaken to determine whether bleomycin-induced lung fibrosis is associated with a decrease in Cys and/or an oxidation of the Cys/CySS redox state and to determine whether these changes were associated with changes in EhGSH/glutathione disulfide (GSSG). We observed distinct effects on plasma GSH and Cys redox systems during the progression of bleomycin-induced lung injury. Plasma EhGSH/GSSG was selectively oxidized during the proinflammatory phase, whereas oxidation of EhCys/CySS occurred at the fibrotic phase. In the epithelial lining fluid, oxidation of EhCys/CySS was due to decreased food intake. Thus the data show that decreased precursor availability and enhanced oxidation of Cys each contribute to the oxidation of extracellular Cys/CySS redox state in bleomycin-induced lung fibrosis.

Obliterative bronchiolitis (OB) and Bronchiolitis Obliterans Syndrome (BOS) are frequent complications in the lung transplant recipient, and are the leading cause of mortality after transplantation. The mechanisms responsible for OB remain elusive, but inflammatory and tissue remodeling responses are implicated. We hypothesized that alterations in markers of tissue remodeling in BALF of lung transplant recipients could predict development of OB. To test this, we identified 13 lung transplant recipients who developed both BOS and histologic OB (OB group) at median post-operative day (POD) 485 (range 73–2070). Bronchoalveolar lavage fluid (BALF) was obtained at median POD 387 (range 45–2205), which preceded the onset of OB and BOS by a median of 140 days (range 60–365). As a control, BALF was also obtained from a group of 21 stable recipients without OB (non-OB group) at median POD 335 (range 270–395). BALF was examined for gelatinolytic activity, fibronectin gene transcription, and transforming growth factor-β1 (TGF-β1) expression. Gelatin zymography of BALF from the OB group showed increased matrix metalloproteinase-9 (MMP-9) activity over that of the non-OB group (p < 0.005). Similarly, BALF from the OB group induced greater fibronectin expression in fibroblasts compared to the non-OB group (p < 0.03). The induction of fibronectin also correlated with the amount of TGF-β1 protein in BALF (r = 0.71) from the OB group. We conclude that activation of tissue remodeling precedes the onset of OB, and analysis of gelatinolytic and/or fibronectin-inducing activity in BALF can serve as an early, pre-clinical marker for OB.

Apoptosis has been implicated as an important process in the development of several organ systems, including limbs, kidneys, and the heart. In developing murine lungs, we found that apoptosis was more predominant during the pseudoglandular stage of lung development than during the saccular stage with ninety-three percent of the apoptotic structures in the mesenchyme. Murine lung explants cultured in the presence of zinc chloride and aurintricarboxylic acid, two blockers of endonuclease function, showed decreased branching. These observations suggest that apoptosis predominates in mesenchymal cells during the pseudoglandular stage of lung development, and may be important for normal progression of lung branching morphogenesis.

Oxidant stress has been implicated in the pathogenesis of chronic lung disorders like idiopathic pulmonary fibrosis. However, mechanisms that link oxidant stress to fibrogenesis remain partially elucidated. Emerging data suggest an important role for the extracellular thiol/disulfide redox environment. The cysteine (Cys)/cystine (CySS) redox couple represents the predominant low-molecular-weight thiol/disulfide pool found in plasma and is sensitive to aging, smoking, and other host factors. We hypothesized that an oxidized extracellular Cys/CySS redox potential (EhCys/CySS) affects lung fibroblasts by inducing intracellular signals that stimulate proliferation and matrix expression. We tested this hypothesis in primary murine lung fibroblasts and found that an oxidized EhCys/CySS (−46 mV) stimulated lung fibroblast proliferation. Furthermore, it stimulated their expression of fibronectin, a matrix glycoprotein highly expressed in fibrotic lung diseases and implicated in lung injury. This stimulatory effect was dependent on protein kinase C activation. Oxidant stress also increased the phosphorylation of cAMP response element binding protein, a transcription factor known for its ability to stimulate fibronectin expression, and increased the expression of mRNAs and proteins coding for the transcription factors nuclear factor (NF)-κB and mothers against decapentaplegic homolog 3. Fibroblasts cultured in normal (−80 mV) or reduced (−131 mV) EhCys/CySS showed less induction. Furthermore, fibronectin expression in response to an oxidized EhCys/CySS was associated with expression of transforming growth factor-β1 (TGF-β1) and was inhibited by an anti-TGF-β1 antibody and SB-431542, a TGF-β1 receptor inhibitor. These studies suggest that extracellular oxidant stress activates redox-sensitive pathways that stimulate lung fibroblast proliferation and matrix expression through upregulation of TGF-β1.

There is abundant epidemiological data linking prenatal environmental tobacco smoke with childhood asthma and wheezing, but the underlying molecular and physiological mechanisms that occur in utero to explain this link remain unelucidated. Several studies suggest that nicotine, which traverses the placenta, is a causative agent. Therefore, we studied the effects of nicotine on lung branching morphogenesis using embryonic murine lung explants. We found that the expression of α7 nicotinic acetylcholine receptors, which mediate many of the biological effects of nicotine, is highest in pseudoglandular stage lungs compared with lungs at later stages. We then studied the effects of nicotine in the explant model and found that nicotine stimulated lung branching in a dose-dependent fashion. α-Bungarotoxin, an antagonist of α7 nicotinic acetylcholine receptors, blocked the stimulatory effect of nicotine, whereas GTS-21, a specific agonist, stimulated branching, thereby mimicking the effects of nicotine. Explants deficient in α7 nicotinic acetylcholine receptors did not respond to nicotine. Nicotine also stimulated the growth of the explant. Altogether, these studies suggest that nicotine stimulates lung branching morphogenesis through α7 nicotinic acetylcholine receptors and may contribute to dysanaptic lung growth, which in turn may predispose the host to airway disease in the postnatal period.

Rationale: The incidence and severity of the acute respiratory distress syndrome (ARDS) is increased in individuals who abuse alcohol. One possible mechanism by which alcohol increases susceptibility to acute lung injury is through alterations in alveolar macrophage function and induction of tissue remodeling activity. Our objective was to determine whether alcohol abuse, independent of other comorbidities, alters fibronectin and metalloproteinase gene expression in alveolar macrophages and in epithelial lining fluid (ELF) of the lung. Methods: Otherwise healthy subjects with alcohol abuse (n=21) and smoking-matched controls (n=17) underwent bronchoalveolar lavage. Alveolar macrophage fibronectin and matrix metalloproteinase (MMP) mRNA expression were measured via reverse transcription-polymerase chain reaction. The supernatant from cultured alveolar macrophages and lung ELF were tested for their ability to induce fibronectin and MMP-9 gene transcription in cell-based assays. Results: Alveolar macrophages from subjects with alcohol abuse demonstrated increased fibronectin mRNA expression (p

Both Alcoholic Liver Disease (ALD) and alcohol-related susceptibility to acute lung injury are estimated to account for the highest morbidity and mortality related to chronic alcohol abuse and, thus, represent a focus of intense investigation. In general, alcohol-induced derangements to both organs are considered to be independent and are often evaluated separately. However, the liver and lung share many general responses to damage, and specific responses to alcohol exposure. For example, both organs possess resident macrophages that play key roles in mediating the immune/inflammatory response. Additionally, alcohol-induced damage to both organs appears to involve oxidative stress that favors tissue injury. Another mechanism that appears to be shared between the organs is that inflammatory injury to both organs is enhanced by alcohol exposure. Lastly, altered extracellular matrix (ECM) deposition appears to be a key step in disease progression in both organs. Indeed, recent studies suggest that early subtle changes in the ECM may predispose the target organ to an inflammatory insult. The purpose of this chapter is to review the parallel mechanisms of liver and lung injury in response to alcohol consumption. This chapter will also explore the potential that these mechanisms are interdependent, as part of a gut-liver-lung axis.

The progression of pulmonary fibrosis (PF) entails a complex network of interactions between multiple classes of molecules and cells, which are closely related to the vagus nerve. Stimulation of the vagus nerve increases fibrogenic cytokines in humans, therefore, activation of the nerve may promote PF. The hypothesis was tested by comparing the extent and severity of fibrosis in lungs with and without vagal innervation in unilaterally vagotomized mice. The results show that in vagotomized lungs, there were less collagen staining, less severe fibrotic foci (subpleural, peri-vascular and peri-bronchiolar lesions) and destruction of alveolar architecture; decreased collagen deposition (denervated vs intact: COL1α1, 19.1 ± 2.2 vs 22.0 ± 2.6 ng/mg protein; COL1α2, 4.5 ± 0.3 vs 5.7 ± 0.5 ng/mg protein; p

The etiology of idiopathic pulmonary fibrosis (IPF) is unknown. Because viral pathogenesis of IPF has been suggested, we have established a murine model of progressive pulmonary fibrosis by infecting IFN-gammaR-deficient mice (IFN-gammaR(-/-)) with the murine gamma-herpesvirus 68. Because alveolar macrophages in humans with IPF have been implicated in driving the profibrotic response, we studied their role in our model. Chronic herpesvirus infection of the lung was associated with recruitment of alveolar macrophages to areas with epithelial hyperplasia and fibrosis in infected lungs. Using immunohistochemistry, Western blot, and RT-PCR techniques, we demonstrated that recruited alveolar macrophages showed high levels of expression of the proteins Ym1/2, FIZZ1 (found in inflammatory zone 1), insulin-like growth factor-1, and arginase I, and also active transcription of fibronectin, indicative of activation of macrophages by an alternative pathway. Arginase I expression was also evident in interstitial fibroblasts, and increased arginase activity was found in lungs of infected animals. Lung tissue from patients with IPF showed increased expression of arginase I in epithelial cells, fibroblast foci, and alveolar macrophages compared with normal lung. These results suggest that virus-induced upregulation of arginase I could be a mechanism driving lung fibrogenesis.

Background: Abnormalities of lung coagulation and fibrinolysis in sarcoidosis are thought to play a role in the pathogenesis of this disease. Objective: We previously showed that bronchoalveolar lavage fluid (BALF) D dimer directly correlated with various measures of severity in sarcoidosis. Here, we analyze our observation that BALF D dimer was more frequently found at higher levels in African-American patients with pulmonary sarcoidosis. Methods: BALF D dimer was measured in 55 subjects with pulmonary sarcoidosis and 31 healthy volunteers by enzyme immunoassay. The healthy group established a normal range of BALF D dimer with 71 ng/ml as the highest measured level. This was the cut point for comparisons among the patients with sarcoidosis. Results: High BALF D dimer levels (>71 ng/ml) were found in younger patients with sarcoidosis and were associated with a significantly lower percent predicted forced expiratory volume in 1 s and greater numbers of BAL lymphocytes. Black patients with sarcoidosis had higher BALF D dimer levels (median 131, range 0–2,040 ng/ml) than white patients (median 18, range 0–605 ng/ml; p = 0.011). Higher than normal BALF D dimer levels were found in 61% of the black subjects with sarcoidosis, but in only 20% of the white individuals (χ2 = 5.539, p = 0.019). BALF D dimer was the only disease measure that discriminated black from white individuals with sarcoidosis. Conclusion: BALF D dimer is an indicator of lung fibrin formation and degradation in sarcoidosis. The relationship of high D dimer levels with greater BAL lymphocytosis and worse lung function may be a marker of active sarcoidosis, especially in African-Americans who tend to suffer a more serious form of the disease.

Latency and reactivation are a significant problem that contributes to the incidence, transmission and pathogenesis of tuberculosis. The mechanisms involved in these processes, at the level of both the bacillus and the host, are poorly understood. InMycobacterium tuberculosistheα-crystallin (acr) gene has been linked to latency, because it is highly expressed during hypoxic growth conditions. Deletion of theacrgene inM. tuberculosisH37Rv (Δacrstrain) was previously shown to reduce the intracellular growth of bacilli in macrophages; however, its impact on pathogenesisin vivowas unknown. This study demonstrated that infection of C57BL6 mice with Δacrresults in lung bacillary loads 1-2 log units higher in comparison to parental H37Rv. Haematoxylin/eosin staining of lungs revealed exacerbated pathology characterized by extensive obliteration of alveolar air spaces by granulomatous inflammation. RT-PCR analysis and immunostaining of lungs showed that infection with either H37Rv or Δacrresults in the differential expression of lysosomal cathepsin proteases. A slight increase in the expression of the matrix-degrading acidic-type cathepsins B, D and H was noted in Δacr-infected mice and was associated with clusters of macrophages within lung granulomas. Δacr-infected mice also showed high serum levels of TNF-α, IFN-γand G-CSF, suggesting that Acr may play a role in modulating the host response to infection.

Background It is well known that liver and lung injury can occur simultaneously during severe inflammation (e.g., multiple organ failure). However, whether these are parallel or interdependent (i.e., liver–lung axis) mechanisms is unclear. Previous studies have shown that chronic ethanol (EtOH) consumption greatly increases mortality in the setting of sepsis-induced acute lung injury (ALI). The potential contribution of subclinical liver disease in driving this effect of EtOH on the lung remains unknown. Therefore, the purpose of this study was to characterize the impact of chronic EtOH exposure on concomitant liver and lung injury. Methods Male mice were exposed to EtOH-containing Lieber–DeCarli diet or pair-fed control diet for 6 weeks. Some animals were administered lipopolysaccharide (LPS) 4 or 24 hours prior to sacrifice to mimic sepsis-induced ALI. Some animals received the tumor necrosis factor-alpha (TNF-α)-blocking drug, etanercept, for the duration of alcohol exposure. The expression of cytokine mRNA in lung and liver tissue was determined by quantitative PCR. Cytokine levels in the bronchoalveolar lavage fluid and plasma were determined by Luminex assay. Results As expected, the combination of EtOH and LPS caused liver injury, as indicated by significantly increased levels of the transaminases alanine aminotransferase/aspartate aminotransferase in the plasma and by changes in liver histology. In the lung, EtOH preexposure enhanced pulmonary inflammation and alveolar hemorrhage caused by LPS. These changes corresponded with unique alterations in the expression of pro-inflammatory cytokines in the liver (i.e., TNF-α) and lung (i.e., macrophage inflammatory protein-2 [MIP-2], keratinocyte chemoattractant [KC]). Systemic depletion of TNF-α (etanercept) blunted injury and the increase in MIP-2 and KC caused by the combination of EtOH and LPS in the lung. Conclusions Chronic EtOH preexposure enhanced both liver and lung injury caused by LPS. Enhanced organ injury corresponded with unique changes in the pro-inflammatory cytokine expression profiles in the liver and the lung.

Lung carcinoma often occurs in patients with chronic lung disease such as tobacco-related emphysema and asbestos-related pulmonary fibrosis. These diseases are characterized by dramatic alterations in the content and composition of the lung extracellular matrix, and we believe this “altered” matrix has the ability to promote lung carcinoma cell growth. One extracellular matrix molecule shown to be altered in these lung diseases is fibronectin (Fn). We previously reported increased growth and survival of non-small cell lung carcinoma (NSCLC) cells exposed to Fn. Thus Fn may serve as a mitogen/survival factor for NSCLC and therefore represents a novel target for anti-cancer strategies. To this end, we studied the effects of the PPARγ ligands 15d-PGJ2, rosiglitazone ( BRL49653 ), and troglitazone on Fn expression in NSCLC cells and found that they were able to inhibit Fn gene transcription. Inhibition of Fn expression by BRL49653 and troglitazone, but not by 15d-PGJ2, was prevented by the specific PPARγ antagonist GW-9662 and by PPARγ small interfering RNA. Working with Fn deletion and mutated promoter constructs, we found that the region between −170 and −50 bp downstream from the transcriptional start site of the promoter was involved in PPARγ ligand inhibition. PPARγ ligands also diminished the phosphorylation of CREB, diminished Sp1 nuclear protein expression, and prevented the binding of these transcription factors to CRE and Sp1 sites, respectively, within the Fn promoter. In summary, our results demonstrate that PPARγ ligands inhibit Fn gene expression in NSCLC cells through PPARγ-dependent and -independent pathways that affect both CREB and Sp1.

We sought to determine whether an intact bone marrow is essential to lung repair following bleomycin-induced lung injury in mice, and the mechanisms of any protective effects conferred by bone marrow–derived mesenchymal stem cell (BMDMSC) transfer. We found that myelosupression increased susceptibility to bleomycin injury and that BMDMSC transfer was protective. Protection was associated with the differentiation of engrafted BMDMSC into specific and distinct lung cell phenotypes, with an increase in circulating levels of G-CSF and GM-CSF (known for their ability to promote the mobilization of endogenous stem cells) and with a decrease in inflammatory cytokines. In vitro, cells from injured, but not from normal, mouse lung produced soluble factors that caused BMDMSC to proliferate and migrate toward the injured lung. We conclude that bone marrow stem cells are important in the repair of bleomycin-injured lung and that transfer of mesenchymal stem cells protects against the injury. BMDMSC localize to the injured lung and assume lung cell phenotypes, but protection from injury and fibrosis also involves suppression of inflammation and triggering production of reparative growth factors.

Clinical studies have demonstrated that chronic alcohol abuse is an independent outcome variable in acute lung injury. The Emory Center for the Study of Acute Lung Injury is determining the mechanisms by which ethanol increases susceptibility to acute lung injury. We developed a rat model of chronic ethanol ingestion and demonstrated that ethanol predisposes rats to edematous lung injury elicited by endotoxemia or sepsis. Chronic ethanol ingestion in rats led to decreased levels of glutathione, an important antioxidant in the lung, and this defect was associated with alterations in epithelial cell permeability, decreased alveolar liquid clearance, decreased cell viability, and decreased surfactant production. Chronic ethanol ingestion also led to the activation of lung tissue remodeling as demonstrated by the increased expression of profibrotic growth factors, matrix components, and metalloproteases. In cultured fibroblasts, the induction of the matrix glycoprotein fibronectin by ethanol was mediated via nicotinic acetylcholine receptor-dependent signal transduction. We speculate that these alterations render the host susceptible to acute lung injury by diminishing the protective mechanisms of the lung and promoting exaggerated inflammatory and tissue repair responses elicited against injurious agents.