Small-Molecule Activation of Protein Phosphatase 2A Counters Bleomycin-Induced Fibrosis in Mice

The activity of protein phosphatase 2A (PP2A), a serine-threonine phosphatase, is reduced in the lung fibroblasts of idiopathic pulmonary fibrosis (IPF) patients. The objective of this study was to determine whether the reactivation of PP2A could reduce fibrosis and preserve the pulmonary function in a bleomycin (BLM) mouse model. Here, we present a new class of direct small-molecule PP2A activators, diarylmethyl-pyran-sulfonamide, exemplified by ATUX-1215. ATUX-1215 has improved metabolic stability and bioavailability compared to our previously described PP2A activators. Primary human lung fibroblasts were exposed to ATUX-1215 and an older generation PP2A activator in combination with TGFβ. ATUX-1215 treatment enhanced the PP2A activity, reduced the phosphorylation of ERK and JNK, and reduced the TGFβ-induced expression of ACTA2, FN1, COL1A1, and COL3A1. C57BL/6J mice were administered 5 mg/kg ATUX-1215 daily following intratracheal instillation of BLM. Three weeks later, forced oscillation and expiratory measurements were performed using the Scireq Flexivent System. ATUX-1215 prevented BLM-induced lung physiology changes, including the preservation of normal PV loop, compliance, tissue elastance, and forced vital capacity. PP2A activity was enhanced with ATUX-1215 and reduced collagen deposition within the lungs. ATUX-1215 also prevented the BLM induction of Acta2, Ccn2, and Fn1 gene expression. Treatment with ATUX-1215 reduced the phosphorylation of ERK, p38, JNK, and Akt and the secretion of IL-12p70, GM-CSF, and IL1α in BLM-treated animals. Delayed treatment with ATUX-1215 was also observed to slow the progression of lung fibrosis. In conclusion, our study indicates that the decrease in PP2A activity, which occurs in fibroblasts from the lungs of IPF subjects, could be restored with ATUX-1215 administration as an antifibrotic agent.

Cultured Mesenchymal Cells from Nasal Turbinate as a Cellular Model of the Neurodevelopmental Component of Schizophrenia Etiology

The study of neurodevelopmental molecular mechanisms in schizophrenia requires the development of adequate biological models such as patient-derived cells and their derivatives. We previously utilized cell lines with neural progenitor properties (CNON) derived from the superior or middle turbinates of patients with schizophrenia and control groups to study schizophrenia-specific gene expression. In this study, we analyzed single-cell RNA seq data from two CNON cell lines (one derived from an individual with schizophrenia (SCZ) and the other from a control group) and two biopsy samples from the middle turbinate (MT) (also from an individual with SCZ and a control). We compared our data with previously published data regarding the olfactory neuroepithelium and demonstrated that CNON originated from a single cell type present both in middle turbinate and the olfactory neuroepithelium and expressed in multiple markers of mesenchymal cells. To define the relatedness of CNON to the developing human brain, we also compared CNON datasets with scRNA-seq data derived from an embryonic brain and found that the expression profile of the CNON closely matched the expression profile one of the cell types in the embryonic brain. Finally, we evaluated the differences between SCZ and control samples to assess the utility and potential benefits of using CNON single-cell RNA seq to study the etiology of schizophrenia.

Cultured Mesenchymal Cells from Nasal Turbinate as a Cellular Model of the Neurodevelopmental Component of Schizophrenia Etiology

Study of the neurodevelopmental molecular mechanisms of schizophrenia requires the development of adequate biological models such as patient-derived cells and their derivatives. We previously used cell lines with neural progenitor properties (CNON) derived from superior or middle turbinates of patients with schizophrenia and control groups to study gene expression specific to schizophrenia. In this study, we compared single cell-RNA seq data from two CNON cell lines, one derived from an individual with schizophrenia (SCZ) and the other from a control group, with two biopsy samples from the middle turbinate (MT), also from an individual with SCZ and a control. In addition, we compared our data with previously published data from olfactory neuroepithelium (1). Our data demonstrated that CNON originated from a single cell type which is present both in middle turbinate and olfactory neuroepithelium. CNON express multiple markers of mesenchymal cells. In order to define relatedness of CNON to the developing human brain, we also compared CNON datasets with scRNA-seq data of embryonic brain (2) and found that the expression profile of CNON very closely matched one of the cell types in the embryonic brain. Finally, we evaluated differences between SCZ and control samples to assess usability and potential benefits of using single cell RNA-seq of CNON to study etiology of schizophrenia.

Lung Function in Women With and Without Human Immunodeficiency Virus

BACKGROUND

Prior studies have found that human immunodeficiency virus (HIV) infection is associated with impaired lung function and increased risk of chronic lung disease, but few have included large numbers of women. In this study, we investigate whether HIV infection is associated with differences in lung function in women.

METHODS

This was a cross-sectional analysis of participants in the Women's Interagency HIV Study, a racially and ethnically diverse multicenter cohort of women with and without HIV. In 2018-2019, participants at 9 clinical sites were invited to perform spirometry. Single-breath diffusing capacity for carbon monoxide (DLCO) was also measured at selected sites. The primary outcomes were the post-bronchodilator forced expiratory volume in 1 second (FEV1) and DLCO. Multivariable regression modeling was used to analyze the association of HIV infection and lung function outcomes after adjustment for confounding exposures.

RESULTS

FEV1 measurements from 1489 women (1062 with HIV, 427 without HIV) and DLCO measurements from 671 women (463 with HIV, 208 without HIV) met standards for quality and reproducibility. There was no significant difference in FEV1 between women with and without HIV. Women with HIV had lower DLCO measurements (adjusted difference, -0.73 mL/min/mm Hg; 95% confidence interval, -1.33 to -.14). Among women with HIV, lower nadir CD4 + cell counts and hepatitis C virus infection were associated with lower DLCO measurements.

CONCLUSIONS

HIV was associated with impaired respiratory gas exchange in women. Among women with HIV, lower nadir CD4 + cell counts and hepatitis C infection were associated with decreased respiratory gas exchange.

Association Between HIV and Prevalence and Manifestations of Asthma: Analysis of the Multicenter AIDS Cohort Study and Women's Interagency HIV Study

BACKGROUND

The association between HIV and asthma prevalence and manifestations remains unclear, with few studies including women.

SETTING

A retrospective observational cohort study from the Multicenter AIDS Cohort Study and Women's Interagency HIV Study.

METHODS

Asthma was defined in 2 ways: (1) self-report and (2) robust criteria requiring all the following: lack of fixed airflow obstruction, presence of wheeze on the St. George's Respiratory Questionnaire (SGRQ), and report of asthma therapies. Estimates of asthma prevalence and asthma-related manifestations were compared by HIV serostatus.

RESULTS

A total of 1815 men and 2122 women were included. Asthma prevalence did not differ between people with HIV (PWH) and people without HIV regardless of definition: self-report (men, 12.0% vs. 11.2%; women, 24.3% vs. 27.5%) and robust criteria (men, 5.0% vs. 3.4%; women, 12.8% vs. 13.2%). Among men with asthma, worse respiratory symptom burden was reported among those with HIV, regardless of asthma definition. Among women with self-reported asthma, those with HIV had less respiratory symptom burden. Regardless of serostatus, women with robust-defined asthma had similar respiratory symptoms across SGRQ domains and similar frequencies of phlegm, shortness of breath, and wheezing.

CONCLUSIONS

Among PWH and people without HIV, asthma prevalence was 2-fold to 3-fold higher using self-reported definition rather than robust definition. In men and women, HIV was not associated with increased asthma prevalence. In men, HIV was associated with more respiratory symptoms when asthma was self-reported; the relationship was attenuated with the robust criteria. Further studies are needed to explore asthma phenotypes among PWH.

Pulmonary Function Trajectories in People with HIV: Analysis of the Pittsburgh HIV Lung Cohort

Rationale: Human immunodeficiency virus (HIV) infection is associated with chronic lung disease and impaired pulmonary function; however, longitudinal pulmonary function phenotypes in HIV are undefined. Objectives: To identify pulmonary function trajectories, their determinants, and outcomes. Methods: We used data from participants with HIV in the Pittsburgh HIV Lung Cohort with three or more pulmonary function tests between 2007 and 2020. We analyzed post-bronchodilator forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC, and diffusing capacity of the lung for carbon monoxide (DlCO) using group-based trajectory modeling to identify subgroups of individuals whose measurements followed a similar pattern over time. We examined the association between participant characteristics and trajectories using multivariable logistic regression. In exploratory adjusted analyses restricted to individuals with available plasma cytokine data, we investigated the association between 18 individual standardized cytokine concentrations and trajectories. We compared mortality, dyspnea prevalence, respiratory health status, and 6-minute-walk distance between phenotypes. Results: A total of 265 participants contributed 1,606 pulmonary function measurements over a median follow-up of 8.1 years. We identified two trajectories each for FEV1 and FVC: "low baseline, slow decline" and "high baseline, rapid decline." There were three trajectory groups for FEV1/FVC: "rapid decline," "moderate decline," and "slow decline." Finally, we identified two trajectories for DlCO: "baseline low" and "baseline high." The low baseline, slow decline FEV1 and FVC, rapid decline, and moderate decline FEV1/FVC, and baseline low DlCO phenotypes were associated with increased dyspnea prevalence, worse respiratory health status, and decreased 6-minute-walk distance. The baseline low DlCO phenotype was also associated with worse mortality. Current smoking and pack-years of smoking were associated with the adverse FEV1, FEV1/FVC, and DlCO phenotypes. Detectable viremia was the only HIV marker associated with the adverse DlCO phenotype. C-reactive protein and endothelin-1 were associated with the adverse FEV1 and FVC phenotypes, and endothelin-1 trended toward an association with the adverse DlCO phenotype. Conclusions: We identified novel, distinct longitudinal pulmonary function phenotypes with significant differences in characteristics and outcomes. These findings highlight the importance of lung dysfunction over time in people with HIV and should be validated in additional cohorts.

Comparing the demographics and laboratory biomarkers of the COVID-19 Omicron wave and the Alpha wave in a predominantly Afro-Caribbean patient population in New York City

BACKGROUND

There is a knowledge gap of specific characteristics linked to disease severity of the different COVID-19 waves, especially in underserved populations. We compared the demographic and clinical factors associated with SARS-CoV-2-infected patients admitted to the intensive care unit (ICU) during the Omicron and Alpha waves.

METHODS

An observational study comparing two COVID-19 waves was conducted in Brooklyn, NY. Twenty-seven ICU admitted patients with a positive COVID-19 test result during the period of November 1, 2021, to January 31, 2022, ("Omicron wave") were compared to 271 COVID-19 patients who received ICU consults during the Alpha wave, the period from March 28, 2020, to April 30, 2020.

RESULTS

The Omicron wave had a 55.6% mortality rate compared to a 67.2% mortality rate in the Alpha wave. For the non-survivors, there were more females (66.7%) in the Omicron wave, while the trend was reversed in the Alpha wave (38.5%). Most of the patients seen were Black (> 85%) in both waves. A bivariate comparison of the two waves found that patients in the Omicron wave had overall significantly lower ALT levels (p = 0.03) and higher monocyte % (p = 0.005) compared to the patients in the Alpha wave. In the multivariate analysis, adjusting for age and sex, increasing levels of HCO3- were significantly associated with reduced mortality in the Omicron wave (OR: 0.698; 95% CI: 0.516 - 0.945; p = 0.02). Also, multivariable analyses using both waves combined found that neutrophil % was significantly associated with increased mortality (OR: 1.05; 95% CI: 1.02 - 1.09; p = 0.006) while lymphocyte % was significantly associated with reduced mortality (OR: 0.946; 95% CI: 0.904 - 0.990; p = 0.018).

CONCLUSIONS

The COVID-19-positive ICU patients in the Omicron wave experienced less severe outcomes than those of the Alpha wave. In contrast to the Alpha variant, the Omicron variant exhibited enhanced infectivity and disease severity in females.

Procalcitonin Levels in COVID-19 Patients Are Strongly Associated with Mortality and ICU Acceptance in an Underserved, Inner City Population

Background and Objectives: This study aimed to identify demographic and clinical factors at the time of critical care consultation associated with mortality or intensive care unit acceptance in a predominantly Afro-Caribbean population during the first wave of the COVID19 pandemic. Materials and Methods: This retrospective, single-center observational cohort study included 271 COVID19 patients who received a critical care consult between March 11 and April 30, 2020 during the first wave of the COVID19 pandemic at State University of New York Downstate Health Sciences University. Results: Of the 271 patients with critical care consults, 33% survived and 67% expired. At the bivariate level, age, blood urea nitrogen, and blood neutrophil percentage were significantly associated with mortality (mean age: survivors, 61.62 ± 1.50 vs. non-survivors, 68.98 ± 0.85, p < 0.001). There was also a significant association between neutrophil% and mortality in the univariate logistic regression model (quartile 4 vs. quartile 1: odd ratio 2.73, 95% confidence interval (1.28–5.82), p trend = 0.044). In the multivariate analyses, increasing levels of procalcitonin and C-reactive protein were significantly associated with mortality, adjusting for age, sex, and race/ethnicity (for procalcitonin quartile 4 vs. quartile 1: odds ratio 5.65, 95% confidence interval (2.14–14.9), p trend < 0.001). In contrast, higher platelet levels correlated with significantly decreased odds of mortality (quartile 4 vs. quartile 1, odds ratio 0.47, 95% CI (0.22–0.998), p trend = 0.010). Of these factors, only elevated procalcitonin levels were associated with intensive care unit acceptance. Conclusions: Procalcitonin showed the greatest magnitude of association with both death and likelihood of intensive care unit acceptance at the bivariate level. Our data suggests that procalcitonin reflects pneumonia severity during COVID-19 infection. Thus, it may help the intensivist identify those COVID19 patients who require intensive care unit level care.

Abnormal C5 production and activation contributes to the mortality of COVID-19 patients

Elucidating the pathogenesis of COVID-19 is vital for treating the disease. Recent clinical studies have suggested that the complement system may play an important role in the course of infection. We investigated the correlation between complement C5, a critical factor in the complement common pathway, and the mortality of COVID-19. Thirty-seven COVID-19 patients were consented for this study. Serial blood samples were collected at different time points from 27 patients who recovered during hospitalization, and 10 patients who did not survive during hospitalization. Circulating native C5 was analyzed by Western Blot to detect α-chain and β-chain of intact C5. The activated C5a levels were detected by an ELISA kit. The levels of C5 β-chain and C5a were significantly higher in the non-survivors than in the survivors. Multivariate regression analyses showed that abnormal levels of C5 β-chain and C5a could independently predict the mortality. Therefore, our results suggest that in COVID-19 patients, the abnormal C5 production and activation may contribute to the systemic inflammation thus affect survival.

Cigarette smoke induction of S100A9 contributes to chronic obstructive pulmonary disease

S100 calcium-binding protein A9 (S100A9) is elevated in plasma and bronchoalveolar lavage fluid (BALF) of patients with chronic obstructive pulmonary disease (COPD), and aging enhances S100A9 expression in several tissues. Currently, the direct impact of S100A9-mediated signaling on lung function and within the aging lung is unknown. Here, we observed that elevated S100A9 levels in human BALF correlated with age. Elevated lung levels of S100A9 were higher in older mice compared with in young animals and coincided with pulmonary function changes. Both acute and chronic exposure to cigarette smoke enhanced S100A9 levels in age-matched mice. To examine the direct role of S100A9 on the development of COPD, S100a9^-/- mice or mice administered paquinimod were exposed to chronic cigarette smoke. S100A9 depletion and inhibition attenuated the loss of lung function, pressure-volume loops, airway inflammation, lung compliance, and forced expiratory volume in 0.05 s/forced vital capacity, compared with age-matched wild-type or vehicle-administered animals. Loss of S100a9 signaling reduced cigarette smoke-induced airspace enlargement, alveolar remodeling, lung destruction, ERK and c-RAF phosphorylation, matrix metalloproteinase-3 (MMP-3), matrix metalloproteinase-9 (MMP-9), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and keratinocyte-derived chemokine (KC) release into the airways. Paquinimod administered to nonsmoked, aged animals reduced age-associated loss of lung function. Since fibroblasts play a major role in the production and maintenance of extracellular matrix in emphysema, primary lung fibroblasts were treated with the ERK inhibitor LY3214996 or the c-RAF inhibitor GW5074, resulting in less S100A9-induced MMP-3, MMP-9, MCP-1, IL-6, and IL-8. Silencing Toll-like receptor 4 (TLR4), receptor for advanced glycation endproducts (RAGE), or extracellular matrix metalloproteinase inducer (EMMPRIN) prevented S100A9-induced phosphorylation of ERK and c-RAF. Our data suggest that S100A9 signaling contributes to the progression of smoke-induced and age-related COPD.

Airway Resistance Caused by Sphingomyelin Synthase 2 Insufficiency in Response to Cigarette Smoke

Sphingomyelin synthase is responsible for the production of sphingomyelin (SGM), the second most abundant phospholipid in mammalian plasma, from ceramide, a major sphingolipid. Knowledge of the effects of cigarette smoke on SGM production is limited. In the present study, we examined the effect of chronic cigarette smoke on sphingomyelin synthase (SGMS) activity and evaluated how the deficiency of Sgms2, one of the two isoforms of mammalian SGMS, impacts pulmonary function. Sgms2-knockout and wild-type control mice were exposed to cigarette smoke for 6 months, and pulmonary function testing was performed. SGMS2-dependent signaling was investigated in these mice and in human monocyte-derived macrophages of nonsmokers and human bronchial epithelial (HBE) cells isolated from healthy nonsmokers and subjects with chronic obstructive pulmonary disease (COPD). Chronic cigarette smoke reduces SGMS activity and Sgms2 gene expression in mouse lungs. Sgms2-deficient mice exhibited enhanced airway and tissue resistance after chronic cigarette smoke exposure, but had similar degrees of emphysema, compared with smoke-exposed wild-type mice. Sgms2-/- mice had greater AKT phosphorylation, peribronchial collagen deposition, and protease activity in their lungs after smoke inhalation. Similarly, we identified reduced SGMS2 expression and enhanced phosphorylation of AKT and protease production in HBE cells isolated from subjects with COPD. Selective inhibition of AKT activity or overexpression of SGMS2 reduced the production of several matrix metalloproteinases in HBE cells and monocyte-derived macrophages. Our study demonstrates that smoke-regulated Sgms2 gene expression influences key COPD features in mice, including airway resistance, AKT signaling, and protease production.

Decreased surfactant lipids correlate with lung function in chronic obstructive pulmonary disease (COPD)

Smoke exposure is known to decrease total pulmonary surfactant and alter its composition, but the role of surfactant in chronic obstructive pulmonary disease (COPD) remains unknown. We aimed to analyze the compositional changes in the surfactant lipidome in COPD and identify specific lipids associated with pulmonary function decline. Bronchoalveolar lavage (BAL) fluid was obtained from 12 former smokers with COPD and 5 non-smoking, non-asthmatic healthy control volunteers. Lipids were extracted and analyzed by liquid chromatography and mass spectrometry. Pulmonary function data were obtained by spirometry, and correlations of lung function with lipid species were determined. Wild-type C57BL/6 mice were exposed to 6 months of second-hand smoke in a full-body chamber. Surfactant lipids were decreased by 60% in subjects with COPD. All phospholipid classes were dramatically decreased, including ether phospholipids, which have not been studied in pulmonary surfactant. Availability of phospholipid, cholesterol, and sphingomyelin in BAL strongly correlated with pulmonary function and this was attributable to specific lipid species of phosphatidylcholine with surface tension reducing properties, and of phosphatidylglycerol with antimicrobial roles, as well as to other less studied lipid species. Mice exposed to smoke for six months recapitulated surfactant lipidomic changes observed in human subjects with COPD. In summary, we show that the surfactant lipidome is substantially altered in subjects with COPD, and decreased availability of phospholipids correlated with decreased pulmonary function. Further investigation of surfactant alterations in COPD would improve our understanding of its physiopathology and reveal new potential therapeutic targets.

Insights into Potential Mechanisms of Injury and Treatment Targets in COVID-19, SARS-Cov-2 Infection

The severe acute respiratory syndrome coronavirus 2, SARS-CoV-2, is the most serious pandemic in modern times. The disease was first reported in January of 2020 in China's city of Wuhan, Hubei province, and since then it has spread worldwide. Given the rapid spread of the virus and the burden it has taken on the healthcare systems it has swept through, there is the need for a concise description of current understanding of the pathogenesis of organ failure in SARS-CoV-2 infection while acknowledging that more is yet to be uncovered. This review will not only inform decision making at the bedside but will also help illustrate potential therapeutic targets for research. We searched the available literature to-date, and present the pathophysiology underlying increased morbidity and mortality of SARS-CoV-2 infection in the lungs, heart and kidneys in a highly illustrated presentation that is easy-to-understand for the clinician, researcher, and student alike.

Electronic cigarettes: a task force report from the European Respiratory Society

There is a marked increase in the development and use of electronic nicotine delivery systems or electronic cigarettes (ECIGs). This statement covers electronic cigarettes (ECIGs), defined as "electrical devices that generate an aerosol from a liquid" and thus excludes devices that contain tobacco. Database searches identified published articles that were used to summarise the current knowledge on the epidemiology of ECIG use; their ingredients and accompanied health effects; second-hand exposure; use of ECIGs for smoking cessation; behavioural aspects of ECIGs and social impact; in vitro and animal studies; and user perspectives.ECIG aerosol contains potentially toxic chemicals. As compared to conventional cigarettes, these are fewer and generally in lower concentrations. Second-hand exposures to ECIG chemicals may represent a potential risk, especially to vulnerable populations. There is not enough scientific evidence to support ECIGs as an aid to smoking cessation due to a lack of controlled trials, including those that compare ECIGs with licenced stop-smoking treatments. So far, there are conflicting data that use of ECIGs results in a renormalisation of smoking behaviour or for the gateway hypothesis. Experiments in cell cultures and animal studies show that ECIGs can have multiple negative effects. The long-term effects of ECIG use are unknown, and there is therefore no evidence that ECIGs are safer than tobacco in the long term. Based on current knowledge, negative health effects cannot be ruled out.

Pro-inflammatory effects of e-cigarette vapour condensate on human alveolar macrophages

OBJECTIVE

Vaping may increase the cytotoxic effects of e-cigarette liquid (ECL). We compared the effect of unvaped ECL to e-cigarette vapour condensate (ECVC) on alveolar macrophage (AM) function.

METHODS

AMs were treated with ECVC and nicotine-free ECVC (nfECVC). AM viability, apoptosis, necrosis, cytokine, chemokine and protease release, reactive oxygen species (ROS) release and bacterial phagocytosis were assessed.

RESULTS

Macrophage culture with ECL or ECVC resulted in a dose-dependent reduction in cell viability. ECVC was cytotoxic at lower concentrations than ECL and resulted in increased apoptosis and necrosis. nfECVC resulted in less cytotoxicity and apoptosis. Exposure of AMs to a sub-lethal 0.5% ECVC/nfECVC increased ROS production approximately 50-fold and significantly inhibited phagocytosis. Pan and class one isoform phosphoinositide 3 kinase inhibitors partially inhibited the effects of ECVC/nfECVC on macrophage viability and apoptosis. Secretion of interleukin 6, tumour necrosis factor α, CXCL-8, monocyte chemoattractant protein 1 and matrix metalloproteinase 9 was significantly increased following ECVC challenge. Treatment with the anti-oxidant N-acetyl-cysteine (NAC) ameliorated the cytotoxic effects of ECVC/nfECVC to levels not significantly different from baseline and restored phagocytic function.

CONCLUSIONS

ECVC is significantly more toxic to AMs than non-vaped ECL. Excessive production of ROS, inflammatory cytokines and chemokines induced by e-cigarette vapour may induce an inflammatory state in AMs within the lung that is partly dependent on nicotine. Inhibition of phagocytosis also suggests users may suffer from impaired bacterial clearance. While further research is needed to fully understand the effects of e-cigarette exposure in humans in vivo, we caution against the widely held opinion that e-cigarettes are safe.

Posttranscriptional control of airway inflammation

Acute inflammation in the lungs is a vital protective response, efficiently and swiftly eliminating inciters of tissue injury. However, in respiratory diseases characterized by chronic inflammation, such as chronic obstructive pulmonary disease and asthma, enhanced expression of inflammatory mediators leads to tissue damage and impaired lung function. Although transcription is an essential first step in the induction of proinflammatory genes, tight regulation of inflammation requires more rapid, flexible responses. Increasing evidence shows that such responses are achieved by posttranscriptional mechanisms directly affecting mRNA stability and translation initiation. RNA-binding proteins, microRNAs, and long noncoding RNAs interact with messenger RNA and each other to impact the stability and/or translation of mRNAs implicated in lung inflammation. Recent research has shown that these biological processes play a central role in the pathogenesis of several important pulmonary conditions. This review will highlight several posttranscriptional control mechanisms that influence lung inflammation and the known associations of derangements in these mechanisms with common respiratory diseases. WIREs RNA 2018, 9:e1455. doi: 10.1002/wrna.1455 This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Turnover and Surveillance > Regulation of RNA Stability.

HIV infection model of chronic obstructive pulmonary disease in mice

Cigarette smoke usage is prevalent in human immunodeficiency virus (HIV)-positive patients, and, despite highly active antiretroviral therapy, these individuals develop an accelerated form of chronic obstructive pulmonary disease (COPD). Studies investigating the mechanisms of COPD development in HIV have been limited by the lack of suitable mouse models. Here we describe a model of HIV-induced COPD in wild-type mice using EcoHIV, a chimeric HIV capable of establishing chronic infection in immunocompetent mice. A/J mice were infected with EcoHIV and subjected to whole body cigarette smoke exposure. EcoHIV was detected in alveolar macrophages of mice. Compared with uninfected mice, concomitant EcoHIV infection significantly reduced forced expiratory flow 50%/forced vital capacity and enhanced distal airspace enlargement following cigarette smoke exposure. Lung IL-6, granulocyte-macrophage colony-stimulating factor, neutrophil elastase, cathepsin G, and matrix metalloproteinase-9 expression was significantly enhanced in smoke-exposed EcoHIV-infected mice. These changes coincided with enhanced IκBα, ERK1/2, p38, and STAT3 phosphorylation and lung cell apoptosis. Thus, the EcoHIV smoke exposure mouse model reproduces several of the pathophysiological features of HIV-related COPD in humans, indicating that this murine model can be used to determine key parameters of HIV-related COPD and to test future therapies for this disorder.

Chronic electronic cigarette exposure in mice induces features of COPD in a nicotine-dependent manner

BACKGROUND

The use of electronic (e)-cigarettes is increasing rapidly, but their lung health effects are not established. Clinical studies examining the potential long-term impact of e-cigarette use on lung health will take decades. To address this gap in knowledge, this study investigated the effects of exposure to aerosolised nicotine-free and nicotine-containing e-cigarette fluid on mouse lungs and normal human airway epithelial cells.

METHODS

Mice were exposed to aerosolised phosphate-buffered saline, nicotine-free or nicotine-containing e-cigarette solution, 1-hour daily for 4 months. Normal human bronchial epithelial (NHBE) cells cultured at an air-liquid interface were exposed to e-cigarette vapours or nicotine solutions using a Vitrocell smoke exposure robot.

RESULTS

Inhalation of nicotine-containing e-cigarettes increased airway hyper-reactivity, distal airspace enlargement, mucin production, cytokine and protease expression. Exposure to nicotine-free e-cigarettes did not affect these lung parameters. NHBE cells exposed to nicotine-containing e-cigarette vapour showed impaired ciliary beat frequency, airway surface liquid volume, cystic fibrosis transmembrane regulator and ATP-stimulated K+ ion conductance and decreased expression of FOXJ1 and KCNMA1. Exposure of NHBE cells to nicotine for 5 days increased interleukin (IL)-6 and IL-8 secretion.

CONCLUSIONS

Exposure to inhaled nicotine-containing e-cigarette fluids triggered effects normally associated with the development of COPD including cytokine expression, airway hyper-reactivity and lung tissue destruction. These effects were nicotine-dependent both in the mouse lung and in human airway cells, suggesting that inhaled nicotine contributes to airway and lung disease in addition to its addictive properties. Thus, these findings highlight the potential dangers of nicotine inhalation during e-cigarette use.

Cigarette smoke inhibits ROCK2 activation in T cells and modulates IL-22 production

Gene-environment interactions are known to play a key role in the development of rheumatoid arthritis (RA). Exposure to cigarette smoke (CS) is one of the strongest environmental risk factors associated with RA and has been shown to mediate a range of complex immunomodulatory effects from decreased T and B cell activation to depressed phagocytic function. The effects of CS on the function of TH17 cells, one of the key TH effector subsets implicated in RA pathogenesis, are not fully understood. IRF4 is one of the crucial transcription factors involved in TH-17 differentiation and is absolutely required for the production of IL-17 and IL-21 but, interestingly, inhibits the synthesis of IL-22. The production of IL-17 and IL-21 by IRF4 can be augmented by its phosphorylation by the serine-threonine kinase ROCK2. Given that CS has been reported to increase ROCK activity in endothelial cells, here we investigated the effects of CS on the ROCK2-IRF4 axis in T cells. Surprisingly, we found that CS leads to decreased ROCK2 activation and IRF4 phosphorylation in T cells. This effect was associated with increased IL-22 production. Using a GEF pull-down assay we furthermore identify ARHGEF1 as a key upstream regulator of ROCK2 whose activity in T cells is inhibited by CS. Thus CS can inhibit the ROCK2-IRF4 axis and modulate T cell production of IL-22.

Cathepsin G degradation of phospholipid transfer protein (PLTP) augments pulmonary inflammation

Phospholipid transfer protein (PLTP) regulates phospholipid transport in the circulation and is highly expressed within the lung epithelium, where it is secreted into the alveolar space. Since PLTP expression is increased in chronic obstructive pulmonary disease (COPD), this study aimed to determine how PLTP affects lung signaling and inflammation. Despite its increased expression, PLTP activity decreased by 80% in COPD bronchoalveolar lavage fluid (BALF) due to serine protease cleavage, primarily by cathepsin G. Likewise, PLTP BALF activity levels decreased by 20 and 40% in smoke-exposed mice and in the media of smoke-treated small airway epithelial (SAE) cells, respectively. To assess how PLTP affected inflammatory responses in a lung injury model, PLTP siRNA or recombinant protein was administered to the lungs of mice prior to LPS challenge. Silencing PLTP at baseline caused a 68% increase in inflammatory cell infiltration, a 120 and 340% increase in ERK and NF-κB activation, and increased MMP-9, IL1β, and IFN-γ levels after LPS treatment by 39, 140, and 190%, respectively. Conversely, PLTP protein administration countered these effects in this model. Thus, these findings establish a novel anti-inflammatory function of PLTP in the lung and suggest that proteolytic cleavage of PLTP by cathepsin G may enhance the injurious inflammatory responses that occur in COPD.

STAT3 modulates cigarette smoke-induced inflammation and protease expression

Signal transducer and activator of transcription-3 (STAT3) regulates inflammation, apoptosis, and protease expression, which are critical processes associated with airway injury and lung tissue destruction. However, the precise role of STAT3 in the development of airway diseases such as chronic obstructive pulmonary disease (COPD) has not been established. This study shows that cigarette smoke activates STAT3 in the lungs of mice. Since cigarette smoke activated STAT3 in the lung, we then evaluated how the loss of STAT3 would impact on smoke-mediated lung inflammation, protease expression, and apoptosis. STAT3^+/+ and STAT3^−/− mice were exposed to 8 days of cigarette smoke. Compared to the STAT3^+/+ mice bronchoalveolar lavage fluid (BALF) cellularity was significantly elevated in the STAT3^−/− mice both before and after cigarette smoke exposure, with the increase in cells primarily macrophages. In addition, smoke exposure induced significantly higher BALF protein levels of Interleukin-1α (IL-1α), and monocyte chemotactic protein-1 (MCP-1) and higher tissue expression of keratinocyte chemoattractant (KC) in the STAT3^−/− mice. Lung mRNA expression of MMP-12 was increased in STAT3^−/− at baseline. However, the smoke-induced increase in MMP-10 expression seen in the STAT3^+/+ mice was not observed in the STAT3^−/− mice. Moreover, lung protein levels of the anti-inflammatory proteins SOCS3 and IL-10 were markedly lower in the STAT3^−/− mice compared to the STAT3^+/+ mice. Lastly, apoptosis, as determined by caspase 3/7 activity assay, was increased in the STAT3^−/− at baseline to levels comparable to those observed in the smoke-exposed STAT3^+/+ mice. Together, these results indicate that the smoke-mediated induction of lung STAT3 activity may play a critical role in maintaining normal lung homeostasis and function.

Protein transfection of mouse lung

Increasing protein expression enables researchers to better understand the functional role of that protein in regulating key biological processes(1). In the lung, this has been achieved typically through genetic approaches that utilize transgenic mice(2,3) or viral or non-viral vectors that elevate protein levels via increased gene expression(4). Transgenic mice are costly and time-consuming to generate and the random insertion of a transgene or chronic gene expression can alter normal lung development and thus limit the utility of the model(5). While conditional transgenics avert problems associated with chronic gene expression(6), the reverse tetracycline-controlled transactivator (rtTA) mice, which are used to generate conditional expression, develop spontaneous air space enlargement(7). As with transgenics, the use of viral and non-viral vectors is expensive(8) and can provoke dose-dependent inflammatory responses that confound results(9) and hinder expression(10). Moreover, the efficacy of repeated doses are limited by enhanced immune responses to the vector(11,12). Researchers are developing adeno-associated viral (AAV) vectors that provoke less inflammation and have longer expression within the lung(13). Using β-galactosidase, we present a method for rapidly and effectively increasing protein expression within the lung using a direct protein transfection technique. This protocol mixes a fixed amount of purified protein with 20 μl of a lipid-based transfection reagent (Pro-Ject, Pierce Bio) to allow penetration into the lung tissue itself. The liposomal protein mixture is then injected into the lungs of the mice via the trachea using a microsprayer (Penn Century, Philadelphia, PA). The microsprayer generates a fine plume of liquid aerosol throughout the lungs. Using the technique we have demonstrated uniform deposition of the injected protein throughout the airways and the alveoli of mice(14). The lipid transfection technique allows the use of a small amount of protein to achieve effect. This limits the inflammatory response that otherwise would be provoked by high protein administration. Indeed, using this technique we published that we were able to significantly increase PP2A activity in the lung without affecting lung lavage cellularity(15). Lung lavage cellularity taken 24 hr after challenge was comparable to controls (27 ± 4 control vs. 31 ± 5 albumin transfected; N=6 per group). Moreover, it increases protein levels without inducing lung developmental changes or architectural changes that can occur in transgenic models. However, the need for repeated administrations may make this technique less favorable for studies examining the effects of long-term increases in protein expression. This would be particularly true for proteins with short half-lives.

The divergent roles of secreted frizzled related protein-1 (SFRP1) in lung morphogenesis and emphysema

Developmentally expressed genes are believed to play a central role in tissue repair after injury; however, in lung disease their role has not been established. This study demonstrates that SFRP1, an inhibitor of Wnt signaling normally expressed during lung embryogenesis, is induced in the lungs of emphysema patients and in two murine models of the disease. SFRP1 was found to be essential for alveolar formation as Sfrp1(-/-) mice exhibited aberrant Wnt signaling, mesenchymal proliferation, and impaired alveoli formation. In contrast, SFRP1 activated ERK and up-regulated MMP1 and MMP9 without altering TIMP1 production when expressed in human lung epithelial cells. These findings demonstrate that SFRP1 promotes normal alveolar formation in lung development, although its expression in the adult up-regulates proteins that can cause tissue destruction. Thus, SFRP1 induction during tissue injury is unlikely to contribute to the repair response but rather is a participatory factor in the pathogenesis of emphysema and tissue destruction.

One-step isolation of plasma membrane proteins using magnetic beads with immobilized concanavalin A

We have developed a simple method for isolating and purifying plasma membrane proteins from various cell types. This one-step affinity-chromatography method uses the property of the lectin concanavalin A (ConA) and the technique of magnetic bead separation to obtain highly purified plasma membrane proteins from crude membrane preparations or cell lines. ConA is immobilized onto magnetic beads by binding biotinylated ConA to streptavidin magnetic beads. When these ConA magnetic beads were used to enrich plasma membranes from a crude membrane preparation, this procedure resulted in 3.7-fold enrichment of plasma membrane marker 5'-nucleotidase activity with 70% recovery of the activity in the crude membrane fraction of rat liver. In agreement with the results of 5'-nucleotidase activity, immunoblotting with antibodies specific for a rat liver plasma membrane protein, CEACAM1, indicated that CEACAM1 was enriched about threefold relative to that of the original membranes. In similar experiments, this method produced 13-fold enrichment of 5'-nucleotidase activity with 45% recovery of the activity from a total cell lysate of PC-3 cells and 7.1-fold enrichment of 5'-nucleotidase activity with 33% recovery of the activity from a total cell lysate of HeLa cells. These results suggest that this one-step purification method can be used to isolate total plasma membrane proteins from tissue or cells for the identification of membrane biomarkers.

Transgenic expression of matrix metalloproteinase-9 causes adult-onset emphysema in mice associated with the loss of alveolar elastin

Matrix metalloproteinase (MMP)-9 has been consistently identified in the lungs of patients with chronic obstructive pulmonary disease (COPD). However, its role in the development of the disease remains undefined. Mice that specifically express human MMP-9 in their macrophages were generated, and morphometric, biochemical, and histological analyses were conducted on the transgenic and littermate control mice over 1 yr to determine the effect of macrophage MMP-9 expression on emphysema formation and lung matrix content. Lung morphometry was normal in transgenic mice at 2 mo of age (mean linear intercept = 50+/-3 littermate mice vs. 51+/-2 transgenic mice). However, after 12 mo of age, the MMP-9 transgenic mice developed significant air space enlargement (mean linear intercept = 53+/-3 littermate mice vs. 61+/-2 MMP-9 transgenic mice; P<0.04). Lung hydroxyproline content was not significantly different between wild-type and transgenic mice, but MMP-9 did significantly decrease alveolar wall elastin at 1 yr of age (4.9+/-0.3% area of alveolar wall in the littermate mice vs. 3.3+/-0.3% area of alveolar wall in the MMP-9 mice; P<0.004). Thus these results establish a central role for MMP-9 in the pathogenesis of this disease by demonstrating that expression of this protease in macrophages can alter the extracellular matrix and induce progressive air space enlargement in mice.

Nonmalignant respiratory effects of chronic arsenic exposure from drinking water among never-smokers in Bangladesh

BACKGROUND

Arsenic from drinking water has been associated with malignant and nonmalignant respiratory illnesses. The association with nonmalignant respiratory illnesses has not been well established because the assessments of respiratory symptoms may be influenced by recall bias or interviewer bias because participants had visible skin lesions.

OBJECTIVES

We examined the relationship of the serum level of Clara cell protein CC16--a novel biomarker for respiratory illnesses--with well As, total urinary As, and urinary As methylation indices.

METHODS

We conducted a cross-sectional study in nonsmoking individuals (n = 241) selected from a large cohort with a wide range of As exposure (0.1-761 microg/L) from drinking water in Bangladesh. Total urinary As, urinary As metabolites, and serum CC16 were measured in urine and serum samples collected at baseline of the parent cohort study.

RESULTS

We observed an inverse association between urinary As and serum CC16 among persons with skin lesions (beta = -0.13, p = 0.01). We also observed a positive association between secondary methylation index in urinary As and CC16 levels (beta = 0.12, p = 0.05) in the overall study population; the association was stronger among people without skin lesions (beta = 0.18, p = 0.04), indicating that increased methylation capability may be protective against As-induced respiratory damage. In a subsample of study participants undergoing spirometric measures (n = 31), we observed inverse associations between urinary As and predictive FEV(1) (forced expiratory volume measured in 1 sec) (r = -0.37; FEV(1)/forced vital capacity ratio and primary methylation index (r = -0.42, p = 0.01).

CONCLUSIONS

The findings suggest that serum CC16 may be a useful biomarker of epithelial lung damage in individuals with arsenical skin lesions. Also, we observed the deleterious respiratory effects of As exposure at concentrations lower than reported in earlier studies.

The Effect of Cigarette Smoke-derived Oxidants on the Inflammatory Response of the Lung

The inhalation of cigarette smoke triggers a marked cellular influx in the lung and this inflammation is believed to play a central role in the development of smoke-related lung diseases such as asthma and COPD. Studies demonstrate that smoke-derived oxidants are a major factor in this inflammatory reaction to cigarette smoke. These oxidants can overwhelm the lung's antioxidant defenses and they can up regulate inflammation by a number of mechanisms. Free radicals directly stimulate the production of chemotactic compounds such as 8-isoprostane. In addition, smoke-derived oxidants can activate several intracellular signaling cascades including NF-κB, MAPK and AP-1. This transcriptional activation induces the expression of cytokines and intracellular adhesion molecules that facilitates the trafficking of neutrophils, macrophages and lymphocytes into the lung. Moreover, oxidants can promote chromatin remodeling that facilitates the expression of proinflammatory genes by stimulating the acetylation of histone residues in the nucleosome. This leads to conformational changes that enhance expression by rendering the gene more accessible to binding to transcriptional factors. Thus, the oxidant-antioxidant imbalance generated by cigarette smoke can promote inflammation which is critical to the functional decline that occurs in both asthma and COPD patients. Future research is needed to better define the effects of smoke-derived oxidants on lung inflammation and to determine the most efficacious strategies for generating significant antioxidant protection in the lung.

Emphysematous changes are caused by degradation of type III collagen in transgenic mice expressing MMP-1

Disruption of the extracellular matrix is believed to play an important role in the pathogenesis of emphysema. Prior studies have demonstrated that transgenic mice expressing the human tissue collagenase, matrix metalloproteinase 1 (MMP-1), develop emphysema. MMP-1 is a protease with substrate specificity for fibrillar collagen. Type I and III collagens, which are the most abundant proteins within the lungs, are the primary substrates for MMP-1. To assess if type I collagen was indeed the site of action for MMP-1 in these transgenic mice, hybrid mice were generated by crossing the MMP-1 transgenic mice with mice that had degradation-resistant type I collagen. The hybrid mice demonstrated an identical emphysematous phenotype as the MMP-1 transgenic mice, indicating that the degradation of type I collagen was not essential to the development of emphysema in these mice. Immunohistochemical studies in control mice demonstrated that collagen fibers in the alveolar walls and ducts of the normal mouse lungs consist mainly of type III collagen. In the transgenic and hybrid mice, the emphysematous changes, which developed, were associated with a marked decrease in type III collagen in these alveolar structures. These results indicate that MMP-1 generated the emphysematous phenotype via the degradative effect on type III collagen, which is a vital structural element of the alveolar walls. This is the first study to show that a matrix metalloproteinase may cause emphysema via its effects on a specific collagen subtype. As such, it should provide important insight into the mechanisms of this disease in humans.

The role of collagenase in emphysema

The extracellular matrix is essential for the integrity of the lung and when disrupted can lead to the architectural changes seen in emphysema. The etiology of emphysema is believed to be due to an imbalance in the proteases and antiproteases within the lung. Studies have focused on elastolytic enzymes as the primary agents in disease pathogenesis, however, recent data suggest that collagenases may also be involved in the destruction of lung tissue in emphysema. It is hoped that this expanded understanding of the pathophysiology of emphysema will lead to improved therapy in the treatment of the disease.