Inhibition of IFN-gamma-dependent antiviral airway epithelial defense by cigarette smoke

MAP2K1 dampens cigarette smoke-induced inflammation via suppression of type I interferon pathway activation

Chronic obstructive pulmonary disease (COPD), comprised of chronic bronchitis and emphysema, is a leading cause of morbidity and mortality worldwide. Mitogen-activated protein 2 kinase (MAP2K) pathway activation is present in COPD lung tissue and a genetic polymorphism in Map2k1 associates with FEV1 decline in COPD, suggesting it may contribute to disease pathogenesis. To test the functional contribution of Map2k1 in cigarette smoke (CS)-induced lung inflammation, we used a short-term CS exposure model in mice deficient in myeloid Map2k1 (LysmCre+Mek1fl) and wild-type mice (Mek1fl). Mice deficient in myeloid Map2k1 had enhanced CS-induced lung inflammation characterized by increased neutrophil recruitment, vascular leak, augmented expression of elastolytic matrix metalloproteinases, and increased type I interferon-stimulated gene expression. The augmented neutrophilic inflammatory response could be abrogated by IFNAR1 blockade. These findings indicate that myeloid Map2k1 regulates the immune response to CS via inhibition of the type I interferon pathway. Overall, these results suggest that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation and its expression is protective.NEW & NOTEWORTHY Activation of the mitogen-activated protein kinases (MAPK)-ERK1/2 pathway is present in COPD lung tissue compared with healthy lungs. Our study using mice deficient in myeloid Map2k1 reveals that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation via suppression of type I interferon responses, and its expression is protective.

Molecular Mechanisms of N-Acetylcysteine in RSV Infections and Air Pollution-Induced Alterations: A Scoping Review

N-acetylcysteine (NAC) is a mucolytic agent with antioxidant and anti-inflammatory properties. The respiratory syncytial virus (RSV) is one of the most important etiological factors of lower respiratory tract infections, and exposure to air pollution appears to be additionally associated with higher RSV incidence and disease severity. We aimed to systematically review the existing literature to determine which molecular mechanisms mediate the effects of NAC in an RSV infection and air pollution, and to identify the knowledge gaps in this field. A search for original studies was carried out in three databases and a calibrated extraction grid was used to extract data on the NAC treatment (dose, timing), the air pollutant type, and the most significant mechanisms. We identified only 28 studies conducted in human cellular models (n = 18), animal models (n = 7), and mixed models (n = 3). NAC treatment improves the barrier function of the epithelium damaged by RSV and air pollution, and reduces the epithelial permeability, protecting against viral entry. NAC may also block RSV-activated phosphorylation of the epidermal growth factor receptor (EGFR), which promotes endocytosis and facilitates cell entry. EGFR also enhances the release of a mucin gene, MUC5AC, which increases mucus viscosity and causes goblet cell metaplasia; the effects are abrogated by NAC. NAC blocks virus release from the infected cells, attenuates the cigarette smoke-induced shift from necrosis to apoptosis, and reverses the block in IFN-γ-induced antiviral gene expression caused by the inhibited Stat1 phosphorylation. Increased synthesis of pro-inflammatory cytokines and chemokines is induced by both RSV and air pollutants and is mediated by the nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways that are activated in response to oxidative stress. MCP-1 (monocyte chemoattractant protein-1) and RANTES (regulated upon activation, expressed and secreted by normal T cells) partially mediate airway hyperresponsiveness (AHR), and therapeutic (but not preventive) NAC administration reduces the inflammatory response and has been shown to reduce ozone-induced AHR. Oxidative stress-induced DNA damage and cellular senescence, observed during RSV infection and exposure to air pollution, can be partially reversed by NAC administration, while data on the emphysema formation are disputed. The review identified potential common molecular mechanisms of interest that are affected by NAC and may alleviate both the RSV infection and the effects of air pollution. Data are limited and gaps in knowledge include the optimal timing or dosage of NAC administration, therefore future studies should clarify these uncertainties and verify its practical use.

Cytokines and Regulating Epithelial Cell Division

Physiologically, cytokines play an extremely important role in maintaining cellular and subcellular homeostasis, as they interact almost with every cell in the organism. Therefore, cytokines play a significantly critical role in the field of pathogenic pharmacological therapy of different types of pathologies. Cytokine is a large family containing many subfamilies and can be evaluated into groups according to their action on epithelial cell proliferation; stimulatory include transforming growth factor-α (TGF-α), Interlukine-22 (IL-22), IL-13, IL-6, IL-1RA and IL-17 and inhibitory include IL-1α, interferon type I (IFN type I), and TGF-β. The balance between stimulatory and inhibitory cytokines is essential for maintaining normal epithelial cell turnover and tissue homeostasis. Dysregulation of cytokine production can contribute to various pathological conditions, including inflammatory disorders, tissue damage, and cancer. Several cytokines have shown the ability to affect programmed cell death (apoptosis) and the capability to suppress non-purpose cell proliferation. Clinically, understanding the role of cytokines' role in epithelial tissue is crucial for evaluating a novel therapeutic target that can be of use as a new tactic in the management of carcinomas and tissue healing capacity. The review provides a comprehensive and up-to-date synthesis of current knowledge regarding the multifaceted effects of cytokines on epithelial cell proliferation, with a particular emphasis on the intestinal epithelium. Also, the paper will highlight the diverse signaling pathways activated by cytokines and their downstream consequences on epithelial cell division. It will also explore the potential therapeutic implications of targeting cytokine- epithelial cell interactions in the context of various diseases.

Lactobacillus rhamnosus Restores Antiviral Signaling and Attenuates Cytokines Secretion from Human Bronchial Epithelial Cells Exposed to Cigarette Smoke and Infected with SARS-CoV-2

Individuals with chronic obstructive pulmonary disease (COPD) are more susceptible to exacerbation crisis triggered by secondary lung infections due to the dysfunction of antiviral signaling, principally via suppression of IFN-γ. Although the probiotic is known for controlling pulmonary inflammation in COPD, the influence of the Lactobacillus rhamnosus (Lr) on antiviral signaling in bronchial epithelium exposed to cigarette smoke extract (CSE) and viruses, remains unknown. Thus, the present study investigated the Lr effect on the antiviral signaling and the secretion of inflammatory mediators from bronchial epithelial cells (16HBE cells) exposed to CSE and SARS-CoV-2. The 16HBE cells were cultured, treated with Lr, stimulated with CSE, and infected with SARS-CoV-2. The cellular viability was evaluated using the MTT assay and cytotoxicity measured by lactate dehydrogenase (LDH) activity. The viral load, TLR2, TLR3, TLR4, TLR7, TLR8, MAVS, MyD88, and TRIF were quantified using specific PCR. The pro-inflammatory mediators were measured by a multiplex biometric immunoassay, and angiotensin converting enzyme 2 (ACE2) activity, NF-κB, RIG-I, MAD5, and IRF3 were measured using specific ELISA kits. Lr decreased viral load, ACE2, pro-inflammatory mediators, TLR2, TLR4, NF-κB, TLR3, TLR7, and TLR8 as well as TRIF and MyD88 expression in CSE and SARS-CoV-2 -exposed 16HBE cells. Otherwise, RIG-I, MAD5, IRF3, IFN-γ, and the MAVS expression were restored in 16HBE cells exposed to CSE and SARS-CoV-2 and treated with Lr. Lr induces antiviral signaling associated to IFN-γ secreting viral sensors and attenuates cytokine storm associated to NF-κB in bronchial epithelial cells, supporting its emerging role in prevention of COPD exacerbation.

TLR7 promotes smoke-induced experimental lung damage through the activity of mast cell tryptase

Toll-like receptor 7 (TLR7) is known for eliciting immunity against single-stranded RNA viruses, and is increased in both human and cigarette smoke (CS)-induced, experimental chronic obstructive pulmonary disease (COPD). Here we show that the severity of CS-induced emphysema and COPD is reduced in TLR7-deficient mice, while inhalation of imiquimod, a TLR7-agonist, induces emphysema without CS exposure. This imiquimod-induced emphysema is reduced in mice deficient in mast cell protease-6, or when wild-type mice are treated with the mast cell stabilizer, cromolyn. Furthermore, therapeutic treatment with anti-TLR7 monoclonal antibody suppresses CS-induced emphysema, experimental COPD and accumulation of pulmonary mast cells in mice. Lastly, TLR7 mRNA is increased in pre-existing datasets from patients with COPD, while TLR7+ mast cells are increased in COPD lungs and associated with severity of COPD. Our results thus support roles for TLR7 in mediating emphysema and COPD through mast cell activity, and may implicate TLR7 as a potential therapeutic target.

Antiviral CD8+ T-cell immune responses are impaired by cigarette smoke and in COPD

BACKGROUND

Virus infections drive COPD exacerbations and progression. Antiviral immunity centres on the activation of virus-specific CD8+ T-cells by viral epitopes presented on major histocompatibility complex (MHC) class I molecules of infected cells. These epitopes are generated by the immunoproteasome, a specialised intracellular protein degradation machine, which is induced by antiviral cytokines in infected cells.

METHODS

We analysed the effects of cigarette smoke on cytokine- and virus-mediated induction of the immunoproteasome in vitro, ex vivo and in vivo using RNA and Western blot analyses. CD8+ T-cell activation was determined in co-culture assays with cigarette smoke-exposed influenza A virus (IAV)-infected cells. Mass-spectrometry-based analysis of MHC class I-bound peptides uncovered the effects of cigarette smoke on inflammatory antigen presentation in lung cells. IAV-specific CD8+ T-cell numbers were determined in patients' peripheral blood using tetramer technology.

RESULTS

Cigarette smoke impaired the induction of the immunoproteasome by cytokine signalling and viral infection in lung cells in vitro, ex vivo and in vivo. In addition, cigarette smoke altered the peptide repertoire of antigens presented on MHC class I molecules under inflammatory conditions. Importantly, MHC class I-mediated activation of IAV-specific CD8+ T-cells was dampened by cigarette smoke. COPD patients exhibited reduced numbers of circulating IAV-specific CD8+ T-cells compared to healthy controls and asthmatics.

CONCLUSION

Our data indicate that cigarette smoke interferes with MHC class I antigen generation and presentation and thereby contributes to impaired activation of CD8+ T-cells upon virus infection. This adds important mechanistic insight on how cigarette smoke mediates increased susceptibility of smokers and COPD patients to viral infections.

Smoking is a Factor in Discordance Between QuantiFERONTB Gold Assay and Tuberculosis Etiology: Especially in Older Patients

Purpose

Exploring whether smoking is an influencing factor for the inconsistency between QuantiFERONTB Gold assay (QFT-GIT) and tuberculosis etiology.

Patients and Methods

The clinical data of patients who were confirmed positive for Mycobacterium tuberculosis (MTB) after undergoing QFT-GIT testing from September 2017 to August 2021 were retrospectively analyzed. Chi-square and rank-sum tests were used to compare the differences in characteristics between smokers and non-smokers. Logistic regression was used to adjust for confounding factors affecting smoking. Propensity score matching (PSM) was used to verify the above conclusions again.

Results

Positive results of tuberculosis etiology were adopted as the standard, the incidence of inconsistent results between QFT-GIT and tuberculosis etiology was 8.90% (108/1213), of which the false negative rate was 6.27% (76/1213) and the indeterminate rate was 2.64% (32/1213). In the overall population, the smokers had a lower level of basal IFN-γ (Z=-2.079, P=0.038). Among 382 elderly (≥65 years old) patients, the smokers had lower levels of antigen-stimulated IFN-γ (Z=-2.838, P=0.005). After performing BOX-COX transformation on all non-normally distributed data, logistic stepwise regression was used to adjust confounding factors. The results showed that smoking was an influencing factor for the inconsistency between QFT-GIT and tuberculosis etiology results (OR=1.69, P=0.020). Using PSM for 1:2 matching, the results showed that smoking was still an independent risk factor for the inconsistent results of QFT-GIT and tuberculosis etiology (OR= 1.95, P=0.019). Age-stratified analysis showed that smoking was an independent risk factor in discordance between QFT-GIT and tuberculosis etiology in patients aged ≥65 years (OR=2.40, P=0.005), but not in patients aged <65 years (P > 0.05).

Conclusion

Smoking can reduce the body's IFN-γ release ability, and smoking (especially the elderly) is an influencing factor for the inconsistency between QFT-GIT and tuberculosis etiological results.

Coinfection with influenza virus and non-typeable Haemophilus influenzae aggregates inflammatory lung injury and alters gut microbiota in COPD mice

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is associated with high mortality rates. Viral and bacterial coinfection is the primary cause of AECOPD. How coinfection with these microbes influences host inflammatory response and the gut microbiota composition is not entirely understood.

Methods

We developed a mouse model of AECOPD by cigarette smoke exposure and sequential infection with influenza H1N1 virus and non-typeable Haemophilus influenzae (NTHi). Viral and bacterial titer was determined using MDCK cells and chocolate agar plates, respectively. The levels of cytokines, adhesion molecules, and inflammatory cells in the lungs were measured using Bio-Plex and flow cytometry assays. Gut microbiota was analyzed using 16S rRNA gene sequencing. Correlations between cytokines and gut microbiota were determined using Spearman’s rank correlation coefficient test.

Results

Coinfection with H1N1 and NTHi resulted in more severe lung injury, higher mortality, declined lung function in COPD mice. H1N1 enhanced NTHi growth in the lungs, but NTHi had no effect on H1N1. In addition, coinfection increased the levels of cytokines and adhesion molecules, as well as immune cells including total and M1 macrophages, neutrophils, monocytes, NK cells, and CD4 + T cells. In contrast, alveolar macrophages were depleted. Furthermore, coinfection caused a decline in the diversity of gut bacteria. Muribaculaceae, Lactobacillus, Akkermansia, Lachnospiraceae, and Rikenella were further found to be negatively correlated with cytokine levels, whereas Bacteroides was positively correlated.

Conclusion

Coinfection with H1N1 and NTHi causes a deterioration in COPD mice due to increased lung inflammation, which is correlated with dysbiosis of the gut microbiota.

Cigarette smoke preferentially induces full length ACE2 expression in differentiated primary human airway cultures but does not alter the efficiency of cellular SARS-CoV-2 infection

Cigarette smoking has many serious negative health consequences. The relationship between smoking and SARS-CoV-2 infection is controversial, specifically whether smokers are at increased risk of infection. We investigated the impact of cigarette smoke on ACE2 isoform expression and SARS-CoV-2 infection in differentiated primary human bronchial epithelial cells at the air-liquid-interface (ALI). We assessed the expression of ACE2 in response to CSE and therapeutics reported to modulate ACE2. We exposed ALI cultures to cigarette smoke extract (CSE) and then infected them with SARS-CoV-2. We measured cellular infection using flow cytometry and whole-transwell immunofluorescence. We found that CSE increased expression of full-length ACE2 (flACE2) but did not alter the expression of a Type I-interferon sensitive truncated isoform (dACE2) that lacks the capacity to bind SARS-CoV-2. CSE did not have a significant impact on key mediators of the innate immune response. Importantly, we show that, despite the increase in flACE2, CSE did not alter airway cell infection after CSE exposure. We found that nicotine does not significantly alter flACE2 expression but that NRF2 agonists do lead to an increase in flACE2 expression. This increase was not associated with an increase in SARS-CoV-2 infection. Our results are consistent with the epidemiological data suggesting that current smokers do not have an excess of SARS-CoV-2 infection. but that those with chronic respiratory or cardiovascular disease are more vulnerable to severe COVID-19. They suggest that, in differentiated conducting airway cells, flACE2 expression levels may not limit airway SARS-CoV-2 infection.

Agarwood Oil Nanoemulsion Attenuates Cigarette Smoke-Induced Inflammation and Oxidative Stress Markers in BCi-NS1.1 Airway Epithelial Cells

Chronic obstructive pulmonary disease (COPD) is an irreversible inflammatory respiratory disease characterized by frequent exacerbations and symptoms such as cough and wheezing that lead to irreversible airway damage and hyperresponsiveness. The primary risk factor for COPD is chronic cigarette smoke exposure, which promotes oxidative stress and a general pro-inflammatory condition by stimulating pro-oxidant and pro-inflammatory pathways and, simultaneously, inactivating anti-inflammatory and antioxidant detoxification pathways. These events cause progressive damage resulting in impaired cell function and disease progression. Treatments available for COPD are generally aimed at reducing the symptoms of exacerbation. Failure to regulate oxidative stress and inflammation results in lung damage. In the quest for innovative treatment strategies, phytochemicals, and complex plant extracts such as agarwood essential oil are promising sources of molecules with antioxidant and anti-inflammatory activity. However, their clinical use is limited by issues such as low solubility and poor pharmacokinetic properties. These can be overcome by encapsulating the therapeutic molecules using advanced drug delivery systems such as polymeric nanosystems and nanoemulsions. In this study, agarwood oil nanoemulsion (agarwood-NE) was formulated and tested for its antioxidant and anti-inflammatory potential in cigarette smoke extract (CSE)-treated BCi-NS1.1 airway basal epithelial cells. The findings suggest successful counteractivity of agarwood-NE against CSE-mediated pro-inflammatory effects by reducing the expression of the pro-inflammatory cytokines IL-1α, IL-1β, IL-8, and GDF-15. In addition, agarwood-NE induced the expression of the anti-inflammatory mediators IL-10, IL-18BP, TFF3, GH, VDBP, relaxin-2, IFN-γ, and PDGF. Furthermore, agarwood-NE also induced the expression of antioxidant genes such as GCLC and GSTP1, simultaneously activating the PI3K pro-survival signalling pathway. This study provides proof of the dual anti-inflammatory and antioxidant activity of agarwood-NE, highlighting its enormous potential for COPD treatment.

Host, technical, and environmental factors affecting QuantiFERON-TB Gold In-Tube performance in children below 5 years of age

Interferon-gamma release assays performance can be impaired by host-related, technical and environmental factors, but data in young children are limited. We performed a cross-sectional study of children < 5 years-of-age at risk of tuberculosis (TB), using QuantiFERON-TB Gold In-Tube (QFT-GIT) assays. The impact of the following was evaluated: (i) host-related [age; hematological parameters; erythrocyte sedimentation rate (ESR); C-reactive protein (CRP); and tobacco smoke exposure (TSE) based on serum cotinine concentrations], (ii) technical (pre-analytical delay) and (iii) environmental factors (annual season; monthly temperatures). Of 204 children, 35 (17.2%) were diagnosed with latent TB infection or TB disease. QFT-GIT results were indeterminate in 14 (6.9%) patients. In multivariate analysis, younger age and higher ESR were associated with lower positive control responses (beta: 0.247, p = 0.002 and - 0.204, p = 0.007, respectively), and increasing age was associated with lower rates of indeterminate QFT-GIT results [OR (95% CI) 0.948 (0.903-0.996) per month, p = 0.035]. In children with positive QFT-GIT results, average monthly temperatures correlated with antigen responses (r = 0.453, p = 0.020); also, antigen responses were lower in winter than in other seasons (p = 0.027). Serum cotinine concentrations determined in a subgroup of patients (n = 41) indicated TSE in 36 (88%), positive control responses being lower in children with TSE (p = 0.034). In children < 5 years-of-age, young age, elevated ESR, temperature, annual season and TSE can affect the performance of QFT-GIT assays.

Molecular Mechanisms of RSV and Air Pollution Interaction: A Scoping Review

RSV is one of the major infectious agents in paediatrics, and its relationship with air pollution is frequently observed. However, the molecular basis of this interaction is sparsely reported. We sought to systematically review the existing body of literature and identify the knowledge gaps to answer the question: which molecular mechanisms are implied in the air pollutants-RSV interaction? Online databases were searched for original studies published before August 2022 focusing on molecular mechanisms of the interaction. The studies were charted and a narrative synthesis was based upon three expected directions of influence: a facilitated viral entry, an altered viral replication, and an inappropriate host reaction. We identified 25 studies published between 1993 and 2020 (without a noticeable increase in the number of studies) that were performed in human (n = 12), animal (n = 10) or mixed (n = 3) models, and analysed mainly cigarette smoke (n = 11), particulate matter (n = 4), nanoparticles (n = 3), and carbon black (n = 2). The data on a damage to the epithelial barrier supports the hypothesis of facilitated viral entry; one study also reported accelerated viral entry upon an RSV conjugation to particulate matter. Air pollution may result in the predominance of necrosis over apoptosis, and, as an effect, an increased viral load was reported. Similarly, air pollution mitigates epithelium function with decreased IFN-γ and Clara cell secretory protein levels and decreased immune response. Immune response might also be diminished due to a decreased viral uptake by alveolar macrophages and a suppressed function of dendritic cells. On the other hand, an exuberant inflammatory response might be triggered by air pollution and provoke airway hyperresponsiveness (AHR), prolonged lung infiltration, and tissue remodeling, including a formation of emphysema. AHR is mediated mostly by increased IFN-γ and RANTES concentrations, while the risk of emphysema was related to the activation of the IL-17 → MCP-1 → MMP-9 → MMP-12 axis. There is a significant lack of evidence on the molecular basics of the RSV-air pollution interaction, which may present a serious problem with regards to future actions against air pollution effects. The major knowledge gaps concern air pollutants (mostly the influence of cigarette smoke was investigated), the mechanisms facilitating an acute infection or a worse disease course (since it might help plan short-term, especially non-pharmacological, interventions), and the mechanisms of an inadequate response to the infection (which may lead to a prolonged course of an acute infection and long-term sequelae). Thus far, the evidence is insufficient regarding the broadness and complexity of the interaction, and future studies should focus on common mechanisms stimulated by various air pollutants and a comparison of influence of the different contaminants at various concentrations.

Cigarette Smoke Extract Disturbs Mitochondria-Regulated Airway Epithelial Cell Responses to Pneumococci

Mitochondrial functionality is crucial for the execution of physiologic functions of metabolically active cells in the respiratory tract including airway epithelial cells (AECs). Cigarette smoke is known to impair mitochondrial function in AECs. However, the potential contribution of mitochondrial dysfunction in AECs to airway infection and airway epithelial barrier dysfunction is unknown. In this study, we used an in vitro model based on AECs exposed to cigarette smoke extract (CSE) followed by an infection with Streptococcus pneumoniae (Sp). The levels of oxidative stress as an indicator of mitochondrial stress were quantified upon CSE and Sp treatment. In addition, expression of proteins associated with mitophagy, mitochondrial content, and biogenesis as well as mitochondrial fission and fusion was quantified. Transcriptional AEC profiling was performed to identify the potential changes in innate immune pathways and correlate them with indices of mitochondrial function. We observed that CSE exposure substantially altered mitochondrial function in AECs by suppressing mitochondrial complex protein levels, reducing mitochondrial membrane potential and increasing mitochondrial stress and mitophagy. Moreover, CSE-induced mitochondrial dysfunction correlated with reduced enrichment of genes involved in apical junctions and innate immune responses to Sp, particularly type I interferon responses. Together, our results demonstrated that CSE-induced mitochondrial dysfunction may contribute to impaired innate immune responses to Sp.

Integrative genomic analysis reveals low T-cell infiltration as the primary feature of tobacco use in HPV-positive oropharyngeal cancer

Although tobacco use is an independent adverse prognostic feature in HPV(+) oropharyngeal squamous cell carcinoma (OPSCC), the biologic features associated with tobacco use have not been systematically investigated. We characterized genomic and immunologic features associated with tobacco use through whole exome sequencing, mRNA hybridization, and immunohistochemical staining in 47 HPV(+) OPSCC tumors. Low expression of transcripts in a T cell-inflamed gene expression profile (TGEP) was associated with tobacco use at diagnosis and lower overall and disease-free survival. Tobacco use was associated with an increased proportion of T > C substitutions and a lower proportion of expected mutational signatures, but not with increases in mutational burden or recurrent oncogenic mutations. Our findings suggest that rather than increased mutational burden, tobacco's primary and clinically relevant association in HPV(+) OPSCC is immunosuppression of the tumor immune microenvironment. Quantitative assays of T cell infiltration merit further study as prognostic markers in HPV(+) OPSCC.

Respiratory Viral and Bacterial Exacerbations of COPD—The Role of the Airway Epithelium

COPD is a leading cause of death worldwide, with acute exacerbations being a major contributor to disease morbidity and mortality. Indeed, exacerbations are associated with loss of lung function, and exacerbation frequency predicts poor prognosis. Respiratory infections are important triggers of acute exacerbations of COPD. This review examines the role of bacterial and viral infections, along with co-infections, in the pathogenesis of COPD exacerbations. Because the airway epithelium is the initial site of exposure both to cigarette smoke (or other pollutants) and to inhaled pathogens, we will focus on the role of airway epithelial cell responses in regulating the pathophysiology of exacerbations of COPD. This will include an examination of the interactions of cigarette smoke alone, and in combination with viral and bacterial exposures in modulating epithelial function and inflammatory and host defense pathways in the airways during COPD. Finally, we will briefly examine current and potential medication approaches to treat acute exacerbations of COPD triggered by respiratory infections.

Impact of inhaled pollutants on response to viral infection in controlled exposures

Air pollutants are a major source of increased risk of disease, hospitalization, morbidity, and mortality worldwide. The respiratory tract is a primary target of potential concurrent exposure to both inhaled pollutants and pathogens, including viruses. Although there are various associative studies linking adverse outcomes to co- or subsequent exposures to inhaled pollutants and viruses, knowledge about causal linkages and mechanisms by which pollutant exposure may alter human respiratory responses to viral infection is more limited. In this article, we review what is known about the impact of pollutant exposure on antiviral host defense responses and describe potential mechanisms by which pollutants can alter the viral infection cycle. This review focuses on evidence from human observational and controlled exposure, ex vivo, and in vitro studies. Overall, there are a myriad of points throughout the viral infection cycle that inhaled pollutants can alter to modulate appropriate host defense responses. These alterations may contribute to observed increases in rates of viral infection and associated morbidity and mortality in areas of the world with high ambient pollution levels or in people using tobacco products. Although the understanding of mechanisms of interaction is advancing through controlled in vivo and in vitro exposure models, more studies are needed because emerging infectious pathogens, such as severe acute respiratory syndrome coronavirus 2, present a significant threat to public health.

Smoking associates with increased BAFF and decreased interferon-γ levels in patients with systemic lupus erythematosus

Objective

In SLE, smoking increases the burden of cutaneous disease and organ damage, and leads to premature mortality. However, the effect of smoking on disease manifestations and cytokine levels of patients with SLE is unclear. This study compared characteristics of patients with SLE across smoking status, and determined the association of smoking with serum cytokine levels.

Method

A cross-sectional study of patients with SLE (n=99) during a research visit in which smoking status was ascertained. Smoking status was compared across classification criteria (American College of Rheumatology Classification Criteria for SLE (ACR97)), disease activity (SLE Disease Activity Index), autoantibody levels, accrued damage (Systemic Lupus International Collaborating Clinics/ACR Damage Index), and circulating concentrations of serum interferon-gamma (IFN-γ), interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-12, IL-17, B cell-activating factor (BAFF), tumour necrosis factor-alpha, transforming growth factor beta 1 (TGF-β1), macrophage inflammatory protein 1 alpha (MIP-1α), MIP-1β and monocyte chemoattractant protein 1. Linear regression models determined the association between smoking and cytokine levels, adjusting for age and sex, clinical characteristics (model 1), and anti-inflammatory (IL-4, IL-10 and TGF- β1) and regulatory (IL-1β) cytokines (model 2).

Results

Among patients with SLE (97.9% ANA+; mean 48.48 years old; 86.9% female; mean 10 years of disease duration), 35.4% (n=35 of 99) were smoking (an average of 7 cigarettes/day for 24 years). Smokers had increased odds of prevalent ACR97 malar rash (OR 3.40, 95% CI 1.23 to 9.34) and mucosal ulcers (OR 3.31, 95% CI 1.36 to 8.05). Smokers had more arthritis (OR 3.19, 95% CI 1.19 to 8.60), migraine (OR 2.82, 95% CI 1.07 to 7.44), Raynaud’s phenomenon (OR 5.15, 95% CI 1.95 to 13.56) and increased non-steroidal anti-inflammatory drug use (OR 6.88, 95% CI 1.99 to 23.72). Smoking associated with 27% increased BAFF levels (95% CI 6% to 48%) and 42% decreased IFN-γ levels (95% CI −79% to −5%) in model 2.

Conclusion

In patients with SLE, smoking independently associated with increased BAFF and decreased IFN-γ levels, and an increased frequency of arthritis, migraine and Raynaud’s phenomenon. Smoking cessation is advisable to reduce systemic inflammation, reduce disease activity and improve host defence.

Viral respiratory infections and air pollutants

Air pollution is a public health issue of global importance and a risk factor for developing cardiorespiratory diseases. These contaminants induce reactive oxygen species (ROS) and increased pro-inflammatory cytokines such as IL-1β, IL-6, and IL-8, triggering the inflammatory response that alters cell and tissue homeostasis and facilitates the development of diseases. The effects of air pollutants such as ozone, particulate matter (PM10, PM2.5, and PM0.1), and indoor air pollutants on respiratory health have been widely reported. For instance, epidemiological and experimental studies have shown associations between hospital admissions for individual diseases and increased air pollutant levels. This review describes the association and relationships between exposure to air pollutants and respiratory viral infections, especially those caused by the respiratory syncytial virus and influenza virus. The evidence suggests that exposure to air contaminants induces inflammatory states, modulates the immune system, and increases molecules' expression that favors respiratory viruses' pathogenesis and affects the respiratory system. However, the mechanisms underlying these interactions have not yet been fully elucidated, so it is necessary to develop new studies to obtain information that will allow health and policy decisions to be made for the adequate control of respiratory infections, especially in the most vulnerable population, during periods of maximum air pollution.

Immune Status and Mortality in Smokers, Ex-smokers, and Never-Smokers: The Ludwigshafen Risk and Cardiovascular Health Study

INTRODUCTION

Elevated leukocyte counts are associated with cardiovascular disease. Smoking induces inflammation and alters levels of leukocyte subtypes.

AIMS AND METHODS

Our aim was to investigate the effect of smoking on circulating immune cells and their association with mortality. Lymphocyte subtypes were identified by flow cytometry of fluorescent-labeled cells. We analyzed the association of leukocytes with mortality using Cox regression and assessed their effect on risk prediction based on principle components (PCs) using area under the receiver operating characteristic curve and net-reclassification in 2173 participants from the Ludwigshafen Risk and Cardiovascular Health Study, a prospective case-control study in patients who underwent coronary angiography.

RESULTS

The numbers of T cells, monocytes, and neutrophils were higher and natural killer cells were lower in smokers compared with never-smokers. In never-smokers, lymphocyte counts were inversely associated with mortality while a positive association was observed for neutrophils. The neutrophil-to-lymphocyte ratio (NLR) had the strongest association in never-smokers with a hazard ratio (95% confidence interval) of 1.43 (1.26-1.61). No associations were found in smokers. Adding the first five PCs or the NLR to a risk prediction model based on conventional risk factors did not improve risk prediction in smokers, but significantly increased the area under the curve from 0.777 to 0.801 and 0.791, respectively, in never-smokers.

CONCLUSIONS

Lymphocyte counts were inversely associated with mortality in never-smokers but not in active smokers. Markers of innate immunity, namely total neutrophils and CD11b+/CD18+ and CD31+/CD40- granulocytes, were directly associated with mortality. Adding markers of immune function like PCs or the NLR to basic risk models improved risk prediction in never-smokers only.

IMPLICATIONS

Total leukocyte counts were higher in active smokers as compared to never-smokers due to elevated counts of neutrophils and monocytes but declined in ex-smokers with increasing time since quitting. In the never-smokers but not in smokers, lymphocyte counts were inversely associated with mortality while there was a direct association with neutrophils, even after adjustment for conventional cardiovascular risk factors. Adding markers of immune function to basic risk models improved risk prediction in never-smokers only. Our data indicate that smoking status has an important impact on the ability of leukocyte counts to predict long-term cardiovascular outcomes.

Vaping, SARS-CoV-2, and Multisystem Inflammatory Syndrome: A Perfect Storm

The use of electronic cigarettes (e-cigarettes) and vaping among adolescents has risen exponentially in the last decade. E-cigarette flavors has driven adolescents to use these convenient, USB-like devices, designed to create a desired social image, while being seemingly unaware of the serious health consequences of their behavior. Vaping impacts protective pulmonary barriers by attenuating the mucociliary clearance and by increasing peribronchial inflammation and fibrosis. The recent SARS-CoV-2 (COVID-19) pandemic has been characterized by a plethora of unusual disease presentations. Among them, a unique presentation seen exclusively in children and adolescents was multisystem inflammatory syndrome (MIS-C). Seventy percent of adolescents who had MIS-C also had acute respiratory distress syndrome (ARDS), and we speculate that there may exist common denominator that links MIS-C and adolescents: the use of e-cigarettes. The virus targets the angiotensin converting receptor (ACE receptor), and studies have shown nicotine-based e-cigarettes or vaping cause oxidative stress and resulting in the upregulation of ACE2, which might worsen ARDS in MIS-C. Our mini-review highlights that adolescents using e-cigarette have alterations in their pulmonary defenses against SARS-CoV-2: an upregulation of the ACE2 receptors, the primary target of SARS-CoV-2. Their compromised immune system makes them more uniquely vulnerable to Covid-19 related MIS-C, increasing their risk for ARDS and related morbidities. Currently, studies have shown an association between MIS-C and vaping, we speculate that adolescents who vape/smoke might be especially vulnerable to serious respiratory symptoms if they develop a hyper-inflammatory state MIS-C.

Transcriptomic and barrier responses of human airway epithelial cells exposed to cannabis smoke

Globally, many jurisdictions are legalizing or decriminalizing cannabis, creating a potential public health issue that would benefit from experimental evidence to inform policy, government regulations, and user practices. Tobacco smoke exposure science has created a body of knowledge that demonstrates the conclusive negative impacts on respiratory health; similar knowledge remains to be established for cannabis. To address this unmet need, we performed in vitro functional and transcriptomic experiments with a human airway epithelial cell line (Calu-3) exposed to cannabis smoke, with tobacco smoke as a positive control. Demonstrating the validity of our in vitro model, tobacco smoke induced gene expression profiles that were significantly correlated with gene expression profiles from published tobacco exposure datasets from bronchial brushings and primary human airway epithelial cell cultures. Applying our model to cannabis smoke, we demonstrate that cannabis smoke induced functional and transcriptional responses that overlapped with tobacco smoke. Ontology and pathway analysis revealed that cannabis smoke induced DNA replication and oxidative stress responses. Functionally, cannabis smoke impaired epithelial cell barrier function, antiviral responses, and increased inflammatory mediator production. Our study reveals striking similarities between cannabis and tobacco smoke exposure on impairing barrier function, suppressing antiviral pathways, potentiating of pro-inflammatory mediators, and inducing oncogenic and oxidative stress gene expression signatures. Collectively our data suggest that cannabis smoke exposure is not innocuous and may possess many of the deleterious properties of tobacco smoke, warranting additional studies to support public policy, government regulations, and user practices.

Risk factors for frontal fibrosing alopecia: A case-control study in a multiracial population

BACKGROUND

Frontal fibrosing alopecia (FFA) is a chronic cicatricial alopecia with unknown etiology and a worldwide rising incidence.

OBJECTIVE

The objective of this study was to evaluate the association of FFA with demographic and exposure factors in a Brazilian multiracial population.

METHODS

A multicenter case-control study was conducted in 11 referral centers throughout Brazil. The study was a case-control study that prospectively recruited 902 participants (451 patients with FFA and 451 sex-matched control individuals). Study participants completed a thorough questionnaire comprising variables grouped as baseline demographics, environmental exposure, diet, hormonal factors, allergies, and hair and skin care.

RESULTS

When adjusted by sex, age, menopause, and skin color, FFA was associated with hair straightening with formalin (odds ratio [OR], 3.18), use of ordinary (nondermatologic) facial soap (OR, 2.09) and facial moisturizer (OR, 1.99), thyroid disorders (OR, 1.69), and rosacea (OR, 2.08). Smokers (OR, 0.33) and users of antiresidue/clarifying shampoo (OR, 0.35) presented a negative association with FFA. There was no association with the use of sunscreen.

LIMITATIONS

Recall bias.

CONCLUSIONS

The association with moisturizers, ordinary facial soap, and hair straightening with formalin and the negative association with antiresidue/clarifying shampoo reinforce the possibility of an exogenous particle triggering FFA.

Association of Genetic Variants of NLRP4 with Exacerbation of Asthma: The Effect of Smoking

Asthma exacerbation is induced by the interaction of genes and environmental factors such as cigarette smoke. NLRP4 counteracts the activity of the inflammasome, which is responsible for asthma exacerbation. In this study, we analyzed the association of single-nucleotide polymorphisms of NLRP4 with the annual rate of exacerbation and evaluated the additive effect of smoking in 1454 asthmatics. Asthmatics possessing the minor allele of rs1696718G > A had more frequent exacerbation episodes than those homozygous for the common allele (0.59 vs. 0.36/year) and the association was present only in current and ex-smokers. There was a significant interaction between the amount smoked and rs16986718 genotypes (p = 0.014) and a positive correlation between the number of annual exacerbation episodes and amount smoked only in rs16986718G > A AA homozygotes. The prevalence of frequent exacerbators (≥2 exacerbation episodes/year) was 2.5 times higher in rs16986718G > A minor allele homozygotes than in common allele homozygotes (12.0% vs. 5.9%). Furthermore, the prevalence was 6 times higher in rs16986718G > A minor allele homozygotes who were current and ex-smokers than in nonsmokers (25.6% vs. 4.1%). The minor allele of rs16986718G > A in NLRP4 may be a genetic marker that predicts asthma exacerbation in adult asthmatics who smoke.

Cigarette smoke and chewing tobacco alter expression of different sets of miRNAs in oral keratinocytes

Carcinogenic effect of tobacco in oral cancer is through chewing and/or smoking. Significant differences exist in development of oral cancer between tobacco users and non-users. However, molecular alterations induced by different forms of tobacco are yet to be fully elucidated. We developed cellular models of chronic exposure to chewing tobacco and cigarette smoke using immortalized oral keratinocytes. Chronic exposure to tobacco resulted in increased cell scattering and invasiveness in immortalized oral keratinocytes. miRNA sequencing using Illumina HiSeq 2500 resulted in the identification of 10 significantly dysregulated miRNAs (4 fold; p ≤ 0.05) in chewing tobacco treated cells and 6 in cigarette smoke exposed cells. We integrated this data with global proteomic data and identified 36 protein targets that showed inverse expression pattern in chewing tobacco treated cells and 16 protein targets that showed inverse expression in smoke exposed cells. In addition, we identified 6 novel miRNAs in chewing tobacco treated cells and 18 novel miRNAs in smoke exposed cells. Integrative analysis of dysregulated miRNAs and their targets indicates that signaling mechanisms leading to oncogenic transformation are distinct between both forms of tobacco. Our study demonstrates alterations in miRNA expression in oral cells in response to two frequently used forms of tobacco.

Distinctive Regulatory T Cells and Altered Cytokine Profile Locally in the Airways of Young Smokers with Normal Lung Function

Smoking influences the immune system in different ways and, hypothetically, effects on pulmonary effector and regulatory T cells emerge as potentially detrimental. Therefore, we characterized the frequencies and characteristics of CD4+ and CD8+ T cell subsets in the blood and lungs of young tobacco smokers. Bronchoalveolar lavage (BAL) and peripheral blood were obtained from healthy moderate smokers (n = 18; 2–24 pack-years) and never-smokers (n = 15), all with normal lung function. Cells were stimulated ex vivo and key intracellular cytokines (IFNγ, IL-17, IL-10 and TNFα) and transcription factors (Foxp3, T-bet and Helios) were analyzed using flow cytometry. Our results indicate that smoking is associated with a decline in lung IL-17+ CD4+ T cells, increased IFNγ+ CD8+ T cells and these alterations relate to the history of daily cigarette consumption. There is an increased fraction of Foxp3+ regulatory T cells being Helios- in the lungs of smokers. Cytokine production is mainly confined to the Helios- T cells, both in regulatory and effector subsets. Moreover, we detected a decline of Helios+Foxp3- postulated regulatory CD8+ T cells in smokers. These alterations in the immune system are likely to increase risk for infection and may have implications for autoimmune processes initiated in the lungs among tobacco smokers.

Cigarette smoking represses expression of cytokine IL-12 and its regulator miR-21-An observational study in patients with coronary artery disease

RATIONALE

The heterodimer IL-12 is an inducer of Th1 responses and stimulates INFƴ production. Micro-RNA-21 (miR-21) is described as a key regulator of the pro-inflammatory response and has IL-12p35 mRNA as one of its main targets. The IL-12p40 1188A/C genetic variant located in 3'untranslated region (UTR), thus environmentally exposed, has further been reported to modify IL-12 levels. We have previously reported on the lowering effect of cigarette smoke on circulating IL-12 in patients with coronary artery disease (CAD).

OBJECTIVES

To explore if cigarette smoking affects IL-12p35, IL-12p40, INFƴ and miR-21 gene-expression and further modulates any effect of the IL-12p40 polymorphism on circulating IL-12 levels.

METHODS AND RESULTS

The IL-12p40 1188A/C polymorphism was analyzed in 1001 stable CAD patients, of which 330 subjects were included for IL-12p35, IL-12p40 and INFƴ gene-expression analyses in circulating leukocytes and 200 were further selected for plasma miR-21 analysis. Smoking associated with lower expression of miR-21 and its target IL-12p35 mRNA (adjusted p<0.05, both) whereas the influence on INFƴ expression tended to be high-dose reliant (p = 0.057). The IL-12p40 CC genotype associated with elevated circulating IL-12 levels, however, when stratified according to smoking, only in the non-smoking group (adjusted p < 0.05). Although the markers were mainly downregulated in current smokers, their inter-correlations were potentiated.

CONCLUSION

Smoking associated with reduced miR-21 gene-repression and the results can therefore not explain the previously observed reduction in circulating IL-12. Smoking attenuated the IL-12 pro-inflammatory axis in which the investigated IL-12p40 genetic variant may have different clinical impact in smokers vs non-smokers.

Prenatal Versus Postnatal Tobacco Smoke Exposure and Intensive Care Use in Children Hospitalized With Bronchiolitis

OBJECTIVE

Among children hospitalized with bronchiolitis, we examined the associations between in utero exposure to maternal cigarette smoking, postnatal tobacco smoke exposure, and risk of admission to the intensive care unit (ICU).

METHODS

We performed a 16-center, prospective cohort study of hospitalized children aged <2 years with a physician admitting diagnosis of bronchiolitis. For 3 consecutive years, from November 1, 2007 until March 31, 2010, site teams collected data from participating families, including information about prenatal maternal smoking and postnatal tobacco exposure. Analyses used chi-square, Fisher's exact, and Kruskal-Wallis tests and multivariable logistic regression.

RESULTS

Among 2207 enrolled children, 216 (10%) had isolated in utero exposure to maternal smoking, 168 (8%) had isolated postnatal tobacco exposure, and 115 (5%) experienced both. Adjusting for age, sex, race, birth weight, viral etiology, apnea, initial severity of retractions, initial oxygen saturation, oral intake, and postnatal tobacco exposure, children with in utero exposure to maternal smoking had greater odds of being admitted to the ICU (adjusted odds ratio [aOR] 1.51, 95% confidence interval [CI] 1.14-2.00). Among children with in utero exposure to maternal smoking, those with additional postnatal tobacco exposure had a greater likelihood of ICU admission (aOR 1.95, 95% CI 1.13-3.37) compared to children without postnatal tobacco smoke exposure (aOR 1.47, 95% CI 1.05-2.04).

CONCLUSIONS

Maternal cigarette smoking during pregnancy puts children hospitalized with bronchiolitis at significantly higher risk of intensive care use. Postnatal tobacco smoke exposure may exacerbate this risk. Health care providers should incorporate this information into counseling messages.

Heavy Cigarette Smokers in a Chinese Population Display a Compromised Permeability Barrier

Cigarette smoking is associated with various cutaneous disorders with defective permeability. Yet, whether cigarette smoking influences epidermal permeability barrier function is largely unknown. Here, we measured skin biophysical properties, including permeability barrier homeostasis, stratum corneum (SC) integrity, SC hydration, skin surface pH, and skin melanin/erythema index, in cigarette smokers. A total of 99 male volunteers were enrolled in this study. Smokers were categorized as light-to-moderate (<20 cigarettes/day) or heavy smokers (≥20 cigarettes/day). An MPA5 was used to measure SC hydration and skin melanin/erythema index on the dorsal hand, forehead, and cheek. Basal transepidermal water loss (TEWL) and barrier recovery rates were assessed on the forearm. A Skin-pH-Meter pH900 was used to measure skin surface pH. Our results showed that heavy cigarette smokers exhibited delayed barrier recovery after acute abrogation (1.02% ± 13.06 versus 16.48% ± 6.07), and barrier recovery rates correlated negatively with the number of daily cigarettes consumption (p = 0.0087). Changes in biophysical parameters in cigarette smokers varied with body sites. In conclusion, heavy cigarette smokers display compromised permeability barrier homeostasis, which could contribute, in part, to the increased prevalence of certain cutaneous disorders characterized by defective permeability. Thus, improving epidermal permeability barrier should be considered for heavy cigarette smokers.

Impairment of Immunoproteasome Function by Cigarette Smoke and in Chronic Obstructive Pulmonary Disease

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) and in particular smokers are more susceptible to respiratory infections contributing to acute exacerbations of disease. The immunoproteasome is a specialized type of proteasome destined to improve major histocompatibility complex (MHC) class I-mediated antigen presentation for the resolution of intracellular infections.

OBJECTIVES

To characterize immunoproteasome function in COPD and its regulation by cigarette smoke.

METHODS

Immunoproteasome expression and activity were determined in bronchoalveolar lavage (BAL) and lungs of human donors and patients with COPD or idiopathic pulmonary fibrosis (IPF), as well as in cigarette smoke-exposed mice. Smoke-mediated alterations of immunoproteasome activity and MHC I surface expression were analyzed in human blood-derived macrophages. Immunoproteasome-specific MHC I antigen presentation was evaluated in spleen and lung immune cells that had been smoke-exposed in vitro or in vivo.

MEASUREMENTS AND MAIN RESULTS

Immunoproteasome and MHC I mRNA expression was reduced in BAL cells of patients with COPD and in isolated alveolar macrophages of patients with COPD or IPF. Exposure of immune cells to cigarette smoke extract in vitro reduced immunoproteasome activity and impaired immunoproteasome-specific MHC I antigen presentation. In vivo, acute cigarette smoke exposure dynamically regulated immunoproteasome function and MHC I antigen presentation in mouse BAL cells. End-stage COPD lungs showed markedly impaired immunoproteasome activities.

CONCLUSIONS

We here show that the activity of the immunoproteasome is impaired by cigarette smoke resulting in reduced MHC I antigen presentation. Regulation of immunoproteasome function by cigarette smoke may thus alter adaptive immune responses and add to prolonged infections and exacerbations in COPD and IPF.

NOD1 agonist iE-DAP reverses effects of cigarette smoke extract on NOD1 signal pathway in human oral mucosal epithelial cells

Smoking is a well-known risk factor for many systemic diseases and oral disorders. Smoking has been recognized to cause diminished defense, persistent inflammation and result in disease development. Nucleotide binding oligomerization domain 1 (NOD1) signal pathway plays a key role in innate immune and tissue homeostasis. Our recent studies confirmed that cigarette smoke extract (CSE) could inhibit NOD1 expression and affect expression levels of crucial molecules of NOD1 signaling in oral mucosal epithelial cells. In the present study, immortalized human oral mucosal epithelial (Leuk-1) cells were treated with CSE, iE-DAP (NOD1 agonist), CSE + iE-DAP, respectively. Western blotting analysis demonstrated that iE-DAP triggered NOD1 expression of leuk-1 cells in a dose-dependent manner. iE-DAP also reversed the suppressive effect of CSE on NOD1 expression and prevented the overactivation of RIP2 and P-NF-κB following CSE exposure. Real-time PCR and ELISA results confirmed that iE-DAP reversed CSE-mediated effects on the mRNA levels and releases of IL-6, IL-8, TNF-α and IFN-γ by Leuk-1 cells. Taken together, our results indicated that NOD1 activation with iE-DAP could reverse CSE-mediated effects on NOD1 signaling in human oral mucosal epithelial cells.

Targeting PI3K-p110α Suppresses Influenza Virus Infection in Chronic Obstructive Pulmonary Disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) and influenza virus infections are major global health issues. Patients with COPD are more susceptible to infection, which exacerbates their condition and increases morbidity and mortality. The mechanisms of increased susceptibility remain poorly understood, and current preventions and treatments have substantial limitations.

OBJECTIVES

To characterize the mechanisms of increased susceptibility to influenza virus infection in COPD and the potential for therapeutic targeting.

METHODS

We used a combination of primary bronchial epithelial cells (pBECs) from COPD and healthy control subjects, a mouse model of cigarette smoke-induced experimental COPD, and influenza infection. The role of the phosphoinositide-3-kinase (PI3K) pathway was characterized using molecular methods, and its potential for targeting assessed using inhibitors.

MEASUREMENTS AND MAIN RESULTS

COPD pBECs were susceptible to increased viral entry and replication. Infected mice with experimental COPD also had more severe infection (increased viral titer and pulmonary inflammation, and compromised lung function). These processes were associated with impaired antiviral immunity, reduced retinoic acid-inducible gene-I, and IFN/cytokine and chemokine responses. Increased PI3K-p110α levels and activity in COPD pBECs and/or mice were responsible for increased infection and reduced antiviral responses. Global PI3K, specific therapeutic p110α inhibitors, or exogenous IFN-β restored protective antiviral responses, suppressed infection, and improved lung function.

CONCLUSIONS

The increased susceptibility of individuals with COPD to influenza likely results from impaired antiviral responses, which are mediated by increased PI3K-p110α activity. This pathway may be targeted therapeutically in COPD, or in healthy individuals, during seasonal or pandemic outbreaks to prevent and/or treat influenza.

Regulation of immunoproteasome function in the lung

Impaired immune function contributes to the development of chronic obstructive pulmonary disease (COPD). Disease progression is further exacerbated by pathogen infections due to impaired immune responses. Elimination of infected cells is achieved by cytotoxic CD8⁺  T cells that are activated by MHC I-mediated presentation of pathogen-derived antigenic peptides. The immunoproteasome, a specialized form of the proteasome, improves generation of antigenic peptides for MHC I presentation thereby facilitating anti-viral immune responses. However, immunoproteasome function in the lung has not been investigated in detail yet. In this study, we comprehensively characterized the function of immunoproteasomes in the human and murine lung. Parenchymal cells of the lung express low constitutive levels of immunoproteasomes, while they are highly and specifically expressed in alveolar macrophages. Immunoproteasome expression is not altered in whole lung tissue of COPD patients. Novel activity-based probes and native gel analysis revealed that immunoproteasome activities are specifically and rapidly induced by IFNγ treatment in respiratory cells in vitro and by virus infection of the lung in mice. Our results suggest that the lung is potentially capable of mounting an immunoproteasome-mediated efficient adaptive immune response to intracellular infections.

Tobacco smoking increases the risk for death from pneumococcal pneumonia

BACKGROUND

Active smoking increases the risk of developing community-acquired pneumonia (CAP) and invasive pneumococcal disease, although its impact on mortality in pneumococcal CAP outcomes remains unclear. The aim of this study was to investigate the influence of current smoking status on pneumococcal CAP mortality.

METHODS

We performed a multicenter, prospective, observational cohort study in 4,288 hospitalized patients with CAP. The study group consisted of 892 patients with pneumococcal CAP: 204 current smokers (22.8%), 387 nonsmokers (43.4%), and 301 exsmokers (33.7%).

RESULTS

Mortality at 30 days was 3.9%: 4.9% in current smokers vs 4.3% in nonsmokers and 2.6% in exsmokers. Current smokers with CAP were younger (51 years vs 74 years), with more alcohol abuse and fewer cardiac, renal, and asthma diseases. Current smokers had lower CURB-65 (confusion, uremia, respiratory rate, BP, age ≥ 65 years) scores, although 40% had severe sepsis at diagnosis. Current smoking was an independent risk factor (OR, 5.0; 95% CI, 1.8-13.5; P = .001) for 30-day mortality of pneumococcal CAP after adjusting for age (OR, 1.06; P = .001), liver disease (OR, 4.5), sepsis (OR, 2.3), antibiotic adherence to guidelines, and first antibiotic dose given < 6 h. The independent risk effect of current smokers remained when compared only with nonsmokers (OR, 4.0; 95% CI, 1.3-12.6; P = .015) or to exsmokers (OR, 3.9; 95% CI, 1.09-4.95; P = .02).

CONCLUSIONS

Current smokers with pneumococcal CAP often develop severe sepsis and require hospitalization at a younger age, despite fewer comorbid conditions. Smoking increases the risk of 30-day mortality independently of tobacco-related comorbidity, age, and comorbid conditions. Current smokers should be actively targeted for preventive strategies.

Brief exposure to cigarette smoke impairs airway epithelial cell innate anti-viral defence

BACKGROUND

Human rhinovirus (hRV) infections commonly cause acute upper respiratory infections and asthma exacerbations. Environmental cigarette smoke exposure is associated with a significant increase in the risk for these infections in children.

OBJECTIVE

To determine the impact of short-term exposure to cigarette smoke on innate immune responses of airway epithelial cells infected with hRV.

METHODS

A human bronchial epithelial cell line (HBEC-3KT) was exposed to cigarette smoke extract (CSE) for 30 min and subsequently infected with hRV serotype 1B. Viral-induced cytokine release was measured with AlphaLISA and viral replication quantified by shed viral titer and intracellular viral copy number 24h post-infection.

RESULTS

CSE induced a concentration-dependent decrease in CXCL10 (p<0.001) and IFN-β (p<0.001), with a 79% reduction at the highest dose with an associated 3-fold increase in shed virus. These effects were maintained when infection was delayed up to 24h post CSE exposure. Exogenous IFN-β treatment at t=0 after infection blunts the effects of CSE on viral replication (p<0.05).

CONCLUSION

A single exposure of 30 min to cigarette smoke has a lasting impact on epithelial innate defence providing a plausible mechanism for the increase in respiratory infections seen in children exposed to second-hand tobacco smoke.

Transcriptional and epigenetic modulation of human rhinovirus-induced CXCL10 production by cigarette smoke

Human rhinovirus (HRV) triggers exacerbations of asthma and chronic obstructive pulmonary disease. Cigarette smoking is the primary risk factor for the development of chronic obstructive pulmonary disease, and 25% of individuals with asthma smoke. Smokers experience both longer and more severe colds. We previously showed that cigarette smoke extract (CSE) inhibited HRV-induced expression of a range of epithelial antiviral molecules. Here, we use CXCL10 as a model antiviral gene to examine the mechanisms by which CSE inhibits epithelial antiviral immunity. HRV-induced CXCL10 transcription depends on activation of NF-ĸB and IFN-regulatory factor-1 (IRF-1), and we now also implicate two signal transducer and activator of transcription (STAT) consensus sequences in the CXCL10 promoter in HRV-induced CXCL10 expression. CSE inhibited HRV-induced activation and nuclear translocation/binding of both NF-ĸB, and IRF-1 to their respective recognition sequences in the CXCL10 promoter. HRV also induced formation of complexes at the STAT region in the CXCL10 promoter, and HRV-induced activation of STAT-1 was inhibited by CSE. In addition, CSE inhibited HRV-induced chromatin accessibility around the transcriptional start site of the CXCL10 promoter. Although CSE inhibited HRV-induced expression of both the viral double-stranded RNA sensors, retinoic acid-inducible gene-I and melanoma differentiation-associated gene (MDA) 5, only specific short interfering RNA (siRNA) to MDA5, but not nontargeting siRNA, or siRNA to retinoic acid-inducible gene-I, inhibited HRV-induced CXCL10 induction. We conclude that CSE reduces chromatin accessibility and inhibits viral signaling via NF-ĸB, IRF-1, STAT-1, and MDA5. Thus, we show that CSE can simultaneously modulate multiple pathways linked to innate immune responses to HRV infection.

Respiratory syncytial virus infections enhance cigarette smoke induced COPD in mice

Respiratory syncytial viral (RSV) infections are a frequent cause of chronic obstructive pulmonary disease (COPD) exacerbations, which are a major factor in disease progression and mortality. RSV is able to evade antiviral defenses to persist in the lungs of COPD patients. Though RSV infection has been identified in COPD, its contribution to cigarette smoke-induced airway inflammation and lung tissue destruction has not been established. Here we examine the long-term effects of cigarette smoke exposure, in combination with monthly RSV infections, on pulmonary inflammation, protease production and remodeling in mice. RSV exposures enhanced the influx of macrophages, neutrophils and lymphocytes to the airways of cigarette smoke exposed C57BL/6J mice. This infiltration of cells was most pronounced around the vasculature and bronchial airways. By itself, RSV caused significant airspace enlargement and fibrosis in mice and these effects were accentuated with concomitant smoke exposure. Combined stimulation with both smoke and RSV synergistically induced cytokine (IL-1α, IL-17, IFN-γ, KC, IL-13, CXCL9, RANTES, MIF and GM-CSF) and protease (MMP-2, -8, -12, -13, -16 and cathepsins E, S, W and Z) expression. In addition, RSV exposure caused marked apoptosis within the airways of infected mice, which was augmented by cigarette smoke exposure. RSV and smoke exposure also reduced protein phosphatase 2A (PP2A) and protein tyrosine phosphates (PTP1B) expression and activity. This is significant as these phosphatases counter smoke-induced inflammation and protease expression. Together, these findings show for the first time that recurrent RSV infection markedly enhances inflammation, apoptosis and tissue destruction in smoke-exposed mice. Indeed, these results indicate that preventing RSV transmission and infection has the potential to significantly impact on COPD severity and progression.

Community-acquired pneumonia among smokers

Recent studies have left absolutely no doubt that tobacco increases susceptibility to bacterial lung infection, even in passive smokers. This relationship also shows a dose-response effect, since the risk reduces spectacularly 10 years after giving up smoking, returning to the level of non-smokers. Streptococcus pneumoniae is the causative microorganism responsible for community-acquired pneumonia (CAP) most frequently associated with smoking, particularly in invasive pneumococcal disease and septic shock. It is not clear how it acts on the progress of pneumonia, but there is evidence to suggest that the prognosis for pneumococcal pneumonia is worse. In CAP caused by Legionella pneumophila, it has also been observed that smoking is the most important risk factor, with the risk rising 121% for each pack of cigarettes smoked a day. Tobacco use may also favor diseases that are also known risk factors for CAP, such as periodontal disease and upper respiratory viral infections. By way of prevention, while giving up smoking should always be proposed, the use of the pneumococcal vaccine is also recommended, regardless of the presence of other comorbidities.

Cigarette smoke enhances human rhinovirus-induced CXCL8 production via HuR-mediated mRNA stabilization in human airway epithelial cells

BACKGROUND

Human rhinovirus (HRV) triggers exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Cigarette smoking is the leading risk factor for the development of COPD and 25% of asthmatics smoke. Smoking asthmatics have worse symptoms and more frequent hospitalizations compared to non-smoking asthmatics. The degree of neutrophil recruitment to the airways correlates with disease severity in COPD and during viral exacerbations of asthma. We have previously shown that HRV and cigarette smoke, in the form of cigarette smoke extract (CSE), each induce expression of the neutrophil chemoattractant and activator, CXCL8, in human airway epithelial cells. Additionally, we demonstrated that the combination of HRV and CSE induces expression of levels of CXCL8 that are at least additive relative to induction by each stimulus alone, and that enhancement of CXCL8 expression by HRV+CSE is regulated, at least in part, via mRNA stabilization. Here we further investigate the mechanisms by which HRV+CSE enhances CXCL8 expression.

METHODS

Primary human bronchial epithelial cells were cultured and treated with CSE alone, HRV alone or the combination of the two stimuli. Stabilizing/destabilizing proteins adenine/uridine-rich factor-1 (AUF-1), KH-type splicing regulatory protein (KHSRP) and human antigen R (HuR) were measured in cell lysates to determine expression levels following treatment. siRNA knockdown of each protein was used to assess their contribution to the induction of CXCL8 expression following treatment of cells with HRV and CSE.

RESULTS

We show that total expression of stabilizing/de-stabilizing proteins linked to CXCL8 regulation, including AUF-1, KHSRP and HuR, are not altered by CSE, HRV or the combination of the two stimuli. Importantly, however, siRNA-mediated knock-down of HuR, but not AUF-1 or KHSRP, abolishes the enhancement of CXCL8 by HRV+CSE. Data were analyzed using one-way ANOVA with student Newman-Keuls post hoc analysis and values of p≤ 0.05 were considered significant.

CONCLUSIONS

Induction of CXCL8 by the combination of HRV and CSE is regulated by mRNA stabilization involving HuR. Thus, targeting the HuR pathway may be an effective method of dampening CXCL8 production during HRV-induced exacerbations of lower airway disease, particularly in COPD patients and asthmatic patients who smoke.

Relationship of secondhand smoke and infant lower respiratory tract infection severity by familial atopy status

BACKGROUND

Individuals with atopy have more severe complications of infectious diseases. We hypothesized that the importance of secondhand smoke (SHS) on lower respiratory tract infection (LRTI) severity would be greater in infants with a familial atopic predisposition.

OBJECTIVE

To determine whether infants with a familial atopic predisposition are more susceptible to adverse effects of SHS, resulting in more severe LRTI.

METHODS

We conducted cross-sectional analyses of mother-infant dyads enrolled during 2004 to 2008 during an infant LRTI. Predictor variables were SHS and 2 measures of a familial atopic predisposition (maternal atopic disease with allergen sensitization or familial atopy). LRTI severity was determined by bronchiolitis severity score (BSS) and hospital length of stay (LOS). We conducted multivariable regression analysis to test for a differential relationship between SHS and LRTI severity by measures of familial atopic predisposition.

RESULTS

In 451 dyads, 57% of infants had SHS exposure, 36% had a mother with atopic disease, and 68% had familial atopy. We did not detect differences in BSS or LOS by SHS exposure stratified by history of maternal atopic disease. In bivariate analysis, there was a significant difference in LOS by SHS in those with familial atopy (P = .006) but not in those without (P = .66). In multivariable analysis, among infants with familial atopy, there was a 23% increased LOS in infants with SHS exposure (P = .03), whereas no statistical significance was detected in those without familial atopy (P = .07).

CONCLUSION

In infants with familial atopy, SHS was associated with longer hospital LOS for LRTI but not BSS. Because the effect was seen only among hospitalized infants, confirmation is required.

Cigarette smoking and mechanisms of susceptibility to infections of the respiratory tract and other organ systems

The predisposition of cigarette smokers for development of oral and respiratory infections caused by microbial pathogens is well recognised, with those infected with the human immunodeficiency virus (HIV) at particularly high risk. Smoking cigarettes has a suppressive effect on the protective functions of airway epithelium, alveolar macrophages, dendritic cells, natural killer (NK) cells and adaptive immune mechanisms, in the setting of chronic systemic activation of neutrophils. Cigarette smoke also has a direct effect on microbial pathogens to promote the likelihood of infective disease, specifically promotion of microbial virulence and antibiotic resistance. In addition to interactions between smoking and HIV infection, a number of specific infections/clinical syndromes have been associated epidemiologically with cigarette smoking, including those of the upper and lower respiratory tract, gastrointestinal tract, central nervous and other organ systems. Smoking cessation benefits patients in many ways, including reduction of the risk of infectious disease.

Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

Background

False negative and indeterminate Interferon Gamma Release Assay (IGRA) results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB) and to impair Interferon-gamma (IFN-γ) responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively.

Methods

Patients with confirmed TB from Denmark (DK, n = 34; 20 smokers) and Tanzania (TZ, n = 172; 23 smokers) were tested with the QuantiFERON-TB Gold In tube (QFT). Median IFN-γ level in smokers and non smokers were compared and smoking was analysed as a risk factor for false negative and indeterminate QFT results.

Results

Smokers from both DK and TZ had lower IFN-γ antigen responses (median 0.9 vs. 4.2 IU/ml, p = 0.04 and 0.4 vs. 1.6, p < 0.01), less positive (50 vs. 86%, p = 0.03 and 48 vs. 75%, p < 0.01) and more false negative (45 vs. 0%, p < 0.01 and 26 vs. 11%, p = 0.04) QFT results. In Tanzanian patients, logistic regression analysis adjusted for sex, age, HIV and alcohol consumption showed an association of smoking with false negative (OR 17.1, CI: 3.0-99.1, p < 0.01) and indeterminate QFT results (OR 5.1, CI: 1.2-21.3, p = 0.02).

Conclusions

Cigarette smoking was associated with false negative and indeterminate IGRA results in both a high and a low TB endemic setting independent of HIV status.

A comparative study of respiratory syncytial virus (RSV) prophylaxis in premature infants within the Canadian Registry of Palivizumab (CARESS)

We examined the dosing regimens, compliance, and outcomes of premature infants who received palivizumab within the Canadian Registry of Palivizumab (CARESS). Infants receiving ≥1 dose of palivizumab during the 2006-2011 respiratory syncytial virus (RSV) seasons were recruited across 30 sites. Respiratory illness events were captured monthly. Infants ≤32 completed weeks gestational age (GA) (Group 1) were compared to 33-35 completed weeks GA infants (Group 2) following prophylaxis. In total, 6,654 patients were analyzed (Group 1, n = 5,183; Group 2, n = 1,471). The mean GA was 29.9 ± 2.9 versus 34.2 ± 2.2 weeks for Groups 1 and 2, respectively. Group differences were significant (all p-values <0.05) for the following: proportion of males, Caucasians, siblings, multiple births, maternal smoking, smoking during pregnancy, household smokers, >5 household individuals, birth weight, and enrolment age. Overall, infants received 92.6 % of expected injections. Group 1 received significantly more injections, but a greater proportion of Group 2 received injections within recommended intervals. The hospitalization rates were similar for Groups 1 and 2 for respiratory illness (4.7 % vs. 3.7 %, p = 0.1) and RSV (1.5 % vs. 1.4 %, p = 0.3). Neither the time to first respiratory illness [hazard ratio = 0.9, 95 % confidence interval (CI) 0.7-1.2, p = 0.5] nor to first RSV hospitalization (hazard ratio = 1.3, 95 % CI 0.8-2.2, p = 0.3) were different. Compliance with RSV prophylaxis is high. Despite the higher number of palivizumab doses in infants ≤32 completed weeks GA, the two groups' respiratory illness and RSV-positive hospitalization rates were similar.

Cigarette smoking decreases global microRNA expression in human alveolar macrophages

Human alveolar macrophages are critical components of the innate immune system. Cigarette smoking-induced changes in alveolar macrophage gene expression are linked to reduced resistance to pulmonary infections and to the development of emphysema/COPD. We hypothesized that microRNAs (miRNAs) could control, in part, the unique messenger RNA (mRNA) expression profiles found in alveolar macrophages of cigarette smokers. Activation of macrophages with different stimuli in vitro leads to a diverse range of M1 (inflammatory) and M2 (anti-inflammatory) polarized phenotypes that are thought to mimic activated macrophages in distinct tissue environments. Microarray mRNA data indicated that smoking promoted an "inverse" M1 mRNA expression program, defined by decreased expression of M1-induced transcripts and increased expression of M1-repressed transcripts with few changes in M2-regulated transcripts. RT-PCR arrays identified altered expression of many miRNAs in alveolar macrophages of smokers and a decrease in global miRNA abundance. Stratification of human subjects suggested that the magnitude of the global decrease in miRNA abundance was associated with smoking history. We found that many of the miRNAs with reduced expression in alveolar macrophages of smokers were predicted to target mRNAs upregulated in alveolar macrophages of smokers. For example, miR-452 is predicted to target the transcript encoding MMP12, an important effector of smoking-related diseases. Experimental antagonism of miR-452 in differentiated monocytic cells resulted in increased expression of MMP12. The comprehensive mRNA and miRNA expression profiles described here provide insight into gene expression regulation that may underlie the adverse effects cigarette smoking has on alveolar macrophages.

Cigarette smoking and inflammation: cellular and molecular mechanisms

Cigarette smoke (CS) causes considerable morbidity and mortality by inducing cancer, chronic lung and vascular diseases, and oral disease. Despite the well-recognized risks associated with smoking, the habit remains unacceptably prevalent. Several toxins present in CS have immunomodulatory effects. CS also contains trace amounts of microbial cell components, including bacterial lipopolysaccharide. These and other CS constituents induce chronic inflammation at mucosal surfaces and modify host responses to exogenous antigens. The effects of CS on immunity are far-reaching and complex; both pro-inflammatory and suppressive effects may be induced. The net effect of CS on immunity depends on many variables, including the dose and type of tobacco, the route and chronicity of exposure, and the presence of other factors at the time of immune cell stimulation, such as Toll receptor ligands or other inflammatory mediators. CS impairs innate defenses against pathogens, modulates antigen presentation, and promotes autoimmunity. CS also impairs immunity in the oral cavity and promotes gingival and periodontal disease and oral cancer. The recognition of specific mechanisms by which CS affects host immunity is an important step toward elucidating mechanisms of tobacco-induced disease and may identify novel therapeutic approaches for the management of diseases that afflict smokers.

Moving towards a new generation of animal models for asthma and COPD with improved clinical relevance

Asthma and chronic obstructive pulmonary disease (COPD) are complex inflammatory airway diseases characterised by airflow obstruction that remain leading causes of hospitalization and death worldwide. Animal modelling systems that accurately reflect disease pathophysiology continue to be essential to the development of new therapies for both conditions. In this review, we describe preclinical in vivo models that recapitulate many of the features of asthma and COPD. Specifically, we discuss the pro's and con's of the standard models and highlight recently developed systems designed to more accurately reflect the complexity of both diseases. For instance, clinically relevant allergens (i.e. house dust mite) are now being used to mimic the inflammatory changes and airway remodelling that result after chronic allergen exposures. Additionally, systems are being developed to mimic steroid-resistant and viral exacerbations of allergic inflammation - aspects of asthma where there is an acute need for new therapies. Similarly, COPD models have evolved to align with the improved clinical understanding of the factors contributing to disease progression. This includes using cigarette smoke to model not only airway inflammation and remodelling, but some systemic changes (e.g. hypertension and skeletal muscle alterations) that are thought to influence disease. Further, mouse genetics are being exploited to gain insights into the genetics of COPD susceptibility. The new models of asthma and COPD described herein demonstrate that improved clinical understanding of the diseases and better preclinical models is an iterative process that will hopefully lead to therapies that can effectively manage severe asthma and COPD.