Tobacco smoke exposure and altered nasal responses to live attenuated influenza virus

Modeling the effects of cigarette smoke extract on influenza B virus infections in mice

Influenza B virus (IBV) is a major respiratory viral pathogen. Due to a lack of pandemic potential for IBV, there is a lag in research on IBV pathology and immunological responses compared to IAV. Therefore, the impact of various lifestyle and environmental factors on IBV infections, such as cigarette smoking (CS), remains elusive. Despite the increased risk and severity of IAV infections with CS, limited information exists on the impact of CS on IBV infections due to the absence of suitable animal models. To this end, we developed an animal model system by pre-treating mice for two weeks with cigarette smoke extract (CSE), then infected them with IBV and monitored the resulting pathological, immunological, and virological effects. Our results reveal that the CSE treatment decreased IBV specific IgG levels yet did not change viral replication in the upper airway/the lung, and weight recovery post infection. However, higher concentrations of CSE did result in higher mortality post infection. Together, this suggests that CS induced inflammation coupled with IBV infection resulted in exacerbated disease outcome.

Cytokine signature clusters as a tool to compare changes associated with tobacco product use in upper and lower airway samples

Inhalation exposure to cigarette smoke and e-cigarette aerosol is known to alter the respiratory immune system, particularly cytokine signaling. In assessments of health impacts of tobacco product use, cytokines are often measured using a variety of sample types, from serum to airway mucosa. However, it is currently unclear whether and how well cytokine levels from different sample types and the airway locations they represent are correlated, making comparing studies that utilize differing sample types challenging. To address this challenge, we compared baseline cytokine signatures in upper and lower airways and systemic samples and evaluated how groups of coexpressed cytokines change with tobacco product use. Matched nasal lavage fluid (NLF), nasal epithelial lining fluid (NELF), sputum, and circulating serum samples were collected from 14 nonsmokers, 13 cigarette smokers, and 17 e-cigarette users and analyzed for levels of 22 cytokines. Individual cytokine signatures were first compared across each sample type, followed by identification of cytokine clusters within each sample type. Identified clusters were then evaluated for potential alterations following tobacco product use using eigenvector analyses. Individual cytokine signatures in the respiratory tract were significantly correlated (NLF, NELF, and sputum) compared with randomly permutated signatures, whereas serum was not significantly different from random permutations. Cytokine clusters that were similar across airway sample types were modified by tobacco product use, particularly e-cigarettes, indicating a degree of uniformity in terms of how cytokine host defense and immune cell recruitment responses cooperate in the upper and lower airways. Overall, cluster-based analyses were found to be especially useful in small cohort assessments, providing higher sensitivity than individual signatures to detect biologically meaningful differences between tobacco use groups. This novel cluster analysis approach revealed that eigencytokine patterns in noninvasive upper airway samples simulate cytokine patterns in lower airways.

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.

Effects of Vaccination Day Routine Activities on Influenza Vaccine Efficacy and Vaccination-Induced Adverse Reaction Incidence: A Cohort Study

We aimed to investigate the effect of vaccination day routine activities on the influenza vaccine efficacy and vaccination-induced adverse reaction incidence. Study participants were workers at three hospitals in the Hyogo Prefecture, Japan, who received the influenza vaccine between October and November, 2018 and 2019. Their data were collected using a questionnaire. The main factors, which were examined for vaccination day routine activities, were personal hygiene (bathing), smoking, alcohol consumption, caffeine intake, and exercise. The main outcome markers included influenza incidence during the winter season and vaccination-induced local or systemic adverse reaction incidence. The risk ratio for the main factors of vaccination day routine activities was calculated against the main outcome markers using the modified Poisson regression. Overall, 3780 people received the influenza vaccination, and 2731 submitted the questionnaire. We found that vaccination day routine activities did not affect the influenza vaccine efficacy, and engaging in strenuous exercise on the vaccination day tended to cause systemic adverse reactions. Moreover, lifestyle-related activities had no impact on the incidence of systemic or local adverse reactions. Therefore, it is advisable to only avoid strenuous physical exercise, and no other lifestyle-related restrictions are necessary on the day of influenza vaccination.

COVID-19 and Smoking: What Evidence Needs Our Attention?

The current COVID-19 pandemic has caused severe morbidity and mortality worldwide. Although relevant studies show that the smoking rate of COVID-19 patients is relatively low, the current smoking status of people with COVID-19 cannot be accurately measured for reasons. Thus, it is difficult to assess the relationship between smoking and COVID-19. Smoking can increase the risk of severe COVID-19 symptoms and aggravate the condition of patients with COVID-19. Nicotine upregulates the expression of ACE2, which can also increase susceptibility to COVID-19, aggravatiing the disease. Although nicotine has certain anti-inflammatory effects, there is no evidence that it is related to COVID-19 treatment; therefore, smoking cannot be considered a preventative measure. Furthermore, smokers gathering and sharing tobacco may promote the spread of viruses. Despite the COVID-19 epidemic, the findings suggested that COVID-19 has not encouraged smokers to quit. Additionally, there is evidence that isolation at home has contributed to increased smoking behavior and increased quantities. Therefore, it is recommended that governments increase smoking cessation messaging as part of public health measures to contain the COVID-19 pandemic. This review analyzes the existing research on smoking's impact on COVID-19 so that governments and medical institutions can develop evidence-based smoking-related prevention and control measures for COVID-19.

Polluted Air Exposure Compromises Corneal Immunity and Exacerbates Inflammation in Acute Herpes Simplex Keratitis

Air pollution is a serious environmental issue worldwide in developing countries’ megacities, affecting the population’s health, including the ocular surface, by predisposing or exacerbating other ocular diseases. Herpes simplex keratitis (HSK) is caused by the herpes simplex virus type 1 (HSV-1). The primary or recurring infection in the ocular site causes progressive corneal scarring that may result in visual impairment. The present study was designed to study the immunopathological changes of acute HSK under urban polluted air, using the acute HSK model combined with an experimental urban polluted air exposure from Buenos Aires City. We evaluated the corneal clinical outcomes, viral DNA and pro-inflammatory cytokines by RT-PCR and ELISA assays, respectively. Then, we determined the innate and adaptive immune responses in both cornea and local lymph nodes after HSV-1 corneal by immunofluorescence staining and flow cytometry. Our results showed that mice exposed to polluted air develop a severe form of HSK with increased corneal opacity, neovascularization, HSV-1 DNA and production of TNF-α, IL-1β, IFN-γ, and CCL2. A high number of corneal resident immune cells, including activated dendritic cells, was observed in mice exposed to polluted air; with a further significant influx of bone marrow-derived cells including GR1+ cells (neutrophils and inflammatory monocytes), CD11c+ cells (dendritic cells), and CD3+ (T cells) during acute corneal HSK. Moreover, mice exposed to polluted air showed a predominant Th1 type T cell response over Tregs in local lymph nodes during acute HSK with decreased corneal Tregs. These findings provide strong evidence that urban polluted air might trigger a local imbalance of innate and adaptive immune responses that exacerbate HSK severity. Taking this study into account, urban air pollution should be considered a key factor in developing ocular inflammatory diseases.

Electronic-Cigarette Use Alters Nasal Mucosal Immune Response to Live-attenuated Influenza Virus. A Clinical Trial

Inhalation of tobacco smoke has been linked to increased risk of viral infection, such as influenza. Inhalation of electronic-cigarette (e-cigarette) aerosol has also recently been linked to immune suppression within the respiratory tract, specifically the nasal mucosa. We propose that changes in the nasal mucosal immune response modify antiviral host-defense responses in e-cigarette users. Nonsmokers, cigarette smokers, and e-cigarette users were inoculated with live-attenuated influenza virus (LAIV) to safely examine the innate immune response to influenza infection. Before and after LAIV inoculation, we collected nasal epithelial-lining fluid, nasal lavage fluid, nasal-scrape biopsy specimens, urine, and blood. Endpoints examined include cytokines and chemokines, influenza-specific IgA, immune-gene expression, and markers of viral load. Statistical analysis included primary comparisons of cigarette and e-cigarette groups with nonsmokers, as well as secondary analysis of demographic factors as potential modifiers. Markers of viral load did not differ among the three groups. Nasal-lavage-fluid anti-LAIV IgA levels increased in nonsmokers after LAIV inoculation but did not increase in e-cigarette users and cigarette smokers. LAIV-induced gene-expression changes in nasal biopsy specimens differed in cigarette smokers and e-cigarette users as compared with nonsmokers, with a greater number of genes changed in e-cigarette users, mostly resulting in decreased expression. The top downregulated genes in cigarette smokers were SMPD3, NOS2A, and KLRB1, and the top downregulated genes in e-cigarette users were MR1, NT5E, and HRAS. Similarly, LAIV-induced cytokine levels in nasal epithelial-lining fluid differed among the three groups, including decreased antiviral host-defense mediators (IFNγ, IL6, and IL12p40). We also detected that sex interacted with tobacco-product exposure to modify LAIV-induced immune-gene expression. Our results demonstrate that e-cigarette use altered nasal LAIV-induced immune responses, including gene expression, cytokine and chemokine release, and LAIV-specific IgA levels. Together, these data suggest that e-cigarette use induces changes in the nasal mucosa that are consistent with the potential for altered respiratory antiviral host-defense function.

Clinical trial registered with www.clinicaltrials.gov (NCT 02019745).

Cigarette Smoke Affects Dendritic Cell Populations, Epithelial Barrier Function, and the Immune Response to Viral Infection With H1N1

Smokers with apparently “healthy” lungs suffer from more severe and frequent viral respiratory infections, but the mechanisms underlying this observation are still unclear. Epithelial cells and dendritic cells (DC) form the first line of defense against inhaled noxes such as smoke or viruses. We therefore aimed to obtain insight into how cigarette smoke affects DCs and epithelial cells and how this influences the response to viral infection. Female C57BL/6J mice were exposed to cigarette smoke (CS) for 1 h daily for 24 days and then challenged i.n. with the viral mimic and Toll-like receptor 3 (TLR3) ligand poly (I:C) after the last exposure. DC subpopulations were analyzed 24 h later in whole lung homogenates by flow cytometry. Calu-3 cells or human precision-cut lung slices (PCLS) cultured at air-liquid interface were exposed to CS or air and subsequently inoculated with influenza H1N1. At 48 h post infection cytokines were analyzed by multiplex technology. Cytotoxic effects were measured by release of lactate dehydrogenase (LDH) and confocal imaging. In Calu-3 cells the trans-epithelial electrical resistance (TEER) was assessed. Smoke exposure of mice increased numbers of inflammatory and plasmacytoid DCs in lung tissue. Additional poly (I:C) challenge further increased the population of inflammatory DCs and conventional DCs, especially CD11b⁺ cDCs. Smoke exposure led to a loss of the barrier function in Calu-3 cells, which was further exaggerated by additional influenza H1N1 infection. Influenza H1N1-induced secretion of antiviral cytokines (IFN-α2a, IFN-λ, interferon-γ-induced protein 10 [IP-10]), pro-inflammatory cytokine IL-6, as well as T cell-associated cytokines (e.g., I-TAC) were completely suppressed in both Calu-3 cells and human PCLS after smoke exposure. In summary, cigarette smoke exposure increased the number of inflammatory DCs in the lung and disrupted epithelial barrier functions, both of which was further enhanced by viral stimulation. Additionally, the antiviral immune response to influenza H1N1 was strongly suppressed by smoke. These data suggest that smoke impairs protective innate mechanisms in the lung, which could be responsible for the increased susceptibility to viral infections in “healthy” smokers.

Possible role of highly activated mucosal NK cells against viral respiratory infections in children undergoing haematopoietic stem cell transplantation

Infection is the leading cause of non-relapse-related mortality after allogeneic haematopoietic stem cell transplantation (HSCT). Altered functions of immune cells in nasal secretions may influence post HSCT susceptibility to viral respiratory infections. In this prospective study, we determined T and NK cell numbers together with NK activation status in nasopharyngeal aspirates (NPA) in HSCT recipients and healthy controls using multiparametric flow cytometry. We also determined by polymerase chain reaction (PCR) the presence of 16 respiratory viruses. Samples were collected pre-HSCT, at day 0, +10, +20 and +30 after HSCT. Peripheral blood (PB) was also analyzed to determine T and NK cell numbers. A total of 27 pediatric HSCT recipients were enrolled and 16 of them had at least one viral detection (60%). Rhinovirus was the most frequent pathogen (84% of positive NPAs). NPAs of patients contained fewer T and NK cells compared to healthy controls (p = 0.0132 and p = 0.120, respectively). Viral PCR + patients showed higher NK cell number in their NPAs. The activating receptors repertoire expressed by NK cells was also higher in NPA samples, especially NKp44 and NKp46. Our study supports NK cells relevance for the immune defense against respiratory viruses in HSCT recipients.

Cigarette smoking and the occurrence of influenza - Systematic review

OBJECTIVES

The association of current smoking with influenza infection is not widely recognised. The aim of this systematic review was to summarise published evidence and quantify the risk of influenza infection in tobacco smokers compared to non-smokers.

METHODS

We systematically searched MEDLINE, EMBASE, CINAHL, LILACS and Web of Science, from inception to 7 November 2017, to identify relevant randomised control trials, cohort and case-control studies. Study quality was assessed using the Newcastle-Ottawa Scale. We included studies defining influenza as a clinical syndrome and those using confirmatory microbiological tests. Pooled odds ratios (ORs) were estimated by using random effects model.

RESULTS

The mean quality score across the nine included studies (n = 40,685 participants) was 5.4 of 9 (SD 1.07). Current smokers were over 5 times more likely to develop laboratory-confirmed influenza than non-smokers (pooled OR 5.69 (95% CI 2.79-11.60), 3 studies). For studies reporting the occurrence of an influenza-like illness (ILI), current smokers were 34% more likely to develop ILI than non-smokers (pooled OR 1.34 (95% CI 1.13-1.59), 6 studies).

CONCLUSION

Current smokers have an increased risk of developing influenza compared to non-smokers. The association was strongest in studies examining cases with laboratory confirmed influenza.

Dynamic changes in lung responses after single and repeated exposures to cigarette smoke in mice

Cigarette smoke is well recognized to cause injury to the airways and the alveolar walls over time. This injury usually requires many years of exposure, suggesting that the lungs may rapidly develop responses that initially protect it from this repetitive injury. Our studies tested the hypotheses that smoke induces an inflammatory response and changes in mRNA profiles that are dependent on sex and the health status of the lung, and that the response of the lungs to smoke differs after 1 day compared to 5 days of exposure. Male and female wildtype (WT) and Scnn1b-transgenic (βENaC) mice, which have chronic bronchitis and emphysematous changes due to dehydrated mucus, were exposed to cigarette smoke or sham air conditions for 1 or 5 days. The inflammatory response and gene expression profiles were analyzed in lung tissue. Overall, the inflammatory response to cigarette smoke was mild, and changes in mediators were more numerous after 1 than 5 days. βENaC mice had more airspace leukocytes than WT mice, and smoke exposure resulted in additional significant alterations. Many genes and gene sets responded similarly at 1 and 5 days: genes involved in oxidative stress responses were upregulated while immune response genes were downregulated. However, certain genes and biological processes were regulated differently after 1 compared to 5 days. Extracellular matrix biology genes and gene sets were upregulated after 1 day but downregulated by 5 days of smoke compared to sham exposure. There was no difference in the transcriptional response to smoke between WT and βENaC mice or between male and female mice at either 1 or 5 days. Taken together, these studies suggest that the lungs rapidly alter gene expression after only one exposure to cigarette smoke, with few additional changes after four additional days of repeated exposure. These changes may contribute to preventing lung damage.

Therapeutic Modulation of Virus-Induced Oxidative Stress via the Nrf2-Dependent Antioxidative Pathway

Virus-induced oxidative stress plays a critical role in the viral life cycle as well as the pathogenesis of viral diseases. In response to reactive oxygen species (ROS) generation by a virus, a host cell activates an antioxidative defense system for its own protection. Particularly, a nuclear factor erythroid 2p45-related factor 2 (Nrf2) pathway works in a front-line for cytoprotection and detoxification. Recently, a series of studies suggested that a group of clinically relevant viruses have the capacity for positive and negative regulations of the Nrf2 pathway. This virus-induced modulation of the host antioxidative response turned out to be a crucial determinant for the progression of several viral diseases. In this review, virus-specific examples of positive and negative modulations of the Nrf2 pathway will be summarized first. Then a number of successful genetic and pharmacological manipulations of the Nrf2 pathway for suppression of the viral replication and the pathogenesis-associated oxidative damage will be discussed later. Understanding of the interplay between virus-induced oxidative stress and antioxidative host response will aid in the discovery of potential antiviral supplements for better management of viral diseases.

Distinguishing Human Peripheral Blood NK Cells from CD56dimCD16dimCD69+CD103+ Resident Nasal Mucosal Lavage Fluid Cells

Natural killer (NK) cells are members of the innate lymphoid cells group 1 (ILC1s), which play a critical role in innate host defense against viruses and malignancies. While many studies have examined the role of circulating peripheral blood (PB) CD56⁺ NK cells, little is known about the resident CD56⁺ cell population. Therefore, matched CD56⁺ cells from nasal lavage fluid (NLF) and PB of smokers and non-smokers were compared phenotypically, via flow cytometry, and functionally, via NK-cell specific gene expression. NLF and PB CD56⁺ cells had similar expression of CD56, but differentially expressed tissue residency (CD69 and CD103) and cytotoxicity (CD16) markers. In addition, NLF CD56^dim cells expressed lower levels of cytotoxicity-associated genes, perforin (PRF1) and granzyme B (GZMB), and increased levels of cytokines and cell signaling molecules, TRAIL, IFNGR2, and IL8, as compared to PB CD56^dim cells. In smokers, ITGA2 was downregulated in NLF CD56^dim cells, while markers of cytotoxic function were primarily downregulated in PB CD56^dim NK cells. Overall, NLF CD56^dim cells are a unique cell population that likely play a role in orchestrating innate immune responses in the nasal cavity, which is distinct from their role as a non-antigen-restricted cytotoxic CD56^dim lymphocytes in the PB.

Flavored e-cigarette liquids and cinnamaldehyde impair respiratory innate immune cell function

Innate immune cells of the respiratory tract are the first line of defense against pathogenic and environmental insults. Failure of these cells to perform their immune functions leaves the host susceptible to infection and may contribute to impaired resolution of inflammation. While combustible tobacco cigarettes have been shown to suppress respiratory immune cell function, the effects of flavored electronic cigarette liquids (e-liquids) and individual flavoring agents on respiratory immune cell responses are unknown. We investigated the effects of seven flavored nicotine-free e-liquids on primary human alveolar macrophages, neutrophils, and natural killer (NK) cells. Cells were challenged with a range of e-liquid dilutions and assayed for their functional responses to pathogenic stimuli. End points included phagocytic capacity (neutrophils and macrophages), neutrophil extracellular trap formation, proinflammatory cytokine production, and cell-mediated cytotoxic response (NK cells). E-liquids were then analyzed via mass spectrometry to identify individual flavoring components. Three cinnamaldehyde-containing e-liquids exhibited dose-dependent broadly immunosuppressive effects. Quantitative mass spectrometry was used to determine concentrations of cinnamaldehyde in each of the three e-liquids, and cells were subsequently challenged with a range of cinnamaldehyde concentrations. Cinnamaldehyde alone recapitulated the impaired function observed with e-liquid exposures, and cinnamaldehyde-induced suppression of macrophage phagocytosis was reversed by addition of the small-molecule reducing agent 1,4-dithiothreitol. We conclude that cinnamaldehyde has the potential to impair respiratory immune cell function, illustrating an immediate need for further toxicological evaluation of chemical flavoring agents to inform regulation governing their use in e-liquid formulations.

Novel applications for a noninvasive sampling method of the nasal mucosa

Reliable methods for sampling the nasal mucosa provide clinical researchers with key information regarding respiratory biomarkers of exposure and disease. For quick and noninvasive sampling of the nasal mucosa, nasal lavage (NL) collection has been widely used as a clinical tool; however, limitations including volume variability, sample dilution, and storage prevent NL collection from being used in nonlaboratory settings and analysis of low abundance biomarkers. In this study, we optimize and validate a novel methodology using absorbent Leukosorb paper cut to fit the nasal passage to extract epithelial lining fluid (ELF) from the nasal mucosa. The ELF sampling method limits the dilution of soluble mediators, allowing quantification of both high- and low-abundance soluble biomarkers such as IL-1β, IL-8, IL-6, interferon gamma-induced protein 10 (IP-10), and neutrophil elastase. Additionally, we demonstrate that this method can successfully detect the presence of respiratory pathogens such as influenza virus and markers of antibiotic-resistant bacteria in the nasal mucosa. Efficacy of ELF collection by this method is not diminished in consecutive-day sampling, and percent recovery of both recombinant IL-8 and soluble mediators are not changed despite freezing or room temperature storage for 24 h. Our results indicate that ELF collection using Leukosorb paper sampling of ELF provides a sensitive, easy-to-use, and reproducible methodology to collect concentrated amounts of soluble biomarkers from the nasal mucosa. Moreover, the methodology described herein improves upon the standard NL collection method and provides researchers with a novel tool to assess changes in nasal mucosal host defense status.

Association of indoor air pollution from coal combustion with influenza-like illness in housewives

An association of influenza-like illness (ILI) with outdoor air pollution has been reported. However, the effect of indoor air pollution on ILI was rarely investigated. We aimed to determine an association of indoor air pollution from coal combustion (IAPCC) and lifestyle with ILI risk in housewives, and the modification effect of phase II metabolic enzyme genes. We recruited 403 housewives for a cross-sectional study in Shanxi Province, China, including 135 with ILI frequency (≥1 time per year in the past ten years) as the case group and 268 with ILI frequency (<1 times per year) as the control group. Information on their energy usage characteristics and lifestyle was collected by questionnaires, as well as the single nucleotide polymorphisms (SNPs) of epoxide hydrolase 1 (rs1051740 and rs2234922), N-acetyltransferase 2 (rs1041983), and glutathione S-transferase (rs1695). We used exposure index to indicate the level of IAPCC among housewives. Our results revealed that the exposure index was positively correlated with ILI frequency. A significant dose-response trend between the exposure index and ILI risk was found with or without adjusting for confounders. Cooking frequency in kitchen with coal as primary fuel and ventilation frequency in the living room or bedroom with a coal-fueled stove for heating during the heating season were two important risk factors to affect ILI frequency. Only rs1051740 was found to be associated with exposure index, whereas it didn't have interaction effect with exposure index on ILI frequency. In conclusion, IAPCC and SNPs of rs1051740 were both associated with ILI frequency.

Perfluoroalkyl substance serum concentrations and immune response to FluMist vaccination among healthy adults

Perfluoroalkyl substances (PFAS) were shown to be immunotoxic in laboratory animals. There is some epidemiological evidence that PFAS exposure is inversely associated with vaccine-induced antibody concentration. We examined immune response to vaccination with FluMist intranasal live attenuated influenza vaccine in relation to four PFAS (perfluorooctanoate, perfluorononanoate, perfluorooctane sulfonate, perfluorohexane sulfonate) serum concentrations among 78 healthy adults vaccinated during the 2010-2011 influenza season. We measured anti-A H1N1 antibody response and cytokine and chemokine concentrations in serum pre-vaccination, 3 days post-vaccination, and 30 days post-vaccination. We measured cytokine, chemokine, and mucosal IgA concentration in nasal secretions 3 days post-vaccination and 30 days post-vaccination. Adults with higher PFAS concentrations were more likely to seroconvert after FluMist vaccination as compared to adults with lower PFAS concentrations. The associations, however, were imprecise and few participants seroconverted as measured either by hemagglutination inhibition (9%) or immunohistochemical staining (25%). We observed no readily discernable or consistent pattern between PFAS concentration and baseline cytokine, chemokine, or mucosal IgA concentration, or between PFAS concentration and change in these immune markers between baseline and FluMist-response states. The results of this study do not support a reduced immune response to FluMist vaccination among healthy adults in relation to serum PFAS concentration. Given the study's many limitations, however, it does not rule out impaired vaccine response to other vaccines or vaccine components in either children or adults.

E-cigarette use results in suppression of immune and inflammatory-response genes in nasal epithelial cells similar to cigarette smoke

Exposure to cigarette smoke is known to result in impaired host defense responses and immune suppressive effects. However, the effects of new and emerging tobacco products, such as e-cigarettes, on the immune status of the respiratory epithelium are largely unknown. We conducted a clinical study collecting superficial nasal scrape biopsies, nasal lavage, urine, and serum from nonsmokers, cigarette smokers, and e-cigarette users and assessed them for changes in immune gene expression profiles. Smoking status was determined based on a smoking history and a 3- to 4-wk smoking diary and confirmed using serum cotinine and urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels. Total RNA from nasal scrape biopsies was analyzed using the nCounter Human Immunology v2 Expression panel. Smoking cigarettes or vaping e-cigarettes resulted in decreased expression of immune-related genes. All genes with decreased expression in cigarette smokers (n = 53) were also decreased in e-cigarette smokers. Additionally, vaping e-cigarettes was associated with suppression of a large number of unique genes (n = 305). Furthermore, the e-cigarette users showed a greater suppression of genes common with those changed in cigarette smokers. This was particularly apparent for suppressed expression of transcription factors, such as EGR1, which was functionally associated with decreased expression of 5 target genes in cigarette smokers and 18 target genes in e-cigarette users. Taken together, these data indicate that vaping e-cigarettes is associated with decreased expression of a large number of immune-related genes, which are consistent with immune suppression at the level of the nasal mucosa.

Cigarette Smoke Attenuates the Nasal Host Response to Streptococcus pneumoniae and Predisposes to Invasive Pneumococcal Disease in Mice

Streptococcus pneumoniae is a leading cause of invasive bacterial infections, with nasal colonization an important first step in disease. While cigarette smoking is a strong risk factor for invasive pneumococcal disease, the underlying mechanisms remain unknown. This is partly due to a lack of clinically relevant animal models investigating nasal pneumococcal colonization in the context of cigarette smoke exposure. We present a model of nasal pneumococcal colonization in cigarette smoke-exposed mice and document, for the first time, that cigarette smoke predisposes to invasive pneumococcal infection and mortality in an animal model. Cigarette smoke increased the risk of bacteremia and meningitis without prior lung infection. Mechanistically, deficiency in interleukin 1α (IL-1α) or platelet-activating factor receptor (PAFR), an important host receptor thought to bind and facilitate pneumococcal invasiveness, did not rescue cigarette smoke-exposed mice from invasive pneumococcal disease. Importantly, we observed cigarette smoke to attenuate nasal inflammatory mediator expression, particularly that of neutrophil-recruiting chemokines, normally elicited by pneumococcal colonization. Smoking cessation during nasal pneumococcal colonization rescued nasal neutrophil recruitment and prevented invasive disease in mice. We propose that cigarette smoke predisposes to invasive pneumococcal disease by suppressing inflammatory processes of the upper respiratory tract. Given that smoking prevalence remains high worldwide, these findings are relevant to the continued efforts to reduce the invasive pneumococcal disease burden.

Effect of Broccoli Sprouts and Live Attenuated Influenza Virus on Peripheral Blood Natural Killer Cells: A Randomized, Double-Blind Study

Enhancing antiviral host defense responses through nutritional supplementation would be an attractive strategy in the fight against influenza. Using inoculation with live attenuated influenza virus (LAIV) as an infection model, we have recently shown that ingestion of sulforaphane-containing broccoli sprout homogenates (BSH) reduces markers of viral load in the nose. To investigate the systemic effects of short-term BSH supplementation in the context of LAIV-inoculation, we examined peripheral blood immune cell populations in non-smoking subjects from this study, with a particular focus on NK cells. We carried out a randomized, double-blinded, placebo-controlled study measuring the effects of BSH (N = 13) or placebo (alfalfa sprout homogenate, ASH; N = 16) on peripheral blood mononuclear cell responses to a standard nasal vaccine dose of LAIV in healthy volunteers. Blood was drawn prior to (day-1) and post (day2, day21) LAIV inoculation and analyzed for neutrophils, monocytes, macrophages, T cells, NKT cells, and NK cells. In addition, NK cells were enriched, stimulated, and assessed for surface markers, intracellular markers, and cytotoxic potential by flow cytometry. Overall, LAIV significantly reduced NKT (day2 and day21) and T cell (day2) populations. LAIV decreased NK cell CD56 and CD158b expression, while significantly increasing CD16 expression and cytotoxic potential (on day2). BSH supplementation further increased LAIV-induced granzyme B production (day2) in NK cells compared to ASH and in the BSH group granzyme B levels appeared to be negatively associated with influenza RNA levels in nasal lavage fluid cells. We conclude that nasal influenza infection may induce complex changes in peripheral blood NK cell activation, and that BSH increases virus-induced peripheral blood NK cell granzyme B production, an effect that may be important for enhanced antiviral defense responses.

Trial Registration: ClinicalTrials.gov NCT01269723

Environmental tobacco exposure is associated with vaccine modified measles in junior high school students

Vaccine modified measles (VMM) affects individuals with attenuated vaccine induced immunity. An outbreak of measles occurred in a junior high school, starting from an unvaccinated eighth-grade student who developed natural measles and affected a majority of students who were immunized with a low potent strain of measles vaccine (TD97). To determine whether environmental tobacco smoke (ETS) exposure was associated with the development of VMM in this population, a questionnaire was used asking whether students had VMM symptoms during the outbreak and the smoking status of family members. VMM was defined in the study population as occurrence of fever and/or erythema, along with documented history of measles vaccination. A total of 513 students (85.9%) responded. Overall, the presence of in-house smokers did not differ between VMM students (49.3%) and non-VMM students (50.2%). However, in the ninth grade, presence of an in-house smoker was significantly higher in the family of VMM students (54.0%) than in non-VMM students (36.6%) (P = 0.044). Urinary cotinine levels were also measured in selected students (n = 37). Among families with at least one smoker, urinary cotinine levels were significantly higher in VMM students than in non-VMM students (P = 0.032). Furthermore, a multivariable logistic regression analysis showed that a high urinary cotinine level (>10 ng/mg creatinine; 13.5 percentile) was associated with the development of VMM. Our findings suggest that a high level of ETS exposure may be associated with an increased risk of VMM in a population with attenuated vaccine induced immunity against measles.

Biomarker sampling of the airways in asthma

PURPOSE OF REVIEW

Although there are several known methods by which to sample the upper and lower airways in asthmatic patients, new endpoints have emerged over the past few years from these sampling techniques that may be useful biomarkers. It is both timely and relevant that these endpoints be reviewed in the context of their role in asthma and hence as potential biomarkers in asthma.

RECENT FINDINGS

This article will cover various upper and lower airway sampling methods, and the standard and specialized endpoints that can be derived from those methods. For the nasal airways, this will include nasal lavage, exhaled nasal nitric oxide and acoustic rhinometry. For the lower airways this will include induced sputum, bronchoscopy-based methods and exhaled breath.

SUMMARY

Some methodologies such as bronchoscopy remain limited in their widespread clinical application due to their invasive nature. Less invasive techniques such as electronic nose and breath condensate have potential biomarker application but still require standardization and additional study. It is clear, however, that despite the applicability of a given sampling technique, both routine (cells and cytokines) and specialized (genomic, phenotypic, hydration) endpoints are measurable and should be combined in clinical trial studies to yield maximum results in asthma.

Effect of broccoli sprouts on nasal response to live attenuated influenza virus in smokers: a randomized, double-blind study

BACKGROUND

Smokers have increased susceptibility and altered innate host defense responses to influenza virus infection. Broccoli sprouts are a source of the Nrf2 activating agentsulforaphane, and short term ingestion of broccoli sprout homogenates (BSH) has been shown to reduce nasal inflammatory responses to oxidant pollutants.

OBJECTIVES

Assess the effects of BSH on nasal cytokines, virus replication, and Nrf2-dependent enzyme expression in smokers and nonsmokers.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial comparing the effects of BSH on serially sampled nasal lavage fluid (NLF) cytokines, viral sequence quantity, and Nrf2-dependent enzyme expression in NLF cells and biopsied epithelium. Healthy young adult smokers and nonsmokers ingested BSH or placebo (alfalfa sprout homogenate) for 4 days, designated Days -1, 0, 1, 2. On Day 0 they received standard vaccine dose of live attenuated influenza virus (LAIV) intranasally. Nasal lavage fluids and nasal biopsies were collected serially to assess response to LAIV.

RESULTS

In area under curve analyses, post-LAIV IL-6 responses (P = 0.03) and influenza sequences (P = 0.01) were significantly reduced in NLF from BSH-treated smokers, while

NAD(P)H

quinoneoxidoreductasein NLF cells was significantly increased. In nonsmokers, a similar trend for reduction in virus quantity with BSH did not reach statistical significance.

CONCLUSIONS

In smokers, short term ingestion of broccoli sprout homogenates appears to significantly reduce some virus-induced markers of inflammation, as well as reducing virus quantity. Nutritional antioxidant interventions have promise as a safe, low-cost strategy for reducing influenza risk among smokers and other at risk populations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01269723.

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.

Influenza virus-induced lung inflammation was modulated by cigarette smoke exposure in mice

Although smokers have increased susceptibility and severity of seasonal influenza virus infection, there is no report about the risk of 2009 pandemic H1N1 (pdmH1N1) or avian H9N2 (H9N2/G1) virus infection in smokers. In our study, we used mouse model to investigate the effect of cigarette smoke on pdmH1N1 or H9N2 virus infection. Mice were exposed to cigarette smoke for 21 days and then infected with pdmH1N1 or H9N2 virus. Control mice were exposed to air in parallel. We found that cigarette smoke exposure alone significantly upregulated the lung inflammation. Such prior cigarette smoke exposure significantly reduced the disease severity of subsequent pdmH1N1 or H9N2 virus infection. For pdmH1N1 infection, cigarette smoke exposed mice had significantly lower mortality than the control mice, possibly due to the significantly decreased production of inflammatory cytokines and chemokines. Similarly, after H9N2 infection, cigarette smoke exposed mice displayed significantly less weight loss, which might be attributed to lower cytokines and chemokines production, less macrophages, neutrophils, CD4⁺ and CD8⁺ T cells infiltration and reduced lung damage compared to the control mice. To further investigate the underlying mechanism, we used nicotine to mimic the effect of cigarette smoke both in vitro and in vivo. Pre-treating the primary human macrophages with nicotine for 72 h significantly decreased their expression of cytokines and chemokines after pdmH1N1 or H9N2 infection. The mice subcutaneously and continuously treated with nicotine displayed significantly less weight loss and lower inflammatory response than the control mice upon pdmH1N1 or H9N2 infection. Moreover, α7 nicotinic acetylcholine receptor knockout mice had more body weight loss than wild-type mice after cigarette smoke exposure and H9N2 infection. Our study provided the first evidence that the pathogenicity of both pdmH1N1 and H9N2 viruses was alleviated in cigarette smoke exposed mice, which might partially be attributed to the immunosuppressive effect of nicotine.

Cigarette smoke effects on innate immune mechanisms in the nasal mucosa. Potential effects on the microbiome

It is well established that exposure to cigarette smoke (CS), through active smoking and through exposure to secondhand smoke, has immunosuppressive effects, yet how this might affect the microbiome is not known. In this manuscript we focus on the effects of CS on innate host defense response, with particular emphasis on the role of epithelial cells and mucosal immune responses in the nose and the potential effects on the microbiome. The studies described here briefly summarize the effects of CS on specific innate immune cells, such as neutrophils, macrophages/monocytes, natural killer cells, and dendritic cells. A detailed description of how CS affects epithelial cells and why we consider this to be a central defect in the overall immunosuppressive effects of CS in the lung is provided. We summarize data on the role of the "epimmunome" in the context of CS exposure, including the effects on soluble mediator production, such as cytokines, chemokines, and antimicrobial defense mediators. Separate emphasis is put on the expression of ligands on epithelial cells, which directly interact with receptors on immune cells, and the effects of CS on these interactions. We introduce the nose and nasal mucosa as a model to study the effects of CS exposure on host defense responses and changes in the microbiome in humans in vivo. Understanding the dynamics of a healthy microbiome and how CS affects this balance is important to uncovering the mechanisms of CS-induced disease.

Regulation and activity of secretory leukoprotease inhibitor (SLPI) is altered in smokers

A hallmark of cigarette smoking is a shift in the protease/antiprotease balance, in favor of protease activity. However, it has recently been shown that smokers have increased expression of a key antiprotease, secretory leukoprotease inhibitor (SLPI), yet the mechanisms involved in SLPI transcriptional regulation and functional activity of SLPI remain unclear. We examined SLPI mRNA and protein secretion in differentiated nasal epithelial cells (NECs) and nasal lavage fluid (NLF) from nonsmokers and smokers and demonstrated that SLPI expression is increased in NECs and NLF from smokers. Transcriptional regulation of SLPI expression was confirmed using SLPI promoter reporter assays followed by chromatin immunoprecipitation. The role of STAT1 in regulating SLPI expression was further elucidated using WT and stat1(-/-) mice. Our data demonstrate that STAT1 regulates SLPI transcription in epithelial cells and slpi protein in the lungs of mice. Additionally, we reveal that NECs from smokers have increased STAT1 mRNA/protein expression. Finally, we demonstrate that SLPI contained in the nasal mucosa of smokers is proteolytically cleaved but retains functional activity against neutrophil elastase. These results demonstrate that smoking enhances expression of SLPI in NECs in vitro and in vivo, and that this response is regulated by STAT1. In addition, despite posttranslational cleavage of SLPI, antiprotease activity against neutrophil elastase is enhanced in smokers. Together, our findings show that SLPI regulation and activity is altered in the nasal mucosa of smokers, which could have broad implications in the context of respiratory inflammation and infection.

Culturing of human nasal epithelial cells at the air liquid interface

In vitro models using human primary epithelial cells are essential in understanding key functions of the respiratory epithelium in the context of microbial infections or inhaled agents. Direct comparisons of cells obtained from diseased populations allow us to characterize different phenotypes and dissect the underlying mechanisms mediating changes in epithelial cell function. Culturing epithelial cells from the human tracheobronchial region has been well documented, but is limited by the availability of human lung tissue or invasiveness associated with obtaining the bronchial brushes biopsies. Nasal epithelial cells are obtained through much less invasive superficial nasal scrape biopsies and subjects can be biopsied multiple times with no significant side effects. Additionally, the nose is the entry point to the respiratory system and therefore one of the first sites to be exposed to any kind of air-borne stressor, such as microbial agents, pollutants, or allergens. Briefly, nasal epithelial cells obtained from human volunteers are expanded on coated tissue culture plates, and then transferred onto cell culture inserts. Upon reaching confluency, cells continue to be cultured at the air-liquid interface (ALI), for several weeks, which creates more physiologically relevant conditions. The ALI culture condition uses defined media leading to a differentiated epithelium that exhibits morphological and functional characteristics similar to the human nasal epithelium, with both ciliated and mucus producing cells. Tissue culture inserts with differentiated nasal epithelial cells can be manipulated in a variety of ways depending on the research questions (treatment with pharmacological agents, transduction with lentiviral vectors, exposure to gases, or infection with microbial agents) and analyzed for numerous different endpoints ranging from cellular and molecular pathways, functional changes, morphology, etc. In vitro models of differentiated human nasal epithelial cells will enable investigators to address novel and important research questions by using organotypic experimental models that largely mimic the nasal epithelium in vivo.

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.

DNA methylation in nasal epithelial cells from smokers: identification of ULBP3-related effects

We previously demonstrated that, in nasal epithelial cells (NECs) from smokers, methylation of an antiviral gene was associated with impaired antiviral defense responses. To expand these findings and better understand biological mechanisms underlying cigarette smoke (CS)-induced modifications of host defense responses, we aimed to compare DNA methylation of genes that may play a role in antiviral response. We used a two-tiered analytical approach, where we first implemented a genome-wide strategy. NECs from smokers differed in the methylation levels of 390 genes, the majority (84%) of which showed decreased methylation in smokers. Secondly, we generated an a priori set of 161 antiviral response-related genes, of which five were differentially methylated in NEC from smokers (CCL2, FDPS, GSK3B, SOCS3, and ULBP3). Assessing these genes at the systems biology level revealed a protein interaction network associated with CS-induced epigenetic modifications involving SOCS3 and ULBP3 signaling, among others. Subsequent confirmation studies focused on SOCS3 and ULBP3, which were hypomethylated and hypermethylated, respectively. Expression of SOCS3 was increased, whereas ULBP3 expression was decreased in NECs from smokers. Addition of the demethylating agent 5-Aza-2-deoxycytidine enhanced ULBP3 expression in NECs from smokers. Furthermore, infection of differentiated NECs with influenza virus resulted in significantly lower levels of ULBP3 in cells from smokers. Taken together, our findings show that genomic DNA methylation profiles are altered in NECs from smokers and that these changes are associated with decreased antiviral host defense responses, indicating that epigenenic dysregulation of genes such as SOCS3 and ULBP3 likely impacts immune responses in the epithelium.

Repair and Remodeling of airway epithelium after injury in Chronic Obstructive Pulmonary Disease

COPD is thought to develop as a result of chronic exposure to cigarette smoke, occupational or other environmental hazards and it comprises both airways and parenchyma. Acute infections or chronic colonization of airways with bacteria may also contribute to development and/or progression of COPD lung disease. Airway epithelium is the primary target for the inhaled environmental factors and pathogens. The repetitive injury as a result of chronic exposure to environmental factors may result in persistent activation of pathways involved in airway epithelial repair, such as epithelial to mesenchymal transition, altered migration and proliferation of progenitor cells, and abnormal redifferentiation leading to airway remodeling. Development of model systems which mimics chronic airways disease as observed in COPD is required to understand the molecular mechanisms underlying the abnormal airway epithelial repair that are specific to COPD and to also develop novel therapies focused on airway epithelial repair.

Diesel exhaust particles modify natural killer cell function and cytokine release

Background

Natural killer (NK) cells are an important lymphocyte population in the nasal mucosa and play important roles in linking the innate and the adaptive immune response. Their two main functions are direct cell-mediated cytotoxicity and the release of cytokines. They are important during viral infections and cancer. Due to their location in the nasal mucosa, NK cells are likely exposed to inhaled pollutants, such as diesel exhaust. Whether and how exposure to diesel exhaust particles (DEP) affects NK cell function in the context of viral infections has not been investigated.

Methods

NK cells were isolated from peripheral blood obtained from normal healthy volunteers and subsequently stimulated with the viral mimetic polyinosinic:polycytidylic acid (pI:C), DEP, or pI:C+DEP for 18 hours. NK cells were subsequently analyzed for changes in surface marker expression, cytokine production, gene expression changes, and cytotoxic function using flow cytometry, ELISA, qRT-PCR, and cell-mediated cytotoxicity assay, respectively.

Results

Stimulation of NK cells with pI:C and pI:C+DEP, but not DEP alone, increased the release of IL-1β, IL-2, IL-4, IL-8, IL-10, IL-12p70, IFN-γ and TNF-α. As compared to pI:C alone or pI:C+DEP, the release of IL-1β, IL-8 and TNF-α was significantly lower after DEP stimulation alone. Stimulation with pI:C alone increased the gene and protein expression of granzyme B and perforin, which was completely blunted by adding DEP. Addition of DEP further reduced CD16 expression in pI:C stimulated cells. Similarly, cell-mediated cytotoxicity was significantly reduced by the addition of DEP.

Conclusions

In the context of viral infection, DEP potentially reduces NK cells' ability to kill virus-infected host cells, in spite of normal cytokine levels, and this may increase susceptibility to viral infections . This reduction in the potential ability of NK cells to kill virus-infected host cells may increase the susceptibility to viral infections after DEP exposure.

Ozone exposed epithelial cells modify cocultured natural killer cells

Ozone (O3) causes significant adverse health effects worldwide. Nasal epithelial cells (NECs) are among the first sites within the respiratory system to be exposed to inhaled air pollutants. They recruit, activate, and interact with immune cells via soluble mediators and direct cell-cell contacts. Based on our recent observation demonstrating the presence of natural killer (NK) cells in nasal lavages, the goal of this study was to establish a coculture model of NECs and NK cells and examine how exposure to O3 modifies this interaction. Flow cytometry analysis was used to assess immunophenotypes of NK cells cocultured with either air- or O3-exposed NECs. Our data show that coculturing NK cells with O3-exposed NECs decreased intracellular interferon-γ (IFN-γ), enhanced, albeit not statistically significant, IL-4, and increased CD16 expression on NK cells compared with air controls. Additionally, the cytotoxicity potential of NK cells was reduced after coculturing with O3-exposed NECs. To determine whether soluble mediators released by O3-exposed NECs caused this shift, apical and basolateral supernatants of air- and O3-exposed NECs were used to stimulate NK cells. While the conditioned media of O3-exposed NECs alone did not reduce intracellular IFN-γ, O3 enhanced the expression of NK cell ligands ULBP3 and MICA/B on NECs. Blocking ULBP3 and MICA/B reversed the effects of O3-exposed NECs on IFN-γ production in NK cells. Taken together, these data showed that interactions between NECs and NK cells in the context of O3 exposure changes NK cell activity via direct cell-cell interactions and is dependent on ULBP3/MICA/B expressed on NECs.

Sulforaphane induces SLPI secretion in the nasal mucosa

Cells lining the respiratory tract are equipped with mechanisms that dampen the effects of oxidative stress. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a mediator involved in regulating oxidative stress. Recent data indicate Nrf2 also controls expression of secretory leukocyte protease inhibitor (SLPI). Sulforaphane (SFN), an isothiocyanate found in cruciferous vegetables, enhances Nrf2 activity. Therefore, we hypothesized that SFN supplementation induces SLPI secretion in the nasal mucosa in an Nrf2 dependent manner. Healthy nonsmoking adults ingested SFN-containing broccoli shake homogenate (BSH) for 3 consecutive days. Nasal lavage fluid (NLF) was collected before and after BSH ingestion and analyzed for SLPI protein levels. In follow up in vitro experiments, differentiated primary nasal epithelial cells were used to evaluate the relationship between SFN, Nrf2, and SLPI. Epithelial cells were transduced with Nrf2-specific shRNA to examine the regulatory role of Nrf2 on SLPI expression. Supplementation with BSH significantly increased SLPI levels in NLF. SFN supplementation in vitro significantly enhanced SLPI secretion and these effects were significantly decreased in cells transduced with Nrf2-specific shRNA. Our data support a relationship between nutritional supplementation, Nrf2 activation, and SLPI secretion. Therefore, ingestion of SFN-containing foods has therapeutic potential to augment SLPI expression in the nasal mucosa.

Localized mucosal response to intranasal live attenuated influenza vaccine in adults

BACKGROUND

Influenza virus infection is a major public health burden worldwide. Available vaccines include the inactivated intramuscular trivalent vaccine and, more recently, an intranasal live attenuated influenza vaccine (LAIV). The measure of successful vaccination with the inactivated vaccine is a systemic rise in immunoglobulin G (IgG) level, but for the LAIV no such correlate has been established.

METHODS

Seventy-nine subjects were given the LAIV FluMist. Blood was collected prior to vaccination and 3 days and 30 days after vaccination. Nasal wash was collected 3 days and 30 days after vaccination. Responses were measured systemically and in mucosal secretions for cytokines, cell activation profiles, and antibody responses.

RESULTS

Only 9% of subjects who received LAIV seroconverted, while 33% of patients developed at least a 2-fold increase in influenza virus-specific immunoglobulin A (IgA) antibodies in nasal wash. LAIV induced a localized inflammation, as suggested by increased expression of interferon-response genes in mucosal RNA and increased granulocyte colony-stimulating factor (G-CSF) and IP-10 in nasal wash. Interestingly, patients who seroconverted had significantly lower serum levels of G-CSF before vaccination.

CONCLUSIONS

Protection by LAIV is likely provided through mucosal IgA and not by increases in systemic IgG. LAIV induces local inflammation. Seroconversion is achieved in a small fraction of subjects with a lower serum G-CSF level.

Airway protease/antiprotease imbalance in atopic asthmatics contributes to increased influenza A virus cleavage and replication

Asthmatics are more susceptible to influenza infections, yet mechanisms mediating this enhanced susceptibility are unknown. Influenza virus hemagglutinin (HA) protein binds to sialic acid residues on the host cells. HA requires cleavage to allow fusion of the viral HA with host cell membrane, which is mediated by host trypsin-like serine protease. We show data here demonstrating that the protease:antiprotease ratio is increased in the nasal mucosa of asthmatics and that these changes were associated with increased proteolytic activation of influenza. These data suggest that disruption of the protease balance in asthmatics enhances activation and infection of influenza virus.

Cigarette smoking as a risk factor for influenza-associated mortality: evidence from an elderly cohort

Please cite this paper as: Wong et al. (2012) Cigarette smoking as a risk factor for influenza‐associated mortality: evidence from an elderly cohort. Influenza and Other Respiratory Viruses 7(4), 531–539.

Background  The effects of individual lifestyle factors on the mortality risk after influenza infection have not been explored.

Objectives  In this study, we assessed the modifying effects of cigarette smoking on mortality risks associated with influenza in a cohort of Hong Kong elders with a follow‐up period of 1998–2009.

Methods  We used the Cox proportional hazards model with time‐dependent covariates of weekly proportions of specimens positive for influenza (termed as influenza virus activity), to calculate the hazard ratio of mortality associated with a 10% increase in influenza virus activity for never, ex‐ and current smokers. Other individual lifestyle and socioeconomic factors as well as seasonal confounders were also added into the models.

Results  The overall hazard ratio associated with influenza was 1·028 (95% confidence interval, 1·006, 1·051) for all natural cause mortality and 1·035 (1·003, 1·068) for cardiovascular and respiratory mortality. We found that influenza‐associated hazard ratio was greater in current and ex‐smokers than in never smokers for mortality of all natural causes, cardiovascular and respiratory diseases.

Conclusions  The findings suggest that smoking might increase influenza‐associated mortality risks among elders.

Alteration of the nasal responses to influenza virus by tobacco smoke

PURPOSE OF REVIEW

The purpose of this review is to highlight recent data regarding the impact of exposure to tobacco smoke on influenza virus infection. This is timely because of the continuing pattern for influenza to cause epidemics and pandemics.

RECENT FINDINGS

Experimental animal studies suggest tobacco smoke increases severity of respiratory disease with influenza. The interaction is complex and dependent on dose and chronicity of both virus and smoke exposure. Smoke-induced oxidant stress and suppression of innate immunity are mechanistic factors leading to worse disease. Experiments using human respiratory cells show that tobacco smoke increases viral replication through mechanisms including suppression of antiviral pathways and altered cytokine patterns in cell types with central roles in mucosal innate immunity, such as epithelium, dendritic cells, and natural killer cells. Studies also suggest a role for antioxidant strategies in reducing risk. Human volunteer studies using live attenuated influenza virus as a model appear to corroborate many of these findings.

SUMMARY

Exposure to tobacco smoke remains extremely prevalent worldwide. Although avoidance of exposure is a primary goal, it is important to understand the mechanisms underlying increased infection risk with tobacco smoke and other pollutant exposures, so that novel preventive or treatment strategies can be developed.

Live attenuated influenza virus (LAIV) induces different mucosal T cell function in nonsmokers and smokers

Smokers are more susceptible to respiratory infections, including influenza. To explore the effect of smoking on influenza-induced responses within the nasal mucosa, we have developed a protocol using inoculation with live attenuated influenza virus (LAIV) vaccine followed by sampling of the nasal mucosa. Mucosal cell populations were harvested through superficial biopsy of the nasal inferior turbinate pre and post LAIV inoculation and analyzed using flow cytometry. The majority of nasal biopsy CD45+ immune cells at baseline were CD3+ T lymphocytes. Following LAIV, these lymphocytes increased in nonsmokers but not in smokers. A subset of individuals was negative for helper T cell marker CD4 and cytotoxic T cell marker CD8 but positive for the γδ T cell receptor (TCR). Increases in γδ TCR+ cells were greater in nonsmokers, than in smokers. Thus, LAIV-induced changes in CD3 T as well as γδ T lymphocyte percentages are suppressed in smokers compared to nonsmokers.

Diesel exhaust exposure and nasal response to attenuated influenza in normal and allergic volunteers

RATIONALE

Diesel exhaust enhances allergic inflammation, and pollutants are associated with heightened susceptibility to viral respiratory infections. The effects of combined diesel and virus exposure in humans are unknown.

OBJECTIVES

Test whether acute exposure to diesel modifies inflammatory responses to influenza virus in normal humans and those with allergies.

METHODS

We conducted a double-blind, randomized, placebo-controlled study of nasal responses to live attenuated influenza virus in normal volunteers and those with allergic rhinitis exposed to diesel (100 μg/m(3)) or clean air for 2 hours, followed by standard dose of virus and serial nasal lavages. Endpoints were inflammatory mediators (ELISA) and virus quantity (quantitative reverse-transcriptase polymerase chain reaction). To test for exposure effect, we used multiple regression with exposure group (diesel vs. air) as the main explanatory variable and allergic status as an additional factor.

MEASUREMENTS AND MAIN RESULTS

Baseline levels of mediators did not differ among groups. For most postvirus nasal cytokine responses, there was no significant diesel effect, and no significant interaction with allergy. However, diesel was associated with significantly increased IFN-γ responses (P = 0.02), with no interaction with allergy in the regression model. Eotaxin-1 (P = 0.01), eosinophil cationic protein (P < 0.01), and influenza RNA sequences in nasal cells (P = 0.03) were significantly increased with diesel exposure, linked to allergy.

CONCLUSIONS

Short-term exposure to diesel exhaust leads to increased eosinophil activation and increased virus quantity after virus inoculation in those with allergic rhinitis. This is consistent with previous literature suggesting a diesel "adjuvant" effect promoting allergic inflammation, and our data further suggest this change may be associated with reduced virus clearance.Clinical trial registered with www.clinicaltrials.gov (NCT00617110).

Nasal lavage natural killer cell function is suppressed in smokers after live attenuated influenza virus

Background

Modified function of immune cells in nasal secretions may play a role in the enhanced susceptibility to respiratory viruses that is seen in smokers. Innate immune cells in nasal secretions have largely been characterized by cellular differentials using morphologic criteria alone, which have successfully identified neutrophils as a significant cell population within nasal lavage fluid (NLF) cells. However, flow cytometry may be a superior method to fully characterize NLF immune cells. We therefore characterized immune cells in NLF by flow cytometry, determined the effects of live attenuated influenza virus (LAIV) on NLF and peripheral blood immune cells, and compared responses in samples obtained from smokers and nonsmokers.

Methods

In a prospective observational study, we characterized immune cells in NLF of nonsmokers at baseline using flow cytometry and immunohistochemistry. Nonsmokers and smokers were inoculated with LAIV on day 0 and serial nasal lavages were collected on days 1-4 and day 9 post-LAIV. LAIV-induced changes of NLF cells were characterized using flow cytometry. Cell-free NLF was analyzed for immune mediators by bioassay. Peripheral blood natural killer (NK) cells from nonsmokers and smokers at baseline were stimulated in vitro with LAIV followed by flow cytometric and mediator analyses.

Results

CD45(+)CD56(-)CD16(+) neutrophils and CD45(+)CD56(+) NK cells comprised median 4.62% (range 0.33-14.52) and 23.27% (18.29-33.97), respectively, of non-squamous NLF cells in nonsmokers at baseline. LAIV did not induce changes in total NK cell or neutrophil percentages in either nonsmokers or smokers. Following LAIV inoculation, CD16(+) NK cell percentages and granzyme B levels increased in nonsmokers, and these effects were suppressed in smokers. LAIV inoculation enhanced expression of activating receptor NKG2D and chemokine receptor CXCR3 on peripheral blood NK cells from both nonsmokers and smokers in vitro but did not induce changes in CD16(+) NK cells or granzyme B activity in either group.

Conclusions

These data are the first to identify NK cells as a major immune cell type in the NLF cell population and demonstrate that mucosal NK cell cytotoxic function is suppressed in smokers following LAIV. Altered NK cell function in smokers suggests a potential mechanism that may enhance susceptibility to respiratory viruses.

Nrf2 expression modifies influenza A entry and replication in nasal epithelial cells

Influenza infection is a major cause of morbidity and mortality worldwide, especially during pandemics outbreaks. Emerging data indicate that phase II antioxidant enzyme pathways could play a role in virus-associated inflammation and immune clearance. While Nrf2-dependent gene expression is known to modify inflammation, a mechanistic role in viral susceptibility and clearance has yet to be elucidated. Therefore, we utilized differentiated human nasal epithelial cells (NEC) and an enzymatic virus-like particle entry assay, to examine the role Nrf2-dependent gene expression has on viral entry and replication. Herein, lentiviral vectors that express Nrf2-specific short hairpin (sh)-RNA effectively decreased both Nrf2 mRNA and Nrf2 protein expression in transduced human NEC from healthy volunteers. Nrf2 knockdown correlated with a significant increase in influenza virus entry and replication. Conversely, supplementation with the potent Nrf2 activators sulforaphane (SFN) and epigallocatechin gallate (EGCG) significantly decreased viral entry and replication. The suppressive effects of EGCG on viral replication were abolished in cells with knocked-down Nrf2 expression, suggesting a causal relationship between the EGCG-induced activation of Nrf2 and the ability to protect against viral infection. Interestingly, the induction of Nrf2 via nutritional supplements SFN and EGCG increased antiviral mediators/responses: RIG-I, IFN-β, and MxA at baseline in the absence of infection. Our data indicate that there is an inverse relationship between the levels of Nrf2 expression and the viral entry/replication. We also demonstrate that supplementation with Nrf2-activating antioxidants inhibits viral replication in human NEC, which may prove to be an attractive therapeutic intervention. Taken together, these data indicate potential mechanisms by which Nrf2-dependent gene expression regulates susceptibility to influenza in human epithelial cells.