Inhibition by cigarette smoke of nuclear factor-κB-dependent response to bacteria in the airway

Analysis of tobacco exposures and high-risk HPV infection in American women: National Health and Nutrition Examination Survey

Nicotine is a known toxin, but its relationship with cervicovaginal high-risk human papillomavirus (HR-HPV) infection is uncertain. This study aimed to investigate whether tobacco exposure is associated with elevated cervicovaginal HR-HPV infection in US women, and if the strength of this association varies with the degree of exposure. Cross-sectional data from the 2011-2016 National Health and Nutrition Examination Survey (NHANES), which included a nationally representative sample of US women, were used for the study. Out of 12436 women aged 18-59 who participated in the interview, 3833 were ultimately enrolled in this study. Weighted logistic regression was used to estimate the link between tobacco exposure and cervicovaginal HR-HPV infection. The mean age of participants was 38.6 (SD 12.1) years, and non-Hispanic White individuals accounted for 37.3% of the sample. Those with any tobacco exposure tended to be younger (mean age 37.7 [SD 12.4] years vs 40.3 [11.2] years), non-Hispanic Black (27.8% vs. 15.1%), lower educated (41.8% vs. 29.4%), and have lower family income (39.9% vs. 23.5%). After adjustment, the odds of having HR-HPV infection were 1.32 (95% CI, 1.09-1.59) for those exposed to tobacco, remaining significant in multiple sensitivity analyses and across subgroups. This study, based on a nationally representative sample from the United States, suggests that tobacco exposure is a risk factor for elevated HR-HPV infection in women, highlighting the need for further research into reducing this modifiable risk factor.

Conventional, Complementary and Alternative Medicines: Mechanistic Insights into Therapeutic Landscape of Chronic Obstructive Pulmonary Disease

COPD (chronic obstructive pulmonary disease) is a major public health concern associated with significant morbidity and mortality worldwide. Current therapeutic guidelines for this disease recommend starting with an inhaled bronchodilator, stepping up to combination therapy as necessary, and/or adding inhaled corticosteroids as symptoms and airflow obstruction progress. However, no drug therapy exists to stop disease progression. The mechanistic definition underlying COPD pathogenesis remains poorly understood, it is generally accepted that oxidative stress and the altered immune response of low-grade airway inflammation are major factors contributing to COPD development. There are several potential therapeutic targets that are currently under investigation, including immune regulatory pathways in inflammation and lung-associated steroid resistance induced by oxidative stress signaling cascades. Patients with COPD have increased levels of inflammatory mediators, including lipid and peptide mediators, as well as a network of cytokines and chemokines that maintain inflammatory immune response and recruit circulating cells into the lungs. Many of these pro-inflammatory mediators are regulated by nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinases (MAPKs), such as p38 MAPK. Increased oxidative stress is a key driving mechanism in perpetuating inflammation and lung injury. Furthermore, many proteases that degrade elastin fibres are secreted by airway resident infiltrating immune cells in COPD patients. In this perspective, we discuss novel aspects of signaling pathway activation in the context of inflammation and oxidative stress, and the broad view of potential effective pharmacotherapies that target the underlying mechanistic disease process in COPD.

Inflammasome involvement in CS-induced damage in HaCaT keratinocytes

Cigarette smoke (CS) alters cutaneous biological processes such as redox homeostasis and inflammation response that might be involved in promoting skin inflammatory conditions. Exposure to CS has also been linked to a destabilization of the NLRP3 inflammasome in pollution target tissues such as the lung epithelium, resulting in a more vulnerable immunological response to several exogenous and endogenous stimuli related to oxidative stress. Thus, CS has an adverse effect on host defense, increasing the susceptibility to develop lung infections and pathologies. In the skin, another direct target of pollution, inflammasome disorders have been linked to an increasing number of diseases such as melanoma, psoriasis, vitiligo, atopic dermatitis, and acne, all conditions that have been connected directly or indirectly to pollution exposure. The inflammasome machinery is an important innate immune sensor in human keratinocytes. However, the role of CS in the NLRP1 and NLRP3 inflammasome in the cutaneous barrier has still not been investigated. In the present study, we were able to determine in keratinocytes exposed to CS an increased oxidative damage evaluated by 4-HNE protein adduct and carbonyl formation. Of note is that, while CS inhibited NLRP3 activation, it was able to activate NLRP1, leading to an increased secretion of the proinflammatory cytokines IL-1β and IL-18. This study highlights the importance of the inflammasome machinery in CS that more in general, in pollution, affects cutaneous tissues and the important cross-talk between different members of the NLRP inflammasome family.

Tobacco use disorder and the lungs

This narrative review provides a summary of the impact of tobacco smoking on the respiratory system and the benefits of smoking cessation. Tobacco smoking is one of the leading preventable causes of death world-wide and a major risk factor for lung cancer and chronic obstructive pulmonary disease. Smoking is also associated with an increased risk of respiratory infections and appears to be related to poorer outcomes among those with COVID-19. Non-smokers with second-hand smoke exposure also experience significant adverse respiratory effects. Smoking imposes enormous health- and non-health-related costs to societies. The benefits of smoking cessation, in both prevention and management of respiratory disease, have been known for decades and, to this day, cessation support remains one of the most important cost-effective interventions that health professionals can provide to people who smoke. Cessation at any age confers substantial health benefits, even in smokers with established morbidities. As other treatments for chronic respiratory disease advance and survival rates increase, smoking cessation treatment will become even more relevant. While smoking cessation interventions are available, the offer of these by clinicians and uptake by patients remain limited.

Chronic Obstructive Pulmonary Disease: Epidemiology, Biomarkers, and Paving the Way to Lung Cancer

Chronic obstructive pulmonary disease (COPD), the frequently fatal pathology of the respiratory tract, accounts for half a billion cases globally. COPD manifests via chronic inflammatory response to irritants, frequently to tobacco smoke. The progression of COPD from early onset to advanced disease leads to the loss of the alveolar wall, pulmonary hypertension, and fibrosis of the respiratory epithelium. Here, we focus on the epidemiology, progression, and biomarkers of COPD with a particular connection to lung cancer. Dissecting the cellular and molecular players in the progression of the disease, we aim to shed light on the role of smoking, which is responsible for the disease, or at least for the more severe symptoms and worse patient outcomes. We summarize the inflammatory conditions, as well as the role of EMT and fibroblasts in establishing a cancer-prone microenvironment, i.e., the soil for ‘COPD-derived’ lung cancer. We highlight that the major health problem of COPD can be alleviated via smoking cessation, early diagnosis, and abandonment of the usage of biomass fuels on a global basis.

Particulate air pollution and respiratory Haemophilus influenzae infection in Mianyang, southwest China

Particulate air pollution is correlated with many respiratory diseases. However, few studies have focused on the relationship between air particulate exposure and respiratory Heamophilus influenzae infection. Therefore, we detected respiratory Heamophilus influenzae infection by bacterial culture of sputum of patients, and we collected particulate air pollution data (including PM2.5 and PM10) from a national real-time urban air quality platform to analyze the relationship between particulate air pollution and respiratory Heamophilus influenzae infection. The mean concentrations of PM2.5 and PM10 were 37.58 μg/m3 and 58.44 μg/m3, respectively, showing particulate air pollution remains a severe issue in Mianyang. A total of 828 strains of Heamophilus influenzae were detected in sputum by bacterial culture. Multiple correspondence analysis suggested the heaviest particulate air pollution and the highest Heamophilus influenzae infection rates were all in winter, while the lowest particulate air pollution and the lowest Heamophilus influenzae infection rates were all in summer. In a single-pollutant model, each elevation of 10 μg/m3 of PM2.5, PM10, and PM2.5/10 (combined exposure level) increased the risk of respiratory Heamophilus influenzae infection by 34%, 23%, and 29%, respectively. Additionally, in the multiple-pollutant model, only PM2.5 was significantly associated with respiratory Heamophilus influenzae infection (B, 0.46; 95% confidence interval, 0.05-0.87), showing PM2.5 is an independent risk factor for respiratory Heamophilus influenzae infection. In summary, this study highlights air particulate exposure could increase the risk of respiratory Heamophilus influenzae infection, implying that stronger measures need to be taken to protect against respiratory infection induced by particulate air pollution.

How Do Innate Immune Cells Contribute to Airway Remodeling in COPD Progression?

Recently, the therapeutic potential of immune-modulation during the progression of chronic obstructive pulmonary disease (COPD) has been attracting increasing interest. However, chronic inflammatory response has been over-simplified in descriptions of the mechanism of COPD progression. As a form of first-line airway defense, epithelial cells exhibit phenotypic alteration, and participate in epithelial layer disorganization, mucus hypersecretion, and extracellular matrix deposition. Dendritic cells (DCs) exhibit attenuated antigen-presenting capacity in patients with advanced COPD. Immature DCs migrate into small airways, where they promote a pro-inflammatory microenvironment and bacterial colonization. In response to damage-associated molecular patterns (DAMPs) in lung tissue affected by COPD, neutrophils are excessively recruited and activated, where they promote a proteolytic microenvironment and fibrotic repair in small airways. Macrophages exhibit decreased phagocytosis in the large airways, while they demonstrate high pro-inflammatory potential in the small airways, and mediate alveolar destruction and chronic airway inflammation. Natural killer T (NKT) cells, eosinophils, and mast cells also play supplementary roles in COPD progression; however, their cellular activities are not yet entirely clear. Overall, during COPD progression, “exhausted” innate immune responses can be observed in the large airways. On the other hand, the innate immune response is enhanced in the small airways. Approaches that inhibit the inflammatory cascade, chemotaxis, or the activation of inflammatory cells could possibly delay the progression of airway remodeling in COPD, and may thus have potential clinical significance.

Cigarette smoke preparations, not moist snuff, impair expression of genes involved in immune signaling and cytolytic functions

Cigarette smoke-induced chronic inflammation is associated with compromised immune responses. To understand how tobacco products impact immune responses, we assessed transcriptomic profiles in peripheral blood mononuclear cells (PBMCs) pretreated with Whole Smoke-Conditioned Medium (WS-CM) or Smokeless Tobacco Extracts (STE), and stimulated with lipopolysaccharide, phorbol myristate and ionomycin (agonists). Gene expression profiles from PBMCs treated with low equi-nicotine units (0.3 μg/mL) of WS-CM and one high dose of STE (100 μg/mL) were similar to those from untreated controls. Cells treated with medium and high doses of WS-CM (1.0 and 3.0 μg/mL) exhibited significantly different gene expression profiles compared to the low WS-CM dose and STE. Pre-treatment with higher doses of WS-CM inhibited the expression of several pro-inflammatory genes (IFNγ, TNFα, and IL-2), while CSF1-R and IL17RA were upregulated. Pre-treatment with high doses of WS-CM abolished agonist-stimulated secretion of IFNγ, TNF and IL-2 proteins. Pathway analyses revealed that higher doses of WS-CM inhibited NF-ĸB signaling, immune cell differentiation and inflammatory responses, and increased apoptotic pathways. Our results show that pre-treatment of PBMCs with higher doses of WS-CM inhibits immune activation and effector cytokine expression and secretion, resulting in a reduced immune response, whereas STE exerted minimal effects.

Effects of extracellular Hsp70 and cigarette smoke on differentiated THP-1 cells and human monocyte-derived macrophages

Extracellular Hsp70 (eHsp70) can act as pro-inflammatory mediator and is elevated in blood of chronic obstructive pulmonary disease (COPD) patients. Most of those patients are smokers, and it was suggested previously that cigarette smoke might induce Hsp70 secretion from the circulating cells. Therefore, we aimed to explore inflammation-associated effects of cigarette smoke extract (CSE) and its combinations with eHsp70 in monocyte-derived macrophages (MDMs) and THP-1 cell line, used as systemic component models of COPD. We hypothesized that eHsp70 induces inflammation, but that it can also modulate cigarette smoke extract (CSE)-stimulated inflammatory responses. We assessed IL-8 secretion, TLR2, TLR4 and Hsp70 expressions, MAPKs and NF-κB activation, and cytotoxicity after treating the cells with CSE (2.5 and 5%) and its combinations with low-endotoxin recombinant human (rh) Hsp70, used to mimic eHsp70 effects. CSE induced IL-8 secretion from both cell types, but its combinations with rhHsp70 increased IL-8 release compared to CSE alone only from MDMs. In THP-1, combinations of rhHsp70 with 2.5% CSE induced TLR2 and TLR4 mRNA, while 5% CSE decreased TLR2 expression. In MDMs, CSE alone attenuated TLR2, while rhHsp70 increased TLR2 and lowered TLR4 gene expression. Hsp70 mRNA expression was suppressed in THP-1 with rhHsp70 and CSE; however, the same treatments increased its level in MDMs. CSE had cytotoxic effect only on MDMs, but cytotoxicity was reduced in co-treatments with rhHsp70, which also triggered apoptosis. CSE and rhHsp70 activated p38 and JNK, while ERK was activated only by rhHsp70 in MDMs. In THP-1, 2.5% CSE activated ERK, and 5% CSE activated p38. Inhibition of NF-κB and JNK in MDMs, and ERK and JNK in THP-1 cells, attenuated IL-8 release after rhHsp70 treatment. In conclusion, rhHsp70 provoked pro-inflammatory effects and could also modulate inflammatory response to CSE on protein and gene expression levels in THP-1 cells and MDMs, which suggests that eHsp70 might be implicated in systemic inflammation induced by cigarette smoke.

Extracellular Hsp70 modulates the inflammatory response of cigarette smoke extract in NCI-H292 cells

NEW FINDINGS

What is the central question of this study? Does extracellular heat shock protein 70 (eHsp70) alter cigarette smoke extract (CSE)-induced inflammatory responses in NCI-H292 bronchial epithelial cells? What is the main finding and its importance? eHsp70 modulates inflammatory responses and TLR2, TLR4 and Hsp70 gene expression, and protects NCI-H292 cells against CSE-induced cytotoxicity. eHsp70 might be implicated in development of inflammatory diseases affected by cigarette smoke, such as COPD.

ABSTRACT

One of the major risk factors for development of chronic obstructive pulmonary disease (COPD) is cigarette smoke. Extracellular Hsp70 (eHsp70) is increased in sera of COPD patients, and can act as damage-associated molecular pattern (DAMP). In this study, we explored inflammatory parameters (cytokine concentrations, Toll-like receptor (TLR) 2 and 4 and Hsp70 expression, mitogen-activated protein kinases (MAPKs) and nuclear factor κB (NF-κB) activation, and cytotoxicity) after exposure of bronchial-epithelial NCI-H292 cells to cigarette smoke extract (CSE) alone (2.5 and 15%) and in combinations with recombinant human (rh) Hsp70 (0.3, 1 and 3 μg ml^-1 ). We applied specific MAPKs, NF-κB and Hsp70 inhibitors to elucidate rhHsp70 inflammation-associated responses. CSE alone and combinations of 15% CSE with rhHsp70 stimulated IL-1α, IL-6 and IL-8 release. However, rhHsp70 applied with 2.5% CSE decreased secretion of cytokines indicating antagonistic effects. Individual and combined treatments with 2.5% CSE suppressed TLR2 expression. CSE at 15% induced TLR2 and TLR4 gene expression, whereas rhHsp70 abolished that effect. rhHsp70 and 15% CSE alone reduced, while their combination increased, intracellular Hsp70 mRNA level. CSE alone and in combination with rhHsp70 activated extracellular signal-regulated kinase and p38 MAPKs, while inhibition of MAPKs, NF-κB and Hsp70 attenuated IL-6 and IL-8 secretion. CSE at 15% reduced cell viability and induced apoptosis, as shown by MTS and caspases-3/7 assays. CSE at 2.5% alone stimulated lactate dehydrogenase release, but cellular membrane integrity remained intact in co-treatments with rhHsp70. rhHsp70 might modulate the inflammatory response of CSE and could also protect NCI-H292 cells against CSE cytotoxicity. Those effects are implemented via MAPK and NF-κB signalling pathways.

Nontypeable Haemophilus influenzae-Promoted Proliferation of Kras-Induced Early Adenomatous Lesions Is Completely Dependent on Toll-Like Receptor Signaling

Chronic obstructive pulmonary disease (COPD) is a risk factor for lung cancer. COPD is characterized by chronic airway inflammation and lung infections. The airways of patients with COPD are frequently colonized with bacteria [eg, nontypeable Haemophilus influenzae (NTHi)] that cause pulmonary inflammation and exacerbations. Pulmonary adenocarcinomas are frequently associated with an activating mutation in the KRAS gene. We determined the function of Toll-like receptor (TLR) signaling on the progression of Kras-induced early adenomatous lesions in the lung. Wild-type (WT) mice and mice doubly deficient in Tlr-2 and -4 (Tlr2/4^-/-), both with an oncogenic Kras allele in lung epithelium, were exposed to NTHi for 4 weeks. Exposure to NTHi resulted in increased tumor proliferation and growth in WT mice, but not in Tlr2/4^-/- mice. Alveolar adenomatous hyperplasia and adenocarcinoma were significantly increased in WT mice compared with Tlr2/4^-/- mice. The average size of tumors was significantly larger in WT mice, whereas there was no difference in the number of alveolar lesions between WT and Tlr2/4^-/- mice. NTHi-induced pulmonary neutrophilic inflammation and tumor-associated neutrophils were reduced in Tlr2/4^-/- mice. Thus, subsequent to a driver mutation, NTHi-induced inflammation promotes proliferation of early adenomatous lesions in a TLR-dependent manner.

Impacts of cigarette smoking on immune responsiveness: Up and down or upside down?

Cigarette smoking is associated with numerous diseases and poses a serious challenge to the current healthcare system worldwide. Smoking impacts both innate and adaptive immunity and plays dual roles in regulating immunity by either exacerbation of pathogenic immune responses or attenuation of defensive immunity. Adaptive immune cells affected by smoking mainly include T helper cells (Th1/Th2/Th17), CD4+CD25+ regulatory T cells, CD8+ T cells, B cells and memory T/B lymphocytes while innate immune cells impacted by smoking are mostly DCs, macrophages and NK cells. Complex roles of cigarette smoke have resulted in numerous diseases, including cardiovascular, respiratory and autoimmune diseases, allergies, cancers and transplant rejection etc. Although previous reviews have described the effects of smoking on various diseases and regional immunity associated with specific diseases, a comprehensive and updated review is rarely seen to demonstrate impacts of smoking on general immunity and, especially on major components of immune cells. Here, we aim to systematically and objectively review the influence of smoking on major components of both innate and adaptive immune cells, and summarize cellular and molecular mechanisms underlying effects of cigarette smoking on the immune system. The molecular pathways impacted by cigarette smoking involve NFκB, MAP kinases and histone modification. Further investigations are warranted to understand the exact mechanisms responsible for smoking-mediated immunopathology and to answer lingering questions over why cigarette smoking is always harmful rather than beneficial even though it exerts dual effects on immune responses.

The Anti-inflammatory Effect of Alpha-1 Antitrypsin in Rhinovirus-infected Human Airway Epithelial Cells

OBJECTIVE

Excessive airway inflammation is seen in chronic obstructive pulmonary disease (COPD) patients experiencing acute exacerbations, which are often associated with human rhinovirus (HRV) infection. Alpha-1 antitrypsin (A1AT) has anti-inflammatory function in endothelial cells and monocytes, but its anti-inflammatory effect has not been investigated in COPD airway epithelial cells. We determined A1AT's anti-inflammatory function in COPD airway epithelial cells and the underlying mechanisms such as the role of caspase-1.

METHODS

Brushed bronchial epithelial cells from COPD and normal subjects were cultured at air-liquid interface and treated with A1AT or bovine serum albumin (BSA, control) two hours prior to whole cigarette smoke (WCS) or air exposure, followed by HRV-16 infection. After 24 hours of viral infection, cell supernatants were collected for measuring IL-8, and cells were examined for caspase-1. The in vivo anti-inflammatory function of A1AT was determined by infecting mice intranasally with HRV-1B followed by aerosolized A1AT or BSA.

RESULTS

A1AT significantly reduced WCS and HRV-16-induced IL-8 production in normal and COPD airway epithelial cells. COPD cells are less sensitive to A1AT's anti-inflammatory effect than normal cells. A1AT exerted the anti-inflammatory function in part via reducing caspase-1 in normal cells, but not in COPD cells. In mice, A1AT significantly reduced HRV-1B induced lung neutrophilic inflammation.

CONCLUSIONS

A1AT exerts an anti-inflammatory effect in cigarette smoke-exposed and HRV-infected human airway epithelial cells, which may be related to its inhibitory effect on caspase-1 activity.

Effects of ceftaroline on the innate immune and on the inflammatory responses of bronchial epithelial cells exposed to cigarette smoke

The tobacco smoking habit interferes with the innate host defence system against infections. Recurrent infections accelerated the functional respiratory decline. The present study assessed the effects of ceftaroline on TLR2 and TLR4 and on pro-inflammatory responses in airway epithelial cells (16HBE cell line and primary bronchial epithelial cells) with or without cigarette smoke extracts (CSE 10%). TLR2, TLR4, LPS binding and human beta defensin 2 (HBD2) were assessed by flow cytometry, NFkB nuclear translocation by western blot analysis, IL-8 and HBD2 mRNA by Real Time PCR; the localization of NFkB on the HBD2 and IL-8 promoters by ChiP Assay. CSE increased TLR4, TLR2 expression, LPS binding and IL-8 mRNA; CSE decreased HBD2 (protein and mRNA), activated NFkB and promoted the localization of NFkB on IL-8 promoter and not on HBD2 promoter. Ceftaroline counteracted the CSE effect on TLR2 expression, on LPS binding, on IL-8 mRNA, HBD2 and NFkB in 16HBE. The effects of ceftaroline on HBD2 protein and on IL-8 mRNA were confirmed in primary bronchial epithelial cells. In conclusion, ceftaroline is able to counteract the effects of CSE on the innate immunity and pro-inflammatory responses modulating TLR2, LPS binding, NFkB activation and activity, HBD2 and IL-8 expression in bronchial epithelial cells.

Cigarette smoke-promoted acquisition of bacterial pathogens in the upper respiratory tract leads to enhanced inflammation in mice

BACKGROUND

Bacterial colonization and recurrent infections of the respiratory tract contribute to the progression of chronic obstructive pulmonary disease (COPD). There is evidence that exacerbations of COPD are provoked by new bacterial strains acquired from the environment. Using a murine model of colonization, we examined whether chronic exposure to cigarette smoke (CS) promotes nasopharyngeal colonization with typical lung pathogens and whether colonization is linked to inflammation in the respiratory tract.

METHODS

C57BL/6 N mice were chronically exposed to CS. The upper airways of mice were colonized with nontypeable Haemophilus influenzae (NTHi) or Streptococcus pneumoniae. Bacterial colonization was determined in the upper respiratory tract and lung tissue. Inflammatory cells and cytokines were determined in lavage fluids. RT-PCR was performed for inflammatory mediators.

RESULTS

Chronic CS exposure resulted in significantly increased numbers of viable NTHi in the upper airways, whereas NTHi only marginally colonized air-exposed mice. Colonization with S. pneumoniae was enhanced in the upper respiratory tract of CS-exposed mice and was accompanied by increased translocation of S. pneumoniae into the lung. Bacterial colonization levels were associated with increased concentrations of inflammatory mediators and the number of immune cells in lavage fluids of the upper respiratory tract and the lung. Phagocytosis activity was reduced in whole blood granulocytes and monocytes of CS-exposed mice.

CONCLUSIONS

These findings demonstrate that exposure to CS impacts the ability of the host to control bacterial colonization of the upper airways, resulting in enhanced inflammation and susceptibility of the host to pathogens migrating into the lung.

In vivo Cigarette Smoke Exposure Decreases CCL20, SLPI, and BD-1 Secretion by Human Primary Nasal Epithelial Cells

Smokers and individuals exposed to second-hand cigarette smoke have a higher risk of developing chronic sinus and bronchial infections. This suggests that cigarette smoke (CS) has adverse effects on immune defenses against pathogens. Epithelial cells are important in airway innate immunity and are the first line of defense against infection. Airway epithelial cells not only form a physical barrier but also respond to the presence of microbes by secreting antimicrobials, cytokines, and chemokines. These molecules can lyse infectious microorganisms and/or provide signals critical to the initiation of adaptive immune responses. We examined the effects of CS on antimicrobial secretions of primary human nasal epithelial cells (PHNECs). Compared to non-CS-exposed individuals, PHNEC from in vivo CS-exposed individuals secreted less chemokine ligand (C-C motif) 20 (CCL20), Beta-defensin 1 (BD-1), and SLPI apically, less BD-1 and SLPI basolaterally, and more CCL20 basolaterally. Cigarette smoke extract (CSE) exposure in vitro decreased the apical secretion of CCL20 and beta-defensin 1 by PHNEC from non-CS-exposed individuals. Exposing PHNEC from non-CS exposed to CSE also significantly decreased the levels of many mRNA transcripts that are involved in immune signaling. Our results show that in vivo or in vitro exposure to CS alters the secretion of key antimicrobial peptides from PHNEC, but that in vivo CS exposure is a much more important modifier of antimicrobial peptide secretion. Based on the gene expression data, it appears that CSE disrupts multiple immune signaling pathways in PHNEC. Our results provide mechanistic insight into how CS exposure alters the innate immune response and increases an individual's susceptibility to pathogen infection.

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.

Inflammasome Activity in Non-Microbial Lung Inflammation

The understanding of interleukin-1 (IL-1) family cytokines in inflammatory disease has rapidly developed, due in part to the discovery and characterization of inflammasomes, which are multi-subunit intracellular protein scaffolds principally enabling recognition of a myriad of cellular stimuli, leading to the activation of caspase-1 and the processing of IL-1β and IL-18. Studies continue to elucidate the role of inflammasomes in immune responses induced by both microbes and environmental factors. This review focuses on the current understanding of inflammasome activity in the lung, with particular focus on the non-microbial instigators of inflammasome activation, including inhaled antigens, oxidants, cigarette smoke, diesel exhaust particles, mineral fibers, and engineered nanomaterials, as well as exposure to trauma and pre-existing inflammatory conditions such as metabolic syndrome. Inflammasome activity in these sterile inflammatory states contribute to diseases including asthma, chronic obstructive disease, acute lung injury, ventilator-induced lung injury, pulmonary fibrosis, and lung cancer.

Molecular processes that drive cigarette smoke-induced epithelial cell fate of the lung

Cigarette smoke contains numerous chemical compounds, including abundant reactive oxygen/nitrogen species and aldehydes, and many other carcinogens. Long-term cigarette smoking significantly increases the risk of various lung diseases, including chronic obstructive pulmonary disease and lung cancer, and contributes to premature death. Many in vitro and in vivo studies have elucidated mechanisms involved in cigarette smoke-induced inflammation, DNA damage, and autophagy, and the subsequent cell fates, including cell death, cellular senescence, and transformation. In this Translational Review, we summarize the known pathways underlying these processes in airway epithelial cells to help reveal future challenges and describe possible directions of research that could lead to better management and treatment of these diseases.

Inflammatory and cytotoxic effects of acrolein, nicotine, acetylaldehyde and cigarette smoke extract on human nasal epithelial cells

BACKGROUND

Cigarette smoke induces a pro-inflammatory response in airway epithelial cells but it is not clear which of the various chemicals contained within cigarette smoke (CS) should be regarded as predominantly responsible for these effects. We hypothesised that acrolein, nicotine and acetylaldehyde, important chemicals contained within volatile cigarette smoke in terms of inducing inflammation and causing addiction, have immunomodulatory effects in primary nasal epithelial cell cultures (PNECs).

METHODS

PNECs from 19 healthy subjects were grown in submerged cultures and were incubated with acrolein, nicotine or acetylaldehyde prior to stimulation with Pseudomonas aeruginosa lipopolysaccharide (PA LPS). Experiments were repeated using cigarette smoke extract (CSE) for comparison. IL-8 was measured by ELISA, activation of NF-κB by ELISA and Western blotting, and caspase-3 activity by Western blotting. Apoptosis was evaluated using Annexin-V staining and the terminal transferase-mediated dUTP nick end-labeling (TUNEL) method.

RESULTS

CSE was pro-inflammatory after a 24 h exposure and 42% of cells were apoptotic or necrotic after this exposure time. Acrolein was pro-inflammatory for the PNEC cultures (30 μM exposure for 4 h inducing a 2.0 fold increase in IL-8 release) and also increased IL-8 release after stimulation with PA LPS. In contrast, nicotine had anti-inflammatory properties (0.6 fold IL-8 release after 50 μM exposure to nicotine for 24 h), and acetylaldehyde was without effect. Acrolein and nicotine had cellular stimulatory and anti-inflammatory effects respectively, as determined by NF-κB activation. Both chemicals increased levels of cleaved caspase 3 and induced cell death.

CONCLUSIONS

Acrolein is pro-inflammatory and nicotine anti-inflammatory in PNEC cultures. CSE induces cell death predominantly by apoptotic mechanisms.

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.

Acrolein exposure suppresses antigen-induced pulmonary inflammation

Background

Adverse health effects of tobacco smoke arise partly from its influence on innate and adaptive immune responses, leading to impaired innate immunity and host defense. The impact of smoking on allergic asthma remains unclear, with various reports demonstrating that cigarette smoke enhances asthma development but can also suppress allergic airway inflammation. Based on our previous findings that immunosuppressive effects of smoking may be largely attributed to one of its main reactive electrophiles, acrolein, we explored the impact of acrolein exposure in a mouse model of ovalbumin (OVA)-induced allergic asthma.

Methods

C57BL/6 mice were sensitized to ovalbumin (OVA) by intraperitoneal injection with the adjuvant aluminum hydroxide on days 0 and 7, and challenged with aerosolized OVA on days 14–16. In some cases, mice were also exposed to 5 ppm acrolein vapor for 6 hrs/day on days 14–17. Lung tissues or brochoalveolar lavage fluids (BALF) were collected either 6 hrs after a single initial OVA challenge and/or acrolein exposure on day 14 or 48 hrs after the last OVA challenge, on day 18. Inflammatory cells and Th1/Th2 cytokine levels were measured in BALF, and lung tissue samples were collected for analysis of mucus and Th1/Th2 cytokine expression, determination of protein alkylation, cellular thiol status and transcription factor activity.

Results

Exposure to acrolein following OVA challenge of OVA-sensitized mice resulted in markedly attenuated allergic airway inflammation, demonstrated by decreased inflammatory cell infiltrates, mucus hyperplasia and Th2 cytokines. Acrolein exposure rapidly depleted lung tissue glutathione (GSH) levels, and induced activation of the Nrf2 pathway, indicated by accumulation of Nrf2, increased alkylation of Keap1, and induction of Nrf2-target genes such as HO-1. Additionally, analysis of inflammatory signaling pathways showed suppressed activation of NF-κB and marginally reduced activation of JNK in acrolein-exposed lungs, associated with increased carbonylation of RelA and JNK.

Conclusion

Acrolein inhalation suppresses Th2-driven allergic inflammation in sensitized animals, due to direct protein alkylation resulting in activation of Nrf2 and anti-inflammatory gene expression, and inhibition of NF-κB or JNK signaling. Our findings help explain the paradoxical anti-inflammatory effects of cigarette smoke exposure in allergic airways disease.

Innate immunity and chronic obstructive pulmonary disease: a mini-review

Chronic obstructive pulmonary disease (COPD), a major smoking-associated lung disorder characterized by progressive irreversible airflow limitation, affects >200 million people worldwide. Individuals with COPD have increased susceptibility to respiratory infections, resulting in exacerbations of the disease. A growing body of evidence indicates that multiple host defense mechanisms, such as those provided by the airway epithelial barrier and innate immune cells, including alveolar macrophages, neutrophils, dendritic cells and natural killer cells, are broadly suppressed in COPD in a smoking-dependent manner. Inactivation of the innate immune system observed in COPD smokers is remarkably similar to the immunosenescence phenotype associated with aging. As a consequence of defective innate immune defense, the lungs of COPD smokers are frequently colonized with pathogens and commonly develop bacterial and viral infections, which cause secondary inflammation, a major driver of the disease progression. In this review, we summarize the evidence from human studies related to disordering of the innate immune system in COPD, discuss possible relationships between those changes and aging, and provide insights into potential therapeutic strategies aimed at the prevention of COPD progression via normalization of the disordered innate immune mechanisms.

Dual role of Toll-like receptors in asthma and chronic obstructive pulmonary disease

During the last decade, significant research has been focused on Toll-like receptors (TLRs) in the pathogenesis of airway diseases. TLRs are pattern recognition receptors that play pivotal roles in the detection of and response to pathogens. Because of the involvement of TLRs in innate and adaptive immunity, these receptors are currently being exploited as possible targets for drug development. Asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory airway diseases in which innate and adaptive immunity play an important role. To date, asthma is the most common chronic disease in children aged 5 years and older. COPD is prevalent amongst the elderly and is currently the fifth-leading cause of death worldwide with still-growing prevalence. Both of these inflammatory diseases result in shortness of breath, which is treated, often ineffectively, with bronchodilators and glucocorticosteroids. Symptomatic treatment approaches are similar for both diseases; however, the underlying immunological mechanisms differ greatly. There is a clear need for improved treatment specific for asthma and for COPD. This review provides an update on the role of TLRs in asthma and in COPD and discusses the merits and difficulties of targeting these proteins as novel treatment strategies for airway diseases. TLR agonist, TLR adjuvant, and TLR antagonist therapies could all be argued to be effective in airway disease management. Because of a possible dual role of TLRs in airway diseases with shared symptoms and risk factors but different immunological mechanisms, caution should be taken while designing pulmonary TLR-based therapies.

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.

Interaction of cigarette exposure and airway epithelial cell gene expression

Cigarette smoking is responsible for lung cancer and chronic obstructive pulmonary disease (COPD), the leading cause of death from cancer and the second-leading cause of death in the United States. In the United States, 46 million people smoke, with an equal number of former smokers. Moreover, 20-25% of current or former smokers will develop either disease, and smokers with one disease are at increased risk for developing the other. There are no tools for predicting risk of developing either disease; no accepted tools for early diagnosis of potentially curable lung cancer; and no tools for defining molecular pathways or molecular subtypes of these diseases, for predicting rate of progression, or for assessing response to therapy at a biochemical or molecular level. This review discusses current studies and the future potential of measuring global gene expression in epithelial cells that are in the airway field of injury and of using the genomic information derived to begin to answer some of the above questions.