Cigarette smoke exposure exacerbates lung inflammation and compromises immunity to bacterial infection

Cigarette smoke extract modulates Pseudomonas aeruginosa bacterial load via USP25/HDAC11 axis in lung epithelial cells

Cigarette smoking increases susceptibility for microbial infection in respiratory system. However, the underlying molecular mechanism(s) is not fully elucidated. Here we report that cigarette smoking extract (CSE) increases bacterial load in lung epithelial cells via downregulation of the ubiquitin-specific protease 25 (USP25)/histone deacetylase 11 (HDAC11) axis. CSE treatment decreases HDAC11 at protein level in lung epithelial cells without significant changes of its transcription. Concomitantly, CSE treatment accelerates a ubiquitin-specific protease USP25 ubiquitination and degradation. Coimmunoprecipitation studies showed that USP25 associated with HDAC11. USP25 catalyzes deubiquitination of HDAC11, which regulates HDAC11 protein stability. CSE-mediated degradation of USP25 thereafter reduces HDAC11 at the protein level. Interestingly, CSE-downregulated USP25/HDAC11 axis increases the bacterial load of Pseudomonas aeruginosa in lung epithelial cells. These findings suggest that CSE-downregulated USP25 and HDAC11 may contribute to high susceptibility of bacterial infection in the cigarette smoking population.

Dietary Inflammatory Index and Non-Communicable Disease Risk: A Narrative Review

There are over 1,000,000 publications on diet and health and over 480,000 references on inflammation in the National Library of Medicine database. In addition, there have now been over 30,000 peer-reviewed articles published on the relationship between diet, inflammation, and health outcomes. Based on this voluminous literature, it is now recognized that low-grade, chronic systemic inflammation is associated with most non-communicable diseases (NCDs), including diabetes, obesity, cardiovascular disease, cancers, respiratory and musculoskeletal disorders, as well as impaired neurodevelopment and adverse mental health outcomes. Dietary components modulate inflammatory status. In recent years, the Dietary Inflammatory Index (DII®), a literature-derived dietary index, was developed to characterize the inflammatory potential of habitual diet. Subsequently, a large and rapidly growing body of research investigating associations between dietary inflammatory potential, determined by the DII, and risk of a wide range of NCDs has emerged. In this narrative review, we examine the current state of the science regarding relationships between the DII and cancer, cardiometabolic, respiratory and musculoskeletal diseases, neurodevelopment, and adverse mental health outcomes. We synthesize the findings from recent studies, discuss potential underlying mechanisms, and look to the future regarding novel applications of the adult and children's DII (C-DII) scores and new avenues of investigation in this field of nutritional research.

Soluble Wood Smoke Extract Promotes Barrier Dysfunction in Alveolar Epithelial Cells through a MAPK Signaling Pathway

Wildfire smoke induces acute pulmonary distress and is of particular concern to risk groups such as the sick and elderly. Wood smoke (WS) contains many of the same toxic compounds as those found in cigarette smoke (CS) including polycyclic aromatic hydrocarbons, carbon monoxide, and free radicals. CS is a well-established risk factor for respiratory diseases such as asthma and COPD. Limited studies investigating the biological effects of WS on the airway epithelium have been performed. Using a cell culture-based model, we assessed the effects of a WS-infused solution on alveolar epithelial barrier function, cell migration, and survival. The average geometric mean of particles in the WS was 178 nm. GC/MS analysis of the WS solution identified phenolic and cellulosic compounds. WS exposure resulted in a significant reduction in barrier function, which peaked after 24 hours of continuous exposure. The junctional protein E-cadherin showed a prominent reduction in response to increasing concentrations of WS. Furthermore, WS significantly repressed cell migration following injury to the cell monolayer. There was no difference in cell viability following WS exposure. Mechanistically, WS exposure induced activation of the p44/42, but not p38, MAPK signaling pathway, and inhibition of p44/42 phosphorylation prevented the disruption of barrier function and loss of E-cadherin staining. Thus, WS may contribute to the breakdown of alveolar structure and function through a p44/42 MAPK-dependent pathway and may lead to the development and/or exacerbation of respiratory pathologies with chronic exposure.

Cigarette Smoke Induced Lung Barrier Dysfunction, EMT, and Tissue Remodeling: A Possible Link between COPD and Lung Cancer

Chronic obstructive pulmonary disease (COPD) and lung cancer, closely related to smoking, are major lung diseases affecting millions of individuals worldwide. The generated gas mixture of smoking is proved to contain about 4,500 components such as carbon monoxide, nicotine, oxidants, fine particulate matter, and aldehydes. These components were considered to be the principle factor driving the pathogenesis and progression of pulmonary disease. A large proportion of lung cancer patients showed a history of COPD, which demonstrated that there might be a close relationship between COPD and lung cancer. In the early stages of smoking, lung barrier provoked protective response and DNA repair are likely to suppress these changes to a certain extent. In the presence of long-term smoking exposure, these mechanisms seem to be malfunctioned and lead to disease progression. The infiltration of inflammatory cells to mucosa, submucosa, and glandular tissue caused by inhaled cigarette smoke is responsible for the destruction of matrix, blood supply shortage, and epithelial cell death. Conversely, cancer cells have the capacity to modulate the proliferation of epithelial cells and produce of new vascular networks. Comprehension understanding of mechanisms responsible for both pathologies is necessary for the prevention and treatment of COPD and lung cancer. In this review, we will summarize related articles and give a glance of possible mechanism between cigarette smoking induced COPD and lung cancer.

Repeated Exposure to Streptococcus pneumoniae Exacerbates Chronic Obstructive Pulmonary Disease

Streptococcus pneumoniae is commonly found in patients with chronic obstructive pulmonary disease (COPD) and is linked to acute exacerbation of COPD. However, current clinical therapy neglects asymptomatic insidious S. pneumoniae colonization. We studied the roles of repeated exposure to S. pneumoniae in COPD progression using a mouse model. C57BL/6J mice were intranasally inoculated with S. pneumoniae ST262 every 4 weeks with or without cigarette smoke (CS) exposure up to 20 weeks to maintain persistent S. pneumoniae presence in the lower airways. Streptococcus pneumoniae enhanced CS-induced inflammatory cell infiltration at 12 to 20 weeks of exposure. Streptococcus pneumoniae also increased CS-induced release of inflammatory cytokines, including IL-1β, tumor necrosis factor-α, IL-12 (p70), and IL-5 at 20 weeks of exposure. Moreover, a combination of CS and S. pneumoniae caused alveolar epithelial injury, a decline in lung function, and an increased expression of platelet-activating factor receptor and bacterial load. Our results suggest that repeated exposure to S. pneumoniae in lower airways exacerbates CS-induced COPD.

Immunometabolism and Pulmonary Infections: Implications for Protective Immune Responses and Host-Directed Therapies

The biology and clinical efficacy of immune cells from patients with infectious diseases or cancer are associated with metabolic programming. Host immune- and stromal-cell genetic and epigenetic signatures in response to the invading pathogen shape disease pathophysiology and disease outcomes. Directly linked to the immunometabolic axis is the role of the host microbiome, which is also discussed here in the context of productive immune responses to lung infections. We also present host-directed therapies (HDT) as a clinically viable strategy to refocus dysregulated immunometabolism in patients with infectious diseases, which requires validation in early phase clinical trials as adjuncts to conventional antimicrobial therapy. These efforts are expected to be continuously supported by newly generated basic and translational research data to gain a better understanding of disease pathology while devising new molecularly defined platforms and therapeutic options to improve the treatment of patients with pulmonary infections, particularly in relation to multidrug-resistant pathogens.

Smoking Dependent Alterations in Bone Formation and Inflammation Represent Major Risk Factors for Complications Following Total Joint Arthroplasty

Numerous studies have described a correlation between smoking and reduced bone mass. This not only increases fracture risk but also impedes reconstruction/fixation of bone. An increased frequency of complications following surgery is common. Here, we investigate the effect of smoking on the clinical outcome following total joint arthroplasty (TJA). 817 patients receiving primary or revision (including clinical transfers) TJA at our level-one trauma center have been randomly interviewed twice (pre- and six months post-surgery). We found that 159 patients developed complications (infections, disturbed healing, revisions, thrombosis, and/or death). Considering nutritional status, alcohol and cigarette consumption as possible risk factors, OR was highest for smoking. Notably, mean age was significantly lower in smokers (59.2 ± 1.0a) than non-smokers (64.6 ± 0.8; p < 0.001). However, the number of comorbidities was comparable between both groups. Compared to non-smokers (17.8 ± 1.9%), the complication rate increases with increasing cigarette consumption (1⁻20 pack-years (PY): 19.2 ± 2.4% and >20 PY: 30.4 ± 3.6%; p = 0.002). Consequently, mean hospital stay was longer in heavy smokers (18.4 ± 1.0 day) than non-smokers (15.3 ± 0.5 day; p = 0.009) or moderate smokers (15.9 ± 0.6 day). In line with delayed healing, bone formation markers (BAP and CICP) were significantly lower in smokers than non-smokers 2 days following TJA. Although, smoking increased serum levels of MCP-1, OPG, sRANKL, and Osteopontin as well as bone resorption markers (TRAP5b and CTX-I) were unaffected. In line with an increased infection rate, smoking reduced 25OH vitamin D3 (immune-modulatory), IL-1β, IL-6, TNF-α, and IFN-γ serum levels. Our data clearly show that smoking not only affects bone formation after TJA but also suppresses the inflammatory response in these patients. Thus, it is feasible that therapies favoring bone formation and immune responses help improve the clinical outcome in smokers following TJA.

Indoor air pollution and tobacco smoke exposure: impact on nasopharyngeal bacterial carriage in mothers and infants in an African birth cohort study

Indoor air pollution (IAP) or environmental tobacco smoke (ETS) exposure may influence nasopharyngeal carriage of bacterial species and development of lower respiratory tract infection (LRTI). The aim of this study was to longitudinally investigate the impact of antenatal or postnatal IAP/ETS exposure on nasopharyngeal bacteria in mothers and infants. A South African cohort study followed mother-infant pairs from birth through the first year. Nasopharyngeal swabs were taken at birth, 6 and 12 months for bacterial culture. Multivariable and multivariate Poisson regression investigated associations between nasopharyngeal bacterial species and IAP/ETS. IAP exposures (particulate matter, carbon monoxide, nitrogen dioxide, volatile organic compounds) were measured at home visits. ETS exposure was measured through maternal and infant urine cotinine. Infants received the 13-valent pneumococcal and Haemophilus influenzae B conjugate vaccines. There were 881 maternal and 2605 infant nasopharyngeal swabs. Antenatal ETS exposure was associated with Streptococcus pneumoniae carriage in mothers (adjusted risk ratio (aRR) 1.73 (95% CI 1.03-2.92)) while postnatal ETS exposure was associated with carriage in infants (aRR 1.14 (95% CI 1.00-1.30)) Postnatal particulate matter exposure was associated with the nasopharyngeal carriage of H. influenzae (aRR 1.68 (95% CI 1.10- 2.57)) or Moraxella catarrhalis (aRR 1.42 (95% CI 1.03-1.97)) in infants. Early-life environmental exposures are associated with an increased prevalence of specific nasopharyngeal bacteria during infancy, which may predispose to LRTI.

Immunodeficiency in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), characterized by progressive airway inflammation and irreversible airflow limitation, leads to serious decline in life quality. The acute exacerbation of COPD (AECOPD) results in high healthcare costs as well as a significant mortality rate. The most common cause of acute exacerbation is infection. Immune deficiency, which induces dysfunction of anti-infection, plays an important role in the pathogenesis of acute exacerbation. As described in this review, the immune dysfunction in patients with AECOPD can be a major focus of efforts to therapeutic strategy.

Integrative Physiology of Pneumonia

Pneumonia is a type of acute lower respiratory infection that is common and severe. The outcome of lower respiratory infection is determined by the degrees to which immunity is protective and inflammation is damaging. Intercellular and interorgan signaling networks coordinate these actions to fight infection and protect the tissue. Cells residing in the lung initiate and steer these responses, with additional immunity effectors recruited from the bloodstream. Responses of extrapulmonary tissues, including the liver, bone marrow, and others, are essential to resistance and resilience. Responses in the lung and extrapulmonary organs can also be counterproductive and drive acute and chronic comorbidities after respiratory infection. This review discusses cell-specific and organ-specific roles in the integrated physiological response to acute lung infection, and the mechanisms by which intercellular and interorgan signaling contribute to host defense and healthy respiratory physiology or to acute lung injury, chronic pulmonary disease, and adverse extrapulmonary sequelae. Pneumonia should no longer be perceived as simply an acute infection of the lung. Pneumonia susceptibility reflects ongoing and poorly understood chronic conditions, and pneumonia results in diverse and often persistent deleterious consequences for multiple physiological systems.

The Interplay Between Immune Response and Bacterial Infection in COPD: Focus Upon Non-typeable Haemophilus influenzae

Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a "vicious circle." Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.

Suppression of Neutrophil Antimicrobial Functions by Total Particulate Matter From Cigarette Smoke

Chronic cigarette smoking is widely known to alter immune functions and compromise host defense against microbial infection. Neutrophils play an essential role in the immune defense against microbial pathogens and also participate in the development of the inflammatory responses. However, there is limited information about the effects of cigarette smoking on neutrophil response. In this study, cultured bone marrow neutrophils were exposed to total particulate matter (TPM) from cigarette smoke. We found that TPM not only reduced LPS-induced TNFα production, but also suppressed neutrophil bactericidal activity. We also observed that TPM priming reduced the expression of NADPH oxidase component gp91 and iNOS, molecules important for bacterial killing. Mechanistically, we documented that TPM-primed neutrophils have reduced STAT1 activation following subsequent LPS challenge. STAT1 is a key transcription factor responsible for the expression of inflammatory genes as well as gp91 and iNOS. Collectively, reduced STAT1 activation and reduced NADPH oxidase/iNOS may potentially explain the compromised anti-microbial function of TPM-programmed neutrophils. Taken together, our findings reveal that the key innate immune neutrophil is subject to reprogramming by smoking to adopt an immune-suppressed state, potentially responsible for chronic smoking-mediated immunosuppression.

Inhaled IL-10 Suppresses Lung Tumorigenesis via Abrogation of Inflammatory Macrophage-Th17 Cell Axis

Intratracheal administration of a novel IL-10 formulation suppressed IL-17-driven, CD4⁺ T cell-dependent tumorigenesis in the LSL-K-ras^G12D murine lung cancer model. Analysis of lung lymphocyte populations demonstrated that antitumor activity of IL-10 was associated with a 5-fold decline in Th17 cell prevalence and a concurrent suppression of inflammatory M1-like macrophage activity. Further phenotypic characterization revealed that macrophages and dendritic cells, but not Th17 cells, expressed IL-10RA on the cell surface with the CD11b⁺F4/80⁺CX3CR1⁺ interstitial macrophages representing the dominant IL-10RA⁺ subset. Consistent with these observations, in vitro stimulation of sorted CD4⁺ T cells with IL-10 did not affect their ability to produce IL-17, whereas similar treatment of purified interstitial macrophages resulted in a dramatic M1 to M2 phenotypic switch. Importantly, preconditioning of macrophages (but not of CD4⁺ T cells) with IL-10 led to potent suppression of CD4⁺ T cell IL-17 production in an in vitro coculture assay, suggesting that IL-10 suppressed Th17 cell activity primarily via its upstream effects on macrophages. In support of this notion, in vivo macrophage depletion resulted in a 5-fold decline in Th17 cell numbers and a concurrent 6-fold reduction in tumor burden. Collectively, these data demonstrate that in the LSL-K-ras^G12D murine lung cancer model, inflammatory macrophage-Th17 cell axis is critical to tumorigenesis and that IL-10 blocks this process primarily via a direct effect on the former. Inhaled IL-10 formulations may be of use in prophylaxis against lung cancer in high-risk patients.

Lignans Isolated From Flower Buds of Magnolia fargesii Attenuate Airway Inflammation Induced by Cigarette Smoke in vitro and in vivo

The flower buds of Magnolia fargesii, known traditionally as Xinyi, exert anti-inflammatory effects against inflammatory lung diseases such as COPD. Lignans isolated from Xinyi are an important group of plant-derived anti-inflammatory compounds. However, the mechanisms of action underlying their protective effects against COPD are not yet fully understood. Here, we showed that seven lignans (lignans 1–7) obtained from a CHCl₃ fraction of Xinyi effectively suppress the inflammatory response in CSC-stimulated airway epithelial cells (in vitro) and in a mouse model of COPD established by exposure to CS and LPS. The CHCl₃ fraction was found to inhibit CSC-induced IL-6 expression in human airway epithelial cells and to suppress the infiltration of inflammatory cells (neutrophils and macrophages) and secretion of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the mouse model. Similarly, each of the seven lignans isolated from the CHCl₃ fraction also suppressed the infiltration of inflammatory cells (neutrophils and macrophages) and secretion of inflammatory mediators such as reactive oxygen species (ROS), TNF-α, and IL-6 in vivo. Notably, all lignan compounds significantly suppressed both extracellular signal-related kinase (ERK) and Akt phosphorylation levels in CSC-stimulated human lung mucoepidermoid carcinoma (NCI-H292) cells. Of these, lignan 1 (dimethylpinoresinol) inhibited the expression of CSC-induced inflammatory cytokines (IL-1β, -6, and -8) in vitro in a dose-dependent manner by suppressing the activation of epidermal growth factor receptor (EGFR) and its downstream effectors, including ERK and Akt, in NCI-H292 cells. Our results show that the lignans isolated from Xinyi may prevent airway inflammatory diseases through the suppression of EGFR and its downstream effectors.

Phosphocholine-Modified Lipooligosaccharides of Haemophilus influenzae Inhibit ATP-Induced IL-1β Release by Pulmonary Epithelial Cells

Phosphocholine-modified bacterial cell wall components are virulence factors enabling immune evasion and permanent colonization of the mammalian host, by mechanisms that are poorly understood. Recently, we demonstrated that free phosphocholine (PC) and PC-modified lipooligosaccharides (PC-LOS) from Haemophilus influenzae, an opportunistic pathogen of the upper and lower airways, function as unconventional nicotinic agonists and efficiently inhibit the ATP-induced release of monocytic IL-1β. We hypothesize that H. influenzae PC-LOS exert similar effects on pulmonary epithelial cells and on the complex lung tissue. The human lung carcinoma-derived epithelial cell lines A549 and Calu-3 were primed with lipopolysaccharide from Escherichia coli followed by stimulation with ATP in the presence or absence of PC or PC-LOS or LOS devoid of PC. The involvement of nicotinic acetylcholine receptors was tested using specific antagonists. We demonstrate that PC and PC-LOS efficiently inhibit ATP-mediated IL-1β release by A549 and Calu-3 cells via nicotinic acetylcholine receptors containing subunits α7, α9, and/or α10. Primed precision-cut lung slices behaved similarly. We conclude that H. influenzae hijacked an endogenous anti-inflammatory cholinergic control mechanism of the lung to evade innate immune responses of the host. These findings may pave the way towards a host-centered antibiotic treatment of chronic airway infections with H. influenzae.

Oleuropein Curtails Pulmonary Inflammation and Tissue Destruction in Models of Experimental Asthma and Emphysema

Airway inflammation has been implicated in evoking progressive pulmonary disorders including chronic obstructive pulmonary disease (COPD) and asthma as a result of exposure to inhaled irritants, characterized by airway fibrosis, mucus hypersecretion, and loss of alveolar integrity. The current study examined whether oleuropein, a phenylethanoid found in olive leaves, inhibited pulmonary inflammation in experimental models of interleukin (IL)-4-exposed bronchial BEAS-2B epithelial cells and ovalbumin (OVA)- or cigarette smoke (CS)-exposed BALB/c mice. Nontoxic oleuropein at 1-20 μM diminished eotaxin-1-mediated induction of α-smooth muscle actin and mucin 5AC in epithelial cells stimulated by IL-4 at the transcriptional levels. Oral supplementation of 10-20 mg/kg oleuropein reduced the airway influx of eosinophils and lymphocytes as well as IL-4 secretion in lung promoted by OVA inhalation or CS. In addition, oleuropein suppressed infiltration of macrophages and neutrophils through blocking OVA inhalation- and CS-promoted induction of ICAM-1, F4/80, CD68, and CD11b in airways. OVA-exposed pulmonary fibrosis was detected, while alveolar emphysema was evident in CS-exposed mouse lungs. In alveolar epithelial A549 cells exposed to CS extracts, oleuropein attenuated apoptotic cell loss. Collectively, oleuropein inhibited pulmonary inflammation leading to asthmatic fibrosis and alveolar emphysema driven by influx of inflammatory cells in airways exposed OVA or CS. Therefore, oleuropein may be a promising anti-inflammatory agent for treating asthma and COPD.

Cigarette Smoke-Induced Emphysema Exhausts Early Cytotoxic CD8+ T Cell Responses against Nascent Lung Cancer Cells

Chronic obstructive pulmonary disease is a chronic inflammatory disorder with an increased incidence of lung cancer. The emphysema component of chronic obstructive pulmonary disease confers the greatest proportion to lung cancer risk. Although tumors create inflammatory conditions to escape immunity, the immunological responses that control growth of nascent cancer cells in pre-established inflammatory microenvironments are unknown. In this study, we addressed this issue by implanting OVA-expressing cancer cells in the lungs of mice with cigarette smoke-induced emphysema. Emphysema augmented the growth of cancer cells, an effect that was dependent on T cytotoxic cells. OVA-specific OTI T cells showed early signs of exhaustion upon transfer in emphysema tumor hosts that was largely irreversible because sorting, expansion, and adoptive transfer failed to restore their antitumor activity. Increased numbers of PD-L1- and IDO-positive CD11c⁺ myeloid dendritic cells (DCs) infiltrated emphysema tumors, whereas sorted emphysema tumor DCs poorly stimulated OTI T cells. Upon adoptive transfer in immunocompetent hosts, T cells primed by emphysema tumor DCs were unable to halt tumor growth. DCs exposed to the emphysema tumor microenvironment downregulated MHC class II and costimulatory molecules, whereas they upregulated PD-L1/IDO via oxidative stress-dependent mechanisms. T cell activation increased upon PD-L1 blockade in emphysema DC-T cell cocultures and in emphysema tumor hosts in vivo. Analysis of the transcriptome of primary human lung tumors showed a strong association between computed tomography-based emphysema scoring and downregulation of immunogenic processes. Thus, suppression of adaptive immunity against lung cancer cells links a chronic inflammatory disorder, emphysema, to cancer, with clinical implications for emphysema patients to be considered optimal candidates for cancer immunotherapies.

Airway Epithelium Dysfunction in Cystic Fibrosis and COPD

Cystic fibrosis is a genetic disease caused by mutations in the CFTR gene, whereas chronic obstructive pulmonary disease (COPD) is mainly caused by environmental factors (mostly cigarette smoking) on a genetically susceptible background. Although the etiology and pathogenesis of these diseases are different, both are associated with progressive airflow obstruction, airway neutrophilic inflammation, and recurrent exacerbations, suggesting common mechanisms. The airway epithelium plays a crucial role in maintaining normal airway functions. Major molecular and morphologic changes occur in the airway epithelium in both CF and COPD, and growing evidence suggests that airway epithelial dysfunction is involved in disease initiation and progression in both diseases. Structural and functional abnormalities in both airway and alveolar epithelium have a relevant impact on alteration of host defences, immune/inflammatory response, and the repair process leading to progressive lung damage and impaired lung function. In this review, we address the evidence for a critical role of dysfunctional airway epithelial cells in chronic airway inflammation and remodelling in CF and COPD, highlighting the common mechanisms involved in the epithelial dysfunction as well as the similarities and differences of the two diseases.

Secondhand Smoke Induces Inflammation and Impairs Immunity to Respiratory Infections

Despite advocacy to reduce smoking-related diseases, >1 billion people worldwide continue to smoke. Smoking is immunosuppressive and an important etiological factor in the development of several human disorders including respiratory diseases like chronic obstructive pulmonary disease. However, there is a critical gap in the knowledge of the role of secondhand smoke (SHS) in inflammation and immunity. We therefore studied the influence of SHS on pulmonary inflammation and immune responses to respiratory infection by nontypeable Haemophilus influenzae (NTHI) recurrently found in chronic obstructive pulmonary disease patients. Chronic SHS-exposed mice were chronically infected with NTHI and pulmonary inflammation was evaluated by histology. Immune cell numbers and cytokines were measured by flow cytometry and ELISA, respectively. Chronic SHS exposure impaired NTHI P6 Ag-specific B and T cell responses following chronic NTHI infection as measured by ELISPOT assays, reduced the production of Abs in serum and bronchoalveolar lavage, and enhanced albumin leak into the bronchoalveolar lavage as determined by ELISA. Histopathological examination of lungs revealed lymphocytic accumulation surrounding airways and bronchovasculature following chronic SHS exposure and chronic infection. Chronic SHS exposure enhanced the levels of inflammatory cytokines IL-17A, IL-6, IL-1β, and TNF-α in the lungs, and impaired the generation of adaptive immunity following either chronic infection or P6 vaccination. Chronic SHS exposure diminished bacterial clearance from the lungs after acute NTHI challenge, whereas P6 vaccination improved clearance equivalent to the level seen in air-exposed, non-vaccinated mice. Our study provides unequivocal evidence that SHS exposure has long-term detrimental effects on the pulmonary inflammatory microenvironment and immunity to infection and vaccination.

Cigarette smoke exposure worsens acute lung injury in antibiotic-treated bacterial pneumonia in mice

Evidence is accumulating that exposure to cigarette smoke (CS) increases the risk of developing acute respiratory distress syndrome (ARDS). Streptococcus pneumoniae is the most common cause of bacterial pneumonia, which in turn is the leading cause of ARDS. Chronic smokers have increased rates of pneumococcal colonization and develop more severe pneumococcal pneumonia than nonsmokers; yet mechanistic connections between CS exposure, bacterial pneumonia, and ARDS pathogenesis remain relatively unexplored. We exposed mice to 3 wk of moderate whole body CS or air, followed by intranasal inoculation with an invasive serotype of S. pneumoniae. CS exposure alone caused no detectable lung injury or bronchoalveolar lavage (BAL) inflammation. During pneumococcal infection, CS-exposed mice had greater survival than air-exposed mice, in association with reduced systemic spread of bacteria from the lungs. However, when mice were treated with antibiotics after infection to improve clinical relevance, the survival benefit was lost, and CS-exposed mice had more pulmonary edema, increased numbers of BAL monocytes, and elevated monocyte and lymphocyte chemokines. CS-exposed antibiotic-treated mice also had higher serum surfactant protein D and angiopoietin-2, consistent with more severe lung epithelial and endothelial injury. The results indicate that acute CS exposure enhances the recruitment of immune cells to the lung during bacterial pneumonia, an effect that may provide microbiological benefit but simultaneously exposes the mice to more severe inflammatory lung injury. The inclusion of antibiotic treatment in preclinical studies of acute lung injury in bacterial pneumonia may enhance clinical relevance, particularly for future studies of current or emerging tobacco products.

Cigarette smoke dampens antiviral signaling in small airway epithelial cells by disrupting TLR3 cleavage

Cigarette smokers and people exposed to second-hand smoke are at an increased risk for pulmonary viral infections, and yet the mechanism responsible for this heightened susceptibility is not understood. To understand the effect of cigarette smoke on susceptibility to viral infection, we used an air-liquid interface culture system and exposed primary human small airway epithelial cells (SAEC) to whole cigarette smoke, followed by treatment with the viral mimetic polyinosinic polycytidylic acid (poly I:C) or influenza A virus (IAV). We found that prior smoke exposure strongly inhibited production of proinflammatory (interleukin-6 and interleukin-8) and antiviral [interferon-γ-induced protein 10 (IP-10) and interferons] mediators in SAECs in response to poly I:C and IAV infection. Impaired antiviral responses corresponded to increased infection with IAV. This was associated with a decrease in phosphorylation of the key antiviral transcription factor interferon response factor 3 (IRF3). Here, we found that cigarette smoke exposure inhibited activation of Toll-like receptor 3 (TLR3) by impairing TLR3 cleavage, which was required for downstream phosphorylation of IRF3 and production of IP-10. These results identify a novel mechanism by which cigarette smoke exposure impairs antiviral responses in lung epithelial cells, which may contribute to increased susceptibility to respiratory infections.

Effects of cigarette smoke on pulmonary endothelial cells

Cigarette smoking is the leading cause of preventable disease and death in the United States. Cardiovascular comorbidities associated with both active and secondhand cigarette smoking indicate the vascular toxicity of smoke exposure. Growing evidence supports the injurious effect of cigarette smoke on pulmonary endothelial cells and the roles of endothelial cell injury in development of acute respiratory distress syndrome (ARDS), emphysema, and pulmonary hypertension. This review summarizes results from studies of humans, preclinical animal models, and cultured endothelial cells that document toxicities of cigarette smoke exposure on pulmonary endothelial cell functions, including barrier dysfunction, endothelial activation and inflammation, apoptosis, and vasoactive mediator production. The discussion is focused on effects of cigarette smoke-induced endothelial injury in the development of ARDS, emphysema, and vascular remodeling in chronic obstructive pulmonary disease.

Active, passive, and electronic cigarette smoking is associated with asthma in adolescents

The present study investigated the associations of active, passive, and electronic cigarette (E-cigarette) smoking with asthma in Korean adolescents. We used the cross-sectional study of Korea Youth Risk Behavior Web-based Survey conducted in 2011, 2012 and 2013. Active smoking was classified into 4 groups (0 days, 1-5 days, 6-19 days, and ≥20 days a month). Passive smoking was also categorized into 4 groups (0 days, 1-2 days, 3-4 days, and ≥5 days a week). E-cigarette was defined as yes or no in the last 30 days. Age, sex, obesity, region of residence, economic level, and parental educational level were adjusted for as confounders. Smoking variables were adjusted for one another. Adjusted odd ratios (AORs) and 95% confidence intervals (CIs) were calculated using multiple logistic regression analysis with complex sampling. In total, 2.3% (4,890/216,056) of participants reported asthma in the past 12 months. Active smoking was significantly associated with asthma (AOR [95% CI] of smoking ≥20 days/month = 1.57 [1.38-1.77], P < 0.001). Passive smoking was also related with asthma (AOR [95% CI] of smoking ≥5 days/week = 1.40 [1.28-1.53], P < 0.001). E-cigarette showed positive relation with asthma, although the effects of past smoking history could not be excluded (AOR [95% CI] = 1.12 [1.01-1.26], P = 0.027).

Targeting Interleukin-17 signalling in cigarette smoke-induced lung disease: Mechanistic concepts and therapeutic opportunities

It is widely accepted that compromised lung function in chronic obstructive pulmonary disease (COPD) is, at least in part, a consequence of persistent airway inflammation caused by particles and noxious gases present in cigarette smoke and indoor air pollution from burning biomass fuel. Currently, the World Health Organization estimates that 80 million people have moderate or severe COPD worldwide. While there is a global need for effective medical treatment, current therapeutic interventions have shown limited success in preventing disease pathology and progression. This is, in large part, due to the complexity and heterogeneity of COPD, and an incomplete understanding of the molecular mechanisms governing inflammatory processes in individual patients. This review discusses recent discoveries related to the pro-inflammatory cytokine interleukin (IL)-17A, and its potential role in the pathogenesis of COPD. We propose that an intervention strategy targeting IL-17 signalling offers an exciting opportunity to mitigate inflammatory processes, and prevent the progression of tissue pathologies associated with COPD.

Early Postnatal Secondhand Smoke Exposure Disrupts Bacterial Clearance and Abolishes Immune Responses in Muco-Obstructive Lung Disease

Secondhand smoke (SHS) exposure has been linked to the worsening of ongoing lung diseases. However, whether SHS exposure affects the manifestation and natural history of imminent pediatric muco-obstructive airway diseases such as cystic fibrosis remains unclear. To address these questions, we exposed Scnn1b transgenic (Scnn1b-Tg⁺) mice to SHS from postnatal day (PND) 3-21 and lung phenotypes were examined at PND22. Although a majority of filtered air (FA)-exposed Scnn1b-Tg⁺ (FA-Tg⁺) mice successfully cleared spontaneous bacterial infections by PND22, the SHS-exposed Scnn1b-Tg⁺ (SHS-Tg⁺) mice failed to resolve these infections. This defect was associated with suppressed antibacterial defenses, i.e., phagocyte recruitment, IgA secretion, and Muc5b expression. Whereas the FA-Tg⁺ mice exhibited marked mucus obstruction and Th2 responses, SHS-Tg⁺ mice displayed a dramatic suppression of these responses. Mechanistically, downregulated expression of IL-33, a stimulator of type II innate lymphoid cells, in lung epithelial cells was associated with suppression of neutrophil recruitment, IgA secretions, Th2 responses, and delayed bacterial clearance in SHS-Tg⁺ mice. Cessation of SHS exposure for 21 d restored previously suppressed responses, including phagocyte recruitment, IgA secretion, and mucous cell metaplasia. However, in contrast with FA-Tg⁺ mice, the SHS-Tg⁺ mice had pronounced epithelial necrosis, alveolar space consolidation, and lymphoid hyperplasia; indicating lagged unfavorable effects of early postnatal SHS exposure in later life. Collectively, our data show that early postnatal SHS exposure reversibly suppresses IL-33 levels in airspaces which, in turn, results in reduced neutrophil recruitment and diminished Th2 response. Our data indicate that household smoking may predispose neonates with muco-obstructive lung disease to bacterial exacerbations.

Cigarette Smoke Disrupted Lung Endothelial Barrier Integrity and Increased Susceptibility to Acute Lung Injury via Histone Deacetylase 6

Epidemiologic evidence indicates that cigarette smoke (CS) is associated with the development of acute lung injury (ALI). We have previously shown that brief CS exposure exacerbates lipopolysaccharide (LPS)-induced ALI in vivo and endothelial barrier dysfunction in vitro. In this study, we found that CS also exacerbated Pseudomonas-induced ALI in mice. We demonstrated that lung microvascular endothelial cells (ECs) isolated from mice exposed to CS had a greater permeability or incomplete recovery after challenges by LPS and thrombin. Histone deacetylase (HDAC) 6 deacetylates proteins essential for maintenance of endothelial barrier function. We found that HDAC6 phosphorylation at serine-22 was increased in lung tissues of mice exposed to CS and in lung ECs exposed to cigarette smoke extract (CSE). Inhibition of HDAC6 attenuated CSE-induced increases in EC permeability and CS priming of ALI. Similar barrier protection was provided by the microtubule stabilizer taxol, which preserved α-tubulin acetylation. CSE decreased α-tubulin acetylation and caused microtubule depolymerization. In coordination with increased HDAC6 phosphorylation, CSE inhibited Akt and activated glycogen synthase kinase (GSK)-3β; these effects were ameliorated by the antioxidant N-acetyl cysteine. Our results suggest that CS increases lung EC permeability, thereby enhancing susceptibility to ALI, likely through oxidative stress-induced Akt inactivation and subsequent GSK-3β activation. Activated GSK-3β may activate HDAC6 via phosphorylation of serine-22, leading to α-tubulin deacetylation and microtubule disassembly. Inhibition of HDAC6 may be a novel therapeutic option for ALI in cigarette smokers.

Nontypeable Haemophilus influenzae and chronic obstructive pulmonary disease: a review for clinicians

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of morbidity and mortality worldwide. In the lower airways of COPD patients, bacterial infection is a common phenomenon and Haemophilus influenzae is the most commonly identified bacteria. Haemophilus influenzae is divided into typeable and nontypeable (NTHi) strains based on the presence or absence of a polysaccharide capsule. While NTHi is a common commensal in the human nasopharynx, it is associated with considerable inflammation when it is present in the lower airways of COPD patients, resulting in morbidity due to worsening symptoms and increased frequency of COPD exacerbations. Treatment of lower airway NTHi infection with antibiotics, though successful in the short term, does not offer long-term protection against reinfection, nor does it change the course of the disease. Hence, there has been much interest in the development of an effective NTHi vaccine. This review will summarize the current literature concerning the role of NTHi infections in COPD patients and the consequences of using prophylactic antibiotics in patients with COPD. There is particular focus on the rationale, findings of clinical studies and possible future directions of NTHi vaccines in patients with COPD.

Serum cytokine levels related to exposure to volatile organic compounds and PM2.5 in dwellings and workplaces in French farmers - a mechanism to explain nonsmoking COPD

Although French farmers smoke less on average than individuals from the general population, they suffer more from COPD. Exposure to biological and chemical air pollutants in the farm may be the cause of these higher COPD rates. This study investigates the role of bio-contaminants, including the relationship of exposure to volatile organic compounds (VOCs) and fine particulate matter (of diameter of 2.5 µm [PM_2.5]) objectively measured in the farm settings (dwellings and workplaces) to serum cytokines involved in COPD, in a sample of 72 farmers from 50 farms in the Auvergne region, France. Mean concentrations of VOCs were highest inside the home, while levels of PM_2.5 were highest in workplaces (stables and granaries). After adjusting for confounders, high exposure to PM_2.5 was significantly associated with a decreased level of serum cytokines (among others, IL13: β: −0.94, CI: −1.5 to −0.2, P-value =0.004; IL8: β: −0.82, CI: −1.4 to −0.2, P-value =0.005) and high exposure to VOCs according to a VOC global score with a decreased IL13 level (β: −0.5, CI: −0.9 to −0.1, P-value =0.01). Moreover, respiratory symptoms and diseases, including COPD, were associated with a decreased level of serum cytokines significantly in the case of IL5. An alteration of immune response balance in terms of cytokine levels in relation to indoor chemical air pollution exposure may contribute to respiratory health impairment in farmers.

Non-Typeable Haemophilus influenzae Infection of the Junbo Mouse

Acute otitis media, inflammation of the middle ear bulla, is the most common bacterial infection in children. For one of the principal otopathogens, non-typeable Haemophilus influenzae (NTHi), animal models allow us to investigate host-microbial interactions relevant to the onset and progression of infection and to study treatment of middle ear disease. We have established a robust model of NTHi middle ear infection in the Junbo mouse. Intranasal inoculation with NTHi produces high rates of bulla infection and high bacterial titers in bulla fluids; bacteria can also spread down the respiratory tract to the mouse lung. An innate immune response is detected in the bulla of Junbo mice following NTHi infection, and bacteria are maintained in some ears at least up to day 56 post-inoculation. The Junbo/NTHi infection model facilitates studies on bacterial pathogenesis and antimicrobial intervention regimens and vaccines for better treatment and prevention of NTHi middle ear infection. © 2017 by John Wiley & Sons, Inc.

Astragalin Inhibits Allergic Inflammation and Airway Thickening in Ovalbumin-Challenged Mice

Lung inflammation and oxidative stress are the major contributors to the development of obstructive pulmonary diseases. Macrophages are involved in pulmonary inflammation and alveolar damage in emphysema. Astragalin is an anti-inflammatory flavonoid present in persimmon leaves and green tea seeds. This study elucidated that astragalin inhibited inflammatory cell infiltration induced by 20 μM H₂O₂ and blocked airway thickening and alveolar emphysema induced by 20 μg of ovalbumin (OVA) in mice. OVA induced mouse pulmonary MCP-1, and H₂O₂ enhanced the expression of MCP-1/ICAM-1/αv integrin in bronchial airway epithelial BEAS-2B cells. Such induction was inhibited by supplying 10-20 mg/kg of astragalin to OVA-challenged mice and 1-20 μM astragalin to oxidant-stimulated cells. Oral administration of 20 mg/kg of astragalin reduced the induction of F4/80/CD68/CD11b in airways of mice challenged with OVA. Additionally, emphysema tissue damage was observed in OVA-exposed alveoli. Mast cell recruitment in the airway subepithelium was blocked by supplementing astragalin to OVA-challenged mice. Orally treating 20 mg/kg of astragalin reduced α-SMA induction in inflammation-occurring airways and appeared to reverse airway thickening and constriction induced by an OVA episode. These results revealed that astragalin may improve airway thickening and alveolar destruction with blockade of allergic inflammation in airways. Therefore, astragalin may be a therapeutic agent antagonizing asthma and obstructive pulmonary diseases.

Relationships between Mucosal Antibodies, Non-Typeable Haemophilus influenzae (NTHi) Infection and Airway Inflammation in COPD

Non-typeable Haemophilus influenzae (NTHi) is a key pathogen in COPD, being associated with airway inflammation and risk of exacerbation. Why some patients are susceptible to colonisation is not understood. We hypothesised that this susceptibility may be due to a deficiency in mucosal humoral immunity. The aim of our study (NCT01701869) was to quantify the amount and specificity of antibodies against NTHi in the lungs and the associated risk of infection and inflammation in health and COPD. Phlebotomy, sputum induction and bronchoscopy were performed on 24 mild-to-moderate COPD patients and 8 age and smoking-matched controls. BAL (Bronchoalveolar lavage) total IgG1, IgG2, IgG3, IgM and IgA concentrations were significantly increased in COPD patients compared to controls. NTHi was detected in the lungs of 7 of the COPD patients (NTHi+ve-29%) and these patients had a higher median number of previous exacerbations than NTHi-ve patients as well as evidence of increased systemic inflammation. When comparing NTHi+ve versus NTHi-ve patients we observed a decrease in the amount of both total IgG1 (p = 0.0068) and NTHi-specific IgG1 (p = 0.0433) in the BAL of NTHi+ve patients, but no differences in total IgA or IgM. We observed no evidence of decreased IgG1 in the serum of NTHi+ve patients, suggesting this phenomenon is restricted to the airway. Furthermore, the NTHi+ve patients had significantly greater levels of IL-1β (p = 0.0003), in BAL than NTHi-ve COPD patients.This study indicates that the presence of NTHi is associated with reduced levels and function of IgG1 in the airway of NTHi-colonised COPD patients. This decrease in total and NTHI-specific IgG1 was associated with greater systemic and airway inflammation and a history of more frequent exacerbations and may explain the susceptibility of some COPD patients to the impacts of NTHi.

Double-hit mouse model of cigarette smoke priming for acute lung injury

Epidemiological studies indicate that cigarette smoking (CS) increases the risk and severity of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). The mechanism is not understood, at least in part because of lack of animal models that reproduce the key features of the CS priming process. In this study, using two strains of mice, we characterized a double-hit mouse model of ALI induced by CS priming of injury caused by lipopolysaccharide (LPS). C57BL/6 and AKR mice were preexposed to CS briefly (3 h) or subacutely (3 wk) before intratracheal instillation of LPS and ALI was assessed 18 h after LPS administration by measuring lung static compliance, lung edema, vascular permeability, inflammation, and alveolar apoptosis. We found that as little as 3 h of exposure to CS enhanced LPS-induced ALI in both strains of mice. Similar exacerbating effects were observed after 3 wk of preexposure to CS. However, there was a strain difference in susceptibility to CS priming for ALI, with a greater effect in AKR mice. The key features we observed suggest that 3 wk of CS preexposure of AKR mice is a reproducible, clinically relevant animal model that is useful for studying mechanisms and treatment of CS priming for a second-hit-induced ALI. Our data also support the concept that increased susceptibility to ALI/ARDS is an important adverse health consequence of CS exposure that needs to be taken into consideration when treating critically ill individuals.

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

RATIONALE

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

OBJECTIVES

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

METHODS AND RESULTS

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

CONCLUSION

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

Randomized, double-blind, placebo-controlled superiority trial of the Yiqigubiao pill for the treatment of patients with chronic obstructive pulmonary disease at a stable stage

In traditional Chinese medicine (TCM), the Yiqigubiao pill is commonly used to enhance physical fitness. The current clinical trial was designed to evaluate the efficacy and safety of the Yiqigubiao pill as an adjuvant therapy for patients with stable chronic obstructive pulmonary disease (COPD). The current trial was a randomized, double-blind, placebo-controlled superiority trial. The participants were recruited from outpatients at the Traditional Chinese Medicine Hospital affiliated with Xinjiang Medical University (Ürümqi, China) between February and September 2012. All participants were patients with stable COPD that were randomized to the Yiqigubiao pill (YQGB; n=84) or placebo (Pb; n=87) groups. The occurrences of acute exacerbation (AE) of COPD during the trial were recorded. Lung function value assessments, scoring of life quality and exercise endurance, arterial blood gas analysis and serum inflammatory cytokines level determination were performed prior to and throughout the study. A total of 139 participants completed the intervention and 132 participants completed the study. The interval between the initial intervention and the first AECOPD was greater in the YQGB group compared with the Pb group (P<0.01). The incidence rate of AECOPD was lower in the YQGB group than in the Pb group (P<0.01). Subsequent to the intervention or at the end of the study, the 6-min walking distance difference was longer in the YQGB group compared with the Pb group (P<0.01). The scores reflecting life quality decline became lower in the YQGB group (P<0.01). The serum levels of proinflammatory factors were downregulated to a greater extent in the YQGB group compared with the Pb group. Thus, the Yiqigubiao pill is an efficient and safe adjuvant therapy for the treatment of stable patients with COPD.

Breastfeeding modifies the effects of environment tobacco smoke exposure on respiratory diseases and symptoms in Chinese children: the Seven Northeast Cities Study

To evaluate the potential effect of interaction between breastfeeding and environmental tobacco smoke (ETS) exposure on respiratory health, we studied 31 049 children (aged 2-14 years) from 25 districts of seven cities in northeast China. Parents of the children completed standardized questionnaires that characterized the children's histories of respiratory symptoms and illness, feeding methods, ETS exposure, and other associated risk factors. Breastfeeding was defined as having been mainly breastfed for 3 months or more. The results showed that the association of ETS exposure with childhood respiratory conditions/diseases was modified by breastfeeding, and the association for nonbreastfed children was stronger than that for breastfed children. In particular, for nonbreastfed children, the odds ratios (ORs) for the effect of current ETS exposure asthma was 1.71 (95% CI: 1.43-2.05); however, the OR for breastfed children was 1.33 (95% CI: 1.20-1.48), indicating that the interactions between breastfeeding and current ETS exposure on asthma were statistically significant (P = 0.019). When stratified by school (kindergarten vs. elementary school), breastfeeding was more protective for asthma-related symptoms among children from kindergarten. In conclusion, this study shows that breastfeeding is associated with smaller associations between ETS exposure and respiratory conditions in children, suggesting that breastfeeding reduces susceptibility to the respiratory effects of ETS.

Murine models of cardiovascular comorbidity in chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiovascular disease (CVD). Currently, COPD patients with atherosclerosis (i.e., the most important underlying cause of CVD) receive COPD therapy complemented with standard CVD therapy. This may, however, not be the most optimal treatment. To investigate the link between COPD and atherosclerosis and to develop specific therapeutic strategies for COPD patients with atherosclerosis, a substantial number of preclinical studies using murine models have been performed. In this review, we summarize the currently used murine models of COPD and atherosclerosis, both individually and combined, and discuss the relevance of these models for studying the pathogenesis and development of new treatments for COPD patients with atherosclerosis. Murine and clinical studies have provided complementary information showing a prominent role for systemic inflammation and oxidative stress in the link between COPD and atherosclerosis. These and other studies showed that murine models for COPD and atherosclerosis are useful tools and can provide important insights relevant to understanding the link between COPD and CVD. More importantly, murine studies provide good platforms for studying the potential of promising (new) therapeutic strategies for COPD patients with CVD.

Inflammatory Diseases of the Lung Induced by Conventional Cigarette Smoke: A Review

Smoking-induced lung diseases were extremely rare prior to the 20th century. With commercialization and introduction of machine-made cigarettes, worldwide use skyrocketed and several new pulmonary diseases have been recognized. The majority of pulmonary diseases caused by cigarette smoke (CS) are inflammatory in origin. Airway epithelial cells and alveolar macrophages have altered inflammatory signaling in response to CS, which leads to recruitment of lymphocytes, eosinophils, neutrophils, and mast cells to the lungs-depending on the signaling pathway (nuclear factor-κB, adenosine monophosphate-activated protein kinase, c-Jun N-terminal kinase, p38, and signal transducer and activator of transcription 3) activated. Multiple proteins are upregulated and secreted in response to CS exposure, and many of these have immunomodulatory activities that contribute to disease pathogenesis. In particular, metalloproteases 9 and 12, surfactant protein D, antimicrobial peptides (LL-37 and human β defensin 2), and IL-1, IL-6, IL-8, and IL-17 have been found in higher quantities in the lungs of smokers with ongoing inflammation. However, many underlying mechanisms of smoking-induced inflammatory diseases are not yet known. We review here the known cellular and molecular mechanisms of CS-induced diseases, including COPD, respiratory bronchiolitis-interstitial lung disease, desquamative interstitial pneumonia, acute eosinophilic pneumonia, chronic rhinosinusitis, pulmonary Langerhans cell histiocytosis, and chronic bacterial infections. We also discuss inflammation induced by secondhand and thirdhand smoke exposure and the pulmonary diseases that result. New targeted antiinflammatory therapeutic options are currently under investigation and hopefully will yield promising results for the treatment of these highly prevalent smoking-induced diseases.

Periodontal disease severity and cancer risk in postmenopausal women: the Buffalo OsteoPerio Study

PURPOSE

Few prospective studies have reported on relationships between objective periodontal disease (PD) measures and cancer risk. This association was examined in 1,337 postmenopausal women participating in the Buffalo OsteoPerio Study.

METHODS

Oral alveolar crestal height (ACH) was measured using oral radiographs. Incident cancers were adjudicated with medical records. Hazard ratios (HRs) and 95 % confidence intervals (CIs) for associations between ACH and incident cancer outcomes were estimated using Cox proportional hazards models.

RESULTS

There were 203 confirmed total incident cancer cases during follow-up (12.2 ± 4.2 years). After adjusting for age and smoking, there were no statistically significant associations between ACH-defined PD categories and total cancer risk (mild/moderate vs. none: HR 1.33, 95 % CI 0.91-1.94; severe vs. none: HR 1.20, 95 % CI 0.77-1.86). ACH-defined PD categories were not associated with common site-specific cancers. Whole-mouth mean and worst-site ACH (per 1 mm loss) were significantly associated with increased risk of lung (adjusted HR 1.81, 95 % CI 1.30-2.54; adjusted HR 1.34, 95 % CI 1.08-1.66, respectively), but not total or other site-specific cancer. Smoking status modified the associations between continuous ACH variables and total cancer risk; measures of PD were associated with total cancer among smokers but not never smokers (interaction p = 0.02 and p < 0.01 for whole-mouth mean and worst-site ACH, respectively).

CONCLUSIONS

ACH-defined PD was associated with total cancer risk in ever but not never smoking postmenopausal women. Whole-mouth mean and worst-site ACH were associated with increased lung cancer risk. However, these results need to be interpreted cautiously given the small number of lung cancer cases (n = 18). Further research utilizing a larger sample is warranted to confirm the relationships among oral bone loss, site-specific cancers, and total cancer.

Enrichment of immunoregulatory proteins in the biomolecular corona of nanoparticles within human respiratory tract lining fluid

When inhaled nanoparticles deposit in the lungs, they transit through respiratory tract lining fluid (RTLF) acquiring a biomolecular corona reflecting the interaction of the RTLF with the nanomaterial surface. Label-free snapshot proteomics was used to generate semi-quantitative profiles of corona proteins formed around silica (SiO2) and poly(vinyl) acetate (PVAc) nanoparticles in RTLF, the latter employed as an archetype drug delivery vehicle. The evolved PVAc corona was significantly enriched compared to that observed on SiO2 nanoparticles (698 vs. 429 proteins identified); however both coronas contained a substantial contribution from innate immunity proteins, including surfactant protein A, napsin A and complement (C1q and C3) proteins. Functional protein classification supports the hypothesis that corona formation in RTLF constitutes opsonisation, preparing particles for phagocytosis and clearance from the lungs. These data highlight how an understanding of the evolved corona is necessary for the design of inhaled nanomedicines with acceptable safety and tailored clearance profiles.

FROM THE CLINICAL EDITOR

Inhaled nanoparticles often acquire a layer of protein corona while they go through the respiratory tract. Here, the authors investigated the identity of these proteins. The proper identification would improve the understanding of the use of inhaled nanoparticles in future therapeutics.

The Role of Innate and Adaptive Immune Cells in the Immunopathogenesis of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a chronic and progressive inflammatory disease of the airways and lungs that results in limitations of continuous airflow and is caused by exposure to noxious gasses and particles. A major cause of morbidity and mortality in adults, COPD is a complex disease pathologically mediated by many inflammatory pathways. Macrophages, neutrophils, dendritic cells, and CD8+ T-lymphocytes are the key inflammatory cells involved in COPD. Recently, the non-coding small RNA, micro-RNA, have also been intensively investigated and evidence suggest that it plays a role in the pathogenesis of COPD. Here, we discuss the accumulated evidence that has since revealed the role of each inflammatory cell and their involvement in the immunopathogenesis of COPD. Mechanisms of steroid resistance in COPD will also be briefly discussed.

Immune Dysfunction in Patients with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a complex chronic disease. Chronic inflammation is the hallmark of COPD, involving the interplay of a wide variety of cells in the lung microenvironment. Cigarette smoke (CS) induces chronic lung inflammation and is considered a key etiological factor in the development and pathogenesis of COPD. Structural and inflammatory cells in the lung respond to CS exposure by releasing proinflammatory mediators that recruit additional inflammatory immune cells, which collectively contribute to the establishment of a chronic inflammatory microenvironment. Chronic inflammation contributes to lung damage, compromises innate and adaptive immune responses, and facilitates the recurrent episodes of respiratory infection that punctuate and further contribute to the pathological manifestations of the stable disease. A number of studies support the conclusion that immune dysfunction leads to exacerbations and disease severity in COPD. Our group has clearly demonstrated that CS exacerbates lung inflammation and compromises immunity to respiratory pathogens in a mouse model of COPD. We have also investigated the phenotype of immune cells in patients with COPD compared with healthy control subjects and found extensive immune dysfunction due to the presence and functional activity of T regulatory cells, CD4(+)PD-1(+) exhausted effector T cells and myeloid-derived suppressor cells. Manipulation of these immunosuppressive networks in COPD could provide a rational strategy to restore functional immune responses, reduce exacerbations, and improve lung function. In this review, we discuss the role of immune dysfunction in COPD that may contribute to recurrent respiratory infections and disease severity.

IL-17A and the Promotion of Neutrophilia in Acute Exacerbation of Chronic Obstructive Pulmonary Disease

RATIONALE

Nontypeable Haemophilus influenzae (NTHi) causes acute exacerbation of chronic obstructive pulmonary disease (AECOPD). IL-17A is central for neutrophilic inflammation and has been linked to COPD pathogenesis.

OBJECTIVES

We investigated whether IL-17A is elevated in NTHi-associated AECOPD and required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke.

METHODS

Experimental studies with cigarette smoke and NTHi infection were pursued in gene-targeted mice and using antibody intervention. IL-17A was measured in sputum collected from patients with COPD at baseline, during, and after AECOPD.

MEASUREMENTS AND MAIN RESULTS

Exacerbated airway neutrophilia in cigarette smoke-exposed mice infected with NTHi was associated with an induction of IL-17A. In agreement, elevated IL-17A was observed in sputum collected during NTHi-associated AECOPD, compared with samples collected before or after the event. NTHi-exacerbated neutrophilia and induction of neutrophil chemoattractants over the background of cigarette smoke, as observed in wild-type mice, was absent in Il17a(-/-) mice and in mice treated with a neutralizing anti-IL-17A antibody. Further studies revealed that IL-1 receptor (R)1 signaling was required for IL-17A-dependent neutrophilia. Moreover, deficiency or therapeutic neutralization of IL-17A did not increase bacterial burden or delay bacterial clearance.

CONCLUSIONS

IL-17A is induced during NTHi-associated AECOPD. Functionally, IL-1R1-dependent IL-17A is required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke. Targeting IL-17A in AECOPD may thus be beneficial to reduce neutrophil recruitment to the airways.

Longitudinal Study of DNA Methylation of Inflammatory Genes and Cancer Risk

BACKGROUND

Chronic inflammation plays a key role in cancer etiology. DNA methylation modification, one of the epigenetic mechanisms regulating gene expression, is considered a hallmark of cancer. Human and animal models have identified numerous links between DNA methylation and inflammatory biomarkers. Our objective was to prospectively and longitudinally examine associations between methylation of four inflammatory genes and cancer risk.

METHODS

We included 795 Normative Aging Study participants with blood drawn one to four times from 1999 to 2012 (median follow-up, 10.6 years). Promoter DNA methylation of IL6, ICAM-1, IFN, and TLR2 in blood leukocytes was measured using pyrosequencing at multiple CpG sites and averaged by gene for data analysis. We used Cox regression models to examine prospective associations of baseline and time-dependent methylation with cancer risk and compared mean methylation differences over time between cancer cases and cancer-free participants.

RESULTS

Baseline IFN hypermethylation was associated with all-cancer (HR, 1.49; P = 0.04) and prostate cancer incidence (HR, 1.69; P = 0.02). Baseline ICAM-1 and IL6 hypermethylation were associated with prostate cancer incidence (HR, 1.43; P = 0.02; HR, 0.70; P = 0.03, respectively). In our time-dependent analyses, IFN hypermethylation was associated with all-cancer (HR, 1.79; P = 0.007) and prostate cancer (HR, 1.57; P = 0.03) incidence; and ICAM-1 and IL6 hypermethylation were associated with prostate cancer incidence (HR, 1.39; P = 0.02; HR, 0.69; P = 0.03, respectively). We detected significant ICAM-1 hypermethylation in cancer cases (P = 0.0003) 10 to 13 years prediagnosis.

CONCLUSION

Hypermethylation of IFN and ICAM-1 may play important roles in early carcinogenesis, particularly that of prostate cancer.

IMPACT

These methylation changes could inform the development of early detection biomarkers and potential treatments of inflammation-related carcinogenesis.

The Lung Immune Response to Nontypeable Haemophilus influenzae (Lung Immunity to NTHi)

Haemophilus influenzae is divided into typeable or nontypeable strains based on the presence or absence of a polysaccharide capsule. The typeable strains (such as type b) are an important cause of systemic infection, whilst the nontypeable strains (designated as NTHi) are predominantly respiratory mucosal pathogens. NTHi is present as part of the normal microbiome in the nasopharynx, from where it may spread down to the lower respiratory tract. In this context it is no longer a commensal and becomes an important respiratory pathogen associated with a range of common conditions including bronchitis, bronchiectasis, pneumonia, and particularly chronic obstructive pulmonary disease. NTHi induces a strong inflammatory response in the respiratory tract with activation of immune responses, which often fail to clear the bacteria from the lung. This results in recurrent/persistent infection and chronic inflammation with consequent lung pathology. This review will summarise the current literature about the lung immune response to nontypeable Haemophilus influenzae, a topic that has important implications for patient management.

Regulation of immunoproteasome function in the lung

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

Why do we need a nonhuman primate model of smoking-induced COPD?

This Commentary highlights the article by Polverino et al, describing the development of a novel nonhuman primate model of cigarette smoke-induced chronic obstructive pulmonary disease.