Environmentally induced changes in immunological function: acute and chronic effects of inhalation of tobacco smoke and other atmospheric contaminants in man and experimental animals

Association between secondhand smoke exposure and rheumatoid arthritis in US never-smoking adults: a cross-sectional study from NHANES

While smoking is widely acknowledged as a risk factor for rheumatoid arthritis (RA), the connection between secondhand smoke (SHS) exposure and RA in never-smoking adults remains limited and inconsistent. This study aims to explore and quantify this association using serum cotinine levels. We conducted a cross-sectional study with 14,940 adults who self-report as never smokers, using National Health and Nutrition Examination Survey data from 1999 to 2018. Based on previous literature, SHS exposure was categorized into four groups according to serum cotinine levels. Compared to individuals in the unexposed group (serum cotinine < 0.05 ng/mL), the adjusted odds ratio (OR) for RA was 1.37 (95% CI 1.14-1.64, p = 0.001) in the low exposure group (serum cotinine at 0.05 to 0.99 ng/mL) after adjusting for covariates. However, no significant association was found in the moderate exposure group (serum cotinine at 1 to 10 ng/mL) or the heavy exposure group (serum cotinine ≥ 10 ng/mL). Furthermore, we detected a non-linear, positively saturated correlation between the cotinine levels after log2 transformation and RA, with a turning point at approximately - 2.756 ng/mL (OR = 1.163, 95% CI 1.073-1.261, p = 0.0002). The stability of the results was confirmed by subgroup analysis.

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

Purpose

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

Patients and Methods

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

Results

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

Conclusion

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

Inflammatory profile of apical periodontitis exacerbated by cigarette smoke inhalation: Histological and immunohistochemical analysis in rats

AIM

The aim of this study was to evaluate the effects of cigarette smoke inhalation (CSI) on inflammation, pro-inflammatory mediators and haematological parameters in rats with induced apical periodontitis (AP).

METHODOLOGY

Thirty-two 3-month-old male Wistar rats were divided into four experimental groups (n = 8): C-Control; S-rats with CSI; AP-rats with AP; and SAP-rats with CSI + AP. Animals in groups S and SAP inhaled cigarette smoke by remaining inside a smoking chamber for 8 min, three times daily, for 50 days. After 20 days of smoke inhalation, animals in AP and SAP groups had the pulps of the lower right first molar exposed to oral environment for 30 days to induce AP. In these subsequent 30 days, animals in group S and SAP continued with CSI. On Day 50, animals were euthanized and mandibles were histologically processed to assess inflammatory infiltrate, immunohistochemical interleukins (IL-1β, IL-6 and TNF-α), and blood samples collected for laboratory analysis. The Mann-Whitney test was performed for non-parametric data and the pairwise analyses of Student's t-test for parametric data, with a significance level of p < .050.

RESULTS

Inflammatory infiltrate was moderate in AP group and more severe in the SAP (p = .010). The interleukins IL-6, IL-1β and TNF-α were higher in SAP group (p < .001) when compared to the AP group. A greater number of red blood cells (p = .010), haemoglobin (p = .007) and neutrophils (p = .014) were observed in the SAP group in comparison with the AP group.

CONCLUSION

Cigarette smoke inhalation induced a more severe inflammatory infiltrate, with increased levels of pro-inflammatory cytokines and changes in haematological parameters in rats with induced AP. Thus, CSI aggravated AP, exacerbating the inflammatory response.

Status and frontier analysis of indoor PM2.5-related health effects: a bibliometric analysis

Epidemiological data indicate atmospheric particulate matter, especially fine particulate matter (PM_2.5), has many negative effects on human health. Of note, people spend about 90% of their time indoors. More importantly, according to the World Health Organization (WHO) statistics, indoor air pollution causes nearly 1.6 million deaths each year, and it is considered as one of the major health risk factors. In order to obtain a deeper understanding of the harmful effects of indoor PM_2.5 on human health, we used bibliometric software to summarize articles in this field. In conclusion, since 2000, the annual publication volume has increased year by year. America topped the list for the number of articles, and Professor Petros Koutrakis and Harvard University were the author and institution with the most published in this research area, respectively. Over the past decade, scholars gradually paid attention to molecular mechanisms, therefore, the toxicity can be better explored. Particularly, apart from timely intervention and treatment for adverse consequences, it is necessary to effectively reduce indoor PM_2.5 through technologies. In addition, the trend and keywords analysis are favorable ways to find out future research hotspots. Hopefully, various countries and regions strengthen academic cooperation and integration of multi-disciplinary.

Predictors of remission in rheumatoid arthritis patients treated with biologics: a systematic review and meta-analysis

Biologics have emerged as an effective treatment of rheumatoid arthritis (RA). However, there is a significant proportion of patients who fail to respond to biologics. Identifying the predictors that affect the response to biologics remains challenging. A comprehensive literature search of PubMed, Embase, and Web of Science databases was conducted through May 1, 2022. We included all studies that used a multivariate model to assess for the predictors of remission in RA patients treated with biologics. We calculated pooled odds ratios (OR) with 95% confidence intervals (CI) for risk factors reported in ≥ 3 studies using a random-effects model. A total of 16,934 patients with RA who were treated with biologics were included in twenty-one studies. Our study showed that old age (OR 0.98 (0.97, 0.99), P < 0.00001), female gender (OR 0.66 (0.56, 0.77), P < 0.00001), smoking history (OR 0.86 (0.75, 0.99), P 0.04), obesity (OR 0.95 (0.91, 0.99), P 0.02), poor functional status (OR 0.62 (0.48, 1.27), P < 0.00001), high disease activity (OR 0.90 (0.85, 0.96), P 0.0005), and elevated erythrocyte sedimentation rate (OR 0.99 (0.98, 1.00), P 0.009) were poor predictors of remission. On the other hand, positive anti-citrullinated protein antibodies (OR 2.52 (1.53, 4.12), P 0.0003) was associated with high remission rate. Old age, female gender, obesity, smoking history, poor functional status, high disease activity, and elevated ESR at the time of diagnosis have been associated with poor response to biologics. Our findings could help establish a risk stratification model for predicting the remission rate in RA patients receiving biologics.

High-Risk Human Papillomavirus Infection in Lung Cancer: Mechanisms and Perspectives

Lung cancer is a very prevalent and heterogeneous group of malignancies, and most of them are etiologically associated with tobacco smoking. However, viral infections have been detected in lung carcinomas, with high-risk human papillomaviruses (HR-HPVs) being among them. The role of HR-HPVs in lung cancer has been considered to be controversial. This issue is due to the highly variable presence of this virus in lung carcinomas worldwide, and the low viral load frequently that is detected. In this review, we address the epidemiological and mechanistic findings regarding the role of HR-HPVs in lung cancer. Some mechanisms of HR-HPV-mediated lung carcinogenesis have been proposed, including (i) HPV works as an independent carcinogen in non-smoker subjects; (ii) HPV cooperates with carcinogenic compounds present in tobacco smoke; (iii) HPV promotes initial alterations being after cleared by the immune system through a "hit and run" mechanism. Additional research is warranted to clarify the role of HPV in lung cancer.

Longitudinal change in blood DNA epigenetic signature after smoking cessation

Cigarette smoking is associated with epigenetic changes that may be reversible following smoking cessation. Whole blood DNA methylation was evaluated in Framingham Heart Study Offspring (n = 169) and Third Generation (n = 30) cohort participants at two study visits 6 years apart and in Atherosclerosis Risk in Communities (ARIC) study (n = 222) participants at two study visits 20 years apart. Changes in DNA methylation (delta β values) at 483,565 cytosine-phosphate-guanine (CpG) sites and differentially methylated regions (DMRs) were compared between participants who were current, former, or never smokers at both visits (current-current, former-former, never-never, respectively), versus those who quit in the interim (current-former). Interim quitters had more hypermethylation at four CpGs annotated to AHRR, one CpG annotated to F2RL3, and one intergenic CpG (cg21566642) compared with current-current smokers (FDR < 0.02 for all), and two significant DMRs were identified. While there were no significant differentially methylated CpGs in the comparison of interim quitters and former-former smokers, 106 DMRs overlapping with small nucleolar RNA were identified. As compared with all non-smokers, current-current smokers additionally had more hypermethylation at two CpG sites annotated to HIVEP3 and TMEM126A, respectively, and another intergenic CpG (cg14339116). Gene transcripts associated with smoking cessation were implicated in immune responses, cell homoeostasis, and apoptosis. Smoking cessation is associated with early reversion of blood DNA methylation changes at CpG sites annotated to AHRR and F2RL3 towards those of never smokers. Associated gene expression suggests a role of longitudinal smoking-related DNA methylation changes in immune response processes.

Genome-wide methylation and expression analyses reveal the epigenetic landscape of immune-related diseases for tobacco smoking

BACKGROUND

Smoking is a major causal risk factor for lung cancer, chronic obstructive pulmonary disease (COPD), cardiovascular disease (CVD), and is the main preventable cause of deaths in the world. The components of cigarette smoke are involved in immune and inflammatory processes, which may increase the prevalence of cigarette smoke-related diseases. However, the underlying molecular mechanisms linking smoking and diseases have not been well explored. This study was aimed to depict a global map of DNA methylation and gene expression changes induced by tobacco smoking and to explore the molecular mechanisms between smoking and human diseases through whole-genome bisulfite sequencing (WGBS) and RNA-sequencing (RNA-seq).

RESULTS

We performed WGBS on 72 samples (36 smokers and 36 nonsmokers) and RNA-seq on 75 samples (38 smokers and 37 nonsmokers), and cytokine immunoassay on plasma from 22 males (9 smokers and 13 nonsmokers) who were recruited from the city of Jincheng in China. By comparing the data of the two groups, we discovered a genome-wide methylation landscape of differentially methylated regions (DMRs) associated with smoking. Functional enrichment analyses revealed that both smoking-related hyper-DMR genes (DMGs) and hypo-DMGs were related to synapse-related pathways, whereas the hypo-DMGs were specifically related to cancer and addiction. The differentially expressed genes (DEGs) revealed by RNA-seq analysis were significantly enriched in the "immunosuppression" pathway. Correlation analysis of DMRs with their corresponding gene expression showed that genes affected by tobacco smoking were mostly related to immune system diseases. Finally, by comparing cytokine concentrations between smokers and nonsmokers, we found that vascular endothelial growth factor (VEGF) was significantly upregulated in smokers.

CONCLUSIONS

In sum, we found that smoking-induced DMRs have different distribution patterns in hypermethylated and hypomethylated areas between smokers and nonsmokers. We further identified and verified smoking-related DMGs and DEGs through multi-omics integration analysis of DNA methylome and transcriptome data. These findings provide us a comprehensive genomic map of the molecular changes induced by smoking which would enhance our understanding of the harms of smoking and its relationship with diseases.

Cigarette smoke alters inflammatory genes and the extracellular matrix - investigations on viable sections of peripheral human lungs

Chronic obstructive pulmonary disease (COPD) is a complex chronic respiratory disorder often caused by cigarette smoke. Cigarette smoke contains hundreds of toxic substances. In our study, we wanted to identify initial mechanisms of cigarette smoke induced changes in the distal lung. Viable slices of human lungs were exposed 24 h to cigarette smoke condensate, and the dose–response profile was analyzed. Non-toxic condensate concentrations and lipopolysaccharide were used for further experiments. COPD-related protein and gene expression was measured. Cigarette smoke condensate did not induce pro-inflammatory cytokines and most inflammation-associated genes. In contrast, lipopolysaccharide significantly induced IL-1α, IL-1β, TNF-α and IL-8 (proteins) and IL1B, IL6, and TNF (genes). Interestingly, cigarette smoke condensate induced metabolism- and extracellular matrix–associated proteins and genes, which were not influenced by lipopolysaccharide. Also, a significant regulation of CYP1A1 and CYP1B1, as well as MMP9 and MMP9/TIMP1 ratio, was observed which resembles typical findings in COPD. In conclusion, our data show that cigarette smoke and lipopolysaccharide induce significant responses in human lung tissue ex vivo, giving first hints that COPD starts early in smoking history.

Exposure to Tobacco Smoking Induces a subset of Activated Tumor-resident Tregs in Non-Small Cell Lung Cancer

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Tumor-specific smoking-induced differentially expressed genes are different in male and female patients.

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A smoking-related tumor-specific Treg subset is defined, highly expressed ADAM12.

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ADAM12⁺ CTLA4⁺ Tregs actively communicated with exhausted T cells than other Tregs.

Tobacco smoking is the major cause of non-small-cell-lung cancer (NSCLC). However, it is barely known how smoking impact the tumor immune environment (TIME) of lung cancer.

We integrated single-cell RNA-seq and bulk RNA-seq data from several studies to systematically study the impact of smoking on T cells in treatment naïve NSCLC patients. We defined a set of smoking-induced differentially expressed genes (SIDEGs) in different cells in TIME.. Specifically, we defined a smoking-related tumor-specific Treg subset, ADAM12⁺ CTLA4⁺ Tregs according to the trajectory analysis and highly express genes in cell adhesion pathways and lipid metabolism. Using independent datasets from treatment naïve patients, we found that the fraction of ADAM12⁺ CTLA4⁺ Tregs are significantly increased in patients with smoking history. Moreover, the fraction of ADAM12⁺ CTLA4⁺ Tregs are positively correlated with the fraction of exhausted T cells. Additionally, we reconstructed the spatial organization of the tumor immune microenvironment and found that ADAM12⁺ CTLA4⁺ Tregs more actively communicate with LAYN⁺CD8⁺ exhausted T cells compared with ADAM12⁻CTLA4⁺ Tregs.

Our data demonstrate that smoking induced a unique subset of tumor-specific activated Tregs which interact with exhausted T cells in the TIME. Our findings not only explained how smoking impact the TIME but also provide new targets and biomarkers for precision immunotherapy of lung cancer.

Host Immune-Metabolic Adaptations Upon Mycobacterial Infections and Associated Co-Morbidities

Mycobacterial diseases are a major public health challenge. Their causative agents include, in order of impact, members of the Mycobacterium tuberculosis complex (causing tuberculosis), Mycobacterium leprae (causing leprosy), and non-tuberculous mycobacterial pathogens including Mycobacterium ulcerans. Macrophages are mycobacterial targets and they play an essential role in the host immune response to mycobacteria. This review aims to provide a comprehensive understanding of the immune-metabolic adaptations of the macrophage to mycobacterial infections. This metabolic rewiring involves changes in glycolysis and oxidative metabolism, as well as in the use of fatty acids and that of metals such as iron, zinc and copper. The macrophage metabolic adaptations result in changes in intracellular metabolites, which can post-translationally modify proteins including histones, with potential for shaping the epigenetic landscape. This review will also cover how critical tuberculosis co-morbidities such as smoking, diabetes and HIV infection shape host metabolic responses and impact disease outcome. Finally, we will explore how the immune-metabolic knowledge gained in the last decades can be harnessed towards the design of novel diagnostic and therapeutic tools, as well as vaccines.

Nicotine promotes breast cancer metastasis by stimulating N2 neutrophils and generating pre-metastatic niche in lung

Smoking has a profound impact on tumor immunity, and nicotine, which is the major addictive component of smoke, is known to promote tumor progression despite being a non-carcinogen. In this study, we demonstrate that chronic exposure of nicotine plays a critical role in the formation of pre-metastatic niche within the lungs by recruiting pro-tumor N2-neutrophils. This pre-metastatic niche promotes the release of STAT3-activated lipocalin 2 (LCN2), a secretory glycoprotein from the N2-neutrophils, and induces mesenchymal-epithelial transition of tumor cells thereby facilitating colonization and metastatic outgrowth. Elevated levels of serum and urine LCN2 is elevated in early-stage breast cancer patients and cancer-free females with smoking history, suggesting that LCN2 serve as a promising prognostic biomarker for predicting increased risk of metastatic disease in female smoker(s). Moreover, natural compound, salidroside effectively abrogates nicotine-induced neutrophil polarization and consequently reduced lung metastasis of hormone receptor-negative breast cancer cells. Our findings suggest a pro-metastatic role of nicotine-induced N2-neutrophils for cancer cell colonization in the lungs and illuminate the therapeutic use of salidroside to enhance the anti-tumor activity of neutrophils in breast cancer patients.

Smoking is known to impact tumor immunity and promote tumor progression. Here, the authors show that chronic nicotine exposure promotes the lung pre-metastatic niche formation by recruiting pro-tumor N2-neutrophils that release lipocalin-2.

High-Risk Human Papillomavirus and Tobacco Smoke Interactions in Epithelial Carcinogenesis

Cervical, anogenital, and some head and neck cancers (HNC) are etiologically associated with high-risk human papillomavirus (HR-HPV) infection, even though additional cofactors are necessary. Epidemiological studies have established that tobacco smoke (TS) is a cofactor for cervical carcinogenesis because women who smoke are more susceptible to cervical cancer when compared to non-smokers. Even though such a relationship has not been established in HPV-related HNC, a group of HPV positive patients with this malignancy are smokers. TS is a complex mixture of more than 4500 chemical compounds and approximately 60 of them show oncogenic properties such as benzo[α]pyrene (BaP) and nitrosamines, among others. Some of these compounds have been evaluated for carcinogenesis through experimental settings in collaboration with HR-HPV. Here, we conducted a comprehensive review of the suggested molecular mechanisms involved in cooperation with both HR-HPV and TS for epithelial carcinogenesis. Furthermore, we propose interaction models in which TS collaborates with HR-HPV to promote epithelial cancer initiation, promotion, and progression. More studies are warranted to clarify interactions between oncogenic viruses and chemical or physical environmental factors for epithelial carcinogenesis.

Combustible Cigarette and Smokeless Tobacco Product Preparations Differentially Regulate Intracellular Calcium Mobilization in HL60 Cells

Changes in the level of intracellular calcium ([Ca²⁺]_i) are central to leukocyte signaling and immune response. Although evidence suggests that cigarette smoking affects inflammatory response via an increase in intracellular calcium, it remains unclear if the use of smokeless tobacco (e.g., moist snuff) elicits a similar response. In this study, we evaluated the effects of tobacco product preparations (TPPs), including total particulate matter (TPM) from 3R4F reference cigarettes, smokeless tobacco extract (STE) from 2S3 reference moist snuff, and nicotine alone on Ca²⁺ mobilization in HL60 cells. Treatment with TPM, but not STE or nicotine alone, significantly increased [Ca²⁺]_i in a concentration-dependent manner in HL60 cells. Moreover, TPM-induced [Ca²⁺]_i increase was not related to extracellular Ca²⁺ and did not require the activation of the IP3 pathway nor involved the transient receptor potential (TRP) channels. Our findings indicate that, in cells having either intact or depleted endoplasmic reticulum (ER) Ca²⁺ stores, TPM-mediated [Ca²⁺]_i increase involves cytosolic Ca²⁺ pools other than thapsigargin-sensitive ER Ca²⁺ stores. These results, for the first time, demonstrate that TPM triggers [Ca²⁺]_i increases, while significantly higher nicotine equivalent doses of STE or nicotine alone, did not affect [Ca²⁺]_i under the experimental conditions. In summary, our study suggests that in contrast with STE or nicotine preparations, TPM activates Ca²⁺ signaling pathways in HL60 cells. The differential effect of combustible and non-combustible TPPs on Ca²⁺ mobilization could be a useful in vitro endpoint for tobacco product evaluation.

Adenoidal Immune Response in the Context of Inflammation and Allergy

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The mucosal-associated lymphoid tissues of the upper respiratory tract, including adenoids and palatine tonsils, are considered as the first line of defense against respiratory infections, being important effector organs in both mucosal-type and systemic-type adaptive immunity. They are strategically located for mediating both local and regional immune functions, as they are exposed to antigens from both the inhaled air (allergens and pathogens) and the alimentary tract. Adenoids play a major role in the early and effective immune responses against viral and bacterial upper airway infections, as well as in the development of allergic reactions to respiratory allergens, being influenced by several environmental antigens and pollutants, such as tobacco smoke. In addition, recent studies have focused on new immune-modulating strategies for adenoidal cells as a preventive and therapeutic approach for chronic upper airways inflammation.

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Herein, we aimed to summarize what is known about the cellular and molecular mechanisms regulating adenoidal immune responses in the context of inflammation and allergy, with particular reference to scientific literature published within the last five years.

Effects of smoking on the association of human leukocyte antigen with ulcerative colitis

BACKGROUND AND AIM

Tobacco smoking is a risk factor for gastrointestinal disorders, causing mucosal damage and impairing immune responses. However, smoking has been found to be protective against ulcerative colitis (UC). Human leukocyte antigen (HLA) is a major susceptibility locus for UC, and HLA-DRB1*15:02 has the strongest effect in Asians. This study investigated the effects of smoking on the association between HLA and UC.

METHODS

The study enrolled 882 patients with UC, including 526 never, 151 current, and 205 former smokers, and 3091 healthy controls, including 2124 never, 502 current, and 465 former smokers. Smoking-stratified analyses of HLA data were performed using a case-control approach.

RESULTS

In a case-control approach, HLA-DRB1*15:02 was associated with UC in never smokers (OR_{never smokers}  = 3.20, P_{never smokers}  = 7.88 × 10^-23 ) but not in current or former smokers (P_{current smokers}  = 0.72 and P_{former smokers}  = 0.33, respectively). In current smokers, HLA-DQB1*06 was associated with UC (OR_{current smokers}  = 2.59, P_{current smokers}  = 6.39 × 10^-12 ). No variants reached genome-wide significance in former smokers.

CONCLUSIONS

An association between UC and HLA-DRB1*15:02 was limited to never smokers. Our findings highlight that tobacco smoking modifies the effects of HLA on the risk of UC.

Combination of TLR8 and TLR4 agonists reduces the degrading effects of nicotine on DC-NK mediated effector T cell generation

The magnitude of immune responses to vaccination is a critical factor in determining protection from disease. It is known that cigarette smoke dampens the immune system and increases the risk of vaccine-preventable diseases. We reported that nicotine, the immunosuppressive component of cigarette smoke, disrupts the differentiation and functional properties of DC, which are pivotal in the initiation of immune response to vaccines. We also reported that TLR agonists act in synergy and boost DC maturation, DC-NK crosstalk and ultimately naïve T cell polarization into effector Th1 and Tc1 cells. Here, we investigated whether the combination of TLR agonists could diminish the degrading effects of nicotine on DC-NK mediated effector T cell generation. We found that none of TLR agonists, single or combined, were able to diminish completely the adverse effects of nicotine on DC. However, TLR3, TLR4, and TLR8 agonists acted as the most effective adjuvants to increase the expression levels of antigen-presenting, costimulatory molecules and production of cytokines by nicotine-exposed DC (nicDC). When combined, TLR3 + 8 and TLR4 + 8 synergistically optimized nicDC maturation and IFN-γ secretion from nicotine-exposed NK (nicNK) during co-cultures. Interestingly, in contrast to DC-NK-T, co-cultures of nicDC-nicNK-T treated with TLR3 + 8 or TLR4 + 8 agonists produced a similar frequency of effector memory Th1 and Tc1 cells. However, the effector cells from TLR4 + 8 followed by TLR3 + 8 treated nicDC-nicNK-T co-cultures produced significantly more IFN-γ when compared with aluminum salt treated co-culture. Our data suggest that addition of appropriate TLR agonists to vaccine formulation could potentially augment the immune response to vaccination in smokers.

Tobacco Smoke Induces and Alters Immune Responses in the Lung Triggering Inflammation, Allergy, Asthma and Other Lung Diseases: A Mechanistic Review

Many studies have been undertaken to reveal how tobacco smoke skews immune responses contributing to the development of chronic obstructive pulmonary disease (COPD) and other lung diseases. Recently, environmental tobacco smoke (ETS) has been linked with asthma and allergic diseases in children. This review presents the most actual knowledge on exact molecular mechanisms responsible for the skewed inflammatory profile that aggravates inflammation, promotes infections, induces tissue damage, and may promote the development of allergy in individuals exposed to ETS. We demonstrate how the imbalance between oxidants and antioxidants resulting from exposure to tobacco smoke leads to oxidative stress, increased mucosal inflammation, and increased expression of inflammatory cytokines (such as interleukin (IL)-8, IL-6 and tumor necrosis factor α ([TNF]-α). Direct cellular effects of ETS on epithelial cells results in increased permeability, mucus overproduction, impaired mucociliary clearance, increased release of proinflammatory cytokines and chemokines, enhanced recruitment of macrophages and neutrophils and disturbed lymphocyte balance towards Th2. The plethora of presented phenomena fully justifies a restrictive policy aiming at limiting the domestic and public exposure to ETS.

Natural Killer Cell Activity and Interleukin-12 in Metabolically Healthy versus Metabolically Unhealthy Overweight Individuals

The purpose of this study was to determine whether the immune system is involved in the different metabolic circumstances in healthy and unhealthy overweight individuals. We examined the metabolic and immune characteristics of 117 overweight individuals. Subjects were classified as metabolically healthy overweight (MHO, n = 72) or metabolically unhealthy overweight (MUO, n = 45). The immune response was measured by circulating levels of natural killer (NK) cell activity and cytokines. Both groups were comparable with regards to age, sex distribution, smoking and drinking status, and body mass index. When compared to the MHO group, the MUO group showed higher systolic and diastolic blood pressure, serum levels of triglyceride, glucose, glucose-related markers, and lower levels of HDL cholesterol. Compared to the MHO group, the MUO group showed 39% lower interferon-γ levels (not significant) and 41% lower interleukin (IL)-12 levels (significant). The MUO group also showed lower NK cell activity at E:T ratios of 10:1, 5:1, 2.5:1, and 1.25:1 (all Ps < 0.05) than the MHO group. This study indicates that individuals displaying the MUO phenotype present an unfavorable immune system with lower NK cell activities under all assay conditions and lower serum levels of IL-12 than the activities and levels in similarly overweight MHO individuals. This result suggests that the immune system may be altered in overweight individuals who are at risk for overweight/obesity-related comorbidities.

Acute Immune-Inflammatory Responses to a Single Bout of Aerobic Exercise in Smokers; The Effect of Smoking History and Status

This study examined the acute immune and inflammatory responses to exercise in smokers compared to non-smokers, and further, the effect of smoking history on these immune-inflammatory responses. Fifty-four recreationally active males who were either smokers (SM; n = 27) or non-smokers (NS; n = 27) were allocated into either young (YSM, YNS) or middle-aged groups (MSM, MNS) based on smoking status. Participants were matched for fitness and smoking habits and following familiarization and baseline testing, undertook an exercise protocol that involved 40 min of cycle ergometry at 50% of VO2peak. Venous blood was obtained pre- and post- (0 min, 1, and 4 h) exercise to measure circulating leukocytes and inflammatory markers interleukin (IL)-6, IL-1β, IL-1ra, and monocyte chemoattractant protein-1 (MCP-1). Compared to MNS, MSM showed elevated basal concentrations of MCP-1, which were increased with a longer smoking history (P < 0.05). In response to exercise, YSM demonstrated an amplified IL-6 response from immediately- to 1 h-post compared to YNS. Furthermore, IL-1ra in YSM was elevated above that of YNS across all time points (P < 0.05). The MSM group had higher IL-1β at baseline when compared to YSM, although IL-1ra was greater for YSM at baseline (P < 0.05). Finally, the post-exercise leukocyte response was greater in MSM compared to YSM and non-smokers (P < 0.05). In conclusion, smoker's exhibit elevated MCP-1 and IL-1β that seem to be evident with a longer smoking history (~15 years). Furthermore, the differences in exercise-induced inflammatory responses noted in YSM may be indicative tobacco smoke exposure priming circulating leukocytes to amplify inflammatory responses.

Integrated miRNA-mRNA analysis in the habenula nuclei of mice intravenously self-administering nicotine

A considerable amount of evidence suggests that microRNAs (miRNAs) play crucial roles in the neuroadaptation of drug addiction. Habenula (Hb), one of the critical brain regions involved in reward and addiction, can be divided into two anatomically and transcriptionally distinct regions: medial habenula (MHb) and lateral habenula (LHb) nuclei. However, very few studies have compared the functional roles of these regions. Here, by using mirConnX integrator and KEGG pathway mapping, we simultaneously analysed the differential expression patterns of miRNAs and messenger RNA (mRNA) within MHb and LHb under nicotine addiction. Significantly altered miRNAs and mRNAs were found in the Hb of mice intravenously self-administering nicotine. Interestingly, some miRNAs were oppositely regulated between the MHb and the LHb, and their potential targets included various genes of cell signalling pathways related to the degeneration of fasciculus retroflexus (FR). This study provides an improved insight into the differential regulation of habenular transcripts in nicotine addiction, as well as the potential functions of miRNAs in several biological pathways involved in the nicotine addiction.

Cigarette smoking increases complication rate in forefoot surgery

BACKGROUND

Cigarette smoking is known to increase perioperative complication rates, but no study to date has examined its effect specifically in forefoot surgery. The purpose of this study was to determine whether cigarette smoking increased complications after forefoot surgery.

METHODS

The records of 602 patients who had forefoot surgery between 2008 and 2010, and for whom smoking status was known, were reviewed. Patients were categorized into 3 groups based on smoking status: active smoker, smoker in the past, or nonsmoker. Medical records were reviewed for occurrence of complications, including nonunion, delayed union, delayed wound healing, infection, and persistent pain.

RESULTS

Active smokers were found to have a notably higher complication rate (36.4%) after forefoot surgery than patients who previously (16.5%) or never (8.5%) smoked. Patients who continued to smoke in the perioperative period had the highest percentage of delayed union (3.0%), infection (9.1%), delayed wound healing (10.6%), and persistent pain (15.2%). Active cigarette smokers were 4.3 times more likely to have a complication than nonsmokers. Patients who smoked at any point in the past but quit prior to surgery were 1.9 times more likely than nonsmokers to incur a complication. The average time of smoking cessation for patients who had smoked at any point in the past but had quit prior to surgery was 17 years. For active smokers, those with a complication smoked an average of 18 cigarettes daily, while those without a complication smoked 14 cigarettes daily.

CONCLUSIONS

Before forefoot surgery, surgeons should educate patients who smoke about their increased risk of complications and encourage smoking cessation.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Smoking and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease caused by both genetic and environmental factors. Smoking has been implicated as one of the most important extrinsic risk factors for its development and severity. Recent developments have shed light on the pathophysiology of RA in smokers, including oxidative stress, inflammation, autoantibody formation and epigenetic changes. The association of smoking and the development of RA have been demonstrated through epidemiologic studies, as well as through in vivo and animal models of RA. With increased use of biological agents in addition to standard disease-modifying antirheumatic drugs (DMARDs), there has been interest in how smoking affects drug response in RA treatment. Recent evidence suggests the response and drug survival in people treated with anti-tumour necrosis factor (anti-TNF) therapy is poorer in heavy smokers, and possible immunological mechanisms for this effect are presented in the current paper.

Tobacco smoking and disability progression in multiple sclerosis: United Kingdom cohort study

Tobacco smoking has been linked to an increased risk of multiple sclerosis. However, to date, results from the few studies on the impact of smoking on the progression of disability are conflicting. The aim of this study was to investigate the effects of smoking on disability progression and disease severity in a cohort of patients with clinically definite multiple sclerosis. We analysed data from 895 patients (270 male, 625 female), mean age 49 years with mean disease duration 17 years. Forty-nine per cent of the patients were regular smokers at the time of disease onset or at diagnosis (ever-smokers). Average disease severity as measured by multiple sclerosis severity score was greater in ever-smokers, by 0.68 (95% confidence interval: 0.36-1.01). The risk of reaching Expanded Disability Status Scale score milestones of 4 and 6 in ever-smokers compared to never-smokers was 1.34 (95% confidence interval: 1.12-1.60) and 1.25 (95% confidence interval: 1.02-1.51) respectively. Current smokers showed 1.64 (95% confidence interval: 1.33-2.02) and 1.49 (95% confidence interval: 1.18-1.86) times higher risk of reaching Expanded Disability Status Scale scores 4 and 6 compared with non-smokers. Ex-smokers who stopped smoking either before or after the onset of the disease had a significantly lower risk of reaching Expanded Disability Status Scale scores 4 (hazard ratio: 0.65, confidence interval: 0.50-0.83) and 6 (hazard ratio: 0.69, confidence interval: 0.53-0.90) than current smokers, and there was no significant difference between ex-smokers and non-smokers in terms of time to Expanded Disability Status Scale scores 4 or 6. Our data suggest that regular smoking is associated with more severe disease and faster disability progression. In addition, smoking cessation, whether before or after onset of the disease, is associated with a slower progression of disability.

The musculoskeletal effects of cigarette smoking

➤ Cigarette smoking decreases bone mineral density and increases the risk of sustaining a fracture or tendon injury, with partial reversibility of these risks with long-term cessation of smoking. ➤ Cigarette smoking increases the risk for perioperative complications, nonunion and delayed union of fractures, infection, and soft-tissue and wound-healing complications. ➤ Brief preoperative cessation of smoking may mitigate these perioperative risks. ➤ Informed-consent discussions should include notification of the higher risk of perioperative complications with cigarette smoking and the benefits of temporary cessation of smoking.

Salivary immunoglobulin classes in Nigerian cigarette smokers: Indication for increased risk of oral diseases

BACKGROUND

Cigarette smoking is a worldwide social epidemic and it is one of the main causes of preventable death and disability. Gingivitis, periodontitis, pocket depth, attachment loss, alveolar bone loss, and tooth loss are some of oral pathologies commonly found in cigarette smokers. The aim of this study was to explore, for the first time among Nigerians, the interplay between components of cigarette smoke and salivary levels of immunoglobulin classes so as to provide oral immunological based reasons for oral diseases in cigarette smokers.

MATERIALS AND METHODS

In this case-control study, 5 mL of unstimulated saliva was collected in plain sample bottles from 24 active smokers who smoke at least 6 sticks of cigarette per day and 21 sex and age-matched non-smokers who were apparently healthy. The samples were spun and supernatant stored at -20°C until assayed. The immunoglobulin levels of the samples were estimated using enzyme-linked immunosorbent assay (ELISA). Student's t-test (unpaired) was used to determine significant differences between the two groups. P values less than 0.05 was considered significant.

RESULTS

No significant differences were observed in the mean salivary levels of IgG, IgA, and IgE. Only IgM was significantly lower in smokers compared with non-smokers (P = 0.038). The proportion of smokers with detectable level of salivary IgE was lower compared with controls.

CONCLUSION

Our study showed that there is decreased salivary IgM in smokers. This observation suggests that reduced salivary immunoglobulin level of IgM might be involved in the pathogenesis of oral diseases in cigarette smokers.

Cigarette smoke decreases airway epithelial FABP5 expression and promotes Pseudomonas aeruginosa infection

Cigarette smoking is the primary cause of Chronic Obstructive Pulmonary Disease (COPD), which is characterized by chronic inflammation of the airways and destruction of lung parenchyma. Repeated and sustained bacterial infections are clearly linked to disease pathogenesis (e.g., exacerbations) and a huge burden on health care costs. The airway epithelium constitutes the first line of host defense against infection and our previous study indicated that Fatty Acid Binding Protein 5 (FABP5) is down regulated in airway epithelial cells of smokers with COPD as compared to smokers without COPD. We hypothesized that cigarette smoke (CS) exposure down regulates FABP5, thus, contributing to a more sustained inflammation in response to bacterial infection. In this report, we show that FABP5 is increased following bacterial infection but decreased following CS exposure of primary normal human bronchial epithelial (NHBE) cells. The goal of this study was to address FABP5 function by knocking down or overexpressing FABP5 in primary NHBE cells exposed to CS. Our data indicate that FABP5 down regulation results in increased P. aeruginosa bacterial load and inflammatory cytokine levels (e.g., IL-8) and decreased expression of the anti-bacterial peptide, β defensin-2. On the contrary, FABP5 overexpression exerts a protective function in airway epithelial cells against P. aeruginosa infection by limiting the production of IL-8 and increasing the expression of β defensin-2. Our study indicates that FABP5 exerts immunomodulatory functions in the airway epithelium against CS exposure and subsequent bacterial infection through its modulation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ activity. These findings support the development of FABP5/PPAR-γ-targeted therapeutic approach to prevent airway inflammation by restoring antimicrobial immunity during COPD exacerbations.

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

Background

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

Methods

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

Results

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

Conclusions

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

Smoking and human papillomavirus (HPV) infection in the HPV in Men (HIM) study

BACKGROUND

The influence of smoking on the natural history of HPV infection in men is not well understood. Smoking could influence the incidence and persistence of HPV infections by suppressing local immune function, increased cellular proliferation, upregulated proinflammatory factors, or induced host DNA damage resulting in increased susceptibility to infection. The purpose of this analysis is to assess prevalent HPV infections by smoking status in men, and to determine baseline risk of HPV infection associated with smoking.

METHODS

The HPV in Men (HIM) study is a multinational prospective study of the natural history of HPV infections in men. Samples from the coronal sulcus, glans penis, shaft, and scrotum were combined for HPV DNA testing. Multivariable logistic regression was used to assess the association between smoking and any-, oncogenic-, and nononcogenic HPV infections.

RESULTS

Our analyses revealed that current smoking was associated with an increased risk of any HPV infection (OR = 1.19; 95% CI: 1.01-1.41) and oncogenic HPV infection (OR = 1.24; 95% CI: 1.05-1.47). However, the association between smoking and any HPV infection (OR = 1.35; 95% CI: 1.05-1.73) and oncogenic HPV infection (OR = 1.46; 95% CI: 1.11-1.92) was only evident among men reporting fewer lifetime sexual partners.

DISCUSSION

These results suggest that current smokers with the fewest number of sexual partners are associated with an increased risk for oncogenic HPV infection.

IMPACT

The relationship between smoking and HPV infection remains understudied in men; these data shed new light on the interplay between smoking, sexual activity, and risk of HPV infection.

The role of IL-1β in nicotine-induced immunosuppression and neuroimmune communication

Although a number of inflammatory cytokines are increased during sepsis, the clinical trials aimed at down-regulating these mediators have not improved the outcome. These paradoxical results are attributed to loss of the "tolerance" phase that normally follows the proinflammatory response. Chronic nicotine (NT) suppresses both adaptive and innate immune responses, and the effects are partly mediated by the nicotinic acetylcholine receptors in the brain; however, the mechanism of neuroimmune communication is not clear. Here, we present evidence that, in rats and mice, NT initially increases IL-1β in the brain, but the expression is downregulated within 1-2 week of chronic exposure, and the animals become resistant to proinflammatory/pyrogenic stimuli. To examine the relationship between NT, IL-1β, and immunosuppression, we hypothesized that NT induces IL-1β in the brain, and its constant presence produces immunological "tolerance". Indeed, unlike wild-type C57BL/6 mice, chronic NT failed to induce immunosuppression or downregulation of IL-1β expression in IL-1β-receptor knockout mice. Moreover, while acute intracerebroventricular administration of IL-1β in Lewis (LEW) rats activated Fyn and protein tyrosine kinase activities in the spleen, chronic administration of low levels of IL-1β progressively diminished the pyrogenic and T cell proliferative responses of treated animals. Thus, IL-1β may play a critical role in the perception of inflammation by the CNS and the induction of an immunologic "tolerant" state. Moreover, the immunosuppressive effects of NT might be at least partly mediated through its effects on the brain IL-1β. This represents a novel mechanism for neuroimmune communication.

Acute schizophrenia is accompanied by reduced T cell and increased B cell immunity

Previous studies of lymphocyte distribution in schizophrenia have yielded inconsistent results, as summarized in the present study. Based on our own original data, potential confounds that might explain these variations are analyzed and discussed. Blood samples from 26 patients with acute paranoid schizophrenia were investigated in comparison with 32 matched healthy controls by flow cytometry (CD3, CD4, CD8, CD19, and CD56 phenotyping). A subgroup of drug-free patients was followed up after 6 weeks of treatment. Cotinine levels and the free cortisol index (FCI) were provided in order to control for medication, smoking, and stress. Cotinine levels correlated with natural killer (NK) cell counts (CD3⁻/CD56(+): r = -0.383, P = 0.003) while the FCI was related to B cell numbers (CD19(+): r = 0.390, P = 0.003). Considering these covariates, a lower level of T helper cells (P = 0.010), a reduced CD4/CD8 ratio (P = 0.029), and elevated B cells (P = 0.008) were found during acute psychosis. After 6 weeks of medication, an inverse pattern was observed in initially drug-free patients: total T cell (P = 0.005), T helper (P = 0.003), and T suppressor/cytotoxic cells (P = 0.005) increased, while B cell counts declined (P = 0.049). In conclusion, acute paranoid schizophrenia may be accompanied by a reduced T cell defense and a shift towards B cell immunity, which normalizes in response to treatment. In addition to disease stage or subtype and medication, cigarette smoking and stress are important co-factors.

Differential effects on T-cell function following exposure to serum from schizophrenia smokers

Cigarette smoking is more prevalent in subjects with schizophrenia compared to those with other psychiatric disorders or the general population and could therefore affect molecular pathways that impact the pathophysiology of this disorder. As smoking is also known to suppress immune responses, we investigated the effects of 'smoking-conditioned' serum obtained from schizophrenia and control subjects on healthy T cell in vitro. We found that T-cell proliferation was significantly increased following exposure to serum from smoking schizophrenia patients whereas no effect was observed when using serum from smoking control subjects or non-smoking patients and controls. We eliminated the possibility that these effects were due to quantitative differences in cigarette consumption as serum levels of the stable nicotine metabolite cotinine were similar in schizophrenic and control smokers. Molecular characterization showed that serum from patient smokers increased expression of T-cell activation markers CD69(high), CD25(high), co-stimulatory molecules CD26+, CD27+ and CD28+, and decreased T-cell receptor complex components TCRalpha/beta and CD3. Moreover, analysis of supernatants collected after T-cell exposure to serum from smoking patients showed a time-dependent decline in interleukin (IL)-2 levels, suggesting that the proliferation effect is promoted by enhanced IL-2 processing. These results suggest that cigarette smoking has selective effects on serum components that, in turn, lead to altered immune function in schizophrenia patients relative to healthy subjects. Further studies aimed at characterizing these components could result in a better understanding of the onset and aetiology of schizophrenia and potentially lead to novel therapeutic strategies.

Natural killer cells in obesity: impaired function and increased susceptibility to the effects of cigarette smoke

BACKGROUND

Obese individuals who smoke have a 14 year reduction in life expectancy. Both obesity and smoking are independently associated with increased risk of malignancy. Natural killer cells (NK) are critical mediators of anti-tumour immunity and are compromised in obese patients and smokers. We examined whether NK cell function was differentially affected by cigarette smoke in obese and lean subjects.

METHODOLOGY AND PRINCIPAL FINDINGS

Clinical data and blood were collected from 40 severely obese subjects (BMI>40 kg/m(2)) and 20 lean healthy subjects. NK cell levels and function were assessed using flow cytometry and cytotoxicity assays. The effect of cigarette smoke on NK cell ability to kill K562 tumour cells was assessed in the presence or absence of the adipokines leptin and adiponectin. NK cell levels were significantly decreased in obese subjects compared to lean controls (7.6 vs 16.6%, p = 0.0008). NK function was also significantly compromised in obese patients (30% +/- 13% vs 42% +/-12%, p = 0.04). Cigarette smoke inhibited NK cell ability to kill tumour cell lines (p<0.0001). NK cells from obese subjects were even more susceptible to the inhibitory effects of smoke compared to lean subjects (33% vs 28%, p = 0.01). Cigarette smoke prevented NK cell activation, as well as perforin and interferon-gamma secretion upon tumour challenge. Adiponectin but not leptin partially reversed the effects of smoke on NK cell function in both obese (p = 0.002) and lean controls (p = 0.01).

CONCLUSIONS/SIGNIFICANCE

Obese subjects have impaired NK cell activity that is more susceptible to the detrimental effects of cigarette smoke compared to lean subjects. This may play a role in the increase of cancer and infection seen in this population. Adiponectin is capable of restoring NK cell activity and may have therapeutic potential for immunity in obese subjects and smokers.

Smoking and circulating IgE in bronchial carcinoma

The serum concentrations of total IgE were significantly raised in smokers compared to those who had never smoked (p less than 0.005) among male patients with bronchial carcinoma, while no differences were found between smoking and non-smoking female bronchial carcinoma patients. The total IgE levels in male and female patients with non-malignant pulmonary diseases were not correlated to smoking habits. No significant differences in the IgE levels were observed between smoking males subgrouped according to the WHO histological types of bronchial carcinoma. Males with carcinoma who had stopped smoking more than 10 years ago had significantly reduced IgE levels compared to male cancer patients continuously smoking (p less than 0.01). These data, indicating that smoking is associated with elevated IgE levels in males with bronchial carcinoma, might suggest that smoking in certain, preferably male, individuals induces an impaired cellular immunity which is reflected by an enhanced IgE synthesis and a depressed resistance to carcinogens of tobacco smoke.

Pneumocystis murina infection and cigarette smoke exposure interact to cause increased organism burden, development of airspace enlargement, and pulmonary inflammation in mice

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of airflow obstruction and lung destruction with airspace enlargement. In addition to cigarette smoking, respiratory pathogens play a role in pathogenesis, but specific organisms are not always identified. Recent reports demonstrate associations between the detection of Pneumocystis jirovecii DNA in lung specimens or respiratory secretions and the presence of emphysema in COPD patients. Additionally, human immunodeficiency virus-infected individuals who smoke cigarettes develop early emphysema, but a role for P. jirovecii in pathogenesis remains speculative. We developed a new experimental model using immunocompetent mice to test the interaction of cigarette smoke exposure and environmentally acquired Pneumocystis murina infection in vivo. We hypothesized that cigarette smoke and P. murina would interact to cause increases in total lung capacity, airspace enlargement, and pulmonary inflammation. We found that exposure to cigarette smoke significantly increases the lung organism burden of P. murina. Pulmonary infection with P. murina, combined with cigarette smoke exposure, results in changes in pulmonary function and airspace enlargement characteristic of pulmonary emphysema. P. murina and cigarette smoke exposure interact to cause increased lung inflammatory cell accumulation. These findings establish a novel animal model system to explore the role of Pneumocystis species in the pathogenesis of COPD.

Cigarette smoke exposure impairs dendritic cell maturation and T cell proliferation in thoracic lymph nodes of mice

Respiratory tract dendritic cells (DCs) are juxtaposed to directly sample inhaled environmental particles. Processing and presentation of these airborne Ags could result in either the development of immunity or tolerance. The purpose of this study was to determine the consequences of cigarette smoke exposure on DC function in mice. We demonstrate that while cigarette smoke exposure decreased the number of DCs in the lungs, Ag-induced DC migration to the regional thoracic lymph nodes was unaffected. However, cigarette smoking suppressed DC maturation within the lymph nodes as demonstrated by reduced cell surface expression of MHC class II and the costimulatory molecules CD80 and CD86. Consequently, DCs from cigarette smoke-exposed animals had a diminished capacity to induce IL-2 production by T cells that was associated with diminished Ag-specific T cell proliferation in vivo. Smoke-induced defects in DC function leading to impaired CD4(+) T cell function could inhibit tumor surveillance and predispose patients with chronic obstructive pulmonary disease to infections and exacerbations.

Impact of smoking status on the biological behavior of lung cancer

Cigarette smoking is the most established risk factor for lung carcinogenesis; however, its effects on the progression of lung cancer are still unclear. We reviewed the clinical investigations on this issue, which imply that smoking status is a treatment predictor and prognostic factor for several subtypes of lung cancer. Moreover, gene alterations and various protein expressions of tumor progression were recognized more frequently in the tumor tissues of smokers than in those of the never smokers. A cellular analysis revealed that tobacco-specific chemical compounds cause genetic or epigenetic alterations, modulate expressions of large numbers of genes that include molecules related to proliferation, invasion and metastasis, and deteriorate anti-tumor immunity. Our findings suggest that smoking promotes the progression of lung cancer, and that elucidating the molecular mechanisms may help to clarify the therapeutic targets.

Immunosuppressive and anti-inflammatory effects of nicotine administered by patch in an animal model

To study the immunological effects of nicotine, there are several rodent models for chronic nicotine administration. These models include subcutaneously implanted miniosmotic pumps, nicotine-spiked drinking water, and self-administration via jugular cannulae. Administration of nicotine via these routes affects the immune system. Smokers frequently use nicotine patches to quit smoking, and the immunological effects of nicotine patches are largely unknown. To determine whether the nicotine patch affects the immune system, nicotine patches were affixed daily onto the backs of Lewis rats for 3 to 4 weeks. The patches efficiently raised the levels of nicotine and cotinine in serum and strongly inhibited the antibody-forming cell response of spleen cells to sheep red blood cells. The nicotine patch also suppressed the concanavalin A-induced T-cell proliferation and mobilization of intracellular Ca(2+) by spleen cells, as well as the fever response of animals to subcutaneous administration of turpentine. Moreover, immunosuppression was associated with chronic activation of protein tyrosine kinase and phospholipase C-gamma1 activities. Thus, in this animal model of nicotine administration, the nicotine patch efficiently raises the levels of nicotine and cotinine in serum and impairs both the immune and inflammatory responses.

Prenatal cigarette smoke decreases lung cAMP and increases airway hyperresponsiveness

Epidemiologic studies suggest that in utero exposure to tobacco smoke, primarily through maternal smoking, increases the risk for asthma in children; however, the mechanism of this phenomenon is not clear. Cyclic adenosine monophosphate relaxes airway smooth muscles in the lung and acts as an antiasthmatic. In this study, we examined the effects of in utero cigarette smoke exposure of Balb/c mice on airway responsiveness, as determined by Penh measurements. Animals exposed prenatally but not postnatally to cigarette smoke exhibited increased airway hyperresponsiveness after a single intratracheal injection of Aspergillus fumigatus extract. The increased airway hyperresponsiveness was not associated with increased leukocyte migration or mucous production in the lung but was causally related to decreased lung cyclic adenosine monophosphate levels, increased phosphodiesterase-4 enzymatic activity, and phosphodiesterase-4D (PDE4D) isoform-specific messenger ribonucleic acid expression in the lung. Exposure of adult mice to cigarette smoke did not significantly alter airway responsiveness, cyclic adenosine monophosphate levels, or the phosphodiesterase activity. These results suggest that prenatal exposure to cigarette smoke affects lung airway reactivity by modulating the lung cyclic adenosine monophosphate levels through changes in phosphodiesterase-4D activity, and these effects are independent of significant mucous production or leukocyte recruitment into the lung.

Evidence for the immunosuppressive role of nicotine on human dendritic cell functions

Nicotine alters a wide range of immunological functions, including innate and adaptive immune responses. To date, no studies have been reported showing the immunoregulatory effects of nicotine on dendritic cells (DCs), which are critical cells for initiation of cell-mediated immunity against infection and neoplastic diseases. In this work, we report that, in a nicotinic environment, monocyte-derived DCs manifest lower endocytic and phagocytic activities. Interestingly, although immature DCs undergo maturation in response to bacterial antigen lipopolysaccharide, they produce decreased levels of pro-inflammatory cytokines, notably interleukin-12, and reveal a reduced ability to stimulate antigen-presenting cell-dependent T-cell responses. Importantly, the reduction in T-cell responses is associated with a diminished ability of DCs to induce differentiation and expansion of type 1 T cells, as evidenced by a decreased frequency of interferon-gamma-producing effector cells. These results strongly suggest that nicotine can exert its immunosuppressive effects on immune surveillance through functional impairment of the DC system.

Acute and chronic nicotine exposures modulate the immune system through different pathways

We have previously shown that T cells from rats exposed chronically to cigarette smoke or nicotine (NT) exhibit T cell anergy and decreased proliferation to T cell mitogens. Effects of chronic NT on T cell function persist for at least 2 weeks after the termination of NT treatment. Moreover, these effects of NT are causally related to the decreased Ca(2+) response to T cell receptor (TCR) ligation and constitutive activation of protein tyrosine kinase (PTK) and phospholipase C (PLC)-gamma1 activities. Acute NT treatment also suppresses the Con A-induced T cell proliferation; however, it is not known whether the mechanism(s) by which acute and chronic NT treatments inhibit T cell proliferation are identical. To evaluate this question, LEW rats were acutely treated with NT (1 mg/kg body wt) for 1, 2, or 24 h by an ip injection or implanted with constant-release miniosmotic pumps containing saline or NT (1 mg/kg body wt/day) for a 3-week chronic exposure. Inhibition of Con A-induced proliferation of peripheral blood cells (PBC) by both acute and chronic treatments was reversed by the inhibitor of nicotinic acetylcholine receptors, mecamylamine (MEC), indicating that these receptors are required for T cell proliferation. However, the effect of acute NT on the Con A response was short lived (i.e., observed at 1 and 2 h but not at 24 h after NT administration) and was seen in PBC but not in spleen cells. Unlike the chronic treatment, acute NT administration neither suppressed significantly the TCR-mediated [Ca(2+)](i) response nor did it cause the constitutive activation of PTK and PLC-gamma1 activities in blood lymphocytes. Acute, but not chronic, NT administration increased the plasma corticosterone concentration, and this increase was also inhibited by MEC. Moreover, adrenalectomy abrogated the acute but not chronic NT effects on the Con A response. Thus, the acute and chronic effects of NT on T lymphocytes are mechanistically distinct phenomena. Whereas chronic administration of NT causes T cell anergy, acute effects are primarily mediated via the activation of the hypothalamus-pituitary-adrenal axis.

Meta-analysis on the association between environmental tobacco smoke (ETS) exposure and the prevalence of lower respiratory tract infection in early childhood

The aim of this study was to obtain quantitative information from published data on the association between environmental tobacco smoke (ETS) exposure and the prevalence of serious lower respiratory tract infections (LRTI) in infancy and early childhood. We identified 21 relevant publications on the relation between ETS and the prevalence of serious LRTI by reviewing reference lists in relevant reports and by conducting manual and computer searches (Medline database; Dissertation abstracts index of Xerox University Microfilms) of published reports between 1966 and 1995. Thirteen studies were included in a quantitative overview using random effects modeling to derive pooled odds ratios. Sensitivity analyses were conducted to test the decision rules used in extracting odds ratio data. The results of community and hospital studies are broadly consistent and show that the child of a parent who smokes is at approximately twice the risk of having a serious respiratory tract infection in early life that requires hospitalization. This association was pronounced in children younger than age two and diminished after the age of two. The combined odds ratio for hospitalization for lower respiratory tract infections in infancy or early childhood is 1.93 (95% CI 1.66-2.25); the combined odds ratio of prevalence of serious LRTI at age less than 2 years, between 0 and 6 years, and between 3 and 6 years were 1.71 (95% CI 1.33-2.20); 1.57 (1.28-1.91), and 1.25 (0.88-1.78), respectively. There was no evidence of heterogeneity across the studies in these combined odds ratios. We conclude that this meta-analysis provides strong evidence that exposure to ETS causes adverse respiratory health outcomes such as either a serious LRTI or hospitalization for LRTI. New public health campaigns are urgently needed to discourage smoking in the presence of young children.

Skin cancer in Australian heart transplant recipients

BACKGROUND

Cutaneous malignancy is a major cause of morbidity in organ transplant recipients.

OBJECTIVE

Our purpose was to report on skin cancer in Australian heart transplant recipients with analysis of HLA factors.

METHODS

We reviewed histologically proven skin cancers in the first 455 patients undergoing organ transplantation in Sydney, Australia.

RESULTS

The cumulative incidence of skin cancer was 31% at 5 years and 43% at 10 years with a squamous cell carcinoma/basal cell carcinoma ratio of 3:1. Caucasian origin, increasing age at transplantation, and duration of follow-up were significantly associated with skin cancer. Skin cancer accounted for 27% of 41 deaths occurring after the fourth year. Recipient HLA-DR homozygosity was associated with skin cancer overall, whereas HLA-DR7 was a protective factor in skin cancer overall, squamous cell carcinoma, and Bowen's disease. HLA-A1 and HLA-A11 were significant protective factors in Bowen's disease.

CONCLUSION

Skin cancer is a major cause of morbidity and long-term mortality in heart transplant patients.

Nicotine inhibits the production of inflammatory mediators in U937 cells through modulation of nuclear factor-kappaB activation

Cigarette smoke is a major risk factor for lung cancer and respiratory infections. This increased susceptibility may result from cigarette smoke-induced impairment of the immune system. In this study, we evaluated the effect of nicotine on the production of inflammatory mediators by activated macrophages. Pretreatment with nicotine caused a significant inhibition of LPS-induced IL-1, IL-8, and PGE2 expression at the transcriptional level in U937 cells. Nicotine inhibited the activation of a transcription factor, NF-kappaB, which in turn, binds to and mediates transcriptional activation of these genes. These inhibitory effects of nicotine may contribute to cigarette smoke-induced immunosuppression.

Immunomodulatory effects of cigarette smoke

Cigarette smoke is a major health risk factor which significantly increases the incidence of diseases including lung cancer and respiratory infections. This increased susceptibility may result from cigarette smoke-induced impairment of the immune system. While the acute effects of cigarette smoke on the immune system are less clear, chronic exposure to cigarette smoke or nicotine causes T cell unresponsiveness. This apparent T cell anergy may account for or contribute to the immunosuppressive and anti-inflammatory properties of cigarette smoke/nicotine. Nicotine-induced immunosuppression may result from its direct effects on lymphocytes, indirectly through its effects on the neuroendocrine system, or both.

Effect of nicotine on the immune system: possible regulation of immune responses by central and peripheral mechanisms

Nicotine (NT) treatment impairs T-cell receptor (TCR)-mediated signaling, leading to the arrest of T cells in the G1 phase of the cell cycle and inhibition of the antibody plaque-forming cell (AFC) response to sheep red blood cells (SRBC). This paper summarizes some of the previous findings related to cigarette smoke/NT and the immune response, and presents preliminary evidence suggesting that mice chronically treated with NT (0.5 mg/day/kg body weight) have a depressed inflammatory response in the turpentine-induced abscess model of inflammation. This ability of nicotine to attenuate an inflammatory response may also be the cause of reduced mortality of chronically nicotine-treated mice from acute influenza A pneumonitis. Moreover, in LEW rats, decreased anti-SRBC AFC responses were also observed after intracerebroventricular (i.c.v.) administration of relatively small concentrations of NT (28 micrograms/day/kg body weight) which, when given peripherally, did not affect the AFC response. In vitro the addition of NT to T cells increased protein tyrosine kinase (PTK) activity and intracellular Ca2+ concentration [Ca2+]i. These results support the hypothesis that NT alters immune responses by directly interacting with T cells, as well as indirectly through brain-immune interactions.