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

Association between short-term air pollution exposure and perturbation in thyrotropin levels in 1.38 million Chinese women: A national longitudinal analysis, 2014-2019

Prevalence of subclinical hypothyroidism substantially increased during the last decade in China, which has been commonly/clinically diagnosed as elevation in thyrotropin (thyroid-stimulating hormone [TSH]). Tobacco smoke containing toxic substances has been linked to thyroid dysfunction; however, data on perturbation of TSH following air pollution exposure in human has not been assessed at nationwide population level. We investigated the longitudinal impact of daily ambient air pollution estimated at residential level on serum TSH in 1.38 million women from China's 29 mainland provinces between 2014 and 2019. We observed that particulate matter with aerodynamic diameter ≤ 10 and ≤ 2.5 µm (PM10, PM2.5) and nitrogen dioxide (NO2) at cumulative lag 0-7 days of exposure were associated with percent elevations in TSH (0.88% [95% CI: 0.71, 1.05] per [interquartile range, IQR: 54.8 μg/m3] of PM10; 0.89% [95% CI, 0.71, 1.07] per IQR [40.3 μg/m3] of PM2.5; 2.01% [95% CI: 1.81, 2.22] per IQR [27.4 μg/m3] of NO2). Greater associations were observed in participants living in areas with ≥adequate iodine intake and those with low BMI levels and high inflammation status. Our results suggest that increased concentrations of recent ambient air pollutants at exposure ranges commonly encountered in Asia were associated with increases in TSH, supporting disturbing role of short-term air pollution exposure on the regulation of thyroid hormone homeostasis.

Effect of Nicotine on Immune System Function

As a parasympathetic alkaloid and the main substance in cigarette smoke, nicotine modulates the immune system, inhibits innate and acquired immunity and is used in treating many autoimmune diseases. It often stimulates the α7 receptor and causes an anti-inflammatory state in the body. This study is designed to evaluate the role of nicotine treatment on immune system. The results showed that nicotine affects many cells in immune system, alters the downstream intracellular mechanisms and changes lymphocytes polarization. This substance alters TLRs and STATs gene expression and thus changes in the innate immune system. All these events inhibit the secretion of pro-inflammatory cytokines and chemokines which increase angiogenesis and metastasis and exacerbates tumors due to increasing survival and cell growth. Nicotine can aggravate tumors in cancer patients, with many positive effects observed in the treating autoimmune disease, Nicotine treatment function in different conditions depends on factors such as concentration, how it is employed, treatment duration and other conditions such as body conditions affecting the immune system, hence, further studies and review of all conditions are required.

Exosomal miR-4466 from nicotine-activated neutrophils promotes tumor cell stemness and metabolism in lung cancer metastasis

Smoking is associated with lung cancer and has a profound impact on tumor immunity. Nicotine, the addictive and non-carcinogenic smoke component, influences various brain cells and the immune system. However, how long-term use of nicotine affects brain metastases is poorly understood. We, therefore, examined the mechanism by which nicotine promotes lung cancer brain metastasis. In this study, we conducted a retrospective analysis of 810 lung cancer patients with smoking history and assessed brain metastasis. We found that current smoker's lung cancer patients have significantly higher brain metastatic incidence compared to the never smokers. We also found that chronic nicotine exposure recruited STAT3-activated N2-neutrophils within the brain pre-metastatic niche and secreted exosomal miR-4466 which promoted stemness and metabolic switching via SKI/SOX2/CPT1A axis in the tumor cells in the brain thereby enabling metastasis. Importantly, exosomal miR-4466 levels were found to be elevated in serum/urine of cancer-free subjects with a smoking history and promote tumor growth in vivo, suggesting that exosomal miR-4466 may serve as a promising prognostic biomarker for predicting increased risk of metastatic disease among smoker(s). Our findings suggest a novel pro-metastatic role of nicotine-induced N2-neutrophils in the progression of brain metastasis. We also demonstrated that inhibiting nicotine-induced STAT3-mediated neutrophil polarization effectively abrogated brain metastasis in vivo. Our results revealed a novel mechanistic insight on how chronic nicotine exposure contributes to worse clinical outcome of metastatic lung cancer and implicated the risk of using nicotine gateway for smoking cessation in cancer patients.

Toxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor inhalation on rheumatoid arthritis

Tobacco combustion exposure worsens rheumatoid arthritis (RA). Non-combustible tobacco devices, as heat-not-burn tobacco (HNBT), are emerging as harm reduction to smokers by releasing nicotine and lower combustible tobacco products. Nevertheless, HNBT toxicity remains unclear. Hence, here we investigated the impacts of the tobacco combustible product (cigarette smoke; CS) or HNBT vapor exposures on antigen-induced arthritis (AIA) in C57BL/6 mice. Animals were exposed to airflow, HNBT vapor, or CS during 1 h/twice a day, under the Health Canada Intense (HCI) smoking regime, between days 14 to 20 after the first immunization. At day 21, 16 h after the last exposures, mice were i.a. challenged and the AIA effects were evaluated 24 h later. CS- or HNBT-exposed mice presented equivalent blood nicotine levels. CS exposure worsened articular symptoms, pulmonary inflammation, and expression of lung metallothioneins. Nevertheless, CS or HNBT exposures reduced lymphoid organs' cellularity, splenocyte proliferation and IL-2 secretion. Additional in vitro CS or HNBT exposures confirmed the harmful effects on splenocytes, which were partially mediated by the activation of nicotine/α7nAchR pathway. Associated, data demonstrate the toxic mechanisms of CS or HNBT inhalation at HCI regime on RA, and highlight that further investigations are fundamental to assure the toxicity of emerging tobacco products on the immune system during specific challenges.

[COVID-19 and Smoking - A Position Paper by the DGP Taskforce for Smoking Cessation]

Tobacco smoking is associated with severe health risks. In 2020, the WHO estimated that 8 million people have died due to smoking. Furthermore, smoking tobacco is a well-known risk factor for various infectious pulmonary diseases. The question raised, whether smoking is facilitating SARS-CoV-2-infections and increases adverse outcomes of COVID-19. To answer these questions a narrative review was conducted, finally including 7 systematic reviews with meta-analyses published in January and February 2021. Tobacco smoking was associated with an increased COVID-19 disease severity (odds ratio range of active vs. never smokers 1.55-2.19 and former vs. never smokers 1.20-2.48) and an increased COVID-19 in-hospital mortality (odds ratio range of active vs. never smokers 1.35-1.51 and former vs. never smokers 1.26-2.58). Beside immediate pulmonary toxic effects through active smoking, the cumulative livelong tobacco exposition and subsequent tobacco-associated diseases seem to predominantly predict adverse outcomes in patients with COVID-19. Data regarding an increased risk of infection among smokers is conflicting. However, a large observational study from England with 2.4 million persons reported an association between tobacco smoking and typical symptoms of COVID-19. For e-cigarettes and vaping less data exist, but experimental and first clinical investigations also suggest an increased risk for adverse outcomes for their use and SARS-CoV-2 infections. Especially during the current SARS-CoV-2 pandemic with limited therapeutic options it is particularly important to advise smokers of their increased risks for unfavourable COVID-19 outcomes. Evidence based support for smoking cessation should be offered. In Germany, the existing and well-established methods to support tobacco cessation need to be reimbursed by statutory health insurances.

Cigarette Smoke Exposure Inhibits Early Phase of Antibody Production through Inhibition of Immune Functions in Alveolar Macrophage

Background::

Cigarette smoke (CS) is inhaled into the lung. Alveolar macrophage (AM) is known to play an important role in the lung immune system. However, the relationship between AM functions and antibody production by CS is not fully investigated.

Objective::

Therefore, we investigated the effects of AM from CS exposed mice on antibody production. Mice were exposed to 20 cigarettes/day for 10 days. AM were obtained by broncho-alveolar lavage. Antibody production was analyzed by plaque-forming cell assay using seep red blood cell (SRBC) as antigen.

Methods::

B cell proliferation was analyzed by 3H-thymidine incorporation. Phagocytic activity using fluorescein isothiocyanate-labeled SRBC and expressions of surface antigens on AM were analyzed by flow cytometry. Cytokines and NF-κB mRNA expressions of AM were analyzed by RTPCR.

Results and Discussion:

Antibody production was decreased at the induction phase, but not at the expression phase by AM from smoked mice (SM) compared with non-smoked mice (NSM). B cell proliferation was decreased by cigarette extracts dose-dependently. Phagocytic activity of AM was decreased in SM compared with NSM. Expression of surface antigens on AM was decreased in SM compared with NSM. Cytokines or NF-κB mRNA expressions of AM were decreased in SM compared with NSM.

Conclusion::

These results suggest that the inhibition of antibody production by cigarette smoking is caused by the inhibition of phagocytosis and expressions of surface antigens associated with antigen presentation. Such inhibition of AM functions may increase the risk of bacterial and virus infections.

Divergent Effect of Cigarette Smoke on Innate Immunity in Inflammatory Bowel Disease: A Nicotine-Infection Interaction

Cigarette smoke (CS) has adverse effects in patients with Crohn’s disease (CD), an inflammatory bowel disease (IBD) that has been associated with microbial infection, immuno-dysregulation, and mucosal dysfunction. However, CS seems to provide relief and protection to patients with another IBD known as ulcerative colitis (UC). These two subsets are featured as M1- and M2-mediated responses, respectively. Nicotine is the most active, addictive, and studied ingredient in CS. The mechanism of how nicotine and/or other CS ingredients induce pro-inflammatory or anti-inflammatory phenotypes in IBD patients remains under investigation. Our most recent in vitro nicotine study provided significant insights toward understanding the contradictory effects of nicotine on IBD patients, and it elucidated the mechanistic role of α7nAChR in modulation of macrophages in tobacco smokers. Shifting the beneficial effect of nicotine to a harmful outcome in CD patients was linked to a nicotine-microbe interaction that supports a microbial etiology in CD pathogenesis. Among the most debated pathogens in CD etiology is Mycobacterium avium subspecies paratuberculosis (MAP). Other studies associated nicotine with upregulation of miR-124 expression in macrophages, which led to anti-inflammatory response. This review discusses published work on the role of nicotine in modulation of the innate immune response and subsequent signaling in macrophages in IBD subsets.

Coronavirus Disease 2019 and Smoking: How and Why We Implemented a Tobacco Treatment Campaign

Smoking is associated with one of five deaths in the United States. Multimodality tobacco treatment increases rates of successful cessation by at least 20%. The coronavirus disease 2019 pandemic has put a halt to many inpatient and outpatient medical visits that have been deemed nonessential, including tobacco treatment. The transition to telehealth has been wrought with challenges. Although data on the association between coronavirus disease 2019 and tobacco products are mixed, the overall health consequences of tobacco point towards increased risk of morbidity and death that is associated with the virus. This leaves smoking as one of the few readily modifiable risk factors in an environment understandably not set up to prioritize cessation. A military health facility on Fort Eustis in Virginia runs a successful tobacco treatment program and adapted it to pandemic times. This article describes the process and lessons learned from this initiative. The model is applicable and scalable to government and civilian health centers as health care adapts to a new normal.

Suppressive effect of environmental tobacco smoke on murine Th2 cell-mediated nasal eosinophilic inflammation

Background

Environmental tobacco smoke (ETS) exposure is recognized as a risk factor for the development of various respiratory diseases.

Objective

In this study, the effect of ETS on allergen-immunized and allergen-specific Th2 cell-transferred murine eosinophilic inflammation models and that of cigarette smoke extract (CSE) and nicotine on allergen-induced Th2 cell proliferation and interleukin (IL)-4 production were investigated.

Methods

Ovalbumin (OVA)-immunized and OVA-specific Th2 cell-transferred BALB/c mice were exposed to ETS and were challenged with OVA. Then, the number of inflammatory cells in the nasal mucosa and nasal hyperresponsiveness (NHR) were assessed. The effects of CSE and nicotine on the allergen-induced proliferative response of and IL-4 production by Th2 cells were determined in vitro.

Results

In OVA-immunized and Th2 cell-transferred mice, allergen-induced NHR and nasal eosinophil infiltration were significantly suppressed by ETS exposure, whereas the accumulation of neutrophils was rather enhanced. Allergen-specific Th2 cell proliferation and IL-4 production were inhibited by coculture with CSE. The same effects were induced by nicotine, though the effect on proliferation was relatively weak.

Conclusion

Regardless of its harmful effect, ETS suppresses NHR, probably through the inhibition of Th2 cell responses.

Chronic Tobacco Exposure by Smoking Develops Insulin Resistance

BACKGROUND AND OBJECTIVES

The present review critically discusses the high occurrence rate, insulin resistance and type-2 diabetes in tobacco exposed individuals. Tobacco extracts and smoke contain a large number of toxic materials and a significant number of those are metabolic disintegrators.

DISCUSSION

Glucose and lipid homeostasis is severely impaired by this compound. Tobacco exposure contributes to adverse effects by impairing the physical, biochemical and molecular mechanisms in the tissues. The immunological components are damaged by tobacco with high production of proinflammatory cytokines (IL-6, TNF-∞) and augmentation of inflammatory responses. These events result in damages to cytoskeletal structures of different tissues. Degradation of matrix structure (by activation of different types of MMPs) results in the permanent damages to the tissues and their metabolic functions. Cellular antioxidant defense system mostly cannot or hardly nullify CS-induced ROS production that activates polymorphonuclear neutrophils (PMNs), which are a major source of cytokines and chemokines (TNFα, IL6, IL8, INFγ). Additive effects of these immediately promote the low energy-metabolism as well as inflammation. Oxidative stress, mitochondrial dysfunction, and inflammation contribute to the direct nicotine toxicity via nAChRs in diabetes. The investigator identified that skeletal muscle insulin-resistance occurs in smokers due to phosphorylation of insulin receptor substrate1 (IRS1) at Ser-636 position.

CONCLUSION

Tobacco exposure initiates free radical related immunological impairment, DNA damage, and inflammation. So, the present analysis is of importance to figure out the mechanistic layout of tobacco-induced tissue damage and its possible therapeutic interventions.

Acetylcholinesterase Inhibitor Pyridostigmine Bromide Attenuates Gut Pathology and Bacterial Dysbiosis in a Murine Model of Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) is a Th2 inflammatory bowel disease characterized by increased IL-5 and IL-13 expression, eosinophilic/neutrophilic infiltration, decreased mucus production, impaired epithelial barrier, and bacterial dysbiosis of the colon. Acetylcholine and nicotine stimulate mucus production and suppress Th2 inflammation through nicotinic receptors in lungs but UC is rarely observed in smokers and the mechanism of the protection is unclear.

METHODS

In order to evaluate whether acetylcholine can ameliorate UC-associated pathologies, we employed a mouse model of dextran sodium sulfate (DSS)-induced UC-like conditions, and a group of mice were treated with Pyridostigmine bromide (PB) to increase acetylcholine availability. The effects on colonic tissue morphology, Th2 inflammatory factors, MUC2 mucin, and gut microbiota were analyzed.

RESULTS

DSS challenge damaged the murine colonic architecture, reduced the MUC2 mucin and the tight-junction protein ZO-1. The PB treatment significantly attenuated these DSS-induced responses along with the eosinophilic infiltration and the pro-Th2 inflammatory factors. Moreover, PB inhibited the DSS-induced loss of commensal Clostridia and Flavobacteria, and the gain of pathogenic Erysipelotrichia and Fusobacteria.

CONCLUSIONS

Together, these data suggest that in colons of a murine model, PB promotes MUC2 synthesis, suppresses Th2 inflammation and attenuates bacterial dysbiosis therefore, PB has a therapeutic potential in UC.

Cytokine profiling of exosomes derived from the plasma of HIV-infected alcohol drinkers and cigarette smokers

Cytokines and chemokines circulate in plasma and may be transferred to distant sites, via exosomes. HIV infection is associated with dysregulation of cytokines and chemokines, which subsequently contribute to the pathogenesis of HIV. Alcohol and tobacco exposure, which are prevalent in HIV-infected individuals, may induce changes in the expression of cytokines and chemokines. Therefore, our aim in this study was to quantify plasma exosomal cytokines and chemokines that we expect to exacerbate toxicity or disease progression in HIV-positive drug abusers. We measured the levels of cytokines and chemokines in the plasma and plasma exosomes of 39 patients comprising six groups: HIV-negative and HIV-positive non drug abusers, HIV-negative and HIV-positive alcohol users, and HIV-negative and HIV positive tobacco smokers. We measured six cytokines (TNF-α, IL-1β, IL-8, IL-6, IL-1ra, IL-10) and two chemokines (MCP-1 and RANTES). All were present in exosomes of healthy subjects, but their levels varied between different study groups. HIV-positive alcohol drinkers had higher levels of plasma IL-8 compared to those of HIV-positive non-drinkers. The IL-1ra level was significantly higher in exosomes of non-HIV-infected alcohol drinkers compared to those of HIV-positive alcohol drinkers. Interestingly, the IL-10 level was higher in exosomes compared with their respective plasma levels in all study groups except HIV-positive non-alcohol drinkers. IL-10 was completely packaged in exosomes of HIV-positive smokers. HIV-positive smokers had significantly higher levels of plasma IL-8 compared with HIV-positive non-smokers and significantly higher exosomal IL-6 levels compared with HIV-negative subjects. HIV-positive smokers had significantly increased plasma levels of IL-1ra compared to HIV-positive non-smokers. The MCP-1 levels in the plasma of HIV-positive smokers was significantly higher than in either HIV-positive non-drug abusers or HIV-negative smokers. Overall, the findings suggest that plasma cytokines and chemokines are packaged in exosomes at varying degrees in different study groups. Exosomal cytokines and chemokines are likely to have a significant biological role at distant sites including cells in the brain.

Tuberculosis and cigarette smoke exposure: An update of in vitro and in vivo studies

Tuberculosis (TB) has been declared the first cause of death by an infectious agent. Annually, 10.4 million people suffer active TB. Most infected individuals live in low-income countries, where social and economic conditions enhance the dissemination and progression of the disease. These countries have a high percentage of smokers. Thousands of studies have linked cigarette smoke (CS) with increased risk of many diseases, such as cancer and lung diseases. Numerous in vitro studies have been conducted to evaluate the general and specific toxic effects of CS in lung immune function. Smoke exposure increases the risk of TB development three-fold. However, until now, only few animal studies have been performed to analyze the association between smoke and TB. In the present work, we review in vitro and in vivo studies whose aim was to analyze the molecular basis of TB susceptibility caused by exposure to CS.

Toxicity of the main electronic cigarette components, propylene glycol, glycerin, and nicotine, in Sprague-Dawley rats in a 90-day OECD inhalation study complemented by molecular endpoints

While the toxicity of the main constituents of electronic cigarette (ECIG) liquids, nicotine, propylene glycol (PG), and vegetable glycerin (VG), has been assessed individually in separate studies, limited data on the inhalation toxicity of them is available when in mixtures. In this 90-day subchronic inhalation study, Sprague-Dawley rats were nose-only exposed to filtered air, nebulized vehicle (saline), or three concentrations of PG/VG mixtures, with and without nicotine. Standard toxicological endpoints were complemented by molecular analyses using transcriptomics, proteomics, and lipidomics. Compared with vehicle exposure, the PG/VG aerosols showed only very limited biological effects with no signs of toxicity. Addition of nicotine to the PG/VG aerosols resulted in effects in line with nicotine effects observed in previous studies, including up-regulation of xenobiotic enzymes (Cyp1a1/Fmo3) in the lung and metabolic effects, such as reduced serum lipid concentrations and expression changes of hepatic metabolic enzymes. No toxicologically relevant effects of PG/VG aerosols (up to 1.520  mg PG/L + 1.890 mg VG/L) were observed, and no adverse effects for PG/VG/nicotine were observed up to 438/544/6.6 mg/kg/day. This study demonstrates how complementary systems toxicology analyses can reveal, even in the absence of observable adverse effects, subtoxic and adaptive responses to pharmacologically active compounds such as nicotine.

Protective efficacy of folic acid and vitamin B12 against nicotine-induced toxicity in pancreatic islets of the rat

Although cigarette smoking is associated with insulin resistance and an increased risk for type 2 diabetes, few studies have examined the effect of nicotine on the adult endocrine pancreas. In this study, male Wister rats were treated with nicotine (3 mg/kg body weight/ day) with or without supplementation of folic acid (36 μg/kg body weight/day) or vitamin B12 (0.63 μg/kg body weight/day) alone or in combination. Fasting blood glucose, insulin and HBA1C level and different oxidative and anti-oxidative stress parameters were measured and pancreatic tissue sections were stained with eosin-haematoxylene. Data were analysed by nonparametric statistics. The results revealed that nicotine induced prediabetes condition with subsequent damage to pancreatic islets in rats. Nicotine also caused oxidative stress in pancreatic tissue as evidenced by increased nitric oxide and malondialdehyde level and decreased superoxide dismutase, catalase and reduced glutathione level. Compared to vitamin B12 supplementation, folic acid blunted the nicotine-induced toxicity in pancreatic islets with higher efficacy. Further, folic acid and vitamin B12 in combination were able to confer significant protection on pancreatic islets against nicotine induced toxicity. These results suggest that supplementation of folic acid and vitamin B12 in combination may be a possible strategy of detoxification against nicotine-induced toxicity in pancreatic islets of the rat.

Impact of maternal cigarette smoke exposure on brain inflammation and oxidative stress in male mice offspring

Maternal cigarette smoke exposure (SE) during gestation can cause lifelong adverse effects in the offspring's brain. Several factors may contribute including inflammation, oxidative stress and hypoxia, whose changes in the developing brain are unknown. Female Balb/c mice were exposed to cigarette smoke prior to mating, during gestation and lactation. Male offspring were studied at postnatal day (P) 1, P20 and 13 weeks (W13). SE dams had reduced inflammatory mediators (IL-1β, IL-6 and toll like receptor (TLR)4 mRNA), antioxidant (manganese superoxide dismutase (MnSOD)), and increased mitochondrial activities (OXPHOS-I, III and V) and protein damage marker nitrotyrosine. Brain hypoxia-inducible factor (HIF)1α and its upstream signalling molecule early growth response factor (EGR)1 were not changed in the SE dams. In the SE offspring, brain IL-1R, IL-6 and TLR4 mRNA were increased at W13. The translocase of outer mitochondrial membrane, and MnSOD were reduced at W13 with higher nitrotyrosine staining. HIF-1α was also increased at W13, although EGR1 was only reduced at P1. In conclusion, maternal SE increased markers of hypoxia and oxidative stress with mitochondrial dysfunction and cell damage in both dams and offspring, and upregulated inflammatory markers in offspring, which may render SE dams and their offspring vulnerable to additional brain insults.

[Search of (-)-Cytisine Derivatives as Potential Inhibitors of NF-κB and STAT1]

Design and synthesis ofnew derivatives of (-)-cytisine with a wide spectrum of pharmacological activity, represents the potential therapeutic interest for development of drug candidates for neurodegenerative disorders, inflammatory diseases, and treatment of nicotine addiction. We used HEK293 cell line transiently transfected with N F-κB and STATI luciferase reporter constructs to screen the (-)-cytisine derivatives for their potency to modulate basal and induced NF-κB and STAT1 activity. Currently, NF-κB, STAT1 and components of their signaling pathways are considered as attractive targets for pharmacological intervention, primarily in chronic inflammation, cancer, autoimmune, neurodegenerative and infectious diseases. The library of compounds included the derivatives of (-)-cytisine with amino-, amide-, thio- and carboxamide groups at 3, 5 and 12 position of the starting molecule, as well as some bimolecular derivatives. Our experimental data revealed compounds with moderate activating as well as inhibitory effects for basal NF-κB and STATI activity (IC50 or EC50 values are mainly in the micromolar range). The structure-activity relationship analysis demonstrated that the character of activity (activation or inhibition of NFκ-B and STAT1) is determined by the topology of the substituents at the (-)-cytisine molecule, whereas the nature of the substituents mainly contributes to severity of the effect (introduction of aromatic and adamantyl substituents, as well as thionyl or keto groups are of the principal importance). When evaluating the effect of (-)-cytisine derivatives on activity of NF-κB and STATI, induced by specific agents (TNFα and IFNγ, respectively) we observed that some compounds inhibited basal and stimulated activity of NF-κB and STAT1, another compounds showed the dual effect (an increase of basal- and a decrease of stimulated NF-κB activity) and several compounds increase both basal and induced activity of NF-κB and STAT1. Thus, obtained results suggest that one of the possible mechanisms of biological action of (-)-cytisine derivatives is their ability to influence the components of NF-κB and STAT1-dependent signaling pathways.

Tobacco smoking effect on HIV-1 pathogenesis: role of cytochrome P450 isozymes

INTRODUCTION

Tobacco smoking is highly prevalent among the HIV-1-infected population. In addition to diminished immune response, smoking has been shown to increase HIV-1 replication and decrease response to antiretroviral therapy, perhaps through drug-drug interaction. However, the mechanism by which tobacco/nicotine increases HIV-1 replication and mediates drug-drug interaction is poorly understood.

AREAS COVERED

In this review, the authors discuss the effects of smoking on HIV-1 pathogenesis. Since they propose a role for the cytochrome P450 (CYP) pathway in smoking-mediated HIV-1 pathogenesis, the authors briefly converse the role of CYP enzymes in tobacco-mediated oxidative stress and toxicity. Finally, the authors focus on the role of CYP enzymes, especially CYP2A6, in tobacco/nicotine metabolism and oxidative stress in HIV-1 model systems monocytes/macrophages, lymphocytes, astrocytes and neurons, which may be responsible for HIV-1 pathogenesis.

EXPERT OPINION

Recent findings suggest that CYP-mediated oxidative stress is a novel pathway that may be involved in smoking-mediated HIV-1 pathogenesis, including HIV-1 replication and drug-drug interaction. Thus, CYP and CYP-associated oxidative stress pathways may be potential targets to develop novel pharmaceuticals for HIV-1-infected smokers. Since HIV-1/TB co-infections are common, future study involving interactions between antiretroviral and antituberculosis drugs that involve CYP pathways would also help treat HIV-1/TB co-infected smokers effectively.

Natural immune responses against eight oncogenic human papillomaviruses in the ASCUS-LSIL Triage Study

Only a subset of women with human papillomavirus (HPV) infections will become seropositive, and the factors influencing seroconversion are not well understood. We used a multiplex serology assay in women with mildly abnormal cytology results to examine seroreactivity to oncogenic HPV genotypes. An unbiased subset of women in the atypical squamous cell of undetermined significance /low-grade squamous intraepithelial lesion Triage Study provided blood samples at trial enrollment for serological testing. A Luminex assay based on glutathione s-transferase-L1 fusion proteins as antigens was used to test seroreactivity against eight carcinogenic HPV genotypes (16, 18, 31, 33, 35, 45, 52 and 58). We analyzed the relationship between seroprevalence in women free of precancer (N = 2,464) and HPV DNA status, age, sexual behavior and other HPV-related risk factors. The overall seroprevalence was 24.5% for HPV16 L1 and ∼20% for 18L1 and 31L1. Among women free of precancer, seroprevalence peaked in women less than 29 years and decreased with age. Type-specific seroprevalence was associated with baseline DNA detection for HPV16 (OR = 1.36, 95%CI: 1.04-1.79) and HPV18 (OR = 2.31, 95%CI: 1.61-3.32), as well as for HPV52 and HPV58. Correlates of sexual exposure were associated with increased seroprevalence across most genotypes. Women who were current or former smokers were less likely to be seropositive for all eight of the tested oncogenic genotypes. The multiplex assay showed associations between seroprevalence and known risk factors for HPV infection across nearly all tested HPV genotypes but associations between DNA- and serostatus were weak, suggesting possible misclassification of the participants' HPV serostatus.

Elevated IL-17A levels in early stages of bladder cancer regardless of smoking status

Aim: The interrelation between nicotine and IL-17A in bladder cancer (BC) patients was investigated. Methods: IL-17A in the sera of 121 BC patients who smoked nicotine, 80 nonsmoker BC patients, 29 and 30 age- and sex-matched healthy smokers and nonsmokers were also measured. Results: IL-17A was elevated in smoker and nonsmoker BC patients compared with smoker and nonsmoker controls (p = 0.004 and p = 0.004, respectively). The level of IL-17A in BC patients who smoked both water pipes and cigarettes were the highest (4.35±8.57 pg/ml), followed by BC water pipe users only (1.33±3.122 pg/ml) and cigarette smokers only (0.79±2.26 pg/ml, p = 0.001). IL-17A was elevated in lower stages (I and II) compared with higher stages (III and IV) of the disease (p = 0.013). Conclusion: IL-17A levels are elevated in some BC patients. IL-17A is an important factor in the inflammatory process during tumor progression, either as a defense mechanism or as a tumor-promoting factor.

The anti-inflamm-aging and hepatoprotective effects of huperzine A in D-galactose-treated rats

Oxidative stress contributes to a chronic inflammatory process referred to as "inflamm-aging". Acetylcholinesterase inhibitors (AChEI) can enhance cholinergic transmission and act as anti-inflammatory agents via immunocompetent cells expressing α-7 acetylcholine receptors (AChR). The present study explores the possible role of huperzine A, a reversible and selective AChEI, against D-gal-induced oxidative damage, cell toxicity and inflamm-aging in rat livers. In two-month-old rats with normal liver function, an 8-week administration of D-gal (300 mg/kg subcutaneously (s.c.) injected), significantly increased hepatic impairment, ROS generation and oxidative damage, hepatic senescence, nuclear factor-kappa B (NF-κB) activation and inflammatory responses. An 8-week co-administration of both D-gal (300 mg/kg s.c.) and huperzine A (0.1 mg/kg s.c.) not only significantly decreased hepatic function impairment, ROS generation, oxidative damage, but also suppressed inflamm-aging by inhibiting hepatic replicative senescence, AChE activity, IκBα degradation, NF-κB p65 nuclear translocation and inflammatory responses. The expression levels of pro-inflammatory cytokine mRNA and proteins, such as TNFα, IL-1β and IL-6 decrease significantly, and the protein levels of the anti-inflammatory cytokine IL-10 display an obvious increase. These findings indicated that D-gal-induced hepatic injury and inflamm-aging in the rat liver was associated with the development of a pro-inflammatory phenotype in this organ. D-gal induced damage-associated molecular patterns (DAMPs) because oxidative damages might play an important role in D-gal-induced hepatic sterile inflammation. Huperzine A exhibited protective effects against D-gal-induced hepatotoxicity and inflamm-aging by inhibiting AChE activity and via the activation of the cholinergic anti-inflammatory pathway. The huperzine A mechanism might be involved in the inhibition of DAMPs-mediated NF-κB nuclear localization and activation.

Role of nicotinic receptors and acetylcholine in mucous cell metaplasia, hyperplasia, and airway mucus formation in vitro and in vivo

BACKGROUND

Airway mucus hypersecretion is a key pathophysiologic feature in a number of lung diseases. Cigarette smoke/nicotine and allergens are strong stimulators of airway mucus; however, the mechanism of mucus modulation is unclear.

OBJECTIVES

We sought to characterize the pathway by which cigarette smoke/nicotine regulates airway mucus and identify agents that decrease airway mucus.

METHODS

IL-13 and γ-aminobutyric acid type A receptors (GABA(A)Rs) are implicated in airway mucus. We examined the role of IL-13 and GABA(A)Rs in nicotine-induced mucus formation in normal human bronchial epithelial (NHBE) and A549 cells and secondhand cigarette smoke-induced, ovalbumin-induced, or both mucus formation in vivo.

RESULTS

Nicotine promotes mucus formation in NHBE cells; however, the nicotine-induced mucus formation is independent of IL-13 but sensitive to the GABA(A)R antagonist picrotoxin. Airway epithelial cells express α7-, α9-, and α10-nicotinic acetylcholine receptors (nAChRs), and specific inhibition or knockdown of α7- but not α9/α10-nAChRs abrogates mucus formation in response to nicotine and IL-13. Moreover, addition of acetylcholine or inhibition of its degradation increases mucus in NHBE cells. Nicotinic but not muscarinic receptor antagonists block allergen- or nicotine/cigarette smoke-induced airway mucus formation in NHBE cells, murine airways, or both.

CONCLUSIONS

Nicotine-induced airway mucus formation is independent of IL-13, and α7-nAChRs are critical in airway mucous cell metaplasia/hyperplasia and mucus production in response to various promucoid agents, including IL-13. In the absence of nicotine, acetylcholine might be the biological ligand for α7-nAChRs to trigger airway mucus formation. α7-nAChRs are downstream of IL-13 but upstream of GABA(A)Rα2 in the MUC5AC pathway. Acetylcholine and α7-nAChRs might serve as therapeutic targets to control airway mucus.

Rapidly progressive colonic dysplasia/neoplasia in a series of treated lung cancer patients: Is paclitaxel involved?

Incidence of second malignancies in patients with advanced lung cancer is not well-studied, in part because of a short survival in this patient population. Apart from a genetic predisposition, various environmental hazards may also be at play in their pathogenesis. Chronic smoking exposure decreases T-cell responsiveness and stimulates production of a variety of inhibitory cytokines. Paclitaxel has been associated with several immunosuppressive effects such as decreased numbers and activity of dendritic cells, NK-cells, and monocytes. We herein describe the first series of lung cancer patients who developed colonic polyps/colon cancer either during or immediately following chemotherapy with paclitaxel, suggesting a possible role of this agent in their pathogenesis.

Exposure to nicotine adversely affects the dendritic cell system and compromises host response to vaccination

The magnitude of Th1 cells response to vaccination is a critical factor in determining protection from clinical disease. Our previous in vitro studies suggested that exposure to the nicotine component of cigarette smoke skews the differentiation of both human and mouse dendritic cell (DC) precursors into atypical DCs (DCs differentiated ex vivo in the presence of nicotine) lacking parameters essential for the development of Th1-mediated immunity. In this study, we determined the causal relationship between nicotine-induced DC alterations and host response to vaccines. We show that animals exposed to nicotine failed to develop and maintain Ag-specific effector memory Th1 cells and Ab production to protein-based vaccine formulated with Th1 adjuvants. Accordingly, both prophylactic and therapeutic vaccines failed to protect and cure the nicotine-exposed mice from disease. More importantly, we demonstrate the nicotine-induced defects in the biological activities of in vivo DCs as an underlying mechanism. Indeed, i.v. administration of DCs differentiated in the presence of nicotine preferentially promoted the development of Ag-specific IL-4-producing effector cells in the challenged mice. In addition, DC subsets isolated from mice exposed to nicotine produced significantly less cytokines in response to Th1 adjuvants and inadequately supported the development of Ag-specific Th1 cells. Collectively, our studies suggest that nicotine-induced defects in the DC system compromises vaccine efficacy in smokers.

Influence of experimental subarachnoid hemorrhage on nicotine-induced contraction of the rat basilar artery in relation to arachidonic acid metabolites signaling pathway

BACKGROUND

Smoking is one of the most important risk factors for cerebral circulatory disorders. The purpose of this study was to investigate the influence of experimental subarachnoid hemorrhage (SAH) on nicotine-induced contraction (arachidonic acid metabolites) in the basilar arteries of rats.

METHODS

Rats were killed at 1 hour and 1 week after blood injection, and the basilar artery was isolated and cut into a spiral strip.

RESULTS

Testing of cyclooxygenase-1 (COX-1) and 5-lipoxygenase (5-LOX) inhibitors revealed no significant differences in their effects on normal and SAH (1 hour and 1 week). Phospholipase C (PLC) inhibitor (1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17yl)amino)hexyl)-1H-pyrrole-2,5,-dione [U-73122]) slightly inhibited contraction of SAH (1 hour and 1 week) when compared to controls. Phospholipase A2 (PLA2) inhibitor (manoalide) and cytosolic PLA2 (cPLA2) inhibitor (arachidonyltrifluoromenthylketone [AACOCF3]) more strongly attenuated contraction in SAH (1 hour and 1 week) than in controls. Secreted PLA2 (sPLA2) inhibitor (indoxam), PLC inhibitor (2-nitro-4-carboxyphenyl N, N-diphenylcarbamate [NCDC]), and COX-2 inhibitors (nimesulide, (5-methanesulfonamido-6-(2,4-difluorothiophenyl)-1-indanone) [L-745337], and celecoxib) only slightly inhibited contraction of SAH (1 week) when compared to normal and SAH (1 hour). The calcium-independent PLA2 (iPLA2) inhibitor bromoenol lactone (BEL) showed greater inhibition of contraction in SAH (1 hour) when compared to normal and SAH (1 week).

CONCLUSIONS

One week after exposure to SAH, PLC, sPLA2, and COX-2 activity were enhanced and cPLA2 activity was inhibited. One hour after exposure to SAH, PLC activity was enhanced and cPLA2 and iPLA2 activity was inhibited. Such changes of inflammatory arachidonic acid metabolites by smoking after SAH may play important roles in fatal cerebral circulatory disorders, suggesting important implications for the etiology and pathogenesis of SAH.

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.

GABA- and acetylcholine-related gene expression in blood correlate with tic severity and microarray evidence for alternative splicing in Tourette syndrome: a pilot study

Tourette syndrome (TS) is a complex childhood neurodevelopmental disorder characterized by motor and vocal tics. Recently, altered numbers of GABAergic-parvalbumin (PV) and cholinergic interneurons were observed in the basal ganglia of individuals with TS. Thus, we postulated that gamma-amino butyric acid (GABA)- and acetylcholine (ACh)-related genes might be associated with the pathophysiology of TS. Total RNA isolated from whole blood of 26 un-medicated TS subjects and 23 healthy controls (HC) was processed on Affymetrix Human Exon 1.0 ST arrays. Data were analyzed to identify genes whose expression correlated with tic severity in TS, and to identify genes differentially spliced in TS compared to HC subjects. Many genes (3627) correlated with tic severity in TS (p < 0.05) among which GABA- (p = 2.1 × 10⁻³) and ACh- (p = 4.25 × 10⁻⁸) related genes were significantly over-represented. Moreover, several GABA and ACh-related genes were predicted to be alternatively spliced in TS compared to HC including GABA receptors GABRA4 and GABRG1, the nicotinic ACh receptor CHRNA4 and cholinergic differentiation factor (CDF). This pilot study suggests that at least some of these GABA- and ACh-related genes observed in blood that correlate with tics or are alternatively spliced are involved in the pathophysiology of TS and tics.

It takes nerves to fight infections: insights on neuro-immune interactions from C. elegans

The innate immune response is evoked as a consequence of interactions between invading foreign infectious agents and host immune cells. A successful innate immune response is pivotal in maintaining the delicate balance between health and disease; an insufficient response results in infection, whereas an excessive response results in prolonged inflammation and tissue damage. Alterations in the state and function of the nervous system influence the immune response. The nervous system regulates innate immune responses through the release of neurotransmitters, neuropeptides and neurohormones. However, many questions related to the molecular and cellular mechanisms involved, the physiological role of the link between the immune and the nervous system, and the biological significance of neuro-immune interactions remain unresolved. The interactions between the nematode Caenorhabditis elegans and its pathogens provide insights into mechanisms of neuroendocrine regulation of immunity and address many outstanding issues related to neuro-immune interactions.

Activation of the cholinergic anti-inflammatory system by nicotine attenuates neuroinflammation via suppression of Th1 and Th17 responses

The alpha7 nicotinic acetylcholine receptor (nAChR) was recently described as an anti-inflammatory target in both macrophages and T cells. Its expression by immune cells may explain the epidemiological data claiming a negative link between cigarette smoking and several inflammatory diseases. In this study, we determined the immunological effects of alpha7 nAChR activation by nicotine. Our results indicate that the alpha7 nAChR is expressed on the surface of CD4(+) T cells and that this expression is up-regulated upon immune activation. Nicotine reduced T cell proliferation in response to an encephalitogenic Ag, as well as the production of Th1 (TNF-alpha and IFN-gamma) and Th17 cytokines (IL-17, IL-17F, IL-21, and IL-22). IL-4 production was increased in the same setting. Attenuation of the Th1 and Th17 lineages was accompanied by reduced T-bet (50%) and increased GATA-3 (350%) expression. Overall, nicotine induced a shift to the Th2 lineage. However, alpha7(-/-)-derived T cells were unaffected by nicotine. Furthermore, nicotine reduced NF-kappaB-mediated transcription as measured by IL-2 and IkappaB transcription. In vivo, administration of nicotine (2 mg/kg s.c.) suppressed the severity of CD4(+) T cell-mediated disease experimental autoimmune encephalomyelitis. alpha7(-/-) mice were refractory to nicotine treatment, although disease severity in those animals was reduced, due to impairment in Ag presentation. Accordingly, CD4(+) and CD11b(+) cells infiltration into the CNS, demyelination, and axonal loss were reduced. Our data implicate a role for the alpha7 nAChR in immune modulation and suggest that alpha7 nAChR agonists may be effective in the treatment of inflammatory disorders.

Rheumatoid arthritis and smoking: putting the pieces together

Besides atherosclerosis and lung cancer, smoking is considered to play a major role in the pathogenesis of autoimmune diseases. It has long been known that there is a connection between rheumatoid factor-positive rheumatoid arthritis and cigarette smoking. Recently, an important gene-environment interaction has been revealed; that is, carrying specific HLA-DRB1 alleles encoding the shared epitope and smoking establish a significant risk for anti-citrullinated protein antibody-positive rheumatoid arthritis. We summarize how smoking-related alteration of the cytokine balance, the increased risk of infections (the possibility of cross-reactivity) and modifications of autoantigens by citrullination may contribute to the development of rheumatoid arthritis.

Nicotine and inflammatory neurological disorders

Cigarette smoke is a major health risk factor which significantly increases the incidence of diseases including lung cancer and respiratory infections. However, there is increasing evidence that smokers have a lower incidence of some inflammatory and neurodegenerative diseases. Nicotine is the main immunosuppressive constituent of cigarette smoke, which inhibits both the innate and adaptive immune responses. Unlike cigarette smoke, nicotine is not yet considered to be a carcinogen and may, in fact, have therapeutic potential as a neuroprotective and anti-inflammatory agent. This review provides a synopsis summarizing the effects of nicotine on the immune system and its (nicotine) influences on various neurological diseases.

Nicotinic receptors containing the alpha7 subunit: a model for rational drug design

The neuronal nicotinic receptor has gained considerable recognition as a target, not just for combating drug addiction but also for treating a number of illnesses ranging from neurodegenerative diseases to psychotic disorders like schizophrenia. This recognition has led to a burgeoning field examining the receptor at all levels. A class of nicotinic receptors that contains the alpha7 gene product, apparently as a homomer, illustrates this multidisciplinary approach. Here, we review recent progress in our understanding of this class of receptors based on data from molecular, structural, physiological and patho-physiological studies. These studies have set the stage for rational drug design to combat disorders of the central nervous system. The studies also exemplify the cautious approach needed in developing CNS therapies and the importance of physiology in tempering drug design.

Pharmacological nature of nicotine-induced contraction in the rat basilar artery: Involvement of arachidonic acid metabolites

The pharmacological nature of nicotine-induced contraction in the rat basilar artery is poorly understood. The purpose of this study was to investigate the endothelium dependency and involvement of arachidonic acid metabolites in nicotine-induced contraction in the rat basilar artery. The rat basilar artery was removed from the brain and cut into a spiral preparation. Nicotine (3x10(-5) to 10(-2) M) induced the concentration-dependent contraction in the rat basilar artery, and the maximal contraction was obtained at 3x10(-3) M. The contraction induced by nicotine (3x10(-3) M) was significantly attenuated by the presence of saponin (0.05 mg/ml, 15 min). Phospholipase C (PLC) inhibitors (NCDC and U-73122), calcium-independent phospholipase A(2) (iPLA(2)) inhibitor (BEL), cyclooxygenase-2 (COX-2) inhibitors (nimesulide, L-745,337 and celecoxib), and a 5-lipoxygenase (5-LOX) inhibitor (ZM-230487) concentration-dependently attenuated the nicotine-induced contraction. A cytosolic phospholipase A(2) (cPLA(2)) inhibitor (AACOCF3), secretory phospholipase A(2) (sPLA(2)) inhibitor (indoxam), and cyclooxygenase-1 (COX-1) inhibitors (flurbiprofen and ketoprofen) did not affect the nicotine-induced contraction. From these results, it was suggested that nicotine-induced contraction in the rat basilar artery is endothelium-dependent and is due to arachidonic acid metabolites.

IBU-octyl-cytisine, a novel bifunctional compound eliciting anti-inflammatory and cholinergic activity, ameliorates CNS inflammation by inhibition of T-cell activity

Experimental autoimmune encephalomyelitis (EAE) is a central nervous system (CNS) inflammatory model in which MOG-specific T-cells initiate an autoimmune attack leading to demyelinization and consequently, neurological damage and morbidity. As EAE pathogenesis results from the involvement of immune cells, CNS resident-cells and inflammatory mediators, our treatment strategy was to use a bifunctional compound with dual anti-inflammatory properties: a non-steroidal anti-inflammatory moiety and a nicotinic agonist moiety, intended to interact with the alpha7 nicotinic receptor present on immune cells. We used IBU-Octyl-Cytisine, with an ibuprofen (IBU) moiety and Cytisine, as the nicotinic agonist. The two moieties are attached by an eight carbon (octyl) spacer. Treatment of EAE with IBU-Octyl-Cytisine (2.5 mg/kg/day, i.p.) reduced significantly (by 70%) disease severity and inflammatory infiltrates in the spinal cord. An equivalent dose of IBU was ineffective, whereas Cytisine was significantly toxic. Treatment with IBU-Octyl-Cytisine inhibited the T-cell response toward the encephalitogenic epitope of myelin oligodendrocyte glycoprotein (MOG). In addition, expression of CCR5 by CD4(+)T-cells was lower, indicating a reduced migratory capacity following treatment. IBU-Octyl-Cytisine reduced Th(1) but not Th(2) cytokine production. This reduction was accompanied by a drop in the level of T-bet mRNA, a transcription factor pivotal to Th(1) lineage differentiation. Thus, IBU-Octyl-Cytisine is an effective treatment for EAE, influencing T-cell responses in several stages of disease pathogenesis. This bifunctional compound was more efficient than IBU or Cytisine separately, as well as than both moieties unconjugated. Thus, it seems that this strategy may be applicable in wider context.

Protective activity ofBacopa monniera Linn. on nicotine-induced toxicity in mice

Nicotine, a pharmacologically active component of cigarettes smoke causes devastating effects in important biomolecules of the cell through generation of free radicals leading to genomic instability. Bacopa monniera is a reputed drug in Ayurveda known for its hepatoprotective and DNA protective effects. In this study, an aqueous extract of Bacopa monniera (BAE, 50 mg/kg i.p.) was investigated for its ability to reduce nicotine-induced lipid peroxidation (LPO) and confer genoprotection in Swiss mice. Genoprotective effect was assayed using micronucleus (MN) assay. LPO status was studied by evaluating MDA levels and antioxidant status. Nicotine altered hepatic function as evident by increased ALP and GST levels and decreased SOD, catalase and GPx activities. BAE treatment restored antioxidant enzymes such as SOD, catalase and GPx in liver. BAE treatment also significantly reduced the frequency of micronuclei induced by nicotine by decreasing the incidence of micronucleated polychromatic erythrocytes (MN-PCE). Hepatic GSH, ALP and GST levels were brought to normal values indicating protection. The results of the present study suggest that BAE exerts protective effects by modulating the extent of lipid peroxidation and enhancing the antioxidant status.

Early postnatal exposure to cigarette smoke impairs the antigen-specific T-cell responses in the spleen

Annually, approximately two million babies are exposed to cigarette smoke in utero and postnatally through cigarette smoking of their mothers. Exposure to mainstream cigarette smoke is known to impair both innate and adaptive immunities, and it has been hypothesized that the effects of in utero exposure to cigarette smoke on children's health might primarily stem from the adverse effects of cigarette smoke on the immune system. To simulate the environment that babies from smoking mothers encounter, we examined the effects of prenatal mainstream and postnatal sidestream cigarette smoke on spleen cell responses. Results show that postnatal exposure of newborn Balb/c mouse pups to sidestream cigarette smoke through the first 6 weeks of life strongly suppresses the antibody response of spleen cells to the T-cell-dependent antigen, sheep red blood cells. The reduction in the antibody response seen within 6 weeks of postnatal smoke exposure is much quicker than the published data on the time 25 weeks) required to establish reproducible immunosuppression in adult rats and mice. Moreover, the immunosuppression is not associated with significant changes in T-cell numbers or subset distribution. While the postnatal exposure to cigarette smoke did not affect the mitogenic response of T and B cells, the exposure inhibited the T cell receptor-mediated rise in the intracellular calcium concentration. These results suggest that the early postnatal period is highly sensitive to the immunosuppressive effects of environmental tobacco smoke, and the effects are causally associated with impaired antigen-mediated signaling in T cells.

Adolescent exposure to nicotine modifies acute functional responses to cannabinoid agonists in rats

We have studied functional interactions between nicotine and the cannabinoid receptor agonist CP 55,940 (CP) in the modulation of behavioural and corticosterone responses of male and female adolescent Wistar rats. The animals underwent a subchronic nicotine treatment (0.4 mg/kg i.p., once daily) during the periadolescent period (postnatal days 34-43). Twenty-four hours after the last injection of nicotine an acute dose of CP (1 or 100 microg/kg i.p.) was administered. Thirty minutes after the cannabinoid injection, the animals were tested individually in the holeboard immediately followed by the elevated plus-maze. We also measured corticosterone levels by radioimmunoassay. In males, neither CP (1 microg/kg) nor nicotine induced any modification in anxiety when administered alone. However, the combination of the two drugs resulted in a significant anxiogenic-like effect. In females, the lower dose of CP was anxiogenic and nicotine, which did not induce any effect per se, prevented this response. In the holeboard, subchronic nicotine and the acute cannabinoid treatment interacted in the modulation of horizontal activity and the nature of this interaction also showed a clear sexual dimorphism. Both, the cannabinoid agonist and nicotine increased corticosterone concentrations and the animals receiving the two drugs showed higher levels than the animals receiving the cannabinoid alone. The data provide evidence for the existence of functional interactions between nicotine and cannabinoids in the modulation of behavioural responses and adrenocortical activity in adolescent rats.

Evidence for the role of nitric oxide in antiapoptotic and genotoxic effect of nicotine on human gingival fibroblasts

Resistance to apoptosis is essential for cancer survival and plays a critical role in carcinogenesis. Growing evidence suggests that nicotine can act as a tumor promoter, impairing apoptotic process in certain types of human cancer cell lines. Our previous study revealed in human gingival fibroblasts (HGFs) a concomitant antiapoptotic and genotoxic effect of nicotine, manifested by the attenuation of staurosporine (STP)-induced apoptosis and the increase of micronucleus frequency. The present report provides evidence that nitric oxide (NO) is critically involved in these actions. In vitro treatment with sodium nitroprusside as NO donor showed that NO produced similar effects as those observed with nicotine: it caused DNA damage and partially prevented apoptosis induced by staurosporine. Exposure of HGFs to nicotine, at concentrations similar to those found in the blood of habitual smokers, leads to the production of NO associated with the induction of inducible nitric oxide synthase (iNOS) expression. Experiments using an inhibitor of iNOS, N-monomethyl-L-arginine (NMA), together with nicotine confirmed the involvement of NO in the drug action, abrogating completely cell death and a good part of the genotoxicity. Finally, we show by different approaches that the inhibition of cell death by nicotine through NO release is related to modulation of caspase-1 activation.

Early manifestations of NNK-induced lung cancer: role of lung immunity in tumor susceptibility

A strong correlation exists between smoking and lung cancer; however, susceptibility to lung cancer among smokers is not uniform. Similarly, mice show differential susceptibility to the tobacco carcinogen nitrosamine 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which produces lung tumors in A/J but not in C3H mice. Host immunity may play a role in the susceptibility to cancer, and cigarette smoke/nicotine suppresses the immune system through activation of nicotinic acetylcholine receptors (nAChRs). Mammalian lungs express alpha7-nAChRs, and NNK is a high-affinity agonist for alpha7-nAChRs. To examine whether NNK differentially modulates lung immunity in susceptible and resistant mouse strains, A/J and C3H mice were treated with NNK and/or immunized with sheep red blood cells. Lung tissues and RNA of treated and untreated animals were analyzed by immunohistochemistry and RT-PCR for alpha7-nAChR and COX-2 expression. Spleen- and the lung-associated lymph node cells from control and immunized animals were assessed for immunologic responses, including anti-sheep red blood cell antibody plaque-forming cells, concanavalin A-induced T-cell proliferation, and the anti-CD3/CD28 antibody-induced rise in intracellular calcium. NNK strongly suppressed these responses in A/J but not in C3H mice. Similar NNK-induced immunologic changes were seen in another pair of carcinogen-sensitive (NGP) and relatively carcinogen-resistant (B10.A) mouse strains. Moreover, NNK stimulates a significantly higher expression of COX-2 and alpha7-nAChRs in A/J than in C3H lungs. These results suggest that the susceptibility to chemical carcinogenesis among various mouse strains might be influenced by their immunologic response to the carcinogen.

Sustained exposure to nicotine leads to extramedullary hematopoiesis in the spleen

The effect of sustained exposure to nicotine, a major constituent of cigarette smoke, on hematopoiesis in the bone marrow (BM) and spleen was evaluated in a murine model. BALB/c mice were exposed to nicotine subcutaneously using 21-day slow-release pellets. Exposure to nicotine had no effect on the proliferation of long-term BM cultures or on their ability to form colonies. However, there was a significant decrease in the generation of lineage-specific progenitor cells, specifically eosinophil (colony-forming unit [CFU]-Eos) progenitors, in the BM of nicotine-exposed mice compared with control mice. Surprisingly, sustained exposure of mice to nicotine was found to induce significant hematopoiesis in the spleen. There was a significant increase in total colony formation as well as eosinophil-, granulocyte-macrophage-, and B-lymphocyte-specific progenitors (CFU-Eos, CFU-GM, and CFU-B, respectively) in nicotine-exposed mice but not in control mice. Sustained exposure to nicotine was associated with significant inhibition of rolling and migration of enriched hematopoietic stem/progenitor cells (HSPCs) across BM endothelial cells (BMECs) in vitro as well as decreased expression of beta2 integrin on the surface of these cells. Although sustained exposure to nicotine has only a modest effect on BM hematopoiesis, our studies indicate that it significantly induces extramedullary hematopoiesis in the spleen. Decreased interaction of nicotine-exposed HSPCs with BMECs (i.e., rolling and migration) may result in altered BM homing of these cells, leading to their seeding and proliferation at extramedullary sites such as the spleen.

Smoking and tuberculosis: the epidemiological association and immunopathogenesis

There is increasing evidence of a link between tuberculosis and smoking. This paper reviews the epidemiological evidence from the UK, China, India and the USA, summarizing some of the main papers which indicate an association. Where an association has been found there seems to be an increase in tuberculosis case rates of between two- and four-fold for those smoking in excess of 20 cigarettes a day, but it may be difficult to control for other factors, particularly alcohol consumption. The final part of the paper reviews possible mechanisms. A likely possibility is that nicotine turns off the production of TNF-alpha by the macrophages in the lungs, rendering the patient more susceptible to the development of progressive disease from latent Mycobacterium tuberculosis infection.

Anti-inflammatory properties of cholinergic up-regulation: A new role for acetylcholinesterase inhibitors

We investigated the anti-inflammatory effects of acetylcholinesterase inhibitors (AChEI) at the cellular and molecular levels. AChEI suppressed lymphocyte proliferation and pro-inflammatory cytokine production, as well as extracellular esterase activity. Anti-inflammatory activity was mediated by the alpha7 nicotinic acetylcholine receptor (neuronal); the muscarinic receptor had the opposite effect. Treatment of the central nervous system (CNS) inflammatory disease, experimental autoimmune encephalomyelitis (EAE), with EN101, an anti-sense oligodeoxynucleotide, targeted to AChE mRNA, reduced the clinical severity of the disease and CNS inflammation intensity. The results of our experiments suggest that AChEI increase the concentration of extracellular acetylcholine (ACh), rendering it available for interaction with a nicotinic receptor expressed on lymphocytes. Our findings point to a novel role for AChEI which may be relevant in CNS inflammatory diseases such as EAE and multiple sclerosis. They also emphasize the importance of cholinergic balance in neurological disorders, such as Alzheimer's disease and myasthenia gravis, in which these drugs are used.

Low-level subchronic exposure to wood smoke exacerbates inflammatory responses in allergic rats

Epidemiological studies have implicated wood smoke as a risk factor for exacerbating asthma. However, comparisons of findings in animal models with those in humans are currently not possible, because detailed clinically relevant measurements of pulmonary function are not available in animal studies. Brown Norway rats were immunized with ovalbumin and exposed to either filtered air or wood smoke at 1 mg particulate matter/m(3) for 70 days and challenged with allergen during the last 4 days of exposure. Baseline values for dynamic lung compliance were lower while functional residual capacity was increased in rats exposed to wood smoke compared to rats exposed to filtered air. IFN-gamma levels were reduced and IL-4 levels increased in the bronchoalveolar lavage fluid and blood plasma, inflammatory lesions in the lungs were 21% greater, and airway mucous cells/mm basal lamina were non-significantly increased in rats exposed to wood smoke compared to controls. Collectively, these studies suggest that the pulmonary function was affected in rats by exposure to wood smoke and this decline was associated with only minor increases in inflammation of the lung. Therefore, this animal model may be useful to elucidate the mechanisms of the decline in pulmonary function caused by environmental pollutants when asthmatics are exposed to allergen.

Nicotinic receptors regulate B lymphocyte activation and immune response

The presence of nicotinic acetylcholine receptors (nicotinic receptors) composed of either alpha7 or alpha4 and beta2 subunits is revealed in B lymphocytes by means of radioligand binding assay and Cell ELISA. Mouse B lymphocytes contained 12,200+/-3200 of epibatidine-binding sites and 3130+/-750 of alpha-Bungarotoxin-binding sites per cell. Mice lacking nicotinic receptor subunits alpha4, beta2 or alpha7 had less serum IgG and IgG-producing cells in the spleen, but showed stronger immune response to both protein antigen in vivo and CD40-specific antibody in vitro than wild-type mice. Anti-CD40-stimulated proliferation of B lymphocytes from beta2 knockout, but not wild-type mice was inhibited with nicotine. Our results indicate that signalling through nicotinic receptors affects both the pre-immune state and activation of B lymphocytes in the immune response, possibly via CD40-dependent pathway. This could contribute to immune depression found in tobacco smokers.