The effects of benzo(a)pyrene, nicotine, and tobacco-specific N-nitrosamines on the generation of human lymphokine-activated killer cells

Comparison of effects of smoking and smokeless tobacco "Maras powder" use on humoral immune system parameters

BACKGROUND

The aim of this study is to assess the impacts of "Maras powder" and cigarette smoking on the parameters of the humoral immune system.

MATERIAL AND METHODS

One hundred seventy seven subjects were included in the study. The IgA, IgG, IgM, C3 and C4 levels were detected via nephelometric method.

RESULTS

In 1.4% of the control group IgM levels were below normal where it was 10.8% and 18.6% in Maras powder group and in cigarette smoking group respectively. The IgM levels of both groups were significantly lower compared to the control group (P < .05). Nonetheless, the IgE levels of Maras powder group and smoking group were found to be remarkably higher compared to the control group (P < .01).

CONCLUSION

Effects of Maras powder on humoral immune response were found to be similar to that of smoking.

Smokeless tobacco (khaini) extracts modulate gene expression in epithelial cell culture from an oral hyperplasia

Smokeless tobacco (ST) usage is a growing public health problem worldwide. Exposure to smokeless tobacco is carcinogenic to humans. The molecular mechanism(s) underlying ST associated oral carcinogenesis remain largely unknown. The major challenge is to identify the key factor(s) involved in malignant transformation of oral lesions. Knowledge of these factors will provide candidate diagnostic biomarkers and targets for early intervention. To identify the molecular targets in ST associated oral lesions, we established and purified cultures of epithelial cells (AMOL-III) from an oral leukoplakia with histological evidence of hyperplasia with hyperkeratosis from gingivo-buccal sulcus of a smokeless tobacco (khaini) consumer. Cell cultures were characterized and modulation of gene expression in response to smokeless tobacco extract (STE) was investigated using confocal microscopy and immunoblotting. AMOL-III cells showed altered expression of cell cycle regulators namely p53, p21waf1/cip1, hdm2, proliferation marker Ki67 and transcription factor Ets-1. These cells did not harbor HPV 16/18. No mutation was detected in H-Ras codon 12/13 or in p53 exons 5-9 in AMOL-III cells. STE treatment of these cells resulted in loss of pRb, RARbeta, p21 waf1/cip1 and O6-methyl guanine-DNA methyl transferase (MGMT) while the expression of cyclin D1 was increased. To our knowledge this is the first report to demonstrate that khaini modulates expression of multiple cellular targets including proteins involved in cell cycle regulation and DNA methylation, which may lead the oral epithelial cells down the carcinogenic pathway. This in vitro model system assumes importance in unraveling the cellular and molecular mechanisms implicated in smokeless tobacco associated early oral cancer progression.

Differential effects of cigarette smoke extracts on cell proliferation in gastric and colon cells

Substantial evidence show a higher incidence of gastric cancer in smokers than nonsmokers and that cigarette smoking is highly associated with colon cancer. The present study was designed to examine the effect of cigarette smoke extracts on gastric and colon cancer cell proliferation, which is important for tumor growth. Two different cell lines were used. One was gastric cancer cell line AGS, and the other was colon cancer cell line HT-29. It was found that cigarette smoke extracts stimulated cell proliferation and c-myc expression in AGS cells. Furthermore, this proliferative action was partially blocked by the c-myc antisense. However, the extracts significantly inhibited HT-29 cell proliferation and suppressed c-myc expression. In conclusion, cigarette smoke extracts stimulated AGS cell proliferation, while inhibiting HT-29 proliferation, which were partially mediated by a c-myc-related pathway. The former action may play a contributory role in the carcinogenic action of cigarette smoking in the stomach.

Pemphigus vulgaris: environmental factors. Occupational, behavioral, medical, and qualitative food frequency questionnaire

BACKGROUND

There have been reports suggesting the involvement of environmental factors in the disease process of pemphigus. Factors suggested include exposure to pesticides or certain drugs.

OBJECTIVE

To analyze the association of pemphigus with environmental exposure to various agents, including smoking, recreational and occupational insults, drugs, and food.

DESIGN AND SETTING

In-person interviews of pemphigus patients and control subjects were conducted by trained medical investigators using a structured questionnaire. Questions included occupational, behavioral, medical, and qualitative food frequency details. The multicenter study was conducted at outpatient services of teaching hospitals in Bulgaria, Brazil, India, Israel, Italy, Spain, and the USA.

PARTICIPANTS

A total of 126 pemphigus patients (55 men, 71 women; age, 54 +/- 17 years) and 173 healthy controls (87 men, 86 women; age 50 +/- 19 years) were interviewed in the period between October 1, 1999 and March 31, 2000. The diagnosis of pemphigus was based on clinical, histologic, immunohistologic, and immunohistochemical criteria. The disease duration was 2-27 years (8.4 +/- 7.2 years). Individuals with skin diseases other than pemphigus were selected as control subjects.

MAIN OUTCOME MEASURE

Information on drugs, foods, and occupational, environmental, constitutional, and other possible risk factors was analyzed by t-tests and chi-squared tests as applicable. A multivariate logistic regression model was applied to the data to study simultaneously the independent relationship between each risk factor and pemphigus vulgaris.

RESULTS

The risk for pemphigus vulgaris was lower for ex-smokers and current smokers than for patients who had never smoked. Exposure to pesticides and occupational exposure to metal vapor were associated with an increased risk of pemphigus. Pemphigus patients had more pregnancies than controls. There were differences in environmental factors between countries, with exposure to gardening materials and pesticides being highest among patients from Bulgaria, followed by Israel. Disease characteristics also exhibited differences between countries. Bulgarian patients less frequently had oral mucous membrane lesions: 66% compared to 92% for Israeli patients and 83% for Italians. The distribution of the disease in skin and mucous membranes was similar among patients from all countries. Exclusive skin involvement was seen in 50% of patients, mucous membranes alone in 23% of patients, and both skin and mucous membranes in 27% of patients.

CONCLUSIONS

The beneficial effect of smoking on pemphigus might be explained by its effect on the immune system. In addition, smoking has an antiestrogenic effect, while pesticides have an estrogenic effect. The lower numbers of smokers among patients, the higher exposure rates to pesticides, and the higher number of female patients who had been pregnant may point to the contribution of estrogens to the disease process. It remains to be determined whether measures, such as avoiding exposure to pesticides or metal vapor, may be beneficial in the clinical context. As the present study was a survey, more definitive studies should be conducted to validate the results.

In vitro effects of smokeless tobacco extract on tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) production, and on lymphocyte proliferation

The use of smokeless tobacco (moist snuff) products is associated with mucosal lesions, gingival recession, attachment loss, and oral cancer. Despite numerous reports on the general toxic effects of smokeless tobacco extract, little information is available regarding the specific effects of smokeless tobacco on immune response. Inflammatory cytokines released as a result of smokeless tobacco-induced irritation may play a role in the development of oral mucosal lesions at habitual tobacco placement sites in smokeless tobacco users. Consequently, the purpose of this study was to determine whether an aqueous extract of smokeless tobacco (STE) affects the secretion of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and the proliferation of lymphocytes. A macrophage cell line (J774-A1) was used to measure the effects of STE on tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) secretion. Mouse splenocytes were used to assess the effects of STE on lymphocyte proliferation. We found that STE at low concentrations enhanced the production of both TNF-alpha and IL-1beta. Furthermore, STE at similar concentrations enhanced mitogen-induced murine splenocyte proliferation. Overall, these data suggest that smokeless tobacco upregulated two key proinflammatory cytokines and also induces lymphocyte proliferation.

Recovery from 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced immunosuppression in A/J mice by treatment with nonsteroidal anti-inflammatory drugs

BACKGROUND

We have previously reported that nonsteroidal anti-inflammatory drugs inhibit lung tumorigenesis induced by the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in mice.

PURPOSE

The aims of this study were to determine if NNK suppresses humoral (i.e., antibody) and cellular immune responses in mice and if nonsteroidal anti-inflammatory drugs could attenuate these immune responses.

METHODS

Female A/J mice (7-8 weeks old) were fed nonsteroidal anti-inflammatory drugs starting 2 weeks before the beginning of NNK treatment (9.1 mg per mouse in total) and continuing through the 7 weeks of NNK treatment. Eight groups (two control groups and six experimental groups) of 10 mice each were used per experiment. Animals in the two control groups received the same diet and water as animals in the six experimental groups; one control group received no nonsteroidal anti-inflammatory drugs or NNK and the other control group received only NNK. The primary humoral and cellular immune responses to the various treatments were assayed by the plaque-forming cell technique and by measurement of natural killer cell cytotoxic activity, respectively. At the end of each experiment, the animals were killed, blood was collected, plasma was prepared, and levels of the immune system modulator prostaglandin E2 were measured.

RESULTS

NNK treatment inhibited the plaque-forming cell response by approximately 50%; this inhibition was attenuated by treatment with sulindac or acetylsalicylic acid (P = .0001 for both). In contrast, treatment with naproxen, which had no chemopreventive (i.e., tumor inhibitory) efficacy, further increased by 26% (P = .05) the immunosuppressive effect of NNK. The cytotoxic activity of splenic natural killer cells against YAC-1 cells was reduced by 60% (P = .002); treatment with acetylsalicylic acid (254 mg/kg of diet) reduced the NNK-induced natural killer cell cytotoxicity inhibition by 50% (P = .02), whereas the administration of the specific cyclooxygenase-2 inhibitor NS-398 (7 mg/kg of diet) resulted in an almost complete recovery (approximately 95%, P = .04) of natural killer cell activity. The prostaglandin E2 plasma concentration was approximately 100% greater in NNK-treated mice than in untreated mice. Treatment of the mice with nonsteroidal anti-inflammatory drugs attenuated this elevation (from approximately 25% to 100%), and NS-398 (7 mg/kg of diet) was the most effective (100%).

CONCLUSIONS AND IMPLICATIONS

The ability of various nonsteroidal anti-inflammatory drugs to inhibit NNK-induced carcinogenesis appears to be directly related to the ability of these drugs to inhibit NNK-induced immunosuppression. Our results suggest that the chemopreventive effect of nonsteroidal anti-inflammatory drugs may be mediated through the modulation of prostaglandin E2 synthesis.

ATSDR evaluation of health effects of chemicals. IV. Polycyclic aromatic hydrocarbons (PAHs): understanding a complex problem

Polycyclic Aromatic Hydrocarbons (PAHs) are a group of chemicals that are formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances, such as tobacco and charbroiled meat. There are more than 100 PAHs. PAHs generally occur as complex mixtures (for example, as part of products such as soot), not as single compounds. PAHs are found throughout the environment in the air, water, and soil. As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals, including PAHs (ATSDR, 1995), found at facilities on the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) and which pose the most significant potential threat to human health, as determined by ATSDR and the Environmental Protection Agency (EPA). These profiles include information on health effects of chemicals from different routes and durations of exposure, their potential for exposure, regulations and advisories, and the adequacy of the existing database. Assessing the health effects of PAHs is a major challenge because environmental exposures to these chemicals are usually to complex mixtures of PAHs with other chemicals. The biological consequences of human exposure to mixtures of PAHs depend on the toxicity, carcinogenic and noncarcinogenic, of the individual components of the mixture, the types of interactions among them, and confounding factors that are not thoroughly understood. Also identified are components of exposure and health effects research needed on PAHs that will allow estimation of realistic human health risks posed by exposures to PAHs. The exposure assessment component of research should focus on (1) development of reliable analytical methods for the determination of bioavailable PAHs following ingestion, (2) estimation of bioavailable PAHs from environmental media, particularly the determination of particle-bound PAHs, (3) data on ambient levels of PAHs metabolites in tissues/fluids of control populations, and (4) the need for a critical evaluation of current levels of PAHs found in environmental media including data from hazardous waste sites. The health effects component should focus on obtaining information on (1) the health effects of mixtures of PAHs particularly their noncarcinogenic effects in humans, and (2) their toxicokinetics. This report provides excerpts from the toxicological profile of PAHs (ATSDR, 1995) that contains more detailed information.

Effects of in vivo treatments of nicotine and benzo[a]pyrene on the epidermal growth factor receptor in hamster buccal pouch

This study was conducted to investigate the effects of two major ingredients in cigarette smoke, benzo-alpha-pyrene (BP) and nicotine (Nic), on epidermal growth factor (EGF) receptor in hamster buccal pouch. Adult male Syrian hamsters were treated by apically swabbing the buccal pouch with mineral oil (Control), 0.5 microgram/ml of BP, Nic or BP+Nic in mineral oil, twice a day, 5 days a week for 4 weeks. The BP+Nic treatment resulted in a significant reduction of submandibular gland (SG) EGF (Control vs. BP+Nic, 6.93 +/- 1.31 vs. 4.77 +/- 0.26* ng/g wet tissue, mean +/- S.D., n=5,*P < 0.05). Treatment with BP or Nic also caused a reduction, although not statistically significant, of EGF in SG extract. For the receptor study, all treatments significantly increased [125I]EGF binding to membrane preparations of buccal pouch as compared to Control (Control, BP, Nic, BP+Nic; 12.2 +/- 0.9, 20.5 +/- 2.2*, 17.0 +/- 1.3*, 21.2 +/= 1.6* fmol/mg prot. (mean +/- S.E.M.), n=5, P < 0.05). Scatchard analysis revealed that the higher EGF binding to the BP+Nic-treated sample was due to the higher number of receptors, but not higher affinity. Data from protein kinase study indicate that EGF stimulated phosphorylation of 170- and 150-kDa proteins in buccal membrane preparations. Treatment of BP+Nic resulted in reductions in EGF-stimulated phosphorylation of 170- and 150-kDa proteins by 19 and 72%, respectively. The present study has established an animal model which will benefit investigation of the mechanism by which tobacco alters the EGF receptor in oral buccal mucosa.

Immune function in cigarette smokers who quit smoking for 31 days

A group of 28 healthy, white, male, light-to-moderate smokers, 21 to 35 years of age, were offered a financial inducement to abstain from smoking for 31 days. A matched control group of 11 smokers were paid to continue smoking during the same period. Nonspecific parameters of immune system function were monitored before and at various times after smoking abstinence. Abstinence increased natural killer cell cytotoxic activity but did not alter mitogen-induced T-lymphocyte proliferation as measured by responses to concanavalin A or phytohemagglutinin. Serum cortisol concentrations also decreased after smoking cessation; however, changes in immune function were not correlated with serum cortisol change, nor with indices of smoking such as plasma nicotine and cotinine levels. Responses to concanavalin A and phytohemagglutinin were positively correlated with change in self-reported alcohol ingestion during smoking abstinence. Results indicate that elevation in natural kill cell cytotoxic activity is detectable within 1 month of smoking cessation, even in light-to-moderate smokers. However, elevation in natural killer cell cytotoxic activity appears not to be directly related to cessation-induced reductions in plasma nicotine, cotinine, or circulating cortisol levels.

Benzo[a]pyrene and nicotine impair epidermal growth factor mediated cellular functions of buccal mucosa

This study investigated the effect of two major ingredients in cigarette smoke, benzo[a]pyrene (BP) and nicotine, on epidermal growth factor (EGF) receptor binding and EGF-mediated cellular functions in rat buccal mucosa. Rat buccal tissue was incubated in DMEM in the absence (control) and presence of 10 microM BP or nicotine for 2.5 h at 25 degrees C. There were no significant differences in [125I]EGF binding to the buccal mucosal membranes between the control and treatment groups. Protein tyrosine kinase assay showed that EGF stimulated phosphorylation of a 170-kDa protein band in the controls, but not in the BP- and nicotine-treated samples. The basal [3H]thymidine incorporations were not significantly different between the groups. Nevertheless, addition of 5 nM EGF increased [3H]thymidine incorporation by 22% in the control, but not in the BP- or nicotine-treated group. The results demonstrate that BP and nicotine change the buccal mucosal functions associated with alteration of EGF receptor.

Effects of smoking on benzo(alpha)pyrene- and glutathione-metabolizing enzymes in human lung tissue

The influence of smoking on the metabolism of benzo(alpha)pyrene and glutathione was investigated in 190 patients with primary bronchial carcinoma and 20 patients with benign lung diseases. There were no significant differences in the activities of drug-metabolizing enzymes in the lung tissue of smokers, regardless of whether they smoked low- or high-tar and -nicotine cigarettes; former smokers; or nonsmokers; nor were there such differences between female and male patients. No significant differences existed between patients with squamous cell carcinoma and those with adenocarcinoma. Impaired detoxification due to decreased activity of glutathione S-transferases, rather induction of benzo(alpha)pyrene-metabolizing enzymes, may disturb the delicate balance between the generation and detoxification of reactive metabolites. This impairment may lead to the accumulation of these compounds in the cell.