Effects of areca nut extracts on the functions of human neutrophils in vitro

BactericidalActivity of Crevicular Polymorphonuclear Neutrophils in Chronic Periodontitis Patients and Healthy Subjects under the Influence of Areca Nut Extract: An In Vitro Study

Arecanutchewing is an established risk factor for oral submucous fibrosis (OSMF), but its role in periodontal disease has not yet been defined. Thisstudy aimed to assess the effect of areca nut extracts (ANE) on the bactericidal activity of crevicular polymorphonuclear neutrophils (cPMNs) in healthy subjects and chronic periodontitis (CP) patients. An in vitro study was designed with an equal number of (n = 30) gingival crevicular fluid (GCF) samples collected from CP patients and healthy subjects. Bactericidal activity and hydrogen peroxide (H2O2) assays were performed with the GCF samples pre-treated with extracts of two varieties of areca nut: ripe and tender. Simultaneously, controls were also carried out with Hank’s balanced salt solution (HBSS) and catechin. Independent t-test and one-way analysis of variance (ANOVA), along with post-hoc analysis, were employed for statistical analysis. In both study groups, a significant reduction (p < 0.01)in the bactericidal activity was noted when the samples treated with the ripe areca nut (rANE) were compared with the tender variant (tANE). Similarly, H2O2 levels were significantly reduced (p < 0.001) in the rANE in contrast to tANE for both study groups. The above results were significant within the group but were found to be non-significant between the study groups, except when it was treated with HBSS (p < 0.001). In the present study, it was found that there was a reduction in the bactericidal activity and H2O2 production of cPMNs in both healthy subjects and CP patients in the presence of areca nut extract. Moreover, the effect of rANE on cPMNs was more detrimental than tANE.

Association of Helicobacter pylori with oral potentially malignant disorders and oral squamous cell carcinoma-a systematic review and meta-analysis

OBJECTIVE

To assess any potential association between Helicobacter pylori and oral squamous cell carcinoma/oral potentially malignant disorders.

MATERIALS AND METHODS

Data mining was done using PubMed, Cochrane Library, and SCOPUS databases. The search included articles published up to May 2019. Newcastle-Ottawa scale was used to score the quality of the included articles. Data including the type of study, the sample population, the type of oral lesion, and the resulting statistical data were extracted.

RESULTS

Out of 131 screened articles, only 15 articles fulfilled the eligibility criteria. Among the 15 studies, 9 focused on oral squamous cell carcinoma and 6 focused on oral potentially malignant disorders. Eight out of the 9 oral squamous cell carcinoma studies were included in the meta-analysis. Forest plot was generated using the odds ratio and confidence intervals calculated for each of the included studies. Due to the lack of sufficient studies, the meta-analysis was not performed for oral potentially malignant disorders.

CONCLUSION

Due to the contradictory results of the included studies, it was not possible to make any conclusive statement on the potential association of H. pylori with oral squamous cell carcinoma. The variations in the methodology, especially the differences in the sensitivity/specificity of the diagnostic modalities could be the cause for differential results.

CLINICAL RELEVANCE

Although the association of H. pylori with oral squamous cell carcinoma could not be confirmed, it is vital to reduce the excess oral microbial load, especially in patients exhibiting oral mucosal changes with no history of associated risk factors.

Arecoline inhibits intermediate-conductance calcium-activated potassium channels in human glioblastoma cell lines

Arecoline (ARE) is an alkaloid-type natural product from areca nut. This compound has numerous pharmacological and toxicological effects. Whether this agent interacts with ion channels to perturb functional activity of cells remains unknown. The effects of ARE on ionic currents were studied in glioma cell lines (U373 and U87MG) using patch-clamp technique. Like TRAM-34(1-[(2-chlorophenyl)-diphenylmethyl]pyrazole), ARE suppressed the amplitude of whole-cell voltage-gated K(+) currents in U373 cells elicited by a ramp voltage clamp. In cell-attached configuration, ARE did not modify the single-channel conductance of intermediate-conductance Ca(2+)-activated K(+) (IKCa) channels; however, it did reduce channel activity. Its inhibition of IKCa channels was accompanied by a significant lengthening in the slow component of mean closed time of IKCa channels. Based on minimal kinetic scheme, the dissociation constant (KD) required for ARE-mediated prolongation of mean closed time was 11.2µM. ARE-induced inhibition of IKCa channels was voltage-dependent. Inability of ARE to perturb the activity of large-conductance Ca(2+)-activated K(+) (BKCa) channels was seen. Under current-clamp recordings, ARE depolarized the membrane of U373 cells and DCEBIO reversed ARE-induced depolarization. Similarly, ARE suppressed IKCa-channel activities in oral keratinocytes. This study provides the evidence that ARE block IKCa channels in a concentration, voltage and state-dependent manner. ARE-induced block of IKCa channels is unrelated to the binding of muscarinic receptors. The effects of ARE on these channels may partially be responsible for the underlying cellular mechanisms by which it influences the functional activities of glioma cells or oral keratinocytes, if similar findings occur in vivo.

Inhibitory effects of areca nut extract on expression of complement receptors and fc receptors in human neutrophils

BACKGROUND

Chewing of areca quid increases the prevalence of periodontal diseases. Areca nut extract (ANE) inhibits the phagocytic activity of human neutrophils. This in vitro study investigates the effects of ANE on complement- and antibody-opsonized phagocytosis by neutrophils. Expression of complement receptors, Fc receptors, and F-actin in ANE-treated neutrophils is also analyzed.

METHODS

The viability of ANE-treated neutrophils was determined using the propidium iodide staining method. The possible effects of ANE on the expression of complement receptors and Fc receptors were examined using an immunofluorescence staining method followed by flow cytometry and confocal laser scanning microscopy. The phagocytic activity of neutrophils against complement or immunoglobulin (Ig)G-opsonized fluorescent beads was analyzed using flow cytometry. Expression of F-actin was determined using confocal laser scanning microscopy.

RESULTS

ANE significantly inhibited the production of complement receptors (CR1, CR3, and CR4) and Fc receptors (FcγRII and FcγRIII) in a concentration-dependent manner. Treatment of neutrophils with ANE significantly impaired their ability to phagocytose fluorescent beads. ANE also inhibited phagocytosis of fluorescent beads that were opsonized by complement or IgG. Moreover, expression of F-actin was inhibited after ANE treatment.

CONCLUSIONS

ANE inhibits the complement- and IgG-mediated neutrophil phagocytosis that may result from reduction of the expression of complement receptors, Fc receptors, and F-actin formation after ANE treatment. The findings suggest that areca nut chewing may jeopardize the defensive functions of neutrophils and affect periodontal health.

Effects of Areca Nut Extracts on Phagocytosis of Actinobacillus actinomycete mcomitans ATCC 33384 by Neutrophils in Patients with Chronic Periondontitis

BACKGROUND & OBJECTIVE

A higher prevalence of periodontal disease among areca nut chewers than non chewers has been demonstrated. Neutrophils, the first line of defence mechanism against microbial infection play an important role in maintaining the periodontal health. In this context our aim was to evaluate the effects of areca nut extracts on phagocytic activity by neutrophils isolated from gingival crevicular washing of healthy subjects and patients with chronic periodontitis.

MATERIAL AND METHODS

Sample size consisted of a total of 60 subjects which were divided into two groups of 30 each. Group I consisted healthy subjects and Group II consisted clinically diagnosed cases of chronic periodontitis. Neutrophils isolated from gingival crevicular washings of both groups were treated with aqueous extracts of ripe areca nut (rANE) and tender areca nut (tANE) and examined for their effect on cellular viability of neutrophils using typan blue exclusion assay. The possible/ ableffects on the phagocytic activity of neutrophils against a periodontal pathogen Aggregatibacter actinomycetemcomitans(ATCC 33384) was determined by using microscopic method.

RESULTS

Both rANE and tANE affected the phagocytic activity by neutrophils in healthy and patients with chronic periodontitis. Ripe areca nut extract has altered the neutrophil functions more than tender areca nut in both the groups. There was no difference seen in the cell viability of neutrophils when treated with rANE and tANE in both the groups (p> 0.05).

CONCLUSION

Both ripe and tender arecanut extract affected the neutrophil function in healthy and patients with chronic periodontitis. Ripe arecanut extract significantly altered the neutrophils functions more than tender areca nut extract. Thus, alterations in these functions of neutrophils may lead to signs of clinical diseases associated with areca chewing.

Inhibitory effects of safrole on phagocytosis, intracellular reactive oxygen species, and the activity of myeloperoxidase released by human polymorphonuclear leukocytes

BACKGROUND

Safrole, a component of Piper betle inflorescence, inhibits bactericidal activity and the release of superoxide anion (O(2)(-)) by polymorphonuclear leukocytes (PMNs). This in vitro study further investigated the effects of safrole on phagocytic activity, the intracellular production of reactive oxygen species (ROS), and the activity of the lysosomal enzyme myeloperoxidase (MPO), which is released by human PMNs.

METHODS

The possible effects of safrole on the phagocytic activity of PMNs against Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) were determined using flow cytometry. PMNs were treated with various concentrations of safrole, which was followed by treatment with Hanks balanced salt solution with or without cytochalasin B and fMet-Leu-Phe (CB/fMLP). Intracellular ROS was determined using 2',7'-dichlorofluorescein diacetate and a fluorometer, whereas MPO activity was determined using a substrate assay.

RESULTS

Safrole significantly inhibited the phagocytic activity of PMNs in a dose-dependent manner. Approximately 50% of the phagocytic activity of PMNs was affected when 10 mM safrole was used. Exposure of the PMNs to safrole (up to 5 mM) did not directly affect the intracellular levels of ROS and the extracellular activity of MPO. However, the ability of CB/fMLP to trigger production of intracellular ROS and the activity of MPO released by human PMNs was significantly suppressed by safrole.

CONCLUSIONS

Safrole reduced the uptake of A. actinomycetemcomitans by human PMNs. Safrole also impaired the normal activation activity of PMNs. Alterations in the defensive properties of PMNs by safrole might promote bacterial colonization, and this could result in periodontal infection.

Presence of Helicobacter pylori in betel chewers and non betel chewers with and without oral cancers

BACKGROUND

Betel chewing has been shown to predispose to periodontal disease and oral cancer. Studies show that people with gum disease are more likely to test positive for Helicobacter pylori (H. pylori). It is not known if the lesions produced by betel quid and the resulting, chemical changes predispose to colonization by H. pylori. Further the role of this organism in oral cancer is not known. Our objective was to determine the presence of H. pylori in oral lesions of thirty oral cancer patients and to determine the presence of IgG antibodies to H. pylori in oral cancer patients who are betel chewers and non betel chewers, healthy betel chewers and healthy non-betel chewers and to compare the presence of H. pylori in these four groups. This case control study was conducted at the Cancer Institute Maharagama and the Department of Microbiology, Faculty of Medical Sciences, University of Sri Jayewardenepura.

METHODS

One hundred and seventy three subjects, of whom fifty three were patients presenting with oral cancer to the Cancer Institute Maharagama, sixty healthy betel chewers and sixty healthy non-betel chewers from the Religious and Welfare Service Centre Maharagama were tested for H. pylori by serology. Thirty oral biopsies from oral cancer patients were cultured under microaerophilic condition to isolate H. pylori. The statistic used was Chi-square test.

RESULTS

Of the fifty-three oral cancer patients, forty-four were betel chewers. Among the 53 oral cancer patients examined, ten of forty-four (10/44 = 22.7%) patients who are betel chewers and four of nine (4/9 = 44.4%) patients who are non-betel chewers were detected positive for IgG antibody against H. pylori. In the healthy group (betel chewers and non betel chewers) ten (16.7%) of the healthy betel chewers tested positive for H. pylori by serology. None of the healthy non-betel chewers tested positive for H. pyloriFourteen [26.4%] of oral cancer patients tested positive for H. pylori by serology, of which two were also culture positive (Only thirty samples were cultured). The presence of H. pylori in betel chewers (with or without cancer) compared to non-betel chewers was statistically significant. (Chi-square test p < 0.05) The use of tobacco and areca nut in betel chewers was significant with the presence of H. pylori (p < 0.05).

CONCLUSION

There is a significant higher proportion of H. pylori in betel chewers compared to non-betel chewers but not between oral cancer patients compared to patients without oral cancer. Hence Betel chewing may predispose to colonisation with H. pylori in the digestive tract through swallowing the quid or during betel chewing.

Areca nut extracts-activated secretion of leukotriene B4, and phosphorylation of p38 mitogen-activated protein kinase and elevated intracellular calcium concentrations in human polymorphonuclear leukocytes

BACKGROUND AND OBJECTIVE

Polymorphonuclear leukocytes are the major source of leukotriene B4, which is synthesized via the 5-lipoxygenase pathway. Activation of the 5-lipoxygenase pathway is regulated by intracellular calcium and the phosphorylation of p38 mitogen-activated protein kinase (MAPK). The impact of areca nut extracts on the biosynthesis of leukotriene B4 by human polymorphonuclear leukocytes was evaluated, and some of the possible mechanisms underlying the responses were examined.

MATERIAL AND METHODS

Polymorphonuclear leukocytes were treated with various concentrations of areca nut extracts. The concentrations of leukotriene B4 released into the supernatants were evaluated using enzyme immunoassay. The phosphorylation of p38 MAPK was monitored using immunoblotting, and the cytosolic calcium kinetics were assessed fluorometrically using Fura-2.

RESULTS

Exposure of polymorphonuclear leukocytes to areca nut extracts led to a dose-dependent increase in the production of leukotriene B4, with levels peaking at 30 min and decreasing thereafter. Areca nut extracts enhanced the phosphorylation of p38 MAPK, an enzyme known to activate 5-lipoxygenase. Incubation with areca nut extracts also resulted in a rapid elevation of intracellular calcium concentrations in polymorphonuclear leukocytes. The induction of leukotriene B4 by areca nut extracts was suppressed with the p38 MAPK inhibitor, SB203580, or with the intracellular calcium chelator, BAPTA-AM.

CONCLUSION

The interaction of areca nut extracts with polymorphonuclear leukocytes activated the arachidonic acid metabolic cascade. Incubation of polymorphonuclear leukocytes with areca nut extracts resulted in the activation of intracellular events, such as phosphorylation of p38 MAPK and Ca2+ mobilization, involved in the release of pro-inflammatory lipid mediators. The results of this study emphasize the potential importance of polymorphonuclear leukocytes as a source of leukotriene B4, which may modulate the inflammatory response in areca chewers.

Ultrastructural and hormonal changes in the pineal-testicular axis following arecoline administration in rats

Arecoline is an alkaloid of betel nut of Areca catechu. Betel nut is chewed by millions of people in the world and it causes oral and hepatic cancers in human. It has therapeutic value for the treatment of Alzheimer and schizophrenia. Arecoline has immunosuppressive, mutagenic and genotoxic effects in laboratory animals. It also affects endocrine functions. The objective of this study was to investigate the effects of arecoline on pineal-testicular axis in rats. Since pineal activity is different between day and night, the current study is undertaken in both the photophase and scotophase. The findings were evaluated by ultrastructural and hormonal studies of pineal and testicular Leydig cells, with quantitations of fructose and sialic acid of sex accessories. Arecoline treatment (10 mg/kg body weight daily for 10 days) caused suppression of pineal activity at ultrastructural level by showing dilatation of the cisternae of the rough endoplasmic reticulum (RER), large autophagosome-like bodies with swollen mitochondrial cristae, numerous lysosomes, degenerated synaptic ribbons and reduced number of synaptic-like microvesicles. Moreover, pineal and serum N-acetylserotonin and melatonin levels were decreased with increased serotonin levels in both the gland and serum. In contrast, testicular Leydig cell activity was stimulated with abundance of smooth endoplasmic reticulum (SER), electron-dense core vesicles and vacuolated secretory vesicles, and increased testosterone level in the arecoline recipients. Consequently, the testosterone target, like prostate, was ultrastructurally stimulated with abundance of RER and accumulation of secretory vesicles. Fructose and sialic acid concentrations were also significantly increased respectively in the coagulating gland and seminal vesicle. These results were more significant in the scotophase than the photophase. The findings suggest that arecoline inhibits pineal activity, but stimulates testicular function (testosterone level) and its target organs presumably via muscarinic cholinergic receptor in rats.

Areca nut extract suppresses T-cell activation and interferon-gamma production via the induction of oxidative stress

Areca quid chewing is a major risk factor associated with oral submucous fibrosis (OSF) and oral cancer. Experimental evidence indicates that immune deterioration is associated with the pathophysiology of OSF and oral cancer. In addition, reactive oxygen species (ROS) is shown to play a role in the cytotoxic and genotoxic effect induced by areca nut extracts (ANE) in oral cells. The present studies investigated the effects of ANE on T-cell reactivity and the role of ROS in ANE effects. Treatment of splenocytes with ANE induced a marked cytotoxic effect, and suppressed the production of IL-2 and IFN-gamma, whereas the production of IL-4 was unaffected. The ANE-mediated cytotoxicity, and suppression of IFN-gamma and IL-2 production were attenuated by the presence of antioxidant N-acetyl-l-cysteine (NAC). Moreover, flow cytometric analysis demonstrated an increase in cellular ROS levels in splenic T-cells treated with ANE, which was also attenuated by the presence of NAC. Concordantly, the cellular level of glutathione was diminished by ANE in splenic T-cells pretreated with NAC. Collectively, these results demonstrated that ANE markedly suppressed T-cell activation and Th1 cytokine production, which was mediated, at least in part, by the induction of oxidative stress.

Areca nut extracts reduce the intracellular reactive oxygen species and release of myeloperoxidase by human polymorphonuclear leukocytes

BACKGROUND AND OBJECTIVE

Polymorphonuclear leukocytes (PMN) represent the first line of host defense. Areca nut extract inhibits the bactericidal activity of, and the release of superoxide anion (O2- ) by, PMN. This study investigated the effects of areca nut extract on the intracellular production of reactive oxygen species (ROS) and on the extracellular release of lysosomal enzyme, myeloperoxidase (MPO), by PMN. The effects of arecoline, a principal component of areca nut, were also examined.

MATERIAL AND METHODS

Human PMN were treated with various concentrations of areca nut extract or arecoline followed by treatment with Hanks' balanced salt solution, with or without cytochalasin B and fMet-Leu-Phe (CB/fMLP). The viability of PMN was determined using propidium iodide staining and flow cytometry. The presence of intracellular ROS was determined using 2',7'-dichlorofluorescin diacetate and fluorometry. MPO release was determined using a substrate assay.

RESULTS

Areca nut extract (25 and 50 microg/ml) significantly decreased the viability of PMN. The intracellular levels of ROS and the extracellular release of MPO were induced in PMN by CB/fMLP. Exposure of PMN to areca nut extract (up to 25 microg/ml) or to arecoline (up to 2 mg/ml) did not directly affect the levels of ROS and MPO activity. However, under conditions that did not affect the viability of PMN, the ability of CB/fMLP to trigger production of intracellular ROS and release of MPO in human PMN was significantly suppressed by areca nut extract and arecoline.

CONCLUSION

Areca nut impaired the activation of PMN by CB/fMLP that might decrease the effectiveness of PMN in the host defense. Alternatively, exposure of PMN to areca nut extract could decrease the capacity of PMN to damage tissues.

Enhancing Effects of Areca Nut Extracts on the Production of Interleukin-6 and Interleukin-8 by Peripheral Blood Mononuclear Cells

BACKGROUND

The habit of chewing areca quid (AQ) has been implicated in oral pathogenesis, including periodontal disease. Little is understood about the roles of AQ in the cytokine secretion by immune cells. The study examined the effects of areca nut, the major ingredient of AQ, on the production of interleukin (IL)-6 and IL-8 by peripheral blood mononuclear cells (PBMC), the immunocompetent cells. The possible role of oxidative stress of areca nut was also examined.

METHODS

Extracts of ripe areca nut (rANE) and tender areca nut (tANE) were examined for their cytotoxic effects on human PBMC using the trypan blue exclusion test. The production of IL-6 and IL-8 by ANE-treated PBMC was analyzed using enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction. Effects of an antioxidant, pyrrolidine dithiocarbamate (PDTC), on ANE-induced cytokine secretion were also studied.

RESULTS

At the experimental conditions, 20 micro g/ml rANE decreased cell viability significantly, whereas no significant effect of tANE (< or =80 micro g/ml) was observed. Both rANE (< or =20 micro g/ml) and tANE (< or =160 micro g/ml) significantly increased the secretion of IL-6 and IL-8 by PBMC in a dose- and time-dependent manner. The altered mRNA expression of IL-6 by rANE and tANE was also observed. Moreover, the stimulating effects of rANE on cytokine expression in PBMC could be attenuated by PDTC, suggesting that the oxidative stress of rANE may play a role.

CONCLUSIONS

Markedly enhancing effects of ANE on PBMC-released inflammatory cytokines might cause a sustained cytokine-rich inflammatory milieu in oral cavity of AQ chewers. These excessive cytokines from ANE-treated immune cells may impair periodontal health.

Modulation of Phagocytosis, Chemotaxis, and Adhesion of Neutrophils by Areca Nut Extracts

BACKGROUND

A higher prevalence of periodontal diseases among areca chewers than non-areca chewers has been demonstrated. Neutrophils, representing the first line of the host defense mechanism against microbial infection, play important roles in maintaining periodontal health. This study determined the possible effects of areca nut on phagocytosis, chemotaxis, and adhesion of human neutrophils.

METHODS

Aqueous extracts of ripe areca nut without husk (rANE) and fresh and tender areca nut with husk (tANE) were examined for their effects on neutrophil phagocytosis using flow cytometry and confocal laser scanning microscopy. The effects of rANE and tANE on chemotaxis and adhesion of neutrophils to human aortic endothelial cells were examined using fluorescence-labeled neutrophils.

RESULTS

Both rANE and tANE inhibited the phagocytic activity of neutrophils in a dose-dependent manner. The levels of internalized fluorescent bacteria in neutrophils decreased after ANE treatment. However, exposure of neutrophils to rANE and tANE stimulated the chemotaxis activity of neutrophils to N-formyl-Met-Leu-Phe (fMLP) and enhanced adhesion of neutrophils to human aortic endothelial cells in a dose-dependent manner. Moreover, treatment of neutrophils with rANE was more effective than incubation with tANE.

CONCLUSIONS

Components of areca nut inhibited phagocytosis activity of neutrophils but enhanced chemotaxis and adhesion of neutrophils. Alterations in functions of neutrophils may lead to signs of clinical diseases associated with areca chewing. The components in ANEs that are responsible for these observations remain to be elucidated.

The natural history of periodontal disease in humans: risk factors for tooth loss in caries-free subjects receiving no oral health care

AIM

No long-term studies have reported on risk factors for tooth loss in subjects without home or professional dental care. The purpose of this report is to identify potential risk factors for tooth loss among male Sri Lankan tea labourers who participated in a 20-year investigation of the natural history of periodontal disease.

MATERIAL AND METHODS

Data for this report were obtained from the 455 subjects who participated in multiple examinations over the 20-year period from 1970 to 1990. Analyses included data from interim examinations in 1971, 1973, 1977, 1982 and 1985. Oral health assessments included the following: (1) attachment levels in millimetres on all mesial and mesio-buccal surfaces, excluding third molars; (2) plaque index; (3) gingival index; (4) calculus index; (5) caries index; and (6) missing teeth. Other variables included age, history of smoking and betel nut use. Statistical analyses included descriptive statistics and multivariate repeated-measures modelling with generalized estimating equations.

RESULTS

Tooth loss was significantly dependent upon interactions between the mean attachment loss and betel nut use (Z=3.40; p=0.0007) and history of missing teeth (Z=-3.70; p=0.0002). The effect of attachment loss on tooth loss was increased in the presence of betel nut and diminished when teeth were already missing at baseline.

CONCLUSION

History of missing teeth, betel nut use and increasing attachment loss were significant predictors of tooth loss over time. Betel nut use increased the effect of attachment loss on loss of teeth, while history of missing teeth diminished the effect of attachment loss on tooth loss.

Cell-mediated immunity and head and neck cancer: with special emphasis on betel quid chewing habit

Betel quid (BQ) chewing is popular in Taiwan, India, and many southeast-Asian countries. BQ chewing has strong association with the risk of oral leukoplakia (OL), oral submucous fibrosis (OSF), and oral cancer (OC). BQ components exhibit genotoxicity and may alter the structure of DNA, proteins and lipids, resulting in production of antigenicity. BQ ingredients are also shown to induce keratinocyte inflammation by stimulating the production of prostaglandins, TNF-alpha, IL-6, IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in keratinocytes. These events may provoke tissue inflammation, early cell-mediated immunity (CMI), and immune surveillance in BQ chewers. However, BQ components also directly affect the functional activities of immunocompotent cells, and moreover tumor cells may hypo-respond to the CMI via diverse mechanisms such as induction of apoptosis of lymphocytes, induction of production of suppressor T cells, downregulation of MHC molecules in tumor cells, etc. Clinically, an alteration in lymphocyte subsets, a decrease in total number of lymphocytes, and a reduction in functional activities of CMI have been observed in isolated peripheral blood mononuclear cells (PBMC) and tumor infiltrated lymphocytes (TIL) in patients with OSF, OL or OC. Adaptation of tumor cells to immune system may promote clonal selection of resistant tumor cells, leading to immune tolerance. Future studies on effects of BQ components on CMI and humoral immunity in vitro and in vivo can be helpful for chemoprevention of BQ-related oral mucosal diseases. To elucidate how virus infection, tobacco, alcohol and BQ consumption, and other environmental exposure affect the immune status of patients with oral premalignant lesions or OC will help us to understand the immunopathogenesis of OC and to develop immunotherapeutic strategies for OC.

Areca nut extracts modulated expression of alkaline phosphatase and receptor activator of nuclear factor kappaB ligand in osteoblasts

OBJECTIVES

Areca chewers have a higher prevalence of periodontal diseases than non-chewers. This study was to determine the possible effects of ripe areca nut extracts (rANE) on viability and gene expression of alkaline phosphatase (ALP), receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in human osteoblasts.

METHODS

The effects of rANE on cell viability of osteoblast-like MG63 cells were determined using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) that measures metabolic activity. Gene expression of ALP, RANKL and OPG was examined using reverse transcription-polymerase chain reaction. ALP activity and RANKL protein were further examined using substrate assay and confocal laser scanning microscopy, respectively.

RESULTS

Relative viability was reduced to approximately 50% when 25 microg/ml of rANE was used. The expression of OPG mRNA in MG63 cells was not altered by rANE. However, decreased levels of mRNA and enzyme activity of ALP were observed. Moreover, the expressions of mRNA and protein of RANKL were stimulated by rANE in a dose-dependent manner.

CONCLUSIONS

The rANE affected morphology and viability of osteoblasts. We also present novel evidence demonstrating that areca nut may compromise the periodontal health of areca chewers by suppression of ALP gene expression and elevation of RANKL gene expression in osteoblasts.

Inhibitory Effects of Areca Nut Extracts on Phagocytosis ofActinobacillus actinomycetemcomitansATCC 33384 by Neutrophils

BACKGROUND

Areca quid chewers have a higher prevalence of periodontal disease than non-chewers. Little is known about the influence of areca quid on the immune system. This study was to determine the possible effects of the areca nut on phagocytic activity of human neutrophils.

METHODS

Aqueous extracts of ripe areca nut without husk (rANE), fresh and tender areca nut with husk (tANE), a major alkaloid (arecoline), and a phenolic component ([+]-catechin) of areca nut were examined for their effects on cellular viability using trypan blue exclusion assay. The possible effects on the phagocytic activity of neutrophils against a periodontal pathogen, Actinobacillus actinomycetemcomitans ATCC 33384, were determined using flow cytometry and confocal laser scanning microscopy.

RESULTS

At the concentrations tested, rANE, tANE, arecoline, and (+)-catechin did not significantly affect viability of neutrophils. However, rANE, tANE, arecoline, and (+)-catechin inhibited the phagocytic activity of neutrophils in a dose-dependent manner. Approximately 50% of the relative phagocytic activity of neutrophils was affected when 50 microg/ml of rANE, 400 microg/ml of tANE, 20,000 microg/ml of arecoline, or 2,500 microg/ml of (+)- catechin was used. Decreased levels of internalized fluorescent bacteria were also demonstrated. However, arecoline or (+)-catechin alone could not be used to explain the inhibitory effects observed for rANE and tANE.

CONCLUSIONS

Components of areca nut reduced the uptake of A. actinomycetemcomitans ATCC 33384 by human neutrophils. The inhibition of areca nut on phagocytosis of neutrophils may be one possible mechanism by which the areca nut compromises the periodontal health of areca quid chewers.

Habitual betel quid chewing as a risk factor for cirrhosis: a case-control study

Betel quid chewing, part of traditional Taiwanese culture, is common in 10%-20% of the human population worldwide. In this case-control study we assessed the independent and interactive role of habitual betel quid chewing and chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection on risk of cirrhosis. Subjects enrolled included 210 pairs of sex- and age-matched cirrhotic patients and healthy controls. Information on risk factors was obtained through serologic examination of hepatitis B surface antigen (HBsAg) and antibodies to hepatitis C virus (anti-HCV), and a standardized personal interview with a structured questionnaire. Univariate analysis indicated that betel quid chewing, HBsAg+, anti-HCV+, alcohol drinking, and smoking are significant risk factors for cirrhosis. Multivariate analysis indicated that betel quid chewing (odds ratio [OR], 3.56), HBsAg (OR 20.37), and anti-HCV (OR 31.43) are independent risk factors for cirrhosis. Most betel quid chewers habitually drink alcohol. Although our analysis indicates that betel quid chewing acts independently from alcohol as a risk factor for cirrhosis, the confounding effect of alcohol cannot be excluded entirely by our study. There was an additive effect of the interaction between betel quid chewing and the presence of either HBsAg or anti-HCV. Moreover, a higher risk of cirrhosis was associated with longer duration of betel quid chewing and greater amount of betel quid consumed (each p for trend <0.0001). In conclusion, betel quid chewing appears to be an independent risk factor for cirrhosis. There is an additive interaction between betel quid chewing and chronic HBV/HCV infection.

Effects of safrole on the defensive functions of human neutrophils

The effects of safrole on the defensive functions of human neutrophils were examined. At the concentrations employed in this study, safrole did not significantly affect the viability of peripheral blood neutrophils as verified by their ability to exclude trypan blue dye. However, exposure of neutrophils to safrole inhibited their bactericidal activity against oral pathogens, including Actinobacillus actinomycetemcomitans and Streptococcus mutans, in a dose dependent manner. In addition, safrole inhibited the production of bactericidal superoxide anion by neutrophils as measured by cytochrome c reduction. In conclusion, the results demonstrated that safrole reduced the antibacterial activity and the superoxide anion production of neutrophils. Inhibition of the defensive functions of neutrophils may be one possible mechanism by which safrole compromises the oral health.

Association between betel quid chewing, periodontal status and periodontal pathogens

The present investigation examined whether an association exists between betel quid chewing and signs of periodontal disease and determined the prevalence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis by polymerase chain reaction. The periodontal status of 34 betel quid chewers and 32 non-betel quid chewers were compared. A significantly higher prevalence of bleeding on probing was found in betel quid chewers than non-chewers among the subjects with higher plaque level, greater gingival inflammation, deeper probing depth or greater attachment loss. Also, the results suggested that betel quid chewers may harbor higher levels of infection with A. actinomycetemcomitans and P. gingivalis than non-betel quid chewers. The association persists after adjusting for severity of the clinical parameters. In conclusion, betel quid chewing was associated with a higher prevalence of bleeding on probing where higher clinical levels of disease existed, and with a likelihood of subgingival infection with A. actinomycetemcomitans and P. gingivalis.