Nicotine effects on PGE2 and IL-1β release by LPS-treated human monocytes

Cigarette smoking is a major risk factor in the development and further progression of periodontitis. However, little is known regarding the pathogenesis of smoking-related periodontal diseases. The purpose of this study was to examine the effects of nicotine, alone and in combination with lipopolysaccharide (LPS), on monocyte secretion of bone-resorbing factors, PGE₂ and IL-1β. Peripheral blood monocytes (PBM) were isolated by counterflow centrifugal elutriation from 15 healthy, non-smoking donors. PBM were incubated for 24 h in RPMI 1640 containing nicotine (0, 50 μg/ml, I μg/ml, 10 μg/ml and 100 μg/ml) with or without 10 μg/ml Porphyromonas gingivalis LPS or Escherichia coli LPS. Culture supernatants were assayed for PGE₂ and IL-1β by ELISA. None of the nicotine preparations resulted in significant PBM secretion of PGE₂ and IL-1β above that of unstimulated cultures. However, PGE₂ release was potentiated 1.7-fold by the combination of P. gingivalis LPS and 10 μg/ml nicotine relative to P. gingivalis LPS alone (p<0.05, one-way ANOVA). Prostaglandin E₃ release also was potentiated 3.5-fold by P. gingivalis LPS and 100 μg/ml nicotine relative to P. gingivalis LPS alone (p<0.00001, one-way ANOVA) and 3.1-fold by E. coli LPS and 100 μg/ml nicotine relative to E. coli LPS alone (p<0.00001, I. one-way ANOVA). IL-1β secretion was lower for either LPS plus 100 μg/ml nicotine relative to LPS alone, although not significantly. These data demonstrate upregulation of LPS-mediated monocyte secretion of PGE₂ by nicotine and suggest a potential role for nicotine in periodontal disease pathogenesis.     

Metabolism of vitamin E acetate by reconstituted human gingival and buccal epithelium

Aim : To demonstrate metabolism of vitamin E acetate to vitamin E by human gingival and buccal reconstituted epithelial cell cultures. Method : Human gingival and buccal reconstituted epithelial cell cultures (SkinEthic, France) were exposed to vitamin E acetate and maintained for up to seven days at 37°C (5% CO₂) in a humidified incubator. Following organic extraction of the cultures, reverse phase HPLC was used to analyse the quantities of vitamin E and vitamin E acetate in the cultures. Results : The ratio of vitamin E to vitamin E acetate increased up to 30 fold more than the solution control in gingival cultures after 7 days. Conclusion : This paper demonstrates that human gingival and buccal epithelial cells can metabolise vitamin E acetate to vitamin E, thus delivering the more active vitamin E species under the control of the activity of endogenous host enzymes.     

Prostaglandin E2 and interleukin-1 levels in smokeless tobacco-induced oral mucosal lesions

Inflammatory mediators released as a result of smokeless tobacco (ST)-induced irritation may play a role in the development of oral mucosal lesions at habitual tobacco placement sites in ST users. The present study examined levels of interleukin-1 (IL-1) and prostaglandin E2 (PGE2) in ST-induced mucosal lesions and compared these to mediator levels in clinically normal mucosa. Soft tissue biopsies were obtained from white mucosal lesions at habitual placement sites and normal alveolar mucosal tissue at non-placement sites in 18 ST users. Fifteen non-tobacco using subjects also provided normal alveolar mucosal biopsies. IL-1 and PGE2 were recovered from the specimens, and mediator levels were determined by enzyme immunoassay. Prostaglandin E2 levels (pg/mg) were lower in both regions in the ST subjects, but values did not vary significantly between the regions with 2.77±0.72 and 2.86±0.99 at placement and non-placement sites, respectively, in ST users and 7.31±3.84 in non-tobacco users. Both IL-1α and IL-lβ (pg/mg) were significantly (p < 0.0I) elevated in ST lesions (IL-lã=25.56±4.00; IL-1β=7.76±1.68) compared to either non-placement sites in ST users (IL-lα=14.64±2.65; IL-lβ=1.63±0.72) or non-tobacco users (IL-lα=12.84±2.60; IL-lβ=2.04±0.75). In view of IL-l's role in keratinocyte proliferation and its inflammatory effects, this cytokine may contribute to mucosal and gingival alterations observed in ST users.     

器官培养中骨吸收因子的相互作用

为了研究不同浓度脂多糖（ｌｉｐｏｐｏｌｙｓａｃｃｈａｒｉｄｅ，ＬＰＳ）、脂磷壁酸（ｌｉｐｏｔｅｉｃｈｏｉｃａｃｉｄ，ＬＴＡ）、肿瘤坏死因子（ｔｕｍｏｕｒｎｅｃｒｏｓｉｓｆａｃｔｏｒ，ＴＮＦ）及前列腺素Ｅ（ｐｒｏｓｔａｇｌａｎｄｉｎＥ，ＰＧＥ）的骨吸收作用和相互作用，采用４５Ｃａ标记的１９天胚胎鼠长骨干器官培养，用样品道比法定量分析。结果表明，上述因子均能在器官培养水平刺激骨吸收，与对照组相比差异有显著性（Ｐ＜０．０５）。低浓度的ＬＰＳ与ＴＮＦ、ＬＰＳ与ＰＧＥ、ＴＮＦ与ＰＧＥ相互作用，超过各因子单独作用之和（期望值）；ＬＰＳ与ＬＴＡ、ＴＮＦ与ＬＴＡ相互作用，等于期望值；而ＬＴＡ与ＰＧＥ相互作用，小于期望值。研究结果提示，多种骨吸收因子的相互作用在牙周病骨吸收发病机理中有重要意义。     

Influence of proinflammatory cytokines on Actinobacillus actinomycetemcomitans specific IgG responses

OBJECTIVE: High levels of serum anti-Actinobacillus actinomycetemcomitans immunoglobulin G (IgG) correlate with reduced extent and severity of periodontal disease and the present study was undertaken to begin testing the hypothesis that proinflammatory cytokines are important in the induction of optimal anti-A. actinomycetemcomitans IgG responses. BACKGROUND: Studies with pokeweed mitogen indicate that interleukin-1alpha (IL-1alpha) and IL-1beta are necessary for optimal IgG1 and IgG2 production and that prostaglandin E(2) (PGE(2)) and interferon-gamma (IFN-gamma) selectively promote IgG2, which is a major component of the anti-A. actinomycetemcomitans response in vivo. The pokeweed mitogen results suggest that these proinflammatory cytokines would also be necessary for optimal production of IgG specific for A. actinomycetemcomitans. METHODS: Peripheral blood mononuclear cells from A. actinomycetemcomitans-seropositive subjects with localized aggressive periodontitis were stimulated with A. actinomycetemcomitans in immune complexes capable of binding follicular dendritic cells that participate in the induction of recall responses in vivo. Cultures were manipulated with anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21, indomethacin, and PGE(2). Actinobacillus actinomycetemcomitans specific IgG production was monitored by enzyme-linked immunosorbent assay (ELISA). RESULTS: Addition of follicular dendritic cells to peripheral blood mononuclear cells cultures resulted in follicular dendritic cell-lymphocyte clusters and increased anti-A. actinomycetemcomitans IgG responses (3-40-fold increases) compared with controls lacking follicular dendritic cells. Anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21 and indomethacin suppressed anti-A. actinomycetemcomitans IgG production by half or more. PGE(2) restored IgG responses suppressed by indomethacin. CONCLUSIONS: The cytokines IL-1alpha, IL-1beta, IFN-gamma, IL-12, and PGE(2) were all necessary for optimal production of human anti-A. actinomycetemcomitans and the need for proinflammatory cytokines including the T helper 1 (Th1) cytokines is consistent with a response with a significant IgG2 component.     

Role of gene E2f1 in susceptibility to bacterial adherence of oral streptococci to tooth surfaces in mice

Dental plaque is composed of a biofilm community of microorganisms on teeth that coats the oral cavity, including attaching to the teeth, and provides a protective reservoir for oral microbial pathogens, which are the primary cause of persistent and chronic infectious diseases. Oral streptococci are pioneering organisms that play an important role in biofilm formation on tooth surfaces as well as being primary causative agents of dental caries. The purpose of this study was to clarify the role of the E2f1 gene in susceptibility to dry mouth and bacterial adherence of oral streptococci to tooth surfaces in animal model experiments. A mutation of the E2f1 gene in mice is known to cause enhanced T-lymphocyte proliferation, leading to testicular atrophy, splenomegaly, salivary gland dysplasia, and other systemic and organ-specific autoimmunity. We found a decreased volume of saliva production and protein production rate, along with increased amylase activity, IgA concentration, and mucin 1 concentration in E2F-1(-/-) mice as compared with the control C57BL/6 mice. Further, we quantified the recolonization of oral streptococci in E2F-1(-/-) mice and found that a higher number of some oral streptococci were colonized on the teeth of these mice. In particular, following oral ingestion of 1% sucrose in water, the colonization of Streptococcus mutans increased in comparison with other streptococci. Our results suggest that the E2f1 gene may affect susceptibility for oral biofilm formation by streptococci in humans with dry mouth.