PD-L1 correlates with chemokines and cytokines in gingival crevicular fluid from healthy and diseased sites in subjects with periodontitis

Objective

PD-L1 is an immune checkpoint molecule that regulates immune and inflammatory responses. While cells of periodontal tissues express PD-L1, its presence in GCF is not known. The purpose of this study was to measure the PD-L1 values in GCF and correlate values with the presence of chemokine and cytokine values from periodontally diseased subjects and periodontally healthy subjects.

Results

PD-L1 values (pg/30 s), determined in triplicate using a fluorescent microparticle-based immunoassay ranged from 0.04–31.65 pg/30 s. PD-L1 correlated with 15 out of 22 chemokine and cytokine responses. In 85 healthy sites in 31 subjects, PD-L1 values were negatively correlated with IL6, CXCL8, IL10, and CCL3 values. In 53 diseased sites in 20 subjects, PD-L1 values were positively correlated with CCL11, CSF2, IFNG, IL1A, IL1B, IL2, IL7, IL15, and CCL5 values and negatively correlated with IL12A and IL5 values. Gene ontology (GO) annotations identified roles of PD-L1 in Th1 and Th2 activation and T-cell exhaustion signaling canonical pathways. PD-L1 values were correlated with the expression of chemokines and cytokines, which likely regulates immune cell trafficking and protects the periodontium from uncontrolled immune responses to pathogens and inflammation-induced tissue damage.

Periodontal health and gingival diseases and conditions on an intact and a reduced periodontium: Consensus report of workgroup 1 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions

Periodontal health is defined by absence of clinically detectable inflammation. There is a biological level of immune surveillance that is consistent with clinical gingival health and homeostasis. Clinical gingival health may be found in a periodontium that is intact, i.e. without clinical attachment loss or bone loss, and on a reduced periodontium in either a non-periodontitis patient (e.g. in patients with some form of gingival recession or following crown lengthening surgery) or in a patient with a history of periodontitis who is currently periodontally stable. Clinical gingival health can be restored following treatment of gingivitis and periodontitis. However, the treated and stable periodontitis patient with current gingival health remains at increased risk of recurrent periodontitis, and accordingly, must be closely monitored. Two broad categories of gingival diseases include non-dental plaque biofilm-induced gingival diseases and dental plaque-induced gingivitis. Non-dental plaque biofilm-induced gingival diseases include a variety of conditions that are not caused by plaque and usually do not resolve following plaque removal. Such lesions may be manifestations of a systemic condition or may be localized to the oral cavity. Dental plaque-induced gingivitis has a variety of clinical signs and symptoms, and both local predisposing factors and systemic modifying factors can affect its extent, severity, and progression. Dental plaque-induced gingivitis may arise on an intact periodontium or on a reduced periodontium in either a non-periodontitis patient or in a currently stable "periodontitis patient" i.e. successfully treated, in whom clinical inflammation has been eliminated (or substantially reduced). A periodontitis patient with gingival inflammation remains a periodontitis patient (Figure 1), and comprehensive risk assessment and management are imperative to ensure early prevention and/or treatment of recurrent/progressive periodontitis. Precision dental medicine defines a patient-centered approach to care, and therefore, creates differences in the way in which a "case" of gingival health or gingivitis is defined for clinical practice as opposed to epidemiologically in population prevalence surveys. Thus, case definitions of gingival health and gingivitis are presented for both purposes. While gingival health and gingivitis have many clinical features, case definitions are primarily predicated on presence or absence of bleeding on probing. Here we classify gingival health and gingival diseases/conditions, along with a summary table of diagnostic features for defining health and gingivitis in various clinical situations.

Computational Models Accurately Predict Multi-Cell Biomarker Profiles in Inflammation and Cancer

Individual computational models of single myeloid, lymphoid, epithelial, and cancer cells were created and combined into multi-cell computational models and used to predict the collective chemokine, cytokine, and cellular biomarker profiles often seen in inflamed or cancerous tissues. Predicted chemokine and cytokine output profiles from multi-cell computational models of gingival epithelial keratinocytes (GE KER), dendritic cells (DC), and helper T lymphocytes (HTL) exposed to lipopolysaccharide (LPS) or synthetic triacylated lipopeptide (Pam3CSK4) as well as multi-cell computational models of multiple myeloma (MM) and DC were validated using the observed chemokine and cytokine responses from the same cell type combinations grown in laboratory multi-cell cultures with accuracy. Predicted and observed chemokine and cytokine responses of GE KER + DC + HTL exposed to LPS and Pam3CSK4 matched 75% (15/20, p = 0.02069) and 80% (16/20, P = 0.005909), respectively. Multi-cell computational models became ‘personalized’ when cell line-specific genomic data were included into simulations, again validated with the same cell lines grown in laboratory multi-cell cultures. Here, predicted and observed chemokine and cytokine responses of MM cells lines MM.1S and U266B1 matched 75% (3/4) and MM.1S and U266B1 inhibition of DC marker expression in co-culture matched 100% (6/6). Multi-cell computational models have the potential to identify approaches altering the predicted disease-associated output profiles, particularly as high throughput screening tools for anti-inflammatory or immuno-oncology treatments of inflamed multi-cellular tissues and the tumor microenvironment.

Dataset on the chemokine and cytokine responses of multi-cell cultures treated with Porphyromonas gingivalis hemagglutinin B

Chemokines and cytokines produced in gingival tissues exposed to microorganisms and microbial products in dental plaque lead to local inflammation and tissue damage seen in periodontal disease. Bates et al. 2018 [1] reported that Porphyromonas gingivalis hemagglutinin B (HagB)-induced matrix metalloproteinase (MMP) responses of single cell cultures containing dendritic cells, gingival epithelial (GE) keratinocytes, or T cells were significantly different from the MMP responses of these same cells grown in multi-cell cultures. Here we report the concentrations (pg/ml) of HagB-induced IL1α, IL6, IL8, IL12(p40), GM-CSF, MIP1α, MIP1β, RANTES, TNFα, and VEGF produced by dendritic cells, GE keratinocytes, or T cells in single cell cultures, two-cell cultures, or three-cell cultures.

Matrix Metalloproteinase Response of Dendritic Cell, Gingival Epithelial Keratinocyte, and T-Cell Transwell Co-Cultures Treated with Porphyromonas gingivalis Hemagglutinin-B

Matrix metalloproteinases (MMPs) are enzymes involved in periodontal tissue destruction. Hemagglutinin B (HagB) from the periodontal pathogen Porphyromonas gingivalis induces an elevated MMP response in dendritic cells, but responses from cultures of single-cell types do not reflect the local tissue environment. The objective of this study was to measure HagB-induced MMP responses in a transwell co-culture system containing dendritic cells, gingival epithelial (GE) keratinocytes, and CD4+ T-cells. Transwell co-cultures were assembled and treated with or without HagB. Immunoassays were used to determine production of MMP1, MMP7, MMP9, and MMP12 in response to HagB up to 64 h. Control responses were subtracted from HagB-induced responses. A two-way fixed effect ANOVA was fit to log-transformed concentrations and pairwise group comparisons were conducted (p < 0.05). At 64 h, dendritic cells produced elevated MMP1 and MMP9 responses, which were attenuated in the 3-cell co-culture (p < 0.05). There were also significant differences in MMP7 and MMP12 production between single-cell cultures and co-cultures. These results support the need to use multiple cell types in culture models to evaluate a more representative response to proinflammatory agonists. This three-cell transwell co-culture model may help us better understand the inflammatory process in periodontal disease and test novel therapeutic approaches.

Promise of Combining Antifungal Agents in Denture Adhesives to Fight Candida Species Infections

PURPOSE

Several complications may arise in patients wearing complete prosthetic appliances, including denture-associated infections and mucosal stomatitis due to Candida species. This study evaluated the activity of anti-Candida agents in denture adhesive and the cytotoxicities of these preparations for primary human gingival epithelial (GE) keratinocytes.

MATERIALS AND METHODS

The anti-Candida activities of antimicrobial peptides, antimicrobial lipids, and antifungal agents against C. albicans ATCC 64124 or HMV4C were assessed in microdilution assays containing water or 1% denture adhesive. The minimal inhibitory concentrations (MIC) and the minimal bactericidal concentrations (MBC) were determined. The cytotoxicities of denture adhesive compounded with these agents were assessed in 1.0 × 10⁵ primary GE keratinocytes in LGM-3 media with resazurin.

RESULTS

Lactoferricin B, SMAP28, sphingosine, dihydrosphingosine, and phytosphingosine in 1% denture adhesive lost antimicrobial activity for C. albicans (p < 0.05). Amphotericin B, chlorhexidine dihydrochloride, chlorhexidine gluconate, fluconazole, and nystatin in 1% denture adhesive or compounded directly into denture adhesive and then diluted to 1% adhesive, did not lose antimicrobial activity. Compounded formulations were not cytotoxic (LD₅₀ > 100.0 μg/ml) against primary human GE keratinocytes.

CONCLUSIONS

Antimicrobial peptides and antimicrobial lipids had diminished activities in 1% adhesive, suggesting that components in adhesives may inactivate local innate immune factors in the oral cavity, possibly predisposing denture wearers to Candida species infections. More importantly, antifungal agents retained their anti-C. albicans activities in denture adhesive, strongly suggesting that antifungal agents could be candidates for inclusion in adhesive formulations and used as prescribed topical treatments for individuals with denture stomatitis.

Predicting PD-L1 expression on human cancer cells using next-generation sequencing information in computational simulation models

PURPOSE

Interaction of the programmed death-1 (PD-1) co-receptor on T cells with the programmed death-ligand 1 (PD-L1) on tumor cells can lead to immunosuppression, a key event in the pathogenesis of many tumors. Thus, determining the amount of PD-L1 in tumors by immunohistochemistry (IHC) is important as both a diagnostic aid and a clinical predictor of immunotherapy treatment success. Because IHC reactivity can vary, we developed computational simulation models to accurately predict PD-L1 expression as a complementary assay to affirm IHC reactivity.

METHODS

Multiple myeloma (MM) and oral squamous cell carcinoma (SCC) cell lines were modeled as examples of our approach. Non-transformed cell models were first simulated to establish non-tumorigenic control baselines. Cell line genomic aberration profiles, from next-generation sequencing (NGS) information for MM.1S, U266B1, SCC4, SCC15, and SCC25 cell lines, were introduced into the workflow to create cancer cell line-specific simulation models. Percentage changes of PD-L1 expression with respect to control baselines were determined and verified against observed PD-L1 expression by ELISA, IHC, and flow cytometry on the same cells grown in culture.

RESULT

The observed PD-L1 expression matched the predicted PD-L1 expression for MM.1S, U266B1, SCC4, SCC15, and SCC25 cell lines and clearly demonstrated that cell genomics play an integral role by influencing cell signaling and downstream effects on PD-L1 expression.

CONCLUSION

This concept can easily be extended to cancer patient cells where an accurate method to predict PD-L1 expression would affirm IHC results and improve its potential as a biomarker and a clinical predictor of treatment success.

Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells

Long-chain bases, found in the oral cavity, have potent antimicrobial activity against oral pathogens. In an article associated with this dataset, Poulson and colleagues determined the cytotoxicities of long-chain bases (sphingosine, dihydrosphingosine, and phytosphingosine) for human oral gingival epithelial (GE) keratinocytes, oral gingival fibroblasts (GF), dendritic cells (DC), and squamous cell carcinoma (SCC) cell lines [1]. Poulson and colleagues found that GE keratinocytes were more resistant to long-chain bases as compared to GF, DC, and SCC cell lines [1]. In this study, we assess the susceptibility of DC to lower concentrations of long chain bases. 0.2–10.0 µM long-chain bases and GML were not cytotoxic to DC; 40.0–80.0 µM long-chain bases, but not GML, were cytotoxic for DC; and 80.0 µM long-chain bases were cytotoxic to DC and induced cellular damage and death in less than 20 mins. Overall, the LD₅₀ of long-chain bases for GE keratinocytes, GF, and DC were considerably higher than their minimal inhibitory concentrations for oral pathogens, a finding important to pursuing their future potential in treating periodontal and oral infections.

Cytotoxicity of HBD3 for dendritic cells, normal human epidermal keratinocytes, hTERT keratinocytes, and primary oral gingival epithelial keratinocytes in cell culture conditions

Human β-defensin 3 (HBD3) is a prominent host defense peptide. In our recent work, we observed that HBD3 modulates pro-inflammatory agonist-induced chemokine and cytokine responses in human myeloid dendritic cells (DCs), often at 20.0 μM concentrations. Since HBD3 can be cytotoxic in some circumstances, it is necessary to assess its cytotoxicity for DCs, normal human epidermal keratinocytes (NHEKs), human telomerase reverse transcriptase (hTERT) keratinocytes, and primary oral gingival epithelial (GE) keratinocytes in different cell culture conditions. Cells, in serum free media with resazurin and in complete media with 10% fetal bovine serum and resazurin, were incubated with 5, 10, 20, and 40 μM HBD3. Cytotoxicity was determined by measuring metabolic conversion of resazurin to resorufin. The lethal dose 50 (LD50, mean μM±Std Err) values were determined from the median fluorescent intensities of test concentrations compared to live and killed cell controls. The LD50 value range of HBD3 was 18.2-35.9 μM in serum-free media for DCs, NHEKs, hTERT keratinocytes, and GE keratinocytes, and >40.0 μM in complete media. Thus, HBD3 was cytotoxic at higher concentrations, which must be considered in future studies of HBD3-modulated chemokine and cytokine responses in vitro.

Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells

Long-chain bases are present in the oral cavity. Previously we determined that sphingosine, dihydrosphingosine, and phytosphingosine have potent antimicrobial activity against oral pathogens. Here, we determined the cytotoxicities of long-chain bases for oral cells, an important step in considering their potential as antimicrobial agents for oral infections. This information would clearly help in establishing prophylactic or therapeutic doses. To assess this, human oral gingival epithelial (GE) keratinocytes, oral gingival fibroblasts (GF), and dendritic cells (DC) were exposed to 10.0-640.0 μM long-chain bases and glycerol monolaurate (GML). The effects of long-chain bases on cell metabolism (conversion of resazurin to resorufin), membrane permeability (uptake of propidium iodide or SYTOX-Green), release of cellular contents (LDH), and cell morphology (confocal microscopy) were all determined. GE keratinocytes were more resistant to long-chain bases as compared to GF and DC, which were more susceptible. For DC, 0.2-10.0 μM long-chain bases and GML were not cytotoxic; 40.0-80.0 μM long-chain bases, but not GML, were cytotoxic; and 80.0 μM long-chain bases induced cellular damage and death in less than 20 min. The LD50 of long-chain bases for GE keratinocytes, GF, and DC were considerably higher than their minimal inhibitory concentrations for oral pathogens, a finding important to pursuing their future potential in treating periodontal and oral infections.

The enhancement of bone regeneration by gene activated matrix encoding for platelet derived growth factor

Gene therapy using non-viral vectors that are safe and efficient in transfecting target cells is an effective approach to overcome the shortcomings of protein delivery of growth factors. The objective of this study was to develop and test a non-viral gene delivery system for bone regeneration utilizing a collagen scaffold to deliver polyethylenimine (PEI)-plasmid DNA (pDNA) [encoding platelet derived growth factor-B (PDGF-B)] complexes. The PEI-pPDGF-B complexes were fabricated at amine (N) to phosphate (P) ratio of 10 and characterized for size, surface charge, and in vitro cytotoxicity and transfection efficacy in human bone marrow stromal cells (BMSCs). The influence of the complex-loaded collagen scaffold on cellular attachment and recruitment was evaluated in vitro using microscopy techniques. The in vivo regenerative capacity of the gene delivery system was assessed in 5 mm diameter critical-sized calvarial defects in Fisher 344 rats. The complexes were ~100 nm in size with a positive surface charge. Complexes prepared at an N/P ratio of 10 displayed low cytotoxicity as assessed by a cell viability assay. Confocal microscopy revealed significant proliferation of BMSCs on complex-loaded collagen scaffolds compared to empty scaffolds. In vivo studies showed significantly higher new bone volume/total volume (BV/TV) % in calvarial defects treated with the complex-activated scaffolds following 4 weeks of implantation (14- and 44-fold higher) when compared to empty defects or empty scaffolds, respectively. Together, these findings suggest that non-viral PDGF-B gene-activated scaffolds are effective for bone regeneration and are an attractive gene delivery system with significant potential for clinical translation.

Quality assessment of systematic reviews on periodontal regeneration in humans

BACKGROUND

Systematic reviews represent the highest form of evidence in the current hierarchy of evidence-based dentistry. Critical analysis of published systematic reviews may help to analyze their strengths and weaknesses and to identify areas that need future improvement. The aim of this overview is to determine and compare the quality of systematic reviews published in the field of periodontal regeneration using established checklists, such as the Assessment of Multiple Systematic Reviews (AMSTAR) guidelines.

METHODS

A systematic search was conducted to retrieve reviews on periodontal regeneration in humans. A total of 14 systematic reviews were selected using a set of inclusion and exclusion criteria. Two independent reviewers appraised the quality of the selected reviews using AMSTAR guidelines. Each article was given an AMSTAR total score, based on the number of AMSTAR criteria that were fulfilled. The quality of included reviews was further assessed using a checklist proposed in 2003.

RESULTS

Only one of the selected systematic reviews satisfied all the AMSTAR guidelines, whereas two reviews satisfied just two of the 11 items. This study shows that published systematic reviews on periodontal regeneration exhibit significant structural and methodologic variability. Quality assessment using the additional checklist further confirmed the variability in the way systematic reviews were conducted and/or reported.

CONCLUSION

Consideration of guidelines for quality assessment, such as AMSTAR, when designing and conducting systematic reviews may increase the validity and clinical applicability of future reviews.

Influence of smoking on gingival crevicular fluid cytokines in severe chronic periodontitis

AIM

The aim of this study was to compare the expression of 22 chemokines and cytokines in gingival crevicular fluid (GCF) from smokers and non-smokers with periodontitis and periodontally healthy control subjects.

MATERIALS AND METHODS

Forty subjects with generalized severe chronic periodontitis (20 smokers and 20 non-smokers) and 12 periodontally healthy control subjects participated in this study. Four diseased and two healthy sites were selected from each of the periodontitis subjects. GCF samples were collected and cytokines analysed utilizing a multiplexed immunoassay (Luminex(®) ). Statistical analyses employed non-parametric tests including the Mann-Whitney and Wilcoxon matched-pairs signed-rank tests.

RESULTS

Compared with healthy control subjects, GCF in subjects with chronic periodontitis contained significantly higher amounts of interleukin (IL)-1α, IL-1β, IL-6, IL-12(p40) (pro-inflammatory cytokines); IL-8, macrophage chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, regulated on activation normal T-cell expressed and secreted (RANTES) (chemokines); IL-2, IFN-γ, IL-3, IL-4 (Th1/Th2 cytokines); IL-15 [regulator of T-cells and natural killer (NK) cells]. Smokers displayed decreased amounts of pro-inflammatory cytokines [IL-1α, IL-6, IL-12(p40)], chemokines (IL-8, MCP-1, MIP-1, RANTES), and regulators of T-cells and NK cells (IL-7, IL-15).

CONCLUSIONS

Periodontitis subjects had significantly elevated cytokine and chemokine profiles. Smokers exhibited a decrease in several pro-inflammatory cytokines and chemokines and certain regulators of T-cells and NK-cells. This reflects the immunosuppressant effects of smoking which may contribute to an enhanced susceptibility to periodontitis.

Association between periodontal disease and osteoporosis in postmenopausal women in jordan

BACKGROUND

Some studies suggest that females with osteoporosis are at an increased risk of periodontal attachment loss and tooth loss; however, results have varied. The aim of this study is to determine the relationship between periodontitis and osteoporosis among postmenopausal Jordanian women.

METHODS

This cross-sectional study includes 400 Jordanian postmenopausal women with a mean age of 62.5 years (SD ± 6.4 years). These subjects were recruited from patients who had received a routine dual-energy x-ray absorptiometry examination in the Radiology Department, King Abdullah Hospital, Jordan University of Science and Technology, between June 2008 and February 2009. The relationship between skeletal bone mineral density (BMD) and radiographic and clinical parameters of periodontal status, including the loss of alveolar crestal height (ACH), clinical attachment level, probing depth, and percentage of sites with bleeding on probing, was evaluated after controlling for known confounders.

RESULTS

Bivariate analyses revealed no significant differences in the severity and extent of clinical attachment and ACH loss among women with normal BMD, osteopenia, and osteoporosis. However, in the multivariate analysis, women with osteoporosis were more likely to have severe ACH loss (odds ratio [OR]: 4.20; 95% confidence interval [CI]: 1.57 to 11.22) and periodontitis (OR: 2.45; 95% CI: 1.38 to 4.34).

CONCLUSION

Osteoporosis was significantly associated with severe alveolar crestal bone loss and the prevalence of periodontitis cases in postmenopausal Jordanian women.

Interleukin-1 and interleukin-8 in nicotine- and lipopolysaccharide-exposed gingival keratinocyte cultures

BACKGROUND AND OBJECTIVE

Tobacco use is associated with increased periodontal destruction in both cigarette smokers and smokeless tobacco users. Gingival keratinocytes are the first cells in contact with microbial and tobacco components and play a key role in the innate immune response to these agents. The objective of this study was to evaluate the effect of nicotine and bacterial lipopolysaccharide (LPS) alone and in combination on gingival keratinocyte production of interleukin-1 alpha (IL-1 alpha) and interleukin-8 (IL-8).

MATERIAL AND METHODS

Gingival keratinocyte cultures were established from 10 healthy, non-tobacco-using subjects. The cells were stimulated for 24 h with 1 mum or 1 mm nicotine and/or 10 microg/mL Escherichia coli or Porphyromonas gingivalis LPS. Interleukin-1 alpha and IL-8 proteins were quantified using ELISAs.

RESULTS

Compared with untreated cultures, 1 mm nicotine stimulated production of IL-1 alpha (p < 0.001); E. coli and P. gingivalis LPS increased IL-8 production (p = 0.0014 and p = 0.0232, respectively). A combination of nicotine and LPS produced the highest cytokine quantities. Amounts of IL-1 alpha and IL-8 following 1 mm nicotine and LPS exposure were significantly greater than in untreated cultures (p < 0.001). Interleukin-8 was also responsive to 0.1 mum nicotine combined with E. coli or P. gingivalis LPS compared with control cultures (p < 0.0001 and p = 0.0029, respectively). Both cytokines tended to be elevated following the combined treatment relative to nicotine or LPS treatment alone.

CONCLUSION

These results demonstrate that nicotine and LPS differentially regulate IL-1 and IL-8 production by gingival keratinocytes. Combined treatment tended to elevate cytokine production further, which may have implications for the progression of periodontitis in tobacco users.

A multiplex immunoassay demonstrates reductions in gingival crevicular fluid cytokines following initial periodontal therapy

BACKGROUND AND OBJECTIVE

Cytokines and chemokines play an important role in the pathogenesis of periodontal diseases. The objective of this study was to quantitatively assess the effect of initial periodontal therapy on gingival crevicular fluid levels of a comprehensive panel of cytokines and chemokines, including several less extensively studied mediators.

MATERIAL AND METHODS

Clinical examinations were performed and gingival crevicular fluid samples obtained from six subjects with generalized severe chronic periodontitis prior to initial periodontal therapy and at re-evaluation (6-8 weeks). Four diseased and two healthy sites were sampled in each subject. Twenty-two gingival crevicular fluid mediators were examined using a multiplex antibody capture and detection platform. Statistical analyses were performed by fitting mixed effects linear models to log-transformed gingival crevicular fluid values.

RESULTS

Gingival crevicular fluid interleukin (IL)-1alpha and IL-1beta were the only cytokines to differ in initially diseased vs. initially healthy sites. Following initial therapy, 13 of the 16 detectable cytokines and chemokines decreased significantly in diseased sites, including IL-1alpha, IL-1beta, IL-2, IL-3, IL-6, IL-7, IL-8, IL-12 (p40), CCL5/regulated on activation, normally T cell expressed and secreted (RANTES), eotaxin, macrophage chemotactic protein-1, macrophage inflammatory protein-1alpha and interferon-gamma. At healthy sites, only three of the 16 mediators were significantly altered following therapy.

CONCLUSION

This is the first study, to our knowledge, to evaluate such an extensive panel of gingival crevicular fluid mediators within the same sample prior to and following initial therapy. The results confirm that periodontal therapy effectively reduces pro-inflammatory cytokines and chemokines, including less well-described mediators that may be important in initiation and progression of periodontitis. The multiplex assay will prove useful for future gingival crevicular fluid studies.

Human beta-defensin 3 binds to hemagglutinin B (rHagB), a non-fimbrial adhesin from Porphyromonas gingivalis, and attenuates a pro-inflammatory cytokine response

Regulatory mechanisms in mucosal secretions and tissues recognize antigens and attenuate pro-inflammatory cytokine responses. Here, we asked whether human beta-defensin 3 (HBD3) serves as an upstream suppressor of cytokine signaling that binds and attenuates pro-inflammatory cytokine responses to recombinant hemagglutinin B (rHagB), a non-fimbrial adhesin from Porphyromonas gingivalis strain 381. We found that HBD3 binds to immobilized rHagB and produces a significantly higher resonance unit signal in surface plasmon resonance spectroscopic analysis, than HBD2 and HBD1 that are used as control defensins. Furthermore, we found that HBD3 significantly attenuates (P<0.05) the interleukin (IL)-6, IL-10, granulocyte macrophage colony stimulating factor (GM-CSF) and tumor-necrosis factor-alpha (TNF-alpha) responses induced by rHagB in human myeloid dendritic cell culture supernatants and the extracellular signal-regulated kinases (ERK 1/2) response in human myeloid dendritic cell lysates. Thus, HBD3 binds rHagB and this interaction may be an important initial step to attenuate a pro-inflammatory cytokine response and an ERK 1/2 response.

E-learning and the future of dental education: opinions of administrators and information technology specialists

The digital revolution and growth of the Internet have led to many innovations in the area of electronic learning (e-learning). To survive and prosper, educators must be prepared to respond creatively to these changes. Administrators and information technology specialists at six dental schools and their parent institutions were interviewed regarding their opinions of the impact that e-learning will have on the future of dental education. Interview questions encompassed vision, rate of change, challenges, role of faculty, resources, enrolment, collaboration, responsibility for course design and content, mission and fate of the institution. The objective of this qualitative study was to sample the opinions of educational administrators and information technology specialists from selected US universities regarding the impact of e-learning on dental education to detect trends in their attitudes. Responses to the survey indicated disagreement between administrators and informational technology specialists regarding the rate of change, generation of resources, impact on enrolment, responsibility for course design and content, mission and fate of the university. General agreement was noted with regard to vision, challenges, role of faculty and need for collaboration.

Factors related to utilization of dental services during pregnancy

OBJECTIVES

The purposes of this study were to investigate factors related to utilization of dental services during pregnancy and to assess the extent of mothers' knowledge regarding oral health during pregnancy and its effect on pregnancy outcomes.

MATERIALS AND METHODS

Cross-sectional data were collected from 625 women using a structured questionnaire mailed to mothers who had given birth in Johnson County, Iowa from August 2001 to March 2002. The survey assessed knowledge, behaviours, attitudes toward dental care during pregnancy, and personal, demographic and pregnancy-related factors. Variables which showed associations in bivariate analysis (p< or =0.1) were considered as candidates for building logistic regression models separately by domain (demographics, dental health care behaviours, lifestyle, financial variables, pregnancy-related variables, and knowledge of the possible association between oral health and pregnancy). Significant domain-specific regression results (p< or =0.05) were used to develop a final model using forward stepwise logistic regression analyses.

RESULTS

The overall response rate was 69%. Dental visits during pregnancy were reported by 49% of respondents. Forty-three percent were aware of the possible connection between oral health and pregnancy outcomes. In the final logistic regression analysis, factors significantly associated with reporting dental visits during pregnancy were: (1) personal factors (being married, greater frequency of visiting the dentist when not pregnant and use of inter-proximal cleaning aids); (2) financial factors (dental insurance); and (3) knowledge of the possible connection between oral health and pregnancy outcomes.

CONCLUSIONS

There was limited knowledge of the possible relationships between oral health and pregnancy outcomes in a fairly homogeneous population of women who were of relatively high socioeconomic standing. This study suggests that better education of the importance of dental care before and during pregnancy is needed.

Correlation between beta-defensin expression and induction profiles in gingival keratinocytes

Human beta-defensins are antimicrobial peptides produced by epithelial cells. To date, 28 beta-defensins have been described and the expression of a select few has been classified as constitutive or inducible. Most studies have evaluated expression and regulation using a limited number of primary cell cultures or immortalized cell lines. The goal of this study was to quantitatively assess the in vitro expression and inducibility profiles of human beta-defensins, HBD-1, HBD-2, and HBD-3 across a number of primary gingival keratinocyte cultures. Cultured cells from 14 human subjects were stimulated with interleukin-1 beta (IL-1beta), IL-2, IL-6, IL-8, IL-12, tumor necrosis factor alpha (TNF-alpha), gamma interferon (IFN-gamma) or Escherichia coli lipopolysaccharide (LPS) and analyzed by reverse transcription (RT)-PCR. A subset of cultures were quantitatively assessed by real-time PCR. HBD-1 presented the highest and most heterogeneous expression at the basal level (non-stimulated) as compared to expression of HBD-2 and HBD-3, which was significantly lower and homogeneous. IFN-gamma was a primary inducer for HBD-1 and HBD-3, while IL-1beta and TNF-alpha were primary inducers for HBD-2. Sporadic induction was seen for IL-2, IL-6 and LPS. Synergistic expression was seen when various cytokines were combined. Interestingly, the induction potential of each beta-defensin was directly correlated to its basal expression. An inhibitor of JAK2 kinase (Janus kinase), down-regulated IFN-gamma-induced HBD-1 and HBD-3 expression, suggesting a role for the JAK/signal transducer and activator of transcription (STAT) signaling pathway in their expression. HBD-2 protein expression of supernatants and cell lysates paralleled mRNA expression. The results suggest that beta-defensin expression and induction in gingival keratinocytes is similar to that seen in other tissue. However, the novel finding of considerable variation among induction levels and the correlation of the induction with basal expression suggests that these innate response elements may play a key role in susceptibility or resistance to disease in the oral cavity.

Comparison of differentiation markers between normal and two squamous cell carcinoma cell lines in culture

This study examines differences between cultures of normal human oral epithelial cells and two squamous cell carcinoma cell lines (SCC15 and SCC25) in the expression of structural proteins, adhesion molecules, plasma membrane lipid composition, and intercellular junctions. Based on immunocytochemistry, most normal cell cultures appeared to express more E-cadherin, integrin beta-1, cytokeratin (CK) 14, CK19, and involucrin than SCC cultures. By Western blot analysis, normal cultures expressing high levels of E-cadherin also expressed high levels of involucrin and low levels of CK19. Both SCC cultures demonstrated lower expression of E-cadherin and involucrin, whereas only SCC15 cells showed high levels of CK19. Expression of beta-catenin, an E-cadherin associated protein with potential oncogene function, did not vary among normal and SCC cells. Proportions of saturated fatty acids quantified by thin layer chromatography were higher in the normal cell cultures, than in both SCC cell lines. No morphological differences were evident by transmission electron microscopy (TEM) between normal and SCC cell-cell intercellular junctions. Although no quantitation was attempted, observation suggested that normal cells form more intercellular junctions (TEM observation) and larger intercellular bridges (SEM observation) compared to both SCC cell lines. Of the factors examined, main variations between cultures of normal oral epithelium and the two SCC cell lines examined include the expression of structural and adhesion proteins, lipid composition, and intercellular junctions. The extent of the differences varies according to the stage of terminal differentiation demonstrated by the normal cell cultures.

Expression of beta-defensins in gingival health and in periodontal disease

BACKGROUND

Human beta-defensins (HBDs) are epithelial-derived antimicrobial peptides. The expression of three HBDs (HBD-1, HBD-2, and HBD-3) has been reported in oral mucosa, gingiva, and salivary glands. However, their role in protection against oral infections is not well understood. This study examined the expression of HBD-1, HBD-2, and HBD-3 mRNAs in gingival health and periodontal disease.

METHODS

Gingival tissue discarded from periodontal procedures was obtained from 20 periodontally healthy and 29 periodontally diseased sites. Total RNA was isolated, and expression of beta-defensins was analyzed by both 35-cycle and semiquantitative (25-cycle) reverse transcription-polymerase chain reaction (RT-PCR). The level of expression was assigned ordinal scores of no expression, low expression, or high expression. mRNA expression was compared between healthy and diseased groups using exact tests of homogeneity and Cochran-Mantel-Haenszel tests; associations among the variables were assessed using exact tests and Kendall's tau-b statistic.

RESULTS

All 49 samples demonstrated basal mRNA expression of HBD-1, HBD-2, and HBD-3. Significantly higher levels of HBD-3 (P = 0.012) expression were found in the healthy tissues as compared to the diseased ones. There was also a suggestion of higher expression of HBD-2 in the healthy tissues (P = 0.12). Levels of HBD-1, HBD-2, and HBD-3 mRNA expression were correlated with one another (P < 0.001).

CONCLUSIONS

High levels of HBD-3 mRNA expression in healthy tissues suggest a potentially important protective role for defensins in the host immune response to infection by periodontal pathogens.

Expression and regulation of novel human beta-defensins in gingival keratinocytes

This study evaluated the expression and regulation of beta-defensins DEFB-104 and the recently identified DEFB-105-14 in gingival keratinocytes. Keratinocytes from healthy subjects were exposed to cytokines, Escherichia coli lipopolysaccharide or Candida species. Total RNA was extracted and defensin expression analyzed by reverse transcription-polymerase chain reaction. Three patterns of expression were seen: no expression, constitutive expression and inducible expression. Constitutive mRNA expression was evident for DEFB-104, 107, 109, 111, and 112. DEFB-108 and 114 were induced by interleukin (IL)-1beta and Candida species. For DEFB-108 expression, synergism was observed when IL-1beta was combined with tumor necrosis factor-alpha or interferon-gamma. Downregulation of DEFB-109 occurred following treatment with Candida albicans. These findings suggest a role for multiple beta-defensins in response to oral infection. Further investigation is needed to better understand their function, both in terms of antimicrobial activities and contributions to innate and acquired immunity.

Epidemiology of Sarcocystis neurona infections in domestic cats (Felis domesticus) and its association with equine protozoal myeloencephalitis (EPM) case farms and feral cats from a mobile spay and neuter clinic

Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease in the horse most commonly caused by Sarcocystis neurona. The domestic cat (Felis domesticus) is an intermediate host for S. neurona. In the present study, nine farms, known to have prior clinically diagnosed cases of EPM and a resident cat population were identified and sampled accordingly. In addition to the farm cats sampled, samples were also collected from a mobile spay and neuter clinic. Overall, serum samples were collected in 2001 from 310 cats, with samples including barn, feral and inside/outside cats. Of these 310 samples, 35 were from nine horse farms. Horse serum samples were also collected and traps were set for opossums at each of the farms. The S. neurona direct agglutination test (SAT) was used for both the horse and cat serum samples (1:25 dilution). Fourteen of 35 (40%) cats sampled from horse farms had circulating S. neurona agglutinating antibodies. Twenty-seven of the 275 (10%) cats from the spay/neuter clinic also had detectable S. neurona antibodies. Overall, 115 of 123 (93%) horses tested positive for anti-S. neurona antibodies, with each farm having greater than a 75% exposure rate among sampled horses. Twenty-one opossums were trapped on seven of the nine farms. Eleven opossums had Sarcocystis sp. sporocysts, six of them were identified as S. neurona sporocysts based on bioassays in gamma-interferon gene knockout mice with each opossum representing a different farm. Demonstration of S. neurona agglutinating antibodies in domestic and feral cats corroborates previous research demonstrating feral cats to be naturally infected, and also suggests that cats can be frequently infected with S. neurona and serve as one of several natural intermediate hosts for S. neurona.

Cigarette Smoking and the Periodontal Patient

Evidence from cross-sectional and case-control studies in various populations demonstrates that adult smokers are approximately three times as likely as non-smokers to have periodontitis. The association between smoking and attachment loss is even stronger when the definition of periodontitis is restricted to the most severely affected subjects. Smokers have a diminished response to periodontal therapy and show approximately half as much improvement in probing depths and clinical attachment levels following non-surgical and various surgical modalities of therapy. Implant failures in smokers are twice those of non-smokers, with a higher failure rate in the maxillary arch accounting for the majority of the difference. Tobacco-induced alterations in microbial and host factors contribute to these deleterious effects of smoking on the periodontium. In longitudinal studies, the rate of periodontal disease progression is increased in smokers, but decreases to that of a non-smoker following tobacco cessation. Likewise, recent non-smokers respond to periodontal therapy in a manner similar to patients who have never smoked. Data regarding the impact of smoking on periodontal status included in this review will be helpful to dental health professionals as they counsel their patients regarding tobacco use. The role of dental health professionals in tobacco cessation is discussed, including the use of the five A's: ask--identify tobacco users; advise--advise them to quit; assess--evaluate the patient's readiness to quit; assist--offer assistance in cessation; and arrange--follow up on the patient's cessation efforts. The addition of pharmacotherapy to behavioral therapy, including nicotine replacement therapy and bupropion, can increase cessation rates. The most popular form of nicotine replacement therapy is the patch, and its use has been shown to double cessation rates compared to behavioral therapy alone. Use of bupropion in combination with nicotine replacement therapy may be particularly helpful for heavy smokers or smokers who have experienced multiple failed attempts at cessation. The American Academy of Periodontology Parameters of Care include tobacco cessation as a part of periodontal therapy, and the 2000 Surgeon General's Report on Oral Health in America encourages dental professionals to become more active in tobacco cessation counseling. Doing so will have far-reaching positive effects on our patients' oral and general health.

Defensin-induced adaptive immunity in mice and its potential in preventing periodontal disease

The severity of periodontal disease is dependent on a combination of host, microbial agent and environmental factors. One strong correlate related to periodontal disease pathogenesis is the immune status of the host. Here we show that human neutrophil peptide (HNP) defensins or human beta-defensins (HBD), co-administered intranasally with the antigen ovalbumin (OVA), induce unique immune responses that if used with microbial antigens may have the potential to hinder the pathogenesis of periodontal disease. C57BL/6 mice were immunized intranasally with phosphate buffered saline (PBS) containing 1 micro g HNP-1, HNP-2, HBD1 or HBD2 with and without 50 microg OVA. At 21 days, isotypes and subclasses of OVA-specific antibodies were determined in saliva, serum, nasal wash, bronchoalveolar lavage fluid, and fecal extracts. OVA-stimulated splenic lymphoid cell cultures from immunized mice were assessed for interferon (IFN)-gamma, Interleukin (IL)-4 and IL-10. In comparison with mice immunized with only OVA, HNP-1 and HBD2 induced significantly higher (P < 0.05) OVA-specific serum IgG, lower, but not significant, serum IgM and significantly lower (P < 0.05) IFN-gamma. In contrast, HNP-2 induced low OVA-specific serum IgG and higher, but not significant, serum IgM. HBD1 induced significantly higher (P < 0.05) OVA-specific serum IgG, higher, but not significant, serum IgM, and significantly higher (P < 0.05) IL-10. The elevated serum IgG subclasses contained IgG1 and IgG2b.

Subcellular localization of beta-catenin in malignant cell lines and squamous cell carcinomas of the oral cavity

BACKGROUND

Beta-catenin, an E-cadherin-associated protein involved in cell-cell adhesion and signaling, has been hypothesized to translocate to the nucleus and activate transcription in several human cancers, including oral squamous cell carcinomas (OSCC).

METHODS

In the present study, we analyzed the subcellular localization of beta-catenin in cultures of human oral normal and malignant (cell lines SCC15 and SCC25) keratinocytes and in 24 frozen samples of oral squamous cell carcinomas by a double-staining technique for nucleic acids and beta-catenin. Growth potential, as assessed by cell count at different time periods, was established for normal, SCC15 and SCC25 cell lines; oral squamous cell carcinomas were classified according to the histopathological and malignancy indexes.

RESULTS

Beta-catenin localized at the plasma membrane in the normal and SCC15 cells, not in the SCC25 cells, where it localized mostly in the perinuclear and nuclear areas. In the growth assays, SCC25 cell lines proliferated faster than in normal and SCC15 cells over a period of 6 days (cell numbers were significantly different, P < 0.0001). Carcinoma sections showed a combination of membranous, cytoplasmic and, in few invading epithelial islands of two tumors, nuclear localization of beta-catenin.

CONCLUSIONS

In oral squamous cell carcinomas, nuclear beta-catenin staining was observed only within invading islands of two carcinomas deep in the underlying connective tissue. On the basis of this study, we conclude that intranuclear beta-catenin does not appear to be a common finding in oral squamous cell carcinomas and that a clear association between intranuclear beta-catenin and histopathological and malignancy indexes in vivo could not be established.

Treatment of periodontitis by local administration of minocycline microspheres: a controlled trial

BACKGROUND

Periodontitis is an inflammatory condition of tooth-supporting tissues that is usually treated by mechanical removal of plaque and microorganisms that adhere to teeth. This treatment, known as scaling and root planing, is not optimally effective. Adjunctive therapy with locally delivered antimicrobials has resulted in improved clinical outcomes such as probing depth reduction. This article reports on the efficacy and safety of locally administered microencapsulated minocycline.

METHODS

Seven hundred forty-eight (748) patients with moderate to advanced periodontitis were enrolled in a multi-center trial and randomized to 1 of 3 treatment arms: 1) scaling and root planing (SRP) alone; 2) SRP plus vehicle; or 3) SRP plus minocycline microspheres. The primary outcome measure was probing depth reduction at 9 months. Clinical assessments were performed at baseline and 1, 3, 6, and 9 months.

RESULTS

Minocycline microspheres plus scaling and root planing provided substantially more probing depth reduction than either SRP alone or SRP plus vehicle. The difference reached statistical significance after the first month and was maintained throughout the trial. The improved outcome was observed to be independent of patients' smoking status, age, gender, or baseline disease level. There was no difference in the incidence of adverse effects among treatment groups.

CONCLUSIONS

Scaling and root planing plus minocycline microspheres is more effective than scaling and root planing alone in reducing probing depths in periodontitis patients.

Periodontal disease in pregnancy complicated by type 1 diabetes mellitus

BACKGROUND

Systemic disease and hormonal changes have been implicated as complicating factors for periodontal disease. Diabetes has been identified as a risk factor for periodontal disease, and diabetics can experience periodontal destruction at an earlier age than non-diabetic individuals. Increased hormone levels during pregnancy can contribute to increased gingival inflammation. The purpose of this study was to examine the association of type 1 diabetes mellitus (DM) on the periodontal status of pregnant women.

METHODS

Thirty-three (13 diabetic and 20 non-diabetic) subjects, 20 to 39 weeks gestation, participated in this study. The mean age of the diabetics and non-diabetics was 28.5 +/- 7.1 (SD) and 27.0 +/- 7.3 years, respectively. The following parameters were assessed at Ramfjord's reference teeth: plaque index (PI), gingival inflammation (GI), probing depth (PD), gingival margin (GM) location, and clinical attachment level (CAL).

RESULTS

Diabetic subjects had significantly (P<0.001) higher PI (1.48 +/- 0.69) and GI (1.77 +/- 0.44) scores than non-diabetics (PI = 0.63 +/- 0.38; GI = 0.93 +/- 0.48). Mean PD for diabetics (2.95 +/- 0.69 mm) was significantly different (P<0.024) from that of non-diabetics (2.44 +/- 0.32 mm). Although mean GM location was coronal to the cemento-enamel junction (CEJ) in both groups, gingival margins were at a more apical position (P<0.001) in the diabetics (-0.20 +/- 1.24 mm) compared to non-diabetics (-1.76 +/- 0.53 mm). Mean CAL values also varied significantly (P<0.001) between diabetics (2.60 +/- 1.54 mm) and non-diabetics (0.68 +/- 0.65 mm). Significant differences were seen for GI (P<0.001), PD (P=0.005), GM location (P<0.001), and CAL (P<0.001) when assessing the effect of diabetes and controlling for plaque. When assessing the effect of plaque and controlling for diabetes, the only significant difference was GI (P=0.001).

CONCLUSIONS

The results of this study demonstrate that periodontal inflammation and destruction are increased in pregnant diabetics as compared to non-diabetic pregnant patients. These findings may have implications for diabetic control and, hence, maternal and fetal outcomes in pregnant diabetic patients.

Impact of tobacco use on periodontal status

This article reviews the effects of smoked and smokeless tobacco on periodontal status, including the impact of smoking on periodontal therapy and potential mechanisms for the adverse effects of tobacco on the periodontium. Approximately half of periodontitis cases have been attributed to either current or former smoking. Both cigar and cigarette smokers have significantly greater loss of bone height than nonsmokers, and there is a trend for pipe smokers to have more bone loss than nonsmokers. Unlike smokers, who experience widespread periodontal destruction, the most prevalent effects of smokeless tobacco are localized to the site of placement, in the form of gingival recession and white mucosal lesions. Smoking has an adverse effect on all forms of periodontal therapy, and up to 90 percent of refractory periodontitis patients are smokers. The pathogenesis of smoking-related periodontal destruction has been attributed to alterations in the microflora and/or host response. Some data indicates that smoking may increase levels of certain periodontal pathogens, but there is more evidence that smoking has a negative effect on host response, such as neutrophil function and antibody production. An encouraging finding is that periodontal disease progression slows in patients who quit smoking and that these individuals have a similar response to periodontal therapy as nonsmokers. The facts presented in this paper will assist dental health professionals in treatment-planning decisions and provide them with important information to share with patients who use tobacco products.

Endoscopic therapy for benign bile duct strictures

Endoscopic therapy was attempted in 25 patients with benign strictures of the bile duct. In 23 patients, treatment involved endoscopic balloon dilation of the stricture zone or balloon dilation plus endoprosthesis placement. In 22 of 25 patients (88%), there was benefit from the endoscopic treatment. In 20 of 23 patients, there was significant radiographic improvement (p less than 0.001) in the diameter of their stricture following endoscopic therapy. All patients with elevated liver enzymes demonstrated rapid improvement following treatment. There was no significant morbidity or mortality associated with endoscopic treatment of benign biliary tract strictures. Follow-up study (mean, 4 +/- 0.3 years) discloses no recurrence of symptoms or elevated enzymes indicative of recurrent strictures. The treatment of benign bile duct strictures by a combination therapy of balloon dilation and stent placement provides a safe and effective treatment modality and an alternative to operative intervention.

Discovery of new human beta-defensins using a genomics-based approach

Epithelial beta-defensins are broad-spectrum cationic antimicrobial peptides that also act as chemokines for adaptive immune cells. In the human genome, all known defensin genes cluster to a <1 Mb region of chromosome 8p22-p23. To identify new defensin genes, the DNA sequence from a contig of large-insert genomic clones from the region containing human beta-defensin-2 (HBD-2) was analyzed for the presence of defensin genes. This sequence survey identified a novel beta-defensin, termed HBD-3. The HBD-3 gene contains two exons, is located 13 kb upstream from the HBD-2 gene, and it is transcribed in the same direction. A partial HBD-3 cDNA clone was amplified from cDNA derived from IL-1beta induced fetal lung tissue. The cDNA sequence encodes for a 67 amino acid peptide that is approximately 43% identical to HBD-2 and shares the beta-defensin six cysteine motif. By PCR analysis of two commercial cDNA panels, HBD-3 expression was detected in adult heart, skeletal muscle, placenta and in fetal thymus. From RT-PCR experiments, HBD-3 expression was observed in skin, esophagus, gingival keratinocytes, placenta and trachea. Furthermore, in fetal lung explants and gingival keratinocytes, HBD-3 mRNA expression was induced by IL-1beta. Additional sequence analysis identified the HE2 (human epididymis secretory protein) gene 17 kb upstream from the HBD-3 gene. One splice variant of this gene (HE2beta1) encodes a beta-defensin consensus cysteine motif, suggesting it represents a defensin gene product. HE2beta1 mRNA expression was detected in gingival keratinocytes and bronchial epithelia using RT-PCR analysis. The discovery of these novel beta-defensin genes may allow further understanding of the role of defensins in host immunity at mucosal surfaces.

Differential DNA methylation of the p16 INK4A/CDKN2A promoter in human oral cancer cells and normal human oral keratinocytes

The p16 INK4A tumor suppressor gene participates in establishing and maintaining the malignant phenotype of a variety of cancer cell lines and primary tumors. Recently it has been observed that p16 expression is lost in oral cavity cancer cell lines in the presence of a normal intact gene. To examine the role of DNA methylation as an explanation for these findings, we analyzed the DNA methylation patterns of the p16 INK4A promoter in DNA isolated from primary cultures of normal human oral keratinocytes and squamous cell carcinoma (SCC-15) oral cancer cells using bisulfite genomic sequencing. Our results demonstrated striking differences in the methylation status of the 5' CpG island of the p16 gene between normal and cancer cells. Normal human oral keratinocytes showed practically no methylation of the p16 INK4A promoter, while SCC-15 oral cancer cells showed almost complete methylation in this region. These data implicate DNA methylation as a mechanism for transcriptional silencing of the p16 INK4A gene in oral cancer cells.

Production of beta-defensin antimicrobial peptides by the oral mucosa and salivary glands

beta-Defensins are cationic peptides with broad-spectrum antimicrobial activity that are produced by epithelia at mucosal surfaces. Two human beta-defensins, HBD-1 and HBD-2, were discovered in 1995 and 1997, respectively. However, little is known about the expression of HBD-1 or HBD-2 in tissues of the oral cavity and whether these proteins are secreted. In this study, we characterized the expression of HBD-1 and HBD-2 mRNAs within the major salivary glands, tongue, gingiva, and buccal mucosa and detected beta-defensin peptides in salivary secretions. Defensin mRNA expression was quantitated by RNase protection assays. HBD-1 mRNA expression was detected in the gingiva, parotid gland, buccal mucosa, and tongue. Expression of HBD-2 mRNA was detected only in the gingival mucosa and was most abundant in tissues with associated inflammation. To test whether beta-defensin expression was inducible, gingival keratinocyte cell cultures were treated with interleukin-1beta (IL-1beta) or bacterial lipopolysaccharide (LPS) for 24 h. HBD-2 expression increased approximately 16-fold with IL-1beta treatment and approximately 5-fold in the presence of LPS. Western immunoblotting, liquid chromatography, and mass spectrometry were used to identify the HBD-1 and HBD-2 peptides in human saliva. Human beta-defensins are expressed in oral tissues, and the proteins are secreted in saliva; HBD-1 expression was constitutive, while HBD-2 expression was induced by IL-1beta and LPS. Human beta-defensins may play an important role in the innate defenses against oral microorganisms.

Clinical presentation and short-term outcome of endoscopic therapy of patients with symptomatic incomplete pancreas divisum

BACKGROUND

The clinical significance of incomplete pancreas divisum (IPD) has not been fully described. In this study we report the clinical presentation and results of endoscopic treatment of the 32 (0.6%) patients with IPD seen at our center over a 10-year period.

METHODS

The study population consisted of 24 women and 8 men (mean age 42 years, range 13 to 82 years). Ten (31%) patients presented with acute recurrent pancreatitis, 5 (16%) with chronic pancreatitis, and 3 (9%) with pancreatic type pain. Detailed history, laboratory tests, US, CT, and ERCP excluded other etiologies for their symptoms. The remaining 14 (44%) presented with biliary problems. The 18 symptomatic patients with IPD were treated as follows: 8 received dorsal duct stents, 3 underwent minor papilla endoscopic sphincterotomy and dorsal duct stent placement, 4 had minor papilla dilatation only, and 3 had ventral duct stents placed.

RESULTS

Patients were then followed for recurrence of pancreatitis and pancreatic-type pain. Mean follow-up was 15.5 months (range 3 to 30 months). Six (60%) of the patients with acute recurrent pancreatitis and 4 (80%) with chronic pancreatitis benefitted from the endoscopic therapy. However, only 1 (33%) of the patients with pancreatic-type pain benefitted.

CONCLUSION

The clinical presentation and response to endoscopic therapy of patients with ICP appeared to be similar to that of patients with complete pancreas divisum.

Development of smokeless tobacco-induced oral mucosal lesions

This study examined clinical and inflammatory mediator parameters during the development of snuff-induced mucosal lesions. Nineteen smokeless tobacco (ST) users placed moist snuff at designated new placement sites over either a 2- or 7-day period. By day 2, the predominant clinical alteration was an erythematous reaction, and one-third of the subjects demonstrated white striations in combination with erythema or ulceration. By 7 days, 56% of the subjects displayed white striated lesions. Tissue concentrations (pg/mg) of IL-1beta were 4.6+/-1.6 at new placement sites as compared with 0.7+/-0.4 at control sites (P<0.05). PGE2 and IL-1alpha concentrations also were significantly higher (P<0.05) at new placement sites as compared with control sites (9.4+/-2.2 vs 4.1+/-0.7 and 6.2+/-1.3 vs 3.2+/-0.7, respectively). In view of the recognized role of PGE2 and IL-1 in immune and inflammatory functions, these mediators may play a role in the pathogenesis of clinical alterations at ST placement sites.

Histological alterations following short-term smokeless tobacco exposure in humans

The purpose of this study was to investigate the histological changes following short-term smokeless tobacco application in humans. Sixteen smokeless tobacco-using subjects participated in this trial. Each subject had used at least 3 cans of snuff per week for the previous 2 yr and had an existing lesion at the site of habitual snuff placement. The experimental design included subject placement of moist snuff (University of Kentucky reference tobacco brand 1S3) at a new site in the mandibular arch. At either 2 or 7 d, biopsies were taken from the new lesions and from a non-placement site in the opposing arch. The volume density of inflammatory cells was determined by point counting. Keratin and epithelial thickness were evaluated by digitizing morphometry. Data were analyzed by repeated measures analysis of variance. In 7-d lesions, increased keratin thickness was observed at the new sites compared to the non-placement sites (p = 0.05). Increased volume density of fibroblasts (p = 0.027) and decreased volume densities of macrophages (p = 0.0083) and mast cells (p = 0.05) were observed at 2 d in new versus non-placement sites. Clinically, the new sites showed erythema, erythema plus ulceration, or white striations. This study demonstrated histological and clinical changes at new snuff placement sites in as few as 2-7 d, underscoring the rapidity of tissue alterations following snuff use.

The role of surveillance endoscopic retrograde cholangiopancreatography in preventing episodic cholangitis in patients with recurrent common bile duct stones

BACKGROUND AND STUDY AIMS

Approximately 2-7% of patients who have undergone previous removal of bile duct stones have recurrence often presenting as ascending cholangitis. The aim of this study was to identify the incidence, clinical presentation, and objective findings in this group of patients. Additionally, the effect of surveillance endoscopic retrograde cholangiopancreatography (ERCP) in preventing cholangitis, was studied.

PATIENTS AND METHODS

Two thousand and ninety-six patients who underwent ERCP for cholelithiasis were studied with 45 of these patients being identified as having recurrent common bile duct stones. Of the 45, 13 had two or more recurrences without having any obvious predisposing factors. The mean age of the 13 patients was 57 years. The characteristics of 13 patients were reviewed, including sphincterotomy size, liver function tests, and contrast drainage time.

RESULTS

All 13 patients with recurrent stones presented with ascending cholangitis. Stones were found to be soft, brown and accompanied by a large amount of sludge. The common bile duct in all 13 patients was noted to be dilated and had notable, widely patent sphincterotomes. There was significant delayed drainage in 77% of these patients. Yearly surveillance ERCPs were performed in the 13 patients, the incidence of acute cholangitis episodes per patient decreased from 2 to 0.6 with a four-year follow-up.

CONCLUSION

In a subgroup of patients with multiple common bile duct stone recurrences, annual surveillance ERCP with stone removal decreases the incidence of recurrent episodes of ascending cholangitis as well as its associated morbidity and mortality.

Evaluation of post-ERCP pancreatitis: potential causes noted during controlled study of differing contrast media. Midwest Pancreaticobiliary Study Group

BACKGROUND

Possible sources of post-ERCP pancreatitis were evaluated during a prospective, randomized, controlled study comparing different contrast media.

METHODS

A total of 1979 patients were randomized and subdivided into groups during the study. Patients were grouped for comparison depending on the type of procedure performed during ERCP. Diagnostic patients studied with pancreatograms (Group I) were compared with other groups, specifically, those not studied with pancreatograms (Group IV). All patients had subjective and objective estimates of the difficulty in cannulation of both ducts. The incidence of postprocedural pancreatitis was compared between and within each group.

RESULTS

In Group I there was a progressively higher incidence of pancreatitis with increased numbers of pancreatic duct injections. Patients with the highest (19.5%) frequency of pancreatitis received 10 or more injections into the pancreatic duct. Group I cases with difficult common bile duct cannulations had a higher frequency of post-ERCP pancreatitis (9.5%), as compared with the entire group (5.6%).

CONCLUSIONS

There was a higher incidence of pancreatitis associated with increased manipulation around the papillary orifice, especially with multiple pancreatic duct injections. There was also a slightly higher incidence of post-ERCP pancreatitis in cases with difficult common bile duct cannulation. Endoscopists are encouraged to evaluate and develop safer cannulation techniques that minimize the number of injections into the pancreatic duct and enhance selective cannulation.

Prostaglandin E2 and interleukin-1 concentrations in nicotine-exposed oral keratinocyte cultures

Oral keratinocytes are the first cells in contact with tobacco components and are capable of producing various inflammatory mediators, including PGE2 and IL-1. The purpose of this study was to examine PGE2 and IL-1 concentrations in nicotine-exposed oral keratinocyte cultures. Gingival keratinocyte cultures were established from healthy gingival tissues obtained from 7 subjects. Cultures were divided into 4 groups exposed to serum free medium (control), 0.1 microM, 10 microM or 1 mM nicotine for 4, 24 or 48 h. Using enzyme-linked immunosorbent assays, PGE2 and IL-1 alpha were quantified in culture supernatants; IL-1 alpha and beta were also measured in lysed cells. A repeated measures analysis of variance was used to identify significant differences over time and treatment. Nicotine exposure did not significantly alter PGE2 levels at any given time period; however, PGE2 quantities declined significantly (p = 0.0001) over time. At both 24 and 48 h, IL-1 alpha concentrations in lysates from 1 mM nicotine-exposed cells were significantly (p < 0.01) greater than those for all other treatments. Interleukin-1 alpha quantities also declined significantly (p = 0.037) over time in the cultures. Interleukin-1 beta concentrations were elevated, albeit not significantly, in the 1 mM treated cells at 24 and 48 h. Cell viability, mass and counts were not affected by nicotine treatment; these parameters increased significantly (p < 0.005) over time. In summary, nicotine treatment significantly increased IL-1 alpha concentrations in cultured keratinocytes; however, PGE2 synthesis was not altered. Elevated IL-1 production by keratinocytes may have implications in tobacco-induced lesions, given the central role IL-1 plays in tissue response to injury.

Effect of nicotine on arachidonic acid metabolites and epithelial parameters in rat oral mucosa

This study examined the effects of nicotine on oral mucosal levels of eicosanoids and on histologic parameters, including keratinocyte proliferation. Surgically-created canals in the mandibular lips of 20 male Sprague Dawley rats received either nicotine or saline in a cotton pellet twice daily for six weeks. Thromboxane B2 (TxB2) levels were depressed (P < 0.05) in nicotine treated tissues compared to saline treatment (5.8 +/- 1.0 vs 13.4 +/- 2.1 pg/mg). Within the nicotine group, TxB2 concentrations were lower (P < 0.05) at the nicotine site compared to the posterior site (18.3 +/- 5.4 pg/mg). There was also a trend towards reduced 6-keto-PGF1 alpha in the nicotine-treated tissues compared to saline-exposed sites. These alterations in cyclooxygenase metabolites were not accompanied by changes in epithelial proliferation or histologic parameters. 12(S)-hydroxyeicosatetranoic acid (12-HETE) and leukotriene B4 (LTB4) were not affected by nicotine. Therefore, nicotine may not be directly responsible for the hyperplasia at habitual tobacco placement sites, but may contribute to alterations in cyclooxygenase products of arachidonic acid metabolism.

Levels of cigarette consumption and response to periodontal therapy

Seventy-four patients with moderate to advanced periodontitis were classified by cigarette consumption at the initial exam: heavy smokers (HS) > or = 20 cigarettes/day (n = 31); light smokers (LS) < or = 19 cigarettes/day (n = 15); past smokers (PS) had a history of smoking but had quit by the initial exam (n = 10); and non-smokers (NS) had never smoked (n = 18). All patients were treated with four modalities of periodontal therapy followed by supportive periodontal treatment (SPT) for a period of up to 7 years. Clinical parameters including probing depth (PD), clinical attachment level (CAL), recession (REC), presence of bleeding on probing (BOP), and supragingival plaque (PL) were assessed at six sites around each tooth. Horizontal probing attachment level (HAL) was obtained at molar furcation sites. Data were collected initially, 4 weeks after non-surgical therapy, 10 weeks after surgical therapy, and yearly during SPT. HS and LS demonstrated less PD reduction and less CAL gain than PS and NS following active treatment and throughout SPT. Following active treatment, HAL changes were similar for all groups, but during 7 years of SPT, HS and LS experienced greater loss of HAL. There were no differences in BOP among the four groups. HS demonstrated a higher percentage of PL positive sites compared to the other groups. In summary, HS and LS responded less favorably to therapy than PS and NS. A past history of smoking was not deleterious to the response to therapy.

Nicotine effects on PGE2 and IL-1 beta 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-1 beta. 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 ng/ml, 1 microgram/ml, 10 micrograms/ml and 100 micrograms/ml) with or without 10 micrograms/ml Porphyromonas gingivalis LPS or Escherichia coli LPS. Culture supernatants were assayed for PGE2 and IL-1 beta by ELISA. None of the nicotine preparations resulted in significant PBM secretion of PGE2 and IL-1 beta above that of unstimulated cultures. However, PGE2 release was potentiated 1.7-fold by the combination of P. gingivalis LPS and 10 micrograms/ml nicotine relative to P. gingivalis LPS alone (p < 0.05, one-way ANOVA). Prostaglandin E2 release also was potentiated 3.5-fold by P. gingivalis LPS and 100 micrograms/ml nicotine relative to P. gingivalis LPS alone (p < 0.00001, one-way ANOVA) and 3.1-fold by E. coli LPS and 100 micrograms/ml nicotine relative to E. coli LPS alone (p < 0.00001, one-way ANOVA). IL-1 beta secretion was lower for either LPS plus 100 micrograms/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.