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1.  Systemic effects of periodontitis: Lessons learned from research on atherosclerotic vascular disease and adverse pregnancy outcomes 
International dental journal  2015;65(6):283-291.
Studies conducted over the past 25 years have focused on the role of periodontitis, an inflammatory condition of microbial etiology that destroys the tooth supporting tissues, as a systemic inflammatory stressor that can act as an independent risk factor of atherosclerotic vascular disease (AVSD) and adverse pregnancy outcomes (APOs). It has been suggested that periodontitis-associated bacteremias and systemic dissemination of inflammatory mediators produced in the periodontal tissues may result in systemic inflammation and endothelial dysfunction, while bacteria of oral origin may translocate into the feto-placental unit. Epidemiologic studies largely support an association between periodontitis and ASVD / APOs independent of known confounders; indeed, periodontitis has been shown to confer statistically significantly elevated risk for clinical events associated with ASVD and APOs in multivariable adjustments. On the other hand, intervention studies demonstrate that although periodontal therapy reduces systemic inflammation and improves endothelial function, it has no positive effect on the incidence of APOs. Studies of the effects of periodontal interventions on ASVD-related clinical events are lacking. This review summarizes key findings from mechanistic, association and intervention studies and attempts to reconcile the seemingly contradictory evidence that originates from different lines of investigation.
doi:10.1111/idj.12185
PMCID: PMC4713295  PMID: 26388299
Inflammation; periodontal; cardiovascular; gestation; therapy; review
2.  Mini but Mighty - microRNAs in the Pathobiology of Periodontal Disease 
Periodontology 2000  2015;69(1):201-220.
microRNAs (miRNAs) are a family of small, non-coding RNA molecules that negatively regulate protein expression by either inhibiting the initiation of the translation of mRNA, or by inducing the degradation of mRNA molecules. Accumulating evidence suggests that miRNA-mediated repression of protein expression is of paramount importance in a broad range of physiologic and pathologic conditions. In particular, miRNA-induced dysregulation of molecular processes involved in inflammatory pathways has been shown to contribute to the development of chronic inflammatory diseases. n this review, we first provide an overview of miRNA biogenesis, main mechanisms of action, and currently available miRNA profiling tools. Next, we summarize the available evidence supporting a specific role for miRNAs in the pathobiology of periodontitis. Based on a review of available data on the differential expression of miRNAs in gingival tissues in states of periodontal health and disease, we address specific roles for miRNAs in molecular and cellular pathways causally linked to periodontitis. Our review points to several lines of evidence suggesting the involvement of miRNAs in periodontal tissue homeostasis and pathology. Although the intricate regulatory networks affected by miRNA function are still incompletely mapped, further utilization of systems biology tools is expected to enhance our understanding of the pathobiology of periodontitis.
doi:10.1111/prd.12095
PMCID: PMC4530521  PMID: 26252410
small RNAs; epigenetics; expression regulators; inflammation
3.  Role of the NK Cell-Activating Receptor CRACC in Periodontitis 
Infection and Immunity  2013;81(3):690-696.
Periodontitis is a highly prevalent, biofilm-mediated chronic inflammatory disease that results in the loss of the tooth-supporting tissues. It features two major clinical entities: chronic periodontitis, which is more common, and aggressive periodontitis, which usually has an early onset and a rapid progression. Natural killer (NK) cells are a distinct subgroup of lymphocytes that play a major role in the ability of the innate immune system to steer immune responses. NK cells are abundant in periodontitis lesions, and NK cell activation has been causally linked to periodontal tissue destruction. However, the exact mechanisms of their activation and their role in the pathophysiology of periodontitis are elusive. Here, we show that the predominant NK cell-activating molecule in periodontitis is CD2-like receptor activating cytotoxic cells (CRACC). We show that CRACC induction was significantly more pronounced in aggressive than chronic periodontitis and correlated positively with periodontal disease severity, subgingival levels of specific periodontal pathogens, and NK cell activation in vivo. We delineate how Aggregatibacter actinomycetemcomitans, an oral pathogen that is causally associated with aggressive periodontitis, indirectly induces CRACC on NK cells via activation of dendritic cells and subsequent interleukin 12 (IL-12) signaling. In contrast, we demonstrate that fimbriae from Porphyromonas gingivalis, a principal pathogen in chronic periodontitis, actively attenuate CRACC induction on NK cells. Our data suggest an involvement of CRACC-mediated NK cell activation in periodontal tissue destruction and point to a plausible distinction in the pathobiology of aggressive and chronic periodontitis that may help explain the accelerated tissue destruction in aggressive periodontitis.
doi:10.1128/IAI.00895-12
PMCID: PMC3584889  PMID: 23250953
4.  Gingival tissue transcriptomes in experimental gingivitis 
Aims
We investigated the sequential gene expression in the gingiva during the induction and resolution of experimental gingivitis.
Methods
Twenty periodontally and systemically healthy non-smoking volunteers participated in a 3-week experimental gingivitis protocol, followed by debridement and 2-week regular plaque control. We recorded clinical indices and harvested gingival tissue samples from 4 interproximal palatal sites in half of the participants at baseline, Day 7, 14 and 21 (‘induction phase’), and at day 21, 25, 30 and 35 in the other half (‘resolution phase’). RNA was extracted, amplified, reversed transcribed, amplified, labeled and hybridized with Affymetrix Human Genome U133Plus2.0 microarrays. Paired t-tests compared gene expression changes between consecutive time points. Gene ontology analyses summarized the expression patterns into biologically relevant categories.
Results
The median gingival index was 0 at baseline, 2 at Day 21 and 1 at Day 35. Differential gene regulation peaked during the third week of induction and the first four days of resolution. Leukocyte transmigration, cell adhesion and antigen processing/presentation were the top differentially regulated pathways.
Conclusions
Transcriptomic studies enhance our understanding of the pathobiology of the reversible inflammatory gingival lesion and provide a detailed account of the dynamic tissue responses during induction and resolution of experimental gingivitis.
doi:10.1111/j.1600-051X.2011.01719.x
PMCID: PMC3413194  PMID: 21501207
Experimental gingivitis; microarray; gene expression; tissue response
5.  Periodontal microbiota and phospholipases: The Oral Infections and Vascular Disease Epidemiology Study (INVEST) 
Atherosclerosis  2015;242(2):418-423.
Objective
Periodontal infections have been linked to cardiovascular disease, including atherosclerosis, and systemic inflammation has been proposed as a possible mediator. Secretory phospholipase A2 (s-PLA2) and Lipoprotein-associated PLA2 (Lp-PLA2) are inflammatory enzymes associated with athero-sclerosis. No data are available on the association between oral microbiota and PLA2s. We studied whether a relationship exists between periodontal microbiota and the activities of these enzymes.
Methods
The Oral Infection and Vascular Disease Epidemiology Study (INVEST) collected subgingival biofilms and serum samples from 593 dentate men and women (age 68.7 ± 8.6 years). 4561 biofilm samples were collected in the two most posterior teeth of each quadrant (average 7/participant) for quantitative assessment of 11 bacterial species using DNA–DNA checkerboard hybridization. Mean concentration of s-PLA2 and activities of s-PLA2 and Lp-PLA2 were regressed on tertiles of etiologic dominance (ED). ED is defined as the level of presumed periodontopathic species/combined level of all eleven species measured, and represents the relative abundance of periodontopathic organisms. Analyses were adjusted for age, sex, race/ethnicity, education, smoking, BMI, diabetes, LDL cholesterol and HDL cholesterol, and systolic blood pressure.
Results
Higher levels of s-PLA2 activity were observed across increasing tertiles of etiologic dominance (0.66 ± 0.04 nmol ml−1 min−1, 0.73 ± 0.04 nmol ml−1 min−1, 0.89 ± 0.04 nmol ml−1 min−1; p < 0.001), with also a trend of association between Lp-PLA2 activity and ED (p = 0.07), while s-PLA2 concentration was unrelated to ED.
Conclusion
Increasingly greater s-PLA2 activity at higher tertiles of etiologic dominance may provide a mechanistic explanatory link of the relationship between periodontal microbiota and vascular diseases. Additional studies investigating the role of s-PLA2 are needed.
doi:10.1016/j.atherosclerosis.2015.07.039
PMCID: PMC4862208  PMID: 26282947
Periodontitis; Phospholipases; Cardiovascular diseases; Atherosclerosis
6.  GRANULOCYTE CHEMOTACTIC PROTEIN 2 (GCP-2/CXCL6) COMPLEMENTS INTERLEUKIN 8 IN PERIODONTAL DISEASE 
Journal of periodontal research  2008;44(4):465-471.
Objectives
Mucosal inflammatory responses are orchestrated largely by proinflammatory chemokines. We aimed to evaluate the expression of the chemokine GCP-2 in clinically healthy vs. diseased gingival tissues and to explore possible correlations with clinical and microbiological markers of periodontitis.
Background
The chemokine granulocyte chemotactic protein 2 (GCP-2/CXCL6) is involved in neutrophil recruitment and migration. Previous studies showed that GCP-2 is upregulated in mucosal inflammation, e.g., in inflammatory bowel disease, similarly to the functionally and structurally related chemokine interleukin 8 (IL-8). Nevertheless, unlike IL-8, a role of GCP-2 in gingival inflammation has not yet been demonstrated.
Methods
Gene expression in 184 ‘diseased’ and 63 ‘healthy’ gingival tissue specimens from 90 periodontitis patients was analyzed using Affymetrix U133Plus2.0 arrays. GCP-2 expression was further confirmed by real time RT-PCR, western blotting and ELISA while the localization of GCP-2 protein in the gingival tissues was analyzed by immunohistochemistry. Plaque samples from the adjacent periodontal pockets were collected and evaluated for 11 periodontal species using checkerboard DNA-DNA hybridizations.
Results
Among all known chemokines, GCP-2 mRNA was the most expressed (3.8 fold, p<1.1×10−16) in ‘diseased’ vs. ‘healthy’ tissue, as compared to a 2.6 fold increased expression of IL-8 mRNA (p<1.2×10−15). Increased expression of GCP-2 correlated with higher levels of ‘red’ and ‘orange’ complex pathogens and with increased probing depth, but not with attachment loss. Immuno-histochemistry showed that GCP-2 was expressed in gingival vascular endothelium.
Conclusion
GCP-2 correlates with the severity of periodontitis and appears to act as a hitherto unrecognized functional adjunct to IL-8 in diseased gingival tissues.
doi:10.1111/j.1600-0765.2008.01134.x
PMCID: PMC2710406  PMID: 18842116
Periodontal disease; inflammatory mediator; Chemokines; Chemotaxis; Matrix metalloproteinase; Microarray
7.  HETEROGENEITY OF SYSTEMIC INFLAMMATORY RESPONSES TO PERIODONTAL THERAPY 
Aims
We investigated the effect of comprehensive periodontal therapy on the levels of multiple systemic inflammatory biomarkers.
Methods
Thirty patients with severe periodontitis received comprehensive periodontal therapy within a 6-week period. Blood samples were obtained at: one week pre- therapy (T1), therapy initiation (T2), treatment completion (T3), and 4 weeks thereafter (T4). We assessed plasma concentrations of 19 biomarkers using multiplex assays, and serum IgG antibodies to periodontal bacteria using checkerboard immunoblotting. At T2 and T4, dental plaque samples were analyzed using checkerboard hybridizations.
Results
At T3, PAI-1, sE-selectin, sVCAM-1, MMP-9, myeloperoxidase, and a composite Summary Inflammatory Score (SIS) were significantly reduced. However, only sE-selectin, sICAM, and serum amyloid P sustained a reduction at T4. Responses were highly variable: analyses of SIS slopes between baseline and T4 showed that approximately 1/3 and 1/4 of the patients experienced marked reduction and pronounced increase in systemic inflammation, respectively, while the remainder were seemingly unchanged. Changes in inflammatory markers correlated poorly with clinical, microbiological and serological markers of periodontitis.
Conclusions
Periodontal therapy resulted in an overall reduction of systemic inflammation, but the responses were inconsistent across subjects and largely not sustainable. The determinants of this substantial heterogeneity need to be explored further.
doi:10.1111/j.1600-051X.2009.01382.x
PMCID: PMC2753407  PMID: 19426174
Periodontal therapy; inflammatory mediators; systemic inflammation; atherosclerotic vascular disease
8.  Transcriptomes in Healthy and Diseased Gingival Tissues 
Journal of periodontology  2008;79(11):2112-2124.
Objectives
Clinical and radiographic measures are gold standards for diagnosing periodontitis but offer little information regarding the pathogenesis of the disease. We hypothesized that a comparison of gene expression signatures between healthy and diseased gingival tissues would provide novel insights in the pathobiology of periodontitis, and would inform the design of future studies.
Methods
Ninety systemically healthy non-smokers with moderate to advanced periodontitis (63 with chronic and 27 with aggressive periodontitis) each contributed with ≥2 “diseased” interproximal papillae [with bleeding on probing (BoP), pocket depth (PD) ≥4mm, and attachment loss (AL) ≥3mm)] and a “healthy” papilla, if available (no BoP, PD ≤4mm and AL ≤2mm). RNA was extracted, amplified, reverse-transcribed, labeled, and hybridized with AffymetrixU133Plus2.0 arrays. Differential expression was assayed in 247 individual tissue samples (183 from diseased and 64 from healthy sites) using a standard mixed-effects linear model approach, with patient effects considered random with a normal distribution, and gingival tissue status considered a two-level fixed effect. Gene ontology analysis summarized the expression patterns into biologically relevant categories.
Results
Transcriptome analysis revealed that a total of 12,744 probe sets were differentially expressed after adjusting for multiple comparisons (p<9.15×10-7). Of those, 5,295 were up-regulated and 7,449 down-regulated in disease when compared to health. Gene ontology analysis identified 61 differentially expressed groups (adjusted p<0.05) including apoptosis, antimicrobial humoral response, antigen presentation, regulation of metabolic processes, signal transduction, and angiogenesis.
Conclusions
Gingival tissue transcriptomes provide a valuable scientific tool for further hypothesis-driven studies of the pathobiology of periodontitis.
doi:10.1902/jop.2008.080139
PMCID: PMC2637651  PMID: 18980520
Periodontitis; genomics; infection; gene expression; microarray
9.  Periodontal therapy alters gene expression of peripheral blood monocytes 
Aims
We investigated the effects of periodontal therapy on gene expression of peripheral blood monocytes.
Methods
Fifteen patients with periodontitis gave blood samples at four time points: 1 week before periodontal treatment (#1), at treatment initiation (baseline, #2), 6-week (#3) and 10-week post-baseline (#4). At baseline and 10 weeks, periodontal status was recorded and subgingival plaque samples were obtained. Periodontal therapy (periodontal surgery and extractions without adjunctive antibiotics) was completed within 6 weeks. At each time point, serum concentrations of 19 biomarkers were determined. Peripheral blood monocytes were purified, RNA was extracted, reverse-transcribed, labelled and hybridized with AffymetrixU133Plus2.0 chips. Expression profiles were analysed using linear random-effects models. Further analysis of gene ontology terms summarized the expression patterns into biologically relevant categories. Differential expression of selected genes was confirmed by real-time reverse transcriptase-polymerase chain reaction in a subset of patients.
Results
Treatment resulted in a substantial improvement in clinical periodontal status and reduction in the levels of several periodontal pathogens. Expression profiling over time revealed more than 11,000 probe sets differentially expressed at a false discovery rate of <0.05. Approximately 1/3 of the patients showed substantial changes in expression in genes relevant to innate immunity, apoptosis and cell signalling.
Conclusions
The data suggest that periodontal therapy may alter monocytic gene expression in a manner consistent with a systemic anti-inflammatory effect.
doi:10.1111/j.1600-051X.2007.01113.x
PMCID: PMC2670555  PMID: 17716309
atherosclerosis; cytokines; genomics; infection; inflammation; periodontitis
10.  Periodontal Infection, Impaired Fasting Glucose and Impaired Glucose Tolerance: Results from The Continuous National Health and Nutrition Examination Survey 2009–2010 
Aim
We investigated the relationship between periodontal disease, a clinical manifestation of periodontal infection, and prediabetes.
Methods
The National Health and Nutrition Examination Survey, 2009–2010 enrolled 1,165 diabetes-free adults (51% female) aged 30–80 years (mean ± SD=50±14) who received a full-mouth periodontal examination and an oral glucose tolerance test. Participants were classified as having none/mild, moderate or severe periodontitis and also according to mean probing depth≥2.19 mm or attachment loss≥1.78 mm, (respective 75th percentiles). Pre-diabetes was defined according to ADA criteria as either: i) impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). In multivariable logistic regression models, the odds of IFG and IGT were regressed on levels of periodontitis category.
Results
The odds ratios and 95% confidence intervals for having IGT among participants with moderate or severe periodontitis, relative to participants with none/mild periodontitis were 1.07[0.50,2.25] and 1.93[1.18,3.17], P=0.02. The ORs for having IFG were 1.14[0.74, 1.77] and 1.12[0.58, 2.18], P =0.84. PD≥75th percentile was related to a 105% increase in the odds of IGT: OR[95%CI] =2.05[1.24, 3.39], P=0.005.
Conclusions
Periodontal infection was positively associated with prevalent impaired glucose tolerance in a cross-sectional study among a nationally representative sample.
doi:10.1111/jcpe.12258
PMCID: PMC4072528  PMID: 24708451
11.  Serum IgG Antibody Levels to Periodontal Microbiota Are Associated with Incident Alzheimer Disease 
PLoS ONE  2014;9(12):e114959.
Background
Periodontitis and Alzheimer disease (AD) are associated with systemic inflammation. This research studied serum IgG to periodontal microbiota as possible predictors of incident AD.
Methods
Using a case-cohort study design, 219 subjects (110 incident AD cases and 109 controls without incident cognitive impairment at last follow-up), matched on race-ethnicity, were drawn from the Washington Heights-Inwood Columbia Aging Project (WHICAP), a cohort of longitudinally followed northern Manhattan residents aged >65 years. Mean follow-up was five years (SD 2.6). In baseline sera, serum IgG levels were determined for bacteria known to be positively or negatively associated with periodontitis (Porphyromonas gingivalis, Tannerella forsythia, Actinobacillus actinomycetemcomitans Y4, Treponema denticola, Campylobacter rectus, Eubacterium nodatum, and Actinomyces naeslundii genospecies-2). In all analyses, we used antibody threshold levels shown to correlate with presence of moderate-severe periodontitis.
Results
Mean age was 72 years (SD 6.9) for controls, and 79 years (SD 4.6) for cases (p<0.001). Non-Hispanic Whites comprised 26%, non-Hispanic Blacks 27%, and Hispanics 48% of the sample. In a model adjusting for baseline age, sex, education, diabetes mellitus, hypertension, smoking, prior history of stroke, and apolipoprotein E genotype, high anti-A. naeslundii titer (>640 ng/ml, present in 10% of subjects) was associated with increased risk of AD (HR = 2.0, 95%CI: 1.1–3.8). This association was stronger after adjusting for other significant titers (HR = 3.1, 95%CI: 1.5–6.4). In this model, high anti-E. nodatum IgG (>1755 ng/ml; 19% of subjects) was associated with lower risk of AD (HR = 0.5, 95%CI: 0.2–0.9).
Conclusions
Serum IgG levels to common periodontal microbiota are associated with risk for developing incident AD.
doi:10.1371/journal.pone.0114959
PMCID: PMC4270775  PMID: 25522313
12.  Systemic Immune Responses in Pregnancy and Periodontitis: Relationship to Pregnancy Outcomes in the Obstetrics and Periodontal Therapy (OPT) Study 
Journal of periodontology  2009;80(6):953-960.
Background
Our previous studies reported on the obstetric, periodontal, and microbiologic outcomes of women participating in the Obstetrics and Periodontal Therapy (OPT) Study. This article describes the systemic antibody responses to selected periodontal bacteria in the same patients.
Methods
Serum samples, obtained from pregnant women at baseline (13 to 16 weeks; 6 days of gestation) and 29 to 32 weeks, were analyzed by enzyme-linked immunosorbent assay for serum immunoglobulin G (IgG) antibody to Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia (previously T. forsythensis), and Treponema denticola.
Results
At baseline, women who delivered live preterm infants had significantly lower total serum levels of IgG antibody to the panel of periodontal pathogens (P = 0.0018), to P. gingivalis (P = 0.0013), and to F. nucleatum (P = 0.0200) than women who delivered at term. These differences were not significant at 29 to 32 weeks. Changes in IgG levels between baseline and 29 to 32 weeks were not associated with preterm birth when adjusted for treatment group, clinical center, race, or age. In addition, delivery of low birth weight infants was not associated with levels of antibody at baseline or with antibody changes during pregnancy.
Conclusions
Live preterm birth is associated with decreased levels of IgG antibody to periodontal pathogens in women with periodontitis when assessed during the second trimester. Changes in IgG antibody during pregnancy are not associated with birth outcomes.
doi:10.1902/jop.2009.080464
PMCID: PMC4133130  PMID: 19485826
Antibody; bacteria; periodontitis; pregnancy; preterm birth
13.  Discovering medical conditions associated with periodontitis using linked electronic health records 
Journal of clinical periodontology  2013;40(5):10.1111/jcpe.12086.
Aim
To use linked electronic medical and dental records to discover associations between periodontitis and medical conditions independent of a priori hypotheses.
Materials and Methods
This case-control study included 2475 patients who underwent dental treatment at the College of Dental Medicine at Columbia University and medical treatment at NewYork-Presbyterian Hospital. Our cases are patients who received periodontal treatment and our controls are patients who received dental maintenance but no periodontal treatment. Chi-square analysis was performed for medical treatment codes and logistic regression was used to adjust for confounders.
Results
Our method replicated several important periodontitis associations in a largely Hispanic population, including diabetes mellitus type I (OR = 1.6, 95% CI 1.30–1.99, p < 0.001) and type II (OR = 1.4, 95% CI 1.22–1.67, p < 0.001), hypertension (OR = 1.2, 95% CI 1.10–1.37, p < 0.001), hypercholesterolaemia (OR = 1.2, 95% CI 1.07–1.38, p = 0.004), hyperlipidaemia (OR = 1.2, 95% CI 1.06–1.43, p = 0.008) and conditions pertaining to pregnancy and childbirth (OR = 2.9, 95% CI: 1.32–7.21, p = 0.014). We also found a previously unreported association with benign prostatic hyperplasia (OR = 1.5, 95% CI 1.05–2.10, p = 0.026) after adjusting for age, gender, ethnicity, hypertension, diabetes, obesity, lipid and circulatory system conditions, alcohol and tobacco abuse.
Conclusions
This study contributes a high-throughput method for associating periodontitis with systemic diseases using linked electronic records.
doi:10.1111/jcpe.12086
PMCID: PMC3690348  PMID: 23495669
data linkage; dental records; electronic health records; medical informatics; periodontal diseases
14.  Periodontal Infection and Cardiorespiratory Fitness in Younger Adults: Results from Continuous National Health and Nutrition Examination Survey 1999–2004 
PLoS ONE  2014;9(3):e92441.
Objective
Previous studies report associations between periodontal infection and cardiorespiratory fitness but no study has examined the association among younger adults. Our objective was to study the association between clinical measures of periodontal infection and cardiorespiratory fitness levels among a population-based sample of younger adults.
Methods
The Continuous National Health and Nutrition Examination Survey 1999–2004 enrolled 2,863 participants (46% women) who received a partial-mouth periodontal examination and completed a submaximal treadmill test for the assessment of estimated VO2 max(eVO2 max ). Participants were mean±SD age 33±9 years (range = 20–49 years), 30% Hispanic, 48% White, 19% Black, and 3% other. Mean eVO2 max (mL/kg/minute) as well as eVO2 max≤32 mL/kg/minute (20th percentile) were regressed across quartiles of mean probing depth and mean attachment loss in multivariable linear and logistic regression models.
Results
After multivariable adjustment, mean eVO2 max levels±SE across quartiles of attachment loss were 39.72±0.37, 39.64±0.34, 39.59±0.36, and 39.85±0.39 (P = 0.99). Mean eVO2 max±SE across quartiles of probing depth were 39.57±0.32, 39.78±0.38, 39.19±0.25, and 40.37±0.53 (P = 0.28). Similarly, multivariable adjusted mean eVO2 max values were similar between healthy participants vs. those with moderate/severe periodontitis: 39.70±0.21 vs. 39.70±0.90 (P = 1.00). The odds ratio (OR) for low eVO2 max comparing highest vs. lowest quartile of attachment loss = 0.89[95% CI 0.64–1.24]. The OR for comparing highest vs. lowest probing depth quartile = 0.77[95% CI 0.51–1.15].
Conclusion
Clinical measures of periodontal infection were not related to cardiorespiratory fitness in a sample of generally healthy younger adults.
doi:10.1371/journal.pone.0092441
PMCID: PMC3963905  PMID: 24663097
15.  Activation of Invariant Natural Killer T-cells in Periodontitis Lesions 
Periodontitis is one of the most prevalent human inflammatory diseases. The major clinical phenotypes of this polymicrobial, biofilm-mediated disease are chronic and aggressive periodontitis, the latter being characterized by a rapid course of destruction that is generally attributed to an altered immune-inflammatory response against periodontal pathogens. Still, the biological basis for the pathophysiological distinction of the two disease categories has not been well documented yet.
Type I natural killer T (NKT) cells are a lymphocyte subset with important roles in regulating immune responses to either tolerance or immunity, including immune responses against bacterial pathogens. Here, we delineate the mechanisms of NKT cell activation in periodontal infections.
We show an infiltration of type I NKT cells in aggressive, but not chronic periodontitis lesions in vivo. Murine DCs infected with aggressive periodontitis-associated Aggregatibacter actinomycetemcomitans triggered a type I interferon response followed by type I NKT cell activation. In contrast, infection with Porphyromonas gingivalis, a principal pathogen in chronic periodontitis, did not induce NKT cell activation. This difference could be explained by the absence of a type I interferon response to P. gingivalis infection. We found these interferons to be critical for NKT cell activation.
Our study provides a conceivable biological distinction between the two periodontitis subforms and identifies factors required for the activation of the immune system in response to periodontal bacteria.
doi:10.4049/jimmunol.1201215
PMCID: PMC3620697  PMID: 23365081
natural killer T cells; immune evasion; bacterial pathogenesis; Porphyromonas gingivalis; Aggregatibacter actinomycetemcomitans
16.  A comparison of periodontal status in the two regional, population-based studies of SHIP and INVEST 
Journal of clinical periodontology  2012;39(12):1115-1124.
Objectives
To compare the prevalence of periodontal disease between two randomly selected population-based studies (the Oral Infections and Vascular Disease Epidemiology Study (INVEST) and the Study of Health in Pomerania (SHIP)) and address relevant methodological issues.
Methods
Comparison was restricted to 55–81-years-olds. Attachment loss (AL), probing depth (PD), and tooth count were assessed in INVEST (full-mouth, six sites) and SHIP (half-mouth, four sites). Subjects were classified according to the CDC/AAP case definition. Recording protocols were standardized. Mixed linear or logistic models were used to compare INVEST with SHIP.
Results
Mean half-mouth AL was lower in INVEST vs. SHIP (INVEST: 2.9mm versus SHIP: 4.0mm, p<0.05). Findings were similar across multiple periodontal disease definitions. After equalisation of recording protocols and adjustment for periodontal risk factors, mean AL and PD were 1.2mm and 0.3mm lower in INVEST vs. SHIP (p<0.001). The odds for severe periodontitis (CDC/AAP) was 0.2-fold in INVEST vs. SHIP (p<0.001). Confounding effects of age, gender, race/ethnicity, education, and use of interdental care devices were highest as indicated by change-in-estimate for study.
Conclusion
Implementation of the proposed method for comparison of epidemiological studies revealed that periodontitis was less prevalent in INVEST compared to SHIP, even after extensive risk-factor adjustment.
doi:10.1111/jcpe.12018
PMCID: PMC3499632  PMID: 23061920
Cross-cultural comparison; Periodontal disease; Attachment loss; Probing depth; Periodontal risk factors
17.  Changes in Clinical and Microbiological Periodontal Profiles Relate to Progression of Carotid Intima‐Media Thickness: The Oral Infections and Vascular Disease Epidemiology Study 
Background
No prospective studies exist on the relationship between change in periodontal clinical and microbiological status and progression of carotid atherosclerosis.
Methods and Results
The Oral Infections and Vascular Disease Epidemiology Study examined 420 participants at baseline (68±8 years old) and follow‐up. Over a 3‐year median follow‐up time, clinical probing depth (PD) measurements were made at 75 766 periodontal sites, and 5008 subgingival samples were collected from dentate participants (average of 7 samples/subject per visit over 2 visits) and quantitatively assessed for 11 known periodontal bacterial species by DNA‐DNA checkerboard hybridization. Common carotid artery intima‐medial thickness (CCA‐IMT) was measured using high‐resolution ultrasound. In 2 separate analyses, change in periodontal status (follow‐up to baseline), defined as (1) longitudinal change in the extent of sites with a ≥3‐mm probing depth (Δ%PD≥3) and (2) longitudinal change in the relative predominance of bacteria causative of periodontal disease over other bacteria in the subgingival plaque (Δetiologic dominance), was regressed on longitudinal CCA‐IMT progression adjusting for age, sex, race/ethnicity, diabetes, smoking status, education, body mass index, systolic blood pressure, and low‐density lipoprotein cholesterol and high‐density lipoprotein cholesterol. Mean (SE) CCA‐IMT increased during follow‐up by 0.139±0.008 mm. Longitudinal IMT progression attenuated with improvement in clinical or microbial periodontal status. Mean CCA‐IMT progression varied inversely across quartiles of longitudinal improvement in clinical periodontal status (Δ%PD≥3) by 0.18 (0.02), 0.16 (0.01), 0.14 (0.01), and 0.07 (0.01) mm (P for trend<0.0001). Likewise, mean CCA‐IMT increased by 0.20 (0.02), 0.18 (0.02), 0.15 (0.02), and 0.12 (0.02) mm (P<0.0001) across quartiles of longitudinal improvement in periodontal microbial status (Δetiologic dominance).
Conclusion
Longitudinal improvement in clinical and microbial periodontal status is related to a decreased rate of carotid artery IMT progression at 3‐year average follow‐up.
doi:10.1161/JAHA.113.000254
PMCID: PMC3886779  PMID: 24166489
atherosclerosis; infection; inflammation; periodontal; progression
18.  Periodontal Infection, Systemic Inflammation, and Insulin Resistance 
Diabetes Care  2012;35(11):2235-2242.
OBJECTIVE
Adverse microbial exposures might contribute to diabetogenesis. We hypothesized that clinical periodontal disease (a manifestation of microbial exposures in dysbiotic biofilms) would be related to insulin resistance among diabetes-free participants. The roles of inflammatory mediation and effect modification were also studied.
RESEARCH DESIGN AND METHODS
The continuous National Health and Nutrition Examination Survey 1999–2004 enrolled 3,616 participants (51% women) who received a periodontal examination and fasting blood draw. Participants were mean age (± SD) 43 ± 17 years and 28% Hispanic, 52% Caucasian, 17% African American, and 3% other. Log-transformed values of the homeostasis model assessment of insulin resistance (HOMA-IR) or HOMA-IR ≥3.30 (75th percentile) were regressed across full-mouth periodontal probing depth (PD) levels using linear and logistic models. White blood cell (WBC) count and C-reactive protein (CRP) were considered as either mediators or effect modifiers in separate analyses. Risk ratios (RRs) stem from marginal predictions derived from the logistic model. Results were adjusted for multiple periodontal disease and insulin resistance risk factors.
RESULTS
In linear regression, geometric mean HOMA-IR levels increased by 1.04 for every 1-mm PD increase (P = 0.007). WBC mediated 6% of the association (P < 0.05). Among participants with WBC ≤6.4 × 109, PD was unrelated to HOMA-IR ≥3.30. Fourth-quartile PD was associated with HOMA-IR ≥3.30 among participants with WBC >7.9 × 109; RR 2.60 (1.36–4.97) (P for interaction = 0.05). Findings were similar among participants with CRP >3.0 mg/L (P for interaction = 0.04).
CONCLUSIONS
Periodontal infection was associated with insulin resistance in a nationally representative U.S. sample of diabetes-free adults. These data support the role of inflammation as both mediator and effect modifier of the association.
doi:10.2337/dc12-0072
PMCID: PMC3476901  PMID: 22837370
19.  Diabetes and oral disease: implications for health professionals 
“Diabetes and Oral Disease: Implications for Health Professionals” was a one-day conference convened by the Columbia University College of Dental Medicine, the Columbia University College of Physicians and Surgeons, and the New York Academy of Sciences on May 4, 2011in New York City. The program included an examination of the bidirectional relationship between oral disease and diabetes and the inter-professional working relationships for the care of people who have diabetes. The overall goal of the conference was to promote discussion among the healthcare professions who treat people with diabetes, encourage improved communication and collaboration among them and ultimately, improve patient management of the oral and overall effects of diabetes. Attracting over 150 members of the medical and dental professions from eight different countries, the conference included speakers from academia and government and was divided into four sessions. This report summarizes the scientific presentations of the event.
doi:10.1111/j.1749-6632.2011.06460.x
PMCID: PMC3429365  PMID: 22409777
diabetes; oral disease; meeting report
20.  PERIODONTAL BACTERIA AND HYPERTENSION: The Oral Infections and Vascular Disease Epidemiology Study (INVEST) 
Journal of Hypertension  2010;28(7):1413-1421.
Objective
Chronic infections, including periodontal infections, may predispose to cardiovascular disease. We investigated the relationship between periodontal microbiota and hypertension. Methods and Results: 653 dentate men and women with no history of stroke or myocardial infarction were enrolled in INVEST. We collected 4533 subgingival plaque samples (average of 7 samples/subject). These were quantitatively assessed for 11 periodontal bacteria using DNA-DNA checkerboard hybridization. Cardiovascular risk factor measurements were obtained. Blood pressure and hypertension (systolic blood pressure≥140 mmHg, diastolic blood pressure≥90 mmHg or taking antihypertensive medication, or self-reported history) were each regressed on the level of bacteria: (1) considered causative of periodontal disease (etiologic bacterial burden); (2) associated with periodontal disease (putative bacterial burden); (3) associated with periodontal health (health associated bacterial burden). All analyses were adjusted for age, race/ethnicity, gender, education, body mass index, smoking, diabetes, LDL and HDL cholesterol. Etiologic bacterial burden was positively associated with both blood pressure and prevalent hypertension. Comparing the highest vs. lowest tertiles of etiologic bacterial burden, SBP was 9 mmHg higher, DBP was 5 mmHg higher (p for linear trend <0.001 in each case), and the odds ratio for prevalent hypertension was 3.05 (95%CI:1.60,5.82) after multivariable adjustment.
Conclusions
Our data provide evidence of a direct relationship between the levels of subgingival periodontal bacteria and both systolic and diastolic blood pressure as well as hypertension prevalence.
doi:10.1097/HJH.0b013e328338cd36
PMCID: PMC3403746  PMID: 20453665
infection; inflammation; hypertension; blood pressure; epidemiology; periodontitis
21.  Maternal Periodontitis Treatment and Child Neurodevelopment at 24 to 28 Months of Age 
Pediatrics  2011;127(5):e1212-e1220.
BACKGROUND:
Some maternal infections are associated with impaired infant cognitive and motor performance. Periodontitis results in frequent bacteremia and elevated serum inflammatory mediators.
OBJECTIVE:
The purpose of this study was to determine if periodontitis treatment in pregnant women affects infant cognitive, motor, or language development.
METHODS:
Children born to women who had participated in a previous trial were assessed between 24 and 28 months of age by using the Bayley Scales of Infant and Toddler Development (Third Edition) and the Preschool Language Scale (Fourth Edition). Information about the pregnancy, neonatal period, and home environment was obtained through chart abstractions, laboratory test results, and questionnaires. We compared infants born to women treated for periodontitis before 21 weeks' gestation (treatment group) or after delivery (controls). In unadjusted and adjusted analyses, associations between change in maternal periodontal condition during pregnancy and neurodevelopment scores were tested by using Student's t tests and linear regression.
RESULTS:
A total of 411 of 791 eligible mother/caregiver-child pairs participated. Thirty-seven participating children (9.0%) were born at <37 weeks' gestation. Infants in the treatment and control groups did not differ significantly for adjusted mean cognitive (90.7 vs 91.4), motor (96.8 vs 97.2), or language (92.2 vs 92.1) scores (all P > .5). Results were similar in adjusted analyses. Children of women who experienced greater improvements in periodontal health had significantly higher motor and cognitive scores (P = .01 and .02, respectively), although the effect was small (∼1-point increase for each SD increase in the periodontal measure).
CONCLUSION:
Nonsurgical periodontitis treatment in pregnant women was not associated with cognitive, motor, or language development in these study children.
doi:10.1542/peds.2010-3129
PMCID: PMC3081189  PMID: 21482606
child neurodevelopment; periodontitis; pregnancy; treatment
22.  Receptor for Advanced Glycation Endproducts mediates proatherogenic responses to periodontal infection in vascular endothelial cells 
Atherosclerosis  2010;212(2):451-456.
Objective
A link between periodontal infections and an increased risk for vascular disease has been demonstrated. Porphyromonas gingivalis, a major periodontal pathogen, localizes in human atherosclerotic plaques, accelerates atherosclerosis in animal models and modulates vascular cell function. The receptor for advanced glycation endproducts (RAGE) regulates vascular inflammation and atherogenesis. We hypothesized that RAGE is involved in P. gingivalis’s contribution to proatherogenic responses in vascular endothelial cells.
Methods and Results
Murine aortic endothelial cells (MAEC) were isolated from wild type C57BL/6 or RAGE−/− mice and were infected with P. gingivalis strain 381. P. gingivalis 381 infection significantly enhanced expression of RAGE in wild-type MAEC. Levels of proatherogenic advanced glycation endproducts (AGEs) and monocyte chemoattractant protein 1 (MCP-1) were significantly increased in wild-type MAEC following P. gingivalis 381 infection, but were unaffected in MAEC from RAGE−/− mice or in MAEC infected with DPG3, a fimbriae-deficient mutant of P. gingivalis 381. Consistent with a role for oxidative stress and an AGE-dependent activation of RAGE in this setting, both antioxidant treatment and AGE blockade significantly suppressed RAGE gene expression and RAGE and MCP-1 protein levels in P. gingivalis 381 infected human aortic endothelial cells (HAEC).
Conclusion
The present findings implicate for the first time the AGE-RAGE axis in the amplification of proatherogenic responses triggered by P. gingivalis in vascular endothelial cells.
doi:10.1016/j.atherosclerosis.2010.07.011
PMCID: PMC2952730  PMID: 20701913
RAGE; infection; P. gingivalis; periodontitis; endothelial cells; vascular inflammation; atherosclerosis
23.  Serum Inflammatory Mediators in Pregnancy: Changes Following Periodontal Treatment and Association with Pregnancy Outcomes 
Journal of periodontology  2009;80(11):1731-1741.
Objective
To determine: 1) if periodontal treatment in pregnant women before 21 weeks of gestation alters levels of inflammatory mediators in serum; and 2) if changes in these mediators are associated with birth outcomes.
Methods
823 pregnant women with periodontitis were randomly assigned to receive scaling and root planing before 21 weeks of gestation or after delivery. Serum obtained between 13 weeks and 16 weeks 6 days (study baseline) and 29–32 weeks gestation was analyzed for C-reactive protein, prostaglandin E2, matrix metalloproteinase-9, fibrinogen, endotoxin, interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α. Cox regression, multiple linear regression, t-tests, chi-square and Fisher’s exact tests were used to examine associations between the biomarkers, periodontal treatment, and gestational age at delivery and birthweight.
Results
796 women had baseline serum data; 620 had baseline and follow-up serum and birth data. Periodontal treatment did not significantly alter the level of any biomarker (P>0.05). Neither baseline levels nor change from baseline in any biomarker was significantly associated with preterm birth or infant birthweight (P>0.05). In treatment subjects, change in endotoxin was negatively associated with change in probing depth (P<0.05).
Conclusions
Non-surgical mechanical periodontal treatment in pregnant women delivered before 21 weeks of gestation did not reduce systemic (serum) markers of inflammation. In pregnant women with periodontitis, levels of these markers at 13–17 weeks and 29–32 weeks gestation were not associated with risk for preterm birth or with infant birthweight.
doi:10.1902/jop.2009.090236
PMCID: PMC2922720  PMID: 19905943
Pregnancy; preterm birth; periodontitis; inflammation; cytokines
24.  PERIODONTAL DISEASE AND MACROVASCULAR DISEASE: WHAT IS THE EVIDENCE? 
Journal of dentistry  2009;37(8):S581-S582.
doi:10.1016/j.jdent.2009.05.016
PMCID: PMC2730464  PMID: 19487063
25.  Change in Periodontitis during Pregnancy and Risk of Preterm Birth and Low Birthweight 
Aim
Determine if periodontitis progression during pregnancy is associated with adverse birth outcomes.
Materials and Methods
We used clinical data and birth outcomes from the OPT Study, which randomized women to receive periodontal treatment before 21 weeks gestation (N=413) or after delivery (410). Birth outcomes were available for 812 women and follow-up periodontal data for 722, including 75 whose pregnancies ended <37 weeks. Periodontitis progression was defined as ≥ 3mm loss of clinical attachment. Birth outcomes were compared between non-progressing and progressing groups using the log rank and t tests, separately in all women and in untreated controls.
Results
The distribution of gestational age at the end of pregnancy (P > 0.1) and mean birthweight (3295 versus 3184 grams, P = 0.11) did not differ significantly between women with and without disease progression. Gestational age and birthweight were not associated with change from baseline in percent of tooth sites with bleeding on probing or between those who did versus did not progress according to a published definition of disease progression (P > 0.05).
Conclusions
In these women with periodontitis and within this study’s limitations, disease progression was not associated with increased risk for delivering a preterm or low birthweight infant.
Clinical Relevance
Scientific Rationale
Maternal periodontitis and disease progression during pregnancy have been associated with elevated risk for preterm birth. We used data from a recent clinical trial to explore possible associations between progressive periodontitis and birth outcomes.
Principal Findings
The distribution of gestational age at delivery and mean birthweights did not differ significantly between women who experienced progressive periodontitis and those who did not.
Clinical Implication
While it is important to treat dental diseases, including periodontitis, during pregnancy, women whose periodontal condition worsens during pregnancy are not at elevated risk for adverse pregnancy outcomes.
doi:10.1111/j.1600-051X.2009.01385.x
PMCID: PMC2741139  PMID: 19426177
preterm birth; low birthweight; periodontal disease; pregnancy; disease progression

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