Effects of obesity on gingival oxidative stress in a rat model

Association between relative fat mass and periodontitis: results from NHANES 2009-2014

Relative fat mass (RFM) is a novel indicator for measuring body fat. This cross-section study aims to explore the association between RFM and periodontitis and to investigate possible effect modifiers in U.S. adults based on the National Health and Nutrition Examination Survey 2009-2014. The category of periodontitis was defined by the CDC/AAP. Mean clinical attachment loss and mean pocket probing depth (PPD) were calculated. The RFM formula is: 64 - (20 × height/WC) + (12 × sex), with sex coded as 1 for female and 0 for male. Natural cubic spline and weighted multivariable regression analyses were conducted to investigate the relationship between RFM and periodontal status. Subgroup and interaction analyses were also employed to assess the moderating roles of age, gender, and race. A total of 10,307 participants were included in our study. Compared to the lowest quartiles, individuals in the highest quartiles of RFM levels were more likely to have moderate/severe periodontitis (ORQ4vs1 = 1.64, 95% CI 1.30-2.06) and had a higher mean PPD (βQ4vs1 = 0.15, 95% CI 0.09-0.22). This association was particularly stronger in populations under the age of 60, with significant interactions. Taken together, RFM is positively associated with periodontitis, particularly in those under 60 years old.

Is Obesity a Risk Factor for Periodontal Disease in Adults? A Systematic Review

There is inconclusive evidence about the link between the severity and prevalence of periodontitis in obese adults. Therefore, this systematic review aims to explore the possibility of significant evidence on the association between obesity and periodontitis and to determine the necessity to consider obesity as a risk factor for periodontitis. We followed the PRISMA protocol, and studies that met the eligibility criteria were included in this review. The risk of bias in individual studies was also evaluated. This review included 15 observational studies (9 cross-sectional studies, 2 case-control, and 4 cohort studies). The total study subjects from these studies were 6603 (males = 3432; females = 3171). Most studies showed a significant association between obesity and periodontitis. Among these studies, a few showed obese females to be at a higher risk, and one study found no association between obesity and periodontal disease at all. Based on the evidence obtained from this review, the body mass index (BMI) should be routinely assessed in patients to assess the risk for periodontal disease and to offer personalized management of periodontitis. Based on the findings of this review, we recommend the need to initiate awareness among clinicians and implement dental hygiene care prevention measures for obese patients.

Protective Effect of Virgin Coconut Oil on Osteopenia Induced by High Refined Carbohydrate-Containing Diet in Mice

Background: Obesity leads to chronic low-grade inflammation, promoting detrimental effects on bone. The consumption of virgin coconut oil (VCO) is associated with benefits related to meta-inflammation. We evaluated the effect of VCO supplementation on osteopenia promoted by diet-induced obesity in mice. Methods: Male BALB/c mice were fed a control (C) or highly refined carbohydrate-containing (HC) diet for eight weeks. After that, the HC diet group was supplemented with three doses of VCO for four weeks. Results: The HC diet increased the adiposity and leptin levels associated with augmented systemic inflammatory cells improved with VCO supplementation. The HC diet reduced the trabecular bone in the tibia, lumbar vertebrae, distal and proximal femur, as well as the bone mineral density of the femur and alveolar bone. The VCO supplementation reverted bone osteopenia by increasing the trabecular bone in different sites and improving femur and alveolar bone microarchitecture. Although the reduced number of osteoblasts in the alveolar bone of the HC diet group was not significantly enhanced by VCO supplementation, the reduced Alp expression in the HC diet group was enhanced in the VCO group. These beneficial effects were associated with lowering the Rankl/Opg ratio. Conclusion: VCO supplementation might be an effective strategy to attenuate bone osteopenic effects induced by obesity.

Obesity, Bone Loss, and Periodontitis: The Interlink

Obesity and periodontitis are both common health concerns that have given rise to considerable economic and societal burden worldwide. There are established negative relationships between bone metabolism and obesity, obesity and diabetes mellitus (DM), and DM and periodontitis, to name a few, with osteoporosis being considered a long-term complication of obesity. In the oral cavity, bone metabolic disorders primarily display as increased risks for periodontitis and alveolar bone loss. Obesity-driven alveolar bone loss and mandibular osteoporosis have been observed in animal models without inoculation of periodontopathogens. Clinical reports have also indicated a possible association between obesity and periodontitis. This review systematically summarizes the clinical periodontium changes, including alveolar bone loss in obese individuals. Relevant laboratory-based reports focusing on biological interlinks in obesity-associated bone remodeling via processes like hyperinflammation, immune dysregulation, and microbial dysbiosis, were reviewed. We also discuss the potential mechanism underlying obesity-enhanced alveolar bone loss from both the systemic and periodontal perspectives, focusing on delineating the practical considerations for managing periodontal disease in obese patients.

Association between serum miRNAs and gingival gene expression in an obese rat model

INTRODUCTION

Recent studies have reported a relationship between periodontitis and obesity; however, the mechanisms of obesity's effects on periodontitis are not well understood. On the other hand, microRNAs (miRNAs) are known to play key roles in the post-transcriptional regulation gene expression by suppressing translation and protein synthesis. We examined the association between obesity-related miRNAs and gene expression in gingival tissue using miRNA-messenger RNA (mRNA) pairing analysis in an obese rat model.

METHODS

Sixteen male Wistar rats aged 8 weeks old were divided into two groups: the control group was fed a normal powdered food for 8 weeks, and the obesity group was fed a high-fat diet for 8 weeks. Distance from the cement-enamel junction to the alveolar bone crest of the first molars was measured. miRNA microarray analysis was performed on samples of serum and gingival tissue; the resulting data were used to calculate fold changes in miRNA levels in the obesity group relative to the control group, and miRNA-mRNA pairing analysis was performed to identify mRNAs potentially targeted by miRNAs of interest.

RESULTS

Alveolar bone loss in the obesity group exceeded that in the control group (p = .017). miRNA-mRNA pairing analysis identified an association between 4 miRNAs (miR-759, miR-9a-3p, miR-203b-3p, and miR-878) that were differentially expressed in the obesity and control groups and 7 genes (Ly86, Arid5b, Rgs18, Mlana, P2ry13, Kif1b, and Myt1) expressed in gingival tissue.

CONCLUSION

This study revealed that several miRNAs play an important role in the mechanism of periodontal disease progression induced by the obesity.

The relationship between body mass index and stage/grade of periodontitis: a retrospective study

OBJECTIVES

Possible impact of obesity on stage and grade of periodontitis has never been investigated before. This study aimed to examine the association between body mass index (BMI) and stage/grade of periodontitis per the current classification of periodontal diseases.

MATERIAL AND METHODS

A total of 142 patients (82 males/60 females) were included in this study. "2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions" was taken as basis to characterize the stage/grade of periodontitis. Age, gender, smoking status, and frequency of tooth brushing, and medical data of the patients including hypertension, hyperlipidemia, BMI, and diabetes mellitus were obtained from the patient's hospital records. Obesity was assessed by BMI using the "World Health Organization" criteria. For estimating the association between BMI and periodontitis, logistic regression analysis was utilized.

RESULTS

BMI was statistically associated with clinical attachment loss (CAL), probing pocket depth (PPD), Plaque index (PI), stage and grade of periodontitis, and number of remaining teeth (p < 0.001, p < 0.05, p < 0.05, p < 0.05, p < 0.001, respectively). According to the multiple regression analysis results, those with BMI 25-29.9 were found to be at risk of being stage III-IV 3.977 times (95% CI: 1.831-8.640, p < 0.001) higher than those with BMI < 25, and similarly, those with BMI ≥ 30 were found to be at risk of being stage III-IV 4.062 times (95% CI: 1.315-12.549, p = 0.015) higher than those with BMI < 25. No relationship was found between obesity and grade of periodontitis according to multivariate analysis.

CONCLUSIONS

BMI increases the likelihood of stage III and stage IV periodontitis; however, it does not have an impact on the grade of periodontitis.

CLINICAL RELEVANCE

It seems that obesity is related to the severity of periodontitis.

Periodontitis is an inflammatory disease of oxidative stress: We should treat it that way

Periodontitis is a highly prevalent disease. As it progresses, it causes serious morbidity in the form of periodontal abscesses and tooth loss and, in the latter stages, pain. It is also now known that periodontitis is strongly associated with several nonoral diseases. Thus, patients with periodontitis are at greater risk for the development and/or exacerbation of diabetes, chronic obstructive pulmonary disease, and cardiovascular diseases, among other conditions. Although it is without question that specific groups of oral bacteria which populate dental plaque play a causative role in the development of periodontitis, it is now thought that once this disease has been triggered, other factors play an equal, and possibly more important, role in its progression, particularly in severe cases or in cases that prove difficult to treat. In this regard, we allude to the host response, specifically the notion that the host, once infected with oral periodontal pathogenic bacteria, will mount a defense response mediated largely through the innate immune system. The most abundant cell type of the innate immune system - polymorphonuclear neutrophils - can, when protecting the host from microbial invasion, mount a response that includes upregulation of proinflammatory cytokines, matrix metalloproteinases, and reactive oxygen species, all of which then contribute to the tissue damage and loss of teeth commonly associated with periodontitis. Of the mechanisms referred to here, we suggest that upregulation of reactive oxygen species might play one of the most important roles in the establishment and progression of periodontitis (as well as in other diseases of inflammation) through the development of oxidative stress. In this overview, we discuss both innate and epigenetic factors (eg, diabetes, smoking) that lead to the development of oxidative stress. This oxidative stress then provides an environment conducive to the destructive processes observed in periodontitis. Therefore, we shall describe some of the fundamental characteristics of oxidative stress and its effects on the periodontium, discuss the diseases and other factors that cause oxidative stress, and, finally, review potentially novel therapeutic approaches for the management (and possibly even the reversal) of periodontitis, which rely on the use of therapies, such as resveratrol and other antioxidants, that provide increased antioxidant activity in the host.

The association of periodontal diseases with metabolic syndrome and obesity

Periodontitis is a multifactorial chronic inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth-supporting apparatus. Globally, it is estimated that 740 million people are affected by its severe form. Periodontitis has been suggested to be linked to obesity and metabolic syndrome. Obesity, defined as excessive fat accumulation, is a complex multifactorial chronic inflammatory disease, with a high and increasing prevalence. Metabolic syndrome is defined as a cluster of obesity, dyslipidemia, hypertension, and dysglycemia. Obesity, metabolic syndrome and periodontitis are among the most common non-communicable diseases and a large body of evidence from epidemiologic studies supports the association between these conditions. Extensive research has established plausible mechanisms to explain how these conditions can negatively impact each other, pointing to a bidirectional adverse relationship. At present there is only limited evidence available from a few intervention studies. Nevertheless, the global burden of periodontitis combined with the obesity epidemic has important clinical and public health implications for the dental team. In accordance with the common risk factor approach for tackling non-communicable diseases, it has been proposed that oral healthcare professionals have an important role in the promotion of periodontal health and general well-being through facilitation of healthy lifestyle behaviours.

Influence of the treatment of periodontal disease in serum concentration of sirtuin 1 and mannose-binding lectin

BACKGROUND

Increased levels of periodontal pathogens disrupt the homeostasis between the host and its microbiota and increase susceptibility to periodontal diseases. Periodontitis increases the serum concentration of mannose-binding lectin (MBL), which exacerbates local inflammatory processes. In animal studies, sirtuin 1 (SIRT1) was associated with protection against inflammation. This study analyzed the influence of non-surgical periodontal treatment on serum levels of MBL and SIRT1.

METHODS

Forty patients with periodontitis and 38 periodontally healthy individuals (aged 45 to 79 years) were included. Periodontitis patients received scaling and root planing using machine driven and hand instruments. Clinical parameters, inflammatory biomarkers, MBL, and SIRT1 levels were measured at baseline and at post-treatment.

RESULTS

For all patients, an inverse correlation was observed between serum concentrations of MBL and SIRT1 (r = -0.30; P = 0.006). Periodontal treatment reduced serum concentrations of MBL (1,099.35 ± 916.59 to 861.42 ± 724.82 ng/mL; P < 0.001) and C-reactive protein (6.05 ± 8.99 to 2.49 ± 2.89 mg/L; P = 0.009). By contrast, SIRT1 serum levels increased (1.06 ± 1.03 to 1.66 ± 1.64 ng/mL; P < 0.001) following periodontal treatment.

CONCLUSIONS

Periodontal treatment was associated with decreased serum concentrations of MBL and CRP and increased serum levels of SIRT1. Prospective studies are needed to assess the impact of these biomarkers on pathophysiology of periodontitis.

Visualization of Oxidative Stress Induced by Experimental Periodontitis in Keap1-Dependent Oxidative Stress Detector-Luciferase Mice

The aim of this study was to investigate whether a Keap1-dependent oxidative stress detector-luciferase (OKD-LUC) mouse model would be useful for the visualization of oxidative stress induced by experimental periodontitis. A ligature was placed around the mandibular first molars for seven days to induce periodontitis. Luciferase activity was measured with an intraperitoneal injection of d-luciferin on days 0, 1, and 7. The luciferase activity in the periodontitis group was significantly greater than that in the control group at seven days. The expressions of heme oxygenase-1 (HO-1) and malondialdehyde in periodontal tissue were significantly higher in the periodontitis group than in the control group. Immunofluorescent analysis confirmed that the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) occurred more frequently in the periodontitis group than in the control group. This study found that under oxidative stress induced by experimental periodontitis, the Nrf2/antioxidant defense pathway was activated and could be visualized from the luciferase activity in the OKD-LUC model. Thus, the OKD-LUC mouse model may be useful for exploring the mechanism underlying the relationship between the Nrf2/antioxidant defense pathway and periodontitis by enabling the visualization of oxidative stress over time.

Oxidative Stress and Periodontal Disease in Obesity

Periodontal disease is a chronic inflammatory disease of the jaws and is more prevalent in obesity. Local and systemic oxidative stress may be an early link between periodontal disease and obesity. The primary aim of this study was to detect whether increased periodontal disease susceptibility in obese individuals is associated with local and systemic oxidative stress. Accordingly; we analyzed periodontal status and systemic (serum) and local (gingival crevicular fluid [GCF]) oxidative status markers in young obese women in comparison with age-matched lean women.Twenty obese and 20 lean women participated. Periodontal condition was determined by clinical periodontal indices including probing depth, clinical attachment level, gingival index, gingival bleeding index, and plaque index. Anthropometric, hormonal, and metabolic measurements were also performed. Blood and GCF sampling was performed at the same time after an overnight fasting. Serum and GCF total antioxidant capacity (TAOC), and total oxidant status (TOS) levels were determined, and oxidative stress index (OSI) was calculated.Clinical periodontal analyses showed higher gingival index and gingival bleeding index in the obese group (P = 0.001 for both) with no significant difference in probing depth, clinical attachment level, and plaque index between the obese and the lean women. Oxidant status analyses revealed lower GCF and serum TAOC, and higher GCF and serum OSI values in the obese women (P < 0.05 for all). GCF TOS was higher in the obese women (P < 0.05), whereas there was a nonsignificant trend for higher serum TOS in obese women (P = 0.074). GCF TAOC values showed a negative correlation with body mass index, whereas GCF OSI was positively correlated with fasting insulin and low-density lipoprotein-cholesterol levels (P < 0.05 for all). Clinical periodontal indices showed significant correlations with body mass index, insulin, and lipid levels, and also oxidant status markers.Our results suggest that young obese, otherwise healthy, women show findings of early periodontal disease (gingival inflammation) compared with age-matched healthy lean women, and that local/periodontal oxidative stress generated by obesity seems to be associated with periodontal disease.

Glutathione levels in plasma, saliva and gingival crevicular fluid after periodontal therapy in obese and normal weight individuals

BACKGROUND AND OBJECTIVE

The purpose of this study was to investigate the effects of obesity on reduced and oxidized glutathione (GSH and GSSG) levels in the gingival crevicular fluid, plasma and saliva of patients with chronic periodontitis and to evaluate the changes after nonsurgical periodontal therapy.

MATERIAL AND METHODS

The study included 60 patients: 30 patients with chronic periodontitis (15 obese patients and 15 normal weight patients) and 30 healthy control subjects (15 obese patients and 15 normal weight patients). Gingival crevicular fluid, plasma and saliva samples were collected, and clinical periodontal measurements were recorded at baseline and at the first month after periodontal therapy from patients with chronic periodontitis. GSH and GSSG levels were analyzed with spectrophotometry.

RESULTS

The GSH levels in the plasma, saliva and gingival crevicular fluid in obese individuals with chronic periodontitis were lower than in normal weight individuals at baseline (p < 0.01). There was a significant difference in the GSH/GSSG ratio in plasma and gingival crevicular fluid between the obese and normal weight groups at baseline (p < 0.01). The GSH levels in plasma, gingival crevicular fluid and saliva were significantly increased in both chronic periodontitis groups after nonsurgical periodontal therapy (p < 0.01). A significant positive correlation was found between GSH levels in saliva, plasma and gingival crevicular fluid in all groups (p < 0.001).

CONCLUSIONS

The study revealed that obesity in patients with chronic periodontitis is associated with decreased GSH levels and the GSH/GSSG ratio. Moreover, nonsurgical periodontal therapy may be helpful for improvement in glutathione values in obese and normal weight individuals with chronic periodontitis.

Ethical guidelines, animal profile, various animal models used in periodontal research with alternatives and future perspectives

Laboratory animal models serve as a facilitator to investigate the etiopathogenesis of periodontal disease, are used to know the efficacy of reconstructive and regenerative procedures, and are also helpful in evaluation of newer therapeutic techniques including laser and implant therapies prior to application in the human beings. The aim of this review is to know the different animal models used in various specialties of dental research and to know the ethical guidelines prior to the usage of experimental models with main emphasis on how to refine, replace, and reduce the number of animal models usage in the laboratory. An online search for experimental animal models used in dental research was performed using MEDLINE/PubMed database. Publications from 2009 to May 2013 in the specialty of periodontics were included in writing this review. A total of 652 references were published in PubMed/MEDLINE databases based on the search terms used. Out of 245 studies, 241 were related to the periodontal research published in English from 2009 to 2013. Relevant papers were chosen according to the inclusion and exclusion criteria. After extensive electronic and hand search on animal models, it has been observed that various animal models were used in dental research. Search on animal models used for dental research purpose revealed that various animals such as rats, mice, guinea pigs, rabbit, beagle dogs, goats, and nonhuman primates were extensively used. However, with the new advancement of ex vivo animal models, it has become easy to investigate disease pathogenesis and to test the efficacy of newer therapeutic modalities with the reduced usage of animal models. This review summarized the large amount of literature on animal models used in periodontal research with main emphasis on ethical guidelines and on reducing the animal model usage in future perspective.

The effect of initial periodontal treatment on plasma, gingival crevicular fluid and salivary levels of 8-hydroxy-deoxyguanosine in obesity

OBJECTIVE

Recent studies have shown adverse effects on the periodontium from the increased production of reactive oxygen species (ROS) in obesity. The purpose of this study was to investigate the effects of obesity on 8-hydroxy-deoxyguanosine (8-OHdG) levels in the bodily fluids of patients with and without periodontal disease and to evaluate changes after initial periodontal treatment.

DESIGN

Forty-five obese individuals and 45 normal-weight individuals were included in this study. Obese and normal-weight groups were classified into three sub-groups: chronic periodontitis (CP), gingivitis (G) and periodontally healthy controls (CTRL). Gingival crevicular fluid (GCF), plasma, saliva samples and clinical measurements were obtained at baseline and a month after initial periodontal treatment. Levels of 8-OHdG were analysed by ELISA.

RESULTS

While plasma 8-OHdG levels were significantly higher at baseline in the obese patients with periodontal disease than in the normal-weight individuals (P<0.05), no significant differences in GCF and saliva 8-OHdG levels were found (P ˃ 0.05). GCF and salivary 8-OHdG levels in obese patients with G and CP were significantly higher than in CTRL groups at baseline (P<0.05). After treatment, 8-OHdG levels were decreased in all groups with periodontal disease (P<0.01). Statistically significant positive correlations were observed between GCF 8-OHdG levels and GI in all the groups (P<0.001).

CONCLUSIONS

The significant increase of plasma 8-OHdG levels in obese patients did not correlate with saliva and GCF 8-OHdG levels when compared to normal-weight individuals. Periodontal treatment had a positive effect on the periodontal parameters and 8-OHdG levels of both obese and normal-weight individuals.

Relationship between increases in BMI and changes in periodontal status: a prospective cohort study

AIM

The purpose of this prospective cohort study was to investigate whether body mass index (BMI) and oral health behaviour are related to changes in periodontal status in Japanese university students.

MATERIALS AND METHODS

Students (n = 224) who were interested in receiving oral health examinations before entering university and before graduation were included in the analysis. Subjects were investigated regarding the correlations of oral health behaviours and increases in BMI with the percentage of bleeding on probing (%BOP) and Community Periodontal Index (CPI) scores as indicators of changes in periodontal status.

RESULTS

The risk of increased %BOP was associated with the non-use of dental floss (adjusted odds ratio [OR]: 3.11; 95% confidence interval [CI]: 1.31-7.37; p < 0.05), whereas the risk of increased CPI score was associated with increases in BMI (OR: 1.95; 95% CI: 1.05-3.65; p < 0.05) and simplified oral hygiene index score (OR: 2.28; 95% CI: 1.23-4.22; p < 0.01).

CONCLUSION

Increases in BMI were associated with worsening of periodontal status, defined as increased CPI score in Japanese university students, whereas lack of inter-dental cleaning was associated with exacerbated gingival bleeding.

Longitudinal relationship between plasma reactive oxygen metabolites and periodontal condition in the maintenance phase of periodontal treatment

Aim. The present cohort study describes the longitudinal relationship between plasma oxidative status and periodontitis progression during the maintenance phase of treatment. Materials and Methods. Forty-five patients (mean age 58.8 years) were monitored from 2008 to 2013. Periodontal conditions, including probing pocket depth (PPD) and clinical attachment level (CAL), were recorded. Measurements of plasma reactive oxygen metabolites (ROM) and biologic antioxidant potential (BAP) were performed to evaluate plasma oxidative status. The patients were assigned into 2 groups as low and high plasma ROM level using a cut-off value which was median of plasma ROM level at baseline. Results. In the subjects with low plasma ROM level at baseline, changes in mean CAL were positively correlated with changes in plasma ROM levels, bleeding on probing, and plaque control record, but not with PPD. In the subjects with high plasma ROM at baseline, changes in CAL were significantly associated with only PPD at baseline. On the other hands there were no significant associations between changes in CAL and those in plasma BAP levels. Conclusions. When plasma ROM level in periodontitis patients was low, increases in plasma ROM level were associated with those in CAL during the maintenance phase of treatment.

Obesity, periodontal and general health: Relationship and management

Obesity is a multifaceted subject. It has increased at an alarming rate in recent years. Being overweight increases the likelihood of a patient having associated health and social problems which may affect dental services and dental management. A review of the literature on obesity and periodontal disease suggested that they both confound each other and obesity itself has been recognized as a major risk factor for periodontal disease. It has been found that adverse effects of obesity on the periodontium may be mediated through pro-inflammatory cytokines and various other bioactive substances. This article tries to focus on the possible role of obesity and obesity-related diseases like diabetes and coronary heart diseases (CHD), as a potential contributor to periodontal disease and vice versa. The meanings of these associations can be useful for various diagnostic and treatment planning purposes.

Serum plasminogen activator inhibitor-1 and tumor necrosis factor-α levels in obesity and periodontal disease

BACKGROUND

Several studies have shown a possible association between periodontal disease and obesity. The aim of this study is to evaluate serum plasminogen activator inhibitor 1 (PAI-1), tumor necrosis factor-alpha (TNF-α), and high-sensitivity C-reactive protein (hsCRP) levels in the association between obesity and periodontal disease.

METHODS

Two hundred individuals participated in this study. Body mass index (BMI), waist-to-hip ratio, plasma triglyceride (TRG), total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG), hsCRP, TNF-α, PAI-1, and periodontal parameters (including plaque index [PI], probing depth [PD], clinical attachment level [CAL], and percentage of sites with bleeding on probing) were evaluated.

RESULTS

The groups with BMI ≥ 25 had higher median values for FBG, TRG, hsCRP, PAI-1, PI, and CAL than did the groups with a BMI < 25 (P <0.01). Serum TRG levels were positively correlated with PI, PD, and CAL. There were negative associations between clinical periodontal parameters and HDL-C. There were statistically significant correlations between PAI-1 and clinical periodontal parameters (PI, PD, and CAL).

CONCLUSION

Serum PAI-1 levels may play an important role in the association between periodontal disease and obesity.

Gingival RAGE expression in calorie-restricted versus ad libitum-fed rats

BACKGROUND

The receptor for advanced glycation end products (RAGE) is a multiligand receptor expressed in a number of cell types, including gingival epithelia. RAGE mediates inflammation and induces cellular oxidative stress. Upregulation of RAGE is associated with various diseases, such as periodontal and cardiovascular diseases. This study examines the hypothesis that the gingiva of rats fed a calorie-restriction (CR) diet expresses lower levels of RAGE than the gingiva of rats fed an ad libitum (AL) diet.

METHODS

Male F344BN rats (n = 16) from the National Institute on Aging (NIA) were fed a CR (n = 8) or AL (n = 8) diet according to NIA recommendations. Rats were sacrificed by guillotine at 8 (n = 5), 18 (n = 3), 29 (n = 4), and 38 (n = 4) months of age. The gingiva from around the molars was dissected and submitted for histologic and molecular analyses.

RESULTS

Immunohistochemistry revealed that RAGE was expressed in the plasma membrane and cytoplasm of gingival epithelial cells and endothelial cells from both groups. RAGE mRNA levels were quantified relative to levels of GAPDH mRNA by real-time reverse-transcriptase polymerase chain reaction. The mean relative RAGE mRNA level in the CR group (7.26 ± 0.54) was lower than in the AL group (10 ± 1.4) (P <0.05). There were no detectable differences in RAGE expression according to animal age.

CONCLUSION

Gingival RAGE expression in rats is reduced by calorie restriction.

Role of Porphyromonas gingivalis phosphoserine phosphatase enzyme SerB in inflammation, immune response, and induction of alveolar bone resorption in rats

Porphyromonas gingivalis secretes a serine phosphatase enzyme, SerB, upon contact with gingival epithelial cells in vitro. The SerB protein plays a critical role in internalization and survival of the organism in epithelial cells. SerB is also responsible for the inhibition of interleukin-8 (IL-8) secretion from gingival epithelial cells infected with P. gingivalis. This study examined the ability of a P. gingivalis SerB mutant to colonize the oral cavity and induce gingival inflammation, immune responses, and alveolar bone resorption in a rat model of periodontal disease. Both P. gingivalis ATCC 33277 and an isogenic ΔSerB mutant colonized the oral cavities of rats during the 12-week experimental period. Both of the strains induced significant (P < 0.05) systemic levels of immunoglobulin G (IgG) and isotypes IgG1, IgG2a, and IgG2b, indicating the involvement of both T helper type 1 (Th1) and Th2 responses to infection. Both strains induced significantly (P < 0.05) higher levels of alveolar bone resorption in infected rats than in sham-infected control rats. However, horizontal and interproximal alveolar bone resorption induced by the SerB mutant was significantly (P < 0.05) lower than that induced by the parental strain. Rats infected with the ΔSerB mutant exhibited significantly higher levels of apical migration of the junctional epithelium (P < 0.01) and polymorphonuclear neutrophil (PMN) recruitment (P < 0.001) into the gingival tissues than rats infected with the wild type. In conclusion, in a rat model of periodontal disease, the SerB phosphatase of P. gingivalis is required for maximal alveolar bone resorption, and in the absence of SerB, more PMNs are recruited into the gingival tissues.