The role of reactive oxygen and antioxidant species in periodontal tissue destruction

Evaluation of anti-inflammatory effects of systemically administered curcumin, lycopene and piperine as an adjunct to scaling and root planing: A clinical study

Background:

The natural herbal extracts curcumin (Curcuma longa), lycopene and piperine demonstrated a very potent anti-inflammatory action and can be used as an antioxidant therapy in the management of inflammatory processes such as gingivitis and periodontitis.

Aim and Objective:

The aim of the present study is to evaluate the effects of systemically administered extracts curcumin, lycopene and piperine as an adjunct to scaling and root planing (SRP) in patients with moderate gingivitis.

Materials and Methods:

Sixty systemically healthy participants with moderate gingivitis were enrolled in a randomized clinical study. Participants were randomly distributed into two treatment groups: Group I (test group) (350 mg/day antioxidant therapy) along with SRP for 3 weeks and Group II (control group) SRP alone. Clinical parameters such as plaque index, gingival index and probing pocket depth were evaluated at baseline and after 21 days using paired t-test.

Results:

Both the treatment groups showed statistically significant reduction in clinical parameters, but the test group showed greater reduction as compared to control group (P < 0.05).

Conclusion:

The results concluded that systemically administered antioxidants could cause better resolution of inflammation when used as an adjunct to SRP.

Salivary oxidative stress biomarkers in chronic periodontitis and acute coronary syndrome

OBJECTIVES

The study aimed at assessing oxidative stress (OS) biomarker levels in the saliva of patients with chronic periodontitis (CP) and acute coronary syndrome (ACS) and establishing their correlation to periodontal parameters and markers for cardiovascular events.

MATERIALS AND METHODS

The present study enrolled 24 patients with ACS and CP (the ACSCP group), 24 patients with ACS only (the ACS group), 24 patients with CP only (the CP group), and 24 healthy controls. Plaque index (PI), gingival index, bleeding on probing, probing pocket depth (PPD), and clinical attachment loss were recorded. Markers for cardiovascular events included serum high sensitivity C-reactive protein (hsCRP) and plasma fibrinogen. 8-Hydroxydeoxyguanosine (8-OHdG), protein carbonyl (PC), malondialdehyde (MDA), and total antioxidant capacity (TAOC) were used as OS biomarkers.

RESULTS

Salivary 8-OHdG, MDA, and PC levels were significantly higher in the ACSCP, ACS, and CP groups than in healthy controls (p < 0.05). There were significant correlations between salivary PC levels and PI or PPD (p < 0.05) as well as between salivary 8-OHdG levels and all periodontal parameters (p < 0.05). TAOC levels in saliva were correlated to both serum hsCRP and plasma fibrinogen (p < 0.05). Salivary MDA levels were correlated to all periodontal parameters and biomarkers for cardiovascular events (p < 0.05).

CONCLUSIONS

Salivary OS biomarker levels were higher in diseased groups compared to control. They also correlated to clinical periodontal parameters and markers for cardiovascular events in ACS patients, with or without CP.

CLINICAL RELEVANCE

Salivary OS biomarkers could potentially serve as diagnostic tools for cardiovascular and/or periodontal diseases.

A Comparative Evaluation of Serum Magnesium in Diabetes Mellitus Type 2 Patients with and without Periodontitis - A Clinico-biochemical Study

INTRODUCTION

Magnesium is an essential cation playing a crucial role in many physiological functions and its imbalance is associated with greater number of pathological situations. Oxidative stress is usually increased due to decreased essential nutrients. Hence, any imbalance of essential nutrients like serum magnesium can significantly play a role in the pathobiology of periodontitis in the presence of diabetes, as diabetes and chronic periodontitis are two chronic diseases that have been biologically linked.

AIM

To evaluate the association of serum magnesium in type 2 diabetes mellitus and chronic periodontitis patients, also to evaluate and associate the influence of serum magnesium on periodontal health.

MATERIALS AND METHODS

A single blinded, randomized study was conducted that comprised of 120 subjects divided into four groups. Individuals with periodontitis and type 2 diabetes mellitus formed the test group. Subjects with chronic periodontitis diagnosed clinically according to 1999 American Academy of Periodontology classification, without any medical history and drug history were included as the study subjects. Gingival Index and Plaque Index were scored for all the groups at baseline and after 21 days of scaling and root planing. Scaling and root planing was done only in the test group. Blood was drawn from the patients at baseline and 21 days after scaling and root planning and estimation of serum magnesium level was done using semi-autoanalyzer. Data obtained was statistically analyzed using the paired t-test, one-way ANOVA, post-hoc test.

RESULTS

The result of the present study showed that mean serum magnesium among healthy was 1.40±0.565mmol/l as compared to 1.01±0.287mmol/l among subjects with periodontitis, 0.920±0.23mmol/l among diabetics with periodontitis and 0.93±0.29mmol/l among diabetics without periodontitis. Serum magnesium was significantly decreased in chronic periodontitis and diabetic patients with and without chronic periodontitis as compared to controls.

CONCLUSION

Imbalance of serum magnesium level was seen in patients with chronic periodontitis and type 2 diabetes mellitus. Hence, it can be a biomarker which can predict the occurrence of type 2 diabetes mellitus and chronic 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.

Oral health and coronary heart disease

BACKGROUND

It is well documented that there is some correlation between poor oral health in the form of periodontal disease and coronary heart disease (CHD). It is unclear whether this correlation is due to a causal relationship or shared underlying disorder such as inflammation. A suitable integrated model of the CHD pathogenetic pathways relevant to periodontal disease may help to elucidate the association. Such a model is currently not available in literature.

METHODS

A previously developed integrated model of CHD was used to investigate potential pathogenetic pathways linking periodontal disease to CHD biomarkers.

RESULTS

The integrated model was created to provide insight into possible higher-order biological interactions underlying CHD and periodontal disease. In order to simplify these interactions a novel 'connection graph' was developed. It quantitatively illustrates the relationship between periodontal disease and various serological biomarkers of CHD. The pathogenesis of periodontitis shows various possible pathways which could link periodontitis to CHD pathogenesis.

CONCLUSION

An integrated model of CHD was developed which provides a summary of the potential CHD effects of periodontal disease. Further research must refine and validate the model.

Impact of non-surgical periodontal therapy on saliva and serum levels of markers of oxidative stress

OBJECTIVE

The purpose of this study was to determine the effect of non-surgical periodontal treatment on markers of oxidative stress in saliva and serum in patients with chronic periodontitis.

MATERIALS AND METHODS

In total, 25 patients, who were diagnosed with generalized chronic periodontitis (11 females and 14 males), and 26 systemically and periodontally healthy individuals (15 females and 11 males) were included. The plaque index (PI), gingival index (GI), probing pocket depth (PPD), attachment loss (AL), gingival recession (GR), and bleeding on probing (BOP) were recorded at baseline and 6 weeks later. Malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), and 4-hydroxy-2-nonenal (4-HNE) were assessed in saliva and serum samples before and after the non-surgical treatment by enzyme-linked immune sorbent assay (ELISA).

RESULTS

In the group with chronic periodontitis, all clinical parameters were significantly higher compared to the control group at baseline (p < 0.001). Periodontal treatment reduced plaque, gingival inflammation, and pocket depth significantly (p < 0.001). At baseline, salivary 8-OHdG was significantly higher in chronic periodontitis (p < 0.001) and reduced significantly subsequent to the periodontal treatment (p < 0.001). Salivary MDA and serum 4-HNE were significantly higher in the patients with periodontitis compared to the control group (p < 0.001). Periodontal treatment did not significantly change the levels of 4-HNE and salivary MDA (p = 0.503, p = 0.093).

CONCLUSIONS

Salivary 8-OHdG and MDA may be associated with local impact of periodontal disease, while 4-HNE may be associated with systemic impact of chronic periodontitis.

CLINICAL RELEVANCE

Clinical intervention in periodontitis may be beneficial for periodontitis patients' systemic oxidative stress control, and using lipidic agents for the use of anti-inflammatory/pro-resolving processes for blocking the actions of arachidonic acid cascade can enable some late therapeutic strategies in order to lead oxidative stress-induced inflammation.

Diabetes and increased lipid peroxidation are associated with systemic inflammation even in well-controlled patients

BACKGROUND

The effect of the interaction between type 2 diabetes and dyslipidemia on inflammation and lipid peroxidation (LPO) has not been assessed.

AIM

To investigate whether diabetes coupled with dyslipidemia alters oxidative metabolism leading to increased LPO products and inflammatory status.

METHODS

100 patients were divided into four groups based upon diabetic and dyslipidemic status: poorly controlled diabetes with dyslipidemia (DM-PC/D), well-controlled diabetes with dyslipidemia (DM-WC/D), normoglycemic individuals with dyslipidemia (NG/D), and normoglycemic individuals without dyslipidemia (NG/ND). Plasma was evaluated for an LPO product (MDA), antioxidant levels and inflammatory cytokines.

RESULTS

Diabetics presented significantly higher levels of LPO (p<0.05) and the DM-PC/D had higher levels of proinflammatory cytokines and MDA in the plasma in comparison with normoglycemics (p<0.05). Interestingly IL1-β, IL-6, and TNF-α in DM-WC/D were not statistically different from those in DM-PC/D. Normoglycemic individuals with dyslipidemia presented significantly increased levels of IL-6 and TNF-α when compared to normoglycemic without dyslipidemia (p<0.05). MDA levels were also positively correlated with the presence of DM complications (r=0.42, p<0.01).

CONCLUSIONS

These findings show that dyslipidemia is associated with an increased inflammatory status, even in well-controlled diabetics and in normoglycemics. Our results suggest that lipid metabolism and peroxidation are important for the development of inflammation, which is elevated in several complications associated with diabetes.

Oral polymorphonuclear neutrophil characteristics in relation to oral health: a cross-sectional, observational clinical study

Polymorphonuclear neutrophils (PMNs) have a major role in the innate immune system. However, little is known about PMN contribution in relation to oral health. The objective of this study was to investigate the numbers and functional characteristics of oral PMNs (oPMNs) compared with circulatory PMNs (cPMNs). Oral rinse and venous blood samples were obtained from 268 systemically and orally healthy volunteers in a cross-sectional observational study. PMN counts, cell cycle analysis and cellular activation state were investigated. Also, reactive oxygen species (ROS) production was analyzed, with and without bacterial stimulation (Fusobacterium nucleatum). In males, 1.2 × 10⁶±1.0 × 10⁶ oPMNs were collected, and showed a tendency to correlate with the levels of gingival bleeding (r=0.215, P=0.008). Comparable oPMNs counts were found among females (1.0 × 10⁶±0.7 × 10⁶). More late-stage apoptotic/necrotic cells were found among the oPMNs (53.1%) compared with the cPMNs (8.5% P<0.001). Without additional stimulation, oPMNs were more activated than cPMNs, as indicated by higher expression of CD11b, CD63 and CD66b, and higher constitutive ROS levels (P<0.001). Notably, in response to bacterial stimulation, oPMNs released comparable ROS levels as cPMNs (P=0.042). In conclusion, this study provides data on viable oPMNs showing high levels of activation in orally and systemically healthy individuals, free of apparent caries lesions and periodontal disease. These data suggests that although the oPMNs are in a more mature stage of their life cycle compared with the cPMNs, oPMNs are still responsive to stimulation, which indicates their functional potential and possible contribution to a healthy oral ecosystem.

Resolvin E1 Reverses Experimental Periodontitis and Dysbiosis

Periodontitis is a biofilm-induced inflammatory disease characterized by dysbiosis of the commensal periodontal microbiota. It is unclear how natural regulation of inflammation affects the periodontal biofilm. Promoters of active resolution of inflammation, including resolvin E1 (RvE1), effectively treat inflammatory periodontitis in animal models. The goals of this study were 1) to compare periodontal tissue gene expression in different clinical conditions, 2) to determine the impact of local inflammation on the composition of subgingival bacteria, and 3) to understand how inflammation impacts these changes. Two clinically relevant experiments were performed in rats: prevention and treatment of ligature-induced periodontitis with RvE1 topical treatment. The gingival transcriptome was evaluated by RNA sequencing of mRNA. The composition of the subgingival microbiota was characterized by 16S rDNA sequencing. Periodontitis was assessed by bone morphometric measurements and histomorphometry of block sections. H&E and tartrate-resistant acid phosphatase staining were used to characterize and quantify inflammatory changes. RvE1 treatment prevented bone loss in ligature-induced periodontitis. Osteoclast density and inflammatory cell infiltration in the RvE1 groups were lower than those in the placebo group. RvE1 treatment reduced expression of inflammation-related genes, returning the expression profile to one more similar to health. Treatment of established periodontitis with RvE1 reversed bone loss, reversed inflammatory gene expression, and reduced osteoclast density. Assessment of the rat subgingival microbiota after RvE1 treatment revealed marked changes in both prevention and treatment experiments. The data suggest that modulation of local inflammation has a major role in shaping the composition of the subgingival microbiota.

Gingival Crevicular Fluid and Plasma Levels of Transglutaminase-2 and Oxidative Stress Markers in Cyclosporin A-Induced Gingival Overgrowth

BACKGROUND

Transglutaminase (TGM)-2 has been shown to contribute to fibrosis by extracellular matrix accumulation in some organs and is activated by intracellular reactive oxygen species. The aim of this study is to investigate levels of gingival crevicular fluid (GCF) and plasma TGM-2 and oxidative stress markers (OSMs) in cyclosporin A (CsA)-induced gingival overgrowth (GO).

METHODS

The study enrolled 20 healthy (H) individuals; 20 patients with gingivitis (G); 20 CsA-medicated patients with GO (CsA GO+); and 20 CsA-medicated patients without GO (CsA GO-). GCF and plasma levels of TGM-2 were analyzed by enzyme-linked immunosorbent assay. Spectrofluorometry was used to analyze thiobarbituric acid reactive substance (TBARS); ferric-reducing antioxidant power (FRAP); total oxidant status (TOS); and total antioxidant capacity (TAC).

RESULTS

GCF TGM-2 level was elevated in CsA GO+ compared with G (P = 0.048) and H (P = 0.001) groups. GCF TBARS level was elevated in CsA GO+ compared with other groups (CsA GO- group: P = 0.003; G group: P <0.001; and H group: P <0.001) and was higher in CsA GO- than in H (P = 0.048). GCF FRAP level was lower in CsA GO- than in H (P = 0.04). Both CsA GO+ and CsA GO- groups had lower GCF TOS levels than H (P <0.001 and P = 0.002) and G (P = 0.003 and P = 0.04). GCF TAC was higher in CsA GO+ than in H (P = 0.02). Plasma TGM-2 level was elevated in CsA GO+ compared with G (P = 0.048) and H (P = 0.002). Plasma FRAP level was higher in H and CsA GO- than in CsA GO+ (P = 0.008 and P = 0.02).

CONCLUSIONS

CsA use significantly alters GCF and plasma levels of TGM-2 and OSMs. TGM-2 may contribute to CsA-induced GO in CsA-treated patients by changing GCF and plasma levels of OSMs. Further studies are needed to prove causality and its direction.

Acrolein-an α,β-Unsaturated Aldehyde: A Review of Oral Cavity Exposure and Oral Pathology Effects

Acrolein is a highly reactive unsaturated aldehyde widely present in the environment, particularly as a product of tobacco smoke. Our previous studies indicated the adverse consequences of even short-term acrolein exposure and proposed a molecular mechanism of its potential harmful effect on oral cavity keratinocytic cells. In this paper we chose to review the broad spectrum of acrolein sources such as pollution, food, and smoking. Consequently, in this paper we consider a high level of oral exposure to acrolein through these sources and discuss the noxious effects it has on the oral cavity including on salivary quality and contents, oral resistance to oxidative stress, and stress mechanism activation in a variety of oral cells.

Influence of Periodontal Clinical Status on Salivary Levels of Glutathione Reductase

BACKGROUND

Inadequate antioxidant balance may play a role in the excessive tissue breakdown in periodontitis. Because aggressive periodontitis (AgP) not only differs from chronic periodontitis (CP) in terms of clinical manifestations, this study investigates whether the salivary levels of glutathione reductase (GR) may be linked with periodontal status.

METHODS

Saliva samples from patients with CP (n = 121), patients with AgP (n = 18), and healthy controls (n = 69) were collected. Periodontal status was assessed by criteria based on probing depth, clinical attachment level, and extent and severity of periodontal breakdown. GR salivary levels were analyzed by spectrophotometry. The association among GR concentration and CP or AgP was analyzed individually and adjusted for confounding using multivariate binary logistic regression models.

RESULTS

GR levels not only differed significantly between the two periodontitis groups, being significantly greater in patients with AgP, but also were significantly greater than those observed in healthy controls. Synchronously, positive significant correlations between salivary GR concentration and clinical parameters were observed. After binary logistic regression analysis, both GR salivary levels ≥15.38 and ≥24.20 mU/mL were associated independently with CP and AgP, respectively. A significant interaction effect was also detected between increased GR salivary concentration and aging in the CP group.

CONCLUSIONS

Increased GR salivary concentration may be a strong/independent prognostic indicator of the amount and extent of oxidative stress-induced periodontal damage in both CP and AgP. Likewise, saliva samples might reflect an interactive effect of GR levels associated with the aging-related cumulative characteristics of periodontal damage in CP.

Elevated MicroRNA-128 in Periodontitis Mitigates Tumor Necrosis Factor-α Response via p38 Signaling Pathway in Macrophages

BACKGROUND

Periodontitis is a chronic inflammatory disease resulting from an inflammatory response to subgingival plaque bacteria, including Porphyromonas gingivalis. MicroRNA (miRNA) is a current focus in regulating the inflammatory processes. In this study, the inflammatory miRNA expression in gingival tissues of patients with periodontitis and of healthy individuals is compared, and its role in regulating the inflammatory response is examined.

METHODS

Gingival tissues from patients with periodontitis and healthy individuals were collected for miRNA microarray. THP-1 and CA9-22 cells were challenged with P. gingivalis, and miRNA expression was determined by real-time polymerase chain reaction. Target genes for miRNA were predicted using TargetScanHuman database, and miRNA gene expressions were reviewed using public databases. For the functional study, THP-1 cells were transfected with a miRNA-128 mimic, and target gene expression was compared with THP-1 cells challenged with P. gingivalis. For the tolerance test, THP-1 cells transfected with miRNA-128 mimic were treated with phorbol 12-myristate 13-acetate (PMA) or paraformaldehyde (PFA)-fixed Escherichia coli. Tumor necrosis factor (TNF)-α production was determined by enzyme-linked immunosorbent assay, and mitogen-activated protein kinase (MAPK) protein phosphorylation was determined by Western blot.

RESULTS

Gingival tissues from patients with periodontitis showed increased expression of miRNA-128, miRNA-34a, and miRNA-381 and decreased expression of miRNA-15b, miRNA-211, miRNA-372, and miRNA-656. THP-1 cells and CA9-22 cells challenged with P. gingivalis showed increased miRNA-128 expression. Among the predicted miRNA-128 target genes, several genes that are involved in MAPK signaling pathway showed similar gene expression pattern between P. gingivalis challenge and miRNA-128 mimic transfection. In THP-1 cells transfected with miRNA-128 mimic, TNF-α production was lower, and phosphorylation of p38 was inhibited when challenged with PMA or PFA-fixed E. coli.

CONCLUSION

miRNA-128 may be involved in mitigating the inflammatory response induced by P. gingivalis in periodontitis.

Longitudinal quantification of the gingival crevicular fluid proteome during progression from gingivitis to periodontitis in a canine model

Aim

Inflammatory periodontal disease is widespread in dogs. This study evaluated site‐specific changes in the canine gingival crevicular fluid (GCF) proteome during longitudinal progression from very mild gingivitis to mild periodontitis. Periodontitis diagnosis in dogs requires general anaesthesia with associated risks and costs; our ultimate aim was to develop a periodontitis diagnostic for application in conscious dogs. The objective of this work was to identify potential biomarkers of periodontal disease progression in dogs.

Material and Methods

Gingival crevicular fluid was sampled from a total of 10 teeth in eight dogs at three different stages of health/disease and samples prepared for quantitative mass spectrometry (data available via ProteomeXchange; identifier PXD003337). A univariate mixed model analysis determined significantly altered proteins between health states and six were evaluated by ELISA.

Results

Four hundred and six proteins were identified with 84 present in all samples. The prevalence of 40 proteins was found to be significantly changed in periodontitis relative to gingivitis. ELISA measurements confirmed that haptoglobin was significantly increased.

Conclusions

This study demonstrates for the first time that proteins detected by mass spectrometry have potential to identify novel biomarkers for canine periodontal disease. Further work is required to validate additional biomarkers for a periodontitis diagnostic.

A review of the evidence for pathogenic mechanisms that may link periodontitis and diabetes

AIMS

To review the evidence for the molecular and cellular processes that may potentially link periodontal disease and diabetes. The pathogenic roles of cytokines and metabolic molecules (e.g. glucose, lipids) are explored and the role of periodontal bacteria is also addressed. Paradigms for bidirectional relationships between periodontitis and diabetes are discussed and opportunities for elaborating these models are considered.

METHODS

Database searches were performed using MeSH terms, keywords, and title words. Studies were evaluated and summarized in a narrative review.

RESULTS

Periodontal microbiota appears unaltered by diabetes and there is little evidence that it may influence glycaemic control. Small-scale clinical studies and experiments in animal models suggest that IL-1β, TNF-α, IL-6, OPG and RANKL may mediate periodontitis in diabetes. The AGE-RAGE axis is likely an important pathway of tissue destruction and impaired repair in diabetes-associated periodontitis. A role for locally activated pro-inflammatory factors in the periodontium, which subsequently impact on diabetes, remains speculative.

CONCLUSION

There is substantial information on potential mechanistic pathways which support a close association between diabetes and periodontitis, but there is a real need for longitudinal clinical studies using larger patient groups, integrated with studies of animal models and cells/tissues in vitro.

Evaluation of oxidant-antioxidant status in tissue samples in oral cancer: A case control study

Background:

Imbalances between the oxidant-antioxidant status have been implicated in the pathogenesis of several diseases, including cancer. The aim of this study was to evaluate the extent of lipid peroxidation and antioxidants in the tissue samples of oral squamous cell carcinoma (OSCC) patients of different clinical stages in comparison with the healthy controls.

Materials and Methods:

A case-control study was designed with 20 new histopathologically proven oral carcinoma patients and an equal number of age, sex, and tobacco chewing habit matched healthy subjects. Their tissue samples were subjected to evaluation of lipid peroxidation product and antioxidant enzymes, namely, superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and glutathione peroxidase (GPx) using spectrophotometric methods. The data are expressed as mean ± standard deviation. The statistical comparisons between the study groups were performed by independent Student's unpaired t-test and one-way analysis of variance. Post-hoc analysis was performed for within study group comparisons. Karl Pearson correlation was performed for the biochemical parameters within the group and between the groups. For statistically significant correlations, simple linear regression was performed using SPSS (α=0.05).

Results:

Significant reduction in lipid peroxidation (P < 0.001) SOD and CAT (P < 0.001) was observed in the tissue of OSCC patients as compared with the healthy controls. On the other hand, reduced GSH and GPx were significantly increased in tumor samples.

Conclusion:

Reduced lipid peroxidation and increased activity of reduced GSH and GPx provides the suitable environment for the local growth and invasion of the tumor and metastasis in the later stages. Among the antioxidant enzymes, GSH reductase appears to have a profound role in carcinogenesis and thus it can be considered as potential prognostic marker.

Nuclear Factor Erythroid 2-Related Factor 2 Down-Regulation in Oral Neutrophils Is Associated with Periodontal Oxidative Damage and Severe Chronic Periodontitis

The balance between reactive oxygen species and antioxidants plays an important role in periodontal health. We previously demonstrated that high reactive oxygen species production by oral polymorphonuclear neutrophils (oPMNs) in chronic periodontitis (CP) refractory to conventional therapy is associated with severe destruction of periodontium. Herein, we show that inhibition of antioxidant production through down-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in oPMN, despite enhanced recruitment in the oral cavity, is associated with severe CP. Twenty-four genes in the Nrf2-mediated oxidative stress response pathway were down-regulated in PMNs of diseased patients. Downstream of Nrf2, levels of oPMN superoxide dismutase 1 and catalase were decreased in severe CP, despite increased recruitment. Nrf2(-/-) mice had more severe loss of periodontium in response to periodontitis-inducing subgingival ligatures compared with wild-types. Levels of 8-hydroxy-deoxyguanosine were increased in periodontal lesions of Nrf2(-/-) mice, indicating high oxidative damage. We report, for the first time, Nrf2 pathway down-regulation in oPMNs of patients with severe CP. PMNs of CP patients may be primed for low antioxidant response in the context of high recruitment in the oral cavity, resulting in increased oxidative tissue damage.

Identical mitochondrial somatic mutations unique to chronic periodontitis and coronary artery disease

Context:

The inflammatory processes involved in chronic periodontitis and coronary artery diseases (CADs) are similar and produce reactive oxygen species that may result in similar somatic mutations in mitochondrial deoxyribonucleic acid (mtDNA).

Aims:

The aims of the present study were to identify somatic mtDNA mutations in periodontal and cardiac tissues from subjects undergoing coronary artery bypass surgery and determine what fraction was identical and unique to these tissues.

Settings and Design:

The study population consisted of 30 chronic periodontitis subjects who underwent coronary artery surgery after an angiogram had indicated CAD.

Materials and Methods:

Gingival tissue samples were taken from the site with deepest probing depth; coronary artery tissue samples were taken during the coronary artery bypass grafting procedures, and blood samples were drawn during this surgical procedure. These samples were stored under aseptic conditions and later transported for mtDNA analysis.

Statistical Analysis Used:

Complete mtDNA sequences were obtained and aligned with the revised Cambridge reference sequence (NC_012920) using sequence analysis and auto assembler tools.

Results:

Among the complete mtDNA sequences, a total of 162 variations were spread across the whole mitochondrial genome and present only in the coronary artery and the gingival tissue samples but not in the blood samples. Among the 162 variations, 12 were novel and four of the 12 novel variations were found in mitochondrial NADH dehydrogenase subunit 5 complex I gene (33.3%).

Conclusions:

Analysis of mtDNA mutations indicated 162 variants unique to periodontitis and CAD. Of these, 12 were novel and may have resulted from destructive oxidative forces common to these two diseases.

Influences of Fucoxanthin on Alveolar Bone Resorption in Induced Periodontitis in Rat Molars

The aim of this study was to evaluate the effects of systemic fucoxanthin treatment on alveolar bone resorption in rats with periodontitis. Thirty rats were divided into control, experimental periodontitis (EP), and experimental periodontitis-fucoxanthin (EP-FUCO) groups. Periodontitis was induced by ligature for four weeks. After removal of the ligature, the rats in the EP-FUCO group were treated with a single dose of fucoxanthin (200 mg/kg bw) per day for 28 consecutive days. At the end of the study, all of the rats were euthanized and intracardiac blood and mandible tissue samples were obtained for biochemical, immunohistochemical, and histometric analyses. Fucoxanthin treatment resulted in a slight decrease in tumor necrosis factor-α, interleukin-1β, and interleukin-6 levels and a significant decrease in oxidative stress index. It was observed that fucoxanthin caused a significant reduction in receptor activator of nuclear factor kappa-β ligand (RANKL) levels and a statistically non-significant elevation in osteoprotegerin and bone-alkaline phosphatase levels. There were no significant differences in alveolar bone loss levels between the EP and EP-FUCO groups. This experimental study revealed that fucoxanthin provides a limited reduction in alveolar bone resorption in rats with periodontitis. One of the mechanisms underlying the mentioned limited effect might be related to the ability of fucoxanthin to inhibit oxidative stress-related RANKL-mediated osteoclastogenesis.

Major neutrophil functions subverted by Porphyromonas gingivalis

Polymorphonuclear leukocytes (neutrophils) constitute an integrated component of the innate host defense in the gingival sulcus/periodontal pocket. However, the keystone periodontal pathogen Porphyromonas gingivalis has in the course of evolution developed a number of capacities to subvert this defense to its own advantage. The present review describes the major mechanisms that P. gingivalis uses to subvert neutrophil homeostasis, such as impaired recruitment and chemotaxis, resistance to granule-derived antimicrobial agents and to the oxidative burst, inhibition of phagocytic killing while promoting a nutritionally favorable inflammatory response, and delay of neutrophil apoptosis. Studies in animal models have shown that at least some of these mechanisms promote the dysbiotic transformation of the periodontal polymicrobial community, thereby leading to inflammation and bone loss. It is apparent that neutrophil–P. gingivalis interactions and subversion of innate immunity are key contributing factors to the pathogenesis of periodontal disease.

Quercitrin-nanocoated titanium surfaces favour gingival cells against oral bacteria

Many dental implants fail due to the infection and inflammation that walk hand in hand with poor healing and soft tissue integration. Titanium surfaces were nanocoated with quercitrin, a natural flavonoid, with the aim to improve soft tissue integration and increase dental implants success. Streptococcus mutans attachment and biofilm formation was analysed. Then, the anti-inflammatory properties and the potential of quercitrin-nanocoated surfaces to boost soft tissue regeneration were tested using human gingival fibroblasts. An inflammatory situation was mimicked using interleulin-1-beta. We found that quercitrin-nanocoated surfaces decreased initial bacterial adhesion while increasing human gingival fibroblasts attachment. Furthermore, quercitrin-nanocoated Ti increased collagen mRNA levels and decreased matrix metalloproteinase-1/tissue inhibitor of metalloproteinanse-1 mRNA ratio, which is related to a reduced metalloproteinase-mediated collagen degradation, while also decreasing the pro-inflammatory prostaglandin E₂ release under basal and inflammatory conditions. These results suggest that quercitrin-nanocoated surfaces could enhance the soft tissue integration and increase dental implants success.

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.

Immune and regulatory functions of neutrophils in inflammatory bone loss

Although historically viewed as merely anti-microbial effectors in acute infection or injury, neutrophils are now appreciated to be functionally versatile with critical roles also in chronic inflammation. Periodontitis, a chronic inflammatory disease that destroys the tooth-supporting gums and bone, is particularly affected by alterations in neutrophil numbers or function, as revealed by observations in monogenic disorders and relevant mouse models. Besides being a significant debilitating disease and health burden in its own right, periodontitis is thus an attractive model to dissect uncharted neutrophil-associated (patho)physiological pathways. Here, we summarize recent evidence that neutrophils can contribute to inflammatory bone loss not only through the typical bystander injury dogma but intriguingly also through their absence from the affected tissue, where they normally perform important immunomodulatory functions. Moreover, we discuss recent advances in the interactions of neutrophils with the vascular endothelium and - upon extravasation - with bacteria, and how the dysregulation of these interactions leads to inflammatory tissue damage. Overall, neutrophils have both protective and destructive roles in periodontitis, as they are involved in both the maintenance of periodontal tissue homeostasis and the induction of inflammatory bone loss. This highlights the importance of developing approaches that promote or sustain a fine balance between homeostatic immunity and inflammatory pathology.

Malondialdehyde, superoxide dismutase and melatonin levels in gingival crevicular fluid of aggressive and chronic periodontitis patients

BACKGROUND

The aim of this study was to investigate malondialdehyde (MDA), superoxide dismutase (SOD) and melatonin levels in the gingival crevicular fluid (GCF) of patients with chronic periodontitis (CP) and generalized aggressive periodontitis (GAgP) as biomarkers for oxidative stress.

METHODS

The study comprised 65 subjects: 15 healthy individuals, 25 CP patients and 25 GAgP patients. Plaque index, gingival index, pocket depth, clinical attachment level measurements and GCF samples were obtained from all subjects. MDA, SOD and melatonin levels were determined utilizing enzyme-linked immunosorbent assay.

RESULTS

GCF-MDA levels were significantly higher in the GAgP group compared to the CP and control groups (p < 0.001) and significantly higher in the CP group than the C group (p < 0.001). SOD and melatonin GCF levels were significantly higher in the control than the GAgP and CP groups (p < 0.05), and significantly lower in the GAgP than the CP group (p < 0.05). The CP group demonstrated a significant negative correlation between GCF-MDA and melatonin concentrations. A positive correlation was observed between SOD and CAL in the CP group and PD in the GAgP group.

CONCLUSIONS

MDA, melatonin and SOD could be considered as biomarkers for oxidative stress in periodontal diseases and might be useful diagnostic aids in distinguishing CP and GAgP patients.

Association between periodontitis and salivary 8-hydroxydeoxyguanosine among Korean rural adults

OBJECTIVES

This study aimed to evaluate the association between salivary 8-hydroxydeoxyguanosine (8-OHdG) and periodontitis among community-dwelling Korean adults.

METHODS

A total of 211 adults (80 men and 131 women) were cross-sectionally surveyed from the Sunchang Longevity Cohort. Periodontitis was defined as having at least 30% of teeth with proximal attachment loss ≥5 mm. The salivary 8-OHdG level was categorized into tertiles: low (<0.916 ng/ml), medium (0.916 to <2.675 ng/ml) and high (≥2.675 ng/ml). Sociodemographic, habitual and systemic health-related factors were controlled for. Logistic regression analysis was performed for the outcome of severe periodontitis. Analysis of covariance in general linear model was performed for the outcome of 8-OHdG.

RESULTS

The high 8-OHdG level showed a significant association with periodontitis. The odds ratio (95% confidence interval) was 2.40 (1.05-5.51), and it was highlighted by adding the interaction term with drinking and smoking. The adjusted mean log-transformed value of 8-OHdG was significantly higher in the severe periodontitis group (1.40 ng/ml) than in the control group (1.02 ng/ml) (ancova, P = 0.028).

CONCLUSIONS

8-OHdG was associated with periodontitis. Thus, salivary 8-OHdG could be a useful marker for periodontitis.

Neutrophil Functions in Periodontal Homeostasis

Oral tissues are constantly exposed to damage from the mechanical effort of eating and to microorganisms, mostly bacteria. In healthy gingiva tissue remodeling and a balance between bacteria and innate immune cells are maintained. However, excess of bacteria biofilm (plaque) creates an inflammation state that recruits more immune cells, mainly neutrophils to the gingiva. Neutrophils create a barrier for bacteria to reach inside tissues. When neutrophils are insufficient, bacteria thrive causing more inflammation that has been associated with systemic effects on other conditions such as atherosclerosis, diabetes, and cancer. But paradoxically when neutrophils persist, they can also promote a chronic inflammatory state that leads to periodontitis, a condition that leads to damage of the bone-supporting tissues. In periodontitis, bone loss is a serious complication. How a neutrophil balance is needed for maintaining healthy oral tissues is the focus of this review. We present recent evidence on how alterations in neutrophil number and function can lead to inflammatory bone loss, and how some oral bacteria signal neutrophils to block their antimicrobial functions and promote an inflammatory state. Also, based on this new information, novel therapeutic approaches are discussed.

Omega-3 fatty acids as an adjunct for periodontal therapy-a review

OBJECTIVES

The aim of this article is to present an overview of omega-3 fatty acids, their anti-inflammatory properties and potential use as an adjunct for periodontal therapy.

MATERIALS AND METHODS

A general literature search was conducted to provide an overview of omega-3 fatty acids, their metabolism and anti-inflammatory properties. A more specific literature search of PubMed and EMBASE was conducted to identify articles dealing studies investigating the effects of omega-3 fatty acids in the treatment of periodontitis in animals and humans and included cross-sectional, longitudinal and intervention designs.

RESULTS

To date, there is good emerging evidence that dietary supplementation with fish oil may be of some benefit and this is enhanced if combined with aspirin. All clinical intervention studies to date have been on small sample sizes, and this indicates there is need for larger and more robust clinical trials to verify these initial findings.

CONCLUSIONS

Dietary supplementation with fish oil could be a cost-effective adjunctive therapy to the management of periodontal disease.

CLINICAL RELEVANCE

The host modulatory properties of omega-3 fatty acids warrant further assessment of their use as an adjunct in the management of periodontitis.

Effects of Melatonin on Oxidative Stress Index and Alveolar Bone Loss in Diabetic Rats With Periodontitis

BACKGROUND

The aim of this study is to evaluate the effects of systemic melatonin treatment on serum oxidative stress index (OSI) and alveolar bone loss (ABL) in rats with diabetes mellitus (DM) and periodontitis.

METHODS

Seventy Sprague Dawley rats were divided into control, experimentally induced periodontitis (EP), DM, EP-DM, EP and melatonin treatment (EP-MEL), DM and melatonin treatment (DMMEL), and EP-DM-MEL groups. DM was induced by alloxan, after which periodontitis was induced by ligature for 4 weeks. After removal of the ligature, the rats in the melatonin groups (EP-MEL, DM-MEL, and EP-DM-MEL) were treated with a single dose of melatonin (10 mg/body weight) every day for 14 consecutive days. At the end of the study, all of the rats were euthanized, and intracardiac blood samples and mandible tissues were obtained for biochemical and histologic analyses. Serum levels of total oxidant status/total antioxidant status and OSI were measured. In addition, neutrophil and osteoclast densities and myeloperoxidase activities were determined in gingival tissue homogenates, and ABL was evaluated with histometric measurements.

RESULTS

Melatonin treatment significantly reduced fasting plasma glucose levels in the rats with DM. In addition, reduced OSI and ABL levels were detected in the EP-MEL and DM-MEL groups; the reductions in the EP-DM-MEL group were found to be more prominent. Melatonin also significantly decreased the increased myeloperoxidase activities and osteoclast and neutrophil densities in the EP, DM, and EP-DM groups.

CONCLUSION

It is revealed in this experimental study that melatonin significantly inhibited hyperglycemia-induced oxidative stress and ABL through antiDM and antioxidant effects in rats with DM and periodontitis.

Thymosin Beta-4 Suppresses Osteoclastic Differentiation and Inflammatory Responses in Human Periodontal Ligament Cells

Background

Recent reports suggest that thymosin beta-4 (Tβ4) is a key regulator for wound healing and anti-inflammation. However, the role of Tβ4 in osteoclast differentiation remains unclear.

Purpose

The purpose of this study was to evaluate Tβ4 expression in H₂O₂-stimulated human periodontal ligament cells (PDLCs), the effects of Tβ4 activation on inflammatory response in PDLCs and osteoclastic differentiation in mouse bone marrow-derived macrophages (BMMs), and identify the underlying mechanism.

Methods

Reverse transcription-polymerase chain reactions and Western blot analyses were used to measure mRNA and protein levels, respectively. Osteoclastic differentiation was assessed in mouse bone marrow-derived macrophages (BMMs) using conditioned medium (CM) from H₂O₂-treated PDLCs.

Results

Tβ4 was down-regulated in H₂O₂-exposed PDLCs in dose- and time-dependent manners. Tβ4 activation with a Tβ4 peptide attenuated the H₂O₂-induced production of NO and PGE₂ and up-regulated iNOS, COX-2, and osteoclastogenic cytokines (TNF-α, IL-1β, IL-6, IL-8, and IL-17) as well as reversed the effect on RANKL and OPG in PDLCs. Tβ4 peptide inhibited the effects of H₂O₂ on the activation of ERK and JNK MAPK, and NF-κB in PDLCs. Furthermore, Tβ4 peptide inhibited osteoclast differentiation, osteoclast-specific gene expression, and p38, ERK, and JNK phosphorylation and NF-κB activation in RANKL-stimulated BMMs. In addition, H₂O₂ up-regulated Wnt5a and its cell surface receptors, Frizzled and Ror2 in PDLCs. Wnt5a inhibition by Wnt5a siRNA enhanced the effects of Tβ4 on H₂O₂-mediated induction of pro-inflammatory cytokines and osteoclastogenic cytokines as well as helping osteoclastic differentiation whereas Wnt5a activation by Wnt5a peptide reversed it.

Conclusion

In conclusion, this study demonstrated, for the first time, that Tβ4 was down-regulated in ROS-stimulated PDLCs as well as Tβ4 activation exhibited anti-inflammatory effects and anti-osteoclastogenesis in vitro. Thus, Tβ4 activation might be a therapeutic target for inflammatory osteolytic disease, such as periodontitis.

Role of nitro-oxidative stress in the pathogenesis of experimental rat periodontitis

Background and aims

Periodontitis is a common chronic adult condition that implicates oxidative damage to gingival tissue, periodontal ligament and alveolar bone. This study aimed at assessing the association between the nitro-oxidative stress and the periodontal tissues destructions in experimental rat periodontitis.

Methods

Periodontitis was induced in 15 male albino rats by repetitive lesions to the gingiva adjacent to the inferior incisors, performed daily, for 16 days. On D1, D3, D6, D8, and D16 the onset and evolution of periodontitis were monitored by clinical and histopathological examinations; blood was collected and serum nitro-oxidative stress was evaluated through total nitrites and nitrates, total oxidative status, total antioxidant capacity, and oxidative stress index.

Results

The results demonstrated that there was a graded and continuous increase in serum levels of total nitrites and nitrates, total oxidative status and oxidative stress index, which was consistent with the severity of periodontal destructions during periodontitis progression. However, total antioxidant capacity was not significantly influenced by the disease progression.

Conclusions

In experimental rat periodontitis, the systemic nitro-oxidative stress was associated with the severity of periodontal destructions assessed clinically and histopathologically. Therefore, systemic nitro-oxidative stress parameters might be used as diagnostic tools in periodontitis.

Total Antioxidant Capacity and Total Oxidant Status in Saliva of Periodontitis Patients in Relation to Bacterial Load

The detection of salivary biomarkers has a potential application in early diagnosis and monitoring of periodontal inflammation. However, searching sensitive salivary biomarkers for periodontitis is still ongoing. Oxidative stress is supposed to play an important role in periodontitis progression and tissue destruction. In this cross-sectional study, we investigated total antioxidant capacity (TAC) and total oxidant status (TOS) in saliva of periodontitis patients compared to healthy controls and their relationship with periodontopathic bacteria and periodontal disease severity. Unstimulated saliva was collected from 45 patients with generalized severe periodontitis and 37 healthy individuals and the TAC/TOS were measured. In addition, salivary levels of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Fusobacterium nucleatum in saliva were measured. Salivary TAC was lower in periodontitis patients compared to healthy controls. Moreover, a significant negative correlation of salivary TAC with clinical attachment loss was observed in periodontitis patients. No significant difference in the salivary TOS was observed between periodontitis patients and healthy controls. Bacterial load was enhanced in periodontitis patients and exhibited correlation with periodontal disease severity but not with salivary TAC/TOS. Our data suggest that changes in antioxidant capacity in periodontitis patients are not associated with increased bacterial load and are probably due to a dysregulated immune response.

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.

Salivary Cytoprotective Proteins in Inflammation and Resolution during Experimental Gingivitis--A Pilot Study

Objective: The protective mechanisms that maintain periodontal homeostasis in gingivitis and prevent periodontal tissue destruction are poorly understood. The aim of this study was to identify changes in the salivary proteome during experimental gingivitis.

Study design: We used oral neutrophil quantification and whole saliva (WS) proteomics to assess changes that occur in the inflammatory and resolution phases of gingivitis in healthy individuals. Oral neutrophils and WS samples were collected and clinical parameters measured on days 0, 7, 14, 21, 28, and 35.

Results: Increased oral neutrophil recruitment and salivary cytoprotective proteins increased progressively during inflammation and decreased in resolution. Oral neutrophil numbers in gingival inflammation and resolution correlated moderately with salivary β-globin, thioredoxin, and albumin and strongly with collagen alpha-1 and G-protein coupled receptor 98.

Conclusions: Our results indicate that changes in salivary cytoprotective proteins in gingivitis are associated with a similar trend in oral neutrophil recruitment and clinical parameters.

Clinical relevance: We found moderate to strong correlations between oral neutrophil numbers and levels of several salivary cytoprotective proteins both in the development of the inflammation and in the resolution of gingivitis. Our proteomics approach identified and relatively quantified specific cytoprotective proteins in this pilot study of experimental gingivitis; however, future and more comprehensive studies are needed to clearly identify and validate those protein biomarkers when gingivitis is active.

Resveratrol prevents alveolar bone loss in an experimental rat model of periodontitis

Resveratrol is an antioxidant and anti-inflammatory polyphenol. Periodontitis is induced by oral pathogens, where a systemic inflammatory response accompanied by oxidative stress is the major event initiating disease. We investigated how resveratrol modulates cellular responses and the mechanisms related to this modulation in lipopolysaccharide (LPS)-stimulated human gingival fibroblasts (hGFs). We also explored whether resveratrol protects rats against alveolar bone loss in an experimental periodontitis model. Periodontitis was induced around the first upper molar of the rats by applying ligature infused with LPS. Stimulating hGFs with 5μg/ml LPS augmented the expression of cyclooxygenase-2, matrix metalloproteinase (MMP)-2, MMP-9, and Toll-like receptor-4. LPS treatment also stimulated the production of reactive oxygen species (ROS) and the phosphorylation of several protein kinases in the cells. However, the expression of heme oxygenase-1 (HO-1) and nuclear factor-E2 related factor 2 (Nrf2) was inhibited by the addition of LPS. Resveratrol treatment almost completely inhibited all of these changes in LPS-stimulated cells. Specifically, resveratrol alone augmented HO-1 induction via Nrf2-mediated signaling. Histological and micro-CT analyses revealed that administration of resveratrol (5mg/kg body weight) improved ligature/LPS-mediated alveolar bone loss in rats. Resveratrol also attenuated the production of inflammation-related proteins, the formation of osteoclasts, and the production of circulating ROS in periodontitis rats. Furthermore, resveratrol suppressed LPS-mediated decreases in HO-1 and Nrf2 levels in the inflamed periodontal tissues. Collectively, our findings suggest that resveratrol protects rats from periodontitic tissue damage by inhibiting inflammatory responses and by stimulating antioxidant defense systems.

STATEMENT OF SIGNIFICANCE

The aims of this study were to investigate how resveratrol modulates cellular responses and the mechanisms related to this modulation in lipopolysaccharide (LPS)-stimulated human gingival fibroblasts (hGFs) and protects rats against alveolar bone disruption in an experimental periodontitis model. Our findings suggest that resveratrol protects rats from periodontitic tissue damage by inhibiting inflammatory responses and by stimulating antioxidant defense systems. On the basis of our experiment studies, we proposed that resveratrol could be used as novel bioactive materials or therapeutic drug for the treatment of periodontitis or other inflammatory bone diseases like osteoporosis, arthritis etc. Furthermore, it could be also used for the modification or coating of implant materials as an antiinflammatory molecules which will help to accelerate bone formation. There are a few of reports suggesting antioxidant and anti-inflammatory potentials of resveratrol. However, our results highlight the cellular mechanisms by which resveratrol inhibits LPS-mediated cellular damages using human-originated gingival fibroblasts and also support the potential of resveratrol to suppress periodontitis-mediated tissue damages. We believe that the present findings might improve a clinical approach of using of resveratrol on human, although further detailed experiments will be needed.

Hydrogen-Rich Water Intake Accelerates Oral Palatal Wound Healing via Activation of the Nrf2/Antioxidant Defense Pathways in a Rat Model

The wound healing process attempts to restore the integrity and function of the injured tissue. Additionally, proinflammatory cytokines, growth factors, and oxidative stress play important roles in wound healing. The aim of this study was to determine whether hydrogen-rich water intake induces the activation of the Nrf2/antioxidant defense pathway in rat palatal tissue, thereby reducing systemic oxidative stress and proinflammatory cytokine levels and promoting healing-associated genes. A circular excisional wound was created in the oral palatal region, and the wound healing process was observed. The rats were divided into two experimental groups in which either hydrogen-rich water or distilled water was consumed. In the drinking hydrogen-rich water, the palatal wound healing process was accelerated compared to that in the control group. As molecular hydrogen upregulated the Nrf2 pathway, systemic oxidative stresses were decreased by the activation of antioxidant activity. Furthermore, hydrogen-rich water intake reduced proinflammatory cytokine levels and promoted the expression of healing-associated factors in rat palatal tissue. In conclusion, hydrogen-rich water intake exhibited multiple beneficial effects through activation of the Nrf2/antioxidant defense pathway. The results of this study support the hypothesis that oral administration of hydrogen-rich water benefits the wound healing process by decreasing oxidative stress and inflammatory responses.

The Effect of Melatonin on Bone Loss, Diabetic Control, and Apoptosis in Rats With Diabetes With Ligature-Induced Periodontitis

BACKGROUND

The aim of this study examines the effect of systemic melatonin administration on proinflammatory cytokine levels, apoptosis, alveolar bone loss (ABL), lipid metabolism, and diabetic control in in rats with diabetes mellitus (DM) and ligature-induced periodontitis.

METHODS

Fifty-two male Wistar rats were used in this study. Study groups were as follows: 1) non-ligated control (NL, n = 6); 2) streptozotocin (STZ, n = 8); 3) STZ and melatonin (STZ+Mel, n = 8); 4) ligature (L, n = 6); 5) ligature and melatonin (L+Mel, n = 8); 6) STZ and ligature (STZ+L, n = 8); and 7) STZ, ligature, and melatonin (STZ+L+Mel, n = 8). DM was induced by intraperitoneal injection of a single dose of STZ (60 mg/kg). Melatonin was administered by intraperitoneal injection of a dose of 10 mg/kg/day for 4 weeks. Silk ligatures were placed subgingivally around the mandibular right first molars. The study period was 4 weeks, and animals were sacrificed at the end of 4 weeks. Morphometric analysis of bone loss was performed. Tissues were histopathologically examined. Inducible nitric oxide synthase (iNOS) and B-cell lymphoma-2-associated X (bax) protein expressions, serum interleukin (IL)-1β levels, and tartrate-resistant acid phosphatase-positive (TRAP+) osteoclast numbers were also evaluated.

RESULTS

After 4 weeks, the highest ABL was observed in the STZ+L group, and the difference was significant (P <0.05). Systemically administered melatonin significantly decreased ABL in the STZ+L+Mel group compared with that in the STZ+L group (P <0.05). TRAP+ osteoclast numbers were the highest in the STZ+L group, and melatonin significantly decreased osteoclast numbers (P <0.05) but had no effect on iNOS, IL-1β, or bax levels.

CONCLUSIONS

Within the limits of this study, it can be concluded that systemic melatonin treatment may decrease osteoclastic activity and reduce ABL in the model using rats with DM.

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.

Smoking and inflammation: evidence for a synergistic role in chronic disease

Tobacco smoking is the most important preventable risk factor for periodontitis; however, the underlying biological mechanisms responsible for the detrimental effects of smoking on periodontal health remain largely unclear. It is also well established that smoking has a negative impact on several inflammatory diseases, including rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease. The aim of this paper was to review smoking-related changes in local and systemic host responses with a focus on cellular and molecular effects that could explain a hyperinflammatory response leading to periodontal destruction. Biological mechanisms that may be common to periodontal disease and other chronic inflammatory diseases were also explored, together with gene-smoking interactions. An epidemiologic perspective on the burden of smoking on periodontal health and the potential for smoking cessation is also presented. Tobacco smoking seems to induce changes ranging from decreased leukocyte chemotaxis to decreased production of immunoglobulins. Smoking also seems to cause a stronger inflammatory reaction with an increased release of potentially tissue-destructive substances (e.g. reactive oxygen species, collagenase, serine proteases and proinflammatory cytokines). These findings support a hypothesis that periodontitis is a hyperinflammatory condition rather than a hypo-inflammatory condition.

Salivary markers of oxidative stress in oral diseases

Saliva is an interesting alternative diagnostic body fluid with several specific advantages over blood. These include non-invasive and easy collection and related possibility to do repeated sampling. One of the obstacles that hinders the wider use of saliva for diagnosis and monitoring of systemic diseases is its composition, which is affected by local oral status. However, this issue makes saliva very interesting for clinical biochemistry of oral diseases. Periodontitis, caries, oral precancerosis, and other local oral pathologies are associated with oxidative stress. Several markers of lipid peroxidation, protein oxidation and DNA damage induced by reactive oxygen species can be measured in saliva. Clinical studies have shown an association with oral pathologies at least for some of the established salivary markers of oxidative stress. This association is currently limited to the population level and none of the widely used markers can be applied for individual diagnostics. Oxidative stress seems to be of local oral origin, but it is currently unclear whether it is caused by an overproduction of reactive oxygen species due to inflammation or by the lack of antioxidants. Interventional studies, both, in experimental animals as well as humans indicate that antioxidant treatment could prevent or slow-down the progress of periodontitis. This makes the potential clinical use of salivary markers of oxidative stress even more attractive. This review summarizes basic information on the most commonly used salivary markers of oxidative damage, antioxidant status, and carbonyl stress and the studies analyzing these markers in patients with caries or periodontitis.

Oral health status in relation to cognitive function among older Japanese

Epidemiologic data examining the relationship between oral health status and cognitive status are sparse, especially in Asian populations. This study aimed to assess whether periodontal disease and tooth loss were related to cognitive impairment among older Japanese. Study participants were 291 Japanese (101 men and 190 women, average age: 80.9 years), classified into three groups based on a clinical examination of oral health status: no periodontal disease, periodontal disease, and edentulous. Periodontal disease was defined using criteria recommended in the consensus report of the European Workshop in Periodontology with a modification. Cognitive impairment was defined using the results of the Mini-mental State Examination (MMSE) and Hasegawa Dementia Scale-Revised (HDS-R) scores. Multivariable logistic regression analyses assessed the relationship of the three-category oral health status variable (reference category = no periodontal disease) with low MMSE score (≤23) and low HDS-R score (≤20). Age, gender, years of education, body mass index, smoking status, drinking behavior, and history of cardiovascular disease were tested as potential confounders in the multivariable models. Periodontal disease and edentulous were significantly associated with greater odds of low cognitive performance after controlling for potential confounders. The multivariable adjusted odds ratios (ORs) (95% confidence intervals [CIs]) for low MMSE score associated with periodontal disease and edentulous were 2.21 (1.01-4.84) and 2.28 (1.06-4.90), respectively. The multivariable adjusted ORs (95% CIs) for low HDS-R score associated with periodontal disease and edentulous were 4.85 (1.29-18.15) and 3.86 (1.05-14.20), respectively. Poor oral health status was significantly associated with cognitive impairment among community-dwelling older Japanese. Additional well-controlled longitudinal studies are needed to elucidate whether there may be a possible cause-and-effect relationship between oral health status and cognitive function.