Obesity-associated Gingival Vascular Inflammation and Insulin Resistance

The bidirectional association between diabetes and periodontitis, from basic to clinical

The prevalence and severity of periodontitis are increased and advanced in diabetes. Severe periodontitis elicits adverse effects on diabetes by impairing insulin actions due to systemic microinflammation. Recent studies unveil the emerging findings and molecular basis of the bidirectional relationship between periodontitis and diabetes. In addition to conventional mechanisms such as hyperglycemia, hyperlipidemia, and chronic inflammation, deficient insulin action may play a pathogenic role in the progression of periodontitis under diabetes. Epidemiologically, from the viewpoint of the adverse effect of periodontitis on diabetes, recent studies have suggested that Asians including Japanese and Asian Americans with diabetes and mild obesity (BMI <25 kg/m2) should pay more attention to their increased risk for cardiovascular diseases. In this review, we summarize recent findings on the effect of diabetes on periodontitis from the viewpoint of abnormalities in metabolism and insulin resistance with novel mechanisms, and the influence of periodontitis on diabetes mainly focused on micro-inflammation related to mature adipose tissue and discuss future perspectives about novel approaches to interrupt the adverse interrelationship.

Improvement of periodontal parameters following intensive diabetes care and supragingival dental prophylaxis in patients with type 2 diabetes: A prospective cohort study

AIM

This study aimed to investigate the effects of diabetes care on periodontal inflammation.

MATERIALS AND METHODS

This prospective cohort study included 51 Japanese patients with type 2 diabetes who underwent intensive diabetes care including educational hospitalization and regular outpatient treatment for 6 months. Dental prophylaxis without subgingival scaling was provided three times during the observational period. Associations between changes in periodontal parameters and glycaemic control levels were evaluated using multiple regression analysis.

RESULTS

Overall, 33 participants (mean age: 58.7 ± 12.9) were followed up for 6 months. At baseline examination, 82% were diagnosed with Stage III or IV periodontitis. Haemoglobin A1c (HbA1c) level changed from 9.6 ± 1.8% at baseline to 7.4 ± 1.3% at 6 months. The ratio of probing pocket depth (PPD) ≥4 mm, bleeding on probing (BOP), full-mouth plaque control record (PCR), periodontal epithelial surface area (PESA) and periodontal inflamed surface area (PISA) also significantly improved. The reduction in PPD and PESA was significantly associated with changes in both HbA1c and fasting plasma glucose (FPG) levels, and the reduction in PISA was significantly associated with an improvement in FPG after adjusting for smoking, change in body mass index and full-mouth PCR.

CONCLUSIONS

This is the first study to report a significant improvement in PPD and BOP after intensive diabetes care and dental prophylaxis without subgingival scaling.

CLINICAL TRIAL REGISTRATION NUMBER

UMIN000040218.

Genetic analysis of impaired healing responses after periodontal therapy in type 2 diabetes: Clinical and in vivo studies

OBJECTIVE

This study aims to investigate the mechanisms underlying the impaired healing response by diabetes after periodontal therapy.

BACKGROUND

Outcomes of periodontal therapy in patients with diabetes are impaired compared with those in patients without diabetes. However, the mechanisms underlying impaired healing response to periodontal therapy have not been sufficiently investigated.

MATERIALS AND METHODS

Zucker diabetic fatty (ZDF) and lean (ZL) rats underwent experimental periodontitis by ligating the mandibular molars for one week. The gingiva at the ligated sites was harvested one day after ligature removal, and gene expression was comprehensively analyzed using RNA-Seq. In patients with and without type 2 diabetes (T2D), the corresponding gene expression was quantified in the gingiva of the shallow sulcus and residual periodontal pocket after non-surgical periodontal therapy.

RESULTS

Ligation-induced bone resorption and its recovery after ligature removal were significantly impaired in the ZDF group than in the ZL group. The RNA-Seq analysis revealed 252 differentially expressed genes. Pathway analysis demonstrated the enrichment of downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway. PPARα and PPARγ were decreased in mRNA level and immunohistochemistry in the ZDF group than in the ZL group. In clinical, probing depth reduction was significantly less in the T2D group than control. Significantly downregulated expression of PPARα and PPARγ were detected in the residual periodontal pocket of the T2D group compared with those of the control group, but not in the shallow sulcus between the groups.

CONCLUSIONS

Downregulated PPAR subtypes expression may involve the impaired healing of periodontal tissues by diabetes.

Effect of adjuvant probiotic therapy (Lactobacillus reuteri) in the treatment of periodontitis associated with diabetes mellitus: clinical, controlled, and randomized study

OBJECTIVES

Subgingival instrumentation (SI) with probiotics may be a proposal for the treatment of periodontitis (P), for patients with type 2 diabetes mellitus (T2DM). The Lactobacillus reuteri probiotic as an adjunctive therapy in the treatment of P associated with T2DM was evaluated.

MATERIALS AND METHODS

Forty diabetic participants diagnosed with P (stage III and IV, grade B) were randomized into SI + Placebo (n = 20): subgingival instrumentation plus placebo lozenges and SI + Probi (n = 20): subgingival instrumentation plus probiotics. Probing depth (PD), gingival recession (GR), clinical attachment level (CAL), plaque index (PI), bleeding on probing (BoP), and PISA index were performed at baseline and 30, 90, and 180 days. Cytokine concentration in the gingival crevicular fluid, subgingival biofilm sample, and LDL and HDL subfractions were evaluated.

RESULTS

In the deep pockets, PD in SI + Probi showed increased values (p = 0.02) compared to SI + Placebo at 90 days. For CAL, SI + Probi showed increased values compared to SI + Placebo, with a significant difference at 30 days (p = 0.03), 90 days (p = 0.02), and 180 days (p = 0.04). At #PD ≥ 7 mm, SI + Probi had a more frequent number of sites (p = 0.03) compared to SI + Placebo only at baseline. For the PISA, SI + Probi showed a significant difference (p = 0.04) compared to SI + Placebo at 90 days. For cytokines, SI + Probi showed higher quantification than SI + Placebo for IL-10 (p < 0.001) at 90 days, IL-12 (p = 0.010) at 90 days, IL-1β (p = 0.035) at 90 days, and IL-8 (p = 0.003) at baseline. SI + Placebo showed higher quantification of IL-1β (p = 0.041) compared to SI + Probi only at 30 days. There was a reduction in all microbial complexes. SI + Probi improved LDL size (246.7 nm vs 260.4 nm; p < 0.001), while large HDL subfractions were reduced aft 180 days of treatment (24.0% vs 20.3%; p = 0.022) when compared with SI + Placebo; this response was dependent of probiotics (1.0 mg/dL vs - 6.2 mg/dL; p = 0.002).

CONCLUSION

Subgingival instrumentation improved the clinical periodontal parameters in patients with T2DM. The use of L. reuteri probiotics had no additional effects compared with the placebo; however, there was a positive effect on the lipoprotein subfraction.

CLINICAL RELEVANCE

Scientific rationale for study: subgingival instrumentation with probiotics may be a proposal for the treatment of periodontitis (P), especially for patients with type 2 diabetes mellitus (T2DM).

PRINCIPAL FINDINGS

the use of L. reuteri probiotics had no additional effects compared with the placebo; however, there was a positive effect on the lipoprotein subfraction.  Practical implications: L. reuteri as an adjunct to subgingival instrumentation may have significant therapeutic implications in dyslipidemia.

Investigation on the association between serum lipid levels and periodontitis: a bidirectional Mendelian randomization analysis

OBJECTIVE

Several research has considered the potential correlation between periodontitis and serum lipids. However, serum lipid profiles correlation with periodontitis remains largely unknown. The investigation objective was to examine periodontitis correlation with serum lipid levels using a bidirectional Mendelian randomization (MR) analysis.

METHODS

The study employed a bidirectional MR analysis with two samples, utilizing a freely accessible genome-wide association study (GWAS). Furthermore, the primary analysis employed the inverse variance weighted (IVW) method. To determine whether the lipid profiles were associated with periodontitis, a variety of sensitivity analyses (including MR-Egger regression, MR-PRESSO, and weighted median), as well as multivariable MR, were employed.

RESULTS

MR analysis performed by IVW did not reveal any relationship between periodontitis and low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG), or total cholesterol (TC). It was also found that LDL, HDL, TG, and TC were not associated to periodontitis. Furthermore, the MR estimations exhibited consistency with other MR sensitivity and multivariate MR (MVMR) analyses. These results show that the correlation between serum lipid levels and periodontitis could not be established.

CONCLUSION

The finding indicates a negligible link between periodontitis and serum lipid levels were identified, despite previous observational studies reporting a link between periodontitis and serum lipid levels.

Influence of Reactive Oxygen Species on Wound Healing and Tissue Regeneration in Periodontal and Peri-Implant Tissues in Diabetic Patients

Diabetes mellitus (DM) is associated with periodontal disease. Clinically, periodontal treatment is less effective for patients with DM. Oxidative stress is one of the mechanisms that link DM to periodontitis. The production of reactive oxygen species (ROS) is increased in the periodontal tissues of patients with DM and is involved in the development of insulin resistance in periodontal tissues. Insulin resistance decreases Akt activation and inhibits cell proliferation and angiogenesis. This results in the deterioration of wound healing and tissue repair in periodontal tissues. Antioxidants and insulin resistance ameliorants may inhibit ROS production and improve wound healing, which is worsened by DM. This manuscript provides a comprehensive review of the most recent basic and clinical evidence regarding the generation of ROS in periodontal tissues resulting from microbial challenge and DM. This study also delves into the impact of oxidative stress on wound healing in the context of periodontal and dental implant therapies. Furthermore, it discusses the potential benefits of administering antioxidants and anti-insulin resistance medications, which have been shown to counteract ROS production and inflammation. This approach may potentially enhance wound healing, especially in cases exacerbated by hyperglycemic conditions.

Endothelial Insulin Resistance Exacerbates Experimental Periodontitis

Epidemiological studies suggest that the severity of periodontitis is higher in people with diabetes than in healthy individuals. Insulin resistance might play a crucial role in the pathogenesis of multiple diabetic complications and is reportedly induced in the gingiva of rodents with type 2 diabetes; however, the molecular mechanisms underlying the pathogenesis of diabetes-related periodontitis remain unclear. Therefore, we aimed to investigate whether endothelial insulin resistance in the gingiva may contribute to the pathogenesis of periodontitis as well as elucidate its underlying molecular mechanisms. We demonstrated that insulin treatment downregulated lipopolysaccharide (LPS)-induced or tumor necrosis factor α (TNFα)-induced VCAM1 expression in endothelial cells (ECs) via the PI3K/Akt activating pathway, resulting in reduced cellular adhesion between ECs and leukocytes. Hyperglycemia-induced selective insulin resistance in ECs diminished the effect of insulin on LPS- or TNFα-stimulated VCAM1 expression. Vascular endothelial cell-specific insulin receptor knockout (VEIRKO) mice exhibited selective inhibition of the PI3K/Akt pathway in the gingiva and advanced experimental periodontitis-induced alveolar bone loss via upregulation of Vcam1, Tnfα, Mcp-1, Rankl, and neutrophil migration into the gingiva compared with that in the wild-type (WT) mice despite being free from diabetes. We also observed that insulin-mediated activation of FoxO1, a downstream target of Akt, was suppressed in the gingiva of VEIRKO and high-fat diet (HFD)-fed mice, hyperglycemia-treated ECs, and primary ECs from VEIRKO. Further analysis using ECs transfected with intact and mutated FoxO1, with mutations at 3 insulin-mediated phosphorylation sites (T24A, S256D, S316A), suggested that insulin-mediated regulation of VCAM1 expression and cellular adhesion of ECs with leukocytes was attenuated by mutated FoxO1 overexpression. These results suggest that insulin resistance in ECs may contribute to the progression of periodontitis via dysregulated VCAM1 expression and cellular adhesion with leukocytes, resulting from reduced activation of the PI3K/Akt/FoxO1 axis.

Dysregulation of CXCL1 Expression and Neutrophil Recruitment in Insulin Resistance and Diabetes-Related Periodontitis in Male Mice

Insulin resistance and hyperglycemia are risk factors for periodontitis and poor wound healing in diabetes, which have been associated with selective loss of insulin activation of the PI3K/Akt pathway in the gingiva. This study showed that insulin resistance in the mouse gingiva due to selective deletion of smooth muscle and fibroblast insulin receptor (SMIRKO mice) or systemic metabolic changes induced by a high-fat diet (HFD) in HFD-fed mice exacerbated periodontitis-induced alveolar bone loss, preceded by delayed neutrophil and monocyte recruitment and impaired bacterial clearance compared with their respective controls. The immunocytokines, CXCL1, CXCL2, MCP-1, TNFα, IL-1β, and IL-17A, exhibited delayed maximal expression in the gingiva of male SMIRKO and HFD-fed mice compared with controls. Targeted overexpression of CXCL1 in the gingiva by adenovirus normalized neutrophil and monocyte recruitment and prevented bone loss in both mouse models of insulin resistance. Mechanistically, insulin enhanced bacterial lipopolysaccharide-induced CXCL1 production in mouse and human gingival fibroblasts (GFs), via Akt pathway and NF-κB activation, which were reduced in GFs from SMIRKO and HFD-fed mice. These results provided the first report that insulin signaling can enhance endotoxin-induced CXCL1 expression to modulate neutrophil recruitment, suggesting CXCL1 as a new therapeutic direction for periodontitis or wound healing in diabetes.

ARTICLE HIGHLIGHTS

The mechanism for the increased risks for periodontitis in the gingival tissues due to insulin resistance and diabetes is unclear. We investigated how insulin action in gingival fibroblasts modulates the progression of periodontitis in resistance and diabetes. Insulin upregulated the lipopolysaccharide-induced neutrophil chemoattractant, CXCL1, production in gingival fibroblasts via insulin receptors and Akt activation. Enhancing CXCL1 expression in the gingiva normalized diabetes and insulin resistance-induced delays in neutrophils recruitment and periodontitis. Targeting dysregulation of CXCL1 in fibroblasts is potentially therapeutic for periodontitis and may also improve wound healing in insulin resistance and diabetes.

Systemic Inflammation, Endothelial Function, and Risk of Periodontitis in Overweight/Obese Adults

The network interaction between systemic inflammatory mediators, endothelial cell adhesion function, and adiponectin as mediators of the association between metabolic diseases and periodontitis has not been evaluated. The objective of this study is to assess whether the interaction of baseline serum levels of TNF-α, hs-CRP, ICAM-1, VCAM-1, and adiponectin leads to periodontitis. Five hundred and ninety-seven overweight/obese (overweight: BMI 25 to <30 kg/m2; obese: >30 kg/m2) adults, aged 40-65 years, with complete 3-year follow-up data were included. Generalized structural equation models with negative binomial regression were used to estimate the regression coefficient (β) for the outcome number of teeth with probing pocket depth (PPD) ≥ 4 mm and bleeding on probing (BOP) at 3-year follow-up for a 1 standard deviation unit increase (Δ = +1SD) in each biomarker. After adjusting for multiple covariates, baseline ICAM-1 and VCAM-1 had significant direct effects on increased log-transformed number of teeth with PPD ≥ 4 mm and BOP (β: 0.16; 95% CI: 0.02-0.30; β: 0.15; 95% CI: 0.02-0.30, respectively). Baseline hs-CRP showed a significant indirect effect via ICAM-1 on the log-transformed number of teeth with PPD ≥ 4 mm and BOP (β: 4.84; 95% CI: 0.27-9.42). Thus, elevated serum ICAM-1 and VCAM-1 have a significant direct effect and increased hs-CRP has a significant indirect effect on the predicted level of periodontitis at the 3-year follow-up among overweight/obese Hispanic adults.

High-fat diet-induced metabolic syndrome increases ligature-induced alveolar bone loss in mice

BACKGROUND

It has been well documented that metabolic syndrome (MetS) increases severity of periodontitis. In this study, we determined the effect of high-fat diet (HFD)-induced MetS on alveolar bone loss in a mouse model with ligature-induced periodontitis. To understand how MetS increases bone loss, we tested our hypothesis that palmitic acid (PA), a most abundant saturated fatty acid in the HFD, interacts with lipopolysaccharide (LPS) to promote osteoclastogenesis.

METHODS

We induced MetS by feeding mice HFD for 18 weeks and induced periodontitis with ligature placement. After treatments, we assessed alveolar bone loss using micro-computed tomography and determined osteoclastogenesis using tartrate-resistant acid phosphatase (TRAP) staining. To explore the mechanisms, we treated macrophages with PA, LPS or both and analyzed the osteoclast formation and cytokine expression in macrophages.

RESULTS

While ligature robustly induced periodontitis in mice with or without MetS, the mice with MetS had more bone loss than those without MetS. PA and LPS cooperatively induced osteoclast formation and stimulated the expression of inflammatory cytokines involved in osteoclastogenesis potentially via a FAT/CD36-dependent mechanism in macrophages.

CONCLUSIONS

HFD-induced MetS increases alveolar bone loss in mice with ligature-induced periodontitis, and PA and LPS cooperatively stimulate osteoclast formation and proinflammatory gene expression in macrophages.

Myeloid-derived growth factor regulates high glucose-mediated apoptosis of gingival fibroblasts and induce AKT pathway activation and nuclear factor κB pathway inhibition

Background

/purpose: Periodontal disease is a chronic inflammatory disease that occurs in the tissues that support and attach teeth. There is considerable evidence of a relationship between diabetes and periodontal disease. Emerging studies have reported that myeloid-derived growth factor (MYDGF) can inhibit apoptosis and inflammation. The purpose of this study was to investigate whether MYDGF mediates the role of hyperglycemia in fibroblasts in periodontitis tissues.

Materials and methods

Fibroblasts were isolated and cultured from normal gums. Gene expression levels were detected by RT-PCR. The protein level was detected by western blotting. Cell viability was determined by MTT assay. To investigate the role of MYDGF, the plasmid was transfected into fibroblasts. The expression levels of cytokines were determined by ELISA.

Results

High glucose can down-regulate the expression of MYDGF in human gingival fibroblasts in a time-dependent manner, and decrease the fibroblast activity. SOD level was decreased and MDA level was increased in gingival fibroblasts by high glucose. High glucose up-regulates pro-apoptotic indicator Bax, down-regulates anti-apototic indicator Bcl-2, and increased endoplasmic reticulum stress related indicators Nox 2, GRP78, ATF6, and PERK. In addition, high glucose increased TNF-α, IL-1β, IL-8 and CXCL1 protein levels in fibroblasts. Our study also found that high glucose inhibits the AKT signaling pathway and activates the nuclear factor κB (NF-κB) pathway. Interestingly, overexpression of MYDGF reversed these effects.

Conclusion

MYDGF is down-regulated in gingival fibroblasts induced by high glucose. Overexpression of MYDGF inhibits apoptosis induced by high glucose, inhibits oxidative stress and cytokine secretion of gingival fibroblasts induced by high glucose, and induces AKT pathway activation and NF-κB pathway inhibition.

Association of type 2 diabetes with periodontitis and tooth loss in patients undergoing hemodialysis

BACKGROUND

Limited evidence are available regarding the influence of diabetes on periodontitis in hemodialysis patients, although the association between diabetes and periodontal disease is well-known.

OBJECTIVE

This study aimed to investigate the influence of type 2 diabetes mellitus (T2D) and its control level on periodontal disease and the number of missing teeth in patients undergoing hemodialysis.

SUBJECTS AND METHODS

A single-center cross-sectional study was conducted on 246 Japanese patients with end-stage renal disease undergoing hemodialysis. Comprehensive medical and dental examinations were performed. The association between severity of periodontitis and T2D was examined by multiple ordered logistic regression analysis. A multiple linear regression model was fitted to assess the association of periodontal probing depth (PPD) ≥4 mm and the number of missing teeth with T2D (n = 125). A subgroup analysis involving only the patients with T2D was performed to investigate the factors associated with missing teeth among them.

RESULTS

After adjusting for confounders, the classification of periodontitis severity was significantly advanced in patients with T2D (odds ratio: 1.64, 95% confidence interval [CI]: 1.02-2.65, p = 0.04). The proportion of PPD≥4 mm sites and the number of missing teeth was significantly associated with T2D (coefficient: 4.1 and 5.7, 95% CI: 0.2-8.0 and 3.4-8.0, p = 0.04 and <0.001, respectively). Subgroup analysis of T2D patients revealed that glycoalbumin levels (coefficient: 0.4, 95% CI: 0.03-0.80, p = 0.03), but not hemoglobin A1c levels (coefficient: 0.8, 95% CI: -1.0-2.7, p = 0.37), were significantly associated with the number of missing teeth.

CONCLUSION

T2D was significantly associated with periodontitis and the number of missing teeth in hemodialysis patients. Moreover, it is first documented that poor glycemic control, as determined by glycoalbumin levels, was significantly associated with the number of missing teeth in hemodialysis patients with T2D.

Astaxanthin Enhances Gingival Wound Healing following High Glucose-Induced Oxidative Stress

Fibroblasts of the gingiva play a key role in oral wound healing in diabetes. In this study, effects of astaxanthin (ASTX), a xanthophyll carotenoid, were tested on gingival fibroblasts in a wound healing assay in vitro. The aim of this study was to determine whether ASTX can recover delayed wound healing or not when oxidative stress is elevated by high glucose exposure. For this purpose, human gingival fibroblasts were incubated with or without ASTX following exposure to systemic doses of low glucose (LG) and high glucose (HG) in culture media (5- and 25-, 50 mM D-glucose in DMEM Ham's F12) following 24 hours of incubation. Levels of ROS (Reactive oxygen species) were determined for each experimental group by confocal microscopy. Cell proliferation and viability were assessed by an automated cell counter with trypan blue assay. Wound healing assay was designed in 60 mm petri dishes. Cells were exposed to 5-, 25-, and 50 mM glucose for 24 hours, and a straight line free of cells was created upon full confluency. 100 μM ASTX was added to the recovery group, simultaneously. Cells were monitored with JuLI^Ⓡ-Br Cell History Recorder. ROS levels were significantly increased with increasing glucose levels, while cell proliferation and viability demonstrated a negative correlation with increasing oxidative stress. ROS levels significantly decreased in the 100 μM ASTX-treated group compared to the gingival fibroblasts treated with 50 mM HG medium-only, as well as growth rate and viability. Wound healing was delayed in a dose-dependent manner following high glucose exposure, while ASTX treatment recovered wounded area by 1.16-fold in the 50 mM HG group. Our results demonstrated that ASTX enhances gingival wound healing through its antioxidative properties following high glucose induced oxidative stress. Therefore, ASTX can be suggested as a promising candidate to maintain oral health in chronic wounds of the oral tissues related to diabetes.

The Link Between Periodontal Inflammation and Obesity

Purpose of Review

Obesity is a trigger for multiple diseases such as diabetes mellitus, hypertension, and cardiovascular diseases. Epidemiological studies have shown that obesity may be a risk factor for periodontal disease. Recently, there have been reports of presumed mechanisms of the associations between periodontitis and lipid metabolism or thermogenesis. This review aims to discuss the link between periodontal disease and energy regulatory function based on recent findings.

Recent Findings

It has been demonstrated that activation of the C–C motif chemokine ligand/C–C chemokine receptor 7 pathway in adipose tissue induces inflammation and impairment of lipid metabolism and energy regulation in mice. Porphyromonas gingivalis administration has been shown to induce further weight gain and increased adipose tissue in diet-induced obese mice. Additionally, it has been reported that Porphyromonas gingivalis–induced endotoxemia potentially affect obesity by altering endocrine functions in brown adipose tissue in mice. Several cohort studies have shown that obesity is associated with tooth loss 5 years later, and periodontal conditions of obese individuals are significantly worse 2 and 6 months after the treatment compared with those of non-obese individuals. It has also been reported that body mass index is positively associated with the periodontal inflamed surface area index, a measure of periodontal inflammation. These results suggest that not only the enhancement of inflammation due to obesity but also the activation of inflammatory signaling may affect energy regulation.

Summary

Loss of adipose tissue homeostasis induces increase and activation of immune cells in adipose tissue, leading to impaired immune function in obesity. Various cytokines and chemokines are secreted from obese adipose tissue and promote inflammatory signaling. Some of these signaling pathways have been suggested to affect energy regulation. The combination of obesity and periodontitis amplifies inflammation to levels that affect the whole body through the adipose tissue. Obesity, in turn, accelerates the exacerbation of periodontitis.

Metformin accelerates wound healing by Akt phosphorylation of gingival fibroblasts in insulin-resistant prediabetes mice

BACKGROUND

This study aimed to investigate the effects of metformin on gingival wound healing in insulin-resistant prediabetes.

METHODS

C57BL/6J mice were fed normal diet (ND) or high-fat diet (HFD) for 10 weeks; half of the HFD mice were treated with metformin (HFD+ Met) for the last 2 weeks. Insulin and glucose tolerance tests were performed. The palatal gingiva (2.0 × 0.5 mm) was surgically removed adjacent to the maxillary molars. Post-surgical wound closure was histomorphometrically evaluated for 1 week. The mRNA expression of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in the tissue were quantified by real-time polymerase chain reaction. In vitro, the proliferation and migration of human gingival fibroblasts (HGFs) cultured under high-glucose or control conditions with/without metformin were analyzed. Akt phosphorylation and VEGF expression following the insulin stimulation were evaluated with/without metformin in high-glucose or control media.

RESULTS

HFD mice showed significantly higher plasma glucose levels and insulin resistance than ND mice. Gingival wound healing was delayed in HFD group compared with ND group but significantly improved in HFD + MET group. The decreased expression of VEGF and eNOS in HFD group was significantly elevated in the HFD + MET group. The proliferation and migration of HGFs were significantly impaired in high-glucose conditions compared with control; metformin treatment partially attenuated these effects. Metformin treatment significantly recovered the downregulated Akt phosphorylation and VEGF expression in high-glucose conditions.

CONCLUSIONS

Metformin improved delayed gingival wound healing in insulin-resistant prediabetes by accelerating HGFs proliferation and migration via Akt phosphorylation in insulin signaling pathway.

Effects of Antioxidant in Adjunct with Periodontal Therapy in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis

This review investigated whether the adjunctive use of antioxidants with periodontal therapy improves periodontal parameters in patients with type 2 diabetes. A systematic and extensive literature search for randomized controlled trials (RCTs) conducted before April 2021 was performed on the PubMed, Cochrane Library, and Web of Science databases. The risk of bias was assessed using the Cochrane risk-of-bias tool. A meta-analysis was performed to quantitatively evaluate the clinical outcomes following periodontal therapy. After independent screening of 137 initial records, nine records from eight RCTs were included. The risk-of-bias assessment revealed that all RCTs had methodological weaknesses regarding selective bias, although other risk factors for bias were not evident. This meta-analysis of two RCTs showed that periodontal pocket depths were significantly reduced in the groups treated with combined non-surgical periodontal therapy and melatonin than in those treated with non-surgical periodontal therapy alone. The present systematic review and meta-analysis suggest that the adjunctive use of melatonin, resveratrol, omega-3 fatty acids with cranberry juice, propolis, and aloe vera gel with periodontal therapy significantly improves periodontal disease parameters in patients with type 2 diabetes, and melatonin application combined with non-surgical periodontal therapy might significantly reduce periodontal pocket depth. However, there are still limited studies of melatonin in combination with non-surgical periodontal therapy in Type 2 diabetic patients, and more well-designed RCTs are required to be further investigated.

Association between periodontal inflammation and serum lipid profile in a healthy population: A cross-sectional study

AIMS

The impact of periodontal inflammation on lipid metabolism is controversial. This study aimed to investigate the association between full-mouth periodontal inflammation and serum lipid levels.

MATERIALS AND METHODS

In this cross-sectional study, we performed periodontal and bacteriological examinations during medical checkup on 131 subjects. The association between the periodontal inflamed surface area (PISA) and the lipid markers was analyzed by multiple linear regression, adjusting for age, sex, smoking, and body mass index.

RESULTS

Overall, 118 medically healthy participants were analyzed. The proportions of none, mild, moderate, and severe periodontitis were 37.3%, 32.2%, 25.4%, and 5.1%, respectively. Multivariate analysis showed that high-density lipoprotein cholesterol was significantly higher in participants with the lowest tertile of PISA values (PISA low, coefficient: 7.94; 95% confidence interval [CI]: 1.63, 14.26, p = .01) compared to those in other tertiles (PISA high). Low-density/high-density lipoprotein cholesterol and total/high-density lipoprotein cholesterol ratios were significantly lower in the PISA-low group than the PISA-high group (coefficient: -0.26 and -0.30; 95% CI: -0.50, -0.02, and -0.59, -0.0002; p = .04 and .0498). Serum high-sensitivity C-reactive protein level, but not serum Porphyromonas gingivalis antibody titer, partly explained the association between PISA and high-density lipoprotein cholesterol. A significant interaction between female sex and PISA values toward high-density lipoprotein cholesterol level was detected.

CONCLUSION

Periodontal inflammation was inversely associated with higher high-density lipoprotein cholesterol, especially in females. Elevated serum C-reactive protein partly explained this association.

Long-term observation of periodontal condition following placement of removable partial dentures with rigid retainers and major connector in patients with/without diabetes: A retrospective study

PURPOSE

This retrospective study evaluated the periodontal tissues of the abutment teeth of removable partial dentures (RPDs) with rigid retainers and major connectors in patients with and without type 2 diabetes mellitus (T2D).

METHODS

A total of 313 patients who had been treated with RPDs, including rigid retainers and major connectors, were divided into two groups: T2D and non-T2D. The periodontal parameters and radiographic bone heights of the abutment teeth were evaluated at baseline and at a 5-year examination during supportive periodontal therapy (SPT). For patients with accessible standardized radiographs, bone density was analyzed based on the gray level (GL) using digital subtraction radiography (n = 83).

RESULTS

Overall, 739 abutment teeth (86 in the T2D group) of 235 patients (25 in the T2D group) were analyzed, and 95.0% (94.2% in the T2D group, and 95.2% in the non-T2D group) were maintained. The mean probing pocket depth significantly increased in both groups ( p < 0.001). There were significant changes in the radiographic bone height (p = 0.038) and GL on the side of the denture base area (p = 0.048) in the T2D group compared to those in the non-T2D group.

CONCLUSIONS

Regardless of T2D, RPDs with rigid retainers and major connectors could prevent the progression of periodontal disease and successfully maintain most of the abutment teeth during 5-years of SPT. However, T2D may be significantly associated with loss of bone height reduction and density on the side of the denture base area.

Insulin's actions on vascular tissues: Physiological effects and pathophysiological contributions to vascular complications of diabetes

Background

Insulin has been demonstrated to exert direct and indirect effects on vascular tissues. Its actions in vascular cells are mediated by two major pathways: the insulin receptor substrate 1/2-phosphoinositide-3 kinase/Akt (IRS1/2/PI3K/Akt) pathway and the Src/mitogen-activated protein kinase (MAPK) pathway, both of which contribute to the expression and distribution of metabolites, hormones, and cytokines.

Scope of review

In this review, we summarize the current understanding of insulin's physiological and pathophysiological actions and associated signaling pathways in vascular cells, mainly in endothelial cells (EC) and vascular smooth muscle cells (VSMC), and how these processes lead to selective insulin resistance. We also describe insulin's potential new signaling and biological effects derived from animal studies and cultured capillary and arterial EC, VSMC, and pericytes. We will not provide a detailed discussion of insulin's effects on the myocardium, insulin's structure, or its signaling pathways' various steps, since other articles in this issue discuss these areas in depth.

Major conclusions

Insulin mediates many important functions on vascular cells via its receptors and signaling cascades. Its direct actions on EC and VSMC are important for transporting and communicating nutrients, cytokines, hormones, and other signaling molecules. These vascular actions are also important for regulating systemic fuel metabolism and energetics. Inhibiting or enhancing these pathways leads to selective insulin resistance, exacerbating the development of endothelial dysfunction, atherosclerosis, restenosis, poor wound healing, and even myocardial dysfunction. Targeted therapies to improve selective insulin resistance in EC and VSMC are thus needed to specifically mitigate these pathological processes.

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Insulin's actions in vascular cells have a significant influence on systemic metabolism.

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Insulin exerts its vascular effects through its receptors and signaling cascades.

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Inhibition or enhancement of different insulin signaling leads to selective insulin resistance.

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Loss of insulin's actions causes endothelial dysfunction and vascular complications in diabetes.

Association of periodontal pocket area with type 2 diabetes and obesity: a cross-sectional study

INTRODUCTION

The aim was to investigate the relationship of full-mouth inflammatory parameters of periodontal disease with diabetes and obesity.

RESEARCH DESIGN AND METHODS

This cross-sectional study conducted diabetes-related examinations and calculated periodontal inflamed and epithelial surface area (PISA and PESA) of 71 Japanese patients with type 2 diabetes. Multiple linear regression analyses were performed to evaluate associations between PISA or PESA and diabetes and obesity parameters.

RESULTS

Median value of body mass index (BMI), hemoglobin A1c (HbA1c) level, fasting plasma glucose (FPG) level, and visceral fat area (VFA) were 25.7 kg/m2, 9.1%, 151 mg/L, and 93.3 cm2, respectively. PISA and PESA were significantly associated with HbA1c after adjusting for age, sex, BMI, smoking status, and full-mouth plaque control level (PISA: coefficient=38.1, 95% CI 8.85 to 67.29, p=0.001; PESA: coefficient=66.89, 95% CI 21.44 to 112.34, p=0.005). PISA was also significantly associated with the highest FPG tertile (>175 mg/dL) after adjusting for confounders (coefficient=167.0, 95% CI 48.60 to 285.4, p=0.006). PISA and PESA were not significantly associated with BMI or VFA.

CONCLUSION

PISA was associated with FPG and HbA1c, but not with obesity parameters, independent from confounders such as full-mouth plaque control level in patients with type 2 diabetes.

Poor oral hygiene and dental caries predict high mortality rate in hemodialysis: a 3-year cohort study

The aim of this study was to investigate the impact of oral hygiene, periodontal diseases, and dental caries on all-cause mortality in hemodialysis. This prospective cohort study included 266 patients with end-stage renal disease who were undergoing hemodialysis. Medical interviews, blood biochemical tests, and comprehensive dental examinations including periodontal pocket examination on all teeth and dental plaque accumulation by debris index-simplified (DI-S), were performed. Survival rates were assessed at a 3-year follow-up. Overall, 207 patients were included in the longitudinal analysis, and 38 subjects died during the follow-up period. Cox proportional hazards analysis of the multivariate model demonstrated that the highest tertile of DI-S had a significantly higher risk of all-cause mortality than the lowest two tertiles after adjustment for age, sex, smoking habit, body mass index, diabetes, prior cardiovascular disease, hemodialysis vintage, high sensitivity C-reactive protein, albumin, and number of remaining teeth (hazard ratio, 3.04; 95% confidence interval, 1.50–6.17; p = 0.002). Moreover, the number of decayed teeth significantly increased the hazard ratio to 1.21 (95% confidence interval, 1.06.1.37; p = 0.003). This study suggests that accumulated dental plaque and untreated decay, but not periodontal disease, may be independently associated with all-cause mortality in patients undergoing hemodialysis.

Periodontal regenerative therapy in patients with type 2 diabetes using minimally invasive surgical technique with enamel matrix derivative under 3-year observation: A prospective cohort study

BACKGROUND

Information regarding periodontal regenerative therapy in patients with diabetes mellitus (DM) is limited. This pilot study compared the regenerative outcomes of minimally invasive periodontal surgery using enamel matrix derivative (EMD) between DM and non-DM patients.

METHODS

This prospective study included deep intrabony defects in patients with or without type 2 DM. Minimally invasive surgical technique (MIST) or modified MIST (M-MIST) using EMD, without bone graft materials, was performed. Periodontal examination and intraoral radiography were performed at baseline, 6 months, and 1 and 3 years after surgery.

RESULTS

Ten sites of 10 subjects in the DM group, and 20 sites of 18 subjects in non-DM group were evaluated (mean age; 67.5 ± 7.6 and 63.1 ± 9.7, respectively). Probing depth significantly decreased from 7.1 ± 1.6 and 7.0 ± 1.3 mm to 2.2 ± 0.9 and 2.3 ± 1.1 mm at the 1-year examination in the DM and non-DM groups, respectively. Clinical attachment level (CAL) gain and radiographical defect fill at the 3-year examination were 3.8 ± 1.1 mm and 58.3% ± 10.4%, respectively, in the DM group, and 4.1 ± 1.1 mm and 65.5% ± 18.8%, respectively, in the non-DM group, showing no significant differences between the groups. Multiple regression analysis showed no significant association of CAL gain with DM or age after adjustments for relevant confounders.

CONCLUSIONS

This is the first documented study of successful periodontal tissue regeneration in patients with DM. Minimally invasive surgery combined with EMD yielded significant clinical attachment gain and bone fill in the DM and non-DM groups at comparable levels.

Can Periodontal Disease Be Considered Linked to Obesity and Lipoinflammation? Mechanisms Involved in the Pathogenesis Occurrence

Obesity is a systemic disease, associated with an increased risk of cardiovascular disorders, type 2 diabetes, cancer, asthma, and osteoarthritis. Overweight and obesity have been suggested to be associated with periodontitis as published in studies and narrative summaries. Obesity and periodontal diseases are very prevalent in the world, and both can lead to severe chronic health conditions and impair people’s life quality. Knowledge of how immune mechanisms and inflammatory responses are regulated is critical for understanding the pathogenesis of complex diseases, such as periodontitis. In conditions of overweight, it has been demonstrated that approximately 70–80% of individuals present an adipose tissue turnover that is both structurally and functionally causing of the systemic inflammatory reaction. The objective of this review is to explore the influence of lipoinflammation. The effects of lipoinflammation and obesity on development of periodontal disease are reported together with the exploration of the mechanisms of interaction between these two diseases.

Characterization of periodontitis in people with type 1 diabetes of 50 years or longer duration

BACKGROUND

Periodontitis is more common and severe in people with diabetes than the general population. We have reported in the Joslin Medalist Study that people with type 1 diabetes of ≥50 years (Medalists) may have endogenous protective factors against diabetic nephropathy and retinopathy.

METHODS

In this cross-sectional study, the prevalence of periodontitis according to the Centers for Disease Control/American Academy of Periodontology classification in a subset (n = 170, mean age = 64.6 ± 6.9 years) of the Medalist cohort, and its associations to various criteria of periodontitis and diabetic complications were assessed.

RESULTS

The prevalence of severe periodontitis in Medalists was only 13.5% which was lower than reported levels in diabetic patients of similar ages. Periodontal parameters, including bleeding on probing, plaque index, gingival index, and demographic traits, including male sex, chronological age, and age at diagnosis were significantly associated with severity of periodontitis, which did not associate with diabetes duration, hemoglobin A1c (HbA1c), body mass index, and lipid profiles. Random serum C-peptide levels inversely associated with severity of periodontitis (P = 0.03), lower probing depth (P = 0.0002), and clinical attachment loss (P = 0.03). Prevalence of cardiovascular diseases (CVD) and systemic inflammatory markers, plasma interleukin-6 (IL-6), and serum immunoglobulin G titer against Porphyromonas gingivalis positively associated with severity of periodontitis (P = 0.002 and 0.02, respectively). Antibody titer to P. gingivalis correlated positively and significantly with CVD, serum IL-6, and high-sensitivity C-reactive protein.

CONCLUSIONS

Some Medalists could be protected from severe periodontitis even with hyperglycemia. Endogenous protective factors for periodontitis could possibly be related to residual insulin production and lower levels of chronic inflammation.

Evaluating All Potential Oral Complications of Diabetes Mellitus

Diabetes mellitus (DM) is associated with several microvascular and macrovascular complications, such as retinopathy, nephropathy, neuropathy, and cardiovascular diseases. The pathogenesis of these complications is complex, and involves metabolic and hemodynamic disturbances, including hyperglycemia, insulin resistance, dyslipidemia, hypertension, and immune dysfunction. These disturbances initiate several damaging processes, such as increased reactive oxygen species (ROS) production, inflammation, and ischemia. These processes mainly exert their damaging effect on endothelial and nerve cells, hence the susceptibility of densely vascularized and innervated sites, such as the eyes, kidneys, and nerves. Since the oral cavity is also highly vascularized and innervated, oral complications can be expected as well. The relationship between DM and oral diseases has received considerable attention in the past few decades. However, most studies only focus on periodontitis, and still approach DM from the limited perspective of elevated blood glucose levels only. In this review, we will assess other potential oral complications as well, including: dental caries, dry mouth, oral mucosal lesions, oral cancer, taste disturbances, temporomandibular disorders, burning mouth syndrome, apical periodontitis, and peri-implant diseases. Each oral complication will be briefly introduced, followed by an assessment of the literature studying epidemiological associations with DM. We will also elaborate on pathogenic mechanisms that might explain associations between DM and oral complications. To do so, we aim to expand our perspective of DM by not only considering elevated blood glucose levels, but also including literature about the other important pathogenic mechanisms, such as insulin resistance, dyslipidemia, hypertension, and immune dysfunction.

Periodontal regenerative effect of enamel matrix derivative in diabetes

The present study aimed to investigate the periodontal regenerative effect of enamel matrix derivative (EMD) in diabetes. Thirty-six rats were assigned to streptozotocin-induced diabetes or control (non-diabetic) groups. Three-wall intrabony defects were surgically generated in the bilateral maxilla molar, followed by application of EMD or saline. Primary wound closure and defect fill were evaluated via histomorphological analysis and micro-computed tomography. mRNA expression levels of inflammatory and angiogenic factors in the defects were quantified via real-time polymerase chain reaction. Gingival fibroblasts were isolated from control animals and cultured in high-glucose (HG) or control medium. The effects of EMD on insulin resistance and PI3K/Akt/VEGF signaling were evaluated. The achievement rate of primary closure and the parameters of defect fill were significantly higher at EMD-treated site than at EMD-untreated sites in both diabetic and non-diabetic rats, although defect fill in the diabetic groups was significantly lower in the control groups on two-way repeated-measures analysis of variance (for both, p<0.05). Newly formed bone and cementum were significantly increased at EMD-treated sites in diabetic rats than at EMD-untreated sites in control rats (for both, p<0.05). Vegf was significantly upregulated at EMD-treated sites in both diabetic and non-diabetic rats (for both, p<0.05). In vitro, insulin or EMD-induced Akt phosphorylation was significantly lower in cells cultured in HG medium (p<0.05). EMD-mediated Vegf upregulation was suppressed by the Akt inhibitor wortmannin, although the effect was significantly lower in HG medium (p<0.01). In conclusion, EMD might promote periodontal tissue regeneration via Akt/VEGF signaling, even in a diabetic condition.

High glucose-induced oxidative stress impairs proliferation and migration of human gingival fibroblasts

Delayed gingival wound healing is widely observed in periodontal patients with diabetes. However, the molecular mechanisms of the impaired function of gingival fibroblasts in diabetes remain unclear. The purpose of this study was to investigate changes in the properties of human gingival fibroblasts (HGFs) under high-glucose conditions. Primary HGFs were isolated from healthy gingiva and cultured with 5.5, 25, 50, and 75 mM glucose for 72 h. In vitro wound healing, 5-ethynyl-2′-deoxyuridine (EdU), and water-soluble tetrazolium salt (WST-8) assays were performed to examine cell migration and proliferation. Lactase dehydrogenase (LDH) levels were measured to determine cytotoxicity. The mRNA expression levels of oxidative stress markers were quantified by real-time PCR. Intracellular reactive oxygen species (ROS) were also measured in live cells. The antioxidant N-acetyl-l-cysteine (NAC, 1 mM) was added to evaluate the involvement of ROS in the glucose effect on HGFs. As a result, the in vitro wound healing assay showed that high glucose levels significantly reduced fibroblast migration and proliferation at 6, 12, 24, 36, and 48 h. The numbers of cells positive for EdU staining were decreased, as was cell viability, at 50 and 75 mM glucose. A significant increase in LDH was proportional to the glucose concentration. The mRNA levels of heme oxygenase-1 and superoxide dismutase-1 and ROS levels were significantly increased in HGFs after 72 h of exposure to 50 mM glucose concentration. The addition of NAC diminished the inhibitory effect of high glucose in the in vitro wound healing assay. The results of the present study show that high glucose impairs the proliferation and migration of HGFs. Fibroblast dysfunction may therefore be caused by high glucose-induced oxidative stress and may explain the delayed gingival wound healing in diabetic patients.

Improved General and Oral Health in Diabetic Patients by an Okinawan-Based Nordic Diet: A Pilot Study

Periodontal disease, periodontitis as well as the preceding gingivitis, has been associated with both obesity and diabetes. Studies have shown that diet changes can lead to a lower incidence of such inflammation. The aim of the present case series over four weeks was to study the effects on medical and dental conditions in patients with type 2 diabetes of the consumption of the Okinawan-based Nordic Diet (OBND^®). Medical and dental examinations were performed to estimate the general health and gingivitis/periodontitis. Serum cytokine levels were assessed using Luminex technology. Eight of ten study participants completed the study. All participants lost weight (p = 0.012). Six out of seven that were treated with insulin could reduce their insulin intake after two weeks with OBND^®. The reduction was about 16 units which corresponds to a 34% relative reduction compared to the starting point (range 15–63%). Fasting blood glucose values fell (p = 0.035). Hemoglobin A1c (HbA1c) (p = 0.01), triglycerides (p = 0.05), and low-density lipoprotein (LDL) (p = 0.05) were also reduced. Bleeding on probing changed from ~28% before any dietary changes to ~13% after two weeks with OBND^® (p = 0.01). The reduction in gingival bleeding was as substantial as might be expected from one session of professional tooth cleaning. Markers of inflammation were also reduced. The OBND^® thus showed significant promise in alleviating the impact of diabetes on dental as well as general health.

Impact of diabetes on gingival wound healing via oxidative stress

The aim of this study is to investigate the mechanisms linking high glucose to gingival wound healing. Bilateral wounds were created in the palatal gingiva adjacent to maxillary molars of control rats and rats with streptozotocin-induced diabetes. After evaluating postsurgical wound closure by digital imaging, the maxillae including wounds were resected for histological examinations. mRNA expressions of angiogenesis, inflammation, and oxidative stress markers in the surgical sites were quantified by real-time polymerase chain reaction. Primary fibroblast culture from the gingiva of both rats was performed in high glucose and normal medium. In vitro wound healing and cell proliferation assays were performed. Oxidative stress marker mRNA expressions and reactive oxygen species production were measured. Insulin resistance was evaluated via PI3K/Akt and MAPK/Erk signaling following insulin stimulation using Western blotting. To clarify oxidative stress involvement in high glucose culture and cells of diabetic rats, cells underwent N-acetyl-L-cysteine treatment; subsequent Akt activity was measured. Wound healing in diabetic rats was significantly delayed compared with that in control rats. Nox1, Nox2, Nox4, p-47, and tumor necrosis factor-α mRNA levels were significantly higher at baseline in diabetic rats than in control rats. In vitro study showed that cell proliferation and migration significantly decreased in diabetic and high glucose culture groups compared with control groups. Nox1, Nox2, Nox4, and p47 expressions and reactive oxygen species production were significantly higher in diabetic and high glucose culture groups than in control groups. Akt phosphorylation decreased in the high glucose groups compared with the control groups. Erk1/2 phosphorylation increased in the high glucose groups, with or without insulin treatment, compared with the control groups. Impaired Akt phosphorylation partially normalized after antioxidant N-acetyl-L-cysteine treatment. Thus, delayed gingival wound healing in diabetic rats occurred because of impaired fibroblast proliferation and migration. Fibroblast dysfunction may occur owing to high glucose-induced insulin resistance via oxidative stress.

Activation and resolution of periodontal inflammation and its systemic impact

Inflammation is a highly organized event impacting upon organs, tissues and biological systems. Periodontal diseases are characterized by dysregulation or dysfunction of resolution pathways of inflammation that results in failure to heal and in a dominant chronic, progressive, destructive and predominantly unresolved inflammation. The biological consequences of inflammatory processes may be independent of the etiological agents, such as trauma, microbial organisms and stress. The impact of the inflammatory pathological process depends upon the tissues or organ system affected. Whilst mediators are similar, there is tissue specificity for the inflammatory events. It is plausible that inflammatory processes in one organ could directly lead to pathologies in another organ or tissue. Communication between distant parts of the body and their inflammatory status is also mediated by common signaling mechanisms mediated via cells and soluble mediators. This review focuses on periodontal inflammation, its systemic associations and advances in therapeutic approaches based on mediators acting through orchestration of natural pathways to resolution of inflammation. We also discuss a new treatment concept in which natural pathways of resolution of periodontal inflammation can be used to limit systemic inflammation and promote healing and regeneration.

From the Acta Prize Lecture 2014: the periodontal-systemic connection seen from a microbiological standpoint

OBJECTIVE

To give an overview of the periodontal-systemic connection seen from a microbiologist.

METHODS

Original research papers, review articles and workshop proceedings were consulted.

RESULTS

Periodontal bacteria can cross epithelial cells, enter the circulation, invade endothelial cells, induce endothelial cell dysfunction and activate inflammatory and immune responses. Several studies support the association between periodontitis (PD) and cardiovascular disease. Severe PD involves a risk for development of type 2 diabetes. Maternal PD is moderately associated with adverse pregnancy outcome and pre-eclampsia. Dental plaque can contain respiratory pathogens able to promote chronic obstructive pulmonary disease and pneumonia. Periodontal bacterial DNA has been detected in synovial fluid of patients with rheumatoid arthritis. Minor evidence exists for associations between PD and chronic kidney disease, obesity, cancer, metabolic syndrome and cognitive impairment. Concerns can be raised as to the interpretation of some study results due to heterogeneity in definitions used for PD, too much weight upon in vitro studies with a few selected organisms and failing recognition that the majority of the periodontal microbiota is not yet cultivated.

CONCLUSION

Periodontal bacteria may participate in extra-oral infections such as CVD, diabetes, APO, pre-eclampsia, COPD, pneumonia, RA, CKD, obesity, cancer, MetS and cognitive impairment. Most knowledge is based on associations which do not necessarily imply causality. Future studies should reach consensus on the definition of PD and systemic disease outcomes, recognize the full spectrum of the microbiota in PD and bacteremia, including not-yet-cultivated organisms and delineate the clinical significance of genetic strain variations and the role of periodontopathogenic vs gut organisms within atheromatous lesions. For demonstration of causality, large, long-term clinical studies should use well-defined criteria for PD and robust disease outcomes to elucidate the importance of PD intervention and prevention.

Persimmon vinegar ripening with the mountain-cultivated ginseng ingestion reduces blood lipids and lowers inflammatory cytokines in obese adolescents

[Purpose]

This study investigated the effect of the vinegar, which is made of 4-year-old mountain-cultivated ginseng ripened into 4-year-matured persimmon vinegar, on the blood lipids level and inflammatory cytokines concentration in obese female adolescents.

[Methods]

Subjects ingested the vinegar, so-called 'mountain-cultivated ginseng persimmon vinegar (MPV)', without meals every day for 6 weeks with activities control. Subjects were grouped into control (CON), persimmon vinegar (PV), and MPV with 10 people in each group. Blood lipids, triglyceride (TG), total-cholesterol (TC), and high density lipoprotein-cholesterol (HDL-C) were analyzed. Also, glutamic oxaloacetic transaminase (GOT) and glutamate pyruvate transaminase (GPT) were analyzed for the hepatotoxicity. Blood cytokines, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) were analyzed.

[Results]

Subjects showed a high reduction in body weight and body fat. Their blood lipid level was effectively improved, and the secretion of inflammatory cytokine was suppressed as well, except for TNF-α. However, the change ratio of the cytokines was high in PV and MPV. Such results were similar to those from research subjects who took persimmon vinegar only (PV), but the effect of the vinegar (MPV) was more remarkable. Besides, this mixture was found to have no effect on the hepatotoxicity.

[Conclusion]

The significance of this study is that all the experiments were conducted without controlling research subjects' daily lives, and it is suggested that the vinegar may be recommended as a kind of health supplement food to suppress obesity. Especially, since these two products are traditional foods of Korean people, which have been taken for ages, it is expected that the fusing of two foods may be better applied to ordinary people who are concerned about obesity.

Metabolic syndrome exacerbates inflammation and bone loss in periodontitis

Clinical studies have shown that metabolic syndrome (MetS) is associated with increased risk of developing periodontitis. However, the underlying mechanisms remain largely unknown. Since it is known that lipopolysaccharide (LPS)-activated toll-like receptor 4 signaling pathways play a crucial role in periodontitis, we hypothesized that MetS enhances LPS-induced periodontal inflammation and alveolar bone loss. In this study, we induced MetS in C57BL/6 mice by feeding them high-fat diet (HFD), and we induced periodontitis by periodontal injection of Aggregatibacter actinomycetemcomitans LPS. We found that mice fed a HFD had significantly increased body weight, plasma lipids, insulin, and insulin resistance when compared with mice fed regular chow, indicating that the mice developed MetS. We also found that a HFD markedly increased LPS-induced alveolar bone loss, osteoclastogenesis, and inflammatory infiltration. Analysis of gene expression in periodontal tissue revealed that HFD and LPS injection cooperatively stimulated expression of cytokines that are known to be involved in periodontal tissue inflammation and osteoclastogenesis-such as interleukin 6, monocyte-chemotactic protein 1, receptor activator of nuclear factor kappa-B ligand, and macrophage colony-stimulating factor. To further understand the potential mechanisms involved in MetS-boosted tissue inflammation, our in vitro studies showed that palmitic acid-the most abundant saturated fatty acid (SFA) and the major SFA in the HFD used in our animal study-potently enhanced LPS-induced proinflammatory gene expression in macrophages. In sum, this study demonstrated that MetS was associated with increased periodontal inflammation and alveolar bone loss in an LPS-induced periodontitis animal model. This study also suggests that SFA palmitic acid may play an important role in MetS-associated periodontitis by enhancing LPS-induced expression of inflammatory cytokines in macrophages.