Relationships among interleukin-6, tumor necrosis factor-α, adipokines, vitamin D, and chronic periodontitis

Can vitamins improve periodontal wound healing/regeneration?

Periodontitis is a complex inflammatory disorder of the tooth supporting structures, associated with microbial dysbiosis, and linked to a number if systemic conditions. Untreated it can result in an irreversible damage to the periodontal structures and eventually teeth loss. Regeneration of the lost periodontium requires an orchestration of a number of biological events on cellular and molecular level. In this context, a set of vitamins have been advocated, relying their beneficial physiological effects, to endorse the biological regenerative events of the periodontium on cellular and molecular levels. The aim of the present article is to elaborate on the question whether or not vitamins improve wound healing/regeneration, summarizing the current evidence from in vitro, animal and clinical studies, thereby shedding light on the knowledge gap in this field and highlighting future research needs. Although the present review demonstrates the current heterogeneity in the available evidence and knowledge gaps, findings suggest that vitamins, especially A, B, E, and CoQ10, as well as vitamin combinations, could exert positive attributes on the periodontal outcomes in adjunct to surgical or nonsurgical periodontal therapy.

The role of vitamin D in periodontal health and disease

Vitamin D plays an essential role in calcium and bone metabolism, immune regulation and possesses profound anti-inflammatory effects. Evidence suggests that low serum vitamin D is associated with increased severity of periodontitis, a chronic inflammatory condition characterised by destruction of the supporting tissues surrounding the tooth, which has several shared risk factors with other chronic non-communicable diseases. The biological functions of vitamin D are mediated by its strong anti-microbial, anti-inflammatory, and host modulatory properties. Experimental periodontitis models involving targeted deletion of 1α-hydroxylase, the enzyme responsible for the conversion of inactive substrate to active 1,25(OH)₂ D₃ (calcitriol), showed augmented alveolar bone loss and gingival inflammation. Vitamin D receptor (VDR) gene polymorphisms have also been associated with increased severity of periodontitis. Thus, the involvement of vitamin D in the pathogenesis of periodontitis is biological plausible. Clinical studies have consistently demonstrated an inverse relationship between serum 25OHD₃ and periodontal disease inflammation. However, due to the paucity of well-designed longitudinal studies, there is less support for the impact of vitamin D status on periodontal disease progression and tooth loss. The evidence emphasises the importance of maintaining vitamin D sufficiency in supporting periodontal health. This review aims to first examine the biological mechanisms by which vitamin D might influence the pathogenesis of periodontal disease and second, discuss the clinical evidence which implicate the role of vitamin D in periodontal disease.

Salivary irisin level is higher and related with interleukin-6 in generalized periodontitis

OBJECTIVES

Irisin plays an important role in energy homeostasis, inflammation, glucose, and lipid metabolism, and it is shown to have relations with many inflammatory diseases. The aim of the study was to determine saliva and serum irisin and IL-6 levels in patients with stage III/grade B periodontitis compared with individuals with healthy periodontium.

MATERIALS AND METHODS

Twenty patients with stage III grade B periodontitis (P) and 20 periodontally healthy subjects (control; C) were included in this study. Clinical periodontal measurements were recorded. Saliva and serum levels of irisin and interleukin-6 (IL-6) were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Salivary irisin and IL-6 levels were significantly higher in the periodontitis group (p < 0.001, p = 0.002, respectively). Furthermore, serum IL-6 levels were found significantly higher in the periodontitis group compared with controls (p = 0.011). There was no significant difference between the periodontitis and control for serum irisin levels (p > 0.05). Significant positive correlations were found between all periodontal parameters and salivary irisin and IL-6 (p < 0.05) and also between BMI and saliva and serum IL-6 (respectively; r = 0.530, r = 0.329, p < 0.05). There was a positive correlation between salivary irisin and IL-6 (r = 0.369, p < 0.05).

CONCLUSIONS

Monitoring of salivary irisin and IL-6 might be potential biomarker for predicting the susceptibility to periodontitis.

CLINICAL RELEVANCE

Scientific rationale for the study: Irisin is a novel adipomyokine that has played an important role in energy homeostasis, glucose and lipid metabolism, angiogenesis, immunity, and inflammation. Irisin is involved in the pathogenesis of diseases affecting many body systems. IL-6, another adipomyokine, is a major inflammatory mediator and homeostatic regulator of glucose and lipid metabolism and is associated with periodontitis. No studies investigated the relationship between advanced periodontal disease, irisin, and IL-6 together.

PRINCIPAL FINDINGS

The salivary irisin and IL-6 levels were significantly higher and positively correlated in patients with periodontitis relative to healthy controls. Furthermore, serum IL-6 levels were significantly increased in patients with periodontitis.

PRACTICAL IMPLICATIONS

The study shows that irisin and IL-6 can be candidate salivary biomarkers for periodontitis and predict to periodontal status.

Obesity as a modifying factor of periodontal therapy outcomes: local and systemic adipocytokines and oxidative stress markers

OBJECTIVES

Adipocytokines and oxidative stress (OS) are involved in the pathogenesis of both obesity and periodontitis. The aim of this study was to evaluate periodontal therapy outcomes in terms of serum and gingival crevicular fluid (GCF) levels of adipocytokines and OS markers in obese patients with periodontitis, in order to have an insight into the association between obesity and periodontitis.

MATERIALS AND METHODS

A total of 39 patients (20 obese, 19 non-obese) with periodontitis were included in this study. Clinical periodontal parameters were assessed; serum and GCF levels of adipocytokines and OS markers were evaluated by ELISA at baseline and 3 months after non-surgical periodontal therapy.

RESULTS

Significant improvements in clinical periodontal parameters were observed in both groups at 3 months (p < 0.01). While serum levels of TNF-α, leptin, and total oxidant status (TOS) in the obese group were higher at baseline (p < 0.01), leptin levels remained higher at 3 months despite a significant decrease (p < 0.01). Although NSPT improved GCF levels of total antioxidant status (TAS) and TOS in both groups, they were significantly different between the groups after therapy (p < 0.05).

CONCLUSIONS

It seems that leptin, TNF-α, and TOS contribute to systemic inflammatory and oxidative state in patients with obesity. Despite improvements in clinical periodontal parameters, obesity might be a modulating factor in the development and progression of periodontal disease in terms of some adipocytokines and OS markers.

CLINICAL RELEVANCE

Since the global burden of both obesity and periodontitis is continuously increasing, the management of these inflammatory diseases has become more important. The current study contributes to our understanding of the role of OS and adipocytokines on the relationship between obesity and periodontitis by response to periodontal treatment.

Central Regulatory Role of Cytokines in Periodontitis and Targeting Options

BACKGROUND

Periodontitis is an immune-inflammatory disease that leads to the progressive destruction of bone and connective tissue in the periodontal area. The cytokine network plays a primary role in tissue homeostasis, the recruitment of immune cells to control the pathogenic impact and the regulation of osteoclastic function, thus modulating the intensity and duration of the immune response. This review provides an update on the main cytokines implicated in the pathogenesis and progression of periodontitis and their targeting potential in order to enrich current treatment options.

METHODS

A structured search of bibliographic databases (PubMed, MEDLINE, Scopus) was performed for peer-reviewed cytokine studies focused on periodontitis the last ten years. A qualitative content analysis was performed in screened papers and a critical discussion of main findings is provided.

RESULTS

An altered cytokine profile has been detected in periodontitis patients and the interplay of pro-inflammatory and/or anti-inflammatory cytokines has been associated with disease pathogenesis. Among the most prominent pro-inflammatory cytokines, TNF-α, IL-1β, IL-17, IL-6 and the chemokines CXCL-6, CXCL-8 are overexpressed in periodontitis patients and correlate with disease progression. On the other hand, the anti-inflammatory IL-4 and IL- 11 levels are reduced while IL-12 and IFN-γ expression play a dual role in periodontal disease. Current periodontitis treatment strategies include selective antibiotics, antimicrobial photodynamic therapy and probiotics, which can modulate the cytokine network and when applied in combination with specific anti-cytokine agents can exert additional beneficial effects.

CONCLUSION

It is evident that cytokines play a central regulatory role in the inflammatory process and immune cell response that underlies bone destruction in periodontitis. Specific cytokine targeting should be considered as a complementary therapeutic scheme to current periodontal management.

Association of Systemic Sclerosis and Periodontitis with Vitamin D Levels

The aim of the present study was to analyze the association among systemic sclerosis (SSc), periodontitis (PT); we also evaluated the impact of PT and SSc on vitamin D levels. Moreover, we tested the association with potential confounders. A total of 38 patients with SSc, 40 subjects with PT, 41 subjects with both PT and SSc, and 41 healthy controls were included in the study. The median vitamin D levels in PT subject were 19.1 (17.6-26.8) ng/mL, while SSc + PT group had vitamin d levels of 15.9 (14.7-16.9) ng/mL, significantly lower with respect to SSc patients (21.1 (15.4-22.9) ng/mL) and to healthy subjects (30.5 (28.8-32.3) ng/mL) (p < 0.001). In all subjects, vitamin D was negatively associated with c-reactive protein (CRP) (p < 0.001) and with probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), and plaque score (PI) (p < 0.001 for all parameters) and positively related to the number of teeth (p < 0.001). Moreover, univariate regression analysis demonstrated an association among high low-density lipoproteins (LDL) cholesterol (p = 0.021), CRP (p = 0.014), and PT (p < 0.001) and reduced levels of vitamin D. The multivariate regression analysis showed that PT (p = 0.011) and CRP (p = 0.031) were both predictors of vitamin D levels. Subjects with PT and SSc plus PT had significant lower vitamin D values with respect to SSc and to healthy subjects. In addition, PT seems negatively associated with levels of vitamin D in all analyzed patients.

The role of adiponectin in periodontitis: Current state and future prospects

Adiponectin (APN), which is an adipokine primarily secreted by adipose tissue into the peripheral blood, exerts anti-inflammatory and metabolic regulatory functions in many systemic inflammatory diseases. Periodontitis is a localized inflammatory disease and is also the sixth-leading complication of diabetes. Uncontrolled periodontal inflammation gradually destructs the periodontal supporting apparatus and leads to the consequent loss of teeth. Recently, emerging evidence has revealed an association between APN and periodontitis. Herein, we summarize the basic information of APN and its receptor agonists. We also overview current studies considering the role of APN in periodontitis and discuss the potential mechanisms in terms of inflammation and bone metabolism. At last, we outline the correlation between APN and systemic diseases related periodontitis. Above all, APN and its agonists are promising candidates for the treatment of periodontitis, while the underlying mechanisms and clinical translational application require further exploration.

Comparative Evaluation of Serum Tumor Necrosis Factor α in Health and Chronic Periodontitis: A Case-Control Study

Background

Tumor necrosis factor-alpha (TNF-α), a " major inflammatory cytokine," not only plays an important role in periodontal destruction but also is extremely toxic to the host. Till date, there are not many studies comparing the levels of TNF-α in serum and its relationship to periodontal disease.

Aim

Our study aimed to compare the serum TNF-α among the two study groups, namely, healthy controls and chronic periodontitis patients and establish a correlation between serum TNF-α and various clinical parameters. Hence, an attempt is made to estimate the level of TNF-α in serum, its relationship to periodontal disease and to explore the possibility of using the level of TNF-α in serum as a biochemical " marker" of periodontal disease.

Materials and Methods

Forty individuals participated in the study and were grouped into two subgroups. Group A - 20 systemically and periodontally healthy controls. Group B - twenty patients with generalized chronic periodontitis. The serum samples were assayed for TNF-α levels by enzyme-linked immunosorbent assay method.

Results

The mean serum TNF-α cytokines for Group B Generalized chronic periodontitis (GCP) was 2.977 ± 1.011, and Group A (healthy) was 0.867 ± 0.865. The range of serum TNF-α was from (0.867 to 2.977). Serum TNF-α cytokines had highly significant correlation with all clinical parameters (plaque index, probing pocket depth, clinical attachment loss, and gingival index) among all study participants (P = 0.001).

Conclusion

These observations suggest a positive association between periodontal disease and increased levels of TNF-α in serum. It can be concluded that there is a prospect of using the estimation of TNF-α in serum as a "marker" of periodontal disease in future. However, it remains a possibility that the absence or low levels of TNF-α in serum might indicate a stable lesion and elevated levels might indicate an active site but only longitudinal studies taking into account, the disease "activity" and "inactivity" could suggest the possibility of using TNF-α in serum as an "Indicator" of periodontal disease.

Evaluation of adipokines and inflammatory mediator expression levels in patients with periodontitis and peri-implantitis: a cross-sectional study

OBJECTIVES

The aim of this study was to analyze the mRNA and protein expression of adiponectin, leptin, visfatin, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 levels in periodontitis and peri-implantitis sites in systemically healthy individuals and to investigate the influence of the presence of current periodontitis on their expression levels in peri-implantitis sites.

MATERIALS AND METHODS

Soft tissue biopsy samples were collected from 60 systemically healthy patients [15 periodontally healthy patients (group I), 16 patients with periodontitis (group II), 15 patients with peri-implantitis (group III), and 14 patients with peri-implantitis and periodontitis (group IV)]; mRNA expression levels of adiponectin, leptin, visfatin, TNF-α, and IL-6 were measured by quantitative real-time PCR; and their protein levels were assessed by immunohistochemistry.

RESULTS

The mRNA expression levels of all biomarkers were significantly higher for group II compared to group I, while significantly higher levels of leptin, TNF-α, and IL-6 were observed in group III in comparison with group I. Group II exhibited significantly higher mRNA expression of adiponectin and TNF-α than group III. Group IV showed significantly higher expression levels of adiponectin, leptin, TNF-α, and IL-6 compared to group III. Regarding the expression of protein levels, which was estimated through quantification of the histoscore, both groups II and III presented higher H-scores than group I for all biomarkers except leptin.

CONCLUSIONS

The presence of current periodontitis may enhance expression levels of adiponectin, leptin, TNF-α, and IL-6 in peri-implant soft tissue.

CLINICAL RELEVANCE

The presence of periodontitis is an important risk factor for the severity of peri-implant inflammation as well as the onset of peri-implantitis.

Adjunctive Antiseptic Irrigation of Periodontal Pockets: Effects on Microbial and Cytokine Profiles

To evaluate the effect of adjunctive antiseptic irrigation of periodontal pockets on microbial and cytokine profiles. Fifty-nine patients with severe periodontitis were allocated to one of three groups for scaling and root planing facilitated with different adjunctive antiseptics: 1% polyhexamethyleneguanidine phosphate (PHMG-P) (n = 19), 0.2% chlorhexidine (CHX) (n = 21) or distilled water (n = 19). Gingival crevicular fluid and subgingival bacterial samples were collected at baseline, and at 2 weeks, and 1 and 4 months. The levels of interleukin (IL)-1β, IL-8, IL-10, and IL-17A, matrix metalloproteinase (MMP)-8, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum,Aggregatibacter actinomycetemcomitans, and Prevotella intermedia were determined. There were no intergroup differences in cytokine concentrations and bacterial counts at any follow-up, however, varying patterns were observed. In the PHMG-P and water groups IL-1β expression peaked at 2 weeks and then gradually declined. In all three groups, the dynamics of MMP-8 concentration were non-linear, increasing by 2 weeks and then declining to below baseline (p > 0.05). P. gingivalis and T. forsythia declined within the first month and increased thereafter, not regaining the baseline level. Adjunctive antiseptic treatment was associated with changes in biomarkers and bacterial counts in the course of the study. The effects of adjunctive antiseptic irrigation were limited in the applied protocol.

A review of T helper 17 cell-related cytokines in serum and saliva in periodontitis

Periodontitis is a chronic inflammatory disease with a complex underlying immunopathology. Cytokines, as molecular mediators of inflammation, play a role in all stages of disease progression. T helper 17 (Th17) cells are thought to play a role in periodontitis. Th17 cell development and maintenance requires a pro-inflammatory cytokine milieu, with many of the cytokines implicated in the pathogenesis of periodontitis. Serum and saliva are easily accessible biofluids which can represent the systemic and local environment to promote the development of Th17 cells. Here we review human clinical studies that investigate IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, IFN-γ, sCD40L and TNF-α in serum and saliva in periodontitis. We highlight their putative role in the pathogenesis of periodontitis and place them within a wider context of animal and other clinical studies.

Association of vitamin D in patients with periodontitis: A cross-sectional study

BACKGROUND AND OBJECTIVE

Vitamin D has been considered to possess anti-inflammatory and antimicrobial activity, which may be a link for the known interaction of periodontitis (CP) and coronary heart disease (CHD). This study investigated the association between serum vitamin D levels and periodontitis in patients with CP and with CHD. Furthermore, the objective was to determine whether periodontitis and CHD had an impact on serum vitamin D levels.

MATERIAL AND METHODS

Using a cross-sectional design, a total of 46 patients with CP, 45 patients with CHD, 45 patients with both CP and CHD, and 43 healthy patients were enrolled in the present study.

RESULTS

Patients in the CP (17.4 ± 5.2 ng/mL) and in the CP + CHD (16.5 ± 5.6 ng/mL) group presented a significantly lower mean serum level of 25(OH)vitamin D compared to patients in the CHD (24.6 ± 3.7 ng/mL) and healthy control groups (29.9 ± 5.4 ng/mL) (P < .001). 25(OH)vitamin D levels were positively correlated with the number of teeth and negatively with C-reactive protein (CRP) and all periodontal parameters (P < .001). In all patients, there was a proportional increase of 25(OH)vitamin D levels with a progressive increase in number of teeth (P-trend <.001) while there were a proportional decrease in 25(OH)vitamin D levels with a progressive increase in clinical attachment level (CAL, P-trend = .001), probing depth (PD, P-trend = .006), and bleeding sites (BOP, P-trend <.001) levels.

CONCLUSION

Patients with CP and CP + CHD presented significantly lower serum levels of vitamin D compared to CHD and healthy controls. Moreover, the presence of CP negatively influenced serum vitamin D levels.

The Effects of 6-Month Vitamin D Supplementation during the Non-Surgical Treatment of Periodontitis in Vitamin-D-Deficient Patients: A Randomized Double-Blind Placebo-Controlled Study

BACKGROUND

This study assessed the effects of weekly vitamin D (VD) supplementation on clinical and biological parameters after scaling and root planning (SRP) in the treatment of periodontitis and served to validate the VD dosage regimen.

METHODS

It was a monocentric, randomized, double-blind, placebo-controlled clinical trial with 6 months follow-up. Healthy Caucasian periodontitis patients presenting serum 25(OH) vitamin D3 below 30 ng/mL were randomly allocated to test group (SRP + VD 25,000 international units (IU)/week) or the control group (SRP + placebo).

RESULTS

A total of 59 patients were screened, 27 were included and 26 completed 3 months (M) and 21 completed 6M control. Test (n = 13) and control groups (n = 14) had similar 25(OH) vitamin D3 levels at baseline (17.6 ± 7.4 vs. 14.4 ± 5.2, respectively). After one month, there was a significant difference between groups (32.9 ± 5.2 vs. 16.1 ± 4.7), also seen at M3 and M6 (t-test, p < 0.001). Periodontal treatment was successful in both groups, since it resulted in a reduction of all measured clinical parameters at M3 and M6 (probing pocket depth (PPD), full mouth bleeding and plaque). However, the reduction in PPD was greater in the test group.

CONCLUSIONS

In this short-term pilot study, no significant differences were observed between two groups. However, supplementation with VD tended to improve the treatment of periodontitis in patients with initial 25(OH) vitamin D3 < 30 ng/mL and proved safe and efficacious. NCT03162406.

Limited Evidence Suggests That Vitamin D May Help Prevent and Treat Periodontal Disease in Adults

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Serum vitamin D levels and chronic periodontitis in adult, Caucasian population-a systematic review. Peric M, Cavallier E, Toma S, Lasserre JF. J Periodontal Res 2018; 53:645-56.

SOURCE OF FUNDING

Information not available/none declared.

TYPE OF STUDY/DESIGN

Systematic review.

Biomarkers in biological fluids in adults with periodontitis and/or obesity: A meta-analysis

Obesity and periodontal diseases have been investigated to be interconnected, but the molecular mechanism underlying this association is still not clear. The aim of this systematic review is to assess the association of serum, salivary and gingival crevicular fluid (GCF) inflammatory markers (IMs), obesity, and periodontitis. Studies that evaluated IM of adults according to obesity status (O) and periodontitis status (P) (O+P+; O-P+; O+P-) were screened on several electronic databases and grey literature up until February 2019. Risk of bias assessment and level of evidence were evaluated through Fowkes and Fulton scale and Grading of Recommendations Assessment, Development and Evaluation (GRADE). Meta-analyses were grouped according to the biological matrix studied (serum/GCF) and groups (O+P+ vs. O−P+/O+P+ vs. O+P−). Out of the 832 studies screened, 21 were considered in qualitative synthesis and 15 in quantitative synthesis (meta-analysis). Although included studies showed mostly “no” or “minor” problems during the quality assessment, GRADE assessment indicated very low to moderate level of evidence based on the question answered. O+P+ adults exhibited significantly higher serum levels of C-reactive protein (CRP), interleukin 6 (IL-6), leptin, and tumor necrosis factor-α (TNF-alpha) and higher resistin GCF levels than O−P+. O+P+ adults showed significantly higher serum levels of IL-6 and leptin and lower adiponectin serum levels than O+P−. Only qualitative information could be obtained of the IM vaspin, omentin-1, chemerin, IL-10, progranulin, MCP-4, IL-1β, and interferon-γ (IFN-γ). Obesity and periodontitis, together or separately, are associated with altered serum and GCF levels of CRP, IL-6, leptin, TNF-alpha, adiponectin, and resistin. It was not possible to evaluate the association between obesity and periodontitis at salivary levels. The role of recently investigated biomarkers as vaspin, omentin-1, chemerin, IL-10, progranulin, MCP-4, IL-1β, and IFN-γ, which can be key points underlying the association between obesity and periodontitis, remains to be further investigated.

The Role of Vitamins in Oral Health. A Systematic Review and Meta-Analysis

The association between vitamins and oral health have recently been discussed, yielding increased attention from medical and dental perspectives. The present review aimed to systematically evaluate and appraise the most recently scientific papers investigating the role of vitamins in the prevention and treatment of the main oral diseases as hard dental pathological processes and gum/periodontal disease. Randomized controlled trials, cross-sectional studies, cohort studies, comparative studies, validation studies and evaluation studies, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, reporting associations between vitamins and oral diseases or the use of vitamins to prevent or treat oral diseases in patients of any age were included. PubMed, Embase and Scopus were searched to November 2019 using an ad hoc prepared search string. All the papers meeting the inclusion criteria were subjected to a quality assessment. The search identified 1597 papers; 741 were selected after removing duplicates. A total of 334 articles were excluded after title and abstract evaluation; 407 were assessed and 73 papers were full-text assessed; other 14 papers were discharged after full text evaluation, leaving finally 58 papers included. In general, there is weak evidence supporting the association between vitamins and both gingival/periodontal disease and hard dental pathological processes.

Relationship between Clinical Indicators of Periodontal Disease and Serum Level of Vitamin D

Background: Vitamin D is obtained through food and nutritional supplements, or is synthesized in the skin by sunshine. It is then transferred to the liver and kidney through the bloodstream and hydroxylated by a specific enzyme (cytochrome P450 family 27 subfamilies A member 1, cytochrome P450 family 27 subfamily B member 1) to form 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D. The vitamin D synthesis facilitates calcium and phosphorus absorption from the intestines. The parathyroid hormone helps to synthesize 1,25-dihydroxy vitamin D to aid calcium absorption. Objectives: Many researchers have investigated the relationship between serum vitamin D levels and periodontal disease. And periodontal disease indicators such as bleeding on probing, pocket depth, clinical attachment level, gingival index, and cementoenamel junction-alveolar cresthave been used to identify the effects of vitamin D on periodontal disease. The effects of vitamin D on bacteria or cytokines have also been investigated. In this review article, vitamin D levels according to the status of periodontal disease were summarized. Data sources: PubMed was searched electronically, and randomized clinical trials, cross-sectional studies, and case-control studies were included in the review. Study appraisal and synthesis methods: Articles that the classification of periodontitis was accurately described, indicators for identifying periodontitis was clearly marked, and the form of vitamin D measured in the study was accurately described were selected. Only highly relevant journals were selected and summarized. Results: Most of the research has found positive associations between the serum 25-hydroxyvitamin D level and periodontal health, and the clinical parameters of periodontal disease were reduced by vitamin D. Limitations: Detailed categorization of the characteristics associated with the 25-hydroxyvitamin D level should be needed in future studies. Conclusions: This review article can be used as a guide by clinicians and as a reference book for patients’ education.

Leptin induces IL-6 and IL-8 expression through leptin receptor Ob-Rb in human dental pulp fibroblasts

OBJECTIVE

Leptin, through binding to its special receptor (Ob-Rb), has potent effects on immunity and inflammation. This study aimed to investigate the expression of leptin receptor Ob-Rb in human dental pulp fibroblasts (HDPFs) and the effects of leptin on the production of proinflammatory cytokines of IL-6 and IL-8 by HDPFs.

METHODS

Ob-Rb expression was determined by quantitative real-time PCR (real-time PCR), Western blot and immunofluorescence analyses in cultured HDPFs. Small interfering RNA (siRNA) was transfected into HDPFs to down-regulate the expression of Ob-Rb. Real-time PCR and enzyme-linked immunosorbent assay (ELISA) were used to determine the proinflammatory cytokines of IL-6 and IL-8 levels in leptin-stimulated HDPFs. The involved signalling pathways that mediate the leptin-stimulated production of proinflammatory cytokines were investigated using Western blot and specific signalling inhibitor analyses.

RESULTS

The expression levels of Ob-Rb mRNA and protein were detected in HDPFs. Leptin could stimulate mRNA and protein expression of IL-6 and IL-8 in HDPFs in a concentration-dependent and time-dependent manner. Transfection with siRNA targeting Ob-Rb resulted in remarkable reduction of IL-6 and IL-8 expressions by HDPFs. In accordance with the enhanced expression of proinflammatory cytokines, leptin stimulation resulted in rapid phosphorylation of STAT3, p38 MAPK, ERK and Akt in HDPFs. Inhibiting JAK2/STAT3, p38 MAPK or PI3K/Akt substantially decreased leptin-induced IL-6 production, whereas blocking ERK and p38 MAPK substantially suppressed IL-8 production from leptin-stimulated HDPFs.

CONCLUSIONS

Leptin may up-regulate IL-6 and IL-8 production through binding with Ob-Rb in HDPFs via the activation of different intracellular signalling pathways.

An Adiponectin Receptor Agonist Reduces Type 2 Diabetic Periodontitis

Periodontitis is twice as prevalent in diabetics as in nondiabetics, and type 2 diabetes (T2D)-associated periodontitis is severe in many cases due to the altered and aberrant functions of bone cells in hyperglycemic conditions. Therefore, developing an effective method to halt the disease process, as well as restore and regenerate lost alveolar bone to reserve the natural teeth in diabetics, is critically important. In the current study, we applied a newly discovered adiponectin receptor agonist AdipoRon (APR) in experimental periodontitis in diabetic animal models and demonstrated the underlying molecular mechanisms. We found that when APR systemically quenched the blood sugar level in diet-induced obesity (DIO) diabetic mice, it reduced osteoclast numbers and alveolar bone loss significantly due to APR's inhibition on osteoclast differentiation shown in our in vitro studies. APR also decreased the production of proinflammatory molecules CC chemokine ligand 2 and interleukin 6 in diseased gingival tissues. On the other hand, APR promoted alveolar bone regeneration through enhancing osteogenic differentiation and decreasing stromal cell-derived factor 1 in the bone marrow that facilitates stem cell migration. Same results were achieved by APR treatment of periodontitis induced in adiponectin (APN) knockout mice, indicating the ability of APR to activate the endogenous APN receptors to exert osteoanabolic effects. In summary, our study supports the notion that APR could be used as an effective multipronged approach to target T2D-associated periodontitis.

Periodontitis May Restrain the Mandibular Bone Healing via Disturbing Osteogenic and Osteoclastic Balance

Periodontitis has been advocated as a systematic chronic low-grade infection burden. However, the relationship between periodontitis and bone defect healing has not been elucidated. One hundred and eight male Wister rats were randomly assigned into three groups: control (healthy) group, periodontitis group, and periodontitis plus human tumor necrosis factor receptorII:IgG Fc fusion protein (rhTNFR:Fc) group. The experimental periodontitis model was established by ligaturing with orthodontic wire and silk suture plus local administration of 20 μl of lipopolysaccharide (LPS). Mandibular bone defects in size of 4 × 2 × 1 mm were created for all the rats and rhTNFR:Fc subcutaneously injected at neck at a dose of 2.5 mg/kg every 3 days for the periodontitis plus rhTNFR:Fc group. The gene and protein expressions of bone-related markers in the healing tissue were monitored and new bone formation was histologically evaluated. Tartrate-resistant acid phosphatase (TRAP) staining was performed to determine the number of osteoclasts. The results showed that the mRNA and protein expressions of osteogenesis-related markers were significantly lower while nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) gene expression was significantly higher in the periodontitis group. The periodontitis group showed decreased new bone formation and increased number of osteoclasts when compared to the control group. However, there was no significant difference between the periodontitis plus rhTNFR:Fc group and the control group. These results demonstrated that periodontitis may restrain the mandibular bone healing via disturbing osteogenic and osteoclastic balance in which tumor necrosis factor-α (TNF-α) could act as a leverage.

The Relationship between Vitamin D and Periodontal Pathology

Osteoporosis and periodontal diseases are common problems among the elderly population. Vitamin D is a secosteroid hormone that is either synthesized by human skin cells under the effect of UV radiation or consumed through diet. Deficiency in vitamin D leads to reduced bone mineral density, osteoporosis, the progression of periodontal diseases and causes resorption to occur in the jawbone. Sufficient intake of vitamin D can decrease the risk of gingivitis and chronic periodontitis, as it has been shown to have immunomodulatory, anti-inflammatory, antiproliferative effects and initiates cell apoptosis. In addition, vitamin D is also important for bone metabolism, alveolar bone resorption and preventing tooth loss. It increases antibacterial defense of gingival epithelial cells and decrease gingival inflammation, improves postoperative wound healing after periodontal surgery and is an important supplement used as prophylaxis in periodontology. This publication aims to update the recent advances, stress the clinical importance, and evaluate vitamin D in the prevention of periodontal diseases to reach a successful outcome of conservative and surgical treatment. An analysis of the literature shows that vitamin D plays a significant role in maintaining healthy periodontal and jaw bone tissues, alleviating inflammation processes, stimulating post-operative healing of periodontal tissues and the recovery of clinical parameters. However, further research is needed to clarify the required vitamin D concentration in plasma before starting periodontal treatment to achieve the best outcome.

Serum vitamin D levels and chronic periodontitis in adult, Caucasian population-a systematic review

The aim of this systematic review was to explore the relationship between serum vitamin D levels and periodontal disease. The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The focused PICO question was: Are serum vitamin D levels (I) associated with gingivitis or periodontitis (C) in healthy humans (P)? PubMed (Medline), Embase, Science Direct, the Cochrane library, and grey literature were searched up to 31 July 2017. Two reviewers independently selected studies and extracted data. Quality, risk of bias, and heterogeneity of the studies were assessed using the Newcastle-Ottawa Scale. In total, 365 studies were identified and 24 were analyzed. Seven studies fulfilled the inclusion criteria. Four case-control studies showed an influence of vitamin D and its metabolites on periodontal health status/disease. One interventional study suggested the proposed anti-inflammatory role of vitamin D. Two cross-sectional studies failed to show a relationship between vitamin D and periodontal condition. The literature on the effect of serum vitamin D levels on periodontal status remains scarce and controversial. Some data, however, support a "perio-protective" role for vitamin D. There is a need for well-designed randomized clinical trials to explore the possible anti-inflammatory effect of vitamin D on periodontal health.

Influence of obesity on the outcome of non-surgical periodontal therapy - a systematic review

BACKGROUND

Obesity and periodontitis are important chronic health problems. Obesity is associated with an increased prevalence of periodontitis. Whether obesity also affects the outcome of non-surgical periodontal therapy is to date still unclear.

METHODS

A systematic review of studies referenced in SCOPUS, MEDLINE, PubMed, Cochrane, CINAHL, Biosis and Web of Science was performed. Titles, abstracts and finally full texts were scrutinized for possible inclusion by two independent investigators. Quality and heterogeneity of the studies were assessed and the study designs were examined. Probing pocket depth reduction was analyzed as primary surrogate parameter for therapeutic success after non-surgical periodontal therapy.

RESULTS

One-hundred-and-fifty-nine potentially qualifying studies were screened. Eight studies fulfilled the inclusion criteria and were analyzed. Three of eight studies failed to show an influence of obesity on pocket depth reduction after non-surgical therapy. The remaining five studies documented a clear negative effect on the outcome of non-surgical periodontal therapy. The finally included studies did not correspond to the highest level of quality (RCTs). Due to the heterogeneity of the data a meta-analysis was not possible.

CONCLUSION

The literature on the effect of obesity on the treatment outcome of non-surgical periodontal therapy remains controversial. The data, however, support that obesity is not only a factor associated with poorer periodontal health but might also result in inferior response to non-surgical treatment of periodontitis.

Systemic Biomarkers in 2-Phase Antibiotic Periodontal Treatment: A Randomized Clinical Trial

Accumulating evidence suggests that periodontal infections may have an impact on systemic health. In patients with untreated periodontitis, very high values for several inflammatory markers in serum are expressed simultaneously. We investigated to what extent these peak values change after nonsurgical and surgical periodontal treatment, with adjunctive antibiotics administered during the first or the second treatment phase. In a single-center, randomized, placebo-controlled, and double-masked clinical trial, 80 patients with chronic or aggressive periodontitis were randomized into 2 treatment groups: group A, receiving systemic amoxicillin and metronidazole during the first, nonsurgical phase of periodontal therapy (phase 1), and group B, receiving the antibiotics during the second, surgical phase (phase 2). Serum samples were obtained at baseline (BL), 3 mo after phase 1 (M3), and 6 and 12 mo after phase 2 (M6, M12). Samples were evaluated for 15 cytokines and 9 acute-phase proteins using the Bio-Plex bead array multianalyte detection system. For each analyte, peak values were defined as greater than mean +2 SD of measurements found in 40 periodontally healthy persons. Sixty-six patients showed a peak value of at least 1 analyte at BL. At M12, the number of these patients was only 36 (P = 0.0002). This decrease was stronger in group A (BL: 35, M12: 19, P = 0.0009) than in group B (BL: 31, M12: 17, P = 0.14). Twenty patients displayed peak values of at least 4 biomarkers at BL. The nonsurgical therapy delivered in the first phase reduced most of these peaks (group A, BL: 9, M3: 4, P = 0.17; group B, BL: 11, M3: 2, P = 0.01), irrespective of adjunctive antibiotics. The reductions obtained at M3 were maintained until M12 in both groups. Initial, nonsurgical periodontal therapy reduced the incidence of peak levels of inflammatory markers. Antibiotics and further surgical therapy did not enhance the effect (Clinicaltrials.gov NCT02197260).

Patient-Specific Variations in Biomarkers across Gingivitis and Periodontitis

This study investigates the use of saliva, as an emerging diagnostic fluid in conjunction with classification techniques to discern biological heterogeneity in clinically labelled gingivitis and periodontitis subjects (80 subjects; 40/group) A battery of classification techniques were investigated as traditional single classifier systems as well as within a novel selective voting ensemble classification approach (SVA) framework. Unlike traditional single classifiers, SVA is shown to reveal patient-specific variations within disease groups, which may be important for identifying proclivity to disease progression or disease stability. Salivary expression profiles of IL-1ß, IL-6, MMP-8, and MIP-1α from 80 patients were analyzed using four classification algorithms (LDA: Linear Discriminant Analysis [LDA], Quadratic Discriminant Analysis [QDA], Naïve Bayes Classifier [NBC] and Support Vector Machines [SVM]) as traditional single classifiers and within the SVA framework (SVA-LDA, SVA-QDA, SVA-NB and SVA-SVM). Our findings demonstrate that performance measures (sensitivity, specificity and accuracy) of traditional classification as single classifier were comparable to that of the SVA counterparts using clinical labels of the samples as ground truth. However, unlike traditional single classifier approaches, the normalized ensemble vote-counts from SVA revealed varying proclivity of the subjects for each of the disease groups. More importantly, the SVA identified a subset of gingivitis and periodontitis samples that demonstrated a biological proclivity commensurate with the other clinical group. This subset was confirmed across SVA-LDA, SVA-QDA, SVA-NB and SVA-SVM. Heatmap visualization of their ensemble sets revealed lack of consensus between these subsets and the rest of the samples within the respective disease groups indicating the unique nature of the patients in these subsets. While the source of variation is not known, the results presented clearly elucidate the need for novel approaches that accommodate inherent heterogeneity and personalized variations within disease groups in diagnostic characterization. The proposed approach falls within the scope of P4 medicine (predictive, preventive, personalized, and participatory) with the ability to identify unique patient profiles that may predict specific disease trajectories and targeted disease management.

Adiponectin, leptin and TNF-α serum levels in obese and normal weight Peruvian adults with and without chronic periodontitis

BACKGROUND

TNF-α, an adipokine involved in systemic inflammation and a member of a group of cytokines that stimulate the acute phase reaction, has been related to the pathogenesis of both periodontitis and obesity. The objective of this study was to assess the serum levels of adiponectin, leptin and TNF-α of periodontally healthy normal weight (NW) patients, NW patients with chronic periodontitis (CP), periodontally healthy obese patients and obese patients with CP.

MATERIAL AND METHODS

Ninety-three patients were enrolled in this cross-sectional study: 30 periodontally healthy NW patients; 18 NW patients with CP; 21 periodontally healthy obese patients; and 24 obese patients with CP. Analyses included clinical and anthropometric outcomes, as well as the assessment of serum levels of adiponectin, leptin and TNF-α by enzyme linked immunosorbent assay (ELISA) or fully automated chemiluminescence immunoassay. One-Way ANOVA, Kruskal-Wallis One-Way on Ranks, Dunn's Test and multivariable logistic regression (MLR) analyses were conducted to estimate the degree of association between periodontitis and obesity.

RESULTS

Obese patients with CP showed significant more bleeding sites than the other three groups (p<0.05). Moreover, patients from the NWCP and OPH showed similar BOP percentages, as well as OPH group showed more bleeding sites than the NWPH group (p<0.05). The OPH group showed similar levels of adiponectin and leptin than the OCP group, but significantly higher than the NWPH and NWCP groups(p<0.05). MLR analyses showed that obesity was positively associated with the percentage of sites with bleeding on probing, with an odds ratio of 0.93 (95% confidence interval: -0.88, - 0.98; p=0.012).

CONCLUSIONS

The serum levels of adiponectin, leptin and TNF-α were not influenced by CP. Obese patients showed almost 10% more sites with BoP. In chronic periodontitis patients, obese subjects presented significant more BOP sites than normal weight subjects. Key words:Periodontitis, obesity, inflammation, adiponectin, leptin.

Local and serum levels of adipokines in patients with obesity after periodontal therapy: one-year follow-up

AIM

This study evaluated the effects of scaling and root planing (SRP) on gingival crevicular fluid (GCF) and serum levels of adipokines in patients with chronic periodontitis (CP) with or without obesity.

METHODS

Twenty patients with obesity and 20 patients without obesity, all with CP, received SRP. Serum and GCF levels of resistin, adiponectin, leptin, tumour necrosis factor [TNF]-α and interleukin [IL]-6 were evaluated by enzyme-linked immunosorbent assay at baseline, 3, 6 and 12 months post-therapy.

RESULTS

SRP reduced the amounts of TNF-α in deep sites and increased the concentration of adiponectin in shallow sites of non-obese patients (p < 0.05). SRP increased the concentrations of TNF-α and leptin in patients with obesity (p < 0.05). GCF levels of TNF-α were higher in patients with obesity than in patients without obesity at all time-points (p < 0.05). There were no changes in serum levels of any adipokines for any group after therapy (p > 0.05). Patients with obesity exhibited higher serum levels of leptin at all time-points and IL-6 at 3 months post-therapy (p < 0.05).

CONCLUSIONS

Obesity may modulate systemic and periodontal levels of adipokines in favour of pro-inflammation, independently of periodontal therapy. SRP did not affect the circulating levels of adipokines in patients with or without obesity.

Serum omentin, resistin and tumour necrosis factor-α levels in Behcet patients with and without ocular involvement

PURPOSE

The objective of this study was to evaluate serum omentin, resistin and tumour necrosis factor-α (TNF-α) levels in Behcet disease (BD) patients with and without ocular involvement, as well as control subjects.

METHODS

Omentin, resistin and TNF-α levels were assessed in the plasma of 51 BD patients and compared with those of 24 control subjects.

RESULTS

The plasma resistin and TNF-α levels were significantly higher in the BD patients than in the control group (p = 0.028 and p = 0.011, respectively), whereas the plasma omentin level was significantly lower in BD patients than in the control group (p = 0.035). In the ocular BD, non-ocular BD and control groups, the omentin levels were 8.9 ± 4.65, 8.6 ± 3.61, and 12.4 ± 6.24 ng/mL; resistin levels were 0.29 ± 0.21, 0.24 ± 0.2 and 0.15 ± 0.45 ng/mL; and TNF-α levels were 25.45 ± 3.65, 24.03 ± 2.49 and 21.93 ± 4.86 ng/mL, respectively. Omentin/resistin and TNF-α/omentin ratios were more significant parameters in the demonstration of the differences in the groups; the former was lower and the latter was higher in the patient groups (p = 0.001 and p = 0.002, respectively).

CONCLUSIONS

We demonstrated that the plasma omentin level and omentin/resistin ratio were decreased, whereas the resistin and TNF-α levels and TNF-α/omentin ratio were increased in BD patients. These ratios may be used in the presentation of deviation in the inflammatory and anti-inflammatory balance in BD.

Upregulated Leptin in Periodontitis Promotes Inflammatory Cytokine Expression in Periodontal Ligament Cells

BACKGROUND

Imbalance or disruption in the expression of inflammatory mediators contributes greatly to the breakdown of the periodontal supporting tissues. Leptin, through binding to its receptor (obesity-related leptin and leptin receptor [OBR]), has potent effects on immunity and inflammation. However, to date, researchers only indicated a role of leptin in periodontitis. No direct or valid evidence exists about how leptin and its receptor are regulated by local inflammation, what effects they have, and the underlying mechanisms.

METHODS

Experimental periodontitis was induced by ligation of mandibular second molars in beagle dogs. The expression of leptin, OBR, and interleukin (IL)-1β was examined by immunohistochemistry. Meanwhile, recombinant human IL-1β was used to stimulate human periodontal ligament cells (hPDLCs) in vitro, and mRNA and protein levels of leptin were measured using real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Then, mRNA and protein levels of IL-6 and IL-8 were measured using real-time PCR and ELISA, after stimulation with various concentrations of leptin, knocking down all or only the long form of OBR (OBRb) by small interfering RNA and incubation with multiple intracellular signaling pathway inhibitors, respectively.

RESULTS

Leptin and OBR increased substantially in inflammatory periodontal tissues, which correlated well with the extent of inflammatory infiltration, and was a result of the upregulation in resident cells themselves. A high dose of leptin could induce the expression of mRNA and protein of IL-6 and IL-8 in hPDLCs through binding with OBRb and activating different intracellular signaling pathways.

CONCLUSION

Upregulated leptin and OBR in periodontitis stimulated proinflammatory cytokine expression in PDL cells to additionally promote local inflammation.

Therapeutic effects of systemic vitamin k2 and vitamin d3 on gingival inflammation and alveolar bone in rats with experimentally induced periodontitis

BACKGROUND

The synergistic effects of vitamin D3 and vitamin K2 on bone loss prevention have been reported. This study evaluates the effects of vitamin D3 and vitamin K2 supplementation in conjunction with conventional periodontal therapy (scaling and root planing [SRP]) on gingival interleukin (IL)-1β and IL-10, serum bone alkaline phosphatase (B-ALP) and tartrate-resistant acid phosphatase 5b (TRAP-5b), and calcium and alveolar bone levels in rats with experimentally induced periodontitis.

METHODS

Seventy-two rats were divided into the following groups: 1) healthy; 2) periodontitis; 3) SRP; 4) SRP + vitamin D3; 5) SRP + vitamin K2; and 6) SRP + vitamins K2 and D3. Periodontitis was induced by ligature placement for 7 days, and vitamin K2 (30 mg/kg) and/or vitamin D3 (2 μg/kg) were administered for 10 days in the SRP + vitamin D3, SRP + vitamin K2, and SRP + vitamins K2 and D3 groups by oral gavage. On day 18, the animals were sacrificed, serum B-ALP, TRAP-5b, and calcium levels were measured, gingiva specimens were extracted for IL-1β and IL-10 analysis, and distances between the cemento-enamel junction and alveolar bone crest were evaluated.

RESULTS

Alveolar bone levels in the periodontitis group were significantly greater than those in the other five groups. No significant differences were found in gingival IL-1β and IL-10, serum B-ALP and TRAP-5b, and calcium and alveolar bone levels between the groups receiving SRP and vitamins and the group receiving SRP alone.

CONCLUSION

Within the limitations of this study, vitamin D3 and K2 alone or in combination did not affect gingival IL-1β and IL-10, serum B-ALP and TRAP-5b levels, or alveolar bone compared with conventional periodontal therapy alone.

Effect of periodontal treatment on adipokines in type 2 diabetes

The association between adipokines and inflammatory periodontal diseases has been studied over the last two decades. This review was intended to explore the observation that periodontal therapy may lead to an improvement of adipokines in diabetic patients. In summary, substantial evidence suggests that diabetes is associated with increased prevalence, extent and severity of periodontitis. Numerous mechanisms have been elucidated to explain the impact of diabetes on the periodontium. However, current knowledge concerning the role of major adipokines indicates only some of their associations with the pathogenesis of periodontitis in type 2 diabetes. Conversely, treatment of periodontal disease and reduction of oral inflammation may have positive effects on the diabetic condition, although evidence for this remains somewhat equivocal.

Lessons learned and unlearned in periodontal microbiology

Periodontal diseases are initiated by bacterial species living in polymicrobial biofilms at or below the gingival margin and progress largely as a result of the inflammation elicited by specific subgingival species. In the past few decades, efforts to understand the periodontal microbiota have led to an exponential increase in information about biofilms associated with periodontal health and disease. In fact, the oral microbiota is one of the best-characterized microbiomes that colonize the human body. Despite this increased knowledge, one has to ask if our fundamental concepts of the etiology and pathogenesis of periodontal diseases have really changed. In this article we will review how our comprehension of the structure and function of the subgingival microbiota has evolved over the years in search of lessons learned and unlearned in periodontal microbiology. More specifically, this review focuses on: (i) how the data obtained through molecular techniques have impacted our knowledge of the etiology of periodontal infections; (ii) the potential role of viruses in the etiopathogenesis of periodontal diseases; (iii) how concepts of microbial ecology have expanded our understanding of host-microbe interactions that might lead to periodontal diseases; (iv) the role of inflammation in the pathogenesis of periodontal diseases; and (v) the impact of these evolving concepts on therapeutic and preventive strategies to periodontal infections. We will conclude by reviewing how novel systems-biology approaches promise to unravel new details of the pathogenesis of periodontal diseases and hopefully lead to a better understanding of their mechanisms.

T helper cells from aggressive periodontitis patients produce higher levels of interleukin-1 beta and interleukin-6 in interaction with Porphyromonas gingivalis

OBJECTIVE

In this study, we analyzed the production of Interleukin-1 beta (IL-1β) and IL-6 by activated CD4+ cells obtained from aggressive periodontitis (AgP) patients in comparison with healthy subjects (HC).

MATERIALS AND METHODS

CD4+ cells were automatically separated from lymphocytes obtained from peripheral blood of patients with AgP and healthy controls. Cells were activated for 4, 8, and 24 h with three different stimuli: anti-CD3/anti-CD28, phytohemagglutinin (PHA), and Porphyromonas gingivalis (P. gingivalis) outer membrane protein (OMP). Protein levels were measured in supernatants of activated CD4+ cells by a bead-based immunoassay (CBA). In addition, serum antibodies against P. gingivalis were determined. Data were analyzed using U test (p < 0.05).

RESULTS

T helper cells of AgP patients activated with P. gingivalis OMP produced higher levels of IL-1β and IL-6 in comparison with healthy controls (p < 0.05). Neither the activation with anti-CD3/anti-CD28 nor the activation with PHA showed significantly different production of IL-1β and IL-6 by the cells 25 % of patients and 17 % of controls presented with high serum reactivity to P. gingivalis.

CONCLUSION

In view of these results, it is possible to conclude that P. gingivalis contributes to the pathogenesis of AgP by inducing high levels of pro-inflammatory cytokines such as IL-1β and IL-6 by peripheral CD4+ T helper cells.

CLINICAL RELEVANCE

In accordance with the clinical parameters and the immunological data, we suggest that full-mouth disinfection with adjunctive systemic antibiotics might be the anti-infectious non-surgical periodontal treatment of choice in this type of patients. Microbiological analyses at the beginning and at the end of the periodontal treatment are recommended. However, it is necessary to verify these data in longitudinal clinical studies.

Investigating the causal effect of vitamin D on serum adiponectin using a Mendelian randomization approach

BACKGROUND/OBJECTIVES

The aim was to examine the causal effect of vitamin D on serum adiponectin using a multiple instrument Mendelian randomization approach.

SUBJECTS/METHODS

Serum 25-hydroxy vitamin D (25(OH)D) and serum total or high molecular weight (HMW) adiponectin were measured in two Danish population-based studies: the Inter99 study (6405 adults, 30-60 years) conducted in 1999-2001, and the MONICA10 study (2656 adults, 41-71 years) conducted in 1993-1994.

RESULTS

In the Inter99 study, serum 25(OH)D was positively associated with total adiponectin (the effect estimate in % per doubling of 25(OH)D was 4.78, 95% CI: 1.96, 7.68, P<0.001). Using variations in the vitamin D-binding protein gene and the filaggrin gene as instrumental variables, the causal effect in % was estimated to 61.46, 95% CI: 17.51, 120.28, P=0.003 higher adiponectin per doubling of 25(OH)D. In the MONICA10 cohort, no significant association was observed between the serum concentrations of 25(OH)D and HMW adiponectin (the effect estimate in % per doubling of 25(OH)D was -1.51, 95% CI: -5.80, 2.98, P=0.50), although the instrumental variables analysis to some extent supported a positive causal association (the effect estimate in % per doubling of 25(OH)D was 37.13, 95% CI: -3.67, 95.20, P=0.080).

CONCLUSIONS

The results indicate a possible causal association between serum 25(OH)D and total adiponectin. However, the association was not replicated for HMW adiponectin. Thus, further studies are needed to confirm a causal relationship.