Changes in Gingival Crevicular Fluid Interleukin-4 and Interferon-gamma in Patients with Chronic Periodontitis Before and After Periodontal Initial Therapy

Influence of root debridement with adjunct photodynamic therapy on periodontal parameters and gingival crevicular fluid cortisol levels among patients with and without type-2 diabetes mellitus

OBJECTIVE

The aim of the present study was to assess the influence of scaling and root planing (SRP) with adjunct antimicrobial photodynamic therapy (aPDT) on periodontal parameters and gingival crevicular fluid (GCF) cortisol levels in type-2 diabetic and non-diabetic patients with periodontitis.

METHODS

One hundred and twenty-eight patients with periodontitis (64 with and 64 without type-2 diabetes mellitus, respectively) were included. In the test- and control-groups, patients underwent SRP with and without aPDT, respectivey. In both groups, plaque and gingival indices (PI and GI), probing depth (PD), clinical attachment loss (CAL), marginal bone loss (MBL) and GCF volume and cortisol levels were assessed at baseline and three and six-months after SRP with or without aPDT. The aPDT was performed at baseline using methylene blue and photobiomodulation. The Kruskall-Wallis test was used to assess data normality; and group-comparisons were done. P-values, which were below 0.01 indicated statistical significance.

RESULTS

Sixty-four type-2 diabetic patients with and 64 non-diabetic patients with periodontitis were included. All individuals had Stage-III/Grade-C periodontitis. Among patients with type-2 diabetes mellitus (DM), there was no statistically significant difference in hemoblobin A1c, PI, GI, PD, CAL and MBL at baseline and at 3- and 6-months intervals. Amongst diabetic patietns, there was no difference in the GCF volume and cortisol levels in the test- and control-groups at all time intervals. In non-diabetic patients, there was a significqnt reductionin GCF volume and cortisol levels when SRP was done with aPDT than when SRP was carried out as the sole treatment strategy CONCLUSION: Among non-diabetic patients, SRP with aPDT helps reduce periodontal inflammation and GCF cortisol levels for up to 6-months; however poorly-controlled DM compromises the beneficial effects of this treatment strategy.

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.

Transcriptional activity of vitamin D receptor in human periodontal ligament cells is diminished under inflammatory conditions

Background

Although vitamin D₃ deficiency is considered as a risk factor for periodontitis, supplementation during periodontal treatment has not been shown to be beneficial to date. Human periodontal ligament cells (hPDLCs) are regulated by vitamin D₃ and play a fundamental role in periodontal tissue homeostasis and inflammatory response in periodontitis. The aim of this study is to investigate possible alterations of the vitamin D₃ activity in hPDLCs under inflammatory conditions.

Methods

Cells isolated from six different donors were treated with either 1,25(OH)₂D₃ (0 to 10 nM) or 25(OH)D₃ (0 to 100 nM) in the presence and absence of ultrapure or standard Porphyromonas gingivalis lipopolysaccharide (PgLPS), Pam3CSK4, or interferon‐γ for 48 hours. Additionally, nuclear factor (NF)‐κB inhibition was performed with BAY 11‐7082. The bioactivity of vitamin D in hPDLCs was assessed based on the gene expression levels of vitamin D receptor (VDR)‐regulated genes osteocalcin and osteopontin. Additionally, VDR and CYP27B1 expression levels were measured.

Results

The vitamin D₃‐induced increase of osteocalcin and osteopontin expression was significantly decreased in the presence of standard PgLPS and Pam3CSK4, which was not observed by ultrapure PgLPS. Interferon‐y had diverse effects on the response of hPDLCs to vitamin D₃ metabolites. NF‐kB inhibition abolished the effects of standard PgLPS and Pam3CSK4. Standard PgLPS and Pam3CSK4 increased VDR expression in the presence of vitamin D₃. CYP27B1 expression was not affected by vitamin D₃ and inflammatory conditions.

Conclusions

This study indicates that the transcriptional activity of VDR is diminished under inflammatory conditions, which might mitigate the effectiveness of vitamin D₃ supplementation during periodontal treatment.

Effect of scaling and root planing on the expression of anti-inflammatory cytokines (IL-4, IL-9, IL-10, and IL-13) in the gingival crevicular fluid of electronic cigarette users and non-smokers with moderate chronic periodontitis

Purpose

The aim of this cross-sectional study was to investigate the effect of scaling and root planing (SRP) on the expression of anti-inflammatory cytokines (interleukin [IL]-4, IL-9, IL-10, and IL-13) in the gingival crevicular fluid (GCF) of electronic cigarette users and non-smokers with moderate chronic periodontitis (CP).

Methods

Electronic cigarette users and non-smokers with CP were included in the study. Full-mouth plaque and gingival indices, probing depth (PD), clinical attachment loss (CAL), and marginal bone loss (MBL) were assessed. The GCF was collected, and its volume and levels of IL-4, IL-9, IL-10, and IL-13 were assessed. These parameters were evaluated at baseline and 3 months after SRP. The sample size was estimated, and comparisons between groups were performed. P<0.05 was considered to indicate statistical significance.

Results

Thirty-six electronic cigarette users (47.7±5.8 years old) and 35 non-smokers (46.5±3.4 years old) with CP were included. At baseline, there were no differences in plaque index (PI), PD, CAL, MBL, and GCF IL-4, IL-9, IL-10, and IL-13 between electronic cigarette users and non-smokers. At the 3-month follow-up, there were no significant differences in PI, gingival index (GI), PD, CAL, and MBL in electronic cigarette users compared to baseline, while there were significant reductions in PI, GI, and PD among non-smokers. At the 3-month follow-up, GCF IL-4, IL-9, IL-10, and IL-13 levels were significantly elevated in both groups (P<0.05) compared to baseline. The increases in GCF IL-4, IL-9, IL-10, and IL-13 levels were significantly higher in non-smokers (P<0.05) than in electronic cigarette users at the 3-month follow-up.

Conclusions

Levels of GCF IL-4, IL-9, IL-10, and IL-13 increased after SRP in electronic cigarette users and non-smokers with CP; however, the anti-inflammatory effect of SRP was more profound in non-smokers than in electronic cigarette users.

Levels of Pro and Anti-inflammatory Citokynes and C-Reactive Protein in Patients with Chronic Periodontitis Submitted to Nonsurgical Periodontal Treatment

Aim

to compare the levels of IFN-γ, TGF-β and C-reactive protein (CRP) in healthy patients (HP) and chronic periodontitis patients (CP) before and seven days after the last session of Non-Surgical Periodontal Treatment (NSPT).

Materials and Methods

40 subjects were divided into two groups: healthy (n= 20), and with chronic periodontitis (n = 20). Serum and gingival crevicular fluid (GCF) were collected from each patient and quantified for IFN-γ, TGF-β and CRP using the enzyme-linked immunosorbent assay (ELISA).

Results

IFN-γ was found to be higher in the GCF of the CP group before NSPT in relation to the HP group (p<0.05), and it had significant higher levels after seven days of NSPT (p<0.05). The levels of TGF-β in the GCF of CP patients before NSPT were significantly higher when compared to HP (p<0.05), but they decreased after seven days of NSPT (p>0.05). Serum CRP levels did not show statistical difference between CP and HP before or after NSPT.

Conclusion

Therefore, our results demonstrated for the first time that NSPT causes early exacerbation of the immune response at the local level represented by increased levels of IFN-γ and decreased levels of TGF-β in the gingival crevicular fluid after seven days of treatment.

Comparative Evaluation of Cytokines in Gingival Crevicular Fluid and Saliva of Patients with Aggressive Periodontitis

Objectives

This study aims to evaluate and compare cytokines in gingival crevicular fluid (GCF) and saliva of patients with aggressive periodontitis (AP) before and after treatment.

Methods

Forty AP patients and 40 healthy volunteers were enrolled in this study. Clinical parameters included probing depth and sulcus bleeding index. GCF and saliva were collected from both groups. The levels of IL-1β, IL-2, IL-4, IL-6, IFN-γ and TNF-α were measured using ELISA.

Results

The probing depth in AP patients was significantly deeper before treatment than after treatment. The concentrations of cytokines in GCF and saliva were significantly higher in AP patients than in the control group and decreased after periodontal treatment. Positive relationships were found between cytokine levels in GCF and clinical parameters. The reliability of cytokines in GCF and saliva was assessed by Cronbach's alpha analysis, which could be considered satisfactory.

Conclusion

Cytokine levels in GCF and saliva correlated well with clinical parameters and AP. Measurements of cytokines in saliva may be regarded as a noninvasive and quick method for monitoring periodontal disease activity.

Estimation of Plasma Levels of Tumor Necrosis Factor-a, Interleukin-4 and 6 in Patients with Chronic Periodontitis and Type II Diabetes Mellitus

INTRODUCTION

Both periodontitis and type II diabetes mellitus (T2DM) are common diseases with a multifactorial etiology and have influence of cytokines in their pathogenesis and thus may also influence each other. In recent times, more attention has been given to understanding the influences of these inflammatory cytokines which are a main part of oral chronic inflammation on systemic health of the individuals. Therefore, the aim of this study was to evaluate the plasma cytokine levels, specifically tumor necrosis factor-a (TNF-a), interleukin (IL)-6, and IL-4, in chronic periodontitis patients and T2DM patients, so as to investigate the influence of chronic periodontitis in systemic inflammation associated with diabetes mellitus.

MATERIALS AND METHODS

The present study comprised a total sample size of 60 patients. A detailed history along with complete periodontal examination were done for each person. These patients were subdivided into four study groups with 15 subjects (n = 15) in each group: group I: healthy individuals, group II: chronic periodontitis, group III: diabetes mellitus without chronic periodontitis, and group IV: diabetes mellitus with chronic periodontitis. Venous blood was withdrawn for obtaining serum samples from the subjects. Hemoglobin A1c (HbAlc) levels were measured from the automated chromatography. Using enzyme-linked immunosorbent assay kit, TNF-a, IL-4, and IL-6 were measured.

RESULTS

It was observed that the difference between almost all the results showed statistical significance. Not much of a difference was seen when TNF-a and IL-6 findings of group II were compared with group III. Furthermore, IL-4 also did not differ when group II was compared with group IV.

CONCLUSION

The inflammatory cytokines together control the inflammation process and a balance is maintained. However, in patients with diabetes mellitus, this balance is interrupted, which affects the final development and progression of the disease. Thus, hyperglycemia may be partly associated with the severity of the periodontal status in diabetic patients.

CLINICAL SIGNIFICANCE

Hyperglycemia thus may play a role in increasing the severity of the periodontal status in diabetic patients. Keeping such relationship in mind, better treatment modalities can be provided to the patients.

Ability of salivary biomarkers in the prognostic of systemic and buccal inflammation

Nowadays, there is a growing interest in using saliva as an alternative sample for the diagnosis, prediction and progression of several diseases. It has been established that some molecules found in saliva are related to oral inflammatory processes and systemic health status. Furthermore, it is known that saliva is crucial for the carrying out of different functions in the oral cavity and its role in the local modulation of inflammatory and immune response is being thoroughly studied by the health research community. The aim of this review is to analyze the most important biomarkers which have been utilized in biomedicine during the last two decades in order to establish a correlation between certain specific salivary biomarkers and systemic inflammation. Then, we discuss the utility of total proteins, immunoglobulin A and alpha-amylase as biomarkers for the prognostic of local inflammation after oral surgery.

Key words:Inflammation, salivary biomarkers, systemic disease, buccal surgery, total proteins, inmunoglobulin A, Alpha-amylase.

Effect of initial periodontal therapy on gingival crevicular fluid cytokine profile in subjects with chronic periodontitis

Cytokines are thought to play an important role in the pathogenesis of periodontal disease. Because periodontal disease is known for its inhomogeneous distribution within the dentition, it is unclear to what extent the detection of various cytokines at different sites correlates with presence of disease. We evaluated whether levels of 12 cytokines in gingival crevicular fluid (GCF) discriminated periodontally diseased sites from healthy ones, or periodontally diseased persons from healthy ones, and assessed the impact of nonsurgical periodontal therapy on these readings. This study included 20 periodontally healthy persons (H) and 24 patients with chronic periodontitis (P). In every participant, we measured the plaque index, gingival index, probing pocket depth (PD), bleeding on probing, and recession at six sites of every tooth. GCF was collected with Durapore^® filter strips from two healthy sites (PD<4 mm; HH) in group H, and from two periodontally diseased sites (PD≥5 mm; PP) and two periodontally healthy sites (PD≤3 mm; PH) in group P. The periodontally diseased participants underwent comprehensive nonsurgical periodontal therapy including deep scaling and root planing under local anesthesia. In these participants, GCF samples were again collected at the same sites 1 and 3 months after therapy. Twelve cytokines (il‐1β, il‐1ra, il‐6, il‐8, il‐17, b‐fgf, g‐csf, gm‐csf, ifn‐γ, mip‐1β, vegf, and tnf‐α) were assessed using the Bio‐Plex suspension array system. Mean plaque index, gingival index, bleeding on probing, PD, and recession were significantly different between groups H and P. Differences between PP and PH sites were not significant for any of the cytokines. Il‐1ra, il‐6, il‐17, b‐fgf, gm‐csf, mip‐1β, and tnf‐α differed significantly between HH sites and both PH and PP sites, whereas il‐8 was significantly higher only at PP sites. Periodontal treatment increased gm‐csf and decreased il‐1ra levels in PP sites. Il‐1ra, il‐6, il‐8, il‐17, b‐fgf, gm‐csf, mip‐1β, and tnf‐α identified patients with chronic periodontitis, rather than diseased sites, suggesting a generalized inflammatory state that is not limited to clinically diseased sites only.

Gingival crevicular fluid levels of cytokines/chemokines in chronic periodontitis: a meta-analysis

AIMS

To compare gingival crevicular fluid (GCF) cytokines/chemokines levels between periodontally healthy subjects and subjects diagnosed with chronic periodontitis (ChP), before and after non-surgical periodontal treatment, and to establish their predictive value for periodontal disease progression.

METHODS

Studies indexed in MEDLINE and EMBASE published in English, Portuguese and Spanish were eligible for this review. Database searches up to December 2015, and manual search of the reference list from reviews and selected articles was performed. Only studies providing data on GCF cytokines/chemokines levels in subjects diagnosed with ChP and periodontally healthy controls were included. Cross-sectional, case series, single-arm clinical studies, randomized controlled trials and prospective/retrospective cohort studies were included. Meta-analyses were conducted for those cytokines/chemokines with at least three available studies.

RESULTS

GCF levels of IL-1β, IL-6, IFN-γ and MCP-1/CCL2 were significantly higher in subjects diagnosed with ChP than periodontally healthy subjects. A significant decrease in GCF levels of IL-1β and IL-17 was observed after non-surgical periodontal treatment, whereas a significant increase was observed for IL-4.

CONCLUSION

Evidence for significant differences between periodontal health and ChP was observed for a few cytokines and one chemokine. No conclusions could be drawn with regards to increased risk of disease progression.

Tumor necrosis factor-α, interleukin-4 and -6 in the serum of health, chronic periodontitis, and type 2 diabetes mellitus

Background

Cytokines are significant in the development and progression of chronic periodontitis (ChP) and type 2 diabetes mellitus (DT2). Insufficient information is available regarding the pro- versus anti-inflammatory cytokines in ChP's influence on systemic levels of cytokines on DT2. This study investigated the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-4 and IL-6 in the serum of patients with ChP, DT2, and with both ChP and DT2, as compared to health.

Materials and Methods

A total of eighty participants were grouped equally groups as healthy (NH), ChP with, and without DT2 (ChP and ChP + DT2) and only type 2 diabetes (DT2). Plaque and gingival indices, bleeding on probing, pocket probing depths, clinical attachment loss, were evaluated. Serum samples were collected to measure glycated hemoglobin, random blood sugar. TNF-α, IL-4 and -6 was assessed by ELISA.

Results

The selected cytokines were detected in all the participants. TNF-α and IL-6 were highest in ChP + DT2 group, whereas IL-4 was highest in health. Significant differences and correlation were observed between the cytokines, periodontal, and glycemic parameters and among the four groups.

Conclusion

TNF-α and IL-6 appear to heighten the inflammatory state in patients with both type 2 diabetes and periodontitis, but IL-4, though considered an anti-inflammatory mediator was not convincing in such a role in this study. The cytokine behavior needs to be studied further in larger studies.

Inflammatory Mediators of Leprosy Reactional Episodes and Dental Infections: A Systematic Review

Reactional episodes in leprosy are a result of complex interactions between the immune system, Mycobacterium leprae, and predisposing factors, including dental infections. To determine the main inflammatory mediators in the immunopathological process of dental infections and leprosy reactions, we conducted a systematic review of primary literature published between 1996 and 2013. A three-stage literature search was performed (Stage I, "leprosy reactions" and "inflammatory mediators"; Stage II, "dental infections" and "inflammatory mediators"; and Stage III, "leprosy reactions," "dental infections," and "inflammatory mediators"). Of the 911 eligible publications, 10 were selected in Stage I, 68 in Stage II, and 1 in Stage III. Of the 27 studied inflammatory mediators, the main proinflammatory mediators were IL-6, IFN-γ, TNF-α, IL-1β, and IL-17; the main anti-inflammatory mediators were IL-10 and IL-4. Serum IL-6 and TNF-α concentrations were significant during periodontal and reactional lesion evolution; IFN-γ and IL-1β were associated with types 1 and 2 reactions and chronic periodontal disease. The proinflammatory mediators in dental infections and leprosy reactions, especially IL-6 and TNF-α, were similar across studies, regardless of the laboratory technique and sample type. IFN-γ and IL-1β were significant for leprosy reactions and periodontal diseases. This pattern was maintained in serum.

Inflammatory mediators in the pathogenesis of periodontitis

Periodontitis is a chronic inflammatory condition of the periodontium involving interactions between bacterial products, numerous cell populations and inflammatory mediators. It is generally accepted that periodontitis is initiated by complex and diverse microbial biofilms which form on the teeth, i.e. dental plaque. Substances released from this biofilm such as lipopolysaccharides, antigens and other virulence factors, gain access to the gingival tissue and initiate an inflammatory and immune response, leading to the activation of host defence cells. As a result of cellular activation, inflammatory mediators, including cytokines, chemokines, arachidonic acid metabolites and proteolytic enzymes collectively contribute to tissue destruction and bone resorption. This review summarises recent studies on the pathogenesis of periodontitis, with the main focus on inflammatory mediators and their role in periodontal disease.

Possible involvement of IL-21 and IL-10 on salivary IgA levels in chronic periodontitis subjects

Specific cytokines and the costimulatory protein CD40 play role in inducing immunoglobulin (Ig)A production by B cells in the humoral immune response. However, to date, the role of these mediators was not investigated in chronic periodontitis. Therefore, the aim of this study was to assess the local levels of interleukin (IL)-21, IL-21 receptor (IL-21R), IL-4, IL-10 and CD40 ligand (CD40L) on chronic periodontitis subjects and their relationship with the salivary levels of IgA. Gingival biopsies and un-stimulated saliva were collected from chronic periodontitis (n = 15) and periodontally healthy (n = 15) subjects. The mRNA levels of IL-4, IL-10, IL-21, IL-21R, CD40L in the gingival biopsies were evaluated by quantitative real-time polymerase chain reaction. The salivary levels of IgA and the levels of IL-4 and IL-10 in the gingival biopsies were analyzed by ELISA. The mean levels of IgA were significantly higher in the chronic periodontitis compared to periodontally healthy group (P < 0.05). The mRNA levels for IL-21 was higher (P < 0.05) in the chronic periodontitis when compared to the healthy group. However, the expression of IL-21R and CD40L did not differ between groups. The IL-10 was significantly elevated at mRNA and protein levels in chronic periodontitis when compared to periodontally healthy group (P < 0.05). Conversely, the mRNA levels as well as the protein amount of IL-4 were significantly lower (P < 0.05) in chronic periodontitis than healthy ones. In conclusion, the upregulation of IL-21 and IL-10 and downregulation of IL-4 in periodontitis tissues may be collectively involved in the increased levels of salivary IgA in chronic periodontitis subjects.

Cytokines and bone-related factors in systemically healthy patients with chronic periodontitis and patients with type 2 diabetes and chronic periodontitis

BACKGROUND

This study compares the levels of cytokines and bone-related factors in the gingival crevicular fluid (GCF) of systemically healthy patients with chronic periodontitis (CP); and better-controlled, and poorly controlled patients with type 2 diabetes and CP.

METHODS

Thirty-seven patients with type 2 diabetes and CP and 20 systemically healthy patients with CP were enrolled in this study. The patients with diabetes mellitus were categorized as better-controlled (n = 17; HbA(1c) levels ≤8%) or poorly controlled (n = 20; glycated hemoglobin values >8%). Levels of tumor necrosis factor-α, interleukin (IL)-4, interferon (IFN)-γ, IL-23, IL-17, soluble receptor activator of nuclear factor-kappa B ligand (sRANKL), and osteoprotegerin (OPG) in GCF of diseased sites were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Type 2 diabetes mellitus, as a whole, upregulates the levels of OPG, sRANKL, IFN-γ, IL-17, and IL-23 and downregulates the production of IL-4 in sites with CP (P <0.05). Better-controlled individuals exhibited the highest levels of IFN-γ, whereas poorly controlled patients presented the highest levels of IL-17 (P <0.05). There were no differences in the levels of tumor necrosis factor-α, OPG, and IL-23 among systemically healthy, better-controlled, and poorly controlled patients with diabetes (P >0.05).

CONCLUSIONS

Increased levels of proinflammatory cytokines and RANKL were observed in the GCF of patients with type 2 diabetes with CP, compared to patients without diabetes. In addition, poor or good glycemic status seems to modulate osteo-immunoinflammatory mediators in a different manner.

Cytokine levels in sites of chronic periodontitis of poorly controlled and well-controlled type 2 diabetic subjects

AIM

This study compared the levels of tumour necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-4, IL-17 and IL-23 in the gingival crevicular fluid (GCF) from well-controlled and poorly controlled type 2 diabetic subjects with chronic periodontitis, before and after periodontal therapy.

MATERIAL AND METHODS

Eighteen well-controlled (glycated haemoglobin levels ≤8%) and 20 poorly controlled (glycated haemoglobin levels >8%) diabetic subjects were enrolled in this study. All subjects were submitted to non-surgical periodontal therapy. GCF sampling and clinical periodontal parameters were assessed before, 3 and 6 months post-therapy. Total amounts and concentrations of TNF-α, IFN-γ, IL-4, IL-17 and IL-23 in the GCF were analysed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The levels of IL-17 were higher in poorly than in well-controlled subjects (p<0.05), whereas the levels of IFN-γ were increased in well- compared with poorly controlled subjects at all experimental groups (p<0.05). In addition, IL-4 levels were lower in well- than poorly controlled diabetic subjects at baseline (p<0.05). There were no differences between groups for TNF-α and IL-23 at any time points (p>0.05).

CONCLUSION

These results indicate a predominance of pro-inflammatory T-helper type 1 (Th1)- or Th17-cytokines in sites of chronic periodontitis from type 2 diabetic subjects, according to their glycaemic control.

A genome-wide association study identifies GLT6D1 as a susceptibility locus for periodontitis

Periodontitis is a widespread, complex inflammatory disease of the mouth, which results in a loss of gingival tissue and alveolar bone, with aggressive periodontitis (AgP) as its most severe form. To identify genetic risk factors for periodontitis, we conducted a genome-wide association study in German AgP patients. We found AgP to be strongly associated with the intronic SNP rs1537415, which is located in the glycosyltransferase gene GLT6D1. We replicated the association in a panel of Dutch generalized and localized AgP patients. In the combined analysis including 1758 subjects, rs1537415 reached a genome-wide significance level of P= 5.51 x 10(-9), OR = 1.59 (95% CI 1.36-1.86). The associated rare G allele of rs1537415 showed an enrichment of 10% in periodontitis cases (48.4% in comparison with 38.8% in controls). Fine-mapping and a haplotype analysis indicated that rs1537415 showed the strongest association signal. Sequencing identified no further associated variant. Tissue-specific expression analysis of GLT6D1 indicated high transcript levels in the leukocytes, the gingiva and testis. Analysis of potential transcription factor binding sites at this locus predicted a significant reduction of GATA-3 binding affinity, and an electrophoretic mobility assay indicated a T cell specific reduction of protein binding for the G allele. Overexpression of GATA-3 in HEK293 cells resulted in allele-specific binding of GATA-3, indicating the identity of GATA-3 as the binding protein. The identified association of GLT6D1 with AgP implicates this locus as an important susceptibility factor, and GATA-3 as a potential signaling component in the pathophysiology of periodontitis.

Involvement of Toll-like receptors 2 and 4 in the innate immune response to Treponema denticola and its outer sheath components

Treponema denticola is considered an important oral pathogen in the development and progression of periodontal diseases. In the present study, the mechanisms of recognition and activation of murine macrophages by T. denticola and its major outer sheath protein (MSP) and lipooligosaccharide (LOS or glycolipid) were investigated. T. denticola cells and the MSP induced innate immune responses through TLR2-MyD88, whereas LOS induced a macrophage response through TLR4-MyD88. The presence of gamma interferon (IFN-gamma), or of high numbers of T. denticola, circumvented the requirement for TLR2 for the macrophage response to T. denticola, although the response was still dependent on MyD88. In contrast, synergy with IFN-gamma did not alter the TLR dependence of the response to the T. denticola surface components LOS and MSP, despite enhanced sensitivity. These data suggest that although there is flexibility in the requirements for recognition of T. denticola cells (TLR2 dependent or independent), MyD88 is a requirement for the downstream signaling events that lead to inflammation. We also demonstrate that both outer sheath molecules LOS and MSP induce macrophage tolerance to further stimulation with enterobacterial lipopolysaccharide. Tolerance induced by T. denticola components during mixed infections may represent a general mechanism through which bacteria evade clearance.