Interleukin-6 expression and gene polymorphism are associated with severity of periodontal disease in a sample of Brazilian individuals

Periodontal disease as a model to study chronic inflammation in aging

Periodontal disease is a chronic inflammatory condition that results in the destruction of the teeth supporting tissues, eventually leading to the loss of teeth and reduced quality of life. In severe cases, periodontal disease can limit proper nutritional intake, cause acute pain and infection, and cause a withdrawal from social situations due to esthetic and phonetic concerns. Similar to other chronic inflammatory conditions, periodontal disease increases in prevalence with age. Research into what drives periodontal disease pathogenesis in older adults is contributing to our general understanding of age-related chronic inflammation. This review will present periodontal disease as an age-related chronic inflammatory disease and as an effective geroscience model to study mechanisms of age-related inflammatory dysregulation. The current understanding of the cellular and molecular mechanisms that drive inflammatory dysregulation as a function of age will be discussed with a focus on the major pathogenic immune cells in periodontal disease, which include neutrophils, macrophages, and T cells. Research in the aging biology field has shown that the age-related changes in these immune cells result in the cells becoming less effective in the clearance of microbial pathogens, expansion of pathogenic subpopulations, or an increase in pro-inflammatory cytokine secretions. Such changes can be pathogenic and contribute to inflammatory dysregulation that is associated with a myriad of age-related disease including periodontal disease. An improved understanding is needed to develop better interventions that target the molecules or pathways that are perturbed with age in order to improve treatment of chronic inflammatory conditions, including periodontal disease, in older adult populations.

Effects of Periodontal Treatment on Levels of Proinflammatory Cytokines in Patients with Chronic Periodontitis: A Meta-Analysis

Background

During the progression of chronic periodontitis (CP), changes in the levels of inflammatory factors are detected in serum and gingival sulcus fluid (GCF). The aim of this meta-analysis was to systematically evaluate the effect of periodontal treatment on GCF and serum proinflammatory cytokines (IL-6, TNF-α, and IL-8) in patients with CP.

Methods

Literature searches were performed through PubMed, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), and Wanfang Database. Randomized controlled trials comparing cytokine levels in periodontal treatment (experimental group) and control group between 2015 and 2020 were included.

Results

There were a total of 13 studies included with 1220 patients. There were 630 cases in the experimental group and 590 cases in the control group. The meta-analysis showed that IL-6 levels in the GCF (SMD = −2.88, 95% CI (-3.68, -2.09), P < 0.001) and serum (SMD = −1.27, 95% CI (-1.72, -0.81), P < 0.001) were significantly lower in the experimental group compared with those before treatment. In addition, IL-8 levels in the GCF (SMD = −2.08, 95% CI (-3.40, -0.76), P < 0.001) and serum (SMD = −1.73, 95% CI (-2.76, -0.70), P < 0.001) were decreased after periodontal treatment, but more than that, a decrease was observed in TNF-α levels of GCF (SMD = −3.98, 95% CI (-5.23, -2.73), P < 0.001) and serum (SMD = −1.80, 95% CI (-3.16, -0.45), P < 0.001) after treatment.

Conclusion

After periodontal therapy, the proinflammatory cytokines in the GCF and serum of patients with CP were significantly decreased compared with those before treatment, and the efficacy was remarkable.

Radiation therapy for head and neck cancer leads to gingival recession associated with dental caries

OBJECTIVE

The aim of this study was to examine effects of radiation therapy (RT) for head and neck cancer (HNC) on periodontal disease and relationships to caries.

STUDY DESIGN

A multicenter prospective observational cohort study (OraRad) was conducted in patients undergoing RT for HNC. Assessments were conducted by calibrated examiners at the pre-RT (baseline) visit (n = 533), the 12-month visit (n = 414), and the 24-month visit (n = 365).

RESULTS

The average whole mouth mean (standard error (SE)) distance from the cementoenamel junction to the gingival margin (CEJ-GM) decreased significantly from 0.43 (0.04) mm at baseline to 0.24 (0.04) mm at 12 months and 0.11 (0.04) mm at 24 months (P ≤ .001). Whole mouth mean (SE) percentage of sites with CEJ-GM distance of <0 mm increased significantly from 23.3% (1.0%) at baseline to 28.5% (1.0%) at 12 months and 30.5% (1.1%) at 24 months (P ≤ .02). Higher mean radiation dose to the mandible was associated with a greater increase in the percentage of mandibular sites with CEJ-GM distance of <0 mm (P = .003). Both mean CEJ-GM distance and the percentage of sites with a CEJ-GM distance <0 mm were strongly associated with whole mouth mean proportion of decayed, missing, and filled surfaces, as well as proportion of decayed or filled facial/buccal surfaces specifically, (P < .001), with greater gingival recession associated with increased caries.

CONCLUSIONS

RT for HNC leads to mandibular gingival recession in a dose-dependent manner. This gingival recession may contribute to increased risk for cervical caries seen in these patients.

Comparison of gingival crevicular fluid levels of IL-1b and IL-6 in subjects with gingivitis and stage III grade C periodontitis

Background/Aim: Periodontal diseases are inflammatory diseases that occur against microbial pathogens. Cytokines are biologically active molecules involved in this inflammatory process. This study aims to evaluate interleukin-1 beta (IL-1b) and interleukin-6 (IL-6) cytokine levels in the gingival crevicular fluid (GCF) of individuals with stage III grade C (SIIIGC) periodontitis, gingivitis (G) and periodontally healthy (PH). Material and Methods: A total of 64 individuals, including 22 PH, 22 G and 20 SIIIGC periodontitis were included in this study. Plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment loss (CAL) parameters were evaluated. GCF samples were analyzed by enzyme-linked immunosorbent assay (ELISA) kits. Results: IL-1b and IL-6 levels in the GCF were significantly higher in the SIII-GC periodontitis group compared to the other groups (P <0.05). There was no significant difference between IL-1b and IL-6 levels in the PH and G groups (P > 0.05). GCF IL-1b and IL-6 levels were positively associated with the whole mouth and sampling area clinical periodontal parameters (P < 0.001). Conclusions: GCF IL-1b and IL-6 total amounts are effective in determining the regions and individuals under risk in SIII-GC periodontitis. Moreover, GCF IL-1b and IL-6 levels were seen to be effective determinants in differentiating gingivitis and periodontitis.

Comparison of gingival crevicular fluid levels of IL-1b and IL-6 in subjects with gingivitis and stage III grade C periodontitis

Background/Aim: Periodontal diseases are inflammatory diseases that occur against microbial pathogens. Cytokines are biologically active molecules involved in this inflammatory process. This study aims to evaluate interleukin-1 beta (IL-1b) and interleukin-6 (IL-6) cytokine levels in the gingival crevicular fluid (GCF) of individuals with stage III grade C (SIII-GC) periodontitis, gingivitis (G) and periodontally healthy (PH). Material and Methods: A total of 64 individuals, including 22 PH, 22 G and 20 SIII-GC periodontitis were included in this study. Plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment loss (CAL) parameters were evaluated. GCF samples were analyzed by enzyme-linked immunosorbent assay (ELISA) kits. Results: IL-1b and IL-6 levels in the GCF were significantly higher in the SIII-GC periodontitis group compared to the other groups (P <0.05). There was no significant difference between IL-1b and IL-6 levels in the PH and G groups (P > 0.05). GCF IL-1b and IL-6 levels were positively associated with the whole mouth and sampling area clinical periodontal parameters (P < 0.001). Conclusions: GCF IL-1b and IL-6 total amounts are effective in determining the regions and individuals under risk in SIII-GC periodontitis. Moreover, GCF IL-1b and IL-6 levels were seen to be effective determinants in differentiating gingivitis and periodontitis.

Interleukin-6 gene -174G>C promoter polymorphism reduces the risk of periodontitis in Brazilian populations: A meta-analysis

INTRODUCTION

Periodontitis is a multifactorial host-mediated oral disease caused by microbes. Previous studies suggested that interleukin-6 (IL-6) gene promoter polymorphism (-174G > C) are associated with the risk of periodontitis, although the results were inconclusive. This study investigated the association between IL-6 -174G > C polymorphism and susceptibility to periodontitis.

METHOD

A comprehensive search was conducted in PubMed, EMBASE, Web of Science, and Google Scholar databases to retrieve relevant studies. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the association between 174G > C polymorphism and the risk of periodontitis. Cochrane Q and I² statistics were used to measure heterogeneity between studies. Publication bias was estimated using Begg's funnel plots and Egger's test.

RESULTS

Our results showed significant differences in the allelic (C vs. G: OR = 0.82, CI = 0.65-1.03), recessive (CC vs. GC + GG: OR = 0.69, CI = 0.42-1.13), and dominant (GC + CC vs. GG: OR = 0.85, CI = 0.63-1.13) genetic models of the IL6 -174G > C polymorphism and risk of periodontitis. Further, subgroup analysis showed decreased susceptibility to periodontitis associated with IL6 -174 G > C in a Brazilian population (C vs. G: OR = 0.60, CI = 0.41-0.88; GC + CC vs. GG: OR = 0.57, CI = 0.42-0.78) but not in Asian or Caucasian populations.

CONCLUSION

The findings of this study revealed that the IL6 -174 "C" allele is protective against periodontitis in the Brazilian population.

Association of interleukin-6 (174 G/C) and interleukin-12B (1188 A/C) gene polymorphism with expression and risk of Japanese encephalitis disease in North Indian population

BACKGROUND

Japanese encephalitis is an acute inflammatory disease caused by Japanese encephalitis virus (JEV). In this study we aim to determine the association of IL-6 (174) and IL-12B (1188A/C) gene polymorphisms with JEV susceptibility, disease severity and outcomes in north Indian population.

METHODS

This study was performed an equal number of cases and control individuals (125). Gene polymorphism has been analyzed by PCR-RFLP and expression by ELISA.

RESULTS

Homozygous(C/C) genotypes of IL-12B were significantly associated with protection in JE infection (p = 0.008, OR = 0.368) whereas IL-6 was not associated with JEV infection (p = 0.269, OR = 1.245). The C allele of IL-6 was associated with protection in JE disease and G/C genotype was associated with outcomes with recovered individuals.

CONCLUSION

IL-12B gene polymorphism leads to increase level of IL-12B in JE patients, which can contribute to JE susceptibility and disease severity. IL-6 polymorphism has not been associated with susceptibility of JE. Overall, this is the first information from northern India shows association of IL-6 and IL-12B polymorphisms with JE disease.

Evaluation of the Genetic Association and Methylation of Immune Response Pathway Genes with the Risk of Chronic Periodontitis in the Uighur Population

Aim: The aim of this study was to explore the possible associations between single nucleotide polymorphisms (SNPs) and DNA methylation levels of seven genes in the inflammatory response pathway with susceptibility to chronic periodontitis (CP) among the Uighur population of the Xinjiang Autonomous Region of China. Methods: A total of 444 eligible subjects (279 CP patients and 165 healthy controls) were enrolled in the study. Genomic DNA was obtained from gingival tissue for genotyping eight SNPs and performing methylation measurements of seven genes. Results: SNP rs2070745 in the formyl peptide receptor 1 (FPR1) gene achieved statistical significance in a standard allelic association analysis for CP (p = 0.02). The frequency of the rs2070745 minor allele G was higher in the cases than in controls (0.367 vs. 0.291). Additionally, rs2070745 was significantly associated with CP under the dominant genetic model (p = 0.03). Using logistic regression analysis, rs2070745 was found to be consistently associated with CP under the additive dominant model, and this association remained significant after covariates were taken into account [odds ratio (OR) = 1.49 (1.09-2.05), p = 0.014; OR = 1.58 (1.04-2.40), p = 0.031, respectively]. No significant gene-gene interactions were identified. Although we did not find a polymorphism in interleukin 6 (IL6) associated with CP in our study, the methylation level of a CpG island region located within the promoter region of IL6 was significantly less in CP patients compared with controls (p < 0.05). Conclusions: The genetic polymorphism rs2070745 in FPR1 and the methylation level of the promoter region of IL6 might be associated with CP in the Uighur population of China.

Cytokines and Their Genetic Polymorphisms Related to Periodontal Disease

Periodontal disease (PD) is a chronic inflammatory disease caused by the accumulation of bacterial plaque biofilm on the teeth and the host immune responses. PD pathogenesis is complex and includes genetic, environmental, and autoimmune factors. Numerous studies have suggested that the connection of genetic and environmental factors induces the disease process leading to a response by both T cells and B cells and the increased synthesis of pro-inflammatory mediators such as cytokines. Many studies have shown that pro-inflammatory cytokines play a significant role in the pathogenesis of PD. The studies have also indicated that single nucleotide polymorphisms (SNPs) in cytokine genes may be associated with risk and severity of PD. In this narrative review, we discuss the role of selected cytokines and their gene polymorphisms in the pathogenesis of periodontal disease.

Interaction between and impact of IL-6 genotype and alpha-tocopherol levels on periodontal condition in aging individuals

BACKGROUND AND OBJECTIVES

Few studies have assessed the possible interaction between and impact of IL-6 variants and serum α-tocopherol levels on periodontal condition in older individuals. Here, we assessed the relationship between IL-6 variants and serum α-tocopherol levels on periodontal condition by considering effect modification.

MATERIAL AND METHODS

Among the study participants, 359 who were 71 years of age underwent a dental examination, biochemical analysis, and interview. After dividing the participants into tertiles based on serum α-tocopherol levels, we conducted Poisson regression analysis to compare the prevalence rate ratio (PRR) for periodontal disease markers with the IL-6 genotype (rs1800796) based on each tertile adjusted by the number of teeth present (offset).

RESULTS

The PRRs of the IL-6 genotype for periodontal condition (probing pocket depth [PPD], clinical attachment level [CAL], and bleeding on probing [BOP]) which were adjusted by the number of teeth present (offset) were 1.17 (P < .001), 1.37 (P < .001), and 1.08 (P = .048), respectively. In addition, a significant association was found between the reciprocal number of PRRs of the IL-6 genotype and three serum α-tocopherol levels. The adjusted PRRs (± standard error) of the IL-6 genotypes for PPD were 0.48 (0.12) for the first group (P < .001), 1.54 (0.04) for the second group (P < .001), and 2.11 (0.03) for the third group (P < .001); similar tendencies were seen for CAL and BOP.

CONCLUSION

The results of this study suggest a potential association between the IL-6 genotype and periodontal condition in relation to serum antioxidant concentrations.

Genetic polymorphisms in the Interleukins IL1B, IL4, and IL6 are associated with concomitant periodontitis and type 2 diabetes mellitus in Brazilian patients

OBJECTIVE

To assess whether single nucleotide polymorphisms (SNPs) in the IL10, IL1A, IL1B, IL4, TNFA, IL6, OPG, RANK, and RANKL genes, "classically" related with periodontitis, could be associated with susceptibility to T2DM, and also with both diseases concomitantly.

BACKGROUND

There are common pathogenic mechanisms in type 2 diabetes mellitus (T2DM) and periodontitis, but the knowledge of the genetic aspect of this is limited. In patients affected by concomitant T2DM and periodontitis, whose incidence is increasing, there is scarce information regarding the gene-phenotype association, including whether there are genes able to influence both diseases as comorbidities.

METHODS

Periodontal clinical parameters and biochemical profile (Insulin, Fasting Glycemia, HbA1c, Triglycerides, Total Cholesterol, HDL-cholesterol, and LDL-cholesterol) data were obtained from 894 individuals divided into following three groups: Healthy (H; n = 347), Periodontitis (P; n = 348), and Periodontitis + T2DM (P + T2DM; n = 199). DNA from oral epithelial cells was collected for genotyping. Associations between SNPs and pathologies were tested by multiple logistic regression models, adjusting for age, sex, and smoking habits. We also investigated whether there are sex or smoking effects of each SNP in these phenotypes.

RESULTS

The rs1143634-GA (IL1B) SNP showed significantly less likely to develop P + T2DM for all population and mainly for women (adjusted OR = 0.37, 95% CI = 0.16-0.88), while women carrying the rs224320 CT (IL4) were more susceptible to develop P + T2DM (adjusted OR = 1.81, 95% CI = 1.04-3.15). Men carrying the rs1800795-CC (IL6) genotype were less likely to develop T2DM (adjusted OR = 0.12, 95% CI = 0.02-0.70, P = .01).

CONCLUSIONS

Some SNPs in the IL1B, IL4, and IL6 genes demonstrated sex-influenced association with concomitant periodontitis and T2DM, increasing the evidence of a common genetic component between these diseases and contributing with the understanding of their common pathogenic mechanisms.

Immunomodulatory factors gene polymorphisms in chronic periodontitis: an overview

BACKGROUND

Chronic periodontitis (CP), defines as destruction of the supporting tissues of the teeth and resorption of the alveolar bone. It is widespread in human populations and represent an important problem for public health. CP results from inflammatory mechanisms created by the interaction between environmental and host genetic factors that confer the individual susceptibility to the disease.

AIM

The aim of the current study was to explore and summarize some functional biomarkers that are associated with CP susceptibility.

METHODS

CP is considered to be a multifactorial disease. The pathogenesis of multifactorial diseases is characterized by various biological pathways. The studies revealed that polymorphisms were associated with susceptibility to periodontal diseases. In other word, genetic variations can change the development of CP. However, there are some conflicting results, because there are different variations in frequency of some alleles in any populations. Therefore, we conducted the current review to completely understanding the special biomarkers for CP.

RESULTS

There is some evidence that SNPs in the IL-1α, IL-1β, IL1RN, IL-6, IL-10, TNF-α, TGF-β1, IFN-γ and VDR may be associated with CP susceptibility.

CONCLUSION

In conclusion, numerous studies have reported the host genetic factors associated with CP susceptibility and related traits. Therefore, it is prevail to study the multiple SNPs and their effects to find the useful diagnosis methods. The current study will investigate the relationship between polymorphisms in cytokine genes and the susceptibility to the chronic periodontitis.

IL-6 and TNF-α salivary levels according to the periodontal status in Portuguese pregnant women

Background

Periodontitis is associated with increased concentration of inflammatory markers and saliva has been proposed as a non-invasive diagnostic fluid in oral and systemic diseases. The levels of salivary biomarkers, such as cytokines, could potentially be used to distinguish periodontal healthy individuals from subjects with periodontal disease. The purpose of this study was to characterize the salivary levels of two inflammatory biomarkers associated with periodontitis, interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α), in order to assess whether these cytokines salivary levels could potentially be used to complement periodontitis pregnant women diagnose.

Methods

Forty-four pregnant women were distributed into three groups, according to their periodontal status: healthy, mild/moderate periodontitis and severe periodontitis. Unstimulated saliva was collected and analysis of TNF-α and IL-6 salivary levels were performed with Immulite^®.

Results

Women with periodontitis exhibited significantly higher levels (p = 0.001) of salivary IL-6 and TNF-α compared with the healthy group: 25.1 (±11.2) pg/mL vs. 16.3 (±5.0) pg/mL and 29.7 (±17.2) pg/mL vs. 16.2 (±7.6) pg/mL, approximately 1.5 and 1.8 times more, respectively. Additionally, cytokines were significantly increased (p < 0.05) in severe periodontitis compared to periodontal healthy pregnant women.

Conclusions

These results revealed that IL-6 and TNF-α salivary biomarkers provide high discriminatory capacity for distinguishing periodontal disease from periodontal health in pregnant women.

Interleukin-6 and interleukin-10 gene polymorphisms and the risk of further periodontal disease progression

Susceptible genotypes to periodontal disease are associated with disease onset and progression. The aim of this study was to examine the effect of gene polymorphisms on the risk of further disease progression and the need for further treatment among adults with chronic periodontal disease. Sixty-seven patients diagnosed with chronic periodontitis were grouped according to genotype status and risk of further progression of disease and tooth loss. All individuals were clinically evaluated for probing pocket depth, clinical attachment loss and bleeding on probing at baseline and 45 days after treatment. Blood samples were collected at baseline and genotyping of the polymorphisms in IL-6 (rs1800796) and IL-10 (rs1800872) genes were performed by PCR. Following DNA separation and genotyping, 65.7% of the patients were homozygous carriers of the IL-6 -572G and 49.3% were carriers of the IL-10 -592A allele. Individuals at risk of disease progression ranged from 7.5% to 62.7% based on the criteria used. Carriers of the IL-10 -592A allele were significantly associated with BOP ≥ 30% and therefore exhibited a higher risk of further periodontal breakdown (p = 0.018) with an odds ratio of 1.18. None of the other definitions of disease progression were significantly associated with the examined IL-6 and IL-10 genotypes (p > 0.05). IL-10 polymorphism was associated with an increased risk of further disease progression and the potential need for further treatment following non-surgical periodontal treatment. Susceptible IL-6 genotypes were not associated with the risk of persisting or recurrent disease activity.

Aging, inflammation, immunity and periodontal disease

The increased prevalence and severity of periodontal disease have long been associated with aging, such that this oral condition affects the majority of the adult population over 50 years of age. Although the immune system is a critical component for maintaining health, aging can be characterized by quantitative and qualitative modifications of the immune system. This process, termed 'immunosenescence', is a progressive modification of the immune system that leads to greater susceptibility to infections, neoplasia and autoimmunity, presumably reflecting the prolonged antigenic stimulation and/or stress responses that occur across the lifespan. Interestingly, the global reduction in the host capability to respond effectively to these challenges is coupled with a progressive increase in the general proinflammatory status, termed 'inflammaging'. Consistent with the definition of immunosenescence, it has been suggested that the cumulative effect of prolonged exposure of the periodontium to microbial challenge is, at least in part, a contributor to the effects of aging on these tissues. Thus, it has also been hypothesized that alterations in the function of resident immune and nonimmune cells of the periodontium contribute to the expression of inflammaging in periodontal disease. Although the majority of aging research has focused on the adaptive immune response, it is becoming increasingly clear that the innate immune compartment is also highly affected by aging. Thus, the phenomenon of immunosenescence and inflammaging, expressed as age-associated changes within the periodontium, needs to be more fully understood in this era of precision and personalized medicine and dentistry.

Role of Thr399Ile and Asp299Gly polymorphisms of toll-like receptor-4 gene in acute dental abscess

BACKGROUND

Apical Periodontitis (AP) is an inflammatory disease that affects the tissues surrounding the root end of a tooth. The disease which is caused by endodontic infections presents in different clinical ways including development of an acute abscess. Recent studies have provided information suggesting role of a multitude of factors in pathogenesis of acute apical abscess (AAA). In this case-control study, our goal was to evaluate the frequency and potential role of two common polymorphisms of toll like receptor-4 (TLR-4) gene; Thr399Ile (1196 C>T) and Asp299Gly (+896 A>G), in 50 patients with AAA as cases and 50 patients with asymptomatic apical periodontitis (AAP) as controls.

MATERIAL AND METHODS

Saliva sample containing mucosal epithelial cells was used for DNA extraction. Polymorphisms were detected by Tetra-ARMS (Amplification Refractory Mutation System) PCR method. Statistical analyses were carried out in SPSS 21 software.

RESULTS

Homozygous wild type (CC) and heterozygous (CT) genotypes of Thr399Ile polymorphism were detected in 84% and 16% of AAA patients respectively. In controls, respective ratios were 94% (CC) and 6% (CT). Observed difference was not statistically significant (P>0.05) for distribution of these genotypes. The mutant homozygous (TT) genotype of this polymorphism was identified in neither of the participants. Overall, T allele frequency was obtained 8% in AAA and 3% in AAP (OR=2.6, 95% CI; 0. 6-10.6, p>0.05). For Asp299Gly polymorphism, no individual was detected with the mutant allele in case or control groups.

CONCLUSIONS

Our results indicated a possible role for Thr399Ile polymorphism in acute presentations of abscess in AAA. However, the impact of this polymorphism needs to be more assessed in future studies. Key words:Genetic polymorphism, periapical abscess, periapical periodontitis, toll-like receptor 4.

Interleukin-6-174G/C Polymorphism Contributes to Periodontitis Susceptibility: An Updated Meta-Analysis of 21 Case-Control Studies

Introduction. Chronic Periodontitis (CP) is suggested to be related to gene variations. Present study aims to quantitatively estimate the association between interleukin-6- (IL-6-) 174G/C polymorphism and CP susceptibility. Materials and Methods. Pubmed, Embase, and Web of Science were searched up to May 2016. The meta-analyses were performed using STATA 12.0. Results. 21 studies were yielded. Significant associations were found under heterozygote comparison and dominant model in studies fulfilling HWE (GC versus GG: OR = 0.690, 95% CI = 0.560–0.849, P = 0.000; CC + GC versus GG: OR = 0.690, 95% CI = 0.568–0.838, P < 0.001); significant associations were found under heterozygote comparison and dominant model in Caucasian studies fulfilling HWE (GC versus GG: OR = 0.752, 95% CI = 0.577–0.980, P = 0.035; CC + GC versus GG: OR = 0.737, 95% CI = 0.576–0.944, P = 0.016); significant associations were found under allele comparison, heterozygote comparison, and dominant model in Brazilian population (C versus G: OR = 0.648, 95% CI = 0.497–0.845, P = 0.001; GC versus GG: OR = 0.621, 95% CI = 0.441–0.876, P = 0.007; CC + GC versus GG: OR = 0.649, 95% CI = 0.470–0.896, P = 0.009). Conclusion. IL-6 174 polymorphism is associated with CP susceptibility. In Brazilian and Caucasian population, IL-6 174 GG genotype plays as a risk factor to CP.

Host and clinical aspects in patients with benign migratory glossitis

OBJECTIVE

Investigate the association of clinical, cytological and genetic characteristics with benign migratory glossitis (BMG).

STUDY DESIGN

Sample consisted of 175 patients, 44 with BMG and 131 control patients. Clinical examination and DMFT index were assessed. Cytological evaluation determined cell morphology and morphometry. Genetic evaluation was performed by analysing IL6 polymorphisms by real-time PCR. Univariate and multivariate analyses were performed (p<0.05).

RESULTS

There was a higher level of anxiety, DMFT score and a prevalence of fissured tongue in BMG group. A high mean nuclear/cytoplasmic area ratio was observed in patients with BMG. There was predominance of Papanicolaou class II I BMG group. IL6 allele G rs2069843 polymorphism was associated with BMG in the dominant model. In multivariate analysis, DMFT and anxiety scale remained associated with BMG.

Association among interleukin-6 gene polymorphisms, type 2 diabetes mellitus, and chronic periodontitis: a pilot study

AIM

The purpose of this pilot study was to determine the association between single nucleotide polymorphisms (-174 G>C) in the interleukin-6 (IL-6) gene with chronic periodontitis (CP) and type 2 diabetes mellitus (T2DM) in south Indian population.

METHODS

Genomic DNA was obtained from the white blood cells of 30 patients with T2DM, 30 patients with CP, 30 patients with T2DM with CP, and 30 controls. DNA was amplified using polymerase chain reaction with specific primers flanking the locus -174 of the IL-6 gene and further genotyped using the restriction fragment length polymorphism method. The genotype distribution and allele frequencies between the study groups were determined using χ² -test. The relative risk was estimated with a 95% confidence interval.

RESULTS

The CP group (26.7%) displayed a greater percentage of GC genotype (P = 0.026) when compared to the control group (3.3%). A statistically-significant difference in the allele frequencies was found between the control and CP group with the C-allele frequency being greater (0.13) in the CP group than normal controls (0.02).

CONCLUSION

The GC genotype was found to be the risk genotype and the C allele was found to be the risk allele for the development of CP.

Association between IFN-γ +874A/T and IFN-γR1 (-611A/G, +189T/G, and +95C/T) Gene Polymorphisms and Chronic Periodontitis in a Sample of Iranian Population

Background. Interferon gamma (IFN-γ) is an immune regulatory cytokine that acts through its receptor and plays important role in progression of inflammatory disease such as chronic periodontitis (CP). The purpose of this study was to determine the differences in the distribution of IFN-γ (+874A/T) and IFN-γR1 (-611A/G, +189T/G, and +95C/T) gene polymorphisms among CP and healthy individuals and to investigate relationships between these polymorphisms and susceptibility to CP. Materials and Methods. 310 individuals were enrolled in the study including 210 CP patients and 100 healthy controls. Single nucleotide polymorphisms at IFN-γ (+874A/T) and IFN-γR1 (-611A/G, +189T/G, and +95C/T) were analyzed by ARMS-PCR and PCR-RFLP methods. Results. The significant difference was found in genotype and allele frequency of IFN-γ (+874A/T) gene polymorphism in chronic periodontitis patients and healthy controls. The distribution of genotypes and allele frequencies for IFN-γR1 (-611A/G, +189T/G, and +95C/T) were similar among the groups and no differences in the frequencies of alleles or genotypes of IFN-γR1 genetic polymorphisms variants between case and control groups were detected. Conclusion. The finding of this study showed that IFN-γ +874A/T gene polymorphism may affect susceptibility to CP, whereas IFN-γR1 genetic polymorphisms at -611A/G, +189T/G, and +95C/T were not associated with this disease.

Circulating interleukin-6 and cancer: A meta-analysis using Mendelian randomization

Interleukin-6 (IL-6) plays a contributory role in the progression and severity of many forms of cancer; it however remains unclear whether the relevance between circulating IL-6 and cancer is causal. We therefore meta-analyzed published articles in this regard using IL-6 gene -174G/C variant as an instrument. Seventy-eight and six articles were eligible for the association of -174G/C variant with cancer and circulating IL-6, respectively. Overall analyses failed to identify any significance between -174G/C and cancer risk. In Asians, carriers of the -174CC genotype had an 1.95-fold increased cancer risk compared with the -174GG genotype carriers (P = 0.009). By cancer type, significance was only attained for liver cancer with the -174C allele conferring a reduced risk under allelic (odds ratio or OR = 0.74; P = 0.001), homozygous genotypic (OR = 0.59; P = 0.029) and dominant (OR = 0.67; P = 0.004) models. Carriers of the -174CC genotype (weighted mean difference or WMD = −4.23 pg/mL; P < 0.001) and -174C allele (WMD = −3.43 pg/mL; P < 0.001) had circulating IL-6 reduced significantly compared with the non-carriers. In further Mendelian randomization analysis, a reduction of 1 pg/mL in circulating IL-6 was significantly associated with an 12% reduced risk of liver cancer. Long-term genetically-reduced circulating IL-6 might be causally associated with a lower risk of liver cancer.

Gingival fibroblasts from periodontitis patients exhibit inflammatory characteristics in vitro

OBJECTIVE

Gingival fibroblasts (GFs) are an important regulatory cell type in the progression of periodontitis. This study aimed to compare the expression levels of genes associated with inflammation, extracellular matrix degradation and bone destruction in GFs isolated from healthy and periodontitis subjects in the absence and presence of Porphyromonas gingivalis.

DESIGNS

Primary GFs from healthy (n=10) and periodontitis subjects (n=10) were stimulated in vitro with viable P. gingivalis ATCC 49417 and 3 clinical isolates of P. gingivalis with type II fimbriae from one healthy subject (KUMC-H1) and two periodontitis patients (KUMC-P1, -P2). The mRNA expression of proinflammatory cytokines (interleukin (IL)-6, IL-8, IL-1B), anti-inflammatory cytokines (IL-4, IL-10), matrix metalloproteinase (MMP)-1 and 2, tissue inhibitor matrix metalloproteinase (TIMP)-3 and osteoprotegerin (OPG) were assessed using real-time PCR. The levels of IL-6, IL-1β and TIMP-3 protein were measured by an enzyme-linked immunosorbent assay.

RESULTS

The mRNA expression of IL-6, IL-1B and TIMP-3 was higher in the periodontitis group compared with the healthy group, whereas IL-4 expression was higher in the healthy group both in the absence and presence of the P. gingivalis strains. The expression levels of IL-6, IL-1β and TIMP-3 protein were also higher in the periodontitis group in the absence and/or presence of the P. gingivalis strains. There was inter-strain variability among P. gingivalis strains in the ability to induce expression of the proinflammatory cytokines, MMPs and OPG and in the ability to degrade IL-6 protein.

CONCLUSION

High expression of proinflammatory cytokines and TIMP-3 and low expression of IL-4 can be a signature of GFs associated with periodontitis.

Interleukin-6 gene polymorphism (-174 G/C) is associated with toxoplasmic retinochoroiditis

PURPOSE

Experimental data have demonstrated a relevant role for IL-6 in the modulation of acute ocular toxoplasmosis. Therefore, we aim to investigate the possible association between the IL-6 gene polymorphism at position -174 and toxoplasmic retinochoroiditis (TR) in humans.

METHODS

Ninety-seven patients with diagnosed TR were recruited from the Uveitis Section, Federal University of Minas Gerais. For comparison, 83 healthy blood donors with positive serology for toxoplasmosis and without retinal signs of previous TR were included in the study. Genomic DNA was obtained from oral swabs of individuals and amplified using polymerase chain reaction (PCR) with specific primers flanking the locus -174 of IL-6 (-174G/C). PCR products were submitted to restriction endonuclease digestion and analysed by polyacrylamide gel electrophoresis to distinguish allele G and C of the IL-6 gene, allowing the detection of the polymorphism and determination of genotypes.

RESULTS

There was a significant difference in the genotype (χ(2) = 12.9, p = 0.001) and allele (χ(2) = 6.62, p = 0.01) distribution between TR patients and control subjects. In a subgroup analysis, there was no significant difference in genotypes and allele frequencies regarding TR recurrence.

CONCLUSIONS

This study suggests that the genotypes related with a lower production of IL-6 may be associated with the occurrence of TR.

The association of IL-6 and IL-6R gene polymorphisms with chronic periodontitis in a Chinese population

OBJECTIVE

The aim of our investigation is to reveal the association of interleukin-6 (IL-6) and interleukin-6 receptor (IL-6R) gene polymorphisms with chronic periodontitis in Northwestern Chinese Han Population.

MATERIAL AND METHODS

A case-control study of 199 cases of chronic periodontitis patients and 216 healthy controls was performed. Genomic DNA was isolated from whole venous blood, and four single nucleotide polymorphisms (IL-6 -572 G/C and -1363 G/T, IL-6R -183 G/A and +48892 A/C) were analysed using polymerase chain reaction, followed by restriction fragment length polymorphism analysis and sequencing methods.

RESULTS

Our SNP analyses showed that the distribution of the IL-6 -572 G/C and IL-6R -183 G/A polymorphisms did not differ between patients and controls. The frequency of the IL-6 -1363 G/T genotype GG was significantly increased chronic periodontitis cases (P = 0.023, odds ratio (OR) = 2.825 adjusted for gender and age.) The IL-6R +48892 A/C polymorphisms genotype CC was found to be protective against chronic periodontitis (P = 0.004, OR = 0.318 adjusted for gender and age.). In addition, compared with the other haplotypes, haplotype A(+48892) A(-183) was significantly associated with chronic periodontitis, with an odds ratio of 0.720 (P = 0.0235).

CONCLUSION

Our results suggest that the IL-6 -1363 G/T and IL-6R +48892 A/C polymorphisms may contribute to genetic susceptibility to chronic periodontitis in Northwestern Chinese Han population.

Expression of IL-1β, IL-6, TNF-α, and iNOS in pregnant women with periodontal disease

Periodontal disease is one of the most prevalent oral diseases. An association between this disease and pregnancy has been suggested, but available findings are controversial. We evaluated the expression levels of interleukins (IL-1β and IL-6), tumor necrosis factor-alpha (TNF-α), and inducible nitric oxide synthase (iNOS) in pregnant women with and without periodontal disease in comparison with non-pregnant women with and without periodontal disease since studies have suggested a relationship between periodontitis and the expression levels of these genes. The women in the sample were distributed into four groups: pregnant and non-pregnant women, with or without periodontal disease, a total of 32 women. The periodontal condition was evaluated according to the probing depth, clinical attachment level and bleeding on probing. Analysis of gene expression was performed by real-time PCR. Comparisons were made of the level of gene expression among the four groups. Expression of IL-1β in the non-pregnant women with periodontal disease was 12.6 times higher than in the non-pregnant women without periodontal disease (P < 0.01), while expression of TNF-α in the non-pregnant women without periodontal disease was 3.5 times higher than in the pregnant women with periodontal disease (P < 0.05). Despite these differences, our overall findings indicate no differences in the expression levels of the cytokines IL-1β, IL-6, TNF-α, and iNOS in pregnant women with and without periodontal disease in comparison with expression of the same genes in non-pregnant women with and without periodontal disease, suggesting that periodontal disease is not influenced by pregnancy.

Expression, polymorphism and methylation pattern of interleukin-6 in periodontal tissues

Periodontitis is considered an inflammatory disorder of bacterial etiology that results in periodontal tissue destruction, as a result of complex interactions between periodontal pathogens, host and immune response. Genetic and epigenetic mechanisms may modulate the individual response since it is able to influence the gene expression. The aim of this study was to evaluate the impact of -174 G/C polymorphism and the methylation status of the promoter region of IL-6 gene on the expression of IL-6 in gingival samples from individuals with chronic periodontitis. Gingival biopsies were collected from 21 patients with chronic periodontitis and 21 controls. Histologic sections stained by hematoxylin-eosin were used for histopathological evaluation. The IL-6 gene expression was assessed by quantitative real-time PCR. The polymorphism IL-6 -174 C/G was studied by polymerase chain reaction (PCR) amplification and restriction endonuclease digestion (HspII). Methylation-specific polymerase chain reaction was used to verify the DNA methylation pattern. The number of inflammatory cells in tissue fragments from individuals with chronic periodontitis was higher than in the control group and the inflammatory infiltrate was predominantly mononuclear. The expression of IL-6 was higher in the group with periodontitis. In polymorphism assay, no statistical difference in the distribution of genotypes and alleles in both groups were observed. The most of samples were partially methylated. No difference was observed in methylation pattern from two different regions of the IL-6 gene among groups. The high expression of IL-6 is an important factor related to chronic periodontitis, but was not associated with methylation status or the -174 (G/C) genetic polymorphism, suggesting that other mechanisms are involved in this gene transcription regulation.

Sex differences in destructive periodontal disease: a systematic review

BACKGROUND

Sexual dimorphisms exist in the prevalence and severity of many human conditions and diseases. Models of risk assessment for periodontitis, however, are inconsistent with respect to the inclusion of sex as a risk factor. A systematic review of the literature and meta-analyses estimates sex-related differences in the prevalence of periodontitis.

METHODS

MEDLINE, EMBASE, and SCOPUS databases were searched for population surveys (sample size >500, half-mouth minimum, clinical attachment level) containing prevalence data on destructive periodontal disease in males and females.

RESULTS

Data were stratified by disease thresholds (3, 4, 5, and 7 mm) representing 50,604 subjects from 12 population surveys meeting selection criteria. Using a ≥ 5-mm clinical attachment loss threshold, seven studies provided data, permitting computation of mean-weighted sex differences in prevalence. Four studies provided data enabling a meta-analysis of prevalence rates. Sex exhibited a significant association with prevalence, reflecting a 9% difference between males and females (37.4% versus 28.1%, respectively), although the overall effect of sex in the meta-analysis was comparatively small (d = 0.19; 95% confidence interval, 0.16 and 0.22). This mean difference in prevalence between males and females was similar regardless of severity of disease threshold and after adjustment for other risk factors.

CONCLUSIONS

Men appear at greater risk for destructive periodontal disease than women; however, men do not appear at higher risk for more rapid periodontal destruction than women.

Gingival overgrowth in cyclosporine, tacrolimus, or sirolimus-based immunosuppressive regimens and the single nucleotide IL-6 (-174 G/C) gene polymorphism

OBJECTIVE

Interleukin-6 (IL-6) may be involved in drug-induced gingival overgrowth (GO). The present study was conducted to assess the association between IL-6 (-174 G/C) gene polymorphism and GO in renal transplant recipients under cyclosporine (CsA), tacrolimus (Tcr), or sirolimus (Sir)-based regimens.

METHODS

Within an eligible population, 45 unrelated subjects were selected for each CsA, Tcr, and Sir group, totaling a sample of 135 subjects. GO was visually assessed and subjects were assigned as controls (non-responders) or cases (responders) in a post hoc definition. IL-6 gene polymorphism was assessed using the polymerase chain reaction amplification and digestion. The distribution of genotypes and allele frequencies in responders and non-responders were compared using the Chi-squared test.

RESULTS

The number of responders was 27 (60.0%), 13 (28.9%), and 7 (15.6%) in the CsA, Tcr, and Sir groups, respectively. No differences could be observed at frequencies of -174GG, -174CG, and -174CC genotypes when comparing responders to non-responders in the CsA, Tcr, and Sir groups. Similar to genotypes, allele frequencies showed no differences between responders and non-responders in all groups.

CONCLUSIONS

No association between IL-6 (-174 G/C) gene polymorphism and gingival overgrowth was observed in renal transplant recipients under CsA, Tcr, or Sir-based immunosuppressive maintenance regimens.

Interleukin-6 polymorphisms modify the risk of periodontitis: a systematic review and meta-analysis

OBJECTIVE

To clarify the association of IL-6 polymorphisms and periodontitis, a meta-analysis of case-control studies and a systemic review were conducted.

MATERIAL AND METHODS

We performed a literature search using PubMed and Medline database to May 2009, with no restrictions. We also reviewed references from all retrieved articles. Six case-control studies involving 1 093 periodontitis cases and 574 controls were selected for meta-analysis to assess the purported associations between IL-6 polymorphisms and the risk of periodontitis. IL-6 -174 G/C and -572 C/G polymorphisms were included in the present meta-analysis, and the association between IL-6 -6331 T/C polymorphism and the risk of periodontitis was adequately reviewed as well.

RESULTS AND CONCLUSION

The present meta-analysis indicates that the IL-6 -174 G allele could not modify the risk of chronic periodontitis, but increased the risk of aggressive periodontitis. And -572 C/G polymorphism is associated with the pathogenesis of periodontitis, including chronic periodontitis or aggressive periodontitis.

Destructive effects of smoking on molecular and genetic factors of periodontal disease

Many epidemiological evidences have proven the association between smoking and periodontal disease. The causality can be further established by linking findings of traditional epidemiological studies with the developments in molecular techniques that occurred in the last decade. The present article reviews recent studies that address the effect of smoking on molecular and genetic factors in periodontal disease. Most findings support the fact that tobacco smoking modulates destruction of the periodontium through different pathways: microcirculatory and host immune systems, connective tissue, and bone metabolism. Although smokers experience an increased burden of inflammatory responses to microbial challenges compared to non-smokers, understanding the association between smoking and periodontal diseases involves substantial problems with respect to accuracy of measurements, and particularly, sampling of many subjects. It remains unclear whether genetic susceptibility to periodontal disease is influenced by exposure to smoking or the effect of smoking on periodontal disease is influenced by genetic susceptibility. Employment of molecular techniques may play a key role in further elucidation of mechanisms linking smoking and periodontal destruction, the direct relationship as environmental factors and indirect relationship through genetic factors.

Gene polymorphisms in chronic periodontitis

We aimed to conduct a review of the literature for gene polymorphisms associated with chronic periodontitis (CP) susceptibility. A comprehensive search of the literature in English was performed using the keywords: periodontitis, periodontal disease, combined with the words genes, mutation, or polymorphism. Candidate gene polymorphism studies with a case-control design and reported genotype frequencies in CP patients were searched and reviewed. There is growing evidence that polymorphisms in the IL1, IL6, IL10, vitamin D receptor, and CD14 genes may be associated with CP in certain populations. However, carriage rates of the rare (R)-allele of any polymorphism varied considerably among studies and most of the studies appeared under-powered and did not correct for other risk factors. Larger cohorts, well-defined phenotypes, control for other risk factors, and analysis of multiple genes and polymorphisms within the same pathway are needed to get a more comprehensive insight into the contribution of gene polymorphisms in CP.