Two polymorphisms of interleukin-4 gene in Korean adult periodontitis

The Association between High-density Lipoproteins and Periodontitis

Periodontitis is one of the most typical chronic dental diseases. This inflammatory disease can change various functions of immune cells and impair lipid metabolism through proinflammatory cytokines. High-Density Lipoprotein (HDL) is considered protective of the cardiovascular system. It has anti-thrombotic and anti-inflammatory effects. In this article, we have reviewed the association between periodontitis and HDL. Various studies have demonstrated a reverse relationship between inflammatory cytokines and HDL. HDL contains antioxidative enzymes and proteins, whereas periopathogens impair HDL's antioxidant function. The presence of periodontal bacteria is associated with a low HDL level in patients with periodontitis. Genetic variants in the interleukin- 6 (IL)-6 gene and cytochrome (CYP)1A1 rs1048943 gene polymorphism are associated with HDL levels and periodontal status. Studies showed that HDL levels improve after treatment for periodontitis. On the one hand, periodontal pathogenic bacteria and their metabolites and pro-inflammatory cytokines from periodontal infection can result in various disorders of lipid metabolism and lipid peroxidation. On the other hand, hyperlipidemia and lipid peroxidation stimulate proinflammatory cytokines, resulting in oxidative stress and delayed wound healing, making individuals susceptible to periodontitis.

A Systematic Review and Meta-Analysis on Multiple Cytokine Gene Polymorphisms in the Pathogenesis of Periodontitis

Aim

Periodontitis is an inflammatory disease that destroys both soft and hard periodontal tissues. However, a complex periodontal cytokine network remains unclear. This systematic review explored multiple cytokine gene polymorphisms in the pathogenesis of periodontitis.

Material and Methods

A systematic search was performed using the databases from previous publications, which indicated the association between cytokine polymorphisms and periodontitis pathogenesis. Meta-analysis was conducted using fixed or randomized models to calculate the significance of multiple cytokine polymorphisms. A total of 147 articles were analyzed with polymorphisms in 12 interleukins [Th1 (IL-2, IFN-γ, and TNF-α), Th2 (IL-4 and IL-13), Th17 (IL-1α, IL-1β, IL-6, and IL-17), and Treg cytokines (IL-10 and TGF-β)]. Doi plot was used to probe the occurrence of publication bias.

Results

The polymorphisms of IL-2 and TNF-α of Th1 cytokine family may be associated with the pathogenesis or the prevention of periodontitis risk, while the polymorphism of IFN-γ is not related to periodontitis risk. The polymorphisms for IL-4 and IL-13 of Th2 cytokine family are not found to be associated with the pathogenesis of periodontitis. For the polymorphisms of the members of Th17 cytokine family, different IL-1α polymorphisms may have inverse actions in the pathogenesis of periodontitis. IL-1β is a noteworthy cytokine biomarker in periodontitis development and progression. IL-6 may have a protective function in the inflammatory responses of periodontitis, and IL-17 has a weak relationship the inflammatory responses. The polymorphisms for the members of Treg cell cytokines may have a protective function against periodontitis risk. LFK indexes show the major asymmetry due to publication bias.

Conclusion

IL-1β is a notable cytokine biomarker in periodontitis risk. Treg cytokines favor an anti-inflammatory and protective environment. Further data are needed to confirm the present conclusion due to publication bias.

IL4 gene VNTR polymorphism in chronic periodontitis in end-stage renal disease patients

OBJECTIVE

Interleukin-4 gene polymorphisms were found to be associated with periodontitis. The purpose of this case-control study was to evaluate association of IL4 VNTR polymorphism with periodontitis in patients with end-stage renal disease (ESRD).

SUBJECTS AND METHODS

We examined 180 ESRD patients with chronic periodontitis, 82 without CP and 180 healthy controls. Genomic DNA from all subjects was genotyped for the IL4 VNTR polymorphism by polymerase chain reaction (PCR).

RESULTS

Genotype distribution in all groups followed Hardy-Weinberg equilibrium. Significant differences in genotype and allele frequencies were observed between groups. The patient group had higher frequency of P1 allele than controls, with odds ratio for P1 allele 1.6 (95% CI 1.1-2.3) and P1P1 genotype 2.73 (95% CI 1.06-7.5). There were no differences in polymorphism distribution between ESRD patients without CP and controls. Periodontal disease was more severe in older patients (≥50 years). Similarly, patients with T2DM had more severe manifestation of CP than patients without diabetes (p = 0.01 for plaque index, p = 0.004 for bleeding index and p = 0.03 for gingival index).

CONCLUSION

Our findings suggest that VNTR polymorphism in IL4 gene might be a risk factor for chronic periodontitis in patients with ESRD.

Determining the relationship between atherosclerosis and periodontopathogenic microorganisms in chronic periodontitis patients

OBJECTIVES

The aim of this study is to determine the relationship between atherosclerosis and periodontopathogenic microorganisms in chronic periodontitis patients following periodontal treatment.

MATERIALS AND METHODS

A total of 40 patients were included in the study. 20 of these patients diagnosed with atherosclerosis and chronic periodontitis formed the test group. The remaining 20 patients were systemically healthy patients diagnosed with chronic periodontitis and formed the control group. All patients had nonsurgical periodontal treatment. The periodontopathogenic microorganism levels were determined at baseline and at 6 months in microbial dental plaque samples and WBC, LDL, HDL, PLT, fibrinogen, creatinine and hs-CRP levels were determined by blood samples.

RESULTS

Statistically significant reduction has been achieved in clinical periodontal parameters following non-surgical periodontal treatment in test and control groups. Following periodontal treatment, WBC, LDL, PLT, fibrinogen, creatinine and hs-CRP levels significantly decreased and HDL levels significantly increased in both test and control groups. Similarly, the periodontopathogenic microorganism levels significantly decreased following periodontal treatment in the test and control groups. A statistically significant positive correlation has been determined between the periodontopathogenic microorganism levels and WBC, LDL, PLT, fibrinogen, creatinine, and hs-CRP levels in the test group.

CONCLUSIONS

The association between hs-CRP, WBC, LDL, PLT, fibrinogen, creatinine, and the amount of periodontopathogenic microorganisms indicates the possibility that periodontal treatment could decrease the risk atherosclerosis. More studies must be conducted in order for these results to be supported.

Association between IL-4 and IL-4R Polymorphisms and Periodontitis: A Meta-Analysis

Background. Previous studies have revealed that gene polymorphisms of inflammatory factors may influence the development or progression of periodontitis, a main cause of tooth loss in adults; however, due to limitations of individual studies, inconsistent findings were reported. Objective. To meta-analytically investigate the relationship between periodontitis and the Interleukin-4 (IL-4) and Interleukin-4 receptor (IL-4R) gene polymorphisms. Methods. Databases were searched for relevant case-control studies. After study selection based on the predefined selection criteria, methodological quality assessment and data extraction were conducted independently by two reviewers, before subsequent statistical analyses. Results. 37 studies involving 4,385 patients and 5,168 controls were included. All the studied IL-4 polymorphisms were not significantly associated with periodontitis, except the -33C/T (CT versus CC: OR = 0.50, 95% CI = 0.28–0.88) associated with reduced AgP susceptibility. Positive association was found between IL-4R Q551 polymorphism and periodontitis susceptibility in three genetic models (R versus Q: OR = 1.59, 95% CI = 1.14–2.22; QR versus QQ: OR = 1.84, 95% CI = 1.21–2.80; RR + QR versus QQ: OR = 1.82, 95% CI = 1.22–2.72). Conclusions. A positive association exists between the IL-4R Q551R polymorphism and occurrence of CP. The IL-4 -33 CT genotype is negatively associated with the occurrence of AgP.

High interleukin-4 expression and interleukin-4 gene polymorphisms are associated with susceptibility to human paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is caused by dimorphic fungi from the Paracoccidioides brasiliensis complex. Previous studies have demonstrated that the severity of disease is associated with a T-helper 2 immune response characterised by high interleukin (IL)-4 production. In the present study we analysed two polymorphisms in the IL-4 gene (-590 C/T and intron-3 microsatellite) in 76 patients with PCM and 73 control subjects from an endemic area. The production of IL-4 by peripheral blood mononuclear cells after antigen or phytohaemagglutinin stimulation was determined by ELISA. A significant correlation was observed between the RP2/RP2 intron-3 genotype and infection with Paracoccidioides sp.(p = 0.011), whereas the RP1/RP1 genotype was correlated with resistance. No significant correlation was observed for the IL-4 promoter polymorphism. Furthermore, the low IL-4 expression observed in the control group compared with patients was associated with the RP1/RP1 genotype. These results suggest that IL-4 polymorphisms might be associated with the ability of the host to control Paracoccidioides sp.infection. The relevance of this polymorphism is supported by the observation that patients with disease produce high levels of IL-4 following mitogen or antigen stimulation. The IL-4 gene is located in the cytokine cluster region of chromosome 5 where other polymorphisms have also been described.

Association of interleukin-4 and interleukin-17F polymorphisms in periodontitis in Dravidian ethnicity

BACKGROUND:

Complex network of pro and anti-inflammatory cytokines are known to act in inflamed periodontal tissue. This study explores the distribution of interleukin (IL)-4 (+33 C/T) and IL-17F (7383A/G, 7488A/G) gene polymorphism in chronic and aggressive periodontitis subjects of Dravidian ethnicity.

MATERIALS AND METHODS:

This case control study consisted of 124 periodontitis individuals comprising of 63 chronic and 61 aggressive periodontitis subjects as cases, and control group consisted of 101 healthy subjects. All subjects were genotyped for IL-4 + 33C/T, IL-17F 7383A/G, 7488A/G by polymerase chain reaction amplification followed by TaqMan assay for IL-4 + 33C/T, restriction enzyme digestion and gel electrophoresis for IL-17F 7383A/G and sequencing for IL-17F 7488A/G.

RESULTS:

IL-4 + 33C/T was significantly associated with periodontitis (P < 0.05) at both allelic and genotypic level. In subgroup analysis also significant difference (P < 0.05) in allelic distribution between aggressive periodontitis and control group for loci IL-4 + 33C/T was noted. However, there was a lack of association between IL-17F 7383A/G and IL-17F 7488A/G with periodontitis and its sub-groups at both allelic and genotypic levels.

CONCLUSIONS:

In Malayalam speaking Dravidian population IL-4 + 33C/T loci appears to be an important risk factor for periodontal disease with a leaning towards aggressive periodontitis. The association between IL-17F at 7383A/G and 7488A/G loci with either chronic or an aggressive periodontitis could not be ascertained.

Epigenetic biomarkers: a step forward for understanding periodontitis

Periodontitis is a common oral disease that is characterized by infection and inflammation of the tooth supporting tissues. While its incidence is highly associated with outgrowth of the pathogenic microbiome, some patients show signs of predisposition and quickly fall into recurrence after treatment. Recent research using genetic associations of candidates as well as genome-wide analysis highlights that variations in genes related to the inflammatory response are associated with an increased risk of periodontitis. Intriguingly, some of the genes are regulated by epigenetic modifications, supposedly established and reprogrammed in response to environmental stimuli. In addition, the treatment with epigenetic drugs improves treatment of periodontitis in a mouse model. In this review, we highlight some of the recent progress identifying genetic factors associated with periodontitis and point to promising approaches in epigenetic research that may contribute to the understanding of molecular mechanisms involving different responses in individuals and the early detection of predispositions that may guide in future oral treatment and disease prevention.

Genetic polymorphism studies in periodontitis and Fcγ receptors

Periodontitis is a complex chronic subgingival plaque-induced inflammatory disease influenced by multiple factors, including genetics, behavior and the environment. Many genetic association studies have been conducted in periodontology. One of the most extensively investigated gene families is the Fcγ receptor gene family, which plays a key role in regulating host immune responses to bacteria. Unlike other genetic polymorphisms reported in periodontology, most Fcγ receptor polymorphisms reported not only have established biological functions but are reported to associate with other autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. There are, however, few recent reviews summarizing the association of this gene family with periodontitis. This article critically reviews the current understanding of genetic polymorphism studies in periodontitis, then summarizes the research status of Fcγ receptor polymorphisms and periodontitis and also of other genes involved in the regulatory network of Fcγ receptors, with special reference to their anticipated biological roles. Moreover, some possible future research directions in the related area are discussed.

Implications of cytokine gene polymorphisms on the orchestration of the immune response: lessons learned from oral diseases

Over the past 10 years, a plethora of information concerning the influence of gene polymorphisms on cytokine expression has been made available in the literature. Significant contribution to this field has come from studies of oral diseases, one of the widest spread health problems in the world, affecting hundreds of millions worldwide. Here we will discuss the importance of studies of gene polymorphism towards the identification of susceptible groups or prognostic indicators of oral disease. Additionally, we will highlight the differences in data obtained from genetically diverse populations and review the application of cytokine gene polymorphisms studies in oral diseases in autoimmune processes and parasitic infections.

Association of the polymorphisms in promoter and intron regions of the interleukin-4 gene with chronic periodontitis in a Turkish population

OBJECTIVES

The etiology of periodontitis is related to the interaction between micro-organisms and host responses. Host modifying factors, such as genetic predisposition, may increase the severity of periodontitis. Recent works have shown that the levels of cytokine expression are regulated by genetic polymorphisms, and that these variations can interfere with progression of the disease. This study therefore aimed to evaluate whether interleukin (IL) 4 gene polymorphisms are associated with severe generalized chronic periodontitis.

MATERIAL AND METHODS

Seventy-five severe generalized chronic periodontitis patients and 73 healthy subjects were examined. Blood samples were taken and genomic DNA was amplified by polymerase chain reaction (PCR). Identification of 70 base-pair repeat polymorphisms in intron 2 and C-->T polymorphisms at -590 position of the promoter region was performed through PCR-restriction fragment length polymorphism (RFLP).

RESULTS

No significant differences were found in the allele and genotype frequencies between the control and periodontitis group.

CONCLUSION

The IL-4 polymorphisms were not related to severe generalized chronic periodontitis in a Turkish population.

The association of the composite IL-1 genotype with periodontitis progression and/or treatment outcomes: a systematic review

BACKGROUND

Genetically transmitted traits such as cytokine gene polymorphisms may accentuate the host inflammatory response to the bacterial challenge and influence susceptibility to periodontitis.

OBJECTIVE

To systematically review the evidence of an association between the interleukin-1 (IL-1) composite genotype, i.e. presence of the allele 2 in the gene clusters IL-1A-889 and in IL-1B +3953, and periodontitis progression and/or treatment outcomes.

MATERIAL AND METHODS

Based on the focused question, a search was conducted for longitudinal clinical trials comparing progression of periodontitis and/or treatment outcomes in IL-1 genotype-positive (carrying allele 2) and IL-1 genotype-negative (not carrying allele 2) subjects. A search in the National Library of Medicine computerized bibliographic database MEDLINE and a manual search were performed. Selection of publications, extraction of data and validity assessment were made independently by two reviewers.

RESULTS

The search provided 122 titles of which 11 longitudinal publications were included. The heterogeneity of the data prevented the performance of a meta-analysis. While findings from some publications rejected a possible role of IL-1 composite genotype on progression of periodontitis after various therapies, other reported a prognostic value for disease progression of the positive IL-1 genotype status. When assessed on a multivariate risk assessment model, several publications concluded that the assessment of the IL-1 composite genotype in conjunction with other covariates (e.g. smoking and presence of specific bacteria) may provide additional information on disease progression. The small sample size of the available publications, however, requires caution in the interpretation of the results.

CONCLUSION

Based on these findings, (i) there is insufficient evidence to establish if a positive IL-1 genotype status contributes to progression of periodontitis and/or treatment outcomes. Therefore, (ii) results obtained with commercially available tests should be interpreted with caution.

Effect of genetic variability on the inflammatory response to periodontal infection

AIM

To review the association between genetic variability and the inflammatory response induced by periodontal infection.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed from January 2000 up to and including March 2005. The search included all types of publications, published in English without other limitations. The following search terms were used: "cytokine polymorphism", "gene polymorphism", "periodontitis", "gingivitis", "inflammation" and "host-response". The papers resulting from the above search were used as an additional source for relevant articles.

RESULTS

Genetic variability was examined for the correlation to clinical indicators of inflammation such as bleeding on probing (BOP), gingival inflammation, cytokine in gingival crevicular fluid (GCF) and cytokine production by inflammatory cells. According to the current literature, most of the studies found no association between genetic variability and BOP, gingival inflammation or cytokine concentrations in the GCF. These studies were hampered by inappropriate study designs and the use of inflammatory parameters as secondary rather than primary outcome variables. The data suggest that the production of inflammatory mediators by inflammatory cells may be affected by different genetic traits but further studies are needed in order to establish this association.

CONCLUSIONS

To date, there is no clear correlation between any of the gene polymorphisms and clinical indicators of inflammation. The powering of studies to reveal associations between single or multiple nucleotide polymorphisms and inflammatory parameters will need to involve a much larger number of subjects than were used in the past. The available data (including the interleukin-1 composite genotype) do not currently support the utility of such tests in the diagnosis and prognostic assessments of periodontal diseases.

Identification of genetic risk factors for periodontitis and possible mechanisms of action

AIM

To review the literature for genetic risk factors associated with periodontitis.

METHODS

Computerized search of the literature in English using key words: Periodontitis; Genes; Mutation; Polymorphism; Risk.

RESULTS AND CONCLUSIONS

Mutations in the cathepsin C gene (CTSC) have been identified as causal for the Papillon-Lefèvre syndrome (PLS), which includes prepubertal periodontitis (PP). Some CTSC mutations are causal for PP without PLS. No relationship has been demonstrated between CTSC mutations and other forms of periodontitis. Genetic polymorphisms in a candidate gene approach have been explored as risk factors for periodontitis. There is limited evidence that some polymorphisms in the genes encoding interleukins (IL)-1, Fc gamma receptors (Fc gammaR), IL-10 and the vitamin D receptor, may be associated with periodontitis in certain ethnic groups. However relatively large variations in carriage rates of the Rare (R)-alleles among studies on any polymorphism were observed. The available studies appear under-powered and do not adequately take into account other pertinent risk factors for periodontitis. Future studies should include larger cohorts, should clearly define phenotypes and should adequately control for other risk factors. In addition to the candidate gene approach, alternative strategies need to be considered to elucidate the gene variations, which confer risk for periodontitis.

Polymorphisms in genes coding for enzymes metabolizing smoking-derived substances and the risk of periodontitis

OBJECTIVES

Although the direct cause for periodontitis is oral bacterial infection, its progression depends upon genetic and environmental factors. Smoking, one of the environmental factors, is a risk factor for the development and severity of periodontitis. Therefore, individual susceptibility to periodontitis may be influenced by the polymorphisms of genes coding for enzymes metabolizing tobacco-derived substances. The object of this study is to investigate roles of genetic polymorphisms of these metabolizing enzymes in the risk for periodontitis.

MATERIAL AND METHODS

We investigated three important enzymes: cytochrome P450 (CYP) 1A1, CYP2E1 and glutathione S-transferase (GST) M1, involved in the metabolic activation and detoxification of tobacco-derived substances. The prevalence of the polymorphisms of these genes was examined in 115 patients with periodontitis as well as in 126 control subjects.

RESULTS

Significantly increased risk for periodontitis was observed for subjects with the polymorphic CYP1A1 m2 allele (odds ratio (OR)=2.3, 95% confidence interval (CI)=1.2-4.4). A significant risk increase for periodontitis associated with the GSTM1 allele was observed (OR=2.1, 95% CI=1.3-3.6). However, no association was observed between the CYP2E1 Pst1 polymorphism and risk for periodontitis (OR=1.3, 95% CI=0.6-2.5).

CONCLUSION

These results suggest that the GSTM1 and CYP1A1 polymorphisms may play an important role in risk for periodontitis.