The genetic impact of the Q551R interleukin-4 receptor alpha polymorphism for aggressive or chronic periodontitis and the occurrence of periodontopathic bacteria

Polymorphisms in Genes Involved in Inflammation and Periodontitis: A Narrative Review

Current evidence pinpoints that the variability in periodontitis traits in humans may be attributable to genetic factors. Different allelic variants can result in alterations in tissue structure, antibody responses and inflammatory mediators. Consequently, genetic variations may act as protective or risk factors for periodontal diseases. A number of features of the inflammatory and immune response that seem to play a role in the development of periodontitis have a clearly established genetic basis. Identifying genes that contribute to the pathogenesis of periodontitis may be utilized for risk assessment in both aggressive and chronic periodontitis. The aim of this narrative review is to summarize the role of polymorphisms in genes involved in inflammation and periodontitis, including cellular receptors, tissue compatibility antigens, antibodies and cytokines.

Interleukin-10 polymorphisms affect the key periodontal pathogens in Chinese periodontitis patients

Interleukin-10 (IL-10) polymorphisms have been shown to affect IL-10 production. This study investigated the influences of IL-10 polymorphisms on the susceptibility to chronic periodontitis (CP) and aggressive periodontitis (AP), and their possible role in the quantity of subgingival bacteria Aggregatibacter Actinomycetemcomitans and Porphyromonas gingivalis. 92 CP patients, 83 AP patients and 91 periodontal healthy controls were recruited. Serum IL-10 concentration was analyzed by enzyme-linked immunosorbent assay (ELISA). Gene polymorphisms were determined by multiplex SNaPshot technique. Bacteria were quantified by real-time polymerase chain reaction with TaqMan MGB probes. Taking into account age, gender and periodontal status, IL-10-592 AA, -819 TT and ATA/ATA genotype occurred more frequently in patients with CP than in healthy controls. In CP cases, higher quantity of subgingival A. actinomycetemcomitans and lower serum IL-10 levels could be detected in homozygous ATA/ATA carriers. These findings indicate that variants in IL-10 promoter gene were not only associated with predisposition to chronic periodontitis but also affected the subgingival number of A. Actinomycetemcomitans in a Chinese Han population.

Periodontal Infectogenomics

Periodontal diseases are chronic infectious disease in which the pathogenic bacteria initiate the host immune response leading to the destruction of tooth supporting tissue and eventually result in the tooth loss. It has multifactorial etiological factors including local, systemic, environmental and genetic factors. The effect of genetic factors on periodontal disease is already under extensive research and has explained the role of polymorphisms of immune mediators affecting disease response. The role genetic factors in pathogens colonisation is emerged as a new field of research as "infectogenomics". It is a rapidly evolving and high-priority research area now days. It further elaborates the role of genetic factors in disease pathogenesis and help in the treatment, control and early prevention of infection. The aim of this review is to summarise the contemporary evidence available in the field of periodontal infectogenomics to draw some valuable conclusions to further elaborate its role in disease pathogenesis and its application in the clinical practice. This will open up opportunity for more extensive research in this field.

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.

Interleukin polymorphisms in aggressive periodontitis: A literature review

Aggressive periodontitis (AgP), occurs in a younger age group (≤35 years) and is associated with the rapid destruction of periodontal attachment and supporting bone. Genetic polymorphisms are allelic variants that occur in at least 1% of the population that could potentially alter the function of the proteins that they encode. Interleukins are a group of cytokines that have complex immunological functions including proliferation, migration, growth and differentiation of cells and play a key role in the immunopathogenesis of periodontal disease. The aim of this review was to summarize the findings of studies that reported associations or potential associations of polymorphisms in the interleukin family of cytokines, specifically with AgP.

Pathogen levels and clinical response to periodontal treatment in patients with Interleukin 8 haplotypes

The aim of this study was to investigate the effect of non-surgical treatment of periodontitis on the levels of periodontopathogens and clinical parameters in patients with different genetic backgrounds produced by polymorphisms in the Interleukin ( IL8) gene. Thirty patients grouped according to IL8 ATC/TTC or AGT/TTC haplotypes were submitted to non-surgical periodontal treatment. Levels of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were determined in 240 subgingival plaque samples by qPCR. The association between IL8 haplotypes and the levels of periodontopathogens and clinical parameters was investigated by multilevel analysis accounting for the clustering of diseased sites analyzed within patients. It was observed that neither levels of periodontopathogens nor non-surgical treatment was associated with the IL8 haplotype. The clinical parameters after periodontal treatment were similar in diseased and healthy sites, independently of the IL8 haplotype. Nonetheless, in the same period, diseased sites of AGT/TTC patients harbored higher levels of P. gingivalis, T. denticola, T. forsythia, and red complex than those of ATC/TTC patients. However, the non-surgical periodontal therapy decreased the levels of these periodontopathogens and of the tested clinical parameters of diseased sites in both groups. Non-surgical therapy is equally effective in improving clinical parameters and decreasing the levels of periodontopathogens, independent of the genotype groups produced by the IL8 haplotype.

Interleukin-10 gene promoter polymorphisms are associated with cyclosporin A-induced gingival overgrowth in renal transplant patients

OBJECTIVE

Interleukin-10 (IL-10) is an anti-inflammatory cytokine whose genetic polymorphisms are associated with the production of IL-10 and the susceptibility to periodontal diseases. The aim of this study was to investigate the possible association of IL-10 single nucleotide polymorphisms (SNPs) and cyclosporin A (CsA)-induced gingival overgrowth (GO) in renal transplant patients in a Chinese population, taking into account subgingival microbiota as additional variables.

MATERIAL AND METHODS

A total of 202 patients were dichotomized into two groups: 122 with GO and 80 without GO. The IL-10-1082 SNP, -819 SNP and -592 SNP were measured using an allele-specific PCR method. The levels of subgingival bacteria were measured by real-time PCR. Genotype and allele frequencies were analyzed using the Chi-square test and logistic regression analysis.

RESULTS

The frequency of IL-10-819TT (-592AA) genotype was statistically higher in patients with GO than that in patients without GO (P<0.05). Multiple logistic regression analysis demonstrated that the prevalence of GO is not dependent on age, gender, and pharmacological variables, being significantly associated with the carriers of ATA haplotype (OR=2.425, 95%CI=1.214-4.845, P=0.012). Moreover, ATA positive carriers in the GO group presented significantly higher levels of Porphyromonas gingivalis and Treponema denticola than those negative carriers.

CONCLUSIONS

Our results show that IL-10-819TT (-592AA) genotype and ATA halpotype are associated with susceptibility to CsA-induced GO. Meanwhile, ATA haplotype is associated with a higher detection of P. gingivalis and T. denticola in GO patients, and may increase the risk of developing GO.