Interleukin-6 polymorphisms are associated with pathogenic bacteria in subjects with periodontitis

Association of Gum Treatment with Cognitive Decline and Dementia Risk among Older Adults with Periodontal Symptoms: A 12-Year Prospective Cohort Study

INTRODUCTION

This study examines the associations of gum treatment with cognitive decline and dementia risk among older adults with periodontal symptoms in the USA.

METHODS

A cohort of 866 adults aged ≥50 with periodontal symptoms was recruited for the 2008 Health and Retirement Study "Dental Health Experimental Module" and followed until 2020. Cognitive function was assessed with the Telephone Interview for Cognitive Status (TICS). Dementia status was ascertained with the Langa-Weir algorithm based on TICS scores and proxy assessments. Linear mixed-effects model and multivariable Cox regression models were utilized to analyze the associations of gum treatment with cognitive decline and the risk of dementia, respectively.

RESULTS

Of 866 participants (mean age 67.7, 61.4% women), 105 (12.1%) developed dementia with a median follow-up of 9 (IQR, 6-10) years. The dementia incidence rates were lower in the group with gum treatment (7.4 vs. 12.9 per 1,000 person-years). Compared with participants who did not have gum treatment, those with gum treatment experienced a decline in TICS score that was on average 0.025 (95% CI, 0.005-0.044) points less per year and a 38% lower incidence of dementia (hazard ratio, 0.62; 95% CI, 0.41-0.93). These associations were consistent across participants with a different severity of periodontal symptoms and sociodemographic characteristics (age, sex, race, ethnicity, and education) except for income levels.

CONCLUSION

Prompt gum treatment for older adults with periodontal symptoms may be beneficial for their cognitive health.

Genomic Medicine in Canine Periodontal Disease: A Systematic Review

Genomic medicine has become a growing reality; however, it is still taking its first steps in veterinary medicine. Through this approach, it will be possible to trace the genetic profile of a given individual and thus know their susceptibility to certain diseases, namely periodontal disease. This condition is one of the most frequently diagnosed in companion animal clinics, especially in dogs. Due to the limited existing information and the lack of comprehensive studies, the objective of the present study was to systematically review the existing scientific literature regarding genomic medicine in canine periodontal disease and determine which genes have already been studied and their probable potential. This study followed the recommendations of the PRISMA 2020 methodology. Canine periodontal disease allied to genomic medicine were the subjects of this systematic review. Only six articles met all of the inclusion criteria, and these were analyzed in detail. These studies described genetic variations in the following genes: interleukin-6, interleukin-10, interleukin-1, lactotransferrin, toll-like receptor 9, and receptor activator of nuclear factor-kappa B. Only in two of them, namely interleukin-1 and toll-like receptor 9 genes, may the identified genetic variations explain the susceptibility that certain individuals have to the development of periodontal disease. It is necessary to expand the studies on the existing polymorphic variations in genes and their relationship with the development of periodontal disease. Only then will it be possible to fully understand the biological mechanisms that are involved in this disease and that determine the susceptibility to its development.

Loss of Interleukin-6 Influences Transcriptional Immune Signatures and Alters Bacterial Colonization in the Skin

The skin functions as a protective barrier to inhibit the entry of foreign pathogens, all the while hosting a diverse milieu of microorganisms. Over time, skin cells, immune cells, cytokines, and microbes interact to integrate the processes of maintaining the skin's physical and immune barrier. In the present study, the basal expression of two immunologically divergent mouse strains C57BL/6 and BALB/c, as well as a strain on the C57 background lacking IL-6, was characterized. Additionally, cutaneous antimicrobial gene expression profiles and skin bacterial microbiome were assessed between strains. Total RNA sequencing was performed on untreated C57BL/6 (control), BALB/c, and IL-6-deficient skin samples and found over 3,400 genes differentially modulated between strains. It was found that each strain modulated its own transcriptional "profile" associated with skin homeostasis and also influenced the overall bacterial colonization as indicated by the differential phyla present on each strain. Together, these data not only provide a comprehensive view of the transcriptional changes in homeostatic skin of different mouse strains but also highlight the possible influence of the strain differences (e.g., Th1/Th2 balance) as well as a role for IL-6 in overall skin immunity and resident microbial populations.

Genomics of periodontal disease and tooth morbidity

In this review we critically summarize the evidence base and the progress to date regarding the genomic basis of periodontal disease and tooth morbidity (ie, dental caries and tooth loss), and discuss future applications and research directions in the context of precision oral health and care. Evidence for these oral/dental traits from genome-wide association studies first emerged less than a decade ago. Basic and translational research activities in this domain are now under way by multiple groups around the world. Key departure points in the oral health genomics discourse are: (a) some heritable variation exists for periodontal and dental diseases; (b) the environmental component (eg, social determinants of health and behavioral risk factors) has a major influence on the population distribution but probably interacts with factors of innate susceptibility at the person-level; (c) sizeable, multi-ethnic, well-characterized samples or cohorts with high-quality measures on oral health outcomes and genomics information are required to make decisive discoveries; (d) challenges remain in the measurement of oral health and disease, with current periodontitis and dental caries traits capturing only a part of the health-disease continuum, and are little or not informed by the underlying biology; (e) the substantial individual heterogeneity that exists in the clinical presentation and lifetime trajectory of oral disease can be identified and leveraged in a precision medicine framework or, if unappreciated, can hamper translational efforts. In this review we discuss how composite or biologically informed traits may offer improvements over clinically defined ones for the genomic interrogation of oral diseases. We demonstrate the utility of the results of genome-wide association studies for the development and testing of a genetic risk score for severe periodontitis. We conclude that exciting opportunities lie ahead for improvements in the oral health of individual patients and populations via advances in our understanding of the genomic basis of oral health and disease. The pace of new discoveries and their equitable translation to practice will largely depend on investments in the education and training of the oral health care workforce, basic and population research, and sustained collaborative efforts..

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.

Genetic Association with Subgingival Bacterial Colonization in Chronic Periodontitis

Chronic periodontitis is the most prevalent form of inflammatory destructive bone disease and has been affecting humans since antiquity. Evidence suggest that genetic factors can highly influence periodontitis risk, modulating disease elements such as the susceptibility to microbial colonization and the nature of subsequent host-microbe interaction. Several single-nucleotide polymorphisms (SNPs) have been associated with the occurrence of periodontitis, but the full range of genetic influence in periodontitis outcomes remains to be determined. In this context, this study comprises an analysis of possible correlation between periodontitis-related genetic variants with changes in the subgingival microbiological pattern performed in a Brazilian population (n = 167, comprising 76 chronic periodontitis patients and 91 healthy subjects). For the genetic characterization, 19 candidate SNPs were selected based on the top hits of previous large genome wide association studies (GWAS), while the subgingival microbiota was characterized for the presence and relative quantity of 40 bacterial species by DNA-DNA checkerboard. The case/control association test did not demonstrate a significant effect of the target SNPs with the disease phenotype. The polymorphism rs2521634 proved significantly associated with Tannerella forsythia, Actinomyces gerencseriae, Fusobacterium periodonticum, and Prevotella nigrescens; rs10010758 and rs6667202 were associated with increased counts of Porphyromonas gingivalis; and rs10043775 proved significantly associated with decreased counts of Prevotella intermedia. In conclusion, we present strong evidence supporting a direct connection between the host’s genetic profile, specifically rs2521634, rs10010758, rs6667202, and rs10043775 polymorphisms, and the occurrence of chronic periodontitis-associated bacteria.

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 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.

Interleukin-17A Gene Variability in Patients with Type 1 Diabetes Mellitus and Chronic Periodontitis: Its Correlation with IL-17 Levels and the Occurrence of Periodontopathic Bacteria

Interleukin-17 contributes to the pathogenesis of type 1 diabetes mellitus (T1DM) and chronic periodontitis (CP). We analyzed IL-17A -197A/G and IL-17F +7488C/T polymorphisms in T1DM and CP and determined their associations with IL-17 production and occurrence of periopathogens. Totally 154 controls, 125 T1DM, and 244 CP patients were genotyped using 5' nuclease TaqMan(®) assays. Bacterial colonization was investigated by a DNA-microarray kit. Production of IL-17 after in vitro stimulation of mononuclear cells by mitogens and bacteria was examined by the Luminex system. Although no differences in the allele/genotype frequencies between patients with CP and T1DM + CP were found, the IL-17A -197 A allele increased the risk of T1DM (P < 0.05). Levels of HbA1c were significantly elevated in carriers of the A allele in T1DM patients (P < 0.05). Production of IL-17 by mononuclear cells of CP patients (unstimulated/stimulated by Porphyromonas gingivalis) was associated with IL-17A A allele (P < 0.05). IL-17A polymorphism increased the number of Tannerella forsythia and Treponema denticola in patients with CP and T1DM + CP, respectively (P < 0.05). IL-17A gene variability may influence control of T1DM and the "red complex" bacteria occurrence in patients with CP and T1DM + CP. Our findings demonstrated the functional relevance of the IL-17A polymorphism with higher IL-17 secretion in individuals with A allele.

Periodontal microbiota and phospholipases: the Oral Infections and Vascular Disease Epidemiology Study (INVEST)

OBJECTIVE

Periodontal infections have been linked to cardiovascular disease, including atherosclerosis, and systemic inflammation has been proposed as a possible mediator. Secretory phospholipase A2 (s-PLA2) and Lipoprotein-associated PLA2 (Lp-PLA2) are inflammatory enzymes associated with atherosclerosis. No data are available on the association between oral microbiota and PLA2s. We studied whether a relationship exists between periodontal microbiota and the activities of these enzymes.

METHODS

The Oral Infection and Vascular Disease Epidemiology Study (INVEST) collected subgingival biofilms and serum samples from 593 dentate men and women (age 68.7 ± 8.6 years). 4561 biofilm samples were collected in the two most posterior teeth of each quadrant (average 7/participant) for quantitative assessment of 11 bacterial species using DNA-DNA checkerboard hybridization. Mean concentration of s-PLA2 and activities of s-PLA2 and Lp-PLA2 were regressed on tertiles of etiologic dominance (ED). ED is defined as the level of presumed periodontopathic species/combined level of all eleven species measured, and represents the relative abundance of periodontopathic organisms. Analyses were adjusted for age, sex, race/ethnicity, education, smoking, BMI, diabetes, LDL cholesterol and HDL cholesterol, and systolic blood pressure.

RESULTS

Higher levels of s-PLA2 activity were observed across increasing tertiles of etiologic dominance (0.66 ± 0.04 nmol ml(-1) min(-1), 0.73 ± 0.04 nmol ml(-1) min(-1), 0.89 ± 0.04 nmol ml-1 min-1; p < 0.001), with also a trend of association between Lp-PLA2 activity and ED (p = 0.07), while s-PLA2 concentration was unrelated to ED.

CONCLUSION

Increasingly greater s-PLA2 activity at higher tertiles of etiologic dominance may provide a mechanistic explanatory link of the relationship between periodontal microbiota and vascular diseases. Additional studies investigating the role of s-PLA2 are needed.

Oral administration of 5-hydroxytryptophan aggravated periodontitis-induced alveolar bone loss in rats

OBJECTIVE

5-Hydroxytryptophan (5-HTP) is the precursor of serotonin and 5-HTP has been widely used as a dietary supplement to raise serotonin level. Serotonin has recently been discovered to be a novel and important player in bone metabolism. As peripheral serotonin negatively regulates bone, the regular take of 5-HTP may affect the alveolar bone metabolism and therefore influence the alveolar bone loss induced by periodontitis. The aim of this study was to investigate the effect of 5-HTP on alveolar bone destruction in periodontitis.

DESIGN

Male Sprague-Dawley rats were randomly divided into the following four groups: (1) the control group (without ligature); (2) the 5-HTP group (5-HTP at 25 mg/kg/day without ligature); (3) the L group (ligature+saline placebo); and (4) the L+5-HTP group (ligature+5-HTP at 25 mg/kg/day). Serum serotonin levels were determined by ELISA. The alveolar bones were evaluated with micro-computed tomography and histology. Tartrate-resistant acid phosphatase staining was used to assess osteoclastogenesis. The receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG) expression in the periodontium as well as the interleukin-6 positive osteocytes were analysed immunohistochemically.

RESULTS

5-HTP significantly increased serum serotonin levels. In rats with experimental periodontitis, 5-HTP increased alveolar bone resorption and worsened the micro-structural destruction of the alveolar bone. 5-HTP also stimulated osteoclastogenesis and increased RANKL/OPG ratio and the number of IL-6 positive osteocytes. However, 5-HTP treatment alone did not cause alveolar bone loss in healthy rats.

CONCLUSION

The present study showed that 5-HTP aggravated alveolar bone loss, deteriorated alveolar bone micro-structure in the presence of periodontitis, which suggests 5-HTP administration may increase the severity of periodontitis.

Genetic dysbiosis: the role of microbial insults in chronic inflammatory diseases

Thousands of bacterial phylotypes colonise the human body and the host response to this bacterial challenge greatly influences our state of health or disease. The concept of infectogenomics highlights the importance of host genetic factors in determining the composition of human microbial biofilms and the response to this microbial challenge. We hereby introduce the term ‘genetic dysbiosis’ to highlight the role of human genetic variants affecting microbial recognition and host response in creating an environment conducive to changes in the normal microbiota. Such changes can, in turn, predispose to, and influence, diseases such as: cancer, inflammatory bowel disease, rheumatoid arthritis, psoriasis, bacterial vaginosis and periodontitis. This review presents the state of the evidence on host genetic factors affecting dysbiosis and microbial misrecognition (i.e. an aberrant response to the normal microbiota) and highlights the need for further research in this area.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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

Haplotype analysis of interleukin-8 gene polymorphisms in chronic and aggressive periodontitis

Objectives. Periodontitis is an inflammatory disease characterized by connective tissue loss and alveolar bone destruction. Interleukin-8 (IL8) is important in the regulation of the immune response. The aim of this study was to analyze four polymorphisms in the IL8 gene in relation to chronic (CP) and aggressive (AgP) periodontitis. Methods. A total of 492 unrelated subjects were included in this case-control association study. Genomic DNA of 278 patients with CP, 58 patients with AgP, and 156 controls were genotyped, using the 5′ nuclease TaqMan assay, for IL8 (rs4073, rs2227307, rs2227306, and rs2227532) gene polymorphisms. Subgingival bacterial colonization was investigated by the DNA-microarray detection kit in a subgroup of subjects (N = 247). Results. Allele and genotype frequencies of all investigated IL8 polymorphisms were not significantly different between the subjects with CP and/or AgP and controls (P > 0.05). Nevertheless, the A(−251)/T(+396)/T(+781) and T(−251)/G(+396)/C(+781) haplotypes were significantly less frequent in patients with CP (2.0% versus 5.1%, P < 0.02, OR = 0.34, 95% CI: 0.15–0.78, resp., 2.0% versus 4.5%, P < 0.05, OR = 0.41, 95% CI: 0.18–0.97) than in controls. Conclusions. Although none of the investigated SNPs in the IL8 gene was individually associated with periodontitis, some haplotypes can be protective against CP in the Czech population.

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.

Periodontopathogens levels and clinical response to periodontal therapy in individuals with the interleukin-4 haplotype associated with susceptibility to chronic periodontitis

Periodontitis is an inflammatory disease that results from an interaction between dental biofilm agents and the host immune-inflammatory response. Periodontopathogenic organisms, such as Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, as well as the host's susceptibility, represented by the host's genetic makeup, are the key factors that influence this complex disease. Recently, we identified haplotypes in the IL4 gene that were associated with chronic periodontitis (CP). This study aimed to evaluate whether subjects with different IL4 haplotypes (TCI/CCI and TTD/CTI) would be differentially colonized by periodontopathogens and whether they would respond differently to non-surgical periodontal therapy. Thirty-nine patients carrying the IL4 haplotype of genetic susceptibility to CP (IL4+) or protection against CP (IL4-) were evaluated. Those groups were further subdivided into individuals with CP (CP IL4+ or CP IL4-) and those that were periodontally healthy (H) (H IL4+ or H IL4-). CP patients were submitted to non-surgical periodontal therapy. Clinical and microbiological analyses were performed considering the data at baseline and 45 and 90 days after periodontal therapy. Periodontopathogens levels were evaluated by absolute quantitative polymerase chain reaction (qPCR). The baseline data revealed that the total levels of periodontopathogens were higher in the CP IL4+ than in the CP IL4- groups. Clinical analyses revealed that the periodontal therapy was equally effective, independent of the subject's IL4 genetic load. The TCI/CCI IL4 haplotype, previously associated with genetic susceptibility to CP, was also associated with increased levels of periodontopathogenic bacteria, but this genetic background did not influence the response to non-surgical periodontal treatment.

Association between IL8 haplotypes and pathogen levels in chronic periodontitis

Chronic periodontitis (CP) is considered to be a multifactorial disease influenced by microbial and genetic factors. The aim of the present study was to investigate whether the genetic susceptibility to CP in individuals with the IL8 ATC/TTC haplotype is associated with subgingival levels of periodontopathogens. Sixty-five individuals, grouped according to the presence (n = 28) or absence (n = 37) of the IL8 haplotype, were evaluated. After clinical periodontal evaluation, each group was subdivided according to the presence (CP) or absence (H) of periodontitis. Four subgingival samples were obtained from CP and two samples per subject from H patients. The levels and proportions of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were analyzed using quantitative real-time polymerase chain reaction (q-PCR). No differences were found in the proportion of periodontopathogenic bacteria between groups with the presence or absence of the IL8 haplotype. However, in the CP groups, the levels of periodontopathogens were significantly higher in the individuals without the IL8 haplotype than in the individuals with the IL8 haplotype. These results suggest that periodontal destruction may occur in patients who are considered to be genetically susceptible to CP with a lower microbial challenge because of the presence of the IL8 ATC/TTC haplotype than in patients without this 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.

Microbial sampling process can change results of microbiological analysis in periodontitis diagnosis. A minireview

This minireview aims to verify the supposition that the microbial sampling process can change results of microbiological analysis in periodontitis diagnosis. The literature search via Pubmed yielded 52 appropriate articles for analysis. Of which 38% (20/52) described that the sampling sites were isolated from saliva, whereas 62% (32/52) did not. Also, 29% (15/52) declared that the microbial sampling was performed before probing pocket depth (PPD), whereas 71% (37/52) did not. Comparison of the results of microbiological analysis in these studies showed that the bacteria most frequently detected in periodontal pockets was variable. Therefore, a sampling process that includes both the microbial sample being taken before PPD and saliva isolation of the sampling sites is needed to ensure the accuracy of microbiological analysis in periodontitis diagnosis.

Association of CD14-260 polymorphisms, red-complex periodontopathogens and gingival crevicular fluid cytokine levels with cyclosporine A-induced gingival overgrowth in renal transplant patients

BACKGROUD AND OBJECTIVE: Genetic factors may influence the colonization of pathogenic bacteria, therefore increasing the risk for the initiation and development of periodontal disease. The present study was carried out to investigate the association of CD14-260 polymorphisms, subgingival microbiota, and gingival crevicular fluid (GCF) cytokine levels with cyclosporine A (CsA)-induced gingival overgrowth (GO) in renal transplant patients.

MATERIAL AND METHODS

A total of 204 patients were dichotomized into two groups: 124 with GO and 80 without GO. The CD14-260 polymorphisms were measured using an allele-specific PCR method. The levels of periodontal pathogens were determined by real-time PCR of subgingival samples. GCF levels of IL-1β and sCD14 were detected by ELISA.

RESULTS

The frequency of CD14-260 genotype CT + TT was found to be similar in both groups. Patients with GO presented increased prevalence of Pg, Td, and Tf (red complex) and significantly higher levels of interleukin -1β than those without GO. Patients with GO carrying CT + TT genotypes were found to have higher frequencies of Pg, Td, and Tf than those carrying the CC genotype. Furthermore, in the presence of red complex, CT + TT genotypes were associated with higher interleukin -1β levels and severe GO. Multiple logistic regression analysis demonstrated that the severity of GO is not dependent on age, gender and pharmacological variables, being only associated with CD14-260 genotype and red complex periodontopathogens.

CONCLUSION

No association between CD14-260 polymorphisms and the prevalence of GO was revealed in renal transplant patients administered CsA. However, CD14-260 CT + TT genotypes are associated with the prevalence of red complex periodontopathogens in patients with GO, and may thus play some role in the development of severe CsA-induced GO.

Influence of IL-6 haplotypes on clinical and inflammatory response in aggressive periodontitis

OBJECTIVES

The aim of this study was to investigate the inflammatory response in aggressive periodontitis (AgP) patients after periodontal therapy and associate these changes to subjects' interleukin-6 (IL-6) genetic variants.

MATERIALS AND METHODS

Twelve non-smoking UK Caucasian patients with AgP were selected based on their IL6 haplotypes (six haplotype positive and six haplotype negative based on polymorphisms rs 2069827 and rs 2069825) and underwent full mouth non-surgical periodontal therapy, followed by open flap surgery. Gingival crevicular fluid (GCF) and peripheral blood samples were taken at baseline and at six different time points after treatment. Gingival biopsy samples were harvested during surgery and underwent immunohistochemical analysis for identification of IL-6.

RESULTS

An overall improvement in clinical periodontal parameters was observed following periodontal therapy. Haplotype status was associated with clinical presentation, Aggregatibacter actinomycetemcomitans counts in subgingival plaque samples, white cell count, neutrophils, red cell count and haemoglobin. GCF IL-6 concentrations increased dramatically 1 day after surgery and IL-6 haplotype-positive subjects exhibited a higher magnitude in this increase.

CONCLUSIONS

IL6 haplotypes may have an effect on clinical presentation and magnitude and kinetics of local and systemic inflammatory responses following non-surgical and surgical periodontal therapy in aggressive periodontitis.

CLINICAL RELEVANCE

Detecting IL-6 haplotype-positive periodontitis patients might become helpful in identifying subjects prone to excessive inflammatory response and increased periodontal breakdown.

Interleukin-6 gene promoter methylation in rheumatoid arthritis and chronic periodontitis

BACKGROUND

Methylation status of the cytokine genes may play a role in the pathogenesis of inflammatory diseases, such as rheumatoid arthritis (RA) and chronic periodontitis (CP). This study was undertaken to evaluate whether the DNA methylation profile of the interleukin-6 (IL-6) gene promoter was unique to individuals with RA and CP.

METHODS

The study participants consisted of 30 patients with RA, 30 patients with CP, and 30 age-, sex-, and smoking status-balanced healthy controls. Genomic DNA isolated from peripheral blood was modified by sodium bisulfite and analyzed for DNA methylation levels of IL-6 gene with direct sequencing. Levels of IL-6 were determined by an enzyme-linked immunosorbent assay.

RESULTS

The region of IL-6 gene promoter from -1200 to +27 bp was shown to contain 19 CpG motifs. The methylation levels of the CpG motif at -74 bp were significantly lower in patients with RA and CP than those in controls (P = 0.0001). Both levels of serum IL-6 and IL-6 production by mononuclear cells were significantly different between individuals with and without the methylation at -74 bp (P = 0.03). The +19 bp motif exhibited differential levels of the methylation among the groups, which was not associated with serum levels of IL-6. The other 17 CpG motifs exhibited comparable levels of the methylation between the groups.

CONCLUSION

These results suggest that hypomethylated status of a single CpG in the IL-6 promoter region may lead to increased levels of serum IL-6, implicating a role in the pathogenesis of RA and CP.

What can we learn about biofilm/host interactions from the study of inflammatory bowel disease

OBJECTIVES

The aim of this review was to evaluate possible common pathogenic pathways and risk factors in inflammatory bowel disease (IBD) and periodontitis.

MATERIALS AND METHODS

A MEDLINE-PubMed research was conducted.

RESULTS

The pathogenesis of both diseases is multi-factorial leading to a substantial defect of the mucosal barrier, deregulation of the immune response and chronic inflammation of the mucosa. Environmental factors, particularly bacteria, are key factors in the pathogenesis of both diseases. Genetic predisposition is a key factor in the IBD pathogenesis, while a clear role of genetics in the pathogenesis of periodontitis is still unclear. The immune response in IBD is mediated by T lymphocytes as a consequence of a genetic trait associated with T-cell deregulation. On the other hand, in periodontitis plasma cells and lymphocytes are the predominant cells in the chronic inflammatory lesion, with the presence of B cells being proportionally larger than T cells.

CONCLUSION

IBD and periodontitis share several factors in their aetiology and pathogenesis, although they also have distinct characteristics.

Systemic inflammatory responses in progressing periodontitis during pregnancy in a baboon model

This study tested the hypothesis that pregnant female baboons exhibit increased levels of various inflammatory mediators in serum resulting from ligature-induced periodontitis, and that these profiles would relate to periodontal disease severity/extent in the animals. The animals were sampled at baseline (B), mid-pregnancy (MP; two quadrants ligated) and at delivery (D; four quadrants ligated). All baboons developed increased plaque, gingival inflammation and bleeding, pocket depths and attachment loss following placement of the ligatures. By MP, both prostaglandin E(2) (PGE(2)) and bactericidal permeability inducing factor (BPI) were greater than baseline, while increased levels of interleukin (IL)-6 occurred in the experimental animals by the time of delivery. IL-8, MCP-1 and LBP all decreased from baseline through the ligation phase of the study. Stratification of the animals by baseline clinical presentation demonstrated that PGE(2), LBP, IL-8 and MCP-1 levels were altered throughout the ligation interval, irrespective of baseline clinical values. IL-6, IL-8 and LBP were significantly lower in the subset of animals that demonstrated the least clinical response to ligation, indicative of progressing periodontal disease. PGE(2), macrophage chemotactic protein (MCP)-1, regulated upon activation, normal T cell expressed and secreted (RANTES) and LBP were decreased in the most diseased subset of animals at delivery. Systemic antibody responses to Fusobacterium nucleatum, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Campylobacter rectus were associated most frequently with variations in inflammatory mediator levels. These results provide a profile of systemic inflammatory mediators during ligature-induced periodontitis in pregnant baboons. The relationship of the oral clinical parameters to systemic inflammatory responses is consistent with a contribution to adverse pregnancy outcomes in a subset of the animals.

IL6 -174 genotype associated with Aggregatibacter actinomycetemcomitans in Indians

AIM

Genetic factors have recently been associated with presence of Aggregatibacter actinomycetemcomitans subgingivally in populations living in industrialized countries. The aim of this study was to analyse associations between Interleukin-6 (IL6) single nucleotide polymorphisms and presence and levels of A. actinomycetemcomitans and other subgingival microbes in a rural Indian population.

SUBJECTS AND METHODS

 A total of 251 individuals from a rural village in India with a periodontal phenotype ranging from healthy to severe periodontitis were included. Checkerboard DNA-DNA analysis was performed to detect 40 periodontal taxa in subgingival plaque samples. Genomic DNA was extracted to genotype five polymorphisms in the IL6 promoter region.

RESULTS

The IL6-74 GG genotype was associated with high (above median) counts of A. actinomycetemcomitans (both in all subjects and in periodontally healthy only) and with presence and counts of Capnocytophaga sputigena. Differences in detection of several other bacteria were noted between periodontitis and healthy subjects.

CONCLUSIONS

These findings support the influence of genetic factors on the subgingival microbiota.

Destructive and protective roles of cytokines in periodontitis: a re-appraisal from host defense and tissue destruction viewpoints

Periodontal diseases (PD) are chronic infectious inflammatory diseases characterized by the destruction of tooth-supporting structures, being the presence of periodontopathogens required, but not sufficient, for disease development. As a general rule, host inflammatory mediators have been associated with tissue destruction, while anti-inflammatory mediators counteract and attenuate disease progression. With the discovery of several T-cell subsets bearing distinct immunoregulatory properties, this pro- vs. anti-inflammatory scenario became more complex, and a series of studies has hypothesized protective or destructive roles for Th1, Th2, Th17, and Treg subpopulations of polarized lymphocytes. Interestingly, the "protective vs. destructive" archetype is usually considered in a framework related to tissue destruction and disease progression. However, it is important to remember that periodontal diseases are infectious inflammatory conditions, and recent studies have demonstrated that cytokines (TNF-α and IFN-γ) considered harmful in the context of tissue destruction play important roles in the control of periodontal infection. Therefore, in this review, the state-of-the-art knowledge concerning the protective and destructive roles of host inflammatory immune response will be critically evaluated and discussed from the tissue destruction and control-of-infection viewpoints.

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.

Periodontal infectogenomics

Multicellular creatures consist of a symbiosis between the host and its colonizing bacteria. The oral cavity may contain as many as 19,000 bacterial phylotypes, while each individual presents a proportion of these microbes. Infectogenomics studies the interaction between host genetic variations and composition of the microbiota. This review introduces the concept of periodontal infectogenomics, defined as the relationship between host genetic factors and the composition of the subgingival microbiota. In particular, the evidence for the effect of genetic variants in neutrophil and cytokine genes and the presence of periodontopathogenic bacteria will be discussed. The influence of genetic factors may affect clearance or persistence of pathogenic bacteria subgingivally, therefore increasing the risk for the development of common pathogenic conditions such as gingivitis and periodontitis, leading to early tooth loss. Mechanisms of interaction between genetic and microbiological factors and prospects for future studies will be discussed.

An interleukin-1beta (IL-1beta) single-nucleotide polymorphism at position 3954 and red complex periodontopathogens independently and additively modulate the levels of IL-1beta in diseased periodontal tissues

Inflammatory cytokines such as interleukin-1beta (IL-1beta) are involved in the pathogenesis of periodontal diseases. A high individual variation in the levels of IL-1beta mRNA has been verified, which is possibly determined by genetic polymorphisms and/or by the presence of periodontopathogens such as Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Aggregatibacter actinomycetemcomitans. In this study, we investigated the role of an IL-1beta promoter single-nucleotide polymorphism at position 3954 [IL-1beta(3954) SNP] and the presence of the periodontopathogens in the determination of the IL-1beta levels in the periodontal tissues of nonsmoking chronic periodontitis (CP) patients (n = 117) and control (C) subjects (n = 175) and the possible correlations with the clinical parameters of the disease. IL-1beta(3954) SNP was investigated by restriction fragment length polymorphism, while the IL-1beta levels and the presence of the periodontopathogens were determined by real-time PCR. Similar frequencies of IL-1beta(3954) SNP were found in the C and CP groups, in spite of a trend toward a higher incidence of T alleles in the CP group. The IL-1beta(3954) SNP CT and TT genotypes, as well as P. gingivalis, T. forsythia, and T. denticola, were associated with higher IL-1beta levels and with higher values of the clinical parameters of disease severity. Concomitant analyses demonstrate that IL-1beta(3954) and the red complex periodontopathogens were found to independently and additively modulate the levels of IL-1beta in periodontal tissues. Similarly, the concurrent presence of both factors was associated with increased scores of disease severity. IL-1beta(3954) genotypes and red complex periodontopathogens, individually and additively, modulate the levels of IL-1beta in the diseased tissues of nonsmoking CP patients and, consequently, are potentially involved in the determination of the disease outcome.