Relevance of IgG receptor IIIb (CD16) polymorphism to handling of Porphyromonas gingivalis: implications for the pathogenesis of adult periodontitis

Impact of FCGR2A R131H, FCGR3A F158V and FCGR3B NA1/NA2 polymorphisms on response to fc-containing TNF inhibitors in Tunisian rheumatoid arthritis patients

OBJECTIVES

Single nucleotid polymorphisms (SNPs) of Fc-gamma receptors (FcgRs), by inducing a variation of their affinity to the Fc-region of immunoglobulins, might influence the efficacy of Fc-containing biologics prescribed in rheumatoid arthritis (RA). Our aim was to investigate associations of FCGR2A, FCGR3A and FCGR3B SNPs with TNF-inhibitors (TNFi)' response in Tunisian RA patients.

METHODS

A cross-sectional, observational and analytic multicentric cohort study was conducted in a group of 47 Tunisian RA patients treated with (etanercept [ETA], adalimumab [ADL] and infliximab [IFX]). Treatment outcome was evaluated after 6 months. R131H-FCGR2A, F158V-FCGR3A and NA1/NA2-FCGR3B SNPs were genotyped.

RESULTS

The analytic study including all types of TNFi showed that FCGR3A-F/F low-affinity receptor was associated with a greater decrease of DAS28, while FCGR3B-NA1/NA1 high-affinity receptor was associated with a lower decrease of DAS28 in ADL group. Furthermore, both of high affinity receptors FCGR3B-NA1/NA1 and FCGR3A-V/V were more prevalent in non-responders to ADL, according to EULAR criteria.

CONCLUSIONS

Identifying reliable biomarkers of response to biologics in RA is necessary to improve responsiveness, preserve joints' functions and structure, and reduce treatment's cost. Our study showed that FCGR3A and FCGR3B polymorphisms might have an impact on TNFis' response in RA Tunisian patients since bad response was more frequent in homozygous carriers of high affinity alleles FCGR3A-V and FCGR3B-NA1.

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.

Neutrophil Subsets in Periodontal Health and Disease: A Mini Review

Neutrophils are amongst the most abundant immune cells within the periodontal tissues and oral cavity. As innate immune cells, they are first line defenders at the tooth-mucosa interface, and can perform an array of different functions. With regard to these, it has been observed over many years that neutrophils are highly heterogeneous in their behavior. Therefore, it has been speculated that neutrophils, similarly to other leukocytes, exist in distinct subsets. Several studies have investigated different markers of neutrophils in oral health and disease in recent years in order to define potential cell subsets and their specific tasks. This research was inspired by recent advancements in other fields of medicine in this field. The aim of this review is to give an overview of the current evidence regarding the existence and presence of neutrophil subsets and their possible functions, specifically in the context of periodontitis, gingivitis, and periodontal health.

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.

Human FcR polymorphism and disease

Fc receptors play a central role in maintaining the homeostatic balance in the immune system. Our knowledge of the structure and function of these receptors and their naturally occurring polymorphisms, including single nucleotide polymorphisms and/or copy number variations, continues to expand. Through studies of their impact on human biology and clinical phenotype, the contributions of these variants to the pathogenesis, progression, and/or treatment outcome of many diseases that involve immunoglobulin have become evident. They affect susceptibility to bacterial and viral pathogens, constitute as risk factors for IgG or IgE mediated inflammatory diseases, and impact the development of many autoimmune conditions. In this chapter, we will provide an overview of these genetic variations in classical FcγRs, FcRLs, and other Fc receptors, as well as challenges in achieving an accurate and comprehensive understanding of the FcR polymorphisms and genomic architecture.

Associations between FCGR2A rs1801274, FCGR3A rs396991, FCGR3B NA1/NA2 polymorphisms and periodontitis: a meta-analysis

The aim of this study was to determine whether the Fcγ receptors (FCGRs) polymorphisms confer susceptibility to periodontitis in ethnically different populations. We did a literature search using PubMed and Embase, and conducted a meta-analysis on the associations between the FCGR2A H131R (rs1801274), FCGR3A F158V (rs396991), and FCGR3B NA1/NA2 polymorphisms and periodontitis using allele contrast, the recessive model, the dominant model, and the homozygote contrast. A total of 17 separate comparisons with 1,421 patients with periodontitis and 1,454 controls, involving six Caucasian, six East Asian, two African and one South Asian population were considered in the meta-analysis. Meta-analysis of the FCGR2A H131R polymorphism showed no association between periodontitis and the FCGR2A R allele (OR=0.987, 95% CI=0.881-1.107, p=0.827). Stratification by ethnicity revealed an association between the RR+RH genotype with periodontitis in Caucasian population (OR=0.624, 95% CI=0.479-0.813, p=4.7×10(-5)), but not in East Asian, and African populations. Meta-analysis of the FCGR3A F158V polymorphism revealed an association between the FCGR3A V allele and periodontitis is in Caucasians (OR=1.457, 95% CI=1.014-2.092, p=0.042), but not in East Asians and Africans. In addition, analysis using the dominant model and homozygote contrast showed the same pattern for the FCGR3A V allele. Meta-analysis of the FCGR3B NA1/NA2 polymorphism using the recessive model revealed a significant association between the NA2/NA2 genotype and periodontitis in aggressive periodontitis (OR=2.853, 95% CI=1.673-4.863, 1.1×10(-5)). This meta-analysis demonstrates that the FCGR2A, and FCGR3A polymorphisms may confer susceptibility to periodontitis in Caucasians, and that the FCGR3B polymorphism may be associated with susceptibility to aggressive periodontitis.

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.

Association of the FcγRIIB-nt645+25A/G polymorphism with the expression level of the FcγRIIb receptor, the antibody response to Porphyromonas gingivalis and the severity of periodontitis

BACKGROUND AND OBJECTIVE

Human FcγRIIb is an immunoglobulin G (IgG) receptor that inhibits the activation of B lymphocytes through cross-linking with the B-cell receptor via immune complexes. This function acts as a negative regulator of antibody production. Our previous studies have demonstrated the gene polymorphisms in FcγRIIb to be associated with periodontitis. In this study, we presented a polymorphism--FcγRIIB-nt645+25A/G (rs2125685)--in intron 4 and analyzed its functional relevance to periodontitis. We examined whether the FcγRIIB-nt645+25A/G polymorphism is associated with periodontal parameters, the IgG response to the periodontopathic bacterium Porphyromonas gingivalis and/or the expression level of FcγRIIb on peripheral B lymphocytes.

MATERIAL AND METHODS

Thirty-two patients with chronic periodontitis were genotyped with nested PCR and by direct sequencing of genome DNA. The levels of serum IgG and of specific IgG subclasses for P. gingivalis sonicate and for the recombinant 40-kDa outer membrane protein (OMP) were determined. The expression levels of FcγRIIb on peripheral B lymphocytes from 19 healthy donors were measured by flow cytometry.

RESULTS

Patients with the FcγRIIB-nt645+25AA genotype showed significantly higher mean clinical attachment levels compared to patients with the FcγRIIB-nt645+25GG genotype (p = 0.003) and a significantly lower IgG response to P. gingivalis sonicate and to the 40-kDa OMP. The expression levels of FcγRIIb protein on the cell surface in peripheral B lymphocytes were higher in healthy donors with the FcγRIIB-nt645+25AA genotype than in those with the FcγRIIB-nt645+25GG genotype (p = 0.03).

CONCLUSION

The higher expression levels of FcγRIIb in subjects with the FcγRIIB-nt645+25AA genotype may induce a lower level of production of IgG against P. gingivalis and therefore more severe periodontitis.

Characterization of human-type monoclonal antibodies against reduced form of hemin binding protein 35 from Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

The gram-negative anaerobe Porphyromonas gingivalis has been implicated as an important pathogen in the development of adult periodontitis, and its colonization of subgingival sites is critical in the pathogenic process. We previously identified a 35 kDa surface protein (hemin binding protein 35; HBP35) from P. gingivalis that exhibited coaggregation activity, while additional analysis suggested that this protein possessed an ability to bind heme molecules. For development of passive immunotherapy for periodontal diseases, human-type monoclonal antibodies have been prepared using HBP35 as an antigen in TransChromo mice. In the present study, we focused on a single antibody, TCmAb-h13, which is known to inhibit heme binding to recombinant HBP35. The aim of our investigation was to clarify the redox-related function of HBP35 and consider the benefits of human-type monoclonal antibodies.

MATERIAL AND METHODS

To examine the antigen recognition capability of TCmAbs with immunoblotting and Biacore techniques, we used the native form as well as several Cys-to-Ser variants of recombinant HBP35.

RESULTS

We found that the redox state of recombinant HBP35 was dependent on two Cys residues, (48) C and (51) C, in the thioredoxin active center (WCGxCx). Furthermore, TCmAb-h13 recognized the reduced forms of recombinant HBP35, indicating its inhibitory effect on P. gingivalis growth.

CONCLUSION

Hemin binding protein 35 appears to be an important molecule involved in recognition of the redox state of environmental conditions. In addition, TCmAb-h13 had an inhibitory effect on heme binding to recombinant HBP35, thereby interfering with P. gingivalis growth.

Fcgamma receptor polymorphisms and their association with periodontal disease: a meta-analysis

AIM

A systematic review and a meta-analysis were conducted in order to investigate the potential association of Fcgamma receptor (FcgammaR) polymorphisms with susceptibility to aggressive and chronic periodontal disease.

MATERIALS AND METHODS

A database search yielded a total of 17 studies involving 1685 cases and 1570 controls. Three polymorphisms were included in the meta-analysis: FcgammaRIIA H131R (rs1801274), FcgammaRIIIA F158V (rs396991) and FcgammaRIIIB NA1/NA2. Random-effect models were used in the analysis. Odds ratios (ORs) along with their 95% confidence intervals (CIs) were computed to compare the distribution of alleles and genotypes between cases and controls.

RESULTS AND CONCLUSIONS

The FcgammaRIIIB NA1/NA2 polymorphism was associated with both aggressive (per-allele OR 2.005, 95% CI: 1.044, 3.851) and chronic periodontitis (recessive contrast NA2NA2 versus NA1NA1+NA1NA2 OR 1.397, 95% CI: 1.039, 1.878). The analysis showed weak evidence for association between the FcgammaRIIA H131R polymorphism and aggressive periodontitis in Asians (R versus H allele OR 1.579, 95% CI: 1.025, 2.432). On the contrary, no relationship was identified between FcgammaRIIIA F158V and periodontal disease. Accumulating evidence from basic research makes the suggested association between FcgammaRIIIB NA1/NA2 polymorphism and periodontitis biologically plausible. Further research, however, is needed in order to assess possible gene-gene or gene-environment interactions (i.e. with smoking).

The association of Fcgamma receptor IIIb genetic polymorphism and susceptibility to periodontitis in Taiwanese individuals

AIM

The allelic polymorphism of FcgammaRIIIb, the neutrophil-specific receptor involved in the phagocytosis of immunoglobulin G-opsonized bacteria, has functionally distinct capacities that are important in host defence mediated by neutrophils. The aim of this study was to identify whether the polymorphism of FcgammaRIIIb is associated with periodontitis in Taiwanese individuals.

MATERIALS AND METHODS

This case-control study included of 93 aggressive periodontitis (AgP) patients, 372 chronic periodontitis (CP) patients and 158 healthy controls (HC). The FcgammaRIIIb genotypes were determined by PCR using allele-specific primers. The risk for periodontitis associated with genotypes was calculated as the odds ratio (OR).

RESULTS

A significant difference was observed in the distribution of the FcgammaRIIIb genotype between either AgP and HC, or AgP and CP, but not between CP and HC. The OR for carriage of the NA2 allele (NA1NA2+NA2NA2 versus NA1NA1) in AgP was 3.27 [95% confidence interval (CI)=1.57-7.51, p=0.0027] and 2.94 (95% CI=1.49-6.48, p=0.0037), as compared with HC and CP. After adjusting for possible confounding factors, the association was still significant.

CONCLUSIONS

The results of the present study suggest that subjects carrying at least one copy of the FcgammaRIIIb-NA2 allele might be associated with susceptibility to AgP. However, the clinical implications of the FcgammaRIIIb allelic polymorphism should be determined by further studies.

Relationship of neutrophil phagocytosis and oxidative burst with the subgingival microbiota of generalized aggressive periodontitis

INTRODUCTION

Polymorphonuclear neutrophil (PMN) dysfunctions have been associated with severe forms of periodontitis. This study evaluated the correlation between PMN phagocytosis and oxidative burst with the subgingival microbiota of patients with generalized aggressive periodontitis (GAgP).

METHODS

Heparinized peripheral blood samples were obtained from 18 GAgP patients and 11 periodontally healthy (PH) subjects, and PMNs were isolated on a Ficoll-Hypaque gradient. For phagocytosis analysis, PMNs were incubated with fluorescein-labeled Staphylococcus aureus. The oxidative burst was evaluated by incubation of PMNs with dihydroethidium and activation by S. aureus. The assays were examined using flow cytometry. Subgingival biofilm samples were obtained from periodontal sites with and without periodontitis and 24 species were detected by checkerboard.

RESULTS

A significantly lower phagocytosis rate was observed for patients with GAgP compared with PH subjects over time (P < 0.05). No differences between groups were found for superoxide production. GAgP patients presented significantly higher prevalence and levels of Porphyromonas gingivalis, Tannerella forsythia, and Aggregatibacter actinomycetemcomitans serotype b than controls (P < 0.05). Significant negative correlations between T. forsythia and P. gingivalis and PMN functions were observed.

CONCLUSIONS

GAgP subjects presented diminished phagocytic activity of peripheral PMNs and high prevalence and levels of classical periodontal pathogens.

An integrated approach for measuring copy number variation at the FCGR3 (CD16) locus

Copy number variation (CNV) is an important source of genomic diversity in humans, and influences disease susceptibility. The immunoglobulin-receptor genes FCGR3A and FCGR3B on chromosome 1q23.3 show CNV, and CNV of the FCGR3B gene is associated with glomerulonephritis in systemic lupus erythematosus and organ-specific autoimmunity. Large-scale case-control association studies of CNV require technologies that are amenable to high-throughput analysis with low error rates. Here we propose an integrated suite of five assays, four of them duplexed to reduce DNA usage, that assays for CNV at FCGR3A and FCGR3B, and genotype the polymorphic neutrophil antigen HNA1. We show how a maximum-likelihood (ML) approach to combining the results from these five assays allows estimation of statistical confidence for each individual copy number, and therefore an appropriate significance threshold to be set, controlling the error rate. This approach results in a high-throughput copy number genotyping system, with demonstrable precision and accuracy, that can be applied to large case-control cohort studies. We demonstrate Mendelian inheritance of this CNV, variation in frequency between Europeans and East Asians, and a lack of strong association between the CNV and flanking SNP genotypes, with important consequences for genome-wide association studies.

Expression of FcgammaRs and mCD14 on polymorphonuclear neutrophils and monocytes may determine periodontal infection

Variance in expression of receptors for immunoglobulin G (FcgammaRs), complement (CR3) and lipopolysaccharide (mCD14) on polymorphonuclear neutrophils (PMNs) and monocytes might affect susceptibility for infection with certain pathogens in periodontitis, a chronic infectious disease of tooth-supportive tissues. Levels of FcgammaRI, IIa, III, CR3 and mCD14 on PMNs and monocytes were measured in 19 periodontitis patients and 18 healthy controls. Subgingival infection with Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) was determined. Activation of PMNs and monocytes in response to stimulation with Aa and Pg was assessed by means of change in mCD14 expression. Periodontitis is associated with an enrichment of the FcgammaRIII(+) monocytes (P = 0.015) with concomitant low mCD14 (P = 0.001). Unadjusted data showed that the subjects culture-positive for Aa (Aa(+)) had significantly lower expression of monocytic FcgammaRI (P = 0.005) and FcgammaRIIa (P = 0.015) than Pg(+) subjects. The FcgammaRI was still lower on monocytes from Aa(+) subjects after adjusting for the background factors (P = 0.037). PMNs from Aa(+) subjects responded in a hyper-reactive manner, in particular when stimulated with Aa (P = 0.011). Lower FcgammaRs expression by monocytes is related to a higher susceptibility of a subject to become infected with Aa. The higher proportion of FcgammaRIII(+) monocytes may be involved in the chronicity of this condition. Hyper-reactive PMNs in Aa(+) subjects may contribute to accelerated breakdown of tooth-supportive tissues.

Gene polymorphisms and the prevalence of key periodontal pathogens

Growing evidence suggests that individual genetic susceptibility may influence the host's response to infections. The aim of this project was to study whether gene polymorphisms of inflammatory markers are associated with the presence of viable periodontopathogenic bacteria. We extracted genomic DNA from 45 young adults diagnosed with generalized aggressive periodontitis to study Fc receptors, formyl peptide receptor, Interleukin-6, tumor necrosis factor-alpha, and vitamin D receptor polymorphisms. The presence and viable numbers of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis were determined by culture, and their identities confirmed by PCR. Multiple logistic regressions revealed that both Fcgamma receptor and IL-6 -174 polymorphisms were associated with increased odds of detecting A. actinomycetemcomitans, P. gingivalis, and T. forsythensis after adjustment for age, ethnicity, smoking, and periodontitis extent. These findings support the hypothesis that complex interactions between the microbiota and host genome may be at the basis of susceptibility to aggressive periodontitis.

NADPH oxidase (CYBA) and FcgammaR polymorphisms as risk factors for aggressive periodontitis: a case-control association study

INTRODUCTION

Neutrophils (PMN) in aggressive periodontitis (AgP) patients have been reported to be hyperactive especially with regards to superoxide production. Polymorphisms in genes influencing PMN function have been proposed as candidate risk factors for AgP. The aim of this study was to test the association of specific gene polymorphisms affecting PMN functions with AgP.

MATERIALS AND METHODS

Two hundred and twenty-four patients with confirmed diagnosis of AgP and 231 subjects with healthy periodontium took part in the study. A blood sample was collected from subjects and genotypes for p22phox (CYBA) NADPH oxidase, FP, Fcalpha and Fcgamma receptors were analysed in a blind fashion.

RESULTS

The C242T p22phox NADPH oxidase T allele was significantly associated with AgP in a multiple logistic regression model adjusting for confounders, and this was observed for all subjects [p = 0.002, odds ratio (OR) = 1.87, 95% confidence interval (CI) = 1.27-2.83] and Caucasians (p = 0.009, OR=2.07, 95% CI = 1.20-3.59). Concomitant presence of C242T p22phox NADPH oxidase T allele and FcgammaRIIIb NA1 homozygosity was associated with the generalized AgP phenotype in Caucasians (p = 0.001, OR = 30.35, 95% CI = 3.81-241.97).

CONCLUSIONS

C242T p22phox NADPH oxidase and FcgammaR polymorphisms may predispose to AgP through a modulation of neutrophil superoxide production.

Distribution of FcγRIIa and FcγRIIIb Genotypes in Patients With Generalized Aggressive Periodontitis

BACKGROUND

Polymorphisms in FcgammaR have been associated with different forms of periodontitis. This study determined the frequency of FcgammaRIIa and FcgammaRIIIb alleles/genotypes in patients with generalized aggressive periodontitis (GAgP).

METHODS

Thirty-one GAgP and 49 periodontally healthy Brazilian subjects participated in the study. Full-mouth periodontal examinations were carried out, and mouthwash samples were collected for human DNA isolation. FcgammaR genotyping was performed by polymerase chain reaction and hybridization with allele-specific oligonucleotide probes. Significant differences between groups were sought by Mann-Whitney, chi2, and Fisher exact tests and configural frequency analysis.

RESULTS

FcgammaRIIa-H131 (53.8%) and FcgammaRIIIb-NA1 (75%) were the most prevalent alleles in this sample population. A significant overrepresentation of FcgammaRIIIb-NA2 was observed in the GAgP group, whereas FcgammaRIIIb-NA1 was detected more often in healthy individuals (odds ratio, 32.5; 95% confidence interval [CI], 10.6 to 99.8; P<0.001). No significant differences in the distribution of the FcgammaRIIa genotypes were observed between the groups. The prevalence of FcgammaRIIIb-NA2/NA2 was higher in GAgP patients, whereas FcgammaRIIIb-NA1/NA1 was predominant in the healthy group (chi2=45.1; P<0.001). The combination of the genotypes FcgammaRIIIb-NA2/NA2 plus FcgammaRIIa-H/H131 was observed more frequently in GAgP subjects than expected from marginal frequencies (chi2=12.5; P<0.001).

CONCLUSIONS

The data suggest that the FcgammaRIIIb-NA2 allele and/or FcgammaRIIIb-NA2/NA2 genotype and the composite genotype FcgammaRIIIb-NA2/NA2 plus FcgammaRIIa-H/H131 may be associated with GAgP, whereas FcgammaRIIIb-NA1 and/or FcgammaRIIIb-NA1/NA1 may be related to periodontal health in this sample of the Brazilian population.

Antibody responses to Porphyromonas gingivalis hemagglutinin A and outer membrane protein in chronic periodontitis

BACKGROUND

Hemagglutinin and outer membrane protein (OMP) are major virulence factors associated with colonization of Porphyromonas gingivalis in the gingival crevice. The genes for the 200-kDa antigenic protein (200-kDa AP) and 40-kDa OMP of P. gingivalis have been successfully cloned. Additionally, the 200-kDa AP gene has been shown to constitute the hemagglutinin A (hagA) gene of P. gingivalis. Therefore, this study was constructed to evaluate the distributions and serum levels of immnoglobulin G (IgG) antibodies specific for 200-kDa AP and 40-kDa OMP in periodontitis patients.

METHODS

Fifty patients with chronic periodontitis and 59 controls without periodontal destruction were enrolled in this study. We cloned the genes for 200-kDa AP and 40-kDa OMP from P. gingivalis and constructed the purified recombinant proteins. Serum levels of IgG subclass antibodies specific for both recombinant 200-kDa and 40-kDa OMP were determined in patients and controls by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

The serum IgG subclass distribution for patients and controls was IgG1>IgG4>IgG2>IgG3 in the anti-200-kDa AP response, which was almost identical to that in the anti-40-kDa OMP response. The patient group showed significantly higher serum IgG responses to the 40-kDa OMP than the control group (P<0.01). In contrast, IgG subclass responses to the 200-kDa AP were not different between the patients and controls. Serum levels of antibodies reactive with both 200-kDa and 40-kDa proteins did not have a significant association with mean probing depth.

CONCLUSION

These results suggested that serum IgG responses against P. gingivalis OMP rather than the hagA may be more active in chronic periodontitis.

Analytical epidemiology of periodontitis

AIMS

To review the literature related to the analytical epidemiology of periodontitis generated over the past decade. This review does not deal with descriptive epidemiologic studies of the prevalence, extent and severity of periodontitis with respect to global geography, but focuses exclusively on analytical epidemiology issues, including the challenges posed by the use of different case definitions across studies, current theories and models of disease progression, and risk factors associated with the onset and progression of periodontitis.

METHODS

Relevant publications in the English language were identified after Medline and PubMed database searches.

FINDINGS AND CONCLUSIONS

There is a conspicuous lack of uniformity in the definition of periodontitis used in epidemiologic studies, and findings from different research groups are not readily interpretable. There is a lack of studies that specifically address the distinction between factors responsible for the onset of periodontitis versus those affecting its progression. Colonization by specific bacteria at high levels, smoking, and poorly controlled diabetes have been established as risk factors for periodontitis, while a number of putative factors, including specific gene polymorphisms, have been identified in association studies. There is a clear need for longitudinal prospective studies that address hypotheses emerging from the cross-sectional data and include established risk factors as covariates along with new exposures of interest. Intervention studies, fulfilling the "targeting" step of the risk assessment process, are particularly warranted. Obvious candidates in this context are studies of the efficacy of elimination of specific bacterial species and of smoking cessation interventions as an alternative to the traditional broad anti-plaque approach in the prevention and control of periodontitis. Ideally, such studies should have a randomized-controlled trial design.

Targeting of Porphyromonas gingivalis with a bispecific antibody directed to FcalphaRI (CD89) improves in vitro clearance by gingival crevicular neutrophils

Phagocytosis and killing of pathogens by polymorphonuclear neutrophils (PMN) from gingival crevicular fluid (GCF) is diminished in chronic periodontitis patients. As an approach to improve targeting of PMN toward a periodontopathogen, Porphyromonas gingivalis, the efficacy of a bispecific antibody (BsAb) directed against both recombinant 130 kDa hemagglutinin domain (r130k-HMGD) of P. gingivalis, and PMN Fc receptor (FcR) was evaluated. GCF PMN exhibited higher IgA FcR (FcalphaRI) levels, and lower IgG FcR (FcgammaRIIa and FcgammaRIIIb) levels than PB PMN. Functional studies revealed that GCF PMN exhibited a higher capacity to phagocytose and kill P. gingivalis opsonized with a BsAb targeting P. gingivalis r130k-HMGD to FcalphaRI as compared to an anti-r130k-HMGD antibody. However, phagocytosis and killing activity of PB PMN that were incubated with the two antibodies proved comparable. These data support targeting of pathogens toward FcalphaRI as an option to improve antibacterial immunity in chronic periodontitis patients.

The Trans-Chromosomic Mouse-Derived Human Monoclonal Antibody Promotes Phagocytosis ofPorphyromonas gingivalisby Neutrophils

BACKGROUND

As a safe immunotherapeutic approach, human monoclonal antibody (hMAb) may be effective in clearing periodontopathic bacteria. The trans-chromosomic (TC) technology has recently been applied to construction of the TC mouse, which enables us to incorporate entire human chromosome fragments containing immunoglobulin (Ig) gene cluster. The aim of this study is to establish TC mouse-derived hMAb, and to test the in vitro opsonophagocytic activity.

METHODS

Human Ig-producing TC mouse was immunized by recombinant 40-kDa outer membrane protein (r40-kDa OMP) of Porphyromonas gingivalis 381, and the spleen cells were fused with the mouse myeloma cell line. The specificity of antir40- kDa OMP hMAb was evaluated with the enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance assays. Flow cytometric analyses were performed to assess the opsonophagocytic activity.

RESULTS

We successfully constructed 99 IgG isotype clones (IgG1: 84; IgG2: 11; IgG4: four clones), which were specifically reactive with r40-kDa OMP. The anti-r40-kDa OMP IgG1 hMAbs promoted phagocytosis of P. gingivalis by neutrophils. Futhermore, an increased opsonophagocytic activitity of anti-r40-kDa OMP IgG1 hMAbs was observed not only in P. gingivalis 381, but also in the W50, W83, and Su63 strains.

CONCLUSION

Our results document the TC mouse-derived hMAb to promote neutrophil phagocytosis of P. gingivalis, suggesting an immunotherapeutic option for clearance of P. gingivalis.

FcγRIIIb Genotypes and Smoking in Periodontal Disease Progression Among Community-Dwelling Older Adults in Japan

BACKGROUND

FcgammaRIIIb genotypes and smoking are risk factors for periodontal disease. However, the interaction of FcgammaRIIIb- NA1-NA2 polymorphism with smoking remains unclear. The purpose of this study was to determine if FcgammaRIIIb-NA1-NA2 polymorphism and smoking are associated with periodontal disease progression among elderly people.

METHODS

Among 70-year-old subjects, 164 with neither diabetes mellitus nor blood sugar > or =140 mg/dl, who had more than 20 teeth and who could participate in both the baseline and the follow-up examinations were included in the study. The NA1 group comprised subjects with FcgammaRIIIb-NA1NA1 genotype (N = 53), while the NA2 group included subjects with FcgammaRIIIb-NA1NA2 or NA2NA2 genotype (N = 111). We examined the progression of periodontitis by measuring attachment loss during 3 years.

RESULTS

The frequency of subjects who showed > or =4 mm additional attachment loss at one or more sites was 55.6% for smokers and 37.2% for non-smokers. The odds ratio (OR) was 2.13 (confidence interval [CI]: 0.92 to 4.76). We found a better association between periodontal progression and smoking in the NA2 group. The OR for smokers was 3.03 (CI:1.12 to 8.33, P = 0.028). Additionally, the mean number of sites with > or =4 mm additional attachment loss per person between smokers and non-smokers in the NA2 group or between smokers and non-smokers in the NA1 group was 2.90 3.42 and 0.74 1.53 or 0.57 0.79 and 0.68 1.03, respectively (P <0.001; analysis of variance [ANOVA]).

CONCLUSION

Our results may suggest an association between smoking and periodontal disease progression in elderly people with FcgammaRIIIb-NA2 polymorphism.

FcgammaRIIB gene polymorphisms in Japanese periodontitis patients

Human type II low-affinity receptor for immunoglobulin G (FcgammaRII) constitutes a clustered gene family consisting of FcgammaRIIA, IIB and IIC genes. FcgammaRIIB is unique in its ability to transmit inhibitory signals in B cells via immunoreceptor tyrosine-based inhibitory motif (ITIM). B-cell activation and subsequent elevated production of IgG are the immunopathological features of inflammatory disease such as periodontitis. To determine whether an association with periodontitis susceptibility exists, genetic polymorphisms of FcgammaRIIB were examined in Japanese patients with aggressive periodontitis (AGP) and chronic periodontitis (CP), and in the race-matched healthy controls (HCs). A significant difference was observed in the distribution of FcgammaRIIB-232I/T allele (exon 5) between the AGP and HC groups, with enrichment of the 232T in the AGP group (P=0.006). In addition, the FcgammaRIIB-nt 646-184A/G allele (intron 4) distribution was significantly different between the CP and HC groups, with enrichment of the nt 646-184A in the CP group (P=0.011). These results document the association of FcgammaRIIB gene polymorphisms with susceptibility to periodontitis in the Japanese.

Gm (23) allotypes and Fcgamma receptor genotypes as risk factors for various forms of periodontitis

OBJECTIVES

Given the diversity of the distribution of the Gm (23) allotypes and FcgammaR genotypes in different ethnic groups, it was our purpose to examine their clinical significance in periodontitis in Taiwan.

MATERIAL & METHODS

Genomic DNA of 50 patients with chronic periodontitis (CP), 30 patients with generalized aggressive periodontitis (G-AP) and 74 healthy controls were harvested. The Gm (23) allotypes were determined by radial immunodiffusion test, and the FcgammaR IIa (CD32) and IlIb (CD16) genotypes were determined by polymerase chain reaction-based allele-specific oligonucleotide hybridization.

RESULTS

The overall carrier rate of the Gm (23+) allotype was higher than 85%, and the Gm (23-) allotype was statistically over-represented in patients with CP compared to the controls. There were no differences in the distributions of the three genotypes of FcgammaR IIa and IIIb among the three tested groups. The frequency of the R131 allele of the FcgammaR IIa polymorphisms was higher in G-AP than in CP when R/H allelic frequencies (p = 0.01) were examined by the chi2 test.

CONCLUSION

The Gm (23-) allotype might be a potential risk factor for CP. Although the R131 allele of FcgammaR IIa occurred more frequently in G-AP than in CP, its clinical significance could not be justified in this study.

Polymorphonuclear Granulocytes Induce Antibody-Dependent Apoptosis in Human Breast Cancer Cells

Recent studies in HER-2/neu-targeted immunotherapy demonstrated that polymorphonuclear neutrophils (PMN) mediated Ab-dependent cellular cytotoxicity against HER-2/neu-positive breast cancer cell lines. However, the mechanism of cell death remained unclear. We used several assays to analyze the induction of apoptosis in the breast cancer cell line SK-BR-3 via PMN-dependent Ab-dependent cellular cytotoxicity. In the presence of the HER-2/neu Ab 520C9 and PMN from healthy donors, apoptosis occurred as detected by annexin V binding and disappearance of euploid SK-BR-3 nuclei, which can be differentiated from PMN nuclei by their increased DNA contents. Apoptosis induction was observed with E:T cell ratios as low as 10:1. Laser scanning fluorescence microscopy of TUNEL tumor cells or staining for cleaved cytokeratin-18 further confirmed apoptosis of the SK-BR-3 breast cancer cells. Killing via 520C9 was dependent on the interaction with FcR on PMN, because 1) F(ab')(2) fragments of 520C9 mediated no cytotoxicity, 2) target cell death was influenced by a biallelic polymorphism of FcgammaRIIa on the effector cells, and 3) a bispecific Ab against HER-2/neu and the IgA receptor (FcalphaRI) expressed on effector cells significantly induced apoptosis. Thus, PMN induce Ab-dependent apoptosis against human breast cancer cells targeted with HER-2/neu-directed mAbs or FcR directed bispecific Abs.

Are there HLA combinations typical supporting for or making resistant against aggressive and/or chronic periodontitis?

OBJECTIVE AND BACKGROUND

Human leukocyte antigens (HLA)/alleles have been considered as risk factors for periodontal disease. However, data from HLA associations is not consistent. Diversity of HLA antigen combinations and en bloc inherited HLA alleles (haplotypes), as known in systemic diseases, can be variable factors in disease association. Therefore, the aim of this study was to investigate the incidence of HLA homozygosities, heterozygosities and estimated haplotypes in German Caucasian groups with generalized aggressive (N = 50) and chronic (N = 102) periodontitis in comparison to control probands without periodontitis (N = 102).

METHODS

HLA-A, -B, -Cw, -DRB1, -DRB3/4/5, -DQB1 typing was carried out using both serologic (microlymphocytotoxicity test) and genomic (PCR-SSP: PCR with sequence specific primers) techniques. Frequencies of all homozygosities, heterozygosities and haplotypes were determined in all patients and controls.

RESULTS

In both patient groups, associations to HLA homozygosities and heterozygosities were found. Most striking was the significantly lower frequency of HLA-DRBblank* homozygosity (non-DRB3*/DRB4*/DRB5*) in chronic periodontitis (p < 0.05), whereas HLA-DRB1*15 : DRB5*(DR51) : DQB1*06 showed a slightly higher homozygosity rate in all patients. As the combination HLA-A*02,A*03 was significantly decreased in aggressive periodontitis (p < 0.05), HLA-A*01,A*03 heterozygosity was significantly lowered in chronic periodontitis (p < 0.05). Among others, the known positive associations for HLA-A*68/69 (A28) and HLA-DRB1*04 were confirmed by the haplotypes HLA-A*68/69 : Cw*07 : B*18 in aggressive periodontitis (p < 0.05) and HLA-Cw*08 : B*14 : DRB1*04 in chronic periodontitis (p < 0.05).

CONCLUSION

The present study elucidates the variety of HLA associations and therefore the difficulty to assign single HLA markers to periodontal disease. Susceptibility/resistance of both aggressive and chronic periodontitis may rather be influenced by particular HLA marker combinations. Associated HLA haplotypes may be of further importance for unknown gene loci representing a part of the genetic background for periodontitis. The different associations in aggressive and chronic periodontitis indicate different susceptibility/resistance factors for both diseases.

Impact of genetic polymorphisms on the smoking-related risk of periodontal disease: the population-based study SHIP

Periodontitis is a bacterial inflammatory disease leading to attachment loss with the consequence of tooth loss. There exists a multifactorial risk pattern including bacterial challenge, smoking, age, sex, diabetes, socio-economic and genetic factors. Smoking has the highest impact on the course of the disease modulated by all the other factors. Here, we report the relationship between smoking and the polymorphisms of genetic polymorphisms inflicted in the pathogenesis.

In a randomly selected population-based study, 1083 subjects were typed for the polymorphisms of the IL-1 genotype, Fcγ RIIIb receptor gene, myeloperoxidase and N-acetyltransferase (NAT2) and related to their periodontal state. Smoking behavior was assessed including present and past quality and quantity of smoking.

There is a significant dose-effect relationship between the exposure to tobacco smoke and the extent of periodontal disease assessed as attachment loss and tooth loss. Moreover, there are gene-environmental interactions as subjects bearing variant genotypes show an enhanced smoking-associated risk of the disease modulated by these genotypes. In non-smokers, the impact of these genetic polymorphisms is mostly negligible.

This study provides support for the hypothesis that subjects bearing genetic variants of polymorphically expressed phenotypes are at an increased risk of periodontitis when smoking. Mostly, this may be accomplished via the influence of smoking-related impairment on defense mechanisms rather than on the pathogenic pathways.

Genetic susceptibility to chronic periodontal disease

Evidence suggests that there is a significant genetic component to susceptibility and resistance to chronic periodontal disease. Data from both clinical studies and studies using animal models are reviewed here. Also outlined are the genomic methods that are now available for identifying susceptibility and resistance loci.

Fc gamma receptor genes as risk markers for localized aggressive periodontitis in African-Americans

BACKGROUND

Receptors for the Fc fragment of immunoglobulin G (Fc gammaRs) play a crucial role in host defense against bacterial infection by linking humoral and cell-mediated immune responses. Allelic variants of certain Fc gammaRs have been shown to differ relative to their biologic activity. Thus, genes encoding allotypes with diminished activity have been suggested as potential risk factors for infectious diseases. The goal of this study was to determine whether specific Fc gammaRIIa, Fc gammaRIIIa, and Fc gammaRIIIb alleles and/or genotypes could be used to predict susceptibility to localized aggressive periodontitis (LAgP) in an African-American population.

METHODS

Whole blood or saliva was obtained from 48 LAgP and 67 periodontally-healthy African-American subjects. DNA was prepared from each sample. Fc gammaRIIa and Fc gammaRIIIa genotyping was analyzed by polymerase chain reaction (PCR) amplification of DNA with allele-specific primers followed by allele-specific restriction digestion of the products. Fc gammaRIIIb genotyping was done by allele-specific PCR.

RESULTS

There was a statistically significant over-representation of the Fc gammaRIIIb-NA2 allele in LAgP patients compared to controls (P = 0.024). Relative to the Fc gammaRIIIb-NA1/NA2 and homozygous NA1/NA1 genotypes, the prevalence of the Fc gammaRIIIb NA2/NA2 genotype was higher in the LAgP group relative to the control population. Individuals expressing this genotype appeared at greater risk for developing LAgP (odds ratio 2.271, 95% confidence interval: 1.005 to 5.132). There were no significant differences in the distribution of the Fc gammaRIIa H/R or Fc gammaRIIIa-158 F/V genotypes nor their allelic frequencies between the LAgP patients and controls.

CONCLUSIONS

These data suggest that the Fc gammaRIIIb NA2 allele and/or NA2/NA2 genotype may represent risk markers for susceptibility to LAgP in African-Americans.

Smoking and polymorphisms of the interleukin-1 gene cluster (IL-1alpha, IL-1beta, and IL-1RN) in patients with periodontal disease

BACKGROUND

Polymorphisms within the interleukin-1 cluster are known to be associated with adult periodontal disease. However, interactions of genetic with other risk factors, especially smoking, remain questionable. The aim of this cross-sectional study was to evaluate the genetic influence on periodontal variables in relation to environmental factors.

METHODS

One-hundred fifty-four (154) Caucasian subjects were clinically and radiographically assessed for their periodontal status, their smoking history recorded, and their allelic pattern of IL-1alpha, IL-1beta, and IL-1RN polymorphisms determined by genotyping.

RESULTS

In assessing periodontitis with mean probing depth, mean attachment loss, or mean bone loss, no differences were found in allele frequencies or combined allotypes between subjects with mild or moderate versus those with severe signs of periodontitis. However, the extent of attachment loss defined as percentage of sites >4 mm was significantly associated with the composite genotype of IL-1alpha/1beta in smokers (odds ratio [OR] = 4.00; 95% confidence interval [CI] 1.03 to 16.70; P= 0.02). No differences were found in genotype negative subjects irrespective of their smoking status. They had nearly identical attachment loss as genotype positive non-smokers. Similar non-significant results were found with respect to extent of bone loss. An increased risk of more extended attachment loss was observed also in individuals carrying mutations of the combined genotype IL-1alpha/IL-1RN, again showing enhanced risk only in genotype-positive and smoking subjects.

CONCLUSIONS

The results provide evidence that the composite genotypes studied show interaction with smoking, the main exposition-related risk factor of periodontal disease. Non-smoking subjects are not at increased risk, even if they are genotype-positive.

The Fc gamma receptor genotype as a severity factor for chronic periodontitis in Japanese patients

BACKGROUND

Functional polymorphisms of immunoglobulin G (IgG) Fc receptors (Fc gamma R) have been shown to be associated with generalized aggressive periodontitis (GAgP) or recurrence of chronic periodontitis (CP) in Japanese patients. The purpose of this study was to evaluate whether Fc gamma R polymorphisms are also associated with severity of CP.

METHODS

Fifty Japanese non-smoking patients with severe CP and 39 Japanese non-smoking patients with moderate CP were identified according to established clinical criteria, including measurements of probing depth (PD), clinical attachment level (CAL), and alveolar bone loss (BL). Fc gamma R genotypes for 3 bi-allelic polymorphisms (Fc gamma RIIa-R/H131, Fc gamma RIIIa-158V/F, Fc gamma RIIIb-NA1/NA2) were determined in these CP patients and 64 race-matched, non-smoking healthy controls by means of allele-specific polymerase chain reactions.

RESULTS

There was a significant over-representation of Fc gamma RIIIa-158V allele in severe CP patients compared to moderate CP patients (odds ratio 2.03, 95% confidence interval [CI] 1.03-4.01, chi 2 = 4.86, P = 0.028). In addition, we found a strong association between CP severity and Fc gamma R composite genotype comprising Fc gamma RIIIa-158V plus Fc gamma RIIIb-NA2 (severe CP versus moderate CP: odds ratio 4.69, 95% CI 1.52-15.10, chi 2 = 9.35, P = 0.002; severe CP versus healthy controls: odds ratio 4.10, 95% CI 1.62-10.59, chi 2 = 11.13, P = 0.0009). Moreover, CP patients positive for the composite genotype exhibited more severe signs of periodontitis than composite genotype-negative individuals (positive versus negative; mean PD: 3.8 mm versus 3.2 mm, P = 0.005; mean CAL: 4.5 mm versus 3.7 mm, P = 0.005; mean % BL: 37.6% versus 29.9%, P = 0.008).

CONCLUSION

Our results document the Fc gamma RIIIa-158V allele and possibly Fc gamma RIIIb-NA2 to be associated with severity of CP in Japanese patients.

Polymorphisms of Fc gamma-receptors RIIa, RIIIa, and RIIIb in patients with adult periodontal diseases

Polymorphisms influencing the binding affinity between the Fcgamma receptors and IgG of different subclasses are thought to be of importance in the individual susceptibility to infections with Gram-negative bacteria contributing to periodontal disease. One hundred and fifty-four Caucasian subjects were clinically and radiographically examined for their periodontal status and genotyped for their allelic pattern of FcgammaRIIa, FcgammaRIIIa, and FcgammaIIIb polymorphism. In assessing periodontitis according to mean probing depth and attachment loss, no differences were found in allele frequencies or combined allotypes between the subjects with mild or moderate and those with severe signs of periodontitis. However, the extent and severity of bone loss were significantly associated with the genotype of the receptor FcgammaRIIIa. An increased risk of severe bone destruction was observed in individuals carrying the FcgammaRIIIa-VV genotype (OR = 5.3; 95% CI 1.4-26.2). FcgammaRIIIb is in linkage disequilibrium with FcgammaRIIIa. Hence it is also related to periodontal disease. There is no indication of an association between the polymorphism of FcgammaRIIa and periodontitis. The results are evidence that the FcgammaRIIIa genotype coding for the high affinity receptor imposes an additional risk of bone loss as does the FcgammaRIIIb genotype coding for the low affinity receptor.

Effective in vitro clearance of Porphyromonas gingivalis by Fc alpha receptor I (CD89) on gingival crevicular neutrophils

Porphyromonas gingivalis has been implicated as a causative pathogen in periodontitis. Immunotherapeutic approaches have recently been suggested to aid in the clearance of P. gingivalis from disease sites. Because antibody-Fc receptor (FcR) interactions play a role in the effector functions of polymorphonuclear neutrophils (PMN), we evaluated which FcR on PMN from gingival crevicular fluid (GCF) serves as an optimal target molecule for FcR-directed immunotherapy. GCF PMN and peripheral blood (PB) PMN from adult periodontitis patients were analyzed for their immunoglobulin G (IgG) and IgA FcR (Fc gamma R and Fc alpha R, respectively) expression and function by studying IgG- and IgA-mediated elimination of P. gingivalis. GCF PMN exhibited higher Fc alpha RI and Fc gamma RI levels and lower Fc gamma RIIa and Fc gamma RIIIb levels than PB PMN. Functional studies revealed that GCF PMN exhibited less of a capacity to phagocytose and kill IgG1-opsonized P. gingivalis than PB PMN. IgA1-mediated phagocytosis and killing capacity was, however, comparable between GCF PMN and PB PMN. In summary, these in vitro results document that Fc alpha RI represents a candidate target for FcR-directed immunotherapy for the clearance of P. gingivalis.

Evidence for a novel polymorphism affecting both N-linked glycosylation and ligand binding of the IgG receptor IIIB (CD16)

Immunoglobulin G Fc receptor IIIb (FcgammaRIIIb) is constitutively expressed on neutrophils, and has three allelic forms: FcgammaRIIIb-NA1, FcgammaRIIIb-NA2, and FcgammaRIIIb-SH. We identified two Japanese subjects in whom an A to G substitution at nt 221 changes asparagine (N) to serine (S) at amino acid position 45 in the FcgammaRIIIb-NA2 gene. FcgammaRIIIb-NA2-specific monoclonal antibodies (GRM1 and PEN1) did not bind to mutant neutrophils, which lack an N-linked glycosylation site. Furthermore, IgG3-mediated neutrophil phagocytosis by mutant was slightly increased as compared to wild-type donors (Note).

Increased frequency of FcgammaRIIIb-NA1 allele in periodontitis-resistant subjects in an elderly Japanese population

Many elderly people show minimum periodontal tissue destruction, which might be partly due to genetic advantages in host immune response against periodontopathic bacteria. The human IgG Fc receptor IIIb on neutrophils bears a NA1-NA2 polymorphism. The FcgammaRIIIb-NA1 displays a more efficient interaction with IgG1- and IgG3-opsonized bacteria, compared with the FcgammaRIIIb-NA2. We investigated a 70-year-old Japanese population (n = 599) to determine whether the FcgammaRIIIb polymorphism was associated with resistance to periodontitis. Among subjects with > or = 20 teeth present, periodontitis-resistant (n = 46) and periodontitis-susceptible groups (n = 73) were selected based on the percentage of sites with > or = 4 mm probing attachment loss in the entire dentition. The FcgammaRIIIb-NA1 allotype was overrepresented in the periodontitis-resistant group, compared with the periodontitis-susceptible group (chi2 = 4.89, p = 0.03, odds ratio = 1.87, 95% CI, 1.07 to 3.28). This suggests that FcgammaRIIIb-NA1 may be associated with resistance to periodontitis.

The Fcgamma receptor genotype as a risk factor for generalized early-onset periodontitis in Japanese patients

BACKGROUND

Genetic polymorphisms of immunoglobulin G (IgG) Fc receptors (FcgammaR) were recently shown to be associated with recurrence rates of adult periodontitis (AP). The purpose of this study was to evaluate whether FcgammaR polymorphisms are also associated with generalized early-onset periodontitis (G-EOP) in Japanese patients.

METHODS

Thirty-eight Japanese patients with G-EOP and 83 Japanese patients with AP were identified according to established clinical criteria, including measurements of probing depth, clinical attachment level, and alveolar bone level. FcgammaR genotypes for 3 bi-allelic polymorphisms were determined in these G-EOP and AP patients and 104 race-matched healthy controls by means of allele-specific polymerase chain reactions.

RESULTS

There was a significant difference in the distribution of FcgammaRIIIb genotypes between G-EOP patients and healthy controls (P = 0.02). Additionally, a significant over-representation of FcgammaRIIIb-NA2 allele was observed in G-EOP patients as compared to AP patients and controls (P= 0.02, P= 0.009, respectively). Moreover, we found a strong association between G-EOP and the composite genotype comprising FcgammaRIIIb-NA2 and FcgammaRIIIa-158F (G-EOP versus controls: odds ratio 2.4, 95% CI 1.0-6.0, chi2 = 4.13, P= 0.04).

CONCLUSIONS

This study indicates that the FcgammaRIIIb-NA2 allele and possibly FcgammaRIIIa-158F could be associated with susceptibility to G-EOP in Japanese patients.