FcγRIIa (CD32): A Potential Marker Defining Susceptibility to Localized Juvenile Periodontitis

Herpesvirus-bacteria synergistic interaction in periodontitis

The etiopathogenesis of severe periodontitis includes herpesvirus-bacteria coinfection. This article evaluates the pathogenicity of herpesviruses (cytomegalovirus and Epstein-Barr virus) and periodontopathic bacteria (Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis) and coinfection of these infectious agents in the initiation and progression of periodontitis. Cytomegalovirus and A. actinomycetemcomitans/P. gingivalis exercise synergistic pathogenicity in the development of localized ("aggressive") juvenile periodontitis. Cytomegalovirus and Epstein-Barr virus are associated with P. gingivalis in adult types of periodontitis. Periodontal herpesviruses that enter the general circulation may also contribute to disease development in various organ systems. A 2-way interaction is likely to occur between periodontal herpesviruses and periodontopathic bacteria, with herpesviruses promoting bacterial upgrowth, and bacterial factors reactivating latent herpesviruses. Bacterial-induced gingivitis may facilitate herpesvirus colonization of the periodontium, and herpesvirus infections may impede the antibacterial host defense and alter periodontal cells to predispose for bacterial adherence and invasion. Herpesvirus-bacteria synergistic interactions, are likely to comprise an important pathogenic determinant of aggressive periodontitis. However, mechanistic investigations into the molecular and cellular interaction between periodontal herpesviruses and bacteria are still scarce. Herpesvirus-bacteria coinfection studies may yield significant new discoveries of pathogenic determinants, and drug and vaccine targets to minimize or prevent periodontitis and periodontitis-related systemic diseases.

CSF1 gene associated with aggressive periodontitis in the Japanese population

Aggressive periodontitis (AgP) is characterized by the early onset of the rapid and progressive destruction of the alveolar bone. We investigated the correlation of single nucleotide polymorphisms (SNPs) in candidate genes with AgP in the Japanese population in order to determine the genetic risk factors for this complex disease. Among 11 genes related to bone formation and resorption, 43 known SNPs were tested in 98 case and 88 control samples for association with AgP by using SNP genotyping techniques. Among these, three polymorphisms located in the colony stimulating factor 1 (CSF1) gene showed a positive association with AgP. This is the first case of an association between a CSF1 polymorphism and a human disease.

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.

Controlled clinical and psychometric studies on the relation between periodontitis and depressive mood

BACKGROUND

Depressive mood is considered a risk factor for the development of periodontitis.

OBJECTIVES

Investigation of the relationship between periodontitis and psychopathology utilizing psychometry (both observer- and self-rating scales).

METHODS

Forty periodontitis patients were compared with 41 age- and sex-matched controls. The percentage of smokers was similar in both groups (30% versus 24.4%). Dental variables included probing depth, clinical attachment loss (CAL), radiographic loss of attachment, papillary bleeding index (PBI) and approximal plaque index (API). Psychometry comprised the Hamilton Depression Scale, the Zung Self-Rating Depression and Anxiety Scales, the von Zerssen Well-being and Complaint Scales, the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, the Quality-of-Life Index, crystallized intelligence and the Freiburg Personality Inventory (FPI).

RESULTS

Multifactorial analysis of variance demonstrated increased depression and anxiety scores, reduced well-being, increased somatic complaints, deteriorated quality of life and introversion in periodontitis. Partial correlation analyses between psychometric measures and dental variables revealed positive correlations of periodontal disease severity/CAL with the depression/anxiety, subjective well-being and complaints scores, and a negative correlation with quality of life. The API was negatively correlated with social orientation, and the CAL was positively correlated with somatic complaints and introversion in the FPI.

CONCLUSION

Our clinical-psychometric studies confirm depressive mood as a relevant pathogenetic factor for periodontitis.

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

AIM

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

METHODS

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

RESULTS AND CONCLUSIONS

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

Periodontal epidemiology: towards social science or molecular biology?

Terms such as 'molecular epidemiology' and 'genetic epidemiology' have been coined to depict the change from 'traditional epidemiology', concerned with disease determinants at the community or society level, over to 'modern epidemiology', which is concerned with determinants operating at the individual level or even below, i.e. at the organ, tissue, cell, or molecular level. In this commentary, we point out to the limitations of this development and suggest that more emphasis is placed on making the presumed causal disease models explicit, when investigating the relationship between putative determinants and disease. Understanding the disease processes at the micro-level is insufficient for understanding disease at the individual level; and disease patterns at the population level cannot be understood unless it is realized that individuals exist in a variety of contexts that cannot be reduced to individual attributes.

Association of Fcgamma receptor IIa genotype with chronic periodontitis in Caucasians

BACKGROUND

Functional polymorphisms of immunoglobulin G (IgG) Fc receptors IIIa and IIIb (FcgammaRIIIa and FcgammaRIIIb) have been shown as risk factors for periodontitis. The aim of this study is to examine whether FcgammaRIIa polymorphism is associated with a disease risk as well.

METHODS

Baseline periodontal and general health examinations were carried out on 1,221 Caucasian adults. From these, 422 subjects with moderate to severe, or little or no periodontal disease were assigned to two groups according to their mean clinical attachment loss (CAL). Subjects with mean CAL > or = 2.94 mm were diagnosed with chronic periodontitis (n = 213, 62 never-smokers and 151 smokers). Subjects with mean CAL < or = 1.77 mm were considered as having little or no periodontal disease and designated as controls (n = 209, 125 never-smokers and 84 smokers). The FcgammaRIIa genotype for three bi-allelic polymorphisms (FcgammaRIIa-R/ R131, R/H131, and H/H131) was determined by means of allele-specific polymerase chain reactions.

RESULTS

The distribution of FcgammaRIIa genotype between the patient and control groups was significantly different, with enrichment of the high ligand-binding genotype FcgammaRIIa-H/H131 in the patients (patients versus controls: 36.6% versus 25.4%; P = 0.04). Multivariate logistic regression model demonstrated that subject age and gender, smoking, and the FcgammaRIIa genotype were significantly associated with severity of chronic periodontitis. For smokers, a significant over-representation of FcgammaRIIa-H/H131 in the patient group compared to the control group (patients versus controls: 35.1% versus 19.0%; P = 0.03). Additionally, smokers with FcgammaRIIa-H/H131 exhibited significantly greater mean CAL (mean +/- SE: 3.44 +/- 0.16 mm) than those with FcgammaRIIa-R/H131 (2.91 +/- 0.14 mm) and R/R131 (2.82 +/- 0.16 mm) (P = 0.04). There was no association between FcgammaRIIa genotype and the disease susceptibility or severity in subjects who had never smoked.

CONCLUSIONS

Our results suggest that the FcgammaRIIa-H/H131 genotype may be associated with chronic periodontitis risk (and disease severity) in Caucasian smokers. Further studies with families and studies of mechanisms are necessary to help establish the extent to which this is a genetic determinant of periodontal diseases.

Interleukin-4 gene polymorphisms in Japanese and Caucasian patients with aggressive periodontitis

OBJECTIVES

Recently, interleukin (IL) 4 gene polymorphisms have been analyzed in association with periodontitis. Genetic differences between Caucasian and Japanese patients with periodontitis have previously been detected. The aim of the present study was to analyze IL-4 genotypes in Caucasian and Japanese patients with aggressive periodontitis (AgP).

MATERIAL AND METHODS

One hundred and twenty-four subjects were included in the study, 31 Japanese and 30 Caucasian patients with generalized AgP, plus 30 Japanese and 33 Caucasian healthy controls. IL-4 polymorphisms were determined by polymerase chain reaction. A logistic regression was used to investigate the possible association of the genotypes with the disease in both populations. Odds ratio (OR) estimates were analyzed for allele frequencies.

RESULTS

No significant association of IL-4 polymorphisms with the risk of AgP was determined in either population. However, the allele frequencies showed different results between populations. The carriage of the polymorphism in intron 2 was higher in Caucasian patients compared with controls (OR: 2.0, 95% confidence interval: [1.0;4.2]. Furthermore, the frequency of the IL-4 promoter/intron 2 composite genotype (PP+/IP+) in patients and controls, respectively, was found to be approximately 25% and 60% higher in the Japanese population than in the Caucasian population.

CONCLUSION

There was no evidence of an association of IL-4 genotypes and AgP in either population, although the frequencies of the IL-4 genotypes in the Japanese and the Caucasians were different.

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.

Prevalence of periodontopathic bacteria in aggressive periodontitis patients in a Japanese population

BACKGROUND

Actinobacillus actinomycetemcomitans is considered a major etiologic agent of aggressive periodontitis. Other periodontopathic bacteria such as Porphyromonas gingivalis are also suspected of participating in aggressive periodontitis, although the evidence is controversial. The aim of the present study was to investigate the prevalence of periodontopathic bacteria and to clarify the microbiological features of aggressive periodontitis in Japanese patients.

METHODS

Subgingival plaque was collected from 50 aggressive periodontitis (AgP) patients (localized 10, generalized 40). Samples from 35 generalized chronic periodontitis (CP) patients and 18 healthy subjects were examined as controls. Plaque samples were examined using culture and polymerase chain reaction (PCR) method.

RESULTS

The prevalence of A. actinomycetemcomitans was relatively low in the localized (20%) and generalized (17.5%) AgP patients, with no significant difference observed in detection frequencies between AgP and the control groups (CP 8.6%, healthy 0%). On the other hand, Tannerella forsythensis (formerly Bacteroides forsythus), Campylobacter rectus, P. gingivalis, and Treponema denticola were frequently detected in localized as well as generalized aggressive periodontitis patients. The prevalence and proportion of P. gingivalis correlated with severity of clinical attachment loss in both localized and generalized aggressive periodontitis.

CONCLUSIONS

T. forsythensis, C. rectus, P. gingivalis, and T. denticola were the predominant periodontopathic bacteria of aggressive periodontitis patients in Japan. Although A. actinomycetem- comitans was also detected in AgP patients, the prevalence of this bacterium was much lower than that of P. gingivalis.

Fcgamma receptor polymorphisms in relation to periodontitis

OBJECTIVES

Evidence suggests functional relevance for polymorphisms in FcgammaR in relation to inflammatory and infectious diseases. The present aim was to investigate genetic polymorphisms in three FcgammaR in relation to susceptibility and severity of periodontitis.

MATERIAL AND METHODS

The study population consisted of 68 periodontitis patients and 61 controls (Northern European Caucasian background, mean ages 44 and 42 years, respectively). Among the patients, 12 subjects were diagnosed with aggressive periodontitis (AgP) and 56 individuals were diagnosed with chronic periodontitis (CP). Radiographic bone levels were scored for all teeth in the patients. Subjects were typed for the following genes (alleles): FcgammaRIIa (R131 or H131), FcgammaRIIIa (V158 or F158) and FcgammaRIIIb (NA1 or NA2).

RESULTS

Hardy-Weinberg equilibrium criteria were fulfilled for the different genotypes at the three genes investigated. The frequency of the FcgammaRIIIa-V158 allele in the patient population (53%) was higher than in the control group (39%) (OR 1.73 [1.06-2.85], p=0.034). The V158 carriage rate in AgP was even higher (63%). The frequency of the FcgammaRIIa-H131 allele in the total periodontitis population was 58%; for AgP this was 79%, compared with 51% in the control population (OR 3.68 [1.29-10.5], p=0.013). Also, the frequency of the FcgammaRIIa-H/H131 genotype was significantly higher in AgP patients than in controls (OR 9.07 [1.29-63.56], p=0.026, adjusted for smoking status and other potential confounders). Moreover, patients with the FcgammaRIIa-H/H131 genotype had more severe radiographic bone loss than patients with the other FcgammaRIIa genotypes.

CONCLUSION

The current study of relative small sample size suggests that the FcgammaRIIa-H/H131 genotype may be a putative susceptibility and severity factor, and the FcgammaRIIIa-V158 allele a putative susceptibility factor for periodontitis in Northern European Caucasians. These results need further verification and the biological importance of these findings needs further investigation.

Risk of periodontitis in systemic lupus erythematosus is associated with Fcgamma receptor polymorphisms

BACKGROUND

Leukocyte Fc receptors for immunoglobulin G (FcgammaR) play a major role in the handling of immune complexes and pathogens in systemic lupus erythematosus (SLE) and periodontitis. Both diseases have been shown to be partly influenced by genetic components including FcgammaR genotype. The aim of this study was therefore to evaluate whether FcgammaR gene polymorphisms are associated with periodontitis risk in SLE patients.

METHODS

The study subjects consisted of 42 SLE patients with periodontitis (SLE/P), 18 SLE patients without periodontitis (SLE/H), 42 healthy subjects with periodontitis (H/P), and 42 healthy subjects without periodontitis (H/H), who were all unrelated Japanese non-smokers. Genomic DNA was isolated from peripheral blood, and FcgammaR genotypes for 3 biallelic polymorphisms (FcgammaRIIa-R131/H131, FcgammaRIIIa-158V/158F, FcgammaRIIIb-NA1/NA2) were determined by allele-specific polymerase chain reactions.

RESULTS

The SLE/P group was found to have more mild levels of periodontal destruction than the H/P group (P < 0.01). There was a significant difference in the distribution of FcgammaRIIa genotypes between SLE/P and H/H groups (P = 0.004). A significant overrepresentation of the FcgammaRIIa-R131 allele was found in the SLE/P group compared to the H/H group (SLE/P versus H/H: odds ratio [OR] 3.13, 95% confidence interval [CI] 1.46-6.77, P = 0.0013). Furthermore, the prevalence of periodontitis was found to be 70% in SLE patients. The FcgammaRIIa-R131 allele was also found to be overrepresented in the SLE/P group compared to the SLE/H group (SLE/P versus SLE/H: OR 3.40, 95% CI 1.18-10.25, P = 0.011).

CONCLUSION

These results show the FcgammaRIIa-R131 allele to be associated with periodontitis risk in SLE patients.

Association of increased levels of fibrinogen and the -455G/A fibrinogen gene polymorphism with chronic periodontitis

BACKGROUND

Fibrinogen is one of the acute-phase proteins whose levels are elevated during periodontal disease. Recent studies suggest that excessive fibrinogen production might play a role in upregulating host immune responses. In addition, there is a relationship between the -455G/A polymorphism (HaeIII) in the 5' flanking region of the beta-fibrinogen gene promoter and increased fibrinogen levels. In this study, we investigated the distribution of the -455G/A polymorphism and the relationship of this specific genotype to fibrinogen levels in periodontitis patients.

METHODS

In order to assess the -455G/A polymorphism, restriction fragment length polymorphism (RFLP) analysis with HaeIII enzyme was performed in the promoter region of the beta-fibrinogen gene. This was carried out on 79 chronic periodontitis patients as compared to 75 periodontally healthy subjects, matched to age, gender, and race. Fibrinogen levels were determined by the radial immunodiffusion assay (RID).

RESULTS

The frequency of homozygocity for the rare allele of the beta-fibrinogen gene (H2H2) was 13% for the periodontitis patients and 3% for the control group (P = 0.01). The distributions of H1H1 and H1H2 genotypes were 48% and 39% in the patient group and 70% and 27% in the control group, respectively. Chi-square analysis indicated that the distribution of these genotypes between the 2 groups was significantly different (P = 0.01). Fibrinogen levels were significantly higher in the patient group (2,496.5 mg/l +/- 105) compared to the control group (2,250.0 mg/l +/- 118.3) after adjusting for age, gender, and smoking status (P = 0.04). Consistent with previous reports, in our study population, those subjects with the H2H2 genotype had significantly higher fibrinogen levels (3,005.7 mg/l +/- 182.5) compared to subjects with the H1H1 genotype (2,325.0 mg/l +/- 91.6) or H1H2 genotype (2,438.0 mg/l +/- 117.4) (P = 0.001). Furthermore, the H1H2 and H2H2 genotypes were found at a higher frequency among periodontitis patients than controls. The odds ratios (OR) for these genotypes were 3.26 (95% confidence interval [CI]: 1.25 to 8.53) for the H1H2 genotype and 6.41 (95% CI: 1.15 to 35.83) for the H2H2 genotype as compared to individuals with the H1H1 genotype, after adjusting for age, gender, and smoking status.

CONCLUSIONS

The results indicate that a higher percentage of chronic periodontitis patients exhibit genotypes associated with higher plasma fibrinogen levels than healthy individuals. Furthermore, periodontitis patients have significantly higher fibrinogen levels compared to healthy individuals. The presence of H1H2 or H2H2 genotypes as well as elevated fibrinogen levels, in conjunction with other factors, may put individuals at higher risk of having periodontal disease, or may result from periodontal infection-genetic interactions.

Host defense and inflammatory gene polymorphisms are associated with outcomes after HLA-identical sibling bone marrow transplantation

We made the hypothesis that donor and recipient gene polymorphisms that drive the host response to microorganisms could be associated with infections after bone marrow transplantation (BMT). HLA-identical BMT was performed for patients with acute (n = 39) or chronic leukemia (n = 68). Genotyping was performed in 107 D/R DNA pairs for gene polymorphisms of cytokines (tumor necrosis factor-alpha [TNF-alpha] and TNF-beta, interleukin-1 receptor antagonist [IL-1Ra], IL-6, and IL-10), adhesion molecules (CD31 and CD54), Fcgammareceptors (FcgammaRIIa, IIIa, IIIb), mannose-binding lectin (MBL), and myeloperoxidase (MPO). First infection (overall) and first episodes of bacterial, viral, or invasive fungal infection were studied retrospectively for 180 days after BMT. Univariate and multivariate analyses, using death as a competing event, were performed to study risk factors. In multivariate analysis, first overall infections were increased in patients with the FcgammaRIIa R-131 genotype (hazard ratio [HR] = 1.92; P =.04), and severe bacterial infections were increased when the MPO donor genotype was AG or AA (HR = 2.16; P =.03). Viral and invasive fungal infections were not influenced by any genetic factor studied. Interestingly, we also found that (1) time to neutrophil recovery was shorter when donors were FcgammaRIIIb HNA-1a/HNA-1b (HR = 1.77; P =.002); (2) donor IL-1Ra (absence of IL-1RN*2) increased the risk for acute graft-versus-host disease (GVHD) (II-IV) (HR = 2.17; P =.017); and (3) recipient IL-10 (GG) and IL-1Ra genotypes increased the risk for chronic GVHD (P =.03 and P =.03, respectively). Finally, 180-day transplantation-related mortality rates were increased when donors were FcgammaRIIIb HNA-1a/HNA-1a or HNA-1b/HNA-1b (HR = 2.57; P =.05) and donor MPO genotype was AA (HR = 5.14; P =.004). In conclusion, donor and recipient gene polymorphisms are informative genetic risk factors for selecting donor/recipient pairs and could help in the understanding of mechanisms involved in host defenses of BM transplant recipients.

Analysis of genetic polymorphisms at the interleukin-10 loci in aggressive and chronic periodontitis

BACKGROUND/AIMS

Different cytokine genotypes have been described in periodontal disease. The aim of the present study was to investigate the genetic association of two previously described interleukin-10 (IL-10) polymorphisms in patients with aggressive (AP) and chronic periodontitis (CP) and to investigate possible associations with clinical manifestations.

METHODS

Based on clinical parameters and radiographs, 23 patients with CP and 18 patients with AP were included in the study. Additionally, 21 age-matched healthy subjects served as a control group. Genomic DNA was isolated from whole blood samples and the IL-10 promoter sequences from positions - 597 to - 824 were amplified by polymerase chain reaction (PCR). Polymorphisms were detected by restriction-enzyme cleavage. The A and C alleles at the - 597 position were associated with the T and C alleles at the - 824 position, respectively. Fisher's exact test was used for the statistical analysis.

RESULTS

No significant differences were observed in the allele frequencies between controls and AP patients (p = 0.70) or CP patients (p = 0.43), although the previously reported association between allele A at position - 597 and allele T at position - 824 was observed in our population.

CONCLUSION

We conclude that the investigated polymorphisms are not associated with periodontal disease.

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.

Interleukin-4 polymorphisms in early onset periodontitis

BACKGROUND, AIMS

Periodontitis is the result of a complex interplay between oral bacteria and the host response, often modulated by behavioral factors. Early-onset periodontitis (EOP) is defined by the age of onset, the distribution of lesions and specific microbial pathogens.

METHOD

Studies in twins suggested a genetic contribution to the pathogenesis of periodontitis. EOP heritable factors may be related to immune mechanisms which could enhance the pathogenic potential of plaque bacteria in susceptible individuals. Among others, Interleukin 4 (IL-4) is a potent cytokine in the immune response and is a potent down regulator of macrophage function. In the present study, we report a specific genotype of the IL-4 gene, which was detected by specific primers and PCR analysis.

RESULTS

In the EOP-group 27.8% were IL-4 promotor- and intron polymorphism positive (PP+ and IP+). None of the age-matched healthy controls or patients with adult periodontitis (n=25) carried the markers. Moreover, serum IL-4 levels of PP+ and IP+ patients were below the detection limit and significantly different (p<0.01) from the IL-4 concentrations of healthy controls and PP- and IP- patients.

Candidate genes as potential links between periodontal and cardiovascular diseases

Recent epidemiological associations between periodontal disease and cardiovascular disease have led to a search for biological mechanisms that explain the associations. Genetic factors that influence biological processes involved in both diseases represent one of the potential mechanisms that may link periodontitis and cardiovascular disease. At present, several candidate genes have been investigated in one of the diseases but not the other. Although there are limited data to support a specific candidate gene as the explanation for observed associations between the 2 diseases, a few candidates look promising. One candidate that influences inflammation, interleukin-1 gene polymorphisms, has been associated with periodontal disease and cardiovascular disease. This review will consider biological mechanisms and genes that may be reasonable candidates for an etiological mechanism that influences the clinical characteristics of both periodontal disease and cardiovascular disease.

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.

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.

Evaluation of human FcgammaRIIA (CD32) and FcgammaRIIIB (CD16) polymorphisms in Caucasians and African-Americans using salivary DNA

Two classes of low-affinity receptors for the Fc region of immunoglobulin G (IgG) (FcgammaR) are constitutively expressed on resting human neutrophils. These receptors, termed FcgammaRIIa (CD32) and FcgammaRIIIb (CD16), display biallelic polymorphisms which have functional consequences with respect to binding and/or ingestion of targets opsonized by human IgG subclass antibodies. The H131-R131 polymorphism of CD32 influences binding of human IgG2 and, to a lesser extent, human IgG3 to neutrophils. The neutrophil antigen (NA1-NA2) polymorphism of CD16 influences the efficiency of phagocytosis of bacteria opsonized by human IgG1 and IgG3. These polymorphisms may influence host susceptibility to certain infectious and/or autoimmune diseases, prompting interest in the development of facile methods for determination of CD32 and CD16 genotype in various clinical settings. We previously reported that genomic DNA from saliva is a suitable alternative to DNA from blood in PCR-based analyses of CD32 and CD16 polymorphisms. In the present study, we utilized for the first time this salivary DNA-based methodology to define CD32 and CD16 genotypes in 271 Caucasian and 118 African-American subjects and to investigate possible linkage disequilibrium between certain CD32 and CD16 genotypes in these two ethnic groups. H131 and R131 gene frequencies were 0.45 and 0.55, respectively, among Caucasians and 0.59 among African-Americans. NA1 and NA2 gene frequencies were 0.38 and 0.62 among Caucasians and 0. 39 and 0.61 among African-Americans. Since FcgammaRIIa and FcgammaRIIIb synergize in triggering neutrophils, we also assessed the frequency of different CD32 and CD16 genotype combinations in these two groups. In both groups, the R/R131-NA2/NA2 genotype combination was more common than the H/H131-NA1/NA1 combination (threefold for Caucasians versus sevenfold for African-Americans). Whether individuals with the combined R/R131-NA2/NA2 genotype are at greater risk for development of infectious and/or autoimmune diseases requires further investigation, which can be conveniently performed using DNA from saliva rather than blood.

Early-onset periodontitis

In 1993, the 1st European Workshop on Periodontology explicitly recognized that there was insufficient knowledge to differentiate truly different forms of periodontal disease from differences in the presentation/severity of the same disease. In spite of recent progress in our understanding of periodontal diseases, the issue is far from having been resolved. Classification of periodontal diseases, therefore, remains based upon the definition of specific clinical syndromes. Early-onset periodontitis (EOP) is one such syndrome and comprises a group of pathological conditions leading to loss of periodontal tissues early in life. The notion that classifies periodontitis syndromes as "early-onset" or "adult" is primarily epidemiological in nature and is based on the observation that periodontitis is rather infrequent in children and young adults. Nevertheless, considerable epidemiological evidence indicates that periodontitis does affect children and young adults to a level of severity that may lead to premature exfoliation of primary and/or permanent teeth. Clinical presentation of periodontitis early in the life of an individual is thought to indicate that the etiologic agents have been able to cause considerable tissue damage over a relatively short period of time. It also implies either infection with highly virulent bacteria and/or a highly susceptible subject. The purpose of this review is to discuss the criteria generally utilized to classify EOP, provide the rationale to designate EOP as a distinct disease entity, and to review the evidence justifying a subclassification into particular subgroups of EOP.

Interleukin-1 haplotype and periodontal disease progression following therapy

The purpose of this study was to assess the prognostic value of the IL-1 haplotype on the progression of periodontal disease following therapy. 48 adult patients with untreated periodontitis harboring Actinobacillus actinomycetemcomitans and/or Porphyromonas gingivalis were randomly assigned to receive full-mouth scaling alone (control) or in combination with systemic metronidazole plus amoxicillin and supragingival irrigation with chlorhexidine digluconate (test). All patients received supportive periodontal therapy at 3 to 6 months intervals. In 33 patients, lymphocyte DNA was analyzed for polymorphism in the IL-1A gene at position -889 and IL-1B gene at position +3953. Overall, 16 of 33 patients (7 of 17 test and 9 of 16 control) carried the IL-1 haplotype. 2 years following initial periodontal therapy, no differences in the survival rates of sites or teeth not exhibiting probing attachment loss of 2 mm or more compared to baseline, were found between patients who tested positive (85% sites, 53% teeth) and patients who tested negative (89% sites, 56% teeth) for the IL-1 haplotype. The results indicated that the IL-1 haplotype may be of limited value for the prognosis of periodontal disease progression following non-surgical periodontal therapy.

Single nucleotide polymorphisms of the N-formyl peptide receptor in localized juvenile periodontitis

BACKGROUND

Neutrophils from patients with localized juvenile periodontitis (LJP) exhibit decreased binding and responsiveness to various chemotactic agents, including N-formyl-1-methionyl-1-leucyl-1-phenylalanine (FMLP). This altered reaction of neutrophils is thought to account in part for the increased susceptibility of LJP patients to infections by periodontal organisms. Receptors for FMLP are involved in the activation and the subsequent response to certain chemotactic stimuli.

METHODS

In order to determine if this decreased response is due to a genetic variation in the receptor, we directly compared DNA encoding the FMLP receptor from controls matched for gender and race and LJP patients by single-strand conformation polymorphism analysis (SSCP).

RESULTS

Using this technique, we observed a characteristic SSCP pattern in 29 out of 30 patient samples in the FMLP receptor DNA. This pattern differed from those obtained from the 20 control subjects as well as 31 patients with adult periodontitis. DNA sequencing of 30 patients indicated single nucleotide polymorphisms (SNPs) in the FMLP receptor DNA from the LJP patients when compared to 20 controls (P = 0.0005). Two single nucleotide base alterations were consistently seen: either a thymine to cytosine substitution at base 329 in 17 LJP patients or a cytosine to guanine substitution at base 378 in 5 LJP patients. A combination of both alterations were seen in 7 LJP patients. Both alterations resulted in amino acid changes in the second intracellular loop of the receptor, specifically phenylalanine to serine at residue 110 and cysteine to tryptophan at residue 126. This region of the FMLP receptor has recently been shown to play a role in ligand binding and G-protein activation.

CONCLUSIONS

This study suggests that a molecular alteration in the second intracellular loop of the FMLP receptor molecules in LP patients may play a role in the decreased chemotactic activity reported for some LJP patients.

The pathogenesis of periodontal diseases

This informational paper was prepared by the Research, Science, and Therapy Committee of The American Academy of Periodontology, and is intended for the information of the dental profession. The purpose of the paper is to provide an overview of current knowledge relating to the pathogenesis of periodontal diseases. The paper will review biological processes thought to provide protection against periodontal infections. It will further discuss the mechanisms thought to be responsible for both overcoming and subverting such protective mechanisms and those that lead to destruction of periodontal tissues. Since an understanding of pathogenic mechanisms of disease is one foundation upon which new diagnostic and therapeutic modalities are based, the practitioner can use this information to help make decisions regarding the appropriate application of such new modalities in patient care settings.

Linkage disequilibrium of interleukin-1 genetic polymorphisms with early-onset periodontitis

BACKGROUND

Genetic polymorphisms at interleukin (IL)-1alpha and IL-1beta were recently suggested to be associated with severity of adult periodontitis. We evaluated whether these polymorphisms might also be associated with early-onset periodontitis (EOP) in 28 African American families and 7 Caucasian American families with 2 or more affected members.

METHODS

Genomic DNA from peripheral blood was amplified, followed by restriction endonuclease digestion and acrylamide gel electrophoresis to distinguish alleles of different fragment sizes. Genetic epidemiological methods suitable for family data were used that are robust to false-positive findings due to mismatching of cases and controls or mixed subpopulations of different ethnic or geographic origin. The 2 major EOP subtypes, localized juvenile periodontitis (LJP), and generalized early-onset periodontitis (G-EOP, encompassing rapidly progressive periodontitis and generalized juvenile periodontitis), were analyzed both separately and together.

RESULTS

We obtained highly significant evidence of linkage disequilibrium for both African American and Caucasian G-EOP subjects. A similar trend was noted for LJP. The IL- alleles associated with high risk of EOP had been suggested previously to be correlated with low risk for severe adult periodontitis. Disequilibrium with G-EOP was equally strong for smoking and non-smoking subjects. IL-1alpha and IL-1beta polymorphisms were in strong disequilibrium with each other in Caucasians, but not in African Americans. Haplotype analyses evaluating both polymorphisms simultaneously indicated that the IL-1beta variant is likely to be most important for EOP risk. Sibpair linkage analyses, by contrast, provided only marginal support for a gene of very major effect on EOP risk attributable to these IL-1 polymorphisms.

CONCLUSIONS

Recent theoretical analyses indicate that our findings are most consistent with an interpretation of EOP as a complex, oligogenic disorder, with IL-1 genetic variation contributing an important but not exclusive influence on disease risk.

The Fc gammaRIIIA-158F allele is a risk factor for systemic lupus erythematosus

OBJECTIVE

To study whether the Fc gammaRIIIA-158V/F polymorphism, which affects IgG binding affinity, is a risk factor for systemic lupus erythematosus (SLE).

METHODS

We genotyped a group of 70 Caucasian SLE patients for all known Fc gammaR polymorphisms. Of this group, 45 patients (64%) had nephritis. In 35 patients, this diagnosis was confirmed by renal biopsy.

RESULTS

In the total group of 70 SLE patients, the frequency of the Fc gammaRIIIA-158F allele was 0.74, versus 0.57 in healthy controls (P = 0.003). The genotype distribution of the Fc gammaRIIIA-158V/F polymorphism was also significantly different from that of the control population (P = 0.004). The distribution of the other Fc gammaR polymorphisms--Fc gammaRIIA-131R/H, Fc gammaRIIIB-NA(1,2), and Fc gammaRIIIA-48L/R/H--was similar in SLE patients and controls.

CONCLUSION

In our group of SLE patients, only the distribution of the alleles of the Fc gammaRIIIA-158V/F polymorphism was significantly different from that in the control group. This might indicate that macrophage expression of the Fc gammaRIIIA-158F isoform is involved in the disturbed clearance of immune complexes in patients with SLE.

Risk indicators for harboring periodontal pathogens

The risk for harboring 6 putative periodontal pathogens in 4 selected periodontal pockets, in whole saliva, or in either site (i.e., orally) was determined in 52 Caucasians, 49 African-Americans, 48 Asian-Americans, and 50 Hispanics living in Los Angeles. 16S rRNA PCR analysis assessed the presence of Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola. Step-wise regression analysis determined the relationship between the occurrence of each organism and various explanatory variables (risk indicators). Periodontal probing depth or disease severity was positively associated with all 6 study organisms. African-Americans carried an increased risk for harboring P. gingivalis in saliva (odds ratio [OR] 2.95) and orally (OR 2.66), and a reduced risk for harboring T. denticola orally (OR 0.34). Asian-Americans showed an increased risk for harboring A. actinomycetemcomitans in periodontal pockets (OR 6.63) and P. gingivalis in periodontal pockets (OR 5.39), in saliva (OR 5.74), and orally (OR 5.81). Hispanics demonstrated an increased risk for harboring A. actinomycetemcomitans in periodontal pockets (OR 12.27) and P. gingivalis in periodontal pockets (OR 6.07), in saliva (OR 8.72), and orally (OR 7.98). Age was positively associated with the prevalence of P. gingivalis in saliva (OR 1.20) and orally (OR 1.20), and of A. actinomycetemcomitans orally (OR 1.18). The male gender was a risk factor for harboring P. intermedia in periodontal pockets (OR 2.40), in saliva (OR 3.31), and orally (OR 4.25), and for harboring P. nigrescens in saliva (OR 2.85). The longer the subjects resided in the United States, the less likely A. actinomycetemcomitans was detected orally (OR 0.82). Former smokers demonstrated a decreased risk for harboring A. actinomycetemcomitans in saliva (OR 0.23). Current smokers displayed an increased risk for harboring T. denticola in periodontal pockets (OR 4.61). The number of dental visits in the past 10 years was inversely related to the prevalence of P. intermedia orally (OR 0.96). The prevalence of P. intermedia in saliva was positively associated with the length of time from the last dental visit (OR 1.01). This study suggests that genetic and/or environmental factors predispose subjects to oral colonization by putative periodontal pathogens.

Crevicular fluid level of beta-glucuronidase in relation to clinical periodontal parameters and putative periodontal pathogens in early-onset periodontitis

Analysis of beta-glucuronidase (betaG) in the gingival crevicular fluid (GCF) provides an indication of neutrophil influx into the crevicular environment. The aim of this study was to test the hypotheses that: (1) betaG is significantly elevated in individuals with early-onset periodontitis (EOP) and that betaG activity correlates with disease severity; and (2) betaG level may reflect the local bacterial challenge in the gingival crevice. The study subjects consisted of a sub-sample of individuals examined in the National Survey of Oral Health of United States Children, which was undertaken during the 1986/87 school year. A total of 249 individuals were selected based on presence or absence of clinical attachment loss at baseline. The individuals were examined a second time 6 years later and the clinical attachment loss was assessed, and subgingival plaque and GCF were collected. The subjects were classified into 3 types of EOP and a control group. BetaG activity in the GCF and the levels of 7 putative micro-organisms in the pocket were assessed. The generalized EOP group had the highest betaG activity, followed by the localized and incidental EOP groups, and the controls, respectively. There was a significant increase in betaG activity with the increase in probing depth. Also, sites with bleeding on probing had a significantly higher betaG activity than sites without bleeding. However, the effect of gingival inflammation on betaG activity was more evident in the generalized and localized EOP groups. Sites harboring high levels of one or more of the micro-organisms tended to have high betaG activity. There were moderate differences between the organisms with respect to their effect on betaG activity, but sites with high numbers of Porphyromonas gingivalis, Prevotella intermedia, or Treponema denticola also had the highest betaG activity. The present findings suggest that betaG activity in GCF from patients with EOP can be of value in the early identification of individuals at higher risk of developing EOP The findings also suggest that host mechanisms leading to higher betaG activity in EOP represent systemic responses and are only partly related to the presence of local factors at the site-level.

Genetic variations in cytokine expression: a risk factor for severity of adult periodontitis

Periodontitis is a collection of chronic inflammatory diseases that are caused by specific bacteria. The bacteria activate inflammatory mechanisms in the periodontal tissues that destroy collagen and bone that support the teeth. Although bacteria are essential for the initiation of periodontitis, the quantity and types of bacteria have not been sufficient to explain the differences in disease severity. In recent years, it has become evident that for many common chronic diseases, there are modifying factors that do not cause the disease but rather amplify some disease mechanisms to make the clinical condition more severe. There are now data to suggest that a few factors which amplify the inflammatory process make people susceptible to an increased severity of periodontitis. Studies of untreated disease in Sri Lanka identified 3 patterns of disease progression. Studies in twins suggested that part of the clinical characteristics of periodontitis may be explained by genetic factors, but previous attempts to identify genetic markers for periodontitis have been unsuccessful Some genetic variations (polymorphisms) are commonly found in our population and represent a mechanism by which individuals may exhibit variations within the range of what is considered biologically normal. Since certain cytokines are key regulators of the inflammatory response and are important in periodontitis, we investigated the relationship between genetic variations associated with cytokine production and periodontitis severity. There are several polymorphisms in the cluster of genes that influence IL-1 biological activity. In recent clinical trials, two of these polymorphisms, when found together, have been associated with a significant increase in the risk for severe generalized periodontitis. Genetic association with periodontitis was evident only when smokers were excluded from the analysis, confirming the importance of smoking, and suggesting that both smoking and the IL- I genotype are independent factors in severe periodontitis. It is notable that 1 polymorphism associated with severe periodontitis in our study is also known to correlate with a 2- to 4-fold increase in IL-1 beta production. These findings are consistent with the current model of how genetic factors influence common chronic diseases. If we apply this model to periodontitis, it would involve the following: 1) a disease-initiating factor that would undoubtedly be specific bacteria such as Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans. and Bacteroides forsythus: and 2) modifiers of disease mechanisms that account for the clinical severity, including smoking, the IL-I genotype, certain systemic diseases, and psychosocial stress. The association of the IL-I genotype with severe periodontitis is consistent with several lines of periodontal research. Several studies have suggested there is a substantial genetic influence in periodontal disease. Although specific genetic markers have been identified in the uncommon juvenile forms of periodontitis, previous studies of specific genetic markers in adults with periodontitis have not been encouraging. Many investigators have, however, demonstrated a role for IL-1 in the initiation and progression of periodontitis. For example, IL-1 activates the degradation of the extracellular matrix and bone of the periodontal tissues, and elevated tissue or gingival fluid levels of IL-1 beta have been repeatedly associated with periodontitis. In addition, IL-1 is a strong enhancer of tissue levels of PGE2 and TNF-alpha. The association of severe periodontitis with smoking and the IL-1 genotype suggest a role for these factors in the pathogenesis of periodontitis. The finding that host modifying factors are associated with severe periodontitis suggest a biological mechanism by which some individuals, if challenged by bacterial accumulations, may have a more vigorous immunoinflammatory response, leading to more severe clinical disease. (ABSTRACT

Models to evaluate the role of stress in periodontal disease

We evaluated the association of stress,distress, and coping behaviors with periodontal disease in 1,426 subjects, aged 25 to 74, in Erie County, NY, Demographic characteristics, medical and dental history, and tobacco and alcohol consumption, as well as clinical assessments of supragingival plaque, subgingival flora, gingival bleeding, calculus, probing depth, clinical attachment level (CAL), and radiographic alveolar bone loss (ABL) were obtained for each subject. Subjects also completed a set of 5 psychosocial instruments that measured life events, daily strains, hassles and uplifts, distress, and coping behaviors. Internal consistencies of all subscales on the instruments were high, with Cronbach's alpha ranging from 0.88 to 0.99. Logistic regression indicated that financial strain was significantly associated with greater attachment and alveolar bone loss (OR 1.70; 95% CI, 1.09-2.65; and 1.68; 95% CI, 1.20-2.37, respectively) after adjusting for age, gender, and smoking. When those with financial strain were stratified with respect to coping behaviors, it was found that those who exhibited high emotion-focused coping (inadequate coping) had and even higher risk of having more severe attachment loss (OR 2.24; 95% CI, 1.15-4.38) and alveolar bone loss (OR 1.91; 95% CI, 1.15-3.17) than those with low levels of financial strain within the same coping group, after adjustment for age, gender, and cigarette smoking. After further adjusting for number of visits to the dentist, those with financial strain who were high emotion-focused copers still had higher levels of periodontal disease based on CAL (OR 2.12; 95% CI, 1.07-4.18). In contrast, subjects with high levels of financial strain who reported high levels of problem-based coping (good coping) had no more periodontal disease than those with low levels of financial strain. Salivary cortisol levels were higher in a test group exhibiting severe periodontitis, a high level of financial strain, and high emotion-focused coping, as compared to a control group consisting of those with little or no periodontal disease, low financial strain, and low levels of emotion-focused coping (11.04 +/-4.4 vs/ 8.6 +/- 4.1 nmol/L salivary cortisol, respectively). These findings suggest that psychosocial measures of stress associated with financial strain are significant risk indicators for periodontal disease in adults. Further prospective studies are needed to help establish the time course of stress, distress, and inadequate coping on the onset and progression of periodontal disease, as well as to evaluate the mechanisms by which stress exerts its effects on periodontal infections.

Serum IgG2 level, Gm(23) allotype and FcgammaRIIa and FcgammaRIIIb receptors in refractory periodontal disease

The purpose of this investigation was to compare the levels of serum IgG2, the frequency of detection of Gm(23)-negative allotype and frequency of detection of FcgammaRIIa and FcgammaRIIIb receptor haplotypes in 32 refractory, 54 successfully treated and 27 periodontally healthy individuals. Refractory subjects showed mean full mouth attachment loss and/or >3 sites with attachment loss >2.5 mm within 1 year after both scaling and root planing, and surgery plus systemically administered tetracycline. Successfully treated subjects showed mean attachment level gain and no sites with attachment loss >2.5 mm 1 year post-therapy. Periodontally healthy subjects exhibited no pocket depth or attachment level >3 mm, and no evidence of progressing disease during 1 year of monitoring. Blood was obtained from each subject at baseline. Serum IgG2 and Gm(23) allotype were determined using radial immunodiffusion. DNA was extracted from whole blood and the FcgammaR genotypes determined using PCR and allele specific oligonucleotide probes. Significance of differences among clinical groups were sought using the Kruskal-Wallis or chi-square tests. Associations between 2 or more variables were tested using regression analysis. Refractory subjects exhibited higher mean attachment loss and pocket depth than successfully treated or periodontally healthy subjects. Smoking status did not differ significantly among groups. No significant differences in serum IgG2 levels and frequency of detection of Gm(23)-negative allotype were observed among the clinical groups. Serum IgG2 level was positively associated with the number of serum antibody responses to subgingival species (r=0.51, p<0.001). Subjects with the Gm(23)-negative allotype exhibited lower mean levels of serum IgG2 (3.06+/-0.3 versus 3.9+/-0.2, p<0.01) and mean number of serum antibodies to subgingival species (17.7+/-1.7 versus 23.3+/-1.4, p<0.05) than allotype positive individuals. No significant differences in FcgammaR haplotype distribution were observed among the 3 clinical groups. Associations of serum IgG2 level, Gm(23) allotype, FcgammaRIIa and FcgammaRIIIb receptor haplotypes and smoking status were weakly related or not related to clinical status. This lack of relationship may have been due to a reality of no relationship, or the inadvertent pooling of subjects where these factors were of primary importance with subjects in whom these factors played a less important role.

Hyper-reactive peripheral neutrophils in adult periodontitis: generation of chemiluminescence and intracellular hydrogen peroxide after in vitro priming and FcgammaR-stimulation

We have earlier reported a higher Fcgamma-receptor (FcgammaR)-mediated generation of reactive oxygen species, measured as luminol-enhanced chemiluminescence (CL) from peripheral neutrophils in adult periodontitis patients. The aims of this study were to confirm our previous results and to elucidate the mechanism of this phenomenon by measuring CL in parallel with the intracellular production of hydrogen peroxide, after stimulation with opsonized bacteria. To determine whether the higher CL was associated with altered responsiveness to priming, the cells were preincubated with tumor necrosis factor alpha (TNFalpha) and lipopolysaccharide (LPS). While CL was significantly higher in subjects with periodontitis, there was no difference in hydrogen peroxide production between the patients and the controls, indicating that the hyperreactivity is related to the generation of other oxygen species than H2O2 and/or to processes in the outer cell membrane. The responsiveness to priming with LPS on CL was slightly but not significantly higher in the periodontitis group, suggesting that priming could be of value for distinguishing subjects with periodontitis. When assaying intracellular production of H2O2, TNFalpha and LPS had both a priming and an activating effect. There were no significant differences between the two groups. In conclusion, this study shows a higher FcgammaR-mediated CL of peripheral neutrophils from adult patients with periodontitis, thus confirming our earlier results. The hyperreactivity seems to be related to the outer cell membrane or to oxygen species other than H2O2.

Opsonization of Actinobacillus actinomycetemcomitans by immunoglobulin G antibodies to the O polysaccharide of lipopolysaccharide

Sera of localized juvenile periodontitis (LJP) patients colonized by Actinobacillus actinomycetemcomitans serotype b often contain markedly elevated levels of immunoglobulin G (IgG) antibodies to serospecific determinants in the O polysaccharide of lipopolysaccharide (LPS), as well as to outer membrane proteins of this species. IgG antibodies in LJP sera are known to opsonize A. actinomycetemcomitans for subsequent phagocytosis and killing by human neutrophils. The objective of this study was to determine whether outer membrane proteins or serospecific determinants in LPS are the primary target for opsonic IgG antibodies in LJP sera. An A. actinomycetemcomitans serotype b O-polysaccharide affinity column was constructed and subsequently used to purify LPS-specific IgG antibodies from LJP serum. The affinity-purified anti-LPS IgG antibodies were enriched in content of IgG2 (66.2%, compared with 37.0% in the total IgG fraction) and were immunospecific for A. actinomycetemcomitans serotype b LPS. In an opsonophagocytic assay using neutrophils from donors who were homozygous for the H131 allotype of Fcy receptor IIa (CD32), it was found that LPS-specific IgG antibodies exhibited substantially greater opsonic activity toward A. actinomycetemcomitans serotype b than an LJP IgG fraction that was depleted of LPS-reactive antibodies but contained antibodies against outer membrane proteins of this species. The results of this study indicate that serospecific determinants in the O polysaccharide of A. actinomycetemcomitans serotype b are a principal target for opsonic antibodies in sera of LJP subjects.

Saliva: a convenient source of DNA for analysis of bi-allelic polymorphisms of Fc gamma receptor IIA (CD32) and Fc gamma receptor IIIB (CD16)

Genetic polymorphisms of low-affinity IgG Fc receptors (Fc gamma R) have been found to influence binding of human IgG subclass antibodies, and may influence susceptibility to certain types of infectious and autoimmune diseases. Phenotypic and/or genotypic analyses of Fc gamma R polymorphisms have traditionally employed peripheral venous blood as a source of leukocytes or genomic DNA, respectively. The present study was undertaken to determine whether human salivary DNA is a suitable alternative to DNA extracted from blood for genetic analysis of FC gamma R allelic polymorphisms. Genomic DNA was extracted from whole saliva of 69 healthy adult volunteers using a commercial DNA purification kit. The average quantity of genomic DNA isolated per ml of saliva was 19.2 +/- 14.1 micrograms. To assess intrasubject variation in yield of salivary DNA, ten saliva samples were collected from a single donor over a 3-month period. The average yield of DNA recovered from these samples was 25.2 +/- 13.7 micrograms. Volumes of saliva as small as 100 microliters, as well as saliva samples stored at -70 degrees C for prolonged periods (up to 6 years), provided DNA in amounts sufficient for PCR-based genetic analysis. Two comparative PCR assays were performed using DNA extracted from both peripheral blood and saliva from a number of individuals. The assays were able to detect a single nucleotide substitution (G-->A) in the Fc gamma RIIA gene, as well as two codominant alleles encoding the NA polymorphism in Fc gamma RIIIB, respectively. Furthermore, Fc gamma RIIA and Fc gamma RIIIB genotype results were confirmed by quantitative flow cytometry using specific monoclonal antibodies. Complete concordance was achieved between the typing results of our salivary DNA, and blood DNA-based assays. Therefore, saliva appears to be an excellent source of DNA for studies of Fc gamma RIIA and Fc gamma RIIIB polymorphisms.

Relevance of immunoglobulin G Fc receptor polymorphism to recurrence of adult periodontitis in Japanese patients

Polymorphonuclear neutrophil (PMN) phagocytic function has been shown to be impaired in some patients with periodontitis. PMN constitutively express members of two immunoglobulin G receptor (Fc gammaR) classes: Fc gammaRIIa (CD32) and Fc gammaRIIIb (CD16). Both receptors exhibit genetically determined structural and functional biallelic polymorphisms, which have been shown to influence PMN phagocytic function. In this study, we assessed the relevance of these Fc gammaR polymorphisms to susceptibility to adult periodontitis and recurrence rate. The distribution of Fc gammaRIIa and Fc gammaRIIIb genotypes of 100 Japanese patients with adult periodontitis during follow-up was compared to the distribution of genotypes in 105 race-matched healthy controls. No significant skewing of distributions of Fc gammaRIIa and Fc gammaRIIIb genotypes was observed between patients and controls. Notably, however, a significant overrepresentation of the Fc gammaRIIIb-NA2 allotype was found in patients with disease recurrence (P < 0.05; odds ratio, 4.29; 95% confidence interval, 1.19 to 16.24). Moreover, the annual rate of recurrence was significantly higher in patients with the Fc gammaRIIIb-NA2/NA2 and Fc gammaRIIIb-NA1/NA2 genotypes than in Fc gammaRIIIb-NA1/NA1 individuals (P < 0.05). Fc gammaRIIa-R/R131 individuals also exhibited higher recurrence rates, though the difference was not statistically significant (P = 0.06). These results suggest that the Fc gammaRIIIb-NA2 allotype represents a risk factor for recurrence of adult periodontitis.

FcγRIIIa-158V/F Polymorphism Influences the Binding of IgG by Natural Killer Cell FcγRIIIa, Independently of the FcγRIIIa-48L/R/H Phenotype

We analyzed a genetic polymorphism of Fcγ receptor IIIa (CD16) that is present on position 158 (Phe or Val) in the membrane-proximal, IgG-binding domain. With a polymerase chain reaction–based allele-specific restriction analysis assay we genotyped 87 donors and found gene frequencies of 0.57 and 0.43 for FcγRIIIA-158F and −158V, respectively. A clear linkage was observed between the FcγRIIIA-158F and −48L genotypes on the one hand and the FcγRIIIA-158V and −48H or −48R genotypes on the other hand (χ2 test; P &lt; .001). To determine the functional consequences of this FcγRIIIa-158V/F polymorphism, we performed IgG binding experiments with natural killer (NK) cells from genotyped donors. All donors were also typed for the recently described triallelic FcγRIIIa-48L/R/H polymorphism. NK cells were treated with lactic acid to remove cell-associated IgG. FcγRIIIaNK158F bound significantly less IgG1, IgG3, and IgG4 than did FcγRIIIaNK-158V, irrespective of the FcγRIIIa-48 phenotype. Moreover, freshly isolated NK cells from FcγRIIIa-158VV individuals carried significantly more cytophilic IgG than did NK cells from FcγRIIIa-158FF individuals. In addition, CD16 monoclonal antibody (MoAb) MEM154 bound more strongly to FcγRIIIa-158V, compared with -158F, again independently of the FcγRIIIa-48 phenotype. The binding of MoAb B73.1 was not influenced by the FcγRIIIa-158V/F polymorphism, but proved to depend solely on the amino acid present at position 48 of FcγRIIIa. In conclusion, the previously reported differences in IgG binding among the three FcγRIIIa-48L/R/H isoforms are a consequence of the linked, biallelic FcγRIIIa-158V/F polymorphism at amino-acid position 158.

FcγRIIIa-158V/F Polymorphism Influences the Binding of IgG by Natural Killer Cell FcγRIIIa, Independently of the FcγRIIIa-48L/R/H Phenotype

We analyzed a genetic polymorphism of Fcγ receptor IIIa (CD16) that is present on position 158 (Phe or Val) in the membrane-proximal, IgG-binding domain. With a polymerase chain reaction–based allele-specific restriction analysis assay we genotyped 87 donors and found gene frequencies of 0.57 and 0.43 for FcγRIIIA-158F and −158V, respectively. A clear linkage was observed between the FcγRIIIA-158F and −48L genotypes on the one hand and the FcγRIIIA-158V and −48H or −48R genotypes on the other hand (χ2 test; P < .001). To determine the functional consequences of this FcγRIIIa-158V/F polymorphism, we performed IgG binding experiments with natural killer (NK) cells from genotyped donors. All donors were also typed for the recently described triallelic FcγRIIIa-48L/R/H polymorphism. NK cells were treated with lactic acid to remove cell-associated IgG. FcγRIIIaNK158F bound significantly less IgG1, IgG3, and IgG4 than did FcγRIIIaNK-158V, irrespective of the FcγRIIIa-48 phenotype. Moreover, freshly isolated NK cells from FcγRIIIa-158VV individuals carried significantly more cytophilic IgG than did NK cells from FcγRIIIa-158FF individuals. In addition, CD16 monoclonal antibody (MoAb) MEM154 bound more strongly to FcγRIIIa-158V, compared with -158F, again independently of the FcγRIIIa-48 phenotype. The binding of MoAb B73.1 was not influenced by the FcγRIIIa-158V/F polymorphism, but proved to depend solely on the amino acid present at position 48 of FcγRIIIa. In conclusion, the previously reported differences in IgG binding among the three FcγRIIIa-48L/R/H isoforms are a consequence of the linked, biallelic FcγRIIIa-158V/F polymorphism at amino-acid position 158.

The role of Actinobacillus actinomycetemcomitans in the pathogenesis of periodontal disease

Periodontal disease consists of a constellation of complex bacterium-host cell interactions. One example of these oral pathogens, Actinobacillus actinomycetemcomitans, has an arsenal of putative virulence determinants that account for its potent periodontopathogenicity. Of these determinants, invasion of host cells and leukocytotoxicity have been studied extensively.

Clinical relevance of Fc gamma receptor polymorphisms

Human IgG receptors are very heterogeneous and we currently distinguish three Fc gamma receptor classes specifying at least 12 receptor isoforms. On top of this complexity, Fc gamma R are further found to differ between different individuals. Polymorphisms have been identified for all three Fc gamma R classes. The best-studied ones represent allelic variation of Fc gamma RIIa (CD32) and Fc gamma RIIIb (CD16). The Fc gamma RIIa polymorphism is now considered to be a heritable risk factor for autoimmune and infectious diseases, and support for a relevant role of the IIIb polymorphism has also been obtained. A detailed analysis of the exact contribution of each of these Fc gamma R polymorphisms in relation to previously implicated risk factors should unravel the pathophysiological importance of Fc gamma R polymorphisms in the near future.