Unique intronic variations of HLA-DQ beta gene in early-onset periodontitis

Periodontal disease immunology: 'double indemnity' in protecting the host

During the last two to three decades our understanding of the immunobiology of periodontal disease has increased exponentially, both with respect to the microbial agents triggering the disease process and the molecular mechanisms of the host engagement maintaining homeostasis or leading to collateral tissue damage. These foundational scientific findings have laid the groundwork for translating cell phenotype, receptor engagement, intracellular signaling pathways and effector functions into a 'picture' of the periodontium as the host responds to the 'danger signals' of the microbial ecology to maintain homeostasis or succumb to a disease process. These findings implicate the chronicity of the local response in attempting to manage the microbial challenge, creating a 'Double Indemnity' in some patients that does not 'insure' health for the periodontium. As importantly, in reflecting the title of this volume of Periodontology 2000, this review attempts to inform the community of how the science of periodontal immunology gestated, how continual probing of the biology of the disease has led to an evolution in our knowledge base and how more recent studies in the postgenomic era are revolutionizing our understanding of disease initiation, progression and resolution. Thus, there has been substantial progress in our understanding of the molecular mechanisms of host-bacteria interactions that result in the clinical presentation and outcomes of destructive periodontitis. The science has embarked from observations of variations in responses related to disease expression with a focus for utilization of the responses in diagnosis and therapeutic outcomes, to current investigations using cutting-edge fundamental biological processes to attempt to model the initiation and progression of soft- and hard-tissue destruction of the periodontium. As importantly, the next era in the immunobiology of periodontal disease will need to engage more sophisticated experimental designs for clinical studies to enable robust translation of basic biologic processes that are in action early in the transition from health to disease, those which stimulate microenvironmental changes that select for a more pathogenic microbial ecology and those that represent a rebalancing of the complex host responses and a resolution of inflammatory tissue destruction.

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.

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.

Genes and gene polymorphisms associated with periodontal disease

The scientific literature during the last ten years has seen an exponential increase in the number of reports claiming links for genetic polymorphisms with a variety of medical diseases, particularly chronic immune and inflammatory conditions. Recently, periodontal research has contributed to this growth area. This new research has coincided with an increased understanding of the genome which, in turn, has permitted the functional interrelationships of gene products with each other and with environmental agents to be understood. As a result of this knowledge explosion, it is evident that there is a genetic basis for most diseases, including periodontitis. This realization has fostered the idea that if we can understand the genetic basis of diseases, genetic tests to assess disease risk and to develop etiology-based treatments will soon be reality. Consequently, there has been great interest in identifying allelic variants of genes that can be used to assess disease risk for periodontal diseases. Reports of genetic polymorphisms associated with periodontal disease are increasing, but the limitations of such studies are not widely appreciated. While there have been dramatic successes in the identification of mutations responsible for rare genetic conditions, few genetic polymorphisms reported for complex genetic diseases have been demonstrated to be clinically valid, and fewer have been shown to have clinical utility. Although geneticists warn clinicians on the over-enthusiastic use and interpretation of their studies, there continues to be a disparity between the geneticists and the clinicians in the emphasis placed on genes and genetic polymorphism associations. This review critically reviews genetic associations claimed for periodontal disease. It reveals that, despite major advances in the awareness of genetic risk factors for periodontal disease (with the exception of periodontitis associated with certain monogenetic conditions), we are still some way from determining the genetic basis of both aggressive and chronic periodontitis. We have, however, gained considerable insight into the hereditary pattern for aggressive periodontitis. Related to our understanding that it is autosomal-dominant with reduced penetrance comes a major clinically relevant insight into the risk assessment and screening for this disease, in that we appreciate that parents, offspring, and siblings of patients affected with aggressive periodontitis have a 50% risk of this disease also. Nevertheless, we must exercise caution and proper scientific method in the pursuit of clinically valid and useful genetic diagnostic tests for chronic and aggressive periodontitis. We must plan our research using plausible biological arguments and carefully avoid the numerous bias and misinterpretation pitfalls inherent in researching genetic associations with disease.

Inter-relationships between rheumatoid arthritis and periodontal disease. A review

This review considers the considerable similarities between periodontal disease and rheumatoid arthritis (RA). While the etiology of these two diseases may differ, the underlying pathogenic mechanisms are remarkably similar and it is possible that individuals manifesting both periodontitis and RA may suffer from a unifying underlying systemic dysregulation of the inflammatory response. In light of these findings, the implications for the use of disease-modifying medications in the management of these two chronic inflammatory conditions is apparent. Further longitudinal studies and medication-based intervention studies are required to determine just how closely these two conditions are allied.

HLA-A, B, Cw, DRB1, DRB3/4/5, DQB1 in German patients suffering from rapidly progressive periodontitis (RPP) and adult periodontitis (AP)

BACKGROUND/AIM

There is growing indication that differences in host response determine susceptibility and resistance to periodontal disease. Particularly, the effect of histocompatibility antigens (HLA) on early onset periodontitis (EOP) has been studied. As most of the results are not conclusive and to date no report has been done on German patients, the aim of this study was to investigate the distribution of HLA alleles in a group of 50 German RPP patients and 102 German AP patients and to compare them to 102 control probands without periodontitis.

METHODS

Diagnosis was established according to standardised clinical criteria. HLA typing was performed using serologic and molecular biologic (PCR-SSP) techniques.

RESULTS

Compared to the controls, RPP patients had a significantly higher frequency of HLA-DRB1*13 and a significantly lower frequency of HLA-DRBblank*(non-DRB3/4/5). AP patients showed a significantly increased occurrence of HLA-B*14 and -Cw*08 as well as a significantly decreased frequency of HLA-A*03. In both patient groups HLA-A*11 and -A*29 had an increased frequency and HLA-A*31 and -A*30/31 were decreased. These differences were statistical significant in the whole patient group (RPP + AP).

CONCLUSIONS

Based on modern DNA techniques the present study shows an association of HLA to both RPP and AP. Certain HLA alleles seem to be associated with susceptibility or resistance to periodontitis in general. However, before this knowledge can be used for differential diagnosis or prognosis, further investigations are necessary.

Sister chromatid exchange (SCE) analysis in periodontitis

BACKGROUND

Emerging data indicate that genetic factors may be associated with the etiopathogenesis of aggressive periodontitis. Sister chromatid exchange (SCE) is a sensitive method that might reflect an instability of DNA or a deficiency of DNA repair. The aim of the present study was to investigate SCE frequency of patients with different forms of periodontal disease and to determine whether this cytogenetic marker in patients with aggressive periodontitis can be differential compared to patients with chronic periodontitis and control subjects.

METHODS

SCE was analysed in peripheral blood lymphocyte chromosomes of 13 patients with generalised aggressive periodontitis (G-AP), 10 patients with chronic periodontitis (CP) and 10 control subjects. The periodontal parameters of probing depth, clinical attachment level, the presence of bleeding on probing and plaque were recorded. Peripheral blood lymphocytes obtained from both patient groups and control subjects were cultured in the presence of 5-Bromo-2-deoxyuridine in complete darkness for 72 h. For scoring SCE frequency, 20 metaphases were studied from each donor.

RESULTS

The frequency of SCE was found to be 6.7 +/- 0.9 per cell in patients with G-AP, 6.5 +/- 1.5 per cell in CP patients and 6.9 +/- 1.1 in control subjects. No statistically significant differences were found between groups (p > 0.05).

CONCLUSIONS

The data indicate that there the cyotogenetic damage in the aggressive type of periodontal disease is not greater than in chronic periodontitis and control subjects. Although no aberrant cytogenetic damage was observed in different forms of periodontitis compared to control, this does not discount the importance of other genetic factors in the pathogenesis of periodontal disease.

Microbiological, immunological and genetic factors in family members with periodontitis as a manifestation of systemic disease, associated with hematological disorders

The microflora, immunological profiles of host defence functions, and human leukocyte antigen (HLA) findings are reported for a mother, son and daughter who were diagnosed as having 'periodontitis as a manifestation of systemic diseases, associated with hematological disorders'. Examinations were made of the bacterial flora from the periodontal pocket, neutrophil chemotaxis, neutrophil phagocytosis, and the genotypes (DQB1) and serotypes (DR locus) of HLA class II antigens. Phenotypic analyses of the peripheral lymphocytes were also conducted. The subgingival microflora from the mother was dominated by Gram-negative rods, especially Porphyromonas endodontalis, Prevotella intermedia/Prevotella nigrescens and Fusobacterium nucleatum. Subgingival microflora samples from the son and daughter were dominated by Gram-positive cocci and Gram-positive rods. Through the use of polymerase chain reaction, Campylobacter rectus and Capnocytophaga gingivalis were detected in all subjects, whereas Porphyromonas gingivalis, P. intermedia, and Treponema denticola were not detected in any subjects. All three subjects showed a remarkable level of depressed neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine, although their phagocyte function levels were normal, in comparison to healthy control subjects. Each subject had the same genotype, HLA-DQB1*0601, while the mother had HLA-DR2 and HLA-DR8, and the son and daughter had HLA-DR2 only. In summary, the members of this family showed a similar predisposition to periodontitis with regard to certain host defence functions. It is suggested that the depressed neutrophil chemotaxis that was identified here could be a significant risk factor for periodontitis in this family.

Heterogeneity of host immunological risk factors in patients with aggressive periodontitis

BACKGROUND

The pathogenesis of early-onset periodontitis (EOP) can be explained by various host risk factors. Previous studies have focused on a single (among many possible) immunological risk factor and the association among the factors has not been assessed. We comprehensively investigated the associations among multiple host immunological risk factors in EOP patients to further elucidate their role in the pathogenesis of EOP.

METHODS

Sixty-eight EOP patients (50 generalized EOP, 18 localized EOP), 51 EOP-suspected patients (S-EOP), 43 adult periodontitis (AP) patients, and 36 periodontally healthy subjects (HS) participated in this cross-sectional study. We examined peripheral neutrophil functions, phenotypic and functional characterization of peripheral lymphocytes (lymphocyte subsets, T-cell proliferative activity), cytokine productivity (interleukin [IL]-1, IL-2, tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma, IL-4 and IL-6), serum immunoglobulin G (IgG) antibody titers against 12 periodontal bacteria, and HLA class II genotypes.

RESULTS

G-EOP, S-EOP, and AP patient groups showed significantly lower percentages of pan T cells and CD8-positive cells (P < 0.02) compared with the HS group. L-EOP patients showed depressed IL-4 and TNF-alpha productivity compared with the HS group (P < 0.02). The EOP group showed significantly elevated antibody levels against Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, and Fusobacterium nucleatum compared with the HS group (P < 0.05). The frequency with DQB1*0503 was significantly higher in the EOP patient group than the HS group (P = 0.045) due to the higher frequency in L-EOP patients than the HS group (P = 0.035). There were wide interindividual variations in each of the tests among patient and HS groups; however, EOP patients showed wider intradiagnostic group variations in certain host defensive cell functions than the other groups. There were some EOP patients who showed extremely low or high values in some tests; the EOP patients could be further divided into subgroups according to their host defensive and immunological profiles. However, there was heterogeneity in some of the other host immunological tests even in the subgroups.

CONCLUSIONS

The association of host immunological risk factors in EOP patients is widely varied and more complex than previously thought. These results indicate the difficulty of explaining the pathogenesis of EOP based on a single host risk factor and also emphasize the importance of critical assessment of not only EOP patient groups, but also individual patients.

Evidence of a substantial genetic basis for risk of adult periodontitis

BACKGROUND

A few previous studies have suggested that risk for adult periodontitis (AP) has a genetic (heritable) component. We estimated genetic and environmental variances and heritability for gingivitis and adult periodontitis using data from twins reared together.

METHODS

One hundred seventeen (117) pairs of adult twins (64 monozygotic [MZ] and 53 dizygotic [DZ] pairs) were recruited. Probing depth (PD), attachment loss (AL), plaque, and gingivitis (GI) were assessed on all teeth by two examiners. Measurements were averaged over all sites, teeth, and examiners. Extent of disease in subjects was defined at four thresholds: the percentage of teeth with AL > or = 2, AL > or = 3, PD > or = 4, or PD > or = 5 mm. Genetic and environmental variances and heritability were estimated using path models with maximum likelihood estimation techniques.

RESULTS

MZ twins were more similar than DZ twins for all clinical measures. Statistically significant genetic variance was found for both the severity and extent of disease. AP was estimated to have approximately 50% heritability, which was unaltered following adjustments for behavioral variables including smoking. In contrast, while MZ twins were also more similar than DZ twins for gingivitis scores, there was no evidence of heritability for gingivitis after behavioral covariates such as utilization of dental care and smoking were incorporated into the analyses.

CONCLUSIONS

These results confirm previous studies and indicate that approximately half of the variance in disease in the population is attributed to genetic variance. The basis for the heritability of periodontitis appears to be biological and not behavioral in nature.

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.

Low prevalence of a periodontitis-associated interleukin-1 composite genotype in individuals of Chinese heritage

BACKGROUND

Polymorphisms in the interleukin-1 (IL-1) gene cluster have been associated with an increased risk of developing certain diseases. A specific composite genotype of IL-1A and IL-1B polymorphisms, consisting of allele 2 of both IL-1A +4845 and IL-1B +3954 (formerly +3953) has been associated with an increased risk of severe adult periodontitis. Approximately 30% of the European population carry this genotype. The prevalence of the above IL-1A and IL-1B composite genotype in populations of different ethnic origins is unknown. Therefore, the primary aim of this study was to determine the prevalence of the IL-1 composite genotype in individuals of Chinese heritage, since epidemiologic studies indicate that periodontitis is widespread among ethnic Chinese. An additional aim was to evaluate if there was an association between the composite genotype and the severity of periodontal disease.

METHODS

A convenience sample of 300 volunteers of Chinese heritage (ages 21 to 69 years) received a periodontal examination including full-mouth clinical attachment loss measurements, probing depths, plaque index scores, and bleeding on probing. Blood was collected from a fingerstick and placed on a blotting paper card. The blood samples were analyzed for IL-1A +4845 and IL-1B +3954 polymorphisms using polymerase chain reaction (PCR)-based methods.

RESULTS

Only 7 of the 300 subjects (2.3%) carried the composite IL- 1 genotype consisting of allele 2 of both IL-1A +4845 and IL-1B +3954. Allele 2 of the IL-1A +4845 polymorphism was carried by 17.0% (51/300) of the subjects; of these, only 2 were homozygous. Allele 2 of the IL-1B +3954 polymorphism was much rarer with only 3.3% (10/300) of the study population carrying this marker. All of the people who carried the IL-1B polymorphism were heterozygous. Too few of the subjects were positive for the IL-1 composite genotype to establish any relationship with the susceptibility to periodontitis.

CONCLUSIONS

It was concluded that the prevalences of both IL-1A and IL-1B polymorphisms are dramatically lower in Chinese than those reported for Europeans. Findings from this study bring into question the usefulness of the composite genotype of allele 2 of both IL-1A +4845 and IL-1B +3954 as a method for determining the susceptibility of Chinese patients to adult periodontitis.

HLA genetics for diagnosis of susceptibility to early-onset periodontitis

Human leukocyte antigens (HLA) are essential in the recognition of foreign antigens in humoral immune response, which is genetically predetermined. Susceptibility to certain diseases that involve the immune response has been studied in relation to distinct HLA types. Although some diseases have been found to correlate to specific HLA loci positively, it has been difficult to isolate HLA types that predispose patients to periodontal destruction. Here, we review the current knowledge and recent advances in HLA genetics and its biology, which determine susceptibility to early-onset periodontitis (EOP). The HLA-DRB1*1501-DQB1*0602 genotype has been found with increasing frequency in EOP patients. This HLA genotype expresses aspartic acid at position 57 and glycine at position 70 on the DQ beta chain, suggesting a capability to bind certain bacterial antigens. The T cell response against the outer membrane protein (Ag53) of Porphyromonas gingivalis was examined via this HLA genotype. Strong T cell response against Ag53 p141-161 was inhibited partially by anti-DR antibody, but not by anti-DQ antibody. Possible host and bacterial peptides capable of binding DRB1*1501 were elucidated when the peptide sequence was compared to gene and protein databases. These results suggest that patients who have the HLA-DRB1*1501-DQB1*0602 genotype may have an accelerated T cell response to certain periodontopathic bacteria such as P. gingivalis in hyperimmune reactions and thus increased susceptibility to EOP.

No association with HLA-DQB1 in European Caucasians with early-onset periodontitis

Periodontitis is a chronic inflammatory disease of the supporting tissues of the teeth that may ultimately result in tooth loss. The human leukocyte antigen (HLA) complex plays an important role in immune responsiveness and may be involved in antigen recognition of periodontal pathogens. A recent report of a Japanese population found an association between an atypical BamHI site in the HLA-DQB1 gene and a severe form of early-onset periodontitis (EOP). The aim of the present study was to test for the existence of the site in a European Caucasian EOP population using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. No statistically significant differences were found between the patients and controls with regard to the presence of the BamHI site. It was concluded that this lack of association could reflect racial genetic variation in HLA allelic frequencies.

Genetic aspects of dental disorders

This paper reviews past and present applications of quantitative and molecular genetics to dental disorders. Examples are given relating to craniofacial development (including malocclusion), oral supporting tissues (including periodontal diseases) and dental hard tissues (including defects of enamel and dentine as well as dental caries). Future developments and applications to clinical dentistry are discussed. Early investigations confirmed genetic bases to dental caries, periodontal diseases and malocclusion, but research findings have had little impact on clinical practice. The complex multifactorial aetiologies of these conditions, together with methodological problems, have limited progress until recently. Present studies are clarifying previously unrecognized genetic and phenotypic heterogeneities and attempting to unravel the complex interactions between genes and environment by applying new statistical modelling approaches to twin and family data. Linkage studies using highly polymorphic DNA markers are providing a means of locating candidate genes, including quantitative trait loci (QTL). In future, as knowledge increases; it should be possible to implement preventive strategies for those genetically-predisposed individuals who are identified to be at risk.

Host defensive, immunological, and microbiological observations of an early-onset periodontitis patient with virus-associated hemophagocytic syndrome

Virus-associated hemophagocytic syndrome (VAHS) is a disorder characterized by benign generalized histiocytic proliferation and marked hemophagocytosis associated with systemic viral infection. An immunodeficiency which includes an extremely decreased leukocyte and platelet count together with abnormalities in the CD4/CD8 ratio are the most common features of VAHS. Here we report an early-onset periodontitis (EOP) patient with VAHS from the standpoint of host-parasite interaction to understand the effect of this systemic disorder which might possibly influence susceptibility to periodontal disease. The patient is a 16-year-old Japanese male clinically diagnosed as having generalized EOP with slight gingival inflammation and moderate bone loss. This patient manifested VAHS at 3 years of age, and then had an unusual 4 recurrences (at 5, 7, 11, and 14 years old). Laboratory tests conducted include: 1) complete blood analyses: 2) peripheral neutrophil functions (chemotaxis, phagocytosis, superoxide production, and adherence); 3) peripheral lymphocyte subpopulations and functions, T-cell proliferative activity and productivity of cytokines (interleukin-2 [IL-2], interferon gamma [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]); 4) serum cytokine levels (IL-1 beta, IL-2, soluble IL-2 receptor [sIL-2R], IL-4, IL-6, IFN-gamma, and TNF-alpha; 5) serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria; 6) serological human leukocyte antigen (HLA) typing; and 7) determination of bacterial flora of the periodontal pockets. The results indicated that the patient's neutrophil chemotaxis and random migration were below the normal range. In lymphocyte examinations, T-cell proliferative activity, IL-2, and IFN-gamma productivity were elevated. Serum IFN-gamma level was also significantly higher than normal range. No specific periodontopathic bacteria were predominant in the periodontal pockets, however, the serum IgG titer against Porphyromonas gingivalis was elevated throughout the examination period. It is suggested that VAHS might be a possible risk factor for periodontal disease, and hence may serve as a model in understanding the role of host defense mechanisms in the establishment of inflammatory periodontal disease.

HLA Class II genotypes associated with early-onset periodontitis: DQB1 molecule primarily confers susceptibility to the disease

DNA typing was performed on 24 Japanese patients with early-onset periodontitis (EOP) using the PCR-RFLP method to investigate an association of the susceptibility to EOP with the particular HLA class II alleles (HLA-DRB1, -DQA1, and -DQB1). DRB1*1401, DRB1*1501, DQB1*0503, and DQB1*0602 were found more frequently ("susceptible") in the EOP patients than in healthy controls. In contrast, DRB1*0405 and DQB1*0401 were found less frequently ("resistant") in EOP patients. All patients carrying DQB1*0602 had an atypical BamHI site in the intron upstream of the third exon of the DQB1 gene, which in our previous studies appeared to be a susceptible marker for EOP. A comparative analysis of the amino acid sequences of these susceptible and resistant HLA-DRB1 and DQB1 alleles elucidated some differences in antigen-derived peptide binding sites related to the susceptible or resistant alleles. Especially, DQB1*0503 and DQB1*0602 alleles carrying aspartic acid at position 57 and glycine at position 70 are increased significantly in EOP. Since amino acid residues at positions 57 and 70 on the DQB1 molecule are supposed to be involved in antigen binding, amino acid substitutions at these positions may affect the immune responsiveness to the periodontopathic antigen. Our results suggest that the DQB1 molecule plays a crucial role in the pathogenesis of EOP and that the susceptibility to EOP may be determined by the binding ability between the peptide and HLA-DQ antigens.

Evaluation of the frequency of HLA determinants in patients with gingival overgrowth induced by cyclosporine-A

This study has been designed to investigate the immunogenetic susceptibility of Cyclosporine-A (CsA) immunosuppressed renal transplant patients to development of gingival overgrowth, and the amplifying effect of calcium channel blockers on the severity of this clinical entity. 52 renal transplant recipients were selected and initially grouped as follows: group (Gp)1: CsA (n = 7); Gp 2: CsA + verapamil (n = 26); Gp 3: CsA + diltiazem (n = 6); Gp 4: CsA + nifedipine (n = 13). These groups were not found to be significantly different in age, sex, plaque index (PlI), gingival index (GI), calculus index, periodontal probing depth, serum CsA level, or duration of CsA therapy (p > 0.05). No significant (p > 0.05) additive effect of the calcium channel blockers on the gingival overgrowth (GO) was assessed. The main group (n = 52) was evaluated for the correlations between the clinical and the pharmacological variables and the GO. GI (rs = 0.60) and the periodontal probing depth (rs = 0.71) were found to be moderately correlated with the GO. The patients were regrouped based on the severity of overgrowth and recognized as responders (n = 26) and nonresponders (n = 26). Age, sex, calculus index, serum CsA level, duration of the CsA therapy, were not statistically different among these groups (p > 0.05). PlI, GI, periodontal probing depth, and GO were significantly higher in the responder group (p > 0.05). Analysis of HLA distribution of the responders and the nonresponders and comparison with the controls (n = 3731) revealed that a statistically significant (p < 0.001)% of the nonresponders were positive for HLA-DR1. These data would indicate that an immunogenetic predisposition should be suspected in the pathogenesis of the entity, and that HLA-DR1 would have a protective rôle against gingival overgrowth induced by CsA.

Association between HLA antigens and early onset periodontitis

HLA-A, B, C and DR antigen frequencies were determined in a group of patients with juvenile periodontitis and rapidly progressive periodontitis. In juvenile periodontitis patients, HLA-A24 and DR4 were found at a significantly higher level than in the control group, and in rapidly progressive periodontitis patients, A9 and DR4 were found at a significantly higher level than the control group. The presence of these antigens gives evidence as to the susceptibility of various forms of early onset periodontitis.

Immunological, genetic, and microbiological study of family members manifesting early-onset periodontitis

From the standpoint of host-parasite interactions, family studies help us understand the host defensive factors and the molecular mechanisms involved in the periodontal immune response. In this study, we report the immunological profile of host-defensive functions, human leukocyte antigen (HLA) phenotypes, and the microflora of a mother (rapidly progressive periodontitis), an older son (periodontally healthy), a younger son (localized juvenile periodontitis), and a daughter (localized juvenile periodontitis). We examined the peripheral neutrophil functions, phenotypic and functional analysis of peripheral lymphocytes, serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria, serological type of HLA class II antigens, and bacterial flora in all periodontal pockets. The results showed that Actinobacillus actinomycetemcomitans was dominant in the pockets of all subjects. The mother and two sons showed a depressed neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine. All subjects except the older son exhibited low T4/T8 ratios. The mother and daughter had raised levels of IgG titers to Porphyromonas gingivalis. All subjects had HLA phenotypes of DRw52 and DQ1 in common. We found that the family members had similar disorders in certain defensive functions. This family has been a model for our understanding of the host defensive factors in the development of early-onset periodontitis.