The interleukin-1 genotype as a severity factor in adult periodontal disease

Interleukin 1 genotypes in multiple sclerosis and relationship to disease severity

We studied the association between clinical outcome in MS and allelic variants single nucleotide polymorphisms (SNPs) of interleukin-1alpha (IL-1alpha), IL-1beta and a variable number tandem repeat (VNTR) in IL-1 receptor antagonist (IL-1RN). A total of 377 patients with MS were studied. Significant associations between IL-1 genotypes and clinical outcome were found using logistic regression after correction for gender, onset age and disease duration. The same trends were subsequently demonstrated in a second independent group of 67 primary progressive patients. Our results suggest that genetically determined immunomodulation mediated by IL-1 influences long-term prognosis in multiple sclerosis (MS).

Relationship between vitamin D receptor gene polymorphism and periodontitis

Recent studies have shown that vitamin D receptor (VDR) gene polymorphism had regulatory effects on bone mineral density (BMD) and bone turnover. The VDR gene has also been indicated as a candidate gene for the susceptibility of osteoporosis. However, it is unclear whether VDR genotypes could be associated with alveolar bone loss of patients with periodontitis, or whether vitamin D receptor gene could be a candidate gene for susceptibility to periodontitis. The purpose of this study was to answer these two questions.

METHODS

Twenty-four cases of adult periodontitis (AP), 37 cases of early onset periodontitis (EOP) and 39 healthy controls were recruited for the study. Individual samples of venous blood and DNA were obtained from each subject. Genotypes of the TaqI VDR gene were determined by PCR and TaqI restriction endonuclease digestion.

RESULTS

One out of 24 AP patients, nine out of 37 EOP patients and two out of 39 healthy controls were detected with Tt genotype, while the rest had the TT genotype. The detected frequency of Tt genotype was significantly higher in EOP patients (24.3%) than in AP patients (4.2%) and healthy controls (5.1%). The frequency of t allele was also significantly higher in EOP patients. There was no statistical difference in the distribution of TaqI VDR genotypes between AP patients and healthy controls. The study suggests that Tt genotype might be a risk indicator for the susceptibility to EOP. Carriage of the allele (t) of the TaqI VDR gene may increase the risk of developing EOP.

Polymorphism in the interleukin-1 gene complex and spontaneous preterm delivery

OBJECTIVE

We examined the association between preterm delivery and polymorphisms at position +3953 of the interleukin-1 beta gene (IL1B+3953) and in intron 2 of the interleukin-1 receptor antagonist gene (IL1RN).

STUDY DESIGN

This was a case-control study that involved 52 pregnancies that resulted in spontaneous preterm delivery before 34 weeks of gestation and 197 pregnancies that resulted in birth at term. Polymorphisms were determined by polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

Homozygous carriage of IL1B+3953 allele 1 by fetuses of African descent was associated with a risk of preterm delivery (P =.033). Fetuses of Hispanic descent that carried IL1RN allele 2 were found to be at an increased risk for preterm premature rupture of membranes and subsequent preterm delivery(P =.021; odds ratio, 6.5; 95% CI, 1.25-37.7).

CONCLUSION

There are associations of spontaneous preterm delivery with the fetal carriage of IL1B+3953*1 and IL1RN*2 alleles in African and Hispanic populations, respectively.

Investigation of an IL-2 polymorphism in patients with different levels of chronic periodontitis

BACKGROUND

Interleukin-2 (IL-2) is a pro-inflammatory cytokine derived from Th1 cells. This cytokine is involved in B-cell activation and stimulates macrophages, natural killer cells, T-cell proliferation and osteoclast activity. IL-2 has been also implicated in the stimulation of osteoclast activity in bone resorption.

OBJECTIVE

In this study the relationship between the polymorphism - 330 (T-->G) in the IL-2 gene and different levels of chronic periodontal disease was investigated.

MATERIAL AND METHODS

DNA was extracted from buccal epithelial cells of 113 unrelated adult individuals acting as controls and with different levels of periodontitis. The PCR-RFLP technique was used to investigate the polymorphism in the promoter of IL-2 gene.

RESULTS

When comparing the data of three groups of patients (Control, Moderate and Severe) we did not find significant differences between the studied IL-2 polymorphism and severity levels of PD. However, when the Control and Moderate phenotypes were grouped together and compared with genotypes TT vs. TG/GG, a significant difference was observed.

CONCLUSION

We conclude that the - 330 (T-->G) polymorphism in the IL-2 gene is associated with the severity of periodontal disease. The results presented in this study suggest an active role of IL-2 in the pathogenesis of periodontal disease.

Cytokine imbalance in non-immunological chronic disease

Over the last decade, cytokine imbalances have been associated with a plethora of diseases. While the Th(1)/Th(2) paradigm is widely used to explain the pathogenesis of immunological diseases, the role of cytokine imbalances for non-immunological diseases is still incompletely defined. The major obstacle here is to assess the extent to which non-immunological diseases are influenced by inflammation. Non-immunological diseases cover the whole spectrum from those triggered by infection-as may be the case for Alzheimer's disease-to those where the immune system has no apparent impact at all. Examples of the latter are bone diseases, including post-menopausal osteoporosis and skeletal malformations. In between there are diseases such as intrinsic asthma and osteoarthritis where the impact of the immune system is unclear. Thus far, imbalances affecting tumour necrosis factor (TNF)-alpha and members of the interleukin (IL)-1 and the TGF superfamily have been found in association with all of these diseases. We speculate here that cytokine imbalance will be found in additional diseases and touch on the role in phylogeny of cytokines outside the immune system.

Correlation of local interleukin-1beta levels with specific IgA response against Gardnerella vaginalis cytolysin in women with bacterial vaginosis

PROBLEM

Mucosal immune system activation may represent a critical determinant of adverse sequelae correlated with bacterial vaginosis, as HIV sexual transmission, upper genital tract infections, cervicitis, endometritis, postsurgical infections, and adverse pregnancy outcomes as preterm delivery (PTD), low birth weight (LBW).

METHOD OF STUDY

Levels of interleukin-1beta (IL-1beta), anti-Gardnerella vaginalis hemolysin (Gvh) IgA, pH, Nugent score, and number of leukocytes were measured in vaginal fluids of 60 fertile women with bacterial vaginosis and of 64 healthy controls.

RESULTS

Vaginal IL-1beta levels were nearly 13-fold higher in women with bacterial vaginosis (BV) and were associated with anti-Gvh IgA response. IL-1beta was positively correlated with leukocyte counts in the smear both in healthy and bacterial vaginosis positive women.

CONCLUSIONS

Induction of the proinflammatory cytokine IL-1beta may be a necessary event to elicit an innate immune response to control anaerobic genital tract infections. High levels of vaginal IL-1beta are associated with mounting of an antigen-specific mucosal immune response in women with bacterial vaginosis. Parallel induction of innate and adaptive immune response may be associated with protection from ascent of micro-organisms to the upper genital tract, and from acquiring viral infection through the vaginal tract.

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.

Periodontal risk assessment, diagnosis and treatment planning

The prevention and treatment of the periodontal diseases is based on accurate diagnosis, reduction or elimination of causative agents, risk management and correction of the harmful effects of disease. Prominent and confirmed risk factors or risk predictors for periodontitis in adults include smoking, diabetes, race, P. gingivalis, P. intermedia, low education, infrequent dental attendance and genetic influences. Several other specific periodontal bacteria, herpesviruses, increased age, male, sex, depression, race, traumatic occlusion and female osteoporosis in the presence of heavy dental calculus have been shown to be associated with loss of periodontal support and can be considered to be risk indicators of periodontitis. The presence of furcation involvement, tooth mobility, and a parafunctional habit without the use of a biteguard are associated with a poorer periodontal prognosis following periodontal therapy. An accurate diagnosis can only be made by a thorough evaluation of data that have been systematically collected by: 1) patient interview, 2) medical consultation as indicated, 3) clinical periodontal examination, 4) radiographic examination, and 5) laboratory tests as needed. Clinical signs of periodontal disease such as pocket depth, loss of clinical attachment and bone loss are cumulative measures of past disease. They do not provide the dentist with a current assessment of disease activity. In an attempt to improve the ability to predict future disease progression, several types of diagnostic tests have been studied, including host inflammatory products and mediators, enzymes, tissue breakdown products and subgingival temperature. In general, the usefulness of these tests for predicting future disease activity remains to be established in terms of sensitivity, specificity and predictive value. Although microbiological analysis of subgingival plaque is not necessary to diagnose and treat most patients with periodontitis, it is helpful when treating patients with unusual forms of periodontal disease such as early-onset, refractory and rapidly progressive disease. There appears to be a strong genetic component in some types of periodontal disease and genetic testing for disease susceptibility has potential for future use, but more research is needed to determine its utility for use in clinical practice. Treatment of the periodontal diseases may be divided into four phases: systemic, hygienic, corrective and maintenance or supportive periodontal therapy. Regardless of the type of treatment provided, periodontal therapy will fail or will be less effective in the absence of adequate supportive periodontal therapy.

Preventive strategies and supportive treatment

There is a preponderance of evidence in the literature that periodontal and other oral diseases, such as caries, can be treated and controlled by thorough mechanical plaque removal by the patient, the use of antimicrobial agents and antibiotics when necessary, and participation with the therapist in a well monitored, long-range program of supportive periodontal therapy. Recent evidence suggests that the control and prevention of oral disease, especially periodontitis, is especially important for patients with various systemic conditions that can be impacted by oral infections. It is far better for patients and therapists to practice primary and even secondary prevention with effective plaque control and regular, consistent supportive periodontal therapy, than having to rely on tertiary prevention for disease that has progressed to a level that requires costly treatment, is time-consuming and carries a greater risk of morbidity.

Modulation of the host response in periodontal therapy

This paper was prepared by the Research, Science, and Therapy Committee of the American Academy of Periodontology to provide the dental profession an overview of current and potential methods to modulate the host response in the treatment of periodontal diseases. Specifically, it discusses components of periodontal disease pathogenesis (i.e., immune and inflammatory responses, excessive production of matrix metalloproteinases and arachidonic acid metabolites, and regulation of bone metabolism) and their modulation.

5 polymorphisms in the transforming growth factor-beta 1 gene (TGF-beta 1) in adult periodontitis

OBJECTIVES

Transforming growth factor-beta (TGF-beta) represents a family of polypeptide growth factors, involved in inflammation and regulation of immune responses. The purpose of this study was to determine whether polymorphisms in the TGF-beta 1 gene may confer susceptibility to adult periodontitis.

MATERIAL AND METHODS

We studied 90 patients with adult periodontitis together with 108 unrelated subjects. 3 polymorphisms located in the 5'region at positions -988 (C/A), -800 (G/A) and -509 (C/T) and 2 polymorphisms located at codons 10 (L10P) and 25 (R25P) of exon 1 were investigated by PCR methods.

RESULTS

There was no statistically-significant difference in genotype or allele frequency distributions between patients and reference group for the -800G/A, -509C/T, L10P and R25P polymorphisms (p>0.05 in all cases). The -988 A polymorphism was present neither in our patients nor in unrelated subjects. Upon stratification for smoking status no significant differences were found in the TGF-beta 1 genotype or allele frequencies either between adult periodontitis smokers compared to control smokers, or between periodontitis non-smokers and control non-smokers.

CONCLUSION

These data indicate that the mentioned polymorphisms of the TGF-beta 1 gene do not influence susceptibility to adult periodontitis. There was no association between any polymorphisms in the TGF-beta 1 gene, severity of periodontitis and the smoking status in our study.

Clinical utility of a genetic susceptibility test for severe chronic periodontitis: a critical evaluation

BACKGROUND

A genetic susceptibility test for severe chronic periodontitis is now commercially available. It detects the simultaneous presence of a specific form of two interleukin genes--allele 2 at the IL1A+4845 and IL1B+3954 loci. Patients are referred to as being "genotype-positive" if both of these alleles are present. A fundamental premise of the test is that a combination of these alleles is responsible for increased secretion of IL-beta, which results in a hyperinflammatory response to a bacterial challenge, thereby predisposing a person to develop severe chronic periodontitis.

TYPES OF STUDIES REVIEWED

The authors reviewed controlled clinical trials that assessed the association between specific genotypes and the patient's susceptibility to increased bleeding on probing, periodontitis and loss of teeth or dental implants.

RESULTS

The relationship between specific IL-1 genotypes and the level of IL-1beta in the gingival crevicular fluid is unclear. Similarly, the ability of the genetic susceptibility test to forecast which patients will develop increased bleeding on probing, periodontitis, or loss of teeth or dental implants is ambiguous.

CLINICAL IMPLICATIONS

Additional prospective clinical trials are needed to determine the risk of developing periodontitis or peri-implantitis when allele 2 at the IL1A+4845 and IL1B+3954 loci is present. Therefore, it is unclear how results of the genetic susceptibility test can be used to alter patients' periodontal maintenance schedules or to change treatment regimens in periodontally symptomatic or asymptomatic patients.

Antisense-mediated inhibition of ICAM-1 expression: a therapeutic strategy against inflammation of human periodontal tissue

Periodontal diseases, such as gingivitis and periodontitis, are caused by a mixed infection by several types of bacteria in the dental plaque, causing a chronic inflammation of the gingival mucosa. Inflammatory processes in conjunction with immune responses to bacterial attacks are generally protective. In profound periodontitis, however, hyperresponsiveness and hypersensitivity of the immune system are counterproductive because of the destruction of the affected periodontal connective tissues. The intercellular adhesion molecule type 1 (ICAM-1) plays a key role in the onset and manifestation of inflammatory responses. Thus, inhibition of ICAM-1 expression could be of therapeutic relevance for the treatment of destructive periodontitis. Here, antisense oligonucleotides (AS-ON) directed against ICAM-1 suppress protein expression and mRNA levels specifically and effectively in primary human endothelial cells of different tissue origin. Moreover, downregulation of ICAM-1 expression is also observed in AS-ON-transfected inflamed gingival mucosal tissue of patients with periodontal diseases. This work strongly suggests exploiting the local topical application of ICAM-1-directed AS-ON as a therapeutic tool against inflammatory processes of the human gingiva.

Clinical, genetic and microbiological findings in a Brazilian family with aggressive periodontitis

BACKGROUND/AIM

Aggressive periodontitis comprises a group of rapidly progressive forms of periodontitis. Besides bacteria, a high level of subject susceptibility must be involved in the expression of disease. In the present study, we report the clinical, microbiological and genetic profile of a 14-individual family with aggressive periodontitis.

METHOD

PCR was utilized to detect pathogenic bacteria of affected sites. DNA was obtained from epithelial cells through a mouthwash with 3% glucose and scrapping of the oral mucosa. RFLP-PCR was used to analyze cytokine genetic polymorphisms.

RESULTS

Localized aggressive periodontitis was diagnosed for an 18-year-old systemically healthy non-smoking proband, with siblings displaying aggressive periodontitis. Bacteroides forsythus and Treponema denticola were the most frequent pathogens. The proband presented Actinobacillus actinomycetemcomitans and detectable levels of Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola. Allele 2 of IL-1alpha (-889) polymorphism was found in all individuals as well as allele 1 of the IL-1beta (+3953) gene. Alleles 1 and 2 (50 % each) of IL-1beta (-511), allele 1 of TNF-alpha (-308) and allele 2 (in homo or heterozygosity) of IL-RN (intron 2) gene were present.

CONCLUSION

The results show that the present microbiological and genetic parameters were not relevant for the prediction of periodontitis susceptibility in this family.

The application of genetics to the discovery of better medicines

The availability of the human genome sequence and the increasing knowledge of functional polymorphisms will highlight new therapeutic approaches to treat diseases with unmet medical need and will allow the targeting of new and existing therapies to those patients who will derive the most benefit without the risk of serious side effects. This review describes how genetic information can be used to improve the drug discovery and development process. It should be emphasized, however, that although it is anticipated that high-throughput genetic studies will provide novel biological insights into disease, it is not a replacement for careful hypothesis-driven experiments. Rather, it is essential to combine genetic studies with carefully conducted preclinical and clinical experiments to extract the true value of high-throughput genetics-based research.

Effect of interleukin-1 gene polymorphism in a periodontally healthy Hispanic population treated with mucogingival surgery

OBJECTIVES

A genetic test for susceptibility of periodontal disease has been introduced. A positive test indicates a risk factor for more severe periodontal destruction. The prevalence of genotype positive subjects has been reported around 30%. In a Mexican population, we have found a 26% prevalence of genotype positive individuals. Few studies have reported the response to therapy in these individuals. The purpose of this study was to assess the response to mucogingival surgery in an otherwise periodontally healthy Hispanic population.

MATERIALS AND METHODS

22 subjects (7 male and 15 female) with a mean age of 45 years participated. They were treated 3 years prior for the treatment of Types I and II recession defects using connective tissue grafts. No other active periodontal treatment was required, except for preventive maintenance. A full-mouth clinical evaluation was performed which included assessment of gingival inflammation and measurements of probing pocket depth and clinical attachment levels. Mean values per patient were determined. A finger stick blood sample was collected using specially provided DNA filter paper, let dried, and mailed for processing.

RESULTS

Results indicated that 5 out of the 22 subjects were genotype positive. The genotype positive subjects presented the following values: GI 1.13+/-0.17, PPD 2.48+/-0.46, and CAL 3.38+/-0.66. The values for the genotype negative subjects were GI 1.06+/-0.14, PPD 2.38+/-0.31 and CAL 3.11+/-0.53. No statistical significant differences were found when both groups were compared (p>0.05). Furthermore, the treatment of the localized recessions was effective and provided similar amount of coverage in genotype positive and negative subjects. However, more genotype negative subjects showed complete coverage of the recession than genotype positive individuals.

CONCLUSIONS

Within the limits of this study it is concluded that (1) periodontal health can be maintained with proper preventive maintenance irrespective of the genotype present, (2) the mean response to mucogingival surgery to cover localized gingival recessions is similar irrespective of the IL-1 periodontal genotype, however, full coverage is achieved more frequently in genotype negative subjects.

A critical assessment of interleukin-1 (IL-1) genotyping when used in a genetic susceptibility test for severe chronic periodontitis

BACKGROUND

This review addresses the ability of a commercially available genetic susceptibility test to determine the risk of developing severe chronic periodontitis. The test is used to detect the simultaneous occurrence of allele 2 at the IL-1A+4845 and IL-1B+3954 loci. If both of these polymorphisms are present, patients are referred to as being genotype-positive and considered predisposed to becoming afflicted with severe chronic periodontitis. A basic premise of this test is the assumption that individuals who are genotype-positive produce increased amounts of IL-beta in response to microbial lipopolysaccharides, which allegedly predisposes them to an exaggerated inflammatory response and an increased incidence of chronic periodontitis.

METHODS

Controlled clinical trials were selected that evaluated the ability of the genetic test to predict which patients were susceptible to bleeding upon probing, periodontitis, peri-implantitis, and tooth loss.

RESULTS

Comparison of results from test (genotype-positive) and control groups (genotype-negative) revealed that there is ambiguity with regard to predicting which patients will manifest elevated sub-gingival levels of IL-beta. Similarly, it is questionable if the test is able to forecast which individuals will demonstrate an increased occurrence of bleeding upon probing, diminished clinical attachment, decreased osseous support, or loss of teeth.

CONCLUSIONS

There are many unanswered questions concerning the utility of detecting allele 2 at the IL-1A+4845 and IL-IB+3954 loci to foretell which patients will develop severe chronic periodontitis. Therefore, clinicians must cautiously interpret results obtained with the commercially available genetic susceptibility test before they alter maintenance schedules or treatment regimens of symptomatic or asymptomatic patients.

Interleukin-1 gene cluster polymorphisms in sarcoidosis and idiopathic pulmonary fibrosis

Members of the interleukin-1 (IL-1) family are implicated in the pathogenesis of sarcoidosis and idiopathic pulmonary fibrosis (IPF). We have, therefore, performed a case-control study to investigate a plausible association between sarcoidosis and the polymorphisms in the IL-1alpha, IL-1beta, and IL-1 receptor antagonist (IL-1Ra) genes. Further, as a separate question, we explored whether the aforementioned genes of the IL-1 cluster are associated with IPF. Using PCR with sequence-specific primers, IL-1alpha -889, IL-1beta -511, IL-1beta +3953, and IL-1Ra intron 2 VNTR polymorphisms were determined in 348 white subjects of West Slavonic ancestry (95 patients with sarcoidosis, 54 patients with IPF, and 199 healthy control subjects). The IL-1alpha -889 1.1 genotype was significantly overrepresented in patients with sarcoidosis in comparison with control subjects (60.0 versus 44.2%, p = 0.012, p(corr) = 0.047). The distribution of IL-1beta -511, IL-1beta +3953, and IL-1Ra VNTR genotypes and alleles did not significantly differ between the cases and controls. No association between IPF and the investigated polymorphisms was found. Strong linkage disequilibrium between pairs of polymorphic loci was observed. Further population studies are warranted to confirm the observed association between sarcoidosis and the IL-1alpha polymorphism and also to explore mechanisms of IL-1alpha -889 participation in aberrant immune response in sarcoidosis.

Failure to detect an association with IL1 genotypes in European Caucasians with generalised early onset periodontitis

OBJECTIVES

In order to elucidate the genetic background to EOP it is useful to investigate associations with genetic polymorphisms of immune response genes, whose products play a r le in the inflammatory process. The aim of this study was to examine IL1A and IL1B genetic polymorphisms in unrelated European white Caucasian patients with generalised early-onset periodontitis (GEOP).

MATERIAL AND METHODS

Polymerase chain reaction (PCR) amplification of the ILIA (-889) gene and IL1B (+3953) gene (56 patients, 56 controls) was carried out and PCR products subjected to restriction fragment length polymorphism (RFLP) analysis.

RESULTS

There were no significant differences between patients and controls for any of the genotype or allele frequencies investigated (p = 1.0). Smoking status was also included as a covariate but this did not alter the results. Furthermore, expression of the composite genotype described by Kornman and coworkers was also investigated in these subjects. No significant differences were found between patients and controls whether smoking was included as a covariate or not.

CONCLUSION

The lack of any association between the IL1 polymorphisms and GEOP, in the population presented here, brings into doubt the usefulness of these candidate genes as markers of susceptibility to this form of periodontitis.

Interleukin-1 gene polymorphism and periodontal status

OBJECTIVES

This case-control study examined polymorphisms at the interleukin-1 gene in relation to periodontal status, subgingival bacteria and systemic antibodies to periodontal microbiota.

METHODS

132 periodontitis patients were age- and gender-matched with 73 periodontally intact controls. Full-mouth clinical assessments of the periodontal tissues were performed. Subgingival plaque samples (2440 in total) were analyzed by genomic DNA probes, and serum IgG antibodies to periodontal microbiota were assessed by an immunoassay. Polymorphisms in the IL-1A gene at position +4845 and the IL-1B gene at position +3953 were studied by PCR. A composite positive genotype was defined as at least one rare (#2) allele present at each locus.

RESULTS

No skewed distribution of the composite genotype was observed between cases and controls (45.2% vs 41.7%). In cases, both the composite genotype and the number of #2 alleles were positively correlated with the severity of attachment loss. No relationship between genotype and subgingival microbial profiles was observed. Genotype positive patients revealed both overall lower serum antibody levels and specific titers against selected bacteria.

CONCLUSIONS

The composite genotype failed to distinguish between periodontitis patients and controls but correlated in patients with the severity of the disease and the antibody responses to periodontal microbiota.

The intra-oral translocation of periodontopathogens jeopardises the outcome of periodontal therapy

BACKGROUND

Although periodontitis has a multi-factorial aetiology, the success of its therapy mainly focuses on the eradication/reduction of the exogenous/endogenous periodontopathogens. Most of the species colonise several niches within the oral cavity (e.g. the mucosae, the tongue, the saliva, the periodontal pockets and all intra-oral hard surfaces) and even in the oro-pharyngeal area (e.g., the sinus and the tonsils).

METHODS

This review article discusses the intra-oral transmission of periodontopathogens between these niches and analyses clinical studies that support the idea and importance of such an intra-oral translocation.

RESULTS AND CONCLUSIONS

Based on the literature, the oro-pharyngeal area should indeed be considered as a microbiological entity. Because untreated pockets jeopardise the healing of recently instrumented sites, the treatment of periodontitis should involve "a one stage approach" of all pathologic pockets (1-stage full-mouth disinfection) or should at least consider the use of antiseptics during the intervals between consecutive instrumentations, in order to prevent a microbial translocation of periodontopathogens during the healing period. For the same reason, regeneration procedures or the local application of antibiotics should be postponed until a maximal improvement has been obtained in the remaining dentition. This more global approach offers significant additional clinical and microbiological benefits.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Tumor necrosis factor-alpha gene polymorphisms in relation to periodontitis

BACKGROUND

Genetic polymorphisms for cytokines have been proposed as potential genetic markers for destructive periodontal disease. The present aim was to investigate 4 bi-allelic polymorphisms in the TNF-alpha gene in relation to susceptibility for and severity of periodontitis. The polymorphisms were all transitions from G to A, 3 in the promoter positions: -376, -308, -238; and one in the first intron at position +489.

METHODS

90 periodontitis patients and 264 reference control subjects were genotyped and frequencies of genotypes and alleles were analyzed. Also genotype frequencies among severe and moderate periodontitis patients were explored, and the % of teeth with 50% bone loss and the % of teeth without any bone loss for patients with the A allele (A+ genotype) and patients without (A- genotype) were compared.

RESULTS

The distributions of genotypes and frequencies of A allele carriage rates for the 4 TNF-alpha polymorphisms were not different between patients and reference controls; Hardy-Weinberg equilibrium criteria were fulfilled. Also the distribution of A+ and A- genotypes, alone or in combinations, were not different for severe periodontitis compared to moderate periodontitis patients. None of the A+ genotypes showed a significant different bone loss pattern compared to A- genotype patients. Smoking status of the patients did not influence the results.

CONCLUSIONS

Genetic polymorphisms in the TNF-alpha gene at positions -376, -308, -238 and +489 could not be identified as susceptibility or severity factors in periodontitis, irrespective of the smoking status of the patients.

Association between bone loss in periodontal disease and polymorphism of N-acetyltransferase (NAT2)

BACKGROUND

The individual susceptibility to periodontal disease is probably the result of an interaction of multiple genetic and environmental influences. Polymorphism of the N-acetyltransferase (NAT 2) modifies the individual susceptibility to toxicity from certain therapeutic drugs or heterocyclic amines including substances from cigarette smoke. Subjects are to be classified as 'slow' or 'rapid' acetylators according to how fast their bodies metabolise such xenobiotics. Differences in their ability to detoxify these substances may contribute to an increased risk for periodontitis in subjects exposed to cigarette smoke or other xenobiotics.

OBJECTIVE

The purpose of this study was to assess whether the NAT2 genotype is a risk factor for periodontal disease in Caucasian patients suffering from adult periodontitis.

MATERIAL AND METHODS

154 Caucasian subjects were assigned to one of the 3 groups: no, moderate, and severe periodontal disease based on bone and attachment loss. In all subjects, genotyping for mutations on the N-acetyltransferase (NAT2) gene was performed by means of PCR and RFLP analysis.

RESULTS

Comparison of frequency distribution of NAT2 acetylation types between the most diseased group and not or moderately affected subjects showed a tendency to over-representation of slow acetylators with severe disease. When using bone loss as measure of periodontitis, this over-representation shows a significant association with the disease (odds ratio=2.13, p=0.025). In the logistic regression analysis, adjusted for age and smoking, NAT2 slow phenotype was significantly associated with the severity of bone loss, the odds ratio being 2.09 (95% C.I. 1.02-4.26, p=0.043). In a case-control analysis (controlled for smoking, gender and age) mean bone loss showed a significant difference between the 2 NAT2-type groups (Mann-Whitney test p=0.041).

CONCLUSION

The data suggest that the slow acetylator phenotype may be associated with a higher risk of periodontitis, especially in smokers. Possible explanations regarding the mechanism are discussed; however, such attempts are highly speculative at this time.

GCF IL-1beta profiles in periodontal disease

OBJECTIVES

Studies suggest a genetic influence on levels of interleukin-1beta (IL-1beta) in gingival crevicular fluid (GCF). Levels of IL-1beta in GCF, however, are also dependent upon the clinical parameters at the site of collection, including probing depth (PD) and level of attachment (AL). To examine this issue, IL-1beta in GCF was evaluated from patients with varying degrees of periodontal disease. The influence of both the status of the patient and the probing depth at the sampled sites were considered in the analysis.

MATERIAL AND METHODS

GCF IL-1beta was determined by ELISA at 6-8 molar sites from 29 non-smoking adults with mild, moderate, or severe periodontal disease at baseline, 2 weeks, and 24 weeks following scaling and root planing. For later analysis, patients were dichotomized on the basis of disease severity (mild/moderate vs severe). Sampled sites were classified at baseline by PD as, shallow (<4 mm), intermediate (4-6 mm), or deep (>6 mm).

RESULTS

PD and AL were each strongly correlated with IL-1beta levels at baseline. However, patients with severe disease had higher levels of IL-1beta in each PD category than those with mild/moderate disease. As compared to patients with mild/moderate disease, IL-1beta levels in shallow sites from patients with severe disease was elevated nearly 2 fold (p<0.001). IL-1beta levels were reduced in all groups at 2 weeks and were still significantly reduced in patients with mild/moderate disease at 24 weeks. At 24 weeks IL-1beta returned to near baseline levels in patients with severe disease.

CONCLUSION

While PD and AL are each associated with increased GCF IL-1beta, patients with severe disease show higher IL-1beta GCF levels in shallow sites, suggesting that high GCF IL-1beta expression is in part a host trait, and not strictly a function of clinical parameters.

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.

The role of inflammatory and immunological mediators in periodontitis and cardiovascular disease

Epidemiological studies have implicated periodontitis (PD) as a risk factor for development of cardiovascular disease (CVD). Persistent infections such as periodontitis induce inflammatory and immune responses which may contribute to coronary atherogenesis, and, in conjunction with other risk factors, may lead to coronary heart disease (CHD). In this review, mechanisms are described that may help explain the association between periodontal infections and CHD. Periodontal diseases are bacterial infections associated with bacteremia, inflammation, and a strong immune response, all of which may represent significant risk factors for the development of atherogenesis, CHD, and myocardial infarction (MI). Several mechanisms may participate in this association, including those induced by oral organisms, and those associated with host response factors. This review will focus on host factors. Oral pathogens and inflammatory mediators (such as interleukin [IL]-1 and tumor necrosis factor [TNF]-alpha) from periodontal lesions intermittently reach the bloodstream inducing systemic inflammatory reactants such as acute-phase proteins, and immune effectors including systemic antibodies to periodontal bacteria. This review will describe the potential role of various inflammatory as well as immunologic factors that may play a role in periodontitis as a possible risk factor for CHD.

The relationship between periodontal diseases and diabetes: an overview

Diabetes mellitus, caused by the malfunction of insulin-dependent glucose and lipid metabolism, presents with the classical triad of symptoms: polydypsia, polyuria, and polyphagia which are often accompanied by chronic fatigue and loss of weight. Complications of diabetes mellitus include retinopathy, nephropathy, neuropathy, and cardiovascular disease. Periodontal diseases are infections affecting the periodontium and resulting in the loss of tooth support. The association between diabetes mellitus and periodontitis has long been discussed with conflicting conclusions. Both of these diseases have a relatively high incidence in the general population (diabetes 1% to 6% and periodontitis 14%) as well as a number of common pathways in their pathogenesis (both diseases are polygenic disorders with some degree of immunoregulatory dysfunction). On the one hand, numerous reports indicate a higher incidence of periodontitis in diabetics compared to healthy controls, while other reports fail to show such a relationship. Clarification of this dilemma is occurring as the diagnostic criteria for periodontitis and diabetes mellitus improve, controlled studies with increased sample sizes are carried out, and the studies take into account major confounding variables that impact on the pathogenesis of both diseases. Current studies tend to support a higher incidence and severity of periodontitis in patients with diabetes mellitus. The overview looks at the bidirectional relationship between periodontitis and diabetes. An analysis of the National Health and Nutrition Examination Survey (NHANES) III data set confirms the previously reported significantly higher prevalence of periodontitis in diabetics than in non-diabetics (17.3% versus 9%). The analysis of the data also shows that the prevalence of diabetes in patients with periodontitis is double that seen in the non-periodontitis patients (12.5% versus 6.3%) and that this difference is also statistically significant. The pathogenesis of the 2 diseases is reviewed with an emphasis on common genetic and immune mechanisms. On the basis of the overview, 2 hypotheses for testing the relationship between periodontitis and diabetes are discussed. The first proposes a direct causal or modifying relationship in which the hyperglycemia and hyperlipidemia of diabetes result in metabolic alterations that may then exacerbate bacteria-induced inflammatory periodontitis. The second hypothesis proposes that a fortuitous combination of genes (gene sets) could result in a host who, under the influence of a variety of environmental stressors, could develop either periodontitis or diabetes or both.

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.

A longitudinal study of interleukin-1 gene polymorphisms and periodontal disease in a general adult population

BACKGROUND

Cross-sectional studies have demonstrated that a specific polymorphism (allele 2 of both IL-1A +4845 and IL-1B +3954) in the IL-1 gene cluster has been associated with an increased susceptibility to severe periodontal disease and to an increased bleeding tendency during periodontal maintenance. The aim of the present study was to investigate the relationship between IL-1 genotype and periodontitis in a prospective longitudinal study in an adult population of essentially European heritage.

METHODS

From an ongoing study of the Oral Care Research Programme of The University of Queensland, 295 subjects consented to genotyping for IL-1 allele 2 polymorphisms. Probing depths and relative attachment levels were recorded at baseline, 6, 12, 24, 36, 48 and 60 months using the Florida probe. Periodontitis progression at a given site was defined as attachment loss > or =2 mm at any observation period during the 5 years of the study and the extent of disease progression determined by the number of sites showing attachment loss. Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia were detected using ELISA.

RESULTS

38.9% of the subjects were positive for the composite IL-1 genotype. A relationship between the IL-1 positive genotype and increased mean probing pocket depth in non-smokers greater than 50 years of age was found. Further, IL-1 genotype positive smokers and genotype positive subjects with P. gingivalis in their plaque had an increase in the number of probing depths > or =3.5 mm. There was a consistent trend for IL-1 genotype positive subjects to experience attachment loss when compared with IL-1 genotype negative subjects.

CONCLUSION

The results of this study have shown an interaction of the IL-1 positive genotype with age, smoking and P. gingivalis which suggests that IL-1 genotype is a contributory but non-essential risk factor for periodontal disease progression in this population.

Analysis of single nucleotide polymorphisms in the 5'-flanking region of tumor necrosis factor-alpha gene in Japanese patients with early-onset periodontitis

BACKGROUND

Early-onset periodontitis (EOP) is considered to have a genetic basis, which has not been clearly defined. The tumor necrosis factor-alpha (TNF-alpha) gene polymorphism as one of the genetic factors may influence the expression of several chronic inflammatory diseases. The aim of the present study was to evaluate whether the polymorphisms in the 5'-flanking region of the TNF-alpha gene are associated with Japanese EOP patients.

METHODS

Forty-six Japanese, generalized EOP (G-EOP) patients and 104 Japanese healthy subjects were identified according to established clinical criteria. Twenty healthy subjects were analyzed by nucleotide sequence to screen polymorphisms of the 5'-flanking region of the TNF-alpha gene. Then, all subjects were analyzed by polymerase chain reaction and sequence-specific oligonucleotide probe (SSOP) methods.

RESULTS

We determined 5 single nucleotide polymorphisms at positions -1031 (T/C), -863 (C/A), -857 (C/T), -308 (G/A), and -238 (G/A) in the 5'-flanking region of the TNF-alpha gene. There were no significant differences in the genotype and allele frequency when we compared G-EOP patients to healthy subjects. Because the frequency of polymorphic alleles at positions -308 and -238 was very low in this study population, we demonstrated the existence of 4 detected haplotypes and 6 detected genotypes concerning 3 single nucleotide polymorphisms (-1031, -863, and -857). The frequency of the H1/H3 (TCC/TCT)-detected genotype tended to decrease in G-EOP patients compared to healthy subjects, but was not statistically significant.

CONCLUSION

These findings suggest there is no significant association between polymorphisms in the 5'-flanking region of the TNF-alpha gene and susceptibility to G-EOP in Japanese patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Non-redundant roles for interleukin-1 alpha and interleukin-1 beta in regulating human IgG2

BACKGROUND

Serum concentrations of immunoglobulin G2 (IgG2) are elevated in localized aggressive periodontitis (LAgP) patients, and secretory products of monocytes from LAgP patients enhance IgG2 responses of lymphocytes from healthy subjects. Furthermore, genes regulating production of interleukin (IL)-1 influence the risk for both aggressive periodontitis (AgP) and chronic periodontitis. These observations, and the fact that IgG2 dominates responses to carbohydrates from Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, prompted the hypothesis that IL-1 alpha, IL-1 beta, and IL-RA may help regulate human IgG2 responses.

METHODS

Human peripheral blood leukocytes (PBL) were stimulated in culture with pokeweed mitogen (PWM); the levels of available IL-1 gene products were manipulated; and the effect on IgG2 production was monitored. Manipulations of IL-1 were accomplished by adding specific neutralizing monoclonal antibodies or recombinant IL-1RA, IL-1 alpha, or IL-1 beta.

RESULTS

Blocking the IL-1 receptor with IL-1RA or neutralizing IL-1 alpha or IL-1 beta with specific antibody dramatically suppressed IgG2 production (50% to 70%). Additionally IL-1 alpha did not compensate for neutralized IL-1 beta, and additional IL-1 beta did not compensate for neutralized IL-1 alpha, suggesting the 2 monokines have separate roles in promoting IgG2. Furthermore, combinations of anti-IL-1 alpha and anti-IL-1 beta were more inhibitory than either antibody alone, and IL-1 alpha and IL-1 beta in combination appeared to work additively in promoting IgG2. Moreover, PBL cultures from a group of LAgP patients with high IgG2 levels had elevated levels of IL-1 beta.

CONCLUSION

IL-1 alpha and IL-1 beta appear to have critical and non-redundant roles in the generation and regulation of potent IgG2 responses, which appear to be important in human responses to carbohydrate-bearing bacteria.

Lower numbers of erythrocytes and lower levels of hemoglobin in periodontitis patients compared to control subjects

BACKGROUND

Anemia of chronic disease (ACD) is defined as the anemia occurring in chronic infections and inflammatory conditions, that is not due to marrow deficiencies or other diseases and in the presence of adequate iron stores and vitamins. The purpose of the present study was to investigate whether periodontitis patients show signs of anemia.

METHOD

39 patients with severe periodontitis, 71 patients with moderate periodontitis and 42 controls, all with good general health, participated in this study. The mean age of all groups was 42 years. Several red blood cell parameters were determined from peripheral blood samples.

RESULTS

Overall data analysis indicated that periodontitis patients have a lower hematocrit, lower numbers of erythrocytes, lower hemoglobin levels and higher erythrocyte sedimentation rates. These results were adjusted for the following possible confounders: gender, age, smoking, ethnicity and level of education. Further, more periodontitis patients (23%) than controls (7%), had hemoglobin levels below the normal reference range.

CONCLUSIONS

The present study provides further evidence that periodontitis has systemic effects and that periodontitis may tend towards anemia. This phenomenon may be explained by a depressed erythropoiesis.

Beyond the specific plaque hypothesis: are highly leukotoxic strains of Actinobacillus actinomycetemcomitans a paradigm for periodontal pathogenesis?

Actinobacillus actinomycetemcomitans is a facultative anaerobe implicated in a variety of periodontal diseases. Its presence is most closely associated with localized juvenile periodontitis (LIP), although the exact role of the organism in this and other periodontal diseases is not entirely clear. While A. actinomycetemcomitans produces several different putative virulence factors, the most widely studied is the leukotoxin. The leukotoxin selectively kills polymorphonuclear leukocytes and macrophages in vitro, constituting the host's first line of defense. Interestingly, even though all strains of A. actinomycetemcomitans have the genes encoding the leukotoxin, there is variability in leukotoxin expression. Differences in the structure of the promoter region of the leukotoxin gene operon were shown to correlate directly with levels of leukotoxin production. Highly leukotoxic forms appear to exhibit increased pathogenic potential, as evidenced by recent studies that have shown a significant association between the prevalence of such strains and the occurrence of LIP in several different populations. This represents the first demonstration of an association between a particular subset of a pathogenic species and a specific periodontal disease. Early identification of A. actinomycetemcomitans by microbial and genetic assays to evaluate leukotoxicity may enhance the efficacy of preventive and/or therapeutic techniques. Future investigations should continue to evaluate pathogenic variations of additional virulence factors expressed in vivo, not only of A. actinomycetemcomitans, but also of other periodontal bacteria and infectious disease pathogens.

Interleukin-10 gene promoter polymorphism in Japanese patients with adult and early-onset periodontitis

BACKGROUND

IL-10 is an anti-inflammatory cytokine, which may modulate disease expression in chronic inflammatory periodontal disease. 3 dimorphic polymorphisms within the IL-10 gene promoter have recently been identified and appear to influence regulation of its expression.

AIM

The aim of the present study was to investigate whether the promoter polymorphisms are associated with adult periodontitis (AP) and generalized early-onset periodontitis (G-EOP).

METHODS

Genomic DNA was obtained from 34 AP patients, 18 G-EOP patients and 52 controls. The promoter region between -506 and -1140 was amplified by polymerase chain reaction, and polymorphisms were detected by nucleotide sequencing.

RESULTS

The haplotype frequencies in Japanese were quite different from those of Caucasian and were even slightly different from those of southern Chinese with systemic lupus erythematosus. We found no significant difference in allele or haplotype frequencies between patients and controls.

CONCLUSIONS

IL-10 production may be regulated within the complex cytokine network in chronic inflammatory periodontal disease, rather than the gene polymorphisms.

Performance of a commercial immunoassay for detection and differentiation of periodontal marker bacteria: analysis of immunochemical performance with clinical samples

BACKGROUND

We employed a commercial immunoassay for simultaneous detection and differentiation of marker bacteria Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia and reassessed the immunochemical performance of the assay.

METHODS

We compared the analytical performance of the immunoassay in our study of clinical samples from 249 periodontal patients in 2 private periodontal practices with the previously reported analytical performance of the same immunoassay. We also compared immunoassay measurements of the marker bacteria in clinical samples with values obtained in other studies by direct culture of the same organisms.

RESULTS

The assay produced 3 times more high-end readings than reported previously. We also reassessed and revised previously published calibration curves for the immunoassay. The immunoassay provided measurements of the marker bacteria in clinical samples from our patients that were comparable to and consistent with measurements of the same bacteria by direct culture in other studies.

CONCLUSIONS

We ascribe the increased sensitivity of the immunoassay in our study to: 1) a more standardized and vigorous sample dispersion that improves release of particulate and soluble antigens from dental plaque biofilm, and 2) better visualization of the reaction product of the enzyme-linked immunoassay. High-technology assays, such as diagnostic immunoassays, have a significant potential for future development in dental diagnosis, because they simplify detection and measurement of biologically important markers such as specific bacteria in clinical samples. Commercial assays also have an important potential for standardization of clinical measurements of biological markers.

IL-1 genotype and adult periodontitis among young New Zealanders

Several recent studies have investigated the association between interleukin-1 genotype and periodontitis in clinical samples, where generalizability is an issue. The aim of this study was to investigate the association between adult periodontitis and IL-1 genotype in a population-based sample of 26-year-olds. Based on probing depth (PD) measurements, participants were divided into three disease groups: "Severe" (1+ teeth with 5+mm PD; N = 25), "Moderate" (2+ teeth with 4+mm PD; N = 36), and "Controls" (the remainder; N = 800). The "periodontitis-associated genotype" (PAG; Kornman et al., 1997) was present in 20.0% of the "Severe" group and in 34.8% of "Controls", whereas the IL-1A(+4845) [1,1]/IL-1B(+3953) [2,2] genotype was present in 12.0% and 0.9%, respectively. After controlling for sex, smoking status, and plaque levels, we found that those with IL-1B(+3953) [1,1]/IL-1A(+4845) [2,2] had 12.3 times the odds of being in the "Severe" group. Analysis of these data suggests that the IL-1A(+4845) [1,1]/IL-1B(+3953) [2,2] genotype is associated with periodontal disease in this young population. Future periodontal data collections as this cohort ages are required to confirm the predictive value of that genotype.

Polymorphisms of the interleukin-1 gene family, oral microbial pathogens, and smoking in adult periodontitis

Interleukin (IL)-1alpha, IL-1beta, and IL-1ra contribute to regulation of the inflammatory response in periodontal tissues. We aimed to investigate the distribution of polymorphisms in the IL-1 gene family among periodontitis patients and controls, taking into account smoking and microbiology as additional variables. Fifty-three non-smoking and 52 smoking patients with severe adult periodontitis and 53 controls were genotyped for bi-allelic IL-1A(-889), IL-1B(-3954), and a penta-allelic 86-bp VNTR IL-1RN gene polymorphisms. The presence of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans was established by culture techniques. We found a higher frequency of allele 2 carriage in IL-1A, IL-1B, and IL-1RN in periodontitis patients who were non-smokers and in whom P. gingivalis and A. actinomycetemcomitans could not be detected (42.1% vs. 11.3% in controls; P = 0.0068; OR 5.7, 95% CI: 1.6-19.8). Our results provide evidence that polymorphisms in genes of the IL-1 family are associated with severe adult periodontitis in the absence of other risk factors tested in this patient population.

Periodontal manifestations of systemic disease

Periodontitis is a chronic bacterial infection of the supporting structures of the teeth. The host response to infection is an important factor in determining the extent and severity of periodontal disease. Systemic factors modify periodontitis principally through their effects on the normal immune and inflammatory mechanisms. Several conditions may give rise to an increased prevalence, incidence or severity of gingivitis and periodontitis. The effects of a significant number of systemic diseases upon periodontitis are unclear and often it is difficult to causally link such diseases to periodontitis. In many cases the literature is insufficient to make definite statements on links between certain systemic factors and periodontitis and for several conditions only case reports exist whereas in other areas an extensive literature is present. A reduction in number or function of polymorphonuclear leukocytes (PMNs) can result in an increased rate and severity of periodontal destruction. Medications such as phenytoin, nifedipine, and cyclosporin predispose to gingival overgrowth in response to plaque and changes in hormone levels may increase severity of plaque-induced gingival inflammation. Immuno-suppressive drug therapy and any disease resulting in suppression of the normal inflammatory and immune mechanisms (such as HIV infection) may predispose the individual to periodontal destruction. There is convincing evidence that smoking has a detrimental effect on periodontal health. The histiocytoses diseases may present as necrotizing ulcerative periodontitis and numerous genetic polymorphisms relevant to inflammatory and immune processes are being evaluated as modifying factors in periodontal disease. Periodontitis severity and prevalence are increased in diabetics and worse in poorly controlled diabetics. Periodontitis may exacerbate diabetes by decreasing glycaemic control. This indicates a degree of synergism between the two diseases. The relative risk of cardiovascular disease is doubled in subjects with periodontal disease. Periodontal and cardiovascular disease share many common risk and socio-economic factors, particularly smoking, which is a powerful risk factor for both diseases. The actual underlying aetiology of both diseases is complex as are the potential mechanisms whereby the diseases may be causally linked. It is thought that the chronic inflammatory and microbial burden in periodontal disease may predispose to cardiovascular disease in ways proposed for other infections such as with Chlamydia pneumoniae. To move from the current association status of both diseases to causality requires much additional evidence. Determining the role a systemic disease plays in the pathogenesis of periodontal disease is very difficult as several obstacles affect the design of the necessary studies. Control groups need to be carefully matched in respect of age, gender, oral hygiene and socio-economic status. Many studies, particularly before the aetiological importance of dental plaque was recognised, failed to include such controls. Longitudinal studies spanning several years are preferable in individuals both with and without systemic disease, due to the time period in which periodontitis will develop.

Retrospective evaluation of the influence of the interleukin-1 genotype on radiographic bone levels in treated periodontal patients over 10 years

BACKGROUND

A difference in genetic susceptibility to plaque accumulation has been advocated to explain different responses to periodontal therapy. The purpose of this study is to assess the role of the interleukin-1 (IL-1) polymorphism on the rate of bone and tooth loss in non-smoking periodontally treated patients during maintenance.

METHODS

Sixty consecutive non-smoking patients (mean age 46.8 +/- 5.0) with moderate to severe periodontitis, treated and maintained for over 10 years were selected. At baseline (T0), radiographic evaluation (cemento-enamel junction [CEJ]-root apex, CEJ-bottom of defect mesial and distal, CEJ-bone crest mesial and distal, crown-root ratio) was performed. All patients received scaling and root planing; 36 patients then underwent surgical therapy. Subsequently, all patients were enrolled in a periodontal maintenance program with recall visits every 3.4 +/- 1.0 months for at least 10 years. At the latest recall visit (T2) the same radiographic measurements evaluated at baseline were taken and a DNA sample for IL-1 genetic susceptibility testing was collected and sent for analysis.

RESULTS

Twenty-three of the 60 patients (38.3%) were IL-1 genotype positive. A total of 52 teeth (3.3%) out of 1,566 were lost due to periodontitis between T0 and T2; 28 of 957 (2.9%) in the IL-1 genotype negative group and 24 of 609 (3.9%) in IL-1 genotype positive group. The mean variation in bone defect level (DeltaBD) averaged -0.04 mm in IL-1 genotype negative patients and 0.01 mm in IL-1 genotype positive patients. The mean variation in bone crest level (DeltaBC) averaged -0.24 mm in IL-1 genotype negative patients and -0.28 mm in IL-1 genotype positive patients. However, a few patients showed significant differences in response to therapy based on initial bone levels and genotype. IL-1 negative patients who showed minimal initial bone loss responded to the therapy better than the IL-1 positive patients. IL-1 positive patients with severe initial bone loss showed a better response to the therapy than IL-1 negative patients.

CONCLUSIONS

On average, there were no significant differences related to IL-1 genotype in tooth loss after 10 years in a non-smoking, well-maintained periodontal population. On an individual patient basis, the IL-1 genotype, in combination with the initial bone level, seems useful at the beginning of therapy for predicting bone level variation.

Donor interleukin 1 receptor antagonist genotype associated with acute graft-versus-host disease in human leucocyte antigen-matched sibling allogeneic transplants

Interleukin 1 (IL-1) is involved in various autoimmune and inflammatory diseases. IL-1 receptor antagonist (IL-1Ra) is the naturally occurring antagonist to IL-1alpha and -1beta. Polymorphisms of IL-1beta have been associated with variations in IL-1beta production (nucleotides +3953 and -511). A variable number tandem repeat (VNTR) polymorphism in the IL-1Ra gene has been associated (allele 2) with increased IL-1Ra production. We examined these polymorphisms in human leucocyte antigen (HLA)-matched allogeneic bone marrow transplant patients and donors. IL-1Ra VNTR (allele 2) in the donor genotype was more frequent with milder acute graft-versus-host disease (aGvHD) grades 0-II (29 out of 59 transplants) than severe GvHD grades III-IV (2 out of 18 transplants) (P = 0.0032). This association was confirmed in a subgroup with cyclosporine monotherapy prophylaxis: donor possession of allele 2 was again associated with milder aGvHD, grades 0-II (19 out of 38 transplants), than grades III-IV (1 out of 14) (P = 0.0042) transplants. No association was found between the IL-1beta -511 or IL-1beta +3953 polymorphism and severity of GvHD. Recipient IL-1Ra VNTR genotype (allele 2) showed a strong trend towards association with aGvHD severity (P = 0.0697). Thus, the donor genotype for the IL-1Ra polymorphism has an apparent protective role against acute GvHD following transplantation and may be an additional factor for individual risk assessment for complications, including GvHD, post transplant.

IL-1B and IL-1Ra gene polymorphisms and disease severity in rheumatoid arthritis: interaction with their plasma levels

The balance between interleukin-1 (IL-1) and its competitive antagonist IL-1 receptor antagonist (IL-1Ra) may contribute to the pathogenesis of rheumatoid arthritis (RA). We analysed the frequency of different alleles in the IL-1B gene (at -511 and at +3954) as well as in the IL-1Ra gene (at +2018) in an association study involving 297 RA patients and 112 healthy controls from the same geographic area. We tested associations with RA susceptibility or severity, and with circulating levels of IL-1Ra and IL-1beta. Carriage of the rare IL-1B (+3954) allele 2 was increased in destructive arthritis (DRA) as compared to non-destructive arthritis (NDRA) (OR 1.7, 95% CI 1.1-2.8, 49.0% vs 35.9%) and controls (OR 1.7, 95% CI 1.1-2.8, 35.8%). Patients carrying this allele had a more destructive (Larsen wrist radiological index: mean +/- s.e.m., 2.1 +/- 0.2 vs 1.6 +/- 0.1, P = 0.005; Steinbrocker functional index: 2.4 +/- 0.1 vs 1.9 +/- 0.1, P = 0.002) and active disease (Ritchie articular index: 8.1 +/- 0.8 vs 5.3 +/- 0.6, P = 0.002; erythrocyte sedimentation rate (ESR): 36.6 +/- 2.9 mm/h vs 25.3 +/- 1.8 mm/h, P = 0.002). This contribution was independent from that of HLA DR4/DR1 to severity. IL-1Ra plasma levels adjusted to ESR values were significantly lower in IL-1B2 (+3954) positive than negative RA patients (1.0 +/- 0.1 vs 1.2 +/- 0.1 ng/ml, P = 0.01). This IL-1B (+3954) gene polymorphism may be an important marker for the severity of joint destruction in RA and is associated with an imbalance in IL-1Ra production. As this genetic association was independent and additive to the risk of HLA DR4/DR1 status, it could be a useful addition to HLA-DR4/1 as a genetic prognostic marker early in the course of the disease.

Adhesion of Porphyromonas gingivalis strains to cultured epithelial cells from patients with a history of chronic adult periodontitis or from patients less susceptible to periodontitis

BACKGROUND

The present study aimed to explain the interindividual variation in periodontitis susceptibility by differences in the initial adhesion rate of Porphyromonas gingivalis to the pocket epithelium of these individuals, and/or by inter-P. gingivalis strain differences in association capacity (adhesion and internalization).

METHODS

Adhesion assays were performed on epithelial monolayers (cultured in vitro from pocket epithelium belonging to patients who were less or more susceptible to chronic adult periodontitis) using 11 genetically different clinical strains of P. gingivalis.

RESULTS

Both the disease category (less susceptible versus susceptible) and the interstrain variation were found to have a significant effect (both P <0.05) on the initial bacterial association. The chronic adult periodontitis group showed significantly more association of P. gingivalis when compared to less susceptible patients (4.2 x 10(6) versus 3.5 x 10(6)). Also, the interstrain variation was significant, with strains Pg 4 and 5 representing the least and best associating bacteria (1.8 x 10(6) colony forming units for Pg 4, 9 x 10(6) for Pg 5).

CONCLUSIONS

These results indicate that periodontitis susceptibility is influenced by both the interindividual differences in pocket epithelium (allowing more adhesion of P. gingivalis) or by the strain type by which the patient is infected (intra-species differences in adhesion capacity).

Association of tumor necrosis factor-alpha and interleukin-1 gene polymorphisms with silicosis

Silicosis, an interstitial lung disease prevalent among miners, sand blasters, and quarry workers, is manifested as a chronic inflammatory response leading to severe pulmonary fibrotic changes. Proinflammatory cytokines, such as TNFalpha and IL-1, produced in the lung by type II epithelial cells and alveolar macrophages, have been strongly implicated in the formation of these lesions. Recently, a number of single nucleotide polymorphisms (SNPs), which quantitatively affect mRNA synthesis, have been identified in the TNFalpha promoter and IL-1 gene cluster and their frequency is associated with certain chronic inflammatory diseases. To assess the role of these SNPs in silicosis, we examined their frequency in 325 ex-miners with moderate and severe silicosis and 164 miners with no lung disease. The odds ratio of disease for carriers of the minor variant, TNFalpha (-238), was markedly higher for severe silicosis (4.0) and significantly lower for moderate silicosis (0.52). Regardless of disease severity, the odds ratios of disease for carriers of the IL-1RA (+2018) or TNFalpha (-308) variants were elevated. There were no significant consistent differences in the distribution of the IL-1alpha (+4845) or IL-1beta (+3953) variants with respect to disease status. In addition, several significant gene-gene and gene-gene-environment interactions were observed. Different associations between moderate cases and controls versus severe cases and controls were also observed in a number of these multigene comparisons. These studies suggest that gene-environment interactions involving cytokine polymorphisms play a significant role in silicosis by modifying the extent of and susceptibility to disease.

Relationship of cigarette smoking to attachment level profiles

OBJECTIVES

The present investigation examined clinical features of periodontal disease and patterns of attachment loss in adult periodontitis subjects who were current, past or never smokers.

MATERIAL AND METHODS

289 adult periodontitis subjects ranging in age from 20-86 years with at least 20 teeth and at least 4 sites with pocket depth and/or attachment level >4 mm were recruited. Smoking history was obtained using a questionnaire. Measures of plaque accumulation, overt gingivitis, bleeding on probing, suppuration, probing pocket depth and probing attachment level were taken at 6 sites per tooth at all teeth excluding 3rd molars at a baseline visit. Subjects were subset according to smoking history into never, past and current smokers and for certain analyses into age categories <41, 41-49, >49. Uni- and multi-variate analyses examined associations between smoking category, age and clinical parameters.

RESULTS

Current smokers had significantly more attachment loss, missing teeth, deeper pockets and fewer sites exhibiting bleeding on probing than past or never smokers. Current smokers had greater attachment loss than past or never smokers whether the subjects had mild, moderate or severe initial attachment loss. Increasing age and smoking status were independently significantly related to mean attachment level and the effect of these parameters was additive. Mean attachment level in non smokers <41 years and current smokers >49 years was 2.49 and 4.10 mm respectively. Stepwise multiple linear regression indicated that age, pack years and being a current smoker were strongly associated with mean attachment level. Full mouth attachment level profiles indicated that smokers had more attachment loss than never smokers particularly at maxillary lingual sites and at lower anterior teeth.

CONCLUSIONS

In accord with other studies, smokers had evidence of more severe periodontal disease than past or never smokers. At all levels of mean attachment loss, smokers exhibited more disease than never smokers. Difference in mean attachment level between smokers and never smokers at individual sites was not uniform. Significantly more loss was observed at maxillary lingual sites and lower anterior teeth suggesting the possibility of a local effect of cigarette smoking.