Evidence of a substantial genetic basis for IgG2 levels in families with aggressive periodontitis

Impact of Treatment on Host Responses in Young Individuals with Periodontitis

Grade C periodontitis in young individuals is characterized by severe/rapid periodontal destruction, usually early onset, in systemically healthy individuals. An individual's host response, triggered by a dysbiotic subgingival biofilm, has been reported as a contributor to the tissue destruction, although mechanisms of this response and contributions to such disease remain poorly understood. Nonsurgical treatment has resulted in positive clinical responses for both localized (now molar-incisor pattern) and generalized forms of grade C periodontitis, especially when adjunctive systemic antibiotics are used. Nonsurgical treatment may also affect host responses, although mechanisms leading to significant changes in this response remain unclear. Significant effects on inflammatory response to antigens/bacteria have been described posttreatment, but evidence for long-term effects remains limited. Nonsurgical treatment in these individuals may also modulate a variety of host markers in serum/plasma and gingival crevicular fluid along with clinical parameter improvements. The impact of other adjuncts to nonsurgical treatment focusing on controlling exacerbated immunoinflammatory responses needs to be further explored in grade C periodontitis in young individuals. Recent evidence suggests that nonsurgical treatment with adjunctive laser therapy may modulate host and microbial responses in those subjects, at least in the short term. Available evidence, while very heterogeneous (including variations in disease definition and study designs), does not provide clear conclusions on this topic yet provides important insights for future studies. In this review, studies within the past decade evaluating the impact of nonsurgical treatment on systemic/local host responses in young individuals with grade C periodontitis, as well as long-term clinical responses posttreatment, will be critically appraised and discussed.

National survey of periodontal diseases in adolescents and young adults in Morocco

AIM

National surveys of periodontal diseases in children are rare. This study describes the first national survey of oral health of adolescents attending public schools in Morocco. We report the prevalence and demographic determinants of periodontal diseases, and generate population estimates for this young population.

MATERIALS AND METHODS

This study used a multi-stage probability sample comprising 14,667 students in 87 schools and 520 classrooms, representative of students attending grades 6-12 (age 12-18 years) in Morocco. The students were interviewed and then examined clinically to assess their periodontal status, which was classified according to the 2017 World Workshop. In addition, the diagnosis of aggressive periodontitis (AgP) was assessed.

RESULTS

Of approximately 3 million students in this age cohort, 12.3% (or approximately 360,894 subjects) had periodontitis and 46.9% (1.4 million) had gingivitis. They comprised 10.8%, 2.9%, and 6.1% subjects with periodontitis stage I, II, and III/IV, respectively; 5.0%, or 148,336 subjects, had AgP. The prevalence rates were not significantly different by gender or urban status. However, the prevalence of AgP was particularly high in certain regions of Morocco.

CONCLUSIONS

The prevalence of staged periodontitis and AgP in this young population is among the highest reported in national surveys worldwide.

Association of Self-Perceived Psychological Stress with the Periodontal Health of Socially Deprived Women in Shelter Homes

The present study aimed to assess the effect of self-perceived psychological stress on the periodontal health of socially deprived women. The study included three hundred and eighty-five socially deprived women residing in shelter homes. The presence of stress and its severity was assessed by using Sheldon Cohen's 10-item perceived stress scale (PSS), and periodontal health status was assessed utilizing the community periodontal index. Statistical analyses were performed using an independent sample t-test, a one-way ANOVA, the Pearson chi-Square test, and binary logistic regression. Results: A total of 385 samples were included, the majority of whom (n = 297; 72.5%) belonged to the age group of 15-30 years. There were 34 (8.8%) participants who were educated up to graduate level. A total of 47.8% of the women were found with healthy periodontal status, and 52.5% of the samples were diagnosed with major psychological stress. Half of the samples (201-52.2%) had a periodontal problem. The mean PSS was found statistically significant concerning age group, education, and psychological stress level. In the univariate logistic regression analysis, a significant association of periodontal status was observed with the age group 31-45 years [(OR = 1.76; 95% C.I (1.11-2.78)] and with a major psychological stress level [(OR = 2.60; 95% C.I (1.72-3.93)]. Psychosocial stress among socially deprived women was found to be a risk factor for periodontal disease.

What Is the Heritability of Periodontitis? A Systematic Review

The aim of this study was to systematically appraise the existing literature on the yet-unclear heritability of gingivitis and periodontitis. This review was conducted following the PRISMA guidelines. A search was conducted through the electronic databases Medline, Embase, LILACS, Cochrane Library, Open Grey, Google Scholar, and Research Gate, as complemented by a hand search, for human studies reporting measures of heritability of gingivitis and periodontitis. A total of 9,037 papers were initially identified from combined databases and 10,810 on Google Scholar. After full-text reading, 28 articles met the inclusion criteria and were carried forward to data abstraction. The reviewed data included information from >50,000 human subjects. Meta-analyses were performed by grouping studies based on design and outcome. Heritability ( H2) of periodontitis was estimated at 0.38 (95% CI, 0.34 to 0.43; I2 = 12.9%) in twin studies, 0.15 (95% CI, 0.06 to 0.24; I2 = 0%) in other family studies, and 0.29 (95% CI, 0.21 to 0.38; I2 = 61.2%) when twin and other family studies were combined. Genome-wide association studies detected a lower heritability estimate of 0.07 (95% CI, -0.02 to 0.15) for combined definitions of periodontitis, increasing with disease severity and when the interaction with smoking was included. Furthermore, heritability tended to be lower among older age groups. Heritability for the self-reported gingivitis trait was estimated at 0.29 (95% CI, 0.22 to 0.36; I2 = 37.6%), while it was not statistically significant for clinically measured gingivitis. This systematic review brings forward summary evidence to confirm that up to a third of the periodontitis variance in the population is due to genetic factors. This seems consistent across the different studied populations and increases with disease severity. In summary, up to a third of the variance of periodontitis in the population is due to genetic factors, with higher heritability for more severe disease.

MicroRNAs responsive to Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis LPS modulate expression of genes regulating innate immunity in human macrophages

MicroRNAs (miRNAs) are a class of small, noncoding RNAs that regulate post-transcriptional expression of their respective target genes and are responsive to various stimuli, including LPS. Here we examined the early (4 h) miRNA responses of THP1-differentiated macrophages challenged with LPS derived from the periodontal pathogens, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis or environmentally-modified LPS obtained from P. gingivalis grown in cigarette smoke extract. Predicted miRNA-gene target interactions for LPS-responsive miR-29b and let-7f were confirmed using dual-luciferase assays and by transfection experiments using miRNA mimics and inhibitors. Convergent and divergent miRNA profiles were observed in treated samples where differences in miRNA levels related to the type, concentration and incubation times of LPS challenge. Dual-luciferase experiments revealed miR-29b targeting of interleukin-6 receptorα (IL-6Rα) and IFN-γ inducible protein 30 and let-7f targeting of suppressor of cytokine signaling 4 and thrombospondin-1. Transfection experiments confirmed miR-29b and let-7f modulation of IL-6Rα and SOCS4 protein expression levels, respectively. Thus, we have demonstrated convergent/divergent miRNA responses to wild type LPS and its environmentally-modified LPS, and demonstrate miRNA targeting of key genes linked to inflammation and immunity. Our data indicate that these LPS-responsive miRNAs may play a key role in fine-tuning the host response to periodontal pathogens.

The oral-systemic personalized medicine model at Marshfield Clinic

Periodontal disease and diabetes, two diseases that have achieved epidemic status, share a bidirectional relationship driven by micro-inflammatory processes. The present review frames the current understanding of the pathological processes that appear to link these diseases and advances the hypothesis that reversal of the epidemic is possible through application of interdisciplinary intervention and advancement of oral-systemic personalized medicine. An overview of how Marshfield Clinic's unique clinical, informatics and bio-repository resources and infrastructures are being aligned to advance oral-systemic personalized medicine is presented as an interventional model with the potential to reverse the epidemic trends seen for these two chronic diseases over the past several decades. The overall vision is to engineer a transformational shift in paradigm from 'personalized medicine' to 'personalized health'.

Birth weight of infants of mothers with aggressive periodontitis

BACKGROUND

It was hypothesized that if periodontal infections predispose low birth weights and premature birth, then such outcomes should be apparent when the mother has aggressive periodontitis (AgP).

METHODS

Birth weight data were collected by questionnaire from females with AgP, their periodontally healthy siblings, and unrelated periodontally healthy women. Both prospective and retrospective birth outcome data were used. Because many of the periodontal evaluations were performed after the births, there were incomplete data regarding most of the risk factors for low birth weight. We determined associations between mothers' periodontal diagnoses and clinical variables and the reported birth weights.

RESULTS

There were no significant differences in mean birth weights of babies born to control subjects or AgP patients. This was true whether all the births were considered or only those reported <1 or 2 years before periodontal examination. For periodontally healthy controls, 13.2% of babies born to siblings of AgP patients and 12.8% of babies born to unrelated mothers weighed <2,500 g, whereas 9.9% of those born to mothers with generalized AgP and 10.3% of those born to mothers with localized AgP weighed <2,500 g.

CONCLUSIONS

Because of the relative rarity of AgP in the population, and attendant difficulties in performing a prospective study of its association with pregnancy outcomes, we used a compromised approach using prospective data as well as weaker retrospective data assuming that disease onset was likely before the births. Our results, within the limitations of this approach, indicate no evidence that AgP in the mother predisposes low birth weights. AgP has many unique biologic characteristics that differentiate it from chronic forms of periodontal disease, and the possible lack of its association with birth weight may be another such characteristic.

Heritability of alveolar bone loss from periodontal disease in a baboon population: a pilot study

BACKGROUND

Reports from studies of twins, disease aggregation in families, animal models for periodontal disease, and various genetic-analysis studies have determined that genetics plays a role in the susceptibility to periodontal disease. The purpose of this pilot study is to evaluate the effect of genetics on periodontal disease by evaluating the heritability of alveolar bone loss in a captive baboon population.

METHODS

A collection of baboon skulls from a pedigreed colony (for which scientists and veterinarians maintain complete genealogic and veterinary records) was obtained from the Southwest National Primate Research Center, San Antonio, Texas and used in this pilot study. Measurements of alveolar bone loss were performed on 390 dry baboon skulls. A periodontal probe was used to measure alveolar bone loss. Maximum likelihood methods (designed to handle complex genealogies) were used to determine the heritability of alveolar bone loss. This software used known pedigrees in the captive baboon sample and tested the relationship between pairwise kinship and alveolar bone loss data to determine the heritability of alveolar bone loss from periodontal disease.

RESULTS

Genetic data were available for 347 of the 390 specimens. Using age and sex as covariates, genetic analysis indicated a heritability of 35% (standard error = 20%; P = 0.01). Although gender was not a significant factor in periodontal disease (P = 0.96), age was highly significantly associated with periodontal disease (P <0.0001).

CONCLUSIONS

In this pilot study, analysis of alveolar bone loss measurements from captive baboons indicates that bone loss increases with age and that a portion of periodontal disease risk may be caused by genetic variance. These findings provide evidence that periodontal disease is heritable in captive baboons and indicate that a larger, more-detailed study is warranted.

Aggressive periodontitis is likely influenced by a few small effect genes

AIM

To evaluate the inheritance mode of aggressive periodontitis in a collection of families with a similar geographic origin.

MATERIALS AND METHODS

Segregation analysis was performed in pedigree data from 74 families by the use of the SEGREG program of SAGE v.5.4.2. Homogeneous no transmission, homogeneous Mendelian transmission, homogeneous general transmission, semi-general transmission and heterogeneous general transmission models were tested assuming the prevalence of aggressive periodontitis as 1% and no deviations from Hardy-Weinberg equilibrium. The parameters of the model were estimated by the method of maximum likelihood, which provides the overall ln (likelihood), -2ln and the AIC (Akaike's score) for each model. The likelihood ratio test (LRT) was used to compare each model against a fully general model (p>0.05).

RESULTS

The most parsimonious mode of inheritance was the semi-general transmission model that allows the heterozygote transmission probability to vary.

CONCLUSION

This result provides strong support for the hypothesis that genetic factors play a role in aggressive periodontitis and that a few loci, each with relatively small effects, contribute to aggressive periodontitis, with or without interaction with environmental factors.

Single-nucleotide polymorphisms in the IL-4 and IL-13 promoter region in aggressive periodontitis

INTRODUCTION

IL-4 and IL-13 polymorphisms have been shown to influence the susceptibility to systemic diseases. In this study, possible associations between the IL-4 -590 C-->T, IL-4 -34 C-->T, IL-13 -1112 C-->T and IL-13 -1512 A-->C promoter polymorphisms were investigated in subjects with generalized aggressive periodontitis (AgP) compared with healthy individuals.

MATERIAL AND METHODS

Fifty-eight patients with diagnosis of generalized AgP and 51 matched healthy controls participated in the study. Blood samples were collected and DNA isolated. Molecular analyses were performed by PCR-RFLP in a blind fashion. Genotype and allele frequencies among study groups were compared using Fisher's exact test (alpha value: 0.05). Pearson's chi(2) test was used for analysis of Hardy-Weinberg equilibrium.

RESULTS

The frequency of the IL-4 -590 T/T and IL-4 -34 T/T genotypes differed significantly between groups (p=0.05, 0.02, respectively), although the allele frequencies were similar. There was a higher frequency of the IL-4 -590 T/T and IL-4 -34 T/T genotypes in patients with AgP compared with controls. The genotype and allele frequencies of the IL-13 polymorphisms did not differ between groups.

CONCLUSIONS

This study demonstrated an association between the IL-4 -590 T/T and IL-4 -34 T/T genotypes and AgP. Further research is necessary to prove if there is an association of these polymorphisms with AgP, and if the polymorphisms have a functional effect.

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis subgingival presence, species-specific serum immunoglobulin G antibody levels, and periodontitis disease recurrence

BACKGROUND AND OBJECTIVE

The biological and clinical effects of antibody against periodontal pathogenic bacteria are incompletely understood. This study evaluated the inter-relationships among periodontal levels of cultivable Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, species-specific serum immunoglobulin G (IgG) antibody levels, and periodontitis disease activity.

MATERIAL AND METHODS

Forty-three adults who had previously been treated for periodontitis and who also harbored cultivable A. actinomycetemcomitans or P. gingivalis were evaluated semiannually for clinical disease recurrence over a 36-month period. Each patient provided subgingival microbial samples, for the recovery of A. actinomycetemcomitans and P. gingivalis, from the two deepest pockets in each dentition sextant. A. actinomycetemcomitans and P. gingivalis serum IgG antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA), together with whole-cell sonicate extracts from A. actinomycetemcomitans serotypes a-c and P. gingivalis ATCC 33277. Data were analyzed using the Mantel-Haenszel chi-square and Fisher exact two-tailed tests.

RESULTS

Eighteen (60.0%) of 30 A. actinomycetemcomitans-positive subjects, and 10 (76.9%) of 13 P. gingivalis-positive subjects, exhibited recurrent periodontal breakdown within 36 months of periodontal therapy. Nineteen (67.9%) of the 28 patients with active periodontitis had A. actinomycetemcomitans or P. gingivalis serum antibody levels below designated threshold values. In comparison, 10 (66.7%) of 15 culture-positive clinically stable subjects showed A. actinomycetemcomitans or P. gingivalis serum antibody levels above threshold values. The difference between specific antibody levels in periodontitis-active and periodontitis-stable patients was statistically significant (p = 0.032).

CONCLUSIONS

Serum levels of IgG antibodies against A. actinomycetemcomitans or P. gingivalis in periodontitis-stable patients were higher than those in patients with active periodontitis. The results suggest that elevated levels of IgG antibody against A. actinomycetemcomitans and P. gingivalis have a detectable protective effect against periodontal infections with these microorganisms.

Periodontal status among relatives of aggressive periodontitis patients and reliability of family history report

OBJECTIVES

To assess the periodontal status of relatives of Aggressive Periodontitis (AgP) patients, and to evaluate the reliability of the family history report as provided by the proband.

MATERIAL AND METHODS

Data from 54 AgP patients were gathered along with a family history report for each of their relatives. Only 27 patients (probands) had relatives willing to be examined. This yielded a total of 61 relatives from whom the periodontal status was obtained. The family history report for each examined relative was compared with the periodontal diagnosis made at examination to assess reliability.

RESULTS

Eight percentage of the examined relatives, aged between 12-76, were diagnosed with AgP, while chronic periodontitis was present in 39%, gingivitis in 38% and 15% were healthy. If the report provided by the proband was positive, the likelihood of finding any type of periodontitis in that relative was 85.7%, whereas if the report was negative the likelihood of the absence of periodontitis was 70.6%.

CONCLUSION

The percentage of examined relatives who were affected with AgP (8%), although lower than percentages reported in other AgP family studies, was still higher than the prevalence of the condition in random populations. Reliability of periodontal family history was considered good and more reliable when it was positive.