Identification of genetic risk factors of aggressive periodontitis using genomewide association studies in association with those of chronic periodontitis

hsa_circ_0095812 accelerates periodontitis progression by adsorbing miR-485-3p-mediated THBS1 expression

OBJECTIVE

To explore the role of hsa_circ_0095812 (circLRRC4C) in periodontitis and its mechanism with miR-485-3p and Thrombospondin-1 (THBS1).

METHODS

Periodontal tissues were collected from periodontitis patients. Periodontal Ligament Cells (PDLCs) were stimulated with Lipopolysaccharide (LPS) and transfected. Cell viability, inflammation, apoptosis, and pyroptosis were analyzed. A mouse model of periodontitis was constructed and injected with a lentiviral plasmid vector targeting circLRRC4C. Immunohistochemistry was performed on the periodontal tissue of model mice. The relevant expression level of genes was measured via real-time reverse transcriptase-polymerase chain reaction or Western blot. The relationship between circLRRC4C and THBS1 with miR-485-3p was analyzed.

RESULTS

CircLRRC4C was highly expressed in periodontitis tissues of patients and LPS-treated PDLCs. Downregulating circLRRC4C attenuated LPS-induced PDLC inflammation, apoptosis and pyroptosis and recovered cellular viability. CircLRRC4C acted as a sponge for miR-485-3p. CircLRRC4C affected LPS-induced PDLC apoptosis, pyroptosis and inflammation by regulating miR-485-3p. THBS1 was the target gene of miR-485-3p. Inhibition of THBS1 effectively improved LPS-induced periodontitis. CircLRRC4C aggravated LPS-induced PDLC apoptosis, pyroptosis and inflammation by regulating the miR-485-3p/THBS1 axis. Suppressing circLRRC4C effectively improved periodontitis in mice.

CONCLUSION

CircLRRC4C induces periodontitis progression by adsorbing miR-485-3p-mediated THBS1 expression.

Genome-wide association studies on periodontitis: A systematic review

OBJECTIVES

This study aims to systematically review the existing literature and critically appraise the evidence of genome-wide association studies (GWAS) on periodontitis. This study also aims to synthesise the findings of genetic risk variants of periodontitis from included GWAS.

METHODS

A systematic search was conducted on PubMed, GWAS Catalog, MEDLINE, GLOBAL HEALTH and EMBASE via Ovid for GWAS on periodontitis. Only studies exploring single-nucleotide polymorphisms(SNPs) associated with periodontitis were eligible for inclusion. The quality of the GWAS was assessed using the Q-genie tool. Information such as study population, ethnicity, genomic data source, phenotypic characteristics(definition of periodontitis), and GWAS methods(quality control, analysis stages) were extracted. SNPs that reached conventional or suggestive GWAS significance level(5e-8 or 5e-06) were extracted and synthesized.

RESULTS

A total of 15 good-quality GWAS on periodontitis were included (Q-genie scores ranged from 38-50). There were huge heterogeneities among studies. There were 11 identified risk SNPs (rs242016, rs242014, rs10491972, rs242002, rs2978951, rs2738058, rs4284742, rs729876, rs149133391, rs1537415, rs12461706) at conventional GWAS significant level (p<5x10-8), and 41 at suggestive level (p<5x10-6), but no common SNPs were found between studies. Three SNPs (rs4284742 [G], rs11084095 [A], rs12461706 [T]) from three large studies were from the same gene region-SIGLEC5.

CONCLUSION

GWAS of periodontitis showed high heterogeneity of methodology used and provided limited SNPs statistics, making identifying reliable risk SNPs challenging. A clear guidance in dental research with requirement of expectation to make GWAS statistics available to other investigators are needed.

Clinical and laboratory assessment of the state of periapical tissues in systemic lupus erythematosus

OBJECTIVE

Aim: To evaluate changes in clinical and laboratory parameters in patients with SLE depending on the severity and activity of the disease.

PATIENTS AND METHODS

Materials and Methods: The study included 50 patients with SLE of different age groups, 10 men and 40 women.

RESULTS

Results: Systemic lupus erythematosus (SLE) is a chronic disease that belongs to the group of rheumatic diseases and is characterised by autoimmune tissue damage. Chronic inflammatory periodontal diseases remain one of the most common dental pathologies. Chronic gingivitis and periodontitis in SLE are described as one of the earliest and most striking symptoms of the disease. Approximately the same trend was found in patients with SLE depending on the degree of clinical and laboratory activity of the disease. Patients with minimal, 1 degree of activity (characterized by the longest duration of SLE) showed the greatest decrease in bone mineral density (up to 2.25 points), and patients with higher activity had a significantly shorter duration of SLE and, accordingly, a smaller decrease in bone mineral density: in patients with 2 degrees of activity (1.79 points), with 3 degrees of activity (1.94 points).

CONCLUSION

Conclusions: In patients with acute SLE, the maximum value of the Muhlemann-Cowell index was 2.31 points, in patients with subacute SLE - 1.89 points, and in patients with chronic SLE - 1.58 points. CPITN values increase inversely with the nature of the course of SLE, which is associated with the duration of the underlying disease.

Genome- and Transcriptome-Wide Association Studies Identify Susceptibility Genes and Pathways for Periodontitis

Several genes associated with periodontitis have been identified through genome-wide association studies (GWAS); however, known genes only explain a minority of the estimated heritability. We aimed to explore more susceptibility genes and the underlying mechanisms of periodontitis. Firstly, a genome-wide meta-analysis of 38,532 patients and 316,185 healthy controls was performed. Then, cross- and single-tissue transcriptome-wide association studies (TWAS) were conducted based on GWAS summary statistics and the Genotype-Tissue Expression (GTEx) project. Risk genes were evaluated to determine if they were differentially expressed in periodontitis sites compared with unaffected sites using public datasets. Finally, gene co-expression network analysis was conducted to identify the functional biology of the susceptible genes. A total of eight single nucleotide polymorphisms (SNPs) within the introns of lncRNA LINC02141 approached genome-wide significance after meta-analysis. EZH1 was identified as a novel susceptibility gene for periodontitis by TWAS and was significantly upregulated in periodontitis-affected gingival tissues. EZH1 co-expression genes were greatly enriched in the cell-substrate junction, focal adhesion and other important pathways. Our findings may offer a fundamental clue for comprehending the genetic mechanisms of periodontitis.

Epigenetics in susceptibility, progression, and diagnosis of periodontitis

Periodontitis is characterized by irreversible destruction of periodontal tissue. At present, the accepted etiology of periodontitis is based on a three-factor theory including pathogenic bacteria, host factors, and acquired factors. Periodontitis development usually takes a decade or longer and is therefore called chronic periodontitis (CP). To search for genetic factors associated with CP, several genome-wide association study (GWAS) analyses were conducted; however, polymorphisms associated with CP have not been identified. Epigenetics, on the other hand, involves acquired transcriptional regulatory mechanisms due to reversibly altered chromatin accessibility. Epigenetic status is a condition specific to each tissue and cell, mostly determined by the responses of host cells to stimulations by local factors, like bacterial inflammation, and systemic factors such as nutrition status, metabolic diseases, and health conditions. Significantly, epigenetic status has been linked with the onset and progression of several acquired diseases. Thus, epigenetic factors in periodontal tissues are attractive targets for periodontitis diagnosis and treatments. In this review, we introduce accumulating evidence to reveal the epigenetic background effects related to periodontitis caused by genetic factors, systemic diseases, and local environmental factors, such as smoking, and clarify the underlying mechanisms by which epigenetic alteration influences the susceptibility of periodontitis.

Identification of potentially functional circRNAs and prediction of circRNA-miRNA-mRNA regulatory network in periodontitis: Bridging the gap between bioinformatics and clinical needs

Background and Objective

Periodontitis is a multifactorial chronic inflammatory disease that can lead to the irreversible destruction of dental support tissues. As an epigenetic factor, the expression of circRNA is tissue‐dependent and disease‐dependent. This study aimed to identify novel periodontitis‐associated circRNAs and predict relevant circRNA‐periodontitis regulatory network by using recently developed bioinformatic tools and integrating sequencing profiling with clinical information for getting a better and more thorough image of periodontitis pathogenesis, from gene to clinic.

Material and Methods

High‐throughput sequencing and RT‐qPCR were conducted to identify differentially expressed circRNAs in gingival tissues from periodontitis patients. The relationship between upregulated circRNAs expression and probing depth (PD) was performed using Spearman's correlation analysis. Bioinformatic analyses including GO analysis, circRNA‐disease association prediction, and circRNA‐miRNA‐mRNA network prediction were performed to clarify potential regulatory functions of identified circRNAs in periodontitis. A receiver‐operating characteristic (ROC) curve was established to assess the diagnostic significance of identified circRNAs.

Results

High‐throughput sequencing identified 70 differentially expressed circRNAs (68 upregulated and 2 downregulated circRNAs) in human periodontitis (fold change >2.0 and p < .05). The top five upregulated circRNAs were validated by RT‐qPCR that had strong associations with multiple human diseases, including periodontitis. The upregulation of circRNAs were positively correlated with PD (R = .40–.69, p < .05, moderate). A circRNA‐miRNA‐mRNA network with the top five upregulated circRNAs, differentially expressed mRNAs, and overlapped predicted miRNAs indicated potential roles of circRNAs in immune response, cell apoptosis, migration, adhesion, and reaction to oxidative stress. The ROC curve showed that circRNAs had potential value in periodontitis diagnosis (AUC = 0.7321–0.8667, p < .05).

Conclusion

CircRNA‐disease associations were predicted by online bioinformatic tools. Positive correlation between upregulated circRNAs, circPTP4A2, chr22:23101560‐23135351+, circARHGEF28, circBARD1 and circRASA2, and PD suggested function of circRNAs in periodontitis. Network prediction further focused on downstream targets regulated by circRNAs during periodontitis pathogenesis.

Mucosal circadian rhythm pathway genes altered by aging and periodontitis

As circadian processes can impact the immune system and are affected by infections and inflammation, this study examined the expression of circadian rhythm genes in periodontitis.

METHODS

Macaca mulatta were used with naturally-occurring and ligature-induced periodontitis. Gingival tissue samples were obtained from healthy, diseased, and resolved sites in four groups: young (≤3 years), adolescent (3-7 years), adult (12-26) and aged (18-23 years). Microarrays targeted circadian rhythm (n = 42), inflammation/tissue destruction (n = 11), bone biology (n = 8) and hypoxia pathway (n = 7) genes.

RESULTS

The expression of many circadian rhythm genes, across functional components of the pathway, was decreased in healthy tissues from younger and aged animals, as well as showing significant decreases with periodontitis. Negative correlations of the circadian rhythm gene levels with inflammatory mediators and tissue destructive/remodeling genes were particularly accentuated in disease. A dominance of positive correlations with hypoxia genes was observed, except HIF1A, that was uniformly negatively correlated in health, disease and resolution.

CONCLUSIONS

The chronic inflammation of periodontitis exhibits an alteration of the circadian rhythm pathway, predominantly via decreased gene expression. Thus, variation in disease expression and the underlying molecular mechanisms of disease may be altered due to changes in regulation of the circadian rhythm pathway functions.

Oral Colonization by Entamoeba gingivalis and Trichomonas tenax: A PCR-Based Study in Health, Gingivitis, and Periodontitis

BACKGROUND

The etiology of periodontitis remains unclear, as is the place of gingivitis in its pathophysiology. A few studies linked the colonization by oral parasites (Entamoeba gingivalis and Trichomonas tenax) to periodontal disease and its severity. The aim of the current study was to estimate the prevalence of these oral parasites among healthy individuals, and in patients with gingivitis and periodontitis in Jordan.

METHODS

The study was conducted during July 2019-December 2019. Samples were composed of saliva and periodontal material including dental plaque sampled with probes. The detection of oral parasites was done using conventional polymerase chain reaction (PCR).

RESULTS

The total number of study participants was 237: healthy (n=94), gingivitis (n=53) and periodontitis (n=90). The prevalence of E. gingivalis was 88.9% among the periodontitis patients, 84.9% among the gingivitis patients and 47.9% in the healthy group. For T. tenax, the prevalence was 25.6% among the periodontitis patients, 5.7% among the gingivitis patients and 3.2% in the heathy group. Positivity for E. gingivalis was significantly correlated with the presence of periodontal disease compared to the healthy group with odds ratio (OR) of 6.6. Periodontal disease was also correlated with lower monthly income (OR=8.2), lack of dental care (OR=4.8), and history of diabetes mellitus (OR=4.5). Colonization by E. gingivalis was correlated with gingivitis (OR=6.1) compared to the healthy group. Colonization by E. gingivalis and T. tenax were significantly correlated with periodontitis (OR=6.4 for E. gingivalis, and OR=4.7, for T. tenax) compared to the healthy group. T. tenax was only detected among individuals with generalized periodontal disease compared to its total absence among those with localized disease (19.6% vs. 0.0%; p=0.039). The co-infection rate by the two oral parasites was 11.0%.

CONCLUSIONS

The higher prevalence of human oral parasites in periodontal disease compared to healthy individuals appears to be more than a mere marker for the disease and might also be associated with disease severity and potential for progression. Thus, the dogmatic view of E. gingivalis and T. tenax as commensals needs to be re-evaluated and their contribution to pathophysiology of periodontal diseases cannot be neglected.

Periodontal Inflammation and Systemic Diseases: An Overview

Periodontitis is a common inflammatory disease of infectious origins that often evolves into a chronic condition. Aside from its importance as a stomatologic ailment, chronic periodontitis has gained relevance since it has been shown that it can develop into a systemic condition characterized by unresolved hyper-inflammation, disruption of the innate and adaptive immune system, dysbiosis of the oral, gut and other location's microbiota and other system-wide alterations that may cause, coexist or aggravate other health issues associated to elevated morbi-mortality. The relationships between the infectious, immune, inflammatory, and systemic features of periodontitis and its many related diseases are far from being fully understood and are indeed still debated. However, to date, a large body of evidence on the different biological, clinical, and policy-enabling sources of information, is available. The aim of the present work is to summarize many of these sources of information and contextualize them under a systemic inflammation framework that may set the basis to an integral vision, useful for basic, clinical, and therapeutic goals.

The Association between IL2 Genotypes and Risk and Severity of Chronic Periodontitis in a Chinese Han Population: A Case-control Study

Chronic periodontitis (CP) is a kind of multifactorial common oral diseases. Multiple immune molecules including interleukin-2 (IL-2) are involved in the occurrence and development of CP. To investigate the association between the IL2 rs2069762 polymorphism and the risk of CP in Chinese individuals, we recruited 375 CP patients and 443 controls in this case-control study. The PCR-RFLP method was used for genotyping. Data revealed that the GG genotype was related with a decreased risk of CP (GG vs TT: OR, 0.58, 95%CI, 0.37-0.92, P-value = 0.020; GG vs TG+TT: OR, 0.61, 95%CI, 0.39-0.94, P-value = 0.027). Besides, G allele was shown to decrease the risk of CP. In addition, the IL2 rs2069762 polymorphism was related with the severity of CP. To sum up, the IL2 rs2069762 polymorphism is related with a decreased risk and severity of CP in Chinese individuals.

Epigenetic regulation of inflammation in periodontitis: cellular mechanisms and therapeutic potential

Epigenetic mechanisms, namely DNA and histone modifications, are critical regulators of immunity and inflammation which have emerged as potential targets for immunomodulating therapies. The prevalence and significant morbidity of periodontitis, in combination with accumulating evidence that genetic, environmental and lifestyle factors cannot fully explain the susceptibility of individuals to disease development, have driven interest in epigenetic regulation as an important factor in periodontitis pathogenesis. Aberrant promoter methylation profiles of genes involved in inflammatory activation, including TLR2, PTGS2, IFNG, IL6, IL8, and TNF, have been observed in the gingival tissue, peripheral blood or buccal mucosa from patients with periodontitis, correlating with changes in expression and disease severity. The expression of enzymes that regulate histone acetylation, in particular histone deacetylases (HDACs), is also dysregulated in periodontitis-affected gingival tissue. Infection of gingival epithelial cells, gingival fibroblasts and periodontal ligament cells with the oral pathogens Porphyromonas gingivalis or Treponema denticola induces alterations in expression and activity of chromatin-modifying enzymes, as well as site-specific and global changes in DNA methylation profiles and in histone acetylation and methylation marks. These epigenetic changes are associated with excessive production of inflammatory cytokines, chemokines, and matrix-degrading enzymes that can be suppressed by small molecule inhibitors of HDACs (HDACi) or DNA methyltransferases. HDACi and inhibitors of bromodomain-containing BET proteins ameliorate inflammation, osteoclastogenesis, and alveolar bone resorption in animal models of periodontitis, suggesting their clinical potential as host modulation therapeutic agents. However, broader application of epigenomic methods will be required to create a comprehensive map of epigenetic changes in periodontitis. The integration of functional studies with global analyses of the epigenetic landscape will provide critical information on the therapeutic and diagnostic potential of epigenetics in periodontal disease.

Periodontal health and disease: The contribution of genetics

Periodontitis is an infectious, inflammatory disease that is associated with a complex interplay between specific bacteria, host response, and environmental factors. Because of its high degree of familial aggregation, specifically for the more aggressive forms of the disease, genetics factors have been implicated in disease pathogenesis for several decades. This review provides an overview of what we currently know regarding the genetic and epigenetic contributions to periodontal disease and discusses future opportunities in the field.

Polymorphisms in the interleukin genes and chronic periodontitis: A field synopsis and revaluation by Bayesian approaches

Periodontitis is a high prevalent disease into the clinical dentistry. Genetic variations in interleukins (IL) genes were associated with chronic periodontitis (CP) and were focus of several meta-analyses. This study aimed to assess the noteworthiness in the meta-analyses by means of a Bayesian approach to determinate possible false report associations. A systematic search was performed for meta-analyses with associations between gene polymorphisms in interleukins and CP. The calculations for the False-Positive Rate Probability (FPRP) and the Bayesian False Discovery Probability (BFDP) were performed to assess the noteworthiness with a statistical power of 1.2 and 1.5 of Odds Ratio at a prior probability of 10^-3 and 10^-6. As results, eight meta-analyses approaching the IL1A/rs1800587, IL1B/rs1143634, IL1RN/rs2234663, IL4/rs2243250, IL6/rs1800795/rs1800796, IL17A/rs2275913 and IL18/rs1946518/rs187238 polymorphisms have been identified. Twenty-two from 270 calculations (8.15%) were noteworthy. Herein, we have identified the IL1A and IL1B polymorphisms as noteworthy biomarkers for CP susceptibility.

Association among serum and salivary A. actinomycetemcomitans specific immunoglobulin antibodies and periodontitis

BACKGROUND

The aim of this study was to assess the association between serum and salivary Immunoglobulin (Ig) Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) specific antibodies in healthy controls (HC) and periodontitis (PT) patients. Furthermore, the objectives were to determine whether PT influenced serum A. actinomycetemcomitans specific antibodies and whether serum or salivary antibodies against A. actinomycetemcomitans IgG were mediated by serum high-sensitivity c-reactive protein (hs-CRP).

METHODS

Fifty-three patients with periodontitis and 48 HC were enrolled in the present study. Patients were regularly examined and characterized by clinical, salivary and blood samples analyses. A. actinomycetemcomitans IgA and IgG antibodies and hs-CRP were evaluated using a commercially available kit. The Spearman Correlation Test and Jonckheere-Terpstra Test were applied in order to assess the interdependence between serum A. actinomycetemcomitans IgG antibodies and clinical periodontal parameters. To evaluate the dependence of the serum and salivary A. actinomycetemcomitans IgG levels from possible confounders, univariate and multivariable linear regression analyses were performed.

RESULTS

Compared to HC, patients with PT had significantly higher IgA [serum: PT, 1.89 (1.2-2.2) EU vs HC, 1.37 (0.9-1.8) EU (p = 0.022); saliva: PT, 1.67 (1.4-2.1) EU vs HC, 1.42 (0.9-1.6) EU (p = 0.019)] and A. actinomycetemcomitans IgG levels [serum: PT, 2.96 (2.1-3.7) EU vs HC, 2.18 (1.8-2.1) EU (p < 0.001); saliva, PT, 2.19 (1.8-2.5) EU vs HC, 1.84 (1.4-2) EU (p = 0.028)]. In PT patients, serum A. actinomycetemcomitans IgG were associated with a proportional extent of PT and tooth loss (P-trend value< 0.001). The univariate regression analysis demonstrated that PT (p = 0.013) and high hs-CRP (p < 0.001) had a significant negative effect on serum and salivary A. actinomycetemcomitans IgG levels. The multivariate regression analysis showed that PT (p = 0.033), hs-CRP (p = 0.014) and BMI (p = 0.017) were significant negative predictors of serum A. actinomycetemcomitans IgG while hs-CRP (p < 0.001) and BMI (P = 0.025) were significant negative predictors of salivary A. actinomycetemcomitans IgG.

CONCLUSIONS

PT patients presented a significantly higher serum and salivary A. actinomycetemcomitans IgA and IgG compared to HC. There was a significant increase in serum A. actinomycetemcomitans IgG when patients presented a progressive extent of PT. Moreover, PT and hs-CRP were significant negative predictors of increased salivary and serum A. actinomycetemcomitans IgG levels.

TRIAL REGISTRATION

The study was retrospectively registered at clinicaltrials.gov ( NCT04417322 ).

Clinical and Microbiological Profiles of Aggressive and Chronic Periodontitis in Congolese Patients: A Cross-sectional Study

Background:

Chronic and aggressive periodontitis were the main forms of periodontitis according to the 1999 classification of periodontal diseases and conditions. Their profile in Congolese patients is still undescribed.

Aim:

The aim of this study was to compare the profile of chronic periodontitis (ChP) with that of aggressive periodontitis (AgP) in Congolese patients.

Materials and Methods:

Thirty-two patients with ChP and 20 with AgP who consulted the dental services at any of the four medical centers in Kinshasa, from April 2017 to April 2018, were enrolled in the cross-sectional study. All patients underwent a full mouth examination, including assessment of the probing pocket depth and clinical attachment level at six sites per tooth. Microbial samples were collected in the deepest pocket in the maxilla and the deepest pocket in the mandible. A deoxyribonucleic acid (DNA) analysis was performed using DNA strip technology. Fisher exact test, the chi-square test, the t test, and the Mann–Whitney test were used for the statistical analysis.

Results:

Patients with AgP were significantly younger than those with ChP (P < 0.001). There was no significant difference in the prevalence of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, or Prevotella intermedia between the AgP and ChP groups (P > 0.05). Aggregatibacter actinomycetemcomitans was detected in 10% of cases in the AgP group and in none of those in the ChP group (P = 0.143).

Conclusion:

This study shows that the clinical profiles of ChP and AgP are similar in Congolese patients. There were no microbiological differences between these two forms of periodontitis.

Association of TNF-α-308G/A, -238G/A, -863C/A, -1031T/C, -857C/T polymorphisms with periodontitis susceptibility: Evidence from a meta-analysis of 52 studies

The association between tumor necrosis factor-alpha (TNF-α-308G/A, -238G/A, -863C/A, -1031T/C, and -857C/T) polymorphism and either chronic (CP) or aggressive (AgP) periodontitis susceptibility was conflicting. This meta-analysis aimed to quantitatively estimate the association.A total of 52 studies involving 5519 patients and 7260 controls were identified through a search of multiple electronic databases. Odds ratios (ORs) and their 95% confidence intervals using allele, homozygous, heterozygous, dominant, and recessive genetic models were computed to assess the strength of the association.The TNF-α-308G/A polymorphism was significantly associated with decreased risks of CP (GG vs AA: OR = 0.353, P < .001; GG+GA vs AA: OR = 0.480, P < .001) and AgP (G vs A: OR = 0.651, P < .001; GG vs AA: OR = 0.306, P < .001; GG+GA vs AA: OR = 0.384, P < .001) in Asians. There were no associations between TNF-α-238G/A, -863C/A, -1031T/C, -857C/T polymorphism and susceptibility to AgP. No associations were also found between CP susceptibility and TNF-α-238G/A, -857C/T polymorphism.These findings supported that TNF-α-308G/A polymorphism might be the protective factors of CP and AgP in Asians, and TNF-α-238G/A, -863C/A, -1031T/C, -857C/T polymorphism is not linked to AgP susceptibility.

Interleukin Gene Variability and Periodontal Bacteria in Patients with Generalized Aggressive Form of Periodontitis

Host genetic predispositions to dysregulated immune response can influence the development of the aggressive form of periodontitis (AgP) through susceptibility to oral dysbiosis and subsequent host-microbe interaction. This case-control study aimed to perform a multilocus analysis of functional variants in selected interleukin (IL) genes in patients with the generalized form of AgP in a homogenous population. Twelve polymorphisms in IL-1 gene cluster, IL-6 and its receptor, IL-10, IL-17A, and IL-18 were determined in 91 AgP patients and 210 controls. Analysis of seven selected periodontal bacteria in subgingival sulci/pockets was performed with a commercial DNA-microarray kit in a subgroup of 76 individuals. The pilot in vitro study included stimulation of peripheral blood monocytes (PBMC) from 20 individuals with periodontal bacteria and measurement of IL-10 levels using the Luminex method. Only the unctional polymorphism IL-10 −1087 A/G (rs1800896) and specific IL-10 haplotypes were associated with the development of the disease (p < 0.05, P_corr > 0.05). Four bacterial species occurred more frequently in AgP than in controls (p < 0.01, P_corr < 0.05). Elevated IL-10 levels were found in AgP patients, carriers of IL-10 −1087GG genotype, and PBMCs stimulated by periodontal bacteria (p < 0.05, P_corr > 0.05). We therefore conclude that a combination of genetic predisposition to the altered expression of IL-10 and the presence of specific periodontal bacteria may contribute to Th1/Th2 balance disruption and AgP development.

Integration of genome-wide association study and expression quantitative trait loci data identifies AIM2 as a risk gene of periodontitis

AIM

To identify risk variants associated with gene expression in peripheral blood and to identify genes whose expression change may contribute to the susceptibility to periodontitis.

MATERIAL AND METHODS

We systematically integrated the genetic associations from a recent large-scale periodontitis GWAS and blood expression quantitative trait loci (eQTL) data using Sherlock, a Bayesian statistical framework. We then validated the potential causal genes in independent gene expression data sets. Gene co-expression analysis was used to explore the functional relationship for the identified causal genes.

RESULTS

Sherlock analysis identified 10 genes (rs7403881 for MT1L, rs12459542 for SIGLEC5, rs12459542 for SIGLEC14, rs6680386 for S100A12, rs10489524 for TRIM33, rs11962642 for HIST1H3E, rs2814770 for AIM2, rs7593959 for FASTKD2, rs10416904 for PKN1, and rs10508204 for WDR37) whose expression may influence periodontitis. Among these genes, AIM2 was consistent significantly upregulated in periodontium of periodontitis patients across four data sets. The cis-eQTL (rs2814770, ~16 kb upstream of AIM2) showed significant association with AIM2 (p = 6.63 × 10^-6 ) and suggestive association with periodontitis (p = 7.52 × 10^-4 ). We also validated the significant association between rs2814770 and AIM2 expression in independent expression data set. Pathway analysis revealed that genes co-expressed with AIM2 were significantly enriched in immune- and inflammation-related pathways.

CONCLUSION

Our findings implicate that AIM2 is a susceptibility gene, expression of which in gingiva may influence periodontitis risk. Further functional investigation of AIM2 may provide new insight for periodontitis pathogenesis.

Genomics of periodontal disease and tooth morbidity

In this review we critically summarize the evidence base and the progress to date regarding the genomic basis of periodontal disease and tooth morbidity (ie, dental caries and tooth loss), and discuss future applications and research directions in the context of precision oral health and care. Evidence for these oral/dental traits from genome-wide association studies first emerged less than a decade ago. Basic and translational research activities in this domain are now under way by multiple groups around the world. Key departure points in the oral health genomics discourse are: (a) some heritable variation exists for periodontal and dental diseases; (b) the environmental component (eg, social determinants of health and behavioral risk factors) has a major influence on the population distribution but probably interacts with factors of innate susceptibility at the person-level; (c) sizeable, multi-ethnic, well-characterized samples or cohorts with high-quality measures on oral health outcomes and genomics information are required to make decisive discoveries; (d) challenges remain in the measurement of oral health and disease, with current periodontitis and dental caries traits capturing only a part of the health-disease continuum, and are little or not informed by the underlying biology; (e) the substantial individual heterogeneity that exists in the clinical presentation and lifetime trajectory of oral disease can be identified and leveraged in a precision medicine framework or, if unappreciated, can hamper translational efforts. In this review we discuss how composite or biologically informed traits may offer improvements over clinically defined ones for the genomic interrogation of oral diseases. We demonstrate the utility of the results of genome-wide association studies for the development and testing of a genetic risk score for severe periodontitis. We conclude that exciting opportunities lie ahead for improvements in the oral health of individual patients and populations via advances in our understanding of the genomic basis of oral health and disease. The pace of new discoveries and their equitable translation to practice will largely depend on investments in the education and training of the oral health care workforce, basic and population research, and sustained collaborative efforts..

Unique etiologic, demographic, and pathologic characteristics of localized aggressive periodontitis support classification as a distinct subcategory of periodontitis

BACKGROUND

Localized aggressive periodontitis (LAgP) occurs in 2% of African-American adolescents but only 0.15% of white adolescents. First molars and incisors are affected by rapid onset and progression.

METHODS

This nonsystematic critical review evaluated published data for LAgP and chronic periodontitis (CP), focusing on potential differences in epidemiology, microbiology, immunology, genetics, and response to therapy.

RESULTS

LAgP differs from CP by localization to incisors and first molars, early onset and rapid progression in adolescents and young adults, and a 10-fold higher prevalence in populations of African or Middle Eastern origin, often with strong familial aggregation. The bacterium Aggregatibacter actinomycetemcomitans and hyperresponsive neutrophils are frequently observed. Antibiotic and nonsurgical therapies are highly effective.

CONCLUSIONS

LAgP differs in many ways from the far more common CP that affects older adults. The substantial evidence of dissimilarities summarized in this review strongly supports the classification of LAgP as a distinct form of periodontitis.

PRACTICAL IMPLICATIONS

Classifying LAgP as a distinct subcategory of periodontitis will encourage future research and does not conflict with the newly proposed "staging and grading" system. The silent onset and rapid progression of LAgP make early diagnosis and frequent follow-up with patients essential for effective treatment.

Correlation study on mtDNA polymorphisms as potential risk factors in aggressive periodontitis by NGS

OBJECTIVES

Using next-generation sequencing (NGS) to determine whether aggressive periodontitis is associated with specific mitochondrial polymorphisms.

MATERIALS AND METHODS

A total of 165 unrelated Han Chinese were enrolled in the study. We analyzed the mitochondrial DNA (mtDNA) in 97 patients with aggressive periodontitis and 68 healthy controls by NGS. The mitochondrial DNA was L-PCR-amplified and subsequently sequenced by an Illumina Genome Analyzer (NGS). Chi-square tests were used to assess the differences between the two groups. In cases of significant difference, multivariate logistic regression models were further used to analyze the association between mtDNA polymorphisms and aggressive periodontitis.

RESULTS

Significant association was observed between aggressive periodontitis and eight mitochondrial polymorphisms: "8860G-10400C" (OR = 2.828, p = .002), "8701A" (OR = 2.308, p = .005), "12705C-10398A" (OR = 2.683, p = .002), "9540C" (OR = 3.838, p = .001) and "10873T-15043G" (OR = 4.375, p = .001).

CONCLUSIONS

The pathogenesis of aggressive periodontitis is complicated, and its heredity is not well characterized. Our study was the first to use next-generation sequencing and found that 8860G-10400C, 8701A, 12705C-10398A, 9540C, and 10873T-15043G are associated with aggressive periodontitis in the Han Chinese population.

Periodontal Regeneration with Enamel Matrix Derivative in the Management of Generalized Aggressive Periodontitis: A Case Report with 11-Year Follow-up and Literature Review

Objectives:

Aggressive periodontitis (AgP) represents an uncommon but rapidly advanced inflammatory process, which involves the destruction of periodontal tissues. This study aimed to report a case of generalized AgP (GAgP), where the treatment approach consists of the utilization of the full-mouth disinfection protocol (FMDP) in conjunction with flap curettage and regenerative appliance of enamel matrix derivatives (EMDs). The associated literature was also reviewed.

Materials and Methods:

A 19-year-old female patient was diagnosed with GAgP. The treatment was initiated with FMDP and administration of antibiotics. Afterward, open flap debridement was performed, and EMD was selected as the regenerative material for the reconstruction of the periodontal defects. Over an 11-year period and during all the phases of the treatment, the outcomes were regularly evaluated with clinical measurements and radiographic controls.

Results:

The 11-year results demonstrated no recurrence of disease, and the patient's periodontal health exhibited evident improvement. Overall, the pocket depths presented satisfactory reduction while the clinical attachment loss (CAL) was improved. Both our limited experience and available literature data revealed that the use of EMD in AgP treatment contributes to bone fill of the intrabony defects as well as regeneration of the destructed periodontal apparatus.

Conclusions:

Although the outcomes of this treatment approach have not been widely evaluated, it seems that the use of EMD may be an effective means of periodontal regeneration in patients with GAgP. Additional prospective studies with adequate number of GAgP patients are essential to thoroughly assess the effectiveness of this approach.