DNA methylation status of the IL8 gene promoter in oral cells of smokers and non-smokers with chronic periodontitis

TNF-alpha gene promoter's hypomethylation mediates a pro-inflammatory phenotype in peripheral blood monocytes from apical periodontitis individuals

AIM

Epigenetic regulation of the key inflammatory genes plays a crucial role in controlling monocyte/macrophage-mediated local and systemic responses to bacterial challenges. However, it has not been addressed in apical periodontitis (AP). We aimed to explore the methylation pattern of the TNF-α gene promoter and its association with the inflammatory phenotype of peripheral blood monocytes from individuals with AP and controls.

METHODS

A cross-sectional study was conducted, including otherwise healthy individuals with AP (n = 25) and controls (n = 29). Monocytes were isolated from the volunteer's blood samples using a Ficoll gradient followed by negative immunoselection. RNA and DNA were extracted. The DNA methylation profiles of the TNF-α gene promoter region were analyzed using bisulfite sequencing PCR. The mRNA expression levels of DNA methyltransferases 3a (DNMT3a) and Ten Eleven Translocation enzymes 1(TET1) were assessed by qPCR. A fraction of primary monocytes was also cultured for 24 h, and the supernatant was collected to measure cytokine levels through a Luminex assay. Generalized structural equation models (GSEM) evaluated the association between AP, DNA methylation, and TNF-α protein expression controlled for potential covariates. Models included the effect of the methylation of TNF-α gene promoter as a mediator of the association between AP and TNF-α protein expression levels.

RESULTS

Monocytes from AP individuals exhibited a heightened secretion of TNF-α and IL-1β and hypomethylation of the TNF gene promoter (p < .05). AP diagnosis was associated with the TNF-α gene promoter´s hypomethylated profile and enhanced pro-inflammatory cytokine levels, while lower methylation of the gene promoter region and -163 CpG single site mediated TNF-α overexpression (p < .05).

CONCLUSIONS

DNA hypomethylation at the TNF-α gene mediates a proinflammatory phenotype in monocytes from AP patients, supporting a role in the systemic response.

Novel DNA methylation changes in mouse lungs associated with chronic smoking

Smoking is a potent cause of asthma exacerbations, chronic obstructive pulmonary disease (COPD) and many other health defects, and changes in DNA methylation (DNAm) have been identified as a potential link between smoking and these health outcomes. However, most studies of smoking and DNAm have been done using blood and other easily accessible tissues in humans, while evidence from more directly affected tissues such as the lungs is lacking. Here, we identified DNAm patterns in the lungs that are altered by smoking. We used an established mouse model to measure the effects of chronic smoke exposure first on lung phenotype immediately after smoking and then after a period of smoking cessation. Next, we determined whether our mouse model recapitulates previous DNAm patterns observed in smoking humans, specifically measuring DNAm at a candidate gene responsive to cigarette smoke, Cyp1a1. Finally, we carried out epigenome-wide DNAm analyses using the newly released Illumina mouse methylation microarrays. Our results recapitulate some of the phenotypes and DNAm patterns observed in human studies but reveal 32 differentially methylated genes specific to the lungs which have not been previously associated with smoking. The affected genes are associated with nicotine dependency, tumorigenesis and metastasis, immune cell dysfunction, lung function decline, and COPD. This research emphasizes the need to study CS-mediated DNAm signatures in directly affected tissues like the lungs, to fully understand mechanisms underlying CS-mediated health outcomes.

Can social adversity alter the epigenome, trigger oral disease, and affect future generations?

The nature versus nurture debate has intrigued scientific circles for decades. Although extensive research has established a clear relationship between genetics and disease development, recent evidence has highlighted the insufficiency of attributing adverse health outcomes to genetic factors alone. In fact, it has been suggested that environmental influences, such as socioeconomic position (SEP), may play a much larger role in the development of disease than previously thought, with extensive research suggesting that low SEP is associated with adverse health conditions. In relation to oral health, a higher prevalence of caries (tooth decay) exists among those of low SEP. Although little is known about the biological mechanisms underlying this relationship, epigenetic modifications resulting from environmental influences have been suggested to play an important role. This review explores the intersection of health inequalities and epigenetics, the role of early-life social adversity and its long-term epigenetic impacts, and how those living within the lower hierarchies of the socioeconomic pyramid are indeed at higher risk of developing diseases, particularly in relation to oral health. A deeper understanding of these mechanisms could lead to the development of targeted interventions for individuals of low SEP to improve oral health or identify those who are at higher risk of developing oral disease.

DNA methylation and its potential roles in common oral diseases

Oral diseases are among the most common diseases worldwide and are associated with systemic illnesses, and the rising occurrence of oral diseases significantly impacts the quality of life for many individuals. It is crucial to detect and treat these conditions early to prevent them from advancing. DNA methylation is a fundamental epigenetic process that contributes to a variety of diseases including various oral diseases. Taking advantage of its reversibility, DNA methylation becomes a viable therapeutic target by regulating various cellular processes. Understanding the potential role of this DNA alteration in oral diseases can provide significant advances and more opportunities for diagnosis and therapy. This article will review the biology of DNA methylation, and then mainly discuss the key findings on DNA methylation in oral cancer, periodontitis, endodontic disease, oral mucosal disease, and clefts of the lip and/or palate in the background of studies on global DNA methylation and gene-specific DNA methylation.

Therapeutic and Metagenomic Potential of the Biomolecular Therapies against Periodontitis and the Oral Microbiome: Current Evidence and Future Perspectives

The principles of periodontal therapy are based on the control of microbial pathogens and host factors that contribute to biofilm dysbiosis, with the aim of modulating the progression of periodontitis and periodontal tissue destruction. It is currently known how differently each individual responds to periodontal treatment, depending on both the bacterial subtypes that make up the dysbiotic biofilm and interindividual variations in the host inflammatory response. This has allowed the current variety of approaches for the management of periodontitis to be updated by defining the goals of target strategies, which consist of reducing the periodontopathogenic microbial flora and/or modulating the host-mediated response. Therefore, this review aims to update the current variety of approaches for the management of periodontitis based on recent target therapies. Recently, encouraging results have been obtained from several studies exploring the effects of some targeted therapies in the medium- and long-term. Among the most promising target therapies analyzed and explored in this review include: cell-based periodontal regeneration, mediators against bone resorption, emdogain (EMD), platelet-rich plasma, and growth factors. The reviewed evidence supports the hypothesis that the therapeutic combination of epigenetic modifications of periodontal tissues, interacting with the dysbiotic biofilm, is a key step in significantly reducing the development and progression of disease in periodontal patients and improving the therapeutic response of periodontal patients. However, although studies indicate promising results, these need to be further expanded and studied to truly realize the benefits that targeted therapies could bring in the treatment of periodontitis.

Biomarkers of Periodontitis and Its Differential DNA Methylation and Gene Expression in Immune Cells: A Systematic Review

The characteristic epigenetic profile of periodontitis found in peripheral leukocytes denotes its impact on systemic immunity. In fact, this profile not only stands for periodontitis as a low-grade inflammatory disease with systemic effects but also as an important source of potentially valuable clinical biomarkers of its systemic effects and susceptibility to other inflammatory conditions. Thus, we aimed to identify relevant genes tested as epigenetic systemic biomarkers in patients with periodontitis, based on the DNA methylation patterns and RNA expression profiles in peripheral immune cells. A detailed protocol was designed following the Preferred Reporting Items for Systematic Review and Meta-analysis -PRISMA guideline. Only cross-sectional and case-control studies that reported potential systemic biomarkers of periodontitis in peripheral immune cell types were included. DNA methylation was analyzed in leukocytes, and gene expression was in polymorphonuclear and mononuclear cells. Hypermethylation was found in TLR regulators genes: MAP3K7, MYD88, IL6R, RIPK2, FADD, IRAK1BP1, and PPARA in early stages of periodontitis, while advanced stages presented hypomethylation of these genes. TGFB1I1, VNN1, HLADRB4, and CXCL8 genes were differentially expressed in lymphocytes and monocytes of subjects with poorly controlled diabetes mellitus, dyslipidemia, and periodontitis in comparison with controls. The DAB2 gene was differentially overexpressed in periodontitis and dyslipidemia. Peripheral blood neutrophils in periodontitis showed differential expression in 163 genes. Periodontitis showed an increase in ceruloplasmin gene expression in polymorphonuclears in comparison with controls. Several genes highlight the role of the epigenetics of peripheral inflammatory cells in periodontitis that could be explored in blood as a source of biomarkers for routine testing.

Association between Maternal Periodontitis and Development of Systematic Diseases in Offspring

Periodontal disease (PD) is one of the most common oral conditions affecting both youths and adults. There are some research works suggesting a high incidence of PD in pregnant women. As an inflammatory disease of bacterial origin, PD may result in the activation of the pathways affecting the course and the pregnancy outcome. The authors, based on the literature review, try to answer the PICO question: Does maternal periodontitis (exposure) influence the incidence of complications rates in pregnancy and the development of systemic diseases in childhood and adult offspring (outcome) in the humans of any race (population) compared to the offspring of mothers with healthy periodontium (comparison)? The authors try to describe the molecular pathways and mechanisms of these interdependencies. There is some evidence that maternal periodontitis may affect the pregnancy course and outcome, resulting in preeclampsia, preterm delivery, vulvovaginitis and low birth weight. It can be suggested that maternal periodontitis may affect offspring epigenome and result in some health consequences in their adult life.

Global DNA Methylation in Dental Implant Failure Due to Peri-Implantitis: An Exploratory Clinical Pilot Study

Background: Peri-implantitis (PIT) is highly prevalent in patients with dental implants and is a challenging condition to treat due to the limited outcomes reported for non-surgical and surgical therapies. Therefore, epigenetic therapeutics might be of key importance to treat PIT. However, developing epigenetic therapeutics is based on understanding the relationship between epigenetics and disease. To date, there is still scarce knowledge about the relationship between epigenetic modifications and PIT, which warrants further investigations. Aim: The purpose of this study was to evaluate the level of global DNA methylation associated with implant failure (IF) due to PIT compared to periodontally healthy (PH) patients. Material and Methods: A total of 20 participants were initially enrolled in this pilot, exploratory, single-blinded, cross-sectional clinical human study in two groups: 10 in the PH group and 10 in the IF group. In the participants who have completed the study, gingival tissue and bone samples were harvested from each participant and were used to perform global DNA methylation analysis. The percentage of global DNA methylation (5-mC%) was compared (1) between groups (PH and IF); (2) between the subgroups of gingival tissue and bone separately; (3) in the whole sample, comparing gingival tissue and bone; (4) within groups, comparing gingival tissue and bone. Demographic, periodontal, and peri-implant measurements as well as periodontal staging, were also recorded. All statistical comparisons were made at the 0.05 significance level. Results: Out of the initially enrolled 20 patients, only 19 completed the study and, thus, were included in the final analysis; 10 patients in the PH group and 9 patients in the IF group, contributing to a total of 38 samples. One patient from the IF group was excluded from the study due to systemic disease. The mean implant survival time was 10.8 years (2.17–15.25 years). Intergroup comparison, stratified by group, indicated a similar 5-mC% between the PH and IF groups in both gingival tissue and bone (p = 0.599), only in bone (p = 0.414), and only in gingival tissue (p = 0.744). Intragroup comparison, stratified by the type of sample, indicated a significantly higher 5-mC% in gingival tissue samples compared to bone in both the PH and IF groups (p = 0.001), in the PH group (p = 0.019), and in the IF group (p = 0.009). Conclusions: Within the limitations of this study, higher global DNA methylation levels were found in gingival tissue samples compared to bone, regardless of the study groups. However, similar global DNA methylation levels were observed overall between the IF and PH groups. Yet, differences in the global DNA methylation levels between gingival tissues and bone, regardless of the study group, could reflect a different epigenetic response between various tissues within the same microenvironment. Further studies are necessary to elucidate the present findings and to evaluate the role of epigenetic modifications in IF due to PIT.

Comprehensive Analysis of the Mechanism of Periodontitis-Related mRNA Expression Combined with Upstream Methylation and ceRNA Regulation

Background: Periodontitis is a multifactorial disease mainly caused by the formation of plaque biofilm, which can lead to the gradual destruction of tooth-supporting tissues. Current research on the genetics and epigenetics of periodontitis remains relatively limited, and the molecular mechanisms remain largely unknown. Objective: Our aims were to construct competitive endogenous RNA (ceRNA) network and determine DNA methylation patterns of target genes to help elucidate the pathogenesis of periodontitis. Methods: We analyzed the expression profiles of the GSE16134, GSE54710, GSE10334, and GSE59932 datasets from the Gene Expression Omnibus database through the weighted gene coexpression network analysis system and screened mRNAs that are regulated by the level of methylation and are associated with the occurrence of periodontitis. Next, a lncRNA-miRNA-mRNA ceRNA network was constructed using databases including miRanda and TargetScan. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted for genes in the clinically significant modules. Finally, a protein-protein interaction network was built. Results: We finally identified four mRNAs, four miRNAs, and six lncRNAs as shared differentially expressed genes related to the periodontitis inflammation pathway. IL-6, IFNA17, CXCL12, and TNFRSF13C were identified as key genes whose expression was significantly enriched in the nuclear factor κB and TLR4 pathways. Moreover, the expression of 28 genes were downregulated by hypermethylation and 70 genes were upregulated by hypomethylation. Conclusions: The constructed ceRNA network can improve our understanding of the pathogenesis of periodontitis. Candidate mRNAs from the ceRNA network could serve as new therapeutic targets and prognostic biomarkers in periodontitis.

Loss of Neutrophil Homing to the Periodontal Tissues Modulates the Composition and Disease Potential of the Oral Microbiota

Periodontal disease is considered to arise from an imbalance in the interplay between the host and its commensal microbiota, characterized by inflammation, destructive periodontal bone loss, and a dysbiotic oral microbial community. The neutrophil is a key component of defense of the periodontium: defects in their number or efficacy of function predisposes individuals to development of periodontal disease. Paradoxically, neutrophil activity, as part of a deregulated inflammatory response, is considered an important element in the destructive disease process. In this investigation, we examined the role the neutrophil plays in the regulation of the oral microbiota by analysis of the microbiome composition in mice lacking the CXCR2 neutrophil receptor required for recruitment to the periodontal tissues. A breeding protocol was employed that ensured that only the oral microbiota of wild-type (CXCR2^+/+) mice was transferred to subsequent generations of wild-type, heterozygote, and homozygote littermates. In the absence of neutrophils, the microbiome undergoes a significant shift in total load and composition compared to when normal levels of neutrophil recruitment into the gingival tissues occur, and this is accompanied by a significant increase in periodontal bone pathology. However, transfer of the oral microbiome of CXCR2^-/- mice into germfree CXCR2^+/+ mice led to restoration of the microbiome to the wild-type CXCR2^+/+ composition and the absence of pathology. These data demonstrate that the composition of the oral microbiome is inherently flexible and is governed to a significant extent by the genetics and resultant phenotype of the host organism.

New tendencies in non-surgical periodontal therapy

The aim of this review was to update the evidence of new approaches to non-surgical therapy (NSPT) in the treatment of periodontitis. Preclinical and clinical studies addressing the benefits of adjunctive antimicrobial photodynamic therapy, probiotics, prebiotics/synbiotics, statins, pro-resolving mediators, omega-6 and -3, ozone, and epigenetic therapy were scrutinized and discussed. Currently, the outcomes of these nine new approaches, when compared with subgingival debridement alone, did not demonstrate a significant added clinical benefit. However, some of these new alternative interventions may have the potential to improve the outcomes of NSPT alone. Future evidence based on randomized controlled clinical trials would help clinicians and patients in the selection of different adjunctive therapies.

Paradigm shift in the pathogenesis and treatment of oral cancer and other cancers focused on the oralome and antimicrobial-based therapeutics

The oral microbiome is a community of microorganisms, comprised of bacteria, fungi, viruses, archaea, and protozoa, that form a complex ecosystem within the oral cavity. Although minor perturbations in the environment are frequent and compensable, major shifts in the oral microbiome can promote an unbalanced state, known as dysbiosis. Dysbiosis can promote oral diseases, including periodontitis. In addition, oral dysbiosis has been associated with other systemic diseases, including cancer. The objective of this review is to evaluate the epidemiologic evidence linking periodontitis to oral, gastrointestinal, lung, breast, prostate, and uterine cancers, as well as describe new evidence and insights into the role of oral dysbiosis in the etiology and pathogenesis of the cancer types discussed. Finally, we discuss how antimicrobials, antimicrobial peptides, and probiotics may be promising tools to prevent and treat these cancers, targeting both the microbes and associated carcinogenesis processes. These findings represent a novel paradigm in the pathogenesis and treatment of cancer focused on the oral microbiome and antimicrobial‐based therapies.

Emerging Role of Epigenetics in Explaining Relationship of Periodontitis and Cardiovascular Diseases

Cardiovascular diseases such as ischemic heart diseases or stroke are among the leading cause of deaths globally, and evidence suggests that these diseases are modulated by a multifactorial and complex interplay of genetic, environmental, and lifestyle factors. Genetic predisposition and chronic exposure to modifiable risk factors have been explored to be involved in the pathophysiology of CVD. Environmental factors contribute to an individual's propensity to develop major cardiovascular risk factors through epigenetic modifications of DNA and histones via miRNA regulation of protein translation that are types of epigenetic mechanisms and participate in disease development. Periodontal disease (PD) is one of the most common oral diseases in humans that is characterized by low-grade inflammation and has been shown to increase the risk of CVDs. Risk factors involved in PD and CVD are determined both genetically and behaviorally. Periodontal diseases such as chronic inflammation promote DNA methylation. Epigenetic modifications involved in the initiation and progression of atherosclerosis play an essential role in plaque development and vulnerability. Epigenetics has opened a new world to understand and manage human diseases, including CVDs and periodontal diseases. Genetic medicine has started a new era of epigenetics to overcome human diseases with various new methodology. Epigenetic profiling may aid in better diagnosis and stratification of patients showing potential predisposed states for disease. A better understanding of the exact regulatory mechanisms of epigenetic pathways driving inflammation is slowly emerging and will aid in developing novel tools for the treatment of disease.

Current advances of epigenetics in periodontology from ENCODE project: a review and future perspectives

BACKGROUND

The Encyclopedia of DNA Elements (ENCODE) project has advanced our knowledge of the functional elements in the genome and epigenome. The aim of this article was to provide the comprehension about current research trends from ENCODE project and establish the link between epigenetics and periodontal diseases based on epigenome studies and seek the future direction.

MAIN BODY

Global epigenome research projects have emphasized the importance of epigenetic research for understanding human health and disease, and current international consortia show an improved interest in the importance of oral health with systemic health. The epigenetic studies in dental field have been mainly conducted in periodontology and have focused on DNA methylation analysis. Advances in sequencing technology have broadened the target for epigenetic studies from specific genes to genome-wide analyses.

CONCLUSIONS

In line with global research trends, further extended and advanced epigenetic studies would provide crucial information for the realization of comprehensive dental medicine and expand the scope of ongoing large-scale research projects.

Decitabine Promotes Modulation in Phenotype and Function of Monocytes and Macrophages That Drive Immune Response Regulation

Decitabine is an approved hypomethylating agent used for treating hematological malignancies. Although decitabine targets altered cells, epidrugs can trigger immunomodulatory effects, reinforcing the hypothesis of immunoregulation in treated patients. We therefore aimed to evaluate the impact of decitabine treatment on the phenotype and functions of monocytes and macrophages, which are pivotal cells of the innate immunity system. In vitro decitabine administration increased bacterial phagocytosis and IL-8 release, but impaired microbicidal activity of monocytes. In addition, during monocyte-to-macrophage differentiation, treatment promoted the M2-like profile, with increased expression of CD206 and ALOX15. Macrophages also demonstrated reduced infection control when exposed to Mycobacterium tuberculosis in vitro. However, cytokine production remained unchanged, indicating an atypical M2 macrophage. Furthermore, when macrophages were cocultured with lymphocytes, decitabine induced a reduction in the release of inflammatory cytokines such as IL-1β, TNF-α, and IFN-γ, maintaining IL-10 production, suggesting that decitabine could potentialize M2 polarization and might be considered as a therapeutic against the exacerbated immune response.

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.

Biosensor and Lab-on-a-chip Biomarker-identifying Technologies for Oral and Periodontal Diseases

Periodontitis is a complex multifactorial disease that can lead to destruction of tooth supporting tissues and subsequent tooth loss. The most recent global burden of disease studies highlight that severe periodontitis is one of the most prevalent chronic inflammatory conditions affecting humans. Periodontitis risk is attributed to genetics, host-microbiome and environmental factors. Empirical diagnostic and prognostic systems have yet to be validated in the field of periodontics. Early diagnosis and intervention prevents periodontitis progression in most patients. Increased susceptibility and suboptimal control of modifiable risk factors can result in poor response to therapy, and relapse. The chronic immune-inflammatory response to microbial biofilms at the tooth or dental implant surface is associated with systemic conditions such as cardiovascular disease, diabetes or gastrointestinal diseases. Oral fluid-based biomarkers have demonstrated easy accessibility and potential as diagnostics for oral and systemic diseases, including the identification of SARS-CoV-2 in saliva. Advances in biotechnology have led to innovations in lab-on-a-chip and biosensors to interface with oral-based biomarker assessment. This review highlights new developments in oral biomarker discovery and their validation for clinical application to advance precision oral medicine through improved diagnosis, prognosis and patient stratification. Their potential to improve clinical outcomes of periodontitis and associated chronic conditions will benefit the dental and overall public health.

DNA methylation alterations and their potential influence on macrophage in periodontitis

OBJECTIVES

To explore how various methylation mechanisms function and affect macrophages in periodontitis, with an aim of getting a comprehensive understanding of pathogenesis of the disease.

SUBJECT

Alterations in DNA methylation are associated with different periodontitis susceptible factors and disrupt immunity homeostasis. The host's immune response to stimulus plays a vital role in the progression of periodontitis. Macrophages are key immune cells of immune system. They act as critical regulators in maintaining issue homeostasis with their nature of high plasticity. The altered methylation status of genes may cause abnormal expression of proteins in the progress of periodontitis, thus, exert potential influence on macrophages.

RESULTS

Certain genes are selectively activated or silenced due to the changes in the methylation status, which causes the alteration of the expression level of cytokines/chemokines, signal molecules, extracellular matrix molecules, leads to the change in local microenvironment, affects activation states of immune cells including macrophages, thus influences the host immune response during periodontitis.. This results in differential susceptibility and therapeutic outcome.

CONCLUSION

DNA methylation alteration may cause aberrant expression level of genes associated with periodontal diseases, thus results in deregulation of macrophages, which supports the prospect of using DNA methylation-related parameter as a new biomarker for the diagnosis and treatment of periodontitis.

The Role of DNA Methylation and Histone Modification in Periodontal Disease: A Systematic Review

Despite a number of reports in the literature on the role of epigenetic mechanisms in periodontal disease, a thorough assessment of the published studies is warranted to better comprehend the evidence on the relationship between epigenetic changes and periodontal disease and its treatment. Therefore, the aim of this systematic review is to identify and synthesize the evidence for an association between DNA methylation/histone modification and periodontal disease and its treatment in human adults. A systematic search was independently conducted to identify articles meeting the inclusion criteria. DNA methylation and histone modifications associated with periodontal diseases, gene expression, epigenetic changes after periodontal therapy, and the association between epigenetics and clinical parameters were evaluated. Sixteen studies were identified. All included studies examined DNA modifications in relation to periodontitis, and none of the studies examined histone modifications. Substantial variation regarding the reporting of sample sizes and patient characteristics, statistical analyses, and methodology, was found. There was some evidence, albeit inconsistent, for an association between DNA methylation and periodontal disease. IL6, IL6R, IFNG, PTGS2, SOCS1, and TNF were identified as candidate genes that have been assessed for DNA methylation in periodontitis. While several included studies found associations between methylation levels and periodontal disease risk, there is insufficient evidence to support or refute an association between DNA methylation and periodontal disease/therapy in human adults. Further research must be conducted to identify reproducible epigenetic markers and determine the extent to which DNA methylation can be applied as a clinical biomarker.

Epigenetic reprogramming in periodontal disease: Dynamic crosstalk with potential impact in oncogenesis

Periodontitis is a chronic multifactorial inflammatory disease associated with microbial dysbiosis and characterized by progressive destruction of the periodontal tissues. Such chronic infectious inflammatory disease is recognized as a major public health problem worldwide with measurable impact in systemic health. It has become evident that the periodontal disease phenotypes are not only determined by the microbiome effect, but the extent of the tissue response is also driven by the host genome and epigenome patterns responding to various environmental exposures. More recently there is mounting evidence indicating that epigenetic reprogramming in response to combined intrinsic and environmental exposures, might be particularly relevant due its plasticity and potential application towards precision health. The complex epigenetic crosstalk is reflected in the prognosis and progress of periodontal diseases and may also lead to a favorable landscape for cancer development. This review discusses epigenomics modifications focusing on the role of DNA methylation and pathways linking microbial infection and inflammatory pathways, which are also associated with carcinogenesis. There is a more clear vision whereas 'omics' technologies applied to unveil relevant epigenetic factors could play a significant role in the treatment of periodontal disease in a personalized mode, evidencing that public health approach should coexist with precision individualized treatment.

miR-9-1 gene methylation and DNMT3B (rs2424913) polymorphism may contribute to periodontitis

BACKGROUND

Genetic and epigenetic changes have been associated with periodontitis in various genes; however, little is known about genes involved in epigenetic mechanisms and in oxidative stress.

OBJECTIVE

This study aims to investigate the association of polymorphisms C677T in MTHFR (rs1801133) and -149C→T in DNMT3B (rs2424913), as well as the methylation profiles of MTHFR, miR-9-1, miR-9-3, SOD1, and CAT with periodontitis. The association between polymorphisms and DNA methylation profiles was also analyzed.

METHODOLOGY

The population studied was composed of 100 nonsmokers of both sexes, divided into healthy and periodontitis groups. Genomic DNA was extracted from the epithelial buccal cells, which were collected through a mouthwash. Polymorphism analysis was performed through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while methylation-specific PCR (MSP) or combined bisulfite restriction analysis techniques were applied for methylation analysis.

RESULTS

For DNMT3B, the T allele and the TT genotype were detected more frequently in the periodontitis group, as well as the methylated profile on the miR-9-1 promoter region. There was also a tendency towards promoter region methylation on the CAT sequence of individuals with periodontal disease.

CONCLUSION

The polymorphism -149C→T in DNMT3B (rs2424913) and the methylated profile of the miR-9-1 promoter region are associated with periodontitis.

Interleukin 1β and Prostaglandin E2 affect expression of DNA methylating and demethylating enzymes in human gingival fibroblasts

Periodontitis is a common chronic inflammatory condition that results in increased levels of inflammatory cytokines and inflammatory mediators. In addition to oral disease and tooth loss, it also causes low-grade systemic inflammation that contributes to development of systemic conditions including cardiovascular disease, pre-term birth, diabetes and cancer. Chronic inflammation is associated with epigenetic change, and it has been suggested that such changes can alter cell phenotypes in ways that contribute to both ongoing inflammation and development of associated pathologies. Here we show that exposure of human gingival fibroblasts to IL-1β increases expression of maintenance methyltransferase DNMT1 but decreases expression of de novo methyltransferase DNMT3a and the demethylating enzyme TET1, while exposure to PGE2 decreases expression of all three enzymes. IL-1β and PGE2 both affect global levels of DNA methylation and hydroxymethylation, as well as methylation of some specific CpG in inflammation-associated genes. The effects of IL-1β are independent of its ability to induce production of PGE2, and the effects of PGE2 on DNMT3a expression are mediated by the EP4 receptor. The finding that exposure of fibroblasts to IL-1β and PGE2 can result in altered expression of DNA methylating/demethylating enzymes and in changing patterns of DNA methylation suggests a mechanism through which inflammatory mediators might contribute to the increased risk of carcinogenesis associated with inflammation.

Effect of Saliva Collection Methods on the Detection of Periodontium-Related Genetic and Epigenetic Biomarkers-A Pilot Study

Different collection methods may influence the ability to detect and quantify biomarker levels in saliva, particularly in the expression of DNA/RNA methylation regulators of several inflammations and tissue turnover markers. This pilot study recruited five participants and unstimulated saliva were collected by either spitting or drooling, and the relative preference for each method was evaluated using a visual analogue scale. Subsequently, total RNA, gDNA and proteins were isolated using the Trizol method. Thereafter, a systematic evaluation was carried out on the potential effects of different saliva collection methods on periodontium-associated genes, DNA/RNA epigenetic factors and periodontium-related DNA methylation levels. The quantity and quality of DNA and RNA were comparable from different collection methods. Periodontium-related genes, DNA/RNA methylation epigenetic factors and periodontium-associated DNA methylation could be detected in the saliva sample, with a similar expression for both methods. The methylation of tumour necrosis factor-alpha gene promoter from drooling method showed a significant positive correlation (TNF α, r = 0.9) with clinical parameter (bleeding on probing-BOP). In conclusion, the method of saliva collection has a minimal impact on detecting periodontium-related genetic and epigenetic regulators in saliva. The pilot data shows that TNF α methylation may be correlated with clinical parameters.

Epigenetics and periodontics: A systematic review

Background

Despite decades of research, our knowledge of several important aspects of periodontal pathogenesis remains incomplete. Epigenetics allows to perform dynamic analysis of different variations in gene expression, providing this great advantage to the static measurement provided by genetic markers. The aim of this systematic review is to analyze the possible relationships between different epigenetic mechanisms and periodontal diseases, and to assess their potential use as biomarkers of periodontitis.

Material and Methods

A systematic search was conducted in six databases using MeSH and non-MeSH terms. The review fulfilled PRISMA criteria (Preferred Reporting Items for Systematic reviews and Meta-analysis).

Results

36 studies met the inclusion criteria. Due to the heterogeneity of the articles, it was not possible to conduct quantitative analysis. Regarding qualitative synthesis, however, it was found that epigenetic mechanisms may be used as biological markers of periodontal disease, as their dynamism and molecular stability makes them a valuable diagnostic tool.

Conclusions

Epigenetic markers alter gene expression, producing either silencing or over-expression of molecular transcription that respond to the demands of the cellular surroundings. Gingival crevicular fluid collection is a non-invasive and simple procedure, which makes it an ideal diagnostic medium for detection of both oral and systemic issues. Although further research is needed, this seems to be a promising field of research in the years to come.

Key words:Epigenetics, periodontitis, DNA methylation, miRNA, epigenetic biomarker, periodontal diseases.

Characterization of Cytokines and Proliferation Marker Ki67 in Cleft Affected Lip Tissue

Background and objectives: Cleft lip palate takes the second place among all anomalies. The complex appearance of cytokines and proliferation markers has still not been clarified despite their possible crucial role in cleft tissue. Therefore, the aim of work was the detection of appearance of pro- and anti-inflammatory cytokines and proliferation marker Ki67, and their inter-correlations in cleft affected lip (CAL). Materials and Methods: The lip material was obtained from 16 children aged before primary dentition during plastic surgery. Control was obtained from 7 non-CAL oral tissue. Tissues were stained for IL-1, IL-4, IL-6, IL-8, IL-10 and Ki67 immunohistochemically. Non-parametric statistic, Mann-Whitney and Spearman's coefficient were used. Results: All cytokines positive cells were observed more into the epithelium. Statistically significant difference was seen between epithelial IL-1, IL-10, IL-8 and Ki67 positive cells and IL-10-, IL-4-containing connective tissue cells in comparison to the control. Strong positive correlation was detected in CAL epithelium between IL-10 and IL-8, IL-10 and IL-4, IL-10 and IL-1, IL-1 and IL-8, IL-1 and IL-4, IL-4 and IL-8, IL-8 and Ki67, IL-10 and Ki67, but moderate-in connective tissue between IL-1 and IL-10, IL-1 and IL-4. Conclusion: The CAL epithelium is the main source for the interleukins. Rich similar expression of IL-1 and IL-10 suggests the balance between pro-and anti-inflammatory tissue response on basis of dysregulated tissue homeostasis (increase of IL-8). The correlations between the different ILs -1, -4, -8, -10 in CAL epithelium seem to indicate the self-protection compensatory mechanism for intensification of local inflammatory-immune response without involvement of IL-6. The correlations between Ki67 and cytokines indicate the involvement of IL-8 and IL-10 in stimulation of cellular proliferation. IL-4 and IL-10 expression from CAL connective tissue simultaneously to IL-1, IL-4 and IL-10 inter-correlations there suggests the intensification of local immune response regulated probably by main pro-inflammatory cytokine-IL-1.

Hypomethylation of the IL8 promoter in nasal epithelial cells of patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

IL-8 is an important chemokine implicated in the pathogenesis of chronic rhinosinusitis (CRS), but little is known about epigenetic regulation of IL8 in the pathogenesis of CRS.

OBJECTIVE

We sought to investigate the relationship between the DNA methylation level in the IL8 proximal promoter and CRS in Han Chinese subjects.

METHODS

Patients with chronic rhinosinusitis with nasal polyps (CRSwNP; n = 187), patients with chronic rhinosinusitis without nasal polyps (CRSsNP; n = 89), and control subjects (n = 57) were enrolled in 2 independent cohorts. Purified human nasal epithelial cells from each participant were assessed for percentage DNA methylation of CpG sites in the IL8 proximal promoter by using bisulfite pyrosequencing and for functional aspects of methylation status by using in vitro assays.

RESULTS

DNA methylation of CpG sites 1, 2, and 3, respectively, in the IL8 proximal promoter was significantly decreased in human nasal epithelial cells of patients with CRSwNP compared with that in patients with CRSsNP (P < .001) and control subjects (P < .001). Percentage of DNA methylation of the CpG3 site was correlated negatively with both tissue eosinophilic cationic protein (P < .01) and myeloperoxidase (P < .05) levels. IL-1β (P < .001) and TNF-α (P < .01) significantly increased IL8 expression accompanied by a reduction in methylation at the CpG3 site (P < .001). Electrophoretic mobility shift assays demonstrated that methylation status of CpG3 changed the binding of octamer-binding transcription factor 1 and nuclear factor κB.

CONCLUSION

Decreased DNA methylation of particularly CpG sites in the IL8 proximal promoter might play a role in the pathogenesis of CRSwNP.

Exposure of low-dose fipronil enantioselectively induced anxiety-like behavior associated with DNA methylation changes in embryonic and larval zebrafish

Fipronil, a broad-spectrum chiral insecticide, has been documented to induce significant neurotoxicity to nontarget aquatic species; however, whether its neurotoxicity behaves enantioselectively and what molecular mechanisms correspond to the neurotoxicity remain unanswered. To date, few investigations have focused on the genomic mechanisms responsible for the enantioselective toxicity of chiral pesticides. The epigenetic modifications, especially DNA methylation, caused by the pesticides are also blind spot of the research works. Video tracking showed that R-fipronil exhibited more intense neurotoxicity, as well as the induction of more severe anxiety-like behavior, such as boosted swimming speed and dysregulated photoperiodic locomotion, to embryonic and larval zebrafish compared with S-fipronil. The MeDIP-Seq analysis, combined with Gene Ontology and KEGG, revealed that R-fipronil disrupted five signaling pathways (MAPK, Calcium signaling, Neuroactive ligand-receptor interaction, Purine metabolism, and Endocytosis) to a greater extent than S-fipronil through the hypermethylation of several important neuro-related genes, whereas no significant alterations of global DNA methylation were observed on the two enantiomers. To summarize, our data indicated that the fipronil-conducted enantioselective neurotoxicity likely applied its enantioselectivity by the dysregulation of DNA methylation. Our study also provided novel epigenetic insights into the study of enantioselective biological effects and the relevant underlying mechanisms of chiral insecticide.

Targeting epigenetic mechanisms in periodontal diseases

Epigenetic factors are heritable genome modifications that potentially impact gene transcription, contributing to disease states. Epigenetic marks play an important role in chronic inflammatory conditions, as observed in periodontal diseases, by allowing microbial persistence or by permitting microbial insult to play a role in the so-called 'hit-and-run' infectious mechanism, leading to lasting pathogen interference with the host genome. Epigenetics also affects the health sciences by providing a dynamic mechanistic framework to explain the way in which environmental and behavioral factors interact with the genome to alter disease risk. In this article we review current knowledge of epigenome regulation in light of the multifactorial nature of periodontal diseases. We discuss epigenetic tagging in identified genes, and consider the potential implications of epigenetic changes on host-microbiome dynamics in chronic inflammatory states and in response to environmental stressors. The most recent advances in genomic technologies have placed us in a position to analyze interaction effects (eg, between periodontal disease and type 2 diabetes mellitus), which can be investigated through epigenome-wide association analysis. Finally, because of the individualized traits of epigenetic biomarkers, pharmacoepigenomic perspectives are also considered as potentially novel therapeutic approaches for improving periodontal disease status.

Epigenetic findings in periodontitis in UK twins: a cross-sectional study

Background

Genetic and environmental risk factors contribute to periodontal disease, but the underlying susceptibility pathways are not fully understood. Epigenetic mechanisms are malleable regulators of gene function that can change in response to genetic and environmental stimuli, thereby providing a potential mechanism for mediating risk effects in periodontitis. The aim of this study is to identify epigenetic changes across tissues that are associated with periodontal disease.

Methods

Self-reported gingival bleeding and history of gum disease, or tooth mobility, were used as indicators of periodontal disease. DNA methylation profiles were generated using the Infinium HumanMethylation450 BeadChip in whole blood, buccal, and adipose tissue samples from predominantly older female twins (mean age 58) from the TwinsUK cohort. Epigenome-wide association scans (EWAS) of gingival bleeding and tooth mobility were conducted in whole blood in 528 and 492 twins, respectively. Subsequently, targeted candidate gene analysis at 28 genomic regions was carried out testing for phenotype-methylation associations in 41 (tooth mobility) and 43 (gingival bleeding) buccal, and 501 (tooth mobility) and 556 (gingival bleeding) adipose DNA samples.

Results

Epigenome-wide analyses in blood identified one CpG-site (cg21245277 in ZNF804A) associated with gingival bleeding (FDR = 0.03, nominal p value = 7.17e−8) and 58 sites associated with tooth mobility (FDR < 0.05) with the top signals in IQCE and XKR6. Epigenetic variation at 28 candidate regions (247 CpG-sites) for chronic periodontitis showed an enrichment for association with periodontal traits, and signals in eight genes (VDR, IL6ST, TMCO6, IL1RN, CD44, IL1B, WHAMM, and CXCL1) were significant in both traits. The methylation-phenotype association signals validated in buccal samples, and a subset (25%) also validated in adipose tissue.

Conclusions

Epigenome-wide analyses in adult female twins identified specific DNA methylation changes linked to self-reported periodontal disease. Future work will explore the environmental basis and functional impact of these results to infer potential for strategic personalized treatments and prevention of chronic periodontitis.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0614-4) contains supplementary material, which is available to authorized users.

DNA methylation profiles of immune response-related genes in apical periodontitis

AIM

To investigate the DNA methylation profiles of immune response-related genes in apical periodontitis (AP) lesions.

METHODOLOGY

The methylation profiles on the cytosine-phosphate-guanine (CpG) regions of 22 gene promoters involved in inflammation and autoimmunity were assessed in 60 human AP lesions and 24 healthy periodontal ligaments (controls) using a pathway-specific real-time polymerase chain reaction array (EpiTect® Methyl Signature PCR Array Human Inflammatory Response). Differentially methylated genes were subsequently assessed for their mRNA expression. Data analyses (One-way anova, Tukey's multiple comparisons tests and Mann-Whitney tests) were performed using GraphPad Prism 6 software. P values ≤ 0.05 were considered statistically significant.

RESULTS

Significant DNA hypermethylation was observed for CXCL3 and FADD gene promoters in AP lesions when compared to control tissues (P < 0.001) and among other genes (P < 0.05). In contrast, IL12B and IL4R were associated with significant hypomethylation in comparison to other genes (P < 0.05). IL12B, IL4R, CXCL3 and FADD had differential mRNA expression in AP lesions and controls (P < 0.001).

CONCLUSIONS

Differential methylation profiles of immune response-related genes, such as FADD, CXCL3, IL12B and IL4R, may have an influence on individual AP susceptibility and patient treatment outcomes, through their potential contributions to altered expression of disease-relevant genes. Methylation and/or genetic variations in additional genes may also contribute to the dynamics of AP development and should be considered in future studies.

Transcriptomics and methylomics in chronic periodontitis with tobacco use: a pilot study

Background

Accumulating evidence suggests that tobacco smoking affects the susceptibility to and severity of chronic periodontitis. Epigenetics may explain the role of smoking in the development and progress of periodontal disease. In this study, we performed transcriptomic and methylomic analyses of non-periodontitis and periodontitis-affected gingival tissues according to smoking status.

Methods

Human gingival tissues were obtained from 20 patients, including non-smokers with and without periodontitis (n = 5 per group) and smokers with and without periodontitis (n = 5 per group). Total RNA and genomic DNA were isolated, and their quality was validated according to strict standards. The Illumina NextSeq500 sequencing system was used to generate transcriptome and methylome datasets.

Results

Comprehensive analysis, including between-group correlation, differential gene expression, DNA methylation, gene set enrichment, and protein-protein interaction, indicated that smoking may change the transcription and methylation states of extracellular matrix (ECM) organization-related genes, which exacerbated the periodontal condition.

Conclusions

Our results suggest that smoking-related changes in DNA methylation patterns and subsequent alterations in the expression of genes coding for ECM components may be causally related to the increased susceptibility to periodontitis in smokers as they could influence ECM organization, which in turn may have an effect on disease characteristics.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-017-0381-z) contains supplementary material, which is available to authorized users.

Potential roles of DNA methylation in the initiation and establishment of replicative senescence revealed by array-based methylome and transcriptome analyses

Cellular senescence is classified into two groups: replicative and premature senescence. Gene expression and epigenetic changes are reported to differ between these two groups and cell types. Normal human diploid fibroblast TIG-3 cells have often been used in cellular senescence research; however, their epigenetic profiles are still not fully understood. To elucidate how cellular senescence is epigenetically regulated in TIG-3 cells, we analyzed the gene expression and DNA methylation profiles of three types of senescent cells, namely, replicatively senescent, ras-induced senescent (RIS), and non-permissive temperature-induced senescent SVts8 cells, using gene expression and DNA methylation microarrays. The expression of genes involved in the cell cycle and immune response was commonly either down- or up-regulated in the three types of senescent cells, respectively. The altered DNA methylation patterns were observed in replicatively senescent cells, but not in prematurely senescent cells. Interestingly, hypomethylated CpG sites detected on non-CpG island regions ("open sea") were enriched in immune response-related genes that had non-CpG island promoters. The integrated analysis of gene expression and methylation in replicatively senescent cells demonstrated that differentially expressed 867 genes, including cell cycle- and immune response-related genes, were associated with DNA methylation changes in CpG sites close to the transcription start sites (TSSs). Furthermore, several miRNAs regulated in part through DNA methylation were found to affect the expression of their targeted genes. Taken together, these results indicate that the epigenetic changes of DNA methylation regulate the expression of a certain portion of genes and partly contribute to the introduction and establishment of replicative senescence.

Association of CXCL12 gene promoter methylation with periodontitis in patients with diabetes mellitus type 2

OBJECTIVES

CXCL12 is widely expressed, constitutive chemokine involved in tissue repair and regeneration, while the extent of its expression is important in various chronic inflammatory conditions. Involvement of DNA methylation in CXCL12 gene suppression (CXCL12) has been shown in malignancy and some autoimmune diseases. The aim of this study was to investigate whether the alterations in DNA methylation of CXCL12 are also involved in progression of periodontitis in combination with diabetes, as these chronic inflammatory conditions are strongly interrelated.

DESIGN

Study included 72 subjects divided in three groups: healthy control (C, n=21), periodontitis (P, n=29) and diabetes/periodontitis group (D/P, n=22). DNA extracted from epithelial cells obtained by sterile cotton swabs from buccal mucosa was subjected to methylation specific polymerase chain reaction (MSP) to obtain DNA methylation pattern of CXCL12 promoter.

RESULTS

CXCL12 promoter was predominantly unmethylated in all groups. However, increase in the frequency of the methylated form and increase in percent of methylation of CXCL12 promoter in periodontitis and diabetes/periodontitis group compared to control group were found, although without statistical significance. However, statistically significant increase in Tm of MSP products in diabetes/periodontitis group was observed. Correlation analysis revealed statistically significant relationship between the extent of DNA methylation of the CXCL12 promoter and periodontal parameters, as well as between DNA methylation of CXCL12 and glycosylated hemoglobin.

CONCLUSION

Presented results suggest that chronic inflammation contributes to the change of CXCL12 DNA methylation in buccal cells and that DNA methylation profile of CXCL12 promoter plays important role in development and progression of periodontal disease.

Saturation of the biological response to orthodontic forces and its effect on the rate of tooth movement

OBJECTIVES

Investigate the expression and activity of inflammatory markers in response to different magnitudes of orthodontic forces and correlate this response with other molecular and cellular events during orthodontic tooth movement.

SETTING AND SAMPLE POPULATION

CTOR Laboratory; 245 Sprague Dawley male rats.

METHODS AND MATERIALS

Control, sham, and 5 different experimental groups received different magnitudes of force on the right maxillary first molar using a coil spring. In the sham group, the spring was not activated. Control group did not receive any appliance. At days 1, 3, 7, 14, and 28, the maxillae were collected for RNA and protein analysis, immunohistochemistry, and micro-CT.

RESULTS

There was a linear relation between the force and the level of cytokine expression at lower magnitudes of force. Higher magnitudes of force did not increase the expression of cytokines. Activity of CCL2, CCL5, IL-1, TNF-α, RANKL, and number of osteoclasts reached a saturation point in response to higher magnitudes of force, with unchanged rate of tooth movement.

CONCLUSION

After a certain magnitude of force, there is a saturation in the biological response, and higher forces do not increase inflammatory markers, osteoclasts, nor the amount of tooth movement. Therefore, higher forces to accelerate the rate of tooth movement are not justified.

Increased expression of interleukin-6 (IL-6) gene transcript in relation to IL-6 promoter hypomethylation in gingival tissue from patients with chronic periodontitis

OBJECTIVE

DNA methylation of the cytokine genes may play a role in the pathogenesis of periodontitis. The aim of this study is to evaluate whether the alteration of interleukin-6 (IL-6) gene promoter methylation in the gingival tissue (GT) and peripheral blood (PB) is unique to chronic periodontitis (CP).

DESIGN

DNA isolated from the GT and PB of 25 patients with (CP) and 20 healthy controls (H) was modified with sodium bisulfite and analyzed for IL-6 promoter methylation with direct sequencing. The levels of IL-6 mRNA and serum IL-6 protein were evaluated by a quantitative reverse transcription polymerase chain reaction and an enzyme-linked immunosorbent assay.

RESULTS

The CP group showed that the overall methylation rates of IL-6 promoter that contained 19 cytosine-guanine dinucleotide (CpG) motifs were significantly decreased in GT in comparison to PB (p<0.001), which was significantly negatively correlated with the probing depth (p=0.003). The GT and PB of the H group displayed similar overall methylation rates. No significant difference was observed in the methylation rates at each CpG in GT in comparison to the PB in both groups. The levels of IL-6 mRNA in the GT and PB and serum IL-6 of the two groups were comparable. The ratio of IL-6 mRNA in the GT relative to the PB was significantly higher in the CP group than in the H group (p=0.03).

CONCLUSION

The increased expression of IL-6 gene transcription may be related to IL-6 promoter hypomethylation in the GT from CP patients.

High-Frequency Acceleration: Therapeutic Tool to Preserve Bone following Tooth Extractions

A common problem in clinical dentistry is the significant and rapid bone loss that occurs after tooth extraction. Currently there is no solution for the long-term preservation of alveolar bone. Previously, we showed that high-frequency acceleration (HFA) has an osteogenic effect on healthy alveolar bone. However, it is not known if HFA can preserve alveolar bone after extraction without negatively affecting wound healing. The purpose of this study was to evaluate the effect of HFA on alveolar bone loss and the rate of bone formation after tooth extraction. Eighty-five adult Sprague-Dawley rats were divided into 3 groups: control, static (static load), and HFA. In all groups, the maxillary right third molar was extracted. The HFA group received HFA for 5 min/d, applied through the second molar. The static group received the same magnitude of static load. The control group did not receive any stimulation. Some animals received fluorescent dyes at 26 and 54 d. Samples were collected on days 0, 7, 14, 28, and 56 for fluorescence microscopy, micro-computed tomography, histology, RNA, and protein analyses. We found that HFA increased bone volume in the extraction site and surrounding alveolar bone by 44% when compared with static, while fully preserving alveolar bone height and width long-term. These effects were accompanied by increased expression of osteogenic markers and intramembranous bone formation and by decreased expression of osteoclastic markers and bone resorption activity, as well as decreased expression of many inflammatory markers. HFA is a noninvasive safe treatment that can be used to prevent alveolar bone loss and/or accelerate bone healing after tooth extraction.

The epigenetic paradigm in periodontitis pathogenesis

Epigenome refers to “epi” meaning outside the “genome.” Epigenetics is the field of study of the epigenome. Epigenetic modifications include changes in the promoter CpG Islands, modifications of histone protein structure, posttranslational repression by micro-RNA which contributes to the alteration of gene expression. Epigenetics provides an understanding of the role of gene-environment interactions on disease phenotype especially in complex multifactorial diseases. Periodontitis is a chronic inflammatory disorder that affects the supporting structures of the tooth. The role of the genome (in terms of genetic polymorphisms) in periodontitis pathogenesis has been examined in numerous studies, and chronic periodontitis has been established as a polygenic disorder. The potential role of epigenetic modifications in the various facets of pathogenesis of periodontitis is discussed in this paper based on the available literature.

Arsenic exposure causes epigenetic dysregulation of IL-8 expression leading to proneoplastic changes in kidney cells

Prolonged arsenic exposure has been shown to cause several detrimental effects in adults. However its effects following prenatal exposure are not well defined at the epigenetic level, particularly in terms of changes which may predispose an individual to adult malignancies. In this work, we have studied the effect of arsenic exposure on renal system using human embryonic kidney cells and prenatally exposed animals and identified Interleukin-8(IL-8) and its homologue (CINC-1) as mediators of arsenic induced renal toxicity. We further show that embryonic kidney cells are more responsive to arsenic leading to higher induction of IL-8 as compared to adult cells due to DNA methylation and histone acetylation (H3 acetylation) changes in the IL-8 promoter. Through bisulfite analysis of the IL-8 promoter, we have also identified an arsenic modulated CpG site at -168 bases upstream of transcription start site. This CpG is associated with C/EBP and CREB binding sites in the IL-8 promoter and its demethylation by arsenic coupled with increased H3 histone acetylation and CBP/P300 recruitment could lead to induction of IL-8. Our study shows how epigenetic modulation of IL-8 by arsenic could contribute to increased cell migratory and proliferative capabilities, cell cycle dysregulation and renal toxicity.

Epigenetics and its role in periodontal diseases: a state-of-the-art review

The immune response to oral bacteria and the subsequent activation of inflammatory signaling is not only dependent on genetic factors. The importance of so-called epigenetic mechanisms presents additional regulatory pathways of genes involved in maintaining chronic inflammation, including gingivitis and periodontitis. The term epigenetics relates to changes in gene expression that are not encoded in the DNA sequence itself and include chemical alterations of DNA and its associated proteins. These changes lead to remodeling of the chromatin and subsequent activation or inactivation of a gene. Epigenetic mechanisms have been found to contribute to disease, including cancer and autoimmune or inflammatory diseases. In this state-of-the art review, the authors provide the latest findings on the involvement of epigenetic modifications in the development of periodontal disease and present emerging therapeutic strategies aimed at epigenetic targets (epidrugs) associated with the disruption of tissue homeostasis and the development of periodontitis.

Comparative epigenetics: relevance to the regulation of production and health traits in cattle

With the development of genomic, transcriptomic and bioinformatic tools, recent advances in molecular technologies have significantly impacted bovine bioscience research and are revolutionising animal selection and breeding. Integration of epigenetic information represents yet another challenging molecular frontier. Epigenetics is the study of biochemical modifications to DNA and to histones, the proteins that provide stability to DNA. These epigenetic changes are induced by environmental stimuli; they alter gene expression and are potentially heritable. Epigenetics research holds the key to understanding how environmental factors contribute to phenotypic variation in traits of economic importance in cattle including development, nutrition, behaviour and health. In this review, we discuss the potential applications of epigenetics in bovine research, using breakthroughs in human and murine research to signpost the way.

11p15 DNA-methylation analysis in monozygotic twins with discordant intrauterine development due to severe twin-to-twin transfusion syndrome

BACKGROUND

Prenatal growth restriction and low birth weight have been linked to long-term alterations of health, presumably via adaptive modifications of the epigenome. Recent studies indicate a plasticity of the 11p15 epigenotype in response to environmental changes during early stages of human development.

STUDY DESIGN

We analyzed methylation levels at different 11p15 loci in 20 growth-discordant monozygotic twin pairs. Intrauterine development was discordant due to severe twin-to-twin transfusion syndrome (TTTS), which was treated by fetoscopic laser coagulation of communicating vessels before 25 weeks of gestation. Methylation levels at age 4 were determined in blood and buccal cell-derived DNA by the single nucleotide primer extension reaction ion pair reverse-phase high performance liquid chromatography (SNuPE IP RP HPLC) assay. Methylation at LINE-1 repeats was analyzed as an estimate of global methylation.

RESULTS

In general, variance of locus-specific methylation levels appeared to be higher in buccal cell- as compared to blood cell-derived DNA samples. Paired analyses within the twin pairs revealed significant differences at only one CpG site (IGF2 dmr0 SN3 (blood), +1.9% in donors; P = 0.013). When plotting the twin pair-discordance in birth weight against the degree of discordance in site-specific methylation at age 4, only a few CpGs were found to interact (one CpG site each at IGF2dmr0 in blood/saliva DNA, one CpG at LINE-1 repeats in saliva DNA), with 26 to 36% of the intra-twin pair divergence at these sites explained by prenatal growth discordance. However, across the entire cohort of 40 children, site-specific methylation did not correlate with SD-scores for weight or length at birth. Insulin-like growth factor-II serum concentrations showed significant within-twin pair correlations at birth (R = 0.57) and at age 4 (R = 0.79), but did not differ between donors and recipients. They also did not correlate with the analyzed 11p15 methylation parameters.

CONCLUSION

In a cohort of 20 growth-discordant monozygotic twin pairs, severe alteration in placental blood supply due to TTTS appears to leave only weak, if any, epigenetic marks at the analyzed CpG sites at 11p15.