Phenotype Harmonization in the GLIDE2 Oral Health Genomics Consortium

Population Proteomics: A Tool to Gain Insights Into the Inflamed Periodontium

Periodontitis, characterized by inflammatory loss of tooth-supporting tissues associated with biofilm, is among the most prevalent chronic diseases globally, affecting approximately 50% of the adult population to a moderate extent and cases of severe periodontitis surpassing the one billion mark. Proteomics analyses of blood, serum, and oral fluids have provided valuable insights into the complex processes occurring in the inflamed periodontium. However, until now, proteome analyses have been primarily limited to small groups of diseased versus healthy individuals. The emergence of population-scale analysis of proteomic data offers opportunities to uncover disease-associated pathways, identify potential drug targets, and discover biomarkers. In this review, we will explore the applications of proteomics in population-based studies and discuss the advancements it brings to our understanding of periodontal inflammation. Additionally, we highlight the challenges posed by currently available data and offer perspectives for future applications in periodontal research. This review aims to explain the ongoing efforts in leveraging proteomics for elucidating the complexities of periodontal diseases and paving the way for clinical strategies.

Periodontitis prevalence and acceleration of biological aging: Insights from NHANES 2009-2014 and Mendelian randomization study

AIM

This study aimed to investigate the association of periodontitis with biological aging and to assess potential causality using Mendelian randomization (MR).

METHODS

A cross-sectional study with 9558 participants from the National Health and Nutrition Examination Survey (2009-2014) was conducted. Age acceleration (BioAgeAccel and PhenoAgeAccel) was calculated from clinical biomarkers and their discrepancies with chronological age. Two-sample MR analysis was performed using data from a large-scale genome-wide association study and UK Biobank.

RESULTS

Periodontitis was associated with increased biological aging, with 0.57-year (95% CI: 0.28-0.86, p < .001) increases in BioAgeAccel and 0.41-year (95% CI: 0.04-0.78, p = .034) increases in PhenoAgeAccel. Subgroup analysis found significantly stronger associations in males for BioAgeAccele (PINTERACTION = .006), and pronounced associations in young adults (pinteraction = .023), individuals with normal body mass index (pinteraction = .015), and current smokers (pinteraction = .016) for PehonAgeAccel. MR analysis did not provide strong evidence for a causal effect of periodontitis on biological aging (BioAgeAccel: IVW β = 0.008, 95% CI: -0.018 to 0.034, p = .553 and PhenoAgeAccel: IVW β = 0.016, 95% CI: -0.042 to 0.074, p = .585).

CONCLUSION

This study identified the association of periodontitis and its severity with accelerated aging, suggesting periodontal health could be a possible method in personalized preventive and therapeutic strategies of biological aging.

The promise and challenges of genomics-informed periodontal disease diagnoses

Recent advances in human genomics and the advent of molecular medicine have catapulted our ability to characterize human and health and disease. Scientists and healthcare practitioners can now leverage information on genetic variation and gene expression at the tissue or even individual cell level, and an enormous potential exists to refine diagnostic categories, assess risk in unaffected individuals, and optimize disease management among those affected. This review investigates the progress made in the domains of molecular medicine and genomics as they relate to periodontology. The review summarizes the current evidence of association between genomics and periodontal diseases, including the current state of knowledge that approximately a third of the population variance of periodontitis may be attributable to genetic variation and the management of several monogenic forms of the disease can be augmented by knowledge of the underlying genetic cause. Finally, the paper discusses the potential utility of polygenic risk scores and genetic testing for periodontitis diagnosis now and in the future, in light of applications that currently exist in other areas of medicine and healthcare.

A Polygenic Score Predicts Caries Experience in Elderly Swedish Adults

Caries is a partially heritable disease, raising the possibility that a polygenic score (PS, a summary of an individual's genetic propensity for disease) might be a useful tool for risk assessment. To date, PS for some diseases have shown clinical utility, although no PS for caries has been evaluated. The objective of the study was to test whether a PS for caries is associated with disease experience or increment in a cohort of Swedish adults. A genome-wide PS for caries was trained using the results of a published genome-wide association meta-analysis and constructed in an independent cohort of 15,460 Swedish adults. Electronic dental records from the Swedish Quality Registry for Caries and Periodontitis (SKaPa) were used to compute the decayed, missing, and filled tooth surfaces (DMFS) index and the number of remaining teeth. The performance of the PS was evaluated by testing the association between the PS and DMFS at a single dental examination, as well as between the PS and the rate of change in DMFS. Participants in the highest and lowest deciles of PS had a mean DMFS of 63.5 and 46.3, respectively. A regression analysis confirmed this association where a 1 standard deviation increase in PS was associated with approximately 4-unit higher DMFS (P < 2 × 10-16). Participants with the highest decile of PS also had greater change in DMFS during follow-up. Results were robust to sensitivity analysis, which adjusted for age, age squared, sex, and the first 20 genetic principal components. Mediation analysis suggested that tooth loss was a strong mediating factor in the association between PS and DMFS but also supported a direct genetic effect on caries. In this cohort, there are clinically meaningful differences in DMFS between participants with high and low PS for caries. The results highlight the potential role of genomic data in improving caries risk assessment.

The role of acquired host immunity in periodontal diseases

The aim of this narrative review is to relate the contribution of European researchers to the complex topic of the host immune system in periodontal disease, focusing on acquired immunity. Other chapters in this volume will address the genetics and autoantibody responses and other forms of immunity to periodontal disease. While the contribution of European authors is the focus, global literature is included in this descriptive narrative for contextual clarity, albeit many with European co-authors. The topic is relatively intense and is thus broken down into sections outlined below, tackled as descriptive narratives to enhance understanding. Any attempt at a systematic or scoping review was quickly abandoned given the descriptive nature and marked variation of approach in almost all publications. Even the most uniform area of this acquired periodontal immunology literature, antibody responses to putative pathogens in periodontal diseases, falls short of common structures and common primary outcome variables one would need and expect in clinical studies, where randomized controlled clinical trials (RCTs) abound. Addressing 'the host's role' in immunity immediately requires a discussion of host susceptibility, which necessitates consideration of genetic studies (covered elsewhere in the volume and superficially covered here).

Periodontitis and Sjogren's syndrome: a bidirectional two-sample mendelian randomization study

OBJECTIVES

Observational studies indicated a controversial relationship between periodontitis (PD) and Sjogren's syndrome (SS). To overcome restrictions in conventional observational studies, we conducted a two-sample Mendelian randomization (MR) analysis to assess the potential bidirectional relationship between PD and SS.

METHODS

We utilized the largest available genome-wide association study (GWAS) of European ancestry on both PD (17,353 cases-28,210 controls) and SS (2495 cases-365,533 controls) for MR genetic instrument selection. The random-effect inverse-variance weighted (IVW) method complemented by Causal Analysis Using Summary Effect (CAUSE), weighted median, weighted mode, simple mode, MR-Egger regression, and MR-pleiotropy residual sum and outlier (MR-PRESSO) was used for MR analysis. Subsequent pleiotropy and heterogeneity tests were conducted.

RESULTS

IVW analysis exhibited neither an effect of PD on SS (OR = 0.939, 95%CI = 0.525-1.677, P = 0.8304) nor that of SS on PD (OR = 1.007, 95%CI = 0.977-1.038, P = 0.6440). The other five complementary methods further recognized the null association with an effect size close to one. No significant pleiotropy was detected in the relationship between PD and SS (P > 0.05). Heterogeneity existed in the effect of PD on SS but not vice versa.

CONCLUSIONS

No genetic causality between PD and SS or vice versa was supported by our results under MR assumptions and limitations. The study results provided new insights into the relationship between periodontal status and sjogren's syndrome, highlighting the need for a more prudent medical intervention.