Replication of gene polymorphisms associated with periodontitis-related traits in an elderly cohort: the Washington Heights/Inwood Community Aging Project Ancillary Study of Oral Health

Genetic Biomarkers for Periodontal Diseases: A Systematic Review

AIMS

To identify genetic biomarkers that may be used in the diagnosis, prevention or management of different forms of periodontal disease.

MATERIALS AND METHODS

Following protocol registration and PICOTS (patient, intervention, comparison, outcome, time, studies) questions, a systematic search of the literature was conducted (PudMed, Ovid), resulting in 1592 papers screened by two reviewers. Diagnostic data were extracted or calculated from included papers and compared with clinically determined diagnoses, disease progression and/or response to treatment.

RESULTS

A total of 607 articles met the inclusion criteria, including 10 reporting data on gingivitis and 597 on periodontitis. Only two papers reported diagnostic performance data, while for 41 articles on large candidate gene studies, diagnostic performance could be calculated from the reported data. No study using chair-side tests was identified. Low to moderate values for sensitivity, specificity, positive and negative predictive value and diagnostic accuracy were found.

CONCLUSION

No genetic diagnostic test of clinical value emerged for periodontal diagnosis, prevention or prediction of disease resolution. Thus, potential future applications of polygenic risk scores that encode susceptibility, as well as single-marker testing for monogenic or oligogenic forms of periodontal diseases, are discussed.

Hypomethylation of the low-density lipoprotein receptor class A domain containing 4 gene in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease linked to epigenetic changes, particularly DNA methylation. While LDLRAD4 has been implicated in RA through GWAS, its role in RA via methylation remains unclear.

OBJECTIVES

To investigate LDLRAD4 methylation patterns in RA and evaluate its potential as a diagnostic and inflammatory biomarker.

METHODS

We assessed DNA methylation at specific CpG sites within LDLRAD4 in 150 RA patients and 150 healthy controls. Clinical data, including disease duration and inflammatory markers, were collected.

RESULTS

RA patients showed significant hypomethylation of LDLRAD4, especially in the LDLRAD4-43 and LDLRAD4-44 regions. ROC analysis yielded an AUC of 0.841, indicating strong diagnostic potential. Methylation levels correlated negatively with ESR, CRP and DAS28 in the RF+/CCP- subgroup.

CONCLUSIONS

LDLRAD4 DNA present hypomethylation in rheumatoid arthritis, and methylation levels are correlated with inflammatory indicator, possibly via TGF-β signaling. Further research is needed to explore its therapeutic potential.

Porphyromonas gingivalis virulence factors induce toxic effects in SH-SY5Y neuroblastoma cells: GRK5 modulation as a protective strategy

Periodontitis (PDS) is a chronic inflammatory disease initiated by a dysbiosis of oral pathogenic bacterial species, such as Porphyromonas gingivalis (Pg). These bacteria can penetrate the bloodstream, releasing various endo and exotoxins that fuel the infection, and stimulate toxic inflammation in different compartments, including the brain. However, the specific mechanisms by which PDS/Pg contribute to brain disorders, such as Alzheimer's disease (AD), remain unclear. This study assessed the effects of Pg's virulence factors - lipopolysaccharide (LPS-Pg) and gingipains (gps) K (Kgp) and Rgp - on SH-SY5Y cells. Our results demonstrated that LPS-Pg activated signaling through the Toll-like receptor (TLR)-2/4 induced a significant downregulation of G protein-coupled receptor kinase 5 (GRK5). Additionally, LPS-Pg stimulation resulted in a robust increase in Tau phosphorylation (pTau) and p53 levels, while causing a marked reduction in Bcl2 and increased cell death compared to unstimulated cells (Ns). LPS-Pg also elevated inducible nitric oxide synthase (iNOS) expression, leading to oxidative damage. In cells overexpressing GRK5 via Adenovirus, LPS-Pg failed to increase iNOS and pTau levels compared to GFP control cells. High GRK5 levels also prevented the nuclear accumulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB). Furthermore, the overexpression of a GRK5 mutant form lacking the nuclear localization signal (ΔNLS) nearly abolished LPS-Pg induced p53 and iNOS upregulation. Finally, we tested whether Kgp and Rgp mediated similar effects and our data showed that both gps caused a marked downregulation of GRK5 leading to increased p53 and pTau levels. In conclusion, this study provides further insight into the toxic effects elicited by Pg in cells and suggests that preventing GRK5 deficiency may be a valid strategy to mitigate Pg-induced toxic effects (i.e. cell death, oxidative damage, and Tau hyperphosphorylation) in SH-SY5Y cells, which are typical molecular hallmarks of neurodegenerative disorders.

Periodontitis and brain magnetic resonance imaging markers of Alzheimer's disease and cognitive aging

INTRODUCTION

We examined the association of clinical, microbiological, and host response features of periodontitis with MRI markers of atrophy/cerebrovascular disease in the Washington Heights Inwood Columbia Aging Project (WHICAP) Ancillary Study of Oral Health.

METHODS

We analyzed 468 participants with clinical periodontal data, microbial plaque and serum samples, and brain MRIs. We tested the association of periodontitis features with MRI features, after adjusting for multiple risk factors for Alzheimer's disease/Alzheimer's disease-related dementia (AD/ADRD).

RESULTS

In fully adjusted models, having more teeth was associated with lower odds for infarcts, lower white matter hyperintensity (WMH) volume, higher entorhinal cortex volume, and higher cortical thickness. Higher extent of periodontitis was associated with lower entorhinal cortex volume and lower cortical thickness. Differential associations emerged between colonization by specific bacteria/serum antibacterial IgG responses and MRI outcomes.

DISCUSSION

In an elderly cohort, clinical, microbiological, and serological features of periodontitis were associated with MRI findings related to ADRD risk. Further investigation of causal associations is warranted.

With Teeth, Broken, or Fixed: The Challenges of Linking Periodontitis, Neuroepidemiology, and Biomarkers of Disease

Periodontitis is a chronic inflammatory, bacterially-driven disease of the tooth-supporting tissues that shares several risk factors and elements of host response with Alzheimer's disease and related dementias (ADRD). Epidemiological studies have identified relatively consistent associations between adverse oral health conditions and ADRD. In this issue of the journal, a large study from the UK Biobank further explores these relationships along with MRI cognitive biomarkers. Despite its strength due to the large sample size, challenges in the study of periodontitis and neuroepidemiology markers include potential sampling bias, appropriate assessment of exposures, and the possibility of reverse causality.