Response to systemic microbial challenge in mice strains resistant and susceptible to periodontal disease

Author(s)

Cristhiam de Jesus Hernandez Martinez

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2024-05-21

Examining board members

Daniela Bazan Palioto Bulle; Luiz Guilherme de Siqueira Branco; Ricardo Della Coletta; Carlos Rossa Junior

• Advisor: Daniela Bazan Palioto Bulle; Flavia Aparecida Chaves Furlaneto Messora

Abstract

The objective of these studies was to analyze the differences in susceptibility to periodontal disease (PD) after systemic microbial challenge in mouse strains known to be susceptible (Balb/C) and resistant (C57bl/6). A total of 140 mice were used, divided into 2 groups (n=70 Balb/C & n=70 C57bl/6). Each group was further divided into 3 subgroups: Control (C), Sham vehicle with 2% sterile carboxymethylcellulose (Sham), Gavage with Porphyromonas gingivalis W83 (Gav). Microbial challenge was conducted weekly for 3 weeks, and after this period, the mice were maintained until completing 42 days of the experiment when they were euthanized. The following were evaluated: 1) alveolar bone microarchitecture in the upper second molar region using X-ray microcomputed tomography (Micro-CT); 2) severity of inflammation in the interproximal region of the upper second molar through histomorphometric analysis; 3) expression of epigenetic methylation markers (DNMT3b) and acetylation of histone 3 (H3ac) and histone 4 (H4ac) through indirect immunofluorescence in the intestine and maxilla in control and gavage groups after two weeks of periodontal disease induction; 4) methylation profile. Oral administration of Porphyromonas gingivalis induced periodontitis in Balb/c and C57bl/6, as assessed by MicroCT and Histomorphometry. Significant loss of bone volume and trabecular thickness, with increased bone porosity, was observed after one week of challenge (p<0.001). Balb/c exhibited a faster establishment of the disease. A distinct methylation profile was observed in Balb/c, with hypermethylation in non-induced sections and hypomethylation in induced groups. Differentially methylated regions, especially in promoters, revealed statistically significant disparities between groups. Changes in levels of histone acetylation H3ac and H4ac, as well as DNMT3b methylation in immunofluorescence analyses, were more pronounced in Balb/c, both in the maxilla and intestinal tissues. After one week of challenge, both strains showed evidence of bone loss, more pronounced in Balb/c. Differential methylation patterns suggest epigenetic contributions to variations in susceptibility to the disease, highlighting regions related to immune regulation and inflammatory response as targets for future research. This study emphasizes the importance of epigenetic mechanisms in periodontitis. Clinical relevance: Our study sheds light on the influence of epigenetic backgrounds on susceptibility to periodontal disease. These findings open new avenues for investigating additional epigenetic modifications, allowing a more comprehensive understanding of the molecular mechanisms underlying periodontal disease. Ultimately, insights gained from this research have the potential to drive new investigations into diagnostic and therapeutic approaches for managing this disease. (AU)

• FAPESP's process: 19/20103-5 - Epigenetic susceptibility to periodontal disease
• Grantee: Cristhiam de Jesus Hernandez Martinez
• Support Opportunities: Scholarships in Brazil - Doctorate