Evaluation of morphological, histological, and immune-related cellular changes in ligature-induced experimental periodontitis in mice

Experimental Murine Periodontitis Increases Salivary Gland IgA-Producing B Cells Following Oral Dysbiosis

The oral microbiome is closely involved in the maintenance of host health and the development of systemic diseases. The salivary glands play an essential role in homeostasis in the oral cavity. Here, we investigated the effects of periodontal inflammation on salivary gland function and the oral microbiome. In experimental periodontitis model mice, an increase in IgA⁺ cells in the salivary glands were observed 1 week after treatment. Alteration of the oral microbiome was also induced in this model. Gene expression analysis of the salivary glands showed changes in the expression of genes related to B-cell maturation and plasma cell differentiation and an increase in the expression of genes related to macrophage activation upon experimental periodontitis induction. Furthermore, the relationship between disruption of oral microflora and salivary gland function was examined using a cohousing model in which experimental periodontitis model mice and untreated mice were reared in the same cage. We found that cohoused normal mice underwent alteration of the oral microbiome, with increases in IgA⁺ cells and macrophages in the salivary glands. In summary, our results suggest that, in the oral cavity, there is a close link between oral bacterial flora and immune cells in the salivary glands. Our results also show that localized inflammation disrupts the homeostasis in the oral cavity, inducing pathological conditions such as dysbiosis. Our study suggests the importance of the interaction among local oral inflammation, salivary gland function, and oral microflora, and provides new insights into the mechanisms by which oral health is maintained.

NOD2 contributes to Parvimonas micra-induced bone resorption in diabetic rats with experimental periodontitis

BACKGROUND

Type 2 diabetes mellitus (T2DM) may affect the oral microbial community, exacerbating periodontal inflammation; however, its pathogenic mechanisms remain unclear. As nucleotide-binding oligomerization domain 2 (NOD2) plays a crucial role in the activation during periodontitis (PD), it is hypothesized that changes in the oral microbial community due to diabetes enhance periodontal inflammation through the activation of NOD2.

METHODS

We collected subgingival plaque from 180 subjects who were categorized into two groups based on the presence or absence of T2DM. The composition of oral microbiota was detected by 16S rRNA high-throughput sequencing. In animal models of PD with or without T2DM, we assessed alveolar bone resorption by micro-computerized tomography and used immunohistochemistry to detect NOD2 expression in alveolar bone. Primary osteoblasts were cultured in osteogenic induction medium with high or normal glucose and treated with inactivated bacteria. After 24 h of inactivated bacteria intervention, the osteogenic differentiation ability was detected by alkaline phosphatase (ALP) staining, and the expressions of NOD2 and interleukin-12 (IL-6) were detected by western blot.

RESULTS

The relative abundance of Parvimonas and Filifactor in the T2DM group was increased compared to the group without T2DM. In animal models, alveolar bone mass was decreased in PD, particularly in T2DM with PD (DMPD) group, compared to controls. Immunohistochemistry revealed NOD2 in osteoblasts from the alveolar bone in both the PD group and DMPD group, especially in the DMPD group. In vitro, intervention with inactivated Parvimonas significantly reduced ALP secretion of primary osteoblasts in high glucose medium, accompanied by increased expression of NOD2 and IL-6.

CONCLUSIONS

The results suggest that T2DM leading to PD may be associated with the activation of NOD2 by Parvimonas.

Experimental Periodontitis Worsens Dopaminergic Neuronal Degeneration

AIM

To investigate the hypothesis supporting the link between periodontitis and dopaminergic neuron degeneration.

MATERIALS AND METHODS

Adult male Wistar rats were used to induce dopaminergic neuronal injury with 6-hydroxydopamine (6-OHDA) neurotoxin and experimental periodontitis via ligature placement. Motor function assessments were conducted before and after periodontitis induction in controls and 6-OHDA-injury-induced rats. Tissue samples from the striatum, jaw and blood were collected for molecular analyses, encompassing immunohistochemistry of tyrosine hydroxylase, microglia and astrocyte, as well as micro-computed tomography, to assess alveolar bone loss and for the analysis of striatal oxidative stress and plasma inflammatory markers.

RESULTS

The results indicated motor impairment in 6-OHDA-injury-induced rats exacerbated by periodontitis, worsening dopaminergic striatal degeneration. Periodontitis alone or in combination with 6-OHDA-induced lesion was able to increase striatal microglia, while astrocytes were increased by the combination only. Periodontitis increased striatal reactive oxygen species levels and plasma tumour necrosis factor-alpha levels in rats with 6-OHDA-induced lesions and decreased the anti-inflammatory interleukin-10.

CONCLUSIONS

This study provides original insights into the association between periodontitis and a neurodegenerative condition. The increased inflammatory pathway associated with both 6-OHDA-induced dopaminergic neuron lesion and periodontal inflammatory processes corroborates that the periodontitis-induced systemic inflammation may aggravate neuroinflammation in Parkinson's-like disease, potentially hastening disease progression.

CHANGES IN THE ULTRASTRUCTURAL ELEMENTS OF PERIODONTAL NEUROTROPHY UNDER CONDITIONS OF ACUTE SIMPLE COAGULATION DYSTROPHY IN THE EXPERIMENT

OBJECTIVE

Aim: To determine the role of damage to the ultrastructural elements of the periodontal nervous system in the pathogenesis of dystrophic periodontal disease.

PATIENTS AND METHODS

Materials and Methods: The basis of the experimental part of the study was the preparation of ultrathin sections from blocks of gum tissue of white rats, which were prepared using the UMTP-3M device. The study and analysis of biopsy samples was carried out with the help of an electron microscope UEMV-100K.

RESULTS

Results: With the help of transmission electron microscopy, it was found that from the first minutes after the injection of hemolysate of isogenic erythrocytes into the rats, aggregates of erythrocytes, clumps of blood plasma, clusters of fibrin monomer masses, bundles of fibrin fibers, platelet and homogeneous were present in the connective tissue of the gums, and in particular in the lumens of hemocapillaries microthrombi, which confirms damage to the ultrastructures of the periodontium, which lead to the development of a pathological process, which is described when simple coagulation dystrophy is reproduced.

CONCLUSION

Conclusions: Coagulative damage to the ultrastructural elements of the periodontal nervous system is one of the important factors in the pathogenesis of dystrophic periodontal damage. Under these conditions, trophic disturbances occur, similar to those that occur when the integrity of the nerve is disturbed - neurotrophic mechanism of dystrophy.