Presence of mast cells and the expression of metalloproteinase 9 in the gingiva of ovariectomized rats with periodontal disease

Innate and adaptive immunity of periodontal disease. From etiology to alveolar bone loss

Periodontal disease refers to inflammation of the tissues that support the tooth. It is of multifactorial etiology. Innate and adaptive immune cells participate jointly through the release of their molecules and mechanisms of action in order to maintain homeostasis in periodontal tissues, so the host's immune response plays an essential role in defense against microorganisms. However, bacterial persistence and the dysregulation of the immune system as an exaggerated response can lead to the worsening of periodontal disease, leading to loss of gingival tissue and alveolar bone and thereby loss of teeth. Therefore, a better understanding of the cellular mechanisms involved in the development of periodontal disease is necessary to design new treatments and prophylactic measures in order to decrease the prevalence of this disease that afflicts a large part of the world population.

Effects of estrogen deficiency followed by streptozotocin-induced diabetes on periodontal tissues of female rats

Although both estrogen deficiency and diabetes contribute to periodontal tissue deterioration, the combined effects of these conditions on periodontium is unknown. Thus, we analyzed the combined effects of ovariectomy followed by streptozotocin (STZ)-induced diabetes on periodontal tissues of rats. Twenty adult rats were ovariectomized (OVX) or SHAM-operated (SHAM). After 3 weeks, the rats received an intraperitoneal injection of STZ (60 mg/kg/body weight) to induce diabetes or vehicle (blank) solution. The groups were assigned as follows (n = 5): SHAM-vehicle (SHAM), OVX-vehicle (OVX), SHAM + STZ (SHAM-Di), and OVX + STZ (OVX-Di). Seven weeks post-diabetes induction, the rats were euthanized. Blood samples were collected for glucose measurements and maxillae were processed for paraffin embedding. Sections stained with hematoxylin/eosin, Masson's trichrome, and picrosirius-red were used for alveolar bone loss and collagen fiber analysis in the lamina propria. Immunohistochemistry was performed for runt-related transcription factor 2 (Runx2), matrix metalloproteinase 9 (MMP-9), and tryptase detection. Alveolar bone loss and fewer collagen fibers were observed in the OVX-Di group, collagen fibers with irregular organization, and MMP-9 immunoreactivity were more evident in diabetic groups, and MMP-9-positive osteoclasts on alveolar bone surface were noticed in all groups. The OVX-Di group showed lower Runx2 immunoreactivity (osteoblast formation marker), and more tryptase-positive cells (mast cell marker) in the alveolar bone marrow. Our results indicate that estrogen depletion, followed by STZ-induced diabetes, promotes periodontal tissue deterioration that is more evident than both interventions applied alone. Furthermore, our results points to a possible participation of bone-derived mast cells in this process.

Cyclosporine A - Induced gingival overgrowth and proliferating cell nuclear antigen expression in experimental periodontitis

The most important microscopic characteristic of Cyclosporine A-induced gingival overgrowth is fibroepithelial hyperplasia.

OBJECTIVE

The objective was to investigate the influence of previous exposure to Cyclosporine A over gingival epithelium in experimental periodontitis in rats.

METHODS

Twenty Wistar rats with 12 weeks-old were divided into four groups with 5 animals each: Control Group (CG); Cyclosporine Group (CsAG); Ligature group (LG) and Cyclosporine and Ligature Group (CsALG). Daily doses of CsA (10 mg/kg) were applied to CsAG and CsALG during 60 days since the beginning of the experiment and, a ligature was placed in LG and CsALG 30 days after the beginning of the experiment. After 60 days, animals were euthanized and gingival tissue was processed to histomorphometric analysis of epithelial thickness (mm²), immunohistochemical expression of PCNA (%) and inflammatory response. Data were analyzed by Kruskal-Wallis and Mann Whitney at 0.05 significance level.

RESULTS

Considering epithelial thickness, CG was thinner than all groups, CsALG was the largest and CsAG and LG were similar between each other. Regarding the PCNA expression CG (16.46 ± 9.26) was similar to CsAG (34.47 ± 19.75) and, LG (59.02 ± 10.33) was similar to CsALG (40.59 ± 18.25). Significant difference (p < 0.05) occurred only in inflammation presence comparing CG/LG and CsAG/CsALG. A weak positive correlation between the number of PCNA+ and inflammatory cells (p = 0.001; r = 0.611) was observed.

CONCLUSION

Based on these results it was concluded that the enlargement of gingival epithelium observed in experimental periodontitis can be increased by previous exposition to CsA and inflammatory conditions enhanced proliferative activity of the keratinocytes.