Age-dependent differential expression of apoptosis markers in the gingival tissue

Immunohistochemical analysis with apoptosis and autophagy markers in periodontitis and peri-implantitis: Clinical comparative study

BACKGROUND AND OBJECTIVES

Recently, the terms autophagy and apoptosis have been studied on implants, especially in cell culture and in vitro studies, but in vivo evaluations are limited. The aim of this study was to compare the differences in apoptosis and autophagy intensity at the molecular and cellular level in periodontal and peri-implant diseases.

METHODS

Sixty-four biopsy samples were obtained from 52 patients, 36 female and 16 male, whose mean age was between 18 and 75, and were included in the study. The periodontitis group was defined as PG (n:30 sample) and the peri-implantitis group as IG (n:34 samples). Granulation tissues as biopsy materials were collected, and immunohistochemical analysis was performed with hematoxylin-eosin, Masson's trichrome, anti-MAP1LC3A, anti-beclin, and anti-active caspase-3 antibodies and terminal TdT-mediated dUTP-biotin nick end labeling (TUNEL) methods. The histological slide images were evaluated with the ImageJ software program. Inflammatory cell density in epithelial tissue, inflammatory cell density in connective tissue, the density of necrotic tissue debris, and collagen density in connective tissue were scored between 0 and 3 (0: none, 1: minimal, 2: moderate, 3: severe by hematoxylin-eosin and Masson's trichrome). The antibody binding reaction areas were evaluated per unit area (mm² ) in connective tissue by immunohistochemical examination.

RESULTS

As histochemical evaluations, there was no statistically significant differences the mean inflammatory cell density value in the epithelial tissue, inflammatory cell density value in the connective tissue, density value of necrotic tissue debris, collagen density value in the connective tissue between the groups. There was no statistically significant difference on immunohistochemical staining with LC3, caspase-3, Beclin-1 and TUNEL between the two groups (p > .05).

CONCLUSIONS

A higher rate of inflammatory accumulation was shown on peri-implantitis, but no difference was found between periodontitis and peri-implantitis according to autophagy and apoptosis markers. Studies with high sample sizes with different markers are needed.

The role of caspase-8, caspase-9, and apoptosis inducing factor in periodontal disease

BACKGROUND

Caspases are key mediators of apoptosis. Caspase-8 mediates extrinsic, and caspase-9 initiates the intrinsic pathway of apoptosis. Apoptosis Inducing Factor (AIF), a mitochondrial proapoptotic protein, mediates cell death by a caspase-independent process. Because apoptosis is involved in periodontal disease, this study evaluated caspase-8, -9, and AIF in periodontal disease.

METHODS

Twenty periodontally healthy volunteers (Group Healthy), 20 patients with generalized aggressive periodontitis (Group AgP), and 20 patients with generalized chronic periodontitis (Group CP) were included in this study. Levels of caspase-8, -9, and AIF were evaluated in gingival crevicular fluid (GCF) of all participants via enzyme-linked immunosorbent assays.

RESULTS

AIF was significantly higher in the AgP (P = 0.07) and CP groups (P = 0.01) than the Healthy group, and similar to the CP and AgP groups (P > 0.05). Caspase-8 was significantly higher in the CP and Healthy groups than the AgP group (P = 0.00), and similar between Healthy and CP groups (P > 0.05). Caspase-9 was significantly higher in the AgP group than the Healthy group (P = 0.01), and similar between Healthy and CP groups (P > 0.05).

CONCLUSIONS

The mitochondrial-centered intrinsic pathway involving caspase-9 and AIF, and the extrinsic pathway involving caspase-8 are significant for aggressive periodontitis. The intrinsic pathway involving caspase-independent AIF is also significant for chronic periodontitis.

Sex differences in inflammatory and apoptotic signaling molecules in normal and diseased human gingiva

BACKGROUND

The purpose of this study is to determine whether sex dimorphism exists in the expression of inflammatory and apoptotic mediators in gingiva obtained from normal and diseased sites of periodontal disease.

METHODS

Gingival papillae were obtained from individuals (56 males and 62 females) who required extraction of adjacent teeth. Gingival samples were grouped by adjacent sulcus depth: 1 to 3 mm (normal), 3 mm with bleeding on probing (slight disease), 3 to 6 mm (moderate disease), and >6 mm (severe disease). The tissue concentrations of cysteine-requiring aspartate-directed protease 3 (caspase-3), interleukin-2, tumor necrosis factor-related apoptosis-inducing ligand, Fas ligand, p38α mitogen-activated protein kinase, extracellular signal-related kinase 1/2, and survivin were determined by enzyme-linked immunosorbent assay. These mediator concentrations, age of donor, sex of donor, and gingival sulcular depth were the outcome variables. Data were compared by factorial analysis of variance, post hoc Tukey, and Pearson correlation test. P <0.05 was used to indicate significant differences among the outcome variables.

RESULTS

The mean gingival sulcular depth was significantly greater in male than in female groups (P <0.05). The majority of the tested mediators were significantly correlated with both sex and sulcular depth and with caspase-3 (P <0.05). The concentration of caspase-3 in female gingiva at all diseased sites was significantly greater than in gingiva derived from male sites (P <0.05).

CONCLUSIONS

These data suggest sex dimorphism in the presence of gingival apoptosis at sites of periodontal disease, with females having the highest incidence of apoptosis. Because apoptosis clears inflammatory cells and promotes healing, this phenomenon could provide a mechanism for sex dimorphism for the incidence of periodontal disease.

Apoptotic genes are differentially expressed in aged gingival tissue

Cellular and molecular changes of the periodontium associated with a higher prevalence of oral diseases (e.g., chronic periodontitis) in aged populations have received little attention. Since impaired apoptosis during aging appears to be related to chronic inflammatory disorders, we hypothesized that the expression of genes associated with apoptotic processes are altered in aged healthy and periodontitis-affected gingival tissue. Ontology analysis of 88 genes related to apoptotic pathways was performed in gingival biopsies of healthy and periodontitis sites from young, adult, and aged non-human primates (Macaca mulatta), using the GeneChip® Rhesus Macaque Genome Array. Lower expression of anti-apoptotic and higher expression of pro-apoptotic genes were associated with healthy gingival tissue from young compared with aged animals. Few differences in gene expression were observed in healthy gingival tissue between adult and aged animals. Comparison between healthy and periodontitis gingival tissues showed that the up- or down-regulated apoptotic genes in diseased gingival tissue are different in adults compared with aged animals. These results suggest that apoptotic events normally occurring in gingival tissues could be reduced in aging,and unique aspects of apoptotic pathways are potentially involved in the pathophysiology of periodontal disease in adult vs. aged gingival tissues.