Gingival tissue autophagy pathway gene expression profiles in periodontitis and aging.

OBJECTIVE: We hypothesized that autophagy-related genes will be differentially expressed in periodontitis, suggesting an impaired gingival autophagic response associated with disease. BACKGROUND: Autophagy is a cellular physiologic mechanism to maintain tissue homeostasis, while deficient autophagic responses increase inflammation and susceptibility to infection. METHODS: Rhesus monkeys [<3 years to 23 years of age (n = 34)] were examined for periodontal health and naturally occurring periodontitis. Gingival tissues samples were obtained from healthy or diseased sites, total RNA was isolated, and the Rhesus Gene Chip 1.0 ST (Affymetrix) was used for gene expression analysis of 150 autophagy-related genes. RESULTS: Comparison of expression levels with adult healthy tissues demonstrated a rather limited number of individual genes that were significantly different across the age-groups. In contrast, with periodontitis in the adults and aged animals, about 15% of the genes were significantly increased or decreased. The differences were reflected in the mTOR complex (5/12), ULK1/ATG1 complex (5/9), PI3K complex (5/21), ATG9 complex (2/7), ATG12 conjugation/LC3 lipidation (7/22), and lysosome fusion/vesicle degradation [LF/VD (5/10)] activities within the broader autophagic pathway. The genes most greatly altered in gingival tissues of naturally occurring periodontitis were identified in the ATG12 and LF/VD pathways that approximated 50% of the genes in each of those categories. While healthy gingival aging did not appear to reflect altered autophagy gene expression, substantial differences were noted with periodontitis irrespective of the age of the animals. Future studies into the role of autophagy in periodontitis and could offer potential new therapeutic strategies to prevent and/or treat periodontal disease.

Bone biology-related gingival transcriptome in ageing and periodontitis in non-human primates.

AIM: Cellular and molecular immunoinflammatory changes in gingival tissues drive alveolar bone loss in periodontitis. Since ageing is a risk factor for periodontitis, we sought to identify age-related gingival transcriptome changes associated with bone metabolism in both healthy and in naturally occurring periodontitis. MATERIALS AND METHODS: Adult (12-16 years) and aged (18-23 years) non-human primates (M. mulatta) (n = 24) were grouped into healthy and periodontitis. Gingival tissue samples were obtained and subjected to microarray analysis using the Gene Chip Macaque Genome Array. Gene expression profiles involved in osteoclast/osteoblast proliferation, adhesion and function were evaluated and compared across and between the age groups. QPCR was also performed on selected genes to validate microarray data. RESULTS: Healthy aged tissues showed a gene profile expression that suggest enhancement of osteoclastic adhesion, proliferation/survival and function (SPP1, TLR4, MMP8 and TFEC) and impaired osteoblastic activity (SMEK3P and SMAD5). The gingival transcriptome in both adult and aged animals with naturally occurring periodontitis (FOS, IL6, TLR4, MMP9, MMP10 and SPP1 genes) was consistent with a local inflammatory response driving towards bone/connective tissue destruction. CONCLUSION: A pro-osteoclastogenic gingival transcriptome is associated with periodontitis irrespective of age; however; a greater bone-destructive molecular environment is associated with ageing in healthy tissues.

Comparative analysis of gingival tissue antigen presentation pathways in ageing and periodontitis.

AIM: Gingival tissues of periodontitis lesions contribute to local elevations in mediators, including both specific T cell and antibody immune responses to oral bacterial antigens. Thus, antigen processing and presentation activities must exist in these tissues to link antigen-presenting cells with adaptive immunity. We hypothesized that alterations in the transcriptome of antigen processing and presentation genes occur in ageing gingival tissues and that periodontitis enhances these differences reflecting tissues less capable of immune resistance to oral pathogens. MATERIALS AND METHODS: Rhesus monkeys (n = 34) from 3 to 23 years of age were examined. A buccal gingival sample from healthy or periodontitis sites was obtained, total RNA isolated, and microarray analysis was used to describe the transcriptome. RESULTS: The results demonstrated increased transcription of genes related to the MHC class II and negative regulation of NK cells with ageing in healthy gingival tissues. In contrast, both adult and ageing periodontitis tissues showed decreased transcription of genes for MHC class II antigens, coincident with up-regulation of MHC class I-associated genes. CONCLUSION: These transcriptional changes suggest a response of healthy ageing tissues through the class II pathway (i.e. endocytosed antigens) and altered responses in periodontitis that could reflect host-associated self-antigens or targeting cytosolic intracellular microbial pathogens.

Comparative Analysis of Gene Expression Patterns for Oral Epithelial Cell Functions in Periodontitis.

The structure and function of epithelial cells are critical for the construction and maintenance of intact epithelial surfaces throughout the body. Beyond the mechanical barrier functions, epithelial cells have been identified as active participants in providing warning signals to the host immune and inflammatory cells and in communicating various detailed information on the noxious challenge to help drive specificity in the characteristics of the host response related to health or pathologic inflammation. Rhesus monkeys were used in these studies to evaluate the gingival transcriptome for naturally occurring disease samples (GeneChip® Rhesus Macaque Genome Array) or for ligature-induced disease (GeneChip® Rhesus Gene 1.0 ST Array) to explore up to 452 annotated genes related to epithelial cell structure and functions. Animals were distributed by age into four groups: ≤ 3 years (young), 3-7 years (adolescent), 12-16 years (adult), and 18-23 years (aged). For naturally occurring disease, adult and aged periodontitis animals were used, which comprised 34 animals (14 females and 20 males). Groups of nine animals in similar age groups were included in a ligature-induced periodontitis experiment. A buccal gingival sample from either healthy or periodontitis-affected tissues were collected, and microarray analysis performed. The overall results of this investigation suggested a substantial alteration in epithelial cell functions that occurs rapidly with disease initiation. Many of these changes were prolonged throughout disease progression and generally reflect a disruption of normal cellular functions that would presage the resulting tissue destruction and clinical disease measures. Finally, clinical resolution may not signify biological resolution and represent a continued risk for disease that may require considerations for additional biologically specific interventions to best manage further disease.

Decreasing sedentary behavior by 30 minutes per day reduces cardiovascular disease risk factors in rural Americans.

Regular physical activity has been associated with reduced cardiovascular disease (CVD) risk factors; however, a decrease in the amount of time spent during the remainder of the day in sedentary behavior may be equally important. The aim of this study was to examine the effects of a decrease in sedentary behavior on CVD risk factors among 205 individuals living in rural Appalachia. All participants received a comprehensive CVD risk reduction life-style intervention and measurement of major CVD risk factors and physical activity levels. Participants were divided into: 1) Adopters: those who decreased their sedentary behavior by 30 min or more per day post-intervention and 2) Non-adopters: those who did not. Repeated measures analysis of variance showed a significant group by time interaction showing that Adopters had a greater reduction in body weight and BMI than Non-adopters. These findings demonstrate that decreasing sedentary behavior is important for achieving optimal body weight.