Octavio A. Gonzalez

Caloric restriction and chronic inflammatory diseases

A reduction in calorie intake [caloric restriction (CR)] appears to consistently decrease the biological rate of aging in a variety of organisms as well as protect against age-associated diseases including chronic inflammatory disorders such as cardiovascular disease and diabetes. Although the mechanisms behind this observation are not fully understood, identification of the main metabolic pathways affected by CR has generated interest in finding molecular targets that could be modulated by CR mimetics. This review describes the general concepts of CR and CR mimetics as well as discusses evidence related to their effects on inflammation and chronic inflammatory disorders. Additionally, emerging evidence related to the effects of CR on periodontal disease in non-human primates is presented. While the implementation of this type of dietary intervention appears to be challenging in our modern society where obesity is a major public health problem, CR mimetics could offer a promising alternative to control and perhaps prevent several chronic inflammatory disorders including periodontal disease.

HIV-1 Reactivation Induced by the Periodontal Pathogens Fusobacterium nucleatum and Porphyromonas gingivalis Involves Toll-Like Receptor 2 and 9 Activation in Monocytes/Macrophages

ABSTRACT Although oral coinfections (e.g., periodontal disease) are highly prevalent in human immunodeficiency virus type 1-positive (HIV-1+) patients and appear to positively correlate with viral load levels, the potential for oral bacteria to induce HIV-1 reactivation in latently infected cells has received little attention. We showed that HIV-1 long terminal repeat (LTR) promoter activation can be induced by periodontopathogens in monocytes/macrophages; nevertheless, the mechanisms involved in this response remain undetermined. Since Toll-like receptor 2 (TLR2), TLR4, and TLR9 activation have been involved in HIV-1 recrudescence, we sought to determine the role of these TLRs in HIV-1 reactivation induced by the periodontal pathogens Fusobacterium nucleatum and Porphyromonas gingivalis using BF24 monocytes/macrophages stably transfected with the HIV-1 promoter driving chloramphenicol acetyltransferase (CAT) expression and THP89GFP cells, a model of HIV-1 latency. We demonstrated that TLR9 activation by F. nucleatum and TLR2 activation by both bacteria appear to be involved in HIV-1 reactivation; however, TLR4 activation had no effect. Moreover, the autocrine activity of tumor necrosis factor alpha (TNF-α) but not interleukin-1β (IL-1β) produced in response to bacteria could impact viral reactivation. The transcription factors NF-κB and Sp1 appear to be positively regulating HIV-1 reactivation induced by these oral pathogens. These results suggest that oral Gram-negative bacteria (F. nucleatum and P. gingivalis) associated with oral and systemic chronic inflammatory disorders enhance HIV-1 reactivation in monocytes/macrophages through TLR2 and TLR9 activation in a mechanism that appears to be transcriptionally regulated. Increased bacterial growth and emergence of these bacteria or their products accompanying chronic oral inflammatory diseases could be risk modifiers for viral replication, systemic immune activation, and AIDS progression in HIV-1+ patients.

HIV-1 reactivation induced by periodontal pathogens Fusobacterium nucleatum and Porphyromonas gingivalis involves TLR2 and TLR9 activation in monocytes/macrophages

ABSTRACT Although oral coinfections (e.g., periodontal disease) are highly prevalent in human immunodeficiency virus type 1-positive (HIV-1+) patients and appear to positively correlate with viral load levels, the potential for oral bacteria to induce HIV-1 reactivation in latently infected cells has received little attention. We showed that HIV-1 long terminal repeat (LTR) promoter activation can be induced by periodontopathogens in monocytes/macrophages; nevertheless, the mechanisms involved in this response remain undetermined. Since Toll-like receptor 2 (TLR2), TLR4, and TLR9 activation have been involved in HIV-1 recrudescence, we sought to determine the role of these TLRs in HIV-1 reactivation induced by the periodontal pathogens Fusobacterium nucleatum and Porphyromonas gingivalis using BF24 monocytes/macrophages stably transfected with the HIV-1 promoter driving chloramphenicol acetyltransferase (CAT) expression and THP89GFP cells, a model of HIV-1 latency. We demonstrated that TLR9 activation by F. nucleatum and TLR2 activation by both bacteria appear to be involved in HIV-1 reactivation; however, TLR4 activation had no effect. Moreover, the autocrine activity of tumor necrosis factor alpha (TNF-α) but not interleukin-1β (IL-1β) produced in response to bacteria could impact viral reactivation. The transcription factors NF-κB and Sp1 appear to be positively regulating HIV-1 reactivation induced by these oral pathogens. These results suggest that oral Gram-negative bacteria (F. nucleatum and P. gingivalis) associated with oral and systemic chronic inflammatory disorders enhance HIV-1 reactivation in monocytes/macrophages through TLR2 and TLR9 activation in a mechanism that appears to be transcriptionally regulated. Increased bacterial growth and emergence of these bacteria or their products accompanying chronic oral inflammatory diseases could be risk modifiers for viral replication, systemic immune activation, and AIDS progression in HIV-1+ patients.

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.

Differential Gene Expression Profiles Reflecting Macrophage Polarization in Aging and Periodontitis Gingival Tissues

Recent evidence has determined a phenotypic and functional heterogeneity for macrophage populations. This plasticity of macrophage function has been related to specific properties of subsets (M1 and M2) of these cells in inflammation, adaptive immune responses and resolution of tissue destructive processes. This investigation hypothesized that targeted alterations in the distribution of macrophage phenotypes in aged individuals, and with periodontitis would be skewed towards M1 inflammatory macrophages in gingival tissues. The study used a non-human primate model to evaluate gene expression profiles as footprints of macrophage variation in healthy and periodontitis gingival tissues from animals 3–23 years of age and in periodontitis tissues in adult and aged animals. Significant increases in multiple genes reflecting overall increases in macrophage activities were observed in healthy aged tissues, and were significantly increased in periodontitis tissues from both adults and aged animals. Generally, gene expression patterns for M2 macrophages were similar in healthy young, adolescent and adult tissues. However, modest increases were noted in healthy aged tissues, similar to those seen in periodontitis tissues from both age groups. M1 macrophage gene transcription patterns increased significantly over the age range in healthy tissues, with multiple genes (e.g. CCL13, CCL19, CCR7 and TLR4) significantly increased in aged animals. Additionally, gene expression patterns for M1 macrophages were significantly increased in adult health versus periodontitis and aged healthy versus periodontitis. The findings supported a significant increase in macrophages with aging and in periodontitis. The primary increases in both healthy aged tissues and, particularly periodontitis tissues appeared in the M1 phenotype.

Effects of aging in the expression of NOD‐like receptors and inflammasome‐related genes in oral mucosa

The molecular changes underlying the higher risk of chronic inflammatory disorders during aging remain incompletely understood. Molecular variations in the innate immune response related to recognition and interaction with microbes at mucosal surfaces could be involved in aging-related inflammation. We developed an ontology analysis of 20 nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) and seven inflammasome-related genes (IRGs) in healthy and inflamed/periodontitis oral mucosal tissues from young, adolescent, adult, and aged non-human primates (Macaca mulatta) using the GeneChip(®) Rhesus Macaque Genome array. Validation of some of the significant changes was done by quantitative reverse transcription-polymerase chain reaction. The expression of NLRB/NAIP, NLRP12, and AIM2 increased with aging in healthy mucosa whereas NLRC2/NOD2 expression decreased. Although higher expression levels of some NLRs were generally observed with periodontitis in adult mucosal tissues (e.g. NLRB/NAIP, NLRP5, and NLRX1), various receptors (e.g. NLRC2/NOD2 and NLRP2) and the inflammasome adaptor protein ASC, exhibited a significant reduction in expression in aged periodontitis tissues. Accordingly, the expression of NLR-activated innate immune genes, such as HBD3 and IFNB1, was impaired in aged but not adult periodontitis tissues. Both adult and aged tissues showed significant increase in interleukin-1β expression. These findings suggest that the expression of a subset of NLRs appears to change with aging in healthy oral mucosa, and that aging-related oral mucosal inflammation could involve an impaired regulation of the inflammatory and antimicrobial response associated with downregulation of specific NLRs and IRGs.

Dietary modulation of the inflammatory cascade

Dietary supplementation has traditionally consisted of adding vitamins and/or minerals to correct or prevent a nutritional deficiency. When supplementing the diet with other inflammatory mediators, such as essential fatty acids, there is an adjunctive benefit to the standard therapies used in the control of chronic inflammatory diseases such as Crohns disease or rheumatoid arthritis. This review focuses on the strategies utilized for therapeutic modulation of the inflammatory cascade through dietary supplementation with specific biomolecules. Examples of how these biomolecules affect local and systemic immune responses to chronic inflammation are examined. In particular, an overview of the literature identifying the potential to modify the host response to chronic periodontitis is provided.

Oral bacteria induce a differential activation of human immunodeficiency virus-1 promoter in T cells, macrophages and dendritic cells

INTRODUCTION The human immunodeficiency virus (HIV) can integrate into T cells, macrophages and dendritic cells resulting in a latent infection. Reports have also demonstrated that various microbial and host cell factors can trigger HIV reactivation leading to HIV recrudescence, potentially undermining highly active antiretroviral therapies. METHODS This study evaluated the capacity of oral bacteria associated with chronic periodontal infections to stimulate HIV promoter activation in various cell models of HIV latency. RESULTS T cells (1G5) challenged with oral bacteria demonstrated a dose-response of HIV promoter activation with a subset of the bacteria, as well as kinetics that were generally similar irrespective of the stimuli. Direct bacterial challenge of the T cells resulted in increased activation of approximately 1.5- to 7-fold over controls. Challenge of macrophages (BF24) indicated different kinetics for individual bacteria and resulted in consistent increases in promoter activation of five fold to six fold over basal levels for all bacteria except Streptococcus mutans. Dendritic cells showed increases in HIV reactivation of 7- to 34-fold specific for individual species of bacteria. CONCLUSION These results suggested that oral bacteria have the capability to reactivate HIV from latently infected cells, showing a relationship of mature dendritic cells > immature dendritic cells > macrophages > or = T cells. Expression of various pattern recognition receptors on these various cell types may provide insight into the primary receptors/signaling pathways used for reactivation by the bacteria.

Antibacterial Effects of Blackberry Extract Target Periodontopathogens

BACKGROUND AND OBJECTIVE Antimicrobial agents provide valuable adjunctive therapy for the prevention and the control of oral diseases. Limitations in their prolonged use have stimulated the search for new, naturally occurring agents with more specific activity and fewer adverse effects. Here we sought to determine the antibacterial properties of blackberry extract (BBE) in vitro against oral bacterial commensals and periodontopathogens. MATERIAL AND METHODS The effects of whole and fractionated BBE on the metabolism of 10 different oral bacteria were evaluated using the colorimetric water-soluble tetrazolium-1 assay. The bactericidal effects of whole BBE against Fusobacterium nucleatum were determined by quantitating the numbers of colony-forming units (CFUs). Cytotoxicity was determined in oral epithelial (OKF6) cells. RESULTS BBE at 350-1400 μg/mL reduced the metabolic activity of Porphyromonas gingivalis, F. nucleatum and Streptococcus mutans. The reduced metabolic activity observed for F. nucleatum corresponded to a reduction in the numbers of CFUs following exposure to BBE for as little as 1 h, indicative of its bactericidal properties. An anthocyanin-enriched fraction of BBE reduced the metabolic activity of F. nucleatum, but not of P. gingivalis or S. mutans, suggesting the contribution of species-specific agents in the whole BBE. Oral epithelial cell viability was not reduced following  exposure to whole BBE (2.24-1400 μg/mL) for ≤ 6 h. CONCLUSION BBE alters the metabolic activity of oral periodontopathogens while demonstrating a minimal effect on commensals. The specific antibacterial properties of BBE shown in this study, along with its previously demonstrated anti-inflammatory and antiviral properties, make this natural extract a promising target as an adjunct for prevention and/or complementary therapy of periodontal infections.

Familial periodontal disease in the cayo santiago rhesus macaques

Substantial ongoing research continues to explore the contribution of genetics and environment to the onset, extent and severity of periodontal disease(s). Existing evidence supports that periodontal disease appears to have an increased prevalence in family units with a member having aggressive periodontitis. We have been using the nonhuman primate as a model of periodontal disease for over 25 years with these species demonstrating naturally occurring periodontal disease that increases with age. This report details our findings from evaluation of periodontal disease in skulls from 97 animals (5–31 years of age) derived from the skeletons of the rhesus monkeys (Macaca mulatta) on Cayo Santiago. Periodontal disease was evaluated by determining the distance from the base of the alveolar bone defect to the cemento‐enamel junction on 1st/2nd premolars and 1st/2nd molars from all four quadrants. The results demonstrated an increasing extent and severity of periodontitis with aging across the population of animals beyond only compensatory eruption. Importantly, irrespective of age, extensive heterogeneity in disease expression was observed among the animals. Linking these variations to multi‐generational matriarchal family units supported familial susceptibility of periodontitis. As the current generations of animals that are descendants from these matrilines are alive, studies can be conducted to explore an array of underlying factors that could account for susceptibility or resistance to periodontal disease. Am. J. Primatol. 78:143–151, 2016.