DNA methylation changes underlie the long-term association between periodontitis and atherosclerotic cardiovascular disease.

Periodontitis, the leading cause of adult tooth loss, has been identified as an independent risk factor for cardiovascular disease (CVD). Studies suggest that periodontitis, like other CVD risk factors, shows the persistence of increased CVD risk even after mitigation. We hypothesized that periodontitis induces epigenetic changes in hematopoietic stem cells in the bone marrow (BM), and such changes persist after the clinical elimination of the disease and underlie the increased CVD risk. We used a BM transplant approach to simulate the clinical elimination of periodontitis and the persistence of the hypothesized epigenetic reprogramming. Using the low-density lipoprotein receptor knockout (LDLRo ) atherosclerosis mouse model, BM donor mice were fed a high-fat diet to induce atherosclerosis and orally inoculated with Porphyromonas gingivalis (Pg), a keystone periodontal pathogen; the second group was sham-inoculated. Naïve LDLR o mice were irradiated and transplanted with BM from one of the two donor groups. Recipients of BM from Pg-inoculated donors developed significantly more atherosclerosis, accompanied by cytokine/chemokines that suggested BM progenitor cell mobilization and were associated with atherosclerosis and/or PD. Using whole-genome bisulfite sequencing, 375 differentially methylated regions (DMRs) and global hypomethylation in recipients of BM from Pg-inoculated donors were observed. Some DMRs pointed to the involvement of enzymes with major roles in DNA methylation and demethylation. In validation assays, we found a significant increase in the activity of ten-eleven translocase-2 and a decrease in the activity of DNA methyltransferases. Plasma S-adenosylhomocysteine levels were significantly higher, and the S-adenosylmethionine to S-adenosylhomocysteine ratio was decreased, both of which have been associated with CVD. These changes may be related to increased oxidative stress as a result of Pg infection. These data suggest a novel and paradigm-shifting mechanism in the long-term association between periodontitis and atherosclerotic CVD.

Endothelial Cell CD36 Reduces Atherosclerosis and Controls Systemic Metabolism.

High-fat Western diets contribute to tissue dysregulation of fatty acid and glucose intake, resulting in obesity and insulin resistance and their sequelae, including atherosclerosis. New therapies are desperately needed to interrupt this epidemic. The significant idea driving this research is that the understudied regulation of fatty acid entry into tissues at the endothelial cell (EC) interface can provide novel therapeutic targets that will greatly modify health outcomes and advance health-related knowledge. Dysfunctional endothelium, defined as activated, pro-inflammatory, and pro-thrombotic, is critical in atherosclerosis initiation, in modulating thrombotic events that could result in myocardial infarction and stroke, and is a hallmark of insulin resistance. Dyslipidemia from high-fat diets overwhelmingly contributes to the development of dysfunctional endothelium. CD36 acts as a receptor for pathological ligands generated by high-fat diets and in fatty acid uptake, and therefore, it may additionally contribute to EC dysfunction. We created EC CD36 knockout (CD36°) mice using cre-lox technology and a cre-promoter that does not eliminate CD36 in hematopoietic cells (Tie2e cre). These mice were studied on different diets, and crossed to the low density lipoprotein receptor (LDLR) knockout for atherosclerosis assessment. Our data show that EC CD36° and EC CD36°/LDLR° mice have metabolic changes suggestive of an uncompensated role for EC CD36 in fatty acid uptake. The mice lacking expression of EC CD36 had increased glucose clearance compared with controls when fed with multiple diets. EC CD36° male mice showed increased carbohydrate utilization and decreased energy expenditure by indirect calorimetry. Female EC CD36°/LDLR° mice have reduced atherosclerosis. Taken together, these data support a significant role for EC CD36 in systemic metabolism and reveal sex-specific impact on atherosclerosis and energy substrate use.

Impact of a CD36 inhibitor on Porphyromonas gingivalis mediated atherosclerosis.

OBJECTIVE: To determine if AP5055 drug, an inhibitor of CD36, prevents the increase in Porphyromonas gingivalis (P. gingivalis) mediated atherosclerosis in low-density lipoprotein receptor knockout (LDLR KO) mice by targeting CD36. METHODS: Male LDLR KO mice were infected with P. gingivalis by oral lavage to induce periodontal disease and fed a western diet to induce atherosclerosis. Mice were treated with the CD36 inhibitor, AP5055 (1 mg/kg), or vehicle (1% DMSO). Aortae were dissected and stained with oil red-O for morphometric analysis; blood/plasma was collected to determine markers of inflammation by cytokine array and cholesterol levels. P. gingivalis-induced bone loss in mandibles was assessed using micro-CT. P. gingivalis lipopolysaccharide stimulated nuclear factor-kappa B (NF-κB) activity was measured using a reporter gene (secreted alkaline phosphatase) assay in AP5055 treated or untreated RAW-Blue macrophages. RESULTS: Isolated aortae showed a significant decrease in lesion area in the AP5055 treated group as compared to the control group. Mechanistically, in vitro analysis demonstrated that AP5055 inhibited NF-κB activity. Cytokine array showed a decrease in the expression of pro-inflammatory cytokines and decreased levels of plasma cholesterol in AP5055 treated mice. Micro-CT measurements of bone loss were not significant between the two groups. CONCLUSION: CD36 inhibitor AP5055 abrogates atherosclerotic lesion burden associated with periodontal disease, accompanied by a reduction in markers of inflammation. These experiments may support the development of drugs targeting CD36 for human disease.

Circulating CD36 is increased in hyperlipidemic mice: Cellular sources and triggers of release.

CD36 is a multifunctional transmembrane glycoprotein abundantly expressed in several cell types. Recent studies have identified CD36 in circulation (cCD36) in several chronic inflammatory diseases, including type 2 diabetes and chronic kidney disease, and proposed cCD36 to be a biomarker of disease activity. Whether cCD36 is present in hyperlipidemia, a condition characterized by oxidative stress and low-grade inflammation, is not known. In addition, the cellular origin of cCD36 and triggers of CD36 release have not been elucidated. We now demonstrate that plasma cCD36 level is increased in hyperlipidemic ApoE-/- and Ldlr-/- mice. Using several cell-specific CD36 knockout mice, we showed that multiple cell types contribute to cCD36 generation in hyperlipidemic conditions, with a particularly strong contribution from endothelial cells. In vitro studies have demonstrated that oxidized phospholipids, ligands for CD36 (oxPCCD36), which are known to accumulate in circulation in hyperlipidemia, induce a robust release of CD36 from several cell types. In vivo studies have demonstrated CD36 release into the circulation of WT mice in response to tail-vein injection of oxPCCD36. These findings document the presence of cCD36 in hyperlipidemia and identify a link between cCD36 and oxidized phospholipids generated under oxidative stress and low-grade inflammation associated with hyperlipidemia.

Surgically accelerated orthodontic techniques and periodontal response: a systematic review.

BACKGROUND: Reduction in orthodontic treatment time is gaining popularity due to patient demands. Several new techniques of acceleratory orthodontic treatment have been introduced to effectively treat the malocclusion in a shorter time period with minimal adverse effects. OBJECTIVE: The objective of this systematic review is to critically evaluate the potential effect of accelerated surgically assisted orthodontic techniques on periodontal tissues. MATERIALS AND METHODS: Electronic databases used to perform the search were Medline (Ovid), EMBASE, PubMed, Scopus, Cochrane, Google Scholar, and hand searching of the literature was also performed. SELECTION CRITERIA: Only randomized control trials (RCTs) that assessed the relationship between accelerated surgically assisted orthodontic techniques and its effects on periodontium were included. DATA COLLECTION AND ANALYSIS: The Joanna Briggs Institute (JBI) critical appraisal checklist tool (2016) was used to assess the finally selected studies. Among these studies, five evaluated corticotomy-facilitated orthodontics, two tested accelerated tooth movement with piezocision, one compared corticotomy-facilitated orthodontics with piezocision, and one studied the effects of periodontally accelerated osteogenic orthodontics. The duration of these studies was relatively short and had moderate to high risk of bias. RESULTS: Literature search identified 225 records from 5 databases and 50 articles from the partial grey literature (Google scholar) search. Finally, nine eligible RCTs were included in the review. LIMITATIONS: Most of the included studies were of a high risk of bias due to high experimental heterogeneity and small sample size. Long-term follow-up of the periodontal response to these interventions was also lacking. CONCLUSIONS: There is an absence of evidence considering the lack of long-term follow-up and small sample size therefore, the results of this review should be carefully interpreted. IMPLICATIONS: Due to the need for more studies with less risk of bias, these techniques should be implemented in dental practice with caution. With stronger evidence, the study may be confirmed to provide quicker desired results for orthodontic patients. REGISTRATION: This study protocol was not registered. FUNDING: No funding was obtained for this systematic review.

Loricrin downregulation and epithelial-related disorders: a systematic review.

Loricrin downregulation has been associated with age-related changes as well as inherited and inflammatory skin diseases. We hypothesize that changes in loricrin could be more related to altered barrier function and consequently disorders that affect epithelial cells, such as psoriasis, atopic dermatitis (AD), erythrokeratoderma, loricrin keratoderma (LK) and periodontitis. The aim of this review is to summarize what is known about the association between loricrin downregulation and epithelial-related disorders (ERDs). A search was performed on the following databases: Medline, Cochrane Library, PubMed, EMBASE, Lilacs, Scopus and Google Scholar, resulting in 16 included articles. Loricrin keratoderma was the ERD most frequently associated with loricrin mutations (730insG, 709insC and 578insG; 5/7 cases - 71.44 %). Atopic dermatitis was the ERD most frequently associated with loricrin downregulation (2/7 cases - 28.6 %). Mutilating palmoplantar keratoderma, progressive symmetrical erythrokeratoderma and a new type of erythrokeratoderma were not associated with any mutations. At the gene level, periodontitis patients showed the highest decrease (-6.89x), followed by AD (-6.5x) and psoriasis patients (-0.5x). In summary, loricrin mutation and downregulation were associated with several ERDs. The diversity in disease presentation is likely related to whether there is a total loss of loricrin, mislocalization and/or if the mutant form of loricrin causes dysfunction of other proteins and/or changes in cornification.

Neointimal hyperplasia: are fatty acid transport proteins a new therapeutic target?

PURPOSE OF REVIEW: High-fat diets contribute to hyperlipidemia and dysregulated metabolism underlying insulin resistant states and cardiovascular diseases. Neointimal hyperplasia is a significant resulting morbidity. Increased fatty acid (FA) levels lead to dysfunctional endothelium, defined as activated, proinflammatory and prothrombotic. The purpose of this review is to assess the recent literature on the emerging concept that uptake of FA into many tissues is regulated at the endothelial level, and this in turn contributes to endothelial dysfunction, an initiating factor in insulin resistant states, atherosclerosis and neointimal hyperplasia. RECENT FINDINGS: Studies support the role of endothelial FA uptake proteins as an additional level of regulation in tissue FA uptake. These proteins include CD36, FA transport proteins, FA-binding proteins and caveolin-1. In many cases, inappropriate expression of these proteins can result in a change in FA and glucose uptake, storage and utilization. Accumulation of plasma FA is one mechanism by which alterations in expression of FA uptake proteins can lead to endothelial dysfunction; changes in tissue substrate metabolism leading to inflammation are also implicated. SUMMARY: Identification of the critical players and regulators can lead to therapeutic targeting to reduce endothelial dysfunction and sequela such as insulin resistance and neointimal hyperplasia.