Periodontitis induced by Porphyromonas gingivalis drives periodontal microbiota dysbiosis and insulin resistance via an impaired adaptive immune response

Porphyromonas gingivalis, a Long-Range Pathogen: Systemic Impact and Therapeutic Implications

Periodontitis is an inflammatory disease associated with a dysbiosis of the oral flora characterized by a chronic sustained inflammation leading to destruction of tooth-supporting tissues. Over the last decade, an association between periodontitis and systemic disorders such as cardiovascular diseases, rheumatoid arthritis and obesity has been demonstrated. The role of periodontal pathogens, notably Porphyromonas gingivalis (P. gingivalis), in the onset or exacerbation of systemic diseases has been proposed. P. gingivalis expresses several virulence factors that promote its survival, spreading, and sustaining systemic inflammation. Recently, the impact of periodontitis on gut dysbiosis has also been suggested as a potential mechanism underlying the systemic influence of periodontitis. New therapeutic strategies for periodontitis and other dysbiotic conditions, including the use of beneficial microbes to restore healthy microbial flora, may pave the way to improved therapeutic outcomes and more thorough patient management.

A Simplified and Effective Method for Generation of Experimental Murine Periodontitis Model

Periodontitis, a common disease that can lead to bone destruction, periodontal attachment loss, and tooth loss, is the major cause for oral tissue engineering. Experimental periodontitis is a suitable disease-model for studying bone regeneration and the potential therapeutic role of biomaterials on periodontal tissue engineering, as this in vivo model could be employed to mimic the natural host response under bacteria-caused oral pathological environments. Although large animals with ligature-induced periodontitis have mostly been used for experiments, a mouse model is a better choice for several reasons. Inserting ligature threads through the interproximal space between the teeth is the key step in establishing a periodontitis model, and it is easy to achieve in large animals, but difficult in mice due to the limited operating space. In this work, we provide a new and proven approach for periodontitis induction in mice using C+ nickel-titanium root canal files and stainless-steel ligature wires. The validity of this method was assessed by evaluating alveolar bone loss via micro-CT and detecting periodontal inflammation by histological staining and qPCR after the treatments. Progressive alveolar bone loss was observed from day 3 after the ligature-placement. Infiltration and accumulation of F4/80+ macrophage was also detected. In accordance with the histological results, there was upregulation of the expression levels of the inflammatory genes Il1β, Tnf-α, and Il6 in gingival tissues isolated from the ligation sites. Our results suggest that this novel method could resolve the difficulty of ligature-placement in mice and consequently contribute to further use of mouse models for studying the pathological mechanisms of periodontitis and developing potential periodontal tissue regeneration strategies. C+ files, which are made of nickel-titanium, are tough, elastic, and sufficiently thin to pass through the interproximal space between the teeth after pre-bending to form an appropriate angle, thus providing an access for ligature wire insertion. As a common tool in the dental clinic, it is familiar to researchers of oral biology, and can provide the feasibility for wide application of our method.

Comparative Microbiological and Whole-Genome Analysis of Staphylococcus aureus Populations in the Oro-Nasal Cavities, Skin and Diabetic Foot Ulcers of Patients With Type 2 Diabetes Reveals a Possible Oro-Nasal Reservoir for Ulcer Infection

Patients with type 2 diabetes are at higher risk for periodontal disease and diabetic foot ulcer infections (DFUIs), the latter of which are predominantly caused by staphylococcal bacteria. Staphylococci have also been detected in the mouth, nose and gums (the oro-nasal cavity) of patients with periodontal disease and can move between the mouth and nose. The present study investigated if the oro-nasal cavity and/or periodontal pockets (PPs) in diseased gum tissue can provide a microbial reservoir for DFUIs. Eighteen patients with type 2 diabetes and at least three natural teeth (13 patients with ulcers and 5 patients without ulcers) underwent non-invasive microbiological sampling of PP, oro-nasal, skin and ulcer sites. Staphylococci were recovered using selective chromogenic agar, definitively identified and subjected to DNA microarray profiling, whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Staphylococcus aureus and Staphylococcus epidermidis were recovered from both the oro-nasal and ulcer sites of 6/13 and 5/13 patients with ulcers, respectively. Molecular typing based on the staphylococcal protein A (spa) gene and DNA microarray profiling indicated that for each patient investigated, S. aureus strains from oro-nasal and ulcer sites were identical. Comparative cgMLST confirmed that isolates from multiple anatomical sites of each individual investigated grouped into closely related, patient-distinct clusters (Clusters 1-7). Isolates belonging to the same cluster exhibited an average of 2.9 allelic differences (range 0-11). In contrast, reference genomes downloaded from GenBank selected as representatives of each sequence type identified in the present study exhibited an average of 227 allelic differences from the most closely related isolate within each cluster.

Solidago virgaurea L. Plant Extract Targeted Against Candida albicans to Reduce Oral Microbial Biomass: a Double Blind Randomized Trial on Healthy Adults

Oral microbiome plays an important part on oral health and endogenous bacteria and fungi should not be eradicated. However, their proliferation must be controlled by oral hygiene care. In vitro, Solidago virgaurea ssp. virgaurea L. (SV) plant extract inhibits the adherence and hyphal formation of a fungus, Candida albicans. It reduces the biomass of Candida-bacterial biofilms but not fungal or bacterial growth. Unlike chemical antiseptics, like triclosan and chlorhexidine for instance, SV is a plant extract easily biodegradable. The purpose of this study was to assess the in vivo effectiveness of SV extract in reducing oral biomass. A randomized, double-blind clinical study, with dental plaque evaluation designed to assess the effectiveness of a fluorinated toothpaste containing SV (Bucovia™, Givaudan, Vernier, Switzerland) was conducted. Sixty-six subjects (SV group n = 33 vs. control n = 33) brushed their teeth twice a day for a 4-week period. Supragingival dental plaque was sampled. Total bacterial load (broad spectral bacterial quantitative Polymerase Chain Reaction (qPCR)), C. albicans and seven bacterial species were quantified by qPCR. In the Intervention group, there was a decrease of Total bacterial load (ΔD0D28 p = 0.005 and ΔD14D28 p = 0.026), Streptococcus mutans (ΔD0D14 p = 0.024) and C. albicans (ΔD0D28 p = 0.022). In the Control group Total bacterial load tended to decrease from baseline to day 28 (ΔD0D28 p = 0.062 and ΔD14D28 p = 0.009). Plaque Index and Gingival Index improved in both groups.

Porphyromonas gingivalis Induces Insulin Resistance by Increasing BCAA Levels in Mice

Insulin resistance is one of the critical pathogeneses of type 2 diabetes mellitus (T2DM). Elevated levels of plasma branched-chain amino acids (BCAAs) are associated with insulin resistance. Recent studies have demonstrated the role of Porphyromonas gingivalis in the development of insulin resistance. However, the mechanisms by which P. gingivalis induces insulin resistance are still unclear. The purpose of this study was to investigate whether P. gingivalis induces insulin resistance through BCAA biosynthesis. We established a murine model of periodontitis by infecting mice with P. gingivalis. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs were measured. A P. gingivalis BCAA aminotransferase-deficient strain (∆bcat) was constructed, and its kinetic growth, biofilm formation, and in vivo colonization were compared with its wild-type strain. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs of the mice infected with either wild-type strain or ∆bcat strain were further measured. We found that periodontal infection with P. gingivalis significantly upregulated the plasma level of BCAAs and aggravated the high-fat diet (HFD)-induced insulin resistance. Bcat deletion did not alter the growth, biofilm formation, and in vivo colonization of P. gingivalis. More important, the ∆bcat strain was unable to upregulate the plasma level of BCAAs and induce insulin resistance in HFD-fed mice. These findings suggest that the BCAA biosynthesis of P. gingivalis plays a critical role in the development of insulin resistance in the HFD-fed mice. The BCAA biosynthesis pathways may provide a potential target for the disruption of linkage between periodontitis and T2DM.

Odontogenic infection by Porphyromonas gingivalis exacerbates fibrosis in NASH via hepatic stellate cell activation

Odontogenic infection of Porphyromonas gingivalis (P.g.), a major periodontal pathogen, exacerbates pathological progression of non-alcoholic steatohepatitis (NASH). In this study, we aimed to clarify the detailed mechanism in which P.g. induced hepatic stellate cells (HSCs; key effector cells in liver fibrosis) activation. In the liver of high fat diet-induced NASH mouse model with P.g. odontogenic infection, immunolocalization of P.g. was detected. The number of hepatic crown-like structure, which was macrophage aggregation and related to liver fibrosis, was drastically increased and fibrosis area was also increased through upregulating immunoexpression of Phosphorylated Smad2 (key signaling molecule of TGF-β1) and Galectin-3. P.g.-secreted trypsin-like enzyme [gingipain; an activator of protease-activated receptor 2 (PAR2)] stimulated HSC proliferation and differentiation through Smad and ERK signaling induced by TGF-β1 produced from HSCs with P.g.-infection. Further, Galectin-3 produced from HSCs with P.g. infection and P.g.-derived LPS/lipoprotein stimulation stabilized TGFβ-receptor II resulting in increasing sensitivity for TGF-β1, finally leading to HSC differentiation via activating Smad and ERK signaling. In addition to them, hepatocytes (main component cells of liver) contributed to HSC activation through TGF-β1 and Galectin-3 production in paracrine manner. Collectively, P.g.-odontogenic infection exacerbates fibrosis of NASH by HSC activation through TGF-β1 and Gal-3 production from HSCs and hepatocytes.

Type 2 diabetes influences bacterial tissue compartmentalisation in human obesity

Visceral obesity is a key risk factor for type 2 diabetes (T2D). Whereas gut dysbiosis appears to be instrumental for this relationship, whether gut-associated signatures translocate to extra-intestinal tissues and how this affects host metabolism remain elusive. Here we provide a comparative analysis of the microbial profile found in plasma, liver and in three distinct adipose tissues of individuals with morbid obesity. We explored how these tissue microbial signatures vary between individuals with normoglycaemia and those with T2D that were matched for body mass index. We identified tissue-specific signatures with higher bacterial load in the liver and omental adipose tissue. Gut commensals, but also environmental bacteria, showed tissue- and T2D-specific compartmentalisation. T2D signatures were most evident in mesenteric adipose tissue, in which individuals with diabetes displayed reduced bacterial diversity concomitant with fewer Gram-positive bacteria, such as Faecalibacterium, as opposed to enhanced levels of typically opportunistic Gram-negative Enterobacteriaceae. Plasma samples of individuals with diabetes were similarly enriched in Enterobacteriaceae, including the pathobiont Escherichia-Shigella. Our work provides evidence for the presence of selective plasma and tissue microbial signatures in individuals with severe obesity and identifies new potential microbial targets and biomarkers of T2D.

Gastric and duodenal ulcers, periodontal disease, and risk of bladder cancer in the Health Professionals Follow-up Study

PURPOSE

Studies suggest that peptic ulcer and periodontal disease are positively associated with bladder cancer risk. These two factors are likely to share common biologic mechanisms such as inflammation and dysbiosis. We examined the joint association of peptic ulcer (gastric/duodenal) and periodontal disease on bladder cancer risk.

METHODS

We conducted a prospective analysis among 45,185 men (563 invasive bladder cancer cases) in the Health Professionals Follow-Up Study (follow-up 1986-2016). History of ulcer and periodontal disease was self-reported at baseline and updated during the follow-up. Cox proportional hazards models estimated hazard ratio (HR) and 95% confidence interval (CI) for the joint associations of ulcers (gastric, duodenal) and periodontal disease, adjusting for age and other potential confounders. We tested for interaction using the Wald test for product terms.

RESULTS

Compared with men having no history of ulcer and periodontal disease, men with a history of peptic ulcer only (HR 1.22, 95% CI 0.90-1.66) and men with a history of periodontal disease only (HR 1.19, 95% CI 0.98-1.46) were associated with higher risk of invasive bladder cancer. The highest bladder cancer risk was observed in men with a history of both peptic ulcer and periodontal disease (HR 1.52, 95% CI 1.05-2.20). Similar results were found when we stratified by ulcer types. The interactions between ulcer and periodontal disease were not statistically significant for all ulcer types (p-interaction ≥ 0.59).

CONCLUSION

We did not find sufficient evidence for interaction between gastric/duodenal ulcers and periodontal disease on bladder cancer risk.

[Expression of high mobility group protein B1 in periodontal tissues and its association with hepatic lipid metabolism in diabetic rats with periodontitis]

OBJECTIVE

To investigate the expression of high mobility group box-1 protein (HMGB1) and its downstream products, receptor for advanced glycation end-products (RAGE) and tumor necrosis factor-α (TNF-α), in periodontal tissues of diabetic rats with periodontitis, and explore the association of HMGB1 with hepatic lipid metabolism.

METHODS

Immunohistochemical staining was used to detect the expression of HMGB1, RAGE and TNF-α in the periodontal tissues in rat models of diabetes mellitus (DM), periodontitis (CP), and diabetic periodontitis (DM + CP). The serum levels of the indicators of lipid metabolism and biochemical indexes of liver damage were detected by spectroscopy.

RESULTS

The expressions of HMGB1 and RAGE in the periodontal tissues were significantly higher in DM group than in the control group, but the expression of TNF-α showed no significant difference among the groups. In CP group, the expressions of HMGB1 and TNF-α were significantly higher than those in the control group, and the expression of RAGE was comparable with that in the control group but significantly lower than that in DM and DM+CP group. The expressions of HMGB1, RAGE and TNF-α were all significantly higher in DM+CP group than in the control group. Compared with the control rats, the rats in DM, CP, DM+CP group all showed abnormal hepatic lipid metabolism with significantly elevated serum ALT levels.

CONCLUSIONS

HMGB1 and RAGE participate in the inflammation of the periodontal tissues in diabetic rats. Diabetes leads to elevated expression of HMGB1 in the periodontal tissues. Both periodontitis and hyperglycemia contribute to liver metabolic dysfunction. HMGB1- RAGE provides clues in the study of signaling pathways underlying the mutual susceptibility of diabetes and periodontitis.

Comparative Microbiological and Whole-Genome Analysis of Staphylococcus aureus Populations in the Oro-Nasal Cavities, Skin and Diabetic Foot Ulcers of Patients With Type 2 Diabetes Reveals a Possible Oro-Nasal Reservoir for Ulcer Infection

Patients with type 2 diabetes are at higher risk for periodontal disease and diabetic foot ulcer infections (DFUIs), the latter of which are predominantly caused by staphylococcal bacteria. Staphylococci have also been detected in the mouth, nose and gums (the oro-nasal cavity) of patients with periodontal disease and can move between the mouth and nose. The present study investigated if the oro-nasal cavity and/or periodontal pockets (PPs) in diseased gum tissue can provide a microbial reservoir for DFUIs. Eighteen patients with type 2 diabetes and at least three natural teeth (13 patients with ulcers and 5 patients without ulcers) underwent non-invasive microbiological sampling of PP, oro-nasal, skin and ulcer sites. Staphylococci were recovered using selective chromogenic agar, definitively identified and subjected to DNA microarray profiling, whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Staphylococcus aureus and Staphylococcus epidermidis were recovered from both the oro-nasal and ulcer sites of 6/13 and 5/13 patients with ulcers, respectively. Molecular typing based on the staphylococcal protein A (spa) gene and DNA microarray profiling indicated that for each patient investigated, S. aureus strains from oro-nasal and ulcer sites were identical. Comparative cgMLST confirmed that isolates from multiple anatomical sites of each individual investigated grouped into closely related, patient-distinct clusters (Clusters 1-7). Isolates belonging to the same cluster exhibited an average of 2.9 allelic differences (range 0-11). In contrast, reference genomes downloaded from GenBank selected as representatives of each sequence type identified in the present study exhibited an average of 227 allelic differences from the most closely related isolate within each cluster.

Implication of Porphyromonas gingivalis in colitis and homeostasis of intestinal epithelium

Emerging evidences have reported that periodontitis can be a risk factor for the pathogenesis of various systemic diseases. Porphyromonas gingivalis (Pg), one of the crucial pathogens in chronic periodontitis, has been spotlighted as a potential cause for the promotion and acceleration of periodontitis-associated systemic disorders. To investigate the association between Pg and intestinal disease or homeostasis, we treated Pg-derived lipopolysaccharide (LPS) in murine colitis model or intestinal organoid, respectively. Pg-derived LPS (Pg LPS) was administrated into chemically induced murine colitis model and disease symptoms were monitored compared with the infusion of LPS derived from E. coli (Ec LPS). Organoids isolated and cultured from mouse small intestine were treated with Pg or Ec LPS and further analyzed for the generation and composition of organoids. In vivo observations demonstrated that both Pg and Ec LPS exerted slight protective effects against murine colitis. Pg LPS did not affect the generation and growth of intestinal epithelial organoids. Among subtypes of epithelial cells, markers for stem cells, goblet cells or Paneth cells were changed in response to Pg LPS. Taken together, these results indicate that Pg LPS leads to partial improvement in colitis and that its treatment does not significantly affect the self-organization of intestinal organoids but may regulate the epithelial composition.

Oral microbiota-induced periodontitis: a new risk factor of metabolic diseases

It has recently become evident that the periodontium (gingiva, desmodontal ligament, cementum and alveolar bone) and the associated microbiota play a pivotal role in regulating human health and diseases. The oral cavity is the second largest microbiota in the body with around 500 different bacterial species identified today. When disruption of oral cavity and dysbiosis occur, the proportion of strict anaerobic Gram-negative bacteria is then increased. Patients with periodontitis present 27 to 53% more risk to develop diabetes than the control population suggesting that periodontitis is an aggravating factor in the incidence of diabetes. Moreover, dysbiosis of oral microbiota is involved in both periodontal and metabolic disorders (cardiovascular diseases, dyslipidaemia …). The oral diabetic dysbiosis is characterized by a specific bacteria Porphyromonas, which is highly expressed in periodontal diseases and could exacerbate insulin resistance. In this review, we will address the nature of the oral microbiota and how it affects systemic pathologies with a bidirectional interaction. We also propose that using prebiotics like Akkermansia muciniphila may influence oral microbiota as novel therapeutic strategies. The discovery of the implication of oral microbiota for the control of metabolic diseases could be a new way for personalized medicine.

The gut microbiota to the brain axis in the metabolic control

The regulation of glycemia is under a tight neuronal detection of glucose levels performed by the gut-brain axis and an efficient efferent neuronal message sent to the peripheral organs, as the pancreas to induce insulin and inhibit glucagon secretions. The neuronal detection of glucose levels is performed by the autonomic nervous system including the enteric nervous system and the vagus nerve innervating the gastro-intestinal tractus, from the mouth to the anus. A dysregulation of this detection leads to the one of the most important current health issue around the world i.e. diabetes mellitus. Furthemore, the consequences of diabetes mellitus on neuronal homeostasis and activities participate to the aggravation of the disease establishing a viscious circle. Prokaryotic cells as bacteria, reside in our gut. The strong relationship between prokaryotic cells and our eukaryotic cells has been established long ago, and prokaryotic and eukaryotic cells in our body have evolved synbiotically. For the last decades, studies demonstrated the critical role of the gut microbiota on the metabolic control and how its shift can induce diseases such as diabetes. Despite an important increase of knowledge, few is known about 1) how the gut microbiota influences the neuronal detection of glucose and 2) how the diabetes mellitus-induced gut microbiota shift observed participates to the alterations of autonomic nervous system and the gut-brain axis activity.

PgRsp Is a Novel Redox-Sensing Transcription Regulator Essential for Porphyromonas gingivalis Virulence

Porphyromonas gingivalis is one of the etiological agents of chronic periodontitis. Both heme and oxidative stress impact expression of genes responsible for its survival and virulence. Previously we showed that P. gingivalis ferric uptake regulator homolog affects expression of a gene encoding a putative Crp/Fnr superfamily member, termed P. gingivalis redox-sensing protein (PgRsp). Although PgRsp binds heme and shows the highest similarity to proteins assigned to the CooA family, it could be a member of a novel, separate family of proteins with unknown function. Expression of the pgrsp gene is autoregulated and iron/heme dependent. Genes encoding proteins engaged in the oxidative stress response were upregulated in the pgrsp mutant (TO11) strain compared with the wild-type strain. The TO11 strain showed higher biomass production, biofilm formation, and coaggregation ability with Tannerella forsythia and Prevotella intermedia. We suggest that PgRsp may regulate production of virulence factors, proteases, Hmu heme acquisition system, and FimA protein. Moreover, we observed growth retardation of the TO11 strain under oxidative conditions and decreased survival ability of the mutant cells inside macrophages. We conclude that PgRsp protein may play a role in the oxidative stress response using heme as a ligand for sensing changes in redox status, thus regulating the alternative pathway of the oxidative stress response alongside OxyR.

The Connection of Periodontal Disease and Diabetes Mellitus: The Role of Matrix Metalloproteinases and Oxidative Stress

Diabetes mellitus, a chronic disease considered by the World Health Organization to be an epidemic, is now recognized as one of the factors behind the onset of periodontal disease. The connection between periodontal disease, which is an irreversible inflammatory disease of the supporting tissue of the teeth, and systemic diseases is reflected in the existence of common risk factors, subgingival dental biofilm, as a constant source of proinflamma-tory cytokines synthesized intensely in inflammatory periodontium. Diabetes mellitus leads to increased oxidative stress in periodontal tissues causing worsening of the disease and periodontopathy exacerbates deficiency of pancreatic β-cells. The most important role in primary inflammatory response in the pathogenesis of periodontopathy is played by neutrophils. Neutrophils cause periodontium destruction by the release of enzymes (matrix metalloproteinases), cytotoxic substances (free radicals, reactive oxygen and nitrogen species) and the expression of membrane receptors. Matrix metalloproteinases within the “protease network” are critical to many physiological and pathological processes, including immunity, inflammation, bone resorption and wound healing. Matrix metalloproteinases levels are elevated in patients with metabolic syndrome and diabetes mellitus, which may contribute to more frequent complications. In this paper, the review of available literature data shows the correlation between periodontal disease and diabetes mellitus, as well as the role of matrix metalloproteinases and oxidative stress in these. In this regard, determining the value of matrix metalloproteinases may be helpful in the diagnosis of periodontal disease complicated by diabetes mellitus. Also, the parameters of oxidative stress could help to clarify the mechanisms of pathogenesis and etiology of periodontal disease, or indicate the potential benefit of antioxidant supplementation in these individuals. As the role of matrix metalloproteinases has not been fully clarified in the pathogenesis of periodontopathy, additional studies will be needed to indicate their importance.

Broad-Spectrum Antibacterial Effects of Human Adipose-Derived Stromal Cells

Introduction

Many pathological conditions may benefit from cell therapy using mesenchymal stromal cells, particularly from adipose tissue (ASCs). Cells may be grafted in an environment with a remnant polymicrobial component. The aim is to investigate the behavior of ASCs when brought in contact with a large panel of bacteria.

Materials and Methods

Carboxyfluorescein-labelled bacterial interaction with ASCs was followed by confocal time-lapse microscopy. Costaining with LAMP-1 was also analyzed. Viability of 4 gram-negative and 4 gram-positive bacterial strains after 6 h of coculture with ASCs was assessed by agar colony counting and by flow cytometry using SYTO-62®/propidium iodide (PI) for membrane permeabilization and DiOC6 for depolarization. A murine model of periodontitis was used to assess in vivo antibacterial capacities of ASCs.

Results

A significant increase of PI-positive events for all bacterial strains and an increase of the DiOC6 signal were obtained after contact with ASCs. The number of CFU was also significantly decreased for several bacterial strains. 0.4 μm transwell systems illustrated the necessary direct contact to induce maximal bacterial membrane damages. Some bacteria were observed into phagolysosomes, confirming macrophage-like properties of ASCs. In vivo, the bacterial load was significantly lower in the ASC-grafted side compared to the control.

Conclusion

Our results highlight for the first time a broad range of antibacterial actions of ASCs, by phagocytosis, secretion of oxygenated free radicals and antibacterial molecules. These data are in line with the development of new therapeutic strategies based on ASC transplantation, appropriated in immune-dysbiotic tissue context such as periodontitis or chronic wounds.

Periodontal Pathogens as Risk Factors of Cardiovascular Diseases, Diabetes, Rheumatoid Arthritis, Cancer, and Chronic Obstructive Pulmonary Disease-Is There Cause for Consideration?

Cardiovascular diseases, chronic obstructive pulmonary diseases, diabetes, rheumatoid arthritis, and cancer are the most common noncommunicable diseases (NCDs). These NCDs share risk factors with periodontal disease (PD), a preventable risk factor linked to lifestyle. The discussion regarding the association between these chronic diseases is more complex. There is still a significant knowledge gap particularly of the causal relationship between PD and NCDs. In this paper, we present fundamental knowledge of the mechanisms and roles of putative periodontal bacteria to gather several hypotheses, evidence that clinical studies thus far have not produced. Although the causal hypotheses are not yet clearly established on a biological basis, prevention and prophylactic measures are recommended to prevent even the possibility of such potential risk factors.

Porphyromonas gingivalis induces depression via downregulating p75NTR-mediated BDNF maturation in astrocytes

Many cross-sectional epidemiological studies have shown the incidence of periodontitis is positive correlated with that of depression. However, their causal relationship and underlying mechanism are largely unknown. Porphyromonas gingivalis (Pg) is the main pathogen for periodontitis. Employing female mice treated with Pg every other day for 4 weeks, we found that Pg-mice showed obvious depression-like behavior, an increased number of activated astrocytes and decreased levels of mature brain derived neurotrophic factor (BDNF) and astrocytic p75NTR in the hippocampus. Both hippocampal injection of BDNF and overexpression of p75NTR in astrocytes alleviated Pg-induced depression-like behavior in mice. Moreover, Pg-lipopolysaccharides (LPS) generated similar phenotypes, which were reversed by the TLR-4 inhibitor TAK242. Our results suggest that Pg-LPS decreases the level of astrocytic p75NTR and then downregulates BDNF maturation, leading to depression-like behavior in mice. Our study provides the first evidence that Pg is a modifiable risk factor for depression and uncovers a novel therapeutic target for the treatment of depression.

[Potential application of human microbiomes in the diagnosis and treatment of type 2 diabetes mellitus]

Human microbiome refers to the total microorganism genetic information of human body surface and internal, which is closely related to human health and disease. Oral and gut microbiomes are the most diverse microbial communities, which can interact and play a role in the development of the disease, and can reflect the health and disease state in real time. Type 2 diabetes mellitus is a metabolic disorder caused by both genetic and environmental factors. Recent research has shown a link between microbes and diabetes. This article reviewed the latest research on the changes of oral and gut microbiomes in type 2 diabetes mellitus patients, which expects to provide a reference for exploring the development of the disease model for prediction, diagnosis and prognosis of type 2 diabetes mellitus based on human microbiome characteristics.

Parkinson's Disease: A Systemic Inflammatory Disease Accompanied by Bacterial Inflammagens

Parkinson’s disease (PD) is a well-known neurodegenerative disease with a strong association established with systemic inflammation. Recently, the role of the gingipain protease group from Porphyromonas gingivalis was implicated in Alzheimer’s disease and here we present evidence, using a fluorescent antibody to detect gingipain R1 (RgpA), of its presence in a PD population. To further elucidate the action of this gingipain, as well as the action of the lipopolysaccharide (LPS) from P. gingivalis, low concentrations of recombinant RgpA and LPS were added to purified fluorescent fibrinogen. We also substantiate previous findings regarding PD by emphasizing the presence of systemic inflammation via multiplex cytokine analysis, and demonstrate hypercoagulation using thromboelastography (TEG), confocal and electron microscopy. Biomarker analysis confirmed significantly increased levels of circulating proinflammatory cytokines. In our PD and control blood analysis, our results show increased hypercoagulation, the presence of amyloid formation in plasma, and profound ultrastructural changes to platelets. Our laboratory analysis of purified fibrinogen with added RgpA, and/or LPS, showed preliminary data with regards to the actions of the protease and the bacterial membrane inflammagen on plasma proteins, to better understand the nature of established PD.

Methylene Blue-Mediated Photodynamic Therapy Induces Macrophage Apoptosis via ROS and Reduces Bone Resorption in Periodontitis

Aim

To investigate whether methylene blue-mediated photodynamic therapy (MB-PDT) can affect the "fate" of macrophages in vitro or in periodontitis tissues and to explore the potential mechanism.

Methods

For in vitro treatments, THP-1 macrophages were divided into three experimental groups: C/control, no treatment; MB, methylene blue treatment; and MB-PDT, MB and laser irradiation treatment. Then, apoptosis and apoptosis-related proteins were detected in each group. For in vivo treatments, periodontitis was ligature-induced in the first molars of the bilateral maxilla in 12 Sprague Dawley (SD) rats. After six weeks, the ligatures were removed and all the induced molars underwent scaling and root planning (SRP). Then, the rats were divided into three groups according to the following treatments: SRP, saline solution; MB, phenothiazinium dye; and MB-PDT, MB and laser irradiation. Apoptotic macrophages, inflammation levels, and alveolar bone resorption in the periodontal tissues of rats were analyzed in each group.

Results

In vitro, flow cytometry analysis demonstrated that 10 μM MB and 40 J/cm² laser irradiation maximized the apoptosis rate (34.74%) in macrophages. Fluorescence probe and Western blot analyses showed that MB-PDT induced macrophage apoptosis via reactive oxygen species (ROS) and the mitochondrial-dependent apoptotic pathway. Conversely, the addition of exogenous antioxidant glutathione (GSH) and the pan-caspase inhibitor Z-VAD-FMK markedly reduced the apoptotic response in macrophages. In vivo, immunohistochemistry, histology, radiographic, and molecular biology experiments revealed fewer infiltrated macrophages, less bone loss, and lower IL-1β and TNF-α levels in the MB-PDT group than in the SRP and MB groups (P < 0.05). Immunohistochemistry analysis also detected apoptotic macrophages in the MB-PDT group.

Conclusion

MB-PDT could induce macrophage apoptosis in vitro and in rats with periodontitis. This may be another way for MB-PDT to relieve periodontitis in addition to its antimicrobial effect. Meanwhile, MB-PDT induced apoptosis in THP-1 macrophages via the mitochondrial caspase pathway.

Porphyromonas gingivalis-derived lipopolysaccharide causes excessive hepatic lipid accumulation via activating NF-κB and JNK signaling pathways

BACKGROUND

Porphyromonas gingivalis is the main pathogen of periodontal disease affecting over half of the worldwide adult population. Recent studies have shown that P. gingivalis is related to the development of non-alcoholic fatty liver disease (NAFLD), a global major chronic liver disease, especially in developed countries. However, how P. gingivalis contributes to the pathogenesis of NAFLD has not been fully clarified. We aimed to conduct a preliminary exploration of the underlying mechanism of P. gingivalis infection in the development of NAFLD.

METHODS

Human hepatocellular cells HepG2 were incubated with/without oleic acid (OA) and tested for lipid accumulation upon stimulation by lipopolysaccharide (LPS) derived from P. gingivalis or Escherichia coli. Intracellular lipid droplet formation was analyzed and quantified by Oil Red O staining. The involvement of signaling pathway molecules and pro-inflammatory cytokines related to NF-κB and MAPKs were examined with Western blot and quantitative real-time PCR (qRT-PCR) analyses and further evaluated with inhibitor treatment and RNA interference.

RESULTS

HepG2 cells accumulated more intracellular lipids when stimulated with P. gingivalis LPS, as compared to cells treated with E. coli LPS or control. Further pathway analysis demonstrated that after stimulation with P. gingivalis LPS, cells displayed significantly upregulated MyD88 expression, increased phosphorylation of p65 and JNK, and more release of pro-inflammatory cytokines, such as IL-1, IL-8, and TNF-α. In addition, suppression of phosphorylation of p65 and JNK by inhibitors and RNA interference resulted in a reduction in lipid accumulation upon P. gingivalis LPS treatment.

CONCLUSIONS

These results suggest that P. gingivalis-derived LPS may contribute to intracellular lipid accumulation and inflammatory reaction of HepG2 cells via the activation of NF-κB and JNK signaling pathways. This study offers a possible explanation to the functional involvement of P. gingivalis infection in the pathological progression of NAFLD. These findings may help design new treatment strategies in NAFLD.

Blockade of Immune-Checkpoint B7-H4 and Lysine Demethylase 5B in Esophageal Squamous Cell Carcinoma Confers Protective Immunity against P. gingivalis Infection

Pathogens are capable of hijacking immune defense mechanisms, thereby creating a tolerogenic environment for hypermutated malignant cells that arise within the site of infection. Immune checkpoint-oriented immunotherapies have shown considerable promise. Equally important, the epigenetic reprogramming of an immune-evasive phenotype that activates the immune system in a synergistic manner can improve immunotherapy outcomes. These advances have led to combinations of epigenetic- and immune-based therapeutics. We previously demonstrated that Porphyromonas gingivalis isolated from esophageal squamous cell carcinoma (ESCC) lesions represents a major pathogen associated with this deadly disease. In this study, we examined the mechanisms associated with host immunity during P. gingivalis infection and demonstrated that experimentally infected ESCC responds by increasing the expression of B7-H4 and lysine demethylase 5B, which allowed subsequent in vivo analysis of the immunotherapeutic effects of anti-B7-H4 and histone demethylase inhibitors in models of chronic infection and immunity against xenografted human tumors. Using three different preclinical mouse models receiving combined therapy, we showed that mice mounted strong resistance against P. gingivalis infection and tumor challenge. This may have occurred via generation of a T cell-mediated response in the microenvironment and formation of immune memory. In ESCC subjects, coexpression of B7-H4 and KDM5B correlated more significantly with bacterial load than with the expression of either molecule alone. These results highlight the unique ability of P. gingivalis to evade immunity and define potential targets that can be exploited therapeutically to improve the control of P. gingivalis infection and the development of associated neoplasia.

Distal Consequences of Oral Inflammation

Periodontitis is an incredibly prevalent chronic inflammatory disease, which results in the destruction of tooth supporting structures. However, in addition to causing tooth and alveolar bone loss, this oral inflammatory disease has been shown to contribute to disease states and inflammatory pathology at sites distant from the oral cavity. Epidemiological and experimental studies have linked periodontitis to the development and/or exacerbation of a plethora of other chronic diseases ranging from rheumatoid arthritis to Alzheimer's disease. Such studies highlight how the inflammatory status of the oral cavity can have a profound impact on systemic health. In this review we discuss the disease states impacted by periodontitis and explore potential mechanisms whereby oral inflammation could promote loss of homeostasis at distant sites.

Lactobacillus helveticus SBT2171 upregulates the expression of β-defensin and ameliorates periodontal disease caused by Porphyromonas gingivalis

Antimicrobial peptides play important roles in the innate immune system of various organisms, and they may also be considered to prevent the organisms from infections. In particular, β-defensins, mainly produced in epithelial cells, are recognized as one of the major antimicrobial peptides in mammals, including humans. In this study, we showed that Lactobacillus helveticus SBT2171 (LH2171), one of the several species of lactic acid bacteria, upregulates the production of β-defensins in oral epithelial cells in vitro. Moreover, LH2171 reduced the increase of proinflammatory cytokine expression, induced by Porphyromonas gingivalis stimulation, in gingival epithelial cells. These data suggested that LH2171 suppresses P. gingivalis-induced inflammation by upregulating the expression of β-defensins in gingival epithelial cells. We subsequently investigated the effects of LH2171 in vivo and revealed that β-defensin expression was increased in the oral cavities of LH2171-fed mice. Furthermore, LH2171 decreased alveolar bone loss, gingival inflammation, and amounts of P. gingivalis-specific 16S ribosomal RNA in the gingiva of P. gingivalis-inoculated mice. Taken together, our results showed that LH2171 upregulates the expression of β-defensins in oral cavity, thereby decreasing the number of P. gingivalis consequently ameliorating the experimental periodontal disease.

Adhesion to pharyngeal epithelium and modulation of immune response: Lactobacillus salivarius AR809, a potential probiotic strain isolated from the human oral cavity

Microbiome modulators such as probiotics are known to modulate oral diseases. Very few probiotics are commercially available for use in the oral cavity. In this context, we selected human-origin Lactobacillus salivarius AR809 as a promising oropharyngeal probiotic and characterized its functional and immunomodulatory properties. Results demonstrated that AR809 could efficiently adhere to pharyngeal epithelial FaDu cells, antagonize Staphylococcus aureus, adapt to the oral environment, and modulate host innate immunity by inducing potentially protective effects. Particularly, AR809 diminished proinflammatory activity by enhancing the production of IL10 and inhibiting the expression of tumor necrosis factor-α, IL1B, inducible nitric oxide synthase, and RELA. Finally, we observed that AR809 grew efficiently when cultured in milk, suggesting that the preparation of a fermented milk product containing AR809 could be a practical way to administer this probiotic to humans. In conclusion, AR809 has high potential to adhere to the pharyngeal mucosa and could be applied in novel milk-based probiotic fermented food products.

Porphyromonas gingivalis experimentally induces periodontis and an anti-CCP2-associated arthritis in the rat

OBJECTIVES

Association between periodontal disease (PD) and rheumatoid arthritis (RA) has been extensively described, but direct evidence of causal involvement of PD in RA is missing. We investigated the priming role of oral Porphyromonas gingivalis (P. gingivalis) in PD and subsequent RA and we assessed biomarkers of bone resorption and arthritis development in rats.

METHODS

Lewis rats were orally exposed to either P. gingivalis, Prevotella intermedia or control gel for 1 month and then followed for 8 months. The onset and development of PD was assessed by serology, gingivitis severity and micro-CT (µCT). We investigated arthritis development using circulating proinflammatory markers, anticyclic citrullinated peptide (CCP), anticitrullinated protein antibody (ACPA), ankle histology and µCT.

RESULTS

PD was only observed in the P. gingivalis treated rats, as early as 1 month postexposure. Joint and systemic inflammation were detected only in the P. gingivalis group after 4 and 8 months. At 8 months, inflammatory cell infiltrate was observed in ankle joints and paralleled cortical erosions and overall cortical bone reduction. Furthermore, anti-CCP2 correlated with local and systemic bone loss.

CONCLUSIONS

In our long-term study, PD induced by oral exposure to P. gingivalis triggered seropositive arthritis, with systemic inflammation and bone erosions. This is the first in vivo demonstration of arthritis induced by oral priming with P. gingivalis.

Periodontal Disease: A Risk Factor for Diabetes and Cardiovascular Disease

Periodontitis is a chronic inflammatory disease, initiated by the presence of a bacterial biofilm, called dental plaque, which affects both the periodontal ligaments and bone surrounding teeth. In the last decades, several lines of evidence have supported the existence of a relationship between periodontitis and systemic health. For instance, as periodontitis acts within the same chronic inflammatory model seen in cardiovascular disease (CVD), or other disorders, such as diabetes, several studies have suggested the existence of a bi-directional link between periodontal health and these pathologies. For instance, people with diabetes are more susceptible to infections and are more likely to suffer from periodontitis than people without this syndrome. Analogously, it is now evident that cardiac disorders are worsened by periodontitis, both experimentally and in humans. For all these reasons, it is very plausible that preventing periodontitis has an impact on the onset or progression of CVD and diabetes. On these grounds, in this review, we have provided an updated account on the current knowledge concerning periodontal disease and the adverse effects exerted on the cardiovascular system health and diabetes, informing readers on the most recent preclinical studies and epidemiological evidence.

Periodontitis is associated with incident chronic liver disease-A population-based cohort study

BACKGROUND & AIMS

Chronic liver disease is a major health concern worldwide and the identification of novel modifiable risk factors may benefit subjects at risk. Few studies have analyzed periodontitis as a risk factor for liver complications. We studied whether periodontitis is associated with incident severe liver disease.

METHODS

The study comprised 6165 individuals without baseline liver disease who participated in the Finnish population-based Health 2000 Survey (BRIF8901) during 2000-2001, a nationally representative cohort. Follow-up was until 2013 for liver-related admissions, liver cancer and mortality from National Hospital Discharge, Finnish Cancer Registry and Causes of Death Register, Statistics Finland. Mild to moderate periodontitis was defined as ≥1 tooth with periodontal pocket ≥4 mm deep, and advanced periodontitis as ≥5 teeth with such pockets. Multiple confounders were considered.

RESULTS

A total of 79 subjects experienced a severe liver event during follow-up. When adjusted for age, sex and number of teeth, hazards ratios by Cox regression regarding incident severe liver disease were, for mild to moderate periodontitis, 2.12 (95% CI 0.98-4.58), and, for advanced periodontitis, 3.69 (95% CI 1.79-7.60). These risk estimates remained stable after additionally adjusting for alcohol use, smoking, metabolic risk, serum gamma-glutamyltransferase, dental-care habits, lifestyle and socioeconomic status. Periodontal disease-associated liver risk was accentuated among subjects with non-alcoholic fatty liver disease or heavy alcohol use at baseline.

CONCLUSIONS

Periodontitis was associated with incident liver disease in the general population independently of various confounders. As a preventable disease, periodontal disease might present a modifiable risk factor for chronic liver disease.

Influence of Porphyromonas gingivalis in gut microbiota of streptozotocin-induced diabetic mice

OBJECTIVES

Increasing evidence suggests that periodontitis can exacerbate diabetes, and gut bacterial dysbiosis appears to be linked with the diabetic condition. The present study examined the effects of oral administration of the periodontopathic bacterium, Porphyromonas gingivalis, on the gut microbiota and systemic conditions in streptozotocin-induced diabetic mice.

MATERIALS AND METHODS

Diabetes was induced by streptozotocin injection in C57BL/6J male mice (STZ). STZ and wild-type (WT) mice were orally administered P. gingivalis (STZPg, WTPg) or saline (STZco, WTco). Feces were collected, and the gut microbiome was examined by 16S rRNA gene sequencing. The expression of genes related to inflammation, epithelial tight junctions, and glucose/fatty acid metabolism in the ileum or liver were examined by quantitative PCR.

RESULTS

The relative abundance of several genera, including Brevibacterium, Corynebacterium, and Facklamia, was significantly increased in STZco mice compared to WTco mice. The relative abundances of Staphylococcus and Turicibacter in the gut microbiome were altered by oral administration of P. gingivalis in STZ mice. STZPg mice showed higher concentrations of fasting blood glucose and inflammatory genes levels in the ileum, compared to STZco mice.

CONCLUSIONS

Oral administration of P. gingivalis altered the gut microbiota and aggravated glycemic control in streptozotocin-induced diabetic mice.

Gut microbiota in children and altered profiles in juvenile idiopathic arthritis

Microbial diversity plays a key role in the maintenance of intestinal homeostasis and in the development of the immune system in the gut mucosa. Maybe one of the most important function of our gut microbiota is the immune system education, in particular the discrimination of friends from foes that occurs during childhood. In addition to bacterial antigens, several metabolites of microbial origin have a crucial role in training of the immune system, such as Short Chain Fatty Acids (SCFAs). There are many evidences on the role of the gut microbiota in rheumatic diseases, in particular modifications of microbiota composition causing dysbiosis that, in turn, can induce gut permeability, and thus immunological imbalance and trigger inflammation. In particular, immune cells can reach extra-intestinal sites, such as joints and trigger local inflammation. Childhood is a crucial period of life for development and evolution of the gut microbiota, especially for the acquisition of fundamental functions such as immunotolerance of commensal microorganisms. For this reason, gut dysbiosis is gaining interest as a potential pathogenetic factor for Juvenile Idiopathic Arthritis (JIA). Here we summarized the studies conducted on JIA patients in which a pro-arthritogenic microbial profiles has been observed; this, together with a depletion of microbial biodiversity, clearly distinguish patients' from healthy subjects' microbiota. Further studies are however needed to better clarify the role of microbiota in JIA pathogenesis.

Reassessing the Role of Entamoeba gingivalis in Periodontitis

The protozoan Entamoeba gingivalis resides in the oral cavity and is frequently observed in the periodontal pockets of humans and pets. This species of Entamoeba is closely related to the human pathogen Entamoeba histolytica, the agent of amoebiasis. Although E. gingivalis is highly enriched in people with periodontitis (a disease in which inflammation and bone loss correlate with changes in the microbial flora), the potential role of this protozoan in oral infectious diseases is not known. Periodontitis affects half the adult population in the world, eventually leads to edentulism, and has been linked to other pathologies, like diabetes and cardiovascular diseases. As aging is a risk factor for the disorder, it is considered an inevitable physiological process, even though it can be prevented and cured. However, the impact of periodontitis on the patient's health and quality of life, as well as its economic burden, are underestimated. Commonly accepted models explain the progression from health to gingivitis and then periodontitis by a gradual change in the identity and proportion of bacterial microorganisms in the gingival crevices. Though not pathognomonic, inflammation is always present in periodontitis. The recruitment of leukocytes to inflamed gums and their passage to the periodontal pocket lumen are speculated to fuel both tissue destruction and the development of the flora. The individual contribution to the disease of each bacterial species is difficult to establish and the eventual role of protozoa in the fate of this disease has been ignored. Following recent scientific findings, we discuss the relevance of these data and propose that the status of E. gingivalis be reconsidered as a potential pathogen contributing to periodontitis.

Oral health and microbiota status in professional rugby players: A case-control study

OBJECTIVE

Elite athletes are prone to develop oral diseases, which could increase the risk for injuries. The aim of this study was to evaluate the oral health and the composition of oral microbiota of elite rugby players compared to the general population.

METHODS

We set up a case-control study by screening 24 professional rugby players (PRG) and 22 control patients (CG) for dental and gingival examinations and performed a taxonomic analysis and a predicted functional analysis of oral microbiota.

RESULTS

The Decay, Missing and Filled (DMF) teeth index (5.54 ± 6.18 versus 2.14 ± 3.01; p = 0.01) and the frequency of gingivitis (58,33% versus 13.63%) were significantly increased in PRG compared to CG. PRG were characterized by a dysbiotic oral microbiota (Shannon Index: 3.32 ± 0.62 in PRG versus 3.79 ± 0.68 in CG; p = 0.03) with an increase of Streptococcus (58.43 ± 16.84 versus 42.60 ± 17.45; p = 0.005), the main genus implicated in caries. Predicted metagenomics of oral microbiota in rugby players was suggestive of a cariogenic metagenome favourable to the development of caries.

CONCLUSIONS

Our study shows that the oral health of PRG was poorer than the general population. PRG are characterized by a dysbiotic oral microbiota with an increase of the relative abundance of Streptococcus genus, positively correlated to the weight and negatively correlated to the diversity of oral microbiota.

CLINICAL SIGNIFICANCE

Dental screening should be included in the medical follow-up of professional rugby players as a part of their health management. New strategies such as using probiotics like Lactobacillus could help to control the dysbiosis of oral microbiota.

High-fat diet disrupts bone remodeling by inducing local and systemic alterations

A high-fat (HF) diet leads to detrimental effects on alveolar bone (AB); however, the mechanisms linking adiposity to bone loss are poorly understood. This study investigated if AB resorption induced by an HF diet is associated with the regulation of inflammatory gene expression and if adipocytes can directly interfere with osteoclastogenesis. We also evaluated the effects of diet restriction (DR) on bone phenotype. C57BL6/J mice were fed normal chow or an HF diet for 12 weeks. Samples of maxillae, femur, blood and white adipose tissue were analyzed. In vitro co-culture of bone marrow-derived osteoclasts and mature adipocytes was carried out. The results revealed an increased number of osteoclasts and fewer osteoblasts in animals fed the HF diet, which led to the disruption of trabecular bone and horizontal AB loss. Similar effects were observed in the femur. The metabolic parameters and the deleterious effects of the HF diet on AB and the femur were reversed after DR. The HF diet modulated the expression of 30 inflammatory genes in AB such as Fam3c, InhBa, Tnfs11, Ackr2, Pxmp2 and Chil3, which are related to the inflammatory response and bone remodeling. In vitro, mature adipocytes produced increased levels of adipokines, and co-culture with osteoclasts resulted in augmented osteoclastogenesis. The results indicate that the mechanisms by which an HF diet affects bone involve induction of osteoclastogenesis and inflammatory gene expression. Adipokines apparently are key molecules in this process. Strategies to control diet-induced bone loss might be beneficial in patients with preexisting bone inflammatory conditions.

Correlation of serum adipocytokine levels with glycolipid metabolism and inflammatory factors in obese patients with periodontal disease

OBJECTIVE

To analyze the correlation of serum levels of visfatin, leptin, resistin, and adiponectin (APN) with glycolipid metabolism and inflammatory factors in obese patients with periodontal disease.

METHODS

116 obese adults (OB), of whom 78 participants were diagnosed with different degrees of chronic periodontitis (CP), and 50 healthy adults were recruited into the study. Fasting peripheral venous blood was extracted to determine serum levels of adipocytokines (e.g., visfatin, leptin, resistin, and APN), glucolipid metabolism (e.g., fasting blood glucose (FBG), fasting insulin (FINS), C-peptide (C-P), cortisol (Cor), homeostasis model of assessment for insulin resistance index (HOMA-IR), glycosylated hemoglobin (HbA1c), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and non-high-density lipoprotein cholesterol (non-HDL)), and micro-inflammation-related indexes like C-reactive protein (CRP), interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor (TNF)-α. Correlation between levels of adipocytokines and levels of glucolipid metabolism and inflammatory factors was further analyzed.

RESULTS

Assays for plasma levels of adipocytokines showed that both the OB group and the OB with CP group had significantly higher serum levels of visfatin, leptin, and resistin than the normal control group and significantly lower serum levels of ANP than the normal control group (P<0.05). Detection of serum glucolipid metabolism levels showed that FBG, FINS, C-P, Cor, HOMA-IR, TG, TC, LDL-C, HDL-C, Non-HDL-C of OB group, and OB with CP patients were significantly higher than those of normal patients (P<0.05). Assay for plasma levels of inflammatory factors showed that both the OB group and the OB with CP group had significantly higher serum levels of CRP, IL-1β, IL-6, and TNF-α than the normal control group and significantly lower serum levels of IL-10 than the normal control group. Spearman's correlation analysis revealed that serum levels of visfatin, leptin, resistin, and APN were significantly correlated with concentrations of FBG, FINS, C-P, Cor, TG, TC, LDL-C, HDL-C, Non-HDL-C, CRP, IL-1β, IL-6, IL-10, and TNF-α.

CONCLUSIONS

There were high expression levels of inflammatory factors and glucolipid metabolism disorder in obese patients with periodontal disease and excessively expressed adipocytokines may be important factors of persistent and worsened obesity and of periodontitis.

Diet versus jaw bones: Lessons from experimental models and potential clinical implications

The consumption of different types of diets influences not only body health but the bone remodeling process as well. Nutritional components can directly affect maxillary and mandibular alveolar bone microarchitecture. In this review, we focus on the current knowledge regarding the influence of diets and dietary supplementation on alveolar bone. Accumulating evidence from experimental models suggests that carbohydrate- and fat-rich diets are detrimental for alveolar bone, whereas protective effects are associated with consumption of calcium, ω-3, and bioactive compounds. Little is known about the effects of protein-free and protein-rich diets, boron, vitamin C, vitamin E, zinc, and caffeine on alveolar bone remodeling. Adipokines and direct effects of nutritional components on bone cells are proposed mechanisms linking diet and bone. Results from animal models substantiate the role of nutritional components on alveolar bone. It is a well-built starting point for clinical studies on nutritional monitoring and intervention for patients with alveolar bone disorders, especially those who are treatment refractory.

Aggravation of collagen-induced arthritis by orally administered Porphyromonas gingivalis through modulation of the gut microbiota and gut immune system

Porhyromonas gingivalis, a causative bacterium of periodontitis, is implicated in the etiology of rheumatoid arthritis (RA), mainly because of expressing peptidyl arginine deiminase (PAD) that generates RA-related autoantigens. However, compared with other periodontopathic bacteria, the precise role of P. gingivalis in RA is largely unknown. We found that orally administered P. gingivalis changed the gut microbiome with concomitant elevation of serum endotoxin and inflammatory markers, and impairment of the gut barrier function. Based on findings showing a relationship between gut microbiota and RA, we investigated whether the change of gut microbiota induced by P. gingivalis and Prevotella intermedia, another periodontopathic bacterium without PAD, is associated with collagen-induced arthritis (CIA). DBA/1J mice were orally administered with or without bacteria followed by induction of CIA. P. gingivalis, but not P. intermedia, administration significantly aggravated arthritis with increased interleukin-17 levels in sera and culture supernatants, increased Th17 cell proportions among mesenteric lymphocytes, and a significant change in the gut microbiome. However, P. gingivalis administration did not elevate the level of anti-citrullinated protein antibody. These results suggest a unique role of P. gingivalis in the link between periodontitis and RA by affecting the gut immune system and the gut microbiota composition.

Porphyromonas gingivalis lipopolysaccharide induces pro-inflammatory adipokine secretion and oxidative stress by regulating Toll-like receptor-mediated signaling pathways and redox enzymes in adipocytes

Gut microbiota LPS contributes to obesity-related chronic inflammation and oxidative stress, promoting insulin resistance. Periodontal disease also represents a risk factor for type 2 diabetes and is associated with obesity. This study compared the effect of LPS from P. gingivalis periodontopathogen and E. coli enterobacteria on inflammatory adipokine secretion and redox status of 3T3-L1 adipocytes. We found that both LPS activated TLR2- and TLR4-mediated signaling pathways involving MyD88 adaptor and NFκB transcription factor, leading to an increased secretion of leptin, resistin, IL-6 and MCP-1. These effects were partly blocked by inhibitors targeting p38 MAPK, JNK and ERK. Moreover, P. gingivalis LPS reduced adiponectin secretion. Both LPS also enhanced ROS production and the expression of NOX2, NOX4 and iNOS genes. P. gingivalis LPS altered catalase gene expression. Collectively, these results showed that LPS of periodontal bacteria induced pro-inflammatory adipokine secretory profile and oxidative stress in adipocytes which may participate to obesity-related insulin resistance.

Toll-like receptor agonists Porphyromonas gingivalis LPS and CpG differentially regulate IL-10 competency and frequencies of mouse B10 cells

IL-10 expressing regulatory B cells (B10) play a key role in immune system balance by limiting excessive inflammatory responses. Effects of toll-like receptor signaling and co-stimulatory molecules on B10 activity during innate and adaptive immune responses are not fully understood.

Genetic Susceptibility Contributing to Periodontal and Cardiovascular Disease

Periodontal disease (PD) and coronary artery disease (CAD) are common diseases characterized by an overaggressive inflammatory response to diverse stimuli. Whereas PD leads to destruction of the tooth-supporting structures, CAD is a chronic inflammatory condition ultimately causing myocardial infarction via narrowing and occluding of blood vessels. Classical twin studies led to the conclusion that both complex diseases have a similar degree of heritability and that a significant fraction of the genetic factors accounting for this heritability is shared. Recent genome-wide association and large-scale candidate gene studies highlight that variations in >50 genes are associated with premature CAD, while variations in only 4 genes showing nominally significant associations with aggressive periodontitis and/or chronic periodontitis have so far been identified. Remarkably, 3 of the PD loci (75%) show shared associations with CAD ( ANRIL/CDKN2B-AS1, PLG, CAMTA1/VAMP3), suggesting involvement of common pathogenic mechanisms. In this critical review, we highlight recent progress in identifying genetic markers and variants associated with PD, present their overlap with CAD, and discuss functional aspects. In addition, we answer why a significant fraction of the heritability of PD is still missing, and we suggest approaches that may be taken to close the gap.

Role of Maternal Periodontitis in Preterm Birth

In the last two decades, many studies have focused on whether periodontitis is a risk factor for preterm birth (PTB). However, both epidemiological investigation and intervention trials have reached contradictory results from different studies. What explains the different findings, and how should future studies be conducted to better assess this risk factor? This article reviews recent epidemiological, animal, and in vitro studies as well as intervention trials that evaluate the link between periodontitis and PTB. Periodontitis may act as a distant reservoir of microbes and inflammatory mediators and contribute to the induction of PTB. Animal studies revealed that maternal infections with periodontal pathogens increase levels of circulating IL-1β, IL-6, IL-8, IL-17, and TNF-α and induce PTB. In vitro models showed that periodontal pathogens/byproducts induce COX-2, IL-8, IFN-γ, and TNF-α secretion and/or apoptosis in placental tissues/cells. The effectiveness of periodontal treatment to prevent PTB is influenced by the diagnostic criteria of periodontitis, microbial community composition, severity of periodontitis, treatment strategy, treatment efficiency, and the period of treatment during pregnancy. Although intervention trials reported contradictory results, oral health maintenance is an important part of preventive care that is both effective and safe throughout pregnancy and should be supported before and during pregnancy. As contradictory epidemiological and intervention studies continue to be published, two new ideas are proposed here: (1) severe and/or generalized periodontitis promotes PTB and (2) periodontitis only promotes PTB for pregnant women who are young or HIV-infected or have preeclampsia, pre-pregnancy obesity, or susceptible genotypes.

The Use of Different Irrigation Techniques to Decrease Bacterial Loads in Healthy and Diabetic Patients with Asymptomatic Apical Periodontitis

BACKGROUND

Diabetes mellitus is a multisystem disease which weakens the human's immunity. Subsequently, it worsens the sequelae of apical periodontitis by raising a fierce bacterial trait due to the impaired host response.

AIM

This study aimed to estimate bacterial reduction after using different irrigation techniques in systemically healthy and diabetic patients with asymptomatic apical periodontitis.

MATERIAL AND METHODS

Enterococcus faecalis, Peptostreptococcus micros, and Fusobacterium necleatum bacteria were chosen, as they are the most common and prevailing strains found in periodontitis. Bacterial samples were retrieved from necrotic root canals of systemically healthy and diabetic patients, before and after endodontic cleaning and shaping by using two different irrigation techniques; the conventional one and the EndoVac system. Quantitive polymerase chain reaction (qPCR) was utilised to detect the reduction in the bacterial count.

RESULTS

The EndoVac irrigation system was effective in reducing bacteria, especially Peptostreptococcus micros in the diabetic group when compared to conventional irrigation technique with a statistically significant difference.

CONCLUSION

The EndoVac can be considered as a promising tool in combination with irrigant solution to defeat the bacterial colonies living in the root canal system. Additional studies ought to be done to improve the means of bacterial clearance mainly in immune-compromised individuals.

Evidence of microbiota dysbiosis in chronic rhinosinusitis

BACKGROUND

Despite considerable research, the pathogenesis of chronic rhinosinusitis (CRS) remains poorly understood. Potential microbial roles in the etiology or progression of CRS have long been hypothesized, yet few specific associations have been identified. In this study we investigate associations between patterns in resident bacterial communities and clinical variants of CRS.

METHODS

Bacterial communities were assessed in 94 patients with extensive bilateral CRS undergoing endoscopic sinus surgery (ESS) and 29 controls undergoing ESS for indications other than CRS. Patients were grouped on the basis of phenotypic variants (with or without polyposis) and clinical parameters, including asthma and cystic fibrosis. Bacterial communities were characterized via 16S rRNA gene amplicon sequencing, and quantified by quantitative polymerase chain reaction.

RESULTS

Controls and idiopathic CRS subjects tended to be dominated by members of the genera Corynebacterium and Staphylococcus, together with lower abundances of several other genera, including Streptococcus, Moraxella, and Haemophilus. Aberrant (dysbiotic) bacterial assemblages (with changes in community membership and structure, reduced diversity, and increased bacterial load) and increased inter- and intrasubject variability were more common in subjects with comorbidities such as asthma and cystic fibrosis. Dysbiotic communities were variably dominated by members of the genera Staphylococcus, Streptococcus, Haemophilus, Pseudomonas, Moraxella, or Fusobacterium.

CONCLUSION

Bacterial community dysbiosis was more apparent than specific associations with examined phenotypes or endotypes, and may play a role in the pathogenesis or influence the severity of CRS. Reductions in several common core bacterial taxa, increased inter- and intrasubject variability, reduced bacterial diversity, and increased bacterial load characterized aberrant bacterial communities in CRS.