Porphyromonas gingivalis Induces Insulin Resistance by Increasing BCAA Levels in Mice

Rational design of multifunctional hydrogels targeting the microenvironment of diabetic periodontitis

Periodontitis is a chronic inflammatory disease and is the primary contributor to adult tooth loss. Diabetes exacerbates periodontitis, accelerates periodontal bone resorption. Thus, effectively managing periodontitis in individuals with diabetes is a long-standing challenge. This review introduces the etiology and pathogenesis of periodontitis, and analyzes the bidirectional relationship between diabetes and periodontitis. In this review, we comprehensively summarize the four pathological microenvironments influenced by diabetic periodontitis: high glucose microenvironment, bacterial infection microenvironment, inflammatory microenvironment, and bone loss microenvironment. The hydrogel design strategies and latest research development tailored to the four microenvironments of diabetic periodontitis are mainly focused on. Finally, the challenges and potential solutions in the treatment of diabetic periodontitis are discussed. We believe this review will be helpful for researchers seeking novel avenues in the treatment of diabetic periodontitis.

Gingipain from Porphyromonas gingivalis causes insulin resistance by degrading insulin receptors through direct proteolytic effects

Periodontitis is a critical risk factor for the occurrence and development of diabetes. Porphyromonas gingivalis may participate in insulin resistance (IR) caused by periodontal inflammation, but the functional role and specific mechanisms of P. gingivalis in IR remain unclear. In the present study, clinical samples were analysed to determine the statistical correlation between P. gingivalis and IR occurrence. Through culturing of hepatocytes, myocytes, and adipocytes, and feeding mice P. gingivalis orally, the functional correlation between P. gingivalis and IR occurrence was further studied both in vitro and in vivo. Clinical data suggested that the amount of P. gingivalis isolated was correlated with the Homeostatic Model Assessment for IR score. In vitro studies suggested that coculture with P. gingivalis decreased glucose uptake and insulin receptor (INSR) protein expression in hepatocytes, myocytes, and adipocytes. Mice fed P. gingivalis tended to undergo IR. P. gingivalis was detectable in the liver, skeletal muscle, and adipose tissue of experimental mice. The distribution sites of gingipain coincided with the downregulation of INSR. Gingipain proteolysed the functional insulin-binding region of INSR. Coculture with P. gingivalis significantly decreased the INSR-insulin binding ability. Knocking out gingipain from P. gingivalis alleviated the negative effects of P. gingivalis on IR in vivo. Taken together, these findings indicate that distantly migrated P. gingivalis may directly proteolytically degrade INSR through gingipain, thereby leading to IR. The results provide a new strategy for preventing diabetes by targeting periodontal pathogens and provide new ideas for exploring novel mechanisms by which periodontal inflammation affects the systemic metabolic state.

Ethanol extract from Astilbe chinensis inflorescence suppresses inflammation in macrophages and growth of oral pathogenic bacteria

Chronic oral inflammation and biofilm-mediated infections drive diseases such as dental caries and periodontitis. This study investigated the anti-inflammatory and antibacterial potential of an ethanol extract from Astilbe chinensis inflorescence (GA-13-6) as a prominent candidate for natural complex substances (NCS) with therapeutic potential. In LPS-stimulated RAW 264.7 macrophages, GA-13-6 significantly suppressed proinflammatory mediators, including interleukin-6 (IL-6), tumor necrosis factor (TNF), and nitric oxide (NO), surpassing purified astilbin, a known bioactive compound found in A. chinensis. Furthermore, GA-13-6 downregulated the expression of cyclooxygenase-2 (COX2) and inducible nitric oxide synthase (iNOS), indicating an inhibitory effect on the inflammatory cascade. Remarkably, GA-13-6 exhibited selective antibacterial activity against Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis, key players in dental caries and periodontitis, respectively. These findings suggest that complex GA-13-6 holds the potential for the treatment or prevention of periodontal and dental diseases, as well as various other inflammation-related conditions, while averting the induction of antibiotic resistance.

Functional profile of oral plaque microbiome: Further insight into the bidirectional relationship between type 2 diabetes and periodontitis

Increasing evidence support the association between the oral microbiome and human systemic diseases. This association may be attributed to the ability of many oral microbes to influence the inflammatory microenvironment. Herein, we focused our attention on the bidirectional relationship between periodontitis and type 2 diabetes using high-resolution whole metagenomic shotgun analysis to explore the composition and functional profile of the subgingival microbiome in diabetics and non-diabetics subjects with different periodontal conditions. In the present study, the abundance of metabolic pathways encoded by oral microbes was reconstructed from the metagenome, and we identified a set of dysregulated metabolic pathways significantly enriched in the periodontitis and/or diabetic patients. These pathways were mainly involved in branched and aromatic amino acids metabolism, fatty acid biosynthesis and adipocytokine signaling pathways, ferroptosis and iron homeostasis, nucleotide metabolism, and finally in the peptidoglycan and lipopolysaccharides synthesis. Overall, the results of the present study provide evidence in favor of the hypothesis that during the primary inflammatory challenge, regardless of whether it is induced by periodontitis or diabetes, endotoxemia and/or the release of inflammatory cytokines cause a change in precursor and/or in circulating innate immune cells. Dysbiosis and inflammation, also via oral-gut microbiome axis or adipose tissue, reduce the efficacy of the host immune response, while fueling inflammation and can induce that metabolic/epigenetic reprogramming of chromatin accessibility of genes related to the immune response. Moreover, the presence of an enhanced ferroptosis and an imbalance in purine/pyrimidine metabolism provides new insights into the role of ferroptotic death in this comorbidity.

Bergenin Alleviates Ulcerative Colitis By Decreasing Gut Commensal Bacteroides vulgatus-Mediated Elevated Branched-Chain Amino Acids

Ulcerative colitis is closely associated with the dysregulation of gut microbiota. There is growing evidence that natural products may improve ulcerative colitis by regulating the gut microbiota. In this research, we demonstrated that bergenin, a naturally occurring isocoumarin, significantly ameliorates colitis symptoms in dextran sulfate sodium (DSS)-induced mice. Transcriptomic analysis and Caco-2 cell assays revealed that bergenin could ameliorate ulcerative colitis by inhibiting TLR4 and regulating NF-κB and mTOR phosphorylation. 16S rRNA sequencing and metabolomics analyses revealed that bergenin could improve gut microbiota dysbiosis by decreasing branched-chain amino acid (BCAA) levels. BCAA intervention mediated the mTOR/p70S6K signaling pathway to exacerbate the symptoms of ulcerative colitis in mice. Notably, bergenin greatly decreased the symbiotic bacteria Bacteroides vulgatus (B. vulgatus), and the gavage of B. vulgatus increased BCAA concentrations and aggravated the symptoms of ulcerative colitis in mice. Our findings suggest that gut microbiota-mediated BCAA metabolism plays a vital role in the protective effect of bergenin on ulcerative colitis, providing novel insights for ulcerative colitis prevention through manipulation of the gut microbiota.

From Energy Metabolic Change to Precision Therapy: a Holistic View of Energy Metabolism in Heart Failure

Heart failure (HF) is a complex and multifactorial disease that affects millions of people worldwide. It is characterized by metabolic disturbances of substrates such as glucose, fatty acids (FAs), ketone bodies, and amino acids, which lead to changes in cardiac energy metabolism pathways. These metabolic alterations can directly or indirectly promote myocardial remodeling, thereby accelerating the progression of HF, resulting in a vicious cycle of worsening symptoms, and contributing to the increased hospitalization and mortality among patients with HF. In this review, we summarized the latest researches on energy metabolic profiling in HF and provided the related translational therapeutic strategies for this devastating disease. By taking a holistic approach to understanding energy metabolism changes in HF, we hope to provide comprehensive insights into the pathophysiology of this challenging condition and identify novel precise targets for the development of more effective treatments.

The association between plasma free amino acids and type 2 diabetes mellitus complicated with infection in Chinese patients

BACKGROUND

Type 2 diabetes mellitus (T2DM), one of the most common public diseases threatening human health, is always accompanied by infection. Though there are still a variety of flaws in the treatment of some infectious diseases, metabolomics provides a fresh perspective to explore the relationship between T2DM and infection. Our research aimed to investigate the association between plasma free amino acids (PFAAs) and T2DM complicated with infection in Chinese patients.

METHODS

A cross-sectional study was conducted from May 2015 to August 2016. We retrieved the medical records of 1032 inpatients with T2DM from Liaoning Medical University First Affiliated Hospital and we used mass spectrometry to quantify 23 PFAAs. Infections contained 15 individual categories that could be retrieved from the database. Principal component analysis was used to extract factors of PFAAs. Multi-variable binary logistic regression was used to obtain odds ratios (OR) and their 95% confidence intervals (CI).

RESULTS

Among 1032 inpatients,109 (10.6%) had infectious diseases. Six factors, accounting for 68.6% of the total variance, were extracted. Factor 4 consisted of Glu, Asp and Orn. Factor 5 consisted of Hcy and Pip. After adjusting for potential confounders, factor 4 was positively correlated with T2DM complicated with infection in Chinese T2DM patients (OR: 1.27, 95%CI: 1.06-1.52). Individual Hcy in factor 5 was positively associated with T2DM complicated with infection (OR: 1.33, 95%CI: 1.08-1.64). Furthermore, factor 4 (OR: 1.44, 95%CI: 1.11-1.87), Orn (OR: 1.01, 95%CI: 1.00-1.02) and Hcy (OR: 1.56, 95%CI: 1.14-3.14) were positively associated with bacterial infection in Chinese T2DM patients, while factor 5 (OR: 0.71, 95%CI: 0.50-1.00) was negatively associated with bacterial infection.

CONCLUSIONS

Urea cycle-related metabolites (Orn, Asp, Glu) and Hcy were positively associated with T2DM complicated with infection in China. Orn and Hcy were positively associated with bacterial infection in T2DM patients in China.

Increased serum α-tocopherol acetate mediated by gut microbiota ameliorates alveolar bone loss through the STAT3 signalling pathway in diabetic periodontitis

AIM

To evaluate whether and how gut microbiota-meditated metabolites regulate alveolar bone homeostasis in diabetic periodontitis (DP).

MATERIALS AND METHODS

Lactobacillus casei (L. casei) was employed as a positive modulator of gut microbiota in DP mice. The destruction of alveolar bone was evaluated. Untargeted metabolomics was conducted to screen out the pivotal metabolites. A co-housing experiment was conducted to determine the connection between the gut microbiota and alpha-tocopherol acetate (α-TA). α-TA was applied to DP mice to investigate its effect against alveolar bone loss. Human periodontal ligament cells (hPDLCs) and human gingival fibroblasts (HGFs) were extracted for the in vitro experiment. Transcriptomic analysis and immunohistochemistry were performed to detect the major affected signalling pathways.

RESULTS

Positive regulation of the gut microbiota significantly attenuated alveolar bone loss and increased the serum α-TA level. The alteration in gut microbiota composition could affect the serum α-T (the hydrolysates of α-TA) level. α-TA could alleviate alveolar bone destruction in DP mice and α-T exert beneficial effects on hPDLCs and HGFs. Mechanistically, the STAT3 signalling pathway was the pivotal pathway involved in the protective role of α-TA.

CONCLUSIONS

The gut microbiota-α-TA-STAT3 axis plays an important role in the regulation of diabetic alveolar bone homeostasis.

Neutrophils' Contribution to Periodontitis and Periodontitis-Associated Cardiovascular Diseases

Neutrophils represent the primary defense against microbial threats playing a pivotal role in maintaining tissue homeostasis. This review examines the multifaceted involvement of neutrophils in periodontitis, a chronic inflammatory condition affecting the supporting structures of teeth summarizing the contribution of neutrophil dysfunction in periodontitis and periodontal-related comorbidities. Periodontitis, a pathological condition promoted by dysbiosis of the oral microbiota, is characterized by the chronic inflammation of the gingiva and subsequent tissue destruction. Neutrophils are among the first immune cells recruited to the site of infection, releasing antimicrobial peptides, enzymes, and reactive oxygen species to eliminate pathogens. The persistent inflammatory state in periodontitis can lead to aberrant neutrophil activation and a sustained release of proinflammatory mediators, finally resulting in tissue damage, bone resorption, and disease progression. Growing evidence now points to the correlation between periodontitis and systemic comorbidities. Indeed, the release of inflammatory mediators, immune complexes, and oxidative stress by neutrophils, bridge the gap between local and systemic immunity, thus highlighting neutrophils as key players in linking periodontal inflammation to chronic conditions, including cardiovascular diseases, diabetes mellitus, and rheumatoid arthritis. This review underscores the crucial role of neutrophils in the pathogenesis of periodontitis and the complex link between neutrophil dysfunction, local inflammation, and systemic comorbidities. A comprehensive understanding of neutrophil contribution to periodontitis development and their impact on periodontal comorbidities holds significant implications for the management of oral health. Furthermore, it highlights the need for the development of novel approaches aimed at limiting the persistent recruitment and activation of neutrophils, also reducing the impact of periodontal inflammation on broader health contexts, offering promising avenues for improved disease management and patient care.

Diabetes mellitus promotes susceptibility to periodontitis-novel insight into the molecular mechanisms

Diabetes mellitus is a main risk factor for periodontitis, but until now, the underlying molecular mechanisms remain unclear. Diabetes can increase the pathogenicity of the periodontal microbiota and the inflammatory/host immune response of the periodontium. Hyperglycemia induces reactive oxygen species (ROS) production and enhances oxidative stress (OS), exacerbating periodontal tissue destruction. Furthermore, the alveolar bone resorption damage and the epigenetic changes in periodontal tissue induced by diabetes may also contribute to periodontitis. We will review the latest clinical data on the evidence of diabetes promoting the susceptibility of periodontitis from epidemiological, molecular mechanistic, and potential therapeutic targets and discuss the possible molecular mechanistic targets, focusing in particular on novel data on inflammatory/host immune response and OS. Understanding the intertwined pathogenesis of diabetes mellitus and periodontitis can explain the cross-interference between endocrine metabolic and inflammatory diseases better, provide a theoretical basis for new systemic holistic treatment, and promote interprofessional collaboration between endocrine physicians and dentists.

Host insulin resistance caused by Porphyromonas gingivalis-review of recent progresses

Porphyromonas gingivalis (P. gingivalis) is a Gram-negative oral anaerobic bacterium that plays a key role in the pathogenesis of periodontitis. P. gingivalis expresses a variety of virulence factors that disrupt innate and adaptive immunity, allowing P. gingivalis to survive and multiply in the host and destroy periodontal tissue. In addition to periodontal disease, P.gingivalis is also associated with systemic diseases, of which insulin resistance is an important pathological basis. P. gingivalis causes a systemic inflammatory response, disrupts insulin signaling pathways, induces pancreatic β-cell hypofunction and reduced numbers, and causes decreased insulin sensitivity leading to insulin resistance (IR). In this paper, we systematically review the studies on the mechanism of insulin resistance induced by P. gingivalis, discuss the association between P. gingivalis and systemic diseases based on insulin resistance, and finally propose relevant therapeutic approaches. Overall, through a systematic review of the mechanisms related to systemic diseases caused by P. gingivalis through insulin resistance, we hope to provide new insights for future basic research and clinical interventions for related systemic diseases.

Predictive value of TCM clinical index for diabetic peripheral neuropathy among the type 2 diabetes mellitus population: A new observation and insight

Aims

The objectives of this study were to identify clinical predictors of the Traditional Chinese medicine (TCM) clinical index for diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM) patients, develop a clinical prediction model, and construct a nomogram.

Methods

We collected the TCM clinical index from 3590 T2DM recruited at the Second Affiliated Hospital of Tianjin University of Traditional Chinese Medicine from January 2019 to October 2020. The participants were randomly assigned to either the training group (n = 3297) or the validation group (n = 1426). TCM symptoms and tongue characteristics were used to assess the risk of developing DPN in T2DM patients. Through 5-fold cross-validation in the training group, the least absolute shrinkage and selection operator (LASSO) regression analysis method was used to optimize variable selection. In addition, using multifactor logistic regression analysis, a predictive model and nomogram were developed.

Results

A total of eight independent predictors were found to be associated with the DPN in multivariate logistic regression analyses: advanced age of grading (odds ratio/OR 1.575), smoke (OR 2.815), insomnia (OR 0.557), sweating (OR 0.535), loose teeth (OR 1.713), dry skin (OR 1.831), purple tongue (OR 2.278). And dark red tongue (OR 0.139). The model was constructed using these eight predictor's medium discriminative capabilities. The area under the curve (AUC) of the training set is 0.727, and the AUC of the validation set is 0.744 on the ROC curve. The calibration plot revealed that the model's goodness-of-fit is satisfactory.

Conclusions

We established a TCM prediction model for DPN in patients with T2DM based on the TCM clinical index.

Bidirectional association between polycystic ovary syndrome and periodontal diseases

Polycystic ovary syndrome (PCOS) and periodontal disease (PDD) share common risk factors. The bidirectional interaction between PCOS and PDD has been reported, but until now, the underlying molecular mechanisms remain unclear. Endocrine disorders including hyperandrogenism (HA) and insulin resistance (IR) in PCOS disturb the oral microbial composition and increase the abundance of periodontal pathogens. Additionally, PCOS has a detrimental effect on the periodontal supportive tissues, including gingiva, periodontal ligament, and alveolar bone. Systemic low-grade inflammation status, especially obesity, persistent immune imbalance, and oxidative stress induced by PCOS exacerbate the progression of PDD. Simultaneously, PDD might increase the risk of PCOS through disturbing the gut microbiota composition and inducing low-grade inflammation and oxidative stress. In addition, genetic or epigenetic predisposition and lower socioeconomic status are the common risk factors for both diseases. In this review, we will present the latest evidence of the bidirectional association between PCOS and PDD from epidemiological, mechanistic, and interventional studies. A deep understanding on their bidirectional association will be beneficial to provide novel strategies for the treatment of PCOS and PDD.

Impact of Porphyromonas gingivalis-odontogenic infection on the pathogenesis of non-alcoholic fatty liver disease

Aim: Non-alcoholic fatty liver disease is characterized by diffuse hepatic steatosis and has quickly risen to become the most prevalent chronic liver disease. Its incidence is increasing yearly, but the pathogenesis is still not fully understood. Porphyromonas gingivalis (P. gingivalis) is a major pathogen widely prevalent in periodontitis patients. Its infection has been reported to be a risk factor for developing insulin resistance, non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and metabolic syndrome. The aim of this review is to evaluate the association between P. gingivalis infection and NAFLD, identify the possible etiopathogenetic mechanisms, and raise public awareness of oral health to prevent and improve NAFLD.Methods: After searching in PubMed and Web of Science databases using 'Porphyromonas gingivalis', 'non-alcoholic fatty liver disease', and 'hepatic steatosis' as keywords, studies related were compiled and examined.Results: P. gingivalis infection is a direct risk factor for NAFLD based on clinical and basic research. Moreover, it induces systematic changes and systemic abnormalities by disrupting metabolic, inflammatory, and immunologic homeostasis.Conclusion: P. gingivalis-odontogenic infection promotes the occurrence and development of NAFLD. Further concerns are needed to emphasize oral health and maintain good oral hygiene for the prevention and treatment of NAFLD.

Sex differences in the oral microbiome, host traits, and their causal relationships

The oral microbiome has been implicated in a growing number of diseases; however, determinants of the oral microbiome and their roles remain elusive. Here, we investigated the oral (saliva and tongue dorsum) metagenome, the whole genome, and other omics data in a total of 4,478 individuals and demonstrated that the oral microbiome composition and its major contributing host factors significantly differed between sexes. We thus conducted a sex-stratified metagenome-genome-wide-association study (M-GWAS) and identified 11 differential genetic associations with the oral microbiome (p _{sex-difference}  < 5 × 10^-8). Furthermore, we performed sex-stratified Mendelian randomization (MR) analyses and identified abundant causalities between the oral microbiome and serum metabolites. Notably, sex-specific microbes-hormonal interactions explained the mostly observed sex hormones differences such as the significant causalities enrichments for aldosterone in females and androstenedione in males. These findings illustrate the necessity of sex stratification and deepen our understanding of the interplay between the oral microbiome and serum metabolites.

Circulating small extracellular vesicles from patients with periodontitis contribute to development of insulin resistance

BACKGROUND

Epidemiological studies have identified the role of periodontitis in the pathogenesis of type 2 diabetes, but the underlying mechanism is poorly understood. It is well-known that small extracellular vesicles are lipid bilayer vesicles derived from cells with a diameter around 30 to 200 nm. The purpose of this study was to investigate whether periodontitis induced or exacerbated insulin resistance via circulating small extracellular vesicles.

METHODS

Plasma small extracellular vesicles from control and periodontitis rats were intravenously injected into type 2 diabetic rats. Insulin tolerance tests, glucose tolerance tests, and the activation of the insulin signaling pathway were measured to detect the effect of the plasma small extracellular vesicles on insulin sensitivity. In addition, circulating small extracellular vesicles from patients with periodontitis with or without diabetes were isolated and co-cultured with HepG2 cells. The ability of glucose uptake was assessed using the fluorescence of 2-NBDG via flow cytometry. The activation of insulin signaling pathway was examined via Western blotting. Real time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of enzyme related to glycolysis and gluconeogenesis.

RESULTS

Small extracellular vesicles derived from the plasma of periodontitis rats further impaired glucose tolerance and insulin tolerance in diabetic rats and significantly reduced the activation of the insulin signaling pathway in liver tissues, as evidenced by the decreased levels of p-AKT and p-GSK3β and the reduced hepatic glycogen content. For small extracellular vesicles isolated from human plasma, the concentration of small extracellular vesicles in patients with type 2 diabetes combined with periodontitis was higher than that of the healthy control and periodontitis alone. Moreover, circulating small extracellular vesicles from patients with periodontitis significantly inhibited the glucose uptake capacity and inhibited insulin signaling of HepG2 cells.

CONCLUSION

Periodontitis acted as a contributing factor to exacerbate insulin resistance of type 2 diabetic rats. Plasma small extracellular vesicles played a critical role in periodontitis aggravating insulin resistance.

Beneficial Effects of Melatonin on Periodontitis Management: Far More Than Oral Cavity

Periodontitis as a highly prevalent chronic infection/inflammatory disease can eventually lead to tooth loss and masticatory dysfunction. It also has a negative impact on general health and largely impairs quality of life. The tissue destruction during periodontitis is mainly caused by the excessive immune-inflammatory response; hence, how to modulate the host's reaction is of profound importance for effective periodontal treatment and tissue protection. Melatonin, as an endogenous hormone exhibiting multiple biological functions such as circadian rhythm regulation, antioxidant, and anti-inflammation, has been widely used in general healthcare. Notably, the past few years have witnessed increasing evidence for the application of melatonin as an adjunctive approach in the treatment of periodontitis and periodontitis-related systemic comorbidities. The detailed underlying mechanisms and more verification from clinical practice are still lacking, however, and further investigations are highly required. Importantly, it is essential to establish standard guidelines in the near future for the clinical administration of melatonin for periodontal health and general wellbeing.

Periodontitis and Its Inflammatory Changes Linked to Various Systemic Diseases: A Review of Its Underlying Mechanisms

Periodontitis is a chronic inflammatory disease of the gums. The incidence of periodontitis is increasing all over the world. In patients with periodontitis, there is gradual destruction of the periodontal ligament and the alveolar bone, and later, in advanced stages, there is tooth loss. Different microorganisms, the host’s immune response, and various environmental factors interact in the progression of this chronic inflammatory disease. In the present review, we discuss the epidemiology, clinical features, diagnosis, and complications of periodontitis. We also discuss the association of chronic inflammation found in periodontitis with various other systemic diseases, which include cardiovascular, respiratory, diabetes, Alzheimer’s, cancer, adverse pregnancy, and multiple myeloma, and also highlight microbial carcinogenesis and the microRNAs involved. The latest updates on the molecular mechanism, possible biomarkers, and treatment procedures may be beneficial for diagnostic and therapeutic purposes.

Periodontitis induced by Porphyromonas gingivalis drives impaired glucose metabolism in mice

Periodontitis has been demonstrated to be bidirectionally associated with diabetes and has been recognized as a complication of diabetes. As a periodontal pathogen, Porphyromonas gingivalis is a possible pathogen linking periodontal disease and systemic diseases. It has also been found to be involved in the occurrence and development of diabetes. In this study, 6-week-old male C57BL/6 mice were orally administered the P. gingivalis strain ATCC381 for 22 weeks. Histological analysis of the gingival tissue and quantified analysis of alveolar bone loss were performed to evaluate periodontal destruction. Body weight, fasting glucose, glucose tolerance test (GTT), and insulin tolerance test (ITT) were used to evaluate glucose metabolism disorder. We then analyzed the expression profiles of inflammatory cytokines and chemokines in gingival tissue, the liver, and adipose tissue, as well as in serum. The results showed that mice in the P. gingivalis-administered group developed apparent gingival inflammation and more alveolar bone loss compared to the control group. After 22 weeks of P. gingivalis infection, significant differences were observed at 30 and 60 min for the GTT and at 15 min for the ITT. P. gingivalis-administered mice showed an increase in the mRNA expression levels of the pro-inflammatory cytokines (TNF-α, IL-6, IL-17, and IL-23) and chemokines (CCL2, CCL8, and CXCL10) in the gingiva and serum. The expression levels of the glucose metabolism-related genes were also changed in the liver and adipose tissue. Our results indicate that oral administration of P. gingivalis can induce changes in the inflammatory cytokines and chemokines in the gingiva and blood, can lead to alveolar bone loss and to inflammatory changes in the liver and adipose tissues, and can promote glucose metabolism disorder in mice.

Host Response Modulation Therapy in the Diabetes Mellitus—Periodontitis Conjuncture: A Narrative Review

The inflammatory response of the host in periodontitis is the phenomenon that underlies the onset and evolution of periodontal destructive phenomena. A number of systemic factors, such as diabetes mellitus (DM), can negatively affect the patient with periodontitis, just as the periodontal disease can aggravate the status of the DM patient. Host response modulation therapy involves the use of anti-inflammatory and anti-oxidant products aimed at resolving inflammation, stopping destructive processes, and promoting periodontal healing, all important aspects in patients with high tissue loss rates, such as diabetic patients. This paper reviews the data available in the literature on the relationship between DM and periodontitis, the main substances modulating the inflammatory response (nonsteroidal anti-inflammatory drugs, sub-antimicrobial doses of doxycycline, or omega-3 fatty acids and their products, specialized pro-resolving mediators), as well as their application in diabetic patients.

Correlation of Salivary Occult Blood with the Plasma Concentration of Branched-Chain Amino Acids: A Cross-Sectional Study

Background: Plasma branched-chain amino acids (BCAA) levels are predictors of glycometabolic disorders, leading to diabetes. Microbes, including periodontal pathogens, are thought to be associated with elevated plasma BCAA levels. This study aimed to evaluate the relationship between salivary occult blood (SOB) and plasma BCAA levels in middle-aged Japanese individuals. Methods: Sixty-four Japanese individuals aged ≥ 40 years were recruited for this study, which was conducted in Fukuoka Prefecture, Japan, from August to December 2021. Individuals diagnosed with and/or treated for diabetes were excluded from the study. The body mass index (BMI); plasma concentrations of total, high-density, and low-density lipoprotein cholesterol; triglyceride, glucose, and BCAA; and glycosylated hemoglobin ratio were measured. A basic periodontal examination was performed after the SOB test. Results: The median age of participants (men—20; women—44) was 55 (range, 41–78) years. The plasma BCAA concentration in the SOB-positive group (477 [400–658] μmol/L) was higher than that in the SOB-negative group (432 [307–665] μmol/L). Linear regression analysis revealed that SOB remained independently associated with the plasma BCAA level with statistical significance (β = 0.17, p = 0.02) after adjusting for sex, age, and BMI. Conclusions: SOB was positively correlated with plasma BCAA levels in middle-aged Japanese individuals. Thus, SOB may be a predictor of elevated plasma BCAA levels.

Alterations and Correlations of Gut Microbiota and Fecal Metabolome Characteristics in Experimental Periodontitis Rats

Objectives

Periodontitis affects the progression of many diseases, while its detailed mechanism remains unclear. This study hopes to provide new ideas for exploring its mechanism by analyzing the gut microbiota and fecal metabolic characteristics of experimental periodontitis rats.

Methods

A total of 10 rats were randomly divided into ligature-induced experimental periodontitis (EP) group and healthy control group. After 4 weeks of the experiment, the feces of all rats were collected for sequencing through 16S ribosomal DNA (rDNA) sequencing technology and liquid chromatography–mass spectrometry (LC–MS).

Results

16S rDNA sequencing results showed that the β-diversity of gut microbiota was significantly different between the EP and control group, and the levels of dominant genera were different. Compared with the control group, Ruminococcus, Escherichia, and Roseburia were significantly enriched in EP, and Coprococcus, Turicibacter, Lachnospira were significantly decreased. Correlation analysis showed that Roseburia exhibited the highest correlation within the genus. Of 3,488 qualitative metabolites, 164 metabolites were upregulated and 362 metabolites were downregulated in EP. Enrichment analysis showed that periodontitis significantly changed 45 positive/negative ion metabolic pathways. Five KEGG pathways, protein digestion and absorption, tyrosine metabolism, glycolysis/gluconeogenesis, niacin and nicotinamide metabolism, and oxidative phosphorylation, are enriched in both the microbiome and metabolome. Correlation analysis showed that the genera with significant differences in periodontitis were usually significantly correlated with more metabolites, such as Roseburia, Lachnospira, Escherichia, Turicibacter, and Ruminococcus. The genera with the same changing trend tended to have a similar correlation with some certain metabolites. In addition, vitamin D2 and protoporphyrin IX have the most significant correlations with microorganisms.

Conclusion

Our study reveals that periodontitis alters gut microbiota and fecal metabolites. The correlation analysis of microbiota and metabolome provides a deeper understanding of periodontitis, and also provides a direction for the study of periodontitis affecting other diseases.

Are Inflamed Periodontal Tissues Endogenous Source of Advanced Glycation End-Products (AGEs) in Individuals with and without Diabetes Mellitus? A Systematic Review

Advanced glycation end-products (AGEs) are heterogeneous compounds formed when excess sugars condense with the amino groups of nucleic acids and proteins. Increased AGEs are associated with insulin resistance and poor glycemic control. Recently, inflamed periodontal tissues and certain oral bacteria were observed to increase the local and systemic AGE levels in both normoglycemic and hyperglycemic individuals. Although hyperglycemia induced AGE and its effect on the periodontal tissues is known, periodontitis as an endogenous source of AGE formation is not well explored. Hence, this systematic review is aimed to explore, for the first time, whether inflamed periodontal tissues and periodontal pathogens have the capacity to modulate AGE levels in individuals with or without T2DM and how this affects the glycemic load. Six electronic databases were searched using the following keywords: (Periodontitis OR Periodontal disease OR Periodontal Inflammation) AND (Diabetes mellitus OR Hyperglycemia OR Insulin resistance) AND Advanced glycation end products. The results yielded 1140 articles, of which 13 articles were included for the review. The results showed that the mean AGE levels in gingival crevicular fluid was higher in individuals with diabetes mellitus and periodontitis (521.9 pg/mL) compared to healthy individuals with periodontitis (234.84 pg/mL). The serum AGE levels in normoglycemic subjects having periodontitis was higher compared to those without periodontitis (15.91 ng/mL vs. 6.60 ng/mL). Tannerella forsythia, a common gram-negative anaerobe periodontal pathogen in the oral biofilm, was observed to produce methylglyoxal (precursor of AGE) in the gingival tissues. Increased AGE deposition and activate of AGE receptors was noted in the presence of periodontitis in both normoglycemic and hyperglycemic individuals. Hence, it can be concluded that periodontitis can modulate the local and systemic levels of AGE levels even in absence of hyperglycemia. This explains the bidirectional relationship between periodontitis and development of prediabetes, incident diabetes, poor glycemic control, and insulin resistance.

Research on Graphene and Its Derivatives in Oral Disease Treatment

Oral diseases present a global public health problem that imposes heavy financial burdens on individuals and health-care systems. Most oral health conditions can be treated in their early stage. Even if the early symptoms of oral diseases do not seem to cause significant discomfort, prompt treatment is essential for preventing their progression. Biomaterials with superior properties enable dental therapies with applications in restoration, therapeutic drug/protein delivery, and tissue regeneration. Graphene nanomaterials have many unique mechanical and physiochemical properties and can respond to the complex oral microenvironment, which includes oral microbiota colonization and high masticatory force. Research on graphene nanomaterials in dentistry, especially in caries, periodontitis therapy, and implant coatings, is progressing rapidly. Here, we review the development of graphene and its derivatives for dental disease therapy.

Leaky Gum: The Revisited Origin of Systemic Diseases

The oral cavity is the gateway for microorganisms into your body where they disseminate not only to the directly connected respiratory and digestive tracts but also to the many remote organs. Oral microbiota, travelling to the end of the intestine and circulating in our bodies through blood vessels, not only affect a gut microbiome profile but also lead to many systemic diseases. By gathering information accumulated from the era of focal infection theory to the age of revolution in microbiome research, we propose a pivotal role of “leaky gum”, as an analogy of “leaky gut”, to underscore the importance of the oral cavity in systemic health. The oral cavity has unique structures, the gingival sulcus (GS) and the junctional epithelium (JE) below the GS, which are rarely found anywhere else in our body. The JE is attached to the tooth enamel and cementum by hemidesmosome (HD), which is structurally weaker than desmosome and is, thus, vulnerable to microbial infiltration. In the GS, microbial biofilms can build up for life, unlike the biofilms on the skin and intestinal mucosa that fall off by the natural process. Thus, we emphasize that the GS and the JE are the weakest leaky point for microbes to invade the human body, making the leaky gum just as important as, or even more important than, the leaky gut.

Porphyromonas gingivalis Induces Increases in Branched-Chain Amino Acid Levels and Exacerbates Liver Injury Through livh/livk

Porphyromonas gingivalis, a keystone periodontal pathogen, has emerged as a risk factor for systemic chronic diseases, including non-alcoholic fatty liver disease (NAFLD). To clarify the mechanism by which this pathogen induces such diseases, we simultaneously analyzed the transcriptome of intracellular P. gingivalis and infected host cells via dual RNA sequencing. Pathway analysis was also performed to determine the differentially expressed genes in the infected cells. Further, the infection-induced notable expression of P. gingivalis livk and livh genes, which participate in branched-chain amino acid (BCAA) transfer, was also analyzed. Furthermore, given that the results of recent studies have associated NAFLD progression with elevated serum BCAA levels, which reportedly, are upregulated by P. gingivalis, we hypothesized that this pathogen may induce increases in serum BCAA levels and exacerbate liver injury via livh/livk. To verify this hypothesis, we constructed P. gingivalis livh/livk-deficient strains (Δlivk, Δlivh) and established a high-fat diet (HFD)-fed murine model infected with P. gingivalis. Thereafter, the kinetic growth and exopolysaccharide (EPS) production rates as well as the invasion efficiency and in vivo colonization of the mutant strains were compared with those of the parental strain. The serum BCAA and fasting glucose levels of the mice infected with either the wild-type or mutant strains, as well as their liver function were also further investigated. It was observed that P. gingivalis infection enhanced serum BCAA levels and aggravated liver injury in the HFD-fed mice. Additionally, livh deletion had no effect on bacterial growth, EPS production, invasion efficiency, and in vivo colonization, whereas the Δlivk strain showed a slight decrease in invasion efficiency and in vivo colonization. More importantly, however, both the Δlivk and Δlivh strains showed impaired ability to upregulate serum BCAA levels or exacerbate liver injury in HFD-fed mice. Overall, these results suggested that P. gingivalis possibly aggravates NAFLD progression in HFD-fed mice by increasing serum BCAA levels, and this effect showed dependency on the bacterial BCAA transport system.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.

Porphyromonas gingivalis-Induced Cognitive Impairment Is Associated With Gut Dysbiosis, Neuroinflammation, and Glymphatic Dysfunction

Background

Periodontal pathogen and gut microbiota are closely associated with the pathogenesis of Alzheimer's disease (AD). Porphyromonas gingivalis (Pg), the keystone periodontal pathogen, can induce cognitive impairment. The gut has a connection and communication with the brain, which is an important aspect of the gut-brain axis (GBA). In the present study, we investigate whether Pg induces cognitive impairment through disturbing the GBA.

Methods

In this study, Pg was orally administered to mice, three times a week for 1 month. The effects of Pg administration on the gut and brain were evaluated through behaviors, gut microbiota, immune cells, glymphatic pathway clearance, and neuroinflammation.

Results

Pg induced cognitive impairment and dysbiosis of gut microbiota. The α-diversity parameters did not show significant change after Pg administration. The β-diversity demonstrated that the gut microbiota compositions were different between the Pg-administered and control groups. At the species level, the Pg group displayed a lower abundance of Parabacteroides gordonii and Ruminococcus callidus than the control group, but a higher abundance of Mucispirillum schaedleri. The proportions of lymphocytes in the periphery and myeloid cells infiltrating the brain were increased in Pg-treated animals. In addition, the solute clearance efficiency of the glymphatic system decreased. Neurons in the hippocampus and cortex regions were reduced in mice treated with Pg. Microglia, astrocytes, and apoptotic cells were increased. Furthermore, amyloid plaque appeared in the hippocampus and cortex regions in Pg-treated mice.

Conclusions

These findings indicate that Pg may play an important role in gut dysbiosis, neuroinflammation, and glymphatic system impairment, which may in turn lead to cognitive impairment.

Beneficial effects of a mouthwash containing an antiviral phthalocyanine derivative on the length of hospital stay for COVID-19: randomised trial

The risk of contamination and dissemination by SARS-CoV-2 has a strong link with nasal, oral and pharyngeal cavities. Recently, our research group observed the promising performance of an anionic phthalocyanine derivative (APD) used in a mouthwash protocol without photoexcitation; this protocol improved the general clinical condition of patients infected with SARS-CoV-2. The present two-arm study evaluated in vitro the antiviral activity and cytotoxicity of APD. Additionally, a triple-blind randomized controlled trial was conducted with 41 hospitalized patients who tested positive for COVID-19. All the included patients received World Health Organization standard care hospital treatment (non-intensive care) plus active mouthwash (experimental group AM/n = 20) or nonactive mouthwash (control group NAM/n = 21). The adjunct mouthwash intervention protocol used in both groups consisted one-minute gargling/rinsing / 5 times/day until hospital discharge. Groups were compared considering age, number of comorbidities, duration of symptoms prior admission and length of hospital stay (LOS). The associations between group and sex, age range, presence of comorbidities, admission to Intensive care unit (ICU) and death were also evaluated. The in vitro evaluation demonstrated that APD compound was highly effective for reduction of SARS-CoV-2 viral load in the 1.0 mg/mL (99.96%) to 0.125 mg/mL (92.65%) range without causing cytotoxicity. Regarding the clinical trial, the median LOS of the AM group was significantly shortened (4 days) compared with that of the NAM group (7 days) (p = 0.0314). Additionally, gargling/rinsing with APD was very helpful in reducing the severity of symptoms (no ICU care was needed) compared to not gargling/rinsing with APD (28.6% of the patients in the NAM group needed ICU care, and 50% of this ICU subgroup passed way, p = 0.0207). This study indicated that the mechanical action of the protocol involving mouthwash containing a compound with antiviral effects against SARS-CoV-2 may reduce the symptoms of the patients and the spread of infection. The use of APD in a mouthwash as an adjuvant the hospital COVID-19 treatment presented no contraindication and reduced the hospital stay period.

Trial registration: The clinical study was registered at REBEC—Brazilian Clinical Trial Register (RBR-58ftdj).

Saliva and Plasma Reflect Metabolism Altered by Diabetes and Periodontitis

Periodontitis is an inflammatory disorder caused by disintegration of the balance between the periodontal microbiome and host response. While growing evidence suggests links between periodontitis and various metabolic disorders including type 2 diabetes (T2D), non-alcoholic liver disease, and cardiovascular disease (CVD), which often coexist in individuals with abdominal obesity, factors linking periodontal inflammation to common metabolic alterations remain to be fully elucidated. More detailed characterization of metabolomic profiles associated with multiple oral and cardiometabolic traits may provide better understanding of the complexity of oral-systemic crosstalk and its underlying mechanism. We performed comprehensive profiling of plasma and salivary metabolomes using untargeted gas chromatography/mass spectrometry to investigate multivariate covariation with clinical markers of oral and systemic health in 31 T2D patients with metabolic comorbidities and 30 control subjects. Orthogonal partial least squares (OPLS) results enabled more accurate characterization of associations among 11 oral and 25 systemic clinical outcomes, and 143 salivary and 78 plasma metabolites. In particular, metabolites that reflect cardiometabolic changes were identified in both plasma and saliva, with plasma and salivary ratios of (mannose + allose):1,5-anhydroglucitol achieving areas under the curve of 0.99 and 0.92, respectively, for T2D diagnosis. Additionally, OPLS analysis of periodontal inflamed surface area (PISA) as the numerical response variable revealed shared and unique responses of metabolomic and clinical markers to PISA between healthy and T2D groups. When combined with linear regression models, we found a significant correlation between PISA and multiple metabolites in both groups, including threonate, cadaverine and hydrocinnamate in saliva, as well as lactate and pentadecanoic acid in plasma, of which plasma lactate showed a predominant trend in the healthy group. Unique metabolites associated with PISA in the T2D group included plasma phosphate and salivary malate, while those in the healthy group included plasma gluconate and salivary adenosine. Remarkably, higher PISA was correlated with altered hepatic lipid metabolism in both groups, including higher levels of triglycerides, aspartate aminotransferase and alanine aminotransferase, leading to increased risk of cardiometabolic disease based on a score summarizing levels of CVD-related biomarkers. These findings revealed the potential utility of saliva for evaluating the risk of metabolic disorders without need for a blood test, and provide evidence that disrupted liver lipid metabolism may underlie the link between periodontitis and cardiometabolic disease.

Outer membrane vesicles of Porphyromonas gingivalis: Novel communication tool and strategy

Extracellular vesicles (EVs) have been recognized as a universal method of cellular communications and are reportedly produced in bacteria, archaea, and eukaryotes. Bacterial EVs are often called “Outer Membrane Vesicles” (OMVs) as they were the result of a controlled blebbing of the outer membrane of gram-negative bacteria such as Porphyromonas gingivalis (P. gingivalis). Bacterial EVs are natural messengers, implicated in intra- and inter-species cell-to-cell communication among microorganism populations present in microbiota. Bacteria can incorporate their pathogens into OMVs; the content of OMVs differs, depending on the type of bacteria. The production of distinct types of OMVs can be mediated by different factors and routes. A recent study highlighted OMVs ability to carry crucial molecules implicated in immune modulation, and, nowadays, they are considered as a way to communicate and transfer messages from the bacteria to the host and vice versa. This review article focuses on the current understanding of OMVs produced from major oral bacteria, P. gingivalis: generation, characteristics, and contents as well as the involvement in signal transduction of host cells and systemic diseases. Our recent study regarding the action of P. gingivalis OMVs in the living body is also summarized.

Exposure to Porphyromonas gingivalis and Modifiable Risk Factors Modulate Risk for Early Diabetic Retinopathy

Purpose

We hypothesized that exposure to Porphyromonas gingivalis (Pg) increases the risk for early diabetic retinopathy (DR) and that the risk can be modulated.

Methods

We identified 116 early DR cases, and 116 non-DR controls were selected randomly by frequency matching for age, sex, race, and education from the US Third National Health and Nutrition Examination Survey. DR was assessed using non-mydriatic fundus photographs and graded by trained graders using the Modified Airlie House Classification scheme and the Early Treatment for Diabetic Retinopathy Study severity scale. Serum Pg immunoglobulin G (IgG) antibody (Ab) was measured in enzyme-linked immunosorbent assay units. Logistic regression was used to relate serum Pg IgG Ab levels to the risk for early DR.

Results

Per tenfold increase in Pg IgG Ab levels, there was an over 60% increased risk for early DR (odds ratio = 1.64; 95% confidence interval, 1.36–1.97), and a linear trend was noted for the estimated probabilities of early DR at various Pg IgG Ab levels (P for trend = 0.0053). The analysis also suggested that moderate alcohol consumption (less than 12 drinks in the past 12 months; P for interaction = 0.0003) and maintaining a normal serum glycated hemoglobulin level (HbA1c ≤ 5.7%; P for interaction < 0.0001) helped reduce the Pg-related DR risk.

Conclusions

The increased Pg-related DR risk could be alleviated by managing alcohol consumption and maintaining a normal blood glucose level.

Translational Relevance

Findings from this study provide new directions for developing novel therapeutics and prevention strategies for DR.

Local and systemic mechanisms linking periodontal disease and inflammatory comorbidities

Periodontitis, a major inflammatory disease of the oral mucosa, is epidemiologically associated with other chronic inflammation-driven disorders, including cardio-metabolic, neurodegenerative and autoimmune diseases and cancer. Emerging evidence from interventional studies indicates that local treatment of periodontitis ameliorates surrogate markers of comorbid conditions. The potential causal link between periodontitis and its comorbidities is further strengthened by recent experimental animal studies establishing biologically plausible and clinically consistent mechanisms whereby periodontitis could initiate or aggravate a comorbid condition. This multi-faceted ‘mechanistic causality’ aspect of the link between periodontitis and comorbidities is the focus of this Review. Understanding how certain extra-oral pathologies are affected by disseminated periodontal pathogens and periodontitis-associated systemic inflammation, including adaptation of bone marrow haematopoietic progenitors, may provide new therapeutic options to reduce the risk of periodontitis-associated comorbidities.

Periodontitis has been causally linked to the development of other chronic inflammatory diseases outside the oral mucosa. In this Review, George Hajishengallis and Triantafyllos Chavakis consider the molecular basis of these links.

Isoleucine increases muscle mass through promoting myogenesis and intramyocellular fat deposition

Isoleucine (Ile), as a branched-chain amino acid (BCAA), has a vital role in regulating body weight and muscle protein synthesis. However, the regulatory effect of Ile on muscle mass under high-fat diet (HFD) conditions and intramyocellular lipid deposition remains largely unclear. In this study, a feeding experiment with HFD with or without 25 g L^-1 Ile was performed using 32 wild male C57BL/6J mice randomly divided into two groups. The results showed that Ile significantly increased both muscle and fat mass, as well as causing insulin resistance and meanwhile upregulating the levels of key adipogenic and myogenic proteins. More importantly, Ile damaged the mitochondrial function by vacuolation, swelling and cristae fracture in the gastrocnemius (GAS) and tibialis anterior (TA) with downregulation of mitochondrial function-related genes. Furthermore, Ile promoted myogenesis and more lipid droplet accumulation in myotubes. Compared with the control, the protein levels of myosin heavy chain (MyHC), myoblast determination protein 1 (MyoD), myogenin (MyoG), peroxisome proliferator-activated receptor gamma (PPARg) and fatty acid synthase (FAS) were upregulated in the Ile group, whereas the protein levels of adipose triglyceride lipase (ATGL) and lipoprotein lipase (LPL) were downregulated. Collectively, Ile increased muscle mass through myogenesis and intramyocellular lipid deposition. Our findings provide a new perspective for not only improving the lean juiciness of farm animals by increasing intramyocellular lipid accumulation, but also modulating myopathies under obesity.

Porphyromonas gingivalis and Its Systemic Impact: Current Status

The relationship between periodontitis and systemic diseases, notably including atherosclerosis and diabetes, has been studied for several years. Porphyromonas gingivalis, a prominent component of oral microorganism communities, is the main pathogen that causes periodontitis. As a result of the extensive analysis of this organism, the evidence of its connection to systemic diseases has become more apparent over the last decade. A significant amount of research has explored the role of Porphyromonas gingivalis in atherosclerosis, Alzheimer's disease, rheumatoid arthritis, diabetes, and adverse pregnancy outcomes, while relatively few studies have examined its contribution to respiratory diseases, nonalcoholic fatty liver disease, and depression. Here, we provide an overview of the current state of knowledge about Porphyromonas gingivalis and its systemic impact in an aim to inform readers of the existing epidemiological evidence and the most recent preclinical studies. Additionally, the possible mechanisms by which Porphyromonas gingivalis is involved in the onset or exacerbation of diseases, together with its effects on systemic health, are covered. Although a few results remain controversial, it is now evident that Porphyromonas gingivalis should be regarded as a modifiable factor for several diseases.

Modeling Diet-Induced Metabolic Syndrome in Rodents

Standardized animal models represent one of the most valuable tools available to understand the mechanism underlying the metabolic syndrome (MetS) and to seek for new therapeutic strategies. However, there is considerable variability in the studies conducted with this essential purpose. This review presents an updated discussion of the most recent studies using diverse experimental conditions to induce MetS in rodents with unbalanced diets, discusses the key findings in metabolic outcomes, and critically evaluates what we have been learned from them and how to advance in the field. The study includes scientific reports sourced from the Web of Science and PubMed databases, published between January 2013 and June 2020, which used hypercaloric diets to induce metabolic disorders, and address the impact of the diet on metabolic parameters. The collected data are used as support to discuss variables such as sex, species, and age of the animals, the most favorable type of diet, and the ideal diet length to generate metabolic changes. The experimental characteristics propose herein improve the performance of a preclinical model that resembles the human MetS and will guide researchers to investigate new therapeutic alternatives with confidence and higher translational validity.

[Research progress of correlation between periodontal pathogens and systemic diseases]

Periodontal pathogens are the main pathogenic factor of periodontitis. Periodontal pathogens have a large variety of virulence factors such as lipopolysaccharide, fimbriae and proteases, which enables the pathogens to infect periodontal tissues and stimulate the secretion of inflammatory cytokines, causing chronic systemic inflammation. Periodontal pathogens may invade multiple systems such as the circulatory system, immune system, respiratory system and digestive system to cause systematic diseases. Recent studies have shown that periodontal pathogens may have close relations with systemic diseases such as cardiovascular disease, diabetes, rheumatoid arthritis, and cancer. Among the periodontal pathogens, Porphyromonas gingivalis can be found in atherosclerotic plaques to impairing the function of the vascular endothelium; Porphyromonas gingivalis may also increase the level of inflammatory factors such as TNF-α to promote insulin resistance and diabetes. Many of the periodontal pathogens such as Porphyromonas gingivalis, Tannerella forsythia and Prevotella intermedia can be detected in the synovial fluid of rheumatoid arthritis patients, suggesting their involvement in the pathogenesis of rheumatoid arthritis. Fusobacterium nucleatum may cause alterations in the intestinal microbiome in mice and promote the occurrence of intestinal tumors. Herein we review the recent progresses in the relationship between periodontal pathogens and systemic diseases.