Review: Pathogen-induced inflammation at sites distant from oral infection: bacterial persistence and induction of cell-specific innate immune inflammatory pathways

Carcinogenetic mechanisms employed by the oral microbiome: A narrative review

Cancers of the oral cavity, lip, salivary gland, and oropharynx cause substantial global disease burden. While tobacco-use and alcohol use are highly associated with oral cancers, the rising incidence of disease in patients who do not use tobacco or alcohol points to additional carcinogenic risk factors. Chronic inflammation, disruption of the oral microbiome, and dysbiosis are becoming more widely implicated in the pathogenesis of oral cancer. Several studies have identified specific bacterial species enriched in patients with oral cancer, including Porphyromonas gingivalis and Fusobacterium nucleatum. In this narrative review, we describe potential carcinogenic mechanisms exhibited by these species and other microbes in the development of oral cancer.

Porphyromonas gingivalis outer membrane vesicles divert host innate immunity and promote inflammation via C4' monophosphorylated lipid A

Porphyromonas gingivalis (Pg) is a prevalent pathogen that promotes human periodontal disease (PD) and exacerbates systemic comorbidities such as atherosclerosis, rheumatoid arthritis, and Alzheimer's disease. Pg produces nonphosphorylated tetra-acylated lipid A (NPLA) in its outer membrane (OM) that evades host Toll-like receptor 4 (TLR4), inflammasome pathways, and cationic peptides, enhancing bacterial survival. Here, we show that Pg also releases outer membrane vesicles (OMVs) that engage and divert host cell TLR4, inflammasome, and LL-37 responses away from the microbe. We determined that Pg OMVs are enriched for C4' monophosphoryl lipid A (C4'-MPLA), an established agonist for TLR4-TRIF-IFNβ and inflammasome-IL-1β responses. Comparisons of Pg 381 and Pg 33277 stationary phase cultures revealed higher OMV production by Pg 381, which correlates with its higher proinflammatory pathogenicity. The cationic peptide, polymyxin B (PMB), which selectively binds lipid A C4'-phosphate, reduces OMV-stimulated HEK cell TLR4 activation and THP-1 cell IL-1β production, confirming the proinflammatory role for OMV-C4'-MPLA. Similar to PMB, the host defense peptide, LL-37, inhibits OMV-C4'-MPLA-dependent HEK cell TLR4 activation. PMB and LL-37 also blocked OMV-C4'-MPLA-driven TLR4 activation in human umbilical vein endothelial cells. Finally, wild-type Pg-containing OM-NPLA is highly resistant to LL-37 antimicrobial activity, whereas the ΔlpxF mutant bacterium, retaining OM-C4'-MPLA, is killed by the peptide. In summary, Pg escapes host TLR4 signaling, inflammasome activation, and LL-37 interaction by retaining immunoevasive OM-NPLA. Moreover, Pg dispenses proinflammatory OMV-C4'-MPLA, which engages and redirects those host defenses. We suggest that OMV-C4'-MPLA triggers elevated IFNβ and IL-1β cytokines, which typify PD comorbidities, and drive PD-related alveolar bone loss.

Association of periodontal disease with the prognosis of chronic kidney disease: A meta-analysis

BACKGROUND

To assess the association between periodontal disease (PD) and the prognosis of chronic kidney disease (CKD).

METHODS

A systematic literature search was conducted using PubMed, Embase, and Cochrane Library to identify eligible cohort studies until April 2023. Relative risk (RR) with a 95% CI was used to evaluate the strength of the relationship between PD and CKD prognosis using the random-effects model.

RESULTS

Ten cohort studies involving 10 144 patients with CKD were selected for the meta-analysis. The summary results indicated that PD was associated with an increased risk of all-cause mortality in patients with CKD (RR: 1.32; 95% CI, 1.10-1.59; p = 0.003). Although no association was observed between PD and the risk of cardiac death in patients with CKD ( p = 0.180), while sensitivity analysis revealed PD may be associated with the risk of cardiac death (RR: 1.31; 95% CI, 1.05-1.64; p = 0.017). In addition, subgroup analyses revealed that the strength of the association of PD with the risks of all-cause mortality and cardiac death varies when stratified by region, sex, and CKD stage.

CONCLUSION

PD might exert a harmful effect on the risk of all-cause mortality, with a potential but unconfirmed association with cardiac death in patients with CKD.

Lipid a remodeling modulates outer membrane vesicle biogenesis by Porphyromonas gingivalis

Outer membrane vesicles (OMVs) are small membrane enclosed sacs released from bacteria which serve as carriers of biomolecules that shape interactions with the surrounding environment. The periodontal pathogen, Porphyromonas gingivalis, is a prolific OMV producer. Here, we investigated how the structure of lipid A, a core outer membrane molecule, influences P. gingivalis OMV production, OMV-dependent TLR4 activation, and biofilm formation. We examined mutant strains of P. gingivalis 33277 deficient for enzymes that alter lipid A phosphorylation and acylation status. The lipid A C4'-phosphatase (lpxF)-deficient strain and strains bearing inactivating point mutations in the LpxF active site displayed markedly reduced OMV production relative to WT. In contrast, strains deficient for either the lipid A C1-phosphatase (lpxE) or the lipid A deacylase (PGN_1123; lpxZ) genes did not display alterations in OMV abundance compared to WT. These data indicate that lipid A C4'-phosphate removal is required for typical OMV formation. In addition, OMVs produced by ΔlpxF and ΔlpxZ strains, possessing only penta-acylated lipid A, stimulated robust TLR4 activation, whereas OMVs obtained from WT and ΔlpxE strains, containing predominantly tetra-acylated lipid A, did not. Hence, lipid A remodeling modulates the capacity of OMVs to engage host TLR4-dependent immunity. Finally, we demonstrate an inverse relationship between OMV abundance and biofilm density, with the ∆lpxF mutants forming denser biofilms than either WT, ΔlpxE, or ΔlpxZ strains. Therefore, OMVs may also contribute to pathogenesis by regulating biofilm formation and dispersal.IMPORTANCEPorphyromonas gingivalis is a bacterium strongly associated with periodontitis. P. gingivalis exports lipids, proteins, and other biomolecules that contribute to the bacterium's ability to persist in inflammatory conditions encountered during disease. These biomolecules are exported through several mechanisms, including via outer membrane vesicles (OMVs). Despite their ubiquity, the mechanisms that drive outer membrane vesicle production vary among bacteria and are not fully understood. In this study, we report that C4' dephosphorylation of lipid A, a major outer membrane molecule, is required for robust outer membrane vesicle production and biological function in P. gingivalis. This finding adds to the growing body of evidence that lipid A structure is an important factor in outer membrane vesicle biogenesis in diverse bacterial species.

Estimation of Salivary Ferritin Levels in Subjects with Chronic Periodontitis with Type 2 Diabetes Mellitus

BACKGROUND

Ferritin is an iron storage protein essential for iron homeostasis regulation and an indicator of iron stores. It is an acute phase reactant and is elevated in inflammation and chronic infection. Periodontitis is a chronic inflammatory disease with periodontopathogens possessing haemolytic activity which leads to increased local iron concentration and iron disorder. Inflammation and excess systemic iron are mediating risk factors of type 2 diabetes mellitus.

AIM

To evaluate and compare the salivary ferritin levels in subjects with chronic periodontitis with and without type 2 diabetes mellitus.

METHODOLOGY

Unstimulated saliva sample was collected by standardized spitting technique from 45 individuals, aged between 30 and 65 years divided into three groups. Group I-Healthy individuals, Group II-Subjects with chronic periodontitis with type 2 diabetes mellitus, Group III-Subjects with chronic periodontitis without type 2 diabetes mellitus. The salivary ferritin levels are analysed using latex-enhanced turbidimetric assay in an autoanalyzer.

RESULTS

The salivary ferritin level was elevated in chronic periodontitis with type 2 diabetes mellitus (Group II) and in chronic periodontitis without type 2 diabetes mellitus (Group III).

Association between gingivitis, tooth loss and cardiovascular risk: Insights from a 10-year nationwide cohort study of 3.7 million Koreans

BACKGROUND

While studies have suggested an association between periodontal disease and an increased risk of cardiovascular disease, the strength of this association and its specific links to various types of cardiovascular disease have not been thoroughly investigated. This study aimed to examine how gingivitis and tooth loss affect cardiovascular diseases, probing their individual impacts.

METHODS

A retrospective cohort study was conducted, encompassing 3,779,490 individuals with no history of cardiovascular disease, utilizing data from the National Health Examination and the Korean National Health Insurance database from 2006 to 2019. Cox proportional hazards models were applied to estimate the association between tooth loss, gingivitis, and cardiovascular disease.

RESULTS

Following a median follow-up of 10.38 years, 17,942 new cardiovascular disease cases were identified, comprising 10,224 cases of angina pectoris, 6,182 cases of acute myocardial infarction, and 9,536 cases of stroke. It was observed that the risk of stroke was significantly higher in the tooth loss group compared to the control group (adjusted hazard ratio [aHR]: 1.09, 95% confidence interval [CI]: 1.04-1.15). In the group with gingivitis and tooth loss, the risk of stroke and cardiovascular disease was significantly higher than in the control group (aHR: 1.12, 95% CI: 1.04-1.20; aHR: 1.08, 95% CI: 1.03-1.14). The gingivitis group exhibited a higher risk associated with stroke (aHR: 1.05, 95% CI: 1.01-1.10) among individuals aged 50 and above. However, statistically significant associations between periodontal disease and angina pectoris were not observed, nor between periodontal disease and acute myocardial infarction except among those aged above 50. Furthermore, the association between periodontal disease and cardiovascular disease was found to be stronger among individuals over the age of 50, males, those with obesity, and smokers compared to the control group.

CONCLUSIONS

Our results emphasize the association of tooth loss and gingivitis with cardiovascular disease, specifically stroke, underlining the critical need for preventive oral healthcare. Tailored interventions are necessary to reduce the heightened risk of cardiovascular disease events, especially stroke, among older, obese individuals and smokers.

Evaluating the impact of oral hygiene instruction and digital oral health education within cardiac rehabilitation clinics: A protocol for a novel, dual centre, parallel randomised controlled trial

INTRODUCTION

Diseases of the periodontal tissues including gingivitis and periodontitis can affect up to 90% and 50% of the population respectively. These conditions are multifactorial inflammatory conditions involving a dysbiotic biofilm that, if left untreated, can lead to the destruction of the supporting structures of the teeth and have significant systemic implications, specifically on cardiovascular health. The elevation of inflammatory markers, particularly high-sensitive C-reactive protein (hsCRP), are strongly associated with an increased risk of atherosclerosis, a key risk factor for cardiovascular disease (CVD). HsCRP as well as other inflammatory markers can be detected in blood samples as early as 21 days after ceasing toothbrushing, due to the immune response to stagnant oral biofilm. The most effective way to ensure oral biofilm cannot remain on oral tissues, thus preventing periodontitis and reducing inflammatory CVD risk, is with good oral hygiene. The primary aim of this study is to assess whether individualised oral hygiene instruction (OHI) partnered with a digital oral health education (DOHE) package can improve the oral health of patients living with CVD.

METHODS AND ANALYSIS

A total of 165 participants will be recruited from the Westmead and Blacktown Mt Druitt cardiac rehabilitation out-patient clinics into this dual centre, single blind, parallel design, randomised controlled trial. A baseline oral health clinical examination will be completed, followed by a self-report questionnaire before they are randomised in a 1:1:1 ratio into one of 3 arms as follows: individualised OHI partnered with DOHE (Group A), (Group B) DOHE only (Group B), and control/usual care (no oral health education) (Group C). Groups will have their intervention repeated at the 6-week follow-up. After completing the 12-week follow-up, Group B and Group C will receive tailored OHI. Group C will also receive the DOHE package. The primary outcome is the change in approximal plaque index score between baseline and 6-week follow up.

ETHICS AND DISSEMINATION

The study has been approved by the Western Sydney Local Health District Human Ethics Committee 2023/ETH00516. Results will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

ACTRN12623000449639p ANZCTR: https://www.anzctr.org.au/.

Oral health education strategies for patients living with cardiovascular disease within hospital settings: a scoping review

Objective

To identify and describe the impact of current oral health education programmes provided to patients in cardiology hospital wards and outpatient clinics.

Methods

This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis for Scoping Reviews statement. Searches were conducted using electronic databases: Cochrane, Medline, and Scopus, as well as grey literature searching.

Results

Three eligible studies were identified. All included studies reported generalised poor oral health in their participants at baseline, with significant improvement at follow-up. They all reported significant reductions in plaque deposits and gingival bleeding. One study reported significantly less bacteria on participant tongues, as well as fewer days with post-operative atrial fibrillation in the intervention group. Furthermore, in this study, one patient in the intervention group developed pneumonia, whilst four patients in the control group did.

Conclusion

Oral health education for patients with cardiovascular disease is limited and many have poor oral health. Educational programmes to improve oral health behaviours in patients with cardiovascular disease can improve both oral and general health outcomes.

Implications for public health

Oral disease is a modifiable risk factor for cardiovascular disease. Integrating oral health education into cardiology hospital settings is a simple strategy to improve access to oral health information and improve both oral and cardiovascular outcomes.

Lifestyle Medicine for the Prevention and Treatment of Pancreatitis and Pancreatic Cancer

The incidence of pancreatitis and pancreatic cancer is on the upswing in the USA. These conditions often lead to higher healthcare costs due to the complex nature of diagnosis and the need for specialized medical interventions, surgical procedures, and prolonged medical management. The economic ramification encompasses direct healthcare expenses and indirect costs related to productivity losses, disability, and potential long-term care requirements. Increasing evidence underscores the importance of a healthy lifestyle in preventing and managing these conditions. Lifestyle medicine employs evidence-based interventions to promote health through six key pillars: embracing a whole-food, plant-predominant dietary pattern; regular physical activity; ensuring restorative sleep; managing stress effectively; removing harmful substances; and fostering positive social connections. This review provides a comprehensive overview of lifestyle interventions for managing and preventing the development of pancreatitis and pancreatic cancer.

Exploring the presence of oral bacteria in non-oral sites of patients with cardiovascular diseases using whole metagenomic data

Cardiovascular diseases (CVDs) encompass various conditions affecting the heart and its blood vessels and are often linked with oral microbes. Our data analysis aimed to identify oral bacteria from other non-oral sites (i.e., gut, arterial plaque and cultured blood) that could be linked with CVDs. Taxonomic profiling identified bacteria to the species level and compared with the Human Oral Microbiome Database (HOMD). The oral bacteria in the gut, cultured blood and arterial plaque samples were catalogued, with their average frequency calculated for each sample. Additionally, data were filtered by comparison with the Human Microbiome Project (HMP) database. We identified 17,243 microbial species, of which 410 were present in the HOMD database and further denominated as "oral", and were found in at least one gut sample, but only 221 and 169 species were identified in the cultured blood and plaque samples, respectively. Of the 410 species, 153 were present solely in oral-associated environments after comparison with the HMP database, irrespective of their presence in other body sites. Our results suggest a potential connection between the presence of specific species of oral bacterial and occurrence of CVDs. Detecting these oral bacterial species in non-oral sites of patients with CVDs could help uncover the link between oral health and general health, including cardiovascular conditions via bacterial translocation.

Lipidomic analysis of Porphyromonas gingivalis reveals novel glycerol bisphosphoceramide, phosphatidyl-, and phosphoglycerol dipeptide lipid families

Porphyromonas gingivalis, like other members of the phylum Bacteroidetes (synonym Bacteroidota), synthesizes several classes of dihydroceramides and peptidolipids. Using a similar strategy as that recently used to delimit the lipidome of its close relative Bacteroides fragilis, we applied linear ion trap multiple-stage mass spectrometry (linear ion trap MSn) with high-resolution mass spectrometry, to structurally characterize the complete lipidome of P. gingivalis and compare it to B. fragilis. This analysis discovered that the P. gingivalis lipidome consists of several previously unidentified lipid families, including dihydroceramide-1-phosphophate, acylated dihydroceramide-1-phosphophate, phosphoglycerol glycylserine lipid, and bis(phosphodihydroceramide) glycerol. Interestingly, we also found a novel sphingolipid family containing a polyunsaturated long-chain base, and a new lipoglycylserine phosphatic acid containing unsaturated acyl chains not reported for the lipid family. The comprehensive coverage of the lipidome of P. gingivalis conducted in this study has revealed more than 140 lipid species including several novel lipids in over 20 lipid families/subfamilies.

Quantitative Evaluation of Periodontitis for Predicting the Occurrence of Postoperative Pneumonia After Oncologic Esophagectomy

BACKGROUND

Periodontitis is a biofilm-associated inflammatory periodontal disease associated with postoperative complications after esophagectomy. However, few studies have evaluated the inflammatory burden posed by periodontitis quantitively for patients undergoing oncologic esophagectomy. This study aimed to clarify the relationship between periodontitis and postoperative pneumonia using periodontal inflammatory surface area (PISA).

METHODS

The study analyzed 251 patients who underwent esophagectomy for esophageal cancer. The patients were classified into low-PISA and high-PISA groups according to preoperative PISA, and the relationship between the occurrence and severity of postoperative pneumonia was investigated.

RESULTS

The high-PISA group (n = 69) included more males (P < 0.001) and patients with poor performance status (P < 0.024). Postoperative pneumonia occurred more frequently in the high-PISA group than in the low-PISA group (31.9 % vs. 15.9 %; P = 0.008), whereas the incidences of other complications did not differ significantly. In addition, the incidence of severe pneumonia was significantly higher in the high-PISA group (7.2 % vs. 1.6 %; P = 0.038). In the multivariable analysis for adjustment of preoperative confounders, age older than 70 years (odds ratio [OR], 2.62; P = 0.006), high PISA (OR, 2.45; P = 0.012), and smoking history (OR, 2.78; P = 0.006) were the independent variables predicting postoperative pneumonia.

CONCLUSION

Preoperative higher PISA was significantly associated with the occurrence of overall and severe postoperative pneumonia. The quantitative evaluation of periodontitis using PISA is a useful measure for predicting postoperative pneumonia, and intensive periodontal intervention may contribute to decreasing postoperative pneumonia.

The Roles of Periodontal Bacteria in Atherosclerosis

Atherosclerosis (AS) is an inflammatory vascular disease that constitutes a major underlying cause of cardiovascular diseases (CVD) and stroke. Infection is a contributing risk factor for AS. Epidemiological evidence has implicated individuals afflicted by periodontitis displaying an increased susceptibility to AS and CVD. This review concisely outlines several prevalent periodontal pathogens identified within atherosclerotic plaques, including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum. We review the existing epidemiological evidence elucidating the association between these pathogens and AS-related diseases, and the diverse mechanisms for which these pathogens may engage in AS, such as endothelial barrier disruption, immune system activation, facilitation of monocyte adhesion and aggregation, and promotion of foam cell formation, all of which contribute to the progression and destabilization of atherosclerotic plaques. Notably, the intricate interplay among bacteria underscores the complex impact of periodontitis on AS. In conclusion, advancing our understanding of the relationship between periodontal pathogens and AS will undoubtedly offer invaluable insights and potential therapeutic avenues for the prevention and management of AS.

Antibodies to oral pathobionts and colon cancer risk in the CLUE I cohort study

Periodontitis has been associated with an increased risk for gastrointestinal cancers. The objective of our study was to investigate the association of antibodies to oral bacteria and the risk of colon cancer in a cohort setting. Using the CLUE I cohort, a prospective cohort initiated in 1974 in Washington County, Maryland, we conducted a nested case-control study to examine the association of levels of IgG antibodies to 11 oral bacterial species (13 total strains) with risk of colon cancer diagnosed a median of 16 years later (range: 1-26 years). Antibody response was measured using checkerboard immunoblotting assays. We included 200 colon cancer cases and 200 controls matched on age, sex, cigarette smoking status, time of blood draw and pipe or cigar smoking status. Controls were selected using incidence density sampling. Conditional logistic regression models were used to assess the association between antibody levels and colon cancer risk. In the overall analysis, we observed significant inverse associations for 6 of the 13 antibodies measured (P-trends <.05) and one positive association for antibody levels to Aggregatibacter actinomycetemcomitans (ATCC 29523; P-trend = .04). While we cannot rule out a role for periodontal disease in colon cancer risk, findings from our study suggest that a strong adaptive immune response may be associated with a lower risk of colon cancer. More studies will need to examine whether the positive associations we observed with antibodies to A. actinomycetemcomitans reflect a true causal association for this bacterium.

Impact of gut microbiome in the development and treatment of pancreatic cancer: Newer insights

The gut microbiome plays an important role in the variation of pharmacologic response. This aspect is especially important in the era of precision medicine, where understanding how and to what extent the gut microbiome interacts with drugs and their actions will be key to individualizing therapy. The impact of the composition of the gut microbiome on the efficacy of newer cancer therapies such as immune checkpoint inhibitors and chimeric antigen receptor T-cell treatment has become an active area of research. Pancreatic adenocarcinoma (PAC) has a poor prognosis even in those with potentially resectable disease, and treatment options are very limited. Newer studies have concluded that there is a synergistic effect for immunotherapy in combination with cytotoxic drugs, in the treatment of PAC. A variety of commensal microbiota can affect the efficacy of conventional chemotherapy and immunotherapy by modulating the tumor microenvironment in the treatment of PAC. This review will provide newer insights on the impact that alterations made in the gut microbial system have in the development and treatment of PAC.

Microbiota Regulates Pancreatic Cancer Carcinogenesis through Altered Immune Response

The microbiota is present in many parts of the human body and plays essential roles. The most typical case is the occurrence and development of cancer. Pancreatic cancer (PC), one of the most aggressive and lethal types of cancer, has recently attracted the attention of researchers. Recent research has revealed that the microbiota regulates PC carcinogenesis via an altered immune response. Specifically, the microbiota, in several sites, including the oral cavity, gastrointestinal tract, and pancreatic tissue, along with the numerous small molecules and metabolites it produces, influences cancer progression and treatment by activating oncogenic signaling, enhancing oncogenic metabolic pathways, altering cancer cell proliferation, and triggering chronic inflammation that suppresses tumor immunity. Diagnostics and treatments based on or in combination with the microbiota offer novel insights to improve efficiency compared with existing therapies.

Correlation Between Chronic Periodontitis and Lung Cancer: A Systematic Review With Meta-Analysis

Periodontal disease is associated with many systemic diseases, such as cardiovascular diseases, atherosclerosis, diabetes mellitus, stroke, and pulmonary diseases. Interestingly, recent literature suggests that periodontal disease might be a risk factor for various cancers such as lung, colon, oesophageal, head, and neck cancers. However, the precise mechanistic link is lacking. Hence, in this meta-analysis, we aimed to investigate the correlation between periodontal disease and lung cancer in periodontally diseased patients. Data were searched for relevant studies from 2010 to 2022. We correlated periodontal disease and lung cancer based on adjusted ORs/HRs and associated CIs. I2 statistic was used to assess statistical heterogeneity. Publication bias was analyzed by visually inspecting the symmetry of the funnel plot and Egger's test. The study is registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration no: CRD42023390819). A total of 194,850 participants from observational studies (two case-control studies and five cohort studies) were incorporated for the current analysis. The meta-analysis of included studies showed an overall effect size (risk ratio) of the periodontal disease group with respect to the non-periodontal disease group for lung neoplasm to be 1.41 (95% CI: 1.32-1.52). The value was more than 1, indicating that the periodontal disease group had a relatively higher lung cancer prevalence than the non-periodontal disease group. Further, the overall risk ratio was found to be statistically significant (p<0.00001). Moreover, the funnel plot suggested some degree of publication bias. Evidence in our study implicated that there is an increased risk of occurrence of lung cancer in chronic periodontitis patients.

Stimulation of Human Periodontal Ligament Fibroblasts Using Purified Dentilisin Extracted from Treponema denticola

Periodontal disease is a chronic multifactorial disease triggered by a complex of bacterial species. These interact with host tissues to cause the release of a broad array of pro-inflammatory cytokines, chemokines, and tissue remodelers, such as matrix metalloproteinases (MMPs), which lead to the destruction of periodontal tissues. Patients with severe forms of periodontitis are left with a persistent pro-inflammatory transcriptional profile throughout the periodontium, even after clinical intervention, leading to the destruction of teeth-supporting tissues. The oral spirochete, Treponema denticola , is consistently found at significantly elevated levels at sites with advanced periodontal disease. Of all T. denticola virulence factors that have been described, its chymotrypsin-like protease complex, also called dentilisin, has demonstrated a multitude of cytopathic effects consistent with periodontal disease pathogenesis, including alterations in cellular adhesion activity, degradation of various endogenous extracellular matrix-substrates, degradation of host chemokines and cytokines, and ectopic activation of host MMPs. Thus, the following model of T. denticola -human periodontal ligament cell interactions may provide new knowledge about the mechanisms that drive the chronicity of periodontal disease at the protein, transcriptional, and epigenetic levels, which could afford new putative therapeutic targets. This protocol was validated in: PLOS Pathog (2021), DOI: 10.1371/journal.ppat.1009311.

Prevalence of Microorganisms in Atherosclerotic Plaques of Coronary Arteries: A Systematic Review and Meta-Analysis

Background

In this systematic review and meta-analysis, the existence of pathogens in atherosclerotic plaques of coronary arteries was investigated in coronary arteries diseases (CAD) patients.

Methods

This study was designed and implemented up to 31 August 2020. The findings present according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) checklist. Two independent reviewers (I.RJ and S.H) performed a comprehensive search on four different English databases including PubMed, ISI, Scopus, and Embase. In order to assess the quality of the articles, a checklist prepared by The Joanna Briggs Institute (JBI) was used.

Results

Finally, 44 studies were selected. The prevalence of different microorganisms in coronary arteries were as follows: Aggregatibacter actinomycetemcomitans (46.2%), Campylobacter rectus (43.0%), Chlamydia pneumonia (42.8%), Cytomegalovirus (29.1%), Helicobacter pylori (18.9%), Herpes simplex virus type 1 (5.9%), Porphyromonas gingivalis (42.6%), Prevotella intermedia (47.6%), Tannerella forsythia (43.7%), and Treponema denticola (32.9%).

Conclusion

Based on the result of this meta-analysis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans are the most common microorganisms in atherosclerotic plaques of coronary arteries and may have an important role in the development of atherosclerosis.

Periodontal therapy for primary or secondary prevention of cardiovascular disease in people with periodontitis

BACKGROUND

There may be an association between periodontitis and cardiovascular disease (CVD); however, the evidence so far has been uncertain about whether periodontal therapy can help prevent CVD in people diagnosed with chronic periodontitis. This is the third update of a review originally published in 2014, and most recently updated in 2019. Although there is a new multidimensional staging and grading system for periodontitis, we have retained the label 'chronic periodontitis' in this version of the review since available studies are based on the previous classification system.

OBJECTIVES

To investigate the effects of periodontal therapy for primary or secondary prevention of CVD in people with chronic periodontitis.

SEARCH METHODS

An information specialist searched five bibliographic databases up to 17 November 2021 and additional search methods were used to identify published, unpublished, and ongoing studies. We also searched the Chinese BioMedical Literature Database, the China National Knowledge Infrastructure, the VIP database, and Sciencepaper Online to March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared active periodontal therapy to no periodontal treatment or a different periodontal treatment. We included studies of participants with a diagnosis of chronic periodontitis, either with CVD (secondary prevention studies) or without CVD (primary prevention studies).

DATA COLLECTION AND ANALYSIS

Two review authors carried out the study identification, data extraction, and 'Risk of bias' assessment independently and in duplicate. They resolved any discrepancies by discussion, or with a third review author. We adopted a formal pilot-tested data extraction form, and used the Cochrane tool to assess the risk of bias in the studies. We used GRADE criteria to assess the certainty of the evidence.

MAIN RESULTS

There are no new completed RCTs on this topic since we published our last update in 2019. We included two RCTs in the review. One study focused on the primary prevention of CVD, and the other addressed secondary prevention. We evaluated both as being at high risk of bias. Our primary outcomes of interest were death (all-cause and CVD-related) and all cardiovascular events, measured at one-year follow-up or longer. For primary prevention of CVD in participants with periodontitis and metabolic syndrome, one study (165 participants) provided very low-certainty evidence. There was only one death in the study; we were unable to determine whether scaling and root planning plus amoxicillin and metronidazole could reduce incidence of all-cause death (Peto odds ratio (OR) 7.48, 95% confidence interval (CI) 0.15 to 376.98), or all CVD-related death (Peto OR 7.48, 95% CI 0.15 to 376.98). We could not exclude the possibility that scaling and root planning plus amoxicillin and metronidazole could increase cardiovascular events (Peto OR 7.77, 95% CI 1.07 to 56.1) compared with supragingival scaling measured at 12-month follow-up. For secondary prevention of CVD, one pilot study randomised 303 participants to receive scaling and root planning plus oral hygiene instruction (periodontal treatment) or oral hygiene instruction plus a copy of radiographs and recommendation to follow-up with a dentist (community care). As cardiovascular events had been measured for different time periods of between 6 and 25 months, and only 37 participants were available with at least one-year follow-up, we did not consider the data to be sufficiently robust for inclusion in this review. The study did not evaluate all-cause death and all CVD-related death. We are unable to draw any conclusions about the effects of periodontal therapy on secondary prevention of CVD.

AUTHORS' CONCLUSIONS

For primary prevention of cardiovascular disease (CVD) in people diagnosed with periodontitis and metabolic syndrome, very low-certainty evidence was inconclusive about the effects of scaling and root planning plus antibiotics compared to supragingival scaling. There is no reliable evidence available regarding secondary prevention of CVD in people diagnosed with chronic periodontitis and CVD. Further trials are needed to reach conclusions about whether treatment for periodontal disease can help prevent occurrence or recurrence of CVD.

PET/CT imaging of CSF1R in a mouse model of tuberculosis

PURPOSE

Macrophages represent an essential means of sequestration and immune evasion for Mycobacterium tuberculosis. Pulmonary tuberculosis (TB) is characterized by dense collections of tissue-specific and recruited macrophages, both of which abundantly express CSF1R on their outer surface. 4-Cyano-N-(5-(1-(dimethylglycyl)piperidin-4-yl)-2',3',4',5'-tetrahydro-[1,1'-biphenyl]-2-yl)-1H-imidazole-2-carboxamide (JNJ-28312141) is a reported high affinity, CSF1R-selective antagonist. We report the radiosynthesis of 4-cyano-N-(5-(1-(N-methyl-N-([11C]methyl)glycyl)piperidin-4-yl)-2',3',4',5'-tetrahydro-[1,1'-biphenyl]-2-yl)-1H-imidazole-2-carboxamide ([11C]JNJ-28312141) and non-invasive detection of granulomatous and diffuse lesions in a mouse model of TB using positron emission tomography (PET).

METHODS

Nor-methyl-JNJ-28312141 precursor was radiolabeled with [11C]iodomethane to produce [11C]JNJ-28312141. PET/CT imaging was performed in the C3HeB/FeJ murine model of chronic pulmonary TB to co-localize radiotracer uptake with granulomatous lesions observed on CT. Additionally, CSF1R, Iba1 fluorescence immunohistochemistry was performed to co-localize CSF1R target with reactive macrophages in infected and healthy mice.

RESULTS

Radiosynthesis of [11C]JNJ-28312141 averaged a non-decay-corrected yield of 18.7 ± 2.1%, radiochemical purity of 99%, and specific activity averaging 658 ± 141 GBq/µmol at the end-of-synthesis. PET/CT imaging in healthy mice showed hepatobiliary [13.39-25.34% ID/g, percentage of injected dose per gram of tissue (ID/g)] and kidney uptake (12.35% ID/g) at 40-50 min post-injection. Infected mice showed focal pulmonary lesion uptake (5.58-12.49% ID/g), hepatobiliary uptake (15.30-40.50% ID/g), cervical node uptake, and renal uptake (11.66-29.33% ID/g). The ratio of infected lesioned lung/healthy lung uptake is 5.91:1, while the ratio of lesion uptake to adjacent infected radiolucent lung is 2.8:1. Pre-administration of 1 mg/kg of unlabeled JNJ-28312141 with [11C]JNJ-28312141 in infected animals resulted in substantial blockade. Fluorescence microscopy of infected and uninfected whole lung sections exclusively co-localized CSF1R staining with abundant Iba1 + macrophages. Healthy lung exhibited no CSF1R staining and very few Iba1 + macrophages.

CONCLUSION

[11C]JNJ-28312141 binds specifically to CSF1R + macrophages and delineates granulomatous foci of disease in a murine model of pulmonary TB.

A cross-sectional study assessing the relationship between non-alcoholic fatty liver disease and periodontal disease

The risk factors for non-alcoholic fatty liver disease (NAFLD) progression are not completely known. Porphyromonas gingivalis infection is a risk factor for systemic diseases. We investigated the association of P. gingivalis infection with the risk of non-alcoholic steatohepatitis progression. Here, hematological tests, periodontal examination, and saliva collection were performed for 164 patients with NAFLD. P. gingivalis was identified in saliva using polymerase chain reaction. Hepatic steatosis and stiffness were evaluated using vibration-controlled transient elastography (VCTE) and magnetic resonance imaging. In patients with NAFLD, P. gingivalis positivity (P. gingivalis ratio ≥ 0.01%) in saliva correlated with liver stiffness determined using magnetic resonance elastography (MRE; p < 0.0001). A P. gingivalis ratio of 0.01% corresponds to 100,000 cells/mL and indicates the proportion of P. gingivalis in the total number of bacteria in the oral cavity. Patients with NAFLD and advanced fibrosis on MRE showed significantly elevated endotoxin activity; those who had > 10 periodontal pockets with depths ≥ 4 mm had significantly increased hepatic stiffness on both VCTE and MRE.

Topical application of Porphyromonas gingivalis into the gingival pocket in mice leads to chronic‑active infection, periodontitis and systemic inflammation

Porphyromonas gingivalis (Pg), one of the 'red-complex' perio-pathogens known to play a critical role in the development of periodontitis, has been used in various animal models to mimic human bacteria-induced periodontitis. In order to achieve a more realistic animal model of human Pg infection, the present study investigated whether repeated small-volume topical applications of Pg directly into the gingival pocket can induce local infection, including periodontitis and systemic vascular inflammation in wild-type mice. Freshly cultured Pg was topically applied directly into the gingival pocket of the second molars for 5 weeks (3 times/week). After the final application, the mice were left in cages for 4 or 8 weeks and sacrificed. The status of Pg colony formation in the pocket, gingival inflammation, alveolar bone loss, the expression levels of pro-inflammatory cytokines in the serum and aorta, the presence of anti-Pg lipopolysaccharide (LPS) and gingipain (Kpg and RgpB) antibodies in the serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingiva and arterial wall were evaluated. The topical application of Pg into the gingival pocket induced the following local and systemic pathohistological changes in mice when examined at 4 or 8 weeks after the final topical Pg application: Pg colonization in the majority of gingival pockets; increased gingival pocket depths; gingival inflammation indicated by the increased expression of TNF-α, IL-6 and IL-1β; significant loss of alveolar bone at the sites of topical Pg application; and increased levels of pro-inflammatory cytokines, such as TNF-α, IL-1β, IL-17, IL-13, KC and IFN-γ in the serum in comparison to those from mice receiving PBS. In addition, the Pg application/colonization model induced anti-Pg LPS and gingipain antibodies in serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingivae and arterial walls. To the best of our knowledge, this mouse model represents the first example of creating a more sustained local infection in the gingival tissues of wild-type mice and may prove to be useful for the investigation of the more natural and complete pathogenesis of the bacteria in the development of local oral and systemic diseases, such as atherosclerosis. It may also be useful for the determination of a treatment/prevention/efficacy model associated with Pg-induced colonization periodontitis in mice.

Stratified analysis of the association between periodontitis and female breast cancer based on age, comorbidities and level of urbanization: A population-based nested case-control study

PURPOSE

To conduct stratified analysis of the association between periodontitis exposure and the risk of female breast cancer based on age, comorbidities and level of urbanization.

METHODS

Using claims data taken from the 1997-2013 Taiwanese National Health Insurance Research Database (NHIRD), we identified 60,756 newly-diagnosed female breast cancer patients during the period 2003-2013 from all beneficiaries. We then randomly selected 243,024 women without breast cancer matching (1:4) for age and the year of the index date during 1997-2013 from a one million representative population acting as the control group. A conditional logistic regression analysis was used to examine the association between periodontitis (ICD-9-CM codes 523.3-4) and the risk of breast cancer, shown as an odds ratio (OR) with a 95% confidence interval (CI) after adjustments for the Charlson Comorbidity Index (CCI) and level of urbanization. Subgroup analyses were conducted based on age, CCI and level of urbanization.

RESULTS

The mean ± standard deviation age was 53 ± 14 years. After adjusting for potential confounders, the risk of female breast cancer was found to be associated with a history of periodontitis (OR, 1.12; 95% CI, 1.10-1.14). Such an association was significantly different between patients aged < 65 years (OR, 1.09; 95% CI, 1.06-1.11) and patients aged ≥ 65 years (OR, 1.23; 95% CI, 1.18-1.28; p for interaction <0.001), as well as between patients where the CCI = 0 (OR, 1.17; 95% CI, 1.15-1.20) and patients with CCI > 0 (OR, 0.99; 95% CI, 0.96-1.03; p for interaction <0.001). The highest level of urbanization was also associated with the risk of breast cancer.

CONCLUSIONS

This population-based nested case-control study demonstrated that periodontitis was significantly associated with the risk of female breast cancer and such an association was modified by both age and comorbidities.

Relationship between chronic periodontitis and inflammatory cytokines in patients undergoing maintenance hemodialysis

OBJECTIVES

To investigate the correlation between serum and gingival crevicular fluid (GCF) levels of inflammatory cytokines and the association with periodontal parameters in patients with maintenance hemodialysis (MHD) and healthy control.

MATERIALS AND METHODS

Patients who were undergoing MHD were enrolled as the MHD group. Healthy individuals who underwent oral examination were selected as the control group after matching for the MHD group. All participants underwent a full-mouth periodontal evaluation, and the levels of eight inflammatory cytokines, including IL-1β, IL-17, IL-6, IL-8, and tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-8 (MMP-8), and C-reactive protein (CRP), in the GCF and serum were measured.

RESULTS

A total of 63 MHD patients and 75 healthy persons were included. The prevalence of moderate/severe periodontitis was significantly higher in the MHD group than in the control group (88.9 vs. 66.7%, P < 0.05). The GCF levels of CRP, TNF-α, MCP-1, and MMP-8 were higher in patients in the MHD group with moderate/severe periodontitis than in the control group (P < 0.05). Serum CRP, MCP-1, TNF-α, and MMP-8 levels were positively correlated with the GCF CRP levels (P < 0.05). The GCF and serum CRP levels were positively correlated with the periodontal clinical parameters (P < 0.05).

CONCLUSIONS

Serum CRP, MCP-1, TNF-α, and MMP-8 may relate with the GCF CRP levels. The GCF and serum CRP levels correlated positively with the periodontal clinical parameters, including the VPI, PPD, and CAL, indicating that CRP may play an important role between periodontitis and ESRD.

CLINICAL RELEVANCE

The present study indicated that GCF and serum CRP levels correlated positively with the periodontal clinical parameters, and the CRP levels may be selected as an indicator to evaluate the severity of inflammation and the effectiveness, prognosis of periodontal treatment in ESRD patients.

Oral and gastric microbiome in relation to gastric intestinal metaplasia

Evidence suggests that Helicobacter pylori plays a role in gastric cancer (GC) initiation. However, epidemiologic studies on the specific role of other bacteria in the development of GC are lacking. We conducted a case-control study of 89 cases with gastric intestinal metaplasia (IM) and 89 matched controls who underwent upper gastrointestinal endoscopy at three sites affiliated with NYU Langone Health. We performed shotgun metagenomic sequencing using oral wash samples from 89 case-control pairs and antral mucosal brushing samples from 55 case-control pairs. We examined the associations of relative abundances of bacterial taxa and functional pathways with IM using conditional logistic regression with and without elastic-net penalty. Compared with controls, oral species Peptostreptococcus stomatis, Johnsonella ignava, Neisseria elongata and Neisseria flavescens were enriched in cases (odds ratios [ORs] = 1.29-1.50, P = .004-.01) while Lactobacillus gasseri, Streptococcus mutans, S parasanguinis and S sanguinis were under-represented (ORs = 0.66-0.76, P = .006-.042) in cases. Species J ignava and Filifactor alocis in the gastric microbiota were enriched (ORs = 3.27 and 1.43, P = .005 and .035, respectively), while S mutans, S parasanguinis and S sanguinis were under-represented (ORs = 0.61-0.75, P = .024-.046), in cases compared with controls. The lipopolysaccharide and ubiquinol biosynthesis pathways were more abundant in IM, while the sugar degradation pathways were under-represented in IM. The findings suggest potential roles of certain oral and gastric microbiota, which are correlated with regulation of pathways associated with inflammation, in the development of gastric precancerous lesions.

Viruses, periodontitis, and comorbidities

Seminal studies published in the 1990s and 2000s explored connections between periodontal diseases and systemic conditions, revealing potential contributions of periodontal diseases in the initiation or worsening of systemic conditions. The resulting field of periodontal medicine led to the publication of studies indicating that periodontal diseases can influence the risk of systemic conditions, including adverse pregnancy outcomes, cardiovascular and respiratory diseases, as well as Alzheimer disease and cancers. In general, these studies hypothesized that the periodontal bacterial insult and/or the associated proinflammatory cascade could contribute to the pathogenesis of these systemic diseases. While investigations of the biological basis of the connections between periodontal diseases and systemic conditions generally emphasized the bacteriome, it is also biologically plausible, under an analogous hypothesis, that other types of organisms may have a similar role. Human viruses would be logical "suspects" in this role, given their ubiquity in the oral cavity, association with periodontal diseases, and ability to elicit strong inflammatory response, compromise immune responses, and synergize with bacteria in favor of a more pathogenic microbial consortium. In this review, the current knowledge of the role of viruses in connecting periodontal diseases and systemic conditions is examined. We will also delve into the mechanistic basis for such connections and highlight the importance of those relationships in the management and treatment of patients.

The impact of the human microbiome in tumorigenesis, cancer progression, and biotherapeutic development

Background

Cancer impacts millions of lives globally each year, with approximately 10 million cancer-related deaths recorded worldwide in 2020. Mounting research has recognised the human microbiome as a key area of interest in the pathophysiology of various human diseases including cancer tumorigenesis, progression and in disease outcome. It is suggested that approximately 20% of human cancers may be linked to microbes. Certain residents of the human microbiome have been identified as potentially playing a role, including: Helicobacter pylori, Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis and Porphyromonas gingivalis.

Main body

In this review, we explore the current evidence that indicate a link between the human microbiome and cancer. Microbiome compositional changes have been well documented in cancer patients. Furthermore, pathogenic microbes harbouring specific virulence factors have been implicated in driving the carcinogenic activity of various malignancies including colorectal, gastric and pancreatic cancer. The associated genetic mechanisms with possible roles in cancer will be outlined. It will be indicated which microbes have a potential direct link with cancer cell proliferation, tumorigenesis and disease progression. Recent studies have also linked certain microbial cytotoxins and probiotic strains to cancer cell death, suggesting their potential to target the tumour microenvironment given that cancer cells are integral to its composition. Studies pertaining to such cytotoxic activity have suggested the benefit of microbial therapies in oncological treatment regimes. It is also apparent that bacterial pathogenic protein products encoded for by certain loci may have potential as oncogenic therapeutic targets given their possible role in tumorigenesis.

Conclusion

Research investigating the impact of the human microbiome in cancer has recently gathered pace. Vast amounts of evidence indicate the human microbiome as a potential player in tumorigenesis and progression. Promise in the development of cancer biomarkers and in targeted oncological therapies has also been demonstrated, although more studies are needed. Despite extensive in vitro and in vivo research, clinical studies involving large cohorts of human patients are lacking. The current literature suggests that further intensive research is necessary to validate both the role of the human microbiome in cancer, and the use of microbiome modification in cancer therapy.

The role of gut microbiota in clinical complications, disease severity, and treatment response in severe alcoholic hepatitis

BACKGROUND

Dysbiotic gut bacteria engage in the development and progression of severe alcoholic hepatitis (SAH). We aimed to characterize bacterial communities associated with clinical events (CE), identify significant bacteria linked to CE, and define bacterial relationships associated with specific CE and outcomes at baseline and after treatment in SAH.

METHODS

We performed 16-s rRNA sequencing on stool samples (n=38) collected at admission and the last follow-up within 90 days in SAH patients (n=26; 12 corticosteroids; 14 granulocyte colony-stimulating factor, [G-CSF]). Validated pipelines were used to plot bacterial communities, profile functional metabolism, and identify significant taxa and functional metabolites. Conet/NetworkX® was utilized to identify significant non-random patterns of bacterial co-presence and mutual exclusion for clinical events.

RESULTS

All the patients were males with median discriminant function (DF) 64, Child-Turcotte-Pugh (CTP) 12, and model for end-stage liver disease (MELD) score 25.5. At admission, 27%, 42%, and 58% had acute kidney injury (AKI), hepatic encephalopathy (HE), and infections respectively; 38.5% died at end of follow-up. Specific bacterial families were associated with HE, sepsis, disease severity, and death. Lachnobacterium and Catenibacterium were associated with HE, and Pediococcus with death after steroid treatment. Change from Enterococcus (promotes AH) to Barnesiella (inhibits E. faecium) was significant after G-CSF. Phenylpropanoid-biosynthesis (innate-immunity) and glycerophospholipid-metabolism (cellular-integrity) pathways in those without infections and the death, respectively, were upregulated. Mutual interactions between Enterococcus cecorum, Acinetobacter schindleri, and Mitsuokella correlated with admission AKI.

CONCLUSIONS

Specific gut microbiota, their interactions, and metabolites are associated with complications of SAH and treatment outcomes. Microbiota-based precision medicine as adjuvant treatment may be a new therapeutic area.

At the Root of 3 “Long” Diseases: Persistent Antigens Inflicting Chronic Damage on the Brain and Other Organs in Gulf War Illness, Long-COVID-19, and Chronic Fatigue Syndrome

Several foreign antigens such as those derived from viruses and bacteria have been linked to long-term deleterious effects on the brain and other organs; yet, health outcomes subsequent to foreign antigen exposure vary depending in large part on the host’s immune system, in general, and on human leukocyte antigen (HLA) composition, in particular. Here we first provide a brief description of 3 conditions characterized by persistent long-term symptoms, namely long-COVID-19, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and Gulf War Illness (GWI), followed by a brief overview of the role of HLA in the immune response to foreign antigens. We then discuss our Persistent Antigen (PA) hypothesis and highlight associations between antigen persistence due to HLA-antigen incongruence and chronic health conditions in general and the 3 “long” diseases above in particular. This review is not intended to cover the breadth and depth of symptomatology of those diseases but is specifically focused on the hypothesis that the presence of persistent antigens underlies their pathogenesis.

Mixed lineage kinase domain-like pseudokinase-mediated necroptosis aggravates periodontitis progression

Necroptosis is a form of cell death that is reportedly involved in the pathogenesis of periodontitis. The role of Mlkl-involved necroptosis remains unclear. Herein, this project aimed to explore the role of MLKL-mediated necroptosis in periodontitis in vitro and in vivo. Expression of RIPK3, MLKL, and phosphorylated MLKL was observed in gingival tissues obtained from healthy subjects or patients with periodontitis. The cell viability of Porphyromonas gingivalis lipopolysaccharide (LPS-Pg)-treated cells was detected. In wild type or Mlkl deficiency mice with ligature-induced periodontitis, alveolar bone loss and osteoclast activation were assessed. mRNA levels of inflammatory cytokines in bone marrow-derived macrophages were tested by qRT-PCR. Increased expression of RIPK3, MLKL, and phosphorylated MLKL was observed in gingival tissues obtained from patients with periodontitis. Porphyromonas gingivalis lipopolysaccharide (LPS-Pg)-treated cells developed necroptosis after caspase inhibition and negatively regulated the NF-κB signaling pathway. In mice with ligature-induced periodontitis, Mlkl deficiency reduced alveolar bone loss and weakened osteoclast activation. Furthermore, genetic ablation of Mlkl in LPS-Pg-treated bone marrow-derived macrophages increased the mRNA levels of tumor necrosis factor-α, interleukin (Il)-1β, Il-6, cyclooxygenase 2, matrix metalloproteinase 9, and receptor activator of nuclear factor kappa-B ligand. Our data indicated that MLKL-mediated necroptosis aggravates the development of periodontitis in a Mlkl-deficient mouse. This will provide a new sight for the understanding of etiology and therapies of periodontitis. KEY MESSAGES: MLKL expression was up-regulated in inflamed human gingival tissue. Mlkl deficiency affected the progression of periodontitis. Necroptosis played a major role in mice periodontitis model. Knockout of Mlkl had a significant effect on inflammatory responses.

Microbiota Alterations and Their Association with Oncogenomic Changes in Pancreatic Cancer Patients

Pancreatic cancer (PC) is an aggressive disease with a high mortality and poor prognosis. The human microbiome is a key factor in many malignancies, having the ability to alter host metabolism and immune responses and participate in tumorigenesis. Gut microbes have an influence on physiological functions of the healthy pancreas and are themselves controlled by pancreatic secretions. An altered oral microbiota may colonize the pancreas and cause local inflammation by the action of its metabolites, which may lead to carcinogenesis. The mechanisms behind dysbiosis and PC development are not completely clear. Herein, we review the complex interactions between PC tumorigenesis and the microbiota, and especially the question, whether and how an altered microbiota induces oncogenomic changes, or vice versa, whether cancer mutations have an impact on microbiota composition. In addition, the role of the microbiota in drug efficacy in PC chemo- and immunotherapies is discussed. Possible future scenarios are the intentional manipulation of the gut microbiota in combination with therapy or the utilization of microbial profiles for the noninvasive screening and monitoring of PC.

Lactobacillus casei Zhang exerts probiotic effects to antibiotic-treated rats

Probiotics administration can facilitate the restoration of host gut microbiota/metabolome after antibiotic treatment. Yet, the mechanism behind such beneficial effects remains unclear. This study constructed a rat model of antibiotic-induced gut dysbiosis to monitor the effects and mechanism of probiotic (Lactobacillus casei Zhang) treatment in maintaining gut homeostasis and restoring the gut microbiota/metabolome. Forty rats were randomly divided into four groups (n = 10 per group): control receiving only saline (Ctrl), antibiotic (AB-Ctrl), antibiotic followed by probiotic (AB-Prob), and antibiotic plus probiotic followed by probiotic (AB + Prob). Rat fecal microbiota and sera were collected at four time points from pre-treatment to post-treatment. The probiotic-treated group (AB + Prob) had significantly more Parabacteroides (P.) goldsteinii after one week of antibiotic and probiotic intervention but fewer antibiotic resistance genes (ARGs)-possessing bacteria (Clostridioides difficile and Burkholderiales bacterium). Consistently, metabolomics data revealed that both probiotic groups had more acetic acid, propionic acid, butyric acid, and valeric acid post treatment. Moreover, a potential probiotic species, P. goldsteinii, strongly correlated with L. casei, as well as propionic acid, butyric acid, and valeric acid. Furthermore, administering probiotic lowered the serum IL-1α level. In contrast, the antibiotic-recipients had a higher irreversible level of IL-1α, suggesting inflammation of the rats. Thus, antibiotic treatment not only led to host gut dysbiosis, but inflammatory responses and an increase in gut ARGs. Daily L. casei Zhang supplementation could alleviate the side effect of cefdinir intervention and facilitate the restoration of gut microbial homeostasis, and these probiotic effects might involve P. goldsteinii-mediated beneficial activities.

Is There an Interplay between Oral Microbiome, Head and Neck Carcinoma and Radiation-Induced Oral Mucositis?

Head and neck carcinoma is one of the most common human malignancy types and it ranks as the sixth most common cancer worldwide. Nowadays, a great potential of microbiome research is observed in oncology-investigating the effect of oral microbiome in oncogenesis, occurrence of treatment side effects and response to anticancer therapies. The microbiome is a unique collection of microorganisms and their genetic material, interactions and products residing within the mucous membranes. The aim of this paper is to summarize current research on the oral microbiome and its impact on the development of head and neck cancer and radiation-induced oral mucositis. Human microbiome might determine an oncogenic effect by, among other things, inducing chronic inflammatory response, instigating cellular antiapoptotic signals, modulation of anticancer immunity or influencing xenobiotic metabolism. Influence of oral microbiome on radiation-induced oral mucositis is expressed by the production of additional inflammatory cytokines and facilitates progression and aggravation of mucositis. Exacerbated acute radiation reaction and bacterial superinfections lead to the deterioration of the patient's condition and worsening of the quality of life. Simultaneously, positive effects of probiotics on the course of radiation-induced oral mucositis have been observed. Understanding the impact on the emerging acute radiation reaction on the composition of the microflora can be helpful in developing a multifactorial model to forecast the course of radiation-induced oral mucositis. Investigating these processes will allow us to create optimized and personalized preventive measures and treatment aimed at their formation mechanism. Further studies are needed to better establish the structure of the oral microbiome as well as the dynamics of its changes before and after therapy. It will help to expand the understanding of the biological function of commensal and pathogenic oral microbiota in HNC carcinogenesis and the development of radiation-induced oral mucositis.

The oral microbiome: Role of key organisms and complex networks in oral health and disease

States of oral health and disease reflect the compositional and functional capacities of, as well as the interspecies interactions within, the oral microbiota. The oral cavity exists as a highly dynamic microbial environment that harbors many distinct substrata and microenvironments that house diverse microbial communities. Specific to the oral cavity, the nonshedding dental surfaces facilitate the development of highly complex polymicrobial biofilm communities, characterized not only by the distinct microbes comprising them, but cumulatively by their activities. Adding to this complexity, the oral cavity faces near-constant environmental challenges, including those from host diet, salivary flow, masticatory forces, and introduction of exogenous microbes. The composition of the oral microbiome is shaped throughout life by factors including host genetics, maternal transmission, as well as environmental factors, such as dietary habits, oral hygiene practice, medications, and systemic factors. This dynamic ecosystem presents opportunities for oral microbial dysbiosis and the development of dental and periodontal diseases. The application of both in vitro and culture-independent approaches has broadened the mechanistic understandings of complex polymicrobial communities within the oral cavity, as well as the environmental, local, and systemic underpinnings that influence the dynamics of the oral microbiome. Here, we review the present knowledge and current understanding of microbial communities within the oral cavity and the influences and challenges upon this system that encourage homeostasis or provoke microbiome perturbation, and thus contribute to states of oral health or disease.

The role of microbiome in pancreatic cancer

Recent studies of the human microbiome have offered new insights into how the microbiome can impact cancer development and treatment. Specifically, in pancreatic ductal adenocarcinoma (PDAC), the microbiota has been shown to modulate PDAC risk, contribute to tumorigenesis, impact the tumor microenvironment, and alter treatment response. These findings provide rationale for further investigations into leveraging the microbiome to develop new strategies to diagnose and treat PDAC patients. There is growing evidence that microbiome analyses have the potential to become easily performed, non-invasive diagnostic, prognostic, and predictive biomarkers in pancreatic cancer. More excitingly, there is now emerging interest in developing interventions based on the modulation of microbiota. Fecal microbiota transplantation, probiotics, dietary changes, and antibiotics are all potential strategies to augment the efficacy of current therapeutics and reduce toxicities. While there are still challenges to overcome, this is a rapidly growing field that holds promise for translation into clinical practice and provides a new approach to improving patient outcomes.

Porphyromonas gingivalis outside the oral cavity

Porphyromonas gingivalis, a Gram-negative anaerobic bacillus present in periodontal disease, is considered one of the major pathogens in periodontitis. A literature search for English original studies, case series and review articles published up to December 2019 was performed using the MEDLINE, PubMed and GoogleScholar databases, with the search terms "Porphyromonas gingivalis" AND the potentially associated condition or systemic disease Abstracts and full text articles were used to make a review of published research literature on P. gingivalis outside the oral cavity. The main points of interest of this narrative review were: (i) a potential direct action of the bacterium and not the systemic effects of the inflammatory acute-phase response induced by the periodontitis, (ii) the presence of the bacterium (viable or not) in the organ, or (iii) the presence of its virulence factors. Virulence factors (gingipains, capsule, fimbriae, hemagglutinins, lipopolysaccharide, hemolysin, iron uptake transporters, toxic outer membrane blebs/vesicles, and DNA) associated with P. gingivalis can deregulate certain functions in humans, particularly host immune systems, and cause various local and systemic pathologies. The most recent studies linking P. gingivalis to systemic diseases were discussed, remembering particularly the molecular mechanisms involved in different infections, including cerebral, cardiovascular, pulmonary, bone, digestive and peri-natal infections. Recent involvement of P. gingivalis in neurological diseases has been demonstrated. P. gingivalis modulates cellular homeostasis and increases markers of inflammation. It is also a factor in the oxidative stress involved in beta-amyloid production.

The Effect of Liposomal Curcumin as an Anti-Inflammatory Strategy on Lipopolysaccharide e from Porphyromonas gingivalis Treated Endothelial Committed Neural Crest Derived Stem Cells: Morphological and Molecular Mechanisms

Curcumin, a yellow polyphenol extracted from the turmeric root is used as a diet supplement. It exhibits anti-inflammatory, antioxidant, and antitumor properties by modulating different intracellular mechanisms. Due to their low solubility in water, the curcumin molecules must be encapsulated into liposomes to improve the bioavailability and biomedical potential. For the periodontal tissue and systemic health, it is essential to regulate the local inflammatory response. In this study, the possible beneficial effect of liposomes loaded with curcumin (CurLIP) in neural crest-derived human periodontal ligament stem cells (hPDLSCs) and in endothelial-differentiated hPDLSCs (e-hPDLSCs) induced with an inflammatory stimulus (lipopolysaccharide obtained from Porphyromonas gingivalis, LPS-G) was evaluated. The CurLIP formulation exhibited a significant anti-inflammatory effect by the downregulation of Toll-like receptor-4 (TLR4)/Myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa light chain enhancer of activated B cells (NFkB)/NLR Family Pyrin Domain Containing 3 (NLRP3)/Caspase-1/Interleukin (IL)-1β inflammation cascade and reactive oxygen species (ROS) formation. Moreover, the exposure to LPS-G caused significant alterations in the expression of epigenetic modifiers, such as DNA Methyltransferase 1 (DNMT1) and P300, while the CurLIP treatment showed physiological expression. Overall, our in vitro study provides novel mechanistic insights into the intracellular pathway exert by CurLIP in the regulation of inflammation and epigenetic modifications.

A potential therapeutic strategy for prostatic disease by targeting the oral microbiome

Nowadays, human microbiome research is rapidly growing and emerging evidence has witnessed the critical role that oral microbiome plays in the process of human health and disease. Oral microbial dysbiosis has been confirmed as a contributory cause for diseases in multiple body systems, ranging from the oral cavity to the gastrointestinal, endocrine, immune, cardiovascular, and even nervous system. As research progressing, oral microbiome-based diagnosis and therapy are proposed and applied, which may represent potential drug targets in systemic diseases. Recent studies have uncovered the possible association between periodontal disease and prostatic disease, suggesting new prevention and therapeutic treatment for the disease by targeting periodontal pathogens. Thus, we performed this review to first explore the association between the oral microbiome and prostatic disease, according to current knowledge based on published articles, and then mainly focus on the underlying molecular and cellular mechanisms and the potential prevention and treatment derived from these mechanistic studies.

Periodontal Disease and Tooth Loss Are Associated with Lung Cancer Risk

Background

The associations between periodontal disease, tooth loss, and lung cancer risk remain debatable. Therefore, the purpose of the present study is to evaluate whether periodontal disease and tooth loss are associated with lung cancer risk.

Methods

A literature search was performed for relevant studies using PubMed and Embase databases. Risk ratio (RR) with 95% confidence interval (CI) was applied as effect size to summarize the associations between periodontal disease, tooth loss, and lung cancer risk. A further dose-response analysis was also performed.

Results

A total of twelve studies comprising 263,238 participants were included. The results indicated that periodontal disease was positively associated with lung cancer risk (RR = 1.37, 95%CI = 1.16‐1.63). There was a positive association between tooth loss and lung cancer risk (RR = 1.69, 95%CI = 1.46‐1.96). Moreover, there was a significantly linear dose-response relationship between tooth loss and lung cancer risk, and every 5 increment in tooth loss was associated with 10% increased lung cancer risk. Similar results were obtained in subgroup analysis.

Conclusions

Periodontal disease and tooth loss are increased risk factors for lung cancer. Prevention and treatment of periodontal disease may be effective potential prevention strategies for lung cancer.

Porphyromonas gingivalis facilitated the foam cell formation via lysosomal integral membrane protein 2 (LIMP2)

OBJECTIVE

The involvement of lysosomal integral membrane protein 2 (LIMP2) in cholesterol transport and formation of foam cells under the infection of Porphyromonas gingivalis (P. gingivalis) is yet to be elucidated. The current study verified the role and explored the mechanism of LIMP2 in promoting foam cell formation by P. gingivalis.

BACKGROUND

An association between periodontitis and atherosclerosis (AS) has been established. P. gingivalis is a key pathogen of periodontitis that promotes foam cell formation by regulating activities of CD36 scavenger receptors expressed on the macrophages. LIMP2, a member of CD36 superfamily, is involved in cholesterol efflux. However, whether LIMP2 is involved in the formation of foam cells promoted by P. gingivalis remains unclear.

METHODS

The formation of foam cells was examined by Oil Red O staining. The knockdown of limp2 was identified by qRT-PCR. The accumulation of cholesterol was monitored by Cholesterol Assay Kit. The location of P. gingivalis was visualized by confocal microscopy. Cathepsin L activity was monitored with Magic Red Cathepsin L Assay Kit. The key genes and pathways in P. gingivalis-infected macrophages were explored by RNA sequencing. The protein level was investigated by Western blotting.

RESULTS

Porphyromonas gingivalis increases foam cells formation and upregulates the expression of LIMP2 in foam cells. The knockdown of limp2 decreases the number of foam cells and increases cholesterol export, which is related to lysosomal functions. In addition, the interaction between LIMP2 and caveolin-1(CAV1) might contribute to this process, and NF-κB and JNK activity is required for increased expression of P. gingivalis-induced LIMP2.

CONCLUSIONS

This study suggested that LIMP2 is involved in the foam cells formation facilitated by P. gingivalis, which favors a close connection between periodontitis and atherosclerosis (AS).

Periodontal Pathogens and Neuropsychiatric Health

Increasing evidence incriminates low-grade inflammation in cardiovascular, metabolic diseases, and neuropsychiatric clinical conditions, all important causes of morbidity and mortality. One of the upstream and modifiable precipitants and perpetrators of inflammation is chronic periodontitis, a polymicrobial infection with Porphyromonas gingivalis (P. gingivalis) playing a central role in the disease pathogenesis. We review the association between P. gingivalis and cardiovascular, metabolic, and neuropsychiatric illness, and the molecular mechanisms potentially implicated in immune upregulation as well as downregulation induced by the pathogen. In addition to inflammation, translocation of the pathogens to the coronary and peripheral arteries, including brain vasculature, and gut and liver vasculature has important pathophysiological consequences. Distant effects via translocation rely on virulence factors of P. gingivalis such as gingipains, on its synergistic interactions with other pathogens, and on its capability to manipulate the immune system via several mechanisms, including its capacity to induce production of immune-downregulating micro-RNAs. Possible targets for intervention and drug development to manage distal consequences of infection with P. gingivalis are also reviewed.

Combinatorial liposomes of berberine and curcumin inhibit biofilm formation and intracellular methicillin resistant Staphylococcus aureus infections and associated inflammation

The increase in drug-resistant strains of Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), has led to an increased rate of infection-related mortality. The emergence of drug resistance has rendered many antibiotics ineffective. The poor penetration and retention of antibiotics in mammalian cells lead to recurrent latent infections. Thus, there is an increasing need for biodegradable, non-toxic anti-infectives that are effective in treating MRSA infections. Phytochemicals such as berberine (BBR) and curcumin (CCR) have long been explored for their antibacterial activities, but their efficacy is often limited due to low bioavailability, water solubility, and poor cell penetration. When used in combination these antimicrobials did not show any synergistic effect against MRSA. Here, both of them were co-encapsulated in liposomes (BCL) and evaluated for biocompatibility, synergistic antimicrobial activity, intracellular infections, associated inflammation, and on biofilms formed by MRSA. Co-encapsulation of BBR and CCR in liposomes decreased their MICs by 87% and 96%, respectively, as compared to their free forms with a FICI of 0.13, indicating synergy between them. BCL inhibited the growth of MRSA and prevented biofilm formation better than free drugs. Co-culture studies showed that intracellular infection was reduced to 77% post BCL treatment. It also reduced the production of pro-inflammatory cytokines by macrophages following infection. The liposomes were found to be five times more efficient than clindamycin and can be used as a potential antimicrobial carrier against intracellular infections.

The Unique Microbiome and Immunity in Pancreatic Cancer

ABSTRACT

Microorganisms can help maintain homeostasis in humans by providing nutrition, maintaining hormone balance, and regulating inflammatory responses. In the case of imbalances, these microbes can cause various diseases, even malignancy. Pancreatic cancer (PC) is characterized by high tumor invasiveness, distant metastasis, and insensitivity to traditional chemotherapeutic drugs, and it is confirmed that PC is closely related to microorganisms. Recently, most studies based on clinical samples or case reports discussed the positive or negative relationships between microorganisms and PC. However, the specific mechanisms are blurry, especially the involved immunological pathways, and the roles of beneficial flora have usually been ignored. We reviewed studies published through September 2020 as identified using PubMed, MEDLINE, and Web of Science. We mainly introduced the traits of oral, gastrointestinal, and intratumoral microbes in PC and summarized the roles of these microbes in tumorigenesis and tumoral development through immunological pathways, in addition to illustrating the relationships between metabolic diseases with PC by microorganism. In addition, we identified microorganisms as biomarkers for early diagnosis and immunotherapy. This review will be significant for greater understanding the effect of microorganisms in PC and provide more meaningful guidance for future clinical applications.

Proteus mirabilis Targets Atherosclerosis Plaques in Human Coronary Arteries via DC-SIGN (CD209)

Bacterial DNAs are constantly detected in atherosclerotic plaques (APs), suggesting that a combination of chronic infection and inflammation may have roles in AP formation. A series of studies suggested that certain Gram-negative bacteria were able to interact with dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin [DC-SIGN; cluster of differentiation (CD) 209] or langerin (CD207), thereby resulting in deposition of CD209s at infection sites. We wondered if Proteus mirabilis (a member of Proteobacteria family) could interact with APs through CD209/CD207. In this study, we first demonstrated that CD209/CD207 were also receptors for P. mirabilis that mediated adherence and phagocytosis by macrophages. P. mirabilis interacted with fresh and CD209s/CD207-expressing APs cut from human coronary arteries, rather than in healthy and smooth arteries. These interactions were inhibited by addition of a ligand-mimic oligosaccharide and the coverage of the ligand, as well as by anti-CD209 antibody. Finally, the hearts from an atherosclerotic mouse model contained higher numbers of P. mirabilis than that of control mice during infection-challenging. We therefore concluded that the P. mirabilis interacts with APs in human coronary arteries via CD209s/CD207. It may be possible to slow down the progress of atherosclerosis by blocking the interactions between CD209s/CD207 and certain atherosclerosis-involved bacteria with ligand-mimic oligosaccharides.

The Role of Microbiologic Agents in the Progression of the Atherosclerosis: a Comprehensive Review

Atherosclerosis is a leading cause of disability, morbidity and mortality in the world. Atherosclerosis is accepted as a chronic progressive inflammatory disease. The inflammatory cascade in the vascular wall is well-defined. However, the predictors and contributors of the inflammatory response in atherosclerosis are not completely understood. Systemic and local inflammation, which enhance the burden of inflammation in the vascular wall, have been proposed as risk factors for the progression of atherosclerosis. Infectious micro-organisms are one of the major triggering factors for local and systemic inflammation. In this review, we aimed to emphasize the linkage between micro-organisms and the progression of atherosclerosis. We briefly summarize the current medical literature and discuss the future perspectives of the linkage between microbial agents and atherosclerosis representing cause and effect.

Porphyromonas gingivalis initiates coagulation and secretes polyphosphates - A mechanism for sustaining chronic inflammation?

BACKGROUND

Periodontitis is a chronic inflammation resulting in destruction of tooth-supporting bone. Chronic inflammation is characterized by extravascular fibrin deposition. Fibrin is central to destruction of bone; monocytes bind to fibrin and form osteoclasts, thus providing a link between coagulation and the tissue destructive processes in periodontitis. The oral microbiome is essential to oral health. However, local ecological changes, such as increased biofilm formation, result in a dysbiotic microbiome characterized by an increase of protease-producing species e.g. Porphyromonas gingivalis. Proteases initiate inflammation and may cleave coagulation factors. Polyphosphates (polyP) may also provide bacteria with procoagulant properties similar to platelet-released polyP. P. gingivalis has also been found in remote locations related to vascular pathology and Alzheimer's disease.

OBJECTIVES

The aim of this study was to investigate procoagulant activity of ten different species of oral bacteria present in oral health and disease as well as presence of polyP and fibrin formation in planktonic and biofilm bacteria.

METHODS

Oral bacteria were studied for protease production and procoagulant activity. The presence of polyP and formation of fibrin was observed using confocal microscopy.

RESULTS

P. gingivalis showed strong protease activity and was the only species exerting procoagulant activity. Confocal microscopy showed polyP intracellularly in planktonic bacteria and extracellularly after biofilm formation. Fibrin formation emanated from planktonic bacteria and from both bacteria and polyP in biofilm cultures.

CONCLUSIONS

The procoagulant activity of P. gingivalis could explain its role in chronic inflammation, locally in oral tissues as well as in remote locations.

You Talking to Me? Says the Enteric Nervous System (ENS) to the Microbe. How Intestinal Microbes Interact with the ENS

Mammalian organisms form intimate interfaces with commensal and pathogenic gut microorganisms. Increasing evidence suggests a close interaction between gut microorganisms and the enteric nervous system (ENS), as the first interface to the central nervous system. Each microorganism can exert a different effect on the ENS, including phenotypical neuronal changes or the induction of chemical transmitters that interact with ENS neurons. Some pathogenic bacteria take advantage of the ENS to create a more suitable environment for their growth or to promote the effects of their toxins. In addition, some commensal bacteria can affect the central nervous system (CNS) by locally interacting with the ENS. From the current knowledge emerges an interesting field that may shape future concepts on the pathogen-host synergic interaction. The aim of this narrative review is to report the current findings regarding the inter-relationships between bacteria, viruses, and parasites and the ENS.