Possible role of Porphyromonas gingivalis in orodigestive cancers

Oral Porphyromonas gingivalis Infections Increase the Risk of Alzheimer's Disease: A Review

Periodontal disease (PD) and Alzheimer's disease (AD) are inflammatory diseases affecting the adult population of the world. PD is mainly caused by infection with Porphyromonas gingivalis (P. gingivalis) and by the synergistic action of various microorganisms. These microorganisms penetrate into the subgingival tissue and cause bacteremia, leading to disruption of the homeostasis of the internal environment of the body. Virulence factors known as gingipains, which are cysteine proteases and other toxins, including fimbria and lipopolysaccharides (LPS), are strongly associated with periodontitis and other systemic inflammation. PD has a known polymicrobial aetiology, and patients who eventually develop sporadic AD tend to have recurrent infections before a clinical diagnosis of dementia. AD, the most common neurodegenerative disease, is characterised by poor memory and specific hallmark proteins. An increasing number of studies have shown that periodontal pathogens are increasingly associated with this form of dementia. Many articles have shown that P. gingivalis infections directly increase the risk of PD and may indirectly lead to the development of AD. However, these links and probable pathogenesis remain to be explored. The aim of this review was to explore whether P. gingivalis periodontal infection is associated with AD and to provide possible mechanisms of association.

New insight into the microbiome, resistome, and mobilome on the dental waste water in the context of heavy metal environment

Object

Hospital sewage have been associated with incorporation of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) into microbes, which is considered as a key indicator for the spread of antimicrobial resistance (AMR). The compositions of dental waste water (DWW) contain heavy metals, the evolution of AMR and its effects on the water environment in the context of heavy metal environment have not been seriously investigated. Thus, our major aims were to elucidate the evolution of AMR in DWW.

Methods

DWW samples were collected from a major dental department. The presence of microbial communities, ARGs, and MGEs in untreated and treated (by filter membrane and ozone) samples were analyzed using metagenomics and bioinformatic methods.

Results

DWW-associated resistomes included 1,208 types of ARGs, belonging to 29 antibiotic types/subtypes. The most abundant types/subtypes were ARGs of multidrug resistance and of antibiotics that were frequently used in the clinical practice. Pseudomonas putida, Pseudomonas aeruginosa, Chryseobacterium indologenes, Sphingomonas laterariae were the main bacteria which hosted these ARGs. Mobilomes in DWW consisted of 93 MGE subtypes which belonged to 8 MGE types. Transposases were the most frequently detected MGEs which formed networks of communications. For example, ISCrsp1 and tnpA.5/4/11 were the main transposases located in the central hubs of a network. These significant associations between ARGs and MGEs revealed the strong potential of ARGs transmission towards development of antimicrobial-resistant (AMR) bacteria. On the other hand, treatment of DWW using membranes and ozone was only effective in removing minor species of bacteria and types of ARGs and MGEs.

Conclusion

DWW contained abundant ARGs, and MGEs, which contributed to the occurrence and spread of AMR bacteria. Consequently, DWW would seriously increase environmental health concerns which may be different but have been well-documented from hospital waste waters.

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.

[Research Progress on the Interaction Between Microorganisms and Macrophages and Their Role in the Mediation of the Onset and Development of Oral Cancer]

Oral squamous cell carcinoma is the sixth most common malignant tumor in the world, and the clinical treatment effect is not satisfactory. Because of the special nature of its location, oral cancer is inextricably linked with a wide variety of microorganisms, and its pathogenesis and development are also extremely susceptible to microbial regulation. In addition, the mediating role of the immune system is also indispensable to the course of tumor pathogenesis and development, especially tumor-associated macrophages, which amplify the regulatory role of microorganisms, and in turn regulate the microbial population components--two complementary effects that jointly exacerbate oral cancer. Herein, we summarized the existing research on the relationship between microorganisms and macrophages, as well as the regulatory role of microorganisms and macrophages in the pathogenesis and development of oral cancer. We also discussed the current status of and gaps in research on the relationship between microorganisms and macrophages and oral cancer. Both microorganisms and macrophages are considered promising indicators for prognosis, showing potentials to be used as new therapeutic targets. Despite some research interest in the role of microorganisms and macrophages in oral cancer, very few studies have linked them to oral precancerous lesions, and the mutual regulatory relationship between microorganisms and macrophages remains unclear. Therefore, in-depth exploration of the relationship network of microorganisms, macrophages and oral cancer is expected to provide more possibilities for the early diagnosis and treatment of tumors.

Therapeutic and Metagenomic Potential of the Biomolecular Therapies against Periodontitis and the Oral Microbiome: Current Evidence and Future Perspectives

The principles of periodontal therapy are based on the control of microbial pathogens and host factors that contribute to biofilm dysbiosis, with the aim of modulating the progression of periodontitis and periodontal tissue destruction. It is currently known how differently each individual responds to periodontal treatment, depending on both the bacterial subtypes that make up the dysbiotic biofilm and interindividual variations in the host inflammatory response. This has allowed the current variety of approaches for the management of periodontitis to be updated by defining the goals of target strategies, which consist of reducing the periodontopathogenic microbial flora and/or modulating the host-mediated response. Therefore, this review aims to update the current variety of approaches for the management of periodontitis based on recent target therapies. Recently, encouraging results have been obtained from several studies exploring the effects of some targeted therapies in the medium- and long-term. Among the most promising target therapies analyzed and explored in this review include: cell-based periodontal regeneration, mediators against bone resorption, emdogain (EMD), platelet-rich plasma, and growth factors. The reviewed evidence supports the hypothesis that the therapeutic combination of epigenetic modifications of periodontal tissues, interacting with the dysbiotic biofilm, is a key step in significantly reducing the development and progression of disease in periodontal patients and improving the therapeutic response of periodontal patients. However, although studies indicate promising results, these need to be further expanded and studied to truly realize the benefits that targeted therapies could bring in the treatment of periodontitis.

The oral microbiota and its role in carcinogenesis

Despite decades of research, cancer continues to be a major global health concern. In recent years, the role played by microorganisms in the development and progression of cancer has come under increased scrutiny. The aim of the present review is to highlight the main associations between members of the human oral microbiota and various cancers. The PubMed database was searched for available literature to outline the current state of understanding regarding the role of the oral microbiota and a variety of human cancers. Oral squamous cell carcinoma (OSCC) is associated with carriage of a number of oral bacteria (e.g., Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sp.), certain viruses (e.g., human papilloma virus, human herpes virus 8, herpes simplex virus 1 and Epstein-Barr virus) and yeast (Candida albicans). Moreover, members of the oral microbiota are associated with cancers of the esophagus, stomach, pancreas, colon/rectum and lung. Furthermore, the present review outlines a number of the carcinogenic mechanisms underlying the presented microbial associations with cancer. Such information may one day help clinicians to diagnose neoplastic diseases at earlier stages and prescribe treatments that take into account the possible microbial nature of carcinogenesis.

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.

Understanding the characteristics of the host genome and microbiome interaction in oral squamous cell carcinoma: a narrative review

Background

Oral health status is directly associated with microbes present within it. The abundance of microbes at the OSCC site is more than at its control site, representing its possible role in the progression of OSCC development. Dysbiosis of oral microbiota could be a crucial etiological risk factor in the elevation of OSCC. This study aimed to analyze and assess: a) positive regulator microbes of oral cancer and their abundance at the cancer site, b) pathways involved in positive regulator microbes, and c) identification of the most virulent oral oncogenic microbe.

Main body

It is obtained from several studies that microbes belonging to Prevotella, Fusobacterium, Alloprevotella, Capnocytophaga, Porphyromonas, Campylobacter, and Aggregatibacter are detected to be more in number contrast to healthy sites. Fusobacterium nucleatum, Porphyromonas gingivalis, and Candida albicans show molecular pathways linked with OSCC development. Genes encoding for virulent factors like FimA, Gingipains, lipopolysaccharide (P. gingivalis), FadA, Fap2 (F. nucleatum), and zymosan (C. Albicans) are directly involved in elevating oral cancer.

Conclusion

Mostly, the genes that are involved in promoting oral cancer are the genes that generally encode cell wall proteins. The cell wall proteins that is FadA, Fap, and FimA interact with the host's cell and hamper the normal regulation pathway, which leads to activation of cell proliferating pathways, down-regulates apoptotic pathways, cytoskeleton rearrangement, and upregulates the cell cycle checkpoint regulators; as a result, progression of oral cancer occurs.

Implications of Porphyromonas gingivalis peptidyl arginine deiminase and gingipain R in human health and diseases

Porphyromonas gingivalis is a major pathogenic bacterium involved in the pathogenesis of periodontitis. Citrullination has been reported as the underlying mechanism of the pathogenesis, which relies on the interplay between two virulence factors of the bacterium, namely gingipain R and the bacterial peptidyl arginine deiminase. Gingipain R cleaves host proteins to expose the C-terminal arginines for peptidyl arginine deiminase to citrullinate and generate citrullinated proteins. Apart from carrying out citrullination in the periodontium, the bacterium is found capable of citrullinating proteins present in the host synovial tissues, atherosclerotic plaques and neurons. Studies have suggested that both virulence factors are the key factors that trigger distal effects mediated by citrullination, leading to the development of some non-communicable diseases, such as rheumatoid arthritis, atherosclerosis, and Alzheimer’s disease. Thus, inhibition of these virulence factors not only can mitigate periodontitis, but also can provide new therapeutic solutions for systematic diseases involving bacterial citrullination. Herein, we described both these proteins in terms of their unique structural conformations and biological relevance to different human diseases. Moreover, investigations of inhibitory actions on the enzymes are also enumerated. New approaches for identifying inhibitors for peptidyl arginine deiminase through drug repurposing and virtual screening are also discussed.

Alterations of Microorganisms in Tongue Coating of Gastric Precancerous Lesion Patients with a Damp Phlegm Pattern

Objective. In the research, the microbial changes in the tongue coating of patients with a damp phlegm pattern of gastric precancerous lesion (GPL) were investigated. Methods. This was a case-control study, in which 80 tongue coating samples were collected including 40 patients with a damp phlegm pattern of GPL, 20 patients with a nondamp phlegm pattern of GPL, and 20 healthy control people. The 16S rRNA microbiome technology was used to analyze the alterations of microorganisms in tongue coating of GPL patients with a damp phlegm pattern. Results. Microorganisms in the genus level were analyzed. Compared with the healthy control group, the relative abundance of 4 microorganisms (Solobacterium, Rothia, Oribacterium, and Alloprevotella) in the GPL group was significantly higher ( $P<0.05$ ). The relative abundance of 10 microorganisms (Terrisporobacter, Solobacterium, Porphyromonas, Parvimonas, Lactobacillus, Johnsonella, Gemella, Fusibacter, Azoarcus, and Acidothermus) in the GPL damp phlegm pattern group was significantly lower than that in the GPL nondamp phlegm pattern group ( $P<0.05$ ). In the comparison of phenotype “forms biofilms,” the relative abundance of microorganisms in the GPL group was significantly higher than that in the healthy control group ( $P<0.05$ ). In the comparison of phenotype “contains mobile elements,” the relative abundance of microorganisms in the GPL damp phlegm pattern group was significantly lower than that in the GPL nondamp phlegm pattern group ( $P<0.05$ ). In the comparison of microbial metabolic functions, the abundance ratio of “infectious diseases: bacterial” in the GPL group was significantly lower than that in the healthy control group ( $P<0.05$ ). The abundance ratio of the “excretory system” and “folding, sorting, and degradation” in the GPL group was significantly higher than that in the healthy control group ( $P<0.05$ ). Conclusions. Solobacterium may be a marker microorganism of the GPL damp phlegm pattern. The differential phenotype of microorganisms in tongue coating of the GPL damp tongue pattern is mainly reflected in “forms biofilms” and “contains mobile elements.”

Cortisol Promotes Surface Translocation of Porphyromonas gingivalis

Studies are showing that the stress hormone cortisol can reach high levels in the gingival sulcus and induce shifts in the metatranscriptome of the oral microbiome. Interestingly, it has also been shown that cortisol can influence expression levels of Type IX Secretion System (T9SS) genes involved in gliding motility in bacteria belonging to the phylum Bacteroidota. The objective of this study was to determine if cortisol impacts gene expression and surface translocation of Porphyromonas gingivalis strain W50. To conduct these experiments, P. gingivalis was stabbed to the bottom of soft agar plates containing varying cortisol concentrations (0 μM, 0.13 μM, 1.3 μM, and 13 μM), and surface translocation on the subsurface was observed after 48 h of incubation. The results show that when grown with certain nutrients, i.e., in rich medium with the addition of sheep blood, lactate, or pyruvate, cortisol promotes migration of P. gingivalis in a concentration-dependent manner. To begin to examine the underlying mechanisms, quantitative PCR was used to evaluate differential expression of genes when P. gingivalis was exposed to cortisol. In particular, we focused on differential expression of T9SS-associated genes, including mfa5, since it was previously shown that Mfa5 is required for cell movement and cell-to-cell interactions. The data show that mfa5 is significantly up-regulated in the presence of cortisol. Moreover, an mfa5 deletion mutant showed less surface translocation compared to the wild-type P. gingivalis in the presence of cortisol, and the defects of the mfa5 deletion mutant were restored by complementation. Overall, cortisol can stimulate P. gingivalis surface translocation and this coincides with higher expression levels of T9SS-associated genes, which are known to be essential to gliding motility. Our findings support a high possibility that the stress hormone cortisol from the host can promote surface translocation and potentially virulence of P. gingivalis.

A Commentary on the Potential Use of Oral Microbiome in Prediction, Diagnosis or Prognostics of a Distant Pathology

In health, the oral microbiome is in balance with its host. If this balance is lost, this symbiosis is replaced by dysbiotic microbial communities, which are thought to affect the rest of the body either directly or via metabolites or pro-inflammatory molecules. The association of oral microbiome with general health has led to attempts to use oral microbial biomarkers for the prediction, diagnosis or prognosis of distant pathologies such as colorectal carcinoma or pancreatic cancer. These attempts however have no chance to succeed if the complexity of the oral ecosystem and the interplay of environmental, behavioral and biological factors is not taken into account. Standardized, well-documented oral sample collection procedures together with detailed clinical oral examination and behavioral data are the prerequisites for the successful evaluation of the oral microbiome as a potential biomarker for distant pathologies.

Culturomics, a potential approach paving the way toward bacteriotherapy

The human microbiota has been extensively studied over the past decade to describe its role in health and diseases. Numerous studies showed the presence of bacterial imbalance in a variety of human health conditions, suggesting great potential for the development of bacteriotherapies. Identifying mechanisms involving the human microbiota has been very challenging due to the complex data generated by molecular approaches and the limited number of organisms isolated by culture and described. This review summarizes the efforts done to describe the human microbiota through culturomics and the advancements in culturing the organisms residing at different body sites.

Macrophages: A communication network linking Porphyromonas gingivalis infection and associated systemic diseases

Porphyromonas gingivalis (P. gingivalis) is a Gram-negative anaerobic pathogen that is involved in the pathogenesis of periodontitis and systemic diseases. P. gingivalis has recently been detected in rheumatoid arthritis (RA), cardiovascular disease, and tumors, as well as Alzheimer’s disease (AD), and the presence of P. gingivalis in these diseases are correlated with poor prognosis. Macrophages are major innate immune cells which modulate immune responses against pathogens, however, multiple bacteria have evolved abilities to evade or even subvert the macrophages’ immune response, in which subsequently promote the diseases’ initiation and progression. P. gingivalis as a keystone pathogen of periodontitis has received increasing attention for the onset and development of systemic diseases. P. gingivalis induces macrophage polarization and inflammasome activation. It also causes immune response evasion which plays important roles in promoting inflammatory diseases, autoimmune diseases, and tumor development. In this review, we summarize recent discoveries on the interaction of P. gingivalis and macrophages in relevant disease development and progression, such as periodontitis, atherosclerosis, RA, AD, and cancers, aiming to provide an in-depth mechanistic understanding of this interaction and potential therapeutic strategies.

Bacteria and tumor: Understanding the roles of bacteria in tumor genesis and immunology

In the past, tumor and microbial infection were commonly regarded as independent diseases with few interrelations. The discovery of bacteria in tumor tissue changed the knowledge of bacteria-tumor relationship. Recently, more and more findings have demonstrated the significant effects of bacteria on the genesis, development and metastasis of tumor. Particularly, the influence of bacteria on tumor immunity is of great interest. Bacteria can inhibit the function of immune system through multiple mechanisms. On the other hand, some bacteria can also enhance the immune response and inhibit tumor progression. Understanding the bacteria-tumor interactions is of great importance for developing novel anticancer approaches. Herein, we aim to provide a comprehensive understanding of the tumor/tumor immunology, the biogenesis of bacteria in tumor and the relation of tumorigenesis with bacteria. In addition, the roles of bacteria in tumor immunology and the potential approaches to use bacteria for cancer therapy are discussed.

Microbiological and molecular identification of the anaerobic component of the oral microbiota in patients with cancer of the oropharyngeal region

A research objective - to study tumor tissues of primary and recurrent patients with cancer of the oropharyngeal region for the frequency of occurrence of four types of anaerobic periodontogens and their associations by two methods: real-time PCR and cultural. There is speculation that bacteria can influence the pathogenesis of cancer. A comparative assessment of the content of four anaerobic periodontogens (Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, Treponema denticola) in the tumor tissue and in the healthy tissue of the oral mucosa of patients with oropharyngeal cancer was carried out. It was found that the identification of odontopathogens by the real-time PCR method is much more informative than the traditional culture method, with the exception of P. intermedia, for the identification of which the traditional culture method was more effective. In 33.3% of patients, both primary and secondary, the composition of microorganisms was the same in both healthy and tumor tissue. In 20% of primary patients and in 13.3% of repeat patients, no associations of microorganisms included in the study were found in healthy tissue. Associations of 4 bacteria were recorded only in tumor tissue in both primary and repeated patients, and in repeated patients - statistically significantly more often. In 53.3% of repeat patients, associations of 4 bacteria were recorded in tumor tissue, whereas in primary patients, only in one case. P. gingivalis from tumor tissue in repeat patients was statistically significantly more often than in primary patients. T. forsythensis in primary patients was found statistically significantly more often in healthy tissues than in repeat patients, in which T. forsythensis was found statistically significantly more often from tumor tissue than in healthy tissue). T. denticola in healthy tissue was detected in both primary and repeated patients in isolated cases. T. denticola in tumor tissue was found statistically significantly more frequently in both primary and repeated patients compared to healthy tissue. P. gingivalis, T. forsythensis, and T. denticola should perhaps be considered risk indicators indicating the level of significance of their associations with oropharyngeal cancer.

The Microbiome in Pancreatic Cancer-Implications for Diagnosis and Precision Bacteriophage Therapy for This Low Survival Disease

While the mortality rates for many cancers have decreased due to improved detection and treatments, that of pancreatic cancer remains stubbornly high. The microbiome is an important factor in the progression of many cancers. Greater understanding of the microbiome in pancreatic cancer patients, as well as its manipulation, may assist in diagnosis and treatment of this disease. In this report we reviewed studies that compared microbiome changes in pancreatic cancer patients and non-cancer patients. We then identified which bacterial genera were most increased in relative abundance across the oral, pancreatic, duodenal, and faecal tissue microbiomes. In light of these findings, we discuss the potential for utilising these bacteria as diagnostic biomarkers, as well as their potential control using precision targeting with bacteriophages, in instances where a causal oncogenic link is made.

Periodontitis pathogen Porphyromonas gingivalis promotes pancreatic tumorigenesis via neutrophil elastase from tumor-associated neutrophils

Intratumor microbiome shapes the immune system and influences the outcome of various tumors. Porphyromonas gingivalis (P. gingivalis), the keystone periodontal pathogen, is highly epidemically connected with pancreatic cancer (PC). However, its causative role and the underlining mechanism in promoting PC oncogenesis remain unclear. Here, we illustrated the landscape of intratumor microbiome and its bacterial correlation with oral cavity in PC patients, where P. gingivalis presented both in the oral cavity and tumor tissues. When exposed to P. gingivalis, tumor development was accelerated in orthotopic and subcutaneous PC mouse model, and the cancerous pancreas exhibited a neutrophils-dominated proinflammatory tumor microenvironment. Mechanistically, the intratumoral P. gingivalis promoted PC progression via elevating the secretion of neutrophilic chemokines and neutrophil elastase (NE). Collectively, our study disclosed the bacterial link between periodontitis and PC, and revealed a previously unrecognized mechanism of P. gingivalis in PC pathophysiology, hinting at therapeutic implications.

Proposal of a health gut microbiome index based on a meta-analysis of Korean and global population datasets

The disruption of the human gut microbiota has been linked to host health conditions, including various diseases. However, no reliable index for measuring and predicting a healthy microbiome is currently available. Here, the sequencing data of 1,663 Koreans were obtained from three independent studies. Furthermore, we pooled 3,490 samples from public databases and analyzed a total of 5,153 fecal samples. First, we analyzed Korean gut microbiome covariates to determine the influence of lifestyle on variation in the gut microbiota. Next, patterns of microbiota variations across geographical locations and disease statuses were confirmed using a global cohort and di-sease data. Based on comprehensive comparative analysis, we were able to define three enterotypes among Korean cohorts, namely, Prevotella type, Bacteroides type, and outlier type. By a thorough categorization of dysbiosis and the evaluation of microbial characteristics using multiple datasets, we identified a wide spectrum of accuracy levels in classifying health and disease states. Using the observed microbiome patterns, we devised an index named the gut microbiome index (GMI) that could consistently predict health conditions from human gut microbiome data. Compared to ecological metrics, the microbial marker index, and machine learning approaches, GMI distinguished between healthy and non-healthy individuals with a higher accuracy across various datasets. Thus, this study proposes a potential index to measure health status of gut microbiome that is verified from multiethnic data of various diseases, and we expect this model to facilitate further clinical application of gut microbiota data in future.

Microbial Protein Binding to gC1qR Drives PLA2G1B-Induced CD4 T-Cell Anergy

The origin of the impaired CD4 T-cell response and immunodeficiency of HIV-infected patients is still only partially understood. We recently demonstrated that PLA2G1B phospholipase synergizes with the HIV gp41 envelope protein in HIV viremic plasma to induce large abnormal membrane microdomains (aMMDs) that trap and inactivate physiological receptors, such as those for IL-7. However, the mechanism of regulation of PLA2G1B activity by the cofactor gp41 is not known. Here, we developed an assay to directly follow PLA2G1B enzymatic activity on CD4 T-cell membranes. We demonstrated that gp41 directly binds to PLA2G1B and increases PLA2G1B enzymatic activity on CD4 membrane. Furthermore, we show that the conserved 3S sequence of gp41, known to bind to the innate sensor gC1qR, increases PLA2G1B activity in a gC1qR-dependent manner using gC1qR KO cells. The critical role of the 3S motif and gC1qR in the inhibition of CD4 T-cell function by the PLA2G1B/cofactor system in HIV-infected patients led us to screen additional microbial proteins for 3S-like motifs and to study other proteins known to bind to the gC1qR to further investigate the role of the PLA2G1B/cofactor system in other infectious diseases and carcinogenesis. We have thus extended the PLA2G1B/cofactor system to HCV and Staphylococcus aureus infections and additional pathologies where microbial proteins with 3S-like motifs also increase PLA2G1B enzymatic activity. Notably, the bacteria Porphyromonas gingivalis, which is associated with pancreatic ductal adenocarcinoma (PDAC), encodes such a cofactor protein and increased PLA2G1B activity in PDAC patient plasma inhibits the CD4 response to IL-7. Our findings identify PLA2G1B/cofactor system as a CD4 T-cell inhibitor. It involves the gC1qR and disease-specific cofactors which are gC1qR-binding proteins that can contain 3S-like motifs. This mechanism involved in HIV-1 immunodeficiency could play a role in pancreatic cancer and several other diseases. These observations suggest that the PLA2G1B/cofactor system is a general CD4 T-cell inhibitor and pave the way for further studies to better understand the role of CD4 T-cell anergy in infectious diseases and tumor escape.

Toward the use ofBoesenbergia rotundaextracts and the chalcone panduratin A to treat periodontitis

Novel affordable medications are needed to treat chronic periodontitis, which is one of the most common dental pathologies worldwide. Extracts prepared from the rhizome of the medicinal plant Boesenbergia rotunda (L.) Mansf., commonly known as fingerroot, are used to treat a variety of human pathologies. These extracts contain potent anti-inflammatory compounds, including the chalcone derivative panduratin A (Pa-A), which is the lead compound of a series of analogues, designated panduratins A to Y. The anti-inflammatory properties of the extracts of B. rotunda and the most abundant bioactive products found in these extracts (including Pa-A, 4-hydroxyoanduratin, isopanduratin, and others) have been reviewed. A standardized extract of the plant has promising utility in the treatment of gingival inflammation. The effects are characterized by three actions: (i) a direct antimicrobial effect against fungi and oral pathogens such as Porphyromonas gingivalis, (ii) a marked anti-inflammatory effect via a reduced production of mediators, like prostaglandin E2 and different interleukins, and (iii) a dual bone-preserving effect, with a reduction in bone resorption and an increase in bone formation. Acting as a protease inhibitor, Pa-A is one of the main active ingredients of the extract, implicated in these actions. A Pa-A-standardized extract of B. rotunda has been used in humans for treating dyspepsia. The product is safe and well-tolerated. The development of panduratin-containing dental products, for the prevention and treatment of periodontitis, has been proposed. The structural analogues, Pa-A to-Y, should also be investigated for the treatment of dental inflammation.

Periodontitis, chronic liver diseases, and the emerging oral-gut-liver axis

The liver carries out a wide range of functions ranging from the control of metabolites, nutrient storage, and detoxification to immunosurveillance. While inflammation is essential for the tissue remodeling and maintenance of homeostasis and normal liver physiology, constant exposure to dietary and microbial products creates a niche for potentially prolonged immune activation and unresolved inflammation in susceptible host. Failure to restrain inflammation can lead to development of chronic liver diseases characterized by fibrosis, cirrhosis and eventually liver failure. The liver maintains close interactions with numerous organs which can influence its metabolism and physiology. It is also known that oral cavity microenvironment can influence the physiological conditions of other organs and emerging evidence implicates that this could be true for the liver as well. Presence of chronic inflammation and dysbiotic microbiota is a common feature leading to clinical pathology both in periodontitis and chronic liver diseases (CLDs). In fact, known CLDs appear to have some relationship with periodontitis, which impacts the onset or progression of these conditions in a bidirectional crosstalk. In this review, we explore the emerging association between oral‐gut‐liver axis focusing on periodontitis and common CLDs including nonalcoholic fatty liver disease, chronic viral hepatitis, liver cirrhosis, and hepatocellular cancer. We highlight the immune pathways and oral microbiome interactions which can link oral cavity and liver health and offer perspectives for future research.

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.

Microbiota and cancer: current understanding and mechanistic implications

During last few decades, role of microbiota and its importance in several diseases has been a hot topic for research. The microbiota is considered as an accessory organ for maintaining normal physiology of an individual. These microbiota organisms which normally colonize several epithelial surfaces are known to secrete several small molecules leading to local and systemic effects on normal biological processes. The role of microbiota is also established in carcinogenesis as per several recent findings. The effects of microbiota on cancer is not only limited to their contribution in oncogenesis, but the overall susceptibility for oncogenesis and its subsequent progression, development of coinfections, and response to anticancer therapy is also found to be affected by microbiota. The information about microbiota and subsequent contributions of microbes in anticancer response motivated researchers in development of microbes-based anticancer therapeutics. We provided current status of microbiota contribution in oncogenesis with special reference to their mechanistic implications in different aspects of oncogenesis. In addition, the mechanistic implications of bacteria in anticancer therapy are also discussed. We conclude that several mechanisms of microbiota-mediated regulation of oncogenesis is known, but approaches must be focused on understanding contribution of microbiota as a community rather than single organisms-mediated effects.

Bacterial-Viral Interactions in Human Orodigestive and Female Genital Tract Cancers: A Summary of Epidemiologic and Laboratory Evidence

Infectious agents, including viruses, bacteria, fungi, and parasites, have been linked to pathogenesis of human cancers, whereas viruses and bacteria account for more than 99% of infection associated cancers. The human microbiome consists of not only bacteria, but also viruses and fungi. The microbiome co-residing in specific anatomic niches may modulate oncologic potentials of infectious agents in carcinogenesis. In this review, we focused on interactions between viruses and bacteria for cancers arising from the orodigestive tract and the female genital tract. We examined the interactions of these two different biological entities in the context of human carcinogenesis in the following three fashions: (1) direct interactions, (2) indirect interactions, and (3) no interaction between the two groups, but both acting on the same host carcinogenic pathways, yielding synergistic or additive effects in human cancers, e.g., head and neck cancer, liver cancer, colon cancer, gastric cancer, and cervical cancer. We discuss the progress in the current literature and summarize the mechanisms of host-viral-bacterial interactions in various human cancers. Our goal was to evaluate existing evidence and identify gaps in the knowledge for future directions in infection and cancer.

Crosstalk between autophagy and microbiota in cancer progression

Autophagy is a highly conserved catabolic process seen in eukaryotes and is essentially a lysosome-dependent protein degradation pathway. The dysregulation of autophagy is often associated with the pathogenesis of numerous types of cancers, and can not only promote the survival of cancer but also trigger the tumor cell death. During cancer development, the microbial community might predispose cells to tumorigenesis by promoting mucosal inflammation, causing systemic disorders, and may also regulate the immune response to cancer. The complex relationship between autophagy and microorganisms can protect the body by activating the immune system. In addition, autophagy and microorganisms can crosstalk with each other in multifaceted ways to influence various physiological and pathological responses involved in cancer progression. Various molecular mechanisms, correlating the microbiota disorders and autophagy activation, control the outcomes of protumor or antitumor responses, which depend on the cancer type, tumor microenvironment and disease stage. In this review, we mainly emphasize the leading role of autophagy during the interaction between pathogenic microorganisms and human cancers and investigate the various molecular mechanisms by which autophagy modulates such complicated biological processes. Moreover, we also highlight the possibility of curing cancers with multiple molecular agents targeting the microbiota/autophagy axis. Finally, we summarize the emerging clinical trials investigating the therapeutic potential of targeting either autophagy or microbiota as anticancer strategies, although the crosstalk between them has not been explored thoroughly.

Porphyromonas gingivalis in oral squamous cell carcinoma: A review

Oral cancer contributes significantly to the global cancer burden. Oral bacteria play an important role in the spread of oral cancer, according to mounting evidence. The most proven instance is the carcinogenic implications of Porphyromonas gingivalis, a key pathogen in chronic periodontitis. It is imperative to understand the pathogenesis of P. gingivalis in OSCC. This review aims to gather and assess scientific shreds of evidence on the involvement of Porphyromonas gingivalis in the molecular mechanism of oral squamous cell carcinoma.

Fusobacterium nucleatum and oral cancer: a critical review

There is a growing level of interest in the potential role inflammation has on the initiation and progression of malignancy. Notable examples include Helicobacter pylori-mediated inflammation in gastric cancer and more recently Fusobacterium nucleatum-mediated inflammation in colorectal cancer. Fusobacterium nucleatum is a Gram-negative anaerobic bacterium that was first isolated from the oral cavity and identified as a periodontal pathogen. Biofilms on oral squamous cell carcinomas are enriched with anaerobic periodontal pathogens, including F. nucleatum, which has prompted hypotheses that this bacterium could contribute to oral cancer development. Recent studies have demonstrated that F. nucleatum can promote cancer by several mechanisms; activation of cell proliferation, promotion of cellular invasion, induction of chronic inflammation and immune evasion. This review provides an update on the association between F. nucleatum and oral carcinogenesis, and provides insights into the possible mechanisms underlying it.

Prospects and Challenges of the Study of Anti-Glycan Antibodies and Microbiota for the Monitoring of Gastrointestinal Cancer

Over the past decades, a large amount of data has been accumulated in various subfields of glycobiology. However, much clinically relevant data and many tools are still not widely used in medicine. Synthetic glycoconjugates with the known structure of glycans are an accurate tool for the study of glycan-binding proteins. We used polyacrylamide glycoconjugates (PGs) including PGs with tumour-associated glycans (TAGs) in immunoassays to assess the prognostic potential of the serum level of anti-glycan antibodies (AG Abs) in gastrointestinal cancer patients and found an association of AG Abs with survival. The specificity of affinity-isolated AG Abs was investigated using synthetic and natural glycoconjugates. AG Abs showed mainly a low specificity to tumour-associated and tumour-derived mucins; therefore, the protective role of the examined circulating AG Abs against cancer remains a challenge. In this review, our findings are analysed and discussed in the context of the contribution of bacteria to the AG Abs stimulus and cancer progression. Examples of the influence of pathogenic bacteria colonising tumours on cancer progression and patient survival through mechanisms of interaction with tumours and dysregulated immune response are considered. The possibilities and problems of the integrative study of AG Abs and the microbiome using high-performance technologies are discussed.

New Frontiers on Adjuvants Drug Strategies and Treatments in Periodontitis

Causes of the progression of periodontitis such as an imbalance between the immune response by the host by the release of inflammatory mediators in the response of the oral pathogenic dysbiotic biofilm have been identified. New insights on specific cell signaling pathways that appear during periodontitis have attracted the attention of researchers in the study of new personalised approaches for the treatment of periodontitis. The gold standard of non-surgical therapy of periodontitis involves the removal of supra and subgingival biofilm through professional scaling and root planing (SRP) and oral hygiene instructions. In order to improve periodontal clinical outcomes and overcome the limitations of traditional SRP, additional adjuvants have been developed in recent decades, including local or systemic antibiotics, antiseptics, probiotics, anti-inflammatory and anti-resorptive drugs and host modulation therapies. This review is aimed to update the current and recent evolution of therapies of management of periodontitis based on the adjunctive and target therapies. Moreover, we discuss the advances in host modulation of periodontitis and the impact of targeting epigenetic mechanisms approaches for a personalised therapeutic success in the management of periodontitis. In conclusion, the future goal in periodontology will be to combine and personalise the periodontal treatments to the colonising microbial profile and to the specific response of the individual patient.

The baseline oral microbiota predicts the response of locally advanced oral squamous cell carcinoma patients to induction chemotherapy: A prospective longitudinal study

PURPOSE

Among oral squamous cell carcinoma (OSCC) patients who receive docetaxel, cisplatin, and 5-fluorouracil (TPF) induction chemotherapy, those with a favorable pathological response tend to obtain satisfactory clinical outcomes, while the total population exhibit no survival benefit. Thus, there is an urgent need to improve the therapeutic effect of TPF by applying personalized treatment according to distinct biomarkers.

METHODS AND MATERIALS

In the present study, we collected oral rinse samples from 44 OSCC patients enrolled in our prospective multicenter random phase II trial before TPF induction chemotherapy to conduct 16S rRNA gene sequencing and metagenomic analysis. Patients were administrated with two cycles of TPF induction chemotherapy (75 mg/m² cisplatin and 75 mg/m² docetaxel on day 1 and 750 mg/m² fluorouracil from the first to the fifth day), and then divided into responsive and nonresponsive groups according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

RESULTS

In the 16S rRNA gene sequence analysis, Fusobacterium and Mycoplasma were more enriched in the nonresponsive group, while Slackia was more enriched in the responder group at the genus level. In the metagenomic shotgun sequencing analysis, Fusobacterium nucleatum was more enriched in the nonresponsive group. Functional analysis showed that the platinum drug resistance pathway and microRNAs in cancer and RNA degradation pathways were remarkably associated with patient sensitivity to induction chemotherapy.

CONCLUSIONS

Our data suggest that the oral microbiome may play an important role in the OSCC patient sensitivity to TPF induction chemotherapy and offer novel potential biomarkers for predicting the response to TPF induction chemotherapy.

The oesophageal microbiome and cancer: hope or hype?

The human oesophagus is home to a complex microbial community, the oesophageal microbiome. Despite decades of work, we still have only a poor, low-resolution view of this community, which makes it hard to distinguish hope from hype when it comes to assessing links between the oesophageal microbiome and cancer. Here we review the potential importance of this microbiome and discuss new approaches, including culturomics, metagenomics, and recovery of whole-genome sequences, that bring renewed hope for an in-depth characterisation of this community that could deliver translational impact.

Microbiota and epigenetics: promising therapeutic approaches?

The direct/indirect responsibility of the gut microbiome in disease induction in and outside the digestive tract is well studied. These results are usually from the overpopulation of certain species on the cost of others, interaction with beneficial microflora, interference with normal epigenetic control mechanisms, or suppression of the immune system. Consequently, it is theoretically possible to cure such disorders by rebalancing the microbiome inside our bodies. This can be achieved by changing the lifestyle pattern and diet or by supplementation with beneficial bacteria or their metabolites. Various approaches have been explored to manipulate the normal microbial inhabitants, including nutraceutical, supplementations with prebiotics, probiotics, postbiotics, synbiotics, and antibiotics, or through microbiome transplantation (fecal, skin, or vaginal microbiome transplantation). In the present review, the interaction between the microbiome and epigenetics and their role in disease induction is discussed. Possible future therapeutic approaches via the reestablishment of equilibrium in our internal micro-ecosystem are also highlighted.

Quantitative difference of oral pathogen between individuals with gastric cancer and individuals without cancer

The loss of teeth and lack of oral hygiene have been associated with the risk of developing gastric cancer (GC) in several populations evidenced in epidemiological studies. In this study, we quantitatively compared the proportion of oral pathogens in individuals with gastric cancer and individuals without cancer in a referral hospital in the city of Belém, Brazil. This study evaluated 192 patients with GC and 192 patients without cancer. Periodontal clinical examination was performed, and all individuals were submitted to the collection of salivary and dental biofilms. When comparing the median periodontal indexes in the gastric and cancer-free groups, it was statistically significant (p < 0.001) in the gastric cancer group compared to the probing depth of the periodontal pocket. Levels of bacterial DNA were observed in saliva and dental plaque, with a statistically significant difference (p < 0.001) between individuals with cancer and without neoplasia in all the bacteria surveyed. Significant relationships (p < 0.001) between biological agents and GC have been found in bacterial species that cause high rates of periodontal pathology and caries. The results suggest a different quantitative association in the presence of oral pathogens between individuals without cancer and patients with GC. As noted, it cannot be said that the bacteria present in the oral cavity increase the risk of gastric cancer or are aggravating factors of the disease. However, it is worth mentioning that, as it is part of the digestive system, the lack of care for the oral cavity can negatively affect the treatment of patients with gastric cancer.

The Role of the Oral Microbiota in the Etiopathogenesis of Oral Squamous Cell Carcinoma

Dysbiosis in the oral environment may play a role in the etiopathogenesis of oral squamous cell carcinoma (OSCC). This review aims to summarize the current knowledge about the association of oral microbiota with OSCC and to describe possible etiopathogenetic mechanisms involved in processes of OSCC development and progression. Association studies included in this review were designed as case–control/case studies, analyzing the bacteriome, mycobiome, and virome from saliva, oral rinses, oral mucosal swabs, or oral mucosal tissue samples (deep and superficial) and comparing the results in healthy individuals to those with OSCC and/or with premalignant lesions. Changes in relative abundances of specific bacteria (e.g., Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sp.) and fungi (especially Candida sp.) were associated with OSCC. Viruses can also play a role; while the results of studies investigating the role of human papillomavirus in OSCC development are controversial, Epstein–Barr virus was positively correlated with OSCC. The oral microbiota has been linked to tumorigenesis through a variety of mechanisms, including the stimulation of cell proliferation, tumor invasiveness, angiogenesis, inhibition of cell apoptosis, induction of chronic inflammation, or production of oncometabolites. We also advocate for the necessity of performing a complex analysis of the microbiome in further studies and of standardizing the sampling procedures by establishing guidelines to support future meta-analyses.

Esophageal Cancer Associated Immune Genes as Biomarkers for Predicting Outcome in Upper Gastrointestinal Tumors

Esophageal cancer (EC) is the seventh most common tumor in the world, ranking the sixth leading cause of cancer death, with a 5-year survival rate of 15-25%. Therefore, reliable prognostic biomarkers are needed to effectively predict the prognosis of EC. In this study, the gene profile information of the EC cohort served as a training set, which was derived from TCGA and Immport databases. GO and KEGG enrichment analysis was performed on the differential genes in normal and tumor groups of EC. The immune genes in differentially expressed genes (DEGs) were further obtained for univariate and multivariate Cox and Lasso regression analysis, and 6 independent immune genes (S100A3, STC2, HSPA6, CCL25, GPER1, and OSM) associated with prognosis were obtained to establish an immune risk score signature (IRSS). The signature was validated using head and neck cancers (HNSC) and gastric cancer (GC)in upper gastrointestinal malignancies as validation sets. The Kaplan-Meier results showed that the prognosis of the high-risk group was significantly favorable than that of the low-risk group in both the training set (P < 0.001; HR = 3.68, 95% CI = 2.14−6.35) and the validation set (P = 0.010; HR = 1.43, 95% CI = 1.09−1.88). A nomogram combining multiple clinical information and IRSS was more effective than a single independent prognostic factor in predicting outcome. This study explored the potential link between immunity and EC, and established and validated prognostic biomarkers that can effectively predict the prognosis of EC, HNSC and GC based on six immune genes.

A Porphyromonas gingivalis Capsule-Conjugate Vaccine Protects From Experimental Oral Bone Loss

Periodontal diseases are chronic inflammatory diseases of the periodontium that result in progressive destruction of the soft and hard tissues supporting the teeth, and it is the most common cause of tooth loss among adults. In the US alone, over 100 million individuals are estimated to have periodontal disease. Subgingival bacteria initiate and sustain inflammation, and, although several bacteria have been associated with periodontitis, Porphyromonas gingivalis has emerged as the key etiological organism significantly contributing to the disease. Currently, intensive clinical maintenance strategies are deployed to mitigate the further progression of disease in afflicted individuals; however, these treatments often fail to stop disease progression, and, as such, the development of an effective vaccine for periodontal disease is highly desirable. We generated a conjugate vaccine, comprising of the purified capsular polysaccharide of P. gingivalis conjugated to eCRM®, a proprietary and enhanced version of the CRM197 carrier protein with predetermined conjugation sites (Pg-CV). Mice immunized with alum adjuvanted Pg-CV developed robust serum levels of whole organism-specific IgG in comparison to animals immunized with unconjugated capsular polysaccharide alone. Using the murine oral bone loss model, we observed that mice immunized with the capsule-conjugate vaccine were significantly protected from the effects of P. gingivalis-elicited oral bone loss. Employing a preclinical model of infection-elicited oral bone loss, our data support that a conjugate vaccine incorporating capsular polysaccharide antigen is effective in reducing the main clinical endpoint of periodontal disease-oral bone destruction. Further development of a P. gingivalis capsule-based conjugate vaccine for preventing periodontal diseases is supported.

Periodontitis as a risk factor for head and neck cancer

Background

Periodontitis may be associated with the development of head and neck cancer (HNC). A literature review was conducted to understand the possible association between them.

Material and Methods

Articles published in the PubMed database from January 1999 and May 2020 were retrieved. Limitations of the studies and biological mechanisms were discussed.

Results

A total of 4,232 articles were found. Of these, 13 were analyzed according to inclusion criteria. Most papers found some association between periodontitis and HNC, although differences in periodontal evaluation, sample size, study design and tumor sites were observed. Porphyromonas gingivalis appears to increase the chance of both diseases, and it may be one of their main potential risk factors. Genetic predisposition is increased by exposure to environmental factors which can directly induce epigenetic changes that contribute to these diseases.

Conclusions

Understanding the mechanisms related to periodontitis and HNC has increased, however, well-designed clinical studies are needed for better conclusions. Furthermore, the advent of multiple "omic" technologies will help comprehend their possible association.

Key words:Periodontitis, head and neck cancer, oral cancer, risk factors, biological factors.

Porphyromonas gingivalis induced up-regulation of PD-L1 in colon carcinoma cells

Programmed death-ligand-1 (PD-L1) is a ligand for programmed death receptor (PD-1) that plays a major role in cell-mediated immune response; it regulates T-cell activation and regulates survival and functions of activated T cells. Expression of PD-L1 can induce chronic inflammation and activate mechanisms of immune evasion. PD-L1 is expressed in most of human carcinomas. Porphyromonas gingivalis (P. gingivalis) is a major keystone pathogen in periodontitis that invade host cells and disposes a variety of virulence factors. The aim of the present study was to clarify the signaling pathway of P. gingivalis molecules that induce PD-L1 up-regulation in colon carcinoma cells. Additionally, it was investigated which components of P. gingivalis are responsible for PD-L1 induction. Colon cancer cells (CL-11) were stimulated with total membrane (TM) fractions, peptidoglycans (PDGs) and viable P. gingivalis bacteria. Seven signaling molecule inhibitors were used: receptor-interacting serine/threonine-protein kinase 2 (RIP2) tyrosine kinase inhibitor, nucleotide-binding oligomerization domain (NOD)-like receptor 1&2 inhibitor, NOD-like receptor, nuclear factor kappa B inhibitor, c-Jun N-terminal kinases inhibitor, mitogen-activated protein/extracellular signal-regulated kinase inhibitor, mitogen activated kinase (MAPK) inhibitor. PD-L1 protein expression was examined by western blot analysis and quantitative real time PCR. It was demonstrated that the TM fraction and PDG induced up-regulation of PD-L1 expression in colon cancer cells. In conclusion, the results of this study suggest that PDG of P. gingivalis plays a major role in PD-L1 up-regulation in colon cancer cells. In addition, the mechanism of PD-L1 up-regulation depends on NOD 1 and NOD 2 and involves activation of RIP2 and MAPK signaling pathways.

Environmental Influences on the Human Microbiome and Implications for Noncommunicable Disease

The human microbiome contributes metabolic functions, protects against pathogens, educates the immune system, and through these basic functions, directly or indirectly, affects most of our physiologic functions. Here, we consider the human microbiome and its relationship to several major noncommunicable human conditions, including orodigestive tract cancers, neurologic diseases, diabetes, and obesity. We also highlight the scope of contextual macroenvironmental factors (toxicological and chemical environment, built environment, and socioeconomic environment) and individual microenvironmental factors (smoking, alcohol, and diet) that may push the microbiota toward less healthy or more healthy conditions, influencing the development of these diseases. Last, we highlight current uncertainties and challenges in the study of environmental influences on the human microbiome and implications for understanding noncommunicable disease, suggesting a research agenda to strengthen the scientific evidence base.

Characterization of Human Genes Modulated by Porphyromonas gingivalis Highlights the Ribosome, Hypothalamus, and Cholinergic Neurons

Porphyromonas gingivalis, a bacterium associated with periodontal disease, is a suspected cause of Alzheimer's disease. This bacterium is reliant on gingipain proteases, which cleave host proteins after arginine and lysine residues. To characterize gingipain susceptibility, we performed enrichment analyses of arginine and lysine proportion proteome-wide. Genes differentially expressed in brain samples with detected P. gingivalis reads were also examined. Genes from these analyses were tested for functional enrichment and specific neuroanatomical expression patterns. Proteins in the SRP-dependent cotranslational protein targeting to membrane pathway were enriched for these residues and previously associated with periodontal and Alzheimer's disease. These ribosomal genes are up-regulated in prefrontal cortex samples with detected P. gingivalis sequences. Other differentially expressed genes have been previously associated with dementia (ITM2B, MAPT, ZNF267, and DHX37). For an anatomical perspective, we characterized the expression of the P. gingivalis associated genes in the mouse and human brain. This analysis highlighted the hypothalamus, cholinergic neurons, and the basal forebrain. Our results suggest markers of neural P. gingivalis infection and link the cholinergic and gingipain hypotheses of Alzheimer's disease.

A bacterial tyrosine phosphatase modulates cell proliferation through targeting RGCC

Tyrosine phosphatases are often weaponized by bacteria colonizing mucosal barriers to manipulate host cell signal transduction pathways. Porphyromonas gingivalis is a periodontal pathogen and emerging oncopathogen which interferes with gingival epithelial cell proliferation and migration, and induces a partial epithelial mesenchymal transition. P. gingivalis produces two tyrosine phosphatases, and we show here that the low molecular weight tyrosine phosphatase, Ltp1, is secreted within gingival epithelial cells and translocates to the nucleus. An ltp1 mutant of P. gingivalis showed a diminished ability to induce epithelial cell migration and proliferation. Ltp1 was also required for the transcriptional upregulation of Regulator of Growth and Cell Cycle (RGCC), one of the most differentially expressed genes in epithelial cells resulting from P. gingivalis infection. A phosphoarray and siRNA showed that P. gingivalis controlled RGCC expression through Akt, which was activated by phosphorylation on S473. Akt activation is opposed by PTEN, and P. gingivalis decreased the amount of PTEN in epithelial cells. Ectopically expressed Ltp1 bound to PTEN, and reduced phosphorylation of PTEN at Y336 which controls proteasomal degradation. Ltp-1 induced loss of PTEN stability was prevented by chemical inhibition of the proteasome. Knockdown of RGCC suppressed upregulation of Zeb2 and mesenchymal markers by P. gingivalis. RGCC inhibition was also accompanied by a reduction in production of the proinflammatory cytokine IL-6 in response to P. gingivalis. Elevated IL-6 levels can contribute to periodontal destruction, and the ltp1 mutant of P. gingivalis incited less bone loss compared to the parental strain in a murine model of periodontal disease. These results show that P. gingivalis can deliver Ltp1 within gingival epithelial cells, and establish PTEN as the target for Ltp1 phosphatase activity. Disruption of the Akt1/RGCC signaling axis by Ltp1 facilitates P. gingivalis-induced increases in epithelial cell migration, proliferation, EMT and inflammatory cytokine production.

Bacteria colonizing the oral cavity can induce inflammatory destruction of the periodontal tissues, and are increasingly associated with oral squamous cell carcinoma. P. gingivalis, a major periodontal pathogen, can subvert epithelial pathways that control important physiological processes relating to innate immunity and cell fate; however, little is known about the effector molecules. Here we show that P. gingivalis can deliver a tyrosine phosphatase, Ltp1, within epithelial cells, and Ltp1 phosphatase activity destabilizes PTEN, a negative regulator of Akt1 signaling. The production of RGCC is thus increased and this leads to increased epithelial cell migration, proliferation, a partial mesenchymal phenotype and inflammatory cytokine production. Ltp1 phosphatase activity thus provides a mechanistic basis for a number of P. gingivalis properties that contribute to disease. Indeed, an Ltp1-deficient mutant was less pathogenic in a murine model of periodontitis. These results contribute to deciphering the pathophysiological events that underlie oral bacterial diseases that initiate at mucosal barriers.

Periodontal microorganisms and diagnosis of malignancy: A cross-sectional study

BACKGROUND

Oral infections associate statistically with cancer.

OBJECTIVE

We hypothesized that certain periodontal microorganisms might specifically link to malignancies in general and set out to investigate this in our ongoing cohort study.

METHODS

A sample of 99 clinically examined patients from our cohort of 1676 subjects was used to statistically investigate the associations between harboring periodontal microorganisms Aggregatibacter actinomycetemcomitans (A.a), Porphyromonas gingivalis (P.g), Prevotella intermedia (P.i), Tannerella forsythia (T.f) and Treponema denticola (T.d). We used oral infection indexes and the incidence figures of malignancies as registered in 2008-2016 in the Swedish National Cancer Register.

RESULTS

The pathogen A.a showed strong association with malignancy in 32 out of the 99 patients while P.g and P.i were more prevalent among patients without malignancy. In principal component analyses, A.a appeared in the strongest component while the second strongest component consisted of a combination of T.f and T.d. The third component consisted of a combination of P.g and P.i, respectively. Of basic and oral health variables, gingival index appeared to be the strongest expression of inflammation (Eigen value 4.11 and Explained Variance 68.44 percent).

CONCLUSIONS

The results partly confirmed our hypothesis by showing that harboring certain periodontal bacteria might link to malignancy. However, the associations are statistical and no conclusions can be drawn about causality.

The human oral phageome

Oral bacteriophages (or phages), especially periodontal ones, constitute a growing area of interest, but research on oral phages is still in its infancy. Phages are bacterial viruses that may persist as intracellular parasitic deoxyribonucleic acid (DNA) or use bacterial metabolism to replicate and cause bacterial lysis. The microbiomes of saliva, oral mucosa, and dental plaque contain active phage virions, bacterial lysogens (ie, carrying dormant prophages), and bacterial strains containing short fragments of phage DNA. In excess of 2000 oral phages have been confirmed or predicted to infect species of the phyla Actinobacteria (>300 phages), Bacteroidetes (>300 phages), Firmicutes (>1000 phages), Fusobacteria (>200 phages), and Proteobacteria (>700 phages) and three additional phyla (few phages only). This article assesses the current knowledge of the diversity of the oral phage population and the mechanisms by which phages may impact the ecology of oral biofilms. The potential use of phage-based therapy to control major periodontal pathogens is also discussed.

Microbiota and cancer: In vitro and in vivo models to evaluate nanomedicines

Nanomedicine implication in cancer treatment and diagnosis studies witness huge attention, especially with the promising results obtained in preclinical studies. Despite this, only few nanomedicines succeeded to pass clinical phase. The human microbiota plays obvious roles in cancer development. Nanoparticles have been successfully used to modulate human microbiota and notably tumor associated microbiota. Taking the microbiota involvement under consideration when testing nanomedicines for cancer treatment might be a way to improve the poor translation from preclinical to clinical trials. Co-culture models of bacteria and cancer cells, as well as animal cancer-microbiota models offer a better representation for the tumor microenvironment and so potentially better platforms to test nanomedicine efficacy in cancer treatment. These models would allow closer representation of human cancer and might smoothen the passage from preclinical to clinical cancer studies for nanomedicine efficacy.

The oralome and its dysbiosis: New insights into oral microbiome-host interactions

The oralome is the summary of the dynamic interactions orchestrated between the ecological community of oral microorganisms (comprised of up to approximately 1000 species of bacteria, fungi, viruses, archaea and protozoa - the oral microbiome) that live in the oral cavity and the host. These microorganisms form a complex ecosystem that thrive in the dynamic oral environment in a symbiotic relationship with the human host. However, the microbial composition is significantly affected by interspecies and host-microbial interactions, which in turn, can impact the health and disease status of the host. In this review, we discuss the composition of the oralome and inter-species and host-microbial interactions that take place in the oral cavity and examine how these interactions change from healthy (eubiotic) to disease (dysbiotic) states. We further discuss the dysbiotic signatures associated with periodontitis and caries and their sequalae, (e.g., tooth/bone loss and pulpitis), and the systemic diseases associated with these oral diseases, such as infective endocarditis, atherosclerosis, diabetes, Alzheimer's disease and head and neck/oral cancer. We then discuss current computational techniques to assess dysbiotic oral microbiome changes. Lastly, we discuss current and novel techniques for modulation of the dysbiotic oral microbiome that may help in disease prevention and treatment, including standard hygiene methods, prebiotics, probiotics, use of nano-sized drug delivery systems (nano-DDS), extracellular polymeric matrix (EPM) disruption, and host response modulators.

Host surface ectonucleotidase-CD73 and the opportunistic pathogen, Porphyromonas gingivalis, cross-modulation underlies a new homeostatic mechanism for chronic bacterial survival in human epithelial cells

Cell surface nucleotide-metabolizing enzyme, ectonucleotidase-CD73, has emerged as a central component of the cellular homeostatic-machinery that counterbalances the danger-molecule (extracellular-ATP)-driven proinflammatory response in immune cells. While the importance of CD73 in microbial host fitness and symbiosis is gradually being unraveled, there remains a significant gap in knowledge of CD73 and its putative role in epithelial cells. Here, we depict a novel host-pathogen adaptation mechanism where CD73 takes a center role in the intracellular persistence of Porphyromonas gingivalis, a major colonizer of oral mucosa, using human primary gingival epithelial cell (GEC) system. Temporal analyses revealed, upon invasion into the GECs, P. gingivalis can significantly elevate the host-surface CD73 activity and expression. The enhanced and active CD73 significantly increases P. gingivalis intracellular growth in the presence of substrate-AMP and simultaneously acts as a negative regulator of reactive oxygen species (ROS) generation upon eATP treatment. The inhibition of CD73 by siRNA or by a specific inhibitor markedly increases ROS production. Moreover, CD73 and P. gingivalis cross-signaling significantly modulates pro-inflammatory interleukin-6 (IL-6) in the GECs. Conversely, exogenous treatment of the infected GECs with IL-6 suppresses the intracellular bacteria via amplified ROS generation. However, the decreased bacterial levels can be restored by overexpressing functionally active CD73. Together, these findings illuminate how the local extracellular-purine-metabolism, in which CD73 serves as a core molecular switch, can alter intracellular microbial colonization resistance. Further, host-adaptive pathogens such as P. gingivalis can target host ectonucleotidases to disarm specific innate defenses for successful intracellular persistence in mucosal epithelia.

HDAC1 regulates the chemosensitivity of laryngeal carcinoma cells via modulation of interleukin-8 expression

Chemotherapies such as 5-fluorouracil (5-FU) and cisplatin (CDDP) have been widely used to treat laryngeal squamous cell carcinoma (LSCC), the second most common head and neck squamous cell carcinoma. However, chemoresistance seriously impairs chemotherapeutic efficacy. Our present study reveals that 5-FU and CDDP treatment increase the expression of histone deacetylase 1 (HDAC1) in LSCC cells. Consistently, increased levels of HDAC1 are observed in chemoresistant cells. Knockdown of HDAC1 significantly restores the sensitivity of LSCC cells, as HDAC1 increases the expression of interleukin-8 (IL-8), which is essential for LSCC chemoresistance. Mechanistically, HDAC1 directly initiates the transcription of IL-8 though binding to its promoter. Simultaneously, si-HDAC1 increases the levels of miR-93, which binds to the 3'UTR of IL-8 mRNA to trigger its degradation. In summary, the HDAC1/IL-8 axis can confer chemotherapeutic resistance to LSCC cells.

Identification of the different salivary Interleukin-6 profiles in patients with periodontitis: A cross-sectional study

OBJECTIVE

The aim of this study was to analyze and identify the association among salivary interleukin-6 (IL-6) levels and periodontitis (PT) and to determine the significant trend of this association in PT patients.

STUDY DESIGN

For the present study, 49 patients with PT and 47 healthy subjects (HS) were enrolled and assessed for clinical parameters, blood samples and salivary IL-6 analyses. Clinical differences among groups were recorded and evaluated. The Spearman Correlation and the Jonckheere-Terpstra Test were applied in order to assess the interdependence between salivary IL-6 and PT.

RESULTS

Patients in the PT group had significantly higher median salivary IL-6 levels [195.4 (184.6-205.9 pg/mL)] compared to the HS group [101.9 (89.5-115.4 pg/mL) (p < 0.001). Salivary IL-6 levels were negatively correlated with C-reactive protein, with the number of teeth and with clinical attachment loss (CAL), probing pocket depth (PPD), and bleeding sites (FMBS) (p < 0.001). Furthermore, in patients with PT, salivary IL-6 levels were inversely associated (P-trend) with the number of teeth (p < 0.001), and directly associated with the proportional extent of PT (CAL, p = 0.006; PPD, p = 0.009; FMBS, p < 0.001).

CONCLUSIONS

The results of this study showed that PT patients presented significant higher salivary IL-6 levels compared to HS. Moreover, in the analyzed sample a significant p-trend among PT, tooth loss and increased salivary IL-6 levels was found.

Looking beyond the smokescreen: can the oral microbiome be a tool or target in the management of tobacco-associated oral cancer?

A wide range of microbes inhabit the oral cavity, and bacterial and fungal communities most often exist as structured communities or biofilms. The use of tobacco alters the structure of the oral microbiome, including that of potentially malignant lesions, and the altered oral microbiome influences key microenvironmental changes such as chronic inflammation, secretion of carcinogenic toxins, cellular and tissue remodelling and suppression of apoptosis. Given this, it is clear that the bacterial and fungal biofilms in potentially malignant states are likely not passive entities, but could play a critical role in shaping potential malignant and carcinogenic conditions. This holds potential towards leveraging the oral microbiome for the management of tobacco-associated potentially malignant lesions and oral cancer. Here, we explore this line of investigation by reviewing the effects of tobacco in shaping the oral microbiome, and analyse the available evidence in the light of the microbiome of oral potentially malignant and cancerous lesions, and the role of dysbiosis in carcinogenesis. Finally, we discuss possible interventions and approaches using which the oral microbiome could be leveraged towards precision-based oral cancer therapeutics.