The GroEL protein of Porphyromonas gingivalis accelerates tumor growth by enhancing endothelial progenitor cell function and neovascularization

Porphyromonas gingivalis GroEL accelerates abdominal aortic aneurysm formation by matrix metalloproteinase-2 SUMOylation in vascular smooth muscle cells: A novel finding for the activation of MMP-2

Infection is a known cause of abdominal aortic aneurysm (AAA), and matrix metalloproteases-2 (MMP-2) secreted by vascular smooth muscle cells (SMCs) plays a key role in the structural disruption of the middle layer of the arteries during AAA progression. The periodontal pathogen Porphyromonas gingivalis is highly associated with the progression of periodontitis. GroEL protein of periodontal pathogens is an important virulence factor that can invade the body through either the bloodstream or digestive tract and is associated with numerous systemic diseases. Although P. gingivalis aggravates AAA by increasing the expression of MMP-2 in animal studies, the molecular mechanism through which P. gingivalis regulates the expression of MMP-2 is still unknown and requires further investigation. In this study, we first confirmed through animal experiments that P. gingivalis GroEL promotes MMP-2 secretion from vascular SMCs, thereby aggravating Ang II-induced aortic remodeling and AAA formation. In addition, rat vascular SMCs and A7r5 cells were used to investigate the underlying mechanisms in vitro. The results demonstrated that GroEL can promote the interaction between the K639 site of MMP-2 and SUMO-1, leading to MMP-2 SUMOylation, which inhibits the reoccurrence of non-K639-mediated monoubiquitylation. Hence, the monoubiquitylation-mediated lysosomal degradation of MMP-2 is inhibited, consequently promoting MMP-2 stability and production. SUMOylation may facilitate intra-endoplasmic reticulum (ER) and Golgi trafficking of MMP-2, thereby enhancing its transport capacity. In conclusion, this is the first report demonstrating the presence of a novel posttranslational modification, SUMOylation, in the MMP family, suggesting that P. gingivalis GroEL may exacerbate AAA formation by increasing MMP-2 production through SUMOylation in vascular SMCs. This study also provides a novel perspective on the role of SUMOylation in MMP-2-induced systemic diseases.

About a Possible Impact of Endodontic Infections by Fusobacterium nucleatum or Porphyromonas gingivalis on Oral Carcinogenesis: A Literature Overview

Periodontitis is linked to the onset and progression of oral squamous cell carcinoma (OSCC), an epidemiologically frequent and clinically aggressive malignancy. In this context, Fusobacterium (F.) nucleatum and Porphyromonas (P.) gingivalis, two bacteria that cause periodontitis, are found in OSCC tissues as well as in oral premalignant lesions, where they exert pro-tumorigenic activities. Since the two bacteria are present also in endodontic diseases, playing a role in their pathogenesis, here we analyze the literature searching for information on the impact that endodontic infection by P. gingivalis or F. nucleatum could have on cellular and molecular events involved in oral carcinogenesis. Results from the reviewed papers indicate that infection by P. gingivalis and/or F. nucleatum triggers the production of inflammatory cytokines and growth factors in dental pulp cells or periodontal cells, affecting the survival, proliferation, invasion, and differentiation of OSCC cells. In addition, the two bacteria and the cytokines they induce halt the differentiation and stimulate the proliferation and invasion of stem cells populating the dental pulp or the periodontium. Although most of the literature confutes the possibility that bacteria-induced endodontic inflammatory diseases could impact on oral carcinogenesis, the papers we have analyzed and discussed herein recommend further investigations on this topic.

GroEL of Porphyromonas gingivalis-induced microRNAs accelerate tumor neovascularization by downregulating thrombomodulin expression in endothelial progenitor cells

We found that GroEL in Porphyromonas gingivalis accelerated tumor growth and increased mortality in tumor-bearing mice; GroEL promoted proangiogenic function, which may be the reason for promoting tumor growth. To understand the regulatory mechanisms by which GroEL increases the proangiogenic function of endothelial progenitor cells (EPCs), we explored in this study. In EPCs, MTT assay, wound-healing assay, and tube formation assay were performed to analyze its activity. Western blot and immunoprecipitation were used to study the protein expression along with next-generation sequencing for miRNA expression. Finally, a murine tumorigenesis animal model was used to confirm the results of in vitro. The results indicated that thrombomodulin (TM) direct interacts with PI3 K/Akt to inhibit the activation of signaling pathways. When the expression of TM is decreased by GroEL stimulation, molecules in the PI3 K/Akt signaling axis are released and activated, resulting in increased migration and tube formation of EPCs. In addition, GroEL inhibits TM mRNA expression by activating miR-1248, miR-1291, and miR-5701. Losing the functions of miR-1248, miR-1291, and miR-5701 can effectively alleviate the GroEL-induced decrease in TM protein levels and inhibit the proangiogenic abilities of EPCs. These results were also confirmed in animal experiments. In conclusion, the intracellular domain of the TM of EPCs plays a negative regulatory role in the proangiogenic capabilities of EPCs, mainly through direct interaction between TM and PI3 K/Akt to inhibit the activation of signaling pathways. The effects of GroEL on tumor growth can be reduced by inhibiting the proangiogenic properties of EPCs through the inhibition of the expression of specific miRNAs.

Periodontitis and progression of gastrointestinal cancer: current knowledge and future perspective

Periodontitis is a polymicrobial disorder caused by dysbiosis. Porphyromonas gingivalis (P.gingivalis) and Fusobacterium nucleatum (F.nucleatum) are pathobiont related to periodontitis pathogenesis and were found to be abundant in the intestinal mucosa of inflammatory bowel disease (IBD) and colorectal cancer (CRC) patients. Besides, periodontal infections have been found in a variety of tissues and organs, indicating that periodontitis is not just an inflammation limited to the oral cavity. Considering the possible translocation of pathobiont from the oral cavity to the gastrointestinal (GI) tract, this study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the relationship between periodontitis and GI malignancies by focusing on the oral/gut axis.

Potential Roles of Selectins in Periodontal Diseases and Associated Systemic Diseases: Could They Be Targets for Immunotherapy?

Periodontal diseases are predisposing factors to the development of many systemic disorders, which is often initiated via leukocyte infiltration and vascular inflammation. These diseases could significantly affect human health and quality of life. Hence, it is vital to explore effective therapies to prevent disease progression. Periodontitis, which is characterized by gingival bleeding, disruption of the gingival capillary's integrity, and irreversible destruction of the periodontal supporting bone, appears to be caused by overexpression of selectins in periodontal tissues. Selectins (P-, L-, and E-selectins) are vital members of adhesion molecules regulating inflammatory and immune responses. They are mainly located in platelets, leukocytes, and endothelial cells. Furthermore, selectins are involved in the immunopathogenesis of vascular inflammatory diseases, such as cardiovascular disease, diabetes, cancers, and so on, by mediating leukocyte recruitment, platelet activation, and alteration of endothelial barrier permeability. Therefore, selectins could be new immunotherapeutic targets for periodontal disorders and their associated systemic diseases since they play a crucial role in immune regulation and endothelium dysfunction. However, the research on selectins and their association with periodontal and systemic diseases remains limited. This review aims to discuss the critical roles of selectins in periodontitis and associated systemic disorders and highlights the potential of selectins as therapeutic targets.

Novel regimens of phytopolyphenols with cisplatin or memantine and ZnSO4 for synergistic inhibition of growth and gingipains of the cultured Porphyromonas gingivalis

Background/purpose

Porphyromonas gingivalis (P.g.) played a keystone pathogen not only in initiation and progression of periodontitis but also as a risk factor involved in systemic diseases (Alzheimer’s disease, cancers, diabetes, osteoporosis etc.). Developments of effective and safe drugs to inhibit P.g. growth are urgent. In this study, we aimed at approaching novel regimens so called (PTM) by combination of repurposing drugs including phytopolyphenols (P) (curcumin, tea polyphenols), targeting drugs (T) such as cisplatin or memantine and metal ions(M) (ZnSO₄).

Materials and methods

The synergistic (combination Index (CI) < 1) antiproliferation and anti-protease efficacies (IC50) of novel regimens on cultured P.g. were evaluated by OD600 and colorimetric method respectively.

Results

The results obtained revealed that these novel regimens (PTM) synergistically (combination index, CI < 1) exerted not only antiproliferative but also anti-gingipain protease effects of P.g. The concentrations for 50% inhibition (IC50) of novel regimens on P.g. growth and gingipains were greatly decreased as compared with those of cisplatin and memantine alone.

Conclusion

Since these novel regimens exerted potent anti-bacterial effects on both planktonic and biofilm P.g., it is encouraged for further preclinical and clinical trials.

Porphyromonas gingivalis lipopolysaccharide affects the angiogenic function of endothelial progenitor cells via Akt/FoxO1 signaling

AIMS

Endothelial progenitor cells (EPCs) function as the angiogenic switch of many physiological and pathological conditions. We aimed to investigate the effects of Porphyromonas gingivalis lipopolysaccharide on the angiogenic capacity of EPCs and delineate the underlying mechanisms.

MATERIALS AND METHODS

EPCs were isolated from human umbilical blood. CCK-8 assay was undertaken to analyze the cell viability. The migration and tube formation capacity were assessed by wound healing and tube formation, respectively. The protein expression of Akt/p-Akt, endothelial nitric oxide synthase (eNOS)/p-eNOS, and Forkhead box O1 (FoxO1)/p-FoxO1 was determined by Western blot. The intracellular localization of FoxO1 was evaluated by immunofluorescent staining.

RESULTS

P. gingivalis LPS at 10 μg/ml significantly increased the viability (10.9 ± 2.9%), migration (16.3 ± 3.1%), and tube formation (38.6 ± 5.5%) of EPCs, along with increased phosphorylation of Akt, eNOS, and FoxO1. Mechanistically, Akt inhibition by specific inhibitor wortmannin and FoxO1 forced expression by adenovirus transfection in EPCs markedly attenuated the P. gingivalis LPS-induced eNOS activation, tube formation, and migration. Moreover, P. gingivalis LPS-induced phosphorylation and nuclear exclusion of FoxO1 were blunted by Akt inhibition.

CONCLUSIONS

The present study suggests that P. gingivalis LPS could affect the angiogenic function of EPCs through the Akt/FoxO1 signaling. The current findings may shed light on the clinical association of periodontitis with aberrant angiogenesis seen in atherosclerotic plaque rupture.

Role of Porphyromonas gingivalis in oral and orodigestive squamous cell carcinoma

Oral and esophageal squamous cell carcinomas harbor a diverse microbiome that differs compositionally from precancerous and healthy tissues. Though causality is yet to be definitively established, emerging trends implicate periodontal pathogens such as Porphyromonas gingivalis as associated with the cancerous state. Moreover, infection with P. gingivalis correlates with a poor prognosis, and P. gingivalis is oncopathogenic in animal models. Mechanistically, properties of P. gingivalis that have been established in vitro and could promote tumor development include induction of a dysbiotic inflammatory microenvironment, inhibition of apoptosis, increased cell proliferation, enhanced angiogenesis, activation of epithelial-to-mesenchymal transition, and production of carcinogenic metabolites. The microbial community context is also relevant to oncopathogenicity, and consortia of P. gingivalis and Fusobacterium nucleatum are synergistically pathogenic in oral cancer models in vivo. In contrast, oral streptococci, such as Streptococcus gordonii, can antagonize protumorigenic epithelial cell phenotypes induced by P. gingivalis, indicating functionally specialized roles for bacteria in oncogenic communities. Consistent with the notion of the bacterial community constituting the etiologic unit, metatranscriptomic data indicate that functional, rather than compositional, properties of the tumor-associated communities have more relevance to cancer development. A consistent association of P. gingivalis with oral and orodigestive carcinoma could have diagnostic potential for early detection of these conditions that have a high incidence and low survival rates.

The pathogenic mechanism of oral bacteria and treatment with inhibitors

OBJECTIVES

The objective of this study was to introduce the evidence obtained through extensive research that periodontitis increases risk of many systemic diseases.

METHOD

Analysis of some oral bacteria (P. gingivalis, T. denticola, T. forsythia, A. actinomycetemcomitans, and F. nucleatum) and its related treatments and mediators by the specific methods (western blot, ELISA, etc).

RESULTS

This article reviews in detail the evidence obtained through extensive research that periodontitis increases risk of many systemic diseases, including cardiovascular disease, rheumatoid arthritis, and Alzheimer's disease. These diseases are known to be associated with some certain specific gram-negative bacteria as periodontal pathogens, which induce inflammation and related diseases through TLR receptors, kinases, transcriptional factors and other cytokines. We also reviewed the latest research for inhibitors against inflammation and related diseases that have potential to be further applied clinically. In addition, based on a large amount of research evidence, we draw two tables about the mechanism of disease caused by periodontal bacteria, so that readers can easily search and analyze these research results.

DISCUSSION

This review details how the periodontal bacteria and their virulence factors can trigger host immune defense and induce many systemic diseases via inflammation and invasion. This Review also addressed the latest research around inhibitors against inflammation.

Molecular Mechanisms Leading from Periodontal Disease to Cancer

Periodontitis is prevalent in half of the adult population and raises critical health concerns as it has been recently associated with an increased risk of cancer. While information about the topic remains somewhat scarce, a deeper understanding of the underlying mechanistic pathways promoting neoplasia in periodontitis patients is of fundamental importance. This manuscript presents the literature as well as a panel of tables and figures on the molecular mechanisms of Porphyromonas gingivalis and Fusobacterium nucleatum, two main oral pathogens in periodontitis pathology, involved in instigating tumorigenesis. We also present evidence for potential links between the RANKL–RANK signaling axis as well as circulating cytokines/leukocytes and carcinogenesis. Due to the nonconclusive data associating periodontitis and cancer reported in the case and cohort studies, we examine clinical trials relevant to the topic and summarize their outcome.

Is periodontitis a risk factor of benign or malignant colorectal tumor? A population-based cohort study

OBJECTIVE

To examine the risk of developing benign or malignant colorectal tumors in patients with periodontitis within 15 years using Taiwan's National Health Insurance Database.

BACKGROUND

Studies have shown that colorectal carcinoma often develops under inflammatory conditions and changes of microbiota in the gut. Recently, a link between Fusobacterium nucleatum, a periodontal pathogen, and colorectal carcinoma has been proposed. However, whether periodontitis is a risk of developing colorectal tumor remains uncertain.

METHODS

In total, 35 124 participants were enrolled from 2000 to 2015 to examine the development risk of benign colorectal tumors, including 11 708 patients with periodontitis who received therapy (group 1), 11 708 patients with periodontitis not receiving periodontal treatment (group 2), and 11 708 non-periodontitis controls after matching for gender, age, and index year. To examine the risk of developing colorectal malignancy, 11 720 participants were assigned to each of the three groups. Cox proportional hazards model and Kaplan-Meier methods were used to compare the risks. Sensitivity analysis was performed, excluding the diagnoses during the first 1 or 5 years.

RESULTS

After the follow-up, 177, 154, and 63 participants in group 1, group 2, and control group had benign colorectal tumors. Patients with periodontitis tended to be associated with a greater rate of having a benign colorectal tumor. The adjusted hazard ratios (aHRs) were 3.77 (95% confidence interval [CI] 2.01-4.82, p < .001) and 2.85 (95% CI 1.62-3.74, p < .001) for groups 1 and 2, respectively. Regarding the risk of malignant colorectal tumor, 20, 18, and 14 participants who developed malignant tumors were included in group 1, group 2, and control group; however, no significant increase in malignancy was observed in periodontitis groups (aHR1.92, 95% CI 0.74-2.36, p = .482; aHR 1.50, 95% CI 0.68-1.97, p = .529, for the two periodontitis groups, respectively).

CONCLUSIONS

The results of this study suggest that patients with periodontitis may have an increased risk of developing benign, but not malignant, colorectal tumors.

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.

[Research progress on the relationship between Porphyromonas gingivalis and the malignancy of the digestive system and possible pathogenetic mechanism]

The malignant tumors including oral cancer, colorectal cancer, pancreatic cancer, and esophageal cancer, of the digestive system are a common high-fatal malignancy. Porphyromonas gingivalis, as the most important pathogen of periodontal disease, has been gradually proved that its invasiveness occurs not only in the mouth but also in other parts of the digestive system. Moreover, the relevant pathogenic mechanism is increasingly attracting the reseachers' attention. In this study, the role and possible pathogenesis of Porphyromonas gingivalis in the digestive system are described in a systematic and comprehensive way.

Analysis of Fusobacterium nucleatum and Streptococcus gallolyticus in saliva of colorectal cancer patients

Aim: The aim of the study was to examine the prevalence and amount of Fusobacterium nucleatum (Fn), Porphyromonas gingivalis (Pg) and Streptococcus gallolyticus (Sg) in the saliva of colorectal cancer (CRC) patients and controls. Methods: PCR analyses performed in 71 CRC patients and 77 controls. Results: Saliva samples of patients had higher amounts of Fn (p = 0.001) and Sg (p < 0.001) compared with controls. Amount of Fn and Sg were lower in the microsatellite instability (+) group. Evaluation of salivary Sg amount by receiver operating characteristics analysis found to have diagnostic value for CRC (AUC: 0.84, 95% CI: 0.72-0.96). Conclusion: We found higher amounts of Fn and Sg in the saliva of CRC patients. Salivary Sg could helpful in distinction of CRC.

Chronic Inflammation as a Link between Periodontitis and Carcinogenesis

Periodontitis is characterized by a chronic inflammation produced in response to a disease-associated multispecies bacterial community in the subgingival region. Although the inflammatory processes occur locally in the oral cavity, several studies have determined that inflammatory mediators produced during periodontitis, as well as subgingival species and bacterial components, can disseminate from the oral cavity, contributing therefore, to various extraoral diseases like cancer. Interestingly, carcinogenesis associated with periodontal species has been observed in both the oral cavity and in extra oral sites. In this review, several studies were summarized showing a strong association between orodigestive cancers and poor oral health, presence of periodontitis-associated bacteria, tooth loss, and clinical signs of periodontitis. Proinflammatory pathways were also summarized. Such pathways are activated either by mono- or polymicrobial infections, resulting in an increase in the expression of proinflammatory molecules such as IL-6, IL-8, IL-1β, and TNF-α. In addition, it has been shown that several periodontitis-associated species induce the expression of genes related to cell proliferation, cell cycle, apoptosis, transport, and immune and inflammatory responses. Intriguingly, many of these pathways are linked to carcinogenesis. Among them, the activation of Toll-like receptors (TLRs) and antiapoptotic pathways (such as the PI3K/Akt, JAK/STAT, and MAPK pathways), the reduction of proapoptotic protein expression, the increase in cell migration and invasion, and the enhancement in metastasis are addressed. Considering that periodontitis is a polymicrobial disease, it is likely that mixed species promote carcinogenesis both in the oral cavity and in extra oral tissues and probably—as observed in periodontitis—synergistic and/or antagonistic interactions occur between microbes in the community. To date, a good amount of studies has allowed us to understand how monospecies infections activate pathways involved in tumorigenesis; however, more studies are needed to determine the combined effect of oral species in carcinogenesis.

Oral cancer cells sustainedly infected with Porphyromonas gingivalis exhibit resistance to Taxol and have higher metastatic potential

Major obstacles to improving the prognosis of patients with oral squamous cell carcinoma (OSCC) are the acquisition of resistance to chemotherapeutic agents and development of metastases. Recently, inflammatory signals are suggested to be one of the most important factors in modulating chemoresistance and establishing metastatic lesions. In addition, epidemiological studies have demonstrated that periodontitis, the most common chronic inflammatory condition of the oral cavity, is closely associated with oral cancer. However, a correlation between chronic periodontitis and chemoresistance/metastasis has not been well established. Herein, we will present our study on whether sustained infection with Porphyromonas gingivalis, a major pathogen of chronic periodontitis, could modify the response of OSCC cells to chemotherapeutic agents and their metastatic capability in vivo. Tumor xenografts composed of P. gingivalis–infected OSCC cells demonstrated a higher resistance to Taxol through Notch1 activation, as compared with uninfected cells. Furthermore, P. gingivalis–infected OSCC cells formed more metastatic foci in the lung than uninfected cells.

Comparison of inherently essential genes of Porphyromonas gingivalis identified in two transposon-sequencing libraries

Porphyromonas gingivalis is a Gram-negative anaerobe and keystone periodontal pathogen. A mariner transposon insertion mutant library has recently been used to define 463 genes as putatively essential for the in vitro growth of P. gingivalis ATCC 33277 in planktonic culture (Library 1). We have independently generated a transposon insertion mutant library (Library 2) for the same P. gingivalis strain and herein compare genes that are putatively essential for in vitro growth in complex media, as defined by both libraries. In all, 281 genes (61%) identified by Library 1 were common to Library 2. Many of these common genes are involved in fundamentally important metabolic pathways, notably pyrimidine cycling as well as lipopolysaccharide, peptidoglycan, pantothenate and coenzyme A biosynthesis, and nicotinate and nicotinamide metabolism. Also in common are genes encoding heat-shock protein homologues, sigma factors, enzymes with proteolytic activity, and the majority of sec-related protein export genes. In addition to facilitating a better understanding of critical physiological processes, transposon-sequencing technology has the potential to identify novel strategies for the control of P. gingivalis infections. Those genes defined as essential by two independently generated TnSeq mutant libraries are likely to represent particularly attractive therapeutic targets.

Prelude to oral microbes and chronic diseases: past, present and future

Associations between oral and systemic health are ancient. Oral opportunistic bacteria, particularly, Porphyromonas gingivalis and Fusobacterium nucleatum, have recently been deviated from their traditional roles as periodontal pathogens and arguably ascended to central players based on their participations in complex co-dependent mechanisms of diverse systemic chronic diseases risk and pathogenesis, including cancers, rheumatoid-arthritis, and diabetes.