Clinical significance and prognostic value of Porphyromonas gingivalis infection in lung cancer

A variety of pathogenic microorganisms can promote the occurrence and development of malignant tumors by colonizing in the body. It has been shown that Porphyromonas gingivalis (P. gingivalis) can be colonized for a long time in upper gastrointestinal tumors and is closely related to the occurrence and development of esophageal cancer in previous studies of our team. Because the esophagus and trachea are closely adjacent and P. gingivalis can instantly enter and colonize in cells, we speculate that P. gingivalis may be colonized in lung cancer cells through oral or blood, promoting the malignant progression of lung cancer. In this study, we investigated P. gingivalis infection in lung carcinoma tissues and adjacent lung tissues, and found that the colonization rate of P. gingivalis in carcinoma tissues was significantly higher than that in adjacent lung tissues. Therefore, we propose that the microenvironment of cancer cells is more conducive to the survival of P. gingivalis. Then, we analyzed the correlation between P. gingivalis infection and clinicopathological features and survival prognosis of patients with lung cancer. It was found that P. gingivalis infection was closely related to smoking, drinking, lymph node metastasis and clinical stage. Moreover, the survival rate and median survival time of patients with P. gingivalis infection were significantly shortened. Therefore, we put forward the view that long term smoking and drinking will cause a bad oral environment, increasing the risk of P. gingivalis infection, then P. gingivalis infection will promote the malignant progression of lung cancer.     

Porphyromonas gingivalis increases the invasiveness of oral cancer cells by upregulating IL-8 and MMPs

Recent studies indicate that chronic inflammation promotes the aggressiveness of cancers. However, the direct molecular mechanisms underlying a functional link between chronic periodontitis, the most common form of oral inflammatory diseases, and the malignancy of oral cancer remain unknown. To elucidate the role of chronic periodontitis in progression of oral cancer, we examined the effect of Porphyromonas gingivalis (P. gingivalis), a major pathogen that causes chronic periodontitis, on the invasiveness of oral squamous cell carcinoma (OSCC) cells, including SCC-25, OSC-20 and SAS cells. Exposures to P. gingivalis promoted the invasive ability of OSC-20 and SAS cells via the upregulation of matrix metalloproteinases (MMPs), specifically MMP-1 and MMP-2. However, P. gingivalis-infected SCC-25 cells did not exhibit changes in their invasive properties or the low expression levels of MMPs. In an effort to delineate the molecular players that control the invasiveness, we first assessed the level of interleukin-8 (IL-8), a well-known inflammatory cytokine, in P. gingivalis-infected OSCC cells. IL-8 secretion was substantially increased in the OSC-20 and SAS cells, but not in the SCC-25 cells, following P. gingivalis infection. When IL-8 was directly applied to SCC-25 cells, their invasive ability and MMP level were significantly increased. Furthermore, the downregulation of IL-8 in P. gingivalis-infected OSC-20 and SAS cells attenuated their invasive potentials and MMP levels. Taken together, our findings strongly suggest that P. gingivalis infection plays an important role in the promotion of the invasive potential of OSCC cells via the upregulation of IL-8 and MMPs.     

Active Invasion of Oral and Aortic Tissues by Porphyromonas gingivalis in Mice Causally Links Periodontitis and Atherosclerosis

Atherosclerotic vascular disease is a leading cause of myocardial infarction and cerebrovascular accident, and independent associations with periodontal disease (PD) are reported. PD is caused by polymicrobial infections and aggressive immune responses. Genomic DNA of Porphyromonas gingivalis, the best-studied bacterial pathogen associated with severe PD, is detected within atherosclerotic plaque. We examined causal relationships between chronic P. gingivalis oral infection, PD, and atherosclerosis in hyperlipidemic ApoE^null mice. ApoE^null mice (n = 24) were orally infected with P. gingivalis for 12 and 24 weeks. PD was assessed by standard clinical measurements while the aorta was examined for atherosclerotic lesions and inflammatory markers by array. Systemic inflammatory markers serum amyloid A, nitric oxide, and oxidized low-density lipoprotein were analyzed. P. gingivalis infection elicited specific antibodies and alveolar bone loss. Fluorescent in situ hybridization detected viable P. gingivalis within oral epithelium and aorta, and genomic DNA was detected within systemic organs. Aortic plaque area was significantly increased in P. gingivalis-infected mice at 24 weeks (P<0.01). Aortic RNA and protein arrays indicated a strong Th2 response. Chronic oral infection with P. gingivalis results in a specific immune response, significant increases in oral bone resorption, aortic inflammation, viable bacteria in oral epithelium and aorta, and plaque development.     

1,2,3-Triazole-based inhibitors of Porphyromonas gingivalis adherence to oral streptococci and biofilm formation

The development and use of small-molecule inhibitors of the adherence of Porphyromonas gingivalis to oral streptococci represents a potential therapy for the treatment of periodontal disease as these organisms work in tandem to colonize the oral cavity. Earlier work from these laboratories demonstrated that a small synthetic peptide was an effective inhibitor of the interaction between P. gingivalis and Streptococcus gordonii and that a small-molecule peptidomimetic would provide a more stable, less expensive and more effective inhibitor. An array of 2-(azidomethyl)- and 2-(azidophenyl)-4,5-diaryloxazoles having a full range of hydrophobic groups were prepared and reacted with substituted arylacetylenes to afford the corresponding ‘click’ products. The title compounds were evaluated for their ability to inhibit P. gingivalis’ adherence to oral streptococci and several were found to be inhibitory in the range of (IC₅₀) 5.3–67 μM.     

Inhibitory effect of Porphyromonas gingivalis-derived phosphoethanolamine dihydroceramide on acid ceramidase expression in oral squamous cells

The maintenance of diminished acid ceramidase (ASAH1) gene expression leading to the accumulation of antiproliferative intracellular ceramides in oral squamous cell carcinoma (OSCC) has emerged as a prospective oral cancer therapeutic regimen. Our published study demonstrated that the key periodontal pathogen Porphyromonas gingivalis downregulates the expression patterns of ASAH1 mRNA in normal epithelial cells in vitro. Therefore, P. gingivalis may also beneficially diminish the expression of ASAH1 in OSCC. Because a uniquely structured P. gingivalis-derived phosphoethanolamine dihydroceramide (PEDHC) inhibits the proliferation of normal human fibroblasts, this study aimed to test the effect of PEDHC on the survival of human oral squamous OECM-1 cells in vitro. We demonstrated that the P. gingivalis dihydroceramide-null (ΔPG1780) strain upregulates the expression of ASAH1 mRNA and promotes aggressive proliferation and migration of OECM-1 cells compared to the parent P. gingivalis-W83 strain. In addition, the intracellular concentration of ceramides was dramatically elevated in OECM-1 cells exposed to PEDHC in vitro. Furthermore, PEDHC inhibited expression patterns of ASAH1 mRNA as well as some genes associated with degradation of the basement membranes and extracellular matrix, for example, MMP-2, ADAM-17 and IL-6, in OECM-1 cells. Altogether, these data indicated that PEDHC produced by P. gingivalis inhibits acid ceramidase expression, promotes intracellular ceramide accumulation and suppresses the survival and migration of OSCC cells in vitro. Further studies are needed to determine molecular mechanisms of PEDHC-mediated inhibitory effect(s) on OSCC using in vivo models of oral cancer.     

Interleukin-29 modulates proinflammatory cytokine production in synovial inflammation of rheumatoid arthritis

Introduction

The association between rheumatoid arthritis (RA) and periodontitis is suggested to be linked to the periodontal pathogen Porphyromonas gingivalis. Colonization of P. gingivalis in the oral cavity of RA patients has been scarcely considered. To further explore whether the association between periodontitis and RA is dependent on P. gingivalis, we compared host immune responses in RA patients with and without periodontitis in relation to presence of cultivable P. gingivalis in subgingival plaque.

Methods

In 95 RA patients, the periodontal condition was examined using the Dutch Periodontal Screening Index for treatment needs. Subgingival plaque samples were tested for presence of P. gingivalis by anaerobic culture technique. IgA, IgG and IgM antibody titers to P. gingivalis were measured by ELISA. Serum and subgingival plaque measures were compared to a matched control group of non-RA subjects.

Results

A higher prevalence of severe periodontitis was observed in RA patients in comparison to matched non-RA controls (27% versus 12%, p < 0.001). RA patients with severe periodontitis had higher DAS28 scores than RA patients with no or moderate periodontitis (p < 0.001), while no differences were seen in IgM-RF or ACPA reactivity. Furthermore, RA patients with severe periodontitis had higher IgG- and IgM-anti P. gingivalis titers than non-RA controls with severe periodontitis (p < 0.01 resp. p < 0.05), although subgingival occurrence of P. gingivalis was not different.

Conclusions

Severity of periodontitis is related to severity of RA. RA patients with severe periodontitis have a more robust antibody response against P. gingivalis than non-RA controls, but not all RA patients have cultivable P. gingivalis.     

Porphyromonas gingivalis induces the production of interleukin‐31 by human mast cells,resulting in dysfunction of the gingival epithelial barrier

Interleukin (IL)‐31 is important for innate immunity in mucosal tissues and skin, and increased IL‐31 expression participates in the pathogenesis of chronic inflammatory diseases affecting the skin, airways, lungs, and intestines. We investigated the contribution of mast cells to the induction of IL‐31 production following infection with the periodontal pathogen, Porphyromonas gingivalis. We found that oral infection with P. gingivalis increased IL‐31 expression in the gingival tissues of wild‐type mice but not in those of mast cell‐deficient mice. The P. gingivalis‐induced IL‐31 production by human mast cells occurred through the activation of the JNK and NF‐κB signalling pathways and was dependent on the P. gingivalis lysine‐specific protease gingipain‐K. P. gingivalis infection induced IL‐31 receptor α and oncostatin M receptor β expression in human gingival epithelial cells. Notably, the P. gingivalis‐induced IL‐31 production by mast cells led to the downregulation of claudin‐1, a tight junction molecule, in gingival epithelial cells, resulting in an IL‐31‐dependent increase in the paracellular permeability of the gingival epithelial barrier. These findings suggest that IL‐31 produced by mast cells in response to P. gingivalis infection causes gingival epithelial barrier dysfunction, which may contribute to the chronic inflammation observed in periodontitis.     

Antimicrobial activity and mechanism of action of a novel cationic α-helical octadecapeptide derived from heat shock protein 70 of rice

Hsp70(241–258), an octadecapeptide derived from the heat shock protein 70 (Hsp70) of rice (Oryza sativa L. japonica), is a novel cationic α-helical antimicrobial peptide (AMP) that contains four lysine, two arginine, and two histidine residues. The antimicrobial activity of Hsp70(241–258) against Porphyromonas gingivalis, a periodontal pathogen, and Candida albicans, an opportunistic fungal pathogen, was quantitatively evaluated using a chemiluminescence method that measures ATP derived from viable cells. The 50% growth-inhibitory concentrations of Hsp70(241–258) against P. gingivalis and C. albicans cells were 63 μM and 70 μM, respectively. Hsp70(241–258) had little or no hemolytic activity even at 1 mM, and showed negligible cytotoxicity up to 300 μM. The degrees of calcein leakage from large unilamellar vesicles, which mimic the membranes of Gram-negative bacteria, and 3,3′-dipropylthiadicarbocyanine iodide release from P. gingivalis cells induced by the addition of Hsp70(241–258) increased in a concentration-dependent manner. When Hsp70(241–258) was added to calcein-acetoxymethyl ester-loaded C. albicans cells, calcein release from the cells increased in a concentration-dependent manner. Flow cytometric analysis also showed that the percentages of C. albicans cells stained with propidium iodide, a DNA-intercalating dye, increased as the concentration of Hsp70(241–258) added was increased. Therefore, Hsp70(241–258) appears to exhibit antimicrobial activity against P. gingivalis and C. albicans through membrane disruption. These results suggest that Hsp70(241–258) could be useful as a safe and potent AMP against P. gingivalis and C. albicans in many fields of health care, especially in the control of oral infections.     

Synthesis and Assembly of <Emphasis Type="Italic">Porphyromonas gingivalis</Emphasis> Fimbrial Protein in Potato Tissues

Periodontal disease caused by the gram-negative oral anaerobic bacterium Porphyromonas gingivalis is thought to be initiated by the binding of P. gingivalis fimbrial protein to saliva-coated oral surfaces. To assess whether biologically active fimbrial antigen can be synthesized in edible plants, a cDNA fragment encoding the C-terminal binding portion of P. gingivalis fimbrial protein, fimA (amino acids 266–337), was cloned behind the mannopine synthase promoter in plant expression vector pPCV701. The plasmid was transferred into potato (Solanum tuberosum) leaf cells by Agrobacterium tumefaciens in vivo transformation methods. The fimA cDNA fragment was detected in transformed potato leaf genomic DNA by PCR amplification methods. Further, a novel immunoreactive protein band of ~6.5 kDa was detected in boiled transformed potato tuber extracts by acrylamide gel electrophoresis and immunoblot analysis methods using primary antibodies to fimbrillin, a monomeric P. gingivalis fimbrial subunit. Antibodies generated against native P. gingivalis fimbriae detected a dimeric form of bacterial-synthesized recombinant FimA(266–337) protein. Further, a protein band of ~160 kDa was recognized by anti-FimA antibodies in undenatured transformed tuber extracts, suggesting that oligomeric assembly of plant-synthesized FimA may occur in transformed plant cells. Based on immunoblot analysis, the maximum amount of FimA protein synthesized in transformed potato tuber tissues was approximately 0.03% of total soluble tuber protein. Biosynthesis of immunologically detectable FimA protein and assembly of fimbrial antigen subunits into oligomers in transformed potato tuber tissues demonstrate the feasibility of producing native FimA protein in edible plant cells for construction of plant-based oral subunit vaccines against periodontal disease caused by P. gingivalis.     

Distinct Lipid A Moieties Contribute to Pathogen-Induced Site-Specific Vascular Inflammation

Several successful pathogens have evolved mechanisms to evade host defense, resulting in the establishment of persistent and chronic infections. One such pathogen, Porphyromonas gingivalis, induces chronic low-grade inflammation associated with local inflammatory bone loss and systemic inflammation manifested as atherosclerosis. P. gingivalis expresses an atypical lipopolysaccharide (LPS) structure containing heterogeneous lipid A species, that exhibit Toll-like receptor-4 (TLR4) agonist or antagonist activity, or are non-activating at TLR4. In this study, we utilized a series of P. gingivalis lipid A mutants to demonstrate that antagonistic lipid A structures enable the pathogen to evade TLR4-mediated bactericidal activity in macrophages resulting in systemic inflammation. Production of antagonistic lipid A was associated with the induction of low levels of TLR4-dependent proinflammatory mediators, failed activation of the inflammasome and increased bacterial survival in macrophages. Oral infection of ApoE^−/− mice with the P. gingivalis strain expressing antagonistic lipid A resulted in vascular inflammation, macrophage accumulation and atherosclerosis progression. In contrast, a P. gingivalis strain producing exclusively agonistic lipid A augmented levels of proinflammatory mediators and activated the inflammasome in a caspase-11-dependent manner, resulting in host cell lysis and decreased bacterial survival. ApoE^−/− mice infected with this strain exhibited diminished vascular inflammation, macrophage accumulation, and atherosclerosis progression. Notably, the ability of P. gingivalis to induce local inflammatory bone loss was independent of lipid A expression, indicative of distinct mechanisms for induction of local versus systemic inflammation by this pathogen. Collectively, our results point to a pivotal role for activation of the non-canonical inflammasome in P. gingivalis infection and demonstrate that P. gingivalis evades immune detection at TLR4 facilitating chronic inflammation in the vasculature. These studies support the emerging concept that pathogen-mediated chronic inflammatory disorders result from specific pathogen-mediated evasion strategies resulting in low-grade chronic inflammation.     

Antimicrobial Activity of Antrodia camphorata Extracts against Oral Bacteria

Antrodia camphorata (A. camphorata) is a unique, endemic and extremely rare mushroom species native to Taiwan, and both crude extracts of and purified chemical compounds from A. camphorata have been reported to have a variety of significant beneficial effects, such as anti-tumor and anti-inflammatory activity. However, reports on the effects of A. camphorata against dental pathogens have been limited. Oral health is now recognized as important for overall general health, including conditions such as dental caries, periodontal disease and rheumatoid arthritis. Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) are the most common bacteria associated with dental plaque and periodontopathic diseases, respectively. Thus, our study examined the ability of five various crude extracts of A. camphorata to inhibit the growth of dental bacteria and anti-adherence in vitro. Among the extracts, the ethanol, ethyl acetate and chloroform extracts exhibited the lowest MICs against P. gingivalis and S. mutans (MIC = 4∼16 µg/mL). The MIC of the aqueous extract was greater than 2048 µg/mL against both P. gingivalis and S. mutans. In vitro adherence of S. mutans was significantly inhibited by the addition of either the ethyl acetate extract or chloroform extract (MIC = 16∼24 µg/mL), while the ethanol extract (MIC = 32∼64 µg/mL) exhibited moderate inhibitory activity. Based on the result of this study, the ethyl acetate and chloroform extracts of A. camphorata may be good candidates for oral hygiene agents to control dental caries and periodontopathic conditions.     

Inhibition de l'adhérence de Porphyromonas gingivalis sur la surface de titane greffé de poly(styrène sulfonate de sodium)

Dental implant-associated infections as peri-implantitis represent one of the major causes of osteointegration failures of oral implants. Adhesion of Porphyromonas gingivalis, one of the bacterial strains mainly involved in such infections, is tightly dependent on the topographical and/or physico-chemical properties of the implant surfaces. As a matter of fact, we showed that the grafting of one bioactive polymer such as poly(sodium styrene sulfonate) onto titanium implant surfaces allowed a sensitive decrease of Staphylococcus aureus adhesion (> 40%). The aim of the study consists in evaluating the adhesion of P. gingivalis onto titanium surfaces grafted with poly(sodium stryrene sulfonate) in order to elaborate implants exhibiting appropriate inhibiting properties towards the adhesion of periodontal pathogens. The grafting of poly(sodium stryrene sulfonate) onto titanium surfaces is carried out in two steps: chemical oxydation of titanium to initiate radical species then grafting of poly(sodium stryrene sulfonate) by radical polymerization. Chemical characterization of the surfaces is achieved by Fourier transformed infrared spectroscopy (FTIR). Bacterial adhesion was studied on grafted and non grafted (control) titanium surfaces, preadsorbed or not by plasmatic proteins. Protein adsorption as well as bacteria adhesion is followed by fluorescence spectroscopy by using proteins or bacteria previously labelled with fluorescence probes; the quantification of adsorption and bacteria adhesion are performed by image analysis. Results showed that protein adsorption is more important (~3 times) and that P. gingivalis adhesion is strongly inhibited (~73%) onto poly(sodium styrene sulfonate) grafted surfaces when compared to titanium control. Moreover, the inhibition of bacterial adhesion on grafted surfaces preadsorbed with plasma proteins is comparable to that observed on grafted surfaces preadsorbed with fibronectin. In conclusion, the obtained results evidenced that the grafting of titanium surface by poly(sodium styrene sulfonate) led to significant inhibition of P. gingivalis adhesion and that this inhibitory activity involved adsorbed proteins. Poly(sodium styrene sulfonate) grafted titanium surfaces present a high interest for the elaboration of oral implants in various clinical dental applications.     

RNAi-Mediated Silencing of Atp6i and Atp6i Haploinsufficiency Prevents Both Bone Loss and Inflammation in a Mouse Model of Periodontal Disease

Periodontal disease affects about 80% of adults in America, and is characterized by oral bacterial infection-induced gingival inflammation, oral bone resorption, and tooth loss. Periodontitis is also associated with other diseases such as rheumatoid arthritis, diabetes, and heart disease. Although many efforts have been made to develop effective therapies for this disease, none have been very effective and there is still an urgent need for better treatments and preventative strategies. Herein we explored for the first time the possibility that adeno-associated virus (AAV)-mediated RNAi knockdown could be used to treat periodontal disease with improved efficacy. For this purpose, we used AAV-mediated RNAi knockdown of Atp6i/TIRC7 gene expression to target bone resorption and gingival inflammation simultaneously. Mice were infected with the oral pathogen Porphyromonas gingivalis W50 (P. gingivalis) in the maxillary periodontium to induce periodontitis. We found that Atp6i depletion impaired extracellular acidification and osteoclast-mediated bone resorption. Furthermore, local injection of AAV-shRNA-Atp6i/TIRC7 into the periodontal tissues in vivo protected mice from P. gingivalis infection-stimulated bone resorption by >85% and decreased the T-cell number in periodontal tissues. Notably, AAV-mediated Atp6i/TIRC7 knockdown also reduced the expression of osteoclast marker genes and inflammation-induced cytokine genes. Atp6i^+/− mice with haploinsufficiency were similarly protected from P. gingivalis infection-stimulated bone loss and gingival inflammation. This suggests that AAV-shRNA-Atp6i/TIRC7 therapeutic treatment may significantly improve the health of millions who suffer from P. gingivalis-mediated periodontal disease.     

Functional Advantages of Porphyromonas gingivalis Vesicles

Porphyromonas gingivalis is a keystone pathogen of periodontitis. Outer membrane vesicles (OMVs) have been considered as both offense and defense components of this bacterium. Previous studies indicated that like their originating cells, P. gingivalis vesicles, are able to invade oral epithelial cells and gingival fibroblasts, in order to promote aggregation of some specific oral bacteria and to induce host immune responses. In the present study, we investigated the invasive efficiency of P. gingivalis OMVs and compared results with that of the originating cells. Results revealed that 70–90% of human primary oral epithelial cells, gingival fibroblasts, and human umbilical vein endothelial cells carried vesicles from P. gingivalis 33277 after being exposed to the vesicles for 1 h, while 20–50% of the host cells had internalized P. gingivalis cells. We also detected vesicle-associated DNA and RNA and a vesicle-mediated horizontal gene transfer in P. gingivalis strains, which represents a novel mechanism for gene transfer between P. gingivalis strains. Moreover, purified vesicles of P. gingivalis appear to have a negative impact on biofilm formation and the maintenance of Streptococcus gordonii. Our results suggest that vesicles are likely the best offence weapon of P. gingivalis for bacterial survival in the oral cavity and for induction of periodontitis.     

Quantification of five putative periodontal pathogens in female patients with and without chronic periodontitis by real-time polymerase chain reaction

Chronic periodontitis is a highly prevalent endogenous polymicrobial disease. To better understand the etiology of the disease a quantitative approach is mandatory and real-time PCR is the molecular technique currently preferred to achieve this purpose. Taking into account that such a kind of study is still scarce, we aimed to evaluate the association between periodontal microbiota and chronic periodontitis. A total of 60 low-income age-matched female adults, 30 with chronic periodontitis and 30 without periodontal disease, were enrolled. DNA obtained from subgingival specimens was used for quantification of Aggregatibacter actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia by real-time PCR. A. actinomycetemcomitans, E. corrodens, and F. nucleatum were detected in all subjects, P. gingivalis was observed in 70.0% and 46.6% and P. intermedia in 90.0% and 80.0% of chronic periodontitis patients and periodontally healthy subjects, respectively. P. gingivalis mean count was significantly higher in patients with chronic periodontitis than in periodontally healthy individuals. Accurate detection and quantification of five putative periodontal pathogens was feasible using a simple and fast real-time PCR protocol. Although P. gingivalis and P. intermedia have been found more commonly in chronic periodontitis patients, no statistical difference was observed between periodontally diseased and healthy groups. Quantitative data indicated association between P. gingivalis and chronic periodontitis. However, because of its uneven distribution, it should not be solely taken as a marker of periodontal status.     

Trace elements (copper,zinc, selenium and molybdenum) as markers in oral sub mucous fibrosis and oral squamous cell carcinoma

Oral cancer is a major cause of cancer morbidity and mortality worldwide and is prevalent in most areas where tobacco related practices are observed. Essential elements play a role in many biochemical reactions as a micro-source and there is growing evidence that their concentrations are altered on the onset and progress of malignant disease. In this study the levels of copper (Cu), zinc (Zn), selenium (Se) and molybdenum (Mo) in serum of patients with oral sub mucous fibrosis (OSMF) (n = 30) and oral squamous cell carcinoma (OSCC) (n = 30); were determined and the alterations of these critical parameters were analyzed in comparison with controls (n = 30) to identify predictors amongst these parameters for disease occurrence and progression. The serum Cu and Zn were established using Flame Atomic Absorption Spectrometry. Serum estimation of Se and Mo was done by graphite furnace atomic absorption spectrometry (GFAAS). Data analysis revealed a marked, progressive and significant increase in Cu levels in precancer (OSMF) and cancer (OSCC) groups as compared to the normal group. The level of Zn in serum was slightly elevated in OSMF and OSCC though not statistically significant. Cu/Zn ratio was slightly but not significantly elevated. Serum levels of Se and Mo were significantly decreased in the precancer and cancer groups as compared to the normals.     

Regulation of olfactomedin 4 by Porphyromonas gingivalis in a community context

At mucosal barriers, the virulence of microbial communities reflects the outcome of both dysbiotic and eubiotic interactions with the host, with commensal species mitigating or potentiating the action of pathogens. We examined epithelial responses to the oral pathogen Porphyromonas gingivalis as a monoinfection and in association with a community partner, Streptococcus gordonii. RNA-Seq of oral epithelial cells showed that the Notch signaling pathway, including the downstream effector olfactomedin 4 (OLFM4), was differentially regulated by P. gingivalis alone; however, regulation was overridden by S. gordonii. OLFM4 was required for epithelial cell migratory, proliferative and inflammatory responses to P. gingivalis. Activation of Notch signaling was induced through increased expression of the Notch1 receptor and the Jagged1 (Jag1) agonist. In addition, Jag1 was released in response to P. gingivalis, leading to paracrine activation. Following Jag1-Notch1 engagement, the Notch1 extracellular domain was cleaved by P. gingivalis gingipain proteases. Antagonism by S. gordonii involved inhibition of gingipain activity by secreted hydrogen peroxide. The results establish a novel mechanism by which P. gingivalis modulates epithelial cell function which is dependent on community context. These interrelationships have relevance for innate inflammatory responses and epithelial cell fate decisions in oral health and disease.Subject terms: Microbial ecology, Microbial ecology