Dataset Information

Oral Pathogen Porphyromonas gingivalis Can Escape Phagocytosis of Mammalian Macrophages.

ABSTRACT: Macrophages are phagocytic cells that play a key role in host immune response and clearance of microbial pathogens. Porphyromonas gingivalis is an oral pathogen associated with the development of periodontitis. Escape from macrophage phagocytosis was tested by infecting THP-1-derived human macrophages and RAW 264.7 mouse macrophages with strains of P. gingivalis W83 and 33277 as well as Streptococcus gordonii DL1 and Escherichia coli OP50 at MOI = 100. CFU counts for all intracellular bacteria were determined. Then, infected macrophages were cultured in media without antibiotics to allow for escape and escaping bacteria were quantified by CFU counting. P. gingivalis W83 displayed over 60% of the bacterial escape from the total amount of intracellular CFUs, significantly higher compared to all other bacteria strains. In addition, bacterial escape and re-entry were also tested and P. gingivalis W83, once again, showed the highest numbers of CFUs able to exit and re-enter macrophages. Lastly, the function of the PG0717 gene of P. gingivalis W83 was tested on escape but found not related to this activity. Altogether, our results suggest that P. gingivalis W83 is able to significantly avoid macrophage phagocytosis. We propose this ability is likely linked to the chronic nature of periodontitis.

SUBMITTER: Werheim ER

PROVIDER: S-EPMC7563140 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Oral Pathogen Porphyromonas gingivalis Can Escape Phagocytosis of Mammalian Macrophages.

Werheim Erik R ER Senior Kevin G KG Shaffer Carly A CA Cuadra Giancarlo A GA

Microorganisms 20200918 9

Macrophages are phagocytic cells that play a key role in host immune response and clearance of microbial pathogens. Porphyromonas gingivalis is an oral pathogen associated with the development of periodontitis. Escape from macrophage phagocytosis was tested by infecting THP-1-derived human macrophages and RAW 264.7 mouse macrophages with strains of P. gingivalis W83 and 33277 as well as Streptococcus gordonii DL1 and Escherichia coli OP50 at MOI = 100. CFU counts for ...[more]

PMID: 32961960

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Project description:Porphyromonas gingivalis is a Gram-negative anaerobe that resides exclusively in the human oral cavity. Long-term colonization by P. gingivalis requires the bacteria to evade host immune responses while adapting to the changing host physiology and alterations in the composition of the oral microflora. The genetic diversity of P. gingivalis appears to reflect the variability of its habitat; however, little is known about the molecular mechanisms generating this diversity. Previously, our research group established that chromosomal DNA transfer occurs between P. gingivalis strains. In this study, we examine the role of putative DNA transfer genes in conjugation and transformation and demonstrate that natural competence mediated by comF is the dominant form of chromosomal DNA transfer, with transfer by a conjugation-like mechanism playing a minor role. Our results reveal that natural competence mechanisms are present in multiple strains of P. gingivalis, and DNA uptake is not sensitive to DNA source or modification status. Furthermore, extracellular DNA was observed for the first time in P. gingivalis biofilms and is predicted to be the major DNA source for horizontal transfer and allelic exchange between strains. We propose that exchange of DNA in plaque biofilms by a transformation-like process is of major ecological importance in the survival and persistence of P. gingivalis in the challenging oral environment. P. gingivalis colonizes the oral cavities of humans worldwide. The long-term persistence of these bacteria can lead to the development of chronic periodontitis and host morbidity associated with tooth loss. P. gingivalis is a genetically diverse species, and this variability is believed to contribute to its successful colonization and survival in diverse human hosts, as well as evasion of host immune defenses and immunization strategies. We establish here that natural competence is the major driving force behind P. gingivalis DNA exchange and that conjugative DNA transfer plays a minor role. Furthermore, we reveal for the first time the presence of extracellular DNA in P. gingivalis biofilms, which is most likely the source of DNA exchanged between strains within dental plaque. These studies expand our understanding of the mechanisms used by this important member of the human oral flora to transition its relationship with the host from a commensal to a pathogenic relationship.

Project description:BACKGROUND Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy, characterized by high recurrence rate resulting in poor prognosis. Porphyromonas gingivalis, most closely correlated with chronic periodontitis, is increasingly thought to play a significant role in OSCC development via influencing tumor-associated macrophages. However, its specific function remains unclear. In this study, we attempted to explore the mechanism of action of P. gingivalis in the recurrence of OSCC by bioinformatics analysis, to lay a foundation for subsequent basic experiments. MATERIAL AND METHODS The P. gingivalis-infected macrophage microarray dataset (GSE24897) and the OSCC advanced relapse patient microarray dataset (GSE87593) were retrieved from the Gene Expression Omnibus (GEO) database. Differentially-expressed genes (DEGs) were screened using R system, and the intersected DEGs were analyzed for functional enrichment, and protein-protein interaction (PPI) networks were constructed. The expression of significant DEG in GSE24897 microarray was assessed to determine its effect on macrophage immune infiltration in pan-cancer by applying the TIMER 2.0 repository. To detect the expression of DOK3 in OSCC specimens, immunohistochemical (ICH) assay was used. RESULTS A total of 106 co-expressed DEGs were upregulated and 131 were downregulation. The biological processes were mainly enriched in DNA-templated transcription terms, the cellular component enrichment was mainly enriched in the nucleus terms, and the molecular function enrichment was mainly enriched in protein-binding function terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the DEGs were mainly enriched in the MAPK signaling pathway. Overall analysis of the PPI network showed a significant aggregation, with the top 10 hub co-expressed genes (CASP3, FYN, HNRNPA2B1, NR3C1, RELA, REL, POLR2F, RAN, RHOA, and STAT5B). DOK3 is significantly upregulated in P. gingivalis-infected macrophages, which is associated with macrophage infiltration and differentiation. There was more positive DOK3 staining in the group with P. gingivalis infection. CONCLUSIONS P. gingivalis can affect the recurrence of OSCC by increasing the expression of DOK3 in TAMs, which may be involved in activation of signaling pathways such as TNF and MAPK.

Dataset Information

Oral Pathogen Porphyromonas gingivalis Can Escape Phagocytosis of Mammalian Macrophages.

Publications

Oral Pathogen <i>Porphyromonas gingivalis</i> Can Escape Phagocytosis of Mammalian Macrophages.

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