Dataset Information

The capsule of Porphyromonas gingivalis reduces the immune response of human gingival fibroblasts.

ABSTRACT:

Background

Periodontitis is a bacterial infection of the periodontal tissues. The Gram-negative anaerobic bacterium Porphyromonas gingivalis is considered a major causative agent. One of the virulence factors of P. gingivalis is capsular polysaccharide (CPS). Non-encapsulated strains have been shown to be less virulent in mouse models than encapsulated strains.

Results

To examine the role of the CPS in host-pathogen interactions we constructed an insertional isogenic P. gingivalis knockout in the epimerase-coding gene epsC that is located at the end of the CPS biosynthesis locus. This mutant was subsequently shown to be non-encapsulated. K1 capsule biosynthesis could be restored by in trans expression of an intact epsC gene. We used the epsC mutant, the W83 wild type strain and the complemented mutant to challenge human gingival fibroblasts to examine the immune response by quantification of IL-1beta, IL-6 and IL-8 transcription levels. For each of the cytokines significantly higher expression levels were found when fibroblasts were challenged with the epsC mutant compared to those challenged with the W83 wild type, ranging from two times higher for IL-1beta to five times higher for IL-8.

Conclusions

These experiments provide the first evidence that P. gingivalis CPS acts as an interface between the pathogen and the host that may reduce the host's pro-inflammatory immune response. The higher virulence of encapsulated strains may be caused by this phenomenon which enables the bacteria to evade the immune system.

SUBMITTER: Brunner J

PROVIDER: S-EPMC2817674 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

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Publications

The capsule of Porphyromonas gingivalis reduces the immune response of human gingival fibroblasts.

Brunner Jorg J Scheres Nina N El Idrissi Nawal B NB Deng Dong M DM Laine Marja L ML van Winkelhoff Arie J AJ Crielaard Wim W

BMC microbiology 20100111

<h4>Background</h4>Periodontitis is a bacterial infection of the periodontal tissues. The Gram-negative anaerobic bacterium Porphyromonas gingivalis is considered a major causative agent. One of the virulence factors of P. gingivalis is capsular polysaccharide (CPS). Non-encapsulated strains have been shown to be less virulent in mouse models than encapsulated strains.<h4>Results</h4>To examine the role of the CPS in host-pathogen interactions we constructed an insertional isogenic P. gingivalis ...[more]

PMID: 20064245

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Project description:BackgroundPorphyromonas gingivalis is a major pathogen of periodontal disease that affects a majority of adults worldwide. Increasing evidence shows that periodontal disease is linked to various systemic diseases like diabetes and cardiovascular disease, by contributing to increased systemic levels of inflammation. Lipopolysaccharides (LPS), as a key virulent attribute of P. gingivalis, possesses significant amount of lipid A heterogeneity containing tetra- (LPS1435/1449) and penta-acylated (LPS1690) structures. Hitherto, the exact molecular mechanism of P. gingivalis LPS involved in periodontal pathogenesis remains unclear, due to limited understanding of the specific receptors and signaling pathways involved in LPS-host cell interactions.Methodology/principal findingsThis study systematically investigated the effects of P. gingivalis LPS1435/1449 and LPS1690 on the expression of TLR2 and TLR4 signal transduction and the activation of pro-inflammatory cytokines IL-6 and IL-8 in human gingival fibroblasts (HGFs). We found that LPS1435/1449 and LPS1690 differentially modulated TLR2 and TLR4 expression. NF-?B pathway was significantly activated by LPS1690 but not by LPS1435/1449. In addition, LPS1690 induced significant expression of NF-?B and p38 MPAK pathways-related genes, such as NFKBIA, NFKB1, IKBKB, MAP2K4 and MAPK8. Notably, the pro-inflammatory genes including GM-CSF, CXCL10, G-CSF, IL-6, IL-8 and CCL2 were significantly upregulated by LPS1690 while down-regulated by LPS1435/1449. Blocking assays confirmed that TLR4-mediated NF-?B signaling was vital in LPS1690-induced expression of IL-6 and IL-8 in HGFs.Conclusions/significanceThe present study suggests that the tetra- and penta-acylated lipid A structures of P. gingivalis LPS differentially activate TLR4-mediated NF-?B signaling pathway, and significantly modulate the expression of IL-6 and IL-8 in HGFs. The ability to alter the lipid A structure of LPS could be one of the strategies carried-out by P. gingivalis to evade innate host defense in gingival tissues, thereby contributing to periodontal pathogenesis.

Project description:ObjectiveEphrinA2-EphA2 and ephrinB2-EphB4 critically engage in bidirectional signalling to modulate alveolar bone remodelling. The present study aimed to investigate the effects of lipopolysaccharides (LPS) derived from Porphyromonas gingivalis on ephrin/Eph signalling in periodontal ligament fibroblasts (PDLFs).Material and methodsThe primary cultured PDLFs were incubated in the absence (as a control) or presence of P. gingivalisLPS at 0.001-10 μg/mL for 24 hours. The PDLFs were then stimulated with P. gingivalisLPS at the optimal concentration (0.1 μg/mL) for different periods (6-48 hours). The expression of ephrinA2, ephrinB2, EphA2 and EphB4 was assessed by quantitative reverse-transcription real-time polymerase chain reaction and western blotting. The osteoblastic markers alkaline phosphatase, osteocalcin and Runt-related transcription factor 2 (Runx2), and the osteoclastogenesis-related factors receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin were also evaluated.ResultsThe ephrinA2 and EphA2 expression was upregulated and EphB4 expression was downregulated by stimulation of P. gingivalisLPS. EphrinA2 mRNA expression in the PDLFs was significantly upregulated from 12 to 48 hours (P<.05), whereas EphA2 exhibited no change for the first 24 hours, after which there was a significant increase at 48 hours (P<.05). EphB4 exhibited lower mRNA expression at 12 and 24 hours than did the control (P<.05), but the change was insignificant at 48 hours. In contrast, the expression of ephrinB2 remained unchanged. The expressions of ephrinA2, EphA2, ephrinB2 and EphB4 at the protein level showed a similar pattern to that at the mRNA level. The expression of Runx2 and osteocalcin significantly decreased, whereas that of RANKL/osteoprotegerin increased.ConclusionThe present study suggest that P. gingivalisLPS would contribute to a dysregulation of bone remodelling, whereby ephrinA2/EphA2 expression is stimulated and EphB4 expression is inhibited.

Dataset Information

The capsule of Porphyromonas gingivalis reduces the immune response of human gingival fibroblasts.

Background

Results

Conclusions

Publications

The capsule of Porphyromonas gingivalis reduces the immune response of human gingival fibroblasts.

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