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The GroEL protein of Porphyromonas gingivalis regulates atherogenic phenomena in endothelial cells mediated by upregulating toll-like receptor 4 expression.

ABSTRACT: Porphyromonas gingivalis (P. gingivalis) is a bacterial species that causes periodontitis. GroEL from P. gingivalis may possess biological activity and may be involved in the destruction of periodontal tissues. However, it is unclear whether P. gingivalis GroEL enhances the appearance of atherogenic phenomena in endothelial cells and vessels. Here, we constructed recombinant GroEL from P. gingivalis to investigate its effects in human coronary artery endothelial cells (HCAECs) in vitro and on aortas of high-cholesterol (HC)-fed B57BL/6 and B57BL/6-Tlr4(lps-del) mice in vivo. The results showed that GroEL impaired tube-formation capacity under non-cytotoxic conditions in HCAECs. GroEL increased THP-1 cell/HCAEC adhesion by increasing the expression of intracellular adhesion molecule (ICAM)-1 and vascular adhesion molecule (VCAM)-1 in endothelial cells. Additionally, GroEL increased DiI-oxidized low density lipoprotein (oxLDL) uptake, which may be mediated by elevated lectin-like oxLDL receptor (LOX)-1 but not scavenger receptor expressed by endothelial cells (SREC) and scavenger receptor class B1 (SR-B1) expression. Furthermore, GroEL interacts with toll-like receptor 4 (TLR4) and plays a causal role in atherogenesis in HCAECs. Human antigen R (HuR), an RNA-binding protein with a high affinity for the 3' untranslated region (3'UTR) of TLR4 mRNA, contributes to the up-regulation of TLR4 induced by GroEL in HCAECs. In a GroEL animal administration study, GroEL elevated ICAM-1, VCAM-1, LOX-1 and TLR4 expression in the aortas of HC diet-fed wild C57BL/6 but not C57BL/6-Tlr4(lps-del) mice. Taken together, our findings suggest that P. gingivalis GroEL may contribute to cardiovascular disorders by affecting TLR4 expression.

SUBMITTER: Huang CY

PROVIDER: S-EPMC4846891 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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The GroEL protein of Porphyromonas gingivalis regulates atherogenic phenomena in endothelial cells mediated by upregulating toll-like receptor 4 expression.

Huang Chun-Yao CY Shih Chun-Ming CM Tsao Nai-Wen NW Lin Yi-Wen YW Shih Chun-Che CC Chiang Kuang-Hsing KH Shyue Song-Kun SK Chang Yu-Jia YJ Hsieh Chi-Kun CK Lin Feng-Yen FY

American journal of translational research 20160215 2

Porphyromonas gingivalis (P. gingivalis) is a bacterial species that causes periodontitis. GroEL from P. gingivalis may possess biological activity and may be involved in the destruction of periodontal tissues. However, it is unclear whether P. gingivalis GroEL enhances the appearance of atherogenic phenomena in endothelial cells and vessels. Here, we constructed recombinant GroEL from P. gingivalis to investigate its effects in human coronary artery endothelial cells (HCAECs) in vitro and on ao ...[more]

PMID: 27158334

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Project description:Periodontitis is a very common oral inflammatory disease that results in the destruction of supporting connective and osseous tissues of the teeth. Although the exact etiology is still unclear, Gram-negative bacteria, especially Porphyromonas gingivalis in subgingival pockets are thought to be one of the major etiologic agents of periodontitis. Endothelin (ET) is a family of three 21-amino acid peptides, ET-1, -2, and -3, that activate G protein-coupled receptors, ETA and ETB. Endothelin is involved in the occurrence and progression of various inflammatory diseases. Previous reports have shown that ET-1 and its receptors, ETA and ETB are expressed in the periodontal tissues and, that ET-1 levels in gingival crevicular fluid are increased in periodontitis patients. Moreover, P. gingivalis infection has been shown to induce the production of ET-1 along with other inflammatory cytokines. Despite these studies, however, the functional significance of endothelin in periodontitis is still largely unknown. In this study, we explored the cellular and molecular mechanisms of ET-1 action in periodontitis using human gingival epithelial cells (HGECs). ET-1 and ETA, but not ETB, were abundantly expressed in HGECs. Stimulation of HGECs with P. gingivalis or P. gingivalis lipopolysaccharide increased the expression of ET-1 and ETA suggesting the activation of the endothelin signaling pathway. Production of inflammatory cytokines, IL-1β, TNFα, and IL-6, was significantly enhanced by exogenous ET-1 treatment, and this effect depended on the mitogen-activated protein kinases via intracellular Ca2+ increase, which resulted from the activation of the phospholipase C/inositol 1,4,5-trisphosphate pathway. The inhibition of the endothelin receptor-mediated signaling pathway with the dual receptor inhibitor, bosentan, partially ameliorated alveolar bone loss and immune cell infiltration. These results suggest that endothelin plays an important role in P. gingivalis-mediated periodontitis. Thus, endothelin antagonism may be a potential therapeutic approach for periodontitis treatment.

Project description:Porphyromonas gingivalis (Pg) is a keystone pathogen in periodontitis, a highly prevalent disease manifested by chronic inflammation of the periodontium, alveolar bone resorption and tooth loss. During periodontitis pathobionts such as Pg can enter the bloodstream and growing evidence correlates periodontitis with increased risk of cardiovascular and neurodegenerative diseases. However, the mechanism by which immune cells respond to Pg challenge in vivo remains elusive. Pg produce aggressive proteolytic virulence factors termed gingipains which not only provide nutrients necessary for bacterial growth, but also subvert the host immune response, facilitating bacterial survival. Using transgenic zebrafish with fluorescently labelled macrophages and neutrophils, the role of gingipains in bacterial survival and interaction with phagocytes during systemic and local infection was examined. In contrast to the wild-type (W83) Pg, isogenic gingipain-null (ΔK/R-ab) or wild-type Pg treated with gingipain inhibitors caused less zebrafish mortality, bacteria were rapidly phagocytosed, acidified in phagosomes and eradicated when systemically injected, showing that gingipains are instrumental in preventing phagocytosis and intracellular killing of Pg by innate immune cells. Moreover, Pg were predominantly phagocytosed by macrophages, and gingipain depletion/inactivation increased bacterial phagocytosis when bacteria were injected either systemically or locally in the otic vesicle, with less bacteria internalised by neutrophils. This phenomenon was Pg-specific as Fusobacterium nucleatum caused neutrophil recruitment that then effectively phagocytosed these bacteria. These data demonstrate the important role of phagocytes, especially macrophages, in combating Pg infection and highlight the crucial protective role of gingipains in subverting the innate immune response. This study also emphasizes the advantages of using zebrafish to study interactions of Pg with phagocytes in vivo in real-time, providing a valuable experimental system for testing new therapeutic strategies aimed at reducing periodontal-associated systemic or neurodegenerative disease.

Dataset Information

The GroEL protein of Porphyromonas gingivalis regulates atherogenic phenomena in endothelial cells mediated by upregulating toll-like receptor 4 expression.

Publications

The GroEL protein of Porphyromonas gingivalis regulates atherogenic phenomena in endothelial cells mediated by upregulating toll-like receptor 4 expression.

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