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Query: UMLS:C0031099 (periodontitis)
 12,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Porphyromonas gingivalis is one of the causative agents of adult periodontitis, and has been reported to be internalized by nonphagocytic epithelial cells. However, the mechanism for the internalization remains unclear. In the present study, we addressed this issue using fluorescent beads coated with bacterial membrane vesicles (MVs) that retain surface components of P. gingivalis. We established an assay system in which we could easily quantify the bead internalization to cells. MVs-coated beads were internalized by HeLa cells in kinetics similar to that of living bacteria. The internalization depended on dynamin but not clathrin. The beads were internalized through the actin-mediated pathway that is controlled by phosphatidylinositol (PI) 3-kinase. The dynamics of microtubule assembly and disassembly was also required. Further, the treatment of cells with cholesterol-binding reagents significantly inhibited bead internalization, and the internalized beads were apparently colocalized with ganglioside GM1 and caveolin-1, which suggest the involvement of the lipid raft in the process. These results suggest that P. gingivalis accomplishes its internalization utilizing membrane lipid raft and cytoskeletal functions of the target cells.
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PMID:Molecular dissection of internalization of Porphyromonas gingivalis by cells using fluorescent beads coated with bacterial membrane vesicle. 1642 61

Porphyromonas gingivalis is a predominant periodontal pathogen that expresses a number of potential virulence factors involved in the pathogenesis of periodontitis. Gingival epithelial cells are spontaneously exposed to bacterial attacks and function to prevent invasion by bacteria into deeper tissues. P. gingivalis fimbriae are a critical factor for mediation of interaction of the organism with host tissues, as they promote both bacterial adhesion to and invasion of targeted sites. Fimbriae are capable of binding to human salivary components, extracellular matrix proteins, and commensal bacteria, while they also strongly adhere to cellular alpha5beta1-integrin. Following adhesion to alpha5beta1-integrin, P. gingivalis is captured by cellular pseudopodia, which enables invagination through an actin-mediated pathway. The invasive event has been reported to require host cellular dynamin, actin fibers, microtubules, and lipid rafts. Following passage through the epithelial barrier, the intracellular pathogen impairs cellular function. Fimbriae are classified into 6 genotypes (types I to V and Ib) based on the diversity of the fimA genes encoding each fimbria subunit, and intracellular P. gingivalis with type II fimbriae has been found to clearly degrade integrin-related signaling molecules, paxillin, and focal adhesion kinase, which disables cellular migration and proliferation. These events are considered to integrate the bacterial strategy for persistence in periodontal tissues.
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PMID:Disruption of epithelial barrier and impairment of cellular function by Porphyromonas gingivalis. 1748 50

Porphyromonas gingivalis, a periodontal pathogen, secretes outer membrane vesicles (MVs) that contain major virulence factors, including major fimbriae and proteases termed gingipains, although it is not confirmed whether MVs enter host cells. In this study, we analyzed the mechanisms involved in the interactions of P. gingivalis MVs with human epithelial cells. Our results showed that MVs swiftly adhered to HeLa and immortalized human gingival epithelial cells in a fimbria-dependent manner and then entered via a lipid raft-dependent endocytic pathway. The intracellular MVs were subsequently routed to early endosome antigen 1-associated compartments and then were sorted to lysosomal compartments within 90 min, suggesting that intracellular MVs were ultimately degraded by the cellular digestive machinery. However, P. gingivalis MVs remained there for over 24 h and significantly induced acidified compartment formation after being taken up by the cellular digestive machinery. In addition, MV entry was shown to be mediated by a novel pathway for transmission of bacterial products into host cells, a Rac1-regulated pinocytic pathway that is independent of caveolin, dynamin, and clathrin. Our findings indicate that P. gingivalis MVs efficiently enter host cells via an endocytic pathway and survive within the endocyte organelles for an extended period, which provides better understanding of the role of MVs in the etiology of periodontitis.
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PMID:Porphyromonas gingivalis outer membrane vesicles enter human epithelial cells via an endocytic pathway and are sorted to lysosomal compartments. 1965 65

Porphyromonas gingivalis is a keystone pathogen of periodontitis. One of its bacterial characteristics is the ability to invade various host cells, including nonphagocytic epithelial cells and fibroblasts, which is known to facilitate P. gingivalis adaptation and survival in the gingival environment. In this study, we investigated two small compounds, Alop1 and dynasore, for their role in inhibition of P. gingivalis invasion. Using confocal microscopy, we showed that these two compounds significantly reduced invasion of P. gingivalis and its outer membrane vesicles into human oral keratinocytes in a dose-dependent manner. The inhibitory effects of dynasore, a dynamin inhibitor, on the bacterial entry is consistent with the notion that P. gingivalis invasion is mediated by a clathrin-mediated endocytic machinery. We also observed that microtubule arrangement, but not actin, was altered in the host cells treated with Alop1 or dynasore, suggesting an involvement of microtubule in this inhibitory activity. This work provides an opportunity to develop compounds against P. gingivalis infection.
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PMID:Two Small Molecules Block Oral Epithelial Cell Invasion by Porphyromons gingivalis. 2689 34