title: Role for gingipains in Porphyromonas gingivalis traffic to phagolysosomes and survival in human aortic endothelial cells.
abstract: Gingipains are cysteine proteinases that are responsible for the virulence of Porphyromonas gingivalis. Recent studies have shown that P. gingivalis is trapped within autophagic compartments of infected cells, where it promotes survival. In this study we investigated the role of gingipains in the intracellular trafficking and survival of this bacterium in human aortic endothelial cells and any possible involvement of these enzymes in the autophagic pathway. Although autophagic events were enhanced by infection with either wild-type (WT) P. gingivalis strains (ATCC 33277, 381, and W83) or an ATCC 33277 mutant lacking gingipains (KDP136), we have found that more than 90% of intracellular WT and KDP136 colocalized with cathepsin B, a lysosome marker, and only a few of the internalized cells colocalized with LC3, an autophagosome marker, during the 0.5- to 4-h postinfection period. This was further substantiated by immunogold electron microscopic analyses, thus implying that P. gingivalis evades the autophagic pathway and instead directly traffics to the endocytic pathway to lysosomes. At the late stages after infection, WT strains in phagolysosomes retained their double-membrane structures. KDP136 in these compartments, however, lost its double-membrane structures, representing a characteristic feature of its vulnerability to rupture. Together with the ultrastructural observations, we found that the number of intracellular viable WT cells decreased more slowly than that of KDP136 cells, thus suggesting that gingipains contribute to bacterial survival, but not to trafficking, within the infected cells.
authors.affiliation: Department of Pharmacology, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yamatake
authors.forename: Maki
authors.initials: M
authors.lastname: Maeda
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kadowaki
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Takii
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tsukuba
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueno
authors.forename: Eiki
authors.initials: E
authors.lastname: Kominami
authors.forename: Sadaki
authors.initials: S
authors.lastname: Yokota
authors.forename: Kenji
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D001011:Aorta / Q000166:cytology / Q000382:microbiology*; D016866:Bacteroidaceae Infections / Q000382:microbiology; D002401:Cathepsin B / Q000378:metabolism; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004705:Endocytosis; D042783:Endothelial Cells / Q000382:microbiology*; D000080867:Gingipain Cysteine Endopeptidases; D006801:Humans; D010588:Phagosomes / Q000382:microbiology*; D016966:Porphyromonas gingivalis / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B