title: Infection of endothelial cells with virulent Rickettsia prowazekii increases the transmigration of leukocytes.
abstract: Rickettsia prowazekii, the etiologic agent of epidemic typhus, infects vascular endothelium, leading to vasculitis and tissue infiltration of leukocytes. Murine and human endothelial cells (ECs) were infected with R. prowazekii, including the virulent Breinl strain and the attenuated Madrid E strain. The transendothelial migration (TM) of murine and human peripheral blood mononuclear cells (PBMCs) across ECs infected with Breinl organisms was significantly increased compared with that for uninfected ECs or for ECs infected with attenuated organisms, demonstrating that increased TM was related to R. prowazekii virulence. Increased TM was associated with a specific inflammatory pattern. Indeed, only Breinl organisms induced the expression of transcripts for inflammatory cytokines and chemokines by ECs. Murine PBMCs that had transmigrated across ECs infected with Breinl organisms overexpressed inflammatory cytokines and chemokines as well as tissue factor, whereas interleukin-10 expression was down-regulated. The impact of R. prowazekii infection on the TM of PBMCs may play a prominent role in the development of lesions in epidemic typhus.
authors.affiliation: Unité des Rickettsies, Centre National de la Recherche Scientifique, Unité Mixte de Recherche, Université de la Méditerranée, Institut Fédératif de Recherche, Faculté de Médecine, Marseille, France.
authors.forename: Yassina
authors.initials: Y
authors.lastname: Bechah
authors.forename: Christian
authors.initials: C
authors.lastname: Capo
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mege
mesh_terms: D000818:Animals; D054441:Cell Migration Assays, Leukocyte; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D042783:Endothelial Cells / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D007962:Leukocytes / Q000382:microbiology / Q000502:physiology; D051379:Mice; D012283:Rickettsia prowazekii / Q000472:pathogenicity*; D014438:Typhus, Epidemic Louse-Borne / Q000276:immunology*; D014774:Virulence / Q000276:immunology