title: Host cell responses to Chlamydia pneumoniae in gamma interferon-induced persistence overlap those of productive infection and are linked to genes involved in apoptosis, cell cycle, and metabolism.
abstract: The respiratory pathogen Chlamydia (Chlamydophila) pneumoniae is associated with chronic diseases, including atherosclerosis and giant-cell arteritis, which are accompanied by the occurrence of these obligate intracellular bacteria in blood vessels. There, C. pneumoniae seems to be present in a persistent state. Persistence is characterized by modified bacterial metabolism and morphology, as well as a reversible arrest of chlamydial development. In cell culture, this persistent state can be induced by gamma interferon (IFN-gamma). To elucidate this long-term interaction between chlamydiae and their host cells, microarray screening on epithelial HeLa cells was performed. Transcription of persistently (and productively) infected cells was compared with that of mock-infected cells. Sixty-six host cell genes were regulated at 24 h and/or 96 h of IFN-gamma-induced persistence. Subsequently, a set of 17 human host cell genes related to apoptosis, cell cycle, or metabolism was identified as permanently up- or down-regulated by real-time PCR. Some of these chlamydia-dependent host cell responses were diminished or even absent in the presence of rifampin. However, other expression patterns were not altered by the inhibition of bacterial RNA polymerase, suggesting two different modes of host cell activation. Thus, in the IFN-gamma model, the persisting bacteria cause long-lasting changes in the expression of genes coding for functionally important proteins. They might be potential drug targets for the treatment of persistent C. pneumoniae infections.
authors.affiliation: Department of Medical Microbiology, Medical School Hannover, 30625 Hannover, Germany.
authors.forename: Meike
authors.initials: M
authors.lastname: Eickhoff
authors.forename: Jessica
authors.initials: J
authors.lastname: Thalmann
authors.forename: Simone
authors.initials: S
authors.lastname: Hess
authors.forename: Myriam
authors.initials: M
authors.lastname: Martin
authors.forename: Thomas
authors.initials: T
authors.lastname: Laue
authors.forename: Joachim
authors.initials: J
authors.lastname: Kruppa
authors.forename: Gudrun
authors.initials: G
authors.lastname: Brandes
authors.forename: Andreas
authors.initials: A
authors.lastname: Klos
mesh_terms: D017209:Apoptosis / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000235:genetics*; D002690:Chlamydia Infections / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D016993:Chlamydophila pneumoniae / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins; D007371:Interferon-gamma