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    Infections with avian pathogenic and fecal Escherichia coli strains display similar lung histopathology and macrophage apoptosis (2012)

    Art
    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Autoren
    Horn, Fabiana
    Corrêa, André Mendes Ribeiro
    Barbieri, Nicolle Lima
    Glodde, Susanne
    Weyrauch, Karl Dietrich
    Kaspers, Bernd
    Driemeier, David
    Ewers, Christa
    Wieler, Lothar H (WE 7)
    Quelle
    PLoS one; 7(7) — S. e41031
    ISSN: 1932-6203
    Sprache
    Englisch
    Verweise
    URL (Volltext): http://edocs.fu-berlin.de/docs/receive/FUDOCS_document_000000019621
    DOI: 10.1371/journal.pone.0041031
    Pubmed: 22848424
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    Abstract / Zusammenfassung

    The purpose of this study was to compare histopathological changes in the lungs of chickens infected with avian pathogenic (APEC) and avian fecal (A(fecal)) Escherichia coli strains, and to analyze how the interaction of the bacteria with avian macrophages relates to the outcome of the infection. Chickens were infected intratracheally with three APEC strains, MT78, IMT5155, and UEL17, and one non-pathogenic A(fecal) strain, IMT5104. The pathogenicity of the strains was assessed by isolating bacteria from lungs, kidneys, and spleens at 24 h post-infection (p.i.). Lungs were examined for histopathological changes at 12, 18, and 24 h p.i. Serial lung sections were stained with hematoxylin and eosin (HE), terminal deoxynucleotidyl dUTP nick end labeling (TUNEL) for detection of apoptotic cells, and an anti-O2 antibody for detection of MT78 and IMT5155. UEL17 and IMT5104 did not cause systemic infections and the extents of lung colonization were two orders of magnitude lower than for the septicemic strains MT78 and IMT5155, yet all four strains caused the same extent of inflammation in the lungs. The inflammation was localized; there were some congested areas next to unaffected areas. Only the inflamed regions became labeled with anti-O2 antibody. TUNEL labeling revealed the presence of apoptotic cells at 12 h p.i in the inflamed regions only, and before any necrotic foci could be seen. The TUNEL-positive cells were very likely dying heterophils, as evidenced by the purulent inflammation. Some of the dying cells observed in avian lungs in situ may also be macrophages, since all four avian E. coli induced caspase 3/7 activation in monolayers of HD11 avian macrophages. In summary, both pathogenic and non-pathogenic fecal strains of avian E. coli produce focal infections in the avian lung, and these are accompanied by inflammation and cell death in the infected areas.