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Infection and Immunity, November 2001, p. 7039-7045, Vol. 69, No. 11
Department of Medical Microbiology and
Hygiene1 and Department of Internal Medicine
I,2 University of Ulm, D-89081 Ulm, Germany
Received 29 June 2001/Returned for modification 27 July
2001/Accepted 14 August 2001
The respiratory tract pathogen Chlamydia pneumoniae has
been associated with atherosclerosis. Monocytes are supposed to serve as a vehicle for systemic dissemination of intracellular C. pneumoniae from the lung to the artery vessel wall. We were
therefore interested in pathogen-induced cellular events associated
with NF-
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.11.7039-7045.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Survival of Chlamydia
pneumoniae-Infected Mono Mac 6 Cells Is Dependent on NF-
B
Binding Activity
B, a crucial transcription factor for both inflammatory
cytokines and antiapoptotic molecules. In this study we demonstrate by
electrophoretic mobility shift assay that C. pneumoniae
infection of the human monocytic cell line Mono Mac 6 induces
activation of NF-
B over 48 h, with a maximum level at 1 h
postinfection. As shown by supershift assay, the activated NF-
B
complex consists of the subunits RelA (p65) and NF-
B1 (p50).
Apoptotic host cells were not detected during the early stages of the
infection when maximal activation of NF-
B was detected. Pretreatment
of Mono Mac 6 with the antioxidant and NF-
B inhibitor PDTC
(pyrrolidine dithiocarbamate) induced activation of caspase-3 and led
to apoptotic cell death. The C. pneumoniae-induced
activation of the NF-
B complex was reduced by PDTC, which in
parallel resulted in an increased apoptosis, as quantified by annexin V
labeling and terminal deoxynucleotidyltransferase-mediated dUTP-biotin
nick end labeling reaction. In the complete absence of activated
NF-
B, when Mono Mac 6 cells were pretreated with the more potent
NF-
B inhibitors MG-132 and parthenolide a C. pneumoniae-mediated rescue of cells from induced apoptosis could not be achieved. Our results indicate that activation of NF-
B in
C. pneumoniae-infected Mono Mac 6 cells is associated with protection of Mono Mac 6 cells against apoptosis and might thereby contribute to systemic spread of the pathogen.
*
Corresponding author. Mailing address: Department of
Medical Microbiology and Hygiene, University of Ulm, Robert-Koch Str. 8, D-89081 Ulm, Germany. Phone: 0049-731-50024610 or 0049-731-50024601. Fax: 0049-731-50024619. E-mail:
christian.wahl{at}medizin.uni-ulm.de.
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