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Infection and Immunity, October 1999, p. 5069-5075, Vol. 67, No. 10
Kuzell Institute for Arthritis and Infectious
Diseases, California Pacific Medical Center Research Institute, San
Francisco, California 94115
Received 3 May 1999/Returned for modification 14 June 1999/Accepted 14 July 1999
Mycobacterium avium is an opportunistic pathogen in
AIDS patients, who acquire the infection mainly through the
gastrointestinal tract. Previous studies in vitro have shown that
M. avium invades epithelial cells of both intestinal and
laryngeal origin. In addition, M. avium enters the
intestinal mucosa of healthy mice. Because M. avium
invasion of the intestinal mucosa in vivo initially is not accompanied
by significant influx of inflammatory cells, we sought to determine
whether M. avium would trigger chemokine release upon entry
into epithelial cells by using HT-29 intestinal and HEp-2 laryngeal
epithelial cell lines. Chemokine synthesis was measured both by the
presence of specific mRNA and protein secretion in the cell culture
supernatant as determined by enzyme-linked immunosorbent assay.
Infection of HT-29 intestinal cells with M. avium did not
induce the release of interleukin-8 (IL-8) or RANTES for up to 7 days
postinfection. However, infection of HEp-2 cells resulted in the
release of IL-8 and RANTES at 72 h. Similar findings were observed
with other AIDS M. avium isolates belonging to different
serovars. Secretion of IL-8 by HEp-2 cells was dependent upon bacterial
uptake. In addition, prior infection with M. avium suppressed IL-8 production by HT-29 cells infected with
Salmonella typhimurium. Our results suggest that M. avium infection of epithelial cells is associated with a delay in
IL-8 and RANTES production which, in the case of HT-29, is prolonged up
to 1 week. These findings may explain the weak inflammatory response
after intestinal mucosa invasion in mice and are probably related with
the ability of the bacterium to evade the host's immune response.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Mycobacterium avium Infection of Epithelial Cells
Results in Inhibition or Delay in the Release of Interleukin-8
and RANTES
*
Corresponding author. Mailing address: Kuzell
Institute, 2200 Webster St., Ste. 305, San Francisco, CA 94115. Phone:
(415) 561-1734. Fax: (415) 441-8548. E-mail:
luizb{at}cooper.cpmc.org.
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