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Infection and Immunity, April 2001, p. 2650-2658, Vol. 69, No. 4
Department of
Medicine1 and Department of Microbiology
and Immunology,2 Stanford University School of
Medicine, Stanford, California 94305, and Veterans Affairs Palo
Alto Health Care System, Palo Alto, California 943043
Received 24 October 2000/Returned for modification 21 November
2000/Accepted 20 December 2000
Filamentous hemagglutinin (FHA) is a dominant cell
surface-associated Bordetella pertussis adhesin.
Recognition that this protein is secreted in significant amounts and
that bacterial adhesins may have other actvities, prompted an
assessment of FHA effects on human macrophages. Incubation of human
macrophage-like U937 cells with preparations of FHA resulted in
dose-dependent cytotoxicity, with death of 95% of treated cells after
24 h. Based on the use of four independent methods, death of these
cells could be largely attributed to apoptosis. FHA-associated
apoptosis was also observed in THP-1 macrophage-like cells, fresh human
peripheral blood monocyte-derived macrophages (MDM), and BEAS-2B human
bronchial epithelial cells. Infection of MDM with wild-type B. pertussis resulted in apoptosis within 6 h, while infection
with an FHA-deficient derivative strain was only 50% as effective.
FHA-associated cytotoxicity was preceded by host cell secretion of
tumor necrosis factor alpha (TNF-
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.4.2650-2658.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Proinflammatory and Proapoptotic Activities
Associated with Bordetella pertussis Filamentous
Hemagglutinin
), a potential proapoptotic factor.
However, pretreatment of cells with a neutralizing anti-TNF-
monoclonal antibody inhibited only 16% of the FHA-associated
apoptosis. On the other hand, a blocking monoclonal antibody directed
against TNF-
receptor 1 inhibited FHA-associated apoptosis by 47.7%
(P = 0.0001), suggesting that this receptor may play a
role in the death pathway activated by FHA. Our in vitro data indicate
that secreted and cell-associated FHA elicits proinflammatory and
proapoptotic responses in human monocyte-like cells, MDM, and bronchial
epithelial cells and suggest a previously unrecognized role for this
prominent virulence factor in the B. pertussis-host interaction.
*
Corresponding author. Mailing address: VA Palo Alto
Health Care System 154T, 3801 Miranda Ave., Palo Alto, CA 94304. Phone: (650) 852-3308. Fax: (650) 852-3291. E-mail:
relman{at}cmgm.stanford.edu.
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