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Infection and Immunity, October 1999, p. 5352-5360, Vol. 67, No. 10
Department of Microbiology and Immunology,
University of North Carolina, Chapel Hill, North Carolina 27599
Received 2 June 1999/Returned for modification 13 July
1999/Accepted 20 July 1999
Haemophilus ducreyi is the etiologic agent of
chancroid, a sexually transmitted genital ulcer disease. Keratinocytes
are likely the first cell type encountered by H. ducreyi
upon infection of human skin; thus, the interaction between H. ducreyi and keratinocytes is probably important for the ability
of H. ducreyi to establish infection. We have used the
HaCaT keratinocyte cell line grown in monolayers and in cocultures with
HS27 fibroblasts to investigate H. ducreyi interactions
with keratinocytes and the host-cell response to H. ducreyi
infection. Using quantitative adherence and gentamicin protection
assays, we determined that approximately 13% of H. ducreyi
adhered to HaCaT cell monolayers, while only a small proportion (0.0052%) was intracellular. By transmission electron microscopy, we
observed numerous H. ducreyi organisms adherent to but
rarely within HaCaT cells cocultured with fibroblasts. Both live
H. ducreyi and purified H. ducreyi
lipooligosaccharide (LOS) induced significant interleukin 8 (IL-8)
expression from HaCaT cell-HS27 cell cocultures. However, the level of
IL-8 expression in response to LOS alone was not as pronounced.
H. ducreyi LOS was a more potent inducer of IL-8 from
cocultures than Escherichia coli lipopolysaccharide (LPS)
at the same concentration, suggesting a unique effect of H. ducreyi LOS on cocultures. Neither live H. ducreyi
nor purified H. ducreyi LOS or E. coli LPS
induced tumor necrosis factor alpha expression from cocultures.
H. ducreyi induced drastically different cytokine profiles
from cocultures than from HS27 or HaCaT cells cultured separately. IL-8
expression by skin cells in response to H. ducreyi
infection in vivo may be responsible for the massive influx of
polymorphonuclear leukocytes and other inflammatory cells to the site
of infection. This influx of inflammatory cells may be partly
responsible for the tissue destruction characteristic of chancroid.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Examination of Early Interactions between
Haemophilus ducreyi and Host Cells by Using Cocultured HaCaT
Keratinocytes and Foreskin Fibroblasts
*
Corresponding author. Mailing address: Department of
Microbiology and Immunology, CB 7290, University of North Carolina
School of Medicine, Chapel Hill, NC 27599. Phone: (919) 966-9699. Fax: (919) 962-8103. E-mail: kawula{at}med.unc.edu.
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