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Infect. Immun., Jun 1997, 2119-2126, Vol 65, No. 6
B Wang, N Ruiz, A Pentland and M Caparon
The gram-positive bacterium Streptococcus pyogenes (group A streptococcus)
is the causative agent of a wide variety of suppurative infections of
cutaneous tissues. Previous analyses have demonstrated that the M protein
of S. pyogenes is an adhesin that directs the attachment of the
streptococcus to keratinocytes in the skin. In this study, we have examined
keratinocyte function in response to S. pyogenes and found that adherent
versus nonadherent streptococci promote distinct patterns of expression of
several proinflammatory molecules and keratinocyte cell fate. When analyzed
by a quantitative reverse transcriptase PCR method, infection of cultured
HaCaT keratinocytes with adherent, but not nonadherent, streptococci
resulted in increased expression of mRNA for the cytokines
interleukin-1alpha (IL-1alpha), IL-1beta, and IL-8 but neither infection
induced expression of tumor necrosis factor alpha. In contrast, both
adherent and nonadherent S. pyogenes induced expression of IL-6 and each
promoted synthesis and release of prostaglandin E2 (PGE2). However,
considerably greater levels of IL-6 expression were stimulated by adherent
streptococci relative to nonadherent streptococci and the kinetics of PGE2
release in response to nonadherent streptococci was delayed compared to the
response to adherent streptococci. Staining with the fluorescent probe
ethidium homodimer-1 revealed that keratinocyte membranes were rapidly
damaged upon infection with adherent streptococci but were not damaged by
nonadherent streptococci. Finally, treatments which inhibited streptococcal
metabolism completely blocked the ability of adherent streptococci to
elicit responses. These data suggest that expression of an adhesin is a
strategy used by S. pyogenes to modulate keratinocyte responses during
infection of the skin and implicate additional streptococcal products in
these signaling interactions.
Copyright © 1997, American Society for Microbiology
Keratinocyte proinflammatory responses to adherent and nonadherent group A streptococci
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
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