Affiliation:
1. Departments of Microbiology
2. Surgery
3. Medicine, University of Mississippi Medical Center, Jackson, Mississippi 39216
Abstract
ABSTRACT
Pneumolysin (PLY) is a major virulence factor of
Streptococcus pneumoniae
that elicits a variety of proinflammatory responses from cells of the host immune system. Intercellular adhesion molecule 1 (ICAM-1) is a cell adhesion molecule involved in leukocyte trafficking toward inflammatory stimuli in extravascular sites. In this study, we evaluated the effect of PLY on expression of ICAM-1 in THP-1 monocytic cells exposed to
S. pneumoniae
. Exposure of cells to PLY-expressing
S. pneumoniae
strain WU2 for 6 h led to significantly higher levels of ICAM-1 message than those in cells exposed to either medium alone or ΔPLY1, a PLY-negative isogenic mutant of WU2. Cells exposed to purified recombinant PLY also showed a dose-dependent increase in ICAM-1 mRNA compared to cells exposed to medium alone. Exposure to recombinant PLY containing a single amino acid substitution (Trp433→Phe) that decreases cytolytic activity did not increase ICAM-1 mRNA to levels seen with wild-type PLY. In addition, THP-1 cells exposed to wild-type strain WU2 or D39 had increased ICAM-1 on their surface compared to cells exposed to medium alone or their PLY-negative isogenic mutants ΔPLY1 and ΔPLY2, respectively. These data indicate that PLY induces transcription and production of a cell adhesion molecule involved in the inflammatory response that may play a role in pneumococcal infection.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
44 articles.
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