Toll-like receptor 2 contributes to antibacterial defence against pneumolysin-deficient pneumococci.

Abstract

Toll-like receptors (TLRs) are pattern recognition receptors that recognize conserved molecular patterns expressed by pathogens. Pneumolysin, an intracellular toxin found in all Streptococcus pneumoniae clinical isolates, is an important virulence factor of the pneumococcus that is recognized by TLR4. Although TLR2 is considered the most important receptor for Gram-positive bacteria, our laboratory previously could not demonstrate a decisive role for TLR2 in host defence against pneumonia caused by a serotype 3 S. pneumoniae. Here we tested the hypothesis that in the absence of TLR2, S. pneumoniae can still be sensed by the immune system through an interaction between pneumolysin and TLR4. C57BL/6 wild-type (WT) and TLR2 knockout (KO) mice were intranasally infected with either WT S. pneumoniae D39 (serotype 2) or the isogenic pneumolysin-deficient S. pneumoniae strain D39 PLN. TLR2 did not contribute to antibacterial defence against WT S. pneumoniae D39. In contrast, pneumolysin-deficient S. pneumoniae only grew in lungs of TLR2 KO mice. TLR2 KO mice displayed a strongly reduced early inflammatory response in their lungs during pneumonia caused by both pneumolysin-producing and pneumolysin-deficient pneumococci. These data suggest that pneumolysin-induced TLR4 signalling can compensate for TLR2 deficiency during respiratory tract infection with S. pneumoniae.

• Authors: Mark C Dessing, Sandrine Florquin, James C Paton, Tom van der Poll
• Journal: Cellular microbiology (Cell Microbiol) Vol. 10 Issue 1 Pg. 237-46 (Jan 2008) ISSN: 1462-5822 [Electronic] India
• PMID: 17711480 (Publication Type: Journal Article)

Chemical References

• Bacterial Proteins
• Streptolysins
• Toll-Like Receptor 2
• plY protein, Streptococcus pneumoniae

Topics

• Animals
• Bacterial Proteins (genetics, immunology)
• Colony Count, Microbial
• Lung (microbiology, pathology)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Pneumonia, Pneumococcal (immunology)
• Streptococcus pneumoniae (genetics, immunology)
• Streptolysins (genetics, immunology)
• Survival Analysis
• Toll-Like Receptor 2 (deficiency, immunology)