Cellular activation, phagocytosis, and bactericidal activity against group B streptococcus involve parallel myeloid differentiation factor 88-dependent and independent signaling pathways
Department of Medicine, Division of Infectious Diseases and Immunology
Adaptor Proteins, Signal Transducing; Animals; Antigens, CD11b; Antigens, CD14; Antigens, CD18; Antigens, Differentiation; CHO Cells; Cells, Cultured; Cricetinae; DNA-Binding Proteins; *Drosophila Proteins; Humans; Intracellular Fluid; Macrophage Activation; Macrophages, Peritoneal; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Myeloid Differentiation Factor 88; NF-kappa B; Phagocytosis; Reactive Oxygen Species; Receptors, Cell Surface; Receptors, Immunologic; Signal Transduction; Streptococcus agalactiae; Streptococcus pneumoniae; Toll-Like Receptor 2; Toll-Like Receptor 4; Toll-Like Receptor 9; Toll-Like Receptors; Tumor Necrosis Factor-alpha
Life Sciences | Medicine and Health Sciences
Group B streptococci (GBS) vigorously activate inflammatory responses. We reported previously that a secreted GBS "factor" activates phagocytes via Toll-like receptor (TLR)2 and TLR6, but that GBS cell walls activate cells independently of these receptors. We hypothesized that the phagocytic immune functions in response to GBS, such as inflammation, uptake, and elimination of bacteria, occur through a coordinated engagement of TLRs, along with the coreceptors CD14 and CD11b/CD18. Using various knockout mice we show that GBS-induced activation of p38 and NF-kappaB depends upon the expression of the cytoplasmic TLR adapter protein, myeloid differentiation factor 88 (MyD88), but not TLR2 and/or TLR4. Macrophages with deletions of CD14 and complement receptor 3 had a normal cytokine response to whole bacteria, although the response to GBS factor was abrogated in CD14-null cells. The intracellular formation of bactericidal oxygen species proved to be MyD88 dependent; however, uptake of GBS, a prerequisite for intracellular killing by O(2) radicals, occurred independently of MyD88. While deletion of complement receptor 3 greatly diminished the uptake of opsonized GBS, it did not affect the formation of bactericidal O(2) radicals or inflammatory signaling intermediates. We conclude that the inflammatory, bactericidal, and phagocytic responses to GBS occur via parallel but independent processes.
J Immunol. 2002 Oct 1;169(7):3970-7.
Journal of immunology (Baltimore, Md. : 1950)
Henneke, Philipp; Takeuchi, Osamu; Malley, Richard; Lien, Egil; Ingalls, Robin R.; Freeman, Mason W.; Mayadas, Tanya N.; Nizet, Victor; Akira, Shizuo; Kasper, Dennis L.; and Golenbock, Douglas, "Cellular activation, phagocytosis, and bactericidal activity against group B streptococcus involve parallel myeloid differentiation factor 88-dependent and independent signaling pathways" (2002). Open Access Articles. 1118.