Distinct microenvironmental cues trigger divergent TLR4-mediated immune signalling in macrophages
Piccinini, Anna M. and Zuliani-Alvarez, Lorena and Lim, Jenny M.P. and Midwood, Kim S. (2016) Distinct microenvironmental cues trigger divergent TLR4-mediated immune signalling in macrophages. Science Signaling, 9 (442). ISSN 1937-9145
Official URL: http://stke.sciencemag.org/content/9/443/ra86
Macrophages exhibit a phenotypic plasticity that enables them to orchestrate specific immune responses to distinct threats. However, the factors that control macrophage behaviour in a context dependent manner are not well understood. Lipopolysaccharide (LPS) and the extracellular matrix glycoprotein tenascin-C both activate toll-like receptor 4 (TLR4), and are released during bacterial infection and tissue injury, respectively. Here we report that these two TLR4 ligands induce distinct macrophage signalling pathways and phenotypes. Macrophages activated by LPS or tenascin-C display some common features, including NF-kB and MAP kinase signalling, and cytokine synthesis. However, different subsets of cytokines, and different phosphoproteomic signatures, are produced by each stimulus. Moreover, tenascin-C promotes macrophages more inclined to matrix synthesis and phosphorylation, whilst LPS-activated macrophages exhibit an elevated capacity to degrade matrix. These data reveal how activation of one pattern recognition receptor by different microenvironmental cues, signalling pathogen invasion or tissue damage, can create unique macrophage phenotypes.
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