[PDF][PDF] CRIg functions as a macrophage pattern recognition receptor to directly bind and capture blood-borne gram-positive bacteria

Z Zeng, BGJ Surewaard, CHY Wong, JA Geoghegan… - Cell host & …, 2016 - cell.com
Z Zeng, BGJ Surewaard, CHY Wong, JA Geoghegan, CN Jenne, P Kubes
Cell host & microbe, 2016cell.com
Kupffer cells (KCs), the vast pool of intravascular macrophages in the liver, help to clear
blood-borne pathogens. The mechanisms by which KCs capture circulating pathogens
remain unknown. Here we use intra-vital imaging of mice infected with Staphylococcus
aureus to directly visualize the dynamic process of bacterial capture in the liver. Circulating
S. aureus were captured by KCs in a manner dependent on the macrophage complement
receptor CRIg, but the process was independent of complement. CRIg bound …
Summary
Kupffer cells (KCs), the vast pool of intravascular macrophages in the liver, help to clear blood-borne pathogens. The mechanisms by which KCs capture circulating pathogens remain unknown. Here we use intra-vital imaging of mice infected with Staphylococcus aureus to directly visualize the dynamic process of bacterial capture in the liver. Circulating S. aureus were captured by KCs in a manner dependent on the macrophage complement receptor CRIg, but the process was independent of complement. CRIg bound Staphylococcus aureus specifically through recognition of lipoteichoic acid (LTA), but not cell-wall-anchored surface proteins or peptidoglycan. Blocking the recognition between CRIg and LTA in vivo diminished the bacterial capture in liver and led to systemic bacterial dissemination. All tested Gram-positive, but not Gram-negative, bacteria bound CRIg in a complement-independent manner. These findings reveal a pattern recognition role for CRIg in the direct capture of circulating Gram-positive bacteria from the bloodstream.
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