IMAGING IMMUNITY – from Nanoscale to Macroscale | Insights from Biophysics
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Invited Lecture | Guillaume Dumenil, Paris

Session chair: Carles Arus (Cerdanyola del Vallès, Spain)
Date: Thursday, 16 January, 2020, 4:15 PM - 5:00 PM


4:15 PM -01

Imaging the innate immune response to vascular colonization by Neisseria meningitidis (#39)

Guillaume Dumenil1

1 INSERM, Pasteur, Paris, France


The infectious niche of a bacterial pathogen determines how the innate immune response is mounted. Neisseria meningitidis, a human-specific pathogen, colonizes blood vessels, rapidly causing thrombosis and hemorrhage despite immune cell infiltration. A lack of in vivo models has impeded understanding of why the innate immune response fails to control this infection. Here, we address this using a humanized xenograft mouse model combined with histology, flow cytometry, and intravital imaging. Vascular occlusion by meningococci occurs within 2-4 hours of infection in vivo. Skin perivascular macrophages efficiently phagocytose intraluminal bacteria, secrete chemo-attractants, and recruit neutrophils to the infection. Intravascular neutrophils phagocytose bacteria but are limited to the extremities of aggregates. Extravascular neutrophils fail to enter infected vessels until late in infection. Our results show that the bacterial adhesive and aggregative properties create an intravascular niche that impairs the function of neutrophils to clear infection and results in fulminant progression



Keywords: Bacteria, intravital imaging, neutrophil, blood vessel