Local microvascular leakage promotes trafficking of activated neutrophils to remote organs
Charlotte Owen-Woods, … , Mathieu-Benoit Voisin, Sussan Nourshargh
Charlotte Owen-Woods, … , Mathieu-Benoit Voisin, Sussan Nourshargh
Published January 23, 2020
Citation Information: J Clin Invest. 2020;130(5):2301-2318. https://doi.org/10.1172/JCI133661.
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Research Article Inflammation Vascular biology

Local microvascular leakage promotes trafficking of activated neutrophils to remote organs

Abstract

Increased microvascular permeability to plasma proteins and neutrophil emigration are hallmarks of innate immunity and key features of numerous inflammatory disorders. Although neutrophils can promote microvascular leakage, the impact of vascular permeability on neutrophil trafficking is unknown. Here, through the application of confocal intravital microscopy, we report that vascular permeability–enhancing stimuli caused a significant frequency of neutrophil reverse transendothelial cell migration (rTEM). Furthermore, mice with a selective defect in microvascular permeability enhancement (VEC-Y685F-ki) showed reduced incidence of neutrophil rTEM. Mechanistically, elevated vascular leakage promoted movement of interstitial chemokines into the bloodstream, a response that supported abluminal-to-luminal neutrophil TEM. Through development of an in vivo cell labeling method we provide direct evidence for the systemic dissemination of rTEM neutrophils, and showed them to exhibit an activated phenotype and be capable of trafficking to the lungs where their presence was aligned with regions of vascular injury. Collectively, we demonstrate that increased microvascular leakage reverses the localization of directional cues across venular walls, thus causing neutrophils engaged in diapedesis to reenter the systemic circulation. This cascade of events offers a mechanism to explain how local tissue inflammation and vascular permeability can induce downstream pathological effects in remote organs, most notably in the lungs.

Authors

Charlotte Owen-Woods, Régis Joulia, Anna Barkaway, Loïc Rolas, Bin Ma, Astrid Fee Nottebaum, Kenton P. Arkill, Monja Stein, Tamara Girbl, Matthew Golding, David O. Bates, Dietmar Vestweber, Mathieu-Benoit Voisin, Sussan Nourshargh

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Figure 3

Chimeric VEC-Y658F mice exhibit reduced microvascular leakage induction and neutrophil reverse TEM.

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Chimeric VEC-Y658F mice exhibit reduced microvascular leakage induction ...
(A) Generation of chimeric mice exhibiting LysM-EGFP-ki hematopoietic cells within VEC-WT or VEC-Y658F recipients. (B) Representative confocal IVM images of postcapillary venular segments (stained with anti-CD31; red) subjected to IL-1β plus histamine stimulation at 2 time points after application of histamine in chimeric VEC-WT and VEC-Y658F mice, illustrating dextran leakage (blue pseudocolor intensity). Scale bars: 10 μm. (C) Time course of dextran accumulation in the perivascular region of selected IL-1β–stimulated postcapillary venules in VEC-WT and VEC-Y658F chimeric mice after topical application of histamine (n = 6–12 mice per group). (D) Total neutrophil extravasation (n = 5–11 mice per group). (E) Frequency of neutrophil reverse TEM events in relation to total TEM events of 16.6 ± 2.1 (VEC-WT) and 19.2 ± 3.1 (VEC-Y685F) per 300-μm venular segment within 2-hour microscopy periods (mean ± SEM, n = 5–11 mice). Data are represented as mean ± SEM (each symbol represents 1 mouse/independent experiment). Indicated statistical differences are shown by *P < 0.05, 2-tailed Student’s t test. NS, not significant.