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 6

Systemic CXCL1 promotes neutrophil reverse TEM.

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Systemic CXCL1 promotes neutrophil reverse TEM. Cremaster muscles of Lys...
Cremaster muscles of LysM-EGFP-ki mice were stimulated with IL-1β (50 ng for 2 hours) followed by topical superfusion of histamine onto exteriorized tissues or subjected to IR injury. Blocking anti-CXCL1 mAb (1 mg/kg), or control IgG, was injected i.v. 30 minutes before exteriorization of tissues or at the point of tissue reperfusion. (A) Time course of dextran accumulation in the perivascular region of selected stimulated postcapillary venules. Tissue dextran accumulation is represented as normalized MFI (n = 4–6 mice per group). (B) Total neutrophil extravasation (n = 4–5 mice/group) and (C) frequency of neutrophil reverse TEM events in relation to total TEM events of 14 ± 2 (control mAb) and 20 ± 2.9 (anti-CXCL1 mAb) per 300-μm venular segment within 2-hour microscopy periods (mean ± SEM, n = 5–6 mice/group). (D) Total neutrophil extravasation (n = 3–6 mice/group) and (E) frequency of neutrophil reverse TEM events in relation to total TEM events of 26.7 ± 3.8 (control mAb) and 26 ± 4.3 (anti-CXCL1) per 300-μm venular segment within 2-hour microscopy periods (mean ± SEM, n = 3–7 mice/group). (F) Cremaster muscles of LysM-EGFP-ki mice were stimulated with IL-1β (50 ng for 2 hours) followed by i.v. injection of murine rCXCL1 (50 ng). Frequency of neutrophil reverse TEM events in relation to total TEM events of 16 ± 2.8 (IL-1β) and 12.9 ± 1.8 (IL-1β + CXCL1) per 300-μm venular segment within 2-hour microscopy periods (mean ± SEM, n = 5–7 mice/group). Data are represented as mean ± SEM (each symbol represents 1 mouse/independent experiment). Statistically significant differences from control mAb–treated groups (C and E) or IL-1β–treated tissues (F) are shown by *P < 0.05; ***P < 0.001, 2-tailed Student’s t test.