Semaphorin 3F signaling actively retains neutrophils at sites of inflammation
Tracie Plant, … , Moira K.B. Whyte, Sarah R. Walmsley
Tracie Plant, … , Moira K.B. Whyte, Sarah R. Walmsley
Published March 19, 2020
Citation Information: J Clin Invest. 2020;130(6):3221-3237. https://doi.org/10.1172/JCI130834.
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Research Article Inflammation Pulmonology Article has an altmetric score of 12

Semaphorin 3F signaling actively retains neutrophils at sites of inflammation

Abstract

Neutrophilic inflammation is central to disease pathogenesis, for example, in chronic obstructive pulmonary disease, yet the mechanisms that retain neutrophils within tissues remain poorly understood. With emerging evidence that axon guidance factors can regulate myeloid recruitment and that neutrophils can regulate expression of a class 3 semaphorin, SEMA3F, we investigated the role of SEMA3F in inflammatory cell retention within inflamed tissues. We observed that neutrophils upregulate SEMA3F in response to proinflammatory mediators and following neutrophil recruitment to the inflamed lung. In both zebrafish tail injury and murine acute lung injury models of neutrophilic inflammation, overexpression of SEMA3F delayed inflammation resolution with slower neutrophil migratory speeds and retention of neutrophils within the tissues. Conversely, constitutive loss of sema3f accelerated egress of neutrophils from the tail injury site in fish, whereas neutrophil-specific deletion of Sema3f in mice resulted in more rapid neutrophil transit through the airways, and significantly reduced time to resolution of the neutrophilic response. Study of filamentous-actin (F-actin) subsequently showed that SEMA3F-mediated retention is associated with F-actin disassembly. In conclusion, SEMA3F signaling actively regulates neutrophil retention within the injured tissues with consequences for neutrophil clearance and inflammation resolution.

Authors

Tracie Plant, Suttida Eamsamarng, Manuel A. Sanchez-Garcia, Leila Reyes, Stephen A. Renshaw, Patricia Coelho, Ananda S. Mirchandani, Jessie-May Morgan, Felix E. Ellett, Tyler Morrison, Duncan Humphries, Emily R. Watts, Fiona Murphy, Ximena L. Raffo-Iraolagoitia, Ailiang Zhang, Jenna L. Cash, Catherine Loynes, Philip M. Elks, Freek Van Eeden, Leo M. Carlin, Andrew J.W. Furley, Moira K.B. Whyte, Sarah R. Walmsley

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Figure 7

Neutrophil treatment with exogenous SEMA3F blocks chemotactic responses while preserving phagocytic capacity and respiratory burst functions.

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Neutrophil treatment with exogenous SEMA3F blocks chemotactic responses ...
(A–F) Isolated peripheral blood neutrophils from healthy volunteers were incubated with recombinant SEMA3F (0–100 nM), and functional assays were performed. (A and B) Chemotactic behavior of neutrophils to fMLF (0–100 nM) and LTB4 were measured by Boyden chamber, CC chemokinesis control (A), and microfluidic chip assay (B). (C) Neutrophils were incubated with Alex 488 E. coli and phagocytic uptake was determined by flow cytometry, with adhesion excluded by 4°C control. (D) Phagocytic indices were calculated by cytospin following neutrophil culture with opsonized Zymosan particles for 30 minutes. (E) ROS generation was determined following a 1 hour preincubation with SEMA3F and treatment with fMLF for 30 minutes. (F) Neutrophil release of elastase was measured by fluorimetric assay following pretreatment with 1 hour of SEMA3F, 30 minutes of GM-CSF (10 ng/mL), and 10 minutes of fMLF (100 nM). All data are mean ± SEM with individual data points from independent experiments (n = 3–6). Statistical analysis was by 1-way ANOVA and Sidak’s post hoc test (A, B, E, and F) or paired t test (C–E). *P < 0.05; **P < 0.01; ****P < 0.0001.