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

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 1

Inflammatory human neutrophils express SEMA3F and its coreceptor NRP2.

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Inflammatory human neutrophils express SEMA3F and its coreceptor NRP2. (...
(A and B) Lung sections taken at time of tumor resection from nontumor regions of patients with moderate severity COPD were stained for SEMA3F or NRP 2 (A), or a combination of CD66b (green), NRP2 (red), and DAPI (blue) (B). Images taken at ×40 magnification. Scale bars: 100 μm in A, 20 μm in B. Human blood neutrophil SEMA3F protein expression following 4 hours culture ex vivo was assessed by Western blot (C), and fold change to unstimulated control was determined by densitometry normalized to P38 (D). The percentage of blood monocytes (CD66b–, CD14/49D+) and neutrophils (CD66b+) expressing NRP1 and NRP2 was determined in freshly isolated cells (E) and following ex vivo culture for 4 hours by flow cytometry in control and stimulated conditions (F). Data are mean ± SEM, with individual data points (n = 3–5) from independent experiments. Human blood neutrophil NRP2 protein expression following 4 hours culture ex vivo was assessed by Western blot (G) and fold change to unstimulated control was determined by densitometry normalized to P38 (H). Statistical analysis: 1-way ANOVA and Bonferroni’s post hoc tests (D and H) and 2-way ANOVA and Sidak’s post hoc tests (E and F) were performed. *P < 0.05; **P < 0.01; ***P < 0.001.