Macrophage-Derived Vascular Endothelial Growth Factor-A Is Integral to Neuromuscular Junction Reinnervation after Nerve Injury

Copyright © 2020 the authors..

Functional recovery in the end target muscle is a determinant of outcome after peripheral nerve injury. The neuromuscular junction (NMJ) provides the interface between nerve and muscle and includes non-myelinating terminal Schwann cells (tSCs). After nerve injury, tSCs extend cytoplasmic processes between NMJs to guide axon growth and NMJ reinnervation. The mechanisms related to NMJ reinnervation are not known. We used multiple mouse models to investigate the mechanisms of NMJ reinnervation in both sexes, specifically whether macrophage-derived vascular endothelial growth factor-A (Vegf-A) is crucial to establishing NMJ reinnervation at the end target muscle. Both macrophage number and Vegf-A expression increased in end target muscles after nerve injury and repair. In mice with impaired recruitment of macrophages and monocytes (Ccr2-/- mice), the absence of CD68+ cells (macrophages) in the muscle resulted in diminished muscle function. Using a Vegf-receptor 2 (VegfR2) inhibitor (cabozantinib; CBZ) via oral gavage in wild-type (WT) mice resulted in reduced tSC cytoplasmic process extension and decreased NMJ reinnervation compared with saline controls. Mice with Vegf-A conditionally knocked out in macrophages (Vegf-Afl/fl; LysMCre mice) demonstrated a more prolonged detrimental effect on NMJ reinnervation and worse functional muscle recovery. Together, these results show that contributions of the immune system are integral for NMJ reinnervation and functional muscle recovery after nerve injury.SIGNIFICANCE STATEMENT This work demonstrates beneficial contributions of a macrophage-mediated response for neuromuscular junction (NMJ) reinnervation following nerve injury and repair. Macrophage recruitment occurred at the NMJ, distant from the nerve injury site, to support functional recovery at the muscle. We have shown hindered terminal Schwann cell (tSC) injury response and NMJ recovery with inhibition of: (1) macrophage recruitment after injury; (2) vascular endothelial growth factor receptor 2 (VegfR2) signaling; and (3) Vegf secretion from macrophages. We conclude that macrophage-derived Vegf is a key component of NMJ recovery after injury. Determining the mechanisms active at the end target muscle after motor nerve injury reveals new therapeutic targets that may translate to improve motor recovery following nerve injury.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:40

Enthalten in:

The Journal of neuroscience : the official journal of the Society for Neuroscience - 40(2020), 50 vom: 09. Dez., Seite 9602-9616

Sprache:

Englisch

Beteiligte Personen:

Lu, Chuieng-Yi [VerfasserIn]
Santosa, Katherine B [VerfasserIn]
Jablonka-Shariff, Albina [VerfasserIn]
Vannucci, Bianca [VerfasserIn]
Fuchs, Anja [VerfasserIn]
Turnbull, Isaiah [VerfasserIn]
Pan, Deng [VerfasserIn]
Wood, Matthew D [VerfasserIn]
Snyder-Warwick, Alison K [VerfasserIn]

Links:

Volltext

Themen:

Ccr2 protein, mouse
Journal Article
Muscle recovery
Nerve injury
Neuromuscular junction
Receptors, CCR2
Reinnervation
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Terminal Schwann cell
Vascular Endothelial Growth Factor A
Vascular endothelial growth factor

Anmerkungen:

Date Completed 04.03.2021

Date Revised 24.10.2023

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1523/JNEUROSCI.1736-20.2020

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM317267620