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Tissue-resident M2 macrophages directly contact primary sensory neurons in the sensory ganglia after nerve injury.
- Source :
-
Journal of neuroinflammation [J Neuroinflammation] 2021 Oct 13; Vol. 18 (1), pp. 227. Date of Electronic Publication: 2021 Oct 13. - Publication Year :
- 2021
-
Abstract
- Background: Macrophages in the peripheral nervous system are key players in the repair of nerve tissue and the development of neuropathic pain due to peripheral nerve injury. However, there is a lack of information on the origin and morphological features of macrophages in sensory ganglia after peripheral nerve injury, unlike those in the brain and spinal cord. We analyzed the origin and morphological features of sensory ganglionic macrophages after nerve ligation or transection using wild-type mice and mice with bone-marrow cell transplants.<br />Methods: After protecting the head of C57BL/6J mice with lead caps, they were irradiated and transplanted with bone-marrow-derived cells from GFP transgenic mice. The infraorbital nerve of a branch of the trigeminal nerve of wild-type mice was ligated or the infraorbital nerve of GFP-positive bone-marrow-cell-transplanted mice was transected. After immunostaining the trigeminal ganglion, the structures of the ganglionic macrophages, neurons, and satellite glial cells were analyzed using two-dimensional or three-dimensional images.<br />Results: The number of damaged neurons in the trigeminal ganglion increased from day 1 after infraorbital nerve ligation. Ganglionic macrophages proliferated from days 3 to 5. Furthermore, the numbers of macrophages increased from days 3 to 15. Bone-marrow-derived macrophages increased on day 7 after the infraorbital nerve was transected in the trigeminal ganglion of GFP-positive bone-marrow-cell-transplanted mice but most of the ganglionic macrophages were composed of tissue-resident cells. On day 7 after infraorbital nerve ligation, ganglionic macrophages increased in volume, extended their processes between the neurons and satellite glial cells, and contacted these neurons. Most of the ganglionic macrophages showed an M2 phenotype when contact was observed, and little neuronal cell death occurred.<br />Conclusion: Most of the macrophages that appear after a nerve injury are tissue-resident, and these make direct contact with damaged neurons that act in a tissue-protective manner in the M2 phenotype. These results imply that tissue-resident macrophages signal to neurons directly through physical contact.<br /> (© 2021. The Author(s).)
- Subjects :
- Animals
Ganglia, Sensory immunology
Macrophages immunology
Male
Mice
Mice, Inbred C57BL
Mice, Transgenic
Peripheral Nerve Injuries immunology
Peripheral Nerve Injuries therapy
Sensory Receptor Cells immunology
Bone Marrow Transplantation methods
Cell Enlargement
Ganglia, Sensory pathology
Macrophages pathology
Peripheral Nerve Injuries pathology
Sensory Receptor Cells pathology
Subjects
Details
- Language :
- English
- ISSN :
- 1742-2094
- Volume :
- 18
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of neuroinflammation
- Publication Type :
- Academic Journal
- Accession number :
- 34645458
- Full Text :
- https://doi.org/10.1186/s12974-021-02283-z