Müller glia–myeloid cell crosstalk accelerates optic nerve regeneration in the adult zebrafish. Issue 6 (27th January 2021)

• Record Type: Journal Article
• Authors: Van Dyck, Annelies; Bollaerts, Ilse; Beckers, An; Vanhunsel, Sophie; Glorian, Nynke; van houcke, Jessie; van Ham, Tjakko J.; De Groef, Lies; Andries, Lien; Moons, Lieve
• Is Part Of: Glia. Volume 69:Issue 6(2021)
• Page Start: 1444
• Page End: 1463
• Publication Date: 2021-01-27
• Subjects: axonal regeneration -- microglia -- Müller glia -- neuroinflammation -- optic nerve injury -- retina -- zebrafish; Neuroglia -- Periodicals; Neurology -- Periodicals; 611.0188
• DOI: 10.1002/glia.23972
• Languages: English
• ISSNs: 0894-1491

Abstract

Abstract: Neurodegenerative disorders, characterized by progressive neuronal loss, eventually lead to functional impairment in the adult mammalian central nervous system (CNS). Importantly, these deteriorations are irreversible, due to the very limited regenerative potential of these CNS neurons. Stimulating and redirecting neuroinflammation was recently put forward as an important approach to induce axonal regeneration, but it remains elusive how inflammatory processes and CNS repair are intertwined. To gain more insight into these interactions, we investigated how immunomodulation affects the regenerative outcome after optic nerve crush (ONC) in the spontaneously regenerating zebrafish. First, inducing intraocular inflammation using zymosan resulted in an acute inflammatory response, characterized by an increased infiltration and proliferation of innate blood‐borne immune cells, reactivation of Müller glia, and altered retinal cytokine expression. Strikingly, inflammatory stimulation also accelerated axonal regrowth after optic nerve injury. Second, we demonstrated that acute depletion of both microglia and macrophages in the retina, using pharmacological treatments with both the CSF1R inhibitor PLX3397 and clodronate liposomes, compromised optic nerve regeneration. Moreover, we observed that csf1ra/b double mutant fish, lacking microglia in both retina and brain, displayed accelerated RGC axonal regrowth after ONC, which was accompanied with unusual Müller glia proliferative gliosis. Altogether, our results highlight the importance of altered glial cell interactions in the axonal regeneration process after ONC in adult zebrafish. Unraveling the relative contribution of the different cell types, as well as the signaling pathways involved, may pinpoint new targets to stimulate repair in the vertebrate CNS. Main points: (1) Influx of innate immune cells after inflammatory stimulation, (2) as well as depletion of microglia, results in improved optic nerve regeneration in adult zebrafish. Both cases coincide with increased proliferative reactivation of Müller glia.