Microglia response in retina and optic nerve in chronic experimental autoimmune encephalomyelitis

Area of Science:

• Neuroscience
• Immunology
• Ophthalmology

Background:

• Experimental autoimmune encephalomyelitis (EAE) is a widely used rodent model for studying multiple sclerosis (MS).
• The long-term effects of EAE on the retina and optic nerve (ON) remain largely unknown.
• Understanding these effects is crucial for developing comprehensive therapeutic strategies for MS patients.

Purpose of the Study:

• To investigate the long-term consequences of EAE on the optic nerve and retina.
• To determine the role of glial cell activation in EAE-induced ocular pathology.
• To correlate clinical symptoms with pathological changes in the optic nerve and retina.

Main Methods:

• Induction of EAE in C57BL/6 mice using MOG35-55 peptide immunization.
• Monitoring of clinical symptoms from day 8 to day 60 post-immunization.
• Histopathological analysis of optic nerves and retinas, including cell counting (microglia, macroglia) and assessment of demyelination and axonal damage.

Main Results:

• Clinical EAE symptoms persisted up to day 60, correlating with optic nerve infiltration and demyelination.
• MOG-immunized mice exhibited increased microglia in optic nerves and retinas at day 60.
• Retinal ganglion cell (RGC) loss was observed alongside an increased macroglia response, with higher microglia numbers associated with axonal damage and RGC loss.

Conclusions:

• Long-term EAE in mice leads to significant optic nerve and retinal pathology.
• Glial activation, particularly by microglia, is a prominent feature in chronic EAE.
• The precise role of glial activation in EAE-related visual impairment requires further investigation to determine if it promotes repair or exacerbates damage.