Absence of galectin-3 promotes neuroprotection in retinal ganglion cells after optic nerve injury

Abstract

A trauma to the mature central nervous system (CNS) often leads to persistent deficits, due to the inability of axons to regenerate after being injured. Increasing evidence suggests that pro-inflammatory and pro-apoptotic genes can present a major obstacle to promoting neuroprotection of retinal ganglion cells and consequently succeed in axonal regeneration. This study evaluated the effect of the absence of galectin-3 (Gal-3) on retinal ganglion cells (RGC) survival and axonal regeneration/degeneration after optic nerve crush injury. Two weeks after crush there was a 2.6 fold increase in the rate of cell survival in Gal-3-/- mice (1283±79.15) compared to WT animals (495.4±53.96). However, no regeneration was observed in the Gal-3-/- mice two weeks after lesion. Furthermore, axonal degeneration presented a particular pattern on those mice; Electron Microscopy (EM) analysis showed incomplete axon degeneration while the WT mice presented an advanced stage of degeneration. This suggests that the removal of the nerve fibers in the Gal 3-/- mice could be deficient and this would cause a delay in the process of Wallerian degeneration once there is a decrease in the number of macrophages/microglia in the nerve. This study demonstrates how the absence of Gal-3 can affect RGC survival and optic nerve regeneration/degeneration after lesion. Our results suggest that the absence of Gal-3 plays an important role in the survival of RGC and thus can be a potential target for therapeutic intervention in RGC neuroprotection.