Abstract
Purpose :
Myelin sheaths play an important role in neurodegenerative diseases; the conduction of the action potential is impaired without normal myelin sheaths, which could cause visual dysfunction and cognitive impairment. Sphingosine-1-phosphate receptor 2 (S1PR2), a G-protein coupled receptor, was previously reported to be associated with demyelination. We hypothesize that decreased S1PR2 by JTE-013 could reverse the demyelination and protect the survival of retinal ganglion cells (RGCs) and axonal regeneration.
Methods :
Adult wild-type male C57Bl/6J mice (5-8 weeks) were purchased to establish the retinal ischemia/reperfusion (I/R) model. The right eye was perfused with sterile 0.9% saline solution for 1 hour to hold the IOP at 70 mmHg. The mice were randomly categorized into three groups in our experiments: blank control group, injured group, and treatment group. The eyes in the treatment group (N=3-7) were intravitreally injected with 3μl JTE-013 immediately after reperfusion, and the eyes in the injured group (N=3-7) with 3μl PBS. The optic nerves were perfusion-fixed and sectioned for immunofluorescent staining. We could detect the change of S1PR2 in the three groups. Then we measured the fluorescence intensity of myelin basic protein (MBP) and SMI32 to evaluate demyelination and axonal degeneration. The retinas were stained with βIII-tubulin and RBPMS to calculate the number of RGCs. Finally, we could observe the myelin sheaths and axons of the optic nerve by transmission electron microscope. One-way ANOVA and unpaired t test was used for statistical analysis.
Results :
The expression of S1PR2 significantly increased in the injured (p<0.05) groups and the JTE-013 could inhibit the increase of S1PR2 (Figure 1A). The fluorescence intensity of MBP was significantly decreased in the injured (p<0.01) group, and JTE-013 could alleviate demyelination (p<0.001) (Figure 1B). Meanwhile, inhibiting S1PR2 could increase the number of RGCs (p<0.001) and reduce axonal degeneration (p<0.05) compared to the injured group (Figure 2). Quantification of G-ration and axons in electron micrographs also showed that JTE-013 could decrease myelin loss and increase the number of axons.
Conclusions :
JTE-013 could relieve demyelination by inhibiting S1PR2, protecting RGCs and axons.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.