Fig. 2: IL-4 protected neuroretinal structure and function in the NaIO3-induced retinal degenerative mice.

A The funduscopy of NaIO₃-induced degenerative retina was characterized by pale appearance and some dot-like or linear lesions showing structural damage (blue arrows), which were alleviated after IL-4 treatment. n = 6. B Representative images of the OCT scanning. The NaIO₃ model demonstrated obvious discontinuity of RPE layer with high-reflective deposits (red arrows), while IL-4-treated RPE exhibited as a smooth, continuous, and uniform reflectiveness layer. The ONL thickness (distance between yellow lines) was calculated and compared. n = 6. C H&E staining showed crumby-structure patches and melanin rich aggregation in the RPE layer of the NaIO₃-retina, particularly in the mid-peripheral locations. After IL-4 treatment, the RPE layer was preserved and well-organized with less melanin rich aggregation and the retinal folds were relieved. Scale bar: 50 μm and 25 μm. D Representative images of RPE flat-mount in the center, mid-periphery and periphery areas sheet showing RPE integrity by ZO-1 staining. NaIO₃ disrupted the well-organized hexagonal-shaped RPE cells, whereas IL-4 treatment could preserve it with more organized barrier structures specifically in the mid-periphery and periphery areas. Statistical analysis showed the amount of ZO-1+ cells. n = 6, Scale bar: 20 μm. E ERG examinations showed a- and b-waves were almost extinct in NaIO₃-retina. However, IL-4 treatment protected the neuroretinal functions with increased amplitudes of both a- and b-waves. n = 6. Data are shown as mean ± SEM, ***P < 0.001, n.s: not significant, one-way ANOVA test.