Tracking astrocyte polarization in the retina in retinopathy of prematurity.

Astrocyte patterns affect the normal development of the retinal vascular network in retinopathy of prematurity (ROP), which is associated with VEGF secretion. However, the role of the astrocyte polarization in this process remains unknown. Therefore, this study aimed to track the status of A1/A2 reactive astrocytes in the retinas of the oxygen-induced retinopathy (OIR) model and their association with VEGF expression. The C57BL/6 mouse OIR model was constructed to characterize the pathological changes in ROP. Immunofluorescence of iB4 and GFAP staining was performed to observe changes in the vascular network and astrocyte pattern at different time points (P0, P7, P12, P17, and P21). C3-labeled A1 reactive and S100A10-labeled A2 reactive astrocytes and VEGF were also observed. The pattern of GFAP-labeled astrocyte was altered concurrently with the iB4-positive vascular network during OIR. Astrocyte activity was significantly weakened at P12 and significantly enhanced at P17. Notably, the number of C3-labeled A1 reactive astrocytes was significantly increased at P12, decreased at P17, and normalized at P21 in OIR models. S100A10-labeled A2 reactive astrocytes were significantly increased at P17 but did not change significantly at P12 or P17. VEGF levels were decreased at P7-P12 and increased at P12-P17. The expression pattern of VEGF was opposite to that of C3-labeled A1 reactive astrocytes and identical to that of S100A10-labeled A2 reactive astrocytes. In conclusion, the astrocyte pattern and vascular network exhibited similar changes during the OIR process, and the periods of vaso-obliteration and neo-vascularization display an abnormal activation in A1-and A2-reactive astrocytes.