AZGP1 Attenuates Subretinal Fibrosis and Inhibits Epithelial-Mesenchymal Transition by Blocking the PI3K/AKT Signaling Pathway

Purpose: Subretinal fibrosis (SRF) represents a significant contributor to irreversible vision loss in patients with neovascular age-related macular degeneration (nAMD). This study aimed to elucidate the underlying mechanism of SRF and identify potential therapeutic targets.

Methods: The SRF model was established using a two-stage laser-induced protocol in C57BL/6J mice. RNA-seq analysis was conducted to identify differentially expressed genes (DEGs) at 10 days and 30 days post-second laser. Quantitative RT-PCR was used to validate the expression levels of selected DEGs including zinc-alpha-2-glycoprotein 1 (AZGP1). Recombinant AZGP1 (rAZGP1) was intravitreally administrated to investigate its effects on SRF. The ARPE-19 cells were used to demonstrate the role of AZGP1 in modulating epithelial-mesenchymal transition (EMT).

Results: RNA-seq of RPE/choroid complex identified a total of 66 DEGs between samples collected at 10 days and 30 days post-second laser compared with controls (log2(fold change) ≥ 1, false discovery rate [FDR] < 0.05), with Azgp1 being one of the most significant downregulated genes. Intravitreal injection of rAZGP1 markedly reduced Collagen I and CD31 positive areas in RPE/choroid flat-mounts. Co-localization of AZGP1 and RPE65 was observed in patients with nAMD (GSE135922) and SRF mouse models. Treatment with rAZGP1 resulted in significantly lower expressions of Collagen I, α-SMA, and fibronectin in ARPE-19 cells after TGFβ1 induction. Both knockdown and overexpression studies demonstrated that AZGP1 regulated the PI3K/Akt signaling pathway within ARPE-19 cells.

Conclusions: The abnormal expression pattern of AZGP1 is critical for the development of SRF. Exogenous supplementation with AZGP1 may represent a promising strategy for ameliorating SRF by inhibiting EMT within RPE through the PI3K/Akt pathway.