A Novel Small Peptide H-KI20 Inhibits Retinal Neovascularization Through the JNK/ATF2 Signaling Pathway.

Purpose: Abundant evidence has shown benefits of antivascular endothelial growth factor (anti-VEGF) therapies in neovascular eye diseases. However, the high cost, side effects, and inconvenience of frequent injections demand alternative novel drug candidates. This study aimed to analyze antiangiogenic effects of peptide H-KI20 and illustrated signaling mechanisms.

Methods: Live cell culture and tracing, wound healing assay, and tube formation were performed in human retinal microvascular endothelial cells (HRECs). The chick embryo chorioallantoic membrane and mouse oxygen-induced ischemic retinopathy model were applied to examine the effects of H-KI20 in vivo. The intracellular signaling pathways were examined. Molecular docking and surface plasmon resonance assay were used to validate the direct interaction of H-KI20 and c-Jun N-terminal kinase 2 (JNK2).

Results: H-KI20 had high penetration ability in vitro and in vivo. It inhibited motility, migration, and tube formation of HRECs, without cytotoxicity, and inhibited angiogenesis in vivo. Furthermore, H-KI20 treatment reduced the phosphorylation level of activating transcription factor 2 (ATF2) stimulated by VEGF via downregulating p-JNK. H-KI20 bound to JNK2 directly with a dissociation constant value of 83.68 µM. The knockdown of ATF2 attenuated VEGF-induced tube formation and decreased the movement speed of HRECs.

Conclusions: H-KI20 inhibited angiogenesis both in vitro and in vivo. The ratios of p-ATF2/ATF2 and p-JNK/JNK stimulated by VEGF were decreased by H-KI20, and H-KI20 targeted JNK2 directly. In addition, the pivotal role of ATF2 in VEGF-induced retinal neovascularization was elucidated for the first time. Taken together, H-KI20 displays potential for pathological retinal angiogenesis as a sustained and low-toxic peptide.