Yingmu San ameliorates pathological myopia by protecting retinal pigment epithelium and enhancing...

Pathological myopia is associated with progressive axial elongation and retinal pigment epithelium (RPE) injury, in which oxidative stress, inflammation, and mitochondrial dysfunction are important pathological contributors. Yingmu San (YMS) is a defined multi-component formulation composed of peony seed oil (PSO), lutein, and zeaxanthin at fixed proportions. However, whether YMS protects the RPE during myopia progression and whether mitophagy-associated responses are involved in this effect remain unclear.

This study aimed to determine whether YMS protects RPE cells and alleviates myopia-associated retinal injury and to clarify whether mitochondrial quality control, particularly AMPK/mTOR/ULK1- and PINK1/Parkin-associated mitophagy responses, contributes to this protection.

This mechanism-oriented study integrated form-deprivation myopia (FDM) mouse and hypoxia (Hx)-induced adult retinal pigment epithelial cell line-19 (ARPE-19) cell models to evaluate YMS-mediated retinal protection and investigate mitophagy-associated mechanisms using transcriptomic, pharmacological, and genetic approaches.

An FDM mouse model and Hx-injured ARPE-19 cells were used to evaluate myopia-associated retinal injury and RPE damage. The chemical profile and batch consistency of YMS were assessed by UHPLC-APCI-MS, and the contribution of representative components was evaluated in Hx-injured cells. Retinal outcomes, mitochondrial function, oxidative stress, apoptosis, and NLRP3 inflammasome activation were examined. RNA sequencing, pathway enrichment analysis, autophagic/mitophagic flux assays, intracellular ATP measurement, pharmacological modulation, AKT overexpression, siAMPK, and siPINK1 interventions were used to investigate the mechanism of YMS.

YMS reduced axial elongation and refractive shifts, preserved retinal and RPE architecture, and improved retinal and choroidal blood flow in FDM mice. YMS displayed consistent chromatographic profiles across five independently prepared batches, and the complete formulation protected Hx-injured ARPE-19 cells more effectively than individual formulation-matched components. In Hx-injured cells, YMS restored mitochondrial membrane potential and ATP levels, reduced ROS accumulation, and suppressed apoptosis and NLRP3 inflammasome-associated responses. Transcriptomic analyses identified autophagy-, lysosome-, AMPK-, mTOR-, and mitophagy-related pathways associated with YMS treatment. Mechanistically, YMS increased AMPK and activation-associated ULK1 signaling, suppressed PI3K/AKT-mTOR signaling, and enhanced PINK1/Parkin-associated mitophagy responses. Genetic analyses suggested that YMS-induced AMPK activation and PI3K/AKT suppression are not fully explained by a simple one-direction linear hierarchy, although complete pathway independence was not established. Importantly, PINK1 knockdown attenuated YMS-induced autophagic responses and weakened its mitochondrial protective, anti-apoptotic, and anti-inflammatory effects in Hx-injured ARPE-19 cells. In FDM mice, YMS preserved RPE mitochondrial morphology and was associated with increased mitophagy-related signals and reduced apoptosis- and inflammasome-associated injury.

YMS protects RPE cells and alleviates myopia-associated retinal injury by preserving mitochondrial function and reducing oxidative and inflammatory damage, accompanied by enhanced PINK1/Parkin-associated mitophagy responses. These findings support the further evaluation of YMS as a potential intervention for myopia-associated retinal degeneration, while the in vivo requirement of mitophagy remains to be defined.