mTOR/HIF-1α-associated scleral metabolic reprogramming by Mingshi formula in form-deprivation myopia

Focusing on the mTOR-HIF-1α signaling pathway, this study investigated the mechanism through which the traditional Chinese medicine compound Mingshi Formula delays the progression of form-deprivation myopia (FDM) in guinea pigs. The guinea pigs were divided into the normal control group (NC), FDM group, Mingshi Formula low-dose group (FDM + Low), medium-dose group (FDM + Medium), high-dose group (FDM + High), and MTOR inhibitor group (FDM + RapaLink-1). The guinea pig model of FDM was established by applying 3D-printed hoods modified by a latex balloon with 60% light transmission for 4 weeks. Refractive error changes were monitored using a refractometer. Axial length was quantitatively analyzed using A-scan ultrasound, choroidal thickness was measured with SD-OCT, and structural changes of the choroid and sclera were observed after hematoxylin-eosin (HE) staining. At the molecular level, the expression levels of the mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), HIF-1α, LDHA, PKM2, MMP2, Collagen I, and α-SMA in the sclera were measured by RT-qPCR and Western blotting. The spatial distribution characteristics of mTOR, p-mTOR, HIF-1α, and Collagen I were verified via immunofluorescence techniques. The results demonstrated that the Mingshi Formula significantly decreased myopic refractive error and axial length (p < 0.01), increased choroidal thickness (p < 0.05), downregulated the gene and protein expression of mTOR, p-mTOR, HIF-1α, LDHA, PKM2, MMP2, and α-SMA in response to hypoxia, and upregulated the expression of Collagen I compared to the FDM group. We demonstrated that MingShi formula modulates the mTOR/HIF-1α signaling axis to ameliorate scleral hypoxic metabolic homeostasis, regulate Collagen synthesis, inhibit aberrant extracellular matrix remodeling, and ultimately delay myopia progression.