Targeting the cochlin/SFRP1/CaMKII axis in the ocular posterior pole prevents the progression of nonpathologic myopia

**Background:** Myopia is a major public health issue, especially in children and adolescents, with high prevalence in Asia (80–90% juvenile myopia). Nonpathologic myopia can progress to pathologic myopia, which causes irreversible vision loss. Current treatments (spectacles, orthokeratology, low-dose atropine, laser surgery) are symptomatic and lack precise molecular targets. Blurred retinal images and reduced choroidal blood perfusion are implicated in myopia pathogenesis, but the signaling axis linking these events is unknown. This study aimed to identify a molecular pathway from retinal photoreceptors to choroidal vessels that drives nonpathologic myopia.

**Methods:** Guinea pig form-deprived myopia (FDM) and lens-induced myopia (LIM) models were established. Ocular posterior pole tissues were analyzed by high-throughput proteomics (iTRAQ LC-MS/MS). Cochlin expression was validated by qPCR, western blot, immunohistochemistry, and immunofluorescence. Human ARPE-19 and primary RPE cells were stimulated with recombinant human cochlin, and transcriptomic changes were assessed by microarray. SFRP1 expression was confirmed by qPCR and ELISA. Simian choroidal vascular endothelial cells (RF/6A) were treated with SFRP1 (30 ng/ml) or conditioned media from cochlin-stimulated RPE cells, with or without WAY 316606 (SFRP1 inhibitor) or Wnt3a (canonical Wnt activator). Functional assays included CCK-8 proliferation, caspase 3/7 activity, annexin V apoptosis, Matrigel aggregation, and Transwell migration. Intracellular Ca2+ concentration and p-CaMKII/CaMKII levels were measured. In vivo, FDM guinea pigs received intravitreal injections of lentiviral shRNA against Coch or WAY 316606. Refraction, axial length, choroidal blood perfusion (OCTA), and choroidal vessel lumen area (histology) were assessed at 1 and 6 weeks post-induction.

**Key Results:** Proteomics identified cochlin as the most upregulated protein in FDM (3.78-fold vs normal) and LIM models. Cochlin upregulation occurred as early as 1 week post-induction, correlated with refraction and axial length changes, and localized to photoreceptor inner/outer segments and RPE interface. In RPE cells, cochlin stimulation increased SFRP1 mRNA (8.61-fold in microarray; 4.41-fold by qPCR in ARPE-19; 2.74-fold in primary RPE) and protein (31.59 ng/ml in ARPE-19 CM; 33.33 ng/ml in primary RPE CM). SFRP1 (30 ng/ml) did not affect proliferation but increased caspase 3/7 activity by 39.75% (P<0.05), reduced Matrigel aggregation by 27.25% (P<0.01), and increased Transwell migration (P<0.001). These effects were reversed by WAY 316606 and Wnt3a. SFRP1 elevated intracellular Ca2+ by 18.08% (P<0.01) and increased p-CaMKII (P<0.001) without affecting β-catenin signaling. In vivo, FDM caused significant myopia (refraction decreased 211.14% at 6 weeks), axial elongation (102.71% increase at 6 weeks), and reduced choroidal blood perfusion (27.30% at 1 week, 16.65% at 6 weeks). Cochlin shRNA reduced cochlin protein by 39.75% at 1 week and 63.72% at 6 weeks, and normalized p-CaMKII. Both shRNA and WAY 316606 prevented myopia progression (refraction and axial length) and restored choroidal blood perfusion and vessel lumen area (all P<0.001 vs FDM).

**Clinical Implications:** This study identifies a novel cochlin/SFRP1/CaMKII signaling axis that links retinal blur to choroidal vascular dysfunction in nonpathologic myopia. Targeting cochlin (via gene knockdown) or SFRP1 (via pharmacological inhibition) prevented myopia progression in a guinea pig model by improving choroidal circulation. These findings provide two actionable molecular targets for early intervention in nonpathologic myopia, potentially reducing progression to pathologic myopia. Limitations include lack of validation in human clinical samples and the possibility that cochlin/SFRP1 upregulation may be a consequence rather than cause of axial elongation. Future studies should test these targets in human trials and develop small-molecule inhibitors of SFRP1.