CCL2-mediated inflammatory pathogenesis underlies high myopia-related anxiety

**Background:** High myopia (axial length ≥26 mm) is a leading cause of blindness and is clinically suspected to be associated with increased anxiety, though this has not been systematically validated. CC chemokine ligand 2 (CCL2) regulates monocyte recruitment and is implicated in anxiety-related psychiatric disorders. Elevated CCL2 has been found in the aqueous humor of highly myopic eyes. This study hypothesized that CCL2-mediated inflammatory pathogenesis underlies high myopia-related anxiety.

**Methods:** The study included 104 highly myopic patients and 106 emmetropic controls. Anxiety was assessed using the Hamilton Anxiety Scale (HAMA). Blood CCL2 levels were measured with a cytokine array, and monocyte levels (CD14+ and CD14+/CD68+) were quantified by flow cytometry. A defocus-induced highly myopic mouse model was created by attaching a −10 D lens to one eye for 4 weeks. Anxiety-like behaviors were evaluated using open field test (OFT), elevated plus maze (EPM), and Vogel test. CCL2 expression in the retina was assessed by immunofluorescence and western blotting. Monocyte/macrophage infiltration in the uvea and brain was quantified by flow cytometry and immunofluorescence. Blood-ocular barrier (BOB) and blood-brain barrier (BBB) integrity were evaluated using enhanced MRI, Evans Blue staining, and tight junction protein (occludin, ZO-1) expression. Mechanistic studies used GFP-positive bone marrow chimeric mice, parabiotic mouse models, Ccl2-deficient mice, and CCL2-neutralizing antibody treatment.

**Key Results:** Highly myopic patients had significantly higher total anxiety scores (3.66±3.43 vs 1.61±1.77, P<0.0001) and psychic anxiety scores (2.57±2.51 vs 0.88±1.22, P<0.0001). 18% had mild to moderate anxiety and 2% severe anxiety, vs 3% and 0% in controls (P<0.001 and P=0.001). Blood CCL2 levels were higher in highly myopic patients (30.04±14.19 pg/mL vs 24.64±14.63 pg/mL, P=0.0073), and even higher in those with anxiety (39.59±18.36 pg/mL vs 27.62±11.90 pg/mL, P=0.0004). Monocyte ratios (CD14+) were elevated (5.66±2.41% vs 2.94±0.52%, P=0.0024). Anxiety scores correlated positively with CCL2 (r=0.350, P=0.0003) and monocyte levels. In mice, high myopia induced anxiety-like behaviors (shorter center duration, fewer entries, fewer head dips) and upregulated CCL2 in the retinal ganglion cell and photoreceptor cell layers. Blood CCL2 was higher in highly myopic mice (99.98±51.29 pg/mL vs 15.47±4.57 pg/mL, P=0.0005). Monocyte infiltration increased in the uvea (CD11b+/CD45+ 1.20±0.76% vs 0.29±0.13%, P=0.0312) and brain (CD11b+/Ly6C+ 2.59±1.88% vs 0.23±0.21%, P=0.0273). Enhanced MRI showed faster contrast leakage into the anterior chamber of highly myopic eyes, and Evans Blue leakage into the brain was increased. Tight junction proteins occludin and ZO-1 were downregulated in the ciliary body, retina, and brain vessels. Ccl2 deficiency or CCL2-neutralizing antibody significantly reduced anxiety-like behaviors, monocyte infiltration, and BOB/BBB disruption. For example, Ccl2-deficient highly myopic mice had lower blood CD11b+/Ly6Chi monocytes (0.73±0.43% vs 2.99±1.85%, P=0.0002) and reduced brain monocyte infiltration (0.55±0.58% vs 2.59±1.88%, P=0.0087). Golgi staining showed that high myopia increased spine density in BLA pyramidal neurons and decreased it in ventral hippocampus neurons, partially reversed by Ccl2 deficiency.

**Clinical Implications:** This study provides the first evidence linking high myopia to anxiety through a CCL2-mediated inflammatory mechanism. Elevated CCL2 and monocyte levels in the blood may serve as biomarkers for anxiety risk in highly myopic patients. Targeting CCL2 or its downstream inflammatory pathways could offer therapeutic strategies to alleviate anxiety in this population. The findings also highlight the potential connection between visual stimulation and psychiatric disorders, emphasizing the need for integrated ophthalmic and psychiatric care in high myopia management.