Wanjing Chen, Yoko Iizuka, Fumihiko Mabuchi, Satoko Yoshizawa, Tomoko Muramatsu, Kenji Kashiwagi
Long-term exposure to ambient particulate matter ≤2.5 μm in aerodynamic diameter (PM2.5) has been associated with optic neuropathy and retinal neurodegeneration, but experimental evidence remains limited. We assessed two certified environmental particulate reference materials in primary mouse retinal cells and after repeated ocular-surface exposure in mice. For the in vitro analyses, technical replicate wells were first averaged within each independent cell isolation, and each experimental condition was then normalized to the corresponding control from the same biological replicate. Particulate exposure produced condition-dependent changes in 2',7'-dichlorofluorescin diacetate (DCFDA) fluorescence and ATP-dependent viability, with statistically significant effects concentrated in selected retinal glial-cell conditions. After within-experiment normalization and multiplicity adjustment, direct comparisons did not demonstrate a statistically significant protective effect of α-tocopherol or N-acetylcysteine on particulate-associated responses, and retinal glial-cell coculture did not significantly improve RGC survival relative to monoculture. In postnatal mice, topical particulate administration was associated with inner retinal thinning and lower RGC-marker-positive cell counts. In adult Thy1-CFP mice, neither sample-specific nor post hoc pooled within-mouse comparisons with contralateral saline-treated eyes were statistically significant. A separate post hoc exploratory between-animal comparison showed fewer CFP-positive cells in pooled particulate-treated eyes than in independent bilateral-saline controls (mean difference, -14.4 cells; 95% CI, -28.1 to -0.7; P = 0.040). These findings support cellular and retinal susceptibility under the conditions used, but they do not establish particle transport to the retina, a causal oxidative mechanism, or quantitative risk from ambient PM2.5 exposure in humans.