Air pollutants, especially ambient fine particulate matter2.5, may contribute to various ocular surface disorders, including
dry eye disease,
keratitis and
conjunctivitis. A natural
polyamine spermidine has a protective effect on the retina and optic nerve; however, no study has been conducted on the application of
spermidine in particulate matter2.5-induced
dry eye disease. In the present study, we investigated the effect of
spermidine eye drops in topically exposed particulate matter2.5-induced
dry eye models of Sprague-Dawley rats, by hematological, biochemical and histological evaluation.
Spermidine eye drops attenuated the particulate matter2.5 exposure-induced reduction of tear secretion and corneal epithelial damage. Furthermore,
spermidine protected against conjunctival goblet cell loss and retinal ganglion cell loss induced by particulate matter2.5. Additionally,
spermidine markedly prevented particulate matter2.5-induced infiltration of cluster of differentiation3+ and cluster of differentiation4+ T lymphocytes and F4/80+ macrophages on lacrimal gland. Moreover, over expression of pro-inflammatory
cytokines, including
tumor necrosis factor-α,
interleukin-6 and
interleukin-17 in the lacrimal gland and cornea. Meanwhile, the levels of serum total
cholesterol and
low-density lipoprotein cholesterol were markedly increased by topical exposure to particulate matter2.5, but this change in the
lipid profile was decreased by
spermidine. Taken together,
spermidine may have protective effects against particulate matter2.5-induced
dry eye symptoms via stabilization of the tear film and suppression of
inflammation and may in part contribute to improving
retinal function and
lipid metabolism disorder.