Air pollutant particulate matter 2.5 induces dry eye syndrome in mice

Abstract

In this study, we explored the effects of particulate matter 2.5 (PM2.5) eye drops on the ocular surface structure and tear function in mice and established a novel animal model for dry eye research. We found that, following treatment with PM2.5, the tear volume and, the tear film break-up time showed statistical differences at each time point (P < 0.05). The FL score of the PM2.5-treated group was higher than that of others (P < 0.05). The average number of corneal epithelial layer cells in groups A and B was significantly lower than that in group C (P < 0.05). Scanning electron microscopy and transmission electron microscopy revealed that the number of corneal epithelial microvilli and corneal desmosomes was drastically reduced in group C. PM2.5 induced apoptosis in the corneal superficial and basal epithelium and led to abnormal differentiation and proliferation of the ocular surface with higher expression levels of Ki67 and a reduced number of goblet cells in the conjunctival fornix in group C. PM2.5 significantly increased the levels of TNF-α, NF-κB p65 (phospho S536), and NF-κB in the cornea. Thus, the topical administration of PM2.5 in mice induces ocular surface changes that are similar to those of dry eye in humans, representing a novel model of dry eye.

Airborne Particulates Affect Corneal Homeostasis and Immunity

“…Nonetheless, it is worth noting that the dosage we used did not achieve levels used to induce dry eye, which is reported to occur at a dose of 5000 μg/mL. 53 Because the MCEC in vitro work suggested that there is an increase in proinflammatory and oxidative stress molecules after PM 2.5 exposure, we used the mouse model (whose corneal epithelium is stratified) described in brief elsewhere in this article, to test the effect of PM 2.5 exposure on keratitis. We found that the particulate exposed infected eye perforated at 2 days p.i.…”

A Murine Model of Acute Allergic Conjunctivitis Induced by Continuous Exposure to Particulate Matter 2.5

“…16 The only animal studies addressing PM2.5-induced effects on the cornea that have been reported so far lead to evidence of PM2.5 interference in cornea epithelium wound healing 18 and induction of dry eye syndrome. 19 Hence, all previous reports regarding PM2.5 effects on the ocular surface implicated only dry eye conditions, without referring to AC pathogenesis. There has been no report on whether PM2.5 may induce AC through its natural route, that is, direct contact with the ocular surface, and no report of an AC animal model induced by PM2.5 has been published.…”

“…One study reported by Cui et al 18 demonstrated that PM2.5 may delay cornea epithelium wound healing. Another report by Tan et al 19 showed that PM2.5 exposure led to dry eye syndrome. Although both these animal study reports did not refer to PM2.5 as a factor causing AC, several lines of evidence derived from epidemiologic studies [20][21][22] have related PM2.5 exposure to AC symptoms.…”

Potential Protective and Therapeutic Roles of the Nrf2 Pathway in Ocular Diseases: An Update

“…PM2.5 can inhibit SOD1 by promoting the expression of miRNA-206, leading to an increase in ROS and aggravating the pneumonia response and asthma symptoms [64]. Climate has also been shown to be associated with ocular surface integrity and tear film stability [65][66][67]. The tear film protects the ocular surface from many physical factors.…”