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The Protective Effect of a Topical Mucin Secretagogue on Ocular Surface Damage Induced by Airborne Carbon Black Exposure.

Purpose
Exposure to airborne particulate matter can induce ocular surface damage and inflammation. We evaluated the effects of a topical mucin secretagogue on the mitigation of ocular surface damage induced by exposure to airborne carbon black (CB).


Methods
Sprague-Dawley rats were exposed to ambient CB for 2 hours twice daily for 5 days. Corneal staining score and tear lactic dehydrogenase (LDH) activity were measured to evaluate ocular surface damage. Serum immunoglobulin (Ig) G and IgE levels and the sizes of cervical lymph nodes were also measured. The expressions of interleukin (IL)-4, IL-17, and interferon (IFN)-γ were measured by Western blot analysis. Diquafosol tetrasodium was instilled six times a day for 5 days, and the extent of ocular surface damage was evaluated.


Results
After exposure to airborne CB, the median corneal staining score and LDH activity were significantly increased. Serum IgG and IgE levels and the sizes of cervical lymph nodes were also significantly increased. Additionally, the expression of IL-4 and IFN-γ was elevated in the anterior segment of the eyeball. Furthermore, the expression of IL-4, IL-17, and IFN-γ was elevated in the cervical lymph nodes. When exposed to airborne black carbon, topical diquafosol tetrasodium significantly increased tear MUC5AC concentration and decreased tear LDH activity.


Conclusions
Exposure to airborne CB induced ocular surface damage and increased proinflammatory cytokines in the eyes and cervical lymph nodes. Topical mucin secretagogues seem to have a protective effect on the ocular surface against exposure to airborne particulate matters.