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A Murine Model of Acute Allergic Conjunctivitis Induced by Continuous Exposure to Particulate Matter 2.5
Yu-Jun Tang1, Han-Hsin Chang2, Chun-Yi Chiang3
1Institute of Biochemistry, Microbiology, and Immunology, Chung Shan Medical University, Taichung, Taiwan.
Purpose:
Several pieces of epidemiologic evidence have indicated PM2.5 (particulate matter with a diameter of 2.5 μm or less) as a causing factor of allergic conjunctivitis, but without experimental elucidation of mechanism. In the present study, PM2.5 in solution was directly applied to the mouse ocular surface to elucidate whether PM2.5 might cause allergic conjunctivitis, and its underlying mechanisms were analyzed.
Methods:
ICR mice were challenged for 18 consecutive days with eye drops containing PM2.5 at 3.2, 6.4, and 12.8 mg/mL in 0.9% NaCl saline, along with the controls prepared in parallel without PM2.5 and another control group treated with both PM2.5 at 12.8 mg/mL and artificial tears. On day 19, the whole eyes and meibomian glands were harvested for histopathological analyses and assessment of clinical scoring, tear volume, tear breakup time, and tear ferning. Furthermore, goblet cells by periodic acid Schiff stain and infiltrated eosinophils by Giemsa stain were quantified and compared among study groups.
Results:
Clinical scoring showed more eyelid edema, tearing, and scratching behaviors, with longer tear breakup time under the influence of increased PM2.5 concentrations. Tear ferning assay showed less tear crystal formation and decreased crystal branches after exposure to PM2.5. In addition, higher goblet cell density in the upper palpebral conjunctiva and extensive eosinophil infiltration in the entire conjunctiva and in the meibomian glands were induced by PM2.5.
Conclusions:
These results demonstrate that PM2.5 can induce symptoms similar to clinical allergic conjunctivitis and that the murine acute allergic conjunctivitis model can be induced by direct exposure to PM2.5.
Insights
Particulate matter (PM2.5) exposure directly caused allergic conjunctivitis symptoms in mice, including eyelid swelling and tearing. This study establishes a new animal model for allergic eye disease research.
Area of Science:
- Ophthalmology
- Environmental Health
- Immunology
Background:
- Epidemiological studies link PM2.5 to allergic conjunctivitis.
- The precise mechanisms remain unclear.
- Experimental validation is needed.
Purpose of the Study:
- To investigate if PM2.5 directly induces allergic conjunctivitis.
- To elucidate the underlying mechanisms of PM2.5-induced ocular inflammation.
Main Methods:
- Mice received topical PM2.5 eye drops for 18 days.
- Evaluated clinical signs, tear parameters, and goblet cell density.
- Quantified eosinophil infiltration in ocular tissues.
Main Results:
- PM2.5 exposure increased eyelid edema, tearing, and scratching.
- Tear film stability decreased, with altered tear ferning.
- Goblet cell hyperplasia and significant eosinophil infiltration were observed.
Conclusions:
- PM2.5 directly induces allergic conjunctivitis-like symptoms in mice.
- This study successfully created a murine model for acute allergic conjunctivitis via PM2.5 exposure.
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