Polluted Air Exposure Compromises Corneal Immunity and Exacerbates Inflammation in Acute Herpes Simplex Keratitis

Area of Science:

• Environmental Science
• Immunology
• Ophthalmology

Background:

• Air pollution is a global environmental concern, particularly in megacities, impacting public health and exacerbating ocular diseases.
• Herpes simplex keratitis (HSK), caused by herpes simplex virus type 1 (HSV-1), can lead to corneal scarring and vision impairment.

Purpose of the Study:

• To investigate the immunopathological effects of urban air pollution on acute herpes simplex keratitis (HSK).
• To model HSK in mice exposed to experimental urban polluted air from Buenos Aires.

Main Methods:

• Evaluated clinical outcomes, viral DNA, and pro-inflammatory cytokines (TNF-α, IL-1β, IFN-γ, CCL2) using RT-PCR and ELISA.
• Assessed innate and adaptive immune responses in the cornea and lymph nodes via immunofluorescence and flow cytometry.

Main Results:

• Polluted air exposure led to more severe HSK, with increased corneal opacity, neovascularization, and viral DNA.
• Elevated pro-inflammatory cytokines and a significant influx of immune cells (neutrophils, monocytes, dendritic cells, T cells) were observed in the cornea.
• A shift towards a Th1 immune response over regulatory T cells (Tregs) in lymph nodes, with decreased corneal Tregs, was noted.

Conclusions:

• Urban air pollution exacerbates HSK severity by disrupting local immune responses.
• Air pollution acts as a key factor in the development and progression of ocular inflammatory diseases.