Acute and continuous exposure of airborne fine particulate matter (PM2.5): diverse outer blood–retinal barrier damages and disease susceptibilities

The association between air pollution and retinal diseases such as age-related macular degeneration (AMD) has been demonstrated, but the pathogenic correlation is unknown. Damage to the outer blood–retinal barrier (oBRB), which consists of the retinal pigment epithelium (RPE) and choriocapillaris, is crucial in the development of fundus diseases. To describe the effects of airborne fine particulate matter (PM2.5) on the oBRB and disease susceptibilities. A PM2.5-exposed mice model was established through the administration of eye drops containing PM2.5. Optical coherence tomography angiography, transmission electron microscope, RPE immunofluorescence staining and Western blotting were applied to study the oBRB changes. A co-culture model of ARPE-19 cells with stretching vascular endothelial cells was established to identify the role of choroidal vasodilatation in PM2.5-associated RPE damage. Acute exposure to PM2.5 resulted in choroidal vasodilatation, RPE tight junctions impairment, and ultimately an increased risk of retinal edema in mice. These manifestations are very similar to the pachychoroid disease represented by central serous chorioretinopathy (CSC). After continuous PM2.5 exposure, the damage to the RPE was gradually repaired, but AMD-related early retinal degenerative changes appeared under continuous choroidal inflammation. This study reveals oBRB pathological changes under different exposure durations, providing a valuable reference for the prevention of PM2.5-related fundus diseases and public health policy formulation.