Abstract
Purpose :
Meibomian gland dysfunction (MGD) is a leading cause of evaporative dry eye disease, yet the role of inflammation in MGD pathogenesis remains unresolved. The allergic eye disease (AED) mouse model develops MGD in an immune-dependent manner that relies on neutrophils. However, the precise manner by which neutrophils cause MGD is incompletely understood. The current study investigated the spatial distribution of neutrophils in the eyelid via immunofluorescence microscopy to help provide insights into the mechanism of pathogenesis of MGD in the AED model.
Methods :
The AED model was generated in female C57Bl/6 mice at 8-12 weeks of age through immunization against ovalbumin (OVA) in the presence of pertussis toxin. After a two-week incubation period, OVA was administered to the eyes daily for one week prior to lid collection. Age- and sex-matched naïve and AED lids were resected then fixed in a 4% paraformaldehyde before being embedded in OCT and frozen. Cryopreserved lids were subsequently cut into 12 µm sections and immunolabelled for leukocytes (CD45+) or neutrophils (Ly6G+) before being imaged. Images were analyzed using ImageJ and cell localization was compared between naïve and AED lids.
Results :
In AED, we observed leukocyte infiltration into the tarsal plate, which was similarly reflected in the periglandular localization of neutrophils. However, these neutrophils and other leukocytes were largely excluded from the intraglandular region, though several exceptions were noted, including some instances of neutrophil aggregate formation near, or involving, acini in AED mice.
Conclusions :
Due to the periglandular localization of neutrophils, albeit apparent exclusion from the intraglandular spaces in the AED mouse model, it is possible that neutrophil activity impacts deeper regions within the tarsal plate more generally, with less reliance on inducing orifice obstruction than has been previously hypothesized. Future work characterizing changes to meibocyte phenotype near infiltrating neutrophils may help with the elucidation of the role of tarsal plate infiltrating neutrophils.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.