The Role of Eosinophils in Modulating the Corneal Response to Infection

Project Summary/Abstract Objective/Hypothesis: Pseudomonas aeruginosa is an opportunistic bacterium known to induce microbial keratitis and is associated with rapid corneal destruction and blindness, especially in individuals who wear contact lenses or are immunocompromised. Microbial keratitis triggers a robust inflammatory response driven by the influx of innate immune cells. During infection, neutrophils (PMNs) and macrophages (Mϕ) are recruited in the acute phase of inflammation to effectively remove the pathogen. However, their persistence and chronicity can lead to extensive tissue destruction, including corneal opacity, stromal fibrosis, and ulceration, if not properly treated. Eosinophils are another type of innate immune cell known to secrete cytokines, chemokines, and growth factors. Although their contribution to microbial keratitis has not yet been explored, an emerging body of literature suggests that eosinophils not only possess antibacterial properties but contribute to tissue remodeling and inflammation resolution. The overarching objective of this proposal is to characterize the role of eosinophils in modulating the corneal response to Pseudomonas aeruginosa-induced infection. Specific Aims: Experiments proposed in Aim 1 will characterize the spatiotemporal distribution of eosinophils in normal and infected corneas. Aim 2 will define the phenotypic profiles of eosinophils during infection. Aim 3 will comparatively analyze proteomic profiles during corneal infection. Study Design: To investigate the role of eosinophils during corneal inflammation and infection, we will use established mouse models of P. aeruginosa-induced keratitis with two disease outcomes: susceptible C57BL/6 (B6) mice that exhibit corneal perforation and resistant BALB/c mice that heal over time. We will largely utilize a combination of microscopy, immunostaining, flow cytometry, proteomics, and eosinophil depletion to comprehensively achieve the three stated aims. Impact: The proposed work is expected to elucidate the currently undefined role of the eosinophil within the corneal microenvironment, filling a current gap in knowledge regarding eosinophil biology in the eye. Therapeutically, the eosinophil may serve as an effective cellular target to help improve disease outcomes.