Abstract
Purpose :
Lipocalin-2 (LCN-2) is a pleiotropic mediator of various inflammatory processes. The role of LCN-2 in the eyes remains unclear. In this study, we investigated the expression and function LCN-2 in an experimental model of Pseudomonas aeruginosa (PA) corneal infection.
Methods :
8 weeks wild type C57BL/6 (B6) and LCN-2 knockout (KO) female mice were used in all experiments. Mouse corneas were scratched with a sterile 25-gauge needle to create three 1mm incisions, then inoculated with 1.0×104 CFU of PA (ATCC 19660) to build the infection model. The expression of LCN-2 in mouse corneas was determined by PCR and Western blot (N=4). The Effects of LCN-2 on the severity of PA keratitis were assessed using clinical scoring, bacterial counting, and MPO (N=6). LCN-2-related gene changes were evaluated by qPCR, Western blot, and ELISA (N=4). The role of LCN-2 on innate and adaptive immune cell infiltration in PA keratitis was assessed by immunofluorescence staining and flow cytometry (N=4). One way-ANOVA and Student’s t test were used for statistical analysis.
Results :
PA infection induced the expression of LCN-2 in mouse corneas. LCN-2 KO mice had significantly more severe keratitis, including increased clinical score, bacterial burden, and neutrophil infiltration. LCN-2 depletion significantly increased the expression of the pro-inflammatory cytokine IL-1β,TNF-α, and decreased the expression of anti-bacterial cytokine CXCL-10, bactericidal protein BD-3 in the corneal epithelium. LCN-2 depletion also suppressed the expression of IL-17C,IL-6 and CCL-20 in the corneal epithelium. LCN-2 increased macrophage infiltration in the cornea at the early stage, and promoted Th1 and Th2 cell responses in the late stage of PA infection.
Conclusions :
LCN-2 plays a protective role in the pathogenesis of PA keratitis. LCN-2 enhances corneal host defense by altering inflammatory gene expression and modulating immune cell function. LCN-2 may serve as a therapeutic reagent for controlling the outcome of P. aeruginosa.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.