β-Catenin promotes host resistance against Pseudomonas aeruginosa keratitis

Objective: To explore the role of beta-catenin in Pseudomonas aeruginosa (PA) keratitis. Methods: Western-blot and immunostaining assay were used to determine the beta-catenin protein expression in C57BL/6 (B6) corneas and in in vitro cultured murine cells including macrophage-like RAW264.7 cells, bone marrow-derived neutrophils and A6(1) corneal epithelial cells. B6 mice were subconjunctivally injected with lentivirus expressing active mutant of beta-catenin (beta-cat-lentivirus) vs appropriate control (Ctl-lentivirus), and then infected with PA. Pro-inflammatory cytokine levels were examined using real-time PCR and ELISA, and bacterial burden was assessed using plate count assays both in vivo and in vitro. Results: beta-Catenin protein expression was decreased in B6 corneas, murine macrophage-like RAW264.7 cells, mouse bone marrow-derived neutrophils and mouse A6(1) corneal epithelial cells after PA infection. Over-expression of beta-catenin in B6 corneas significantly reduced the severity of corneal disease after PA infection, by decreasing pro-inflammatory cytokine expression and bacterial burden. In vitro data further demonstrated that over-expression of beta-catenin suppressed pro-inflammatory cytokine production but enhanced bacterial clearance in macrophages and neutrophils. Conclusions: beta-Catenin reduces the severity of PA keratitis by decreasing corneal inflammation and bacterial burden.(C) 2013 The British Infection Association. Published by Elsevier Ltd. All rights reserved.