Maresin1 regulates neutrophil recruitment and IL-10 expression in Aspergillus fumigatus keratitis

Abstract

Purpose: Maresin1, a lipid mediator derived from polyunsaturated fatty acids, has been shown to suppress the inflammatory response in various inflammatory diseases. However, its effects in fungal keratitis are still uncertain. In this study, we investigated the role of maresin1 (MaR1) in Aspergillus fumigatus keratitis of the eye in a mouse model.

Methods: Mouse corneas were infected with A. fumigatus by corneal intrastromal injection. Two hours after infection, maresin1 (5 ng/5 μl) was delivered by subconjunctival injection. Then, topical administration of maresin1 (5 ng/3 μl) was applied to mouse corneas twice a day from day 1 to day 5. The development of FK lesions, the production of chemokines, the production of inflammation cytokines and the levels of p-GSK3β were measured via slit-lamp biomicroscope, quantitative polymerase chain reaction (qRT-PCR) and western blot. The presence of neutrophils in the cornea was detected by immunofluorescence staining and myeloperoxidase. The effect of maresin1 on A. fumigatus stimulated mouse macrophage RAW264.7 cells was assessed via PCR and Western blot.

Results: In our study, administration of maresin1 reduced the severity of fungal keratitis with infiltration of fewer neutrophils and reduced levels of the chemokine CXCL1, while the anti-inflammatory cytokines such as IL-10 were enhanced compared with the PBS group. Additionally, in vitro studies showed that treatment with maresin1 inhibited the production of the chemokine CXCL1 and enhanced IL-10 levels in A. fumigatus stimulated RAW264.7 mouse macrophages. Moreover, levels of p-GSK3β increased after maresin1 treatment in A. fumigatus stimulated RAW264.7 cells.

Conclusion: Taken together, these findings demonstrate that treatment with maresin1 moderates corneal inflammation through reducing neutrophil recruitment and levels of the chemokine CXCL1 and enhancing the anti-inflammatory cytokine IL-10 in A. fumigatus keratitis. Additionally, maresin1 alters levels of GSK3β phosphorylation to regulate CXCL1 and IL-10 expression in response to A. fumigatus infection. Topical administration of maresin1 may emerge as a novel anti-inflammatory molecule and has a protective role in A. fumigatus keratitis.

Keywords: Aspergillus fumigatus; Cytokines; Fungal keratitis; Inflammatory cells; Maresin1.