Involvement of corneal lymphangiogenesis and macrophages in a murine bacterial keratitis model.

Abstract

Purpose :
To evaluate corneal lymphangiogenesis and involvement of tissue-resident and monocyte-derived macrophages in a bacterial keratitis model in mice using Pseudomonas aeruginosa.

Methods :
The mouse bacterial keratitis model was established using Pseudomonas aeruginosa strain PAO-1 and C57BL/6 mice. Strain PAO-1 (1×10⁵ CFU/2.5ul) were applied in the infected group and PBS was applied in the control group after corneal epithelium was scratched. Lymphangiogenesis, angiogenesis, and macrophage infiltration were evaluated by immunostaining using whole-mount cornea at days 2, 7 and 14 post-inoculation. Anti-CD31 antibody, anti-LYVE-1 antibody, anti-CD11b antibody and anti-F4/80 antibody were used for immunostaining. Alteration of lymphangiogenesis by macrophage depletion was also evaluated intraperitoneal injection of clodronate-containing liposomes. Tissue-resident macrophages were depleted by sub-conjunctival injection and eye drop. Conversely, monocyte-derived macrophages were depleted by intraperitoneal injection.

Results :
Lymphangiogenesis and angiogenesis increased significantly in infected group at days 7 and 14 post-inoculation of PAO-1. A significant number of macrophages were observed around the lymphatic vessels in infected group. Lymphatic vessel formation was significantly reduced by monocyte-derived macrophage depletion, but not reduced by tissue-resident macrophage depletion in infected group.

Conclusions :
These results suggest that the process of lymphangiogenesis in bacterial infection of the cornea occurs at the late stage of infection presumably induced by local infiltration of monocyte-derived macrophages.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.