Abstract
Abstract: :
Purpose: During Bacillus endophthalmitis, an explosive rapid influx of inflammatory cells into the posterior segment may contribute to bystander retinal damage that ultimately results in retinal function loss. The purpose of this study is to identify the inflammatory cell types infiltrating into the eye and analyze the evolution of inflammation throughout the course of infection during Bacillus Endophthalmitis. Methods: C57BL/6J mice were infected intravitreally with 100 CFU of Bacillus cereus. Cell infiltration into the posterior segment was analyzed at 0, 2, 4, 6, 8, 10, and 12 hours postinfection by flow cytometry, using cell–specific markers for analysis, including polymorphonuclar leukocytes (Gr–1, CD18), monocyte/macrophages (F4/80, Moma–2), and dendritic cells (CD13/APN, I–A). Further analysis of infiltrating cells during analysis included myeloperoxidase assays, immunofluorescence staining of histology sections, and retinal wholemount immunostaining of retinal vasculature and specific infiltrating cell types of interest. Results: Flow cytometric and immunofluorescence analysis revealed that the majority of infiltrating inflammatory cells during experimental Bacillus endophthalmitis were Gr–1+, CD18+ polymorphonuclear leukocytes (PMN). Myeloperioxidase assays activities of infected eyes increased significantly with time, further confirmed confirming this observation. Retinal wholemount analysis showed the occlusion of retinal vasculature by the infiltrating inflammatory cells, leading to breakdown of the vasculature and leakage of these cells into the vitreous. Conclusions: The majority of infiltrating inflammatory cells during Bacillus endophthalmitis were PMN that occluded retinal vessels, reaching the vitreous during the early stages of infection. Further analysis will focus on the triggers for PMN infiltration into the eye during Bacillus endophthalmitis, the extent of bystander damage to the retina from these cells, and improved therapeutic regimens designed to block the migration of inflammatory cells during Bacillus endophthalmitis.
Keywords: endophthalmitis • bacterial disease • retina