Abstract
Purpose :
Neutrophils are primary immune cells that migrate rapidly into the damaged or infected tissue to remove pathogens and debris and recruit various inflammatory cells. However, excessive neutrophil activity causes host tissue damage and unexpected sequelae. Therefore, controlling neutrophil activity properly in sterile damage can be a way to minimize the sequelae. This study evaluated the effect of leukocyte enzymes inhibitors on corneal opacity following acute inflammation.
Methods :
Corneal inflammation was induced using NaOH 1M in SD rats. As measures of acute inflammation, histologic analysis of neutrophil infiltration, the expression level of neutrophil elastase(NE), myeloperoxidase(MPO), IL-1, !L-6, TNF-alpha were performed at 1, 3, 7 days, and 1 month. To assess the corneal opacity, the gross photograph of the cornea was taken, and the level of alpha-SMA and vimentin were also assessed by ELISA and histology. Mixed solution of NE inhibitor(sivelestat sodium) and MPO inhibitor (benzoic acid hydrazide) was applied topically 4 times per day during 1 week immediately after NaOH application and the parameters of acute inflammation and fibrosis were compared between the treatment group and vehicle(phosphate buffered solution) group. Additionally, the effect of neutrophil enzyme inhibitors on keratocytes co-cultured with neutrophils.
Results :
Neutrophils and NE were highly presented at 1, 3, and 7 days, whereas MPO was not increased at 3 and 7 day. Inflammatory cytokines (IL-1, IL-6, and TNF-alpha) all were significantly increased at 1, 3, 7 days in both treatment and vehicle group. The numerical scale of corneal opacity was significantly smaller in the treatment group, and Histology and ELISA showed that alpha-SMA were less expressed in the treatment group than in the vehicle group. As a supplementary experiment, the NE inhibitor and MPO inhibitor reduced the phenotypic change of keratocytes into fibroblasts when co-cultured with neutrophils.
Conclusions :
NE and MPO inhibitors have the protective effect on the corneal opacity following the sterile inflammation. It suggests that NE and MPO inhibitors act on the corneal stromal cells rather than on neutrophils or inflammatory cells.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.