Abstract
Purpose :
Keratocytes are neural crest-derived fibroblast cells in corneal stroma. Keratocytes are normally quiescent, but they can readily respond following injury. As the major neighbor cell to the corneal endothelium, we aim to evaluate NLRP3 inflammasome in keratocyte to illustrate the keratocyte fibrosis and possible inflammatory pathogenesis in endothelial keratopathy.
Methods :
We created a corneal endothelial dysfunction model in New Zealand White rabbits (1.5-2 kg) by scraping corneal endothelial cells about 9 mm in diameter. Slit-lamp examination, anterior segment optical coherence tomography measuring central corneal thickness (CCT), confocal microscopy, transcript expressions of NLRP3 inflammasome pathway molecules and immunohistochemistry (IHC) evaluation were performed before endothelial scraping and at 1, 3, 7, 14, 30 and 60 days after the surgery.
Results :
All the corneas were opaque and moderately to severely edematous at day 1 (normal 379 (mean)±10.56 (SE) µm vs 1209±49.81 µm, p<0.0001) and at day 3 (normal 392±9.17 µm vs 751.9±129.6 µm, p=0.0003); but regained transparency and normal thickness since day 7 (normal 391±9.63 µm vs 367.5±21.88 µm, p=0.53). In the posterior portion of corneal stroma, confocal microscopy detected many highly reflective activated keratocytes in a multiple dendritic cell-like shape with multiple long extensions. These activated keratocytes returned to their original quiescent form at 30-60 days after surgery, showing small nuclei without processes. At the same period, the endothelial cells are fully regenerated, but had lower endothelial cell counts at 60 days (normal 2491±108.6 cells/mm2 vs 1699±123.47 cells/mm2, p<0.0001). Interleukin-1 beta (Il1β), Il18, Nlrp3 transcripts were upregulated in activated keratocytes vs quiescent ones (all p values<0.05). Upregulated expressions of Caspase-1 p10, NLRP3 proteins were noted in activated keratocytes vs controls.
Conclusions :
Our study showed keratocytes activation with upregulated NLRP3 pathway in a rabbit model of endothelial keratopathy. Proinflammatory cytokines may contribute to keratocyte activation and fibrosis, which in turn influences corneal homeostasis via inflammatory pathway in endothelial keratopathy.
This is a 2020 ARVO Annual Meeting abstract.