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Published on: September 27, 2016
Hyaluronan protection of corneal endothelial cells against extracellular histones after phacoemulsification
Hiroki Kawano1, Taiji Sakamoto1, Takashi Ito1
1From the Department of Ophthalmology (Kawano, Sakamoto), the Department of Laboratory and Vascular Medicine (Hashiguchi), and the Department of Systems Biology in Thromboregulation (Ito, Maruyama), Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, and Miyata Eye Hospitals (Miyata), Miyakonojyo, Japan.
Purpose:
To determine the effect of histones on corneal endothelial cells generated during cataract surgery.
Setting:
Kagoshima University Hospital, Kagoshima, Japan.
Design:
Experimental study.
Methods:
Standard phacoemulsification was performed on enucleated pig eyes. Histones in the anterior segment of the eye were determined by immunohistochemistry. Cultured human corneal endothelial cells were exposed to histones for 18 hours, and cell viability was determined by 2-(2-methoxy-4-nitrophenyl)-3-(4-nitro-phenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt assay. The concentration of interleukin-6 (IL-6) in the culture medium of human corneal endothelial cells was measured using enzyme-linked immunosorbent assay. The effects of signal inhibitors U0126, SB203580, and SP600125 were evaluated. The protective effect of hyaluronan against histones was evaluated in human corneal endothelial cells with and without hyaluronan.
Results:
Cellular debris containing histones was observed in the anterior chamber of pig eyes after phacoemulsification. Exposure of human corneal endothelial cells to 50 μg/mL of histones or more led to cytotoxic effects. The IL-6 concentration was significantly increased dose dependently after exposure of human corneal endothelial cells to histones (P<.01). The histone-induced IL-6 production was significantly decreased by extracellular signal-regulated kinases 1/2 and p-38 mitogen-activated protein kinase inhibitors (P<.01). Co-incubation of hyaluronan and histones caused formation of histone aggregates, decreased the cytotoxic effects of the histones, and blocked the increase in IL-6 (P<.01).
Conclusions:
Histones were released extracellularly during phacoemulsification and exposure of human corneal endothelial cells to histones increased the IL-6 secretion. The intraoperative use of hyaluronan may decrease the cytotoxic effects of histones released during cataract surgery.
Financial Disclosure:
No author has a financial or proprietary interest in any material or method mentioned.
