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Tomoko Sato, Koji Sugioka, Hiroshi Mishima, Shunji Kusaka, Teruo Nishida; The mechanism of phagocytosis induced by plasminogen on cultured corneal fibroblasts. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4671. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Plasminogen is a zymogen of plasmin that is synthesized by the liver and circulates in the blood. Plasminogen is known to be expressed in the corneal stroma following corneal injury and interacts with corneal fibroblasts during the wound healing process. In this study, we examined the effect of plasminogen on phagocytic activity of corneal fibroblasts. We also examined the signal transduction involved in the phagocytosis of plasminogen on human corneal fibroblasts (HCFs).
Primary cultured HCFs were isolated from donated eyes (The Eye-Bank for Sight Restoration [New York, NY]). HCFs were incubated for various time periods up to 36 hr in media containing plasminogen and plastic beads labeled with fluorescein isothiocyanate. The phagocytic activity of corneal fibroblasts was measured by flow cytometry. To elucidate the mechanism involved in phagocytosis induced by plasminogen on HCFs, we used 6-Aminohexanoic Acid (EACA) which blocks plasminogen binding to the receptor on the cell surface, nuclear factor-kappa B (NFκB) inhibitor and p-38 mitogen-activated protein kinase (MAPK) inhibitor and measured the phagocytic activity of each substance by flow cytometry.
In flow cytometry analysis, plasminogen significantly promoted phagocytic activity to the utmost level in 24 hr after incubation (2.5 ± 0.5% vs. 10.1 ± 2.8%, P < 0.01). EACA and p-38 MAPK inhibitor inhibited the phagocytic activity of plasminogen (3.1 ± 0.4%, 3.6 ± 0.5%).
It is likely that plasminogen promoted phagocytic activity of corneal fibroblasts. A p-38 MAPK cascade seems to be involved in its mechanism.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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