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Sofya Gindina, Arturo Osvaldo Barron Arrambide, Yan Hu, John Danias; Tissue plasminogen activator (tPA) rescues steroid-induced outflow facility reduction via non-enzymatic action. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1435.
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Tissue plasminogen activator (tPA) has been shown to prevent steroid-induced reduction in aqueous humor outflow facility (OF) (Kumar et al., 2013); however its mechanism of action at the trabecular meshwork (TM) remains unclear. Catalytic and non-catalytic domains allow tPA to function as both an enzyme and cytokine. The purpose of this study was to determine whether cytokine activity is sufficient to rescue OF following steroid exposure.
8-12 week old, female C57Bl/6 mice received bilateral injections of triamcinolone acetonide (TA; 20µl of 40mg/ml) subconjunctivally, or were left untreated (naive controls). One cohort of steroid treated animals received simultaneous intracameral adenovirus (AdV) injections. Intracameral injections (2µl) of AdV contained either a sheep PLAT cDNA transgene (AdPLAT) or a mutated sheep non-enzymatic PLAT cDNA transgene (AdPLATNE). Control eyes received either balanced salt solution (BSS) or AdV lacking a transgene (AdNULL). A second cohort received intravitreal protein injections 5 days after the steroid injection. Intravitreal protein injections (2µl, 5µg/µl in BSS) consisted of either native human tPA or mutant non-enzymatic human tPA (NE-tPA). Control eyes received bovine serum albumin (BSA). 7 days after steroid exposure, OF was measured in enucleated eyes using a constant pressure perfusion system. OF was compared between groups using ANOVA with Tukey Kramer post-hoc testing.
OF (mean±standard deviation µl/min/mmHg) was significantly reduced in steroid (TA) exposed eyes receiving BSA (0.000678±0.000258), BSS(0.0007±0.000263) or AdNULL(0.000636±0.000338) compared to eyes that had not been exposed to steroids (0.00117±0.000283). OF of steroid treated eyes was rescued to baseline levels in AdPLAT (0.001009±0.000187) or AdPLATNE (0.001013±0.00028) treated eyes. (p=0.00005, ANOVA, Tukey Kramer post-hoc test). OF of steroid treated eyes was also rescued to baseline levels with tPA (0.001053±0.000358) or NE-tPA (0.00122±0.000569) protein treatment. (p=0.00076, ANOVA, Tukey Kramer post-hoc test).
Enzymatically-inactive tPA is sufficient to rescue steroid-induced OF reduction in mice.
This is a 2020 ARVO Annual Meeting abstract.
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