Increased human scleral permeability with prostaglandin exposure

PURPOSE. To investigate the effect of prostaglandins (PGs) on the permeabil ity of human sclera in vitro. METHODS. Twenty-three pairs of human eye bank eyes were studied. Circular p ieces of sclera were cultured in low-serum DMEM/F-12 media. Scleral hydrati on was assessed by measuring wet and dry weight of scleral cultures incubat ed with medium for 3 days and with Hanks' buffered saline solution (HBSS) f or 4 hours. To assess scleral permeability, organ-cultured scleral tissues were exposed to 100 to 500 nM PGF(2 alpha), 17-phenyltrinor PGF(2 alpha), o r PhXA85 (the active form of latanoprost) for 1, 2, and 3 daps. Scleral per meability was measured using a two-chamber Ussing apparatus and rhodamine-d extran polymers dissolved in HBSS (MW = 10,000, 40,000, and 70,000). The mo vement of each rhodamine-dextran across the cultured sclera was measured us ing a spectrofluorometer. To understand the biological basis of the permeab ility change, the media were collected from the treated cultures, and the c oncentration of MMP-1, 2, and 3 was measured using an enzyme linked immunos orbent assay. RESULTS. There was no difference in scleral hydration among fresh sclera an d sclera incubated with medium for 3 days, with HBSS for 4 hours, or with m edium for 3 days followed by HBSS for 4 hours. Compared to tracer movement across untreated scleral cultures (1.5 x 10(-6) cm/sec for 10 kDa dextran, 0.7 X 10(-6) cm/sec for 40 kDa dextran, and 0.4 x 10(-6) cm/sec for 70 kDa dextran), exposure to PGF(2 alpha), 17-phenyltrinor PGF(2 alpha), Or PhXA85 each increased scleral permeability in a dose- and time-dependent manner. Increases in permeability were greater with the 10 kDa dextran than with th e 40 or 70 kDa dextran. The magnitude of these effects was greatest with ex posure to PhXA85 and similar with exposure to PGF(2 alpha), or 17-phenyltri nor-PGF(2 alpha). MMP expression also was significantly increased after PG exposure. These increases were generally time and dose dependent and greate r with MMP-2 and -3 than with MMP-1. CONCLUSIONS. There is increased permea bility of human sclera exposed to various PGs in organ culture. This increa sed permeability is accompanied by increased expression of MMPs.