This study aimed to evaluate the neuroprotective effect of EPO in the presence of N-methyl-d-aspartate (NMDA)-, trophic factor withdrawal (TFW)-, and tumor necrosis factor-alpha (TNF-α)-induced toxicity on total, small, and large retinal ganglion cells (RGCs). Retinal cells from adult rats were cultured in a medium containing brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), basic fibroblast growth factor (bFGF), and forskolin. Expression of RGC markers and EPOR was examined using immunocytochemistry. RGCs were classified according to their morphological properties. Cytotoxicity was induced by NMDA, TFW, or TNF-α. RGC survival was assessed by counting thy-1 and neurofilament-l double-positive cells. EPO offered dose-dependent (EC₅₀ = 5.7 ng/mL) protection against NMDA toxicity for small RGCs; protection was not significant for large RGCs. Time-course analysis showed that the presence of EPO either before or after NMDA exposure gave effective protection. For both small and large RGCs undergoing trophic factor withdrawal, EPO at concentrations of 1, 10, or 100 ng/mL improved survival. However, EPO had to be administered soon after the onset of injury to provide effective protection. For TNF-α-induced toxicity, survival of small RGCs was seen only for the highest examined concentration (100 ng/mL) of EPO, whereas large RGCs were protected at concentrations of 1, 10, or 100 ng/mL of EPO. Time-course analysis showed that pretreatment with EPO provided protection only for large RGCs; early post-treatment with EPO protected both small and large RGCs. Inhibitors of signal transduction and activators of transcription such as (STAT)-5, mitogen-activated protein kinases (MAPK)/extracellular-regulated kinase (ERK), and phosphatidyl inositol-3 kinase (PI3K)/Akt impaired the protective effect of EPO on RGCs exposed to different insults. EPO provided neuroprotection to cultured adult rat RGCs; however, the degree of protection varied with the type of toxic insult, RGC subtype, and timing of EPO treatment.

Age-related macular degeneration (AMD) is a vision-threatening age-associated disease. The retinal pigment epithelial (RPE) cells phagocytose and digest photoreceptor outer segment (POS). Incomplete digestion of POS leads to lipofuscin accumulation, which contributes to the pathology of the AMD. Autophagy could help reduce the amount of lipofuscin accumulation. In the present study, we evaluated the effects of glucosamine (GlcN), a natural supplement, on the induction of autophagy and POS-derived lipofuscin-like autofluorescence (LLAF) in ARPE-19 cells in vitro, and investigated the potential molecular pathway involved. Our results revealed that GlcN had no effect on phagocytosis of POS at the lower doses. GlcN treatment induced autophagy in cells. GlcN decreased the LLAF in native POS-treated cells, whereas malondialdehyde or 4-hydroxynonenal-modified POS attenuated this effect. 3-Methyladenine inhibited GlcN-induced autophagy and attenuated the effect of GlcN on the decrease of the native POS-derived LLAF. Furthermore, GlcN induced the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR), whereas Compound C inhibited these effects of GlcN. Altogether, these results suggest that GlcN decreased the native POS-derived LLAF through induction of autophagy, at least in part, by the AMPK–mTOR pathway. This mechanism has potential for the preventive treatment of lipofuscin-related retinal degeneration such as AMD.

Peer reviewed article authored by (Chen C, Yeh M, Shiau C, Chiang C, Lu D). Read article or submit your manuscript for publishing.

Purpose: The purpose of this study was to investigate the IOP-lowering effects of the ITRI-E-212, a new Rho-associated protein kinase (ROCK) inhibitor. ITRI-E-212 improved fluid outflow through the trabecular meshwork and reduced IOP with transient and mild conjunctival hyperemia. ITRI-E-212 can potentially be developed into new antiglaucoma agents. Methods: ITRI-E-212 was selected from more than 200 amino-isoquinoline structures because of its adequate solubility and drug-loading percentage in eye drops. ITRI-E-212 has less than 50% inhibitory concentration (IC₅₀) against ROCK2. The in vitro kinase inhibition was evaluated using the ADP-Glo kinase assay. A comprehensive analysis of the kinase inhibitor selectivity of ITRI-E-212 was performed using the KINOMEscan methodology. The IOP-lowering effect and tolerability of ITRI-E-212 were investigated in normotensive and ocular hypertensive rabbits. The pharmacokinetics study was performed in vivo in the aqueous humor (AH), and hyperemia was assessed. Results: ITRI-E-212 showed high in vitro inhibitory activity against ROCK2 and high specificity against AGC kinases. The mean IOP-lowering effect of ITRI-E-212 in normotensive and ocular hypertensive models was 24.9% and 28.6%, respectively; 1% ITRI-E-212 produced notable reductions in IOP that were sustained for at least 6 hours after each dose once per day. Only transient, mild hyperemia was observed. The compound extracted from the AH reached 78.4% ROCK2 kinase inhibition at 1 hour after dose administration and was sustained for 4 hours. Conclusions: ITRI-E-212 is a novel and highly specific ROCK2 inhibitor with the ability to lower IOP in animal models. It has favorable pharmacokinetic and ocular tolerability profiles with only minimal conjunctival hyperemia.

Purpose To analyze the results of trabeculectomy in patients with primary angle-closure glaucoma. Methods A retrospective and noncomparative case series analysis was performed on data from Taiwan, from 2001 to 2004. The outcomes of trabeculectomy in eyes with acute primary angle-closure glaucoma attack (AACG) and those with chronic primary angle-closure glaucoma (CACG) were assessed in terms of final intraocular pressure (IOP), changes to visual acuity, and the incidence of complications. Results A total of 52 eyes of 52 patients, 15 patients in AACG group and 37 patients in CACG group, were reviewed. The mean follow-up period was 32 months (range, 26-42 mo). In terms of no visual acuity change after surgery, there were significant differences between the CACG and AACG groups (P=0.02, Fisher exact test). In terms of final IOP control, trabeculectomy outcome was significantly worse in patients in the AACG group than those in the CACG group (P<0.01, Fisher exact test). Moreover, the complication of bleb encapsulation appeared more frequently in the AACG group than in the CACG group (P=0.02, Fisher exact test). Conclusions Compared with CACG, trabeculectomy may not be as good for patients of AACG, because it may lead to worsened visual acuity; it also seems to present a greater failure rate, more complications, and fewer cases of surgical survival.

The changes of vitreous pH values under acute glaucoma status have never been reported. In this study, we measured the changes of vitreous pH values in an acute glaucoma rabbit model. Under ketamine and xylazine anesthesia, the anterior chamber of the right eye of New Zealand white rabbits was cannulated and connected to a polygraph for continuous intraocular pressure (IOP) monitoring and a mini-pump for persistent injection of viscoelastic substance, Healon GV. The measurement of vitreous pH was done by inserting a pH probe via a third opening through the sclera into the vitreous. Different IOP levels were maintained by varied amounts of Healon GV injections into the anterior chamber. The changes of vitreous pH values following the intracameral injections were recorded and evaluated. The changes of vitreous pH values were minimal when IOPs were maintained at lower than 35 mmHg. Vitreous pH values decreased significantly from 7.32 to less than 7.03, when the IOPs were kept at 70 mmHg or higher. However, the decrease of pH values was reversible if IOP was held at 70 mmHg for less than 10 minutes and then reduced to normal level at once. In addition, with MTT viability assay, it was noted that the decrease in vitreous pH was associated with a higher percentage of retinal cell death.