Cyclo-oxygenase-2 expression in human idiopathic epiretinal membrane

The Effect of S-Allyl L-Cysteine on Retinal Ischemia: The Contributions of MCP-1 and PKM2 in the Underlying Medicinal Properties

Retinal ischemia plays a vital role in vision-threatening retinal ischemic disorders, such as diabetic retinopathy, age-related macular degeneration, glaucoma, etc. The aim of this study was to investigate the effects of S-allyl L-cysteine (SAC) and its associated therapeutic mechanism. Oxidative stress was induced by administration of 500 μM H2O2 for 24 h; SAC demonstrated a dose-dependent neuroprotective effect with significant cell viability effects at 100 μM, and it concurrently downregulated angiogenesis factor PKM2 and inflammatory biomarker MCP-1. In a Wistar rat model of high intraocular pressure (HIOP)-induced retinal ischemia and reperfusion (I/R), post-administration of 100 μM SAC counteracted the ischemic-associated reduction of ERG b-wave amplitude and fluorogold-labeled RGC reduction. This study supports that SAC could protect against retinal ischemia through its anti-oxidative, anti-angiogenic, anti-inflammatory, and neuroprotective properties.

MicroRNA-494 augments fibrotic transformation of human retinal pigment epithelial cells and targets p27 with cell-type specificity

Epiretinal membranes (ERMs) are the result of fibro-cellular proliferation that cause distortion and impairment of central vision. We hypothesized that select microRNAs (miRs) regulate retinal fibro-proliferation and ERM formation. Following IRB approval, a pilot study was performed in patients presenting for retina surgery with and without clinical ERMs. Total RNA was isolated from ERM tissue and controls from non-ERM vitreous and subjected to miR profiling via microarray analysis. MiR-494 was identified as the only miR selectively expressed at significantly greater levels, and in silico analysis identified p27 as a putative fibroproliferative gene target of miR-494. In vitro testing of miR-494 and p27 in fibrotic transformation was assessed in spontaneously immortalized human retinal pigment epithelial (RPE) and human Müller cell lines, stimulated to transform into a fibroproliferative state via transforming growth factor beta (TGFβ). Fibroproliferative transformation was characterized by de novo cellular expression of alpha smooth muscle actin (αSMA). In both RPE and Müller cells, both TGFβ and miR-494 mimic decreased p27 expression. In parallel experiments, transfection with p27 siRNA augmented TGFβ-induced αSMA expression, while only in RPE cells did co-transfection with miR-494 inhibitor decrease αSMA levels. These results demonstrate that miR-494 augments fibrotic transformation in both Müller cells and RPEs, however only in RPEs does miR-494 mediate fibrotic transformation via p27. As p27 is known to regulate cellular proliferation and differentiation, future studies should extend clinical testing of miR-494 and/or p27 as a potential novel non-surgical therapy for ERMs, as well as identify relevant miR-494 targets in Müller cells.

Clinical and histological evaluation of large macular hole surgery using the inverted internal limiting membrane flap technique

PURPOSE

The aims of this study were to analyze optical coherence tomography (OCT) imaging of large macular holes (MHs) treated with inverted internal limiting membrane (ILM) flap technique and to perform a histological examination of an ILM-like membrane tissue obtained during vitrectomy.

PATIENTS AND METHODS

This is a retrospective observational case study. Nine patients, comprising of five males and four females, showing large and myopic MHs, underwent pars plana vitrectomy (PPV) with inverted ILM flap technique assisted by brilliant blue G (BBG) staining. Ophthalmological findings including visual acuity and OCT were investigated based on medical records. Formalin-fixed paraffin-embedded tissue section of an ILM-like membrane was submitted for immunohistochemistry with glial fibrillary acidic protein (GFAP).

RESULTS

ILM was clearly stained with BBG in eight patients, whereas the ILM in one case revealed no staining with BBG during PPV. Visual acuities improved to >0.2 LogMAR in six patients. The complete closure of MH following PPV with inverted ILM technique was eventually achieved in all patients determined by OCT imaging (100%). Only one patient showed recovery of ellipsoid zone and interdigitation zone following the surgery. Elongation of outer nuclear layer was noted in three eyes. The ILM-like membrane not stained with BBG histologically revealed an amorphous structure admixed with GFAP-positive mononuclear cell infiltration.

CONCLUSION

PPV with inverted ILM flap technique achieved 100% closure rates with favorable configuration at an initial surgery in large MHs. Our histopathological data also suggest that even BBG staining-negative membrane may be a useful material for autologous transplantation to the hole.