Resveratrol prevents hypoxia-induced retinal ganglion cell death related with ErbB2

AIM: To confirm the changes in proteins related with hypoxia-induced retinal cell death and to assess the effects of resveratrol(Res).METHODS: The therapeutic effect of Res was verified using an ischemic/reperfusion(I/R) model in vivo and a hypoxia modelin retinal ganglion cells(RGCs) in vitro.Death of RGCs were confirmed by TUNEL assay.Protein expression was confirmed by Western blotting and immunohistochemistry.In addition, flow cytometric analysis was used to confirm the response in the cell unit to obtain more accurate data.RESULTS: ErbB2 expression and apoptosis in the ganglion cell layer(GCL) increased after I/R injury.Treatment of Res rescued I/R-induced ganglion cell death, downregulated apoptosis and ErbB2 protein expression in the retina.In subsequent in vitro models, Res affects apoptosis by regulating the phosphorylation and expression of mouse double minute 2 homolog(MDM2), along with those of ErbB2.These results suggest that Res reverses GCL-specific apoptosis via downregulation of ErbB2 in ischemic injury.CONCLUSION: In light of Res favorable properties, it should be evaluated in the treatment of RGC death and related retinal disease characterized by ErbB2 and MDM2 expression.Therefore, Res is appropriate therapeutic agent for treating ischemic injury-related eye diseases by targeting the expression of ErbB2 and MDM2.

Suppression of laser-induced choroidal neovascularization by intravitreal injection of tristetraprolin

AIM: To examine the effect of intravitreal adenoviral vector-mediated tristetraprolin(Ad-TTP) on VEGF m RNA expression in a rat model of laser-induced choroidal neovascularization.METHODS: Ad-TTP was prepared using a commercial kit. Retinal laser-induced photocoagulation(10 spots per eye) was performed on rats in this experimental choroidal neovascularization(CNV) model. Rats were divided into four groups: control(single intravitreal injection of balanced salt solution, n =10), laser-induced CNV(photocoagulation only, n =20), laser-induced CNV plus Ad-TTP injection(photocoagulation plus a single intravitreal Ad-TTP injection, n =20) and Ad-TTP injection only(n =10). Changes in choroidal morphology were evaluated in ten rats in the laser only and the laser plus Ad-TTP groups. Two weeks after laser injury, the size of CNV was calculated by perfusion with high-molecular-weight fluorescein isothiocyanate(FITC)-dextran. VEGF m RNA expression in retina-choroid tissue from ten rats in each group was measured by reverse transcription polymerase chain reaction(RT-PCR). RESULTS: Two weeks after treatment, the area of laser-induced CNV was reduced by approximately 60% in the rats given the Ad-TTP injection compared with that in the laser-only group. There was a tendency toward decreased VEGF m RNA expression in the Ad-TTP injection groups.CONCLUSION: A single intravitreal injection of Ad-TTP significantly suppressed CNV size in this experimental laser-induced CNV model. Ad-TTP injection also decreased VEGF m RNA expression compared with that inthe laser-induced CNV group. The present study is meaningful as the first study to investigate the effect of tristetraprolin delivered via intravitreal injection.

The ocular toxicity and pharmacokinetics of simvastatin following intravitreal injection in mice

AIM: To investigate the retinal toxicity and pharmacokinetics of simvastatin intravitreally injected into mice. METHODS: Forty-eight 6-8-week-old C57BL/6J mice were used in this study. Simvastatin was intravitreally injected into the right eye of each mouse; the left eye was injected with vehicle and was used as a control. Bilateral dark-adapted electroretinography(ERG) was performed 1 and 7d following injection. Histology was examined using a combination of light, fluorescence and electron microscopy. Highperformance liquid chromatography(HPLC) was used to determine the decay in the retinal simvastatin concentration.RESULTS: ERG revealed no significant changes in the simvastatin-injected eyes compared to control. Histologic studies showed normal retinal morphology in eyes injected with simvastatin up to a final vitreal concentration of 200 μmol/L. No significant changes in the number of photoreceptors, bipolar cells or ganglion cells were found. The retinal simvastatin concentration decayed exponentially, with a half-life of 1.92-2.41 h.CONCLUSION: Intravitreal injection of up to 200 μmol/L simvastatin produced no signs of adverse effects in the mouse retina. Simvastatin reaches the retina shortly after intravitreal injectionand has a short half-life.

Comparison of anterior segment optical coherence tomography findings in acanthamoeba keratitis and herpetic epithelial keratitis

This study is to investigate the characteristic features of Acanthamoeba keratitis(AK) that differentiating it from herpetic epithelial keratitis(HEK) using anterior segment optical coherence tomography(AS-OCT). Medical records of three eyes of each AK and herpetic keratitis who had AS-OCT examination were reviewed in this study. Slitlamp biomicroscopy and AS-OCT was performed on the initial visit and on every follow-up visits in all patients. In all three AK cases, reflective bands in the corneal stroma that correspond to the area of radial keratoneuritis were observed. The depth of the reflective bands varied in each case. After AK treatment, slit-lamp biomicroscopy confirmed that radial keratoneuritis had resolved and AS-OCT confirmed that reflective bands in the corneal stroma had also disappeared in all patients. Unlike the AS-OCT results found in AK, highly reflective HEK lesions were observed only in the subepithelial area, not in the stroma. AS-OCT seems to be helpful analyzing the specific depth of the lesion which enables to distinguish AK from HEK.