Proteome changes induced by laser in diabetic retinopathy.

BACKGROUND: Diabetic macular oedema (DMO) is the commonest cause of vision loss in people with diabetes. Laser photocoagulation can be effective in the treatment of DMO; however, its mechanism of action is still poorly understood. A better understanding of these mechanisms may allow the development of therapeutic approaches that could avoid the deleterious adverse events associated with photocoagulation. METHODS: We have used proteomic techniques to identify the protein changes induced by threshold intensity retinal laser treatment in a rodent model of diabetic retinopathy. Retinae were obtained from diabetic Dark Agouti rats 8 weeks following laser treatment. Extracted proteins from lasered and non-lasered diabetic retinae were separated and compared using two-dimensional gel electrophoresis. RESULTS: Image analysis revealed 24 protein spots with decreased expression after laser treatment and 9 spots with increased expression. On lasered retinal gels, four spots were uniquely expressed, with eight unique spots on non-lasered gels. Twenty-two protein spots of interest were identified using matrix-assisted desorption ionization-mass spectrometry with database matching. Following laser, Wnt-5 beta, LEK-1, GADPH, claudin-12 and calretinin were significantly down-regulated in expression. CONCLUSIONS: The present study provides a proteomic insight into the underlying biological basis for the therapeutic effects of laser for DMO. We provide further evidence of the involvement of Wnt pathway signalling in the neural retina in DMO, and for up to 2 months following laser treatment. Changes in LEK-1 and claudin-12 may have effector roles, and changes in glyceraldehyde-3-phosphate dehydrogenase and calretinin may reflect the altered retinal microenvironment resulting from laser treatment.

A randomized clinical trial of intravitreal bevacizumab versus intravitreal dexamethasone for diabetic macular edema: the BEVORDEX study.

OBJECTIVE: To report the 12-month results of the first head-to-head comparison of a dexamethasone implant (Ozurdex; Allergan, Inc., Irvine, CA) versus bevacizumab (Avastin; Genentech, South San Francisco, CA) for center-involving diabetic macular edema (DME). DESIGN: Phase 2, prospective, multicenter, randomized, single-masked clinical trial (clinicaltrials.gov identifier NCT01298076). PARTICIPANTS: We enrolled 88 eyes of 61 patients with center-involving DME. METHODS: Forty-two eyes were randomized to receive bevacizumab every 4 weeks and 46 eyes were randomized to receive a dexamethasone implant every 16 weeks, both pro re nata. Results were analyzed using linear regression with generalized estimation equation methods to account for between-eye correlation. MAIN OUTCOME MEASURES: The primary outcome was the proportion of eyes that improved vision by 10 logarithm of minimum angle of resolution letters. Secondary outcomes included mean change in best-corrected visual acuity (BCVA), change in central macular thickness (CMT), injection frequency, and adverse events. Patient-reported outcomes were measured using the Impact of Vision Impairment (IVI) questionnaire. RESULTS: Improvement in BCVA of 10 or more letters was found in 17 of 42 eyes (40%) treated with bevacizumab compared with 19 of 46 dexamethasone implant-treated eyes (41%; P = 0.83). None of the 42 bevacizumab eyes lost 10 letters or more, whereas 5 of 46 (11%) dexamethasone implant eyes did, mostly because of cataract. Mean CMT decreased by 122 µm for bevacizumab eyes and by 187 µm for dexamethasone implant eyes (P = 0.015). Bevacizumab-treated eyes received a mean of 8.6 injections compared with 2.7 injections for dexamethasone implant eyes. Significant improvement in IVI scores occurred for both treatment groups. CONCLUSIONS: Dexamethasone implant achieved similar rates of visual acuity improvement compared with bevacizumab for DME, with superior anatomic outcomes and fewer injections. Both treatments were associated with improvement in visual quality-of-life scores. However, more dexamethasone implant-treated eyes lost vision, mainly because of cataract.

Efficacy of dexamethasone versus bevacizumab on regression of hard exudates in diabetic maculopathy: data from the BEVORDEX randomised clinical trial.

OBJECTIVE: To report the effect of bevacizumab versus dexamethasone on hard exudates (HEX) in diabetic macular oedema (DME). DESIGN: Post hoc analysis of 24-month data from the Randomised clinical trial of BEVacizumab OR DEXamethasone for diabetic macular oedema (BEVORDEX) phase 2 multicentre randomised clinical trial. Eyes with centre-involving DME resistant to or unlikely to benefit from macular laser therapy were included. Eyes were randomly assigned to bevacizumab every 4 weeks or Ozurdex dexamethasone implant (DEX) every 16 weeks, both as required. The 68 eyes from 48 patients that completed 24-month follow-up were analysed. Two masked graders assessed extent and location of HEX on baseline, 12-month and 24-month foveal-centred colour fundus photographs using validated grading software. RESULTS: Macular HEX was present in 60% of study eyes. Of these, 21 eyes were treated with DEX and 20 eyes with bevacizumab. Both treatments led to reduction in area of macular HEX at 12 months and 24 months. There was greater regression of HEX from the foveal centre in DEX-treated eyes (median change +890 µm, IQR=1040 µm) than bevacizumab-treated eyes (median change +7.0 µm, IQR=590 µm) at 12 months (p=0.04) but the difference was no longer statistically significant (p=0.10) by 24 months (DEX +1400 µm, IQR=1590 µm; bevacizumab +20 µm, IQR=2680 µm). Reassuringly, no study eye developed HEX at the foveal centre, a visually devastating consequence of diabetic maculopathy. CONCLUSIONS: Bevacizumab and DEX were effective in reducing area of HEX in eyes with DME. DEX provided more rapid regression of HEX from the foveal centre although bevacizumab-treated eyes started to catch up by 24 months. Distance from the foveal centre as well as total area of macular HEX should be assessed when evaluating treatments for foveal-threatening HEX. TRIAL REGISTRATION NUMBER: NCT01298076; Post-results.

Proteome map of normal rat retina and comparison with the proteome of diabetic rat retina: new insight in the pathogenesis of diabetic retinopathy.

We have employed proteomics to establish a proteome map of the normal rat retina. This baseline map was then used for comparison with the early diabetic rat retinal proteome. Diabetic rat retinae were obtained from Dark Agouti rats after 10 wk of streptozotocin-induced hyperglycaemia. Extracted proteins from normal and diabetic rat retinae were separated and compared using 2-DE. A total of 145 protein spots were identified in the normal rat retina using MALDI-MS and database matching. LC-coupled ESI-MS increased the repertoire of identified proteins by 23 from 145 to 168. Comparison with early diabetic rat retinae revealed 24 proteins unique to the diabetic gels, and 37 proteins absent from diabetic gels. Uniquely expressed proteins identified included the HSPs 70.1A and 8, and platelet activating factor. There were eight spots with increased expression and 27 with decreased expression on diabetic gels. Beta catenin, phosducin and aldehyde reductase were increased in expression in diabetes whilst succinyl coA ligase and dihydropyrimidase-related protein were decreased. Identification of such changes in protein expression has given new insights and a more comprehensive understanding of the pathogenesis of diabetic retinopathy, widening the scope of potential avenues for new therapies for this common cause of blindness.