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Intravitreal triamcinolone acetonide inhibits breakdown of the blood-retinal barrier through differential regulation of VEGF-A and its receptors in early diabetic rat retinas.

ABSTRACT: OBJECTIVE: To elucidate the mechanism of the unique beneficial effect of intravitreal steroid therapy on diabetic macular edema, we investigated the effect of locally administered triamcinolone acetonide (TA) on the expression of vascular endothelial growth factor (VEGF)-A and its receptors in retinas of rats with streptozotocin (STZ)-induced diabetes. We then correlated the expression of these proteins with breakdown of the blood-retinal barrier (BRB). RESEARCH DESIGN AND METHODS: Thirty-two eyes of 16 diabetic and nondiabetic rats were divided into four groups. TA was injected into the vitreous of the right eye, and saline was injected into the left eye (control) 3.5 weeks after induction of diabetes. Retinas were harvested 48 h following treatment. mRNA and protein expression of VEGF-A, VEGF-A receptor 1 (fms-like tyrosine kinase [FLT]-1), and VEGF-A receptor 2 (fetal liver kinase [FLK]-1) were determined by real-time RT-PCR and immunohistochemistry. BRB permeability was quantitated by measuring extravasated endogenous albumin and retinal thickness. RESULTS: Diabetes-induced retinal thickness and albumin extravasation were significantly reduced in TA-treated diabetic retinas to a level similar to that in sham-treated nondiabetic eyes. A close correlation between albumin leakage and increased expression of both Vegf-a and Flk-1 was noted in the diabetic retinas. TA downregulated the expression of Vegf-a and Flk-1 but upregulated the expression of Flt-1. TA did not alter the expression of these genes in nondiabetic retinas. CONCLUSIONS: Intravitreal injection of TA stabilizes the BRB in association with regulation of Vegf-a, Flk-1, and Flt-1 expression in retinas in the early stages of diabetes.

SUBMITTER: Zhang X

PROVIDER: S-EPMC2836241 | biostudies-literature | 2008 Apr

REPOSITORIES: biostudies-literature

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Intravitreal triamcinolone acetonide inhibits breakdown of the blood-retinal barrier through differential regulation of VEGF-A and its receptors in early diabetic rat retinas.

Zhang Xinyuan X Bao Shisan S Lai Donna D Rapkins Robert W RW Gillies Mark C MC

Diabetes 20080103 4

<h4>Objective</h4>To elucidate the mechanism of the unique beneficial effect of intravitreal steroid therapy on diabetic macular edema, we investigated the effect of locally administered triamcinolone acetonide (TA) on the expression of vascular endothelial growth factor (VEGF)-A and its receptors in retinas of rats with streptozotocin (STZ)-induced diabetes. We then correlated the expression of these proteins with breakdown of the blood-retinal barrier (BRB).<h4>Research design and methods</h4> ...[more]

PMID: 18174522

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Project description:BackgroundThe comparative safety and efficacy of different doses of intravitreal triamcinolone acetonide (IVTA) for diabetic macular edema (DME) and macular edema (ME) secondary to retinal vein occlusion (RVO) is unclear.ObjectivesThis meta-analysis aimed to compare the safety and efficacy of different doses of IVTA in this setting.MethodsA systematic literature search for randomized clinical trials (RCTs) was conducted on Cochrane Library, Ovid MEDLINE, and EMBASE from January 2005 to May 2022. Studies that reported on patients with DME or ME secondary to RVO that received treatment with different doses of IVTA were included. A random-effects meta-analysis was performed. Cochrane's Risk of Bias Tool 2 was used to assess the risk of bias, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) guidelines were used to assess certainty of evidence.ResultsFive RCTs reporting on 1,041 eyes at baseline were included in this meta-analysis. In eyes with ME secondary to RVO, high-dose (4 mg) IVTA achieved a significantly better change in best-corrected visual acuity (WMD = -4.75 ETDRS letters, 95% CI = [-7.73, -1.78], p = 0.002) and reduction in retinal thickness (WMD = -93.02 μm, 95% CI = [-153.23, -32.82], p = 0.002) at months 4-6 compared to low-dose (1-2 mg) IVTA. However, high-dose IVTA had a higher risk of intraocular pressure-related adverse events (RR = 2.99, 95% CI = [1.05, 8.50], p = 0.04) and cataract surgery (RR = 5.67, 95% CI = [3.09, 10.41], p < 0.00001) than low-dose IVTA in eyes with ME secondary to RVO. These efficacy and safety differences in high-dose and low-dose IVTA were not observed in DME eyes.ConclusionsThe RCT evidence in this setting is limited. High-dose IVTA achieved greater improvements in visual acuity and reductions in retinal thickness than low-dose IVTA at months 4-6. However, high-dose IVTA had a less favorable safety profile than low-dose IVTA. The significance of these outcomes was based on patients with ME secondary to RVO, but not DME.

Project description:ObjectiveTo evaluate the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone in comparison with focal/grid photocoagulation for the treatment of diabetic macular edema (DME).DesignMulticenter, randomized clinical trial.ParticipantsEight hundred forty study eyes of 693 subjects with DME involving the fovea and with visual acuity of 20/40 to 20/320.MethodsEyes were randomized to focal/grid photocoagulation (n = 330), 1 mg intravitreal triamcinolone (n = 256), or 4 mg intravitreal triamcinolone (n = 254). Retreatment was given for persistent or new edema at 4-month intervals. The primary outcome was evaluated at 2 years.Main outcome measuresVisual acuity measured with the electronic Early Treatment Diabetic Retinopathy Study method (primary), optical coherence tomography-measured retinal thickness (secondary), and safety.ResultsAt 4 months, mean visual acuity was better in the 4-mg triamcinolone group than in either the laser group (P<0.001) or the 1-mg triamcinolone group (P = 0.001). By 1 year, there were no significant differences among groups in mean visual acuity. At the 16-month visit and extending through the primary outcome visit at 2 years, mean visual acuity was better in the laser group than in the other 2 groups (at 2 years, P = 0.02 comparing the laser and 1-mg groups, P = 0.002 comparing the laser and 4-mg groups, and P = 0.49 comparing the 1-mg and 4-mg groups). Treatment group differences in the visual acuity outcome could not be attributed solely to cataract formation. Optical coherence tomography results generally paralleled the visual acuity results. Intraocular pressure increased from baseline by 10 mmHg or more at any visit in 4%, 16%, and 33% of eyes in the 3 treatment groups, respectively, and cataract surgery was performed in 13%, 23%, and 51% of eyes in the 3 treatment groups, respectively.ConclusionsOver a 2-year period, focal/grid photocoagulation is more effective and has fewer side effects than 1-mg or 4-mg doses of preservative-free intravitreal triamcinolone for most patients with DME who have characteristics similar to the cohort in this clinical trial. The results of this study also support that focal/grid photocoagulation currently should be the benchmark against which other treatments are compared in clinical trials of DME.

Project description:Our objective was to investigate the efficacy and safety of dexa methasone (DEX) implant for the treatment of pseudophakic cystoid macular edema (PCME) in diabetic patients.This was a prospective, non-randomized, interventional case series of 43 participants. Eighteen patients were enrolled in the DEX implant group and 25 were enrolled in an intravitreal triamcinolone acetonide (IVTA) group.The primary efficacy measurement was the percentage of patients who gained improvements of more than ten letters in best corrected visual acuity (BCVA) during 6 months of follow-up. Other efficacy measurements included change in BCVA, change in central macular thickness (CMT), and number of retreatments. The primary safety evaluation was the percentage of patients with intraocular hypertension and variation in intraocular pressure (IOP) during 6 months of follow-up. Other adverse events, such as conjunctival hemorrhage, eye pain, secondary infection, endophthalmitis, noninfectious inflammation, retinal detachment, and implant migration, were also recorded during follow-up.At month 1, we observed that the percentage of patients gaining improvement of more than ten letters was similar in both groups (P = 0.625). As patients in the IVTA group were retreated several times, this effect persisted throughout the study (P = 0.941 at month 2, P = 0.553 at month 3, P = 0.856 at month 6). Variations in CMT were noticed at week 1 and reached their maximum at month 1. No significant difference was found between the two groups (P = 0.831 at week 1, P = 0.783 at month 1). At month 1, the variation in IOP reached its maximum in the DEX implant group and then decreased slightly. However, in the IVTA group, it increased continuously throughout the study. Conjunctival hemorrhage and eye pain were found in both groups, but both were rated as mild in severity, and no significant difference was found (P = 0.184, P = 0.766, respectively).Both IVTA and DEX implants could effectively restore visual function and recover morphological change in diabetic patients with PCME for at least 6 months, but repeated intravitreal injection was required in the IVTA group. DEX implant is well tolerated. We suggest that intravitreal injection of DEX implant is a promising new therapeutic option for diabetic patients with PCME.

Dataset Information

Intravitreal triamcinolone acetonide inhibits breakdown of the blood-retinal barrier through differential regulation of VEGF-A and its receptors in early diabetic rat retinas.

Publications

Intravitreal triamcinolone acetonide inhibits breakdown of the blood-retinal barrier through differential regulation of VEGF-A and its receptors in early diabetic rat retinas.

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