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Expression pattern of extracellular matrix (ECM) components after ranibizumab treatment of neovascular age-related macular degeneration (AMD): preliminary study

Session Details

Session Title: AMD III

Session Date/Time: Sunday 29/09/2013 | 11:00-13:00

Paper Time: 12:20

Venue: Hall G1 (Level 2)

First Author: M.Nita POLAND

Co Author(s):    K. Michalska-Ma?ecka   U. Mazurek   M. Kimsa   A. Grzybowski     

Abstract Details

Purpose:

The aim of the study was to evaluate the effect of loading doses of ranibizumab on gene expression of collagen, elastin and laminin in patients with exudative AMD.

Setting:

Study was conducted by the Department of Ophthalmology, Medical University of Silesia, Independent Public Clinical Hospital, Katowice, Poland.

Methods:

We performed a retrospective review of patients with neovascular AMD treated with intravitreal ranibizumab. It included patients ≥ 60 years, with BCVA 20/40 to 20/320 (Snellen equivalent), active choroidal neovascularization (CNV) in biomicroscope and in OCT, which wasn’t treated with any of the following: intravitreal injection of anty-VEGF, photodynamic therapy with verteporfine, laserotherapy, or steroids (triamcinolone). The study excluded eyes with: polypoidal choroidal vasculopathy (PCV), retinal angiomatous proliferations (RAP), coexisting diabetic maculopathy, epiretinal membrane, idiopatic CNV, and retinal vein occlusion (RVO). Patients were given ophthalmological exams (fluorescein and indocyanine angiography, optical coherence tomography, visual acuity, eye fundus, Goldmann applanation tonometry) before and after injections. Injections were given three times, at intervals of 4 weeks. The expression profile of selected genes of the EMC were analyzed after 3 injections. Venous blood samples of AMD patients before and after intravitreal injections were collected into EDTA-containing tubes. Total RNA concentration was determined by spectrophotometric measurement in 5 μl capillary tubes using the Gene Quant II RNA/DNA Calculator (Pharmacia Biotech, Cambridge, UK). The analysis of genes’ expression profile of collagen, laminin and elastin in samples was performed using commercially available oligonucleotide microarrays of HG-U133A (Affymetrix, Santa Clara, CA) according to the manufacturer’s recommendations.

Results:

Ranibizumab has an effect on the ECM. Under the influence of a loading dose of ranibizumab, overexpression of genes encoding collagen type VI (COL6A1) was observed. Increased gene expression of collagen type VI may be beneficial generally and locally, as it increases the amount of an agent that promotes cell adhesion to basement membranes and the interaction of ECM. On the other hand, it can help to increase the basal deposits (BLamD and SD) in Bruch's membrane of the eye being treated and the adjacent eye, and through them contribute to pathological angiogenesis. After the influence of a loading dose of ranibizumab, genes encoding collagen type IV (COL4A6) were silenced, as were the genes encoding the laminin gamma (LAMC2). COL4A6 gene expression exhibited the greatest decrease in the total analysed group of genes. Laminin is a very important, next to the type IV collagen, structural component of basement membranes. It initiates the process of membrane formation and is necessary for it, in contrast to collagen IV which, in spite of its universality and abundance, is not involved in this process, but plays an important role in maintaining the structure. Anti-VEGF therapy had no effect on elastin gene expression change.

Conclusions:

After administering three intravitreal injections it was demonstrated that the administration of ranibizumab affects the expression profile of genes of collagen and laminin. Additionally, in most of the eyes there was a significant improvement in visual function. It has been shown that this drug is well tolerated while also reducing macular edema and leakage of CNV.

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