Effects of intravitreal injection of anti‐TNFα and anti‐VEGF in experimental branch retinal vein occlusion in rats

Abstract

AbstractPurpose To investigate the effect of intravitreal injection of anti‐TNFα and anti‐VEGF antibodies on the inner blood retinal barrier (iBRB) in a rat model of experimental branch retinal vein occlusion (BRVO). Claudin‐5, a tight junction protein seen in the retinal vascular wall was examined in order to evaluate the iBRB integrity.Methods BRVO was induced in the right eye of Long Evans rats, using laser photocoagulation. The left eye served as control. The intravitreal injection with either anti‐TNFα or anti‐VEGF was performed in the right eye of each animal, 6 hours after BRVO. Two days after laser application, animals were sacrificed and retinas were harvested. The expression and distribution of claudin‐5 were examined by immunofluorescent staining of flat‐mounts under confocal microscopy.Results Confocal micrographs showed that claudin‐5 is specifically expressed on the cell boundaries of retinal vessels. Two days after laser induced BRVO, the distribution of claudin‐5 in retinal veins of non‐treated rats was weaker, rougher and less linear compared to the images seen in control animals. The staining of claudin‐5 in retinal veins of rats treated with anti‐VEGF or anti‐TNFα was stronger, more linear and uniform.Conclusion The anti‐TNFα and anti‐VEGF drugs seem to partially restore the integrity of the iBRB which may contribute to the reduction of macular edema. Ongoing experiments using RT‐PCR will determine the effect of those drugs in the expression of genes that influence the development of macular edema after BRVO.