Different Ipsi- and Contralateral Glial Responses to Anti-VEGF and Triamcinolone Intravitreal Injections in Rats

Abstract

Citation: Di Pierdomenico J, García-Ayuso D, Jiménez-López M, AgudoBarriuso M, Vidal-Sanz M, VillegasPérez MP. Different ipsi-and contralateral glial responses to anti-VEGF and triamcinolone intravitreal injections in rats. Invest Ophthalmol Vis Sci. 2016;57:3533-3544. DOI:10.1167/iovs.16-19618 PURPOSE. To investigate the glial response of the rat retina to single or repeated intravitreal injections (IVI).METHODS. Albino Sprague-Dawley rats received one or three (one every 7 days) IVI of anti-rat VEGF (5 lL; 0.015 lg/lL), triamcinolone (2.5 or 5 lL; 40 lg/lL; Trigón Depot), bevacizumab (5 lL; 25 lg/lL; Avastin), or their vehicles (PBS and balanced salt solution) and were processed 7 days after the last injection. Retinas were dissected as whole mounts and incubated with antibodies against: Iba1 (Ionized Calcium-Binding Adapter Molecule 1) to label retinal microglia, GFAP (Glial Fibrillary Acidic Protein) to label macroglial cells, and vimentin to label Müller cells. The retinas were examined with fluorescence and confocal microscopy, and the numbers of microglial cells in the inner retinal layers were quantified using a semiautomatic method.RESULTS. All the injected substances caused an important micro-and macroglial response locally at the injection site and all throughout the injected retina that was exacerbated by repeated injections. The microglial response was also observed but was milder in the contralateral noninjected eyes. The IVI of the humanized antibody bevacizumab caused a very strong microglial reaction in the ipsilateral retina. Two types of macroglial response were observed: astrocyte hypertrophy and Müller end-foot hypertrophy. While astrocyte hypertrophy was widespread throughout the injected retina, Müller end-foot hypertrophy was localized and more extensive with triamcinolone use or after repeated injections. CONCLUSIONS.Intravitreal injections cause micro-and macroglial responses that vary depending on the injected agent but increase with repeated injections. This inflammatory glial response may influence the effects of the injected substances on the retina.

Topical Treatment With Bromfenac Reduces Retinal Gliosis and Inflammation After Optic Nerve Crush

“…33 Indeed, it has been recently shown that macroglial cells hypertrophy across the whole retina after an apparently innocuous manipulation such as intravitreal injection of phosphate-buffered saline. 29 It was interesting to find that they also responded to topical administration of bromfenac, as evidenced by the significant increase of GFAP and vimentin and the decrease of CRALBP1 in extracts from intact retinas treated during 7 days with the NSAID. However, these changes reverted in ONC þ bromfenac retinas when compared to ONC alone, indicating, firstly, that the gliosis triggered by ONC is very strong and almost but not completely abolished by bromfenac, and, secondly, that treatment with this NSAID maintains retinal homeostasis after ONC.…”

“…21 Inflammation and edema are, as well, common responses to tissue damage or disease, as has been shown for the retina in animal models of glaucoma or optic nerve injury. [22][23][24][25][26][27][28] Macroglial retinal cells, astrocytes, and Müller cells readily respond to intravitreral injections, 29 injury, or disease. [30][31][32][33] A very well characterized model of retinal damage and degeneration is optic nerve axotomy in rodents.…”

Neuroprotective Effects of FGF2 and Minocycline in Two Animal Models of Inherited Retinal Degeneration

“…IVIs were performed only in the left eye following previously described methods that are standard in our laboratory. 39 Briefly, the injections were made through the supratemporal sclera using a Hamilton microsyringe (26G; Hamilton 701 N, Esslab, Benfleet, UK). Once the needle was visualized retrolenticularly, the liquid was injected and the needle was removed.…”

Early Events in Retinal Degeneration Caused by Rhodopsin Mutation or Pigment Epithelium Malfunction: Differences and Similarities

“…Macroglial retinal cells: astrocytes and Müller cells, readily respond to intravitreral injections (Di Pierdomenico et al, 2016), injury or disease (Ramírez et al, 2010; Gallego et al, 2012; Rojas et al, 2014; de Hoz et al, 2016). Macroglial hypertrophy has been related to retinal stress or injury, and thus, gliosis has been used to assess the homeostatic state of the retina (Cuenca et al, 2014).…”