Galectin-1 involvement in neovascular retinopathies

MAGALI E. RIDANO; PAULA SUBIRADA; MARIA CONSTANZA PAZ; VALERIA E. LORENC; JUAN CARLOS STUPIRSKI; A. LAURA GRAMAJO; JOSE D LUNA PINTO; DIEGO O. CROCI RUSSO; GABRIEL A. RABINOVICH; MARIA CECILIA SANCHEZ

Congreso; Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) 2017; 2017

Purpose: Vascular Endothelial Growth Factor (VEGF) inhibitors have been established as the mainstay of currenttreatment of neovascular retinopathies (NVRx), however, it remains an unmet medical need. Galectin-1 (Gal1) hasbeen implicated in pathologies associated with neovascularization (NV) through VEGF independent pathways and byits interaction with N-acetyllactosamine (NAcLc) structures in N- and O- glycans on glycosylated receptors. Here, wehypothesize that Gal1 is participating in experimental and clinical NVRx and independently of anti-VEGF therapy.Methods: Oxygen-Induced Retinopathy (OIR) mouse model was carried out. Briefly, C57BL/6 mice (OIR, N=33) wereexposed to 75% O2 from P7 to P12, after which they were brought to room air for additional five (P17) or nine days(P26). Age-match mice maintained in room air (RA, N=15) were used as controls. Some OIR mice were intraocularinjected at P12 with 1,25 μg of anti-VEGF (N=9) or vehicle (N=9). At P12, P17 and P26 mice were sacrificed. Someeyes were fixed to obtain cryosections for immunofluorescences and retinas were isolated to analyze Gal1 expressionby Western blots and qRT-PCR. Moreover, aqueous humor of patients with NVRx (N=16) or from control patients(N=6) was used to measure Gal1 levels by ELISA assays. GraphPad Prism program was employed for statisticalanalysis.Results: Gal1 protein and mRNA levels were increased in P17 and P26 OIR retinas respect to RA controls (p<0,05).Immunofluorescence assays showed that it was located in the layers closest to the vitreous humor and its expressionwas most prominent in areas with NV. Moreover, Gal1 colocalization with Glial Fibrillary Acidic Protein (GFAP) andGlutamine Synthase (GS) suggested that it was present in astrocytes and activated Müller cells. In addition, it waswithin neovessels (OIR) but not in normal retinal vessels (RA) at P17. Byotinilated lectin staining demonstrated thatOIR conditions modify the ??glycosylation signature?? of the normal retina showing a glycosylation pattern permissive toGal1 binding at P17 OIR. Furthermore, anti-VEGF therapy was not able to reduce the OIR Gal1 induction (p<0,05).Finally, Gal1 levels were also elevated in aqueous humor of patients with NVRx (p<0,05).Conclusions: We conclude that Gal1 is participating in the pathogenesis of OIR and it is independently of the anti-VEGF therapy. In light of our results, we also suggest that it is involved in the clinical NVRx.