title: Early effects of dexamethasone and anti-VEGF therapy in an inflammatory corneal neovascularization model.
abstract: Inflammatory angiogenesis is the pathogenic mechanism of various sight-threatening eye diseases, among them corneal neovascularization. Current treatment options include steroids which have undesirable side effects, or anti-VEGF which has only limited efficacy. In an inflammatory environment, however, angiogenesis can be stimulated by numerous factors not directly targeted by anti-VEGF therapy. The aim of this study was to induce corneal inflammation leading to angiogenesis, and investigate the early, differential effects of steroid and anti-VEGF therapy at the cellular, tissue, and gene expression levels. Fifty-two Wistar rats received a single intrastromal corneal suture to induce a controlled inflammatory angiogenic response. Rats were subsequently treated with dexamethasone, rat specific anti-VEGF, or goat IgG (control), topically 4 times daily for 7 days. In vivo confocal microscopy of the cornea was performed longitudinally from 5 h up to 7 d to investigate morphology at the cellular and tissue-level. In vivo photographic vessel analysis and immunohistochemistry were also performed. RT-PCR for VEGF-A, FGF-2, IL-6, TNF-α, CXCL2, CCL2, CCL3 and DLL4 was performed at 24 h, and for VEGF-A, IL-6, TNF-α, FGF-2, CXCL2, CCL2, and CCL3 at 7 days. Early infiltration of CD11b + myeloid cells into the cornea at 5 h post-suture was delayed by both treatments relative to controls; however neither treatment was able to suppress accumulation of myeloid cells at day 2 or 7. Limbal vessel dilation was inhibited at 5 h by both treatments, but only dexamethasone showed sustained effect until day 2. Early macrophage recruitment was also suppressed by dexamethasone (but not by anti-VEGF) until day 2. Dexamethasone furthermore suppressed corneal neovascularization at day 7 by over 90%, whereas suppression by anti-VEGF was 14%. Despite differential suppression of vessel dilation, macrophage recruitment, and vascular invasion, anti-VEGF and dexamethasone both down-regulated VEGF-A and IL-6 expression at 24 h with sustained effect to 7 d. They also both down regulated FGF-2 and TNF-α at 24 h and CCL2 at 7 d. In conclusion, anti-angiogenic treatments influence early, pre-angiogenic tissue activity such as limbal vessel dilation, inflammatory cell infiltration of the stroma, and macrophage recruitment. Importantly, the differential effects of steroids and anti-VEGF treatment in suppressing neovascular growth could not be attributed to differential inhibition of several major angiogenic and inflammatory factors in the early pre-sprouting phase, including IL-6, VEGF-A, FGF-2, TNF-α, CCL2, CCL3, CXCL2, or DLL4.
authors.affiliation: Department of Ophthalmology, Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden.
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Mirabelli
authors.affiliation: Department of Ophthalmology, Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden. Electronic address: beatrice.peebo@liu.se.
authors.forename: Beatrice B
authors.initials: BB
authors.lastname: Peebo
authors.affiliation: Department of Ophthalmology, Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Xeroudaki
authors.affiliation: Department of Ophthalmology, Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden.
authors.forename: Marina
authors.initials: M
authors.lastname: Koulikovska
authors.affiliation: Department of Ophthalmology, Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden.
authors.forename: Neil
authors.initials: N
authors.lastname: Lagali
mesh_terms: D000704:Analysis of Variance; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D016510:Corneal Neovascularization / Q000188:drug therapy* / Q000473:pathology; D003907:Dexamethasone / Q000627:therapeutic use*; D004195:Disease Models, Animal; D016850:Limbus Corneae / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects; D008297:Male; D017208:Rats, Wistar; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors*
chemical_list: D020533:Angiogenesis Inhibitors; D000893:Anti-Inflammatory Agents; D042461:Vascular Endothelial Growth Factor A; D003907:Dexamethasone
keywords: angiogenesis; anti-VEGF; confocal microscopy; cornea; dexamethasone; inflammation; neovascularization; rat