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T. Dietrich, J. Onderka, F. Bock, D. Hos, G. Zahn, R. Stragies, F. E. Kruse, C. Cursiefen; Effect of Integrin Alpha 5 Inhibition on Lymphangiogenesis and Recruitment of CD11b-Positive Macrophages in a Murine Model of High-Risk Keratoplasty. Invest. Ophthalmol. Vis. Sci. 2007;48(13):181.
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© ARVO (1962-2015); The Authors (2016-present)
Neovascularization of the cornea is the main risk factor for immune rejection after penetrating keratoplasty (PK). Integrin alpha 5 was recently identified on lymphatic endothelial cells as well as macrophages. Therefore, purpose of this study was to analyze whether specific inhibition of integrin alpha 5 can reduce lymphangiogenesis in the context of corneal grafting and whether such an inhibitory effect is due to either direct inhibition of lymphatic endothelial cells or recruitment of inflammatory macrophages.
Inflammatory corneal neovascularization was induced by placing three 11-0 nylon sutures in 6 week old BalbC mice in a standardized fashion. Mice in the treatment group systemically received integrin alpha 5 inhibiting molecules (JSM6427; 23 mg/kg/d) via subcutaneous osmotic pumps (Alzet® Pumps) for 14 days (n = 20). In the control group, only the vehicle solution was applied in the same manner (n = 20). After this pre-vascularization period, mice were either sacrificed for analysis of lymphangiogenesis and macrophage recruitment (n = 5 per group) or PK was performed. Corneal grafts from 6 week old C57Bl/6 mice were used. Mice were sacrificed 6 weeks after PK. For immunohistochemistry, LYVE-1 antibody as a specific lymphatic vascular marker and CD-11b as macrophage marker were used on whole mount preparations of the corneas. The fluorescence microscopic images were analyzed morphometrically using analySIS^B® software.
Systemic inhibition of alpha 5 integrin by small molecule antagonists resulted in a statistically significant reduction of lymphatic vessels outgrowth from the limbus both prior to (p < 0.001; lymphvascularized area 52.4% vs. control set as 100%) as well as after grafting compared to the control group (p = 0.0173; lymphvascularized area 49.8% vs. control set as 100%). There was no significant reduction of the number of macrophages recruited both prior to (p = 0.55) as well as after grafting (p = 0.4).
Inflammatory lymphangiogenesis in the cornea prior to and after grafting can be inhibited by blockade of integrin alpha 5. The recruitment of CD-11b positive macrophages into the cornea and into the graft was not significantly affected, which suggests a direct effect of integrin alpha 5 inhibition on lymphatic endothelial cells.
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