Interleukin-10 promotes macrophage infiltration in mouse retina

Purpose Inflammation, specifically macrophage infiltration, is known to promote a number of pathologic processes including eye neovascularization. In the current study, we explored the macrophage retinal infiltration in a mouse model that over-expressed interleukin-10 (IL-10) in the retina. Methods A transgenic mouse model in C57BL6 background that overexpress IL-10 under the control of the glial fibrillar acidic protein (GFAP) promoter was analysed. Retinas from transgenic and their wild type (wt) littermates were studied by immunohistochemistry. Results The IL-10 transgenic mice (tg-IL10) expressed higher levels of IL-10 in the retina compared to wild type mice. Histologically, when compared to wt, the cytoarchitecture of the transgenic retinas did not show any differences. The only morphological alteration observed was a CD11b+ macrophage infiltration in the retina and the irido-corneal angle of tg-IL10. These macrophages were fully loaded with melanin. Our observations show that the number of macrophages in tg-IL10 retinas was approximately ten fold superior than in wt. Interestingly, the 80% of macrophages in tg-IL10 retinas were localized along blood vessels. This finding supports previous work in other paradigmas reporting infiltrated macrophages located along blood vessels, which may be involved in the modulation of blood vessel growth and regression. Conclusion A significant increase in the number of macrophages aligning along blood vessels has been observed in the retina of a transgenic model that produces IL-10 under the control of GFAP promoter. This preliminary result suggests that IL-10 promotes macrophage perivascular infiltration in mouse retina.