Intravitreous interleukin-2 treatment and inflammation modulates glial cells activation and uncrossed retinotectal...

Interleukin-2 (IL-2) plays regulatory functions both in immune and nervous system. However, in the visual system, little is known about the cellular types which respond to IL-2 and its effects. Herein, we investigated the influence of IL-2 in the development of central visual pathways. Lister Hooded rats were submitted to multiple (at postnatal days [PND]7/10/13) or single (at PND10) intravitreous injections of phosphate-buffered saline (PBS) (vehicle), zymosan, or IL-2. IL-2 receptor α subunit was detected in the whole postnatal retina. Chronic treatment with either PBS or IL-2 increases retinal glial fibrillary acidic protein (GFAP) expression, induces intravitreous inflammation revealed by the presence of macrophages, and results in a slight rearrangement of retinotectal axons. Acute zymosan treatment disrupts retinotectal axons distribution, confirming the influence of inflammation on retinotectal pathway reordering. Furthermore, acute IL-2 treatment increases GFAP expression in the retina without inflammation and produces a robust sprouting of the intact uncrossed retinotectal pathway. No difference was observed in glial cells activity in superior colliculus. Taken together, these data suggest that inflammation and interleukin-2 modulate retinal ganglion cells development and the distribution of their axons within central targets.