GFAPδ immunostaining improves visualization of normal and pathologic astrocytic heterogeneity

Neuropathological analysis of cellular mechanisms underlying gliosis and brain tumors is slowed by the lack of markers allowing to distinguish glial subpopulations in normal or pathological human brains. We therefore evaluated GFAPdelta immunostaining in a wide panel of astrogliosis and gliomas, and compared these with GFAP and vimentin. In normal tissue, gliosis and gliomas, GFAPdelta immunostaining was observed in astrocytes with relatively high GFAP levels. GFAPdelta immunostaining was most conspicuous in glia limitans astrocytes. In Chaslin's gliosis accompanying chronic epilepsy, GFAPdelta immunostaining evidenced the glia limitans reactive astrocytes as the source of the dense fibrillary meshwork typical of Chaslin's gliosis. Interestingly GFAPdelta and vimentin immunostainings coincided in normal tissues and gliosis, but not in gliomas. Altogether these results show that combined GFAP, GFAPdelta and vimentin labelling reveals fine gliofilament regulation in normal and pathological brain.