Prevention of neuron and oligodendrocyte degeneration by interleukin-6 (IL-6) and IL-6 receptor/IL-6 fusion protein in organotypic hippocampal slices

We investigated the effects of IL-6 and a chimeric derivative of IL-6 and soluble IL-6 receptor (IL6RIL6 chimera) on excitotoxic injury in rat organotypic hippocampal slices. Brief application of N-methyl-d-aspartate (NMDA) induced astrocyte reactivity, neuron cell death, and oligodendrocyte degeneration, the latter caused by secondary activation of AMPA/kainate receptors. Both these cytokines rescued neurons and oligodendrocytes, albeit the chimeric compound was much more potent and efficient than IL-6. No change was produced on reactive astrocytosis. The cytokines preserved myelin basic protein (MBP) production in slices exposed to excitotoxic insult, and when applied singularly for a week, they also enhanced both MBP and proteolipid protein expression. These effects occurred through activating the signal transducer gp130 and were associated with stimulation of transcription factors STAT1 and STAT3. Our results suggest that IL-6 and IL6RIL6 may prove to be valuable in treating neurodegenerative and demyelinating diseases.