Pro‐inflammatory cytokines induce differentiation in cultured schwann cells

During cell-mediated demyelination of the peripheral nervous system (PNS), pro-inflammatory cytokines have a predictable pattern of expression and appear to be involved in damaging the myelin sheath and the axon. However, the role of these molecules regarding Schwann cell life and death is still controversial. In fact, some pro-inflammatory cytokines act synergistically to kill PNS glial cells, but besides Schwann cell death they can induce cell proliferation, and both processes are related to cytokine dosage and time of exposure. In this preliminary study we stimulated Schwann cell cultures with 10 U/ml interleukin-1 beta and 50 U/ml interferon-gamma for 24, 48 and 72 hours. As previously reported we observed the peak of cell death and proliferation by 24 hours with both cytokines. At this time point, interestingly, in few Schwann cells belonging to the cytokine treated cultures and not to the untreated control cultures, we observed by electron microscopy analysis a cellular differentiation towards a myelin forming phenotype, even though our cultures were axon free as we have detected by immunocytochemical analysis with neurofilament antibody. In conclusion, we think that pro-inflammatory cytokines besides promoting Schwann cell death and proliferation might be involved in the processes of cellular differentiation.