SCHWANN CELL APOPTOSIS IN TISSUE CULTURE FOLLOWING THE ADMINISTRATION OF PRO-INFLAMMATORY CYTOKINES

In immune-mediated demyelination of the nervous system, glial cell apoptosis has been observed recently; however, the relevance of the phenomenon and the characterization of the involved molecules are still controversial. Cytokines are secreted by many cells, including inflammatory and glial cells, and appear to play a relevant role in the peripheral nervous system (PNS) immuno-mediated demyelination, being active in promoting the damage to Schwann cells, myelin, and axons. Even though the exact role of the different cytokines is at present uncertain, they have a sequential different expression in PNS immune-mediated demyelination and could induce apoptotic death of Schwann cells in the vicinity of the inflammatory reaction via the expression of CD95 (Apo1/Fas). This study has been designed to detect in rat primary Schwann cell tissue cultures whether the administration of IL-1B and IFN-y can induce cell death. Identification of apoptotic Schwann cell was performed by morphological, immunohistochemical, and electron-microscopy analysis. Our results show that Schwann cells stimulated by proinflammatory cytokines IL-1B and IFN-y show morphological evidence of nuclear chromatin condesation at the DAPI staining and are TUNEL positive. The same features of apoptotic cell death were observed by electron microscopy. These findings provide evidence to support the hypothesis that cytokines can directly damage Schwann cells in disorders of the PNS.