Hydrogen peroxide induced chemokine production in the glia-rich cultured cerebellar granule cells under acidosis.
We have documented the time-dependent production of chemotactic cytokine, i.e., IL-8, in the extracellular fluid of astrocyte-rich cultured rat cerebellar granule cells under acidified conditions. In this paper, the mechanism of this production was evaluated based on the production of hydrogen peroxide (H2O2). Significant and time-dependent increases of cytosolic H2O2 were detected under acidosis in astrocyte-rich cultured cell. Upon exposure to 10 microM H2O2, significant levels of IL-8 appeared in the extracellular fluid of astrocyte-rich cells, although an initial transient increase of IL-8 was also seen in the intracellular space. Concurrently, after H2O2 exposure cell injury and a delayed increase of cytosolic Ca2+ levels were detected in astrocyte-rich cells. However, in the absence of extracellular Ca2+, the cell injury and the increase of IL-8 production were significantly attenuated. A synergistic effect of cyclosporine A (an inhibitor of the Ca2+/calmodulin-regulated protein phosphatase) and trifluoperazine (an inhibitor of phospholipase A2) on the suppression of H2O2-induced IL-8 production was clearly evident. These results suggest that extracellular acidosis induced Ca2+-dependent H2O2 production, which in turn stimulated IL-8 expression. which is regulated by the cytosolic Ca2+ cascade. Thus, the production of IL-8 from glia cells may have a role in regulating in the process of cell injury.
Miura
Izumi
I
Department of Bioregulatory Function, School of Medicine, Yamaguchi University, Ube, Japan.
Miyamoto
Koji
K
Nakamura
Kazuyuki
K
Watanabe
Yasuo
Y
D000138:Acidosis / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000172:deficiency / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D003470:Culture Media / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004357:Drug Synergism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016209:Interleukin-8 / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D014268:Trifluoperazine / Q000494:pharmacology
D003470:Culture Media; D016209:Interleukin-8; D014268:Trifluoperazine; D016572:Cyclosporine; D006861:Hydrogen Peroxide; D002118:Calcium