INTERLEUKIN-1 AND TUMOR NECROSIS FACTOR-MEDIATED REGULATION OF C3 GENE-EXPRESSION IN HUMAN ASTROGLIOMA CELLS

In this report, we show that in the human astroglioma cell line D54-MG, both interleukin-1 (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) enhance C3 gene expression in a time- and dose-dependent manner. Kinetic analysis demonstrates that after 96 h, C3 mRNA levels increase approximately 30-fold and 20-fold in response to IL-1beta or TNF-alpha, respectively. C3 protein production increases proportionally, reaching levels 36-fold and 18-fold higher than untreated controls upon exposure to IL-1beta or TNF-alpha, respectively. D54-MG cells require a minimal 1 h exposure to IL-1beta in order to enhance C3 gene expression significantly, while 4 to 8 h are required for TNF-alpha. Simultaneous treatment of D54-MG cells with IL-1beta and interferon-gamma (IFN-gamma) resulted in an additive increase in both C3 mRNA and protein expression, a finding not seen with the combination of TNF-alpha and IFN-gamma. Primary rat astrocytes also express increased C3 mRNA levels after 48 h in response to IL-1beta (5.3-fold increase) and TNF-alpha (7-fold increase), while an additive effect was observed upon simultaneous treatment with both IL-1beta and IFN-gamma. In the central nervous system (CNS), endogenous complement and cytokine production by astrocytes, and enhancement by IFN-gamma, a product of activated T cells often seen in the CNS in neural autoimmune disease, may contribute to the pathogenesis of inflammatory demyelinating diseases such as multiple sclerosis.