Neuronal death in cytokine-activated primary human brain cell culture:: Role of tumor necrosis factor-α.

We examined cytokine-mediated neuronal death in neuron-astrocyte cultures from second trimester human fetal cerebrum. In these cultures, high-output inducible nitric oxide synthase (NOS) and tumor necrosis factor-alpha (TNF alpha) are expressed in astrocytes after exposure to IL-1 beta/IFN gamma. Neuronal cell death was evident at greater than or equal to 48 h following cytokine stimulation. Neutralizing anti-TNF alpha antiserum inhibited (approximate to 48%) neurotoxicity in IL-1 beta/IFN gamma-treated cultures, demonstrating a role for endogenously produced TNF alpha. Interestingly, the degree of neuroprotection conferred by superoxide dismutase or N-methyl D-aspartate (NDMA) receptor antagonists in these cultures was smaller and variable. Similarly, the effect of the NOS inhibitor, N-G-monomethyl L-arginine (NMMA) on IL-1 beta/IFN gamma-induced neuronal death was variable, showing no statistically significant effect when results from more than 30 independent cultures were averaged. Neurons die by apoptosis in, cytokine-treated human fetal CNS cultures as shown by the characteristic nuclear morphology as well as positive labeling for TUNEL. Our results demonstrate a potent neurotoxicity mediated by the cytokine combination IL-1 beta/IFN gamma in primary human neuron-astrocyte cultures and a crucial role for endogenous TNF alpha in mediating neurotoxicity in this system. These results firmly establish the neurotoxic potential of the inflammatory cytokines IL-1 beta and TNF alpha in the human CNS. (C) 1999 Wiley-Liss, Inc.