Inflammatory cytokines IL-1α, IL-1β, IL-6, and TNF-α impart neuroprotection to an excitotoxin through distinct pathways

NG Carlson, WA Wieggel, J Chen, A Bacchi… - The Journal of …, 1999 - journals.aai.org
NG Carlson, WA Wieggel, J Chen, A Bacchi, SW Rogers, LC Gahring
The Journal of Immunology, 1999journals.aai.org
The proinflammatory cytokines IL-1α, IL-1β, IL-6, and TNF-α are produced within the CNS,
and, similar to the periphery, they have pleotrophic and overlapping functions. We have
shown previously that TNF-α increases neuronal survival to a toxic influx of calcium
mediated through neuronal N-methyl-d-aspartic acid (NMDA) glutamate-gated ion channels.
This process, termed excitotoxicity, is a major contributor to neuronal death following
ischemia or stroke. Neuroprotection by this cytokine requires both activation of the p55/TNF …
Abstract
The proinflammatory cytokines IL-1α, IL-1β, IL-6, and TNF-α are produced within the CNS, and, similar to the periphery, they have pleotrophic and overlapping functions. We have shown previously that TNF-α increases neuronal survival to a toxic influx of calcium mediated through neuronal N-methyl-d-aspartic acid (NMDA) glutamate-gated ion channels. This process, termed excitotoxicity, is a major contributor to neuronal death following ischemia or stroke. Neuroprotection by this cytokine requires both activation of the p55/TNF receptor type I and the release of TNF-α from neurons, and it is inhibited by the plant alkaloid nicotine. Here, we report that other inflammatory cytokines (IL-1α, IL-1β, and IL-6) are also neuroprotective to excessive NMDA challenge in our system. Neuroprotection provided by IL-1 is distinct from TNF-α because it is inhibited by IL-1 receptor antagonist; it is not antagonized by nicotine, but it is inhibited by a neutralizing Ab to nerve growth factor (NGF). Similar to IL-1, IL-6-mediated neuroprotection is also antagonized by pretreatment with IL-1 receptor antagonist and it is not affected by nicotine. However, neutralizing anti-NGF only partially blocks IL-6-mediated protection. These studies support an important role for distinct but overlapping neuroprotective cytokine effects in the CNS.
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