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Interleukin-18 Expression After Focal Ischemia of the Rat Brain: Association With the Late-Stage Inflammatory Response

Sebastian Jander, Michael Schroeter, Guido Stoll

J Cereb Blood Flow Metab. 2002 Jan;22(1):62-70.

PMID: 11807395

Abstract:

Interleukin-18, previously designated interferon gamma-inducing factor, is a proinflammatory cytokine structurally related to interleukin-1beta and is therefore considered a member of the growing family of interleukin-1-like cytokines. Both interleukin-18 and -1beta are synthesized as inactive precursors that necessitate cleavage by caspase-1 for functional activity. In this study, the authors analyzed the expression pattern of interleukin-18, -1beta, and caspase-1 in focal brain ischemia induced in rats either by permanent middle cerebral artery occlusion or by photothrombosis of cortical microvessels. Using reverse transcriptase-polymerase chain reaction, they found a delayed increase of interleukin-18 mRNA starting at 48 hours and reaching its peak between 7 and 14 days after ischemia. In contrast, interleukin-1beta mRNA peaked within 16 hours and was downregulated thereafter. The time course of caspase-1 mRNA expression paralleled that of interleukin-18, but not of interleukin-1beta mRNA. Immunocytochemically, interleukin-18 expression was localized to ED1-positive phagocytic microglia/macrophages infiltrating the necrotic lesion between 3 and 6 days after ischemia. In contrast, interleukin-1beta immunoreactivity was expressed by ramified microglia in the infarct border zone and remote ipsilateral cortex during the first 16 hours postlesion. Induction of interleukin-18 was not accompanied by detectable expression of interferon-gamma mRNA. Their data show spatial and temporal diversity in interleukin-1 and -18 cytokine family expression in brain ischemia, and suggest a role of the interleukin-18/caspase-1 pathway in late-stage inflammatory responses to focal brain ischemia.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR42413369 Interleukin-18 from rat Interleukin-18 from rat Price
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