Cyclooxygenase-2 mediates the sensitizing effects of systemic IL-1-beta on excitotoxic brain lesions in newborn mice

Epidemiological and experimental data implicate maternal-fetal infection and an associated increase in circulating cytokines in the etiology of cerebral palsy. We have previously shown that pretreatment of newborn mice with systemic interleukin-1-beta exacerbates ibotenate-induced excitotoxic brain lesions. Such lesions are consistent with those observed in cerebral palsy. The present study builds on this murine model to assess the role of cyclooxygenase in interleukin-1-beta-induced brain toxicity. Pups pretreated with interleukin-1-beta developed greater ibotenate-induced brain damage than controls, an effect blocked by the co-administration of nimesulide (cyclooxygenase-2 inhibitor) or indomethacin (cyclooxygenase-1 and -2 inhibitor). Cyclooxygenase inhibitor administration prevented the interleukin-1-beta-induced increase in the production of brain prostaglandin E(2) (a cyclooxygenase metabolite) and changes in the expression of brain interleukin-6, interleukin-18, tumor necrosis factor-alpha, and brain-derived neurotrophic factor. It also stimulated the expression of brain interleukin-10. Our data suggest that the sensitizing effects of circulating inflammatory cytokines on the brain are mediated by the inducible isoform cyclooxygenase-2, which generates excess prostaglandin E(2). Some of these deleterious effects could involve an autocrine/paracrine loop leading to a disruption of the balance between pro- and anti-inflammatory cytokines in the brain.