Leukocyte infiltration into the brain has been implicated in the development of ischemic brain damage. In this study, simulated in vitro
ischemia/reperfusion and IL-1beta were found to up-regulate both the expression of
intercellular adhesion molecule- (ICAM-1) in cultured human cerebromicrovascular endothelial cells (
HCEC) and the adhesion of allogenic neutrophils to
HCEC. Both
HCEC and human fetal astrocytes (FHAS) also responded to IL-1beta and to in vitro
ischemia/reperfusion by a pronounced up-regulation of
IL-8 and MCP-1
mRNA and by increased release of
IL-8 and MCP-1 in cell
culture media. FHAS were found to release 30-times higher levels of MCP-1 than
HCEC under both basal and ischemic conditions. However, 100 u/ml IL-1beta induced greater stimulation of both
IL-8 and MCP-1 secretion in
HCEC (50 and 20 times above controls, respectively) than in FHAS (three and two times above controls, respectively).
IL-8 was the principal neutrophil
chemoattractant released from IL-1beta-treated
HCEC, since
IL-8 antibody completely inhibited neutrophil chemotaxis enticed by
HCEC media. However, the
IL-8 antibody neutralized only 50% of IL-1beta-stimulated neutrophil
chemoattractants released from FHAS, and 40%-60% of
ischemia-stimulated chemotactic activity released by either
HCEC or FHAS. These results suggest that simulated in vitro
ischemia, in addition to
IL-8 and MCP-1, stimulates secretion of other bioactive
chemokines from
HCEC and FHAS.