Altered chemokine expression in the spinal cord and brain contributes to differential interleukin-1b-induced neutrophil recruitment Sandra J. Campbell,* David C. Wilcockson, Angus G. Butchart,* V. Hugh Perry  and Daniel C. Anthony* *Molecular Neuropathology Laboratory and  CNS Inflammation Group, School of Biological Sciences, University of Southampton, Southampton, UK Abstract The pattern of neutrophil recruitment that accompanies inflammation in the CNS depends on the site of injury and the stage of development. The adult brain parenchyma is refractory to neutrophil recruitment and associated damage as compared to the spinal cord or juvenile brain. Using quanti- tative Taqman RT–PCR and enzyme-liked immunosorbent assay (ELISA), we compared mRNA and protein expression of the rat neutrophil chemoattractant chemokines (CINC) in spinal cord and brain of adult and juvenile rats to identify possible association with the observed differences in neutro- phil recruitment. Interleukin-1b (IL-1b) injection resulted in up-regulated chemokine expression in both brain and spinal cord. CINC-3 mRNA was elevated above CINC-1 and CINC- 2a, with expression levels for each higher in spinal cord than in brain. By ELISA, IL-1b induced greater CINC-1 and CINC-2a expression compared to CINC-3, with higher protein levels in spinal cord than in brain. In the juvenile brain, significantly higher levels of CINC-2a protein were observed in response to IL-1b injection than in the adult brain following an equivalent challenge. Correspondingly, neutrophil recruitment was observed in the juvenile brain and adult spinal cord, but not in the adult brain. No expression of CINC-2b mRNA was detected. Thus differential chemokine induction may contrib- ute to variations in neutrophil recruitment in during develop- ment and between the different CNS compartments. Keywords: chemokine, CINC, cytokine, interleukin-1b, neutrophil, spinal cord. J. Neurochem. (2002) 83, 432–441. In the CNS, where there is little scope for cellular repair, acute inflammation and the recruitment of neutrophils following injury has been shown in many instances to be deleterious (Matsuo et al. 1994; Jiang et al. 1995). The CNS has evolved mechanisms to regulate the potentially damaging effects of an acute inflammatory response and, in particular, to restrict the recruitment of neutrophils (Anthony et al. 1997). However, within the CNS, there is still marked variation in the inflammatory response to equivalent chal- lenges at different sites (Andersson et al. 1991). Inflamma- tion in the spinal cord following mechanical lesions or microinjections of tumour necrosis factor-a (TNFa) or interleukin-1b (IL-1b) is more overt when compared to that in the brain (Schnell et al. 1999a, 1999b). It is also clear that there are periods during development in both rats and mice, known as windows of susceptibility, when the brain is less refractory to inflammatory stimuli than it is in an adult animal (Lawson and Perry 1995; Anthony et al. 1997; Bolton and Perry 1998). The mechanisms that underlie the differences in neutrophil recruitment and inflammatory response between different CNS compartments and in the brain at different developmental stages are unknown. The principal inflammatory mediators, necessary for the induc- tion of a successful inflammatory cascade, are induced in the Received March 22, 2002; revised manuscript received May 15, 2002; accepted July 19, 2002. Address correspondence and reprint requests to S. J. Campbell, Molecular Neuropathology Laboratory, School of Biological Sciences, University of Southampton, Biomedical Sciences Building, Southampton S016 7PX, UK. E-mail: s.j.campbell@soton.ac.uk Abbreviations used: BBB, blood–brain barrier; CINC, cytokine- induced neutrophil chemoattractant; GAG, glycosaminoglycan; GAP- DH, glyceraldehyde 3-phosphate dehydrogenase; ELR, glutamate– leucine–arginine; GRO, growth-regulated oncogene; IL-1b, interleukin- 1b; IL-8, interleukin-8; MIP-2, macrophage inflammatory protein-2; TNFa, tumour necrosis factor-a; T8, thoracic level 8. Journal of Neurochemistry , 2002, 83, 432–441 432 Ó 2002 International Society for Neurochemistry, Journal of Neurochemistry , 83, 432–441