Abstract 1582 Neonatal Infectious Disease Platform, Monday, 5/3

Group B Streptococci (GBS)neonatal meningitis causes a complex inflammatory process involving numerous biochemical mediators. Nitric Oxide (NO), formed from L-arginine by NO-Synthase (NOS) generated by many cell types in response to bacterial endotoxin and/or cytokines exists in four forms. One form,the inducible NOS (iNOS) is cytokine regulated during inflammation. The Nuclear Factor Kappa B (NF-kB) family of transcription factors plays an important role in the inflammatory processes. Its activation induces a number of biochemical mediator genes, including iNOS. The aim of our study was to link NK-kB to the signaling pathways that induce iNOS expression in response to GBS. We speculate that GBS initiates the inflammatory cascade by induction of iNOS gene expression through the activation of NF-kB. Using RT-PCR, Northern and Western blot analysis, the iNOS mRNA and protein level were determined in cerebral microvascular endothelial cells (CMVL) treated with GBS n=3 (102cfu/ml)and Control n=3 (saline). The significant induction of iNOS mRNA was 5-6 folds (p<0.005) 24 hrs after the addition of GBS compared to control (saline). The amount of mRNA correlated with the iNOS protein 3-4 fold induction (p<0.01) 24 hrs post GBS treatment. Cell viability exceeded 94% suggesting that induction of iNOS was not a result of general cytotoxicity of GBS. Activation of NF-kB was determined in the nuclear extracts of GBS-treated cells (6 ug) after 1 and 3 hrs compared to control. Electrophoretic mobility shift assay (EMSA) was performed by incubating nuclear extracts (6ug) with end-labeled iNOS specific NF-kB oligonucleotide. DNA-NF-kB binding activity was detected within 15 min of GBS treatment and reached it's maximum at 180 mins. Data suggest that NF-kB activation is an early step step in the induction of iNOS gene expression by GBS and that this interaction may play a vital role in the pathogenesis of GBS meningitis funded by MRC Canada