IL6 and infectious meningitis: Similar results were obtained for the expression of IL-1β: meningitis resulted in a strong increase of IL-1β mRNA expression in the hippocampus and cortex in WT mice while the deficient mice strains displayed lower IL-1β levels with a significant difference for TNFR1−/− and TNFR1-IL-6−/− mice compared to infected WT mice (Figures 5(c) and 5(g)).