Fig. 5

Pro-inflammatory cytokine levels and microglial activation in the brains of WT and IL-33^−/− mice after i.c.v. LPS injection. WT mice and IL-33^−/− mice received i.c.v. injection of saline or LPS, and pro-inflammatory cytokine expression levels were detected in the brains by using qRT-PCR and ELISAs. The mRNA levels of the pro-inflammatory cytokines TNF-α (a), IL-6 (b), and MCP-1 (c) were significantly decreased in IL-33^−/− mice 4 h after LPS administration, and no differences in IL-1β levels (d) were observed in the brains of LPS-treated WT and IL-33^−/− mice. TNF-α production in the brains did not differ between LPS-treated WT and IL-33^−/− mice (e), but IL-33^−/− mice produced significantly less IL-6 (f), MCP-1 (g), and IL-1β (h) in the brains than WT mice. Twelve hours after i.c.v. LPS injection, cortex sections of WT and IL-33^−/− mice were immunostained with anti-Iba1 antibody to determine microglial activation, and IL-33^−/− mice exhibited significantly decreased microglial activation as compared to WT mice (i). Data are presented as the mean ± SEM, with n = 5 for all groups; *P < 0.05, **P < 0.01, and ***P < 0.001