Figure 2.

TREM2 does not impact early CNS inflammation following a peripheral inflammatory challenge. Hippocampal tissues from PBS perfused male brains were isolated from C57BL/6 N wild type (WT) or Trem2^−/− (KO) mice 4 h post i.p. challenge with 2 mg/kg LPS. RT-qPCR was conducted for (A) Tnfa and (B) Aif1 (encodes IBA1) levels. Shown are the averages ± S.E.M. for N = 4–7 mice per group. No significant differences based on genotype were noted. A main effect of LPS was noted for Tnfa, but no Trem2 genotype effect was observed (Two-way ANOVA, Tukey post-hoc, **P ≤ 0.01, ***P≤ 0.001). Hippocampal interstitial fluid (ISF) was collected from WT and Trem2^−/− mice 4 h prior to and 18 h post i.p. injection with 2 mg/kg LPS using in vivo microdialysis. ISF fractions pooled in 2-h increments were measured for (C) TNFα and (D) IL-6. No significant Trem2 genotype differences were found with the exception of slight elevation of TNFα at the 12 h time point (Multiple t-test, Benjamini and Hochberg post hoc, *P ≤ 0.05). Shown are the averages ± S.E.M. for N = 3 mice per group.