Upregulation of TRPM2 and production of CXCL2 in cultured macrophages that evoked mechanical allodynia after intraplantar injection. Upregulation of TRPM2 and production of CXCL2 in cultured macrophages that evoked mechanical allodynia after intraplantar injection. Cultured peritoneal macrophages were treated with LPS (100 ng/ml) and IFN-γ (10 ng/ml) for the indicated times. A, The expression level of TRPM2 mRNA was measured by real-time PCR. TRPM2 mRNA levels were normalized to the GAPDH mRNA level and expressed relative to the control (fold). ***p < 0.001 (compared with unstimulated control macrophages); n = 3. B, In LPS/IFN-γ-stimulated cultured macrophages derived from WT and TRPM2-KO mice, the CXCL2 level was measured by ELISA. **p < 0.01; n = 3. C, Naive WT mice were injected intraplantarly with WT- or TRPM2-KO-derived cultured macrophages (5 × 105 cells/20 μl) stimulated by LPS (100 ng/ml) for 1 h. D, E, WT and TRPM2-KO mice were injected intraplantarly with TNF-α (50 pmol, n = 6–7; D) or an ROS donor, t-BOOH (3 μmol, n = 9–11; E). The 50% withdrawal threshold to mechanical stimulation in the von Frey filament test was determined at the indicated times (n = 5). *p < 0.05; **p < 0.01 (compared with WT-derived cultured macrophages mice). Data are expressed as means ± SEM.. Kayo Haraguchi et al. J. Neurosci. 2012;32:3931-3941 ©2012 by Society for Neuroscience