Figure 5

Spinal nerve injury-induced expression of proinflammatory cytokines in DRGs and spontaneous pain are attenuated in TLR2 knock-out mice. (A) Total RNA was isolated from pooled L5 DRGs of WT and TLR2 knock-out mice with or without L5 spinal nerve transection (n = 5, each group). TNF-α and IL-1β gene expression was measured by real-time RT-PCR and presented as fold induction compared with the sham control group. Means ± SEM of two independent experiments are shown (*, p < 0.05, WT vs. TLR2 knock-out mice; ^##, p < 0.01; sham vs. 48 h post-injury mice). (B) TNF-α and IL-1β protein expression in DRGs were measured by ELISA. Proteins were prepared from pooled DRG tissues of WT and TLR2 knock-out mice with or without L5 spinal nerve transection (n = 5, each group). Means ± SEM of two independent experiments are shown (*, p < 0.05, WT vs. TLR2 knock-out mice; ^##, p < 0.01; sham vs. 7 dpi mice). (C) IL-1β expression was detected in DRG macrophages. DRG tissues at 7 dpi were immunostained with anti-CD68 (a) and anti-IL-1β antibody (b). Merged images are shown in the right panels (c). Low magnification images (75×) of DRG tissue are shown as subsets in each panel. Scale bar: 50 μm. (D) Spontaneous pain in nerve-injured WT and TLR2 knock-out mice was measured using foot lifting behavior following L5 spinal nerve transection. The duration of spontaneous foot lifting was measured in WT mice (WT; n = 6) and TLR2 knock-out mice (TLR2; n = 6). Data were presented as mean ± SEM (*, P < 0.05; WT vs. TLR2 knock-out mice).