Skip to main content
. Author manuscript; available in PMC: 2019 Mar 1.
Published in final edited form as: Brain Behav Immun. 2017 Nov 4;69:91–112. doi: 10.1016/j.bbi.2017.11.004

Figure 3. Therapeutic expression of IL-10 transgene mediates pain relief through anti-inflammatory changes in ipsilateral lumbar DRG.

Figure 3

mRNA was isolated from ipsilateral and contralateral Lumbar DRG (L3-5) on Day 12 post-injection (Day 17 post-surgery). (A–F) Baseline transcript levels were compared between WT Naïve (N = 3 mice) and IL-10 KO Naïve (N = 2 mice) groups. Transcript levels for TNF mRNA are significantly higher in ipsilateral DRG from IL-10 KO Naïves compared to WT Naïves (*P < 0.05), but not contralateral DRG (P > 0.05). Tgfb1, Il1b, Mrc1, and Il10ra mRNA transcript levels were not significantly different between WT and IL-10 KO Naïve groups in either ipsilateral or contralateral DRG (P > 0.05). (A) Post-surgical mRNA levels of pro-inflammatory cytokine TNF are greatly increased in ipsilateral lumbar DRG from all CCI conditions compared to Sham+DM/pDNA-Ctrl treated mice, (F(4, 30) = 17.17, P < 0.0001). However, TNF mRNA expression was significantly decreased in pain relieved CCI+DM/pDNA-IL-10 mice compared to allodynic CCI+Saline/pDNA-IL-10 controls. Interestingly, TNF mRNA expression was also significantly decreased in CCI+DM/pDNA-Ctrl mice that recently returned to allodynia as compared to CCI+Saline/pDNA-IL-10 controls. (B) No statistically significant difference was detected for TNF mRNA levels in contralateral DRG by 1-way ANOVA (F(4, 31) = 2.4, P > 0.05). (C) Transcript levels of the anti-inflammatory cytokine TGF-β1 (Tgfb1) are decreased in lumbar DRG collected from chronically allodynic mice (CCI+Saline/pDNA-IL-10) compared to Sham+DM/pDNA-Ctrl treated mice (F(4, 31) = 11.13, P < 0.0001). In contrast, pain relieved CCI+DM/pDNA-IL-10 mice exhibited elevated TGF-β1 mRNA expression compared to both Sham+DM/pDNA-Ctrl treated mice (F(4, 30) = 8.67, P < 0.0001). TGF-β1 mRNA levels were significantly decreased in chronically allodynic CCI+Saline/pDNA-IL-10 mice as compared to both CCI+DM/pDNA-Ctrl and pain-relieved CCI+DM/pDNA-IL-10 mice. (D) No statistically significant difference was detected for TGF-β1 mRNA levels in contralateral DRG (F(4, 31) = 0.03, P > 0.05). (E) No statistically significant difference was detected for pro-inflammatory cytokine IL-1β (Il1b) mRNA transcript levels in ipsilateral DRG (F(4, 27) = 1.36, P > 0.05). (F) Post-surgical mRNA levels for the mannose receptor (Mrc1; MR; CD206) are increased in ipsilateral lumbar DRG from all CCI conditions compared to Sham+DM/pDNA-Control treated mice, with MR transcript levels significantly decreased in pain-reversed CCI+DM/pDNA-IL-10 mice and recently allodynic CCI+DM/pDNA-Ctrl mice as compared to chronically allodynic CCI+Saline/pDNA-IL-10-treated mice (F(4, 30) = 29.48, P < 0.0001). (G) For IL-10 receptor alpha (Il10ra) mRNA levels, all CCI conditions exhibited significant increases compared to Sham+DM/pDNA-Ctrl mice (**P < 0.01) (F(4, 30) = 6.82, P < 0.001). N = 5–9 mice/group for treatment groups, as indicated on graphs. mRNA levels (mean ± SEM) are normalized to 18S rRNA and graphically presented relative to mean WT Naïve levels. Post-hoc multiple comparisons via Fisher’s LSD (α = 0.05; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001).