Poly（I：C）与R848对大鼠脊髓小胶质细胞活性的影响

TLR3 and TLR7/8 ligands induce microglia activation in intact rat spinal cord

目的研究Toll样受体3（TLR3）配体多聚肌胞苷酸[Poly（I：C）]与TLR7／8配体R848对小胶质细胞（MG）活性的影响。方法6～8周龄Lewis大鼠30只分为Poly（I：C）组（12只）、R848组（15只）和对照组（3只），前两组大鼠根据处死时间的不同分别分为4、5个亚组，每亚组3只，分别单次腹腔注射1mLPoly（I：C）（5mg／kg）和R848（1mg／kg），对照组注射等量PBS；应用免疫组化检测大鼠脊髓内ED-1、同种异体移植炎性因子-1（AIF-1）、血管内皮单核细胞活化肽Ⅱ（EMAPⅡ）、OX-6和P2X4R的表达，应用免疫组化双染染色检测增殖的MG。结果与对照组相比，Poly（I：C）组和R848组注药后第4天ED-1^＋的MG明显增加，差异有统计学意义（P〈0．05），Poly（I：C）组与R848组仅观察到少量EMAPⅡ^＋细胞，未观察到AIF-1^＋、OX6^＋、P2X4R^＋细胞，对照组未观察到EMAPII^＋、AIF-1^＋、OX6^＋及P2X4R^＋细胞：免疫组化双染显示Poly（I：C）组和R848组大鼠注射后第4天脊髓有少量BrdU^＋／ED-1^＋双染细胞，提示仅有少量MG增殖。结论TLR配体外周给药后可作用于脊髓内的固有免疫系统，进而影响脊髓内MG的免疫活性，提示这类制剂对调节脊髓损伤组织的再生修复有一定价值。

Objective To study the effects of two stimulators of the innate immune system, polyinosine-polycytidylic acid [Poly （I：C）] and R848, on the activation ofmicroglia in rat spinal cord. Methods Thirty male Lewis rats （6 to 8 weeks old） were divided into Poly（I：C） group （n=12）, R848 group （n=15） and control group （n=3）. According to the killing time, the Poly（I：C） group and R848 group were divided into 4 and 5 sub-groups, respectively, with 3 rats in each sub-group. The rats in the subgroups received intraperitoneal injection of a single bolus of Poly（I：C） （5 mg/kg） or R848 （1 mg/kg） accordingly, and in the control group, the same volume of phosphate-buffered saline （PBS） was administered. Activated microglia were observed using immunohistochemistry for ED-1, AIF-1, EMAP Ⅱ, OX6, and P2X4R, and BrdU staining was used to identify the proliferating cells. Results Compared with the control group, both Poly （I：C） and R848 groups showed a significant but transient increase of ED-1-positive spinal cord microglia 4 days after the injection, while no significant differences were found in the microglial markers AIF-1, EMAP Ⅱ, OX6, P2X4 receptor （P2X4R）, indicating that the microglia were not fully activated. Tracing of the cell proliferation by BrdU revealed that only a small fraction of the proliferating cells were microglia （less than 5%）. Conclusion Poly（I：C） and R848 have definite effects on the innate immune system of the spinal cord and modulate the immune activity in the spinal cord, suggesting the value of these agents in modulating local regenerative processes in injured spinal cord.