甲酰基肽受体1对脊髓损伤后小胶质细胞诱导的炎性反应的影响

Effect of formyl peptide receptor-1 on microglia-induced inflammatory response after spinal cord injury

目的探讨甲酰基肽受体1(Fpr1)是否参与脊髓损伤(SCI)后小胶质细胞诱导的炎性反应,为SCI后减轻神经炎性反应提供理论依据。方法将30只成年C57BL/6雄性小鼠按照随机数字表法分为假手术组(Sham组)和不同时间点SCI组(术后1、3、5、7 d),每组6只。采用蛋白质印迹检测小鼠SCI后不同时间点损伤周围脊髓组织Fpr1蛋白的表达变化,采用免疫荧光实验检测Fpr1在小胶质细胞中的定位。选择Fpr1蛋白表达水平最高时间点制作小鼠模型进行进一步实验,将小鼠随机分为SCI组和Fpr1抑制剂(HCH6-1)干预组(HCH6-1干预组),每组6只,并与Sham组比较,应用免疫荧光实验评估各组小胶质细胞的活化程度,通过蛋白质印迹检测各组炎性因子[白细胞介素(IL)-1β、IL-18和肿瘤坏死因子-α(TNF-α)]以及炎性小体(NLRP3、ASC和Caspase-1)蛋白的表达情况。结果与Sham组相比,Fpr1在SCI后第1天开始表达增多,第3天最高,第5天下降,第7天下降至与Sham组水平相当。免疫荧光染色结果提示,Fpr1主要表达在小胶质细胞。与SCI组相比,HCH6-1干预组小胶质细胞的活化程度显著减轻,炎性因子(IL-1β、IL-18和TNF-α)和炎性小体(NLRP3、ASC和Caspase-1)的表达显著减少。结论Fpr1能够介导SCI后小胶质细胞诱导的炎性反应,抑制Fpr1有望成为干预SCI后继发性损伤的新治疗策略。

Objective To investigate whether the formyl peptide receptor-1(Fpr1)is involved in microglia-induced inflammatory response after spinal cord injury(SCI)to provide a theoretical basis for reducing neuroinflammatory response after SCI.Methods Thirty adult C57BL/6 male mice were randomly divided into a sham surgery group(sham group)and SCI groups at different time points(1,3,5,7 d after operation),with 6 mice in each group.The expression of Fpr1 protein in the spinal cord was detected by Western blotting at different time points after SCI,and the localization of Fpr1 in microglia was detected by immunofluorescence assay.The time point at which the expression level of Fpr1 protein was highest was selected to create the model for further experiments.The mice were randomly divided into SCI group and Fpr1 inhibitor(HCH6-1)intervention group(HCH6-1 intervention group)with 6 mice in each group,and compared with the sham group.The activation degree of microglia in each group was evaluated by immunofluorescence assay,and the expression of inflammatory factors(interleukin[IL]-1β,IL-18 and tumor necrosis factor-α[TNF-α])and inflammasome(NLRP3,ASC and Caspase-1)proteins in each group were detected by Western blotting.Results Compared with the sham group,Fpr1 expression increased on the first day after SCI,reached its peak on the third day,decreased on the fifth day,and decreased to the same level as the sham group on the seventh day.The results of immunofluorescence staining indicated that Fpr1 was mainly expressed in microglia.Compared with the SCI group,the activation of microglia in the HCH6-1 intervention group was significantly reduced,the expressions of inflammatory factors(IL-1β,IL-18 and TNF-α)and inflammasomes(NLRP3,ASC and Caspase-1)were significantly reduced.Conclusion Fpr1 can mediate the inflammatory response induced by microglia after SCI,and inhibition of Fpr1 may be a new therapeutic strategy to intervene the secondary injury after SCI.