甲酰基肽受体1促进创伤性脑损伤后小胶质细胞诱导的神经炎症

Formyl peptide receptor 1 potentiates microglia-induced neuroinflammation after traumatic brain injury

目的观察模式识别受体在创伤性脑损伤(TBI)后炎性反应中的作用,并探讨可能的调控机制。方法将成年C57小鼠按照随机数字表法随机分为假手术组(Sham组)和TBI组,每组各3只,分别将Sham组正常皮层组织和TBI后3 d损伤周围皮层组织进行转录组测序分析;将小鼠随机分为Sham组和4个不同时间点TBI组(术后6 h、1 d、3 d和7 d),每组各6只,通过蛋白质印迹法(Western blot)和免疫荧光检测Fpr1的表达变化情况;然后将小鼠随机分为Sham组、TBI组、TBI+溶剂组和TBI+HCH6-1(Fpr1抑制剂)干预组,每组各6只,通过Western blot、脑含水量测定和行为学检测等实验评估各组炎性反应和神经功能等。两组比较采用t检验;多组间比较采用单因素方差分析。结果TBI组损伤周围皮层组织Fpr1的蛋白表达水平在第3天高于Sham组最显著(相对表达量为2.480±0.331,t=7.757,P<0.01),且主要表达于小胶质细胞。TBI+HCH6-1(Fpr1抑制剂)干预组中炎症分子IL-1β、IL-18、TNF-α、Caspase-1和NLRP3的蛋白表达水平均低于TBI+溶剂组(t=2.161、4.245、2.992、5.945、4.409,P<0.05)。在行为学方面,TBI+HCH6-1(Fpr1抑制剂)干预组小鼠在第3天和第7天mNSS行为学评分低于TBI+溶剂组(t=4.183、3.162,P<0.05);TBI+HCH6-1(Fpr1抑制剂)干预组小鼠在第7天转角实验中左转%低于TBI+溶剂组(t=2.273,P<0.05);TBI+HCH6-1(Fpr1抑制剂)干预组小鼠在第7天挂线实验中停留时间长于TBI+溶剂组(t=3.123,P<0.05)。结论Fpr1促进TBI后小胶质细胞诱导的神经炎症,抑制Fpr1能够改善TBI后神经功能缺陷。

Objective To explore the role of pattern recognition receptors in the inflammatory response after traumatic brain injury(TBI),and to elucidate the possible mechanisms therein,providing a theoretical foundation for inhibiting neuroinflammation and alleviating secondary injury.Methods(1)Adult C57 mice were randomly divided into Sham group and TBI group,according to random number table method,with 3 mice in each group.The normal cortical tissue of Sham group and the damaged peripheral cortical tissue on the day 3 after TBI were analyzed by transcriptome sequencing.(2)Mice were randomly divided into Sham group and TBI group at 4 different time points(6 h,1st d,3rd d and 7th d after surgery),with 6 mice in each group and the expression of Fpr1 was detected by Western blotting and immunofluorescence.(3)The mice were randomly divided into Sham group,TBI group,TBI+Vehicle group and TBI+HCH6-1(Fpr1 inhibitor)intervention group,with 6 mice in each group.Western blotting,brain water content and behavioral tests were used to evaluate the inflammatory response and neurological function of each group.Two groups were compared using t-test;one-way ANOVA was used for comparison between multiple groups.Results The protein expression level of Fpr1 in the peri-injured cortical tissue of the TBI group was most significantly higher than that of the Sham group at day 3(relative expression 2.480±0.331,t=7.757,P<0.01),and was mainly expressed in microglia.inflammatory molecules IL-1β,IL-18,TNF-α,Caspase 1 and NLRP3 in the TBI+HCH6-1(Fpr1 inhibitor)intervention group had lower protein expression levels than in the TBI+Vehicle group(t=2.161,4.245,2.992,5.945,4.409,P<0.05).In terms of behavior,mice in the TBI+HCH6-1(Fpr1 inhibitor)intervention group had lower mNSS behavioral scores on days 3 and 7 than the TBI+Vehicle group(t=4.183,3.162,P<0.05);mice in the TBI+HCH6-1(Fpr1 inhibitor)intervention group had a lower%left turn in the corner-turning experiment on day 7 than the TBI+Vehicle group(t=2.273,P<0.05);mice in the TBI+HCH6-1(Fpr1 inhibitor)intervention group stayed longer in the hanging experiment on day 7 than the TBI+solvent group(t=3.123,P<0.05).Conclusion Fpr1 potentiates microglia-induced neuroinflammation after TBI,and the inhibition of Fpr1 can improve neurological function.