Annexin A1 protects against traumatic spinal cord injuries by modulating microglia/macro-phage polarization via FPR2/ALX-dependent AMPK-mTOR pathway
Objective To investigate whether annexin A1(ANXA1)improves traumatic spinal cord injuries(SCIs)by activating the G protein-coupled formyl peptide receptor type 2/lipoxin A4 receptor(FPR2/ALX)-de-pendent adenosine monophosphate activated protein kinase/mammalian target of rapamycin(AMPK/mTOR)pathway.Methods Twenty-four male SD rats of 10-week old were randomly divided into sham group(group A),SCI group(group B),SCI+Ac2-26 group(treated by mimetic peptide of ANXA1,group C)and SCI+Ac2-26+WRW4 group(an-tagonism of ANXA1 role,group D),with 6 rats in each group.On the third day before modeling,rats in group C were injected with 1 mg/kg Ac2-26 via the subarachnoid space of T10 segment,those in group D were injected with 1 mg/kg Ac2-26 and 2.2 mg/kg WRW4 while others in groups A and B with equivalent normal saline via the same segment.The SCI model was established by a spinal cord percussion device(height of 6 cm and weight of 10 g).The motor function of the rats was detected by Basso-Beatie-Bresnahan(BBB)score,and the level of reactive oxygen species(ROS)in the spinal tissue was detected by a ROS kit.The levels of TNF-α,IL-1β and IL-6 in the spinal cord tissue were detected by ELISA,while the expression levels of adenosine monophosphate activated protein kinase(AMPK),phosphorylated AMPK(p-AMPK),mammalian target of rapamycin(mTOR),phosphorylated mTOR(p-mTOR),mi-crotubule-associated light chain protein 3(LC3)and selective autophagy adaptor protein 1(p62)were detected by western blot.Results Compared with group A,the BBB score of group B was significantly decreased(P＜0.05),indi-cating success modeling;compared with group B,the BBB score of group C was significantly increased,indicating a protection role of the ANXA1;compared with group C,the BBB score of rats in group D was significantly increased,indicating an antagonism effect(groupsB-D:7.8±1.9vs.16.4±2.5 vs.10.1±1.5,both P＜0.05).Other variables showed a similar trend.Comparison between groups A and B,B and C,C and D showed significantly lower levels in groups A and C(all P＜0.05)in terms of ROS(groups B-D,152.33％±26.56％vs.106.00±22.76％vs.133.01％±28.70％),TNF-α(ng/g,groups B-D,490.77±13.50 vs.268.19±10.94 vs.394.20±15.24),IL-6(ng/g,groups B-D,356.48±13.20 vs.194.23±11.60 vs.305.77±12.92)and IL-1β(ng/g,groups B-D,334.65±9.73 vs.153.15±11.61 vs.258.74±10.02).As for the autophagy-related proteins,group C also showed the best results compared to groups B and D respectively(all P＜0.05),with significantly up-regulated p-AMPK/AMPK(groups B-D,0.32±0.06 vs.0.53±0.09 vs.0.43±0.08)and LC3-Ⅱ/Ⅰ(groups B-D,0.21±0.04 vs.0.66±0.08 vs.0.57±0.06)and down-regulated p-mTOR/mTOR(groups B-D,1.38±0.14 vs.0.76±0.06 vs.1.22±0.12)and p62(1.27±0.09 vs.0.79±0.06 vs.1.10±0.11).Conclusion ANXA1 can protect against SCIs,which may be mediated by activation of FPR2/ALX-dependent AMPK/mTOR pathways to up-regulate the autophagy level and inhibit ROS and release of inflammato-ry mediators.
Spinal cord injuriesAnnexin A1Adenosine monophosphate activated protein kinaseMamma-lian target of rapamycinAutophagy
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