The role of TLR4 in the recovery of sciatic nerve injury in C3H/HeJ mice

TANG Guoqing; XIE Sibin; SHEN Ruowu; MA Kai; WANG Fang; ZHU Lingyu; YAO Jia; DING Yingqiao; WANG Xuan; ZHANG Bei

doi:10.13431/j.cnki.immunol.j.20170146

Abstract：This study designed to investigate the impact of TLR4 mutation on sciatic nerve injury.C3H/HeJ mice (TLR4 mutation type) and C3H/HeN mice (wild type) were chosen and divide into C3H/HeJ injury group (HeJ),C3H/HeN injury group (HeN) and C3H/HeN control group (control).The model of sciatic nerve injury was constructed in sterile environment.Real-time quantitative PCR (qRT-PCR) is applied to detect the dynamic expressions of IL-1β,IL-6 and TNF-α in 6 h,12 h,24 h and 48 h post-operation,respectively;Western blot was used to measure the expression of P75NTR (p75 neurotrophin receptor) protein in 12 h and 24 h post-operation.After 1 week,2 weeks,4 weeks or 8 weeks of sciatic nerve injury in mice,hematoxylin-eosin staining (HE staining) was used to observe the pathological variations,while immunohistochemistry was used to detect growth-associated protein-43 (GAP-43),and p75NTR protein expression.Motor function recovery was evaluated by using sciatic nerve function index (SFI).qPCR showed that IL-1β and TNF-α expression of HeN group were significandy increased at 6 h,12 h and 24 h (P＜0.01) as compared with control group,while the change of the HeJ group was not obvious.The expression of TNF-α showed significant difference between HeN and HeJ group (P＜0.001).At 6 h,the expression of IL-6 in HeN group was significantly increased (P＜0.001) as compared with the control group.Western blotting showed that p75NTR protein expression in HeJ mice was significantly increased at 12 h or 24 h post sciatic nerve injury,as compared with the HeN group (P＜0.001);HE staining showed that lymphocyte expression and inflammatory response in HeJ mice was less,as compared with HeN mice.Immunohistochemical results showed that the expression of p75NTR and GAP43 in HeJ mice were significantly increased (P＜0.01),as compared with HeN mice;SFI results show that,SFI score of HeJ mice was relatively high and the nerve recovery was better in post-operation period,as compared with HeN mice.We can conclude that sciatic nerve injury model is successfully built in mutant mice,and the study reveal that TLR4 can speed up the sciatic nerve repair by interfering inflammatory factors,which provide a experimental theory basis for the clinical treatment of peripheral nerve injury.