Effect Of Infliximab Combinated With Methylprednisolone On Expression Of NF-κB, TRADD And FADD In A Rat Model Of Acute Spinal Cord Injury

Objective:Investigate the effects of infliximab, methyl prednisolone (MP) and the combination of these two agents on expression of NF-κB(nuclear factor Kappa B), TRADD(Tumor necrosis factor receptor associated death domain) and FADD(Fas associated death domain) in a rat model of acute spinal cord injury(ASCI), confirm the therapeutic efficacy of infliximab combinated with methylprednisolone(MP) in the treatment of rat spinal cord injury.Methods:90 adult male Sprague Dawley rats with 300-350g body weight were allocated randomly into six groups as follows:(1) normal control group(Group NC, n=15); (2) sham-operation group(Group SO, only received laminectomy operation, n=15), (3) SCI+ placebo group(Group NS, n=15); (4) SCI+ MP group(Group MP, received 30mg/kg of MP intraperitoneally immediately after ASCI, n=15); (5) SCI+infliximab group(Group IN, received 5mg/kg of infliximab intraperitoneally immediately after ASCI, n=15);(6)SCI+Infliximab +MP group(Group I+M, received both 5 mg/kg of infliximab and 30 mg/kg of MP intraperitoneally immediately after SCI, n=15). Allen's weight drop method was used to establish the rat model of ASCI at T10 section. We applied BBB locomotor rating scale in this study to assess the hindlimb motor functional score for 5 rat model of ASCI in each group. The other rat models of ASCI in each group were sacrificed to collect the spinal cord tissue samples from the injured segment at the time point of 24th hours after SCI, 5 samples of which in each group were prepared for immunohistochemistry staining to assay the expression of NF-κB, TRADD and FADD, the other 5 samples in each group were used to evaluate the expression of NF-κB mRNA, TRADD mRNA ,FADD mRNA.Results:(1)BBB motor function score assessment:The BBB score was dropped dramatically right after ASCI and then gradually increased afterwards in the treatment group. The score of group IN, group MP and group I+M was significantly higher than group NS at 14th, 21th days after ASCI (p<0.05); moreover, the score of group I+M was significantly higher than group MP and group IN at the same days (p<0.05)(2) Immunohistochemistry assessment:The amounts of NF-κB, TRADD and FADD positive cell in group IN,Group MP and Group I+M were less than Group NS at the time point of 24th hour after ASCI (p<0.05); moreover, there were less NF-κB, TRADD and FADD positive cells in Group I+M than Group IN and Group MP at the same time point (p<0.05).(3)RT-PCR assessment:The expression level of NF-κB mRNA in Group IN, Group MP and Group I+M was lower than Group NS at the time point of 24th hour after ASCI (p<0.05),the same as FADD mRNA and TRADD mRNA. Meanwhile, Group I+M has lower NF-κB mRNA expression level, FADD mRNA expression level and TRADD mRNA expression level than Group MP and group IN at the time point of 24th hour after ASCI(p<0.05).Conclusions:(1)Both infliximab and methylprednisolone can lower the expression of NF-κB, TRADD and FADD in the rat ASCI model. The two agents can attenuate the severity of rat ASCI and improve the locomotor function of rat ASCI model.(2) Infliximab combinated with methylprednisolone exhibit more powerful ability to reduce the expression of NF-κB, TRADD and FADD in rat ASCI model, moreover, the combination of these two agents has stronger potential of attenuating the severity of ASCI and improving the locomotor function in rat ASCI model.