Protective effect of infliximab on neurological function and its related mechanism in mice after traumatic brain injury / 中华神经医学杂志

ABSTRACT

Objective:To investigate the effect of infliximab (IFX) on neurological function in mice after traumatic brain injury (TBI) and the role of nuclear factor-κB (NF-κB)/inducible nitric oxide lyase (iNOS) signaling in it.Methods:Seventy-two healthy adult male C57BL/6 mice were randomly divided into sham-operated group, TBI group, and TBI+IFX group ( n=24). The mouse TBI models were established by controlled cortical impact method. IFX (dissolved in normal saline at a concentration of 2.5 mg/mL and a dose of 10 μg/g) was administered intraperitoneally into the mice of TBI+IFX group 30 min after modeling once daily for 3 d; mice in the sham-operated group and TBI group were given the same amount of saline intraperitoneally at the same time points for 3 d. Neurological deficits (Garcia scores) were assessed one, 3 and 7 d after modeling; blood-brain barrier permeability was detected by Evans blue staining, and brain tissue water content was measured by dry and wet weight method; Nissl staining was used to detect the percentage of injured neurons in brain tissues; the percentage of apoptotic neurons was detected by Tunel staining; immunofluorescent double-labeling was used to detect the expressions of caspase-3 and neuronal nuclear antigen (NeuN) in neurons; immunohistochemical staining was used to detect the microglia marker ionized calcium binding adaptor molecule-1 (IBa-1) expression; ELISA was used to detect the expressions of inflammatory factors (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, IL-6, interferon [IFN]-γ) and free radicals (oxygen free radicals [ROS], nitrogen free radicals [RNS]) in the brain tissues; and immunofluorescent staining and Western blotting were used to detect the expressions of nuclear factor (NF)-κB/inducible nitric oxide synthase (iNOS). Results:(1) One, 3 and 7 d after modeling, the Garcia scores showed significant differences among the three groups ( P<0.05); as compared with the TBI group, the TBI+IFX group had significantly increased Garcia scores 3 and 7 d after modeling ( P<0.05). (2) Three d after modeling, as compared with those in the TBI group, Evans blue leakage ([18.45±1.32] μg/g vs. [16.38±1.25] μg/g), brain water content ([81.56±0.96]% vs. [79.97±0.79]%), percentage of injured neurons ([79.50±5.85]% vs. [68.81±7.47]%), and percentage of apoptotic neurons ([41.93±7.49]% vs. [30.59±8.60]%) in mice of the TBI+IFX group were significantly deceased ( P<0.05). Three d after modeling, immunofluorescent double labeling showed that the relative caspase-3 expression in the TBI+IFX group (0.76±0.16) was significantly decreased as compared with the TBI group (1.11±0.23, P<0.05). Immunohistochemical staining and ELISA results showed that as compared with those in the TBI group, the Iba-1 staining scores, TNF-α, IL-1β, IL6 and IFN-γ levels, and ROS and RNS contents in TBI+IFX group were significantly decreased ( P<0.05). Immunofluorescent staining and Western blotting showed that as compared with the TBI group, the TBI+IFX group had significantly decreased expressions of NF-κB p65, iNOS and phosphorylated nuclear factor-κB inhibitor-α, and statistically inhibited nuclear translocation of NF-κB ( P<0.05). Conclusion:IFX can reduce inflammatory response and oxidative stress response, and play a neuroprotective role, which is related to its inhibition of downstream NF-κB/iNOS pathway activation.