Inhibiting endogenous tissue plasminogen activator enhanced neuronal apoptosis and axonal injury after traumatic brain injury.

Tissue plasminogen activator is usually used for the treatment of acute ischemic stroke, but the role of endogenous tissue plasminogen activator in traumatic brain injury has been rarely reported. A rat model of traumatic brain injury was established by weight-drop method. The tissue plasminogen activator inhibitor neuroserpin (5 µL, 0.25 mg/mL) was injected into the lateral ventricle. Neurological function was assessed by neurological severity score. Neuronal and axonal injuries were assessed by hematoxylin-eosin staining and Bielschowsky silver staining. Protein level of endogenous tissue plasminogen activator was analyzed by western blot assay. Apoptotic marker cleaved caspase-3, neuronal marker neurofilament light chain, astrocyte marker glial fibrillary acidic protein and microglial marker Iba-1 were analyzed by immunohistochemical staining. Apoptotic cell types were detected by immunofluorescence double labeling. Apoptotic cells in the damaged cortex were detected by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP-biotin nick-end labeling staining. Degenerating neurons in the damaged cortex were detected by Fluoro-Jade B staining. Expression of tissue plasminogen activator was increased at 6 hours, and peaked at 3 days after traumatic brain injury. Neuronal apoptosis and axonal injury were detected after traumatic brain injury. Moreover, neuroserpin enhanced neuronal apoptosis, neuronal injury and axonal injury, and activated microglia and astrocytes. Neuroserpin further deteriorated neurobehavioral function in rats with traumatic brain injury. Our findings confirm that inhibition of endogenous tissue plasminogen activator aggravates neuronal apoptosis and axonal injury after traumatic brain injury, and activates microglia and astrocytes. This study was approved by the Biomedical Ethics Committee of Animal Experiments of Shaanxi Province of China in June 2015.

AG490 ameliorates early brain injury via inhibition of JAK2/STAT3-mediated regulation of HMGB1 in subarachnoid hemorrhage.

High mobility group box 1 (HMGB1) is a classic damage-associated molecular pattern that has an important role in the pathological inflammatory response. In vitro studies have demonstrated that the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is involved in the regulation of HMGB1 expression, mediating the inflammatory response. Therefore, the purpose of the present study was to evaluate JAK2/STAT3 pathway involvement in the subarachnoid hemorrhage (SAH)-dependent regulation of HMGB1, using an in vivo rat model. A SAH model was established by endovascular perforation. Western blotting, immunohistochemistry and immunofluorescence were used to analyze HMGB1 expression after SAH. In addition, the effects of AG490 after SAH on JAK2/STAT3 phosphorylation, HMGB1 expression and brain damage were evaluated. The results of the present study demonstrated that JAK2/STAT3 was significantly phosphorylated (P<0.05) and the total HMGB1 protein level was significantly increased (P<0.05) after SAH. In addition, the cytosolic HMGB1 level after SAH demonstrated an initial increase followed by a decrease to the control level, while the nuclear HMGB1 level after SAH demonstrated the opposite trend, with an initial decrease and subsequent increase. AG490 administration after SAH significantly inhibited JAK2/STAT3 phosphorylation (P<0.05), suppressed the expression and translocation of HMGB1, reduced cortical apoptosis, brain edema and neurological deficits. These results demonstrated the involvement of the JAK2/STAT3 pathway in HMGB1 regulation after SAH.

Protection of FK506 against neuronal apoptosis and axonal injury following experimental diffuse axonal injury.

Diffuse axonal injury (DAI) is the most common and significant pathological features of traumatic brain injury (TBI). However, there are still no effective drugs to combat the formation and progression of DAI in affected individuals. FK506, also known as tacrolimus, is an immunosuppressive drug, which is widely used in transplantation medicine for the reduction of allograft rejection. Previous studies have identified that FK506 may play an important role in the nerve protective effect of the central nervous system. In the present study, apoptosis of neuronal cells was observed following the induction of experimental DAI. The results demonstrated that it was closely related with the upregulation of death­associated protein kinase 1 (DAPK1). It was hypothesized that FK506 may inhibit the activity of DAPK1 by inhibiting calcineurin activity, which may be primarily involved in anti­apoptosis following DAI induction. Through researching the expression of nerve regeneration associated proteins (NF­H and GAP­43) following DAI, the present study provides novel data to suggest that FK506 promotes axon formation and nerve regeneration following experimental DAI. Therefore, FK506 may be a potent therapeutic for inhibiting nerve injury, as well as promoting the nerve regeneration following DAI.

Etanercept alleviates early brain injury following experimental subarachnoid hemorrhage and the possible role of tumor necrosis factor-α and c-Jun N-terminal kinase pathway.

Cerebral inflammation plays a crucial role in early brain injury (EBI) after subarachnoid hemorrhage (SAH). This study investigated the effects of c-Jun N-terminal kinase (JNK) inhibitor SP600125, acetylcholine (Ach), etanercept, and anti-TNF-α on cellular apoptosis in the cerebral cortex and the hippocampus, in order to establish the role of JNK and TNF-α in EBI. The SAH model was established using an endovascular puncture protocol. The reliability of the EBI model was determined by phosphorylated-Bad (pBad) immunohistochemistry. Neurological scores were recorded and western blot was used to detect the expression of JNK and TNF-α, and TUNEL assay was used to mark apoptotic cells. The results showed that pBad positive cells were evenly distributed in the cerebral cortex at different time points. The highest expression of pBad was reached 1 day after SAH, and pJNK and TNF-α reached their peak expression at 2 days after SAH. SP600125, Ach, and etanercept significantly decreased the level of pJNK and TNF-α in the cerebral cortex and the hippocampus. In addition, SP600125 and etanercept reduced cellular apoptosis in the cerebral cortex and the hippocampus and significantly improved neurological scores at 2 days after SAH potentially via inhibition of the JNK-TNF-α pathway. Ach reduced cellular apoptosis only in the cerebral cortex. It is possible that JNK induces TNF-α expression, which in turn enhances JNK expression in EBI after SAH, leading to increased apoptosis in the cerebral cortex and the hippocampus. Thus, our results indicate that that etanercept may be a potential therapeutic agent to alleviate EBI.

Meta-analysis of the efficacy and safety of therapeutic hypothermia in children with acute traumatic brain injury.

OBJECTIVE: To evaluate the efficacy and safety of therapeutic hypothermia in children with acute traumatic brain injury (TBI). METHODS: A systematic literature review using PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang, VIP, and Chinese Biomedical Database was performed to retrieve studies of randomized controlled trials (RCTs) on therapeutic hypothermia for children with TBI published before March 2014. Data extraction and quality evaluation of RCTs were performed by 2 investigators independently. A meta-analysis was performed by RevMan 5.2.7. RESULTS: There were 7 RCTs comprising 442 children (218 in hypothermia group and 224 in normothermia group). Meta-analysis showed therapeutic hypothermia could increase mortality compared with the normothermia group (relative risk [RR] = 1.84, 95% confidence interval [CI] = 1.15-2.93, P = 0.01). On the Glasgow Outcome Scale (GOS), the following scores did not differ between the hypothermia group and normothermia group: 3-month GOS 4-5 (RR = 0.89, 95% CI = 0.68-1.16, P = 0.39), 3-month GOS 1-3 (RR = 1.19, 95% CI = 0.80-1.76, P = 0.39), 6-month GOS 4-5 (RR = 0.91, 95% CI = 0.78-1.07, P = 0.26), and 6-month GOS 1-3 (RR = 1.18, 95% CI = 0.88-1.59, P = 0.27). Hypothermia did not increase the rate of pneumonia (RR = 0.84, 95% CI = 0.63-1.12, P = 0.23) or bleeding (RR = 0.94, 95% CI = 0.39-2.26, P = 0.89), but the incidence of arrhythmias was higher in the hypothermia group (RR = 2.60, 95% CI = 1.06-6.41, P = 0.04). CONCLUSIONS: No benefit of therapeutic hypothermia in children with TBI is shown in this study; therapeutic hypothermia may increase the risk of mortality and arrhythmia. There is no evidence that therapeutic hypothermia improves prognosis of children with TBI; there is also no evidence that therapeutic hypothermia increases the risk of pneumonia and coagulation dysfunction. These results are limited by the quality of the included studies and need to be considered with caution. Further large-scale, well-designed RCTs on this topic are needed.