Kaijie Wang

Neuroprotective effect of ceftriaxone in a rat model of traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of mortality and disability in children and young adults worldwide. Neurologic impairment is caused by both immediate brain tissue disruption and post-injury cellular and molecular events that worsen the primary neurologic insult. The β-lactam antibiotic ceftriaxone (CTX) has been reported to induce neuroprotection in animal models of diverse neurologic diseases via up-regulation of GLT-1. However, no studies have addressed the neuroprotective role of CTX in the setting of TBI, and whether the mechanism is involved in the modulation of neuronal autophagy remains totally unclear. The present study was designed to determine the hypothesis that administration of CTX could significantly enhance functional recovery in a rat model of TBI and whether CTX treatment could up-regulate GLT-1 expression and suppress post-TBI neuronal autophagy. The results demonstrated that daily treatment with CTX attenuated TBI-induced brain edema and cognitive function deficits in rats. GLT-1 is down-regulated following TBI and this phenomenon can be reversed by treatment of CTX. In addition, we also found that CTX significantly reduced autophagy marker protein, LC3 II, in hippocampus compared to the TBI group. These results suggest that CTX might provide a new therapeutic strategy for TBI and this protection might be associated with up-regulation of GLT-1 and suppression of neuronal autophagy.

Resveratrol attenuates neuronal autophagy and inflammatory injury by inhibiting the TLR4/NF-κB signaling pathway in experimental traumatic brain injury

Previous research has demonstrated that traumatic brain injury (TBI) activates autophagy and a neuroinflammatory cascade that contributes to substantial neuronal damage and behavioral impairment, and Toll-like receptor 4 (TLR4) is an important mediator of this cascade. In the present study, we investigated the hypothesis that resveratrol (RV), a natural polyphenolic compound with potent multifaceted properties, alleviates brain damage mediated by TLR4 following TBI. Adult male Sprague Dawley rats, subjected to controlled cortical impact (CCI) injury, were intraperitoneally injected with RV (100 mg/kg, daily for 3 days) after the onset of TBI. The results demonstrated that RV significantly reduced brain edema, motor deficit, neuronal loss and improved spatial cognitive function. Double immunolabeling demonstrated that RV decreased microtubule-associated protein 1 light chain 3 (LC3), TLR4-positive cells co-labeled with the hippocampal neurons, and RV also significantly reduced the number of TLR4-positive neuron-specific nuclear protein (NeuN) cells following TBI. Western blot analysis revealed that RV significantly reduced the protein expression of the autophagy marker proteins, LC3II and Beclin1, in the hippocampus compared with that in the TBI group. Furthermore, the levels of TLR4 and its known downstream signaling molecules, nuclear factor-κB (NF-κB), and the inflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor (TNF)-α were also decreased after RV treatment. Our results suggest that RV reduces neuronal autophagy and inflammatory reactions in a rat model of TBI. Thus, we suggest that the neuroprotective effect of RV is associated with the TLR4/NF-κB signaling pathway.

The effects of BMSCs transplantation on autophagy by CX43 in the hippocampus following traumatic brain injury in rats

Traumatic brain injury (TBI) can initiate a series of complicated pathological events, and induce various types of neuronal cell death including autophagy and apoptosis. Currently, the treatment of TBI is one of the main challenges in neurobiology. In this regard, the administration of bone marrow stromal cells (BMSCs) represents a novel treatment modality for TBI. However, the protective mechanism of BMSCs was unknown in the TBI. The aim of the present study was to assess the effects of BMSCs on connexin 43(CX43) and autophagy in the hippocampus following TBI in rats. A rat model of TBI was created using a modified weight-drop device. Double-membrane structures in the process of autophagy formation were frequently observed in injured brain by electron microscopy. The levels of autophagic pathway associated proteins and CX43 were also detected by western blot analysis. Specifically, immunoblotting results showed that BMSCs treatment after TBI could down-regulate light chain 3 (LC3), Beclin-1 and CX43 expression in the hippocampus. Taken together, our results demonstrated that BMSCs were able to significantly suppress TBI-induced autophagy activity, and the potential mechanism by regulating CX43 levels.

Bone Marrow Mesenchymal Stem Cell Transplantation Increases GAP-43 Expression via ERK1/2 and PI3K/Akt Pathways in Intracerebral Hemorrhage

Background/Aims: Intracerebral hemorrhage (ICH) occurs in hypertensive patients and results in high rates of mortality and disability. This study determined whether bone marrow mesenchymal stem cell (BMSC) transplantation affects axonal regeneration and examined the underlying mechanisms after the administration of PD98059 (p-ERK1/2 inhibitor) or/ and LY294002 (PI3K inhibitor). The hypothesis that was intended to be tested was that BMSC transplantation regulates the expression of growth-associated protein-43 (GAP-43) via the ERK1/2 and PI3K/Akt signaling pathways. Methods: Seventy-five male rats (250–280 g) were subjected to intracerebral blood injection and then randomly received a vehicle, BMSCs, PD98059 or LY294002 treatment. Neurological deficits were evaluated prior to injury and at 1, 3 and 7 days post-injury. The expression of GAP-43, Akt, p-Akt, ERK1/2, and p-ERK1/2 proteins was measured by western blot analysis. Results: BMSC transplantation attenuated neurological deficits 3-7 days post-ICH. The expression of GAP-43 was increased 3 days following BMSC transplantation. However, this increase was inhibited by either PD98059 or LY294002 treatment. Treatment with both PD98059 and LY294002 was more effective than was treatment with an individual compound. Conclusion: BMSC transplantation could attenuate neurological deficits and activate axonal regeneration in this rat ICH model. The protective effects might be associated with increased GAP-43 expression by activating both the ERK1/2 and PI3K/Akt signaling pathways.

Induction of the Vitamin D Receptor Attenuates Autophagy Dysfunction-Mediated Cell Death Following Traumatic Brain Injury

Background/Aims: Traumatic brain injury (TBI) is a major public health problem in the world and causes high rates of mortality and disability. Recent evidence suggests that vitamin D (VD) has neuroprotective actions and can promote function recovery after TBI. In vitro and in vivo studies have demonstrated that autophagy could be enhanced following supplementation with an active metabolite of VD (calcitriol). However, it is unclear whether autophagy participates in the protective effects of calcitriol after TBI. To test this hypothesis, we examined the protective effects of calcitriol on TBI-induced neurological impairment and further investigated whether calcitriol could modulate autophagy dysfunction-mediated cell death in the cortex region of rat brain. Methods: Eighty-five male rats (250-280 g) were randomly assigned to sham (n=15), TBI model (TBI, n=35) and calcitriol treatment (calcitriol, n=35) groups. Rats were injected intraperitoneally with calcitriol (1 µg/kg) at 30 min, 24 h and 48 h post-TBI in the calcitriol group. The lysosomal inhibitor, chloroquine (CQ), was used to evaluate autophagic flux in the TBI and calcitriol groups. Neurological functions were evaluated via the modified neurological severity score test at 1-7 days after TBI or sham operation, and the terminal deoxynucleotidyl transferase-mediated FITC-dUTP nick-end labeling method was used to evaluate the ability of calcitriol to inhibit apoptosis. The expression of VDR, LC3 and p62 proteins was measured by western blot analysis at 1, 3 and 7 days post-injury Results: Calcitriol treatment attenuated mNSS at 2-7 days post-TBI (P < 0.05 versus TBI group). Calcitriol dramatically increased VDR protein expression compared with the untreated counterparts at 1, 3 and 7 days post-TBI (P < 0.05). The rate of apoptotic cells in calcitriol-treated rats was significantly reduced compared to that observed in the TBI group (P < 0.05). The LC3II/LC3I ratio was decreased in the cortex region at 1, 3 and 7 days post-TBI in rats treated with calcitriol (p < 0.05 versus TBI group), and the p62 expression was also attenuated (p < 0.05 versus TBI group). The LC3II/LC3I ratio in the calcitriol group was significantly increased when pretreated with CQ (P < 0.05). Conclusion: Calcitriol treatment activated VDR protein expression and attenuated neurological deficits in this rat TBI model. The protective effects might be associated with the restoration of autophagy flux and the decrease in apoptosis in the cortex region of rat brain.

Intraparenchymal treatment with bone marrow mesenchymal stem cell-conditioned medium exerts neuroprotection following intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a life-threatening type of stroke. Previous studies have reported that bone marrow mesenchymal stem cells (BMSCs) may exert beneficial effects on the treatment of ICH. However, it remains unknown whether the neuroprotection exerted by BMSCs on ICH is due to the differentiation of BMSCs, or the trophic factors secreted into their conditioned medium (CM). In addition, growth‑associated protein‑43 (GAP‑43) is a protein associated with neurite extension, which may be considered a prospective therapeutic target in the treatment of ICH. The present study investigated whether administration of BMSC‑CM could be considered as an alternative to the established treatment of direct BMSC transplantation; in addition, the underlying mechanisms were evaluated. Neurological function tests, brain water content, reverse transcription ‑quantitative polymerase chain reaction and western blotting were used in present study. The current study indicated that the neuroprotective effects of BMSC implantation and BMSC-CM treatment are similar, and that both decrease the severity of post‑ICH cerebral edema, as well as improving neurological functions. At the molecular level, treatment with BMSC‑CM resulted in a marked elevation in the expression of GAP‑43 and interleukin (IL)‑10, in addition to a significant reduction in the expression levels of IL‑1β, tumor necrosis factor‑α and IL‑6. Following application of a phosphorylated‑extracellular signal‑regulated kinase (ERK1/2) inhibitor, PD98059, in a BMSC‑CM rat model, the mRNA and protein expression levels of GAP‑43 were significantly attenuated. Therefore, the findings of the present study demonstrated that treatment with BMSC‑CM may be an alternative to direct BMSC transplantation in a rat model of ICH. The mechanism underlying BMSC‑CM‑mediated neuroprotection may be associated with anti-inflammatory effects, as well as activation of GAP‑43 transcription and expression through ERK‑1/2 phosphorylation. Therefore, the ERK-1/2-GAP-43 signaling pathway may be considered a potential novel application target of BMSC‑CM for the treatment of neurological diseases.