Wen-Sheng Qu

Tamoxifen attenuates inflammatory-mediated damage and improves functional outcome after spinal cord injury in rats

Tamoxifen has been found to be neuroprotective in both transient and permanent experimental ischemic stroke. However, it remains unknown whether this agent shows a similar beneficial effect after spinal cord injury (SCI), and what are its underlying mechanisms. In this study, we investigated the efficacy of tamoxifen treatment in attenuating SCI‐induced pathology. Blood–spinal cord barrier (BSCB) permeability, tissue edema formation, microglial activation, neuronal cell death and myelin loss were determined in rats subjected to spinal cord contusion. The results showed that tamoxifen, administered at 30 min post‐injury, significantly decreased interleukin‐1β (IL‐1β) production induced by microglial activation, alleviated the amount of Evans blue leakage and edema formation. In addition, tamoxifen treatment clearly reduced the number of apoptotic neurons post‐SCI. The myelin loss and the increase in production of myelin‐associated axonal growth inhibitors were also found to be significantly attenuated at day 3 post‐injury. Furthermore, rats treated with tamoxifen scored much higher on the locomotor rating scale after SCI than did vehicle‐treated rats, suggesting improved functional outcome after SCI. Together, these results demonstrate that tamoxifen provides neuroprotective effects for treatment of SCI‐related pathology and disability, and is therefore a potential neuroprotectant for human spinal cord injury therapy.

Inhibition of EGFR/MAPK signaling reduces microglial inflammatory response and the associated secondary damage in rats after spinal cord injury

BackgroundEmerging evidence indicates that reactive microglia-initiated inflammatory responses are responsible for secondary damage after primary traumatic spinal cord injury (SCI); epidermal growth factor receptor (EGFR) signaling may be involved in cell activation. In this report, we investigate the influence of EGFR signaling inhibition on microglia activation, proinflammatory cytokine production, and the neuronal microenvironment after SCI.MethodsLipopolysaccharide-treated primary microglia/BV2 line cells and SCI rats were used as model systems. Both C225 and AG1478 were used to inhibit EGFR signaling activation. Cell activation and EGFR phosphorylation were observed after fluorescent staining and western blot. Production of interleukin-1beta (IL-1β) and tumor necrosis factor alpha (TNFα) was tested by reverse transcription PCR and ELISA. Western blot was performed to semi-quantify the expression of EGFR/phospho-EGFR, and phosphorylation of Erk, JNK and p38 mitogen-activated protein kinases (MAPK). Wet-dry weight was compared to show tissue edema. Finally, axonal tracing and functional scoring were performed to show recovery of rats.ResultsEGFR phosphorylation was found to parallel microglia activation, while EGFR blockade inhibited activation-associated cell morphological changes and production of IL-1β and TNFα. EGFR blockade significantly downregulated the elevated MAPK activation after cell activation; selective MAPK inhibitors depressed production of cytokines to a certain degree, suggesting that MAPK mediates the depression of microglia activation brought about by EGFR inhibitors. Subsequently, seven-day continual infusion of C225 or AG1478 in rats: reduced the expression of phospho-EGFR, phosphorylation of Erk and p38 MAPK, and production of IL-1β and TNFα; lessened neuroinflammation-associated secondary damage, like microglia/astrocyte activation, tissue edema and glial scar/cavity formation; and enhanced axonal outgrowth and functional recovery.ConclusionsThese findings indicate that inhibition of EGFR/MAPK suppresses microglia activation and associated cytokine production; reduces neuroinflammation-associated secondary damage, thus provides neuroprotection to SCI rats, suggesting that EGFR may be a therapeutic target, and C225 and AG1478 have potential for use in SCI treatment.

Tamoxifen alleviates irradiation-induced brain injury by attenuating microglial inflammatory response in vitro and in vivo

Irradiation-induced brain injury, leading to cognitive impairment several months to years after whole brain irradiation (WBI) therapy, is a common health problem in patients with primary or metastatic brain tumor and greatly impairs quality of life for tumor survivors. Recently, it has been demonstrated that a rapid and sustained increase in activated microglia following WBI led to a chronic inflammatory response and a corresponding decrease in hippocampal neurogenesis. Tamoxifen, serving as a radiosensitizer and a useful agent in combination therapy of glioma, has been found to exert anti-inflammatory response both in cultured microglial cells and in a spinal cord injury model. In the present study, we investigated whether tamoxifen alleviated inflammatory damage seen in the irradiated microglia in vitro and in the irradiated brain. Irradiating BV-2 cells (a murine microglial cell line) with various radiation doses (2-10 Gy) led to the increase in IL-1 beta and TNF-alpha expression determined by ELISA, and the conditioned culture medium of irradiated microglia with 10 Gy radiation dose initiated astroglial activation and decreased the number of neuronal cells in vitro. Incubation BV-2 cells with tamoxifen (1 microM) for 45 min significantly inhibited the radiation-induced microglial inflammatory response. In the irradiated brain, WBI induced the breakdown of the blood-brain barrier permeability at day 1 post irradiation and tissue edema formation at day 3 post-radiation. Furthermore, WBI led to microglial activation and reactive astrogliosis in the cerebral cortex and neuronal apoptosis in the CA1 hippocampus at day 3 post-radiation. Tamoxifen administration (i.p., 5 mg/kg) immediately post radiation reduced the irradiation-induced brain damage after WBI. Taken together, these data support that tamoxifen can decrease the irradiation-induced brain damage via attenuating the microglial inflammatory response.

Inhibition of mTOR pathway restrains astrocyte proliferation, migration and production of inflammatory mediators after oxygen-glucose deprivation and reoxygenation.

Glial scar is a major impediment to axonal regeneration in central nervous system (CNS) disorders. Overcoming this physical and biochemical barrier might be crucial for axonal regeneration and functional compensation during the progression of CNS disorders. The mammalian target of rapamycin (mTOR) is an evolutionarily conserved serine/threonine kinase, involved in process of cell proliferation, migration, autophagy and protein synthesis. Rapamycin, an inhibitor of mTOR signaling, can exert neuroprotective effects in several CNS diseases. However, its role in the process of reactive astrogliosis including cell proliferation, migration and cytokine production after cerebral ischemia still remains largely unknown. In this study, we investigated the effects of mTOR blockade in cultured astrocytes exposed to oxygen-glucose deprivation/reoxygenation (OGD/R), a wildly used cellular ischemia model which mimics ideally cerebral ischemia model in vivo. We found that astrocytes became activated after OGD/R, characterized by change of astrocytic morphology, upregulation of GFAP expression, the increase number of Edu positive cells, and accompanied with phosphorylation of mTOR protein and its substrate S6K1. Rapamycin significantly inhibited mTOR signal pathway, suppressed proliferation of astrocytes via modulation of cell cycle progression. Moreover, rapamycin attenuated astrocytic migration and mitigated production of inflammatory factors such as TNF-α and iNOS induced by astrocytes exposed to OGD/R. Taken together, our findings indicated that mTOR blockade by rapamycin attenuates astrocyte migration, proliferation and production of inflammation mediators. We suggest that targeting mTOR pathway in astrocyte activation may represent a potentially new therapeutic strategy against deleterious neurotoxic processes of reactive astrogliosis in CNS disorders such as ischemic stroke.

Inhibiting epidermal growth factor receptor attenuates reactive astrogliosis and improves functional outcome after spinal cord injury in rats

As a physical barrier to regenerating axons, reactive astrogliosis is also a biochemical barrier which can secrete inhibitory molecules, including chondroitin sulfate proteoglycans (CSPGs) in the pathological mechanism of spinal cord injury (SCI). Thus, inhibition of astroglial proliferation and CSPG production might facilitate axonal regeneration after SCI. Recent studies have demonstrated that epidermal growth factor receptor (EGFR) activation triggers quiescent astrocytes into becoming reactive astrocytes and forming glial scar after CNS injury. In the present study, we investigated whether a specific EGFR inhibitor (AG1478) could attenuate the reactive astrogliosis and production of CSPGs, alleviate demyelination, and eventually enhance the functional recovery after SCI in rats. Our results showed that pEGFR immunoreactivity was up-regulated significantly post injury, mainly confined to astrocytes. Meanwhile, astrocytes near the injury site after SCI became activated obviously characterized by hypertrophic morphology and enhanced GFAP expression. However, administration of AG1478 remarkably reduced trauma induced-reactive astrogliosis and accumulation of CSPGs. Furthermore, the treatment with AG1478 also alleviated demyelination, increased expression of growth-associated proteins-43 (GAP-43) and improved hindlimb function after SCI. Therefore, the local blockade of EGFR in an injured area is beneficial to functional outcome by facilitating a more favorable environment for axonal regeneration in SCI rats.

Galectin-1 attenuates astrogliosis-associated injuries and improves recovery of rats following focal cerebral ischemia.

J. Neurochem. (2011) 116, 217–226.

Blocking epidermal growth factor receptor attenuates reactive astrogliosis through inhibiting cell cycle progression and protects against ischemic brain injury in rats

J. Neurochem. (2011) 119, 644–653.

Proliferation and Differentiation of Neural Stem Cells Are Selectively Regulated by Knockout of Cyclin D1

Although stem cells can proliferate and differentiate through the completion of cell cycle progression, little is known about the genes and molecular mechanisms controlling this process. Here, we investigated the effect of the inhibition of cell cycle by cyclin D1 gene knockout on proliferation and differentiation of neural stem cells (NSCs). Knockout of cyclin D1 induced the cultured neural stem cells arrested at the G0/G1 phase as detected by flow cytometry. Cyclin D1 knockout led to the apoptosis of NSCs and inhibited the differentiation into astrocytes without affecting the differentiation into neurons. We further demonstrated that a significant reduction of BrdU+ cells in the subgranular zone of the dentate gyrus and subventricular zone was found in cyclin D1 gene knockout (cyclin D1−/−) mice compared with cyclin D1+/+ and cyclin D1+/− mice. These observations demonstrated that cyclin D1 plays essential roles in the proliferation and differentiation of neural stem cells.

Endovascular thrombectomy versus medical treatment for large vessel occlusion stroke with mild symptoms: A meta-analysis

It remains controversial as to whether mechanical thrombectomy (MT) is safer and more beneficial in patients with large vessel occlusion stroke (LVOS) presenting with a National Institutes of Health Stroke Scale score ≤ 8. We therefore conducted a meta-analysis of the published data.We searched PubMed and Embase and pooled relevant data in the meta-analyses using fixed effects models. Only studies that directly compared best medical therapy alone (BMT) with MT were included. We used odds ratios to analyze the associations between MT and 90-day functional outcome (evaluated using the modified Rankin Scale (mRS)), mortality, and rates of symptomatic intracerebral hemorrhage (sICH) in patients with LVOS and minor symptoms. Five studies including a total of 581 patients met our inclusion criteria. A significant difference was found that the patients treated with MT were associated with improved 90-day mRS score (OR, 1.68; 95% CI, 1.08–2.61) compared with BMT group. There was no difference in 90-day mortality between the two groups. However, sICH occurred more frequently in the MT group than the BMT group (OR, 3.89; 95% CI, 1.83–8.27). Patients with LVOS with minor or mild symptoms who underwent primary thrombectomy had a significantly improved 90-day mRS score compared to those who received BMT alone. Meanwhile, the risk of sICH was higher in the MT group than that in BMT group. Future randomized clinical controlled trials evaluating the role of endovascular reperfusion for LVOS with minimal symptoms are warranted.

A Case of Subacute Combined Degeneration of the Spinal Cord with Infective Endocarditis

Background. Subacute combined degeneration (SCD) is a rare cause of demyelination of the dorsal and lateral columns of spinal cord and is a neurogenic complication due to cobalamin deficiency. Anemia of chronic disease (ACD) occurs in patients with acute or chronic immune activation, including infective endocarditis. It remains to be elucidated whether ACD patients are more sensitive to suffer from SCD. Little cases about SCD patients accompanied with ACD have been reported till now. Here we reported a 36-year-old man with SCD with a medical history of mitral inadequacy over 20 years, who was admitted and transported from another hospital to our hospital due to an 8-month history of gait disturbance, lower limb weakness and paresthesia, and loss of proprioception. Significant laboratory results and echocardiography suggest iron deficiency anemia and infective endocarditis (IE). The SCD diagnosis was confirmed by MRI, which showed selective demyelination in the dorsal and lateral columns of spinal cord. In conclusion, the ACD patients may suffer from SCD, which can be diagnosed by 3 Tesla magnetic resonance imaging.