针灸对阿尔茨海默病大鼠的治疗作用及相关信号通路研究

目的 研究针灸对阿尔茨海默病大鼠的治疗作用及相关信号通路。方法 取40只SD大鼠,随机分为对照组(正常大鼠,不处理)、假手术组(大鼠双侧海马CA1区注射等量生理盐水)、模型组(建立阿尔茨海默病模型)、干预组(建立阿尔茨海默病模型+针灸),每组各10只。取各组大鼠脑组织,经苏木精-伊红染色行病理学检查;比较各组大鼠脑皮层区Janus激酶2(JAK2)、信号转导子和转录激活子3(STAT3)和炎性细胞因子白细胞介素1 (IL-1)、白细胞介素6(IL-6)阳性细胞数比率;采用免疫印迹法检测大鼠脑皮层区JAK2和STAT3蛋白表达情况。结果 病理学检查提示,模型组和干预组大鼠均出现不同程度的病理改变,且干预组的病理损伤程度明显轻于模型组。模型组、干预组大鼠脑皮层区JAK2、STAT3、IL-1和IL-6阳性细胞数比率较对照组、假手术组均明显升高(P <0. 01);干预组大鼠脑皮层区JAK2、STAT3、IL-1和IL-6阳性细胞数比率较模型组明显下降(P <0. 01)。免疫印迹法检测可知,相比对照组、假手术组,模型组、干预组大鼠脑皮层区JAK2和STAT3蛋白表达水平均明显升高(P <0. 01);相比模型组,干预组大鼠脑皮层区JAK2和STAT3蛋白表达水平均明显下降(P <0. 01)。结论 针灸治疗可有效减轻阿尔茨海默病大鼠脑损伤,其原因可能在于针灸治疗可下调JAK2和STAT3蛋白表达,阻滞JAK2/STAT3信号通路的异常活化,抑制炎性细胞因子的表达,从而可抑制慢性炎症反应的进展,减轻病情程度,起到良好的治疗作用。     

Periventricular demyelination and axonal pathology is associated with subependymal virus spread in a murine model for multiple sclerosis

Objectives: Theiler's murine encephalomyelitis virus (TMEV) infection of mice is a widely used animal model for demyelinating disorders, such as multiple sclerosis (MS). The aim of the present study was to identify topographical differences of TMEV spread and demyelination in the brain of experimentally infected susceptible SJL/J mice and resistant C57BL/6 mice. Methods: Demyelination was confirmed by Luxol fast blue and cresyl violet staining and axonal damage by neurofilament-specific and β-amyloid precursor protein-specific immunohistochemistry. Viral dissemination within the central nervous system (CNS) was quantified by immunohistochemistry and in situ hybridization. Further, the phenotype of infected cells was determined by confocal laser scanning microscopy. Results: An early transient infection of periventricular cells followed by demyelination and axonopathies around the fourth ventricle in SJL/J mice was noticed. Periventricular and brain stem demyelination was associated with a predominant infection of microglia/macrophages and oligodendrocytes. Conclusions: Summarized, the demonstration of ependymal infection and subjacent spread into the brain parenchyma as well as regional virus clearance despite ongoing demyelination and axonal damage in other CNS compartments allows new insights into TME pathogenesis. This novel aspect of TMEV CNS interaction will enhance the understanding of region-specific susceptibilities to injury and regenerative capacities of the brain in this MS model.     

Inhibitors of poly(ADP-ribose) polymerase modulate signal transduction pathways and secondary damage in experimental spinal cord trauma

Poly(ADP-ribose) polymerase (PARP), a nuclear enzyme activated by strand breaks in DNA, plays an important role in the tissue injury associated with stroke and neurotrauma. The aim of our study was to evaluate the therapeutic efficacy of in vivo inhibition of PARP in an experimental model of spinal cord trauma, which was induced by the application of vascular clips (force of 24g) to the dura via a four-level T5-T8 laminectomy. Spinal cord injury in mice resulted in severe trauma characterized by edema, neutrophil infiltration (measured as an increase in myeloperoxidase activity), and apoptosis (measured by terminal deoxynucleotidyltransferase-mediated UTP end labeling coloration). Infiltration of spinal cord tissue with neutrophils was associated with a marked increase in immunoreactivity for poly(ADP-ribose) (PAR), index of PARP activation, in the spinal cord tissue. These inflammatory events were associated with the activation of nuclear factor-kappaB (NF-kappaB) at 4 h after spinal cord damage. Treatment of the mice with the PARP inhibitors 3-aminobenzamide (3-AB) or 5-aminoisoquinolinone (5-AIQ) significantly reduced the degree of 1) spinal cord inflammation and tissue injury (histological score), 2) PAR formation, 3) neutrophil infiltration, and 4) apoptosis. Treatment with these PARP inhibitors also reduced DNA binding of NF-kappaB and inhibitory kappaB degradation. In a separate set of experiments, we have also demonstrated that PARP inhibitors significantly ameliorated the recovery of limb function (evaluated by motor recovery score). Taken together, our results clearly demonstrate that treatment with PARP inhibitors reduces the development of inflammation and tissue injury events associated with spinal cord trauma.     

银杏叶提取物EGb761对大鼠脊髓损伤后神经损伤恢复的影响

目的研究银杏叶提取物EGb761对大鼠脊髓损伤后神经损伤恢复的作用。方法 SD大鼠120只,随机分为假手术组、损伤对照组、甲基强的松龙（MP）治疗组和EGb761治疗组,每组30只。用改良Allen法建立脊髓损伤的动物模型。采用斜板试验法和BBB行为学评分观察大鼠脊髓损伤后神经功能的恢复情况;HE染色观察脊髓大体组织结构变化;采用酶联免疫吸附试验（ELISA）法测定脊髓组织中IL-10的含量。结果与损伤对照组比较,MP治疗组及EGb761治疗组大鼠术后7d和14 d临界角度显著增加、BBB评分显著升高、大鼠脊髓组织中IL-10的含量显著增高。HE染色显示,损伤对照组脊髓组织发生出血、水肿、坏死、轴突脱髓鞘改变以及炎症细胞浸润和胶质细胞反应,MP治疗组及EGb761治疗组术后7 d脊髓组织水肿、炎症反应减轻,神经元变性坏死不明显。结论 EGb761能减轻受伤脊髓的继发性损伤,对大鼠脊髓损伤后神经损伤恢复具有促进作用。     

银杏叶提取物EGb761对大鼠脊髓损伤后神经损伤恢复的影响

目的研究银杏叶提取物EGb761对大鼠脊髓损伤后神经损伤恢复的作用。方法 SD大鼠120只,随机分为假手术组、损伤对照组、甲基强的松龙(MP)治疗组和EGb761治疗组,每组30只。用改良Allen法建立脊髓损伤的动物模型。采用斜板试验法和BBB行为学评分观察大鼠脊髓损伤后神经功能的恢复情况;HE染色观察脊髓大体组织结构变化;采用酶联免疫吸附试验(ELISA)法测定脊髓组织中IL-10的含量。结果与损伤对照组比较,MP治疗组及EGb761治疗组大鼠术后7d和14 d临界角度显著增加、BBB评分显著升高、大鼠脊髓组织中IL-10的含量显著增高。HE染色显示,损伤对照组脊髓组织发生出血、水肿、坏死、轴突脱髓鞘改变以及炎症细胞浸润和胶质细胞反应,MP治疗组及EGb761治疗组术后7 d脊髓组织水肿、炎症反应减轻,神经元变性坏死不明显。结论 EGb761能减轻受伤脊髓的继发性损伤,对大鼠脊髓损伤后神经损伤恢复具有促进作用。     

Coexpression of class I major histocompatibility antigen and viral RNA in central nervous system of mice infected with Theiler's virus: a model for multiple sclerosis.

Chronic infection of susceptible strains of mice with Theiler's murine encephalomyelitis virus (TMEV) results in central nervous system (CNS) demyelination similar to multiple sclerosis. Demyelination induced by TMEV is mediated, in part, by class I-restricted CD8+ T lymphocytes. For these T cells to function, they must recognize virus-infected CNS targets in the presence of class I major histocompatibility complex (MHC) antigen. Therefore, we studied in vivo expression of class I MHC antigen and viral antigen-RNA in prototypic mouse strains that are susceptible (SJL/J) or resistant (C57BL/10SNJ) to TMEV-induced demyelination. In brains of resistant mice, viral antigen-RNA expression peaked on day 3 after infection and was effectively diminished by day 5 such that few virus-infected cells were ever detected in the spinal cord. In contrast, susceptible mice demonstrated delay in clearance of TMEV from the brain and a subsequent increase and persistence of viral antigen-RNA in the spinal cord for as long as 277 days. Viral infection resulted in "upregulation" of class I MHC expression in the CNS. Class I MHC antigens were expressed as early as 1 day after infection in the choroid plexus of both strains of mice before detection of viral antigen or inflammation. In resistant mice, class I MHC expression predominated in the gray matter of the brain and spinal cord on day 7 after infection but returned to undetectable levels by day 28. In susceptible mice, class I MHC expression in the CNS persisted and was intense in the white matter of the spinal cord throughout chronic infection and demyelination. No class I MHC expression was detected in the CNS of uninfected mice. Coexpression of viral RNA and class I MHC antigen was demonstrated in CNS cells by using simultaneous in situ hybridization and immunoperoxidase technique. These results support the hypothesis that a class I-restricted immune response directed against virus-infected cells may be important in the mechanism of demyelination.     

Assessment of lesion pathology in a new animal model of MS by multiparametric MRI and DTI

Magnetic resonance imaging (MRI) is the gold standard for the detection of multiple sclerosis (MS) lesions. However, current MRI techniques provide little information about the structural features of a brain lesion with inflammatory cell infiltration, demyelination, gliosis, acute axonal damage and axonal loss. To identify methods for a differentiation of demyelination, inflammation, and axonal damage we developed a novel mouse model combining cuprizone-induced demyelination and experimental autoimmune encephalomyelitis. MS-like brain lesions were assessed by T1-weighted, T2-weighted, and magnetization transfer MRI as well as by diffusion tensor imaging (DTI). T2-weighted MRI differentiated control and diseased mice, while T1-weighted MRI better reflected the extent of inflammation and axonal damage. In DTI, axonal damage and cellular infiltration led to a reduction of the axial diffusivity, whereas primary demyelination after cuprizone treatment was reflected by changes in radial but not axial diffusivity. Importantly, alterations in radial diffusivity were less pronounced in mice with demyelination, inflammation, and acute axonal damage, indicating that radial diffusivity may underestimate demyelination in acute MS lesions. In conclusion, the combined information from different DTI parameters allows for a more precise identification of solely demyelinated lesions versus demyelinated and acutely inflamed lesions. These findings are of relevance for offering individualized, stage-adapted therapies for MS patients.     

Leptin enhances NMDA-induced spinal excitation in rats: A functional link between adipocytokine and neuropathic pain

Recent studies have shown that leptin (an adipocytokine) played an important role in nociceptive behavior induced by nerve injury, but the cellular mechanism of this action remains unclear. Using the whole-cell patch-clamp recording from rat’s spinal cord slices, we showed that superfusion of leptin onto spinal cord slices dose-dependently enhanced N-methyl-d-aspartate (NMDA) receptor-mediated currents in spinal cord lamina II neurons. At the cellular level, the effect of leptin on spinal NMDA-induced currents was mediated through the leptin receptor and the JAK2/STAT3 (but not PI3K or MAPK) pathway, as the leptin effect was abolished in leptin receptor-deficient (db/db) mice and inhibited by a JAK/STAT inhibitor. Moreover, we demonstrated in naïve rats that a single intrathecal administration of leptin enhanced spontaneous biting, scratching, and licking behavior induced by intrathecal NMDA and that repeated intrathecal administration of leptin elicited thermal hyperalgesia and mechanical allodynia, which was attenuated by the noncompetitive NMDA receptor antagonist MK-801. Intrathecal leptin also upregulated the expression of NMDA receptors and pSTAT3 within the rat’s spinal cord dorsal horn, and intrathecal MK-801 attenuated this leptin effect as well. Our data demonstrate a relationship between leptin and NMDA receptor-mediated spinal neuronal excitation and its functional role in nociceptive behavior. Since leptin contributes to nociceptive behavior induced by nerve injury, the present findings suggest an important cellular link between the leptin’s spinal effect and the NMDA receptor-mediated cellular mechanism of neuropathic pain.     

Potential of olfactory ensheathing cells for cell-based therapy in spinal cord injury

Contusive spinal cord injury (SCI) results in a complex lesion that includes cellular and axonal loss, microglia and macrophage activation, and demyelination. These changes result in permanent neurological deficits in people with SCI and in high financial costs to society. Unlike the peripheral nervous system (PNS), in which axonal regeneration can occur, axonal regeneration in the central nervous system (CNS) is extremely limited. This limited regeneration is thought to result from a lack of a permissive environment and from active inhibitory molecules that are present in the CNS but minimal in the PNS. Currently, cell transplantation approaches are among several experimental strategies being investigated for the treatment of SCI. In the olfactory system, a specialized glial cell called the olfactory ensheathing cell (OEC) has been shown to improve functional outcome when transplanted into rodents with SCI, and clinical studies transplanting OECs into patients with SCI are ongoing in China, Portugal, and other sites. Yet, a number of controversial issues related to OEC biology and transplantation must be addressed to understand the rationale and expectations for OEC cell therapy approaches in SCI. This review provides information on these issues for spinal cord medicine clinicians.     

Spinal leptin contributes to the pathogenesis of neuropathic pain in rodents

Pain after nerve injury, a phenomenon referred to as neuropathic pain, is a debilitating clinical condition, but the underlying mechanisms remain unclear. As leptin, an adipocytokine produced mainly by nonneuronal tissue, has been implicated in the regulation of neuronal functions, we examined the role of leptin in neuropathic pain using a rat model of the condition chronic constriction sciatic nerve injury (CCI). We report that leptin critically contributed to pain behaviors following CCI. Specifically, spinal administration of a leptin antagonist prevented and reversed neuropathic pain behaviors in rats. Further examination revealed that levels of both leptin and the long form of the leptin receptor (Ob-Rb) were substantially increased within the ipsilateral spinal cord dorsal horn after peripheral nerve injury. Mechanistic studies showed that leptin upregulated the expression of both the spinal NMDA receptor and IL-1β through the JAK/STAT pathway. Furthermore, these CCI-induced behavioral and cellular responses were diminished in leptin-deficient mice and mimicked by spinal administration of exogenous leptin in naive rats. Our findings reveal a critical role for spinal leptin in the pathogenesis of neuropathic pain and suggest what we believe to be a novel form of nonneuronal and neuronal interactions in the mechanisms of pathological pain.     

Regulation of cytokine and toll-like receptor signaling by SOCS family genes

Bacterial lipopolysaccharide (LPS) triggers innate immune responses through the Toll-like receptor (TLR) 4. Regulation of TLR signaling is a key step for inflammation, septic shock and innate/adaptive immunity. TLR signaling is shown to be regulated by cytokines, such as interferon-gamma (positive) and interleukin-10 and IL-4 (negative). However, molecular mechanisms of the regulation of LPS signaling by cytokines have not been clarified. Cytokine signaling is regulated by CIS/SOCS family proteins. Both SOCS1 and SOCS3 can inhibit JAK tyrosine kinase activity. We demonstrate that SOCS1 and SOCS3 play an important regulatory role in macrophages and dendritic cells (DCs) by modulating TLR signaling. SOCS1 negatively regulates not only the JAK/STAT pathway, but also the TLR-NF-kappaB pathway. SOCS3 protein was strongly induced by both IL-6 and IL-10 in the presence of LPS, but selectively inhibited IL-6 signaling. Therefore lack of SOCS3 gene in macrophages resulted in suppression of TLR signaling by hyperactivation of STAT3.     

Nogo的作用机制和受体干预

Nogo是一个与中枢髓磷脂结合的特异性的抑制因子。脊髓损伤后,少突胶质细胞和髓磷脂释放出Nogo-A到细胞外基质,抑制轴突再生。通过分析Nogo受体的细胞外分子干预、细胞内信息干预和基因干预,了解对Nogo受体介导的髓磷脂相关抑制因子的抑制,为脊髓损伤后轴突的再生提供了新的思路和方法。     

JAK2/STAT3信号通路在应激性溃疡大鼠胃黏膜炎症反应中的作用研究

目的：探讨Janus激酶2（JAK2）/信号转导与转录激活子3（STAT3）信号通路在应激性溃疡（SU）的胃黏膜炎症反应过程中的作用。方法：选用雄性清洁级SD大鼠96只,随机分为4组,分别为：正常对照组（NC组）、应激性溃疡组（SU组）、抑制剂组（AG490组）、二甲基亚砜组（DMSO组）。建立水浸束缚SU大鼠模型。4组大鼠分别于实验开始后2h、4h、8h、16h各取6只,测定胃黏膜血流量（GMBF）,计算溃疡指数（UI）。观察胃黏膜组织学变化,测定TNF-α、IL-1β、IL-6以及JAK2、p-JAK2、STAT3、p-STAT3的表达量。结果：SU组GMBF明显低于NC组,而UI明显高于NC组（P〈0.01）;AG490组GMBF明显高于SU组,而UI明显低于SU组（P〈0.01）。通过造模前给予抑制剂AG490,胃黏膜病理学变化明显改善。SU组TNF-a、IL-1β、IL-6以及p-JAK2、p-STAT 3表达量明显高于NC组（P〈0.01）,而AG490组较SU组显著降低（P〈0.01）。结论：JAK2/STAT 3信号通路参与了SU大鼠胃黏膜炎症反应过程,使用JAK2特异性抑制剂AG490可以减轻SU大鼠胃黏膜炎症反应。     

Proteinase-activated receptor 2 modulates neuroinflammation in experimental autoimmune encephalomyelitis and multiple sclerosis

The proteinase-activated receptors (PARs) are widely recognized for their modulatory properties of inflammation and neurodegeneration. We investigated the role of PAR2 in the pathogenesis of multiple sclerosis (MS) in humans and experimental autoimmune encephalomyelitis (EAE) in mice. PAR2 expression was increased on astrocytes and infiltrating macrophages in human MS and murine EAE central nervous system (CNS) white matter (P < 0.05). Macrophages and astrocytes from PAR2 wild-type (WT) and knockout (KO) mice exhibited differential immune gene expression with PAR2 KO macrophages showing significantly higher interleukin 10 production after lipopolysaccharide stimulation (P < 0.001). PAR2 activation in macrophages resulted in the release of soluble oligodendrocyte cytotoxins (P < 0.01). Myelin oligodendrocyte glycoprotein-induced EAE caused more severe inflammatory gene expression in the CNS of PAR2 WT animals (P < 0.05), together with enhanced T cell proliferation and interferon gamma production (P < 0.05), compared with KO littermates. Indeed, PAR2 WT animals showed markedly greater microglial activation and T lymphocyte infiltration accompanied by worsened demyelination and axonal injury in the CNS compared with their PAR2 KO littermates. Enhanced neuropathological changes were associated with a more severe progressive relapsing disease phenotype (P < 0.001) in WT animals. These findings reveal previously unreported pathogenic interactions between CNS PAR2 expression and neuroinflammation with ensuing demyelination and axonal injury.     

Effect of fasudil, a selective inhibitor of rho kinase activity, in the secondary injury associated with the experimental model of spinal cord trauma

Rho kinase (ROK) may play an important role in regulating the biological events of cells, including proliferation, differentiation, and survival/death. Blockade of ROK promotes axonal regeneration and neuron survival in vivo and in vitro, thereby exhibiting potential clinical applications in spinal cord damage and stroke. The aim of this experimental study was to determine the role of ROK signaling pathways in the inflammatory response, in particular in the secondary injury associated with the experimental model of spinal cord trauma. The injury was induced by application of vascular clips to the dura via a four-level T5 to T8 laminectomy in mice. Fasudil was administered in mice (10 mg/kg i.p.) 1 and 6 h after the trauma. The treatment with fasudil significantly decreased 1) histological damage; 2) motor recovery; 3) nuclear factor-κB (NF-κB) expression; 4) ROK activity; 5) inflammasome activation (caspase-1 and NOD-like receptor family, pyrin domain-containing 3 expression); 6) production of proinflammatory cytokine such as tumor necrosis factor and interleukin-1β (IL-1β); 7) neutrophil infiltration; 8) nitrotyrosine and poly-ADP-ribose formation; 9) glial fibrillary acidic protein expression; 10) apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, FAS ligand expression, and Bax and Bcl-2 expression); and 11) mitogen-activated protein kinase activation (phospho-extracellular signal-regulated kinase and phospho-c-Jun NH(2)-terminal kinase expression). Our results indicate that inhibition of ROK by fasudil may represent a useful therapeutic perspective in the treatment of inflammation associated with spinal cord trauma.     

Caspase-11 mediates oligodendrocyte cell death and pathogenesis of autoimmune-mediated demyelination

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by localized areas of demyelination. The mechanisms underlying oligodendrocyte (OLG) injury in MS and EAE remain unknown. Here we show that caspase-11 plays crucial roles in OLG death and pathogenesis in EAE. Caspase-11 and activated caspase-3 were both expressed in OLGs in spinal cord EAE lesions. OLGs from caspase-11-deficient mice were highly resistant to the cell death induced by cytotoxic cytokines. EAE susceptibility and cytokine concentrations in the CNS were significantly reduced in caspase-11-deficient mice. Our findings suggest that OLG death is mediated by a pathway that involves caspases-11 and -3 and leads to the demyelination observed in EAE.