MicroRNA-146a-5p attenuates neuropathic pain via suppressing TRAF6 signaling in the spinal cord

Glia-mediated neuroinflammation plays an important role in the pathogenesis of neuropathic pain. Our recent study demonstrated that TNF receptor associated factor-6 (TRAF6) is expressed in spinal astrocytes and contributes to the maintenance of spinal nerve ligation (SNL)-induced neuropathic pain. MicroRNA (miR)-146a is a key regulator of the innate immune response and was shown to target TRAF6 and reduce inflammation. In this study, we found that in cultured astrocytes, TNF-α, IL-1β, or lipopolysaccharide (LPS) induced rapid TRAF6 upregulation and delayed miR-146a-5p upregulation. In addition, miR-146a-5p mimic blocked LPS-induced TRAF6 upregulation, as well as LPS-induced c-Jun N-terminal kinase (JNK) activation and chemokine CCL2 expression in astrocytes. Notably, LPS incubation with astrocytes enhanced the DNA binding activity of AP-1 to the promoters of mir-146a and ccl2. TRAF6 siRNA or JNK inhibitor SP600125 significantly reduced LPS-induced miR-146a-5p increase in astrocytes. In vivo, intrathecal injection of TNF-α or LPS increased spinal TRAF6 expression. Pretreatment with miR-146a-5p mimic alleviated TNF-α- or LPS-induced mechanical allodynia and reduced TRAF6 expression. Finally, SNL induced miR-146a-5p upregulation in the spinal cord at 10 and 21 days. Intrathecal injection of miR-146a-5p mimic attenuated SNL-induced mechanical allodynia and decreased spinal TRAF6 expression. Taken together, the results suggest that (1) miR-146a-5p attenuates neuropathic pain partly through inhibition of TRAF6 and its downstream JNK/CCL2 signaling, (2) miR-146a-5p is increased by the activation of TRAF6/JNK pathway. Hence, miR-146a-5p may be a novel treatment for chronic neuropathic pain.     

Current status on tissue factor activation of factor VIIa

Free factor VIIa displays a zymogen-like behavior with low intrinsic activity. Formation of a complex between factor VIIa and tissue factor is necessary to enhance the procoagulant activity of factor VIIa, not only by providing membrane localization, substrate exosites and positioning the active site at an appropriate distance above the surface but also by allosteric enhancement of the enzymatic activity, and this event signals initiation of blood coagulation. The interaction is of high affinity and all the domains are engaged at the interface. The crosstalk between the protease domain of factor VIIa, in particular residue Met-306, and the N-terminal domain of tissue factor provides the starting point for the allosteric activation of factor VIIa. The pathway(s) of conformational transitions in factor VIIa ensuing tissue factor binding has not been entirely mapped. The present paper is a brief compilation of our current knowledge of the allosteric mechanism by which tissue factor induces and stabilizes the active conformation of factor VIIa.     

失神经支配的骨骼肌萎缩与防治

背景：随着当今医学的发展,失神经支配骨骼肌萎缩的防治已取得了显著的进步,但临床疗效仍不十分满意。 目的：对失神经支配骨骼肌萎缩防治方法的研究现状作一总结,试图寻找更为有效的失神经支配骨骼肌萎缩防治方法。 方法：以denervation,muscle atrophy,treatment为检索词,检索Medline数据库(1998-01/2008-01)。以失神经,肌萎缩,治疗为检索词,检索中国期刊全文数据库(1998-01/2008-01)、万方数据库(1998-01/2008-01)和《中国临床康复》杂志(1998-01/2008-01)。文献检索语种限制为英文和中文。以肌肉的耐力及收缩力、失神经的肌湿重和骨骼肌的修复情况为评价指标。纳入研究失神经支配骨骼肌萎缩的显微外科手术方法、物理疗法、生物和化学疗法、基因疗法。排除上述方法之外失神经支配骨骼肌萎缩的其他疗法。 结果与结论：周围神经损伤后,骨骼肌失神经支配将不可避免的发生萎缩。因此,探索失神经支配骨骼肌萎缩的防治方法,吸引了国内外许多学者的兴趣,必将成为21世纪周围神经领域内的重要任务和研究热点。显微外科手术、物理疗法、生物和化学疗法、基因疗法等都是失神经支配骨骼肌萎缩有效的防治手段。目前,该领域的研究已经呈现多角度、多方面的趋势。失神经肌萎缩的防治方面已经有了针对性的措施,但在改善微循环、防止细胞凋亡、抑制胶原过度生长以及如何应用基因治疗的方法在基因水平改变生肌调节因子的表达等方面,还有大量工作需要进行。随着组织工程学、细胞培养学、分子生物学、基因工程等方面的不断发展,防治失神经肌萎缩必定会有新的突破。     

Oxymatrine reduces neuroinflammation in rat brain A signaling pathway

Cerebral neuroinflammation models were established by injecting 10 μg lipopolysaccharide into the hippocampus of male Sprague-Dawley rats. The rats were treated with an intraperitoneal injection of 120, 90, or 60 mg/kg oxymatrine daily for three days prior to the lipopolysaccharide injection. Twenty-four hours after model induction, the hippocampus was analyzed by real-time quantitative PCR, and the cerebral cortex was analyzed by enzyme-linked immunosorbent assay and western blot assay. The results of the enzyme-linked immunosorbent assay and the real-time quantitative PCR showed that the secretion and mRNA expression of the pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α were significantly decreased in the hippocampus and cerebral cortex of model rats treated with oxymatrine. Western blot assay and real-time quantitative PCR analysis indicated that toll-like receptor 4 mRNA and protein expression were significantly decreased in the groups receiving different doses of oxymatrine. Additionally, 120 and 90 mg/kg oxymatrine were shown to reduce protein levels of nuclear factor-κB p65 in the nucleus and of phosphorylated IκBα in the cytoplasm of brain cells, as detected by western blot assay. Experimental findings indicate that oxymatrine may inhibit neuroinflammation in rat brain via downregulating the expression of molecules in the toll-like receptor 4/nuclear factor-κB signaling pathway.     

前列地尔对实验性脑出血大鼠血肿周围组织炎性反应的影响

目的观察前列地尔对实验性脑出血模型大鼠血肿周围组织神经元形态的影响。方法采用立体定向技术于右侧基底节注射自体动脉血制备脑出血大鼠模型。前肢伸置和转身运动测验评价大鼠行为学变化,尼氏染色观察不同处理组大鼠血肿周围组织神经元形态变化,间接免疫荧光染色计数血肿周围组织TNF-α和IL-6表达阳性细胞数目及分布范围。结果脑出血后大鼠行为障碍主要表现为运动感觉损伤和动作不对称,给予前列地尔治疗后其症状与体征明显改善,且于实验第5、7和14天时行为功能恢复程度接近对照组（P〈0．05或P〈0．01）。组织形态学观察可见,脑出血后血肿周围组织有大量炎性细胞浸润、坏死,呈现“挤压区”,其外侧细胞水肿、轮廓不清;经前列地尔治疗后炎性细胞浸润和神经元肿胀不同程度改善,且随着治疗时间的延长脑出血同侧正中裂旁皮质区神经元数目逐渐增加,至治疗结束时接近正常水平（P=0．650）。脑出血后血肿周围组织神经元高表达TNF-α和IL-6,阳性细胞主要分布于血肿周围组织,血肿远隔部位和健侧几乎不表达;经前列地尔治疗后,二者表达水平呈逐渐降低趋势,并于治疗第7（P=0．035,0．023）和14天（P：0．024,0．020）时接近正常水平。结论前列地尔对脑出血模型大鼠神经功能改善的机制,可能与抑制血肿周围组织炎性反应、减少血肿周围组织继发性神经元损害有关。     

Vagus nerve stimulation promotes the M1-to-M2 transition via inhibition of TLR4/NF-κB in microglial to rescue the reperfusion injury

ObjectiveTo specify the effect of vagus nerve stimulation (VNS) on microglial polarization following ischemic-reperfusion and further investigate its underlying mechanism.Materials and methodsSprague-Dawley rats were randomly divided into the sham, ischemic reperfusion group (IR), IR+VNS groups. VNS intervention lasting for 1 hour was administered after 30 minutes of occlusion. We analyzed the expression of Arginase 1 (Arg1), the number of M2 microglial in the peri-infarction cortex and assessed the neurological scores at the 1, 3, 7 days after reperfusion to determine the research time point. Then, we assessed polarization status of microglial, the infarct volume, neurological scores, the cellular distribution of Toll-like Receptor 4 (TLR4), the TLR4-associated pathway protein and the p-NF-κB in microglial at 3 days after reperfusion.ResultsWe found that VNS could increase the specific marker of M2 Arg1 and upregulate the M2 microglial after reperfusion, and the increase of Arg1, M2 microglial and the neurological scores was largest at the 3 days after reperfusion. VNS treatment significantly reduced the number and percent of M1, improved the number and percent of M2 and upregulated the M2 to M1 ratio without changing the number of total microglial at the 3 days after reperfusion. Moreover, VNS reduced the infarct volume and neurological deficits. In addition, VNS significantly reduced the microglial-specific TLR4, inhibited the activated TLR4/MyD88/NF-κB pathway following ischemic-reperfusion, and ultimately suppressed the p-NF-κB in microglial.ConclusionOur study revealed that VNS can promote the M1-to-M2 phenotype conversion to alleviate inflammatory response and brain injury through inhibition of TLR4/MyD88/NF-κB pathway in microglia following ischemic-reperfusion.     

Post-stroke cognitive impairment and the risk of stroke recurrence and death in patients with insulin resistance

ObjectivePost-stroke cognitive impairment (PSCI) is associated with etiology, severity, and functional outcome of stroke. The risks of recurrent stroke and death in patients with PSCI and insulin resistance (IR) is unknown. The goal of this study was to determine whether global and domain-specific cognitive impairment after stroke in patients with IR was associated with recurrent stroke and death.Materials and MethodsWe studied patients with recent stroke or transient ischemic attack (TIA) and IR with a baseline Modified Mini-Mental State Examination (3MS) cognitive exam at median of 79 days after stroke. We considered a baseline score of ≤ 88 on the 3MS to indicate global cognitive impairment, and domain-specific summary scores in the lowest quartile to indicate language, attention, orientation, memory and visuospatial impairments. The primary endpoint was fatal or non-fatal recurrent stroke, and the secondary endpoints were all-cause mortality, and fatal or non-fatal myocardial infarction (MI).ResultsAmong studied n = 3,338 patients 13.6% had global cognitive impairment. During the median 4.96 years of follow-up, 7.4% patients experienced recurrent stroke, 3.5% MI, and 7.3% died. In the fully adjusted model, impairment in language (HR 1.35; 95% CI 1.01—1.81) and orientation (HR 1.41; 95% CI: 1.06—1.87) were associated with a higher risk of recurrent stroke, while attention impairment was associated with all-cause mortality (HR 1.34; 95% CI: 1.01—1.78).Discussion/ConclusionIn patients with recent stroke/TIA and IR, post-stroke language and orientation impairments independently predicted recurrent stroke, while attention deficit was associated with increased risk of all-cause mortality.     

Asystole due to trigemino-cardiac reflex: A rare complication of trans-sphenoidal surgery for pituitary adenoma

The trigemino-cardiac reflex (TCR) is a well-known reflexive response in which bradycardia, hypotension, and gastric hypermotility are induced by stimulation of a peripheral or central portion of the trigeminal nerve. This reflex occurs during craniofacial surgery and other operations on or near the cerebellopontine angle, petrosal sinus, orbit and trigeminal ganglion. TCR is a well-known, although not well documented, phenomenon commonly observed during trans-sphenoidal surgery for resection of pituitary adenomas. We report a case in which asystole occurred during trans-sphenoidal surgery on a pituitary adenoma that was infiltrating the right cavernous sinus. When the anesthesiologist reported asystole, the team stopped manipulation and administered intravenous atropine. Intra-operative MRI showed a small tumour remnant in the right cavernous sinus. The operation was terminated but subsequent radiosurgery was planned for the residual tumor. Although TCR is rare and usually self-limiting, this case led us to change our treatment strategy. Surgeons who perform trans-sphenoidal surgery should be aware of this potential problem. Invasive pituitary adenomas should be removed gently and the risk of triggering TCR should be kept in mind.