Spinal interleukin-6 contributes to central sensitisation and persistent pain hypersensitivity in a model of juvenile idiopathic arthritis

Pain is the most debilitating symptom in juvenile idiopathic arthritis. As pain correlates poorly to the extent of joint pathology, therapies that control joint inflammation are often inadequate as analgesics. We test the hypothesis that juvenile joint inflammation leads to sensitisation of nociceptive circuits in the central nervous system, which is maintained by cytokine expression in the spinal cord. Here, transient joint inflammation was induced in postnatal day (P)21 and P40 male Sprague-Dawley rats with a single intra-articular ankle injection of complete Freund’s adjuvant. Hindpaw mechanical pain sensitivity was assessed using von Frey hair and weight bearing tests. Spinal neuron activity was measured using in vivo extracellular recording and immunohistochemistry. Joint and spinal dorsal horn TNFα, IL1β and IL6 protein expression was quantified using western blotting. We observed greater mechanical hyperalgesia following joint inflammation in P21 compared to P40 rats, despite comparable duration of swelling and joint inflammatory cytokine levels. This is mirrored by spinal neuron hypersensitivity, which also outlasted the duration of active joint inflammation. The cytokine profile in the spinal cord differed at the two ages: prolonged upregulation of spinal IL6 was observed in P21, but not P40 rats. Finally, spinal application of anti-IL-6 antibody (30 ng) reduced the mechanical hyperalgesia and neuronal activation. Our results indicate that persistent upregulation of pro-inflammatory cytokines in the spinal dorsal horn is associated with neuronal sensitisation and mechanical hyperalgesia in juvenile rats, beyond the progress of joint pathology. In addition, we provide proof of concept that spinal IL6 is a key target for treating persistent pain in JIA.     

Robust T-tubulation and maturation of cardiomyocytes using tissue-engineered epicardial mimetics

Complex three-dimensional (3-D) heart structure is an important determinant of cardiac electrical and mechanical function. In this study, we set to develop a versatile tissue-engineered system that can promote important aspects of cardiac functional maturation and reproduce variations in myofiber directions present in native ventricular epicardium. We cultured neonatal rat cardiomyocytes within a 3-D hydrogel environment using microfabricated elastomeric molds with hexagonal posts. By varying individual post orientations along the directions derived from diffusion tensor magnetic resonance imaging (DTMRI) maps of human ventricle, we created large (2.5 × 2.5 cm²) 3-D cardiac tissue patches with cardiomyocyte alignment that replicated human epicardial fiber orientations. After 3 weeks of culture, the advanced structural and functional maturation of the engineered 3-D cardiac tissues compared to age-matched 2-D monolayers was evident from: 1) the presence of dense, aligned and electromechanically-coupled cardiomyocytes, quiescent fibroblasts, and interspersed capillary-like structures, 2) action potential propagation with near-adult conduction velocity and directional dependence on local cardiomyocyte orientation, and 3) robust formation of T-tubules aligned with Z-disks, co-localization of L-type Ca²⁺ channels and ryanodine receptors, and accelerated Ca²⁺ transient kinetics. This biomimetic tissue-engineered platform can enable systematic in vitro studies of cardiac structure–function relationships and promote the development of advanced tissue engineering strategies for cardiac repair and regeneration.     

卒中后肩痛周围神经电生理学研究

目的 通过对卒中后肩痛患者上肢进行神经传导速度检查及针极肌电图检查，观察卒中后肩痛患者周围神经电生理指标的变化。方法 选择符合入选标准的卒中住院患者40例，根据数字疼痛评分法（Numerical Pain Rating Scale，NPRS）分为肩痛组（26例）与无肩痛组（14例）。分别进行双侧上肢神经传导速度检查和针极肌电图（electromyography，EMG）检查。结果 肩痛组患侧腋神经、肌皮神经、正中神经复合肌肉动作电位（compound muscle action potential，CMAP）波幅较无肩痛组患侧降低，差异有显著性（P=0.000，0.001，0.000）；无肩痛组患侧尺神经CMAP波幅较同组健侧降低，差异有显著性（P=0.000）；肩痛组患侧尺神经感觉神经动作电位（sensory nerve action potential，SNAP）波幅较无肩痛组患侧降低，差异有显著性（P=0.000）。三角肌、肱二头肌自发电位出现率，肩痛组较无肩痛组增高，差异具有显著性（P=0.044，0.044）。结论 卒中后肩痛患者伴有上肢周围神经的损伤，且肩痛的发生可能与运动神经损伤有关。     

Participation of interleukin 17A in neuroimmune interactions

Inflammation involving the helper T cell 17 (Th17) subset of lymphocytes has been implicated in a number of diseases that affect the nervous system. As the canonical cytokine of Th17 cells, interleukin 17A (IL-17A) is thought to contribute to these neuroimmune interactions. The main receptor for IL-17A is expressed in many neural tissues. IL-17A has direct effects on neurons but can also impact neural function via signaling to satellite cells and immune cells. In the central nervous system, IL-17A has been associated with neuropathology in multiple sclerosis, epilepsy syndromes and ischemic brain injury. Effects of IL-17A at the level of dorsal root ganglia and the spinal cord may contribute to enhanced nociception during neuropathic and inflammatory pain. Finally, IL-17A plays a role in sympathetic axon growth and regeneration of damaged axons that innervate the cornea. Given the widespread effects of IL-17A on neural tissues, it will be important to determine whether selectively mitigating the damaging effects of this cytokine while augmenting its beneficial effects is a possible strategy to treat inflammatory damage to the nervous system.     

A comparison of neural responses to appetitive and aversive stimuli in humans and other mammals

Distinguishing potentially harmful or beneficial stimuli is necessary for the self-preservation and well-being of all organisms. This assessment requires the ongoing valuation of environmental stimuli. Despite much work on the processing of aversive- and appetitive-related brain signals, it is not clear to what degree these two processes interact across the brain. To help clarify this issue, this report used a cross-species comparative approach in humans (i.e. meta-analysis of imaging data) and other mammals (i.e. targeted review of functional neuroanatomy in rodents and non-human primates). Human meta-analysis results suggest network components that appear selective for appetitive (e.g. ventromedial prefrontal cortex, ventral tegmental area) or aversive (e.g. cingulate/supplementary motor cortex, periaqueductal grey) processing, or that reflect overlapping (e.g. anterior insula, amygdala) or asymmetrical, i.e. apparently lateralized, activity (e.g. orbitofrontal cortex, ventral striatum). However, a closer look at the known value-related mechanisms from the animal literature suggests that all of these macroanatomical regions are involved in the processing of both appetitive and aversive stimuli. Differential spatiotemporal network dynamics may help explain similarities and differences in appetitive- and aversion-related activity.     

Sloping ABR baselines and the ECG myogenic artefact

Objective: To investigate the possibility that a sloping baseline in an ABR recording has its origins in cardiac activity and if so, identify how it is expressed. Design: The effect of ECG removal on the averaged ABR was investigated at two artefact rejection levels. Study sample: Ten 1-minute records of raw EEG containing ABR responses but contaminated with cardiac activity were recorded from babies under 12 weeks of age and re-averaged using two artefact rejection levels. The slope of the ABR recording was measured. The measurements were repeated after removing effectively the cardiac activity from the records. Results: A sloping baseline was observed at one or both artefact rejection levels in all records. The slope varied as the artefact rejection level was changed, suggesting this may be implicated in slope generation. The slope effectively disappeared when the cardiac activity was removed from the record. Conclusions: Cardiac activity has the potential to cause a sloping ABR baseline. A possible explanation for this effect is offered, together with suggestions for tester strategy when a sloping ABR baseline is seen in a clinical setting.     

Enhanced ethanol inhibition of recombinant N-methyl-D-aspartate receptors by magnesium: role of NR3A subunits

Background:  The effects of ethanol on brain function are thought to be partly because of altered activity of ion channels that regulate synaptic activity. Results from previous studies from this lab and others have shown that ethanol inhibits the function of the N -methyl- d -aspartate (NMDA) receptors, a calcium-permeable ion channel activated by the neurotransmitter glutamate. Factors that influence the acute sensitivity of NMDA receptors to ethanol may be critical in determining how neurons and neuronal networks respond to the presence of ethanol. In this study, we have examined the effect of physiologically relevant concentrations of magnesium on the ethanol sensitivity of recombinant NMDA receptors and how ethanol inhibition under these conditions is influenced by the NR3A subunit.
Methods:  Recombinant cDNAs encoding NMDA receptor subunits were expressed in human embryonic kidney 293 cells. Whole-cell patch-clamp electrophysiology was used to measure currents induced by rapid application of glutamate in the absence and presence of ethanol.
Results:  In magnesium-free recording solution, ethanol inhibited glutamate-mediated currents in cells transfected with NMDA receptor subunits. The magnitude of ethanol inhibition was significantly enhanced when recordings were carried out in media containing 1 mM magnesium. This effect was reversible and required magnesium-sensitive receptors. Magnesium did not enhance ethanol inhibition of glycine-activated NR1/NR3A/NR3B receptors. However, NR3A co-expression prevented the enhancement of ethanol's inhibitory effect on receptors composed of NR2A but not NR2B subunits.
Conclusions:  These results suggest that under physiological conditions, NR3A may be an important regulator of the acute ethanol sensitivity of brain NMDA receptors.     

绝对不应期电刺激对心力衰竭豚鼠心室肌细胞动作电位时程和L型钙电流的影响

目的 探讨绝对不应期电刺激(ARPES)对健康和心力衰竭豚鼠心室肌细胞(分别简称NVM和FVM)动作电位(AP)时程(APD)和L型钙电流(ICa-L)的影响。方法 应用膜片钳技术中电流钳,首先记录基础刺激S1所诱发的AP(APS1),与S1延迟10 ms给予ARPES,记录ARPES给予后的AP(APARPES),比较APS1和APARPES的APD的值,以APD30、APD50和APD90代表动作电位复极30%、50％和90％时的APD值。分别以APS1和APARPES为测试电压,记录AP电压钳下的细胞膜ICa-L。结果(1)在NVM和FVM,ARPES应用后APD均明显延长,以APD30和APD50最为显著(P<0.01)。(2)在NVM,与APS1电压钳记录的ICa-L相比,APARPES电压钳记录的ICa-L电流强度有一过性的减弱和继发增强,但其单位膜电容下的电流强度的整合值略有降低(P<0.05)。在FVM,与APS1电压钳记录的ICa-L相比,APARPES电压钳记录的ICa-L电流强度的减弱程度明显减少,其单位膜电容下的电流强度的整合值是增加的(P<0.01)。结论 ARPES延长NVM和FVM的APD,对NVM和FVM的ICa-L具有不同的影响。     

阵发性心房颤动局灶消融后复发病例的大静脉肌袖电隔离治疗

对肺静脉内点消融治疗术后随访 2 2± 1 1 .1个月内的心房颤动 (简称房颤 )复发病例 ,在Lasso标测导管指引下 ,进行再次心内电生理检查及大静脉肌袖电隔离治疗。探讨点消融治疗阵发性房颤后复发的机制 ,并对再次经验性大静脉肌袖电隔离治疗的结果进行分析与评价。 5例患者共接受心内电生理标测和电隔离治疗 6次 (一例行第二次电隔离 ) ,除一例行右下肺静脉靶肌袖的电隔离外 ,其余病例均进行了经验性全部大静脉的电隔离 ,共电隔离心脏大静脉 1 5根 ,其中肺静脉 1 3根、上腔静脉 2根 ,即刻电隔离成功率 1 0 0 %。术后随访 1 1 .8± 8.9个月 ,均无房颤复发。因此 ,对于阵发性房颤导管射频点消融后复发病例进行经验性全部大静脉肌袖电隔离治疗可以满意控制房颤的发作。