Interleukin-33 treatment reduces secondary injury and improves functional recovery after contusion spinal cord injury

Interleukin-33 (IL-33) is a member of the interleukin-1 cytokine family and highly expressed in the naïve mouse brain and spinal cord. Despite the fact that IL-33 is known to be inducible by various inflammatory stimuli, its cellular localization in the central nervous system and role in pathological conditions is controversial. Administration of recombinant IL-33 has been shown to attenuate experimental autoimmune encephalomyelitis progression in one study, yet contradictory reports also exist.Here we investigated for the first time the pattern of IL-33 expression in the contused mouse spinal cord and demonstrated that after spinal cord injury (SCI) IL-33 was up-regulated and exhibited a nuclear localization predominantly in astrocytes. Importantly, we found that treatment with recombinant IL-33 alleviated secondary damage by significantly decreasing tissue loss, demyelination and astrogliosis in the contused mouse spinal cord, resulting in dramatically improved functional recovery. We identified both central and peripheral mechanisms of IL-33 action. In spinal cord, IL-33 treatment reduced the expression of pro-inflammatory tumor necrosis factor-alpha and promoted the activation of anti-inflammatory arginase-1 positive M2 microglia/macrophages, which chronically persisted in the injured spinal cord for up to at least 42 days after the treatment. In addition, IL-33 treatment showed a tendency towards reduced T-cell infiltration into the spinal cord. In the periphery, IL-33 treatment induced a shift towards the Th2 type cytokine profile and reduced the percentage and absolute number of cytotoxic, tumor necrosis factor-alpha expressing CD4+ cells in the spleen. Additionally, IL-33 treatment increased expression of T-regulatory cell marker FoxP3 and reduced expression of M1 marker iNOS in the spleen. Taken together, these results provide the first evidence that IL-33 administration is beneficial after CNS trauma. Treatment with IL33 may offer a novel therapeutic strategy for patients with acute contusion SCI.     

VX-765 reduces neuroinflammation after spinal cord injury in mice

Inflammation is a major cause of neuronal injury after spinal cord injury. We hypothesized that inhibiting caspase-1 activation may reduce neuroinflammation after spinal cord injury, thus producing a protective effect in the injured spinal cord. A mouse model of T9 contusive spinal cord injury was established using an Infinite Horizon Impactor, and VX-765, a selective inhibitor of caspase-1, was administered for 7 successive days after spinal cord injury. The results showed that: (1) VX-765 inhibited spinal cord injury-induced caspase-1 activation and interleukin-1β and interleukin-18 secretion. (2) After spinal cord injury, an increase in M1 cells mainly came from local microglia rather than infiltrating macrophages. (3) Pro-inflammatory Th1Th17 cells were predominant in the Th subsets. VX-765 suppressed total macrophage infiltration, M1 macrophages/microglia, Th1 and Th1Th17 subset differentiation, and cytotoxic T cells activation; increased M2 microglia; and promoted Th2 and Treg differentiation. (4) VX-765 reduced the fibrotic area, promoted white matter myelination, alleviated motor neuron injury, and improved functional recovery. These findings suggest that VX-765 can reduce neuroinflammation and improve nerve function recovery after spinal cord injury by inhibiting caspase-1/interleukin-1β/interleukin-18. This may be a potential strategy for treating spinal cord injury. This study was approved by the Animal Care Ethics Committee of Bengbu Medical College (approval No. 2017-037) on February 23, 2017.

Chinese Library Classification No. R453; R392.3; R744     

Effects of pro-inflammatory cytokines in experimental spinal cord injury

Following injury to the spinal cord, secondary tissue damage leading to massive additional tissue loss and inflammatory reactions as well as scar formation takes place. The precise functions and effects of the inflammatory cells and their secreted factors are largely unclear. The present study investigates whether the exogenous local administration of pro-inflammatory cytokines to mice after spinal cord injury can influence these intrinsic processes. A mixture of murine recombinant interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumour necrosis factor α (TNFα) was administered to the lesioned spinal cord of adult mice. These cytokines provoked an increased recruitment and activation of macrophages and microglial cells in the lesion area when administered 1 day post lesion. In contrast, when administered 4 days after the lesion, recruitment of macrophages was slightly increased while activation of microglia was decreased as compared to controls. The amount of tissue loss 7 days after trauma was smaller in the animals receiving the cytokine mixture than in the mice receiving Ringer control solution on day 4 after lesion. Thus the role of the inflammatory response in spinal cord injury seems to be complex and well regulated. Anti-inflammatory cytokines and factors probably also contribute to the outcome of the damage following injury to the spinal cord.     

Elamipretide reduces pyroptosis and improves functional recovery after spinal cord injury

Aims

Elamipretide (EPT), a novel mitochondria-targeted peptide, has been shown to be protective in a range of diseases. However, the effect of EPT in spinal cord injury (SCI) has yet to be elucidated. We aimed to investigate whether EPT would inhibit pyroptosis and protect against SCI.

Methods

After establishing the SCI model, we determined the biochemical and morphological changes associated with pyroptosis, including neuronal cell death, proinflammatory cytokine expression, and signal pathway levels. Furthermore, mitochondrial function was assessed with flow cytometry, quantitative real-time polymerase chain reaction, and western blot.

Results

Here, we demonstrate that EPT improved locomotor functional recovery following SCI as well as reduced neuronal loss. Moreover, EPT inhibited nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome activation and pyroptosis occurrence and decreased pro-inflammatory cytokines levels following SCI. Furthermore, EPT alleviated mitochondrial dysfunction and reduced mitochondrial reactive oxygen species level.

Conclusion

EPT treatment may protect against SCI via inhibition of pyroptosis.     

AIDA reduces glutamate release and attenuates mechanical allodynia after spinal cord injury

Spinal cord injury (SCI) leads to an increase in extracellular excitatory amino acid (EAA) concentrations, resulting in glutamate receptor-mediated excitotoxicity and central sensitization. To test contributions of group I metabotropic glutamate receptors (mGluRs) in SCI induced release of glutamate and in behavioral outcomes of central sensitization following injury, we administered 1-aminoindan-1,5-dicarboxylic acid (AIDA; 0.1 nmol intraspinally), a potent group I mGluR antagonist, to rats immediately after spinal cord contusion injury. EAAs were collected by microdialysis and quantified using HPLC. AIDA significantly decreased extracellular glutamate but not aspartate concentrations and significantly attenuated the development of mechanical but not thermal allodynia. These results suggest mGluRs play an important role in injury-induced EAA release and in central sensitization following SCI.     

Muscle after spinal cord injury

The morphological and contractile changes of muscles below the level of the lesion after spinal cord injury (SCI) are dramatic. In humans with SCI, a fiber‐type transformation away from type I begins 4–7 months post‐SCI and reaches a new steady state with predominantly fast glycolytic IIX fibers years after the injury. There is a progressive drop in the proportion of slow myosin heavy chain (MHC) isoform fibers and a rise in the proportion of fibers that coexpress both the fast and slow MHC isoforms. The oxidative enzymatic activity starts to decline after the first few months post‐SCI. Muscles from individuals with chronic SCI show less resistance to fatigue, and the speed‐related contractile properties change, becoming faster. These findings are also present in animals. Future studies should longitudinally examine changes in muscles from early SCI until steady state is reached in order to determine optimal training protocols for maintaining skeletal muscle after paralysis. Muscle Nerve, 2009     

Chemokine antagonist infusion promotes axonal sparing after spinal cord contusion injury in rat

Spinal cord injury produced by mechanical contusion causes the onset of acute and chronic degradative events. These include blood brain barrier disruption, edema, demyelination, axonal damage and neuronal cell death. Posttraumatic inflammation after spinal cord injury has been implicated in the secondary injury that ultimately leads to neurologic dysfunction. Studies after spinal cord contusion have shown expression of several chemokines early after injury and suggested a role for them in the ordered recruitment of inflammatory cells at the lesion site (McTigue et al. [1998] J. Neurosci. Res. 53:368-376; Lee et al., [2000] Neurochem Int). We have demonstrated previously that infusion of the broad-spectrum chemokine receptor antagonist (vMIPII) in the contused spinal cord initially attenuates leukocyte infiltration, suppresses' gliotic reaction and reduces neuronal damage after injury. These changes are accompanied by increased expression of bcl-2, the endogenous apoptosis inhibitor, and reduced neuronal apoptosis (Ghirnikar et al. [2000] J. Neurosci. Res. 59:63-73). We demonstrate that 2 and 4 weeks of vMIPII infusion in the contusion-injured spinal cord also results in decreased hematogenous infiltration and is accompanied by reduced axonal degeneration in the gray matter. Luxol fast blue and MBP immunoreactivity indicated reduced myelin breakdown in the dorsal and ventral funiculi. Increased neuronal survival in the ventral horns of vMIPII infused cords was seen along with increased bcl-2 staining in them. Immunohistochemical identification of fiber phenotypes showed increased presence of calcitonin gene related peptide, choline acetyl transferase and tyrosine hydroxylase positive fibers as well as increased GAP43 staining in treated cords. These results suggest that sustained reduction in posttraumatic cellular infiltration is beneficial for tissue survival. A preliminary report of this study has been published (Eng et al. [2000] J. Neurochem. 74(Suppl):S67B). In contrast to vMIPII, infusion of MCP-1 (9-76), a N-terminal analog of the MCP-1 chemokine showed only a modest reduction in cellular infiltration at 14 and 21 dpi without significant tissue survival after spinal cord contusion injury. Comparing data on tissue survival obtained with vMIPII and MCP-1 (9-76) further validate the importance of the use of broad-spectrum antagonists in the treatment of spinal cord injury. Controlling the inflammatory reaction and providing a growth permissive environment would enhance regeneration and ultimately lead to neurological recovery after spinal cord injury. J. Neurosci. Res. 64:582-589, 2001. Published 2001 Wiley-Liss, Inc.     

LINGO-1 antagonist promotes functional recovery and axonal sprouting after spinal cord injury

LINGO-1 is a CNS-specific protein and a functional component of the NgR1/p75/LINGO-1 and NgR1/TAJ(TROY)/LINGO-1 signaling complexes that mediate inhibition of axonal outgrowth. These receptor complexes mediate the axonal growth inhibitory effects of Nogo, myelin-associated glycoprotein (MAG) and oligodendrocyte-myelin glycoprotein (OMgp) via RhoA activation. Soluble LINGO-1 (LINGO-1-Fc), which acts as an antagonist of these pathways by blocking LINGO-1 binding to NgR1, was administered to rats after dorsal or lateral hemisection of the spinal cord. LINGO-1-Fc treatment significantly improved functional recovery, promoted axonal sprouting and decreased RhoA activation and increased oligodendrocyte and neuronal survival after either rubrospinal or corticospinal tract transection. These experiments demonstrate an important role for LINGO-1 in modulating axonal outgrowth in vivo and that treatment with LINGO-1-Fc can significantly enhance recovery after spinal cord injury.     

慢性压迫性脊髓损伤后巢蛋白mRNA表达的观察

目的观察成年大鼠慢性压迫性脊髓损伤后及减压后早期巢蛋白与巢蛋白mRNA的相关性表达。方法选用健康wistar大鼠50只，体重280～320g，制备慢性压迫性脊髓损伤中度、重度及重度损伤减压后3d、10d模型，取自距胜迫边缘5mm段脊髓组织切片。正常成年大鼠作为对照组。行巢蛋白免疫组织化学染色，巢蛋白mRNA原位杂交实验，计算机罔像分析仪定量分析，观察巢蛋白、巢蛋白mRNA在脊髓中央管、灰质和白质中表达的变化，探讨巢蛋白与巢蛋白mRNA表达的相关性。结果成年大鼠慢性膻迫性脊髓损伤中、重度及重度压迫损伤减压后3d，巢蛋白在自、灰质及脊髓中央管室管膜细胞中均有明显表达（P〈0．05），以重度压迫组最为显著（P〈0．01）。减压后10d组灰质与正常对照组比较，差异无显著性意义（P=0．483）。重度压迫组及减压后3d组，巢蛋白mRNA在脊髓灰质、白质及中央管室管膜细胞中均有显著性表达（P〈0．05），以灰质前角第Ⅸ板层、后角和室管膜下区最为显著。中度压迫组，巢蛋白mRNA在灰质前角第Ⅸ板层及中央管室管膜细胞中有显著性表达（P〈0．05），其余区域仅有微弱表达，而白质内巢蛋白mRNA表达于软脊膜下星形胶质细胞的足突中。减压后10d组灰质内巢蛋白mRNA的表达与正常对照组比较，无显著性差异（P=0．375）。正常对照组中无表达。结论成年大鼠慢性压迫性脊髓损伤及减压后早期存在神经前体细胞的增殖。增殖的神经前体细胞巢蛋白与巢蛋白mRNA表达的相关性具有与胚胎发育期脊髓相似的特征。     

Expression of pro-inflammatory cytokine and caspase genes promotes neuronal apoptosis in pontine reticular formation after spinal cord transection

We identified apoptotic neurons in pontine reticular formation (PRF), the origin of pontine reticulospinal fibers, in adult Sprague-Dawley rats after complete spinal cord transection (SCT) at T8 level. SCT also increased the expression in PRF of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, caspase-1, or caspase-3 mRNA. This was followed by an augmented expression of activated caspase-3 protein, an increase in caspase-3 activity, and expression of a cleaved fragment of poly(ADP-ribose) polymerase (PARP), a proteolytic substrate of the activated caspase-3. Microinjection bilaterally into the PRF of an antiserum against TNF-alpha attenuated the expression of IL-6 mRNA and up-regulation of caspase-3 mRNA, and a caspase-3 inhibitor, DEVD-CHO, suppressed the augmentation in activated caspase-3 or cleaved PARP expression after SCT. Both treatments also reduced the number of SCT-induced apoptotic PRF neurons. We conclude that PRF neurons in adult mammalian brain may actively degrade themselves after SCT through apoptosis, via signaling processes that involve activation of proinflammatory cytokine genes and the intracellular caspase-3 pathway.     

Limb segment vibration modulates spinal reflex excitability and muscle mRNA expression after spinal cord injury

ObjectiveWe investigated the effect of various doses of vertical oscillation (vibration) on soleus H-reflex amplitude and post-activation depression in individuals with and without SCI. We also explored the acute effect of short-term limb vibration on skeletal muscle mRNA expression of genes associated with spinal plasticity.MethodsSix healthy adults and five chronic complete SCI subjects received vibratory stimulation of their tibia over three different gravitational accelerations (0.3g, 0.6g, and 1.2g) at a fixed frequency (30 Hz). Soleus H-reflexes were measured before, during, and after vibration. Two additional chronic complete SCI subjects had soleus muscle biopsies 3 h following a single bout of vibration.ResultsH-reflex amplitude was depressed over 83% in both groups during vibration. This vibratory-induced inhibition lasted over 2 min in the control group, but not in the SCI group. Post-activation depression was modulated during the long-lasting vibratory inhibition. A single bout of mechanical oscillation altered mRNA expression from selected genes associated with synaptic plasticity.ConclusionsVibration of the lower leg inhibits the H-reflex amplitude, influences post-activation depression, and alters skeletal muscle mRNA expression of genes associated with synaptic plasticity.SignificanceLimb segment vibration may offer a long term method to reduce spinal reflex excitability after SCI.     

脊髓损伤后痉挛性瘫痪不同手术方式的临床观察

目的 通过临床观察探讨不同手术方式对脊髓损伤后痉挛性瘫痪患者生活质量改善的影响.方法 2001年10月～2005年6月我院收治的44例脊髓损伤患者中29例患者伤后三个月或半年发生痉挛性瘫痪,其中行选择性脊髓后根切断术10例,前后入路翻修、粘连松解加椎体内固定术14例,单纯粘连松解5例,以肌挛缩缓解、肌张力下降、腱反射减弱、阵挛改善、病理征转阴、感觉平面下降、二便功能改善、肌力改善、并发症发生等和患者生活质量密切相关的指标来综合评价术后效果.结果 行选择性脊髓后根切断术后9例患者肌挛缩缓解,9例肌张力下降,7例腱反射减弱,7例阵挛改善,7例病理征转阴,4例感觉平面下降,5例二便功能改善,1例发生并发症.行前后入路翻修、粘连松解加椎体内固定术后5例患者感觉平面下降,6例肌力改善,2例发生并发症,无一例肌挛缩缓解、肌张力下降、腱反射减弱、阵挛改善、病理征转阴或二便功能改善.行单纯粘连松解术后1例患者肌挛缩缓解,1例肌张力下降,1例阵挛改善,2例感觉平面下降,2例肌力改善,无一例腱反射减弱、病理征转阴、二便功能改善或发生并发症.结论 选择性脊髓后根切断术能有效改善瘫痪肢体的痉挛、强直状态,粘连松解加内固定术一定程度上可改善肢体肌力、下降感觉平面.对于脊髓损伤后痉挛性瘫痪患者的治疗,选择性脊髓后根切断和内固定术的适当结合也许是一种有效方法.     

Neural plasticity after spinal cord injury

Plasticity changes of uninjured nerves can result in a novel neural circuit after spinal cord injury, which can restore sensory and motor functions to different degrees. Although processes of neural plasticity have been studied, the mechanism and treatment to effectively improve neural plasticity changes remain controversial. The present study reviewed studies regarding plasticity of the central nervous system and methods for promoting plasticity to improve repair of injured central nerves. The results showed that synaptic reorganization, axonal sprouting, and neurogenesis are critical factors for neural circuit reconstruction. Directed functional exercise, neurotrophic factor and transplantation of nerve-derived and non-nerve-derived tissues and cells can effectively ameliorate functional disturbances caused by spinal cord injury and improve quality of life for patients.     

Valproic acid reduces autophagy and promotes functional recovery after spinal cord injury in rats

Secondary damage is a critical determinant of the functional outcome in patients with spinal cord injury (SCI), and involves multiple mechanisms of which the most important is the loss of nerve cells mediated by multiple factors. Autophagy can result in cell death, and plays a key role in the development of SCI. It has been recognized that valproic acid (VPA) is neuroprotective in certain experimental animal models, however, the levels of autophagic changes in the process of neuroprotection by VPA treatment following SCI are still unknown. In the present study, we determined the extent of autophagy after VPA treatment in a rat model of SCI. We found that both the mRNA and protein levels of Beclin-1 and LC3 were significantly increased at 1, 2, and 6 h after SCI and peaked at 2 h; however, Western blot showed that autophagy was markedly decreased by VPA treatment at 2 h post-injury. Besides, post-SCI treatment with VPA improved the Basso-Beattie-Bresnahan scale, increased the number of ventral horn motoneurons, and reduced myelin sheath damage compared with vehicle-treated animals at 42 days after SCI. Together, our results demonstrated the characteristics of autophagy expression following SCI, and found that VPA reduced autophagy and enhanced motor function.     

Decorin treatment of spinal cord injury

The scarring response after a penetrant central nervous system injury results from the interaction between invading leptominingeal/pericyte-derived fibroblasts and endogenous reactive astrocytes about the wound margin. Extracellular matrix and scar-derived axon growth inhibitory mole- cules fill the lesion site providing both a physical and chemical barrier to regenerating axons. Dec orin, a small leucine-rich chondroitin-dermatan sulphate proteoglycan expressed by neurons and astrocytes in the central nervous system, is both anti-fibrotic and anti-inflammatory and attenu- ates the formation and partial dissolution of established and chronic scars. Here, we discuss the potential of using Decorin to antagonise scarring in the central nervous system.     

Blocking connexin43 expression reduces inflammation and improves functional recovery after spinal cord injury

After traumatic CNS injury, a cascade of secondary events expands the initial lesion. The gap-junction protein connexin43 (Cx43), which is transiently up-regulated, has been implicated in the spread of 'bystander' damage. We have used an antisense oligodeoxynucleotide (asODN) to suppress Cx43 up-regulation in two rat models of spinal cord injury. Within 24 h of compression injury, rats treated with Cx43-asODN scored higher than sense-ODN and vehicle-treated controls on behavioural tests of locomotion. Their spinal cords showed less swelling and tissue disruption, less up-regulation of astrocytic GFAP, and less extravasation of fluorescently-labelled bovine serum albumin and neutrophils. The locomotor improvement was sustained over at least 4 weeks. Following partial spinal cord transection, Cx43-asODN treatment reduced GFAP immunoreactivity, neutrophil recruitment, and the activity of OX42(+) microglia in and around the lesion site. Cx43 has many potential roles in the pathophysiology of CNS injury and may be a valuable target for therapeutic intervention.