Cytokine activity contributes to induction of inflammatory cytokine mRNAs in spinal cord following contusion

Treadmill training improves neural function recovery in rats with spinal cord injury via JAK2/STAT3 signaling pathway and attenuating apoptosis

To investigate the role of JAK2/STAT3 signaling pathway in neural function recovery in rats with spinal cord injury (SCI) after treadmill training. Sprague-Dawley rats were randomly divided into four groups: (a) sham group; (b) SCI group; (c) SCI+treadmill training group (SCI/TT); and (d) SCI/TT+AG490 group (a JAK2 inhibitor) ( n  = 12). The 12 Sprague-Dawley rats in each group were randomly assigned into 1 st , 3 rd , 7 th , and 14 th  day subgroups. The Basso-Beattie-Bresnahan (BBB) locomotor rating scale was used to assess the spinal cord function, and JAK2, STAT3, and IL-6 protein expressions in the rat spinal cord were evaluated by western blot. The level of cell apoptosis and expressions of apoptotic proteins were evaluated by TUNEL assay and immunohistochemistry, respectively. Rats in the SCI+TT group showed a significantly higher BBB score after SCI compared with the SCI group and the SCI/TT+AG490 group. Mechanistically, the JAK2/STAT3 signal pathway was immediately activated after SCI compared with sham group, and JAK2 and STAT3 were obviously upregulated when treadmill training was performed ( P  < 0.05). Results of TUNEL assay showed that the apoptotic rate in SCI/TT was significantly lower than that in the SCI group and SCI/TT+AG490 group ( P  < 0.05). Besides, the IL-6 expression in the SCI/TT group was significantly attenuated compared with the SCI group ( P  < 0.05). Our results showed that physical treadmill training can enhance activation of JAK2/STAT3 signal pathway and attenuate apoptosis in the injured spinal cord, resulting in better functional recovery. These results underline the importance of synergistic treatment strategies for SCI.

Repair of spinal cord injury by bone marrow mesenchymal stem cell-derived exosomes: a systematic review and meta-analysis based on rat models

Objective

This study aims to systematically evaluate the efficacy of bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exo) in improving spinal cord injury (SCI) to mitigate the risk of translational discrepancies from animal experiments to clinical applications.

Methods

We conducted a comprehensive literature search up to March 2024 using PubMed, Embase, Web of Science, and Scopus databases. Two researchers independently screened the literature, extracted data, and assessed the quality of the studies. Data analysis was performed using STATA16 software.

Results

A total of 30 studies were included. The results indicated that BMSCs-Exo significantly improved the BBB score in SCI rats (WMD = 3.47, 95% CI [3.31, 3.63]), inhibited the expression of the pro-inflammatory cytokine TNF-α (SMD = -3.12, 95% CI [-3.57, -2.67]), and promoted the expression of anti-inflammatory cytokines IL-10 (SMD = 2.76, 95% CI [1.88, 3.63]) and TGF-β (SMD = 3.89, 95% CI [3.02, 4.76]). Additionally, BMSCs-Exo significantly reduced apoptosis levels (SMD = -4.52, 95% CI [-5.14, -3.89]), promoted the expression of axonal regeneration markers NeuN cells/field (SMD = 3.54, 95% CI [2.65, 4.42]), NF200 (SMD = 4.88, 95% CI [3.70, 6.05]), and the number of Nissl bodies (SMD = 1.89, 95% CI [1.13, 2.65]), and decreased the expression of astrogliosis marker GFAP (SMD = -5.15, 95% CI [-6.47, -3.82]). The heterogeneity among studies was primarily due to variations in BMSCs-Exo transplantation doses, with efficacy increasing with higher doses.

Conclusion

BMSCs-Exo significantly improved motor function in SCI rats by modulating inflammatory responses, reducing apoptosis, inhibiting astrogliosis, and promoting axonal regeneration. However, the presence of selection, performance, and detection biases in current animal experiments may undermine the quality of evidence in this study.

The acute spinal cord injury microenvironment and its impact on the homing of mesenchymal stem cells

Spinal cord injury (SCI) is a highly debilitating condition that inflicts devastating harm on the lives of affected individuals, underscoring the urgent need for effective treatments. By activating inflammatory cells and releasing inflammatory factors, the secondary injury response creates an inflammatory microenvironment that ultimately determines whether neurons will undergo necrosis or regeneration. In recent years, mesenchymal stem cells (MSCs) have garnered increasing attention for their therapeutic potential in SCI. MSCs not only possess multipotent differentiation capabilities but also have homing abilities, making them valuable as carriers and mediators of therapeutic agents. The inflammatory microenvironment induced by SCI recruits MSCs to the site of injury through the release of various cytokines, chemokines, adhesion molecules, and enzymes. However, this mechanism has not been previously reported. Thus, a comprehensive exploration of the molecular mechanisms and cellular behaviors underlying the interplay between the inflammatory microenvironment and MSC homing is crucial. Such insights have the potential to provide a better understanding of how to harness the therapeutic potential of MSCs in treating inflammatory diseases and facilitating injury repair. This review aims to delve into the formation of the inflammatory microenvironment and how it influences the homing of MSCs.

The Role of Tumor Necrosis Factor Following Spinal Cord Injury: A Systematic Review

Pre-clinical studies place tumor necrosis factor (TNF) as a central player in the inflammatory response after spinal cord injury (SCI), and blocking its production and/or activity has been proposed as a possible treatment option after SCI. This systematic review provides an overview of the literature on the temporal and cellular expression of TNF after SCI and clarifies the potential for its therapeutic manipulation in SCI. A systematic search was performed in EMBASE (Ovid), MEDLINE (Ovid), and Web of Science (Core Collection). The search terms were the MeSH forms of tumor necrosis factor and spinal cord injury in the different databases, and the last search was performed on February 3, 2021. We found twenty-four articles examining the expression of TNF, with most using a thoracic contusive SCI model in rodents. Two articles described the expression of TNF receptors in the acute phase after SCI. Twenty-one articles described the manipulation of TNF signaling using genetic knock-out, pharmaceutical inhibition, or gain-of-function approaches. Overall, TNF expression increased rapidly after SCI, within the first hours, in resident cells (neurons, astrocytes, oligodendrocytes, and microglia) and again in macrophages in the chronic phase after injury. The review underscores the complexity of TNF's role after SCI and indicates that TNF inhibition is a promising therapeutic option. This review concludes that TNF plays a significant role in the inflammatory response after SCI and suggests that targeting TNF signaling is a feasible therapeutic approach.

Tocilizumab promotes repair of spinal cord injury by facilitating the restoration of tight junctions between vascular endothelial cells

BACKGROUND

Our previous study demonstrated that M1 macrophages could impair tight junctions (TJs) between vascular endothelial cells by secreting interleukin-6 (IL-6) after spinal cord injury (SCI). Tocilizumab, as a humanized IL-6 receptor (IL-6R) monoclonal antibody approved for the clinic, has been applied in the treatment of neurological diseases in recent years, but the treatment effect of Tocilizumab on the TJs restoration of the blood-spinal cord barrier (BSCB) after SCI remains unclear. This study aimed to explore the effect of Tocilizumab on the restoration of TJs between vascular endothelial cells and axon regeneration after SCI.

METHODS

In this study, the mouse complete spinal cord crush injury model was used, and Tocilizumab was continuously injected intrathecally until the day of sample collection. A PBS injection in the same location was included as a control. At 14 days postinjury (dpi) and 28 dpi, spinal cord tissue sections were examined via tissue immunofluorescence. The Basso Mouse Scale (BMS) scores and footprint analysis were used to verify the effect of Tocilizumab on the recovery of motor function in mice after SCI.

RESULTS

We demonstrated that depletion of macrophages has no effect on axon regeneration and motor functional recovery after SCI, but mice subjected to Tocilizumab showed a significant increase in axon regeneration and a better recovery in motor function during the chronic phase after SCI. Moreover, our study demonstrated that at 14 and 28 dpi, the expression of claudin-5 (CLDN5) and zonula occludens-1 (ZO-1) between vascular endothelial cells was significantly increased and the leakage of BSCB was significantly reduced in the injured core after daily intrathecal injection of Tocilizumab. Notably, the infiltration of CD68⁺ macrophages/microglia and the formation of fibrotic scar were decreased in the injured core after Tocilizumab treatment. Tocilizumab treatment could effectively reduce the IL-6 expression in macrophages in the injured core.

CONCLUSION

The application of Tocilizumab to antagonize IL-6R can effectively reduce the expression of IL-6 in macrophages and facilitate TJs restoration of the BSCB, which is beneficial for axon regeneration and motor functional recovery after SCI. Hence, Tocilizumab treatment is a potential therapeutic strategy for SCI.

Immune response following traumatic spinal cord injury: Pathophysiology and therapies

Traumatic spinal cord injury (SCI) is a devastating condition that is often associated with significant loss of function and/or permanent disability. The pathophysiology of SCI is complex and occurs in two phases. First, the mechanical damage from the trauma causes immediate acute cell dysfunction and cell death. Then, secondary mechanisms of injury further propagate the cell dysfunction and cell death over the course of days, weeks, or even months. Among the secondary injury mechanisms, inflammation has been shown to be a key determinant of the secondary injury severity and significantly worsens cell death and functional outcomes. Thus, in addition to surgical management of SCI, selectively targeting the immune response following SCI could substantially decrease the progression of secondary injury and improve patient outcomes. In order to develop such therapies, a detailed molecular understanding of the timing of the immune response following SCI is necessary. Recently, several studies have mapped the cytokine/chemokine and cell proliferation patterns following SCI. In this review, we examine the immune response underlying the pathophysiology of SCI and assess both current and future therapies including pharmaceutical therapies, stem cell therapy, and the exciting potential of extracellular vesicle therapy.

Potential Neuroimmune Interaction in Chronic Pain: A Review on Immune Cells in Peripheral and Central Sensitization

Chronic pain is a long-standing unpleasant sensory and emotional feeling that has a tremendous impact on the physiological functions of the body, manifesting itself as a dysfunction of the nervous system, which can occur with peripheral and central sensitization. Many recent studies have shown that a variety of common immune cells in the immune system are involved in chronic pain by acting on the peripheral or central nervous system, especially in the autoimmune diseases. This article reviews the mechanisms of regulation of the sensory nervous system by neutrophils, macrophages, mast cells, B cells, T cells, and central glial cells. In addition, we discuss in more detail the influence of each immune cell on the initiation, maintenance, and resolution of chronic pain. Neutrophils, macrophages, and mast cells as intrinsic immune cells can induce the transition from acute to chronic pain and its maintenance; B cells and T cells as adaptive immune cells are mainly involved in the initiation of chronic pain, and T cells also contribute to the resolution of it; the role of glial cells in the nervous system can be extended to the beginning and end of chronic pain. This article aims to promote the understanding of the neuroimmune mechanisms of chronic pain, and to provide new therapeutic ideas and strategies for the control of chronic pain at the immune cellular level.

Maladaptation of Renal Hemodynamics Contributes to Kidney Dysfunction Resulting from Thoracic Spinal Cord Injury in Mice

Renal dysfunction is a hallmark of spinal cord injury (SCI). Several SCI sequalae are implicated, however, the exact pathogenic mechanism of renal dysfunction is unclear. Herein, we found that T3 (T3Tx) or T10 (T10Tx) complete thoracic spinal cord transection induced hypotension, bradycardia, and hypothermia immediately after injury. T3Tx-induced hypotension but not bradycardia or hypothermia slowly recovered to levels in T10Tx SCI and uninjured mice ~16 h after injury as determined by continuous radiotelemetry monitoring. Both types of thoracic SCI led to a marked decrease in albuminuria and proteinuria in all phases of SCI, while the kidney injury marker, NGAL, rapidly increased in the acute phase, remaining elevated in the chronic phase of T3Tx SCI. Renal interstitial and vascular elastin fragmentation after SCI were worsened during chronic T3Tx SCI. In the chronic phase, renal vascular resistance response to a step increase in renal perfusion pressure or a bolus injection of Ang II or NE was almost completely abolished after T3Tx SCI. Bulk RNAseq analysis showed enrichment of genes involved in extracellular matrix (ECM) remodeling and chemokine signaling in the kidney from T3Tx SCI mice. Serum levels of interleukin 6 was elevated in the acute but not chronic phase of T3Tx and T10Tx SCI, while serum amyloid A1 level was elevated in both acute and chronic phases. We conclude that tissue fibrosis and hemodynamic impairment are involved in renal dysfunction resulting from thoracic SCI; these pathological alterations, exacerbated by high thoracic-level injury, is mediated at least partly by renal microvascular ECM remodeling.

Notoginsenoside R1 alleviates spinal cord injury through the miR-301a/KLF7 axis to activate Wnt/β-catenin pathway

Spinal cord injury (SCI) is a devastating incident that induces neuronal loss and dysfunction. Notoginsenoside R1 (NGR1) has been reported to exhibit a neuroprotective role after SCI. In this study, the effect and molecular mechanisms of NGR1 in models of SCI were further investigated. Rat adrenal pheochromocytoma cell line (PC-12) were stimulated with lipopolysaccharide (LPS) to establish a cell model of SCI-like condition. The changes of proinflammatory cytokines and associated proteins were analyzed using enzyme linked immunosorbent assay (ELISA) and western blotting. A rat model of SCI was established. Nissl staining were used to observe the morphological characteristics of spinal cord tissues. reverse transcription-quantitative PCR (RT-qPCR) was used to measure the expression of miR-301a andKrüppel-like factor 7 (KLF7). Our results showed that NGR1 alleviated LPS-triggered apoptosis and inflammation in PC-12 cells. MiR-301a was upregulated in LPS-stimulated PC-12 cells and was downregulated by NGR1 treatment. MiR-301a overexpression reversed the effect of NGR1 in LPS-treated PC-12 cells. KLF7 was verified to be targeted by miR-301a. NGR1 activated Wnt/β-catenin signaling in LPS-treated PC-12 cells by inhibiting miR-301a and upregulating KLF7. Moreover, blocking wingless/integrated (Wnt)/β-catenin signaling eliminated the protective effect of NGR1 against SCI in vitro and in vivo. Overall, NGR1 could reduce inflammation and apoptosis and promote functional recovery of SCI rats by activating Wnt/β-catenin pathway.

Enhancing Functional Recovery Through Intralesional Application of Extracellular Vesicles in a Rat Model of Traumatic Spinal Cord Injury

Local inflammation plays a pivotal role in the process of secondary damage after spinal cord injury. We recently reported that acute intravenous application of extracellular vesicles (EVs) secreted by human umbilical cord mesenchymal stromal cells dampens the induction of inflammatory processes following traumatic spinal cord injury. However, systemic application of EVs is associated with delayed delivery to the site of injury and the necessity for high doses to reach therapeutic levels locally. To resolve these two constraints, we injected EVs directly at the lesion site acutely after spinal cord injury. We report here that intralesional application of EVs resulted in a more robust improvement of motor recovery, assessed with the BBB score and sub-score, as compared to the intravenous delivery. Moreover, the intralesional application was more potent in reducing inflammation and scarring after spinal cord injury than intravenous administration. Hence, the development of EV-based therapy for spinal cord injury should aim at an early application of vesicles close to the lesion.

Inflammation after spinal cord injury: a review of the critical timeline of signaling cues and cellular infiltration

Traumatic spinal cord injury (SCI) is a devastating neurological condition that results in a loss of motor and sensory function. Although extensive research to develop treatments for SCI has been performed, to date, none of these treatments have produced a meaningful amount of functional recovery after injury. The primary injury is caused by the initial trauma to the spinal cord and results in ischemia, oxidative damage, edema, and glutamate excitotoxicity. This process initiates a secondary injury cascade, which starts just a few hours post-injury and may continue for more than 6 months, leading to additional cell death and spinal cord damage. Inflammation after SCI is complex and driven by a diverse set of cells and signaling molecules. In this review, we utilize an extensive literature survey to develop the timeline of local immune cell and cytokine behavior after SCI in rodent models. We discuss the precise functional roles of several key cytokines and their effects on a variety of cell types involved in the secondary injury cascade. Furthermore, variations in the inflammatory response between rats and mice are highlighted. Since current SCI treatment options do not successfully initiate functional recovery or axonal regeneration, identifying the specific mechanisms attributed to secondary injury is critical. With a more thorough understanding of the complex SCI pathophysiology, effective therapeutic targets with realistic timelines for intervention may be established to successfully attenuate secondary damage.

A Pivotal Role of the Nrf2 Signaling Pathway in Spinal Cord Injury: A Prospective Therapeutics Study

The nuclear erythroid 2-related factor 2 (Nrf2) signaling pathway has a main role against oxidative stress and inflammation. Spinal Cord Injury (SCI) leads to the high secretion of inflammatory cytokines and reactive oxygen species, which disturbs nervous system function and regeneration. Several studies have indicated that the activation of the Nrf2 signaling pathway may be effective against inflammation after SCI. The experimental studies have indicated that many chemical and natural agents act as Nrf2 inducer, which inhibits the SCI progression. Thus, the finding of novel Nrf2- inducer anti-inflammatory agents may be a valuable approach in drug discovery. In the present review, we discussed the Nrf2 signal pathway and crosstalk with the NF-κB pathway and also the impact of this pathway on inflammation in animal models of SCI. Furthermore, we discussed the regulation of Nrf2 by several phytochemicals and drugs, as well as their effects on the SCI inhibition. Therefore, the current study presented a new hypothesis of the development of anti-inflammatory agents that mediate the Nrf2 signaling pathway for treating the SCI outcomes.

Exercise-Induced Plasticity in Signaling Pathways Involved in Motor Recovery after Spinal Cord Injury

Spinal cord injury (SCI) leads to numerous chronic and debilitating functional deficits that greatly affect quality of life. While many pharmacological interventions have been explored, the current unsurpassed therapy for most SCI sequalae is exercise. Exercise has an expansive influence on peripheral health and function, and by activating the relevant neural pathways, exercise also ameliorates numerous disorders of the central nervous system (CNS). While the exact mechanisms by which this occurs are still being delineated, major strides have been made in the past decade to understand the molecular underpinnings of this essential treatment. Exercise rapidly and prominently affects dendritic sprouting, synaptic connections, neurotransmitter production and regulation, and ionic homeostasis, with recent literature implicating an exercise-induced increase in neurotrophins as the cornerstone that binds many of these effects together. The field encompasses vast complexity, and as the data accumulate, disentangling these molecular pathways and how they interact will facilitate the optimization of intervention strategies and improve quality of life for individuals affected by SCI. This review describes the known molecular effects of exercise and how they alter the CNS to pacify the injury environment, increase neuronal survival and regeneration, restore normal neural excitability, create new functional circuits, and ultimately improve motor function following SCI.

Photobiomodulation Promotes Neuronal Axon Regeneration After Oxidative Stress and Induces a Change in Polarization from M1 to M2 in Macrophages via Stimulation of CCL2 in Neurons: Relevance to Spinal Cord Injury

To study the effect of photobiomodulation (PBM) on axon regeneration and secretion change of dorsal root ganglion (DRG) under oxidative stress after spinal cord injury (SCI), and further explore the effect of changes in DRG secretion caused by PBM on the polarization of macrophages. The PBM-DRG model was constructed to perform PBM on neurons under oxidative stress simulated in vitro. And the irradiation conditions were as follows: wavelength, 810 nm; power density, 2 mW/cm²; irradiation area, 4.5 cm²; and irradiation time, 440 s. Then resulted in an energy of 4 J (2 mW/cm² × 4.5 cm² × 440 s). About 100 μM H₂0₂ was added to the culture medium to simulate oxidative stress after SCI. An ROS (reactive oxygen species) assay kit was used to measure ROS contend in the DRG. The survival level of the neurons was measured using the CCK-8 method, and the axon regeneration of neurons was observed by using immunofluorescence. The secretion level of CCL2 from DRG was determined by RT-qPCR and ELISA. Further culturing macrophages of DRG-conditioned medium culture, the expression level of iNOS and Arg-1 in macrophages was assessed using Western blot analysis. The expression level of TNF-α and IL-1β was determined by ELISA. After adding the neutralizing antibody of CCL2 to the DRG neuron-conditioned medium following PBM irradiation to culture macrophages to observe the effects on macrophage polarization and secretion. PBM could reduce ROS levels in neurons, increase neuronal survival under oxidative stress, and promote neuronal axon regeneration. In addition, PBM could also promote CCL2 secretion by DRG under oxidative stress. By constructing a DRG supernatant-M1 macrophage adoptive culture model, we found that the supernatant of DRG after PBM intervention could reduce the expression level of iNOS and the secretion of TNF-α and IL-1β in M1 macrophages; at the same time, it could also up-regulate the expression of Arg-1, one of the markers of M2 macrophages. Furthermore, these effects could be prevented by the addition of neutralizing antibodies of CCL2. PBM could promote survival and axonal regeneration of DRG under SCI oxidative stress, increase the secretion level of CCL2 by DRG, and this change can reduce the polarization of macrophages to M1, further indicating that PBM could promote spinal cord injury repair.

Advances in immunotherapy for the treatment of spinal cord injury

Spinal cord injury (SCI) is a leading cause of morbidity and disability in the world. Over the past few decades, the exact molecular mechanisms describing secondary, persistent injuries, as well as primary and transient injuries, have attracted massive attention to the clinicians and researchers. Recent investigations have distinctly shown the critical roles of innate and adaptive immune responses in regulating sterile neuroinflammation and functional outcomes after SCI. In past years, some promising advances in immunotherapeutic options have efficaciously been identified for the treatment of SCI. In our narrative review, we have mainly focused on the new therapeutic strategies such as the maturation and apoptosis of immune cells by several agents, mesenchymal stem cells (MSCs) as well as multi-factor combination therapy, which have recently provided novel ideas and prospects for the future treatment of SCI. This article also illustrates the latest progress in clarifying the potential roles of innate and adaptive immune responses in SCI, the progression and specification of prospective immunotherapy and outstanding issues in the area.

Effects of combined treatment of minocycline and methylprednisolone on the expression of tumor necrosis factor alpha and interleukine-6 in experimental spinal cord injury: a light and electron microscopic study

Spinal cord injury (SCI) is an important health problem, and there is no universal treatment protocol for it today. Following SCI pro-inflammatory mediators such as tumor necrosis factor- alpha (TNF-α) and interleukin-6 (IL-6) increase at the lesion site and play important roles in secondary tissue damage. Methylprednisolone (MP) is a glucocorticoid, and minocycline is a tetracycline-derived antibiotic both with neuroprotective effects on central nervous system trauma. However, there are limited studies on their effects on SCI. In this study, we aimed to evaluate effects of MP+minocycline combined treatment on cellular distribution and localization of TNF-α And IL-6 after SCI. Eighty Wistar rats were divided into three main groups as the intact control group, sham operation group, and experimental control group that received spinal cord compression injury. Following the injury, the experimental control group was subdivided into four groups as control, methylprednisolone treatment, minocycline treatment and, MP+minocycline combined treatment groups. Tissue samples were obtained from all groups at 24 hours and 72 hours after the injury. We found a significant decrease in TNF-α And IL-6 expressions in combined treatment group at 24 hours after injury. Also, there was a significant decrease in MDA and increase in SOD levels in this group. Furthermore, decreased lipid peroxidation and neuronal and glial cell death were also observed in combined treatment group. These results suggest that MP+minocycline combined treatment promotes functional recovery and, it should be considered as an effective treatment protocol following SCI.

Suppression of LINC00707 alleviates lipopolysaccharide-induced inflammation and apoptosis in PC-12 cells by regulated miR-30a-5p/Neurod 1

Long noncoding RNA (lncRNA) has emerged as a pivotal regulator improving neural regeneration in the progression of spinal cord injury (SCI). However, whether lncRNAs can be targeted for therapeutic intervention of SCI remains unclear. In this study, we found that LINC00707 expression was significantly up-regulated in lipopolysaccharide (LPS)-treated PC-12, a model that mimics nerve cell injury in an inflammatory environment after SCI. Suppression of LINC00707 alleviated LPS-induced inflammation and apoptosis in PC-12 cells. Furthermore, we found that LINC00707 adsorbed miR-30a-5p and silenced miR-30a-5p or overexpressed Neurod 1 reversed the effect of LINC00707 on the inflammation and apoptosis of LPS-treated PC-12 cells. These findings revealed that LINC00707 alleviates LPS-induced inflammation and apoptosis in PC-12 cells by targeting miR-30a-5p/Neurod 1, providing a preliminary theoretical basis for the clinical application of LINC00707 in SCI.

Autophagy in Neurotrauma: Good, Bad, or Dysregulated

Autophagy is a physiological process that helps maintain a balance between the manufacture of cellular components and breakdown of damaged organelles and other toxic cellular constituents. Changes in autophagic markers are readily detectable in the spinal cord and brain following neurotrauma, including traumatic spinal cord and brain injury (SCI/TBI). However, the role of autophagy in neurotrauma remains less clear. Whether autophagy is good or bad is under debate, with strong support for both a beneficial and detrimental role for autophagy in experimental models of neurotrauma. Emerging data suggest that autophagic flux, a measure of autophagic degradation activity, is impaired in injured central nervous systems (CNS), and interventions that stimulate autophagic flux may provide neuroprotection in SCI/TBI models. Recent data demonstrating that neurotrauma can cause lysosomal membrane damage resulting in pathological autophagosome accumulation in the spinal cord and brain further supports the idea that the impairment of the autophagy-lysosome pathway may be a part of secondary injury processes of SCI/TBI. Here, we review experimental work on the complex and varied responses of autophagy in terms of both the beneficial and detrimental effects in SCI and TBI models. We also discuss the existing and developing therapeutic options aimed at reducing the disruption of autophagy to protect the CNS after injuries.

Regulation of Inflammatory Cytokines for Spinal Cord Injury Repair Through Local Delivery of Therapeutic Agents

The balance of inflammation is critical to the repair of spinal cord injury (SCI), which is one of the most devastating traumas in human beings. Inflammatory cytokines, the direct mediators of local inflammation, have differential influences on the repair of the injured spinal cord. Some inflammatory cytokines are demonstrated beneficial to spinal cord repair in SCI models, while some detrimental. Various animal researches have revealed that local delivery of therapeutic agents efficiently regulates inflammatory cytokines and promotes repair from SCI. Quite a few clinical studies have also shown the promotion of repair from SCI through regulation of inflammatory cytokines. However, local delivery of a single agent affects only a part of the inflammatory cytokines that need to be regulated. Meanwhile, different individuals have differential profiles of inflammatory cytokines. Therefore, future studies may aim to develop personalized strategies of locally delivered therapeutic agent cocktails for effective and precise regulation of inflammation, and substantial functional recovery from SCI.

Mechanical ventilation modulates pro-inflammatory cytokine expression in spinal cord tissue after injury in rats

RATIONALE

Spinal cord injury (SCI) may induce significant respiratory muscle weakness and paralysis, which in turn may cause a patient to require ventilator support. Central nervous system alterations can also exacerbate local inflammatory responses with immune cell infiltration leading to additional risk of inflammation at the injury site. Although mechanical ventilation is the traditional treatment for respiratory insufficiency, evidence has shown that it may directly affect distant organs through systemic inflammation.

OBJECTIVES

This study aimed to better understand the impact of invasive mechanical ventilation on local spinal cord inflammatory responses following cervical or thoracic SCI.

METHODS

Five groups of female Sprague-Dawley rats were anesthetised for 24 h. Three groups received mechanical ventilation: seven rats without SCI, seven rats with cervical injury (C4-C5), and seven rats with thoracic injury (T10); whereas, two groups were non-ventilated: six rats without SCI; and six rats with thoracic injury (T10). Changes in inflammatory responses were determined in the spinal cord tissues collected at the local site of injury. Cytokines were measured using ELISA.

MAIN RESULTS

SCI induced local pro-inflammatory cytokine IL-6 expression for all groups. Mechanical ventilation also had effects on pro-inflammatory cytokines and independently increased TNF-α and decreased IL-1β levels in the spinal cords of anesthetized rats.

CONCLUSION

These data provide the first evidence that mechanical ventilation contributes to local inflammation after SCI and in the absence of direct tissue injury.

Electric field stimulation protects injured spinal cord from secondary inflammatory response in rats

OBJECTIVES

To investigate acute beneficial effects of electrical field stimulation (EFS) on secondary inflammatory response in spinal cord injury (SCI) rats.

METHODS

Sprague-Dawley (SD) rats were divided into three groups,sham group rats received laminectomy only, control group rats were subjected to SCI only, and EFS group rats received EFS immediately after the injury. During the 30-min-stimulation, the injury potential modulated to 0 ± 0.5 mV by EFS. At 12h, 24h and 48h after the surgery, the rats in each group were sacrificed. Immunofluorescence staining for macrophage marker (ED-1), the tautomerase activity of macrophage inhibitory factor (MIF) assay and real-time PCR analysis for interleukin-1β (IL-1β) and matrix metalloproteinase-9 (MMP-9) were performed.

RESULTS

Compared to the rats in control group, the rats treated with EFS presented less ED-1 positive cells 12h (P <; 0.05), 24h (P <; 0.01) and 48h (P <; 0.05) after the surgery and showed a lower MIF tautomerase activity 12h (P <; 0.01), 24h (P <; 0.01) and 48h (P <; 0.01) after the surgery. Moreover, EFS significantly decreased the mRNA levels of IL-β (P <; 0.05) and MMP-9 at 48h (P <; 0.01) after the injury.

CONCLUSIONS

EFS could attenuate secondary inflammatory response of injured spinal cord shortly after SCI, and EFS treatment could be a candidate for SCI therapy.

Determinants of Axon Growth, Plasticity, and Regeneration in the Context of Spinal Cord Injury

The mechanisms that underlie recovery after injury of the central nervous system have rarely been definitively established. Axon regrowth remains the major prerequisite for plasticity, regeneration, circuit formation, and eventually functional recovery. The attributed functional relevance of axon regrowth, however, will depend on several subsequent conditional neurobiological modifications, including myelination and synapse formation, but also pruning of aberrant connectivity. Despite the ability to revamp axon outgrowth by altering an increasing number of extracellular and intracellular targets, disentangling which axons are responsible for the recovery of function from those that are functionally silent, or even contributing to aberrant functions, represents a pertinent void in our understanding, challenging the intuitive translational link between anatomical and functional regeneration. Anatomic hallmarks of regeneration are not static and are largely activity dependent. Herein, we survey mechanisms leading to the formation of dystrophic growth cone at the injured axonal tip, the subsequent axonal dieback, and the molecular determinants of axon growth, plasticity, and regeneration in the context of spinal cord injury.

Long Coding RNA XIST Contributes to Neuronal Apoptosis through the Downregulation of AKT Phosphorylation and Is Negatively Regulated by miR-494 in Rat Spinal Cord Injury

Recent evidence has suggested that long non-coding RNAs (lncRNAs) may play a significant role in the pathogenesis of several neurological diseases, including spinal cord injury (SCI). However, little is known about the role of lncRNAs in SCI. The aim of the present study was to evaluate the potential functions of lncRNAs in SCI and to identify the underlying mechanisms of action. We firstly analyzed Gene Expression Omnibus (GEO) datasets to investigate aberrantly-expressed lncRNAs which might be involved in the pathogenesis of SCI. The long non-coding RNA X-inactive specific transcript (XIST) was found to be one of the most significantly upregulated lncRNAs in the GEO dataset analysis, and is associated with apoptosis. We, therefore, selected this as a candidate lncRNA and investigated its function. We found that knockdown of lncRNA-XIST by Lv-shRNA had a prominent protective effect on SCI recovery by suppressing apoptosis through reactivation of the PI3K/AKT signaling pathway in rat spinal cord tissue. In particular, our results suggested that lncRNA-XIST may act as a competitive endogenous RNA, effectively becoming a sink for miR-494, leading to derepression of its target gene, phosphatase and tensin homolog deleted on chromosome ten (PTEN). In addition, an inverse relationship between lncRNA-XIST and miR-494 was observed in spinal cord tissues of SCI rats. Further study demonstrated that antagomiR-494 could reverse the protective effects of lncRNA-XIST knockdown on SCI rats through blocking the PTEN/PI3K/AKT signaling pathway. These results suggested that lncRNA-XIST knockdown may play an important role in limiting neuronal apoptosis in rats following SCI, and that the observed protective effects of lncRNA-XIST knockdown might have been mediated by its regulation on the phosphorylation of AKT by competitively binding miR-494. These findings have revealed, for the first time, the importance of the XIST/miR-494/PTEN/AKT signaling axis in the pathogenesis of SCI and suggest that lncRNA-XIST may be a promising molecular target for SCI therapy.

Spinal Cord Injury and Related Clinical Trials

Spinal cord injury (SCI) has been considered an incurable condition and it often causes devastating sequelae. In terms of the pathophysiology of SCI, reducing secondary damage is the key to its treatment. Various researches and clinical trials have been performed, and some of them showed promising results; however, there is still no gold standard treatment with sufficient evidence. Two therapeutic concepts for SCI are neuroprotective and neuroregenerative strategies. The neuroprotective strategy modulates the pathomechanism of SCI. The purpose of neuroprotective treatment is to minimize secondary damage following direct injury. The aim of neuroregenerative treatment is to enhance the endogenous regeneration process and to alter the intrinsic barrier. With advancement in biotechnology, cell therapy using cell transplantation is currently under investigation. This review discusses the pathophysiology of SCI and introduces the therapeutic candidates that have been developed so far.

RNA Binding Protein Human Antigen R Is Translocated in Astrocytes following Spinal Cord Injury and Promotes the Inflammatory Response

Inflammation plays a prominent role in the events following traumatic injury to the central nervous system (CNS). The initial inflammatory response is driven by mediators such as tumor necrosis factor α and interleukin 1β, which are produced by activated astrocytes and microglia at the site of injury. These factors are regulated post-transcriptionally by RNA binding proteins (RBP) that interact with adenylate and uridylate-rich elements (ARE) in the 3'-untranslated region of the messenger RNA (mRNA). Human antigen R (HuR) is one of these RBPs and generally functions as a positive regulator of ARE-containing mRNAs. Here, we hypothesized that HuR plays an important role in the induction of cytokine and chemokines in astrocytes following traumatic injury. Using a mouse model of spinal cord injury, we found HuR to be extensively translocated to the cytoplasm in astrocytes at the level of injury, consistent with its activation. In an in vitro stretch injury model of CNS trauma, we observed a similar cytoplasmic shift of HuR in astrocytes and an attenuation of cytokine induction with HuR knockdown. RNA kinetics and luciferase assays suggested that the effect was more related to transcription than RNA destabilization. A small molecule inhibitor of HuR suppressed cytokine induction of injured astrocytes and reduced chemoattraction for neutrophils and microglia. In summary, HuR is activated in astrocytes in the early stages of CNS trauma and positively regulates the molecular response of key inflammatory mediators in astrocytes. Our findings suggest that HuR may be a therapeutic target in acute CNS trauma for blunting secondary tissue injury triggered by the inflammatory response.

Genetic Ablation of Soluble TNF Does Not Affect Lesion Size and Functional Recovery after Moderate Spinal Cord Injury in Mice

Traumatic spinal cord injury (SCI) is followed by an instant increase in expression of the microglial-derived proinflammatory cytokine tumor necrosis factor (TNF) within the lesioned cord. TNF exists both as membrane-anchored TNF (mTNF) and as cleaved soluble TNF (solTNF). We previously demonstrated that epidural administration of a dominant-negative inhibitor of solTNF, XPro1595, to the contused spinal cord resulted in changes in Iba1 protein expression in microglia/macrophages, decreased lesion volume, and improved locomotor function. Here, we extend our studies using mice expressing mTNF, but no solTNF (mTNF^Δ/Δ), to study the effect of genetic ablation of solTNF on SCI. We demonstrate that TNF levels were significantly decreased within the lesioned spinal cord 3 days after SCI in mTNF^Δ/Δ mice compared to littermates. This decrease did, however, not translate into significant changes in other pro- and anti-inflammatory cytokines (IL-10, IL-1β, IL-6, IL-5, IL-2, CXCL1, CCL2, or CCL5), despite a tendency towards increased IL-10 and decreased IL-1β, TNFR1, and TNFR2 levels in mTNF^Δ/Δ mice. In addition, microglial and leukocyte infiltration, activation state (Iba1, CD11b, CD11c, CD45, and MHCII), lesion size, and functional outcome after moderate SCI were comparable between genotypes. Collectively, our data demonstrate that genetic ablation of solTNF does not significantly modulate postlesion outcome after SCI.

A Comparative Study of Three Different Types of Stem Cells for Treatment of Rat Spinal Cord Injury

Three different sources of human stem cells-bone marrow-derived mesenchymal stem cells (BM-MSCs), neural progenitors (NPs) derived from immortalized spinal fetal cell line (SPC-01), and induced pluripotent stem cells (iPSCs)-were compared in the treatment of a balloon-induced spinal cord compression lesion in rats. One week after lesioning, the rats received either BM-MSCs (intrathecally) or NPs (SPC-01 cells or iPSC-NPs, both intraspinally), or saline. The rats were assessed for their locomotor skills (BBB, flat beam test, and rotarod). Morphometric analyses of spared white and gray matter, axonal sprouting, and glial scar formation, as well as qPCR and Luminex assay, were conducted to detect endogenous gene expression, while inflammatory cytokine levels were performed to evaluate the host tissue response to stem cell therapy. The highest locomotor recovery was observed in iPSC-NP-grafted animals, which also displayed the highest amount of preserved white and gray matter. Grafted iPSC-NPs and SPC-01 cells significantly increased the number of growth-associated protein 43 (GAP43+) axons, reduced astrogliosis, downregulated Casp3 expression, and increased IL-6 and IL-12 levels. hMSCs transiently decreased levels of inflammatory IL-2 and TNF-α. These findings correlate with the short survival of hMSCs, while NPs survived for 2 months and matured slowly into glia- and tissue-specific neuronal precursors. SPC-01 cells differentiated more in astroglial phenotypes with a dense structure of the implant, whereas iPSC-NPs displayed a more neuronal phenotype with a loose structure of the graft. We concluded that the BBB scores of iPSC-NP- and hMSC-injected rats were superior to the SPC-01-treated group. The iPSC-NP treatment of spinal cord injury (SCI) provided the highest recovery of locomotor function due to robust graft survival and its effect on tissue sparing, reduction of glial scarring, and increased axonal sprouting.

Morphine amplifies mechanical allodynia via TLR4 in a rat model of spinal cord injury

Central neuropathic pain (CNP) is a pervasive, debilitating problem that impacts thousands of people living with central nervous system disorders, including spinal cord injury (SCI). Current therapies for treating this type of pain are ineffective and often have dose-limiting side effects. Although opioids are one of the most commonly used CNP treatments, recent animal literature has indicated that administering opioids shortly after a traumatic injury can actually have deleterious effects on long-term health and recovery. In order to study the deleterious effects of administering morphine shortly after trauma, we employed our low thoracic (T13) dorsal root avulsion model (Spinal Neuropathic Avulsion Pain, SNAP). Administering a weeklong course of 10mg/kg/day morphine beginning 24h after SNAP resulted in amplified mechanical allodynia. Co-administering the non-opioid toll-like receptor 4 (TLR4) antagonist (+)-naltrexone throughout the morphine regimen prevented morphine-induced amplification of SNAP. Exploration of changes induced by early post-trauma morphine revealed that this elevated gene expression of TLR4, TNF, IL-1β, and NLRP3, as well as IL-1β protein at the site of spinal cord injury. These data suggest that a short course of morphine administered early after spinal trauma can exacerbate CNP in the long term. TLR4 initiates this phenomenon and, as such, may be potential therapeutic targets for preventing the deleterious effects of administering opioids after traumatic injury.

Effects of melatonin on severe crush spinal cord injury-induced reactive astrocyte and scar formation

The present work aimed at analyzing the effects of melatonin on scar formation after spinal cord injury (SCI). Upregulation of reactive astrocyte under SCI pathological conditions has been presented in several studies. It has been proved that the crucial factor in triggering this upregulation is proinflammatory cytokines. Moreover, scar formation is an important barrier to axonal regeneration through the lesion area. Melatonin plays an important role in reducing inflammation, but its effects on scar formation in the injured spinal cord remain unknown. Hence, we used the model of severe crush injury in mice to investigate the effects of melatonin on scar formation. Mice were randomly separated into four groups; SCI, SCI+Melatonin 1 (single dose), SCI+Melatonin 14 (14 daily doses), and control. Melatonin was administered by intraperitoneal injection (10 mg/kg) after injury. Immunohistochemical analysis, Western blot, and behavioral evaluation were used to explore the effects of melatonin after SCI for 14 days. The melatonin-treated mice presented higher expression of neuronal markers (P < 0.001). Remarkably, the inflammatory response appeared to be greatly reduced in the SCI+Melatonin 14 group (P < 0.001), which also displayed less scar formation (P < 0.05). These findings suggest that melatonin inhibits scar formation by acting on inflammatory cytokines after SCI. Overall, our results suggest that melatonin is a promising treatment strategy after SCI that deserves further investigation. © 2016 Wiley Periodicals, Inc.

Identification of molecular pathway changes after spinal cord injury by microarray analysis

Background

Spinal cord injury (SCI) is highly related to the devastating sensory and motor dysfunction.

Methods

The GSE45006 gene expression profile dataset was downloaded from Gene Expression Omnibus, which was collected from 24 rats including 20 animals with injured T7 spinal cords using an aneurysm clip impact-compression injury model and killed after 1 day, 3 days, 1 week, 2 weeks, and 8 weeks and four sham-operated rats. Differentially expressed genes (DEGs) between the injured rats at each time point and the sham-operated rats were screened. DEGs commonly detected throughout different time points were further identified, followed by comparing the expression level of these DEGs at each time point between the injured spinal cord samples and controls. Pathway enrichment analysis of the common DEGs was performed.

Results

The difference in the expression level of 416 common DEGs was significant between the injured spinal cord samples and the controls at each time point (P < 0.05), with the most significant difference 1 day after SCI. The common DEGs were enriched in three pathways, namely Fcγ R-mediated phagocytosis, mitogen-activated protein kinase (MAPK) signaling pathway, and chemokine signaling pathway. AKT3 and RAC2 were enriched in all the three pathways; RAP1B in both MAPK signaling pathway and chemokine signaling pathway; and VAV1, LYN, and HCK in both Fcγ R-mediated phagocytosis and chemokine signaling pathway.

Conclusions

This study has confirmed the occurrence of neuronal death, inflammation, and neuronal regeneration after SCI. AKT3, RAC2, VAV1, RAP18, LYN, and HCK may have critical roles in the pathological responses to SCI.

Transplantation of Neural Stem Cells Cultured in Alginate Scaffold for Spinal Cord Injury in Rats

Study Design

This study investigated the effects of transplantation of alginate encapsulated neural stem cells (NSCs) on spinal cord injury in Sprague-Dawley male rats. The neurological functions were assessed for 6 weeks after transplantation along with a histological study and measurement of caspase-3 levels.

Purpose

The aim of this study was to discover whether NSCs cultured in alginate transplantation improve recovery from spinal cord injury.

Overview of Literature

Spinal cord injury is one of the leading causes of disability and it has no effective treatment. Spinal cord injury can also cause sensory impairment. With an impetus on using stem cells therapy in various central nervous system settings, there is an interest in using stem cells for addressing spinal cord injury. Neural stem cell is one type of stem cells that is able to differentiate to all three neural lineages and it shows promise in spinal injury treatment. Furthermore, a number of studies have shown that culturing NSCs in three-dimensional (3D) scaffolds like alginate could enhance neural differentiation.

Methods

The NSCs were isolated from 14-day-old rat embryos. The isolated NSCs were cultured in growth media containing basic fibroblast growth factor and endothelial growth factor. The cells were characterized by differentiating to three neural lineages and they were cultured in an alginate scaffold. After 7 days the cells were encapsulated and transplanted in a rat model of spinal cord injury.

Results

Our data showed that culturing in an alginate 3D scaffold and transplantation of the NSCs could improve neurological outcome in a rat model of spinal cord injury. The inflammation scores and lesion sizes and also the activity of caspase-3 (for apoptosis evaluation) were less in encapsulated neural stem cell transplantation cases.

Conclusions

Transplantation of NSCs that were cultured in an alginate scaffold led to a better clinical and histological outcome for recovery from spinal cord injury in a rat model.

Cytokine and Growth Factor Activation In Vivo and In Vitro after Spinal Cord Injury

Spinal cord injury results in a life-disrupting series of deleterious interconnected mechanisms encompassed by the primary and secondary injury. These events are mediated by the upregulation of genes with roles in inflammation, transcription, and signaling proteins. In particular, cytokines and growth factors are signaling proteins that have important roles in the pathophysiology of SCI. The balance between the proinflammatory and anti-inflammatory effects of these molecules plays a critical role in the progression and outcome of the lesion. The excessive inflammatory Th1 and Th17 phenotypes observed after SCI tilt the scale towards a proinflammatory environment, which exacerbates the deleterious mechanisms present after the injury. These mechanisms include the disruption of the spinal cord blood barrier, edema and ion imbalance, in particular intracellular calcium and sodium concentrations, glutamate excitotoxicity, free radicals, and the inflammatory response contributing to the neurodegenerative process which is characterized by demyelination and apoptosis of neuronal tissue.

Inflammogenesis of Secondary Spinal Cord Injury

Spinal cord injury (SCI) and spinal infarction lead to neurological complications and eventually to paraplegia or quadriplegia. These extremely debilitating conditions are major contributors to morbidity. Our understanding of SCI has certainly increased during the last decade, but remains far from clear. SCI consists of two defined phases: the initial impact causes primary injury, which is followed by a prolonged secondary injury consisting of evolving sub-phases that may last for years. The underlying pathophysiological mechanisms driving this condition are complex. Derangement of the vasculature is a notable feature of the pathology of SCI. In particular, an important component of SCI is the ischemia-reperfusion injury (IRI) that leads to endothelial dysfunction and changes in vascular permeability. Indeed, together with endothelial cell damage and failure in homeostasis, ischemia reperfusion injury triggers full-blown inflammatory cascades arising from activation of residential innate immune cells (microglia and astrocytes) and infiltrating leukocytes (neutrophils and macrophages). These inflammatory cells release neurotoxins (proinflammatory cytokines and chemokines, free radicals, excitotoxic amino acids, nitric oxide (NO)), all of which partake in axonal and neuronal deficit. Therefore, our review considers the recent advances in SCI mechanisms, whereby it becomes clear that SCI is a heterogeneous condition. Hence, this leads towards evidence of a restorative approach based on monotherapy with multiple targets or combinatorial treatment. Moreover, from evaluation of the existing literature, it appears that there is an urgent requirement for multi-centered, randomized trials for a large patient population. These clinical studies would offer an opportunity in stratifying SCI patients at high risk and selecting appropriate, optimal therapeutic regimens for personalized medicine.

Neuroprotective Effect of Ginsenoside Rd in Spinal Cord Injury Rats

In this study, the neuroprotective effects of ginsenoside Rd (GS Rd) were evaluated in a rat model of spinal cord injury (SCI). Rats in SCI groups received a T8 laminectomy and a spinal contusion injury. GS Rd 12.5, 25 and 50 mg/kg were administered intraperitoneally 1 hr before the surgery and once daily for 14 days. Dexamethasone 1 mg/kg was administered as a positive control. Locomotor function was evaluated using the BBB score system. H&E staining and Nissl staining were performed to observe the histological changes in the spinal cord. The levels of MDA and GSH and the activity of SOD were assessed to reflect the oxidative stress state. The production of TNF-α, IL-1β and IL-1 was assessed using ELISA kits to examine the inflammatory responses in the spinal cord. TUNEL staining was used to detect the cell apoptosis in the spinal cord. Western blot analysis was used to examine the expression of apoptosis-associated proteins and MAPK proteins. The results demonstrated that GS Rd 25 and 50 mg/kg significantly improved the locomotor function of rats after SCI, reduced tissue injury and increased neuron survival in the spinal cord. Mechanically, GS Rd decreased MDA level, increased GSH level and SOD activity, reduced the production of pro-inflammatory cytokines and prevented cell apoptosis. The effects were equivalent to those of dexamethasone. In addition, GS Rd effectively inhibited the activation of MAPK signalling pathway induced by SCI, which might be involved in the protective effects of GS Rd against SCI. In conclusion, GS Rd attenuates SCI-induced secondary injury through reversing the redox-state imbalance, inhibiting the inflammatory response and apoptosis in the spinal cord tissue.

Effect of adenovirus-mediated RNA interference of IL-1β expression on spinal cord injury in rats

STUDY DESIGN

We introduced an adenoviral vector expressing interleukin-1β (IL-1β) small-hairpin RNA (shRNA) into the injured spinal cords to evaluate the therapeutic potential of IL-1β downregulation in a rat model of spinal cord injury (SCI).

OBJECTIVES

The purpose of this study was to investigate the possible protective effects of the IL-1β downregulation on traumatic SCI in rats.

SETTING

Department of Orthopedic Surgery, The Second Affiliated Hospital, Fujian Medical University, Quanzhou, People's Republic of China.

METHODS

An adenoviral shRNA targeting IL-1β was constructed and injected at the T12 section 7 days before SCI. The rats' motor functions were evaluated by the Basso-Beattie-Bresnahan (BBB) rating scale. Immunofluorescence, enzyme-linked immunosorbent assay, flow-cytometric analysis and western blots were also performed.

RESULTS

Animals downregulating IL-1β had significantly better recovery of locomotor function and less neuronal loss after SCI. In addition, IL-1β downregulation significantly decreased tumor necrosis factor-alpha (TNF-α) level and Bax expression, reduced the activity of caspase-3 and increased Bcl-2 expression after SCI.

CONCLUSION

This study demonstrated that the IL-1β downregulation may have potential therapeutic benefits for both reducing secondary damages and improving the outcomes after traumatic SCI.

Inflammation is increased with anxiety- and depression-like signs in a rat model of spinal cord injury

Spinal cord injury (SCI) leads to increased anxiety and depression in as many as 60% of patients. Yet, despite extensive clinical research focused on understanding the variables influencing psychological well-being following SCI, risk factors that decrease it remain unclear. We hypothesized that excitation of the immune system, inherent to SCI, may contribute to the decrease in psychological well-being. To test this hypothesis, we used a battery of established behavioral tests to assess depression and anxiety in spinally contused rats. The behavioral tests, and subsequent statistical analyses, revealed three cohorts of subjects that displayed behavioral characteristics of (1) depression, (2) depression and anxiety, or (3) no signs of decreased psychological well-being. Subsequent molecular analyses demonstrated that the psychological cohorts differed not only in behavioral symptoms, but also in peripheral (serum) and central (hippocampi and spinal cord) levels of pro-inflammatory cytokines. Subjects exhibiting a purely depression-like profile showed higher levels of pro-inflammatory cytokines peripherally, whereas subjects exhibiting a depression- and anxiety-like profile showed higher levels of pro-inflammatory cytokines centrally (hippocampi and spinal cord). These changes in inflammation were not associated with injury severity; suggesting that the association between inflammation and the expression of behaviors characteristic of decreased psychological well-being was not confounded by differential impairments in motor ability. These data support the hypothesis that inflammatory changes are associated with decreased psychological well-being following SCI.

The Incremental Induction of Neuroprotective Properties by Multiple Therapeutic Strategies for Primary and Secondary Neural Injury

Neural diseases including injury by endogenous factors, traumatic brain injury, and degenerative neural injury are eventually due to reactive oxygen species (ROS). Thus ROS generation in neural tissues is a hallmark feature of numerous forms of neural diseases. Neural degeneration and the neural damage process is complex, involving a vast array of tissue structure, transcriptional/translational, electrochemical, metabolic, and functional events within the intact neighbors surrounding injured neural tissues. During aging, multiple changes involving physical, chemical, and biochemical processes occur from the molecular to the morphological levels in neural tissues. Among many recommended therapeutic candidates, melatonin also plays a role in protecting the nervous system from anti-inflammation and efficiently safeguards neuronal cells via antioxidants and other endogenous/exogenous beneficial factors. Therefore, given the wide range of mechanisms responsible for neuronal damage, multi-action drugs or therapies for the treatment of neural injury that make use of two or more agents and target several pathways may have greater efficacy in promoting functional recovery than a single therapy alone.

Cell Therapy Augments Functional Recovery Subsequent to Spinal Cord Injury under Experimental Conditions

The spinal cord injury leads to enervation of normal tissue homeostasis ultimately leading to paralysis. Until now there is no proper cure for the treatment of spinal cord injury. Recently, cell therapy in animal spinal cord injury models has shown some progress of recovery. At present, clinical trials are under progress to evaluate the efficacy of cell transplantation for the treatment of spinal cord injury. Different types of cells such as pluripotent stem cells derived neural cells, mesenchymal stromal cells, neural stem cells, glial cells are being tested in various spinal cord injury models. In this review we highlight both the advances and lacuna in the field of spinal cord injury by discussing epidemiology, pathophysiology, molecular mechanism, and various cell therapy strategies employed in preclinical and clinical injury models and finally we discuss the limitations and ethical issues involved in cell therapy approach for treating spinal cord injury.

Regulation of gene expression in rats with spinal cord injury based on microarray data

The present study aimed to investigate the molecular mechanisms of spinal cord injury (SCI) in rats. First, the differentially expressed genes (DGEs) were screened based on GSE45006 microarray data downloaded from Gene Expression Omnibus using the significant analysis of microarray (SAM) method. Screening was performed for DEGs which were negatively or possibly correlated with time and subsequently subjected to gene ontology (GO) functional annotation. Furthermore, pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes was also performed. In addition, a protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database. Finally, GeneCodis was used to seek transcription factors and microRNAs that are involved in the regulation of DEGs. A total of 806 DEGs were upregulated and 549 DEGs were downregulated in the rats with SCI. Cholesterol metabolism-associated genes (e.g. HMGCS1, FDFT1 and IDI1) were negatively correlated with time, while injury genes (e.g. SERPING1, C1S and RAB27A) were positively correlated with time after SCI. PCNA, MCM2, JUN and SNAP25 were the hub proteins of the PPI network. The transcription factors LEF1 and SP1 were observed to be associated with the regulation of two DEGs that were involved in the cholesterol-associated metabolism as well as injury responses. A number of microRNAs (e.g. miR210, miR-487b and miR-16) were observed to target cholesterol metabolism-associated DGEs. The hub genes PCNA, MCM2, JUN and SNAP25 presumably have critical roles in rats with SCI, and the transcription factors LEF1 and SP1 may be important for the regulation of cholesterol metabolism and injury responses following SCI.

Early inflammatory mediator gene expression in two models of traumatic brain injury: ex vivo cortical slice in mice and in vivo cortical impact in piglets

Background

The immunological response during the first 24 hours after traumatic brain injury (TBI) may be a critical therapeutic interval for limiting the secondary neuronal damage that is influenced by enhanced inflammatory mediator expression.

Methods

To gain further insight of the early injury response, we examined the expression of several inflammatory genes by real-time qPCR as a function of time or distance from injury in two distinct mammalian models: an ex vivo mouse cortical slice injury system and an in vivo piglet model of brain injury.

Results

Interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), chemokine ligands 2 (CCL2), 3 (CCL3), 4 (CCL4), and prostaglandin-endoperoxide synthase 2 (PTGS2) mRNAs increased within 5 h after injury in mouse cortical slices. Chemokine and PTGS2 mRNAs remained elevated in slices at 24 h, whereas IL-1β and TNF-α expressions decreased from earlier peak levels. At 24 h after cortical injury in 1-month-old piglets, the expression of CCL2 mRNA was significantly increased in the lesion core and in the penumbra region. The expression of PTGS2, IL-1β, and TNF-α was variable among the piglets.

Conclusions

These in vitro and large animal models of cortical injury expand our understanding of the early timing and spread of the immunological response and can serve as preclinical systems to facilitate the discovery of therapeutic agents for TBI aimed at regulating inflammatory mediator expression.

Inhibition of monocyte chemoattractant peptide-1 decreases secondary spinal cord injury

Previous studies have suggested that impairment secondary to mechanical injury is a major cause of irreversible damage to the spinal cord. Inflammatory chemokines have been shown to play an important role in the pathological and physiological consequences of secondary spinal cord injury (SCI). The aim of the present study was to evaluate how changes in the expression levels of the cellular chemokine, monocyte chemoattractant peptide-1 (MCP-1), and the chemotaxis of inflammatory cells (monocytes and macrophages) are involved in the process of SCI. RNA interference methods were used to study the mechanisms that protect residual neurons after SCI in an attempt to explore novel, early interventions for managing SCI. Our results suggested that inhibiting inflammation alleviates nerve cell injury caused by apoptosis and provides a potentially important approach for the future treatment of secondary SCI.

The role of the JAK-STAT pathway in neural stem cells, neural progenitor cells and reactive astrocytes after spinal cord injury

Patients with spinal cord injuries can develop severe neurological damage and dysfunction, which is not only induced by primary but also by secondary injuries. As an evolutionarily conserved pathway of eukaryotes, the JAK-STAT pathway is associated with cell growth, survival, development and differentiation; activation of the JAK-STAT pathway has been previously reported in central nervous system injury. The JAK-STAT pathway is directly associated with neurogenesis and glia scar formation in the injury region. Following injury of the axon, the overexpression and activation of STAT3 is exhibited specifically in protecting neurons. To investigate the role of the JAK-STAT pathway in neuroprotection, we summarized the effect of JAK-STAT pathway in the following three sections: Firstly, the modulation of JAK-STAT pathway in proliferation and differentiation of neural stem cells and neural progenitor cells is discussed; secondly, the time-dependent effect of JAK-STAT pathway in reactive astrocytes to reveal their capability of neuroprotection is revealed and lastly, we focus on how the astrocyte-secretory polypeptides (astrocyte-derived cytokines and trophic factors) accomplish neuroprotection via the JAK-STAT pathway.

Associated occurrence of p75 neurotrophin receptor expressing aldynoglia and microglia/macrophages in long term organotypic murine brain slice cultures

Growth-promoting aldynoglia, characterized by the expression of the prototype immature Schwann cell marker p75 neurotrophin receptor (NTR) have been shown to occur in some demyelinating diseases. However, the mechanisms determining the emergence and fate of such cells are largely unknown. This study aimed at the identification of such cells and potential triggering factors using an in vitro slice culture approach. Organotypic cerebrum and brain stem slices of adult mice were cultivated for up to 18 days in vitro. Immunohistochemistry for the detection of p75(NTR), CD107b, periaxin, growth associated protein (GAP)-43, and glial fibrillary acidic protein (GFAP) was performed. The results for p75(NTR) were substantiated by the use of in situ hybridization. Cultivation was associated with a progressively increasing spontaneous occurrence of bi- to multipolar p75(NTR)-positive, but periaxin-negative glia, indicative of aldynoglial Schwann cell like cells. Similar cells stained intensely positive for GAP-43, a marker for non-myelinating Schwann cells. The number of p75(NTR) positive glia did not correlate with GFAP expression, but showed a strong correlation with a remarkable spontaneous response of CD107b positive phagocytic microglia/macrophages. Moreover, aldynoglial p75(NTR) immunoreactivity negatively correlated to neuronal p75(NTR) expression, which was lost during culturing. The present results demonstrate that the cultivation of organotypic murine brain slices is accompanied by a spontaneous response of both microglia/macrophages and p75(NTR) positive cells, suggestive of Schwann cell like aldynoglia. The findings highlights the role of microglia/macrophages, which seem to be an important triggering factor, facilitating the occurrence of this unique type of macroglia.

New aspects of the pathogenesis of canine distemper leukoencephalitis

Canine distemper virus (CDV) is a member of the genus morbillivirus, which is known to cause a variety of disorders in dogs including demyelinating leukoencephalitis (CDV-DL). In recent years, substantial progress in understanding the pathogenetic mechanisms of CDV-DL has been made. In vivo and in vitro investigations provided new insights into its pathogenesis with special emphasis on axon-myelin-glia interaction, potential endogenous mechanisms of regeneration, and astroglial plasticity. CDV-DL is characterized by lesions with a variable degree of demyelination and mononuclear inflammation accompanied by a dysregulated orchestration of cytokines as well as matrix metalloproteinases and their inhibitors. Despite decades of research, several new aspects of the neuropathogenesis of CDV-DL have been described only recently. Early axonal damage seems to represent an initial and progressive lesion in CDV-DL, which interestingly precedes demyelination. Axonopathy may, thus, function as a potential trigger for subsequent disturbed axon-myelin-glia interactions. In particular, the detection of early axonal damage suggests that demyelination is at least in part a secondary event in CDV-DL, thus challenging the dogma of CDV as a purely primary demyelinating disease. Another unexpected finding refers to the appearance of p75 neurotrophin (NTR)-positive bipolar cells during CDV-DL. As p75NTR is a prototype marker for immature Schwann cells, this finding suggests that Schwann cell remyelination might represent a so far underestimated endogenous mechanism of regeneration, though this hypothesis still remains to be proven. Although it is well known that astrocytes represent the major target of CDV infection in CDV-DL, the detection of infected vimentin-positive astrocytes in chronic lesions indicates a crucial role of this cell population in nervous distemper. While glial fibrillary acidic protein represents the characteristic intermediate filament of mature astrocytes, expression of vimentin is generally restricted to immature or reactive astrocytes. Thus, vimentin-positive astrocytes might constitute an important cell population for CDV persistence and spread, as well as lesion progression. In vitro models, such as dissociated glial cell cultures, as well as organotypic brain slice cultures have contributed to a better insight into mechanisms of infection and certain morphological and molecular aspects of CDV-DL. Summarized, recent in vivo and in vitro studies revealed remarkable new aspects of nervous distemper. These new perceptions substantially improved our understanding of the pathogenesis of CDV-DL and might represent new starting points to develop novel treatment strategies.