Acute inflammatory response in spinal cord following impact injury

Protective effects of 3,4-dihydroxyphenylethanol on spinal cord injury-induced oxidative stress and inflammation

3,4-Dihydroxyphenylethanol (DOPET) is a potent antioxidant polyphenolic compound. In this study, our objective was to investigate the underlying mechanism of the neuroprotective role of DOPET in attenuating spinal cord injury (SCI). Initially, SCI was induced by performing surgical laminectomy on the rats at T10-T12 level. Then, the neurological function-dependent locomotion was measured using Basso Beattie Bresnahan score, which declined in the SCI-induced group. Increased antioxidant levels such as superoxide dismutase, glutathione peroxidase, and glutathione along with other parameters such as increased lipid peroxidation (LPO) and myeloperoxidase (MPO) activities were all observed in the SCI group. Levels of proinflammatory cytokines such as tumor necrosis factor-α and interleukin-1β were upregulated in the serum and spinal cord tissue as observed on the immunoblot. Interestingly, protein levels of apoptotic markers such as Bax, cleaved caspase 3 and RT-PCR analysis-based mRNA level of pro-inflammatory cytokine, nuclear factor- κ activated B cells (NF-κB) were significantly upregulated in the spinal cord tissue. Nonetheless, antiapoptotic factor such as B-cell lymphoma 2 (Bcl-2) protein expression was downregulated in the same group. However, on administering 10 mg/kg of DOPET, the neuronal function was rescued, antioxidants were restored back to the normal levels, LPO and MPO activities were reduced in conjunction with downregulated levels of proinflammatory cytokines and apoptotic markers in the SCI group. These findings show that DOPET could potentially target multiple signalling pathways to combat SCI.

Experimental Pulmonary Hypertension Is Associated With Neuroinflammation in the Spinal Cord

Rationale

Pulmonary hypertension (PH) is a rare but fatal disease characterized by elevated pulmonary pressures and vascular remodeling, leading to right ventricular failure and death. Recently, neuroinflammation has been suggested to be involved in the sympathetic activation in experimental PH. Whether PH is associated with neuroinflammation in the spinal cord has never been investigated.

Methods/Results

PH was well-established in adult male Wistar rats 3-week after pulmonary endothelial toxin Monocrotaline (MCT) injection. Using the thoracic segments of the spinal cord, we found a 5-fold increase for the glial fibrillary acidic protein (GFAP) in PH rats compared to controls (p < 0.05). To further determine the region of the spinal cord where GFAP was expressed, we performed immunofluorescence and found a 3 to 3.5-fold increase of GFAP marker in the gray matter, and a 2 to 3-fold increase in the white matter in the spinal cord of PH rats compared to controls. This increase was due to PH (MCT vs. Control; p < 0.01), and there was no difference between the dorsal versus ventral region. PH rats also had an increase in the pro-inflammatory marker chemokine (C-C motif) ligand 3 (CCL3) protein expression (∼ 3-fold) and (2.8 to 4-fold, p < 0.01) in the white matter. Finally, angiogenesis was increased in PH rat spinal cords assessed by the adhesion molecule CD31 expression (1.5 to 2.3-fold, p < 0.01).

Conclusion

We report for the first time evidence for neuroinflammation in the thoracic spinal cord of pulmonary hypertensive rats. The impact of spinal cord inflammation on cardiopulmonary function in PH remains elusive.

Notoginsenoside R1 alleviates lipopolysaccharide-triggered PC-12 inflammatory damage via elevating microRNA-132

BACKGROUND

Delayed inflammatory response is closely associated with the severity of Spinal cord injury (SCI). Herein, the function and molecular mechanism of notoginsenoside R1 (NGR1) in the in vitro model of SCI inflammation injury were explored.

METHODS

PC-12 neuronal cells were subjected with LPS to construct a cell-based model of SCI inflammatory injury. NGR1 was applied in this cell model. miR-132 was silenced by transfection with miR-132 inhibitor. Cell viability and apoptosis were assessed, respectively. Then, the expression changes of pro-inflammatory cytokines and JNK pathway were examined.

RESULTS

In this model, LPS was neurotoxic, with inhibiting PC-12 cell viability, inducing apoptosis, and enhancing concentrations of IL-6, IL-8 and TNF-α. However, NGR1 weakened the influence of LPS on PC-12 cells via elevating cell viability, decreasing apoptosis, decreasing pro-inflammatory cytokines expression, and suppressing activation of JNK signalling pathway. miR-132 was up-regulated by NGR1 treatment. Silence of miR-132 eliminated the influence of NGR1 on LPS-stimulated PC-12 cells.

CONCLUSION

NGR1 relieved PC-12 cells from LPS-triggered inflammatory damage via elevating miR-132 and hereafter suppressing JNK pathway.

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.

Combinational protective therapy for spinal cord injury medicated by sialic acid-driven and polyethylene glycol based micelles

Spinal cord injury (SCI) leads to immediate disruption of neuronal membranes and loss of neurons, followed by extensive secondary injury process. Treatment of SCI still remains a tremendous challenge clinically. Minocycline could target comprehensive secondary injury via anti-inflammatory, anti-oxidant and anti-apoptotic mechanisms. Polyethylene glycol (PEG), a known sealing agent, is able to seal the damaged cell membranes and reduce calcium influx, thereby exerting neuroprotective capacity. Here, an E-selectin-targeting sialic acid - polyethylene glycol - poly (lactic-co-glycolic acid) (SAPP) copolymer was designed for delivering hydrophobic minocycline to achieve combinational therapy of SCI. The obtained SAPP copolymer could self-assemble into micelles with critical micelle concentration being of 13.40 μg/mL, and effectively encapsulate hydrophobic minocycline. The prepared drug-loaded micelles (SAPPM) displayed sustained drug release over 72 h, which could stop microglia activation and exhibited excellent neuroprotective capacity in vitro. The SAPP micelles were efficiently accumulated in the lesion site of SCI rats via the specific binding between sialic acid and E-selectin. Due to the targeting distribution and combinational effect between PEG and minocycline, SAPPM could obviously reduce the area of lesion cavity, and realize more survival of axons and myelin sheaths from the injury, thus distinctly improving hindlimb functional recovery of SCI rats and conferring superior therapeutic effect in coparison with other groups. Our work presented an effective and safe strategy for SCI targeting therapy. Besides, neuroprotective capacity of PEG deserves further investigation on other central nervous system diseases.

Complement receptor C3aR1 controls neutrophil mobilization following spinal cord injury through physiological antagonism of CXCR2

Traumatic spinal cord injury (SCI) triggers an acute-phase response that leads to systemic inflammation and rapid mobilization of bone marrow (BM) neutrophils into the blood. These mobilized neutrophils then accumulate in visceral organs and the injured spinal cord where they cause inflammatory tissue damage. The receptor for complement activation product 3a, C3aR1, has been implicated in negatively regulating the BM neutrophil response to tissue injury. However, the mechanism via which C3aR1 controls BM neutrophil mobilization, and also its influence over SCI outcomes, are unknown. Here, we show that the C3a/C3aR1 axis exerts neuroprotection in SCI by acting as a physiological antagonist against neutrophil chemotactic signals. We show that C3aR1 engages phosphatase and tensin homolog (PTEN), a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, to restrain C-X-C chemokine receptor type 2-driven BM neutrophil mobilization following trauma. These findings are of direct clinical significance as lower circulating neutrophil numbers at presentation were identified as a marker for improved recovery in human SCI. Our work thus identifies C3aR1 and its downstream intermediary, PTEN, as therapeutic targets to broadly inhibit neutrophil mobilization/recruitment following tissue injury and reduce inflammatory pathology.

Trehalose attenuates spinal cord injury through the regulation of oxidative stress, inflammation and GFAP expression in rats

OBJECTIVE

Inflammation and oxidative stress are implicated in pathogenesis of spinal cord injury (SCI). Trehalose, a nonreducing disaccharide, exhibits anti-inflammatory and antioxidant effects. The present study investigated the therapeutic efficacy of trehalose in the SCI model.

DESIGN AND SETTING

An experimental study was designed using 120 male Wistar rats which were randomly divided into three groups including SCI, SCI + phosphate buffer saline (vehicle) and SCI + trehalose. All rats were subjected to SCI. Immediately after SCI, vehicle and trehalose groups received intrathecal injection of buffer and trehalose, respectively.

OUTCOME MEASURES

The level of tissue TNFα, IL-1β, nitric oxide, malondialdehyde, myeloperoxidase, glial fibrillary acidic protein (GFAP) as well as hindlimb function were assessed at 4 hours, 1, 3 and 7 days post-SCI.

RESULTS

Data indicated an early significant decrease in inflammatory and oxidative responses following SCI in trehalose treated group. Moreover, trehalose reduced GFAP expression as soon as 1-day post-trauma. Furthermore, trehalose treatment increased the score of hindlimb function.

CONCLUSION

Our results indicated that treatment with trehalose reduces the development of secondary injury associated with SCI. This effect likely underlies improved neurological function.

Macrophage centripetal migration drives spontaneous healing process after spinal cord injury

Traumatic spinal cord injury (SCI) brings numerous inflammatory cells, including macrophages, from the circulating blood to lesions, but pathophysiological impact resulting from spatiotemporal dynamics of macrophages is unknown. Here, we show that macrophages centripetally migrate toward the lesion epicenter after infiltrating into the wide range of spinal cord, depending on the gradient of chemoattractant C5a. However, macrophages lacking interferon regulatory factor 8 (IRF8) cannot migrate toward the epicenter and remain widely scattered in the injured cord with profound axonal loss and little remyelination, resulting in a poor functional outcome after SCI. Time-lapse imaging and P2X/YRs blockade revealed that macrophage migration via IRF8 was caused by purinergic receptors involved in the C5a-directed migration. Conversely, pharmacological promotion of IRF8 activation facilitated macrophage centripetal movement, thereby improving the SCI recovery. Our findings reveal the importance of macrophage centripetal migration via IRF8, providing a novel therapeutic target for central nervous system injury.

Acute Spinal Cord Injury: A Systematic Review Investigating miRNA Families Involved

Acute traumatic spinal cord injury (SCI) involves primary and secondary injury mechanisms. The primary mechanism is related to the initial traumatic damage caused by the damaging impact and this damage is irreversible. Secondary mechanisms, which begin as early as a few minutes after the initial trauma, include processes such as spinal cord ischemia, cellular excitotoxicity, ionic dysregulation, and free radical-mediated peroxidation. SCI is featured by different forms of injury, investigating the pathology and degree of clinical diagnosis and treatment strategies, the animal models that have allowed us to better understand this entity and, finally, the role of new diagnostic and prognostic tools such as miRNA could improve our ability to manage this pathological entity. Autopsy could benefit from improvements in miRNA research: the specificity and sensitivity of miRNAs could help physicians in determining the cause of death, besides the time of death.

Polysialic-Acid-Based Micelles Promote Neural Regeneration in Spinal Cord Injury Therapy

Spinal cord injury (SCI) routinely causes the immediate loss and disruption of neurons followed by complicated secondary injuries, including inflammation, oxidative stress, and dense glial scar formation. Inhibitory factors in the lesion scar and poor intrinsic neural regeneration capacity restrict functional recovery after injury. Minocycline, which has neuroprotective activity, can alleviate secondary injury, but the long-term administration of this drug may cause toxicity. Polysialic acid (PSA) is a large cell-surface carbohydrate that is critical for central nervous system development and is capable of promoting precursor cell migration, axon path finding, and synaptic remodeling; thus, PSA plays a vital role in tissue repair and regeneration. Here, we developed a PSA-based minocycline-loaded nanodrug delivery system (PSM) for the synergistic therapy of spinal cord injury. The prepared PSM exerted marked anti-inflammatory and neuroprotective activities both in vitro and in vivo. The administration of PSM could significantly protect neurons and myelin sheaths from damage, reduce the formation of glial scar, recruit endogenous neural stem cells to the lesion site, and promote the regeneration of neurons and the extension of long axons throughout the glial scar, thereby largely improving the locomotor function of SCI rats and exerting a superior therapeutic effect. The findings might provide a novel strategy for SCI synergistic therapy and the utilization of PSA in other central nervous system diseases.

Protocatechuic acid improves functional recovery after spinal cord injury by attenuating blood-spinal cord barrier disruption and hemorrhage in rats

After spinal cord injury (SCI), blood-spinal cord barrier (BSCB) disruption and hemorrhage lead to blood cell infiltration and progressive secondary injuries including inflammation. Inflammatory response is one of the major events resulting in apoptosis, scar formation and neuronal dysfunction after SCI. Here, we investigated whether protocatechuic acid (PCA), a natural phenolic compound, would attenuate BSCB disruption and hemorrhage, leading to functional improvement after SCI. After a moderate contusion injury at T9, PCA (50 mg/kg) was administrated via intraperitoneal injection immediately, 6 h, and 12 h after SCI, and the same dose of PCA once a day until 7 d after injury. Our data show that PCA inhibited apoptotic cell death of neurons and oligodendrocytes and improved functional recovery after injury. PCA also attenuated BSCB disruption and hemorrhage and reduced the infiltration of neutrophils and macrophages compared to vehicle control. Moreover, PCA inhibited the expression and activation of matrix metalloprotease-9, which is well known to disrupt BSCB after SCI. Furthermore, PCA treatment significantly inhibited the expression of sulfonylurea receptor 1 and transient receptor potential melastatin 4, which are known to mediate hemorrhage at an early stage after SCI. Consistent with these findings, the mRNA and protein expression of inflammatory mediators such as tumor necrosis factor alpha, interleukin 1 beta, cyclooxygenase-2, inducible nitric oxide synthase, and chemokines was significantly alleviated by PCA treatment. Thus, our results suggest that PCA improved functional recovery after SCI in part by inhibiting BSCB disruption and hemorrhage through the down-regulation of sulfonylurea receptor 1/transient receptor potential melastatin 4 and matrix metalloprotease-9.

Bioinformatics analyses of differentially expressed genes associated with spinal cord injury: A microarray-based analysis in a mouse model

Gene spectrum analysis has shown that gene expression and signaling pathways change dramatically after spinal cord injury, which may affect the microenvironment of the damaged site. Microarray analysis provides a new opportunity for investigating diagnosis, treatment, and prognosis of spinal cord injury. However, differentially expressed genes are not consistent among studies, and many key genes and signaling pathways have not yet been accurately studied. GSE5296 was retrieved from the Gene Expression Omnibus DataSet. Differentially expressed genes were obtained using R/Bioconductor software (expression changed at least two-fold; P < 0.05). Database for Annotation, Visualization and Integrated Discovery was used for functional annotation of differentially expressed genes and Animal Transcription Factor Database for predicting potential transcription factors. The resulting transcription regulatory protein interaction network was mapped to screen representative genes and investigate their diagnostic and therapeutic value for disease. In total, this study identified 109 genes that were upregulated and 30 that were downregulated at 0.5, 4, and 24 hours, and 3, 7, and 28 days after spinal cord injury. The number of downregulated genes was smaller than the number of upregulated genes at each time point. Database for Annotation, Visualization and Integrated Discovery analysis found that many inflammation-related pathways were upregulated in injured spinal cord. Additionally, expression levels of these inflammation-related genes were maintained for at least 28 days. Moreover, 399 regulation modes and 77 nodes were shown in the protein-protein interaction network of upregulated differentially expressed genes. Among the 10 upregulated differentially expressed genes with the highest degrees of distribution, six genes were transcription factors. Among these transcription factors, ATF3 showed the greatest change. ATF3 was upregulated within 30 minutes, and its expression levels remained high at 28 days after spinal cord injury. These key genes screened by bioinformatics tools can be used as biological markers to diagnose diseases and provide a reference for identifying therapeutic targets.

The Biology of Regeneration Failure and Success After Spinal Cord Injury

Since no approved therapies to restore mobility and sensation following spinal cord injury (SCI) currently exist, a better understanding of the cellular and molecular mechanisms following SCI that compromise regeneration or neuroplasticity is needed to develop new strategies to promote axonal regrowth and restore function. Physical trauma to the spinal cord results in vascular disruption that, in turn, causes blood-spinal cord barrier rupture leading to hemorrhage and ischemia, followed by rampant local cell death. As subsequent edema and inflammation occur, neuronal and glial necrosis and apoptosis spread well beyond the initial site of impact, ultimately resolving into a cavity surrounded by glial/fibrotic scarring. The glial scar, which stabilizes the spread of secondary injury, also acts as a chronic, physical, and chemo-entrapping barrier that prevents axonal regeneration. Understanding the formative events in glial scarring helps guide strategies towards the development of potential therapies to enhance axon regeneration and functional recovery at both acute and chronic stages following SCI. This review will also discuss the perineuronal net and how chondroitin sulfate proteoglycans (CSPGs) deposited in both the glial scar and net impede axonal outgrowth at the level of the growth cone. We will end the review with a summary of current CSPG-targeting strategies that help to foster axonal regeneration, neuroplasticity/sprouting, and functional recovery following SCI.

CSF1R Inhibition Reduces Microglia Proliferation, Promotes Tissue Preservation and Improves Motor Recovery After Spinal Cord Injury

Spinal cord injury (SCI) induces a pronounced neuroinflammation driven by activation and proliferation of resident microglia as well as infiltrating peripheral monocyte-derived macrophages. Depending on the time post-lesion, positive and detrimental influences of microglia/macrophages on axonal regeneration had been reported after SCI, raising the issue whether their modulation may represent an attractive therapeutic strategy. Colony-stimulating factor 1 (CSF1) regulates microglia/macrophages proliferation, differentiation and survival thus, pharmacological treatments using CSF1 receptor (CSF1R) inhibitors had been used to ablate microglia. We analyzed the effect of chronic (10 weeks) food diet containing GW2580 (a CSF1R inhibitor) in mice that underwent lateral spinal cord hemisection (HS) at vertebral thoracic level 9. Treatment started 4 weeks prior to SCI and continued until 6 weeks post-lesion. We first demonstrate that GW2580 treatment did not modify microglial response in non-injured spinal cords. Conversely, a strong decrease in proliferating microglia was observed following SCI. Second, we showed that GW2580 treatment improved some parameters of motor recovery in injured animals through better paw placement. Using in and ex vivo magnetic resonance imaging (MRI), we then established that GW2580 treatment had no effect on lesion extension and volume. However, histological analyses revealed that GW2580-treated animals had reduced gliosis and microcavity formation following SCI. In conclusion, CSF1R blockade using GW2580 specifically inhibits SCI-induced microglia/macrophages proliferation, reduces gliosis and microcavity formations and improves fine motor recovery after incomplete SCI. Preventing microglial proliferation may offer therapeutic approach to limit neuroinflammation, promote tissue preservation and motor recovery following SCI.

Sodium Butyrate Exerts Neuroprotective Effects in Spinal Cord Injury

Sodium butyrate (SB) is a dietary microbial fermentation product and serves as an important neuromodulator in the central nervous system. Recent experimental evidence has suggested potential therapeutic applications for butyrate, including its utility in treating metabolic and inflammatory diseases. The aim of the present study was to evaluate the potential beneficial effects of SB in a mouse model of spinal cord injury (SCI) and its possible mechanism of action. SCI was induced by extradural compression for 1 min of the spinal cord at the T6-7 level using an aneurysm clip, and SB (10-30-100 mg/kg) was administered by oral gavage 1 and 6 h after SCI. For locomotor activity, study mice were treated with SB once daily for 10 days. Morphological examination was performed by light microscopy through hematoxylin-eosin (H&E) staining. In addition, NF-κB, IκB-α, COX-2, and iNOS expressions were assayed by western blot analysis and IL-1β and TNF-α levels by immunohistochemistry analysis. The results showed that SB treatment significantly ameliorated histopathology changes and improved recovery of motor function changes in spinal cord injury in a dose-dependent manner. Moreover, we demonstrated that SB modulated the NF-κB pathway showing a significant reduction in cytokine expression. Thus, this study showed that SB exerts neuroprotective effects anti-inflammatory properties following spinal cord injury suggesting that SB may serve as a potential candidate for future treatment of spinal cord injury.

Zafirlukast in combination with pseudohypericin attenuates spinal cord injury and motor function in experimental mice

Background

Biosynthesis of leukotriene (LT) by arachidonic acid involves 5-lipoxygenase (5-LO) as an important precursor. Here, we evaluated the role of pseudohypericin (PHP) for its postulated 5-LO inhibitory activity along with a Cys-LT receptor antagonist zafirlukast (ZFL) against inflammatory response and tissue injury in mice.

Materials and methods

The spinal injury was induced by two-level laminectomy of T6 and T7 vertebrae. The inflammation was assessed by histology, inflammatory mediators by enzyme-linked immunosorbent assay, apoptosis by Annexin-V, FAS staining, terminal deoxynucleoti-dyltransferase-mediated UTP end labeling (TUNEL) assay and expression of Bax and Bcl-2 by Western blot. Effect on motor recovery of hind limbs was evaluated for 10 days postinjury.

Results

The spinal injury resulted in tissue damage, apoptosis, edema, infiltration of neutrophils with increased expression of tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). The spinal tissue showed elevated levels of prostaglandin E₂ (PGE2), and LTB₄ and increased phosphorylation of injured extracellular signal-regulated kinase-1/2 (ERK1/2). The PHP, ZFL and combination decreased inflammation, tissue injury and infiltration of neutrophils. Treatment also decreased the levels of PGE₂, phosphorylation of extracellular signal-regulated kinase-1/2 (pERK 1/2), LT, TNF-α and COX-2 with a marked reduction in apoptosis and improved the motor function.

Conclusion

The present study confirmed 5-LO antagonist activity of PHP and established its neuroprotective role along with ZFL.

Degeneration of white matter and gray matter revealed by diffusion tensor imaging and pathological mechanism after spinal cord injury in canine

AIM

Exploration of the mechanism of spinal cord degeneration may be the key to treatment of spinal cord injury (SCI). This study aimed to investigate the degeneration of white matter and gray matter and pathological mechanism in canine after SCI.

METHODS

Diffusion tensor imaging (DTI) was performed on canine models with normal (n = 5) and injured (n = 7) spinal cords using a 3.0T MRI scanner at precontusion and 3 hours, 24 hours, 6 weeks, and 12 weeks postcontusion. The tissue sections were stained using H&E and immunohistochemistry.

RESULTS

For white matter, fractional anisotropy (FA) values significantly decreased in lesion epicenter, caudal segment 1 cm away from epicenter, and caudal segment 2 cm away from epicenter (P = 0.003, P = 0.004, and P = 0.013, respectively) after SCI. Apparent diffusion coefficient (ADC) values were initially decreased and then increased in lesion epicenter and caudal segment 1 cm away from epicenter (P < 0.001 and P = 0.010, respectively). There are no significant changes in FA and ADC values in rostral segments (P > 0.05). For gray matter, ADC values decreased initially and then increased in lesion epicenter (P < 0.001), and overall trend decreased in caudal segment 1 cm away from epicenter (P = 0.039). FA values did not change significantly (P > 0.05). Pathological examination confirmed the dynamic changes of DTI parameters.

CONCLUSION

Diffusion tensor imaging is more sensitive to degeneration of white matter than gray matter, and the white matter degeneration may be not symmetrical which meant the caudal degradation appeared to be more severe than the rostral one.

Spinal Cord Injury Scarring and Inflammation: Therapies Targeting Glial and Inflammatory Responses

Deficits in neuronal function are a hallmark of spinal cord injury (SCI) and therapeutic efforts are often focused on central nervous system (CNS) axon regeneration. However, secondary injury responses by astrocytes, microglia, pericytes, endothelial cells, Schwann cells, fibroblasts, meningeal cells, and other glia not only potentiate SCI damage but also facilitate endogenous repair. Due to their profound impact on the progression of SCI, glial cells and modification of the glial scar are focuses of SCI therapeutic research. Within and around the glial scar, cells deposit extracellular matrix (ECM) proteins that affect axon growth such as chondroitin sulfate proteoglycans (CSPGs), laminin, collagen, and fibronectin. This dense deposition of material, i.e., the fibrotic scar, is another barrier to endogenous repair and is a target of SCI therapies. Infiltrating neutrophils and monocytes are recruited to the injury site through glial chemokine and cytokine release and subsequent upregulation of chemotactic cellular adhesion molecules and selectins on endothelial cells. These peripheral immune cells, along with endogenous microglia, drive a robust inflammatory response to injury with heterogeneous reparative and pathological properties and are targeted for therapeutic modification. Here, we review the role of glial and inflammatory cells after SCI and the therapeutic strategies that aim to replace, dampen, or alter their activity to modulate SCI scarring and inflammation and improve injury outcomes.

Neutrophil infiltration to the brain is platelet-dependent, and is reversed by blockade of platelet GPIbα

Neutrophils are key components of the innate immune response, providing host defence against infection and being recruited to non-microbial injury sites. Platelets act as a trigger for neutrophil extravasation to inflammatory sites but mechanisms and tissue-specific aspects of these interactions are currently unclear. Here, we use bacterial endotoxin in mice to trigger an innate inflammatory response in different tissues and measure neutrophil invasion with or without platelet reduction. We show that platelets are essential for neutrophil infiltration to the brain, peritoneum and skin. Neutrophil numbers do not rise above basal levels in the peritoneum and skin and are decreased (~60%) in the brain when platelet numbers are reduced. In contrast neutrophil infiltration in the lung is unaffected by platelet reduction, up-regulation of CXCL-1 (2·4-fold) and CCL5 (1·4-fold) acting as a compensatory mechanism in platelet-reduced mice during lung inflammation. In brain inflammation targeting platelet receptor GPIbα results in a significant decrease (44%) in platelet-mediated neutrophil invasion, while maintaining platelet numbers in the circulation. These results suggest that therapeutic blockade of platelet GPIbα could limit the harmful effects of excessive inflammation while minimizing haemorrhagic complications of platelet reduction in the brain. The data also demonstrate the ability to target damaging brain inflammation in stroke and related disorders without compromising lung immunity and hence risk of pneumonia, a major complication post stroke. In summary, our data reveal an important role for platelets in neutrophil infiltration to various tissues, including the brain, and so implicate platelets as a key, targetable component of cerebrovascular inflammatory disease or injury.

Anti-inflammatory effect of Mongolian drug Naru-3 on traumatic spinal cord injury and its mechanism of action

Objective This study was performed to confirm the anti-inflammatory effect of the Mongolian drug Naru-3 on traumatic spinal cord injury (TSCI) and its possible mechanism of action. Methods We prepared a TSCI model using Sprague-Dawley rats. The rats were divided into a Naru-3 group and a methylprednisolone group. Real-time polymerase chain reaction and western blotting were performed to measure the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. Enzyme-linked immunosorbent assay kits were employed to detect serum inflammatory cytokine levels. The localization and expression of monocyte chemotactic protein-1 (MCP-1) in spinal cord tissue was determined by immunohistochemical analysis. Flow cytometry was performed to analyze the ratio of M1- and M2-phenotype macrophages. The locomotor function recovery was evaluated by the Basso, Beattie, and Bresnahan score. Results Naru-3 significantly inhibited the inflammatory response and reduced the expression of TNF-α, IL-6, and IL-1β in both spinal cord and blood in a time- and concentration-dependent manner. Immunohistochemical analysis indicated that Naru-3 significantly reduced MCP-1 expression in spinal cord and promoted M2-phenotype macrophage differentiation. Conclusions Naru-3 is an effective treatment for impact-induced TSCI in rats. Naru-3 treatment affects inflammatory cytokine levels and macrophage differentiation, which play a role in TSCI remission.

A Single Dose of Atorvastatin Applied Acutely after Spinal Cord Injury Suppresses Inflammation, Apoptosis, and Promotes Axon Outgrowth, Which Might Be Essential for Favorable Functional Outcome

The aim of our study was to limit the inflammatory response after a spinal cord injury (SCI) using Atorvastatin (ATR), a potent inhibitor of cholesterol biosynthesis. Adult Wistar rats were divided into five experimental groups: one control group, two Th9 compression (40 g/15 min) groups, and two Th9 compression + ATR (5 mg/kg, i.p.) groups. The animals survived one day and six weeks. ATR applied in a single dose immediately post-SCI strongly reduced IL-1β release at 4 and 24 h and considerably reduced the activation of resident cells at one day post-injury. Acute ATR treatment effectively prevented the excessive infiltration of destructive M1 macrophages cranially, at the lesion site, and caudally (by 66%, 62%, and 52%, respectively) one day post-injury, whereas the infiltration of beneficial M2 macrophages was less affected (by 27%, 41%, and 16%). In addition, at the same time point, ATR visibly decreased caspase-3 cleavage in neurons, astrocytes, and oligodendrocytes. Six weeks post-SCI, ATR increased the expression of neurofilaments in the dorsolateral columns and Gap43-positive fibers in the lateral columns around the epicenter, and from day 30 to 42, significantly improved the motor activity of the hindlimbs. We suggest that early modulation of the inflammatory response via effects on the M1/M2 macrophages and the inhibition of caspase-3 expression could be crucial for the functional outcome.

Biochemical events related to glial response in spinal cord injury

Introducción. La lesión de la médula espinal (LME) es un evento devastador con implicaciones físicas, psicológicas y socioeconómicas. En el tejido cercano a la lesión se instauran cambios morfofisiológicos que determinan la recuperación funcional del segmento medular y de los órganos efectores dependientes de los tractos axonales lesionados.Objetivo. Describir los eventos bioquímicos secuenciales más relevantes de la respuesta de las células gliales posterior a la LME.Materiales y métodos. Se realizó una búsqueda de publicaciones científicas de los últimos 18 años en las bases de datos PubMed y ScienceDirect, bajo los términos en inglés spinal cord injury (SCI), SCI pathophysiology, SCI inflammation, microglia in SCI, glial scar y chondroitin sulfate proteoglycans (CSPG).Resultados. Los procesos fisiopatológicos que se producen después de la LME determinan la recuperación neurológica de los pacientes. La activación de las células gliales juega un papel importante, ya que promueve la producción de moléculas bioactivas y la formación de barreras físicas que inhiben la regeneración neural.Conclusión. El conocimiento de los cambios neurobiológicos ocurridos tras la LME permite una mayor comprensión de la fisiopatología y favorece la búsqueda de nuevas alternativas terapéuticas que limiten la progresión de la lesión primaria y que minimicen el daño secundario responsable de la disfunción neurológica.

Downregulation of Matrix Metalloproteinases 2 and 9 is Involved in the Protective Effect of Trehalose on Spinal Cord Injury

Upregulation of matrix metalloproteinases (MMPs), in particular MMP-2 and MMP-9 contributes to secondary pathogenesis of spinal cord injury (SCI) via promoting inflammation. Recently, we have reported that trehalose suppresses inflammatory responses following SCI. Therefore, we investigated the effect of trehalose on MMP-2 and MMP-9 expression in SCI. A weight-drop contusion SCI was induced in male rats. Then, the animals received trehalose at three doses of 10 (T10), 100 (T100) and 1000 (T1000) mM intrathecally. MMP-2 and MMP-9 transcripts were then measured in damaged spinal cord at 1, 3 and 7 days after trauma, and compared with vehicle and sham groups. Additionally, behavioral analysis was conducted for 1 week using Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Our data showed an early upregulation of MMP-9 at 1 day post-SCI. However, MMP-2 expression was increased at 3 days after trauma. Treatment with 10 mM trehalose significantly reduced MMP-2 expression in 3 and 7 days (P< 0.01) and MMP-9 expression in 1, 3, and 7 days (P< 0.05) post-damage compared with vehicle. Nonetheless, downregulation of both MMPs was not observed in T100 and T1000 groups. In addition, T10 group showed more rapid recovery of hind limb strength compared with T100 and T1000 groups. We propose that the neuroprotective effect of low dose trehalose is mediated by attenuation of MMP-2 and MMP-9 expression.

Early surgical decompression within 8 hours for traumatic spinal cord injury: Is it beneficial? A meta-analysis

Introduction

The aim of this study is to evaluate whether early (<8 h) surgical decompression is better in improving neurologic outcomes than late (≥8 h) surgical decompression for traumatic spinal cord injury (tSCI).

Methods

The various electronic databases were used to detect relevant articles published up until May 2016 that compared the outcomes of early versus late surgery for tSCI. Data searching, extraction, analysis, and quality assessment were performed according to Cochrane Collaboration guidelines. The results are presented as relative ratio (RR) for binary outcomes and mean difference (MD) for continuous outcomes with 95% confidence intervals (CIs).

Results

Seven studies were finally included in this meta-analysis. There were significant differences between the 2 groups in neurologic improvement (MD = 0.54, 95% CI = −18.52 to −7.02, P < 0.0001) and length of hospital stay (MD = −12.77, 95% CI = 0.34–0.74, P < 0.00001). However, no significant differences were found between the 2 groups in perioperative complications (OR = 0.95, 95% CI = 0.35–2.61, P = 0.92).

Conclusions

Early surgical decompression within 8 h after tSCI was beneficial in terms of neurologic improvement compared with late surgery. Early surgical decompression (within 8 h) is recommended for patients with tSCI.

Level of evidence

Level III, therapeutic study.

Mithramycin A Improves Functional Recovery by Inhibiting BSCB Disruption and Hemorrhage after Spinal Cord Injury

After spinal cord injury (SCI), blood-spinal cord barrier (BSCB) disruption and progressive hemorrhage lead to secondary injury, subsequent apoptosis and/or necrosis of neurons and glia, causing permanent neurological deficits. Growing evidence indicates that mithramycin A (MA), an anti-cancer drug, has neuroprotective effects in ischemic brain injury and Huntington's disease (HD). However, the precise mechanism underlying its protective effects is largely unknown. Here, we examined the effect of MA on BSCB breakdown and hemorrhage as well as subsequent inflammation after SCI. After moderate spinal cord contusion injury at T9, MA (150 μg/kg) was immediately injected intraperitoneally (i.p.) and further injected once a day for 5 days. Our data show that MA attenuated BSCB disruption and hemorrhage, and inhibited the infiltration of neutrophils and macrophages after SCI. Consistent with these findings, the expression of inflammatory mediators was significantly alleviated by MA. MA also inhibited the expression and activation of matrix metalloprotease-9 (MMP-9) after injury, which is known to disrupt BSCB and the degradation of tight junction (TJ) proteins. In addition, the expression of sulfonylurea receptor 1 (SUR1) and transient receptor potential melastatin 4 (TRPM4), which are known to mediate hemorrhage at an early stage after SCI, was significantly blocked by MA treatment. Finally, MA inhibited apoptotic cell death and improved functional recovery after injury. Thus, our results demonstrated that MA improves functional recovery by attenuating BSCB disruption and hemorrhage through the downregulation of SUR1/TRPM4 and MMP-9 after SCI.

Extremely low frequency magnetic field protects injured spinal cord from the microglia- and iron-induced tissue damage

Spinal cord injury (SCI) is insult to the spinal cord, which results in loss of sensory and motor function below the level of injury. SCI results in both immediate mechanical damage and secondary tissue degeneration. Following traumatic insult, activated microglia release proinflammatory cytokines and excess iron due to hemorrhage, initiating oxidative stress that contributes to secondary degeneration. Literature suggests that benefits are visible with the reduction in concentration of iron and activated microglia in SCI. Magnetic field attenuates oxidative stress and promotes axonal regeneration in vitro and in vivo. The present study demonstrates the potential of extremely low frequency magnetic field to attenuate microglia- and iron-induced secondary injury in SCI rats. Complete transection of the spinal cord (T13 level) was performed in male Wistar rats and subsequently exposed to magnetic field (50 Hz,17.96 µT) for 2 h daily for 8 weeks. At the end of the study period, spinal cords were dissected to quantify microglia, macrophage, iron content and study the architecture of lesion site. A significant improvement in locomotion was observed in rats of the SCI + MF group as compared to those in the SCI group. Histology, immunohistochemistry and flow cytometry revealed significant reduction in lesion volume, microglia, macrophage, collagen tissue and iron content, whereas, a significantly higher vascular endothelial growth factor expression around the epicenter of the lesion in SCI + MF group as compared to SCI group. These novel findings suggest that exposure to ELF-MF reduces lesion volume, inflammation and iron content in addition to facilitation of angiogenesis following SCI.

Molecular Ultrasound Imaging for the Detection of Neural Inflammation: A Longitudinal Dosing Pilot Study

Molecular ultrasound imaging provides the ability to detect physiologic processes noninvasively by targeting a variety of biomarkers in vivo. The current study was performed by exploiting an inflammatory biomarker, P-selectin, known to be present following spinal cord injury. Using a murine model (n = 6), molecular ultrasound imaging was performed using contrast microbubbles modified to target and adhere to P-selectin, prior to spinal cord injury (0D), acute stage postinjury (7D), and chronic stage (42D). Additionally, two imaging sessions were performed on each subject at specific time points, using doses of 30 μL and 100 μL. Upon analysis, targeted contrast analysis parameters were appreciably increased during the 7D scan compared with the 42D scan, without statistical significance. When examining the dose levels, the 30-μL dose demonstrated greater values than the 100-μL dose but lacked statistical significance. These findings provide additional preclinical evidence for the use of molecular ultrasound imaging for the possible detection of inflammation.

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.

PPAR-α Modulates the Anti-Inflammatory Effect of Melatonin in the Secondary Events of Spinal Cord Injury

Melatonin is the principal secretory product of the pineal gland, and its role as an immunomodulator is well established. Recent evidence shows that melatonin is a scavenger of oxyradicals and peroxynitrite and reduces the development of inflammation and tissue injury events associated with spinal cord trauma. Previous results suggest that peroxisome proliferator-activated receptor α (PPAR-α), a nuclear receptor protein that functions as a transcription factor activated by fatty acids, plays a role in control of secondary inflammatory process associated with spinal cord injury (SCI).With the aim to characterize the role of PPAR-α in melatonin-mediated anti-inflammatory activity, we tested the efficacy of melatonin (30 mg/kg) in an experimental model of spinal cord trauma, induced in mice, by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy, and comparing mice lacking PPAR-α (PPAR-α KO) with wild-type (WT) mice.The results obtained indicate that melatonin-mediated anti-inflammatory activity is weakened in PPAR-α KO mice, as compared to WT controls. In particular, melatonin was less effective in PPAR-α KO, compared to WT mice, as evaluated by inhibition of the degree of spinal cord inflammation and tissue injury, neutrophil infiltration, pro-inflammatory cytokine expression, nuclear factor κB (NF-κB) activation, and inducible nitric oxide synthase (iNOS) expression. This study indicates that PPAR-α can contribute to the anti-inflammatory activity of melatonin in SCI.

Molecular Ultrasound Imaging of the Spinal Cord for the Detection of Acute Inflammation

Molecular ultrasound imaging provides the ability to detect physiologic processes non-invasively by targeting a wide variety of biological markers in vivo. The current study investigates the novel application of molecular ultrasound imaging for the detection of neural inflammation. Using a murine model with acutely injured spinal cords (n=31), subjects were divided into four groups, each being administered ultrasound contrast microbubbles bearing antibodies against various known inflammatory molecules (P-selectin, vascular cell adhesion protein 1 [VCAM-1], intercellular adhesion molecule 1 [ICAM-1], and isotype control) during molecular ultrasound imaging. Upon administration of the targeted contrast agent, ultrasound imaging of the injured spinal cord was performed at 40MHz for seven minutes, followed by a bursting pulse. We observed significantly enhanced signals from contrast targeted to P-selectin and VCAM-1, using a variety of outcome measures. These findings provide preclinical evidence that molecular ultrasound imaging could be a useful tool in the detection of neural inflammation.

HDAC3 inhibition ameliorates spinal cord injury by immunomodulation

Following spinal cord injury (SCI), the innate immune response of microglia and infiltrating macrophages clears up cellular debris and promotes tissue repair, but it also inflicts secondary injury from inflammatory responses. Immunomodulation aimed at maximizing the beneficial effects while minimizing the detrimental roles of the innate immunity may aid functional recovery after SCI. However, intracellular drivers of global reprogramming of the inflammatory gene networks in the innate immune cells are poorly understood. Here we show that SCI resulted in an upregulation of histone deacetylase 3 (HDAC3) in the innate immune cells at the injury site. Remarkably, blocking HDAC3 with a selective small molecule inhibitor shifted microglia/macrophage responses towards inflammatory suppression, resulting in neuroprotective phenotypes and improved functional recovery in SCI model. Mechanistically, HDAC3 activity is largely responsible for histone deacetylation and inflammatory responses of primary microglia to classic inflammatory stimuli. Our results reveal a novel function of HDAC3 inhibitor in promoting functional recovery after SCI by dampening inflammatory cytokines, thus pointing towards a new direction of immunomodulation for SCI repair.

Activation of the Nrf2/ARE signaling pathway by probucol contributes to inhibiting inflammation and neuronal apoptosis after spinal cord injury

The nuclear erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway plays an essential role in the cellular antioxidant and anti-inflammatory responses. Spinal cord injury (SCI) results in a massive release of inflammatory factors and free radicals, which seriously compromise nerve recovery and axon regeneration. In this study, we examined the efficacy of probucol on anti-inflammatory responses and functional recovery after SCI by activating the Nrf2/ARE signaling pathway. We also investigated the mechanism by which inflammation is inhibited in this process. We found that treatment of injured rats with probucol significantly increased levels of Nrf2, heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase-1 (NQO1), while levels of inflammatory cytokines, interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were decreased. This was associated with a reduction in neural cell apoptosis and promotion of nerve function recovery. These results demonstrate that the neuroprotective effects of probucol after SCI are mediated by activation of the Nrf2/ARE signaling pathway. These findings indicate that the anti-inflammatory effects of probucol represent a viable treatment for improving functional recovery following SCI.

Anti-inflammatory effects of ursodeoxycholic acid by lipopolysaccharide-stimulated inflammatory responses in RAW 264.7 macrophages

PURPOSE

The aim of this study was to investigate the anti-inflammatory effects of Ursodeoxycholic acid (UDCA) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

METHODS

We induced an inflammatory process in RAW 264.7 macrophages using LPS. The anti-inflammatory effects of UDCA on LPS-stimulated RAW 264.7 macrophages were analyzed using nitric oxide (NO). Pro-inflammatory and anti-inflammatory cytokines were analyzed by quantitative real time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). The phosphorylations of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 in mitogen-activated protein kinase (MAPK) signaling pathways and nuclear factor kappa-light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) signaling pathways were evaluated by western blot assays.

RESULTS

UDCA decreased the LPS-stimulated release of the inflammatory mediator NO. UDCA also decreased the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin 1-α (IL-1α), interleukin 1-β (IL-1β), and interleukin 6 (IL-6) in mRNA and protein levels. In addition, UDCA increased an anti-inflammatory cytokine interleukin 10 (IL-10) in the LPS-stimulated RAW 264.7 macrophages. UDCA inhibited the expression of inflammatory transcription factor nuclear factor kappa B (NF-κB) in LPS-stimulated RAW 264.7 macrophages. Furthermore, UDCA suppressed the phosphorylation of ERK, JNK, and p38 signals related to inflammatory pathways. In addition, the phosphorylation of IκBα, the inhibitor of NF-κB, also inhibited by UDCA.

CONCLUSION

UDCA inhibits the pro-inflammatory responses by LPS in RAW 264.7 macrophages. UDCA also suppresses the phosphorylation by LPS on ERK, JNK, and p38 in MAPKs and NF-κB pathway. These results suggest that UDCA can serve as a useful anti-inflammatory drug.

Cordycepin-enriched WIB-801C from Cordyceps militaris improves functional recovery by attenuating blood-spinal cord barrier disruption after spinal cord injury

ETHNOPHARMACOLOGICAL RELEVANCE

Cordyceps militaris is an ingredient of traditional Chinese medicine and have been widely used for inflammatory diseases and cancer. Cordycepin is one of the major bioactive components of Cordyceps militaris, and has been known to have anti-inflammatory and anti-oxidant effects.

AIM OF THIS STUDY

In the present study, we examined whether WIB-801C, a standardized and cordycepin-enriched extract of caterpillar fungus (Cordyceps militaris), would attenuate blood-spinal cord barrier (BSCB) disruption by inhibiting matrix metalloprotease (MMP)-9 activity, leading to improvement of functional outcomes after spinal cord injury (SCI).

MATERIALS AND METHODS

Male Sprague-Dawley rats were subjected to contusive SCI using a New York University (NYU) impactor, and WIB-801C (50mg/kg) was administered at 2h and 8h after injury orally and further treated once a day for indicated time points. BSCB disruption, MMP-9 activity, blood infiltration, inflammation, neuronal apoptosis, axonal loss, demyelination, and neurological deficit were evaluated.

RESULTS

We found that WIB-801C significantly attenuated BSCB disruption by inhibiting MMP-9 expression and activation after injury. The infiltration of neutrophils at 1 d and macrophage at 5 d after SCI was also ameliorated by WIB-801C as compared with vehicle control. In addition, the expression of inflammatory cytokines and mediators such as Tnf-α, IL-1β, IL-6, Cox-2, and inos as well as chemokines such as Gro-α and Mip-2α was significantly inhibited by WIB-801C. Furthermore, WIB-801C inhibits p38MAPK activation and proNGF production in microglia after injury. These events eventually led to the inhibition of apoptotic cell death of neurons and oligodendrocytes, improved functional recovery and attenuated demyelination and axon loss after SCI.

CONCLUSION

Our results suggest that WIB-801C can be used as a therapeutic agent after SCI by attenuating BSCB disruption followed inflammation.

Creation of an intramedullary cavity by hemorrhagic necrosis removal 24 h after spinal cord contusion in rats for eventual intralesional implantation of restorative materials

Intramedullary hemorrhagic necrosis occurs early after spinal cord injury at the site of injury and adjacent segments. It is considered harmful because of its potential to aggravate secondary injury, and to interfere with axonal regeneration; it might also lead to an unfavorable environment for intralesional implants. Removal of hemorrhagic necrosis has been attempted before with variable results. The invasive nature of these procedures carries the risk of exacerbating damage to the injured cord. The overall objective for this study was to test several strategies for non-damaging removal of hemorrhagic necrosis and characterize the resulting cavity looking for a space for future intralesional therapeutic implants in rats with acute cord injury. Rats were subjected to graded cord contusion, and hemorrhagic necrosis was removed after 24h. Three grades of myelotomy (extensive, medium sized, and small) were tested. Using the small surgical approach to debridement, early and late effects of the intervention were determined by histology and by analytical and behavioral analysis. Appearance and capacity of the resulting cavity were characterized. Satisfactory removal of hemorrhagic necrosis was achieved with all three surgical approaches to debridement. However, bleeding in spared cord tissue was excessive after medium sized and extensive myelotomies but similar to control injured rats after small cord surgery. Small surgical approach to debridement produced no swelling nor acute inflammation changes, nor did it affect long-term spontaneous locomotor recovery, but resulted in modest improvement of myelination in rats subjected to both moderate and severe injuries. Cavity created after intervention was filled with 10 to 15 μL of hydrogel. In conclusion, by small surgical approach to debridement, removal of hemorrhagic necrosis was achieved after acute cord contusion thereby creating intramedullary spaces without further damaging the injured spinal cord. Resulting cavities appear suitable for future intralesional placement of pro-reparative cells or other regenerative biomaterials in a clinically relevant model of spinal cord injury.

Low-level laser facilitates alternatively activated macrophage/microglia polarization and promotes functional recovery after crush spinal cord injury in rats

Macrophages and resident microglia play an import role in the secondary neuroinflammation response following spinal cord injury. Reprogramming of macrophage/microglia polarization is an import strategy for spinal cord injury restoration. Low-level laser therapy (LLLT) is a noninvasive treatment that has been widely used in neurotrauma and neurodegenerative diseases. However, the influence of low-level laser on polarization of macrophage/microglia following spinal cord injury remains unknown. The present study applied low-level laser therapy on a crush spinal cord injury rat model. Using immunofluorescence, flow cytometry, RT-qPCR, and western blot assays, we found that low-level laser therapy altered the polarization state to a M2 tendency. A greater number of neurons survived in the pare injury site, which was accompanied by higher BBB scores in the LLLT group. Furthermore, low-level laser therapy elevated expression of interleukin 4 (IL-4) and interleukin 13 (IL-13). Results from this study show that low-level laser therapy has the potential for reducing inflammation, regulating macrophage/microglia polarization, and promoting neuronal survival. These beneficial effects demonstrate that low-level laser therapy may be an effective candidate for clinical treatment of spinal cord injury.

IL-17 induces reactive astrocytes and up-regulation of vascular endothelial growth factor (VEGF) through JAK/STAT signaling

Spinal cord injury is a grave neurological disability resulting in neuron degeneration and permanent paralysis. The inflammation triggered by the injury would promote the spinal cord lesion in turn. Activated astrocytes during inflammatory response could promote glial scar formation and contribute to the progression of the spinal cord injury. Interleukin 17 (IL-17) was upregulated in inflammatory responses to contusion or compression of the spinal cord. in this study, IL-17 could induce reactive astrocytes which was indicated by a well-known hallmark glial fibrillary acidic protein (GFAP) in vitro and in vivo. Moreover, we demonstrated that the upregulation of VEGF was induced by IL-17 human astrocytoma cells. In our further investigation, IL-17 induced the expression of VEGF in spinal cord injury by activating JAK/STAT signaling pathway both in vitro and in vivo. In addition, we also found that IL-17 significantly changed tissue preservation and residual urine volumes and blood-spinal cord-barrier integrity in vivo. This newly found IL-17-JAK/STAT-VEGF axis improves our understanding of the molecular mechanism of spinal cord injury during inflammatory response and provides another potential target of spinal cord injury.

Role of hypoxia‑inducible factor‑1α in autophagic cell death in microglial cells induced by hypoxia

Microglial cells are phagocytic cells of the central nervous system (CNS) and have been proposed to be a primary component of the innate immune response and maintain efficient CNS homeostasis. Microglial cells are activated during various phases of tissue repair and participate in various pathological conditions in the CNS. Following spinal cord injury (SCI), anoxemia is a key problem that results in tissue destruction. Hypoxia-inducible factor 1-α (HIF-1α) may protect hypoxic cells from apoptosis or necrosis under ischemic and anoxic conditions. However, numerous studies have revealed that hypoxia upregulates HIF-1α expression leading to the death of microglial cells. The present study investigated the alterations in HIF-1α expression levels and the mechanism of autophagic cell death mediated by HIF-1α in microglial cells induced by hypoxia. Hypoxia was demonstrated to induce HIF-1α expression and autophagic cell death in microglial cells. Enhanced autophagy reduced cell death during the initial stages by restraining the functions of autophagy-associated genes (microtubule-associated protein 1A/1B-light chain 3 phosphatidylethanolamine conjugate and Beclin-1) and modulating the expression of inflammatory cytokines (tumor necrosis factor-α and interleukin-1β). Target value was determined by Cell Counting Kit 8 and cell death by flow cytometry. Transmission electron microscopy, immunohistochemical staining, reverse transcription-quantitative polymerase chain reaction, western blotting, and ELISA were used for further analysis. However, increased expression of HIF-1α induced cell death and autophagic cell death in microglial cells. Furthermore, the effects of the HIF-1α inhibitor 2-methoxyestradiol and HIF-1α small interfering RNA on the death and autophagy of microglial cells in vitro were investigated. These investigations revealed the suppression of autophagy, the decrease of cell viability and the increase of inflammatory cytokines results from HIF-1α inhibition or HIF-1α silencing. In conclusion, the results indicated that appropriate expression of HIF-1α can ameliorate autophagic cell death of microglial cells associated with hypoxia, and may provide a novel therapeutic approach for SCI associated with microglial cell activation.

Differences in the Cellular Response to Acute Spinal Cord Injury between Developing and Mature Rats Highlights the Potential Significance of the Inflammatory Response

There exists a trend for a better functional recovery from spinal cord injury (SCI) in younger patients compared to adults, which is also reported for animal studies; however, the reasons for this are yet to be elucidated. The post injury tissue microenvironment is a complex milieu of cells and signals that interact on multiple levels. Inflammation has been shown to play a significant role in this post injury microenvironment. Endogenous neural progenitor cells (NPC), in the ependymal layer of the central canal, have also been shown to respond and migrate to the lesion site. This study used a mild contusion injury model to compare adult (9 week), juvenile (5 week) and infant (P7) Sprague-Dawley rats at 24 h, 1, 2, and 6 weeks post-injury (n = 108). The innate cells of the inflammatory response were examined using counts of ED1/IBA1 labeled cells. This found a decreased inflammatory response in the infants, compared to the adult and juvenile animals, demonstrated by a decreased neutrophil infiltration and macrophage and microglial activation at all 4 time points. Two other prominent cellular contributors to the post-injury microenvironment, the reactive astrocytes, which eventually form the glial scar, and the NPC were quantitated using GFAP and Nestin immunohistochemistry. After SCI in all 3 ages there was an obvious increase in Nestin staining in the ependymal layer, with long basal processes extending into the parenchyma. This was consistent between age groups early post injury then deviated at 2 weeks. The GFAP results also showed stark differences between the mature and infant animals. These results point to significant differences in the inflammatory response between infants and adults that may contribute to the better recovery indicated by other researchers, as well as differences in the overall injury progression and cellular responses. This may have important consequences if we are able to mirror and manipulate this response in patients of all ages; however much greater exploration in this area is required.

Ethanol extract of Cotinus coggygria leaves accelerates wound healing process in diabetic rats

CONTEXT

Cotinus coggygria Scop. (Anacardiaceae) leaves that were used as wound healing in traditional Balkan and Anatolian folk medicine, could be potentially effective in treating diabetic wounds.

OBJECTIVE

This study investigates biochemical and histological effects of ethanol extract of C. coggygria (CCE) on excision wound model in diabetic rats.

MATERIALS AND METHODS

This study was conducted on diabetic Wistar albino rats, which were injected by a single dose (50 mg/kg i.p.) streptozotocin. Afterward an excision wound model was created in all animals; diabetic control rats were applied topically simple ointment and diabetic treatment rats were applied topically 5% (w/w) ointment with CC, once a day during the experimental period. Malondialdehyde, glutathione and hydroxyproline levels in wound tissues were investigated at the end of 3rd, 7th, and 14th days. Histopathological examination was also performed.

RESULTS

Hydroxyproline content was significantly increased in the CCE treated group versus control after the 3rd and 7th days (15.33 versus 11.83; 19.67 versus 15.67 mg/g, p < 0.05; respectively). A statistically significant elevation in glutathione at the end of 3rd, 7th, and 14th days (5.13 versus 1.58, p < 0.05; 4.72 versus 1.88, p < 0.05; 3.83 versus 1.88 μmol/g, p < 0.05, respectively) and a statistically significant decrease in malondialdehyde level at the end of 7th day (4.49 versus 1.48 nmol/g, p < 0.05) were determined in the treated group versus control group. These results were also supported by histological analyses.

DISCUSSION AND CONCLUSION

These findings indicate that CCE accelerated the cutaneous wound healing process in diabetic wounds, in confirmation of its traditional use.

NADPH oxidase isoform expression is temporally regulated and may contribute to microglial/macrophage polarization after spinal cord injury

Spinal cord injury (SCI) results in both acute and chronic inflammation, as a result of activation of microglia, invasion of macrophages and activation of the NADPH oxidase (NOX) enzyme. The NOX enzyme is a primary source of reactive oxygen species (ROS) and is expressed by microglia and macrophages after SCI. These cells can assume either a pro- (M1) or anti-inflammatory (M2) polarization phenotype and contribute to tissue response to SCI. However, the contribution of NOX expression and ROS production to this polarization and vice versa is currently undefined. We therefore investigated the impact of SCI on NOX expression and microglial/macrophage polarization over time in a mouse model of contusion injury. Adult C57Bl/6 mice were exposed to a moderate T9 contusion SCI and tissue was assessed at acute, sub-acute and chronic time points for NOX isoform expression and co-expression with M1 and M2 microglia/macrophage polarization markers. Two NOX isoforms were increased after injury and were associated with both M1 and M2 markers, with an M1 preference for NOX2 acutely and NOX4 chronically. M2 cells were primarily found at acute time points only; the peak of NOX2 expression was associated with the decline in M2 polarization. In vitro, NOX2 inhibition shifted microglial polarization toward the M2 phenotype. These results now show that microglial/macrophage expression of NOX isoforms is independent of polarization state, but that NOX activity can influence subsequent polarization. These data can contribute to the therapeutic targeting of NOX as a therapy for SCI.

Aescin reduces oxidative stress and provides neuroprotection in experimental traumatic spinal cord injury

Aescin has many physiological functions that are highly relevant to spinal cord injury (SCI), including anti-inflammation, anti-oxidation, anti-oedema, and enhancing vascular tone. The present study investigated the putative therapeutic value of aescin in SCI, with a focus on its neuroprotective, anti-inflammatory, and anti-oxidative properties. Sodium aescinate (1.0mg/kg body weight) or equivalent volume of saline was administered 30min after injury by intravenous injection, with an additional dose daily for seven consecutive days after moderate SCI in rats. After contusion injury of the 8th thoracic (T8) spinal cord, aescin-treated rats developed less severe hind limb weakness than saline controls, as assayed by the Basso-Beattie-Bresnahan scale, the beam walking test, and a footprint analysis. The improved locomotor outcomes in aescin-treated rats corresponded to markedly decreased immune response, oxidative stress, neuronal loss, axon demyelination, spinal cord swelling, and cell apoptosis, measured around T8 after impact. Our data suggest aescin treatment as a novel, early, neuroprotective approach in SCI. Given the known safety of aescin in clinical applications, the results of this study suggest that it is a good candidate for SCI treatment in humans.

Exploring Targeted Contrast-Enhanced Ultrasound to Detect Neural Inflammation

Targeted contrast-enhanced ultrasound (TCEUS) is an innovative method of molecular imaging used for detection of inflammatory biomarkers in vivo. By targeting ultrasound contrast to cell adhesion molecules (CAMs), which are known inflammatory markers within neural tissue, a more direct evaluation of neural inflammation can be made. Due to the novel nature of TCEUS, standardized methods of image analysis do not yet exist. Time intensity curve (TIC) shape analysis is currently used in magnetic resonance contrast imaging to determine temporal behavior of perfusion. Therefore, the presented research attempts to determine TIC shape analysis utility in TCEUS imaging by applying it to TCEUS scans targeted to CAMs present in neural inflammation. This was done in an animal model that underwent a traumatic spinal cord injury to induce inflammation ( n = 31). Subjects were divided into four groups, each receiving a TCEUS targeted to a different CAM seven days after surgery (P-selectin, intracellular adhesion molecule 1 [ICAM-1], vascular cell adhesion molecule 1 [VCAM-1], and control). TICs were generated using average pixel intensity within the injured region of the spinal cord. TIC shape analysis found similar curves were produced while targeting P-selectin and VCAM-1, both demonstrating rapid and sustained enhancement. Control injections demonstrated no enhancement. ICAM-1 injections demonstrated limited enhancement and a shape similar to the control.