GM-CSF inhibits glial scar formation and shows long-term protective effect after spinal cord injury

Transplantation of dorsal root ganglia overexpressing the NaChBac sodium channel improves locomotion after complete SCI

Spinal cord injury (SCI) is a debilitating condition currently lacking treatment. Severe SCI causes the loss of most supraspinal inputs and neuronal activity caudal to the injury, which, coupled with the limited endogenous capacity for spontaneous regeneration, can lead to complete functional loss even in anatomically incomplete lesions. We hypothesized that transplantation of mature dorsal root ganglia (DRGs) genetically modified to express the NaChBac sodium channel could serve as a therapeutic option for functionally complete SCI. We found that NaChBac expression increased the intrinsic excitability of DRG neurons and promoted cell survival and neurotrophic factor secretion in vitro. Transplantation of NaChBac-expressing dissociated DRGs improved voluntary locomotion 7 weeks after injury compared to control groups. Animals transplanted with NaChBac-expressing DRGs also possessed higher tubulin-positive neuronal fiber and myelin preservation, although serotonergic descending fibers remained unaffected. We observed early preservation of the corticospinal tract 14 days after injury and transplantation, which was lost 7 weeks after injury. Nevertheless, transplantation of NaChBac-expressing DRGs increased the neuronal excitatory input by an increased number of VGLUT2 contacts immediately caudal to the injury. Our work suggests that the transplantation of NaChBac-expressing dissociated DRGs can rescue significant motor function, retaining an excitatory neuronal relay activity immediately caudal to injury.

The secondary injury cascade after spinal cord injury: an analysis of local cytokine/chemokine regulation

JOURNAL/nrgr/04.03/01300535-202406000-00035/inline-graphic1/v/2023-10-30T152229Z/r/image-tiff

After spinal cord injury, there is an extensive infiltration of immune cells, which exacerbates the injury and leads to further neural degeneration. Therefore, a major aim of current research involves targeting the immune response as a treatment for spinal cord injury. Although much research has been performed analyzing the complex inflammatory process following spinal cord injury, there remain major discrepancies within previous literature regarding the timeline of local cytokine regulation. The objectives of this study were to establish an overview of the timeline of cytokine regulation for 2 weeks after spinal cord injury, identify sexual dimorphisms in terms of cytokine levels, and determine local cytokines that significantly change based on the severity of spinal cord injury. Rats were inflicted with either a mild contusion, moderate contusion, severe contusion, or complete transection, 7 mm of spinal cord centered on the injury was harvested at varying times post-injury, and tissue homogenates were analyzed with a Cytokine/Chemokine 27-Plex assay. Results demonstrated pro-inflammatory cytokines including tumor necrosis factor α, interleukin-1β, and interleukin-6 were all upregulated after spinal cord injury, but returned to uninjured levels within approximately 24 hours post-injury, while chemokines including monocyte chemoattractant protein-1 remained upregulated for days post-injury. In contrast, several anti-inflammatory cytokines and growth factors including interleukin-10 and vascular endothelial growth factor were downregulated by 7 days post-injury. After spinal cord injury, tissue inhibitor of metalloproteinase-1, which specifically affects astrocytes involved in glial scar development, increased more than all other cytokines tested, reaching 26.9-fold higher than uninjured rats. After a mild injury, 11 cytokines demonstrated sexual dimorphisms; however, after a severe contusion only leptin levels were different between female and male rats. In conclusion, pro-inflammatory cytokines initiate the inflammatory process and return to baseline within hours post-injury, chemokines continue to recruit immune cells for days post-injury, while anti-inflammatory cytokines are downregulated by a week post-injury, and sexual dimorphisms observed after mild injury subsided with more severe injuries. Results from this work define critical chemokines that influence immune cell infiltration and important cytokines involved in glial scar development after spinal cord injury, which are essential for researchers developing treatments targeting secondary damage after spinal cord injury.

Conditional deletion of IκBζ in hematopoietic cells promotes functional recovery after spinal cord injury in mice

BACKGROUND

Transcription factor protein IκBζ (encoded by the Nfkbiz gene) regulates nuclear factor-κB (NF-κB) and is involved in the pathophysiology of various inflammatory diseases. However, the role of IκBζ in secondary damage following spinal cord injury (SCI) remains to be determined. Here, we investigated the effect of IκBζ expressed in hematopoietic cells on the progression of secondary damage and functional recovery after SCI.

METHODS

We used conditional IκBζ-knockout mice (Mx1-Cre;Nfkbizfl/f) to examine the role of IκBζ in hematopoietic cells after SCI. Contusion SCI was induced using a force of 60 kdyn. The recovery of locomotor performance was evaluated using the nine-point Basso Mouse Scale (BMS) until 42 days post-injury. Expression patterns of inflammatory cytokines and chemokines were examined by quantitative real-time PCR or proteome array analysis. Bone marrow transplantation (BMT) was performed to eliminate the effect of IκBζ deletion in non-hematopoietic cells.

RESULTS

Mx1-Cre;Nfkbizfl/fl mice had significantly improved locomotor function compared with wild-type (WT) mice. The mRNA expression of Nfkbiz in WT mice peaked at 12 h after SCI and then decreased slowly in both the spinal cord and white blood cells. In situ hybridization showed that Nfkbiz mRNA was localized in cell nuclei, including macrophage-like cells, in the injured spinal cord of WT mice at 1 day after SCI. Compared with WT mice, Mx1-Cre;Nfkbizfl/fl mice had significantly increased mRNA expressions of interleukin (Il)-4 and Il-10 in the injured spinal cord. In addition, Mx1-Cre;Nfkbizfl/fl mice had significantly higher protein levels of granulocyte-macrophage colony-stimulating factor and C-C motif chemokine 11 compared with WT mice. BMT from Mx1-Cre;Nfkbizfl/fl mice into WT mice improved functional recovery after SCI compared with control mice (WT cells into WT mice).

CONCLUSIONS

IκBζ deletion in hematopoietic cells improved functional recovery after SCI, possibly by shifting the inflammatory balance towards anti-inflammatory and pro-regenerative directions.

Models and approaches to comprehend and address glial inflammation following spinal cord injury

Spinal cord injury (SCI) culminates in chronic inflammation and glial scar formation driven by the activation of microglia and astrocytes. Current anti-inflammatory strategies to treat glial activation associated with SCI have several limitations. Existing in vitro and ex vivo models studying molecular mechanisms associated with inflammation focus only on the acute phase. However, the progression of glial cell-derived inflammation over the acute-to-chronic phases has not been assessed. Understanding this progression will help establish a framework for evaluating therapeutic strategies. Additionally, new models could be useful as high-throughput screening (HTS) platforms. This review aims to highlight currently available models and future methods that could facilitate screening of novel therapeutics for SCI.

Granulocyte colony-stimulating factor effects on neurological and motor function in animals with spinal cord injury: a systematic review and meta-analysis

Background

Spinal cord injury (SCI) is a severe neurological injury for which no effective treatment exists. Granulocyte colony-stimulating factor (G-CSF) is used to treat autologous bone marrow transplantation, chemotherapy-induced granulocytopenia, Acquired Immune Deficiency Syndrome (AIDS), etc. Recent research has revealed the potential application of G-CSF on neuroprotective effectiveness. In central nervous system diseases, G-CSF can be used to alleviate neuronal injury.

Objective

To investigate the effects of G-CSF on Basso, Beattie, and Bresnahan (BBB) scale score, inclined plane test, electrophysiologic exam, quantitative analysis of TUNEL-positive cells, and quantitative analysis of glial fibrillary acidic protein (GFAP) immunostaining images in animal models of SCI.

Methods

We searched PubMed, Web of Science, and Embase databases for all articles on G-CSF intervention with animal models of SCI reported before November 2022. A total of 20 studies met the inclusion criteria.

Results

Results revealed that G-CSF intervention could improve the BBB scale score in both groups at 3, 7, 14, 28, and 35 days [at 35  days, weighted mean differences (WMD) = 2.4, 95% CI: 1.92-2.87, p < 0.00001, I² = 69%]; inclined plane test score; electrophysiologic exam; quantitative analysis of TUNEL-positive cell numbers; quantitative analysis of GFAP immunostaining images in animal models of SCI. Subgroup analysis revealed that treatment with normal saline, phosphate-buffered saline, and no treatment resulted in significantly different neurological function effectiveness compared to the G-CSF therapy. SD rats and Wistar rats with SCI resulted in significant neurological function effectiveness. C57BL/6 mice showed no difference in the final effect. The T9-T10 or T10 segment injury model and the T8-T9 or T9 segment injury model resulted in significant neurological function effectiveness. The BBB score data showed no clear funnel plot asymmetry. We found no bias in the analysis result (Egger's test, p = 0.42). In our network meta-analysis, the SUCRA ranking showed that 15 mg/kg-20 mg/kg was an optimal dose for long-term efficacy.

Conclusion

Our meta-analysis suggests that G-CSF therapy may enhance the recovery of motor activity and have a specific neuroprotective effect in SCI animal models.Systematic review registration: PROSPERO, identifier: CRD42023388315.

Treatment with Granulocyte-Macrophage Colony-Stimulating Factor Reduces Viral Titers in the Brains of West Nile Virus-Infected Mice and Improves Survival

West Nile virus (WNV) is the leading cause of epidemic arboviral encephalitis in the United States. As there are currently no proven antiviral therapies or licensed human vaccines, understanding the neuropathogenesis of WNV is critical for rational therapeutic design. In WNV-infected mice, the depletion of microglia leads to enhanced viral replication, increased central nervous system (CNS) tissue injury, and increased mortality, suggesting that microglia play a critical role in protection against WNV neuroinvasive disease. To determine if augmenting microglial activation would provide a potential therapeutic strategy, we administered granulocyte-macrophage colony-stimulating factor (GM-CSF) to WNV-infected mice. Recombinant human GM-CSF (rHuGMCSF) (sargramostim [Leukine]) is an FDA-approved drug used to increase white blood cells following leukopenia-inducing chemotherapy or bone marrow transplantation. Daily treatment of both uninfected and WNV-infected mice with subcutaneous injections of GM-CSF resulted in microglial proliferation and activation as indicated by the enhanced expression of the microglia activation marker ionized calcium binding adaptor molecule 1 (Iba1) and several microglia-associated inflammatory cytokines, including CCL2 (C-C motif chemokine ligand 2), interleukin 6 (IL-6), and IL-10. In addition, more microglia adopted an activated morphology as demonstrated by increased sizes and more pronounced processes. GM-CSF-induced microglial activation in WNV-infected mice was associated with reduced viral titers and apoptotic activity (caspase 3) in the brains of WNV-infected mice and significantly increased survival. WNV-infected ex vivo brain slice cultures (BSCs) treated with GM-CSF also showed reduced viral titers and caspase 3 apoptotic cell death, indicating that GM-CSF specifically targets the CNS and that its actions are not dependent on peripheral immune activity. Our studies suggest that stimulation of microglial activation may be a viable therapeutic approach for the treatment of WNV neuroinvasive disease. IMPORTANCE Although rare, WNV encephalitis poses a devastating health concern, with few treatment options and frequent long-term neurological sequelae. Currently, there are no human vaccines or specific antivirals against WNV infections, so further research into potential new therapeutic agents is critical. This study presents a novel treatment option for WNV infections using GM-CSF and lays the foundation for further studies into the use of GM-CSF as a treatment for WNV encephalitis as well as a potential treatment for other viral infections.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) shows therapeutic effect on dimethylnitrosamine (DMN)-induced liver fibrosis in rats

This study was undertaken to investigate the inhibitory effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) on dimethylnitrosamine (DMN)-induced liver fibrosis in rats. Liver fibrosis was induced in Sprague-Dawley rats by injecting DMN intraperitoneally (at 10 mg/kg of body weight) daily for three consecutive days per week for 4 weeks. To investigate the effect of GM-CSF on disease onset, GM-CSF (50 μg/kg of body weight) was co-treated with DMN for 2 consecutive days per week for 4 weeks (4-week groups). To observe the effect of GM-CSF on the progression of liver fibrosis, GM-CSF was post-treated alone at 5–8 weeks after the 4 weeks of DMN injection (8-week groups). We found that DMN administration for 4 weeks produced molecular and pathological manifestations of liver fibrosis, that is, it increased the expressions of collagen type I, alpha-smooth muscle actin (α-SMA), and transforming growth factor-β1 (TGF-β1), and decreased peroxisome proliferator-activated receptor gamma (PPAR-γ) expression. In addition, elevated serum levels of aspartate aminotransferase (AST), total bilirubin level (TBIL), and decreased albumin level (ALB) were observed. In both the 4-week and 8-week groups, GM-CSF clearly improved the pathological liver conditions in the gross and histological observations, and significantly recovered DMN-induced increases in AST and TBIL and decreases in ALB serum levels to normal. GM-CSF also significantly decreased DMN-induced increases in collagen type I, α-SMA, and TGF-β1 and increased DMN-induced decreases in PPAR-γ expression. In the DMN groups, survival decreased continuously for 8 weeks after DMN treatment for the first 4 weeks. GM-CSF showed a survival benefit when co-treated for the first 4 weeks but a marginal effect when post-treated for 5–8 weeks. In conclusion, co-treatment of GM-CSF showed therapeutic effects on DMN-induced liver fibrosis and survival rates in rats, while post-treatment efficiently blocked liver fibrosis.

The innate immune system stimulating cytokine GM-CSF improves learning/memory and interneuron and astrocyte brain pathology in Dp16 Down syndrome mice and improves learning/memory in wild-type mice

Down syndrome (DS) is characterized by chronic neuroinflammation, peripheral inflammation, astrogliosis, imbalanced excitatory/inhibitory neuronal function, and cognitive deficits in both humans and mouse models. Suppression of inflammation has been proposed as a therapeutic approach to treating DS co-morbidities, including intellectual disability (DS/ID). Conversely, we discovered previously that treatment with the innate immune system stimulating cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF), which has both pro- and anti-inflammatory activities, improved cognition and reduced brain pathology in a mouse model of Alzheimer's disease (AD), another inflammatory disorder, and improved cognition and reduced biomarkers of brain pathology in a phase II trial of humans with mild-to-moderate AD. To investigate the effects of GM-CSF treatment on DS/ID in the absence of AD, we assessed behavior and brain pathology in 12-14 month-old DS mice (Dp[16]1Yey) and their wild-type (WT) littermates, neither of which develop amyloid, and found that subcutaneous GM-CSF treatment (5 μg/day, five days/week, for five weeks) improved performance in the radial arm water maze in both Dp16 and WT mice compared to placebo. Dp16 mice also showed abnormal astrocyte morphology, increased percent area of GFAP staining in the hippocampus, clustering of astrocytes in the hippocampus, and reduced numbers of calretinin-positive interneurons in the entorhinal cortex and subiculum, and all of these brain pathologies were improved by GM-CSF treatment. These findings suggest that stimulating and/or modulating inflammation and the innate immune system with GM-CSF treatment may enhance cognition in both people with DS/ID and in the typical aging population.

Peptide OM-LV20 promotes structural and functional recovery of spinal cord injury in rats

At present, there are no satisfactory therapeutic drugs for the functional recovery of spinal cord injury (SCI). We previously identified a novel peptide (OM-LV20) that accelerated the regeneration of injured skin tissues of mice and exerts neuroprotective effects against cerebral ischemia/reperfusion injury in rats. Here, the intraperitoneal injection of OM-LV20 (1 μg/kg) markedly improved motor function recovery in the hind limbs of rats with traumatic SCI, and further enhanced spinal cord repair. Administration of OM-LV20 increased the number of surviving neuron bodies, as well as the expression levels of brain-derived neurotrophic factor (BDNF) and its receptor tyrosine receptor kinase B (TrkB). In the acute stage of SCI, OM-LV20 treatment also increased superoxide dismutase and glutathione content but decreased the levels of malonaldehyde and nitric oxide. Thus, OM-LV20 significantly promoted structural and functional recovery of SCI in adult rats by increasing neuronal survival and BDNF and TrkB expression, and thereby regulating the balance of oxidative stress. Based on our knowledge, this research is the first report on the effects of amphibian-derived peptide on the recovery of SCI and our results highlight the potential of peptide OM-LV20 administration in the acceleration of the recovery of SCI.

Jia Wei Xiao Yao San ameliorates chronic stress-induced depression-like behaviors in mice by regulating the gut microbiome and brain metabolome in relation to purine metabolism

BACKGROUND

The pathogenesis of depression remains largely unknown. Accumulating evidence demonstrates the existence of a complex relationship between gut microbiome composition and brain functions. Jia Wei Xiao Yao San (JWXYS) is considered a potential antidepressant. However, the pharmacological mechanisms of JWXYS have not yet been clarified.

PURPOSE

This study aimed to explore the effects of JWXYS on chronic stress-induced depression-like behaviors in mice.

METHODS

A chronic restraint stress mouse model of depression was established. JWXYS was administered, and the responses of these mice to treatment were evaluated through several behavioral tests. The activity of astrocytes and microglia was detected by specific fluorescent labels. Inflammatory cytokines were quantified in intestinal and cerebral tissues. An integrated approach with full-length 16S rRNA sequencing and different types of untargeted metabolomics was conducted to investigate the relationship between the gut microbiome at the species level, metabolic brain functions, and JWXYS.

RESULTS

We found that behavioral symptoms were associated with the relative abundance of Lactobacillus animalis. After JWXYS treatment, the relative abundance of Ileibacterium valens with enzymes potentially involved in purine metabolism was also described. The activation of astrocytes and microglia was negatively correlated with the relative abundance of L. animalis. Combined with network pharmacological analysis, several targets predicted based on JWXYS treatment focused on purine metabolism, which was also enriched from cerebral metabolites regulated by JWXYS.

CONCLUSION

Our study suggests that L. animalis is involved in depression-like behaviors in mice. JWXYS increases the abundance of I. valens with potential enzymes in relation to cerebral purine metabolism, which is positively correlated with the activation of astrocytes in the amygdala.

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.

Safety and efficacy of sargramostim (GM-CSF) in the treatment of Alzheimer's disease

INTRODUCTION

Inflammatory markers have long been observed in the brain, cerebrospinal fluid (CSF), and plasma of Alzheimer's disease (AD) patients, suggesting that inflammation contributes to AD and might be a therapeutic target. However, non-steroidal anti-inflammatory drug trials in AD and mild cognitive impairment (MCI) failed to show benefit. Our previous work seeking to understand why people with the inflammatory disease rheumatoid arthritis are protected from AD found that short-term treatment of transgenic AD mice with the pro-inflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) led to an increase in activated microglia, a 50% reduction in amyloid load, an increase in synaptic area, and improvement in spatial memory to normal. These results called into question the consensus view that inflammation is solely detrimental in AD. Here, we tested our hypothesis that modulation of the innate immune system might similarly be used to treat AD in humans by investigating the ability of GM-CSF/sargramostim to safely ameliorate AD symptoms/pathology.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted in mild-to-moderate AD participants (NCT01409915). Treatments (20 participants/group) occurred 5 days/week for 3 weeks plus two follow-up (FU) visits (FU1 at 45 days and FU2 at 90 days) with neurological, neuropsychological, blood biomarker, and imaging assessments.

RESULTS

Sargramostim treatment expectedly changed innate immune system markers, with no drug-related serious adverse events or amyloid-related imaging abnormalities. At end of treatment (EOT), the Mini-Mental State Examination score of the sargramostim group increased compared to baseline (P = .0074) and compared to placebo (P = .0370); the treatment effect persisted at FU1 (P = .0272). Plasma markers of amyloid beta (Aβ40 [decreased in AD]) increased 10% (P = .0105); plasma markers of neurodegeneration (total tau and UCH-L1) decreased 24% (P = .0174) and 42% (P = .0019), respectively, after sargramostim treatment compared to placebo.

DISCUSSION

The innate immune system is a viable target for therapeutic intervention in AD. An extended treatment trial testing the long-term safety and efficacy of GM-CSF/sargramostim in AD is warranted.

Analysis of the immune response to sciatic nerve injury identifies efferocytosis as a key mechanism of nerve debridement

Sciatic nerve crush injury triggers sterile inflammation within the distal nerve and axotomized dorsal root ganglia (DRGs). Granulocytes and pro-inflammatory Ly6C^high monocytes infiltrate the nerve first and rapidly give way to Ly6C^negative inflammation-resolving macrophages. In axotomized DRGs, few hematogenous leukocytes are detected and resident macrophages acquire a ramified morphology. Single-cell RNA-sequencing of injured sciatic nerve identifies five macrophage subpopulations, repair Schwann cells, and mesenchymal precursor cells. Macrophages at the nerve crush site are molecularly distinct from macrophages associated with Wallerian degeneration. In the injured nerve, macrophages ‘eat’ apoptotic leukocytes, a process called efferocytosis, and thereby promote an anti-inflammatory milieu. Myeloid cells in the injured nerve, but not axotomized DRGs, strongly express receptors for the cytokine GM-CSF. In GM-CSF-deficient (Csf2^-/-) mice, inflammation resolution is delayed and conditioning-lesion-induced regeneration of DRG neuron central axons is abolished. Thus, carefully orchestrated inflammation resolution in the nerve is required for conditioning-lesion-induced neurorepair.

Microglia and Macrophages in the Pathological Central and Peripheral Nervous Systems

Microglia, the immunocompetent cells in the central nervous system (CNS), have long been studied as pathologically deteriorating players in various CNS diseases. However, microglia exert ameliorating neuroprotective effects, which prompted us to reconsider their roles in CNS and peripheral nervous system (PNS) pathophysiology. Moreover, recent findings showed that microglia play critical roles even in the healthy CNS. The microglial functions that normally contribute to the maintenance of homeostasis in the CNS are modified by other cells, such as astrocytes and infiltrated myeloid cells; thus, the microglial actions on neurons are extremely complex. For a deeper understanding of the pathophysiology of various diseases, including those of the PNS, it is important to understand microglial functioning. In this review, we discuss both the favorable and unfavorable roles of microglia in neuronal survival in various CNS and PNS disorders. We also discuss the roles of blood-borne macrophages in the pathogenesis of CNS and PNS injuries because they cooperatively modify the pathological processes of resident microglia. Finally, metabolic changes in glycolysis and oxidative phosphorylation, with special reference to the pro-/anti-inflammatory activation of microglia, are intensively addressed, because they are profoundly correlated with the generation of reactive oxygen species and changes in pro-/anti-inflammatory phenotypes.

Recruiting the innate immune system with GM-CSF to fight viral diseases, including West Nile Virus encephalitis and COVID-19

As the coronavirus disease 2019 (COVID-19) pandemic grows throughout the world, it is imperative that all approaches to ameliorating its effects be investigated, including repurposing drugs that show promise in other diseases. We have been investigating an approach to multiple disorders that involves recruiting the innate immune system to aid the body's healing and regenerative mechanism(s). In the case of West Nile Virus encephalitis and potentially COVID-19, the proposed intervention to stimulate the innate immune system may give the adaptive immune response the necessary time to develop, finish clearing the virus, and provide future immunity. Furthermore, we have found that GM-CSF-induced recruitment of the innate immune system is also able to reverse brain pathology, neuroinflammation and cognitive deficits in mouse models of Alzheimer's disease and Down syndrome, as well as improving cognition in normal aging and in human patients with cognitive deficits due to chemotherapy, both of which exhibit neuroinflammation. Others have shown that GM-CSF is an effective treatment for both bacterial and viral pneumonias, and their associated inflammation, in animals and that it has successfully treated pneumonia-associated Acute Respiratory Distress Syndrome in humans. These and other data strongly suggest that GM-CSF may be an effective treatment for many viral infections, including COVID-19.

Natural killer cells protect white matter integrity in bipolar disorder

BACKGROUND

Bipolar Disorder (BD) associates with disrupted white matter (WM) microstructure and functional connectivity, and with a perturbation of the immune system. Higher cytokines, and reduced T cells, correlated with WM disruption and fMRI responses. A core component of the innate immune system, natural killer (NK) cells were detected in brain parenchyma, but never studied in BD.

METHODS

We studied Diffusion Tensor Imaging (DTI) measures of water diffusion, fMRI corticolimbic functional response and connectivity, and multi-parameter cytofluorometry analysis of NK (CD56⁺) subpopulations, in 30 inpatients with active Bipolar Disorder type I. NK cells were also obtained in 36 healthy controls.

RESULTS

Patients had significantly higher circulating counts of CD56⁺GMCSF⁺, CD56⁺INFγ⁺, and CD56⁺IL17⁺. NK cell levels positively associated to fractional anisotropy (FA) measures. CD56⁺TNFα⁺, CD56⁺INFγ⁺, and CD56⁺GMCSF⁺ directly correlated with FA, and inversely with radial (RD) and mean (MD) diffusivity. Duration of lithium treatment associated with higher CD56⁺TNFα⁺, CD56⁺IL2⁺, and CD56⁺IL4⁺, and positively associated with FA in tracts were NKs had significant effects. A mediation model suggested a partial mediation of CD56⁺TNFα⁺ cells, higher in patients on lithium, on the effects of lithium on FA. Frequencies of the same cytokine-producing NK cells also influenced fMRI cortico-limbic functional connectivity during processing of both, emotional and non-emotional stimuli.

DISCUSSION

Higher circulating cytokine-producing NK cells associated with lithium treatment, and with DTI measures of WM integrity, partially mediating the effect of lithium on WM. The same cells associated with fMRI responses and connectivity, thus suggesting an effect on structural and functional connectomics in BD.

Beneficial Effects of Theta-Burst Transcranial Magnetic Stimulation on Stroke Injury via Improving Neuronal Microenvironment and Mitochondrial Integrity

Recent work suggests that repetitive transcranial magnetic stimulation (rTMS) may beneficially alter the pathological status of several neurological disorders, although the mechanism remains unclear. The current study was designed to investigate the effects of rTMS on behavioral deficits and potential underlying mechanisms in a rat photothrombotic (PT) stroke model. From day 0 (3 h) to day 5 after the establishment of PT stroke, 5-min daily continuous theta-burst rTMS (3 pulses of 50 Hz repeated every 200 ms, intensity at 200 G) was applied on the infarct hemisphere. We report that rTMS significantly attenuated behavioral deficits and infarct volume after PT stroke. Further investigation demonstrated that rTMS remarkably reduced synaptic loss and neuronal degeneration in the peri-infarct cortical region. Mechanistic studies displayed that beneficial effects of rTMS were associated with robust suppression of reactive micro/astrogliosis and the overproduction of pro-inflammatory cytokines, as well as oxidative stress and oxidative neuronal damage especially at the late stage following PT stroke. Intriguingly, rTMS could effectively induce a shift in microglial M1/M2 phenotype activation and an A1 to A2 switch in astrocytic phenotypes. In addition, the release of anti-inflammatory cytokines and mitochondrial MnSOD in peri-infarct regions were elevated following rTMS treatment. Finally, rTMS treatment efficaciously preserved mitochondrial membrane integrity and suppressed the intrinsic mitochondrial caspase-9/3 apoptotic pathway within the peri-infarct cortex. Our novel findings indicate that rTMS treatment exerted robust neuroprotection when applied at least 3 h after ischemic stroke. The underlying mechanisms are partially associated with improvement of the local neuronal microenvironment by altering inflammatory and oxidative status and preserving mitochondrial integrity in the peri-infarct zone. These findings provide strong support for the promising therapeutic effect of rTMS against ischemic neuronal injury and functional deficits following stroke.

The antidepressant effects of GM-CSF are mediated by the reduction of TLR4/NF-ĸB-induced IDO expression

BACKGROUND

Indoleamine 2, 3-dioxygenase 1 (IDO) is responsible for the progression of the kynurenine pathway. This pathway has been implicated in the pathophysiology of inflammation-induced depression in which conventional antidepressants are not effective. It has been reported that granulocyte-macrophage stimulating factor (GM-CSF) could interfere with the induction of IDO in septic patients. We hypothesized that GM-CSF could exert antidepressant effects through IDO downregulation in a model for acute inflammation-induced depression.

METHODS

To produce the model, lipopolysaccharide (LPS) (0.83 mg/kg) was administered intraperitoneally to mice. It has been well documented that LPS mediates IDO overexpression through TLR4/NF-ĸB signaling. In the treatment group, mice received GM-CSF (30 μg/kg, i.p.) thirty minutes prior to LPS injection. A validated selective serotonin reuptake inhibitor, fluoxetine (30 mg/kg i.p.), was also administered to an experimental group 30 min prior to LPS. Depressive-like behaviors were evaluated based on the duration of immobility in the forced swim test. To confirm that GM-CSF interferes with IDO induction in LPS treated mice, real-time PCR was used to quantify IDO mRNA expression. Furthermore, in order to study whether GM-CSF inhibits the TLR4/NF-ĸB signaling pathway, we measured levels ofpNF-ĸB and TLR4 by western blotting.

RESULTS

GM-CSF demonstrated significant antidepressant activity in the presence of LPS on immobility (p < .001) and latency (p = .010) times in the forced swim test. In contrast, fluoxetine did not show any antidepressant activity on either immobility (p = .918) or latency (p = .566) times. Furthermore, GM-CSF inhibited the increase in IDO mRNA (p = .032) and protein (p = .016) expression as a result of LPS administration. A similar trend was observed for TLR4 (p = .042) and pNF-ĸB (p = .026) expression as both proteins showed reduced expression levels in the GM-CSF-pretreated group compared to the untreated (LPS) group.

CONCLUSION

Our results propose a promising antidepressant effect for GM-CSF possibly through the downregulation of IDO expression. This remedying effect of GM-CSF could be attributed to decreased amounts of TLR4 and active NF-ĸB in the treated mice.

LINGO-1 deficiency promotes nerve regeneration through reduction of cell apoptosis, inflammation, and glial scar after spinal cord injury in mice

Leucine-rich repeat and immunoglobulin domain-containing protein 1 (LINGO-1) is a transmembrane protein that negatively regulates neural regeneration in the central nervous system. LINGO-1 expression is up-regulated after central nerve injury, and is accompanied by cell death. Both LINGO-1 and cell death in the injury microenvironment are thought to limit neural regeneration, but the relationship between LINGO-1 and cell death has not been characterized. To investigate whether LINGO-1 deletion improves the spinal cord microenvironment after spinal cord injury (SCI) and contributes to cell survival, we generated LINGO-1 knockout (KO) mice. These mice and wild-type control mice were subjected to spinal cord transection. Fourteen days after spinal cord transection, cell apoptosis, inflammation, glial scar, and growth of nerve fibers were evaluated by immunostaining. The results showed that LINGO-1 KO mice demonstrated a profound reduction in expression of caspase-3, transferase-mediated deoxyuridine triphosphate biotin nick end labeling (TUNEL), ionized calcium binding adapter molecule 1 (IBA1), glial fibrillary acidic protein (GFAP), and chondroitin sulfate proteoglycans (CSPGs) compared to controls. In contrast, expression of neurofilament (NF) at the SCI site in LINGO-1 KO mice was markedly increased compared to that in wild-type mice. These results suggested that LINGO-1 plays a critical role in the injury microenvironment in processes such as cell death, inflammatory response, and glial scar formation. Importantly, LINGO-1 deletion and a positive microenvironment may exert synergistic effects to promote nerve fiber regeneration. Therefore, inhibition of LINGO-1 may be a therapeutic strategy to promote neural regeneration following SCI.

TGN-020 alleviates edema and inhibits astrocyte activation and glial scar formation after spinal cord compression injury in rats

AIMS

Identifying drugs that inhibit edema and glial scar formation and increase neuronal survival is crucial to improving outcomes after spinal cord injury (SCI). Here, we used 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020), a potent selective inhibitor of aquaporin 4 (AQP4), to investigate the effects of TGN-020 on SCI in Sprague-Dawley rats.

MAIN METHODS

We compressed the spinal cord at T10 using a sterile impounder (35 g, 5 min), to induce moderate injury. TGN-020 (100 mg/kg) or an equal volume of 10% dimethyl sulfoxide was then administered via intraperitoneal injection. Neurological function was evaluated using the Basso-Beattie-Bresnahan open-field locomotor scale 1, 3, 7, 14, 21, and 28 days after SCI. The degree of edema was assessed via determination of the precise spinal cord water content 3 days after SCI. Expression levels of AQP4, glial fibrillary acidic protein (GFAP), proliferating cell nuclear antigen (PCNA), and growth-associated protein-43 (GAP-43) were determined via western blotting and immunofluorescence staining 3 days after SCI and 4 weeks after SCI. Numbers of surviving neurons and glial scar sizes were determined using Nissl and hematoxylin-eosin staining, respectively.

KEY FINDINGS

Our results showed that TGN-020 promoted functional recovery at days 3, 7, 14, 21, and 28, as well as reduced the degree of edema and inhibited the expression of AQP4, GFAP, PCNA at days 3 after SCI. Furthermore, observations 4 weeks after SCI revealed that TGN-020 inhibited the glial scar formation and upregulated GAP-43 expression.

SIGNIFICANCE

TGN-020 can alleviate spinal cord edema, inhibit glial scar formation, and promote axonal regeneration, conferring beneficial effects on recovery in rats.

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.

Extracellular matrix and traumatic brain injury

The brain extracellular matrix (ECM) plays a crucial role in both the developing and adult brain by providing structural support and mediating cell-cell interactions. In this review, we focus on the major constituents of the ECM and how they function in both normal and injured brain, and summarize the changes in the composition of the ECM as well as how these changes either promote or inhibit recovery of function following traumatic brain injury (TBI). Modulation of ECM composition to facilitates neuronal survival, regeneration and axonal outgrowth is a potential therapeutic target for TBI treatment.

Glial scar-modulation as therapeutic tool in spinal cord injury in animal models

PURPOSE

Spinal Cord injury represents, in veterinary medicine, most of the neurological attendances and may result in permanent disability, death or euthanasia. Due to inflammation resulting from trauma, it originates the glial scar, which is a cell interaction complex system. Its function is to preserve the healthy circuits, however, it creates a physical and molecular barrier that prevents cell migration and restricts the neuroregeneration ability.

METHODS

This review aims to present innovations in the scene of treatment of spinal cord injury, approaching cell therapy, administration of enzyme, anti-inflammatory, and other active principles capable of modulating the inflammatory response, resulting in glial scar reduction and subsequent functional improvement of animals.

RESULTS

Some innovative therapies as cell therapy, administration of enzymes, immunosuppressant or other drugs cause the modulation of inflammatory response proved to be a promising tool for the reduction of gliosis.

CONCLUSION

Those tools promise to reduce gliosis and promote locomotor recovery in animals with spinal cord injury.

Transplantation of human bone marrow-derived clonal mesenchymal stem cells reduces fibrotic scar formation in a rat spinal cord injury model

This study aimed to evaluate the therapeutic effect on tissue repair and scar formation of human bone marrow-derived clonal mesenchymal stem cells (hcMSCs) homogeneously isolated by using a subfractionation culturing method, in comparison with the non-clonal MSCs (hMSCs), in a rat spinal cord injury (SCI) model. The SCI was made using a vascular clip at the T9 level. Cells were transplanted into the lesion site 3 days after injury. A functional test was performed over 4 weeks employing a BBB score. Rats were killed for histological analysis at 3 days, 1 week and 4 weeks after injury. The transplantation of hMSCs and hcMSCs significantly reduced lesion size and the fluid-filled cavity at 4 weeks in comparison with the control group injected with phosphate buffered saline (PBS) (p < 0.01). Transplantation of hcMSCs showed more axons reserved than that of hMSCs in the lesion epicentre filled with non-neuronal tissues. In addition, hMSCs and hcMSCs clearly reduced the inflammatory reaction and intraparenchymal hemorrhaging, compared with the PBS group. Interestingly, hcMSCs largely decreased Col IV expression, one of the markers of fibrotic scars. hcMSCs yielded therapeutic effects more than equal to those of hMSCs on the SCI. Both hMSCs and hcMSCs created an increase in axon regeneration and reduced scar formation around the SCI lesion. Copyright © 2017 John Wiley & Sons, Ltd.

Transcriptome profile of rat genes in injured spinal cord at different stages by RNA-sequencing

Background

Spinal cord injury (SCI) results in fatal damage and currently has no effective treatment. The pathological mechanisms of SCI remain unclear. In this study, genome-wide transcriptional profiling of spinal cord samples from injured rats at different time points after SCI was performed by RNA-Sequencing (RNA-Seq). The transcriptomes were systematically characterized to identify the critical genes and pathways that are involved in SCI pathology.

Results

RNA-Seq results were obtained from total RNA harvested from the spinal cords of sham control rats and rats in the acute, subacute, and chronic phases of SCI (1 day, 6 days and 28 days after injury, respectively; n = 3 in every group). Compared with the sham-control group, the number of differentially expressed genes was 1797 in the acute phase (1223 upregulated and 574 downregulated), 6590 in the subacute phase (3460 upregulated and 3130 downregulated), and 3499 in the chronic phase (1866 upregulated and 1633 downregulated), with an adjusted P-value <0.05 by DESeq. Gene ontology (GO) enrichment analysis showed that differentially expressed genes were most enriched in immune response, MHC protein complex, antigen processing and presentation, translation-related genes, structural constituent of ribosome, ion gated channel activity, small GTPase mediated signal transduction and cytokine and/or chemokine activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the most enriched pathways included ribosome, antigen processing and presentation, retrograde endocannabinoid signaling, axon guidance, dopaminergic synapses, glutamatergic synapses, GABAergic synapses, TNF, HIF-1, Toll-like receptor, NF-kappa B, NOD-like receptor, cAMP, calcium, oxytocin, Rap1, B cell receptor and chemokine signaling pathway.

Conclusions

This study has not only characterized changes in global gene expression through various stages of SCI progression in rats, but has also systematically identified the critical genes and signaling pathways in SCI pathology. These results will expand our understanding of the complex molecular mechanisms involved in SCI and provide a foundation for future studies of spinal cord tissue damage and repair.

The sequence data from this study have been deposited into Sequence Read Archive (http://www.ncbi.nlm.nih.gov/sra; accession number PRJNA318311).

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3532-x) contains supplementary material, which is available to authorized users.

The upregulation of annexin A2 after spinal cord injury in rats may have implication for astrocyte proliferation

Annexin A2 (ANXA2), is a member of the annexin family of proteins that exhibit Ca²⁺-dependent binding to phospholipids. One attractive biological function of ANXA2 is participating in DNA synthesis and cell proliferation. Previous studies have shown that ANXA2 play a role in the development of the central nervous system. However, the biological function of ANXA2 after spinal cord injury (SCI) is still with limited acquaintance. In the present study, we performed a SCI model in adult rats and investigated the dynamic changes of ANXA2 expression in the spinal cord. Western blot analysis indicated a striking expression upregulation of ANXA2 after SCI. Immunohistochemistry further confirmed that ANXA2 immunoactivity was expressed at low levels in normal condition and increased at 5day after SCI. Double immunofluorescence staining prompted that ANXA2 immunoreactivity was found in astrocytes and neurons. Interestingly, ANXA2 expression was increased predominantly in astrocytes. We also examined the expression profiles of proliferating cell nuclear antigen (PCNA), Cyclin D1 and active caspase-3 in the injured spinal cords by western blot. Co-expression of ANXA2/PCNA, ANXA2/Cyclin D1 was detected in glial fibrillary acidic protein. Importantly, double immunofluorescence staining revealed that cell proliferation evaluated by PCNA appeared in many ANXA2-expressing cells and rare caspase-3 was observed in ANXA2-expressing cells after SCI. In addition, ANXA2 knockdown in astrocytes resulted in the increase of PCNA expression after LPS stimulation, showing that ANXA2 inhibited astrocyte proliferation after inflammation. Our data suggested that ANXA2 might play important roles in CNS pathophysiology after SCI.

The role of the PI3K/Akt/mTOR pathway in glial scar formation following spinal cord injury

Several studies suggest that glial scars pose as physical and chemical barriers that limit neurite regeneration after spinal cord injury (SCI). Evidences suggest that the activation of the PI3K/Akt/mTOR signaling pathway is involved in glial scar formation. Therefore, inhibition of the PI3K/Akt/mTOR pathway may beneficially attenuate glial scar formation after SCI. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) negatively regulates the PI3K/Akt/mTOR pathway. Therefore, we hypothesized that the overexpression of PTEN in the spinal cord will have beneficial effects after SCI. In the present study, we intrathecally injected a recombinant adenovirus carrying the pten gene (Ad-PTEN) to cause overexpression of PTEN in rats with contusion injured spinal cords. The results suggest overexpression of PTEN in spinal cord attenuated glial scar formation and led to improved locomotor function after SCI. Overexpression of PTEN following SCI attenuated gliosis, affected chondroitin sulfate proteoglycan expression, and improved axon regeneration into the lesion site. Furthermore, we suggest that the activation of the PI3K/Akt/mTOR pathway in astrocytes at 3 days after SCI may be involved in glial scar formation. Because delayed treatment with Ad-PTEN enhanced motor function recovery more significantly than immediate treatment with Ad-PTEN after SCI, the results suggest that the best strategy to attenuate glial scar formation could be to introduce 3 days after SCI. This study's findings thus have positive implications for patients who are unable to receive immediate medical attention after SCI.

Antiapoptotic Effect of Highly Secreted GMCSF From Neuronal Cell-specific GMCSF Overexpressing Neural Stem Cells in Spinal Cord Injury Model

STUDY DESIGN

Neuronal cell-specific gene expression system and neural stem cells (NSCs) were combined for treatment of spinal cord injury (SCI).

OBJECTIVE

To verify the reproducibility of the neuronal cell-specific therapeutic gene overexpression system, we develop a neuronal cell-specific granulocyte-macrophage colony-stimulating factor expression system (NSE-GMCSF), and then examine the characteristics of GMCSF overexpression and protective effect on neural cells in vitro and vivo.

SUMMARY OF BACKGROUND DATA

The stem cell transplantation is considered a promising therapy for SCI. However, stem cell monotherapy strategy is insufficient for complete recovery after SCI. Therefore, combined treatment method based on stem cells with other therapeutic system may be effective for improving the therapeutic efficacy. In this study, we established the gene and stem cell therapy platform based on NSCs and neuronal cell-specific gene expression system.

METHODS

To examine the GMCSF expression pattern, we compared the amount of secreted GMCSF from the neuronal cell-specific GMCSF expressing NSCs with control GMCSF-expressing NSCs (respectively, NSE-GMCSF-NSCs vs. SV-GMCSF-NSCs) by ELISA in vitro and in vivo, and then verified the neuronal protective effect of these cells in vitro and vivo.

RESULTS

The results showed that NSE-GMCSF-NSCs secreted more GMCSF compared with SV-GMCSF-NSCs in normoxia, hypoxia and cytotoxic conditions. The cell viability of NSE-GMCSF-NSCs was increased depending on the amount of secreted GMCSF in cytotoxic condition. In addition, the amount of secreted GMCSF by NSE-GMCSF-NSCs transplanted into injured spinal cord was significantly higher than SV-GMCSF-NSCs. Higher amount of secreted GMCSF decreased the expression of proapoptotic protein, Bax.

CONCLUSION

In this study, we demonstrated that the neuronal cell-specific gene expression system induced overexpression of GMCSF in NSCs. These combined NSCs & gene therapy treatment protocol would be an effective therapeutic system for SCI.

LEVEL OF EVIDENCE

N/A.

GM-CSF reduces expression of chondroitin sulfate proteoglycan (CSPG) core proteins in TGF-β-treated primary astrocytes

GM-CSF plays a role in the nervous system, particularly in cases of injury. A therapeutic effect of GM-CSF has been reported in rat models of various central nervous system injuries. We previously showed that GM-CSF could enhance long-term recovery in a rat spinal cord injury model, inhibiting glial scar formation and increasing the integrity of axonal structure. Here, we investigated molecular the mechanism(s) by which GM-CSF suppressed glial scar formation in an in vitro system using primary astrocytes treated with TGF-β. GM-CSF repressed the expression of chondroitin sulfate proteoglycan (CSPG) core proteins in astrocytes treated with TGF-β. GM-CSF also inhibited the TGF-β-induced Rho-ROCK pathway, which is important in CSPG expression. Finally, the inhibitory effect of GM-CSF was blocked by a JAK inhibitor. These results may provide the basis for GM-CSF’s effects in glial scar inhibition and ultimately for its therapeutic effect on neural cell injuries. [BMB Reports 2014; 47(12): 679-684]

Histamine promotes locomotion recovery after spinal cord hemisection via inhibiting astrocytic scar formation

AIM

This study investigated whether histamine could play a protective role in pathophysiological response of spinal cord injury (SCI) and regulate the glial scar formation.

METHODS

Functional assessment and histological analyses were performed to investigate the effect of histamine after SCI. Histidine decarboxylase knockout (HDC(-/-)) mice were used to confirm the action of histamine. Selective antagonists for H1 and H2 receptors were utilized in vivo and in vitro to verify the functional properties of histamine on astrogliosis.

RESULTS

The local administration of histamine significantly attenuated the tissue damage and glial scar formation after SCI. In particular, the astrogliosis and neurocan expression found around the lesion were significantly suppressed by histamine. Immunofluorescent staining for neurofilament showed that histamine promoted axonal growth across the glial scar. The HDC(-/-) mice, lacking in endogenous histamine, showed lower behavior score, increased lesion size and astrogliosis, as compared with the wild types. The effect of histamine on locomotor recovery and reactive astrogliosis is reversed by H1 receptor antagonist but not H2 receptor antagonist.

CONCLUSIONS

Our results indicate that histamine significantly improved the chronic locomotor recovery via attenuating astrogliosis after SCI by stimulating histamine H1 receptor. This study highlights a therapeutic potential of histamine and its related drugs for SCI.

Hyaluronan tetrasaccharide exerts neuroprotective effect and promotes functional recovery after acute spinal cord injury in rats

The objective of this study was to explore the therapeutic efficiency of hyaluronan tetrasaccharide (HA4) treatment after spinal cord injury (SCI) in rats and to investigate the underlying mechanism. Locomotor functional and electrophysiological evaluations revealed that the behavioral function of rats in the HA4-treated group was significantly improved compared with the vehicle-treated group. The expression of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), cluster determinant (CD44) and Toll-like receptor-4 (TLR-4) was obviously upregulated in the HA4-treated group than that in the sham and vehicle-treated group. Furthermore, HA4 could induce BDNF and VEGF expression in the astrocytes in vitro. In addition, the high expression of BDNF and VEGF could be inhibited by blocking CD44 and TLR-4. These findings indicate that HA4 could be useful as a promising therapeutic agent for SCI and might exert the effect by interaction with the CD44 and TLR-4.

Effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor on glial scar formation after spinal cord injury in rats

OBJECT

This study investigated the effects of granulocyte colony-stimulating factor (G-CSF) on glial scar formation after spinal cord injury (SCI) in rats and compared the therapeutic effects between G-CSF and granulocytemacrophage colony-stimulating factor (GM-CSF) to evaluate G-CSF as a potential substitute for GM-CSF in clinical application.

METHODS

Rats were randomly assigned to 1 of 4 groups: a sham-operated group (Group 1), an SCI group without treatment (Group 2), an SCI group treated with G-CSF (Group 3), and an SCI group treated with GM-CSF (Group 4). G-CSF and GM-CSF were administered via intraperitoneal injection immediately after SCI. The effects of G-CSF and GM-CSF on functional recovery, glial scar formation, and axonal regeneration were evaluated and compared.

RESULTS

The rats in Groups 3 and 4 showed better functional recovery and more decreased cavity sizes than those in Group 2 (p < 0.05). Both G-CSF and GM-CSF suppressed intensive expression of glial fibrillary acidic protein around the cavity at 4 weeks and reduced the expression of chondroitin sulfate proteoglycans (p < 0.05). Also, early administration of G-CSF and GM-CSF protected axon fibers from destructive injury and facilitated axonal regeneration. There were no significant differences in comparisons of functional recovery, glial scar formation, and axonal regeneration between G-CSF and GM-CSF.

CONCLUSIONS

G-CSF suppressed glial scar formation after SCI in rats, possibly by restricting the expression of glial fibrillary acidic protein and chondroitin sulfate proteoglycans, which might facilitate functional recovery from SCI. GM-CSF and G-CSF had similar effects on glial scar formation and functional recovery after SCI, suggesting that G-CSF can potentially be substituted for GM-CSF in the treatment of SCI.

Alteration in chondroitin sulfate proteoglycan expression at the epicenter of spinal cord is associated with the loss of behavioral function in Tiptoe walking Yoshimura mice

The objective of this study was to explore the correlation between the alteration in chondroitin sulfate proteoglycan (CSPG) expression at the epicenter of spinal cord and the loss of behavioral function in tiptoe walking Yoshimura mice. The tiptoe walking Yoshimura mice (twy) and Institute of Cancer Research (ICR) mice, aged 20 and 26 weeks, were used in the present study. The behavior assessment, micro-computed tomography and immunofluorescent staining were performed. The compressed spinal cord was histologically analyzed. The results showed that the expression of CSPG was statistically higher at the compressed spinal cord for twy mice compared with that at the normal spinal cord for ICR mice. At the 26th week, a large ossification block at the posterior longitudinal ligament of C1-3 was obviously observed at the micro-CT image We observed the BMS Score was significantly correlated with the expression of glial fibrillary acidic protein, CSPG and hyaluronan (P < 0.05). These findings suggest that compression injury induces the higher CSPG expression at the compressed spinal cord in the twy mice. Furthermore, the alteration in CSPG expression at the epicenter of spinal cord is associated with the loss of behavioral function in twy mice.

Spatiotemporal profile and essential role of RBM3 expression after spinal cord injury in adult rats

Hypoxia and other adverse conditions are usually encountered by rapidly growing cells. The RNA-binding motif protein 3 (RBM3) is induced by low temperature and hypoxia. However, its expression and function in spinal cord injury are still unclear. To investigate the certain expression and biological function in the central nervous system, we performed an acute spinal cord contusion injury (SCI) model in adult rats. Western blot analysis indicated a striking expression upregulation of RBM3 after spinal cord injury (SCI). Double immunofluorescence staining prompted that RBM3 immunoreactivity was found in astrocytes and neurons. Interestingly, RBM3 expression was increased predominantly in astrocytes. Furthermore, colocalization of RBM3 with proliferating cell nuclear antigen (PCNA) was detected in astrocytes. To further understand whether RBM3 plays a role in astrocyte proliferation, we applied lipopolysaccharide (LPS) to induce astrocyte proliferation in vitro. Western blot analysis demonstrated that RBM3 expression was positively correlated with PCNA expression following LPS stimulation. Immunofluorescence analysis showed that the expression of RBM3 was also changed following the stimulation of astrocytes with LPS, which was parallel with the data in vivo. Additionally, knocking RBM3 down with small interfering RNA (siRNA) demonstrated that RBM3 might play a significant role in the proliferation of astrocytes treated by hypoxia in vitro. These results suggest that RBM3 may be involved in the proliferation of astrocytes after SCI. To summarize, we firstly uncover the temporal and spatial expression changes of RBM3 in spinal cord injury. Our data suggest that RBM3 might be implicated in central nervous system pathophysiology after SCI.

Optic nerve inflammation and demyelination in a rodent model of nonarteritic anterior ischemic optic neuropathy

PURPOSE

Optic nerve (ON) ischemia associated with nonarteric anterior ischemic optic neuropathy (NAION) results in axon and myelin damage. Myelin damage activates the intraneural Ras homolog A (RhoA), contributing to axonal regeneration failure. We hypothesized that increasing extrinsic macrophage activity after ON infarct would scavenge degenerate myelin and improve postischemic ON recovery. We used the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) to upregulate ON macrophage activity, and evaluated GM-CSF's effects after ON ischemia in the NAION rodent model (rAION).

METHODS

Following rAION induction, GM-CSF was administered via intraventricular injection. Retinal ganglion cell (RGC) stereologic analysis was performed 1 month postinduction. The retinae and optic nerve laminae of vehicle- and GM-CSF-treated animals were examined immunohistochemically and ultrastructurally using transmission electron microscopy (TEM). RhoA activity was analyzed using a rhotekin affinity immunoanalysis and densitometry. Isolated ONs were analyzed functionally ex vivo by compound action potential (CAP) analysis.

RESULTS

Rodent NAION produces ON postinfarct demyelination and myelin damage, functionally demonstrable by CAP analysis and ultrastructurally by TEM. Granulocyte-macrophage colony-stimulating factor increased intraneural inflammation, activating and recruiting endogenous microglia, with only a moderate amount of exogenous macrophage recruitment. Treatment with GM-CSF reduced postinfarct intraneural RhoA activity, but did not neuroprotect RGCs after rAION.

CONCLUSIONS

Sudden ON ischemia results in previously unrecognized axonal demyelination, which may have a clinically important role in NAION-related functional defects and recovery. Granulocyte-macrophage colony-stimulating factor is not neuroprotective when administered directly to the optic nerve following ON ischemia, and does not improve axonal regeneration. It dramatically increases ON-microglial activation and recruitment.

Granulocyte macrophage colony-stimulating factor shows anti-apoptotic activity via the PI3K-NF-κB-HIF-1α-survivin pathway in mouse neural progenitor cells

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a hematopoietic cytokine that plays a crucial role in regulating the proliferation, differentiation, and survival of hematopoietic cells. Recent studies have shown that GM-CSF also has anti-apoptotic effects and regulates the expression of anti-apoptotic genes including Bcl-2 family proteins in neuronal cells in vitro and in vivo. However, the mechanism underlying the anti-apoptotic function of GM-CSF is not well understood. In the present work, we examined the role of phosphoinositide 3-kinase (PI3K)-AKT signal pathway in the anti-apoptotic activity of GM-CSF in mouse neural progenitor cells (NPCs). In terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, the anti-apoptotic effect of GM-CSF (apoptotic population of approximately 8.17 %) on staurosporine-induced apoptosis of NPCs (31.09 %) was significantly blocked by LY294002, an inhibitor of PI3K signal (24.04 %). We found that the PI3K-AKT signal pathway induced by GM-CSF treatment activated nuclear factor κB (NF-κB) and increased the expression of hypoxia-inducible factor 1α (HIF-1α) in normoxic conditions. Analyses using specific small interfering RNAs (siRNAs) showed that NF-κB was an upstream molecule of HIF-1α and activated its expression at the mRNA level. Further analyses using the siRNAs and chromatin immunoprecipitation (ChIP) showed that HIF-1α was responsible for the induced expression of survivin, a member of the inhibitor of apoptosis proteins (IAPs). Each of the specific siRNAs for NF-κB, HIF-1α, and survivin inhibited significantly the anti-apoptotic activity of GM-CSF on the staurosporine-induced apoptosis in NPCs in TUNEL assays. The results of this study showed the downstream signals and mechanism of PI3K/AKT-mediated anti-apoptotic activity of GM-CSF in NPCs, particularly revealing the role of the NF-κB-HIF-1α-survivin cascade.

Safety of granulocyte colony-stimulating factor (G-CSF) administration for postrehabilitated motor complete spinal cord injury patients: an open-label, phase I study

Granulocyte colony-stimulating factor (G-CSF) is a major growth factor in the activation and differentiation of granulocytes. This cytokine has been widely and safely employed in different conditions over many years. In this translational study, G-CSF is administered to 19 patients with chronic motor complete spinal cord injury, and outcomes are reported. All 19 patients received subcutaneous G-CSF (5 µg/kg per day) for 5 days and were followed for at least 6 months. The American Spinal Injury Association (ASIA) scale was used for motor and sensory assessment, and the International Association of Neurorestoratology-Spinal Cord Injury Functional Rating Scale (IANR-SCIFRS) and the Spinal Cord Independence Measure (SCIM) III were used to assess improvements in the ability to perform basic daily tasks. At the 6-month follow-up, upper extremity motor scores improved by 10, which was statistically significant (p = 0.007), whereas there were no significant changes in lower extremity motor scores. Also, the median of light touch sensory scores improved by 5 (p = 0.001). Pinprick sensory scores significantly improved (p = 0.002). The median increment in SCIM III total score was 7 (p = 0.001). The improvements in bladder and bowel management as well as moderate distance mobility subscales were also significant (p < 0.05). Total IANR-SCIFRS scores changed from 17 to 32, which was statistically significant (p = 0.001); again the bladder and bowel management subscale improvements were statistically significant (p < 0.05). Mild side effects of the G-CSF treatment such as bone pain, rash, fever, neuropathic pain, and spasticity were noted in a few patients; all of them resolved after 1 week. Our results indicate that G-CSF administration is a safe process and is associated with neurological as well as functional improvement. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

Using extracellular matrix for regenerative medicine in the spinal cord

Regeneration within the mammalian central nervous system (CNS) is limited, and traumatic injury often leads to permanent functional motor and sensory loss. The lack of regeneration following spinal cord injury (SCI) is mainly caused by the presence of glial scarring, cystic cavitation and a hostile environment to axonal growth at the lesion site. The more prominent experimental treatment strategies focus mainly on drug and cell therapies, however recent interest in biomaterial-based strategies are increasing in number and breadth. Outside the spinal cord, approaches that utilize the extracellular matrix (ECM) to promote tissue repair show tremendous potential for various application including vascular, skin, bone, cartilage, liver, lung, heart and peripheral nerve tissue engineering (TE). Experimentally, it is unknown if these approaches can be successfully translated to the CNS, either alone or in combination with synthetic biomaterial scaffolds. In this review we outline the first attempts to apply the potential of ECM-based biomaterials and combining cell-derived ECM with synthetic scaffolds.

Regulation of wound healing by granulocyte-macrophage colony-stimulating factor after vocal fold injury

Objectives

Vocal fold (VF) scarring remains a therapeutic challenge. Granulocyte-macrophage colony-stimulating factor (GM-CSF) facilitates epithelial wound healing, and recently, growth factor therapy has been applied to promote tissue repair. This study was undertaken to investigate the effect of GM-CSF on VF wound healing in vivo and in vitro.

Methods

VF scarring was induced in New Zealand white rabbits by direct injury. Immediately thereafter, either GM-CSF or PBS was injected into the VFs of rabbits. Endoscopic, histopathological, immunohistochemical, and biomechanical evaluations of VFs were performed at 3 months post-injury. Human vocal fold fibroblasts (hVFFs) were cultured with GM-CSF. Production of type I and III collagen was examined immunocytochemically, and the synthesis of elastin and hyaluronic acids was evaluated by ELISA. The mRNA levels of genes related to ECM components and ECM production-related growth factors, such as HGF and TGF-ß1, were examined by real time RT-PCR.

Results

The GM-CSF-treated VFs showed reduced collagen deposition in comparison to the PBS-injected controls (P<0.05). Immunohistochemical staining revealed lower amounts of type I collagen and fibronectin in the GM-CSF-treated VFs (P<0.05 and P<0.01, respectively). Viscous and elastic shear moduli of VF samples were significantly lower in the GM-CSF group than in the PBS-injected group (P<0.001 and P<0.01, respectively). Mucosal waves in the GM-CSF group showed significant improvement when compared to the PBS group (P = 0.0446). GM-CSF inhibited TGF-β1-induced collagen synthesis by hVFFs (P<0.05) and the production of hyaluronic acids increased at 72 hours post-treatment (P<0.05). The expressions of HAS-2, tropoelastin, MMP-1, HGF, and c-Met mRNA were significantly increased by GM-CSF, although at different time points (P<0.05).

Conclusion

The present study shows that GM-CSF offers therapeutic potential for the remodeling of VF wounds and the promotion of VF regeneration.

Improvement in sensory function via granulocyte-macrophage colony-stimulating factor in rat spinal cord injury models

OBJECT

The aim in this study was to determine whether granulocyte-macrophage colony-stimulating factor (GM-CSF) leads to sensory improvement in rat spinal cord injury (SCI) models.

METHODS

Thirty male Sprague-Dawley rats were included in this study: 10 in the sham group (laminectomy alone without SCI), 10 in the SCI group (SCI treated with phosphate-buffered saline), and 10 in the GM-CSF treatment group (SCI treated with GM-CSF). A locomotor function test and pain sensitivity test were conducted weekly for 9 weeks after SCI or sham injury. Spinal tissue samples from all rats were immunohistochemically examined for the expression of calcitonin gene-related peptide (CGRP) and abnormal sprouting at Week 9 post-SCI.

RESULTS

Granulocyte-macrophage colony-stimulating factor treatment improves functional recovery after SCI. In the tactile withdrawal threshold and frequency of the hindlimb paw, the GM-CSF group always responded with a statistically significant lower threshold than the SCI group 9 weeks after SCI (p < 0.05). The response of the forelimb and hindlimb paws to cold in the GM-CSF group always reflected a statistically significant lower threshold than in the SCI group 9 weeks after injury (p < 0.05). Decreased CGRP expression, observed by density and distribution area, was noted in the GM-CSF group (optical density 113.5 ± 20.4) compared with the SCI group (optical density 143.1 ± 18.7; p < 0.05).

CONCLUSIONS

Treatment with GM-CSF results in functional recovery, improving tactile and cold sense recovery in a rat SCI model. Granulocyte-macrophage colony-stimulating factor also minimizes abnormal sprouting of sensory nerves after SCI.

70th Birthday symposium of Prof. Dr. Riederer: autologous adult stem cells in ischemic and traumatic CNS disorders

Ischemic and traumatic insults of the central nervous system both result in definite chronic disability, only to some extent responsive to rehabilitation. Recently, the application of autologous stem cells (fresh bone marrow-derived mononuclear cells including mesenchymal and hematopoietic stem cells) was suggested to provide a strategy to further improve neurological recovery in these disorders. During the acute phase, stem cells act mainly by neuroprotection with prevention of apoptosis, whereas during the chronic situation they provide neurorestoration by transdifferentiation and/or the secretion of neurotrophic factors. To reach these goals, in the acute phase, stem cells (10 million mononuclear cells per kg body weight) might be best applied intravenously, as during the first 7 days after the lesion, the blood-brain barrier permits passage of cells from the blood into the brain or the spinal cord. In the more chronic situation, though, those cells might be applied best intrathecally by lumbar puncture. Based on the reported results so far, it seems justified to develop well-designed clinical double-blind trials in chronic spinal cord injury and ischemic stroke patients, as efficacy and safety concerns might not be answered by preclinical studies.

Mesenchymal stem cell graft improves recovery after spinal cord injury in adult rats through neurotrophic and pro-angiogenic actions

Numerous strategies have been managed to improve functional recovery after spinal cord injury (SCI) but an optimal strategy doesn't exist yet. Actually, it is the complexity of the injured spinal cord pathophysiology that begets the multifactorial approaches assessed to favour tissue protection, axonal regrowth and functional recovery. In this context, it appears that mesenchymal stem cells (MSCs) could take an interesting part. The aim of this study is to graft MSCs after a spinal cord compression injury in adult rat to assess their effect on functional recovery and to highlight their mechanisms of action. We found that in intravenously grafted animals, MSCs induce, as early as 1 week after the graft, an improvement of their open field and grid navigation scores compared to control animals. At the histological analysis of their dissected spinal cord, no MSCs were found within the host despite their BrdU labelling performed before the graft, whatever the delay observed: 7, 14 or 21 days. However, a cytokine array performed on spinal cord extracts 3 days after MSC graft reveals a significant increase of NGF expression in the injured tissue. Also, a significant tissue sparing effect of MSC graft was observed. Finally, we also show that MSCs promote vascularisation, as the density of blood vessels within the lesioned area was higher in grafted rats. In conclusion, we bring here some new evidences that MSCs most likely act throughout their secretions and not via their own integration/differentiation within the host tissue.

Guilty molecules, guilty minds? The conflicting roles of the innate immune response to traumatic brain injury

Traumatic brain injury (TBI) is a complex disease in the most complex organ of the body, whose victims endure lifelong debilitating physical, emotional, and psychosocial consequences. Despite advances in clinical care, there is no effective neuroprotective therapy for TBI, with almost every compound showing promise experimentally having disappointing results in the clinic. The complex and highly interrelated innate immune responses govern both the beneficial and deleterious molecular consequences of TBI and are present as an attractive therapeutic target. This paper discusses the positive, negative, and often conflicting roles of the innate immune response to TBI in both an experimental and clinical settings and highlights recent advances in the search for therapeutic candidates for the treatment of TBI.

NG2 expression in rats with acute T10 spinal cord injury

Rat models of T₁₀ spinal cord injury were established with a clamp method. NG2 expression was detected with immunohistochemical staining and western blot. Ten days after spinal cord injury, the number of NG2-positive cells in the damaged areas and NG2 absorbance were both significantly increased. The findings indicate that acute T₁₀ spinal cord injury in rats can lead to upregulation of NG2 protein expression in damaged areas.

Detection of neurocan in cerebrospinal fluid

Cerebrospinal fluid (CFS) is the most easily accessible component of the human central nervous system and has been successfully used for the analysis of disease-associated molecular imbalances, particularly for extracellular matrix components. Alterations in the presence of the nervous system-associated chondroitin sulfate proteoglycan neurocan had been reported from active multiple sclerosis lesions. Neurocan could be detected as a component of human CFS after enrichment of proteoglycans by anion exchange chromatography from pooled liquor as well as individual 300 μL samples by Western blot. However, a general alteration in neurocan levels in CFS sample with high immunoglobulin content could not be demonstrated. To further reduce the sample size, the development of a PG capturing assay based on polybrene-coated 96-well plates was initiated. This approach could be an interesting alternative option for the analysis of PGs in biological fluid and tissue samples.

Harmful and beneficial effects of inflammation after spinal cord injury: potential therapeutic implications

Spinal cord injury (SCI) results in immediate damage followed by a secondary phase of tissue damage that occurs over a period of several weeks. The mechanisms underlying this secondary damage are multiple and not fully understood. A number of studies suggest that the local inflammatory response in the spinal cord that occurs after SCI contributes importantly to secondary damage. This response is mediated by cells normally found in the central nervous system (CNS) as well as infiltrating leukocytes. While the inflammatory response mediated by these cells is required for efficient clearance of tissue debris, and promotes wound healing and tissue repair, they also release various factors that can be detrimental to neurons, glia, axons, and myelin. In this chapter we provide an overview of the inflammatory response at the cell and molecular level after SCI, and review the current state of knowledge about its contribution to tissue damage and repair. Additionally, we discuss how some of this work is leading to the development and testing of drugs that modulate inflammation to treat acute SCI in humans.

Delayed granulocyte colony-stimulating factor treatment promotes functional recovery in rats with severe contusive spinal cord injury

STUDY DESIGN

We used a severe contusive spinal cord injury (SCI) model and electrophysiologic, motor functional, immunohistochemical, and electron microscopic examinations to analyze the neuroprotective effects of delayed granulocyte colony-stimulating factor (G-CSF) treatment.

OBJECTIVE

To determine the neuroprotective effects of delayed G-CSF treatment using multimodality evaluations after severe contusive SCI in rats.

SUMMARY OF BACKGROUND DATA

Despite some reports that G-CSF treatment in the acute stage of different central nervous system injury models was neuroprotective, it has not been determined whether delayed G-CSF treatment can promote neural recovery in severe contusive SCI.

METHODS

Rats with severe contusive SCI were divided into 2 groups: G-CSF group rats were given serial subcutaneous injections of G-CSF, and control group rats (controls) were given only saline injections on postcontusion days 9 to 13. Using the Basso-Beattie-Bresnahan scale and cortical somatosensory evoked potentials, we recorded functional evaluations weekly. The spinal cords were harvested for protein and immunohistochemical analysis, and for electron microscopy examination.

RESULTS

The preserved spinal cord area was larger in G-CSF group rats than in control group rats. Both sensory and motor functions improved after G-CSF treatment. Detachment and disruption of the myelin sheets in the myelinated axons were significantly decreased, and axons sprouted and regenerated. There were fewer microglia and macrophages in the G-CSF group than in the control group. The levels of brain-derived neurotrophic factor were comparable between the 2 groups.

CONCLUSION

Delayed G-CSF treatment at the subacute stage of severe contusive SCI promoted spinal cord preservation and improved functional outcomes. The mechanism of G-CSF's protection may be related in part to attenuating the infiltration of microglia and macrophages.