The Modulation of Neurotrophin and Epigenetic Regulators: Implication for Astrocyte Proliferation and Neuronal Cell Apoptosis After Spinal Cord Injury

Epigenetic modifications of inflammation in spinal cord injury

Spinal cord injury (SCI) is a central nervous system injury that leads to neurological dysfunction or paralysis, which seriously affects patients' quality of life and causes a heavy social and economic burden. The pathological mechanism of SCI has not been fully revealed, resulting in unsatisfactory clinical treatment. Therefore, more research is urgently needed to reveal its precise pathological mechanism. Numerous studies have shown that inflammation is closely related to various pathological processes in SCI. Inflammatory response is an important pathological process leading to secondary injury, and sustained inflammatory response can exacerbate the injury and hinder the recovery of neurological function after injury. Epigenetic modification is considered to be an important regulatory mechanism in the pathological process of many diseases. Epigenetic modification mainly affects the function and characteristics of genes through the reversibility of mechanisms such as DNA methylation, histone modification, and regulation of non-coding RNA, thus having a significant impact on the pathological process of diseases and the survival state of the body. Recently, the role of epigenetic modification in the inflammatory response of SCI has gradually entered the field of view of researchers, and epigenetic modification may be a potential means to treat SCI. In this paper, we review the effects and mechanisms of different types of epigenetic modifications (including histone modifications, DNA methylation, and non-coding RNAs) on post-SCI inflammation and their potential therapeutic effects on inflammation to improve our understanding of the secondary SCI stage. This review aims to help identify new markers, signaling pathways and targeted drugs, and provide theoretical basis and new strategies for the diagnosis and treatment of SCI.

Haloperidol alters neurotrophic factors and epigenetic parameters in an animal model of schizophrenia induced by ketamine

This study aimed to evaluate Haloperidol's (Hal) effects on the behavioral, neurotrophic factors, and epigenetic parameters in an animal model of schizophrenia (SCZ) induced by ketamine (Ket). Injections of Ket or saline were administered intraperitoneal (once a day) between the 1st and 14th days of the experiment. Water or Hal was administered via gavage between the 8th and 14th experimental days. Thirty minutes after the last injection, the animals were subjected to behavioral analysis. The activity of DNA methyltransferase (DNMT), histone deacetylase (HDAC), and histone acetyltransferase and levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3), and glial-derived neurotrophic factor (GDNF) were evaluated in the frontal cortex, hippocampus, and striatum. Ket increased the covered distance and time spent in the central area of the open field, and Hal did not reverse these behavioral alterations. Significant increases in the DNMT and HDAC activities were detected in the frontal cortex and striatum from rats that received Ket, Hal, or a combination thereof. Besides, Hal per se increased the activity of DNMT and HDAC in the hippocampus of rats. Hal per se or the association of Ket plus Hal decreased BDNF, NGF, NT-3, and GDNF, depending on the brain region and treatment regimen. The administration of Hal can alter the levels of neurotrophic factors and the activity of epigenetic enzymes, which can be a factor in the development of effect collateral in SCZ patients. However, the precise mechanisms involved in these alterations are still unclear.

Subacute and Chronic Spinal Cord Injury: A Scoping Review of Epigenetics and Secondary Health Conditions

Background

Epigenetics studies the impact of environmental and behavioral factors on stable phenotypic changes; however, the state of the science examining epigenomic mechanisms of regulation related to secondary health conditions (SHCs) and neuroepigenetics in chronic spinal cord injury (SCI) remain markedly underdeveloped.

Objective

This scoping review seeks to understand the state of the science in epigenetics and secondary complications following SCI.

Methods

A literature search was conducted, yielding 277 articles. The inclusion criteria were articles (1) investigating SCI and (2) examining epigenetic regulation as part of the study methodology. A total of 23 articles were selected for final inclusion.

Results

Of the 23 articles 52% focused on histone modification, while 26% focused on DNA methylation. One study had a human sample, while the majority sampled rats and mice. Primarily, studies examined regeneration, with only one study looking at clinically relevant SHC, such as neuropathic pain.

Discussion

The findings of this scoping review offer exciting insights into epigenetic and neuroepigenetic application in SCI research. Several key genes, proteins, and pathways emerged across studies, suggesting the critical role of epigenetic regulation in biological processes. This review reinforced the dearth of studies that leverage epigenetic methods to identify prognostic biomarkers in SHCs. Preclinical models of SCI were genotypically and phenotypically similar, which is not reflective of the heterogeneity found in the clinical population of persons with SCI. There is a need to develop better preclinical models and more studies that examine the role of genomics and epigenomics in understanding the diverse health outcomes associated with traumatic SCI.

The RNA binding protein HuR promotes neuronal apoptosis in rats with spinal cord injury via the HDAC1/RAD21 axis

The current research aims to study the regulation of the RNA binding protein HuR on neuronal apoptosis during spinal cord injury (SCI) and its underlying mechanism. SCI rat models were injected with HuR shRNA and/or pcDNA3.1-RAD21, followed by the evaluation of motor function, the degree of SCI, the expression of HuR and RAD21, and neuronal-like apoptosis. The co-localization of HuR-RAD21, RAD21-NeuN, and NeuN-cleaved caspase 3 was measured by immunofluorescence. Additionally, targeting relationships among HuR, HDAC1, and RAD21 were verified by chromatin immunoprecipitation and RNA immunoprecipitation. After transfection, apoptosis of PC12 cells was tested by flow cytometry. Results showed that silencing HuR or up-regulating RAD21 could alleviate SCI and reduce neuronal apoptosis. HuR could combine HDAC1 mRNA, and HDAC1 combined the promoter of RAD21. Further experiments revealed that HuR enhanced HDAC1 expression and reduced RAD21 promoter region acetylation. Overexpression of RAD21 reversed the enhancement in apoptosis of PC12 cells caused by overexpression of HuR. The injection of HuR shRNA in tail vein of SCI rats increased basso, beattie, and bresnahan score, relieved SCI, reduced HuR and HDAC1 expression, elevated RAD21 expression, and decreased neuronal-like apoptosis. However, this result was reversed by co-injection of pcDNA3.1-HDAC1. In conclusion, down-regulation of HuR alleviated SCI and neuronal apoptosis in rats by suppressing HDAC1 expression and promoting RAD21 expression.

Homeodomain Interacting Protein Kinase 2-Modified Rat Spinal Astrocytes Affect Neurofunctional Recovery After Spinal Cord Injury

BACKGROUND

Spinal cord injury (SCI) is regarded as an acute neurological disorder, and astrocytes play a role in the progression of SCI.

OBJECTIVE

Herein, we investigated the roles of homeodomain-interacting protein kinase 2 (HIPK2)- modified rat spinal astrocytes in neurofunctional recovery after SCI.

METHODS

Rat spinal astrocytes were cultured, isolated, and then identified through microscopic observation and immunofluorescence staining. Astrocytes were infected with the adenovirus vector overexpressing HIPK2 for modification, and proliferation and apoptosis of astrocytes were examined using Cell Counting Kit-8 method and flow cytometry. SCI rat models were established and treated with astrocytes or HIPK2-modified astrocytes. Subsequently, rat motor ability was analyzed via the Basso-Beattie-Bresnahan (BBB) scoring and inclined-plane test, and the damage to spinal cord tissues and neuronal survival were observed via Hematoxylin-eosin staining and Nissl staining. The levels of HIPK2, brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and nuclear factor erythroid 2- related transcription factor 2 (Nrf2)/antioxidant response element (ARE) pathway-related proteins were detected.

RESULTS

Rat spinal astrocytes were harvested successfully. HIPK2 overexpression accelerated the proliferation and repressed the apoptosis of rat spinal astrocytes. Rat spinal astrocytes treatment increased BBB points and the maximum angle at which SCI rats remained stable, ameliorated damage to spinal cord tissues, increased the number of neurons, and attenuated neural damage and inflammation, while the treatment of HIPK2-modified rat spinal astrocytes imparted more pronounced effects to the neurofunctional recovery of SCI rats. Meanwhile, HIPK2-modified rat spinal astrocytes further activated the Nrf2/ARE pathway.

CONCLUSION

HIPK2-modified rat spinal astrocytes facilitated neurofunctional recovery and activated the Nrf2/ARE pathway after SCI.

Euxanthone inhibits traumatic spinal cord injury via anti-oxidative stress and suppression of p38 and PI3K/Akt signaling pathway in a rat model

BACKGROUND

Owing to neurite promoting, antioxidant and anti-inflammatory effects of Euxanthone (Eux), the investigation was aimed to probe the neuroprotective efficacy of Eux against traumatic spinal cord injury (t-SCI) in rats and whether Eux can improve neuropathic function in t-SCI.

METHOD

Sprague-Dawley (SD) rats were randomized in - Sham, t-SCI, Eux30, and Eux60 (t-SCI + 30 and 60 mg/kg respectively). Animals with compression force-induced t-SCI were subjected to estimation of locomotor functions. Spinal cord water content and Evans blue (EB) effusion were determined for quantifying edema and intactness of the spinal cord. Oxidative stress and immunochemical markers were quantified by ELISA and western blotting.

RESULTS

Findings revealed that Eux60 group animals had greater Basso, Beattie, and Bresnahan (BBB) and (incline plane test) IPT score indicating improved locomotor functions. There was a reduction in the spinal edema and water content after Eux treatment, together with lowering of oxidative stress markers. The expression of IL-6, IL-12, IL-1β, caspase-3, RANKL, TLR4, NF-κB, p-38, PI3K, and Akt in spinal cord tissues of t-SCI-induced rats was lowered after Eux treatment.

CONCLUSION

Overall, the investigation advocates that Eux attenuates t-SCI and associated inflammation, oxidative damage, and resulting apoptosis via modulation of TLR4/NF-κB/p38 and PI3K/Akt signaling cascade.

Multimodal treatment for spinal cord injury: a sword of neuroregeneration upon neuromodulation

Spinal cord injury is linked to the interruption of neural pathways, which results in irreversible neural dysfunction. Neural repair and neuroregeneration are critical goals and issues for rehabilitation in spinal cord injury, which require neural stem cell repair and multimodal neuromodulation techniques involving personalized rehabilitation strategies. Besides the involvement of endogenous stem cells in neurogenesis and neural repair, exogenous neural stem cell transplantation is an emerging effective method for repairing and replacing damaged tissues in central nervous system diseases. However, to ensure that endogenous or exogenous neural stem cells truly participate in neural repair following spinal cord injury, appropriate interventional measures (e.g., neuromodulation) should be adopted. Neuromodulation techniques, such as noninvasive magnetic stimulation and electrical stimulation, have been safely applied in many neuropsychiatric diseases. There is increasing evidence to suggest that neuromagnetic/electrical modulation promotes neuroregeneration and neural repair by affecting signaling in the nervous system; namely, by exciting, inhibiting, or regulating neuronal and neural network activities to improve motor function and motor learning following spinal cord injury. Several studies have indicated that fine motor skill rehabilitation training makes use of residual nerve fibers for collateral growth, encourages the formation of new synaptic connections to promote neural plasticity, and improves motor function recovery in patients with spinal cord injury. With the development of biomaterial technology and biomechanical engineering, several emerging treatments have been developed, such as robots, brain-computer interfaces, and nanomaterials. These treatments have the potential to help millions of patients suffering from motor dysfunction caused by spinal cord injury. However, large-scale clinical trials need to be conducted to validate their efficacy. This review evaluated the efficacy of neural stem cells and magnetic or electrical stimulation combined with rehabilitation training and intelligent therapies for spinal cord injury according to existing evidence, to build up a multimodal treatment strategy of spinal cord injury to enhance nerve repair and regeneration.

Reactive astrocytes increase expression of proNGF in the mouse model of contused spinal cord injury

Astrocytes are major glial cells critically in maintaining stability of the central nervous system and functional activation of astrocytes occurs rapidly in various diseased or traumatic events. We are interested in functional changes of astrocytes during the spinal cord injury, and studied expression of nerve growth factor (NGF) in activated astrocytes by mouse model of contused spinal cord injury and cell culture experiment. It revealed that the spinal cord injury resulted in apparent activation of astrocytes and microglial cells and decreased BMS scores. A larger number of astrocytes showed immunoreactivity to proNGF in the injured spinal cord areas, and proNGF expression increased and remained high level at 7 to 14dpi, which was coincided with upregulation of glial fibrillary acidic protein. The proNGF was clearly localized in both exosome-like vesicles and cytoplasm of astrocytes in culture. Electron microscopy confirmed exosome-like vesicles with proNGF-immunoreactivity in diameter sizes of 50-100 nm. Finally, cell culture with lipopolysaccharide (LPS) experiment indicated increasing expression and release of proNGF in the astrocytes with LPS exposure. This study demonstrated that reactive astrocytes increased proNGF expression after spinal cord injury, also suggesting involvement of exosome-like proNGF transport or release in triggering neuronal apoptosis and aggravating progression of spinal cord injury.

Pre-Injection of Small Interfering RNA (siRNA) Promotes c-Jun Gene Silencing and Decreases the Survival Rate of Axotomy-Injured Spinal Motoneurons in Adult Mice

Brachial plexus injury is a common clinical peripheral nerve trauma. A series of genes in motoneurons were activated in the corresponding segments of the spinal cord after brachial plexus roots axotomy. The spatial and temporal expression of these genes directly affects the speed of motoneuron axon regeneration and precise target organ reinnervation. In a previous study, we observed the overexpression of c-Jun in motoneurons of the spinal cord ventral horn after brachial plexus injury in rats. However, the relevance of c-Jun expression with respect to the fate of axotomy-induced branchial plexus injury in adult mice remains unknown. In the present study, we explored the function of c-Jun in motoneuron recovery after axotomy. We pre-injected small interfering RNA (siRNA) to knockdown c-Jun expression in mice and examined the effects of the overexpression of c-Jun in motoneurons after the axotomy of the brachial plexus in vivo. Axotomy induced c-Jun overexpression in the ventral horn motoneurons of adult mice from 3 to 14 days after injury. In addition, the pre-injection of siRNA transiently inhibited c-Jun expression and decreased the survival rate of axotomy-injured motoneurons. These findings indicate that the axotomy-induced overexpression of c-Jun plays an important role in the survival of ventral horn motoneurons in adult mice. In addition, the pre-injection of c-Jun siRNA through the brachial plexus stem effectively adjusts c-Jun gene expression at the ipsilateral side.

Elucidation of Gene Expression Patterns in the Brain after Spinal Cord Injury

Spinal cord injury (SCI) is a devastating neurological disease. The pathophysiological mechanisms of SCI have been reported to be relevant to central nervous system injury such as brain injury. In this study, gene expression of the brain after SCI was elucidated using transcriptome analysis to characterize the temporal changes in global gene expression patterns in a SCI mouse model. Subjects were randomly classified into 3 groups: sham control, acute (3 h post-injury), and subacute (2 wk post-injury) groups. We sought to confirm the genes differentially expressed between post-injured groups and sham control group. Therefore, we performed transcriptome analysis to investigate the enriched pathways associated with pathophysiology of the brain after SCI using Database for Annotation Visualization, and Integrated Discovery (DAVID), which yielded Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Following enriched pathways were found in the brain: oxidative phosphorylation pathway; inflammatory response pathways—cytokine–cytokine receptor interaction and chemokine signaling pathway; and endoplasmic reticulum (ER) stress-related pathways—antigen processing and presentation and mitogen-activated protein kinase signaling pathway. Oxidative phosphorylation pathway was identified at acute phase, while inflammation response and ER stress-related pathways were identified at subacute phase. Since the following pathways—oxidative phosphorylation pathway, inflammatory response pathways, and ER stress-related pathways—have been well known in the SCI, we suggested a link between SCI and brain injury. These mechanisms provide valuable reference data for better understanding pathophysiological processes in the brain after SCI.

Glial fibrillary acidic protein levels are associated with global histone H4 acetylation after spinal cord injury in rats

Emerging evidence has suggested global histone H4 acetylation status plays an important role in neural plasticity. For instance, the imbalance of this epigenetic marker has been hypothesized as a key factor for the development and progression of several neurological diseases. Likewise, astrocytic reactivity - a well-known process that markedly influences the tissue remodeling after a central nervous system injury - is crucial for tissue remodeling after spinal cord injury (SCI). However, the linkage between the above-mentioned mechanisms after SCI remains poorly understood. We sought to investigate the relation between both glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein B (S100B) (astrocytic reactivity classical markers) and global histone H4 acetylation levels. Sixty-one male Wistar rats (aged ~3 months) were divided into the following groups: sham; 6 hours post-SCI; 24 hours post-SCI; 48 hours post-SCI; 72 hours post-SCI; and 7 days post-SCI. The results suggested that GFAP, but not S100B was associated with global histone H4 acetylation levels. Moreover, global histone H4 acetylation levels exhibited a complex pattern after SCI, encompassing at least three clearly defined phases ( first phase: no changes in the 6, 24 and 48 hours post-SCI groups; second phase: increased levels in the 72 hours post-SCI group; and a third phase: return to levels similar to control in the 7 days post-SCI group). Overall, these findings suggest global H4 acetylation levels exhibit distinct patterns of expression during the first week post-SCI, which may be associated with GFAP levels in the perilesional tissue. Current data encourage studies using H4 acetylation as a possible biomarker for tissue remodeling after spinal cord injury.

Gambogic acid inhibits spinal cord injury and inflammation through suppressing the p38 and Akt signaling pathways

Gamboge is the dry resin secreted by Garcinia hanburyi Hook.f, with the function of promoting blood circulation, detoxification, hemostasis and killing insects, used for the treatment of cancer, brain edema and other diseases. Gambogic acid is the main effective constituent of Gamboge. The present study investigated the protective effects of gambogic acid on spinal cord injury (SCI) and its anti‑inflammatory mechanism in an SCI model in vivo. Basso, Beattie and Bresnahan (BBB) testing was used to detect the protective effects of gambogic acid on nerve function of SCI rats. The water content of the spinal cord was used to analyze the protective effects of gambogic acid on the damage of SCI. Treatment with gambogic acid effectively improved BBB scores and inhibited water content of the spinal cord in SCI rats. Also, gambogic acid significantly reduced inflammatory cytokines levels of [tumor necrosis factor‑α, interleukin (IL)‑6, IL‑12 and IL‑1β] and oxidative stress (malondialdehyde, superoxide dismutase, glutathione and glutathione‑peroxidase) factors, and suppressed receptor activator of nuclear factor κB ligand, phosphorylated p38 protein expression and toll‑like receptor 4/nuclear factor‑κB pathway activation, and increased phosphatidylinositol 3‑kinase/protein kinase B (Akt) pathway activation in SCI rats. These results provide evidence that gambogic acid inhibits SCI and inflammation through suppressing the p38 and Akt signaling pathways.

Urinary Levels of IL-1β and GDNF in Preterm Neonates as Potential Biomarkers of Motor Development: A Prospective Study

Objectives. To evaluate the association between inflammatory biomarkers, neurotrophic factors, birth conditions, and the presence of motor development abnormalities in preterm neonates. Methods. Plasma and urinary levels of cytokines (IL-1β, IL-6, IL-10, TNF, and IL-12p70), chemokines (CXCL8/IL-8, CCL2/MCP-1, CCL5/RANTES, CXCL10/IP-10, and CXCL9/MIG), and neurotrophic factors (BDNF and GDNF) were evaluated in 40 preterm neonates born between 28 and 32 incomplete weeks of gestation, at four distinct time points: at birth (umbilical cord blood) (T0), at 48 (T1), at 72 hours (T2), and at 3 weeks after birth (T3). Biomarkers levels were compared between different time points and then associated with Test of Infant Motor Performance (TIMP) percentiles. Results. Maternal age, plasma, and urinary concentrations of inflammatory molecules and neurotrophic factors were significantly different between groups with normal versus lower than expected motor development. Higher levels of GDNF were found in the group with lower than expected motor development, while IL-1β and CXCL8/IL-8 values were higher in the group with typical motor development. Conclusion. Measurements of cytokines and neurotrophic factors in spot urine may be useful in the follow-up of motor development in preterm neonates.