Exercise Ameliorates Spinal Cord Injury by Changing DNA Methylation

Repeated epidural delivery of Shinbaro2: effects on neural recovery, inflammation, and pain modulation in a rat model of lumbar spinal stenosis

The choice of treatment for lumbar spinal stenosis (LSS) depends on symptom severity. When severe motor issues with urinary dysfunction are not present, conservative treatment is often considered to be the priority. One such conservative treatment is epidural injection, which is effective in alleviating inflammation and the pain caused by LSS-affected nerves. In this study, Shinbaro2 (Sh2), pharmacopuncture using natural herbal medicines for patients with disc diseases, is introduced as an epidural to treat LSS in a rat model. The treatment of primary sensory neurons from the rats' dorsal root ganglion (DRG) neurons with Sh2 at various concentrations (0.5, 1, and 2 mg/mL) was found to be safe and non-toxic. Furthermore, it remarkably stimulated axonal outgrowth even under H2O2-treated conditions, indicating its potential for stimulating nerve regeneration. When LSS rats received epidural injections of two different concentrations of Sh2 (1 and 2 mg/kg) once daily for 4 weeks, a significant reduction was seen in ED1+ macrophages surrounding the silicone block used for LSS induction. Moreover, epidural injection of Sh2 in the DRG led to a significant suppression of pain-related factors. Notably, Sh2 treatment resulted in improved locomotor recovery, as evaluated by the Basso, Beattie, and Bresnahan scale and the horizontal ladder test. Additionally, hind paw hypersensitivity, assessed using the Von Frey test, was reduced, and normal gait was restored. Our findings demonstrate that epidural Sh2 injection not only reduced inflammation but also improved locomotor function and pain in LSS model rats. Thus, Sh2 delivery via epidural injection has potential as an effective treatment option for LSS.

Exoskeleton-Assisted Rehabilitation and Neuroplasticity in Spinal Cord Injury

Spinal cord injury (SCI) results in neurological deficits below the level of injury, causing motor dysfunction and various severe multisystem complications. Rehabilitative training plays a crucial role in the recovery of individuals with SCI, and exoskeleton serves as an emerging and promising tool for rehabilitation, especially in promoting neuroplasticity and alleviating SCI-related complications. This article reviews the classifications and research progresses of medical exoskeletons designed for SCI patients and describes their performances in practical application separately. Meanwhile, we discuss their mechanisms for enhancing neuroplasticity and functional remodeling, as well as their palliative impacts on secondary complications. The potential trends in exoskeleton design are raised according to current progress and requirements on SCI rehabilitation.

The effect of early mobilisation (< 14 days) on pathophysiological and functional outcomes in animals with induced spinal cord injury: a systematic review with meta-analysis

INTRODUCTION

The optimum time to mobilise (standing, walking) following spinal cord injury (SCI) is unknown but may have implications for patient outcomes. There are no high-quality experimental studies that examine this issue, with a paucity of guidance for clinicians. Pre-clinical studies lead research in this field and can contribute to knowledge and support future clinical practice.

OBJECTIVE

to evaluate the effect of early compared to no mobilisation on pathophysiological and functional outcomes in animals with induced SCI.

METHODS

A systematic review with meta-analysis was conducted by searching pre-clinical literature in MEDLINE (PubMed), Embase (Ovid), Web of Science, OpenGrey, and EThOS (June 2023). Studies were included of any research method giving numerical results comparing pathophysiological and functional outcomes in rats and mice mobilised within 14-days of induced SCI to those that did not mobilise. Data were synthesised using random-effects meta-analyses. The quality of the evidence was assessed using the CAMARADES checklist. The certainty of findings was reported using the GRADE approach. This study is registered on PROSPERO (CRD42023437494).

RESULTS

Seventeen studies met the inclusion criteria. Outcomes found that Brain Derived Neurotrophic Factor levels were greater in those that initiated mobilisation within 14-days of SCI compared to the groups that did not. Mobilisation initiated within 14-days of SCI was also associated with statistically significant functional gains: (Basso, Beattie and Bresnahan locomotor rating score (BBB) = 2.13(0-21), CI 1.43, 2.84, Ladder Rung Walking Task = - 12.38(0-100), CI 20.01, - 4.76). Meta-analysis identified the greatest functional gains when mobilisation was initiated within 3 days of SCI (BBB = 3.00, CI 2.31-3.69, p < 0.001), or when delivered at low intensity (BBB = 2.88, CI 2.03-3.70, p < 0.001). Confidence in the findings from this review was low to moderate due to the risk of bias and mixed methodological quality.

CONCLUSION

Mobilisation instigated within 14-days of injury, may be an effective way of improving functional outcomes in animal models following SCI, with delays potentially detrimental to recovery. Outcomes from this study support further research in this field to guide future clinical practice.

Curcumin can improve spinal cord injury by inhibiting DNA methylation

Spinal cord injury (SCI) is a serious central nervous system disease. Traumatic SCI often causes persistent neurological deficits below the injury level. Epigenetic changes occur after SCI. Studies have shown DNA methylation to be a key player in nerve regeneration and remodeling, and in regulating some pathophysiological characteristics of SCI. Curcumin is a natural polyphenol from turmeric. It has anti-inflammatory, antioxidant, and neuroprotective effects, and can mitigate the cell and tissue damage caused by SCI. This report analyzed the specific functions of DNA methylation in central nervous system diseases, especially traumatic brain injury and SCI. DNA methylation can regulate the level of gene expressions in the central nervous system. Therefore, pharmacological interventions regulating DNA methylation may be promising for SCI.

Aerobic exercise alters DNA hydroxymethylation levels in an experimental rodent model of temporal lobe epilepsy

The therapeutic potential of aerobic exercise in mitigating seizures and cognitive issues in temporal lobe epilepsy (TLE) is recognized, yet the underlying mechanisms are not well understood. Using a rodent TLE model induced by Kainic acid (KA), we investigated the impact of a single bout of exercise (i.e., acute) or 4 weeks of aerobic exercise (i.e., chronic). Blood was processed for epilepsy-associated serum markers, and DNA methylation (DNAme), and hippocampal area CA3 was assessed for gene expression levels for DNAme-associated enzymes. While acute aerobic exercise did not alter serum Brain-Derived Neurotrophic Factor (BDNF) or Interleukin-6 (IL-6), chronic exercise resulted in an exercise-specific decrease in serum BDNF and an increase in serum IL-6 levels in epileptic rats. Additionally, whole blood DNAme levels, specifically 5-hydroxymethylcytosine (5-hmC), decreased in epileptic animals following chronic exercise. Hippocampal CA3 5-hmC levels and ten-eleven translocation protein (TET1) expression mirrored these changes. Furthermore, immunohistochemistry analysis revealed that most 5-hmC changes in response to chronic exercise were neuron-specific within area CA3 of the hippocampus. Together, these findings suggest that DNAme mechanisms in the rodent model of TLE are responsive to chronic aerobic exercise, with emphasis on neuronal 5-hmC DNAme in the epileptic hippocampus.

Inhibition of UTX/KDM6A improves recovery of spinal cord injury by attenuating BSCB permeability and macrophage infiltration through the MLCK/p-MLC pathway

Spinal cord injury (SCI) can prompt an immediate disruption to the blood-spinal cord barrier (BSCB). Restoring the integrity of this barrier is vital for the recovery of neurological function post-SCI. The UTX protein, a histone demethylase, has been shown in previous research to promote vascular regeneration and neurological recovery in mice with SCI. However, it is unclear whether UTX knockout could facilitate the recovery of the BSCB by reducing its permeability. In this study, we systematically studied BSCB disruption and permeability at different time points after SCI and found that conditional UTX deletion in endothelial cells (ECs) can reduce BSCB permeability, decrease inflammatory cell infiltration and ROS production, and improve neurological function recovery after SCI. Subsequently, we used RNA sequencing and ChIP-qPCR to confirm that conditional UTX knockout in ECs can down-regulate expression of myosin light chain kinase (MLCK), which specifically mediates myosin light chain (MLC) phosphorylation and is involved in actin contraction, cell retraction, and tight junctions (TJs) protein integrity. Moreover, we found that MLCK overexpression can increase the ratio of p-MLC/MLC, further break TJs, and exacerbate BSCB deterioration. Overall, our findings indicate that UTX knockout could inhibit the MLCK/p-MLC pathway, resulting in decreased BSCB permeability, and ultimately promoting neurological recovery in mice. These results suggest that UTX is a promising new target for treating SCI.

Reduced non-CpG methylation is a potential epigenetic target after spinal cord injury

DNA methylation is a critical epigenetic regulator in the occurrence and development of diseases and is closely related to various functional responses in relation to spinal cord injury. To investigate the role of DNA methylation in spinal cord injury, we constructed a library with reduced-representation bisulfite sequencing data obtained at various time points (day 0-42) after spinal cord injury in mice. Global DNA methylation levels, specifically non-CpG (CHG and CHH) methylation levels, decreased modestly following spinal cord injury. Stages post-spinal cord injury were classified as early (day 0-3), intermediate (day 7-14), and late (day 28-42) based on similarity and hierarchical clustering of global DNA methylation patterns. The non-CpG methylation level, which included CHG and CHH methylation levels, was markedly reduced despite accounting for a minor proportion of total methylation abundance. At multiple genomic sites, including the 5' untranslated regions, promoter, exon, intron, and 3' untranslated regions, the non-CpG methylation level was markedly decreased following spinal cord injury, whereas the CpG methylation level remained unchanged at these locations. Approximately one-half of the differentially methylated regions were located in intergenic areas; the other differentially methylated regions in both CpG and non-CpG regions were clustered in intron regions, where the DNA methylation level was highest. The function of genes associated with differentially methylated regions in promoter regions was also investigated. From Gene Ontology analysis results, DNA methylation was implicated in a number of essential functional responses to spinal cord injury, including neuronal synaptic connection creation and axon regeneration. Notably, neither CpG methylation nor non-CpG methylation was implicated in the functional response of glial or inflammatory cells. In summary, our work elucidated the dynamic pattern of DNA methylation in the spinal cord following injury and identified reduced non-CpG methylation as an epigenetic target after spinal cord injury in mice.

The role of ferroptosis in intervertebral disc degeneration

Nucleus pulposus, annulus fibrosus, and cartilage endplate constitute an avascular intervertebral disc (IVD), which is crucial for spinal and intervertebral joint mobility. As one of the most widespread health issues worldwide, intervertebral disc degeneration (IVDD) is recognized as a key contributor to back and neck discomfort. A number of degenerative disorders have a strong correlation with ferroptosis, a recently identified novel regulated cell death (RCD) characterized by an iron-dependent mechanism and a buildup of lipid reactive oxygen species (ROS). There is growing interest in the part ferroptosis plays in IVDD pathophysiology. Inhibiting ferroptosis has been shown to control IVDD development. Several studies have demonstrated that in TBHP-induced oxidative stress models, changes in ferroptosis marker protein levels and increased lipid peroxidation lead to the degeneration of intervertebral disc cells, which subsequently aggravates IVDD. Similarly, IVDD is significantly relieved with the use of ferroptosis inhibitors. The purpose of this review was threefold: 1) to discuss the occurrence of ferroptosis in IVDD; 2) to understand the mechanism of ferroptosis and its role in IVDD pathophysiology; and 3) to investigate the feasibility and prospect of ferroptosis in IVDD treatment.

The Influence of Exercise on Oxidative Stress after Spinal Cord Injury: A Narrative Review

Spinal cord injury (SCI) is an irreversible disease resulting in partial or total loss of sensory and motor function. The pathophysiology of SCI is characterized by an initial primary injury phase followed by a secondary phase in which reactive oxygen species (ROSs) and associated oxidative stress play hallmark roles. Physical exercise is an indispensable means of promoting psychophysical well-being and improving quality of life. It positively influences the neuromuscular, cardiovascular, respiratory, and immune systems. Moreover, exercise may provide a mechanism to regulate the variation and equilibrium between pro-oxidants and antioxidants. After a brief overview of spinal cord anatomy and the different types of spinal cord injury, the purpose of this review is to investigate the evidence regarding the effect of exercise on oxidative stress among individuals with SCI.

Motor rehabilitation as a therapeutic tool for spinal cord injury: New perspectives in immunomodulation

Traumatic spinal cord injury (SCI) is a devastating condition that significantly impacts motor, sensory and autonomic function in patients. Despite advances in therapeutic approaches, there is still no curative therapy currently available. Neuroinflammation is a persisting event of the secondary injury phase of SCI that affects functional recovery, and modulation of the inflammatory response towards a beneficial anti-inflammatory state can improve recovery in preclinical SCI models. In human SCI patients, rehabilitative exercise, or motor rehabilitation as we will refer to it from here on out, remains the cornerstone of treatment to increase functional capacity and prevent secondary health implications. Motor rehabilitation is known to have anti-inflammatory effects; however, current literature is lacking in the description of the effect of motor rehabilitation on inflammation in the context of SCI. Understanding the effect on different inflammatory markers after SCI should enable the optimization of motor rehabilitation as a therapeutic regime. This review extensively describes the effect of motor rehabilitation on selected inflammatory mediators in both preclinical and human SCI studies. Additionally, we summarize how the type, duration, and intensity of motor rehabilitation can affect the inflammatory response after SCI. In doing so, we introduce a new perspective on how motor rehabilitation can be optimized as an immunomodulatory therapy to improve patient outcome after SCI.

Purified regenerating retinal neurons reveal regulatory role of DNA methylation-mediated Na+/K+-ATPase in murine axon regeneration

While embryonic mammalian central nervous system (CNS) axons readily grow and differentiate, only a minority of fully differentiated mature CNS neurons are able to regenerate injured axons, leading to stunted functional recovery after injury and disease. To delineate DNA methylation changes specifically associated with axon regeneration, we used a Fluorescent-Activated Cell Sorting (FACS)-based methodology in a rat optic nerve transection model to segregate the injured retinal ganglion cells (RGCs) into regenerating and non-regenerating cell populations. Whole-genome DNA methylation profiling of these purified neurons revealed genes and pathways linked to mammalian RGC regeneration. Moreover, whole-methylome sequencing of purified uninjured adult and embryonic RGCs identified embryonic molecular profiles reactivated after injury in mature neurons, and others that correlate specifically with embryonic or adult axon growth, but not both. The results highlight the contribution to both embryonic growth and adult axon regeneration of subunits encoding the Na⁺/K⁺-ATPase. In turn, both biochemical and genetic inhibition of the Na⁺/K⁺-ATPase pump significantly reduced RGC axon regeneration. These data provide critical molecular insights into mammalian CNS axon regeneration, pinpoint the Na⁺/K⁺-ATPase as a key regulator of regeneration of injured mature CNS axons, and suggest that successful regeneration requires, in part, reactivation of embryonic signals.

Demethylation of miR-299-5p by aerobic exercise relieves insulin resistance in the vascular endothelium by repressing resistin

AIMS

Insulin resistance (IR) is a critical marker underlying type 2 diabetes mellitus (T2DM). Exercise is reported to prevent IR, yet the mechanism of which is complicated and largely unknown. Here, the study aimed to ascertain whether and how aerobic exercise mediates IR in T2DM.

METHODS

An in vivo model of high-fat diet (HFD)-induced IR and an in vitro model of high-glucose-induced IR were constructed.

RESULTS

Aerobic exercise training in mice led to attenuation of IR in the vascular endothelium. microRNA-299-5p (miR-299-5p) expression was deficient in T2MD, which could be restored by aerobic exercise through modulating the DNA methylation modification enzymes. The expression of miR-299-5p enhanced by aerobic exercise consequently resulted in ameliorating the IR in vivo. Furthermore, increased levels of nitric oxide (NO), reduced levels of Angiotensin II (Ang II), vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) in response to miR-299-5p elevation suggested the anti-IR role of miR-299-5p in IR-cell model. Dual-luciferase reporter and ChIP assays identified that miR-299-5p could bind to resistin and hence repressed the resistin level.

CONCLUSION

The key observation of the study is that aerobic exercise stimulates miR-299-5p-targeted resistin inhibition through demethylation, which underlies the mechanism of reducing IR.

Molecular mechanisms of exercise contributing to tissue regeneration

Physical activity has been known as an essential element to promote human health for centuries. Thus, exercise intervention is encouraged to battle against sedentary lifestyle. Recent rapid advances in molecular biotechnology have demonstrated that both endurance and resistance exercise training, two traditional types of exercise, trigger a series of physiological responses, unraveling the mechanisms of exercise regulating on the human body. Therefore, exercise has been expected as a candidate approach of alleviating a wide range of diseases, such as metabolic diseases, neurodegenerative disorders, tumors, and cardiovascular diseases. In particular, the capacity of exercise to promote tissue regeneration has attracted the attention of many researchers in recent decades. Since most adult human organs have a weak regenerative capacity, it is currently a key challenge in regenerative medicine to improve the efficiency of tissue regeneration. As research progresses, exercise-induced tissue regeneration seems to provide a novel approach for fighting against injury or senescence, establishing strong theoretical basis for more and more "exercise mimetics." These drugs are acting as the pharmaceutical alternatives of those individuals who cannot experience the benefits of exercise. Here, we comprehensively provide a description of the benefits of exercise on tissue regeneration in diverse organs, mainly focusing on musculoskeletal system, cardiovascular system, and nervous system. We also discuss the underlying molecular mechanisms associated with the regenerative effects of exercise and emerging therapeutic exercise mimetics for regeneration, as well as the associated opportunities and challenges. We aim to describe an integrated perspective on the current advances of distinct physiological mechanisms associated with exercise-induced tissue regeneration on various organs and facilitate the development of drugs that mimics the benefits of exercise.