Qki5 safeguards spinal motor neuron function by defining the motor neuron-specific transcriptome via pre-mRNA processing.

Many RNA-binding proteins (RBPs) are linked to the dysregulation of RNA metabolism in motor neuron diseases (MNDs). However, the molecular mechanisms underlying MN vulnerability have yet to be elucidated. Here, we found that such an RBP, Quaking5 (Qki5), contributes to formation of the MN-specific transcriptome profile, termed "MN-ness," through the posttranscriptional network and maintenance of the mature MNs. Immunohistochemical analysis and single-cell RNA sequencing (scRNA-seq) revealed that Qki5 is predominantly expressed in MNs, but not in other neuronal populations of the spinal cord. Furthermore, comprehensive RNA sequencing (RNA-seq) analyses revealed that Qki5-dependent RNA regulation plays a pivotal role in generating the MN-specific transcriptome through pre-messenger ribonucleic acid (mRNA) splicing for the synapse-related molecules and c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) signaling pathways. Indeed, MN-specific ablation of the Qki5 caused neurodegeneration in postnatal mice and loss of Qki5 function resulted in the aberrant activation of stress-responsive JNK/SAPK pathway both in vitro and in vivo. These data suggested that Qki5 plays a crucial biological role in RNA regulation and safeguarding of MNs and might be associated with pathogenesis of MNDs.

Biomechanical study of spinal cord and nerve root in idiopathic scoliosis: based on finite element analysis.

BACKGROUND: Current research lacks comprehensive investigation into the biomechanical changes in the spinal cord and nerve roots during scoliosis correction. This study employs finite element analysis to extensively explore these biomechanical variations across different Cobb angles, providing valuable insights for clinical treatment. METHODS: A personalized finite element model, incorporating vertebrae, ligaments, spinal cord, and nerve roots, was constructed using engineering software. Forces and displacements were applied to achieve Cobb angle improvements, designating T1/2-T4/5 as the upper segment, T5/6-T8/9 as the middle segment, and T9/10-L1/2 as the lower segment. Simulations under traction, pushing, and traction + torsion conditions were conducted, and biomechanical changes in each spinal cord segment and nerve roots were analyzed. RESULTS: Throughout the scoliosis correction process, the middle spinal cord segment consistently exhibited a risk of injury under various conditions and displacements. The lower spinal cord segment showed no significant injury changes under traction + torsion conditions. In the early correction phase, the upper spinal cord segment demonstrated a risk of injury under all conditions, and the lower spinal cord segment presented a risk of injury under pushing conditions. Traction conditions posed a risk of nerve injury on both sides in the middle and lower segments. Under pushing conditions, there was a risk of nerve injury on both sides in all segments. Traction + torsion conditions implicated a risk of injury to the right nerves in the upper segment, both sides in the middle segment, and the left side in the lower segment. In the later correction stage, there was a risk of injury to the upper spinal cord segment under traction + torsion conditions, the left nerves in the middle segment under traction conditions, and the right nerves in the upper segment under pushing conditions. CONCLUSION: When the correction rate reaches 61-68%, particular attention should be given to the upper-mid spinal cord. Pushing conditions also warrant attention to the lower spinal cord and the nerve roots on both sides of the main thoracic curve. Traction conditions require attention to nerve roots bilaterally in the middle and lower segments, while traction combined with torsion conditions necessitate focus on the right-side nerve roots in the upper segment, both sides in the middle segment, and the left-side nerve roots in the lower segment.

AAV-DJ is superior to AAV9 for targeting brain and spinal cord, and de-targeting liver across multiple delivery routes in mice.

Highly efficient adeno associated viruses (AAVs) targeting the central nervous system (CNS) are needed to deliver safe and effective therapies for inherited neurological disorders. The goal of this study was to compare the organ-specific transduction efficiencies of two AAV capsids across three different delivery routes. We compared AAV9-CBA-fLucYFP to AAV-DJ-CBA-fLucYFP using the following delivery routes in mice: intracerebroventricular (ICV) 1 × 1012 vg/kg, intrathecal (IT) 1 × 1012 vg/kg, and intravenous (IV) 1 × 1013 vg/kg body weight. Our evaluations revealed that following ICV and IT administrations, AAV-DJ demonstrated significantly increased vector genome (vg) uptake throughout the CNS as compared to AAV9. Through the IV route, AAV9 demonstrated significantly increased vg uptake in the CNS. However, significantly fewer vgs were detected in the off-target organs (kidney and liver) following administration of AAV-DJ using the IT and IV delivery routes as compared to AAV9. Distributions of vgs correlate well with transgene transcript levels, luciferase enzyme activities, and immunofluorescence detection of YFP. Overall, between the two vectors, AAV-DJ resulted in better targeting and expression in CNS tissues paired with de-targeting and reduced expression in liver and kidneys. Our findings support further examination of AAV-DJ as a gene therapy capsid for the treatment of neurological disorders.

Fasudil attenuates syncytin-1-mediated activation of microglia and impairments of motor neurons and motor function in mice.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. Syncytin-1 (Syn), an envelope glycoprotein encoded by the env gene of the human endogenous retrovirus-W family, has been resorted to be highly expressed in biopsies from the muscles from ALS patients; however, the specific regulatory role of Syn during ALS progression remains uncovered. In this study, C57BL/6 mice were injected with adeno-associated virus-overexpressing Syn, with or without Fasudil administration. The Syn expression was assessed by quantitative real-time polymerase chain reaction and immunohistochemistry analysis. The histological change of anterior tibial muscles was determined by hematoxylin-eosin staining. Qualitative ultrastructural analysis of electron micrographs obtained from lumbar spinal cords was carried out. Serum inflammatory cytokines were assessed by enzyme linked immunosorbent assay (ELISA) assay and motor function was recorded using Basso, Beattie, and Bresnahan (BBB) scoring, climbing test and treadmill running test. Immunofluorescence and western blot assays were conducted to examine microglial- and motor neurons-related proteins. Syn overexpression significantly caused systemic inflammatory response, muscle tissue lesions, and motor dysfunction in mice. Meanwhile, Syn overexpression promoted the impairment of motor neuron, evidenced by the damaged structure of the neurons and reduced expression of microtubule-associated protein 2, HB9, neuronal nuclei and neuron-specific enolase in Syn-induced mice. In addition, Syn overexpression greatly promoted the expression of CD16/CD32 and inducible nitric oxide synthase (M1 phenotype markers), and reduced the expression of CD206 and arginase 1 (M2 phenotype markers). Importantly, the above changes caused by Syn overexpression were partly abolished by Fasudil administration. This study provides evidence that Syn-activated microglia plays a pivotal role during the progression of ALS.

Neuronal repair after spinal cord injury by in vivo astrocyte reprogramming mediated by the overexpression of NeuroD1 and Neurogenin-2.

BACKGROUND: As a common disabling disease, irreversible neuronal death due to spinal cord injury (SCI) is the root cause of functional impairment; however, the capacity for neuronal regeneration in the developing spinal cord tissue is limited. Therefore, there is an urgent need to investigate how defective neurons can be replenished and functionally integrated by neural regeneration; the reprogramming of intrinsic cells into functional neurons may represent an ideal solution. METHODS: A mouse model of transection SCI was prepared by forceps clamping, and an adeno-associated virus (AAV) carrying the transcription factors NeuroD1 and Neurogenin-2(Ngn2) was injected in situ into the spinal cord to specifically overexpress these transcription factors in astrocytes close to the injury site. 5-bromo-2´-deoxyuridine (BrdU) was subsequently injected intraperitoneally to continuously track cell regeneration, neuroblasts and immature neurons marker expression, neuronal regeneration, and glial scar regeneration. In addition, immunoprotein blotting was used to measure the levels of transforming growth factor-ß (TGF-ß) pathway-related protein expression. We also evaluated motor function, sensory function, and the integrity of the blood-spinal cord barrier(BSCB). RESULTS: The in situ overexpression of NeuroD1 and Ngn2 in the spinal cord was achieved by specific AAV vectors. This intervention led to a significant increase in cell regeneration and the proportion of cells with neuroblasts and immature neurons cell properties at the injury site(p < 0.0001). Immunofluorescence staining identified astrocytes with neuroblasts and immature neurons cell properties at the site of injury while neuronal marker-specific staining revealed an increased number of mature astrocytes at the injury site. Behavioral assessments showed that the intervention did not improve The BMS (Basso mouse scale) score (p = 0.0726) and gait (p > 0.05), although the treated mice had more sensory sensitivity and greater voluntary motor ability in open field than the non-intervention mice. We observed significant repair of the BSCB at the center of the injury site (p < 0.0001) and a significant improvement in glial scar proliferation. Electrophysiological assessments revealed a significant improvement in spinal nerve conduction (p < 0.0001) while immunostaining revealed that the levels of TGF-ß protein at the site of injury in the intervention group were lower than control group (p = 0.0034); in addition, P70 s6 and PP2A related to the TGF-ß pathway showed ascending trend (p = 0.0036, p = 0.0152 respectively). CONCLUSIONS: The in situ overexpression of NeuroD1 and Ngn2 in the spinal cord after spinal cord injury can reprogram astrocytes into neurons and significantly enhance cell regeneration at the injury site. The reprogramming of astrocytes can lead to tissue repair, thus improving the reduced threshold and increasing voluntary movements. This strategy can also improve the integrity of the blood-spinal cord barrier and enhance nerve conduction function. However, the simple reprogramming of astrocytes cannot lead to significant improvements in the striding function of the lower limbs.

Epigenetic Regulation and Molecular Mechanisms of Burn Injury-Induced Nociception in the Spinal Cord of Mice.

Epigenetic mechanisms, including histone post-translational modifications (PTMs), play a critical role in regulating pain perception and the pathophysiology of burn injury. However, the epigenetic regulation and molecular mechanisms underlying burn injury-induced pain remain insufficiently explored. Spinal dynorphinergic (Pdyn) neurons contribute to heat hyperalgesia induced by severe scalding-type burn injury through p-S10H3-dependent signaling. Beyond p-S10H3, burn injury may impact various other histone H3 PTMs. Double immunofluorescent staining and histone H3 protein analyses demonstrated significant hypermethylation at H3K4me1 and H3K4me3 sites and hyperphosphorylation at S10H3 within the spinal cord. By analyzing Pdyn neurons in the spinal dorsal horn, we found evidence of chromatin activation with a significant elevation in p-S10H3 immunoreactivity. We used RNA-seq analysis to compare the effects of burn injury and formalin-induced inflammatory pain on spinal cord transcriptomic profiles. We identified 98 DEGs for burn injury and 86 DEGs for formalin-induced inflammatory pain. A limited number of shared differentially expressed genes (DEGs) suggest distinct central pain processing mechanisms between burn injury and formalin models. KEGG pathway analysis supported this divergence, with burn injury activating Wnt signaling. This study enhances our understanding of burn injury mechanisms and uncovers converging and diverging pathways in pain models with different origins.

Calycosin activates Nrf2/Keap1 signaling to ameliorate hydrogen peroxide-induced spinal cord neuron death and mitochondrial dysfunction.

Oxidative stress is a hallmark of secondary injury of spinal cord injuries. Controlling oxidative stress is crucial for mitigating secondary injury and promoting functional recovery after spinal cord injuries. Calycosin is an O-methylated isoflavone with antioxidant activity. To evaluate the effect of calycosin on spinal cord neurons under oxidative stress and clarify the molecular mechanism underlying the effect, we tested the neuroprotective activity of calycosin in a primary spinal cord neuron culture model. We found that calycosin protected neurons from H2O2-induced neuronal death in a dose-dependent manner. Further experiments revealed that calycosin decreased H2O2-induced mitochondrial fragmentation and mitochondrial membrane potential loss, and subsequently reduced H2O2-triggered release of mitochondrial cytochrome c into the cytoplasm. In addition, calycosin inhibited H2O2-induced reactive oxygen species generation and activation of NF-κB signaling in spinal cord neurons. Furthermore, the expression of several antioxidant enzymes such as HO-1, NQO1, GCLC, GCLM, TrxR1, and Trx1 was significantly promoted by calycosin. More importantly, we revealed that the Nrf2/Keap1 signal is crucial for the effect of calycosin, because calycosin increased the amount of nuclear Nrf2 while decreasing the amount of cytoplasmic Nrf2. Nrf2 knockdown with siRNA transfection abolished the neuroprotective effect of calycosin. Taken together, this study disclosed a novel mechanism by which calycosin combats oxidative stress. Our study thus sheds light on the potential clinical application of calycosin in SCI treatment.

A preliminary study exploring the effects of transcutaneous spinal cord stimulation on spinal excitability and phantom limb pain in people with a transtibial amputation.

Objective. Phantom limb pain (PLP) is debilitating and affects over 70% of people with lower-limb amputation. Other neuropathic pain conditions correspond with increased spinal excitability, which can be measured using reflexes andF-waves. Spinal cord neuromodulation can be used to reduce neuropathic pain in a variety of conditions and may affect spinal excitability, but has not been extensively used for treating PLP. Here, we propose using a non-invasive neuromodulation method, transcutaneous spinal cord stimulation (tSCS), to reduce PLP and modulate spinal excitability after transtibial amputation.Approach. We recruited three participants, two males (5- and 9-years post-amputation, traumatic and alcohol-induced neuropathy) and one female (3 months post-amputation, diabetic neuropathy) for this 5 d study. We measured pain using the McGill Pain Questionnaire (MPQ), visual analog scale (VAS), and pain pressure threshold (PPT) test. We measured spinal reflex and motoneuron excitability using posterior root-muscle (PRM) reflexes andF-waves, respectively. We delivered tSCS for 30 min d-1for 5 d.Main Results. After 5 d of tSCS, MPQ scores decreased by clinically-meaningful amounts for all participants from 34.0 ± 7.0-18.3 ± 6.8; however, there were no clinically-significant decreases in VAS scores. Two participants had increased PPTs across the residual limb (Day 1: 5.4 ± 1.6 lbf; Day 5: 11.4 ± 1.0 lbf).F-waves had normal latencies but small amplitudes. PRM reflexes had high thresholds (59.5 ± 6.1µC) and low amplitudes, suggesting that in PLP, the spinal cord is hypoexcitable. After 5 d of tSCS, reflex thresholds decreased significantly (38.6 ± 12.2µC;p< 0.001).Significance. These preliminary results in this non-placebo-controlled study suggest that, overall, limb amputation and PLP may be associated with reduced spinal excitability and tSCS can increase spinal excitability and reduce PLP.

Intranasal delivery of small extracellular vesicles reduces the progress of amyotrophic lateral sclerosis and the overactivation of complement-coagulation cascade and NF-ĸB signaling in SOD1G93A mice.

Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by progressive motoneuron degeneration, and effective clinical treatments are lacking. In this study, we evaluated whether intranasal delivery of mesenchymal stem cell-derived small extracellular vesicles (sEVs) is a strategy for ALS therapy using SOD1G93A mice. In vivo tracing showed that intranasally-delivered sEVs entered the central nervous system and were extensively taken up by spinal neurons and some microglia. SOD1G93A mice that intranasally received sEV administration showed significant improvements in motor performances and survival time. After sEV administration, pathological changes, including spinal motoneuron death and synaptic denervation, axon demyelination, neuromuscular junction degeneration and electrophysiological defects, and mitochondrial vacuolization were remarkably alleviated. sEV administration attenuated the elevation of proinflammatory cytokines and glial responses. Proteomics and transcriptomics analysis revealed upregulation of the complement and coagulation cascade and NF-ĸB signaling pathway in SOD1G93A mouse spinal cords, which was significantly inhibited by sEV administration. The changes were further confirmed by detecting C1q and NF-ĸB expression using Western blots. In conclusion, intranasal administration of sEVs effectively delays the progression of ALS by inhibiting neuroinflammation and overactivation of the complement and coagulation cascades and NF-ĸB signaling pathway and is a potential option for ALS therapy.

Morphometric analysis of spinal motor neuron degeneration in sporadic amyotrophic lateral sclerosis.

OBJECTIVES: This study aimed to clarify the relationship between 43-kDa TAR DNA-binding protein (TDP-43) pathology and spinal cord anterior horn motor neuron (AHMN) atrophy in sporadic amyotrophic lateral sclerosis (SALS). METHODS: Eight patients with SALS and 12 controls were included in this study. Formalin-fixed specimens of lumbar spinal cord samples were paraffin-embedded and sectioned at the level of the fourth lumbar spinal cord with a 4 µm thickness. Using a microscope, the long diameters of the neurons with nucleoli were measured in spinal AHMNs stained with an anti-SMI-32 antibody. AHMNs were divided into medial and lateral nuclei for statistical analysis. We also used previously reported data to measure the long diameter of AHMNs with initial TDP-43 pathology, in which TDP-43 was present both in the nucleus and cytoplasm. RESULTS: The long diameter of the lumbar spinal AHMNs in patients with SALS was smaller in the medial nucleus (42.54 ± 9.33 µm, n = 24) and the lateral nucleus (49.41 ± 13.86 µm, n = 129) than in controls (medial nucleus: 55.84 ± 13.49 µm, n = 85, p < 0.001; lateral nucleus: 62.39 ± 13.29 µm, n = 756, p < 0.001, Mann-Whitney U test). All 21 motor neurons with initial TDP-43 pathology were in the lateral nucleus, and their long diameter (67.60 ± 18.3 µm, p = 0.352) was not significantly different from that of controls. CONCLUSION: Motor neuron atrophy in SALS does not occur during the initial stages of TDP-43 pathology, and TDP-43 pathology is already advanced in the atrophied motor neurons.

A robust paradigm for studying regeneration after traumatic spinal cord injury in zebrafish.

BACKGROUND: Zebrafish are vertebrates with a high potential of regeneration after injury in the central nervous system. Therefore, they have emerged as a useful model system for studying traumatic spinal cord injuries. NEW METHOD: Using larval zebrafish, we have developed a robust paradigm to model the effects of anterior spinal cord injury, which correspond to the debilitating injuries of the cervical and thoracic regions in humans. Our new paradigm consists of a more anterior injury location compared to previous studies, a modified behavioral assessment using the visual motor response, and a new data analysis code. RESULTS: Our approach enables a spinal cord injury closer to the hindbrain with more functional impact compared to previous studies using a more posterior injury location. Results reported in this work reveal recovery over seven days following spinal cord injury. COMPARING WITH EXISTING METHODS: The present work describes a modified paradigm for the in vivo study of spinal cord regeneration after injury using larval zebrafish, including an anterior injury location, a robust behavioral assessment, and a new data analysis software. CONCLUSIONS: Our findings lay the foundation for applying this paradigm to study the effects of drugs, nutrition, and other treatments to improve the regeneration process.

Neuromodulation with transcranial direct current stimulation contributes to motor function recovery via microglia in spinal cord injury.

Spinal cord injury (SCI) is damage or trauma to the spinal cord, which often results in loss of function, sensation, or mobility below the injury site. Transcranial direct current stimulation (tDCS) is a non-invasive and affordable brain stimulation technique used to modulate neuronal circuits, which changes the morphology and activity of microglia in the cerebral cortex. However, whether similar morphological changes can be observed in the spinal cord remains unclear. Therefore, we evaluated neuronal population activity in layer 5 (L5) of M1 following SCI and investigated whether changes in the activities of L5 neurons affect microglia-axon interactions using C57BL/6J mice. We discovered that L5 of the primary motor cortex (corticospinal neurons) exhibited reduced synchronized activity after SCI that correlates with microglial morphology, which was recovered using tDCS. This indicates that tDCS promotes changes in the morphological properties and recovery of microglia after SCI. Combining immunotherapy with tDCS may be effective in treating SCI.

Mass spectrometry imaging of SOD1 protein-metal complexes in SOD1G93A transgenic mice implicates demetalation with pathology.

Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of motor neurons in the central nervous system (CNS). Mutations in the metalloenzyme SOD1 are associated with inherited forms of ALS and cause a toxic gain of function thought to be mediated by dimer destabilization and misfolding. SOD1 binds two Cu and two Zn ions in its homodimeric form. We have applied native ambient mass spectrometry imaging to visualize the spatial distributions of intact metal-bound SOD1G93A complexes in SOD1G93A transgenic mouse spinal cord and brain sections and evaluated them against disease pathology. The molecular specificity of our approach reveals that metal-deficient SOD1G93A species are abundant in CNS structures correlating with ALS pathology whereas fully metalated SOD1G93A species are homogenously distributed. Monomer abundance did not correlate with pathology. We also show that the dimer-destabilizing post-translational modification, glutathionylation, has limited influence on the spatial distribution of SOD1 dimers.

Inhibiting the NF-κB/DRP1 Axis Affords Neuroprotection after Spinal Cord Injury via Inhibiting Polarization of Pro-Inflammatory Microglia.

BACKGROUND: Spinal cord injury (SCI) is considered a central nervous system (CNS) disorder. Nuclear factor kappa B (NF-κB) regulates inflammatory responses in the CNS and is implicated in SCI pathogenesis. The mechanism(s) through which NF-κB contributes to the neuroinflammation observed during SCI however remains unclear. METHODS: SCI rat models were created using the weight drop method and separated into Sham, SCI and SCI+NF-κB inhibitor groups (n = 6 rats per-group). We used Hematoxylin-Eosin Staining (H&E) and Nissl staining for detecting histological changes in the spinal cord. Basso-Beattie-Bresnahan (BBB) behavioral scores were utilized for assessing functional locomotion recovery. Mouse BV2 microglia were exposed to lipopolysaccharide (LPS) to mimic SCI-induced microglial inflammation in vitro. RESULTS: Inhibition of NF-κB using JSH-23 alleviated inflammation and neuronal injury in SCI rats' spinal cords, leading to improved locomotion recovery (p < 0.05). NF-κB inhibition reduced expression levels of CD86, interleukin-6 (IL-6), IL-1ß, and inducible Nitric Oxide Synthase (iNOS), and improved expression levels of CD206, IL-4, and tissue growth factor-beta (TGF-ß) in both LPS-treated microglia and SCI rats' spinal cords (p < 0.05). Inhibition of NF-κB also effectively suppressed mitochondrial fission, evidenced by the reduced phosphorylation of dynamin-related protein 1 (DRP1) at Ser616 (p < 0.001). CONCLUSION: We show that inhibition of the NF-κB/DRP1 axis prevents mitochondrial fission and suppresses pro-inflammatory microglia polarization, promoting neurological recovery in SCI. Targeting the NF-κB/DRP1 axis therefore represents a novel approach for SCI.

Urinary dysfunction after spinal cord injury: Comparing outcomes after thoracic spinal transection and contusion in the rat.

Spinal cord injury (SCI) above the lumbosacral spinal cord induces loss of voluntary control over micturition. Spinal cord transection (SCT) was the gold standard method to reproduce SCI in rodents, but its translational value is arguable and other experimental SCI methods need to be better investigated, including spinal cord contusion (SCC). At present, it is not fully investigated if urinary impairments arising after transection and contusion are comparable. To explore this, we studied bladder-reflex activity and lower urinary tract (LUT) and spinal cord innervation after SCT and different severities of SCC. Severe-contusion animals presented a longer spinal shock period and the tendency for higher residual volumes, followed by SCT and mild-contusion animals. Urodynamics showed that SCT animals presented higher basal and peak bladder pressures. Immunostaining against growth-associated protein-43 (GAP43) and calcitonin gene-related peptide (CGRP) at the lumbosacral spinal cord demonstrated that afferent sprouting is dependent on the injury model, reflecting the severity of the lesion, with a higher expression in SCT animals. In LUT organs, the expression of GAP43, CGRP cholinergic (vesicular acetylcholine transporter (VAChT)) and noradrenergic (tyrosine hydroxylase (TH)) markers was reduced after SCI in the LUT and lumbosacral cord, but only the lumbosacral expression of VAChT was dependent on the injury model. Overall, our findings demonstrate that changes in LUT innervation and function after contusion and transection are similar but result from distinct neuroplastic processes at the lumbosacral spinal cord. This may impact the development of new therapeutic options for urinary impairment arising after spinal cord insult.

Single-cell analysis of innate spinal cord regeneration identifies intersecting modes of neuronal repair.

Adult zebrafish have an innate ability to recover from severe spinal cord injury. Here, we report a comprehensive single nuclear RNA sequencing atlas that spans 6 weeks of regeneration. We identify cooperative roles for adult neurogenesis and neuronal plasticity during spinal cord repair. Neurogenesis of glutamatergic and GABAergic neurons restores the excitatory/inhibitory balance after injury. In addition, a transient population of injury-responsive neurons (iNeurons) show elevated plasticity 1 week post-injury. We found iNeurons are injury-surviving neurons that acquire a neuroblast-like gene expression signature after injury. CRISPR/Cas9 mutagenesis showed iNeurons are required for functional recovery and employ vesicular trafficking as an essential mechanism that underlies neuronal plasticity. This study provides a comprehensive resource of the cells and mechanisms that direct spinal cord regeneration and establishes zebrafish as a model of plasticity-driven neural repair.

Formyl peptide receptor 2 regulates dendritic cell metabolism and Th17 cell differentiation during neuroinflammation.

Formyl peptide receptor 2 (FPR2) is a receptor for formylated peptides and specific pro-resolving mediators, and is involved in various inflammatory processes. Here, we aimed to elucidate the role of FPR2 in dendritic cell (DC) function and autoimmunity-related central nervous system (CNS) inflammation by using the experimental autoimmune encephalomyelitis (EAE) model. EAE induction was accompanied by increased Fpr2 mRNA expression in the spinal cord. FPR2-deficient (Fpr2 KO) mice displayed delayed onset of EAE compared to wild-type (WT) mice, associated with reduced frequencies of Th17 cells in the inflamed spinal cord at the early stage of the disease. However, FPR2 deficiency did not affect EAE severity after the disease reached its peak. FPR2 deficiency in mature DCs resulted in decreased expression of Th17 polarizing cytokines IL6, IL23p19, IL1ß, and thereby diminished the DC-mediated activation of Th17 cell differentiation. LPS-activated FPR2-deficient DCs showed upregulated Nos2 expression and nitric oxide (NO) production, as well as reduced oxygen consumption rate and impaired mitochondrial function, including decreased mitochondrial superoxide levels, lower mitochondrial membrane potential and diminished expression of genes related to the tricarboxylic acid cycle and genes related to the electron transport chain, as compared to WT DCs. Treatment with a NO inhibitor reversed the reduced Th17 cell differentiation in the presence of FPR2-deficient DCs. Together, by regulating DC metabolism, FPR2 enhances the production of DC-derived Th17-polarizing cytokines and hence Th17 cell differentiation in the context of neuroinflammation.

DNA damage induced PARP-1 overactivation confers paclitaxel-induced neuropathic pain by regulating mitochondrial oxidative metabolism.

AIMS: Poly (ADP-ribose) polymerase (PARP) has been extensively investigated in human cancers. Recent studies verified that current available PARP inhibitors (Olaparib or Veliparib) provided clinical palliation of clinical patients suffering from paclitaxel-induced neuropathic pain (PINP). However, the underlying mechanism of PARP overactivation in the development of PINP remains to be investigated. METHODS AND RESULTS: We reported induction of DNA oxidative damage, PARP-1 overactivation, and subsequent nicotinamide adenine dinucleotide (NAD+) depletion as crucial events in the pathogenesis of PINP. Therefore, we developed an Olaparib PROTAC to achieve the efficient degradation of PARP. Continuous intrathecal injection of Olaparib PROTAC protected against PINP by inhibiting the activity of PARP-1 in rats. PARP-1, but not PARP-2, was shown to be a crucial enzyme in the development of PINP. Specific inhibition of PARP-1 enhanced mitochondrial redox metabolism partly by upregulating the expression and deacetylase activity of sirtuin-3 (SIRT3) in the dorsal root ganglions and spinal cord in the PINP rats. Moreover, an increase in the NAD+ level was found to be a crucial mechanism by which PARP-1 inhibition enhanced SIRT3 activity. CONCLUSION: The findings provide a novel insight into the mechanism of DNA oxidative damage in the development of PINP and implicate PARP-1 as a possible therapeutic target for clinical PINP treatment.

Astrocyte-Neuron Interactions in Spinal Cord Injury.

Spinal cord injuries cause irreversible loss of sensory and motor functions. In mammals, intrinsic and extrinsic inhibitions of neuronal regeneration obstruct neural repair after spinal cord injury. Although astrocytes have been involved in a growing list of vital homeostatic functions in the nervous system, their roles after injury have fascinated and puzzled scientists for decades. Astrocytes undergo long-lasting morphological and functional changes after injury, referred to as reactive astrogliosis. Although reactive astrogliosis is required to contain spinal cord lesions and restore the blood-spinal cord barrier, reactive astrocytes have detrimental effects that inhibit neuronal repair and remyelination. Intriguingly, elevated regenerative capacity is preserved in some non-mammalian vertebrates, where astrocyte-like glial cells display exclusively pro-regenerative effects after injury. A detailed molecular and phenotypic catalog of the continuum of astrocyte reactivity states is an essential first step toward the development of glial cell manipulations for spinal cord repair.

How I do it: Exoscope assisted microsurgical ligation of type 1 spinal dural arteriovenous fistula.

BACKGROUND: Type 1 Spinal dural arteriovenous fistula (dAVF) is a rare but curable vascular cause of myelopathy. Microneurosurgery is a very efficacious modality in treating them. METHOD: A 26 year old gentleman with progressive flaccid paraparesis (LMN type) and urinary incontinence underwent surgery using exoscope for a right side T9-10 dAVF. A dilated vein was seen accompanying the exiting nerve root intraoperatively, consistent with the preoperative angiographic findings. The vein was ligated and divided leading to restitution of spinal cord vasculature on table and excellent postoperative outcome. CONCLUSION: Surgical resection is a straightforward and highly effective treatment in spinal dAVF.