Mouse Model Of Spinal Cord Injury Research Articles

Exosomes from hypoxic ADSCs ameliorate neuronal damage post spinal cord injury through circ-Wdfy3 delivery and inhibition of ferroptosis

BackgroundExosomes generated from adipose-derived mesenchymal stem cells (Exos), and in particular hypoxia-pretreated ADSCs (HExos), possess therapeutic properties that promote spinal cord repair following spinal cord injury (SCI). Nevertheless, the regulatory mechanisms through which HExos exert their effects remain unclear. MethodsHere, next-generation sequencing (NGS) was utilized to examine abnormal circRNA expression comparing HExos to Exos. Bioinformatics analysis and RNA pulldown assays together with luciferase reporter assays were applied to determine interactions among miRNAs, mRNAs and circRNAs. ELISA and immunofluorescence staining were used to examine inflammatory cytokine levels, apoptosis and ROS deposition in LPS-treated HT-22 cells, respectively. The therapeutic effects of Exos and HExos on a mouse model of SCI were analyzed by immunohistochemistry and immunofluorescence staining. ResultsOur findings confirmed that HExos have more significant therapeutic influences on decreasing ROS and inflammatory cytokine levels post-SCI than Exos. NGS revealed that circ-Wdfy3 expression levels were significantly higher in HExos than Exos. Downregulation of circ-Wdfy3 led to a decrease in HExo-induced therapeutic effects on spinal cord repair post-SCI, indicating that circ-Wdfy3 has a critical role in the regulation of HExo-mediated protection against SCI. Our bioinformatics, RNA pulldown and luciferase reporter data demonstrated that GPX4 and miR-423-3p were downstream targets of circ-Wdfy3. GPX4 downregulation or miR-423-3p overexpression reversed the protective effects of circ-Wdfy3 on LPS-treated HT-22 cells. Furthermore, overexpression of circ-Wdfy3 led to an in increase in the Exo-induced therapeutic effects on spinal cord repair post-SCI through the inhibition of ferroptosis. Conclusionscirc-WDfy3-overexpressing Exos promote spinal cord repair post-SCI through mediation of ferroptosis via the miR-138-5p/GPX4 pathway.

Exercise Volume Can Modulate the Regenerative Response to Spinal Cord Injury in Mice.

Traumatic spinal cord injury (SCI) causes debilitating motor and sensory deficits that impair functional performance, and physical rehabilitation is currently the only established therapeutic reality in the clinical setting. In this study, we aimed to assess the effect of exercise of different volume and timing of intervention on functional recovery and neuromuscular regeneration in a mouse model of compressive SCI. Mice were assigned to one of four groups: laminectomy only (SHAM); injured, without treadmill training (SCI); injured, treadmill trained for 10 min until day 56 postinjury (TMT1); and injured, treadmill trained for two 10-min cycles with a 10-min pause between them until day 28 postinjury followed by the TMT1 protocol until day 56 postinjury (TMT3). On day 7 postinjury, animals started an eight-week treadmill-training exercise protocol and were trained three times a week. TMT3 mice had the best results in terms of neuroregeneration, functional recovery, and muscle plasticity as measured by functional and morphometric parameters. In conclusion, the volume of exercise can modulate the quality of the regenerative response to injury, when started in the acute phase and adjusted according to the inflammatory window.

SP1 transcriptionally activates HTR2B to aggravate traumatic spinal cord injury by shifting microglial M1/M2 polarization.

Spinal cord injury (SCI) can result in structural and functional damage to the spinal cord, which may lead to loss of limb movement and sensation, loss of bowel and bladder control, and other complications. Previous studies have revealed the critical influence of trans-acting transcription factor 1 (SP1) in neurological pathologies, however, its role and mechanism in SCI have not been fully studied. The study was performed using mouse microglia BV2 stimulated using lipopolysaccharide (LPS) and male adult mice subjected to spinal hitting. Western blotting was performed to detect protein expression of SP1, 5-hydroxytryptamine (serotonin) receptor 2B (HTR2B), BCL2-associated x protein (Bax), B-cell lymphoma-2 (Bcl-2), inducible nitric oxide synthase (iNOS), clusters of differentiation 86 (CD86), Arginase 1 (Arg-1) and clusters of differentiation 206 (CD206). Cell viability and apoptosis were analyzed by MTT assay and TUNEL assay. mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-4 (IL-4) and tumor necrosis factor-β (TNF-β) were quantified by quantitative real-time polymerase chain reaction. The association of SP1 and HTR2B was identified by chromatin immunoprecipitation assay and dual-luciferase reporter assay. HE staining assay was performed to analyze the pathological conditions of spinal cord tissues. LPS treatment induced cell apoptosis and inhibited microglia polarization from M1 to M2 phenotype, accompanied by an increase of Bax protein expression and a decrease of Bcl-2 protein expression, however, these effects were relieved after SP1 silencing. Mechanism assays revealed that SP1 transcriptionally activated HTR2B in BV2 cells, and HTR2B knockdown rescued LPS-induced effects on BV2 cell apoptosis and microglial M1/M2 polarization. Moreover, SP1 absence inhibited BV2 cell apoptosis and promoted microglia polarization from M1 to M2 phenotype by decreasing HTR2B expression. SCI mouse model assay further showed that SP1 downregulation could attenuate spinal hitting-induced promoting effects on cell apoptosis of spinal cord tissues and microglial M1 polarization. SP1 transcriptionally activated HTR2B to aggravate traumatic SCI by shifting microglial M1/M2 polarization.

179 Stem Progenitor Cell Proliferation in the Brainstem After Spinal Cord Injury: A Potential Target for Therapeutic Intervention Distant From the Site of Injury

INTRODUCTION: Though there has been an increasing number of clinical trials focused on modulating stem/progenitor cell proliferation in the spinal cord after spinal cord injury (SCI), little is known about the acute response of stem/progenitor cells in supraspinal structures. We hypothesized that the signals stimulating stem/progenitor cell proliferation in the spinal cord after SCI activate similar responses in supraspinal regions because pathways injured in the spinal cord have their targets or sources in the brain. METHODS: We employed a mouse model of SCI, bromodeoxyuridine (BrdU) labeling of cells in S-phase, and co-labeling of markers of astrocytes, microglia, glial/oligodendrocyte precursor cells, and neuronal lineages to characterize the proliferative response within the brainstem of C57BL/6J mice 96 hours after a thoracic SCI. The extent of SCI and white matter (WM) spared was quantified by labeling of beta amyloid precursor protein and eriochrome cyanine R staining, respectively. RESULTS: Compared to sham-operated mice, there was a significant increase (3-fold; p < 0.01) in BrdU-labeled cells in the ventral-caudal medulla of injured mice. This response was consistent with the extent of SCI and primarily in WM tracts (57%) and the inferior olive (41%; IO). Co-labeling with cell-specific markers indicated that this response is glial (i.e., NG-2+ glial/oligodendrocyte precursor cells and GFAP+ astrocytes) with the largest increase in the number of BrdU-labeled cells occurring in the IO (6-fold increase; p < 0.01). Notably, there were no BrdU-labeled cells that co-labeled with markers of microglia or neuronal lineages. CONCLUSIONS: Our results demonstrate a stem/progenitor cell response within days of SCI that occurs distant from the injury site, notably in brainstem structures involved in motor learning and coordination. These findings highlight an acute response of glial/oligodendrocyte precursor cells in the brainstem as a potential target for future studies and therapeutic intervention after SCI.

Small nucleolar RNA host gene 1 silence inhibits the lipopolysaccharide-induced microglial apoptosis and inflammation.

Microglia activation is an early mediator of neuroinflammation and a major contributor to spinal damage and motor dysfunction. This study was designed to investigate the role of small nucleolar RNA host gene 1 (SNHG1) on the apoptosis and inflammatory response of microglial cell BV-2 and its underlying molecular mechanism. The C5 lamina contusion-induced mouse model of spinal cord injury (SCI) was constructed. Mouse microglia BV2 was stimulated by lipopolysaccharide (LPS) to establish the in vitro model of SCI. The quantitative reverse transcription polymerase chain reaction method was used to quantify RNA expression levels. Enzyme-linked immunosorbent assays were used to quantify concentrations of inflammatory cytokines. Protein levels were assessed by western blotting, and apoptosis was assessed by flow cytometry. Dual luciferase reporter gene assay and RNA pull-down assay were conducted to investigate the binding relationships between molecules. Upregulation of SNHG1 and downregulation of miR-195-5p were observed in the spinal cords of SCI mouse model. LPS treatment led to elevation of SNHG1 expression in BV2 cells, as well as accelerated apoptosis and inflammation. Evident mitigation of LPS-induced BV2 cell damage was observed after SNHG1 knockdown. MiR-195-5p was identified as a target of SNHG1. Inhibition of miR-195-5p restored the impact of SNHG1 knockdown on cell damage of LPS-treated BV2 cells. Furthermore, miR-195-5p can target activating transcription factor-6 (ATF6). In summary, SNHG1 knockdown ameliorates LPS-induced microglial apoptosis and inflammatory response via the miR-195-5p/ATF6 axis, providing a novel direction for SCI treatment.

Extracellular vesicles from UTX-knockout endothelial cells boost neural stem cell differentiation in spinal cord injury

BackgroundVascular endothelial cells are pivotal in the pathophysiological progression following spinal cord injury (SCI). The UTX (Ubiquitously Transcribed Tetratripeptide Repeat on Chromosome X) serves as a significant regulator of endothelial cell phenotype. The manipulation of endogenous neural stem cells (NSCs) offers a compelling strategy for the amelioration of SCI.MethodsTwo mouse models were used to investigate SCI: NSCs lineage-traced mice and mice with conditional UTX knockout (UTX KO) in endothelial cells. To study the effects of UTX KO on neural differentiation, we harvested extracellular vesicles (EVs) from both UTX KO spinal cord microvascular endothelial cells (SCMECs) and negative control SCMECs. These EVs were then employed to modulate the differentiation trajectory of endogenous NSCs in the SCI model.ResultsIn our NSCs lineage-traced mice model of SCI, a marked decrease in neurogenesis was observed post-injury. Notably, NSCs in UTX KO SCMECs mice showed enhanced neuronal differentiation compared to controls. RNA sequencing and western blot analyses revealed an upregulation of L1 cell adhesion molecule (L1CAM), a gene associated with neurogenesis, in UTX KO SCMECs and their secreted EVs. This aligns with the observed promotion of neurogenesis in UTX KO conditions. In vivo administration of L1CAM-rich EVs from UTX KO SCMECs (KO EVs) to the mice significantly enhanced neural differentiation. Similarly, in vitro exposure of NSCs to KO EVs resulted in increased activation of the Akt signaling pathway, further promoting neural differentiation. Conversely, inhibiting Akt phosphorylation or knocking down L1CAM negated the beneficial effects of KO EVs on NSC neuronal differentiation.ConclusionsIn conclusion, our findings substantiate that EVs derived from UTX KO SCMECs can act as facilitators of neural differentiation following SCI. This study not only elucidates a novel mechanism but also opens new horizons for therapeutic interventions in the treatment of SCI.1C6MBiJnKEY-9R1wsAiwJtVideo Graphical

Osteopontin Promotes Angiogenesis in the Spinal Cord and Exerts a Protective Role Against Motor Function Impairment and Neuropathic Pain After Spinal Cord Injury.

Basic science study using a hemisection spinal cord injury (SCI) model. We sought to assess the effect of blocking osteopontin (OPN) upregulation on motor function recovery and pain behavior after SCI and to further investigate the possible downstream target of OPN in the injured spinal cord. OPN is a noncollagenous extracellular matrix protein widely expressed across different tissues. Its expression substantially increases following SCI. A previous study suggested that this protein might contribute to locomotor function recovery after SCI. However, its neuroprotective potential was not fully explored, nor were the underlying mechanisms. We constructed a SCI mouse model and analyzed the expression of OPN at different time points and the particular cell distribution in the injured spinal cord. Then, we blocked OPN upregulation with lentivirus-delivering siRNA targeting OPN specifically and examined its effect on motor function impairment and neuropathic pain after SCI. The underlying mechanisms were explored in the OPN-knockdown mice model and cultured vascular endothelial cells. The proteome study revealed that OPN was the most dramatically increased protein following SCI. OPN in the spinal cord was significantly increased three weeks after SCI. Suppressing OPN upregulation through siRNA exacerbated motor function impairment and neuropathic pain. In addition, SCI resulted in an increase in vascular endothelial growth factor (VEGF), AKT phosphorylation, and angiogenesis within the spinal cord, all of which were curbed by OPN reduction. Similarly, OPN knockdown suppressed VEGF expression, AKT phosphorylation, cell migration, invasion, and angiogenesis in cultured vascular endothelial cells. OPN demonstrates a protective influence against motor function impairment and neuropathic pain following SCI. This phenomenon may result from the proangiogenetic effect of OPN, possibly due to activation of the VEGF and/or AKT pathways.

Nicotinamide Riboside Regulates Chemotaxis to Decrease Inflammation and Ameliorate Functional Recovery Following Spinal Cord Injury in Mice.

Changes in intracellular nicotinamide adenine dinucleotide (NAD+) levels have been observed in various disease states. A decrease in NAD+ levels has been noted following spinal cord injury (SCI). Nicotinamide riboside (NR) serves as the precursor of NAD+. Previous research has demonstrated the anti-inflammatory and apoptosis-reducing effects of NR supplements. However, it remains unclear whether NR exerts a similar role in mice after SCI. The objective of this study was to investigate the impact of NR on these changes in a mouse model of SCI. Four groups were considered: (1) non-SCI without NR (Sham), (2) non-SCI with NR (Sham +NR), (3) SCI without NR (SCI), and (4) SCI with NR (SCI + NR). Female C57BL/6J mice aged 6-8 weeks were intraperitoneally administered with 500 mg/kg/day NR for a duration of one week. The supplementation of NR resulted in a significant elevation of NAD+ levels in the spinal cord tissue of mice after SCI. In comparison to the SCI group, NR supplementation exhibited regulatory effects on the chemotaxis/recruitment of leukocytes, leading to reduced levels of inflammatory factors such as IL-1β, TNF-α, and IL-22 in the injured area. Moreover, NR supplementation notably enhanced the survival of neurons and synapses within the injured area, ultimately resulting in improved motor functions after SCI. Therefore, our research findings demonstrated that NR supplementation had inhibitory effects on leukocyte chemotaxis, anti-inflammatory effects, and could significantly improve the immune micro-environment after SCI, thereby promoting neuronal survival and ultimately enhancing the recovery of motor functions after SCI. NR supplementation showed promise as a potential clinical treatment strategy for SCI.

Targeting transcription factor pu.1 for improving neurologic outcomes after spinal cord injury.

After spinal cord injury (SCI), lipid metabolism dysregulation at the lesion site exacerbates secondary damage. The transcription factor pu.1 has been implicated as a negative regulator of multiple lipid metabolism-related genes and pathways. However, its role in post-SCI lipid metabolism remains unclear. We employed a mouse model of complete T10 crush SCI. Non-targeted metabolomics and bioinformatics analysis were utilized to investigate lipid metabolism at the lesion site after SCI. Polarized light imaging was used to evaluate the presence of cholesterol crystals. DB1976, a specific inhibitor of pu.1, was administered to examine its impact on local lipid metabolism after SCI. Immunofluorescence staining was performed to assess pu.1 expression and distribution, and to evaluate lipid droplet formation, astrocytic/fibrotic scar development, inflammatory cell infiltration, and tight junctions within the vasculature. Non-targeted metabolomics and bioinformatics analyses revealed significant alterations in lipid metabolism components after SCI. Moreover, immunofluorescence staining and polarized light imaging demonstrated substantial BODIPY+ lipid droplet accumulation and persistent cholesterol crystal formation at the lesion site after SCI. Increased pu.1 expression was predominantly observed within macrophages/microglia at the lesion site after SCI. DB1976 treatment significantly mitigated lipid droplet accumulation and cholesterol crystal formation, reduced CD68+ macrophage/microglial infiltration, and attenuated fibrotic scar formation. Moreover, DB1976 treatment promoted the expression of claudin-5 and zonula occludens-1 between vascular endothelial cells and enhanced GFAP+ glial connectivity after SCI. Our study reveals a significant correlation between lipid metabolism disturbance post-SCI and transcription factor pu.1 upregulation, specifically in macrophages/microglia at the lesion site. Thus, targeted pu.1 modulation has the potential to yield promising results by substantially diminishing the deposition of lipid metabolism byproducts at the lesion site and fostering a milieu conducive to SCI repair.

The compensatory increase of Gli-similar 3 inhibited neuronal apoptosis through regulating Mps one binder kinase activator 1b (MOB1b): a possible strategy for the functional recovery after spinal cord injury.

Spinal cord injury (SCI) is a devastating disease characterized by neuronal apoptosis. Gli-similar 3 (GLIS3), a transcriptional factor, was involved in cell apoptosis and associated with the transcription of downstream target genes related to neuronal function. However, the function of GLIS3 in SCI remains unknown. Therefore, we used the mouse model of SCI to explore the role of GLIS3 in SCI. The results showed that GLIS3 expression was significantly increased in spinal cord tissues of SCI mice, and GLIS3 overexpression promoted the functional recovery, reserved histological changes, and inhibited neuronal apoptosis after SCI. Through online tools, the potential target genes of GLIS3 were analyzed and we found that Mps one binder kinase activator 1b (Mob1b) had a strong association with SCI among these genes. MOB1b is a core component of Hippo signaling pathway, which was reported to inhibit cell apoptosis. MOB1b expression was significantly increased in mice at 7 days post-SCI and GLIS3 overexpression further increased its expression. Dual-luciferase reporter assay revealed that GLIS3 bound to the promoter of Mob1b and promoted its transcription. In conclusion, our findings reveal that the compensatory increase of GLIS3 promotes functional recovery after SCI through inhibiting neuronal apoptosis by transcriptionally regulating MOB1b. Our study provides a novel target for functional recovery after SCI.

Down-regulation of PGAM5 attenuates spinal cord injury-induced neuronal injury by inhibiting ASK-1/p38/NF-kB signaling.

The morbidity and mortality of spinal cord injury (SCI) are increasing year by year. It is of vital importance to ascertain the mechanism of SCI. Phosphoglycerate mutase family member 5 (PGAM5) is viewed as a molecular marker of SCI, but its specific role in SCI is elusive. Following establishment of the SCI mouse model, the pathological examination of the spinal cord was initially assessed using H&E staining. PGAM5 expression in spinal cord tissues was appraised utilizing immunohistochemistry and RT-qPCR. Subsequently, after the expression of PGAM5 in SCI mice was inhibited by adenovirus transfection, the degree of SCI was determined, and the motor ability of hind limbs was estimated with the BBB score. In addition, the apoptosis of neurons, microglia activation and the generation of inflammatory cytokines in the spinal cord of mice were detected. Next, at the cellular level, PGAM5 expression was inhibited in the BV2 microglial cells induced by lipopolysaccharide (LPS), so as to explore the effects of down-regulation of PGAM5 on the activation, inflammation and apoptosis of neurons. Finally, western blot was applied for the appraisement of apoptosis signal-regulating kinase-1 (ASK-1)/p38/nuclear factor-kappa B (NF-kB) signaling-associated proteins. PGAM5 expression in SCI mice was found to be raised. Inhibition of PGAM5 expression in SCI mice can significantly reduce spinal cord pathological injury, SCI-induced neuronal apoptosis, microglial cell activation and inflammation. The above regulatory process might be realized through the ASK-1/p38/NF-kB signaling pathway mediated by PGAM5. Down-regulation of PGAM5 attenuated SCI-induced neuronal injury by inhibiting ASK-1/p38/NF-kB signaling.

Spinal cord injury-induced gut dysbiosis influences neurological recovery partly through short-chain fatty acids

Spinal cord injury (SCI) can reshape gut microbial composition, significantly affecting clinical outcomes in SCI patients. However, mechanisms regarding gut–brain interactions and their clinical implications have not been elucidated. We hypothesized that short-chain fatty acids (SCFAs), intestinal microbial bioactive metabolites, may significantly affect the gut–brain axis and enhance functional recovery in a mouse model of SCI. We enrolled 59 SCI patients and 27 healthy control subjects and collected samples. Thereafter, gut microbiota and SCFAs were analyzed using 16 S rDNA sequencing and gas chromatography–mass spectrometry, respectively. We observed an increase in Actinobacteriota abundance and a decrease in Firmicutes abundance. Particularly, the SCFA-producing genera, such as Faecalibacterium, Megamonas, and Agathobacter were significantly downregulated among SCI patients compared to healthy controls. Moreover, SCI induced downregulation of acetic acid (AA), propionic acid (PA), and butyric acid (BA) in the SCI group. Fecal SCFA contents were altered in SCI patients with different injury course and injury segments. Main SCFAs (AA, BA, and PA) were administered in combination to treat SCI mice. SCFA supplementation significantly improved locomotor recovery in SCI mice, enhanced neuronal survival, promoted axonal formation, reduced astrogliosis, and suppressed microglial activation. Furthermore, SCFA supplementation downregulated NF-κB signaling while upregulating neurotrophin-3 expression following SCI. Microbial sequencing and metabolomics analysis showed that SCI patients exhibited a lower level of certain SCFAs and related bacterial strains than healthy controls. SCFA supplementation can reduce inflammation and enhance nourishing elements, facilitating the restoration of neurological tissues and the improvement of functional recuperation. Trial registration: This study was registered in the China Clinical Trial Registry (www.chictr.org.cn) on February 13, 2017 (ChiCTR-RPC-17010621).

Synergistic Pharmacological Therapy to Modulate Glial Cells in Spinal Cord Injury.

Current treatments for modulating the glial-mediated inflammatory response after spinal cord injury (SCI) have limited ability to improve recovery. This is quite likely due to the lack of a selective therapeutic approach acting on microgliosis and astrocytosis, the glia components most involved after trauma, while maximizing efficacy and minimizing side effects. A new nanogel that can selectively release active compounds in microglial cells and astrocytes is developed and characterized. The degree of selectivity and subcellular distribution of the nanogel is evaluated by applying an innovative super-resolution microscopy technique, expansion microscopy. Two different administration schemes are then tested in a SCI mouse model: in an early phase, the nanogel loaded with Rolipram, an anti-inflammatory drug, achieves significant improvement in the animal's motor performance due to the increased recruitment of microglia and macrophages that are able to localize the lesion. Treatment in the late phase, however, gives opposite results, with worse motor recovery because of the widespread degeneration. These findings demonstrate that the nanovector can be selective and functional in the treatment of the glial component in different phases of SCI. They also open a new therapeutic scenario for tackling glia-mediated inflammation after neurodegenerative events in the central nervous system.

Small Extracellular Vesicles Derived from Altered Peptide Ligand-Loaded Dendritic Cell Act as A Therapeutic Vaccine for Spinal Cord Injury Through Eliciting CD4+ T cell-Mediated Neuroprotective Immunity.

The balance among different CD4+ T cell subsets is crucial for repairing the injured spinal cord. Dendritic cell (DC)-derived small extracellular vesicles (DsEVs) effectively activate T-cell immunity. Altered peptide ligands (APLs), derived from myelin basic protein (MBP), have been shown to affect CD4+ T cell subsets and reduce neuroinflammation levels. However, the application of APLs is challenging because of their poor stability and associated side effects. Herein, it is demonstrate that DsEVs can act as carriers for APL MBP87-99 A91 (A91-DsEVs) to induce the activation of 2 helper T (Th2) and regulatory T (Treg) cells for spinal cord injury (SCI) in mice. These stimulated CD4+ T cells can efficiently "home" to the lesion area and establish a beneficial microenvironment through inducing the activation of M2 macrophages/microglia, inhibiting the expression of inflammatory cytokines, and increasing the release of neurotrophic factors. The microenvironment mediated by A91-DsEVs may enhance axon regrowth, protect neurons, and promote remyelination, which may support the recovery of motor function in the SCI model mice. In conclusion, using A91-DsEVs as a therapeutic vaccine may help induce neuroprotective immunity in the treatment of SCI.

TRIM32 Inhibits NEK7 Ubiquitylation-Dependent Microglia Pyroptosis After Spinal Cord Injury.

Spinal cord injury (SCI) is a disabling disease associated with microglial activation. Tripartite motif containing 32 (TRIM32) is an E3 ubiquitin ligase that plays a role in SCI. This study aimed to explore the role of TRIM32 in SCI and its potential mechanisms. We established an SCI mouse model to assess the function of TRIM32 using quantitative real-time polymerase chain reaction (qPCR), and hematoxylin and eosin staining. Additionally, a lipopolysaccharides (LPS)-induced cell injury model was generated to explore the impact of TRIM32 on pyroptosis using qPCR, propidium iodide staining, and western blotting. The ubiquitylation of NEK7 was analyzed using western blotting, co-immunoprecipitation, and immunofluorescence staining. The results showed that TRIM32 expression was increased in SCI mice and LPS-induced BV-2 cells. Overexpression of TRIM32 ameliorated SCI in mice and suppressed pyroptosis in LPS-treated BV-2 cells. Additionally, the E3 ligase TRIM32 promoted the ubiquitylation of NEK7 at the K64 site, leading to the downregulation of NEK7 levels. Inhibiting NEK7 ubiquitylation reversed the suppression of pyroptosis by TRIM32. In conclusion, TRIM32 inhibits microglia pyroptosis by facilitating the ubiquitylation of NEK7 at the K64 site, thereby alleviating the progression of SCI. The findings suggest that TRIM32 has the potential to be a therapeutic target of SCI.

Human Adipose Tissue Lysate-Based Hydrogel for Lasting Immunomodulation to Effectively Improve Spinal Cord Injury Repair.

The long-term inflammatory microenvironment is one of the main obstacles to inhibit acute spinal cord injury (SCI) repair. The natural adipose tissue-derived extracellular matrix hydrogel shows effective anti-inflammatory regulation because of its unique protein components. However, the rapid degradation rate and removal of functional proteins during the decellularization process impair the lasting anti-inflammation function of the adipose tissue-derived hydrogel. To address this problem, adipose tissue lysate provides an effective way for SCI repair due to its abundance of anti-inflammatory and nerve regeneration-related proteins. Thereby, human adipose tissue lysate-based hydrogel (HATLH) with an appropriate degradation rate is developed, which aims to in situ long-term recruit and induce anti-inflammatory M2 macrophages through sustainedly released proteins. HATLH can recruit and polarize M2 macrophages while inhibiting pro-inflammatory M1 macrophages regardless of human or mouse-originated. The axonal growth of neuronal cells also can be effectively improved by HATLH and HATLH-induced M2 macrophages. In vivo experiments reveal that HATLH promotes endogenous M2 macrophages infiltration in large numbers (3.5 × 105/100µL hydrogel) and maintains a long duration for over a month. In a mouse SCI model, HATLH significantly inhibits local inflammatory response, improves neuron and oligodendrocyte differentiation, enhances axonal growth and remyelination, as well as accelerates neurological function restoration.

PD-1 deficiency aggravates spinal cord injury by regulating the reprogramming of NG2 glia and activating the NgR/RhoA/ROCK signaling pathway

Spinal cord injury (SCI) is a devastating disorder and a leading cause of disability in adults worldwide. Multiple studies have reported the upregulation of programmed cell death 1 (PD-1) following SCI. However, the underlying mechanism of PD-1 deficiency in SCI is not well established. Therefore, we aimed to investigate the role and potential mechanism of PD-1 in SCI pathogenesis. PD-1 Knockout (KO) SCI mouse model was established, and PD-1 expression was evaluated in tissue samples by western blot assay. We then used a series of function gain-and-loss assays to determine the role of PD-1 in SCI pathogenesis. Moreover, mechanistic assays were performed to explore the association between PD-1, neuron-glia antigen-2 (NG2) glia cells, and miR-23b-5p and then investigated the involved signaling pathway. Results illustrated that PD-1 deficiency enhanced the inflammatory response, neuron loss, and functional impairment induced by SCI. We found that NG2 glia depletion aggravated inflammation, reduced neural survival, and suppressed locomotor recovery in murine SCI model. Further analysis indicated that NG2+ cells were increased in the spinal cord of SCI mice, and PD-1 deficiency increased the number of NG2+ cells by activating the Nogo receptor/ras homolog family member A/Rho kinase (NgR/RhoA/ROCK) signaling. Mechanistically, miR-23b-5p was identified as the negative regulator of PD-1 in NG2 glia. MiR-23b-5p deficiency reduced the expression of inflammatory cytokines, enhanced neural survival, and promoted locomotor recovery in SCI mice, which was counteracted by PD-1 deficiency. In conclusion, PD-1 deficiency exacerbates SCI in vivo by regulating reprogramming of NG2 glia and activating the NgR/RhoA/ROCK signaling.

Electroacupuncture promotes the repair of the damaged spinal cord in mice by mediating neurocan-perineuronal net.

This study aimed to investigate the effect of perineuronal net (PNN) and neurocan (NCAN) on spinal inhibitory parvalbumin interneuron (PV-IN), and the mechanism of electroacupuncture (EA) in promoting spinal cord injury (SCI) repair through neurocan in PNN. A mouse model of SCI was established. Sham-operated mice or SCI model mice were treated with chondroitin sulfate ABC (ChABC) enzyme or control vehicle for 2 weeks (i.e., sham+veh group, sham+ChABC group, SCI+veh group, and SCI+ChABC group, respectively), and then spinal cord tissues were taken from the T10 lesion epicenter for RNA sequencing (RNA-seq). MSigDB Hallmark and C5 databases for functional analysis, analysis strategies such as differential expression gene analysis (DEG), Kyoto Encyclopedia of Genes and Genomes (KEGG), gene set enrichment analysis (GSEA), and protein-protein interaction (PPI). According to the results of RNA-seq analysis, the expression of NCAN was knocked down or overexpressed by virus intervention, or/and EA intervention. Polymerase chain reaction (PCR), immunofluorescence, western blot, electrophysiological, and behavioral tests were performed. After the successful establishment of SCI model, the motor dysfunction of lower limbs, and the expression of PNN core glycan protein at the epicenter of SCI were reduced. RNA-seq and PCR showed that PNN core proteoglycans except NCAN showed the same expression trend in normal and injured spinal cord treated with ChABC. KEGG and GSEA showed that PNN is mainly associated with inhibitory GABA neuronal function in injured spinal cord tissue, and PPI showed that NCAN in PNN can be associated with inhibitory neuronal function through parvalbumin (PV). Calcium imaging showed that local parvalbumin interneuron (PV-IN) activity decreased after PNN destruction, whether due to ChABC treatment or surgical bruising of the spinal cord. Overexpression of neurocan in injured spinal cord can enhance local PV-IN activity. PCR and western blot suggested that overexpression or knockdown of neurocan could up-regulate or down-regulate the expression of GAD. At the same time, the activity of PV-IN in the primary motor cortex (M1) and the primary sensory cortex of lower (S1HL) extremity changed synchronously. In addition, overexpression of neurocan improved the electrical activity of the lower limb and promoted functional repair of the paralyzed hind limb. EA intervention reversed the down-regulation of neurocan, enhanced the expression of PNN in the lesioned area, M1 and S1HL. Neurocan in PNN can regulate the activity of PV-IN, and EA can promote functional recovery of mice with SCI by upregulating neurocan expression in PNN.

BFGF-like Activity Supported Tissue Regeneration, Modulated Neuroinflammation, and Rebalanced Ca2+ Homeostasis following Spinal Cord Injury.

A spinal cord injury (SCI) is a well-defined debilitating traumatic event to the spinal cord that usually triggers permanent changes in motor, sensory, and autonomic functions. Injured tissue becomes susceptible to secondary mechanisms caused by SCIs, which include pro-inflammatory cytokine release, the activation of astrocytes and microglia, and increased neuronal sensibility. As a consequence, the production of factors such as GFAP, IBA-1, TNF-α, IL-1β, IFN-γ, and S100-β slow down or inhibit central nervous system (CNS) regeneration. In this regard, a thorough understanding of the mechanisms regulating the CNS, and specifically SCI, is essential for the development of new therapeutic strategies. It has been demonstrated that basic fibroblast growth factor (bFGF) was successful in the modulation of neurotrophic activity, also promoting neurite survival and tissue repair, thus resulting in the valuable care of CNS disorders. However, bFGF therapeutic use is limited due to the undesirable effects developed following its administration. Therefore, the synthetic compound mimetic of bFGF, SUN11602 (with chemical name 4-[[4-[[2-[(4-Amino-2,3,5,6-tetramethylphenyl)amino]acetyl]methylamino]-1-piperidinyl]methyl]benzamide), has been reported to show neuroprotective activities similar to those of bFGF, also demonstrating a good pharmacokinetic profile. Here, we aimed to investigate the neuroprotective activity of this bFGF-like compound in modulating tissue regeneration, neuroinflammation, and Ca2+ overload by using a subacute mouse model of SCI. SUN11602 (1, 2.5, and 5 mg/kg) was administered orally to mice for 72 h daily following the in vivo model of SCI, which was generated by the extradural compression of the spinal cord. The data obtained demonstrated that SUN11602 treatment considerably decreased motor alteration and diminished the neuroinflammatory state through the regulation of glial activation, the NF-κB pathway, and kinases. Additionally, by controlling Ca2+-binding proteins and restoring neurotrophin expression, we showed that SUN11602 therapy restored the equilibrium of the neuronal circuit. Because of these findings, bFGF-like compounds may be an effective tool for reducing inflammation in SCI patients while enhancing their quality of life.

FGF-18 Protects the Injured Spinal cord in mice by Suppressing Pyroptosis and Promoting Autophagy via the AKT-mTOR-TRPML1 axis.

Spinal cord injury (SCI) is a severe medical condition with lasting effects. The efficacy of numerous clinical treatments is hampered by the intricate pathophysiological mechanism of SCI. Fibroblast growth factor 18 (FGF-18) has been found to exert neuroprotective effects after brain ischaemia, but its effect after SCI has not been well explored. The aim of the present study was to explore the therapeutic effect of FGF-18 on SCI and the related mechanism. In the present study, a mouse model of SCI was used, and the results showed that FGF-18 may significantly affect functional recovery. The present findings demonstrated that FGF-18 directly promoted functional recovery by increasing autophagy and decreasing pyroptosis. In addition, FGF-18 increased autophagy, and the well-known autophagy inhibitor 3-methyladenine (3MA) reversed the therapeutic benefits of FGF-18 after SCI, suggesting that autophagy mediates the therapeutic effects of FGF-18 on SCI. A mechanistic study revealed that after stimulation of the protein kinase B (AKT)-transient receptor potential mucolipin 1 (TRPML1)-calcineurin signalling pathway, the FGF-18-induced increase in autophagy was mediated by the dephosphorylation and nuclear translocation of transcription factor E3 (TFE3). Together, these findings indicated that FGF-18 is a robust autophagy modulator capable of accelerating functional recovery after SCI, suggesting that it may be a promising treatment for SCI in the clinic.