Neuroinflammation In Spinal Cord Injury Research Articles

Exploring the Impact of Fibroblast Growth Factor 17 on Functional Recovery and Neuroinflammation in Spinal Cord Injury

Spinal cord injury (SCI) affects more than 300,000 people in the United States, making it a significant and widespread problem. This includes injuries at the cervical level, which pose greater challenges due to respiratory in addition to mobility issues. Though there is a large societal impact there is still standard of care following spinal cord injury. While previous preclinical research has shown benefits from FGF1 and FGF2, there is weak data to suggest their clinical effcacy. A related compound, Fibroblast Growth Factor 17 (FGF17), has recently been described as a component within the CSF of young animals that when delivered to aged animals improved cognitive function. These improvements were associated with oligodendrogenesis. Spinal cord injury results in secondary demyelination, which may be mitigated by increasing oligodendrogenesis; this led us to examine how FGF17 may be used as a therapeutic agent following SCI. We used a rat C2 hemisection injury model to evaluate the effects of FGF17 at 4 hours, 2 and 6 weeks after injury. FGF17 was administered via intrathecal infusion at 25 μg/μl for 14 days at 0.5 μL/hour or a single application of 20 μL (4-hour timepoint). Following treatment, whole body plethysmography was performed weekly. Tissues were collected at endpoint to assess brainstem neuroinflammation via immunohistochemistry and molecular signaling pathways via western blotting. As anticipated, animals that were not treated with FGF17 had reduced tidal volume following spinal cord injury. Treatment with FGF17 partially preserved tidal volume as early as 3 days post injury. 6 weeks following spinal cord injury we observed a reduction in GFAP+ and IBA1+ staining in the brainstem near regions associated with respiratory control in animals treated with FGF17. Further, when we quantified the protein content in the spinal cord near the lesion epicenter we saw an increase in p-ERK 1/2 in all injured animals. However, in FGF17 treated animals we saw an increase in downstream transcription factors, STAT6 and Serum Response Factor. Serum Response Factor was implicated in oligodendrogenesis, ongoing studies will directly address this. These data suggest that FGF17 may be a viable alternative to the traditional fibroblast growth factor family members when treating spinal cord injury. R21NS121966, R01NS116068. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Novel nanocomposites improve functional recovery of spinal cord injury by regulating NF-κB mediated microglia polarization

Secondary neuroinflammation caused by proinflammatory microglia exacerbates the disability of patients with spinal cord injury (SCI), while low drug delivery efficiency reduces the therapeutic effect of conventional drugs on promoting functional recovery. Nowadays, resorting to nanocomposites has been regarded as a promising approach to overcome such an obstacle. Herein, neutrophil membrane-coated quercetin-loaded nanoparticles (denoted NQNPs) were developed to improve drug delivery efficiency and repolarize microglia thereby inhibiting secondary neuroinflammation in SCI. Quercetin-loaded nanoparticles (QNPs), which have the capacity to reprogram proinflammatory microglia toward anti-inflammatory microglia, act as the inner core of NQNPs. The neutrophil membrane was further coated onto the inner core for targeted drug delivery and co-neutralizing inflammatory factors. In vitro and in vivo studies demonstrated that NQNPs could controllably release quercetin under the reactive oxygen species (ROS) abundant environment, reprogram microglia polarization toward M2 phenotype via nuclear factor kappa-B (NK-κB) pathway, thereby inhibiting excessive neuroinflammation, increasing the density and functional status of neurons, and finally promoting motor recovery of SCI with outstanding biocompatibility. We believe that the current research brings a novel strategy and sheds new light on the treatment of SCI.

BM-MSC-Loaded Graphene-Collagen Cryogels Ameliorate Neuroinflammation in a Rat Spinal Cord Injury Model.

A major obstacle to axonal regeneration following spinal cord injury (SCI) is neuroinflammation mediated by astrocytes and microglial cells. We previously demonstrated that graphene-based collagen hydrogels alone can decrease neuroinflammation in SCI. Their regenerative potential, however, is poorly understood and incomplete. Furthermore, stem cells have demonstrated both neuroprotective and regenerative properties in spinal cord regeneration, although there are constraints connected with the application of stem cell-based therapy. In this study, we have analyzed the regeneration capability of human bone marrow mesenchymal stem cell (BM-MSC)-loaded graphene-cross-linked collagen cryogels (Gr-Col) in a thoracic (T10-T11) hemisection model of SCI. Our study found that BM-MSC-loaded Gr-Col improves axonal regeneration, reduces neuroinflammation by decreasing astrocyte reactivity, and promotes M2 macrophage polarization. BM-MSC-loaded-Gr-Col demonstrated enhanced regenerative potential compared to Gr-Col and the injury group control. Next-generation sequencing (NGS) analysis revealed that BM-MSC-loaded-Gr-Col modulates the JAK2-STAT3 pathway, thus decreasing the reactive and scar-forming astrocyte phenotype. The decrease in neuroinflammation in the BM-MSC-loaded-Gr-Col group is attributed to the modulation of Notch/Rock and STAT5a/b and STAT6 signaling. Overall, Gene Set Enrichment Analysis suggests the promising role of BM-MSC-loaded-Gr-Col in promoting axonal regeneration after SCI by modulating molecular pathways such as the PI3/Akt pathway, focal adhesion kinase, and various inflammatory pathways.

Dihydrotestosterone reduces neuroinflammation in spinal cord injury through NF-κB and MAPK pathway.

Neuroinflammation induced by microglia following spinal cord injury (SCI) leads to secondary neurologic injury. Androgens including testosterone and dihydrotestosterone (DHT) show as endogenous neuroprotective factors against multiple neurologic diseases, while their therapeutic role in SCI-induced neuroinflammation and underlying mechanism remains elusive. In the study, we aimed to investigate the role of DHT against microglia-induced neuroinflammation in SCI and evaluate its protective treatment. BV2 cells were activated by neuroinflammation via LPS in vitro. Adult male C57BL/6 mice were used to establish the SCI model. BV2 cells and SCI mice were administrated DHT. Microglia activation, pro-inflammatory factors, p38 and p65 phosphorylation, glial scar, fibrotic scar, histology, and locomotor function recovery were measured, respectively. We demonstrated that DHT administration attenuates neuroinflammation in microglia through inhibition of p38 and p65 pathways. Moreover, DHT reduces microglia and astrocyte accumulation, cord fibrosis and histologic damage. Besides, DHT ameliorates locomotor functional recovery after SCI. DHT is verified to play a neuroprotective role in SCI, which fights against neuroinflammation by inhibition of p38 and p65 pathways. Therefore, Mel is defined as a promising factor in protecting neural tissue after SCI.

Injectable and Photocurable Gene Scaffold Facilitates Efficient Repair of Spinal Cord Injury.

RNA interference-based gene therapy has led to a strategy for spinal cord injury (SCI) therapy. However, there have been high requirements regarding the optimal gene delivery vector for siRNA-based SCI gene therapy. Here, we developed an injectable and photocurable lipid nanoparticle GelMA (PLNG) hydrogel scaffold for controlled dual siRNA delivery at the SCI wound site. The prepared PLNG scaffold could efficiently protect and retain the bioactivity of the siRNA nanocomplex. It facilitated sustainable siRNA release along with degradation in 7 days. After loading dual siRNA targeting phosphatase and tensin homologue (PTEN) and macrophage migration inhibitory factor (MIF) simultaneously, the locally administered siRNAs/PLNG scaffold efficiently improved the Basso mouse scale (BMS) score and recovered ankle joint movement and plantar stepping after treatment with only three doses. We further proved that the siRNAs/PLNG scaffold successfully regulated the activities of neurons, microglia, and macrophages, thus promoting neuron axon regeneration and remyelination. The protein array results suggested that the siRNAs/PLNG scaffold could increase the expression of growth factors and decrease the expression of inflammatory factors to regulate neuroinflammation in SCI and create a neural repair environment. Our results suggested that the PLNG scaffold siRNA delivery system is a potential candidate for siRNA-based SCI therapy.

Lycium barbarum glycopeptide alleviates neuroinflammation in spinal cord injury via modulating docosahexaenoic acid to inhibiting MAPKs/NF-kB and pyroptosis pathways

BackgroundLycium barbarum polysaccharide (LBP) is an active ingredient extracted from Lycium barbarum that inhibits neuroinflammation, and Lycium barbarum glycopeptide (LbGp) is a glycoprotein with immunological activity that was purified and isolated from LBP. Previous studies have shown that LbGp can regulate the immune microenvironment, but its specific mechanism of action remains unclear.AimsIn this study, we aimed to explore the mechanism of action of LbGp in the treatment of spinal cord injury through metabolomics and molecular experiments.MethodsSD male rats were randomly assigned to three experimental groups, and after establishing the spinal cord hemisection model, LbGp was administered orally. Spinal cord tissue was sampled on the seventh day after surgery for molecular and metabolomic experiments. In vitro, LbGp was administered to mimic the inflammatory microenvironment by activating microglia, and its mechanism of action in suppressing neuroinflammation was further elaborated using metabolomics and molecular biology techniques such as western blotting and q-PCR.ResultsIn vivo and in vitro experiments found that LbGp can improve the inflammatory microenvironment by inhibiting the NF-kB and pyroptosis pathways. Furthermore, LbGp induced the secretion of docosahexaenoic acid (DHA) by microglia, and DHA inhibited neuroinflammation through the MAPK/NF-κB and pyroptosis pathways.ConclusionsIn summary, we hypothesize that LbGp improves the inflammatory microenvironment by regulating the secretion of DHA by microglia and thereby inhibiting the MAPK/NF-κB and pyroptosis pathways and promoting nerve repair and motor function recovery. This study provides a new direction for the treatment of spinal cord injury and elucidates the potential mechanism of action of LbGp.

Lipocalin-2 Deficiency Diminishes Canonical NLRP3 Inflammasome Formation and IL-1β Production in the Subacute Phase of Spinal Cord Injury.

Spinal cord injury (SCI) results in the production of proinflammatory cytokines due to inflammasome activation. Lipocalin 2 (LCN2) is a small secretory glycoprotein upregulated by toll-like receptor (TLR) signaling in various cells and tissues. LCN2 secretion is induced by infection, injury, and metabolic disorders. In contrast, LCN2 has been implicated as an anti-inflammatory regulator. However, the role of LCN2 in inflammasome activation during SCI remains unknown. This study examined the role of Lcn2 deficiency in the NLRP3 inflammasome-dependent neuroinflammation in SCI. Lcn2-/- and wild-type (WT) mice were subjected to SCI, and locomotor function, formation of the inflammasome complex, and neuroinflammation were assessed. Our findings demonstrated that significant activation of the HMGB1/PYCARD/caspase-1 inflammatory axis was accompanied by the overexpression of LCN2 7 days after SCI in WT mice. This signal transduction results in the cleaving of the pyroptosis-inducing protein gasdermin D (GSDMD) and the maturation of the proinflammatory cytokine IL-1β. Furthermore, Lcn2-/- mice showed considerable downregulation in the HMGB1/NLRP3/PYCARD/caspase-1 axis, IL-1β production, pore formation, and improved locomotor function compared with WT. Our data suggest that LCN2 may play a role as a putative molecule for the induction of inflammasome-related neuroinflammation in SCI.

SARM1 promotes the neuroinflammation and demyelination through IGFBP2/NF-κB pathway in experimental autoimmune encephalomyelitis mice.

Multiple sclerosis (MS) is an autoimmune disease, and its typical characteristics are neuroinflammation and the demyelination of neurons in the central nervous system (CNS). Sterile alpha and TIR motif containing 1 (SARM1) is an essential factor mediating axonal degeneration and SARM1 deletion reduces the neuroinflammation in spinal cord injury. This study aimed to explore the roles of SARM1 and its underlying mechanisms in MS. Experimental autoimmune encephalomyelitis (EAE, a model of MS) model was established. Immunostaining, western blot, electron microscope, and HE staining were used to examine the pathological manifestations such as inflammation, demyelination, and neuronal death in SARM1f/f EAE mice and SARM1Nestin -CKO EAE mice. In addition, RNA-seq, real-time PCR and double-immunostaining were used to examine the underlying mechanism of SARM1 in EAE mice. SARM1 was upregulated in neurons of the spinal cords of EAE mice. SARM1 knockout in CNS ameliorated EAE with less neuroinflammation, demyelination, and dead neurons. Mechanically, SARM1 knockout resulted in the reduction of insulin-like growth factor (IGF)-binding protein 2 (IGFBP2) in neurons of EAE mice, which might inhibit the neuroinflammation through inhibiting NF-κB signaling. Finally, activation of NF-κB partially aggravated the neuroinflammation and demyelination deficits of SARM1Nestin -CKO EAE mice. These results identified the unknown role of SARM1 in the promotion of neuroinflammation and demyelination and revealed a novel drug target pathway of SARM1/IGFBP2/NF-κB for MS.

Protective effect of Boldine against neuroinflammation in spinal cord injury in rats

Abstract The successful clinical management of spinal cord injury (SCI) is still a unmet medical need. Despite advances in novel therapeutics, the multifactorial etiology of SCI still poses significant challenge to the mankind. Thus, in the present study, we intend to scrutinize the protective effect of Boldine (BOL), an alkaloid obtained from the boldo tree against experimental spinal cord injury. The effect of BOL was investigated on locomotor function of rats with various biomarkers of oxidative stress (MDA, SOD and GSH), inflammation (TNF-α, IL-1β and IL-6), and apoptosis. Results suggest that BOL showed improvement in locomotor function (on BBB scale) of rats with does-dependent reduction in oxidative stress and inflammation. It also reduces neuronal apoptosis in flow cytometry experiment. The study successfully demonstrated the possible clinical utility of BOL against SCI.

HUCMSCs transplantation combined with ultrashort wave therapy attenuates neuroinflammation in spinal cord injury through NUR77/ NF-κB pathway

AimsSpinal cord injury (SCI) is a major cause of long-term physical impairment. Currently, treatment for SCI is limited to supportive measures, which can lead to permanent disability, representing a serious social burden. The present study aimed to evaluate the inflammatory microenvironment effects of human umbilical cord mesenchymal stem cells (HUCMSCs)+ Ultrashort Wave (USW) therapy on SCI and reveal possible mechanisms. Main methodsLow-dose USW was treated one day after SCI, and HUCMSCs suspension was transferred to the lesion using a micro-syringe 7 days after SCI. The functional effects of HUCMSCs and USW, separately and combinedly, were measured, together with the infiltration of CD3+ cells, formation of A1 astrocytes and activation of NUR77/ NF-κB pathway. Key findingsOur results showed that HUCMSCs+USW therapy improved motor function of SCI rat, together with decreased infiltration of CD3+ T cells, and decreased induction of microglia and A1 astrocytes. And also USW treatment played a very important role on decreasing the infiltration of CD3+ T cells and IBA-1+ cells. Reduced production of pro-inflammatory cytokines IL-1β and IL-6 was also observed in rats receiving HUCMSCs+USW therapy, medicated by NUR77/NF-κB pathway. SignificanceThese findings indicated that HUCMSCs+USW therapy could attenuate inflammatory microenvironment through NUR77/NF-κB signaling pathway, which might contribute to its better outcome.

Erratum to: A new co-ultramicronized composite including palmitoylethanolamide and luteolin to prevent neuroinflammation in spinal cord injury

Erratum to: A new co-ultramicronized composite including palmitoylethanolamide and luteolin to prevent neuroinflammation in spinal cord injury

A new co-ultramicronized composite including palmitoylethanolamide and luteolin to prevent neuroinflammation in spinal cord injury

BackgroundIt has recently been demonstrated that palmitoylethanolamide (PEA), an endogenous lipid amide belonging to the N-acylethanolamine family, exerts neuroprotection in central nervous system (CNS) pathologies. In recent studies, we have demonstrated that treatment with PEA significantly reduced inflammatory secondary events associated with spinal cord injury (SCI). Since oxidative stress is considered to play an important role in neuroinflammatory disorders, in the present work we studied a new composite, a formulation including PEA and the antioxidant compound luteolin (Lut), subjected to an ultramicronization process, co-ultraPEALut. We investigated the effect of co-ultraPEALut (in the respective fixed doses of 10:1 in mass) in both an ex vivo organotypic spinal cord culture model and an in vivo model of SCI.MethodsFor the organotypic cultures, spinal cords were prepared from mice at postnatal day 6 and were cut into transverse slices of 400 μm thickness to generate the lumbar organotypic slice cultures. After 7 days of culturing, the slices were mechanically injured onto the center of the slice and the co-ultraPEALut was applied at different concentrations (0.00009, 0.0009 and 0.009 g/l) 1 hour before damage. For in vivo studies, SCI was induced in mice through spinal cord compression by the application of vascular clips (force of 24 g) to the dura via a four-level T5 to T8 laminectomy, and co-ultraPEALut (1 mg/kg ip) was administered at 1 and 6 hours after SCI. At 24 hours after SCI, mice were sacrificed and the spinal cords were collected for further evaluation. Additional animals were treated similarly and sacrificed 10 days after SCI.ResultsPretreatment with co-ultraPEALut significantly reduced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression in a concentration-dependent manner, restored neuronal nitric oxide synthase (nNOS) expression at all three tested concentrations, and protected cells by cell death (MTT assay) in spinal cord organotypic cultures. Moreover, we demonstrated in vivo that co-ultraPEALut 1 mg/kg reduced the severity of trauma induced by compression and improved the motor activity evaluated at 10 days post-injury.ConclusionThe present study demonstrates that the protective effect of PEA on SCI-associated neuroinflammation could be improved by co-ultramicronization with Lut possibly due to its antioxidant properties.

P2X7 receptor‐induced death of motor neurons by a peroxynitrite/FAS‐dependent pathway

The P2X7 receptor/channel responds to extracellular ATP and is associated with neuronal death and neuroinflammation in spinal cord injury and amyotrophic lateral sclerosis. Whether activation of P2X7 directly causes motor neuron death is unknown. We found that cultured motor neurons isolated from embryonic rat spinal cord express P2X7 and underwent caspase-dependent apoptosis when exposed to exceptionally low concentrations of the P2X7 agonist 2'(3')-O-(4-Benzoylbenzoyl)-ATP. The P2X7 inhibitors BBG, oATP, and KN-62 prevented 2'(3')-O-(4-Benzoylbenzoyl)-ATP-induced motor neuron death. The endogenous P2X7 agonist ATP induced motor neuron death at low concentrations (1-100μM). High concentrations of ATP (1mM) paradoxically became protective due to degradation in the culture media to produce adenosine and activate adenosine receptors. P2X7-induced motor neuron death was dependent on neuronal nitric oxide synthase-mediated production of peroxynitrite, p38 activation, and autocrine FAS signaling. Taken together, our results indicate that motor neurons are highly sensitive to P2X7 activation, which triggers apoptosis by activation of the well-established peroxynitrite/FAS death pathway in motor neurons.

Immunoglobulin G: A Potential Treatment to Attenuate Neuroinflammation Following Spinal Cord Injury

IntroductionSpinal cord injury (SCI) is caused by two related but mechanistically distinct events: the primary injury to the spinal cord is caused by a mechanic trauma; the secondary injury is a cascade of cellular and molecular events that exacerbates the initial damage.Materials and MethodsNeuroinflammation, an important event in the secondary injury cascade, is critical in the clearance of cellular debris after SCI. However, leukocytes and microglia, recruited to the injury site during neuroinflammation, can exacerbate the initial damage following SCI by secreting reactive oxygen species, matrix-metalloproteinase, and proinflammatory cytokines. Therefore, attenuating the activity of leukocytes and microglia is an attractive therapeutic strategy to reduce the neurological deficit associated with SCI.DiscussionIn this regard, immunoglobulin G (IgG) is a potential treatment candidate. IgG has been used clinically to treat autoimmune disease and has been demonstrated to attenuate the activities of leukocytes and microglia. In this review, we discuss the potential use of IgG for SCI based on the current understanding of the immune-modulating mechanism of IgG and the role of neuroinflammation in SCI.

Depletion of Ly6G/Gr-1 Leukocytes after Spinal Cord Injury in Mice Alters Wound Healing and Worsens Neurological Outcome

Spinal cord injury (SCI) induces a robust inflammatory response and the extravasation of leukocytes into the injured tissue. To further knowledge of the functions of neuroinflammation in SCI in mice, we depleted the early arriving neutrophils using an anti-Ly6G/Gr-1 antibody. Complete blood counts revealed that neutrophils increased approximately 3-fold over uninjured controls and peaked at 6-12 h after injury, and that anti-Ly6G/Gr-1 treatment reduced circulating neutrophils by >90% at these time points. Intravital and spinning disk confocal microscopy of the exposed posterior vein and postcapillary venules showed a significant reduction in rolling and adhering neutrophils in vivo after anti-Ly6G/Gr-1 treatment; this was accompanied by a parallel reduction in neutrophil numbers within the injured spinal cord at 24 and 48 h as determined by flow cytometry. The evolution of astrocyte reactivity, a wound healing response, was reduced in anti-Ly6G/Gr-1-treated mice, which also had less spared white matter and axonal preservation compared with isotype controls. These histological outcomes may be caused by alterations of growth factors and chemokines important in promoting wound healing. Importantly, anti-Ly6G/Gr-1 treatment worsened behavioral outcome as determined using the Basso Mouse Scale and subscores. Although the spectrum of cells affected by anti-Ly6G/Gr-1 antibody treatment cannot be fully ascertained at this point, the correspondence of neutrophil depletion and worsened recovery suggests that neutrophils promote recovery after SCI through wound healing and protective events that limit lesion propagation.

Characterization of the Early Neuroinflammation After Spinal Cord Injury in Mice

The occurrence of neuroinflammation after spinal cord injury (SCI) is well established, but its function is debated, with both beneficial and detrimental consequences ascribed. A discriminate of the role of neuroinflammation may be the time period after SCI, and there is evidence to favor early neuroinflammation being undesirable, whereas the later evolving phase may have useful roles. Here, we have focused on the inflammatory response in the first 24 hours of SCI in mice. We found elevation of interleukin (IL)-1beta and other cytokines and chemokines within 15 minutes to 3 hours of injury. The early neuroinflammation in SCI is likely to be CNS-derived and involves microglia, as demonstrated by in situ hybridization for IL-1beta in microglia, by an in vitro model of SCI in which elevation of inflammatory cytokines occurs in the absence of a dynamic source of infiltrating leukocytes, and by the correlation of decreased levels of inflammatory molecules and microglia activity in IL-1beta-null mice. Nonetheless, as there are no specific immunohistochemical markers that clearly differentiate microglia from their peripheral counterparts, macrophages, the latter cannot be definitively excluded as participants in early neuroinflammation in mouse SCI. These results of an instantaneous inflammatory response validate approaches to modulate microglia/macrophage activity to improve recovery from SCI.