Trehalose Augments Neuron Survival and Improves Recovery from Spinal Cord Injury via mTOR-Independent Activation of Autophagy

Enhancing mitophagy by ligustilide through BNIP3-LC3 interaction attenuates oxidative stress-induced neuronal apoptosis in spinal cord injury

Mitophagy selectively eliminates damaged or dysfunctional mitochondria, playing a crucial role in maintaining mitochondrial quality control. However, it remains unclear whether mitophagy can be fully activated and how it evolves after SCI. Our RNA-seq analysis of animal samples from sham and 1, 3, 5, and 7 days post-SCI indicated that mitophagy was indeed inhibited during the acute and subacute early stages. In vitro experiments showed that this inhibition was closely related to excessive production of reactive oxygen species (ROS) and the downregulation of BNIP3. Excessive ROS led to the blockage of mitophagy flux, accompanied by further mitochondrial dysfunction and increased neuronal apoptosis. Fortunately, ligustilide (LIG) was found to have the ability to reverse the oxidative stress-induced downregulation of BNIP3 and enhance mitophagy through BNIP3-LC3 interaction, alleviating mitochondrial dysfunction and ultimately reducing neuronal apoptosis. Further animal experiments demonstrated that LIG alleviated oxidative stress and mitophagy inhibition, rescued neuronal apoptosis, and promoted tissue repair, ultimately leading to improved motor function. In summary, this study elucidated the state of mitophagy inhibition following SCI and its potential mechanisms, and confirmed the effects of LIG-enhanced mitophagy through BNIP3-LC3, providing new therapeutic targets and strategies for repairing SCI.

Injectable Hydrogel Loaded with CDs and FTY720 Combined with Neural Stem Cells for the Treatment of Spinal Cord Injury

Purpose

Spinal cord injury (SCI) is an incurable and disabling event that is accompanied by complex inflammation-related pathological processes, such as the production of excessive reactive oxygen species (ROS) by infiltrating inflammatory immune cells and their release into the extracellular microenvironment, resulting in extensive apoptosis of endogenous neural stem cells. In this study, we noticed the neuroregeneration-promoting effect as well as the ability of the innovative treatment method of FTY720-CDs@GelMA paired with NSCs to increase motor function recovery in a rat spinal cord injury model.

Methods

Carbon dots (CDs) and fingolimod (FTY720) were added to a hydrogel created by chemical cross-linking GelMA (FTY720-CDs@GelMA). The basic properties of FTY720-CDs@GelMA hydrogels were investigated using TEM, SEM, XPS, and FTIR. The swelling and degradation rates of FTY720-CDs@GelMA hydrogels were measured, and each group's ability to scavenge reactive oxygen species was investigated. The in vitro biocompatibility of FTY720-CDs@GelMA hydrogels was assessed using neural stem cells. The regeneration of the spinal cord and recovery of motor function in rats were studied following co-treatment of spinal cord injury using FTY720-CDs@GelMA hydrogel in combination with NSCs, utilising rats with spinal cord injuries as a model. Histological and immunofluorescence labelling were used to determine the regeneration of axons and neurons. The recovery of motor function in rats was assessed using the BBB score.

Results

The hydrogel boosted neurogenesis and axonal regeneration by eliminating excess ROS and restoring the regenerative environment. The hydrogel efficiently contained brain stem cells and demonstrated strong neuroprotective effects in vivo by lowering endogenous ROS generation and mitigating ROS-mediated oxidative stress. In a follow-up investigation, we discovered that FTY720-CDs@GelMA hydrogel could dramatically boost NSC proliferation while also promoting neuronal regeneration and synaptic formation, hence lowering cavity area.

Conclusion

Our findings suggest that the innovative treatment of FTY720-CDs@GelMA paired with NSCs can effectively improve functional recovery in SCI patients, making it a promising therapeutic alternative for SCI.

UBC9-mediated SUMOylation of Lamin B1 enhances DNA-damage-induced nuclear DNA leakage and autophagy after spinal cord injury

Recent studies have shown that nucleophagy can mitigate DNA damage by selectively degrading nuclear components protruding from the nucleus. However, little is known about the role of nucleophagy in neurons after spinal cord injury (SCI). Western blot analysis and immunofluorescence were performed to evaluate the nucleophagy after nuclear DNA damage and leakage in SCI neurons in vivo and NSC34 expression in primary neurons cultured with oxygen-glucose deprivation (OGD) in vitro, as well as the interaction and colocalization of autophagy protein LC3 with nuclear lamina protein Lamin B1. The effect of UBC9, a Small ubiquitin-related modifier (SUMO) E2 ligase, on Lamin B1 SUMOylation and nucleophagy was examined by siRNA transfection or 2-D08 (a small-molecule inhibitor of UBC9), immunoprecipitation, and immunofluorescence. In SCI and OGD injured NSC34 or primary cultured neurons, neuronal nuclear DNA damage induced the SUMOylation of Lamin B1, which was required by the nuclear Lamina accumulation of UBC9. Furthermore, LC3/Atg8, an autophagy-related protein, directly bound to SUMOylated Lamin B1, and delivered Lamin B1 to the lysosome. Knockdown or suppression of UBC9 with siRNA or 2-D08 inhibited SUMOylation of Lamin B1 and subsequent nucleophagy and protected against neuronal death. Upon neuronal DNA damage and leakage after SCI, SUMOylation of Lamin B1 is induced by nuclear Lamina accumulation of UBC9. Furthermore, it promotes LC3-Lamin B1 interaction to trigger nucleophagy that protects against neuronal DNA damage.

DADLE promotes motor function recovery by inhibiting cytosolic phospholipase A2 mediated lysosomal membrane permeabilization after spinal cord injury

BACKGROUND AND PURPOSE

Autophagy is a protective factor for controlling neuronal damage, while necroptosis promotes neuroinflammation after spinal cord injury (SCI). DADLE (D-Ala2 , D-Leu5 ]-enkephalin) is a selective agonist for delta (δ) opioid receptor and has been identified as a promising drug for neuroprotection. The aim of this study was to investigate the mechanism/s by which DADLE causes locomotor recovery following SCI.

EXPERIMENTAL APPROACH

Spinal cord contusion model was used and DADLE was given by i.p. (16 mg·kg-1 ) in mice for following experiments. Motor function was assessed by footprint and Basso mouse scale (BMS) score analysis. Western blotting used to evaluate related protein expression. Immunofluorescence showed the protein expression in each cell and its distribution. Network pharmacology analysis was used to find the related signalling pathways.

KEY RESULTS

DADLE promoted functional recovery after SCI. In SCI model of mice, DADLE significantly increased autophagic flux and inhibited necroptosis. Concurrently, DADLE restored autophagic flux by decreasing lysosomal membrane permeabilization (LMP). Additionally, chloroquine administration reversed the protective effect of DADLE to inhibit necroptosis. Further analysis showed that DADLE decreased phosphorylated cPLA2 , overexpression of cPLA2 partially reversed DADLE inhibitory effect on LMP and necroptosis, as well as the promotion autophagy. Finally, AMPK/SIRT1/p38 pathway regulating cPLA2 is involved in the action DADLE on SCI and naltrindole inhibited DADLE action on δ receptor and on AMPK signalling pathway.

CONCLUSION AND IMPLICATION

DADLE causes its neuroprotective effects on SCI by promoting autophagic flux and inhibiting necroptosis by decreasing LMP via activating δ receptor/AMPK/SIRT1/p38/cPLA2 pathway.

Targeting ANXA7/LAMP5-mTOR axis attenuates spinal cord injury by inhibiting neuronal apoptosis via enhancing autophagy in mice

Spinal cord injury (SCI) could lead to severe disabilities in motor and sensory functions, and cause a heavy burden on patient physiology and psychology due to lack of specific repair measures so far. ANXA7 is an annexin with Ca2+ -dependent GTPase activity, which were mainly expressed in neuron in spinal cord and downregulated significantly after SCI in mice. In our study, GTPase activity activation of ANXA7 plays the protective role in neuron after OGD/R through inhibiting neuron apoptosis, which mediated by enhancing autophagy via mTOR/TFEB pathway. We also discovered that ANXA7 has significant interaction with neural-specific lysosomal-associated membrane protein LAMP5, which together with ANXA7 regulates autophagy and apoptosis. Asp411 mutation of ANXA7 obviously impaired the interaction of ANXA7 and LAMP5 compared with the wild type. Furthermore, it was found that activation of ANXA7 could help to stabilize the protein expression of LAMP5. Overexpression of LAMP5 could attenuate the destruction of lysosomal acidic environment, inhibition of autophagy and activation of apoptosis caused by ANXA7 downregulation after OGD/R. We verified that injecting ANXA7 overexpression lentivirus and activation of ANXA7 both have significant repair effects on SCI mice by using CatWalk assay and immunohistochemistry staining. In summary, our findings clarify the new role of ANXA7 and LAMP5 in SCI, provided a new specific target of neuronal repair and discovered new molecular mechanisms of ANXA7 to regulate autophagy and apoptosis. Targeting ANXA7 may be a prospective therapeutic strategy for SCI in future.

Neuroprotective Effects of Oxymatrine via Triggering Autophagy and Inhibiting Apoptosis Following Spinal Cord Injury in Rats

Spinal cord injury (SCI) is a devastating neurological disorder characterized by high morbidity and disability. However, there is still a lack of effective treatments for it. The identification of drugs that promote autophagy and inhibit apoptosis in neurons is critical for improving patient outcomes following SCI. Previous studies have shown that increasing the activity of silent information regulator 1 (SIRT1) and downstream protein AMP-activated protein kinase (AMPK) in rat models of SCI is highly neuroprotective. Oxymatrine (OMT), a quinolizidine alkaloid, has exhibited neuroprotective effects in various central nervous system (CNS) diseases. However, its explicit effect and molecular mechanism in SCI are still unclear. Herein, we aimed to investigate the therapeutic effects of OMT and explore the potential role of autophagy regulation following SCI in rats. A modified compressive device (weight 35 g, time 5 min) was applied to induce moderate SCI in all groups except the sham group. After treatment with drugs or vehicle (saline), our results indicated that OMT treatment significantly reduced the lesion size, promoted survival of motor neurons, and subsequently attenuated motor dysfunction following SCI in rats. OMT significantly enhanced autophagy activity, inhibited apoptosis in neurons, and increased SIRT1 and p-AMPK expression levels. Interestingly, these effects of OMT on SCI were partially prevented by co-treatment with SIRT1 inhibitor EX527. Furthermore, combining OMT with the potent autophagy inhibitor chloroquine (CQ) could effectively abolish its promotion of autophagic flux. Taken together, these data revealed that OMT exerts a neuroprotective role in functional recovery against SCI in rats, and these effects are potentially associated with OMT-induced activation of autophagy via the SIRT1/AMPK signaling pathway.

Therapeutic potential of natural compounds from herbs and nutraceuticals in spinal cord injury: Regulation of the mTOR signaling pathway

Spinal cord injury (SCI) is a disease in which the spinal cord is subjected to various external forces that cause it to burst, shift, or, in severe cases, injure the spinal tissue, resulting in nerve injury. SCI includes not only acute primary injury but also delayed and persistent spinal tissue injury (i.e., secondary injury). The pathological changes post-SCI are complex, and effective clinical treatment strategies are lacking. The mammalian target of rapamycin (mTOR) coordinates the growth and metabolism of eukaryotic cells in response to various nutrients and growth factors. The mTOR signaling pathway has multiple roles in the pathogenesis of SCI. There is evidence for the beneficial effects of natural compounds and nutraceuticals that regulate the mTOR signaling pathways in a variety of diseases. Therefore, the effects of natural compounds on the pathogenesis of SCI were evaluated by a comprehensive review using electronic databases, such as PubMed, Web of Science, Scopus, and Medline, combined with our expertise in neuropathology. In particular, we reviewed the pathogenesis of SCI, including the importance of secondary nerve injury after the primary mechanical injury, the roles of the mTOR signaling pathways, and the beneficial effects and mechanisms of natural compounds that regulate the mTOR signaling pathway on pathological changes post-SCI, including effects on inflammation, neuronal apoptosis, autophagy, nerve regeneration, and other pathways. This recent research highlights the value of natural compounds in regulating the mTOR pathway, providing a basis for developing novel therapeutic strategies for SCI.

Multiple mechanisms of curcumin targeting spinal cord injury

Spinal cord injury (SCI) is an irreversible disease process with a high disability and mortality rate. After primary spinal cord injury, the secondary injury may occur in sequence, which is composed of ischemia and hypoxia, excitotoxicity, calcium overload, oxidative stress and inflammation, resulting in massive death of parenchymal cells in the injured area, followed by the formation of syringomyelia. Effectively curbing the process of secondary injury can promote nerve repair and improve functional prognosis. As the main active ingredient in turmeric, curcumin can play an important role in reducing inflammation and oxidation, protecting the neurons, and ultimately reducing spinal cord injury. This article reviews the effects of curcumin on the repair of nerve injury, with emphasis on the various mechanisms by which curcumin promotes the treatment of spinal cord injury.

Identification of the CCL2 PI3K/Akt axis involved in autophagy and apoptosis after spinal cord injury

Spinal cord injury (SCI) is a devastating neurological disease with no cure that usually results in irreversible loss of sensory and voluntary motor functions below the injury site. We conducted an in-depth bioinformatics analysis combining the gene expression omnibus spinal cord injury database and the autophagy database and found that the expression of the autophagy gene CCL2 was significantly upregulated and the PI3K/Akt/mTOR signaling pathway was activated after SCI. The results of the bioinformatics analysis were verified by constructing animal and cellular models of SCI. We then used small interfering RNA to inhibit the expression of CCL2 and PI3K to inhibit and activate the PI3K/Akt/mTOR signaling pathway; western blot, immunofluorescence, monodansylcadaverine, and cell flow techniques were used to detect the expression of key proteins involved in downstream autophagy and apoptosis. We found that when PI3K inhibitors were activated, apoptosis decreased, the levels of autophagy-positive proteins LC3-I/LC3-II and Bcl-1 increased, the levels of autophagy-negative protein P62 decreased, the levels of pro-apoptotic proteins Bax and caspase-3 decreased, the levels of the apoptosis-inhibiting protein Bcl-2 increased. In contrast, when a PI3K activator was used, autophagy was inhibited, and apoptosis was increased. This study revealed the effect of CCL2 on autophagy and apoptosis after SCI through the PI3K/Akt/mTOR signaling pathway. By blocking the expression of the autophagy-related gene CCL2, the autophagic protective response can be activated, and apoptosis can be inhibited, which may be a promising strategy for the treatment of SCI.

Ca2+ Regulates Autophagy Through CaMKKβ/AMPK/mTOR Signaling Pathway in Mechanical Spinal cord Injury: An in vitro Study

Spinal cord injury (SCI), resulting in damage of the normal structure and function of the spinal cord, would do great harm to patients, physically and psychologically. The mechanism of SCI is very complex. At present, lots of studies have reported that autophagy was involved in the secondary injury process of SCI, and several researchers also found that calcium ions (Ca²⁺) played an important role in SCI by regulating necrosis, autophagy, or apoptosis. However, to our best of knowledge, no studies have linked the spinal cord mechanical injury, intracellular Ca²⁺, and autophagy in series. In this study, we have established an in vitro model of SCI using neural cells from fetal rats to explore the relationship among them, and found that mechanical injury could promote the intracellular Ca²⁺ concentration, and the increased Ca²⁺ level activated autophagy through the CaMKKβ/AMPK/mTOR pathway. Additionally, we found that apoptosis was also involved in this pathway. Thus, our study provides new insights into the specific mechanisms of SCI and may open up new avenues for the treatment of SCI.

Disaccharide Trehalose in Experimental Therapies for Neurodegenerative Disorders: Molecular Targets and Translational Potential

Induction of autophagy is a prospective approach to the treatment of neurodegeneration. In the recent decade, trehalose attracted special attention. It is an autophagy inducer with negligible adverse effects and is approved for use in humans according to FDA requirements. Trehalose has a therapeutic effect in various experimental models of diseases. This glucose disaccharide with a flexible α-1-1'-glycosidic bond has unique properties: induction of mTOR-independent autophagy (with kinase AMPK as the main target) and a chaperone-like effect on proteins imparting them natural spatial structure. Thus, it can reduce the accumulation of neurotoxic aberrant/misfolded proteins. Trehalose has an anti-inflammatory effect and inhibits detrimental oxidative stress partially owing to the enhancement of endogenous antioxidant defense represented by the Nrf2 protein. The disaccharide activates lysosome and autophagosome biogenesis pathways through the protein factors TFEB and FOXO1. Here we review various mechanisms of the neuroprotective action of trehalose and touch on the possibility of pleiotropic effects. Current knowledge about specific features of trehalose pharmacodynamics is discussed. The neuroprotective effects of trehalose in animal models of major neurodegenerative disorders such as Alzheimer's, Parkinson's, and Huntington's diseases are examined too. Attention is given to translational transition to clinical trials of this drug, especially oral and parenteral routes of administration. Besides, the possibility of enhancing the therapeutic benefit via a combination of mTOR-dependent and mTOR-independent autophagy inducers is analyzed. In general, trehalose appears to be a promising multitarget tool for the inhibition of experimental neurodegeneration and requires thorough investigation of its clinical capabilities.

Numb Promotes Autophagy through p53 Pathway in Acute Kidney Injury Induced by Cisplatin

Acute kidney injury (AKI) is an important public health concern and characterized as tubular death involved in apoptosis and necrosis. Autophagy is rapidly induced in tubules and associates with renal tubular cells homeostasis to have a complex link with tubular death in AKI. Numb is a multifunctional protein and exerts protective role in tubular death in AKI induced by Cisplatin. However, the effect of Numb on tubular autophagy remains to be investigated. In the present study, the protein expression of LC3 and Beclin-1 related to autophagy was analyzed in Cisplatin-induced AKI mice with knocking down Numb. In model of tubular injury induced by Cisplatin in vitro, downregulation of Numb in NRK-52E cells also inhibited the activation of autophagy accompanied with the decreased protein level of p53. Overexpression of Numb in NRK-52E cells activated autophagy with increased LC3 and Beclin-1 expression accompanied with increased protein level of p53. Moreover, autophagy activation following Numb overexpression was suppressed by p53 inhibitor pifithrin-α. These data indicate that Numb promotes p53-mediated activation of tubular autophagy in AKI induced by Cisplatin and therefore may provide important targets for the treatment of AKI.

Quercetin Can Improve Spinal Cord Injury by Regulating the mTOR Signaling Pathway

The pathogenesis of spinal cord injury (SCI) is complex. At present, there is no effective treatment for SCI, with most current interventions focused on improving the symptoms. Inflammation, apoptosis, autophagy, and oxidative stress caused by secondary SCI may instigate serious consequences in the event of SCI. The mammalian target of rapamycin (mTOR), as a key signaling molecule, participates in the regulation of inflammation, apoptosis, and autophagy in several processes associated with SCI. Quercetin can reduce the loss of myelin sheath, enhance the ability of antioxidant stress, and promote axonal regeneration. Moreover, quercetin is also a significant player in regulating the mTOR signaling pathway that improves pathological alterations following neuronal injury. Herein, we review the therapeutic effects of quercetin in SCI through its modulation of the mTOR signaling pathway and elaborate on how it can be a potential interventional agent for SCI.

Strategies for Biomaterial-Based Spinal Cord Injury Repair via the TLR4-NF-κB Signaling Pathway

The repair and motor functional recovery after spinal cord injury (SCI) has remained a clinical challenge. Injury-induced gliosis and inflammation lead to a physical barrier and an extremely inhibitory microenvironment, which in turn hinders the recovery of SCI. TLR4-NF-κB is a classic implant-related innate immunomodulation signaling pathway and part of numerous biomaterial-based treatment strategies for SCI. Numerous experimental studies have demonstrated that the regulation of TLR4-NF-κB signaling pathway plays an important role in the alleviation of inflammatory responses, the modulation of autophagy, apoptosis and ferroptosis, and the enhancement of anti-oxidative effect post-SCI. An increasing number of novel biomaterials have been fabricated as scaffolds and carriers, loaded with phytochemicals and drugs, to inhibit the progression of SCI through regulation of TLR4-NF-κB. This review summarizes the empirical strategies for the recovery after SCI through individual or composite biomaterials that mediate the TLR4-NF-κB signaling pathway.

Trehalose inhibits ferroptosis via NRF2/HO-1 pathway and promotes functional recovery in mice with spinal cord injury

Spinal cord injury (SCI) is the main cause of severe damage to the central nervous system and leads to irreversible tissue loss and neurological dysfunction. Ferroptosis is a cell death pattern, newly discovered in recent years. Ferroptosis is an oxidizing cell death induced by small molecules, and is an iron-dependent process caused by the imbalance between the generation and degradation of lipid reactive oxygen species (ROS) in cells. As an antioxidant, trehalose can effectively prevent lipid peroxidation. Studies have reported that trehalose can improve the prognosis of SCI. However, it is unclear whether these benefits are related to ferroptosis. In this study, we demonstrated for the first time that trehalose reduces the degeneration and iron accumulation of neurons by inhibiting the production of ROS and ferroptosis caused by lipid peroxides after SCI, thus promoting the survival of neurons and improving the recovery of motor function. More specifically, we found that trehalose inhibited the expansion of cavities in the nerve tissue of mice with SCI, inhibited neuron loss, and improved functional recovery. In terms of mechanism, our results indicate that the neuroprotective effect of trehalose is due to the activation of the NRF2/HO-1 pathway, which in turn inhibits ferroptosis and ferroptosis-related inflammation. Our findings provide important insights into the previously unknown role of trehalose in SCI, as well as new evidence supporting the hypothesis that suppression of ferroptosis plays a key neuroprotective role in SCI.