The Function and Mechanisms of Autophagy in Spinal Cord Injury

Bibliometric analysis of the inflammation expression after spinal cord injury: current research status and emerging frontiers

STUDY DESIGN

Bibliometric analysis.

OBJECTIVE

To analyze literature on inflammatory expression following spinal cord injury, highlighting development trends, current research status, and potential emerging frontiers.

SETTING

Not applicable.

METHODS

Articles were retrieved using terms related to spinal cord injury and inflammatory responses from the Web of Science Core Collection, covering January 1, 1980, to May 23, 2024. Tools like CiteSpace and VOSviewer assessed the research landscape, evaluating core authors, journals, and contributing countries. Keyword co-occurrence analyses identified research trends.

RESULTS

A total of 2504 articles were retrieved, showing a consistent increase in publications. The Journal of Neurotrauma had the highest publication volume and influence. The most prolific author was Cuzzocrea S, with Popovich PG having the highest H-index. China led in the number of publications, followed closely by the United States, which had the highest impact and extensive international collaboration. Research mainly focused on nerve function recovery, glial scar formation, and oxidative stress. Future research is expected to investigate cellular autophagy, vesicular transport, and related signaling pathways.

CONCLUSION

The growing interest in inflammation caused by spinal cord injury is evident, with current research focusing on oxidative stress, glial scar, and neurological recovery. Future directions include exploring autophagy and extracellular vesicles for new therapies. Interdisciplinary research and extensive clinical trials are essential for validating new treatments. Biomarker discovery is crucial for diagnosis and monitoring, while understanding autophagy and signaling pathways is vital for drug development. Global cooperation is needed to accelerate the application of scientific findings, improving spinal cord injury treatment.

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.

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.

Upregulation of RAB7 is related to neuronal pyroptosis after spinal cord injury in rats

Rab7 belongs to the Ras small GTPase superfamily, and abnormal expression of Rab7 can cause neuropathy and lipid metabolism diseases. Studies have shown that Rab7 plays a crucial role in the inner membrane translocase. However, the role of Rab7 in the regulatory mechanisms of cell survival in spinal cord injury remains unknown. We used a rat spinal cord injury (SCI) model to explore the cellular localization and expression of Rab7 after SCI in this study. Western blot analysis showed that Rab7 was expressed in the spinal cord tissue. On the first day, it significantly increased and peaked after SCI on the third day. Furthermore, western blotting also demonstrated that pyroptosis-related protein Gasdermin D (GSDMD), Caspase-1, apoptosis-associated speck-like protein (ASC) expression peaked after the third-day post-injury. Importantly, the immunohistochemistry analysis revealed that Rab7 was completely colocalized with ASC in neurons after SCI. These results suggested that Rab7 was colocalized with NeuN and ASC, involved in the pyroptosis of neurons, and closely related to the spinal cord after injury.

Advances in molecular therapies for targeting pathophysiology in spinal cord injury

INTRODUCTION

Spinal cord injury (SCI) affects 25,000-50,000 people around the world each year and there is no cure for SCI patients currently. The primary injury damages spinal cord tissues and secondary injury mechanisms, including ischemia, apoptosis, inflammation, and astrogliosis, further exacerbate the lesions to the spinal cord. Recently, researchers have designed various therapeutic approaches for SCI by targeting its major cellular or molecular pathophysiology.

AREAS COVERED

Some strategies have shown promise in repairing injured spinal cord for functional recoveries, such as administering neuroprotective reagents, targeting specific genes to promote robust axon regeneration of disconnected spinal fiber tracts, targeting epigenetic factors to enhance cell survival and neural repair, and facilitating neuronal relay pathways and neuroplasticity for restoration of function after SCI. This review focuses on the major advances in preclinical molecular therapies for SCI reported in recent years.

EXPERT OPINION

Recent progress in developing novel and effective repairing strategies for SCI is encouraging, but many challenges remain for future design of effective treatments, including developing highly effective neuroprotectants for early interventions, stimulating robust neuronal regeneration with functional synaptic reconnections among disconnected neurons, maximizing the recovery of lost neural functions with combination strategies, and translating the most promising therapies into human use.

Biological Functions and Therapeutic Potential of Autophagy in Spinal Cord Injury

Autophagy is an evolutionarily conserved lysosomal degradation pathway that maintains metabolism and homeostasis by eliminating protein aggregates and damaged organelles. Many studies have reported that autophagy plays an important role in spinal cord injury (SCI). However, the spatiotemporal patterns of autophagy activation after traumatic SCI are contradictory. Most studies show that the activation of autophagy and inhibition of apoptosis have neuroprotective effects on traumatic SCI. However, reports demonstrate that autophagy is strongly associated with distal neuronal death and the impaired functional recovery following traumatic SCI. This article introduces SCI pathophysiology, the physiology and mechanism of autophagy, and our current review on its role in traumatic SCI. We also discuss the interaction between autophagy and apoptosis and the therapeutic effect of activating or inhibiting autophagy in promoting functional recovery. Thus, we aim to provide a theoretical basis for the biological therapy of SCI.

Quercetin promotes locomotor function recovery and axonal regeneration through induction of autophagy after spinal cord injury

Quercetin (Que), one of the flavonoids, exerts numerous actions on the central nervous system. However, the roles and underlying mechanism of Que in locomotor function recovery and axonal regeneration following spinal cord injury (SCI) have not been fully elucidated. A rat model of spinal cord injury (SCI) was established at T10 using the modified Allen's method. The results in our study indicated that Basso, Beattie and Bresnahan (BBB) locomotor scores were significantly higher after Que treatment. Additionally, Que administration cut down the latency of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP), increased the amplitude of MEP and SEP following SCI. Hematoxylin-eosin (HE) staining demonstrated that Que administration reduced lesion size and cavity formation. Biotinylated dextran amine (BDA) anterograde tracing revealed that BDA positive fibres were increased by Que following SCI. Immunofluorescence staining revealed that Que elevated 5-hydroxytryptamine (5-HT) positive nerve fibres and neurofilament-200 (NF-200) positive neurons, reduced glial fibrillary acidic protein (GFAP) positive astrocytes. In addition, Que inhibited GFAP expression, increased both NeuN and NF-200 expression and facilitated the spinal cord energy metabolism. Moreover, Que increased 18 F-FDG uptake in a time-dependent manner. Furthermore, Que increased Beclin 1 and LC3 II expression, blocked the phosphorylation of Akt, mTOR and p70S6K. 3-methyladenine (3-MA) partly abolished the neuro-protective roles of Que following SCI. Taken together, our study suggested that Que might promote locomotor function recovery, axonal regeneration and energy metabolism through induction of autophagy via Akt/mTOR/p70S6K pathway.

Lysine-specific demethylase 1 inhibition enhances autophagy and attenuates early-stage post-spinal cord injury apoptosis

Neuron death in spinal cords is caused primarily by apoptosis after spinal cord injury (SCI). Autophagy can act as a cellular response to maintain neuron homeostasis that can reduce apoptosis. Although more studies have shown that an epigenetic enzyme called Lysine-specific demethylase 1 (LSD1) can negatively regulate autophagy during cancer research, existing research does not focus on impacts related to LSD1 in nerve injury diseases. This study was designed to determine whether inhibiting LSD1 could enhance autophagy against apoptosis and provide effective neuroprotection in vitro and vivo after SCI. The results showed that LSD1 inhibition treatment significantly reduced spinal cord damage in SCI rat models and was characterized by upregulated autophagy and downregulated apoptosis. Further research demonstrated that using both pharmacological inhibition and gene knockdown could enhance autophagy and reduce apoptosis for in vitro simulation of SCI-caused damage models. Additionally, 3-methyladenine (3-MA) could partially eliminate the effect of autophagy enhancement and apoptosis suppression. These findings demonstrated that LSD1 inhibition could protect against SCI by activating autophagy and hindering apoptosis, suggesting a potential candidate for SCI therapy.