Sirtuins: Potential Therapeutic Targets for Defense against Oxidative Stress in Spinal Cord Injury

The effects of hyaluronan and proteoglycan link protein 1 (HAPLN1) in ameliorating spinal cord injury mediated by Nrf2

Excessive inflammatory response and oxidative stress (OS) play an important role in the pathogenesis of spinal cord injury (SCI). Balance of inflammation and prevention of OS have been considered an effective strategy for the treatment of SCI. Hyaluronan and proteoglycan link protein 1 (HAPLN1), also known as cartilage link protein, has displayed a wide range of biological and physiological functions in different types of tissues and cells. However, whether HAPLN1 regulates inflammation and OS during SCI is unknown. Therefore, we aimed to examine whether HAPLN1 can have a protective effect on SCI. In this study, both in vitro and in vivo SCI models were established. Nissl staining and terminal deoxynucleotidyl transferase dUTP nick end labeling staining assays were used. Western blotting and enzyme-linked immunosorbent assay were employed to assess the expression of proteins. Our results demonstrate that the administration of HAPLN1 promoted the recovery of motor neurons after SCI by increasing the Basso mouse scale score, increasing the numbers of motor neurons, and preventing apoptosis of spinal cord cells. Additionally, HAPLN1 mitigated OS in spinal cord tissue after SCI by increasing the content of superoxide dismutase SOD and the activity of glutathione peroxidase but reducing the levels of malondialdehyde. Importantly, we found that HAPLN1 stimulated the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway and stimulated the expression of heme oxygenase-1 and nicotinamide adenine dinucleotide phosphate quinone oxidoreductase-1, which mediated the attenuation of HAPLN1 in activation of the NOD-like receptor protein 3 (NLRP3) inflammasome by reducing the levels of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, and interleukin-1β. Correspondingly, in vitro experiments show that the presence of HAPLN1 suppressed the NLRP3 inflammasome and prevented cell injury against H2O2 in PC12 cells. These effects were mediated by the Nrf2/ARE pathway, and inhibition of Nrf2 with ML385 abolished the beneficial effects of HAPLN1. Based on these findings, we conclude that HAPLN1 inhibits the NLRP3 inflammasome through the stimulation of the Nrf2/ARE pathway, thereby suppressing neuroinflammation, enhancing motor neuronal survival, and improving the recovery of nerve function after SCI.

Redox signaling and skeletal muscle adaptation during aerobic exercise

Redox regulation is a fundamental physiological phenomenon related to oxygen-dependent metabolism, and skeletal muscle is mainly regarded as a primary site for oxidative phosphorylation. Several studies have revealed the importance of reactive oxygen and nitrogen species (RONS) in the signaling process relating to muscle adaptation during exercise. To date, improving knowledge of redox signaling in modulating exercise adaptation has been the subject of comprehensive work and scientific inquiry. The primary aim of this review is to elucidate the molecular and biochemical pathways aligned to RONS as activators of skeletal muscle adaptation and to further identify the interconnecting mechanisms controlling redox balance. We also discuss the RONS-mediated pathways during the muscle adaptive process, including mitochondrial biogenesis, muscle remodeling, vascular angiogenesis, neuron regeneration, and the role of exogenous antioxidants.

Mertk Reduces Blood-Spinal Cord Barrier Permeability Through the Rhoa/Rock1/P-MLC Pathway After Spinal Cord Injury

Disruption of the blood-spinal cord barrier (BSCB) is a critical event in the secondary injury following spinal cord injury (SCI). Mertk has been reported to play an important role in regulating inflammation and cytoskeletal dynamics. However, the specific involvement of Mertk in BSCB remains elusive. Here, we demonstrated a distinct role of Mertk in the repair of BSCB. Mertk expression is decreased in endothelial cells following SCI. Overexpression of Mertk upregulated tight junction proteins (TJs), reducing BSCB permeability and subsequently inhibiting inflammation and apoptosis. Ultimately, this led to enhanced neural regeneration and functional recovery. Further experiments revealed that the RhoA/Rock1/P-MLC pathway plays a key role in the effects of Mertk. These findings highlight the role of Mertk in promoting SCI recovery through its ability to mitigate BSCB permeability and may provide potential targets for SCI repair.

Sirtuins as Players in the Signal Transduction of Citrus Flavonoids

Sirtuins (SIRTs) belong to the family of nicotine adenine dinucleotide (NAD+)-dependent class III histone deacetylases, which come into play in the regulation of epigenetic processes through the deacetylation of histones and other substrates. The human genome encodes for seven homologs (SIRT1-7), which are localized into the nucleus, cytoplasm, and mitochondria, with different enzymatic activities and regulatory mechanisms. Indeed, SIRTs are involved in different physio-pathological processes responsible for the onset of several human illnesses, such as cardiovascular and neurodegenerative diseases, obesity and diabetes, age-related disorders, and cancer. Nowadays, it is well-known that Citrus fruits, typical of the Mediterranean diet, are an important source of bioactive compounds, such as polyphenols. Among these, flavonoids are recognized as potential agents endowed with a wide range of beneficial properties, including antioxidant, anti-inflammatory, hypolipidemic, and antitumoral ones. On these bases, we offer a comprehensive overview on biological effects exerted by Citrus flavonoids via targeting SIRTs, which acted as modulator of several signaling pathways. According to the reported studies, Citrus flavonoids appear to be promising SIRT modulators in many different pathologies, a role which might be potentially evaluated in future therapies, along with encouraging the study of those SIRT members which still lack proper evidence on their support.

Engineered Multifunctional Zinc-Organic Framework-Based Aggregation-Induced Emission Nanozyme for Accelerating Spinal Cord Injury Recovery

Functional recovery following a spinal cord injury (SCI) is challenging. Traditional drug therapies focus on the suppression of immune responses; however, strategies for alleviating oxidative stress are lacking. Herein, we developed the zinc-organic framework (Zn@MOF)-based aggregation-induced emission-active nanozymes for accelerating recovery following SCI. A multifunctional Zn@MOF was modified with the aggregation-induced emission-active molecule 2-(4-azidobutyl)-6-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)-1H-phenalene-1,3-dione via a bioorthogonal reaction, and the resulting nanozymes were denoted as Zn@MOF-TPD. These nanozymes gradually released gallic acid and zinc ions (Zn2+) at the SCI site. The released gallic acid, a scavenger of reactive oxygen species (ROS), promoted antioxidation and alleviated inflammation, re-establishing the balance between ROS production and the antioxidant defense system. The released Zn2+ ions inhibited the activity of matrix metalloproteinase 9 (MMP-9) to facilitate the regeneration of neurons via the ROS-mediated NF-κB pathway following secondary SCI. In addition, Zn@MOF-TPD protected neurons and myelin sheaths against trauma, inhibited glial scar formation, and promoted the proliferation and differentiation of neural stem cells, thereby facilitating the repair of neurons and injured spinal cord tissue and promoting functional recovery in rats with contusive SCI. Altogether, this study suggests that Zn@MOF-TPD nanozymes possess a potential for alleviating oxidative stress-mediated pathophysiological damage and promoting motor recovery following SCI.

Pregnane X receptor (PXR) deficiency protects against spinal cord injury by activating NRF2/HO-1 pathway

INTRODUCTION

As a devastating neurological disease, spinal cord injury (SCI) results in severe tissue loss and neurological dysfunction. Pregnane X receptor (PXR) is a ligand-activated nuclear receptor with a major regulatory role in xenobiotic and endobiotic metabolism and recently has been implicated in the central nervous system. In the present study, we aimed to investigate the role and mechanism of PXR in SCI.

METHODS

The clip-compressive SCI model was performed in male wild-type C57BL/6 (PXR+/+ ) and PXR-knockout (PXR-/- ) mice. The N2a H2 O2 -induced injury model mimicked the pathological process of SCI in vitro. Pregnenolone 16α-carbonitrile (PCN), a mouse-specific PXR agonist, was used to activate PXR in vivo and in vitro. The siRNA was applied to knock down the PXR expression in vitro. Transcriptome sequencing analysis was performed to discover the relevant mechanism, and the NRF2 inhibitor ML385 was used to validate the involvement of PXR in influencing the NRF2/HO-1 pathway in the SCI process.

RESULTS

The expression of PXR decreased after SCI and reached a minimum on the third day. In vivo, PXR knockout significantly improved the motor function of mice after SCI, meanwhile, inhibited apoptosis, inflammation, and oxidative stress induced by SCI. On the contrary, activation of PXR by PCN negatively influenced the recovery of SCI. Mechanistically, transcriptome sequencing analysis revealed that PXR activation downregulated the mRNA level of heme oxygenase-1 (HO-1) after SCI. We further verified that PXR deficiency activated the NRF2/HO-1 pathway and PXR activation inhibited this pathway in vitro.

CONCLUSION

PXR is involved in the recovery of motor function after SCI by regulating NRF2/HO-1 pathway.

Encapsulation of Selenium Nanoparticles and Metformin in Macrophage-Derived Cell Membranes for the Treatment of Spinal Cord Injury

Spinal cord injury is an impact-induced disabling condition. A series of pathological changes after spinal cord injury (SCI) are usually associated with oxidative stress, inflammation, and apoptosis. These pathological changes eventually lead to paralysis. The short half-life and low bioavailability of many drugs also limit the use of many drugs in SCI. In this study, we designed nanovesicles derived from macrophages encapsulating selenium nanoparticles (SeNPs) and metformin (SeNPs-Met-MVs) to be used in the treatment of SCI. These nanovesicles can cross the blood-spinal cord barrier (BSCB) and deliver SeNPs and Met to the site of injury to exert anti-inflammatory and reactive oxygen species scavenging effects. Transmission electron microscopy (TEM) images showed that the SeNPs-Met-MVs particle size was approximately 125 ± 5 nm. Drug release assays showed that Met exhibited sustained release after encapsulation by the macrophage cell membrane. The cumulative release was approximately 80% over 36 h. In vitro cellular experiments and in vivo animal experiments demonstrated that SeNPs-Met-MVs decreased reactive oxygen species (ROS) and malondialdehyde (MDA) levels, increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities, and reduced the expression of inflammatory (TNF-α, IL-1β, and IL-6) and apoptotic (cleaved caspase-3) cytokines in spinal cord tissue after SCI. In addition, motor function in mice was significantly improved after SeNPs-Met-MVs treatment. Therefore, SeNPs-Met-MVs have a promising future in the treatment of SCI.

The crosstalk between Nrf2 and NF-κB pathways in coronary artery disease: Can it be regulated by SIRT6?

Coronary artery disease (CAD) is the leading cause of death worldwide. Oxidative stress and inflammation are major mechanisms responsible for the progression of CAD. Nuclear transcription factor erythroid-2 related factor 2 (Nrf2) is a transcription factor that modulates the cellular redox status. Nrf2 upregulation increases the expression of antioxidant genes, decreases the expression of Nuclear factor-kappa B (NF-kB), and increases free radical metabolism. Activated NF-kB increases the production of inflammatory cytokines causing endothelial dysfunction. The two pathways of Nrf2 and NF-kB can regulate the expression of each other. Foremost, the Nrf2 pathway can decrease the level of active NF-κB by increasing the level of antioxidants and cytoprotective enzymes. Furthermore, the Nrf2 pathway prevents IκB-α degradation, an inhibitor of NF-kB, and thus inhibits NF-κB mediated transcription. Also, NF-kB transcription inhibits Nrf2 activation by reducing the antioxidant response element (ARE) transcription. Sirtuin 6 (SIRT6) is a member of the Sirtuins family that was found to protect against cardiovascular diseases. SIRT6 can suppress the production of Reactive oxygen species (ROS) through deacetylation of NRF2 which results in NRF2 activation. Furthermore, SIRT6 can inhibit the inflammatory process through the downregulation of NF-kB transcription. Therefore, targeting sirtuins could be a therapeutic strategy to treat CAD. This review describes the potential role of SIRT6 in regulating the crosstalk between NRF2 and NF-kB signaling pathways in CAD.

Elevation of NAD+ by nicotinamide riboside spares spinal cord tissue from injury and promotes locomotor recovery

Spinal cord injury (SCI)-induced tissue damage spreads to neighboring spared cells in the hours, days, and weeks following injury, leading to exacerbation of tissue damage and functional deficits. Among the biochemical changes is the rapid reduction of cellular nicotinamide adenine dinucleotide (NAD+), an essential coenzyme for energy metabolism and an essential cofactor for non-redox NAD+-dependent enzymes with critical functions in sensing and repairing damaged tissue. NAD+ depletion propagates tissue damage. Augmenting NAD+ by exogenous application of NAD+, its synthesizing enzymes, or its cellular precursors mitigates tissue damage. Nicotinamide riboside (NR) is considered to be one of the most promising NAD+ precursors for clinical application due to its ability to safely and effectively boost cellular NAD+ synthesis in rats and humans. Moreover, various preclinical studies have demonstrated that NR can provide tissue protection. Despite these promising findings, little is known about the potential benefits of NR in the context of SCI. In the current study, we tested whether NR administration could effectively increase NAD+ levels in the injured spinal cord and whether this augmentation of NAD+ would promote spinal cord tissue protection and ultimately lead to improvements in locomotor function. Our findings indicate that administering NR (500 mg/kg) intraperitoneally from four days before to two weeks after a mid-thoracic contusion-SCI injury, effectively doubles NAD+ levels in the spinal cord of Long-Evans rats. Moreover, NR administration plays a protective role in preserving spinal cord tissue post-injury, particularly in neurons and axons, as evident from the observed gray and white matter sparing. Additionally, it enhances motor function, as evaluated through the BBB subscore and missteps on the horizontal ladderwalk. Collectively, these findings demonstrate that administering NR, a precursor of NAD+, increases NAD+ within the injured spinal cord and effectively mitigates the tissue damage and functional decline that occurs following SCI.

Engineered human spinal cord-like tissues with dorsal and ventral neuronal progenitors for spinal cord injury repair in rats and monkeys

Transplanting human neural progenitor cells is a promising method of replenishing the lost neurons after spinal cord injury (SCI), but differentiating neural progenitor cells into the diverse types of mature functional spinal cord neurons in vivo is challenging. In this study, engineered human embryonic spinal cord-like tissues with dorsal and ventral neuronal characters (DV-SC) were generated by inducing human neural progenitor cells (hscNPCs) to differentiate into various types of dorsal and ventral neuronal cells on collagen scaffold in vitro. Transplantation of DV-SC into complete SCI models in rats and monkeys showed better therapeutic effects than undifferentiated hscNPCs, including pronounced cell survival and maturation. DV-SC formed a targeted connection with the host's ascending and descending axons, partially restored interrupted neural circuits, and improved motor evoked potentials and the hindlimb function of animals with SCI. This suggests that the transplantation of pre-differentiated hscNPCs with spinal cord dorsal and ventral neuronal characteristics could be a promising strategy for SCI repair.

Hydrogel-based treatments for spinal cord injuries

Spinal cord injury (SCI) is characterized by damage resulting in dysfunction of the spinal cord. Hydrogels are common biomaterials that play an important role in the treatment of SCI. Hydrogels are biocompatible, and some have electrical conductivity that are compatible with spinal cord tissues. Hydrogels have a high drug-carrying capacity, allowing them to be used for SCI treatment through the loading of various types of active substances, drugs, or cells. We first discuss the basic anatomy and physiology of the human spinal cord and briefly discuss SCI and its treatment. Then, we describe different treatment strategies for SCI. We further discuss the crosslinking methods and classification of hydrogels and detail hydrogel biomaterials prepared using different processing methods for the treatment of SCI. Finally, we analyze the future applications and limitations of hydrogels for SCI. The development of biomaterials opens up new possibilities and options for the treatment of SCI. Thus, our findings will inspire scholars in related fields and promote the development of hydrogel therapy for SCI.

Research progress on long non-coding RNAs for spinal cord injury

Spinal cord injury is a complex central nervous system disease with an unsatisfactory prognosis, often accompanied by multiple pathological processes. However, the underlying mechanisms of action of this disease are unclear, and there are no suitable targeted therapeutic options. Long non-coding RNA mediates a variety of neurological diseases and regulates various biological processes, including apoptosis and autophagy, inflammatory response, microenvironment, and oxidative stress. It is known that long non-coding RNAs have significant differences in gene expression in spinal cord injury. To further understand the mechanism of long non-coding RNA action in spinal cord injury and develop preventive and therapeutic strategies regarding spinal cord injury, this review outlines the current status of research between long non-coding RNAs and spinal cord injury and potential long non-coding RNAs targeting spinal cord injury.

Analysis of gene expression profiles in two spinal cord injury models

Objectives

To analyze the changes of gene expression at different timepoints after spinal cord injury (SCI) with tenth segment thoracic injury.

Methods

Two SCI models, the complete paraplegia (H) and Allen’s strike (D) methods were applied to induce SCI in rats, and transcriptome sequencing was performed 1, 3, 7, 14, 56, and 70 days after SCI, respectively. Principal component analysis, differentially expressed gene analysis, and hierarchical clustering analysis were applied to analyze the differentially expressed genes (DEGs). Gene Ontology GO enrichment analysis, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, and Gene Set Enrichment Analysis revealed the pathway of gene enrichment.

Results

There were 1,907, 3,120, 3,728, 978, 2,319, and 3,798 DEGs in the complete paraplegia group and 2,380, 878, 1,543, 6,040, 1,945, and 3,850 DEGs in the Allen’s strike method group and after SCI at 1, 3, 7, 14, 56, and 70 days, respectively. The transcriptome contours of D1, H1, D3, and H14 were clustered with C; the H56, D56, H70, and D70 transcriptome contours were similar and clustered together. H3, D7, and H7 were clustered together, and D14 was clustered separately. The transcriptome differences of the two SCI models were mainly concentrated during the first 2 weeks after SCI. The DEGs after SCI in the complete paraplegia group were more concentrated. Most of the early transcriptional regulation stabilized within 2 weeks after injury.

Conclusions

There were DEGs between the two SCI models. Through the gene changes and pathway enrichment of the entire time period after SCI, the molecular mechanism of SCI repair was revealed in depth, which provided a reference for SCI treatment in the future.

[Advances of the role of mitochondrial dysfunction in the spinal cord injury and its relevant treatments]

OBJECTIVE

To review the advances of the role of mitochondrial dysfunction in the spinal cord injury (SCI) and its relevant treatments.

METHODS

Focusing on various mechanisms of mitochondrial dysfunction, recent relevant literature at home and abroad was identified to summarize the therapeutic strategies for SCI.

RESULTS

Mitochondrial dysfunction is mainly manifested in abnormalities in mitochondrial energy metabolism, mitochondrial oxidative stress, mitochondrial-mediated apoptosis, mitophagy, mitochondrial permeability transition, and mitochondrial biogenesis, playing a vital role in the development of SCI. Drug that enhanced mitochondrial function have been proved beneficial for the treatment of SCI.

CONCLUSION

Mitochondrial dysfunction can serve as a potential therapeutic target for SCI, providing ideas and basis for the development of SCI therapeutic candidates in the future.

Will Sirtuin 2 Be a Promising Target for Neuroinflammatory Disorders?

Neuroinflammatory disorder is a general term that is associated with the progressive loss of neuronal structure or function. At present, the widely studied diseases with neuroinflammatory components are mainly divided into neurodegenerative and neuropsychiatric diseases, namely, Alzheimer’s disease, Parkinson’s disease, depression, stroke, and so on. An appropriate neuroinflammatory response can promote brain homeostasis, while excessive neuroinflammation can inhibit neuronal regeneration and damage the central nervous system. Apart from the symptomatic treatment with cholinesterase inhibitors, antidepressants/anxiolytics, and neuroprotective drugs, the treatment of neuroinflammation is a promising therapeutic method. Sirtuins are a host of class III histone deacetylases, that require nicotinamide adenine dinucleotide for their lysine residue deacetylase activity. The role of sirtuin 2 (SIRT2), one of the sirtuins, in modulating senescence, myelin formation, autophagy, and inflammation has been widely studied. SIRT2 is associated with many neuroinflammatory disorders considering it has deacetylation properties, that regulate the entire immune homeostasis. The aim of this review was to summarize the latest progress in regulating the effects of SIRT2 on immune homeostasis in neuroinflammatory disorders. The overall structure and catalytic properties of SIRT2, the selective inhibitors of SIRT2, the relationship between immune homeostasis and SIRT2, and the multitasking role of SIRT2 in several diseases with neuroinflammatory components were discussed.

Traditional Chinese medicine active ingredients-based selenium nanoparticles regulate antioxidant selenoproteins for spinal cord injury treatment

Background

As Traditional Chinese Medicine (TCM) drugs, Huangqi and Danshen are always applied in combination for spinal cord injury (SCI) treatment based on the compatibility theory of TCM. Astragalus Polysaccharidesis (APS) and Tanshinone IIA (TSIIA) are the main active ingredients of Huangqi and Danshen, and they both possess neuroprotective effects through antioxidant activities. However, low solubility and poor bioavailability have greatly limited their application. In recent years, selenium nanoparticles (SeNPs) have drawn enormous attention as potential delivery carrier for antioxidant drugs.

Results

In this study, TCM active ingredients-based SeNPs surface decorated with APS and loaded with TSIIA (TSIIA@SeNPs-APS) were successfully synthesized under the guidance of the compatibility theory of TCM. Such design improved the bioavailability of APS and TSIIA with the benefits of high stability, efficient delivery and highly therapeutic efficacy for SCI treatment illustrated by an improvement of the antioxidant protective effects of APS and TSIIA. The in vivo experiments indicated that TSIIA@SeNPs-APS displayed high efficiency of cellular uptake and long retention time in PC12 cells. Furthermore, TSIIA@SeNPs-APS had a satisfactory protective effect against oxidative stress-induced cytotoxicity in PC12 cells by inhibiting excessive reactive oxygen species (ROS) production, so as to alleviate mitochondrial dysfunction to reduce cell apoptosis and S phase cell cycle arrest, and finally promote cell survival. The in vivo experiments indicated that TSIIA@SeNPs-APS can protect spinal cord neurons of SCI rats by enhancing GSH-Px activity and decreasing MDA content, which was possibly via the metabolism of TSIIA@SeNPs-APS to SeCys₂ and regulating antioxidant selenoproteins to resist oxidative stress-induced damage.

Conclusions

TSIIA@SeNPs-APS exhibited promising therapeutic effects in the anti-oxidation therapy of SCI, which paved the way for developing the synergistic effect of TCM active ingredients by nanotechnology to improve the efficacy as well as establishing novel treatments for oxidative stress-related diseases associated with Se metabolism and selenoproteins regulation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01490-x.

Reverse Adverse Immune Microenvironments by Biomaterials Enhance the Repair of Spinal Cord Injury

Spinal cord injury (SCI) is a severe and traumatic disorder that ultimately results in the loss of motor, sensory, and autonomic nervous function. After SCI, local immune inflammatory response persists and does not weaken or disappear. The interference of local adverse immune factors after SCI brings great challenges to the repair of SCI. Among them, microglia, macrophages, neutrophils, lymphocytes, astrocytes, and the release of various cytokines, as well as the destruction of the extracellular matrix are mainly involved in the imbalance of the immune microenvironment. Studies have shown that immune remodeling after SCI significantly affects the survival and differentiation of stem cells after transplantation and the prognosis of SCI. Recently, immunological reconstruction strategies based on biomaterials have been widely explored and achieved good results. In this review, we discuss the important factors leading to immune dysfunction after SCI, such as immune cells, cytokines, and the destruction of the extracellular matrix. Additionally, the immunomodulatory strategies based on biomaterials are summarized, and the clinical application prospects of these immune reconstructs are evaluated.

SIRT1: A Key Player in Male Reproduction

Reproduction is the way to immortality for an individual, and it is essential to the continuation of the species. Sirtuins are involved in cellular homeostasis, energy metabolism, apoptosis, age-related problems, and sexual reproduction. Sirtuin 1 (SIRT1) belongs to the sirtuin family of deacetylases, and it is a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase. It removes the acetyl group from a variety of substrates. SIRT1 regulates endocrine/metabolic, reproductive, and placental development by deacetylating histone, different transcription factors, and signal transduction molecules in a variety of cellular processes. It also plays a very important role in the synthesis and secretion of sex hormones via regulating the hypothalamus-pituitary-gonadal (HPG) axis. Moreover, SIRT1 participates in several key stages of spermatogenesis and sperm maturation. The current review will give a thorough overview of SIRT1’s functions in male reproductive processes, thus paving the way for more research on restorative techniques and their uses in reproductive medicine.

Antioxidant Therapy in Oxidative Stress-Induced Neurodegenerative Diseases: Role of Nanoparticle-Based Drug Delivery Systems in Clinical Translation

Free radicals are formed as a part of normal metabolic activities but are neutralized by the endogenous antioxidants present in cells/tissue, thus maintaining the redox balance. This redox balance is disrupted in certain neuropathophysiological conditions, causing oxidative stress, which is implicated in several progressive neurodegenerative diseases. Following neuronal injury, secondary injury progression is also caused by excessive production of free radicals. Highly reactive free radicals, mainly the reactive oxygen species (ROS) and reactive nitrogen species (RNS), damage the cell membrane, proteins, and DNA, which triggers a self-propagating inflammatory cascade of degenerative events. Dysfunctional mitochondria under oxidative stress conditions are considered a key mediator in progressive neurodegeneration. Exogenous delivery of antioxidants holds promise to alleviate oxidative stress to regain the redox balance. In this regard, natural and synthetic antioxidants have been evaluated. Despite promising results in preclinical studies, clinical translation of antioxidants as a therapy to treat neurodegenerative diseases remains elusive. The issues could be their low bioavailability, instability, limited transport to the target tissue, and/or poor antioxidant capacity, requiring repeated and high dosing, which cannot be administered to humans because of dose-limiting toxicity. Our laboratory is investigating nanoparticle-mediated delivery of antioxidant enzymes to address some of the above issues. Apart from being endogenous, the main advantage of antioxidant enzymes is their catalytic mechanism of action; hence, they are significantly more effective at lower doses in detoxifying the deleterious effects of free radicals than nonenzymatic antioxidants. This review provides a comprehensive analysis of the potential of antioxidant therapy, challenges in their clinical translation, and the role nanoparticles/drug delivery systems could play in addressing these challenges.

The ROCK inhibitor Y-27632 ameliorates blood-spinal cord barrier disruption by reducing tight junction protein degradation via the MYPT1-MLC2 pathway after spinal cord injury in rats

The blood-spinal cord barrier (BSCB) is a physiological barrier between the blood and spinal cord parenchyma. This study aims to determine whether Y-27632, a Rho-associated protein kinase (ROCK) inhibitor, can protect the BSCB using in vivo models. The Evans blue fluorescence assay was used to detect leakage of the BSCB. Western blotting was used to define alterations in ROCK-related and tight junction (TJ) protein expression. Immunofluorescence triple-staining was used to evaluate histologic alterations in TJs. Locomotor function was evaluated using the open-field test, the Basso-Beattie-Bresnahan score, and footprint analysis. Two peaks of BSCB leakage after spinal cord injury (SCI) occurred at 24 h and 5 days. The ROCK inhibitor reduced the BSCB leakage at the second peak after SCI. Moreover, the ROCK inhibitor ameliorated the integrity of the BSCB and improved motor function recovery after SCI by regulating the phosphorylation of myosin phosphatase subunit-1 (MYPT1) and cofilin. ROCK inhibitors might protect the BSCB, which provides a new strategy for transitioning SCI treatment from the bench to bedside.