Icariin Inhibits Endoplasmic Reticulum Stress-induced Neuronal Apoptosis after Spinal Cord Injury through Modulating the PI3K/AKT Signaling Pathway

Recent advances on signaling pathways and their inhibitors in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury. Its complex pathological mechanism can lead to sensory and motor dysfunction. It has been reported that signaling pathway plays a key role in the pathological process and neuronal recovery mechanism of SCI. Such as PI3K/Akt, MAPK, NF-κB, and Wnt/β-catenin signaling pathways. According to reports, various stimuli and cytokines activate these signaling pathways related to SCI pathology, thereby participating in the regulation of pathological processes such as inflammation response, cell apoptosis, oxidative stress, and glial scar formation after injury. Activation or inhibition of relevant pathways can delay inflammatory response, reduce neuronal apoptosis, prevent glial scar formation, improve the microenvironment after SCI, and promote neural function recovery. Based on the role of signaling pathways in SCI, they may be potential targets for the treatment of SCI. Therefore, understanding the signaling pathway and its inhibitors may be beneficial to the development of SCI therapeutic targets and new drugs. This paper mainly summarizes the pathophysiological process of SCI, the signaling pathways involved in SCI pathogenesis, and the potential role of specific inhibitors/activators in its treatment. In addition, this review also discusses the deficiencies and defects of signaling pathways in SCI research. It is hoped that this study can provide reference for future research on signaling pathways in the pathogenesis of SCI and provide theoretical basis for SCI biotherapy.

High-strength double-network silk fibroin based hydrogel loaded with Icariin and BMSCs to inhibit osteoclasts and promote osteogenic differentiation to enhance bone repair

Large bone defects cause significant clinical challenges due to the lack of optimal grafts for effective regeneration. The tissue engineering way that requires the combination of biomaterials scaffold, stem cells and proper bioactive factors is a prospective method for large bone repair. Here, we synthesized a three-arm host-guest supramolecule (HGSM) to covalently crosslinking with the naturally derived polymer methacrylated silk fibroin (SFMA). The combination of HGSM and SFMA can form a high strength double-crosslinked hydrogel HGSFMA, that serve as the hydrogel scaffold for bone marrow mesenchymal stem cells (BMSCs) growing. Icariin (ICA) loaded in the HGSFMA hydrogel can promote the osteogenesis efficiency of BMSCs and inhibit the osteoclasts differentiation. Our findings demonstrated that the HGSFMA/ICA hydrogel effectively promoted the in vitro adhesion, proliferation, and osteogenic differentiation of BMSCs. Rat femoral defects model show that this hydrogel can completely repair femoral damage within 4 weeks and significantly promote the secretion of osteogenesis-related proteins. In summary, we have prepared an effective biomimetic bone carrier, offering a novel strategy for bone regeneration and the treatment of large-scale bone defects.

Icariin alleviates oxygen-induced retinopathy by targeting microglia hexokinase 2

Retinopathy of prematurity (ROP) is a retinal disease-causing retinal neovascularization that can lead to blindness. Oxygen-induced retinopathy (OIR) is a widely used ROP animal model. Icariin (ICA) has anti-oxidative and anti-inflammation properties; however, whether ICA has a regulatory effect on OIR remains unclear. In this study, ICA alleviated pathological neovascularization, microglial activation and blood-retina barrier (BRB) damage in vivo. Further results indicated that endothelial cell tube formation, migration and proliferation were restored by ICA treatment in vitro. Proteomic microarrays and molecular mimicry revealed that ICA can directly bind to hexokinase 2 (HK2) and decrease HK2 protein expression in vivo and in vitro. In addition, ICA inhibited the AKT/mTOR/HIF1α pathway activation. The effects of ICA on pathological neovascularization, microglial activation and BRB damage disappeared after HK2 overexpression in vivo. Similarly, the endothelial cell function was revised after HK2 overexpression. HK2 overexpression reversed ICA-induced AKT/mTOR/HIF1α pathway inhibition in vivo and in vitro. Therefore, ICA prevented pathological angiogenesis in OIR in an HK2-dependent manner, implicating ICA as a potential therapeutic agent for ROP.

Endoplasmic reticulum stress in pancreatic β-cell dysfunction: The potential therapeutic role of dietary flavonoids

Diabetes mellitus (DM) is a global health burden that is characterized by the loss or dysfunction of pancreatic β-cells. In pancreatic β-cells, endoplasmic reticulum (ER) stress is a fact of life that contributes to β-cell loss or dysfunction. Despite recent advances in research, the existing treatment approaches such as lifestyle modification and use of conventional therapeutics could not prevent the loss or dysfunction of pancreatic β-cells to abrogate the disease progression. Therefore, targeting ER stress and the consequent unfolded protein response (UPR) in pancreatic β-cells may be a potential therapeutic strategy for diabetes treatment. Dietary phytochemicals have therapeutic applications in human health owing to their broad spectrum of biochemical and pharmacological activities. Flavonoids, which are commonly obtained from fruits and vegetables worldwide, have shown promising prospects in alleviating ER stress. Dietary flavonoids including quercetin, kaempferol, myricetin, isorhamnetin, fisetin, icariin, apigenin, apigetrin, vitexin, baicalein, baicalin, nobiletin hesperidin, naringenin, epigallocatechin 3-O-gallate hesperidin (EGCG), tectorigenin, liquiritigenin, and acacetin have shown inhibitory effects on ER stress in pancreatic β-cells. Dietary flavonoids modulate ER stress signaling components, chaperone proteins, transcription factors, oxidative stress, autophagy, apoptosis, and inflammatory responses to exert their pharmacological effects on pancreatic β-cells ER stress. This review focuses on the role of dietary flavonoids as potential therapeutic adjuvants in preserving pancreatic β-cells from ER stress. Highlights of the underlying mechanisms of action are also presented as well as possible strategies for clinical translation in the management of DM.

Electroacupuncture improves gastrointestinal motility through a central-cholinergic pathway-mediated GDNF releasing from intestinal glial cells to protect intestinal neurons in Parkinson's disease rats

Constipation symptoms of Parkinson's disease (PD) seriously reduce the quality of life of patients and aggravate the development of the disease, but current treatment options still cannot alleviate the progress of constipation. Electroacupuncture (EA) is a new method for the treatment of constipation, which can effectively treat the symptoms of constipation in PD patients. However, the specific regulatory mechanisms of EA in the treatment of constipation symptoms in PD remain unclear. The aim of this study is to investigate the therapeutic effect of EA on PD constipation rats and its regulatory mechanism. A rotenone (ROT)-induced gastrointestinal motility disorder model was used to simulate the pathological process of constipation in PD. The results showed that EA could effectively promote gastrointestinal peristalsis, reduce α-synuclein accumulation in substantia nigra and colon and colonic injury in rats after ROT administration. Mechanistically, EA activation of the central-cholinergic pathway increases acetylcholine release in the colon. At the same time, EA up-regulated the co-expression of enteric glial cells (EGCs) and α7 nicotinic acetylcholine receptor (α7nAChR). EA increased the expression of choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH) in the colon of PD rats. Further mechanistic studies showed that EA increased the expression of glial cell-derived neurotrophic factor (GDNF), GFRa1 and p-AKT in colon tissues. The present study confirmed that EA upregulates α7nAChR through a central-cholinergic mechanism to promote GDNF release from EGCs, thereby protecting intestinal neurons and thereby improving gastrointestinal motility.

Crosstalk Between Cell Death and Spinal Cord Injury: Neurology and Therapy

Spinal cord injury (SCI) often leads to neurological dysfunction, and neuronal cell death is one of the main causes of neurological dysfunction. After SCI, in addition to necrosis, programmed cell death (PCD) occurs in nerve cells. At first, studies recognized only necrosis, apoptosis, and autophagy. In recent years, researchers have identified new forms of PCD, including pyroptosis, necroptosis, ferroptosis, and cuproptosis. Related studies have confirmed that all of these cell death modes are involved in various phases of SCI and affect the direction of the disease through different mechanisms and pathways. Furthermore, regulating neuronal cell death after SCI through various means has been proven to be beneficial for the recovery of neural function. In recent years, emerging therapies for SCI have also provided new potential methods to restore neural function. Thus, the relationship between SCI and cell death plays an important role in the occurrence and development of SCI. This review summarizes and generalizes the relevant research results on neuronal necrosis, apoptosis, autophagy, pyroptosis, necroptosis, ferroptosis, and cuproptosis after SCI to provide a new understanding of neuronal cell death after SCI and to aid in the treatment of SCI.

Photobiomodulation therapy enhances neural differentiation of dental pulp stem cells via ERK1/2 signaling pathway

Photobiomodulation therapy (PBMT) is the application of a low-level laser device to generate physiological changes and provide therapeutic effects. Till now, the effects of PBMT on the neural differentiation of mesenchymal stem cells have been rarely reported. Herein, the potential effect and mechanism of PBMT on the neural differentiation of dental pulp stem cells (DPSCs) were preliminarily investigated in our research. The optimal dose of 3.75 J/cm2 was first screened for use in the following neural-inducing studies. Then, DPSCs were cultured in neural induction medium and treated with laser irradiation for 7 days. From the results of morphology and immunofluorescence, we found that irradiation promoted the formation of neural stem cell-like spheroids derived from DPSCs and enhanced potential neural differentiation. Furthermore, neural differentiation gene expressions of Nestin, microtubule-associated protein-2, and neural cell adhesion molecule were increased after PBMT irradiation. The protein expressions of class III β-tubulin and neurogenic differentiation factor 1 were also improved. Meanwhile, the involvement of extracellular signal-regulated kinase (ERK1/2) was investigated by western blot. Our study showed that the neural differentiation of DPSCs was promoted by PBMT, and the underlying mechanism in this process was associated with activating the ERK1/2 signaling pathway.

Bioinformatics analysis of differentially expressed genes related to ischemia and hypoxia in spinal cord injury and construction of miRNA-mRNA or mRNA-transcription factor interaction network

BACKGROUND

Previous studies show that spinal cord ischemia and hypoxia is an important cause of spinal cord necrosis and neurological loss. Therefore, the study aimed to identify genes related to ischemia and hypoxia after spinal cord injury (SCI) and analyze their functions, regulatory mechanism, and potential in regulating immune infiltration.

METHODS

The expression profiles of GSE5296, GSE47681, and GSE217797 were downloaded from the Gene Expression Omnibus database. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to determine the function and pathway enrichment of ischemia- and hypoxia-related differentially expressed genes (IAHRDEGs) in SCI. LASSO model was constructed, and support vector machine analysis was used to identify key genes. The diagnostic values of key genes were evaluated using decision curve analysis and receiver operating characteristic curve analysis. The interaction networks of miRNAs-IAHRDEGs and IAHRDEGs-transcription factors were predicted and constructed with the ENCORI database and Cytoscape software. CIBERSORT algorithm was utilized to analyze the correlation between key gene expression and immune cell infiltration.

RESULTS

There were 27 IAHRDEGs identified to be significantly expressed in SCI at first. These genes were mostly significantly enriched in wound healing function and the pathway associated with lipid and atherosclerosis. Next, five key IAHRDEGs (Abca1, Casp1, Lpl, Procr, Tnfrsf1a) were identified and predicted to have diagnostic value. Moreover, the five key genes are closely related to immune cell infiltration.

CONCLUSION

Abca1, Casp1, Lpl, Procr, and Tnfrsf1a may promote the pathogenesis of ischemic or hypoxic SCI by regulating vascular damage, inflammation, and immune infiltration.

HRD1-induced TMEM2 ubiquitination promotes ER stress-mediated apoptosis through a non-canonical pathway in intestinal ischemia/reperfusion

Intestinal ischemia/reperfusion (I/R) injury is a typical pathological course in the clinic with a high morbidity rate. Recent research has pointed out the critical role of ubiquitination during the occurrence and development of intestinal I/R by precisely mediating protein quality control and function. Here, we conducted an integrated multiomic analysis to identify critical ubiquitination-associated molecules in intestinal I/R and identified endoplasmic reticulum-located HRD1 as a candidate molecule. During intestinal I/R, excessive ER stress plays a central role by causing apoptotic pathway activation. In particular, we found that ER stress-mediated apoptosis was mitigated by HRD1 knockdown in intestinal I/R mice. Mechanistically, TMEM2 was identified as a new substrate of HRD1 in intestinal I/R by mass spectrometry analysis, which has a crucial role in attenuating apoptosis and promoting non-canonical ER stress resistance. A strong negative correlation was found between the protein levels of HRD1 and TMEM2 in human intestinal ischemia samples. Specifically, HRD1 interacted with the lysine 42 residue of TMEM2 and reduced its stabilization by K48-linked polyubiquitination. Furthermore, KEGG pathway analysis revealed that TMEM2 regulated ER stress-mediated apoptosis in association with the PI3k/Akt signaling pathway rather than canonical ER stress pathways. In summary, HRD1 regulates ER stress-mediated apoptosis through a non-canonical pathway by ubiquitinating TMEM2 and inhibiting PI3k/Akt activation during intestinal I/R. The current study shows that HRD1 is an intestinal I/R critical regulator and that targeting the HRD1/TMEM2 axis may be a promising therapeutic approach.

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

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

Potential Role of Endoplasmic Reticulum Stress in Modulating Protein Homeostasis in Oligodendrocytes to Improve White Matter Injury in Preterm Infants

Preterm white matter injury (WMI) is a demyelinating disease with high incidence and mortality in premature infants. Oligodendrocyte cells (OLs) are a specialized glial cell that produces myelin proteins and adheres to the axons providing energy and metabolic support which susceptible to endoplasmic reticulum protein quality control. Disruption of cellular protein homeostasis led to OLs dysfunction and cell death, immediately, the unfolded protein response (UPR) activated to attempt to restore the protein homeostasis via IRE1/XBP1s, PERK/eIF2α and ATF6 pathway that reduced protein translation, strengthen protein-folding capacity, and degraded unfolding/misfolded protein. Moreover, recent works have revealed the conspicuousness function of ER signaling pathways in regulating influenced factors such as calcium homeostasis, mitochondrial reactive oxygen generation, and autophagy activation to regulate protein hemostasis and improve the myelination function of OLs. Each of the regulation modes and their corresponding molecular mechanisms provides unique opportunities and distinct perspectives to obtain a deep understanding of different actions of ER stress in maintaining OLs' health and function. Therefore, our review focuses on summarizing the current understanding of ER stress on OLs' protein homeostasis micro-environment in myelination during white matter development, as well as the pathophysiology of WMI, and discussing the further potential experimental therapeutics targeting these factors that restore the function of the UPR in OLs myelination function. Potential Role of ER Stress in Modulating Protein Homeostasis in OLs. OLs, produce myelin proteins and provide energy and metabolic support which are susceptible to cellular protein homeostasis and ER protein quality control. 1) UPR plays a different role in activating IRE1/XBP1s, PERK/eIF2α, and ATF6 pathways not only in attempting to restore protein homeostasis to promote cell survival but also aggravating disruption of cellular protein homeostasis to accelerate cell death. 2) PERK pathway facilitated the protein secretion, amino acid metabolism, and stress response to promote cell survival via phosphorylating eIF2α level and strengthening ATF4 expression; Nevertheless, the prolonged activating of the PERK pathway could up-regulate CHOP, GADD34, and other pro-apoptotic factors to further aggravates cell injury. 3) IRE1 and ATF6 pathways enhanced various gene transcription associated with protein folding, secreting, EARD, and ERQC to prompt cell protein homeostasis micro-environment; However, sustained IRE1 and/or ATF6 activity could prompt cell survival toward apoptosis via the pro-apoptotic pathway, inflammation, and other patterns.

Mechanism of Valeriana Jatamansi Jones for the treatment of spinal cord injury based on network pharmacology and molecular docking

Spinal cord injury (SCI) is characterized by high rates of disability and death. Valeriana jatamansi Jones (VJJ), a Chinese herbal medicine, has been identified to improve motor function recovery in rats with SCI. The study aimed to analyze the potential molecular mechanisms of action of VJJ in the treatment of SCI. The main ingredients of VJJ were obtained from the literature and the SwissADME platform was used to screen the active ingredients. The Swiss TargetPrediction platform was used to predict the targets of VJJ, and the targets of SCI were obtained from the GeneCards and OMIM databases. The intersecting genes were considered potential targets of VJJ in SCI. The protein-protein interaction network was constructed using the STRING database and the hub genes of VJJ for SCI treatment were screened according to their degree values. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed using the Metascape database. Cytoscape software was used to construct the "herb-ingredient-target-pathway" network. Preliminary validation was performed using molecular docking via Auto Dock Vina software. A total of 56 active ingredients of VJJ, mainly iridoids, were identified. There were 1493 GO items (P < .01) and 173 signaling pathways (P < .01) obtained from GO and Kyoto Encyclopedia of Genes and Genomes enrichment, including the phosphoinositide-3-kinase (PI3K)-protein kinase B (Akt) signaling pathway, hypoxia-inducible factor 1 signaling pathway, and tumor necrosis factor signaling pathway. Molecular docking revealed that 12 hub genes enriched in the PI3K/Akt signaling pathway had a high binding affinity for the active ingredient of VJJ. VJJ may exert its therapeutic effects on SCI through the iridoid fraction, acting on signal transducer and activator of transcription 3, CASP3, AKT1, tumor necrosis factor, mammalian target of rapamycin, interleukin 6, and other hub genes, which may be related to the PI3K/Akt signaling pathway.

Tibolone Improves Locomotor Function in a Rat Model of Spinal Cord Injury by Modulating Apoptosis and Autophagy

Spinal cord injury (SCI) harms patients' health and social and economic well-being. Unfortunately, fully effective therapeutic strategies have yet to be developed to treat this disease, affecting millions worldwide. Apoptosis and autophagy are critical cell death signaling pathways after SCI that should be targeted for early therapeutic interventions to mitigate their adverse effects and promote functional recovery. Tibolone (TIB) is a selective tissue estrogen activity regulator (STEAR) with neuroprotective properties demonstrated in some experimental models. This study aimed to investigate the effect of TIB on apoptotic cell death and autophagy after SCI and verify whether TIB promotes motor function recovery. A moderate contusion SCI was produced at thoracic level 9 (T9) in male Sprague Dawley rats. Subsequently, animals received a daily dose of TIB orally and were sacrificed at 1, 3, 14 or 30 days post-injury. Tissue samples were collected for morphometric and immunofluorescence analysis to identify tissue damage and the percentage of neurons at the injury site. Autophagic (Beclin-1, LC3-I/LC3-II, p62) and apoptotic (Caspase 3) markers were also analyzed via Western blot. Finally, motor function was assessed using the BBB scale. TIB administration significantly increased the amount of preserved tissue (p < 0.05), improved the recovery of motor function (p < 0.001) and modulated the expression of autophagy markers in a time-dependent manner while consistently inhibiting apoptosis (p < 0.05). Therefore, TIB could be a therapeutic alternative for the recovery of motor function after SCI.

Shikonin inhibits neuronal apoptosis via regulating endoplasmic reticulum stress in the rat model of double-level chronic cervical cord compression

Cervical spondylotic myelopathy (CSM) is a clinically symptomatic entity arising from the spinal cord compression by degenerative diseases. Although endoplasmic reticulum (ER) stress has been commonly observed in several neurodegenerative diseases, the relationship between ER stress and CSM remains unknown. Shikonin is known to protect PC12 by inhibiting apoptosis in vitro. This study hypothesised that ER stress was vital in neuronal apoptosis in CSM. Shikonin might inhibit such responses by regulating ER stress through the protein kinase-like ER kinase-eukaryotic translation initiation factor 2 α-subunit-C/EBP homologous protein (PERK-eIF2α-CHOP) signalling pathway. Thus, the aim of this study was evaluating the neuroprotective effect of shikonin in rats with double-level chronic cervical cord compression, as well as primary rat cortical neurons with glutamate-induced neurotoxicity. The result showed that ER stress-related upregulation of PERK-eIF2α-CHOP resulted in rat neuronal apoptosis after chronic cervical cord compression; then, shikonin promoted motor recovery and inhibited neuronal apoptosis by attenuating PERK-eIF2α-CHOP and prevented Bax translocation from cytoplasm to mitochondrion induced by CHOP of neurons in rats with chronic compression. Also, it was found that shikonin could protect rat primary cortical neuron against glutamate toxicity by regulating ER stress through the PERK-eIF2α-CHOP pathway in vitro. In conclusion, shikonin might inhibit neuronal apoptosis by regulating ER stress through attenuating the activation of PERK-eIF2α-CHOP.

Resveratrol Suppresses Bupivacaine-Induced Spinal Neurotoxicity in Rats by Inhibiting Endoplasmic Reticulum Stress via SIRT1 Modulation

Bupivacaine (BUP) may cause neurotoxic effects after spinal anesthesia. Resveratrol (RSV), a natural agonist of Silent information regulator 1 (SIRT1), protects various tissues and organs from damage by regulating endoplasmic reticulum (ER) stress. The aim of this study is to explore whether RSV could alleviate the neurotoxicity induced by bupivacaine via regulating ER stress. We established a model of bupivacaine-induced spinal neurotoxicity in rats using intrathecal injection of 5% bupivacaine. The protective effect of RSV was evaluated by injecting intrathecally with 30 μg/μL RSV in total of 10 μL per day for 4 consecutive days. On day 3 after bupivacaine administration, tail-flick latency (TFL) tests and the Basso, Beattie, and Bresnahan (BBB) locomotor scores were assessed to neurological function, and the lumbar enlargement of the spinal cord was obtained. H&E and Nissl staining were used to evaluate the histomorphological changes and the number of survival neurons. TUNEL staining was conducted to determine apoptotic cells. The expression of proteins was detected by IHC, immunofluorescence, and western blot. The mRNA level of SIRT1 was determined by RT-PCR. Bupivacaine caused spinal cord neurotoxicity by inducing cell apoptosis and triggering ER stress. RSV treatment promoted the recovery of neurological dysfunction after bupivacaine administration by suppressing neuronal apoptosis and ER stress. Furthermore, RSV upregulated SIRT1 expression and inhibited PERK signaling pathway activation. In summary, resveratrol suppresses bupivacaine-induced spinal neurotoxicity in rats by inhibiting endoplasmic reticulum stress via SIRT1 modulation.

Network pharmacology integrated with experimental validation to explore the therapeutic role and potential mechanism of Epimedium for spinal cord injury

Objective

Epimedium (EPI) is a common Chinese herb with neuroprotective effects against a variety of central nervous system disorders, especially spinal cord injury (SCI). In this study, we performed network pharmacology and molecular docking analyses to reveal the mechanism underlying EPI treatment of SCI, then validated its efficacy using animal models.

Methods

The active ingredients and targets of EPI were screened by Traditional Chinese Medicine Systems Pharmacology (TCMSP) and their targets annotated on the UniProt platform. SCI-related targets were searched from OMIM, TTD, and GeneCards databases. We employed the STRING platform to construct a protein-protein interaction (PPI) network then visualized the results using Cytoscape (3.8.2) software. We also subjected key EPI targets to ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, then docked the main active ingredients with the key targets. Finally, we established an SCI rat model to evaluate efficacy of EPI in treating SCI and validate the effects of different biofunctional modules predicted by network pharmacology.

Results

A total of 133 EPI targets were associated with SCI. GO terms and KEGG pathway enrichment results showed that EPI's effect in treating SCI was significantly associated with inflammatory response, oxidative stress and the PI3K/AKT signaling pathway. Molecular docking results indicated that EPI's active ingredients have a high affinity for the key targets. Results from animal experiments revealed that EPI not only markedly improved Basso, Beattie, and Bresnahan scores in SCI rats, but also significantly improved p-PI3K/PI3K and p-AKT/AKT ratio. Moreover, EPI treatment not only mediated a significant decrease in malondialdehyde (MDA) but also increased both superoxide dismutase (SOD), and glutathione (GSH). However, this phenomenon was successfully reversed by LY294002, a PI3K inhibitor.

Conclusion

EPI improves behavioral performance in SCI rats through anti-oxidative stress, which may be mediated by activation of the PI3K/AKT signaling pathway.

Inhibition of TERC inhibits neural apoptosis and inflammation in spinal cord injury through Akt activation and p-38 inhibition via the miR-34a-5p/XBP-1 axis

This study investigated the function of telomerase RNA component (TERC) in spinal cord injury (SCI). SCI models were established in rats via laminectomy and PC-12 cells were treated with lipopolysaccharide (LPS). TERC and miR-34a-5p expressions in cells and rat spinal cords were detected by quantitative reverse transcription polymerase chain reaction, followed by overexpression/knockdown of TERC/miR-34a-5p. Spinal cord histopathological changes were examined via hematoxylin-eosin staining. miR-34a-5p' relation with TERC and XBP-1 was predicted by TargetScan and checked by dual-luciferase reporter/RNA immunoprecipitation assays. Cell biological behaviors were assessed by Cell counting kit-8, wound healing, Transwell, and flow cytometry assays. XBP-1 and inflammation/apoptosis-related protein expressions were analyzed by western blot. TERC was upregulated and miR-34a-5p was low-expressed in SCI tissues and LPS-induced PC-12 cells. TERC-knockdown alleviated histopathological abnormalities yet upregulated miR-34a-5p in SCI tissues. In LPS-induced PC-12 cells, TERC knockdown promoted cell viability, migration, invasion, and inhibited apoptosis, while TERC overexpression ran oppositely. TERC knockdown downregulated the XBP-1, IL-6, TNF-α, Bax, p-p38/t-p38, and cleaved caspase-9/-3, but upregulated Bcl-2 and p-Akt/t-Akt. TERC targeted miR-34a-5p, which further targeted XBP-1. miR-34a-5p downregulation exerted effects opposite to and offset TERC knockdown-induced effects. TERC knockdown facilitated the regeneration of neuron tissues yet inhibited inflammation in SCI through Akt activation and p-38 inhibition via the miR-34a-5p/XBP-1 axis.

Genomic and clinical features of endoplasmic reticulum stress factor in digestive system pan-cancer studies

Introduction

Digestive system pan-cancer is one of the lethal malignant tumors, which have the propensity for poor prognosis and difficult treatment. Endoplasmic reticulum (ER) stress has served as a pivotal role in the progression of the tumor, while the implication of ER stress on digestive system pan-cancers still needs elucidation, especially from the perspective of clinical outcome and that of genomic features.

Methods

First, Among the ER STRESS factors from the REACTOME_UNFOLDED_PROTEIN_RESPONSE_UPR (113 genes) and HALLMARK_UNFOLDED_PROTEIN_RESPONSE (92 genes) terms, 153 ER STRESS regulators were identified after removing replicates. The somatic mutation data and copy number variation data of gastrointestinal pan-cancer were downloaded from The Cancer Genome Atlas (TCGA) database. Then, we explored the clinical outcome and genetic mutation of ER stress-related differentially expressed genes (DEGs) by multiple bioinformatics analysis. Subsequently, we analyzed the Spearman correlation between the drug sensitivity of 179 gastrointestinal anticancer drugs and the transcriptional expression of 153 ER stress factors in 769 cancer cell lines of the GDSC2 cohort. Next, ssGSEA method was used to quantify the immune cell infiltration scores in the tumor microenvironment, and Spearman correlation was used to calculate the correlation between ER stress scores and immune cell infiltration. Finally, we analyzed the cellular origin of ER stress factor dysregulation.

Results

We analyzed the genomic changes and clinical outcomes of ER stress factors in different tumors of gastrointestinal pan-cancer. Endoplasmic reticulum stress factor (ER) in digestive tract tumors showed high SNV mutation frequency, less methylation dysregulation and was associated with multiple oncogenic pathways. Endoplasmic reticulum stress factor (ER) is a risk factor for many cancers, but the effect on overall survival in rectal adenocarcinoma is opposite to that in other gastrointestinal tumors. And ER stress factors are highly correlated with drugs that target important pathways.

Discussion

Based on the clinical prognosis and genomic analysis of ER stress-related factors in patients with gastrointestinal pan-cancer, this study provides a new direction for further research on gastrointestinal pan-cancer.

Preparation, structural characterization and neuroprotective effects to against H2O2-induced oxidative damage in PC12 cells of polysaccharides from Pleurotus ostreatus

Pleurotus ostreatus is one of the most common edible and medicinal fungi in life, and its polysaccharide has been a hot research topic in recent years. In this paper, a new intracellular polysaccharide component named P. ostreatus polysaccharide (POP-W) was obtained from the mycelium of P. ostreatus, and its structure was analyzed. The results showed that its molecular weight was Mw = 3.034 × 10³ kDa, and it did not contain protein and nucleic acid. POP-W was composed of mannose, glucose, galactose and xylose in a molar ratio of 40.34:47.60:7.97:4.09. The backbone of POP-W was α-D-Glcp(1→,→3,4)-α-D-Glcp(1→, →3,4)-α-D-Manp(1→,→3)-α -D-Galp(1→, →4)-α-D-Glcp(1→, →3)-α-D-Glcp(1→, →2)-β-D-Manp(1→, →4) -β-D-Xylp(1 →. SEM and TGA analysis showed the structure of POP-W and good thermal stability. In addition, POP-W showed significant antioxidant activity in vitro. More importantly, POP-W protected PC12 cells induced by H₂O₂ by inhibiting the contents of lactate dehydrogenase (LDH) and malondialdehyde (MDA) and increasing the levels of superoxide dismutase (SOD) and reduced glutathione (GSH). Western blot detection of Caspase-3, BAX, Bcl-2, PI3K/Akt protein expression. The results showed that POP-W inhibited the expression of caspase-3 and BAX, while promoting the expression of Bcl-2. In addition, POP-W can also promote the phosphorylation of Akt. In conclusion, POP-W pretreatment can protect PC12 cells from H₂O₂-induced oxidative damage through PI3K/Akt signaling pathway and regulation of apoptosis-related pathway proteins. It provided a theoretical basis for the practical application of the polysaccharide of P. ostreatus in production.

Geraniol-Mediated Suppression of Endoplasmic Reticulum Stress Protects against Cerebral Ischemia-Reperfusion Injury via the PERK-ATF4-CHOP Pathway

Endoplasmic reticulum (ER) stress plays an important role in cerebral ischemia-reperfusion injury (CIRI). Geraniol has antioxidant, antibacterial, and anti-inflammatory activities. Studies have shown that geraniol has a protective effect against CIRI in rats, but the exact mechanism is unclear. Purpose: The aim of this study was to investigate the protective mechanism of geraniol against CIRI. We established a middle cerebral artery occlusion reperfusion model in rats and a PC12 cell oxygen-glucose deprivation/reoxygenation (OGD/R) model to observe the neuroprotective effects of geraniol. Neurological scoring, 2,3,5-triphenyltetrazolium chloride staining, and hematoxylin and eosin staining were used to evaluate the neuroprotective effects of geraniol against CIRI. ER-stress-related and apoptosis-related protein expression was detected via Western blotting and immunofluorescence. Apoptosis was also detected via TUNEL assays and flow cytometry. The fluorescent detection of intracellular calcium was achieved using fluorescent calcium-binding dyes, and transmission electron microscopy was used to assess the neuronal ultrastructure. Geraniol effectively attenuated cerebral infarction and pathological injury after CIRI, had a protective effect against CIRI, significantly reduced the expression of the ER-stress-related proteins P-PERK, ATF4, CHOP, and GRP78 and the pro-apoptotic protein BAX, increased the expression of the anti-apoptotic protein BCL-2, and reduced the occurrence of apoptosis. In the OGD/R model in PC12 cells, the protective effect of geraniol was the same as that in vivo. Our results suggest that geraniol has a protective effect against ischemic stroke by a mechanism possibly related to ER stress via the PERK-ATF4-CHOP pathway.

c-Mpl-del, a c-Mpl alternative splicing isoform, promotes AMKL progression and chemoresistance

Acute megakaryocytic leukemia (AMKL) is a clinically heterogeneous subtype of acute myeloid leukemia characterized by unrestricted megakaryoblast proliferation and poor prognosis. Thrombopoietin receptor c-Mpl is a primary regulator of megakaryopoeisis and a potent mitogenic receptor. Aberrant c-Mpl signaling has been implicated in a myriad of myeloid proliferative disorders, some of which can lead to AMKL, however, the role of c-Mpl in AMKL progression remains largely unexplored. Here, we identified increased expression of a c-Mpl alternative splicing isoform, c-Mpl-del, in AMKL patients. We found that c-Mpl-del expression was associated with enhanced AMKL cell proliferation and chemoresistance, and decreased survival in xenografted mice, while c-Mpl-del knockdown attenuated proliferation and restored apoptosis. Interestingly, we observed that c-Mpl-del exhibits preferential utilization of phosphorylated c-Mpl-del C-terminus Y607 and biased activation of PI3K/AKT pathway, which culminated in upregulation of GATA1 and downregulation of DDIT3-related apoptotic responses conducive to AMKL chemoresistance and proliferation. Thus, this study elucidates the critical roles of c-Mpl alternative splicing in AMKL progression and drug resistance, which may have important diagnostic and therapeutic implications for leukemia accelerated by c-Mpl-del overexpression.

Molecular mechanisms regulating the pharmacological actions of icariin with special focus on PI3K-AKT and Nrf-2 signaling pathways

Icariin is a primary active component of the traditional Chinese medicinal plant Epimedium grandiflorum. A range of pharmacological effects of icariin has been researched by modern science to explain its traditional medicinal uses. Attributing to the wide range of pharmacological properties like anti-osteoporosis, anti-inflammation, anti-oxidative stress, anti-depression, and anti-tumor property possessed by icariin, it is now being considered a potential therapeutic agent for a wide variety of disorders ranging from neoplasm, neurodegenerative disorders, osteoporosis, and cardiovascular diseases. Various signaling pathways including NFκB/NALP3, IGF-1, MiR-223-3p/ NALP3, TLR4/ NFκB, and WNT1/β-catenin are involved in the different biological actions exerted by icariin. Apart from these pathways, PI3K-AKT (Phosphoinositide 3 kinase-Protein kinase B) and Nrf-2 (nuclear erythroid 2-related factor 2) signaling pathways are two important pathways that form the fundamental basis for the pharmaceutical efficacy of icariin. This review gives an overview of previous in vitro and in vivo studies that investigated the potential role of icariin via PI3K-AKT and Nrf-2 signaling pathways to provide greater insights into its potential clinical use in a variety of disorders.

TSG-6 released from adipose stem cells-derived small extracellular vesicle protects against spinal cord ischemia reperfusion injury by inhibiting endoplasmic reticulum stress

Background

Spinal cord ischemia reperfusion injury (SCIRI) is a complication of aortic aneurysm repair or spinal cord surgery that is associated with permanent neurological deficits. Mesenchymal stem cell (MSC)-derived small extracellular vesicles (sEVs) have been shown to be potential therapeutic options for improving motor functions after SCIRI. Due to their easy access and multi-directional differentiation potential, adipose‐derived stem cells (ADSCs) are preferable for this application. However, the effects of ADSC-derived sEVs (ADSC-sEVs) on SCIRI have not been reported.

Results

We found that ADSC-sEVs inhibited SCIRI-induced neuronal apoptosis, degradation of tight junction proteins and suppressed endoplasmic reticulum (ER) stress. However, in the presence of the ER stress inducer, tunicamycin, its anti-apoptotic and blood–spinal cord barrier (BSCB) protective effects were significantly reversed. We found that ADSC-sEVs contain tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) whose overexpression inhibited ER stress in vivo by modulating the PI3K/AKT pathway.

Conclusions

ADSC-sEVs inhibit neuronal apoptosis and BSCB disruption in SCIRI by transmitting TSG-6, which suppresses ER stress by modulating the PI3K/AKT pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02963-4.

Catalpol as a Component of Rehmannia glutinosa Protects Spinal Cord Injury by Inhibiting Endoplasmic Reticulum Stress-Mediated Neuronal Apoptosis

Disturbance of the internal environment in the spinal cord after spinal cord injury (SCI) is an important cause of the massive death of neurons in the injury area and one of the major problems that lead to the difficult recovery of motor function in patients. Rehmannia glutinosa, a famous traditional Chinese medicine, is commonly used in neurodegenerative diseases, whereas an iridoid glycoside extract of catalpol (CAT), with antioxidant, antiapoptotic, and neuroprotective pharmacological effects. However, the neuroprotective and anti-apoptosis mechanism of CAT in SCI remains unclear. In our study, we found that CAT has a restorative effect on the lower limb motor function of rats with SCI by establishing a rat model of SCI and treating CAT gavage for 30 days. Our study further found that CAT has the effect of inhibiting apoptosis and protecting neurons, and the action pathway may reduce endoplasmic reticulum (ER) stress by inhibiting CHOP and GRP78 expression and then reduce apoptosis and protect neurons through the Caspase3/Bax/Bcl-2 pathway. In conclusion, we demonstrated that CAT can treat SCI by inhibiting ER stress-mediated neuronal apoptosis and has the potential to be a clinical drug for the treatment of SCI.

The PI3K/AKT signalling pathway in inflammation, cell death and glial scar formation after traumatic spinal cord injury: Mechanisms and therapeutic opportunities

Objects

Traumatic spinal cord injury (TSCI) causes neurological dysfunction below the injured segment of the spinal cord, which significantly impacts the quality of life in affected patients. The phosphoinositide 3kinase/serine‐threonine kinase (PI3K/AKT) signaling pathway offers a potential therapeutic target for the inhibition of secondary TSCI. This review summarizes updates concerning the role of the PI3K/AKT pathway in TSCI.

Materials and Methods

By searching articles related to the TSCI field and the PI3K/AKT signaling pathway, we summarized the mechanisms of secondary TSCI and the PI3K/AKT signaling pathway; we also discuss current and potential future treatment methods for TSCI based on the PI3K/AKT signaling pathway.

Results

Early apoptosis and autophagy after TSCI protect the body against injury; a prolonged inflammatory response leads to the accumulation of pro‐inflammatory factors and excessive apoptosis, as well as excessive autophagy in the surrounding normal nerve cells, thus aggravating TSCI in the subacute stage of secondary injury. Initial glial scar formation in the subacute phase is a protective mechanism for TSCI, which limits the spread of damage and inflammation. However, mature scar tissue in the chronic phase hinders axon regeneration and prevents the recovery of nerve function. Activation of PI3K/AKT signaling pathway can inhibit the inflammatory response and apoptosis in the subacute phase after secondary TSCI; inhibiting this pathway in the chronic phase can reduce the formation of glial scar.

Conclusion

The PI3K/AKT signaling pathway has an important role in the recovery of spinal cord function after secondary injury. Inducing the activation of PI3K/AKT signaling pathway in the subacute phase of secondary injury and inhibiting this pathway in the chronic phase may be one of the potential strategies for the treatment of TSCI.

Baicalin attenuates blood-spinal cord barrier disruption and apoptosis through PI3K/Akt signaling pathway after spinal cord injury

Baicalin is a natural active ingredient isolated from Scutellariae Radix that can cross the blood-brain barrier and exhibits neuroprotective effects on multiple central nervous system diseases. However, the mechanism behind the neuroprotective effects remains unclear. In this study, rat models of spinal cord injury were established using a modified Allen's impact method and then treated with intraperitoneal injection of Baicalin. The results revealed that Baicalin greatly increased the Basso, Beattie, Bresnahan Locomotor Rating Scale score, reduced blood-spinal cord barrier permeability, decreased the expression of Bax, Caspase-3, and nuclear factor κB, increased the expression of Bcl-2, and reduced neuronal apoptosis and pathological spinal cord injury. SH-SY5Y cell models of excitotoxicity were established by application of 10 mM glutamate for 12 hours and then treated with 40 µM Baicalin for 48 hours to investigate the mechanism of action of Baicalin. The results showed that Baicalin reversed tight junction protein expression tendencies (occludin and ZO-1) and apoptosis-related protein expression (Bax, Bcl-2, Caspase-3, and nuclear factor-κB), and also led to up-regulation of PI3K and Akt phosphorylation. These effects on Bax, Bcl-2, and Caspase-3 were blocked by pretreatment with the PI3K inhibitor LY294002. These findings suggest that Baicalin can inhibit blood-spinal cord barrier permeability after spinal cord injury and reduce neuronal apoptosis, possibly by activating the PI3K/Akt signaling pathway. This study was approved by Animal Ethics Committee of Xi'an Jiaotong University on March 6, 2014.

Urolithin A as a Potential Drug for the Treatment of Spinal Cord Injuries: A Mechanistic Study Using Network Pharmacology Approaches

Objective

This research was focused to examine the potential targets, action network, and mechanism of urolithin A (UA) in spinal cord injury (SCI) management exploiting the network pharmacology (NP).

Methods

We used the SwissTargetPrediction, PharmMapper, and TargetNet databases to obtain UA action targets. We searched the OMIM, GeneCards, CTD, and DrugBank databases to screen selected target genes for SCI treatment. The intersection of target genes between the UA and SCI databases was obtained by constructing Venn diagrams, which led to the identification of common druggable targets for the disease. The relationship network of the targets was built with Cytoscape 3.7.2, and the protein interaction network was analyzed with the STRING platform. The protein-protein interaction (PPI) network can be built on the STRING database. Gene Ontology (GO) function and KEGG pathway analyses of target intersections were completed with the DAVID 6.8 database. We constructed preliminary network targets for actions underlying UA-SCI interactions. Using the AutoDock software, we examined the molecular docking interactions between UA and its target proteins and further verified the mechanism of the action of UA.

Results

We obtained 318 UA drug targets and 1492 SCI disease targets. We identified a total of 118 common UA-SCI targets. Based on the PPI analysis, we identified MAPK1, SRC, AKT1, HRAS, MAPK8, HSP90AA1, MAPK14, JAK2, ESR1, and NF-κB1 as possible therapeutic targets. Enrichment analysis revealed that the PI3K-AKT, VEGF, and TNF signaling pathways could be critical for the NP analysis. Molecular docking indicated that UA had a strong affinity for docked proteins (binding energy range: -6.3 to -9.3 kcal mol-1).

Conclusions

We employed an NP approach to validate and predict the underlying mechanisms associated with UA therapy for SCI. An additional purpose of this study was to provide a theoretical basis for further experimental studies on UA's potential in SCI treatment.

Restoration of ER proteostasis attenuates remote apoptotic cell death after spinal cord injury by reducing autophagosome overload

The pathogenic mechanisms that underlie the progression of remote degeneration after spinal cord injury (SCI) are not fully understood. In this study, we examined the relationship between endoplasmic reticulum (ER) stress and macroautophagy, hereafter autophagy, and its contribution to the secondary damage and outcomes that are associated with remote degeneration after SCI. Using a rat model of spinal cord hemisection at the cervical level, we measured ER stress and autophagy markers in the axotomized neurons of the red nucleus (RN). In SCI animals, mRNA and protein levels of markers of ER stress, such as GRP78, CHOP, and GADD34, increased 1 day after the injury, peaking on Day 5. Notably, in SCI animals, the increase of ER stress markers correlated with a blockade in autophagic flux, as evidenced by the increase in microtubule-associated protein 2 light chain 3 (LC3-II) and p62/SQSTM1 (p62) and the decline in LAMP1 and LAMP2 levels. After injury, treatment with guanabenz protected neurons from UPR failure and increased lysosomes biogenesis, unblocking autophagic flux. These effects correlated with greater activation of TFEB and improved neuronal survival and functional recovery—effects that persisted after suspension of the treatment. Collectively, our results demonstrate that in remote secondary damage, impairments in autophagic flux are intertwined with ER stress, an association that contributes to the apoptotic cell death and functional damage that are observed after SCI.

Drug Discovery in Spinal Cord Injury With Ankylosing Spondylitis Identified by Text Mining and Biomedical Databases

Spinal cord injury (SCI) and ankylosing spondylitis (AS) are common inflammatory diseases in spine surgery. However, it is a project where the relationship between the two diseases is ambiguous and the efficiency of drug discovery is limited. Therefore, the study aimed to investigate new drug therapies for SCI and AS. First, text mining was used to obtain the interacting genes related to SCI and AS, and then, the functional analysis was conducted. Protein–protein interaction (PPI) networks were constructed by STRING online and Cytoscape software to identify hub genes. Last, hub genes and potential drugs were performed after undergoing drug–gene interaction analysis, and MicroRNA and transcription factors regulatory networks were also analyzed. Two hundred five genes common to “SCI” and “AS” identified by text mining were enriched in inflammatory responses. PPI network analysis showed that 30 genes constructed two significant modules. Ultimately, nine (SST, VWF, IL1B, IL6, CXCR4, VEGFA, SERPINE1, FN1, and PROS1) out of 30 genes could be targetable by a total of 13 drugs. In conclusion, the novel core genes contribute to a novel insight for latent functional mechanisms and present potential prognostic indicators and therapeutic targets in SCI and AS.

The neuroprotective effects of icariin on ageing, various neurological, neuropsychiatric disorders, and brain injury induced by radiation exposure

Epimedium brevicornum Maxim, a Traditional Chinese Medicine, has been used for the treatment of impotence, sinew and bone disorders, “painful impediment caused by wind-dampness,” numbness, spasms, hypertension, coronary heart disease, menopausal syndrome, bronchitis, and neurasthenia for many years in China. Recent animal experimental studies indicate that icariin, a major bioactive component of epimedium may effectively treat Alzheimer’s disease, cerebral ischemia, depression, Parkinson’s disease, multiple sclerosis, as well as delay ageing. Our recent study also suggested that epimedium extract could exhibit radio-neuro-protective effects and prevent ionizing radiation-induced impairment of neurogenesis. This paper reviewed the pharmacodynamics of icariin in treating different neurodegenerative and neuropsychiatric diseases, ageing, and radiation-induced brain damage. The relevant molecular mechanisms and its anti-neuroinflammatory, anti-apoptotic, anti-oxidant, as well as pro-neurogenesis roles were also discussed.

Icariin Attenuation of Diabetic Kidney Disease Through Inhibition of Endoplasmic Reticulum Stress via G Protein-Coupled Estrogen Receptors

Diabetic kidney disease (DKD) is the most common complication of diabetes mellitus and has become the primary cause of End-Stage Renal Disease (ESRD) globally. Icariin (ICA), an effective component extracted from Epimedium, has antiosteoporosis effect, antitumor effects, anti-ischemia effects, and other effects. In this study, a mouse DKD model was established, and Icariin solid nanoliposomes were administered to determine whether ICA had a protective effect on the renal function of DKD mice by regulating estrogen level and endoplasmic reticulum (ER) stress pathway. The results showed that the microalbumin/creatinine in urine, serum urea nitrogen, and CHOL in ICA cultured DKD mice significantly decreased, and mice nephropathy improved significantly. rat renal tubule epithelial cells were further tested, and the rat renal tubule epithelial cells were modeled by cultured cells with high glucose. The results showed that high glucose could promote the proliferation of renal tubular epithelial cells. Simultaneously, ICA can inhibit the proliferation of renal tubular epithelial cells and induce cell apoptosis. Furthermore, the expression of ER stress-related proteins IRE1 and XBP-1S was further detected. Additionally, to ICA intervention, a GPER antagonist (G-15) was added for intervention, the inhibitory effects of IRE1 and XBP-1S were reversed, and the ER stress pathway was activated. Cell experiments showed that ICA could promote GPER expression, while inhibiting GPER expression promoted the activation of ER stress pathway, and GPER expression was negatively correlated with ER stress protein expression. Therefore, the experiment proved that in DKD tissues, a high concentration of ICA can inhibit the ER stress response by promoting the expression of GPER, reducing the proliferation of diabetic nephropathy, and increasing the rate of tissue apoptosis.

Icariin accelerates cartilage defect repair by promoting chondrogenic differentiation of BMSCs under conditions of oxygen-glucose deprivation

This study explored the role played by combined ICA and bone mesenchymal stem cells (BMSCs) in repairing rabbit knee cartilage defects. Firstly, rabbit BMSCs were isolated and used to construct an in vitro cellular model of oxygen‐glucose deprivation/reoxygenation (OGD/R). Subsequently, ICA processing, Alcian blue staining, immunofluorescence and Western blot studies were performed to evaluate the ability of BMSCs to display signs of chondrogenic differentiation. Furthermore, a rabbit knee cartilage injury model was established in vivo. International Cartilage Repair Society (ICRS) macroscopic evaluations, H&E, Alcian blue and EdU staining, as well as immunohistochemistry, were analysed cartilage repair and pathological condition of the knee cartilage tissue. Our in vitro results showed that ICA promoted the chondrogenic differentiation of BMSCs, as well as aggrecan (AGR), bone morphogenetic protein 2 (BMP2) and COL2A1 protein expression in BMSCs. In vivo experiments showed that rabbits in the BMSCs or ICA treatment group had higher ICRS scores and displayed a better restoration of cartilage‐like tissue and chondrocyte expression on the surface of their cartilage defects. In conclusion, ICA or BMSCs alone could repair rabbit knee cartilage damage, and combined treatment with ICA and BMSCs showed a better ability to repair rabbit knee cartilage damage.

Attenuation of Activated eIF2α Signaling by ISRIB Treatment After Spinal Cord Injury Improves Locomotor Function

Following spinal cord injury (SCI), multiple signaling cascades are activated instantaneously in the injured segments of the spinal cord to create a complex and pathogenic microenvironment, making it difficult to treat SCI. Nevertheless, the significance of the integrated stress response (ISR) to the series of physiological and pathological changes that occur after SCI remains unclear. Through western blotting (WB), we determined that the autophosphorylation of stress receptors (GCN2, PERK, PKR, and HRI) was enhanced after SCI, leading to increased phosphorylation of eIF2α at Ser51. Strikingly, we found that eIF2α was highly phosphorylated at 1 day post injury (dpi) and that this hypophosphorylation was maintained thereafter in the spinal cord, especially in neurons, which suggests that intervening with eIF2α phosphorylation may be a treatment strategy for SCI. Therefore, we employed the small molecule ISRIB, which inhibits eIF2α phosphorylation when the ISR is activated at moderate or low levels but not when the ISR is highly activated. Daily intraperitoneal injection of ISRIB significantly inhibited ISR signaling after SCI, reduced the cytosolic localization of RNA-binding proteins, and decreased neuronal apoptosis. Histological and functional experiments further demonstrated that treatment with ISRIB after SCI effectively curbed morphological deterioration and promoted the recovery of locomotor function. In summary, the ISR plays an important role in SCI, and ISRIB is a promising drug for the treatment of SCI.

Dexmedetomidine alleviates traumatic spinal cord injury in rats via inhibiting apoptosis induced by endoplasmic reticulum stress

OBJECTIVE

To investigate the protective effect of dexmedetomidine (Dex) on traumatic spinal cord injury (TSCI) and to evaluate the involvement of inhibition of endoplasmic reticulum (ER) stress response in the potential mechanism.

METHOD

Sprague-Dawley rats were randomly divided into five groups. The hind limb locomotor function of rats was evaluated at 1, 3 and 7 days after the operation. At 7 days after the operation, spinal cord specimens were obtained for hematoxylin and eosin (H&E), Nissl and TUNEL staining, as well as immunofluorescence and Western blot analyses to detect the level of apoptosis and the levels of proteins related to ER stress.

RESULTS

7 days after the operation, Dex treatment promoted the recovery and also inhibited apoptosis of neurons in the spinal cord. Additionally, Dexinhibited the expression of proteins related to ER stress response after spinal cord injury.

CONCLUSIONS

Dex improves the neurological function of rats with TSCI and reduces apoptosis of spinal cord neurons. The potential mechanism is related to the inhibition of the ER stress response.

Human umbilical cord mesenchymal stem cells-derived extracellular vesicles facilitate the repair of spinal cord injury via the miR-29b-3p/PTEN/Akt/mTOR axis

Spinal cord injury (SCI) is a salient traumatic disease that often leads to permanent disability, and motor and sensory impairments. Human umbilical cord mesenchymal stem cells (HucMSCs) have a wide application prospect in the treatment of SCI. This study explored the repair effect of HucMSCs-derived extracellular vesicles (HucMSCs-EVs) on SCI. HucMSCs and HucMSCs-EVs were cultured and identified. The rat model of SCI was established, and SCI rats were treated with HucMSCs-EVs. The motor function of SCI rats and morphology of spinal cord tissues were evaluated. Levels of NeuN, GFAP, and NF200 in spinal cord tissues were detected and cell apoptosis was measured. SCI rats were treated with EVs extracted from miR-29b-3p inhibitor-transfected HucMSCs. The downstream gene and pathway of miR-29b-3p were examined. HucMSCs-EVs-treated rats showed obvious motor function recovery and reduced necrosis, nuclear pyknosis, and cavity. HucMSCs-EVs alleviated spinal cord neuronal injury. miR-29b-3p was poorly expressed in SCI tissues, but highly expressed in EVs and SCI rats treated with EVs. miR-29b-3p targeted PTEN. Inhibition of miR-29b-3p or overexpression of PTEN reversed the repair effect of EVs on SCI. EVs activated the AKT/mTOR pathway via the miR-29b-3p/PTEN. In conclusion, HucMSCs-EVs reduced pathological changes, improved motor function, and promoted nerve function repair in SCI rats via the miR-29b-3p/PTEN/Akt/mTOR axis.

FBXW7alpha Promotes the Recovery of Traumatic Spinal Cord

BACKGROUND

White matter damage and neuronal cell death are incurred by spinal cord injury (SCI). FBXW7α, an important mediator of cell division and growth was investigated to explore its role in repairing the traumatic spinal cord in rats. Underlying mechanisms such as oxidative stress and inflammasomes signaling were also studied.

METHODS

Spinal cord injury in rats was established by longitudinal surgical incision from the lower to mid-thoracic vertebrae on the backside, followed by 20-g weight placed on the exposed Th12 surface for 30 min. AAV-delivered FBXW7α and -sh-FBXW7α were intrathecally injected into the rat spinal cord. Indices of oxidation, neurotrophic factors, and pyroptosis were measured by Western blot, Elisa, and RT-PCR.

RESULTS

We found the overexpression of FBXW7α in spinal cord rescue neuronal death triggered by the injury. Specifically, the nutritional condition, oxidative stress, and pyroptosis were improved. A synchronization of BNDF and GDNF expression patterns in various groups indicated the secretion of neurotrophic factors affect the outcome of SCI. The SOD1, CAT, and GSH-px were suppressed after trauma but all restored in response to FBXW7α overexpression. Inflammasomes-activated pyroptosis was incurred after the injury, and relevant biomarkers such as GSDMD, caspase-1, caspase- 11, IL-1β, and IL-18 were down-regulated after the introduction of FBXW7α into the injured cord. Additionally, up-regulating FBXW7α also repaired the mitochondria dysfunction.

CONCLUSION

Our data indicate FBXW7α probably serves as an important molecular target for the therapy of spinal cord injury.

Long noncoding RNA ZFAS1 aggravates spinal cord injury by binding with miR-1953 and regulating the PTEN/PI3K/AKT pathway

Multiple evidence has shown that long non-coding RNAs (lncRNAs) are novel modulators in the development of many neurological diseases, including spinal cord injury (SCI). Recently, a novel lncRNA zinc finger antisense 1 (ZFAS1) has been found to facilitate the development of many human diseases. However, the effect of ZFAS1 in SCI has not been explored. In the present study, we used the SCI mouse models and LPS-treated BV-2 cellular models to explore the role of ZFAS1 in SCI. Basso Mouse Scale score was applied to reveal locomotor function. Cresyl violet staining was used to reveal volume of spared myelin around the lesion in the injured cord. RIP and luciferase reporter assay were applied to detect binding capacity among RNAs. Next, ZFAS1 was identified to be upregulated in spinal cord tissues of SCI mice. ZFAS1 knockdown promoted functional recovery and inhibited cell apoptosis and the inflammatory response in SCI mice. ZFAS1 bound with microRNA 1953 (miR-1953), and miR-1953 was downregulated in spinal cord tissues of SCI mice. Furthermore, we confirmed that ZFAS1 promoted SCI progression via binding with miR-1953. In addition, phosphatase and tensin homolog (PTEN) was verified to be a downstream target for miR-1953 in vitro, and PTEN was upregulated in spinal cord tissues of SCI mice. Finally, we illustrated that ZFAS1 inactivated the PI3K/AKT pathway through upregulation of PTEN. In conclusion, our study revealed that ZFAS1 facilitated SCI by binding with miR-1953 and regulating the PTEN/PI3K/AKT pathway, which may provide a potential novel insight for treatment of SCI.

Grape seed proanthocyanidins protect PC12 cells from hydrogen peroxide-induced damage via the PI3K/AKT signaling pathway

Grape seed proanthocyanidins (GSP) are natural flavonoids with strong antioxidant and anti-apoptotic effects. Oxidative stress and neuronal apoptosis are major contributors to spinal cord injury (SCI). In this study, we assessed the potential protective effects of GSP on hydrogen peroxide (H₂O₂)-damaged pheochromocytoma-12 (PC12) cells in an in vitro model of SCI as well as the putative mechanism of action. We established a model using PC12 cells with oxidative damage induced by H₂O₂. Cells were treated with various concentrations of GSP (control group, 200 μmol/L H₂O₂ group, 5 μM GSP + H₂O₂ group, 10 μM GSP + H₂O₂ group, and 25 μM GSP + H₂O₂ group). The CCK-8 assay was used to determine cell activity. Dichloro-dihydro-fluorescein diacetate was used to detect intracellular reactive oxygen species (ROS), and flow cytometry was used to determine apoptosis rate. Western blot analysis was used to detect the expression of caspase-3, Bax, Bcl-2, and PI3K/AKT proteins. The results showed that GSP reduced H₂O₂-induced intracellular ROS and inhibited apoptosis. Furthermore, GSP inhibited the expression of caspase-3 and Bax, while promoting the expression of Bcl-2. In addition, GSP promoted the phosphorylation of PI3K and AKT. Moreover, a PI3K inhibitor (LY294002) weakened the protective effects of GSP on H₂O₂-induced PC12 cells. In conclusion, GSP pretreatment can protect PC12 cells from oxidative damage induced by H₂O₂ via the PI3K/AKT signaling pathway.

Identification and analysis of spinal cord injury subtypes using weighted gene co-expression network analysis

Background

Spinal cord injury (SCI) has an immediate and devastating impact on the control over various movements and sensations. However, no effective therapies for SCI currently exist.

Methods

To identify and analyze SCI subtypes, we obtained the expression profile data of the 1,057 genes (889 intersection genes) in GSE45550 using weighted gene co-expression network analysis (WGCNA), and 14 co-expression gene modules were identified. Next, we filtered out the network degree top 10 (degree >80) genes, considered the final key SCI genes. A multifactor regulatory network (105 interaction pairs), consisting of messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), and transcription factors (TFs) was constructed. This network was involved in the co-expression of key genes. We selected the top 10 regulatory factors (degree >4) as core regulators in the multifactor regulatory network.

Results

The results of functional enrichment analysis of the target gene expressing the core regulatory factor [1,059] showed that these target genes were enriched in pathways for human cytomegalovirus infection, chronic myeloid leukemia, and pancreatic cancer. Further, we used the key genes in the co-expression network to categorize the SCI samples in GSE45550. The expression levels of the top 6 genes (CCNB2, CCNB1, CKS2, COL5A1, KIF20A, and RACGAP1) may act as potential marker genes for different SCI subtypes. On the basis of these different subtypes, 8 SCI core gene CDK1-associated drugs were also found to provide potential therapeutic options for SCI.

Conclusions

These results may provide a novel therapeutic strategy for the treatment of SCI.

Icariin ameliorates endothelial dysfunction in type 1 diabetic rats by suppressing ER stress via the PPARα/Sirt1/AMPKα pathway

Icariin (ICA), as a flavonoid glycoside, is associated with the improvement of vascular complications in diabetes. However, its protective mechanisms remain to be well-established. Here, we tested the hypothesis that ICA attenuates vascular endothelial dysfunction by inhibiting endoplasmic reticulum (ER) stress in type 1 diabetes. In streptozotocin-induced diabetic rats, ICA positively affected acetylcholine-induced vasodilation and phenylephrine-induced vasoconstriction in aortas. ICA treatment significantly attenuated ER stress in diabetic rats and high-glucose induced human umbilical vein endothelial cells. Incubation with ICA in vitro attenuated vascular reactivity in diabetic rats, which was blocked by the ER stress inducer, and peroxisome proliferator-activated receptor α (PPARα), sirtuin1 (Sirt1), or AMP-activated protein kinase-α (AMPKα) inhibitors. Western blot showed that ICA activated the PPARα/Sirt1/AMPKα pathway, which contributed to reducing ER stress and activating endothelial nitric oxide synthase in vivo and vitro. Our results implicate that ICA normalizes ER stress to attenuate endothelial dysfunction by the regulation of the PPARα/Sirt1/AMPKα pathway.

MicroRNA-211-5p attenuates spinal cord injury via targeting of activating transcription factor 6

The recovery of spinal cord injury (SCI) involves multiple factors, of which miRNAs take an important part. In this study, we evaluated the function of microRNA-211-5p (miR-211-5p) on SCI in a rat model. SCI model was established using modified Allen's weight-drop method and Basso-Bcattie-Bresnahan score was applied to assess the locomotor function. MiR-211-5p agomir was utilized to increase miR-211-5p expression and endoplasmic reticulum (ER) stress inhibitor, 4-PBA (4-phenylbutyric acid), was utilized to suppress ER stress. Neuron apoptosis and the expressions of miR-211-5p, activating transcription factor 6 (ATF6), apoptosis-related proteins, pro-inflammatory cytokines and endoplasmic reticulum stress-related proteins were detected. Dual luciferase reporter gene assay was performed to verify the binding between miR-211-5p and ATF6. The results showed that miR-211-5p directly targeted ATF6. MiR-211-5p was down-regulated and ATF6 was up-regulated in SCI rats. Both interferences with miR-211-5p agomir and 4-PBA effectively attenuated neuron apoptosis and reversed the expressions of apoptosis, inflammation and endoplasmic reticulum stress-related molecules post SCI in rats. These findings demonstrated that miR-211-5p could effectively alleviate SCI-induced neuron apoptosis and inflammation via directly targeting ATF-6 and regulating ER stress.

Rea regulates microglial polarization and attenuates neuronal apoptosis via inhibition of the NF-κB and MAPK signalings for spinal cord injury repair

Inflammation and neuronal apoptosis aggravate the secondary damage after spinal cord injury (SCI). Rehmannioside A (Rea) is a bioactive herbal extract isolated from Rehmanniae radix with low toxicity and neuroprotection effects. Rea treatment inhibited the release of pro-inflammatory mediators from microglial cells, and promoted M2 polarization in vitro, which in turn protected the co-cultured neurons from apoptosis via suppression of the NF-κB and MAPK signalling pathways. Furthermore, daily intraperitoneal injections of 80 mg/kg Rea into a rat model of SCI significantly improved the behavioural and histological indices, promoted M2 microglial polarization, alleviated neuronal apoptosis, and increased motor function recovery. Therefore, Rea is a promising therapeutic option for SCI and should be clinically explored.

Activating Transcription Factor 6 Contributes to Functional Recovery After Spinal Cord Injury in Adult Zebrafish

Spinal cord injury (SCI) is one of the most common devastating injuries, with little possibility of recovery in humans. However, zebrafish efficiently regenerate functional nervous system tissue after SCI. Therefore, the spinal cord transection model of adult zebrafish was applied to explore the role of ATF6 in neuro-recovery. Activating transcription factor 6 (ATF6) is a type-II transmembrane protein in the endoplasmic reticulum (ER). ATF6 target genes could improve ER homeostasis, which contributes to cytoprotection. Herein, we found that the ATF6 level increased at 12 h and 3 days post SCI, and returned to sham levels at 7 days post SCI. ATF6-expressing motor neurons were present in the central canal of the spinal cord and increased at 12 h post SCI. ATF6 morpholino treatment showed that inhibition of ATF6 delayed locomotor recovery and hindered neuron axon regrowth in SCI zebrafish. Furthermore, we investigated the role of both binding immunoglobulin protein (Bip) and C/EBP homologous transcription factor protein (CHOP), the two target genes of ATF6. We found that Bip expression significantly increased in the spinal cord at 7 days after SCI, which served as a pro-survival chaperone. Our results also showed that CHOP expression significantly decreased in the spinal cord at 7 days after SCI, which was identified as a protein involved in apoptosis. Taken together, our data demonstrate that ATF6 may contribute to the functional recovery after SCI in adult zebrafish, via up-regulation of Bip and down-regulation of CHOP to restore the homeostasis of ER.

Mechanism of tauroursodeoxycholic acid-mediated neuronal protection after acute spinal cord injury through AKT signaling pathway in rats

OBJECTIVE

To explore themechanism of tauroursodeoxycholic acid- (TUDCA) mediated neuronal protection after acute spinal cord injury (ASCI) in rats. Methods: ASCI rat model was established following modified Allen's weight-drop method and these rats were assigned to sham group (received sham operation), model group (ASCI rats), TUDCA group (ASCI rats received TUDCA treatment), MK2206 group (ASCI rats received AKT inhibitor MK2206 orally) and TUDCA + MK2206 group. Motor function of rats was evaluated using Basso Beattie Bresnahan (BBB) method. Hematoxylin-eosin (H&E) staining was used to detect histopathologic changes in the spinal cord and TUNEL fluorescence staining was used to check apoptosis. Real time fluorescence quantitative polymerase chain reaction (qRT-PCR) and western blot were employed to detect the production of AKT pathway related factors, apoptosis related factors (Bax, Bcl-2, caspase-3), autophagy related factor Beclin-1 and endoplasmic reticulum (ER) stress related factors (IRE1, Chop, ATF6) in spinal cord of rats.

RESULTS

Compared to the rats in the sham group, rats in ASCI group had decreased BBB scores (P<0.05), more significant tissue edema, structural cavity and apoptosis. Compared to rats in sham group, AKT pathway was inactivated in ASCI rats and was activated by TUDCA treatment (P<0.05). Compared to sham group, expressions of ER stress-related factors were increased, apoptosis was largely induced in other four groups, and expression of Beclin-1 was increased in the model group (P<0.05). TUDCA increased the expression of Beclin-1 and Bcl-2, and inhibited the expression of Bax, Caspase-3, and ER stress-related factors, thus suppressing apoptosis (P<0.05). Treatment by MK2206 had contrary effects and protective effects of TUDCA on ASCI rats could be counteracted by MK2206.

CONCLUSION

TUDCA can significantly improve the neural damage, enhance neuron autophagy, alleviate ER stress, and inhibit apoptosis in ASCI rats, by activating the AKT signaling pathway.

Accumulation of Asn450Tyr mutant myocilin in ER promotes apoptosis of human trabecular meshwork cells

PURPOSE

In a previous study, we identified the Asn450Tyr mutant myocilin gene (Myoc-N450Y) in the pedigree of families with juvenile open angle glaucoma (JOAG), but whether N450Y is a pathogenic mutation remained to be determined. The present study aimed at exploring the role of Myoc-N450Y in primary human trabecular meshwork (HTM) cells.

METHODS

Primary HTM cells were infected with lentivirus with wild-type myocilin (Myoc-WT) or Myoc-N450Y. Primary HTM cells overexpressing Myoc-WT or Myoc-N450Y was treated with sodium 4-phenylbutyrate (4-PBA) or not. The secretion and intracellular distribution of Myoc were analyzed with western blotting and immunofluorescence. Expression of endoplasmic reticulum (ER) stress-related proteins was detected with quantitative real-time PCR (qRT-PCR) and western blotting. Cell viability, apoptosis, and expression of the related proteins were examined with Cell Counting Kit-8 (CCK-8), flow cytometry analysis, and western blotting, respectively.

RESULTS

We found that non-secretion of Myoc-N450Y induced ER stress by colocalization with the ER marker calreticulin (CALR), and upregulating the expression of ER stress markers in primary HTM cells. Moreover, overexpression of Myoc-N450Y inhibited the viability and induced apoptosis of primary HTM cells, and inhibition of PI3K/AKT signaling was induced by ER stress. Reduction in ER stress with 4-PBA decreased the level of ER stress markers, promoted secretion, and prevented accumulation of myocilin in the Myoc-N450Y group. Apoptosis was rescued, and inhibition of PI3K/AKT signaling was reversed, after PBA treatment in primary HTM cells with Myoc-N450Y overexpression.

CONCLUSIONS

The study results suggest that Myoc-N450Y promotes apoptosis of primary HTM cells via the ER stress-induced apoptosis pathway, in which the PI3K/AKT signaling pathway plays a crucial role.