Sevoflurane preconditioning ameliorates neuronal deficits by inhibiting microglial MMP-9 expression after spinal cord ischemia/reperfusion in rats

The CXCL12/CXCR4 Axis: An Emerging Therapeutic Target for Chronic Pain

Chronic pain greatly affects patients' quality of life and poses significant challenges for the healthcare system. Conventional medication is generally inadequate for managing chronic pain and frequently leads to numerous adverse effects. The chemokine C-X-C motif ligand 12 (CXCL12) and its receptor, the chemokine C-X-C motif receptor 4 (CXCR4), are emerging as significant neuromodulators within the nervous system. A growing body of evidence has underscored the critical roles of this chemokine axis in the development and persistence of pathological pain. In this review, we aim to synthesize recent findings that highlight the role and mechanisms of the CXCL12/CXCR4 axis in the etiology of chronic pain conditions. We focus on chronic pain stemming from sciatic nerve injury, diabetic neuropathy, spinal cord injury, bone cancer, opioid tolerance, and opioid-induced hyperalgesia. These conditions represent a diverse range of pathologies that underscore the broad impact of the CXCL12/CXCR4 axis in pain management. Furthermore, we discuss the potential for targeting the CXCL12/CXCR4 axis as a comprehensive therapeutic strategy for chronic pain. In this review, we aim to summarize emerging evidence on the critical role of the CXCL12/CXCR4 signaling in mediating chronic pain pathogenesis and its potential contributions to neurological disorders.

The Role of Desflurane in the Functional Outcomes Among Spinal Cord Injury Patients Undergoing Upper Extremity Nerve Transfer Procedures

Background and objective While several experimental studies have demonstrated the neuroprotective role of volatile anesthetics after spinal cord injury (SCI), the impact of volatile anesthetics on improving neurologic outcomes in spinal cord-injured patients is not known. Hence, this study aimed to examine the impact of volatile anesthetics on functional outcomes of chronic cervical SCI patients undergoing peripheral nerve transfer procedures. Methods We conducted a retrospective analysis involving adult patients with cervical SCI and upper extremity paralysis undergoing nerve transfer procedures between September 1, 2015, and January 31, 2019. The principal outcome measured was the motor strength of the reinnervated muscle targets assessed per the Medical Research Council (MRC) scale graded from 0 to 5. Secondary outcomes included Disabilities of Arm, Shoulder, and Hand (DASH); Sollerman Hand Function Test (SHFT); and Michigan Hand Questionnaire (MHQ) scores. Univariate analysis and logistic regression were performed to examine the association between the volatile anesthetics (sevoflurane, desflurane) used during the nerve transfer surgery with the improvement in muscle strength examined up to 48 months postoperatively. Results A total of 13 tetraplegic patients with a mean age of 39.2 ± 15.9 years were included in this study. We found that the desflurane group (n=22 muscles) had greater median motor strength than the sevoflurane group (n=60 muscles) towards the final follow-up when the desflurane group had median motor strength of 3 [interquartile range (IQR): 1-4] and sevoflurane group had a median motor strength of 1 (IQR: 0-2.25); p=0.014. However, there was no statistically significant difference between the two groups in the DASH, SHFT, and MHQ scores. Logistic regression analysis showed that type of nerve transfer and preop AIS (ASIA Impairment Scale) grade were significantly associated with higher odds of improvement of motor power by at least 2 grades. Conclusions Our preliminary data show an association between desflurane use and improved motor strength in SCI patients undergoing peripheral nerve transfers. The data suggest that volatile anesthetic conditioning-induced protection observed in preclinical studies may also exist in SCI patients. This will need to be validated in a larger sample size. Examining the therapeutic window, and identifying the molecular mechanisms underlying volatile anesthetic conditioning-induced protection are warranted to aid future translational studies.

Propofol alleviates spinal cord ischemia-reperfusion injury by preserving PI3K/AKT/GIT1 axis

Spinal cord ischemia-reperfusion injury (SCIRI) is a major contributor to neurological damage and mortality associated with spinal cord dysfunction. This study aims to explore the possible mechanism of Propofol and G-protein-coupled receptor-interacting protein 1 (GIT1) in regulating SCIRI in rat models. SCIRI rat models were established and injected with Propofol, over expression of GIT1 (OE-GIT1), or PI3K inhibitor (LY294002). The neurological function was assessed using Tarlov scoring system, and Hematoxylin & Eosin (H&E) staining was applied to observe morphology changes in spinal cord tissues. Cell apoptosis, blood-spinal cord barriers (BSCB) permeability, and inflammatory cytokines were determined by TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, evans blue (EB) staining, and enzyme-linked immuno sorbent assay (ELISA), respectively. Reverse transcription-quantitative polymerase chain reaction and western blot were used to detect the expression levels of GIT1, endothelial nitric oxide synthase (eNOS), PI3K/AKT signal pathway and apoptosis-related proteins. SCIRI rats had decreased expressions of GIT1 and PI3K/AKT-related proteins, whose expressions can be elevated in response to Propofol treatment. LY294002 can also decrease GIT1 expression levels in SCIRI rats. Propofol can attenuate neurological dysfunction induced by SCIRI, decrease spinal cord tissue injury and BSCB permeability in addition to suppressing cell apoptosis and inflammatory cytokines, whereas further treatment by LY294002 can partially reverse the protective effect of Propofol on SCIRI. Propofol can activate PI3K/AKT signal pathway to increase GIT1 expression level, thus attenuating SCIRI in rat models.

Liquiritin ameliorates painful diabetic neuropathy in SD rats by inhibiting NLRP3-MMP-9-mediated reversal of aquaporin-4 polarity in the glymphatic system

Background

Despite advancements in diabetes treatment, the management of Painful Diabetic Neuropathy (PDN) remains challenging. Our previous research indicated a significant correlation between the expression and distribution of Aquaporin-4 (AQP4) in the spinal glymphatic system and PDN. However, the potential role and mechanism of liquiritin in PDN treatment remain uncertain.

Methods

This study established a rat model of PDN using a combination of low-dose Streptozotocin (STZ) and a high-fat, high-sugar diet. Rats were treated with liquiritin and MCC950 (an NLRP3 inhibitor). We monitored fasting blood glucose, body weight, and mechanical allodynia periodically. The glymphatic system's clearance function was evaluated using Magnetic Resonance Imaging (MRI), and changes in proteins including NLRP3, MMP-9, and AQP4 were detected through immunofluorescence and Western blot techniques.

Results

The rats with painful diabetic neuropathy (PDN) demonstrated several physiological changes, including heightened mechanical allodynia, compromised clearance function within the spinal glymphatic system, altered distribution of AQP4, increased count of activated astrocytes, elevated expression levels of NLRP3 and MMP-9, and decreased expression of AQP4. However, following treatment with liquiritin and MCC950, these rats exhibited notable improvements.

Conclusion

Liquiritin may promote the restoration of AQP4 polarity by inhibiting NLRP3 and MMP-9, thereby enhancing the clearance functions of the spinal cord glymphatic system in PDN rats, alleviating the progression of PDN.

The role of lncRNAs related ceRNA regulatory network in multiple hippocampal pathological processes during the development of perioperative neurocognitive disorders

Background

Perioperative neurocognitive disorders (PND) refer to neurocognitive abnormalities during perioperative period, which are a great challenge for elderly patients and associated with increased morbidity and mortality. Our studies showed that long non-coding RNAs (lncRNAs) regulate mitochondrial function and aging-related pathologies in the aged hippocampus after anesthesia, and lncRNAs are associated with multiple neurodegenerations. However, the regulatory role of lncRNAs in PND-related pathological processes remains unclear.

Methods

A total of 18-month mice were assigned to control and surgery (PND) groups, mice in PND group received sevoflurane anesthesia and laparotomy. Cognitive function was assessed with fear conditioning test. Hippocampal RNAs were isolated for sequencing, lncRNA and microRNA libraries were constructed, mRNAs were identified, Gene Ontology (GO) analysis were performed, and lncRNA-microRNA-mRNA networks were established. qPCR was performed for gene expression verification.

Results

A total of 312 differentially expressed (DE) lncRNAs, 340 DE-Transcripts of Uncertain Coding Potential (TUCPs), and 2,003 DEmRNAs were identified in the hippocampus between groups. The lncRNA-microRNA-mRNA competing endogenous RNA (ceRNA) network was constructed with 29 DElncRNAs, 90 microRNAs, 493 DEmRNAs, 148 lncRNA-microRNA interaction pairs, 794 microRNA-mRNA interaction pairs, and 110 lncRNA-mRNA co-expression pairs. 795 GO terms were obtained. Based on the frequencies of involved pathological processes, BP terms were divided into eight categories: neurological system alternation, neuronal development, metabolism alternation, immunity and neuroinflammation, apoptosis and autophagy, cellular communication, molecular modification, and behavior changes. LncRNA-microRNA-mRNA ceRNA networks in these pathological categories were constructed, and involved pathways and targeted genes were revealed. The top relevant lncRNAs in these ceRNA networks included RP23-65G6.4, RP24-396L14.1, RP23-251I16.2, XLOC_113622, RP24-496E14.1, etc., and the top relevant mRNAs in these ceRNA networks included Dlg4 (synaptic function), Avp (lipophagy), Islr2 (synaptic function), Hcrt (regulation of awake behavior), Tnc (neurotransmitter uptake).

Conclusion

In summary, we have constructed the lncRNA-associated ceRNA network during PND development in mice, explored the role of lncRNAs in multiple pathological processes in the mouse hippocampus, and provided insights into the potential mechanisms and therapeutic gene targets for PND.

ADAMTS13 deficiency exacerbates neuroinflammation by targeting matrix metalloproteinase-9 in ischemic brain injury

Our design aimed to explore the potential involvement of matrix metalloproteinase-9 (MMP-9) in the inflammatory response associated with acute ischemic stroke (AIS). We also aimed to preliminarily examine the potential impact of a disintegrin-like and metalloprotease with thrombospondin type I repeats-13 (ADAMTS13) on MMP-9 in AIS. We conducted oxygen-glucose deprivation models of microglia cells and mice models of AIS with middle cerebral artery occlusion (MCAO). We assessed the expression pattern of MMP-9 with western blotting (WB) and real-time quantitative PCR both in vivo and in vitro. MMP-9 downregulation was achieved by using ACE inhibitors such as trandolapril. For the MCAO model, we used ADAMTS13-deficient mice. We then evaluated the related neurological function scores, cerebral edema and infarct volume. The levels of inflammation-related proteins, such as COX2 and iNOS, were assessed using WB, and the expression of inflammatory cytokines was measured via enzyme-linked immuno sorbent assay in vivo. Our findings indicated that MMP-9 was up-regulated while ADAMTS13 was down-regulated in the MCAO model. Knockdown of MMP-9 reduced both inflammation and ischemic brain injury. ADAMTS13 prevented brain damage, improved neurological function and decreased the inflammation response in mice AIS models. Additionally, ADAMTS13 alleviated MMP-9-induced neuroinflammation in vivo. It showed that ADAMTS13 deficiency exacerbated ischemic brain injury through an MMP-9-dependent inflammatory mechanism. Therefore, the ADAMTS13-MMP-9 axis could have therapeutic potential for the treatment of AIS.

Effect of General Anesthetic Agents on Microglia

The effects of general anesthetic agents (GAAs) on microglia and their potential neurotoxicity have attracted the attention of neuroscientists. Microglia play important roles in the inflammatory process and in neuromodulation of the central nervous system. Microglia-mediated neuroinflammation is a key mechanism of neurocognitive dysfunction during the perioperative period. Microglial activation by GAAs induces anti-inflammatory and pro-inflammatory effects in microglia, suggesting that GAAs play a dual role in the mechanism of postoperative cognitive dysfunction. Understanding of the mechanisms by which GAAs regulate microglia may help to reduce the incidence of postoperative adverse effects. Here, we review the actions of GAAs on microglia and the consequent changes in microglial function. We summarize clinical and animal studies associating microglia with general anesthesia and describe how GAAs interact with neurons via microglia to further explore the mechanisms of action of GAAs in the nervous system.

Administration with curcumin alleviates spinal cord ischemia-reperfusion injury by regulating anti-oxidative stress and microglia activation-mediated neuroinflammation via Nrf2/NF-κB axis

Spinal cord ischemia-reperfusion injury (SCII) ranks as the common complication after aortic surgery, usually leading to devastating post-operative paraplegia. Microglia over-activation and neuronal cell loss are key pathological features of SCII. Curcumin is involved in several I/R injuries. However, its underlying mechanism in SCII remains elusive. Here, curcumin attenuated oxygen and glucose deprivation/reoxygenation (OGD/R)-induced oxidative injury in PC12 neuronal cells by increasing cell viability, inhibiting cell apoptosis, lactate dehydrogenase, malondialdehyde levels, but elevating anti-oxidative superoxide dismutase and glutathione peroxidase levels. Furthermore, curcumin restrained OGD/R-evoked microglia M1 activation by decreasing microglia M1 polarization marker IBA-1 and iNOS transcripts. Moreover, the increased inflammatory cytokine levels of TNF-α and IL-6 in microglia under OGD/R conditions were suppressed after curcumin treatment. Importantly, neuronal cells incubated with a conditioned medium from OGD/R-treated microglia exhibited lower cell viability and higher apoptotic ratio, which were overturned when microglia were treated with curcumin. Intriguingly, curcumin could inhibit the activation of the NF-κB pathway by Nrf2 enhancement in OGD/R-treated PC12 cells and microglia. Notably, targeting Nrf2 signaling reversed the protective efficacy of curcumin against OGD/R-evoked oxidative insult in neuronal, microglia M1 activation, inflammatory response, and microglial activation-evoked neuronal death. In vivo, curcumin improved histopathologic injury and neurologic motor function in SCII rats and attenuated oxidative stress, microglia activation and neuroinflammation in spinal cord tissues, and activation of the Nrf2/NF-κB pathway. Thus, curcumin may alleviate SCII by mitigating I/R-evoked oxidative injury in neuron and microglia activation-induced neuroinflammation and neuron death through Nrf2/NF-κB signaling, supporting a promising therapeutic agent for SCII.

Reduced inhibitory and excitatory input onto parvalbumin interneurons mediated by perineuronal net might contribute to cognitive impairments in a mouse model of sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is commonly defined as diffuse brain dysfunction and can manifest as delirium to coma. Accumulating evidence has suggested that perineuronal net (PNN) plays an important role in the modulation of the synaptic plasticity of central nervous system. We here investigated the role of PNN in SAE induced by lipopolysaccharide (LPS) injection. Behavioral tests were performed by open field, Y-maze, and fear conditioning tests at the indicated time points. The densities of vesicular γ-aminobutyric acid transporter, vesicular glutamate transporter 1, PNN, and parvalbumin (PV) in the hippocampus were evaluated by immunofluorescence. Matrix metalloproteinases-9 (MMP-9) expression and its activity were detected by Western blot and gel zymography, respectively. Local field potential was recorded by in vivo electrophysiology. LPS-treated mice displayed significant cognitive impairments, coincided with activated MMP-9, decreased PNN and PV densities, reduced inhibitory and excitatory input onto PV interneurons enwrapped by PNN, and decreased gamma oscillations in hippocampal CA1. Notably, MMP-9 inhibitor SB-3CT treatment rescued most of these abnormalities. Taken together, our study demonstrates that active MMP-9 mediated PNN remodeling, leading to reduced inhibitory and excitatory input onto PV interneurons and abnormal gamma oscillations in hippocampal CA1, which consequently contributed to cognitive impairments after LPS injection.

Peroxiredoxin-6 Released by Astrocytes Contributes to Neuroapoptosis During Ischemia

Peroxiredoxin-6 (PRDX6), a member of the peroxiredoxin family, has progressively emerged as a possible therapeutic target for a variety of brain diseases, particularly Alzheimer's disease and ischemic stroke. However, the role of PRDX6 in neurons under ischemic conditions has remained elusive. Here, we found that astrocytes could release PRDX6 extracellularly after OGD/R, and that PRDX6 release actually worsened neuroapoptosis under OGD/R. We discovered a unique PRDX6/RAGE/JNK signaling pathway that contributes to the effect of neuroapoptosis. We applied a specific inhibitor of the RAGE signaling pathway in a mouse MCAO model and observed significant alterations in animal behavior. Considered together, our findings show the crucial role of the astrocyte-released PRDX6 in the process of neuroapoptosis caused by OGD/R, and could provide novel insights for investigating the molecular mechanism of protecting brain function from ischemia-reperfusion injury.

Dexmedetomidine postconditioning alleviates spinal cord ischemia-reperfusion injury in rats via inhibiting neutrophil infiltration, microglia activation, reactive gliosis and CXCL13/CXCR5 axis activation

PURPOSE

Spinal cord ischemia-reperfusion (I/R) injury is an unresolved complication and its mechanisms are still not completely understood. Here, we studied the neuroprotective effects of dexmedetomidine (DEX) postconditioning against spinal cord I/R injury in rats and explored the possible mechanisms.

MATERIALS AND METHODS

In the study, rats were randomly divided into five groups: sham group, I/R group, DEX0.5 group, DEX2.5 group, and DEX5 group. I/R injury was induced in experimental rats; 0.5 μg/kg, 2.5 μg/kg, 5 μg/kg DEX were intravenously injected upon reperfusion respectively. Neurological function, histological assessment, and the disruption of blood-spinal cord barrier (BSCB) were evaluated via the BBB scoring, hematoxylin and eosin staining, Evans Blue (EB) extravasation and spinal cord edema, respectively. Neutrophil infiltration was evaluated via Myeloperoxidase (MPO) activity. Microglia activation and reactive gliosis was evaluated via ionized calcium-binding adapter molecule-1(IBA-1) and glial fibrillary acidic protein (GFAP) immunofluorescence, respectively. The expression of C-X-C motif ligand 13 (CXCL13), C-X-C chemokine receptor type 5(CXCR5), caspase-3 was determined by western blotting. The expression levels of interleukin 6(IL-6), tumor necrosis factor-α(TNF-α), IL-1β were determined by ELISA assay.

RESULTS

DEX postconditioning preserved neurological assessment scores, improved histological assessment scores, attenuated BSCB leakage after spinal cord I/R injury. Neutrophil infiltration, microglia activation and reactive gliosis were also inhibited by DEX postconditioning. The expression of CXCL13, CXCR5, caspase-3, IL-6, TNF-α, IL-1β were reduced by DEX postconditioning.

CONCLUSIONS

DEX postconditioning alleviated spinal cord I/R injury, which might be mediated via inhibition of neutrophil infiltration, microglia activation, reactive gliosis and CXCL13/CXCR5 axis activation.

Albumin alleviated esketamine-induced neuronal apoptosis of rat retina through downregulation of Zn2+-dependent matrix metalloproteinase 9 during the early development

Aims

Esketamine upregulates Zn²⁺-dependent matrix metalloproteinase 9 (MMP9) and increases the neuronal apoptosis in retinal ganglion cell layer during the early development. We aimed to test whether albumin can alleviate esketamine-induced apoptosis through downregulating Zn²⁺-dependent MMP9.

Methods

We investigate the role of Zn²⁺ in esketamine-induced neuronal apoptosis by immunofluorescence. MMP9 protein expression and enzyme activity were investigated by zymography in situ., western blot and immunofluorescence. Whole-mount retinas from P7 Sprague-Dawley rats were used.

Results

We demonstrated that esketamine exposure increased Zn²⁺ in the retinal GCL during the early development. Zn²⁺-dependent MMP9 expression and enzyme activity up-regulated, which eventually aggravated apoptosis. Albumin effectively down-regulated MMP9 expression and activity via binding of free zinc, ultimately protected neurons from apoptosis. Meanwhile albumin treatment promoted activated microglia into multi-nucleated macrophagocytes and decreased the inflammation.

Conclusion

Albumin alleviates esketamine-induced neuronal apoptosis through decreasing Zn²⁺ accumulation in GCL and downregulating Zn²⁺-dependent MMP9.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00753-5.

Whole-transcriptome sequencing identifies neuroinflammation, metabolism and blood-brain barrier related processes in the hippocampus of aged mice during perioperative period

AIM

Perioperative neurocognitive disorders (PND) occur frequently after surgery and anesthesia, especially in aged patients. Previous studies have shown multiple PND related mechanisms in the hippocampus; however, their relationships remain unclear. Meanwhile, the perioperative neuropathological processes are sophisticated and changeable, single period study could not reveal the accurate mechanisms. Thus, multiperiod whole-transcriptome study is necessary to elucidate the gene expression patterns during perioperative period.

METHODS

Aged C57BL/6 mice were subjected to exploratory laparotomy under sevoflurane anesthesia. Whole-transcriptome sequencing (RNA-seq analysis) was performed on the hippocampi from control condition (Con), 30 min (Day0), 2 days (Day2), and 7 days (Day7) after surgery. Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analyses, quantitative real-time PCR, immunofluorescence, and fear conditioning test were also performed to elucidate the pathological processes and modulation networks during the period.

RESULTS

Through RNA-seq analysis, 328, 3597, and 4179 differentially expressed genes (DEGs) were screened out in intraoperative period (Day0 vs. Con), early postoperative period (Day2 vs. Day0), and late postoperative period (Day7 vs. Day2). The involved GO biological processes were divided into 9 categories, and positive-regulated processes were more than negative-regulated ones. Seventy-four transcription factors were highlighted. The potential synaptic and neuroinflammatory pathways were constructed for Neurotransmitter, Synapse and Neuronal alteration categories with 9 genes (Htr1a, Rims1, and Ezh2, etc.). The metabolic and mitochondrial pathways were constructed for metabolism, oxidative stress, and biological rhythm categories with 9 genes (Gpld1, Sirt1, and Cry2, etc.). The blood-brain barrier and neurotoxicity related pathways were constructed for blood-brain barrier, neurotoxicity, and cognitive function categories with 10 genes (Mmp2, Itpr1, and Nrf1, etc.).

CONCLUSION

The results revealed gene expression patterns and modulation networks in the aged hippocampus during perioperative period, which provide insights into overall mechanisms and potential therapeutic targets for prevention and treatment of perioperative central nervous system diseases, such as PND, from the genetic level.

Construction and Comprehensive Analysis of the ceRNA Network to Reveal Key Genes for Benign Tracheal Stenosis

Objective: To explore the possible biological functions of the differentially expressed genes in patients with benign tracheal stenosis, and to provide a valuable molecular basis for investigating the pathogenesis of benign tracheal stenosis.

Method: Whole transcriptome sequencing was performed on blood samples collected from patients with benign tracheal stenosis and normal controls. Differentially expressed mRNA, lncRNA, and circRNA were analyzed using the DESeq2 package. The protein interaction networks for differentially expressed mRNAs were constructed by STRING. The results of gene co-expression network analysis, Starbase database prediction, and differential gene expression were combined to construct a competing endogenous RNA network. The transcription factors of key genes were predicted using the Network Analyst database and a transcription factor-mRNA regulatory network was constructed. The classical pathways, intermolecular interaction networks, and upstream regulatory components of key genes were analyzed using Ingenuity Pathway Analysis (IPA). Finally, the DGIDB database was used to predict the potential therapeutic drugs to target the identified key genes.

Result: Based on mRNA, lncRNA and circRNA expression data, we found that differentially expressed mRNAs were enriched in oxygen transport, neutrophil activation, immune response, and oxygen binding. Then the pearson correlation between mRNAs of 46 key genes and lncRNAs and cricRNAs were calculated, and the correlation greater than 0.9 were selected to construct the co-expression network of “mRNA-lncRA” and “mRNA-cricRNA.” Moreover, a “lncRNA-miRNA-mRNA” network and a “circRNA-miRNA-mRNA” network were constructed. IPA analysis showed that the 46 key genes were significantly associated with inflammatory activation and acute respiratory distress syndrome. The constructed TF-mRNA regulatory network was composed of 274 nodes and 573 interacting pairs. 251 potential therapeutic drugs were identified from the DGIDB database.

Conclusion: This study analyzed the differential genes associated with benign tracheal stenosis and explored the potential regulatory mechanisms, providing a scientific reference for further studies on the pathogenesis of benign tracheal stenosis.

Inhibiting the aberrant PACT-p53 axis activation ameliorates spinal cord ischaemia-reperfusion injury in rats

Spinal cord ischaemia-reperfusion injury (SCII) induces multiple molecular and cellular changes, resulting in dyskinesia. Recently, it is reported that the p53 network plays a vital role in SCII. However, the roles of the PACT/PRKRA (interferon-inducible double-stranded RNA-dependent protein kinase activator A)-p53 axis in SCII are still unclear. The aim of this study was to elucidate the roles of the PACT-p53 axis in SCII. A Sprague-Dawley rat model of SCII was established by subjecting rats to a 14-min occlusion of the aortic arch. The Tarlov criteria, Western blotting, double immunofluorescence staining, haematoxylin and eosin (HE) staining, and transferase dUTP nick end labelling (TUNEL) assay were performed after SCII. Here, spinal cord ischaemia-reperfusion (SCI) caused hindlimb motor functional deficits as assessed by the Tarlov criteria. The protein expression of PACT was substantially upregulated at 48 h after SCII. Increased PACT fluorescence was mainly localized to neurons. Si-PACT pretreatment improved hindlimb motor function, ameliorated histological changes, and attenuated cell apoptosis after SCII. Si-PACT pretreatment reduced the protein expression of PACT, p53, Caspase-8 and IL-1β and the number of double-labelled PACT and p53. Taken together, inhibiting the aberrant PACT-p53 axis activation by si-PACT pretreatment ameliorates SCI-induced neuroapoptosis and neuroinflammation in rats. Silencing PACT expression is promising new therapeutic strategy for SCII.

Blood-Spinal Cord Barrier: Its Role in Spinal Disorders and Emerging Therapeutic Strategies

The blood-spinal cord barrier (BSCB) has been long thought of as a functional equivalent to the blood-brain barrier (BBB), restricting blood flow into the spinal cord. The spinal cord is supported by various disc tissues that provide agility and has different local immune responses compared to the brain. Though physiologically, structural components of the BSCB and BBB share many similarities, the clinical landscape significantly differs. Thus, it is crucial to understand the composition of BSCB and also to establish the cause-effect relationship with aberrations and spinal cord dysfunctions. Here, we provide a descriptive analysis of the anatomy, current techniques to assess the impairment of BSCB, associated risk factors and impact of spinal disorders such as spinal cord injury (SCI), amyotrophic lateral sclerosis (ALS), peripheral nerve injury (PNI), ischemia reperfusion injury (IRI), degenerative cervical myelopathy (DCM), multiple sclerosis (MS), spinal cavernous malformations (SCM) and cancer on BSCB dysfunction. Along with diagnostic and mechanistic analyses, we also provide an up-to-date account of available therapeutic options for BSCB repair. We emphasize the need to address BSCB as an individual entity and direct future research towards it.

MicroRNA-101a-3p mimic ameliorates spinal cord ischemia/reperfusion injury

miR-101a-3p is expressed in a variety of organs and tissues and plays a regulatory role in many diseases, but its role in spinal cord ischemia/reperfusion injury remains unclear. In this study, we established a rat model of spinal cord ischemia/reperfusion injury by clamping the aortic arch for 14 minutes followed by reperfusion for 24 hours. Results showed that miR-101a-3p expression in L4–L6 spinal cord was greatly decreased, whereas MYCN expression was greatly increased. Dual-luciferase reporter assay results showed that miR-101a-3p targeted MYCN. MYCN immunoreactivity, which was primarily colocalized with neurons in L4–L6 spinal tissue, greatly increased after spinal cord ischemia/reperfusion injury. However, intrathecal injection of an miR-101a-3p mimic within 24 hours before injury decreased MYCN, p53, caspase-9 and interleukin-1β expression, reduced p53 immunoreactivity, reduced the number of MYCN/NeuN-positive cells and the number of necrotic cells in L4–L6 spinal tissue, and increased Tarlov scores. These findings suggest that the miR-101a-3p mimic improved spinal ischemia/reperfusion injury-induced nerve cell apoptosis and inflammation by inhibiting MYCN and the p53 signaling pathway. Therefore, miR-101a-3p mimic therapy may be a potential treatment option for spinal ischemia/reperfusion injury.

Autophagy of Spinal Microglia Affects the Activation of Microglia through the PI3K/AKT/mTOR Signaling Pathway

Delayed paralysis occurs within some patients suffered from ischemic spinal cord injury (ISCI) due to the aorta occlusion during the repair surgery of thoracic and thoracoabdominal aortic aneurysms. Although mild hypothermia has been reported to improve ISCI and prolong the tolerance of rats to ISCI without inducing immediate paralysis, the mechanism remains unclear. Herein, the study revealed that the mild hypothermia treatment indeed partially improved the ISCI in rats caused by cross-clamping at the descending aorta. ISCI induced the excessive activation of microglia and moderate autophagy in the spinal cord tissues of rats, while mild hypothermia significantly induced autophagy and reversed the excessive activation of microglia in the spinal cord tissues of rats. In OGD-stimulated mouse microglia BV-2 cells, the excessive activation of microglia and moderate autophagy were also observed; in the rapamycin-treated OGD model in BV-2 cells, autophagy was significantly enhanced whereas the excessive activation of microglia was reversed. In both in vivo ISCI model in rats and in vitro OGD model in BV-2 cells, the PI3K/AKT/mTOR pathway showed to be inhibited, whereas the PI3K/AKT/mTOR pathway was further inhibited by mild hypothermia in ISCI rats or rapamycin treatment in OGD-stimulated BV-2 cells. In conclusion, enhanced autophagy might be the mechanism of inhibited microglia activation by hypothermia treatment in ISCI rats and by rapamycin treatment in OGD-stimulated BV-2 cells. Autophagy could be enhanced through inhibiting the PI3K/AKT/mTOR pathway.

Blocking the EGFR/p38/NF-κB signaling pathway alleviates disruption of BSCB and subsequent inflammation after spinal cord injury

Epidermal growth factor receptor (EGFR) activation is involved in blood spinal cord barrier (BSCB) disruption and secondary injury after spinal cord injury (SCI). However, the underlying mechanisms of EGFR activation mediating BSCB disruption and secondary injury after SCI remain unclear. An in vitro model of oxygen and glucose deprivation/reoxygenation (OGD/R) induced BSCB damage and in vivo rat SCI model were employed to define the role of EGFR/p38/NF-κB signal pathway activation and its induced inflammatory injury in main cellular components of BSCB. Genetic regulation (lentivirus delivered shRNA and overexpression system) or chemical intervention (agonist or inhibitor) were applied to activate or inactivate EGFR and p38 in astrocytes and microvascular endothelial cells (MEC) under which conditions, the expression of pro-inflammatory factors (TNF-α, iNOS, COX-2, and IL-1β), tight junction (TJ) protein (ZO-1 and occludin), nuclear translocation of NF-κB and permeability of BSCB were analyzed. The pEGFR was increased in astrocytes and MEC which induced the activation of EGFR and p38 and NF-κB nuclear translocation. The activation of EGFR and p38 increased the TNF-α, iNOS, COX-2, and IL-1β responsible for the inflammatory injury and reduced the ZO-1 and occludin which caused BSCB disruption. While EGFR or p38 inactivation inhibited NF-κB nuclear translocation, and markedly attenuated the production of pro-inflammatory factors and the loss of TJ protein. This study suggests that the EGFR activation in main cellular components of BSCB after SCI mediates BSCB disruption and secondary inflammatory injury via the EGFR/p38/NF-κB pathway.

Perillaldehyde Alleviates Spinal Cord Ischemia-Reperfusion Injury Via Activating the Nrf2 Pathway

BACKGROUND

Spinal Cord ischemia-reperfusion injury (SCII) is one of the most destructive complications in thoracic-abdominal aortic surgery, which can cause physical abnormalities, paralysis and even brain death. Evidence has shown that perillaldehyde (PAH) can ameliorate rat's cerebra ischemia-reperfusion injury. However, the effect of PAH on SCII remains unknown.

METHODS

The current study established SCII rat models and oxygen and glucose deprivation/reoxygenation-induced BV2 microglia models to explore whether PAH could alleviate SCII symptoms and to investigate underlying mechanism.

RESULTS

SCII rats underwent severe neurologic motor dysfunction and histopathologic injury compared with the normal rats, which are exhibited by loss of motor neurons and decrease of nissl bodies. Treatment with PAH significantly ameliorated motor dysfunction and neuron damage. PAH downregulated the expression of NLR family pyrin domain containing 3, cleaved/pro caspase-1, interleukin-1β and interleukin-18 in spinal cord tissues of SCII rats. Besides, the contents of oxidative stress-related factors superoxide dismutase, manganese-dependent superoxide dismutase, catalase and glutathione peroxidase were significantly increased and malondialdehyde content was decreased after PAH treatment. PAH treatment upregulated the expression of nuclear factor-E2-related factor 2 and heme oxygenase-1 in spinal cord tissues of SCII rats. Our in vitro study confirmed that PAH inhibited microglial activation by activating the nuclear factor-E2-related factor 2/heme oxygenase-1 pathway, exhibited by alleviated inflammation and oxidative stress.

CONCLUSIONS

This study elucidates that PAH has the potential value for treating SCII, which provides an experimental basis for clinical trials in the future.

Identification of the biological function of miR-9 in spinal cord ischemia-reperfusion injury in rats

Spinal cord ischemia–reperfusion injury (SCII) is still a serious problem, and the mechanism is not fully elaborated. In the rat SCII model, qRT-PCR was applied to explore the altered expression of miR-9 (miR-9a-5p) after SCII. The biological function of miR-9 and its potential target genes based on bioinformatics analysis and experiment validation in SCII were explored next. Before the surgical procedure of SCII, miR-9 mimic and inhibitor were intrathecally infused. miR-9 mimic improved neurological function. In addition, miR-9 mimic reduced blood-spinal cord barrier (BSCB) disruption, inhibited apoptosis and decreased the expression of IL-6 and IL-1β after SCII. Gene Ontology (GO) analysis demonstrated that the potential target genes of miR-9 were notably enriched in several biological processes, such as “central nervous system development”, “regulation of growth” and “response to cytokine”. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the potential target genes of miR-9 were significantly enriched in several signaling pathways, including “Notch signaling pathway”, “MAPK signaling pathway”, “Focal adhesion” and “Prolactin signaling pathway”. We further found that the protein expression of MAP2K3 and Notch2 were upregulated after SCII while miR-9 mimic reduced the increase of MAP2K3 and Notch2 protein. miR-9 mimic or MAP2K3 inhibitor reduced the release of IL-6 and IL-1β. miR-9 mimic or si-Notch2 reduced the increase of cleaved-caspase3. Moreover, MAP2K3 inhibitor and si-Notch2 reversed the effects of miR-9 inhibitor. In conclusion, overexpression of miR-9 improves neurological outcomes after SCII and might inhibit BSCB disruption, neuroinflammation, and apoptosis through MAP2K3-, or Notch2-mediated signaling pathway in SCII.

Interferon-β alleviates delayed tPA-induced adverse effects via modulation of MMP3/9 production in ischemic stroke

Tissue plasminogen activator (tPA) is the only US Food and Drug Administration (FDA)-approved drug for ischemic stroke. However, delayed tPA administration is associated with increased risk of blood-brain barrier (BBB) disruption and hemorrhagic transformation (HT). Interferon-β (IFNβ), an FDA-approved drug for the treatment of multiple sclerosis, is a cytokine with immunomodulatory properties. Previous studies, including ours, demonstrated that IFNβ or type I IFN receptor signaling conferred protection against ischemic stroke in preclinical models, suggesting IFNβ might have translational therapeutic potential for the treatment of ischemic stroke. Currently, whether IFNβ could be coadministered with tPA to alleviate delayed tPA-induced adverse effects remains unknown. To elucidate that, IFNβ was coadministered with delayed tPA to ischemic stroke animals, and the severity and pathology of ischemic brain injury were assessed. We found delayed tPA treatment exacerbated ischemic brain injury, manifested by aggravated BBB disruption and HT. Notably, IFNβ ameliorated delayed tPA-exacerbated brain injury and alleviated adverse effects. Mechanistic studies revealed IFNβ suppressed tPA-enhanced neuroinflammation and MMP3/9 production in the ischemic brain. Furthermore, we identified IFNβ suppressed MMP9 production in microglia and attenuated tight junction protein degradation in brain endothelial cells. Moreover, we observed that peripheral immune cells may participate to a lesser extent in delayed tPA-exacerbated brain injury during the early phase of ischemic stroke. In conclusion, we provide the first evidence that IFNβ can be coadministered with tPA to mitigate delayed tPA-induced adverse effects of BBB disruption and HT that could potentially extend the tPA therapeutic window for the treatment of ischemic stroke.

Sevoflurane pretreatment regulates abnormal expression of MicroRNAs associated with spinal cord ischemia/reperfusion injury in rats

Background

Spinal cord ischemia/reperfusion injury (SCII) is one of the most serious spinal cord complications that stem from varied spine injuries or thoracoabdominal aortic surgery. Nevertheless, the molecular mechanisms underlying the SCII remain unclear.

Methods

Male Sprague-Dawley (SD) rats were randomly divided into 5 groups of sham, SCII 24 h, SCII 72 h, sevoflurane preconditioning SCII 24 h (SCII 24 h+sevo), and sevoflurane preconditioning SCII 72 h (SCII 72 h+sevo) group. We then analyzed the expression of differentially expressed micro RNAs (DEmiRNAs) in these groups and their target genes. Functional enrichment analysis of their target genes was further performed using Metascape software. The microRNA-messenger RNA-pathway (miRNA-mRNA-pathway) network and the sevoflurane-miRNA-mRNA-pathway integrative network were further constructed to explore the molecular mechanisms underlying SCII and neuroprotective effects of sevoflurane against SCII. Molecular docking was also performed to evaluate the interactions between hub targets and sevoflurane. Finally, the expression levels of miR-21-5p and its target genes [mitogen-activated protein kinase kinase 3 and protein phosphatase 1 regulatory subunit 3B (MAP2K3 and PPP1R3B)] were measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses.

Results

We found that sevoflurane alters several miRNA expression following SCII at 24 and 72 h after reperfusion. It was shown that miR-221-3p, miR-181a-1-3p, and miR-21-5p were upregulated both at 24 and 72 h in the sevoflurane pre-treatment reperfusion groups. Functional enrichment analysis revealed that target genes for the above co-DEmiRNAs at 24 and 72 h in the SCII group with sevoflurane pretreatment participated in the mitogen-activated protein kinase (MAPK), ErbB, apoptosis, and transforming growth factor-beta (TGF-beta) signaling pathways. Both MAP2K3 and PPP1R3B were found to be common targets for sevoflurane and miRNA-mRNA-pathway (rno-miR-21-5p). It was shown that MAP2K3 regulates the MAPK signaling and the T cell receptor signaling pathways, whereas PPP1R3B regulates the ErbB signaling pathway. Molecular docking further revealed that sevoflurane strongly binds the MAP2K3 and PPP1R3B proteins. Compared to the sham group, SCII induced significant under-expression of miR-21-5p but upregulated PPP1R3B and MAP2K3 proteins; sevoflurane pretreatment increased the expression of miR-21-5p but decreased those of PPP1R3B and MAP2K3 proteins.

Conclusions

In general, sevoflurane regulates the expression of several miRNAs following SCII. In particular, sevoflurane might protect against SCII via regulating the expression of miR-21-5p, its target genes (MAP2K3 and PPP1R3B), and related signaling pathways.

The effect of long-term doxycycline treatment in a mouse model of cigarette smoke-induced emphysema and pulmonary hypertension

Chronic obstructive pulmonary disease (COPD) is a major cause of death and a still incurable disease, comprising emphysema and chronic bronchitis. In addition to airflow limitation, patients with COPD can suffer from pulmonary hypertension (PH). Doxycycline, an antibiotic from the tetracycline family, in addition to its pronounced antimicrobial activity, acts as a matrix metalloproteinase (MMP) inhibitor and has anti-inflammatory properties. Furthermore, doxycycline treatment exhibited a beneficial effect in several preclinical cardiovascular disease models. In preclinical research, doxycycline is frequently employed for gene expression modulation in Tet-On/Tet-Off transgenic animal models. Therefore, it is crucial to know whether doxycycline treatment in Tet-On/Tet-Off systems has effects independent of gene expression modulation by such systems. Against this background, we assessed the possible curative effects of long-term doxycycline administration in a mouse model of chronic CS exposure. Animals were exposed to cigarette smoke (CS) for 8 mo and then subsequently treated with doxycycline for additional 3 mo in room air conditions. Doxycycline decreased the expression of MMPs and general pro-inflammatory markers in the lungs from CS-exposed mice. This downregulation was, however, insufficient to ameliorate CS-induced emphysema or PH. Tet-On/Tet-Off induction by doxycycline in such models is a feasible genetic approach to study curative effects at least in established CS-induced emphysema and PH. However, we report several parameters that are influenced by doxycycline and use of a Tet-On/Tet-Off system when evaluating those parameters should be interpreted with caution.

Differentially expressed genes induced by β-caryophyllene in a rat model of cerebral ischemia-reperfusion injury

Experimental studies have shown that β-caryophyllene (BCP) improved neurological deficits of cerebral ischemia-reperfusion injury (CIRI) rats resulting from Middle Cerebral Artery Occlusion (MCAO). However, research on targets of BCP on CIRI has not been completed. In this study, the mRNA sequencing was used to distinguish various therapeutic multiple targets of BCP on CIRI. Differentially expressed genes (DEGs) were identified from RNA-seq analysis. CIRI induced up-regulated genes (CIRI vs. Sham) and BCP -induced down-regulated genes (BCP vs CIRI) were identified. Significant DEGs were identified only that expressed in each of all samples. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis of significant DEGs were determined by cluster Profiler. Protein interactive network (PPI) was analyzed using the String tool and Hub genes was identified by cytoHubba. Transcription factor (TF) regulatory network for the potential Hub genes was constructed. Western blot and ELISA were used to verified hub genes and relative inflammatory cytokines. After mRNA sequencing, a total of 411 DEGs were filtered based on the 2 series (CIRI vs. Sham and CIRI vs. BCP), with Pax1, Cxcl3 and Ccl20 are the most remarkable ones reversed by BCP. GO analysis was represented by DEGs involved in multiple biological process such as extra-cellular matrix organization, leukocyte migration, regulation of angiogenesis, reactive oxygen species metabolic process, etc. KEGG analysis showed that DEGs participated several signaling pathways including MAPK signaling pathway (rno04010), Cytokine-cytokine receptor interaction (rno04060), JAK-STAT signaling pathway (rno04630), and others. The protein-protein interaction (PPI) network consisted of 339 nodes and 1945 connections, and top ten Hub genes were identified by cytoHubba such as TIMP1, MMP-9, and STAT3. Subsequently, a TFs-miRNAs-targets regulatory network was established, involving 6 TFs, 5 miRNAs, and 10 hub genes, consisting of several regulated models such as Brd4 - rno-let-7e - Mmp9, Brd4 - rno-let-7i - Stat3, and Hnf4a- rno-let-7b -Timp1. Finally, western blot demonstrated that BCP could inhibit the increased TIMP1, MMP-9 and STAT3 expression in rat brains after I/R. ELISA represented that BCP could suppress inflammatory cytokines caused by CIRI and present anti-oxidative property. In conclusion, this study shows that the intervention of BCP can significantly reduce neurologic deficit, improve the cerebral ischemia, and a total of ten hub genes were found closely related to the treatment of BCP on CIRI. Prudent experimental validation suggests that the BCP might have the neuro-protective effects in CIRI by decreasing the expression of MMP-9 and TIMP-1, STAT3. In a sense, this study reveals that the MMP-9/TIMP-1 signaling pathway may be involved in the injury after CIRI and thus provides a new treatment strategy as well as a researching method for stroke.

Sevoflurane alleviates oxygen-glucose deprivation/reoxygenation-induced injury in HT22 cells through regulation of the PI3K/AKT/GSK3β signaling pathway

Sevoflurane (Sev), a volatile anesthetic, has been reported to exhibit beneficial effects on different ischemia/reperfusion (I/R)-injured organs. However, the neuroprotective effect of Sev on cerebral I/R injury is poorly understood. In the present study, the effects of Sev on HT22 cells exposed to oxygen-glucose deprivation/reperfusion (OGD/R) injury are investigated. The present study demonstrated that OGD/R suppressed the cell viability and increased lactate dehydrogenase (LDH) release from the cells, and these effects were attenuated by Sev treatment. The results also demonstrated that Sev alleviated OGD/R-induced cell apoptosis via flow cytometry and caspase-3 activity determination. Biochemical analysis results revealed that Sev significantly protected against OGD/R-induced oxidative stress by reducing ROS generation and improving antioxidant defense markers. Western blot analysis demonstrated that Sev reactivated the PI3K/AKT/glycogen synthase kinase-3β (GSK3β) signaling pathway, which was inhibited by OGD/R. In addition, wortmannin, a selective PI3K inhibitor was used to investigate the underlying pathways. Notably, the neuroprotective effect of Sev on apoptosis and reactive oxygen species production was found to be suppressed by wortmannin. Collectively, these results demonstrated that Sev may protect neuronal cells against OGD/R-induced injury through the activation of the PI3K/AKT/GSK3β signaling pathway. The findings from the present study provide a novel insight into understanding the neuroprotective effect of Sev on cerebral I/R injury.

Sevoflurane Post-treatment Upregulated miR-203 Expression to Attenuate Cerebral Ischemia-Reperfusion-Induced Neuroinflammation by Targeting MyD88

To investigate the expression of miR-203 by sevoflurane treatment and its effect on neuroinflammation induced by cerebral ischemia-reperfusion. Rats were randomly divided into sham operation group (C), cerebral ischemia-reperfusion group (I/R), and sevoflurane treatment group (S). The neurological function score was evaluated. The area of cerebral infarction was evaluated by TTC staining. The expression of inflammatory factor in brain tissue was detected by ELISA. The apoptosis of neurons was detected by TUNEL. A miR-203 agonist and inhibitor treated the cerebral ischemia-reperfusion model. The luciferase assay verified whether miR-203 targeted MyD88. To further verify the relationship between miR-203 and MyD88, the I/R group was treated with MyD88 activator and inhibitor, and the mRNA expressions of miR-203 and MyD88 in brain tissue were detected by RT-PCR. Western blot was used to detect the expression of MyD88 protein in brain tissue, and the above experiment was repeated. Compared with the I/R group, miR-203 mRNA was significantly increased in brain tissue and the neurological function score, the area of cerebral infarction, the expression of inflammatory factor, and MyD88 mRNA were decreased in the S group (P < 0.05). After treatment of miR-203 agonist and inhibitor in the I/R group, overexpression of miR-203 could alleviate cerebral ischemia-reperfusion injury, and miR-203 inhibitor could aggravate cerebral ischemia-reperfusion injury. The miR-203 agonist could enhance the action of sevoflurane, and the miR-203 inhibitor could reverse the action of sevoflurane. miR-203 agonist treatment could inhibit the expression of MyD88 gene and protein and reduce the neuroinflammation induced by cerebral ischemia-reperfusion. The treatment of sevoflurane upregulated miR-203 expression, which targeted MyD88 and attenuate neuroinflammation induced by cerebral ischemia-reperfusion.

STAT3 Suppresses Cardiomyocytes Apoptosis in CVB3-Induced Myocarditis Via Survivin

Background: Viral myocarditis (VMC) is a common inflammatory cardiovascular disease with unclear mechanisms, which mainly affects children and adolescents. Apoptosis is the key to CVB3-induced myocarditis, and blocking this process may be beneficial to the therapy of VMC. Hence, this study aimed to explore the protective function of STAT3 on cardiomyocyte apoptosis of VMC and its underlying mechanisms.

Methods and Results: In this research, we confirmed that STAT3 was significantly activated in both animal and cell models of VMC. To further clarify what role did STAT3 play in VMC, AG490, an inhibitor of STAT3, was used to suppress p-STAT3. Our results demonstrated that decreased expression of p-STAT3 caused by AG490 significantly aggravated severity of VMC with elevated myocardial inflammation, deteriorative ventricular systolic function and increased mortality. It suggested that STAT3 plays a protective role in VMC. To further identify the anti-apoptosis impact that activated STAT3 made, we constructed lentivirus to regulate the expression of STAT3 in NMCs. We found that up-regulated activated STAT3 attenuated cardiomyocyte apoptosis, but down-regulated one aggravated that, which verified activated STAT3 played an anti-apoptosis role in VMC. Following that, we explored what elements are involved in the anti-apoptotic mechanism of activated STAT3 by using survivin inhibitor YM155. The result showed the anti-apoptotic effect of activated STAT3 does not work in the case of survivin inhibition.

Conclusion: Our findings demonstrated STAT3 by targeting survivin alleviated cardiomyocyte apoptosis in CVB3-induced myocarditis.

Protective effects of sevoflurane in cerebral ischemia reperfusion injury: a narrative review

Ischemia/reperfusion (I/R) injury is a phenomenon that the reperfusion of ischemic organs or tissues aggravates their damage, which poses a serious health threat and economic burden to the world. I/R gives rise to a series of physiological and pathological world, including inflammatory response, oxidative stress, brain edema, blood-brain barrier destruction, and neuronal death. Therefore, finding effective treatment measures is extremely important to the recovery of I/R patients and the improvement of long-term quality of life. Sevoflurane is an important volatile anesthetic which has been reported to reduce myocardial I/R damage and infarct size. Sevoflurane also has anti-inflammatory and neuroprotective effects. As reported sevoflurane treatment could reduce nerve function injury, cerebral infarction volume and the level of inflammatory factors. At the same time, there is evidence that sevoflurane can reduce neuron apoptosis and antioxidant stress. The protective effect of sevoflurane in brain injury has been proved to be existed in several aspects, so that a comprehensive understanding of its neuroprotective effect is helpful to exploit new treatment paths for I/R, provide clinicians with new clinical treatment decisions, contribute to the effective treatment of I/R patients and the improvement of quality of life after I/R healing.

MiR-128-3p Alleviates Spinal Cord Ischemia/Reperfusion Injury Associated Neuroinflammation and Cellular Apoptosis via SP1 Suppression in Rat

BACKGROUND

Neuroinflammation and cellular apoptosis caused by spinal cord ischemia/reperfusion (I/R) injury result in neurological dysfunction. MicroRNAs (miRs) have crucial functions in spinal cord I/R injury pathogenesis according to previous evidences. Herein, whether miR-128-3p contributes to spinal cord I/R injury by regulating specificity protein 1 (SP1) was assessed.

METHODS

A rat model of spinal cord I/R injury was established by occluding the aortic arch for 14 min. Then, miR-128-3p's interaction with SP1 was detected by dual-luciferase reporter assays. Next, miR-128-3p mimic and inhibitor, as well as adenovirus-delivered shRNA specific for SP1 were injected intrathecally for assessing the effects of miR-128-3p and SP1 on rats with spinal cord I/R injury. SP1, Bax and Bcl-2 expression levels in I/R injured spinal cord tissues were evaluated by Western blotting, while IL-1β, TNF-α, and IL-6 were quantitated by ELISA. Tarlov scores were obtained to detect hind-limb motor function. Evans blue (EB) dye extravasation was utilized to examine blood-spinal cord barrier (BSCB) permeability. Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining was performed for neuronal apoptosis assessment.

RESULTS

MiR-128-3p expression was decreased, while SP1 amounts were increased in rat spinal cord tissue specimens following I/R. SP1 was identified as a miR-128-3p target and downregulated by miR-128-3p. MiR-128-3p overexpression or SP1 silencing alleviated I/R-induced neuroinflammation and cell apoptosis, and improved Tarlov scores, whereas pretreatment with miR-128-3p inhibitor aggravated the above injuries.

CONCLUSION

Overexpression of miR-128-3p protects neurons from neuroinflammation and apoptosis during spinal cord I/R injury partially by downregulating SP1.

Downregulation of LncRNA Gas5 inhibits apoptosis and inflammation after spinal cord ischemia-reperfusion in rats

Spinal cord ischemia-reperfusion injury(SCII)affects nerve function through many mechanisms, which are complex and not fully understood. Recently, accumulating evidence has indicated that long noncoding RNAs (lncRNAs) play an increasingly important role in SCII. We investigated the role of lncRNA growth arrest-specific 5(Gas5) in a rat SCII model, and its effects on apoptosis and inflammation possibly by modulating MMP-7, cleaved caspase-3 and IL-1β. LncRNA Gas5 and MMP-7 were knocked down by intrathecal siRNA injection. Neurological assessment and TUNEL assay were performed. The RNA and protein expression levels of lncRNA Gas5, MMP-7, cleaved caspase-3 and IL-1β were determined by PCR and Western blotting, respectively. MMP-7 localization was visualized by double-immunofluorescence. SCII induced functional impairment in the hind limb, and the expression of lncRNA Gas5 was highest at 24 h after SCII. LncRNA Gas5 downregulation inhibited the RNA and protein expression of MMP-7, as well as the protein expression of cleaved caspase-3 and IL-1β. LncRNA Gas5 downregulation reduced the number of TUNEL-positive and MMP-7-positive double-labeled cells. Therefore, lncRNA Gas5 downregulation alleviated hind limb functional impairment and improved neuronal apoptosis after SCII. MMP-7 downregulation also inhibited apoptosis and inflammation and alleviated damage. Pretreatment with intrathecal injection of si-lncRNA Gas5 and si-MMP-7 reduced the expression levels of cleaved caspase-3 and IL-1β, protecting nerve function after SCII. These results show that lncRNA Gas5 plays an important role in SCII, perhaps by inhibiting MMP-7, cleaved caspase-3 and IL-1β. LncRNA Gas5 downregulation could be a promising therapeutic approach in the SCII treatment.

Involvement of the miR-137-3p/CAPN-2 Interaction in Ischemia-Reperfusion-Induced Neuronal Apoptosis through Modulation of p35 Cleavage and Subsequent Caspase-8 Overactivation

Background

Neuron survival after ischemia-reperfusion (IR) injury is the primary determinant of motor function prognosis. MicroRNA- (miR-) based gene therapy has gained attention recently. Our previous work explored the mechanisms by which miR-137-3p modulates neuronal apoptosis in both in vivo and in vitro IR models.

Methods

IR-induced motor dysfunction and spinal calpain (CAPN) subtype expression and subcellular localization were detected within 12 h post IR. Dysregulated miRs, including miR-137-3p, were identified by miR microarray analysis and confirmed by PCR. A luciferase assay confirmed CAPN-2 as a corresponding target of miR-137-3p, and their modulation of motor function was evaluated by intrathecal injection with synthetic miRs. CAPN-2 activity was measured by the intracellular Ca²⁺ concentration and mean fluorescence intensity in vitro. Neuronal apoptosis was detected by flow cytometry and TUNEL assay. The activities of p35, p25, Cdk5, and caspase-8 were evaluated by ELISA and Western blot after transfection with specific inhibitors and miRs.

Results

The IR-induced motor dysfunction time course was closely associated with upregulated expression of the CAPN-2 protein, which was mainly localized in neurons. The miR-137-3p/CAPN-2 interaction was confirmed by luciferase assay. The miR-137-3p mimic significantly improved IR-induced motor dysfunction and decreased CAPN-2 expression, even in combination with recombinant rat calpain-2 (rr-CALP2) injection, whereas the miR-137-3p inhibitor reversed these effects. Similar changes in the intracellular Ca²⁺ concentration, CAPN-2 expression, and CAPN-2 activity were observed when cells were exposed to oxygen-glucose deprivation and reperfusion (OGD/R) and transfected with synthetic miRs in vitro. Moreover, double fluorescence revealed identical neuronal localization of CAPN-2, p35, p25, and caspase-8. The decrease in CAPN-2 expression and activity was accompanied by the opposite changes in p35 activity and protein expression in cells transfected with the miR-137-3p mimic, roscovitine (a Cdk5 inhibitor), or Z-IETD-FMK (a caspase-8 inhibitor). Correspondingly, the abovementioned treatments resulted in a higher neuron survival rate than that of untreated neurons, as indicated by decreases in the apoptotic cell percentage and p25, Cdk5, caspase-8, and caspase-3 protein expression.

Conclusions

The miR-137-3p/CAPN-2 interaction modulates neuronal apoptosis during IR injury, possibly by inhibiting CAPN-2, which leads to p35 cleavage and inhibition of subsequent p25/Cdk5 and caspase-8 overactivation.

lncRNAs Are Involved in Sevoflurane Anesthesia-Related Brain Function Modulation through Affecting Mitochondrial Function and Aging Process

Long noncoding RNAs (lncRNAs) play important roles in brain function modulation and neurodegenerative diseases. However, whether lncRNA regulations are involved in the mechanisms of perioperative neurocognitive disorders, especially in anesthesia-related brain dysfunction, remain unknown. Therefore, we explored the expression and regulation pattern profiles of lncRNAs in the hippocampus of aged rats after sevoflurane anesthesia. Three lncRNAs and 772 protein-coding genes were identified by microarray analysis and evidenced by in vitro and in vivo experiments as differentially expressed. Functional annotation and differentially expressed- (DE-) lncRNA-mRNA coexpression networks reveal that DE-lncRNAs are associated with mitochondrial dysfunction and oxidative stress, aging-related metabolism alterations, DNA damage, and apoptosis, as well as neurodegenerative features during sevoflurane anesthesia. These results suggest that lncRNAs play roles in general anesthesia-related brain function modulation during the perioperative context and provide insights into the lncRNA-related modulation mechanisms and targets.

DNA Methylation Manipulation of Memory Genes Is Involved in Sevoflurane Induced Cognitive Impairments in Aged Rats

DNA methylation is an essential epigenetic mechanism involving in gene transcription modulation. An age-related increase in promoter methylation has been observed for neuronal activity and memory genes, and participates in neurological disorders. However, the position and precise mechanism of DNA methylation for memory gene modulation in anesthesia related cognitive impairment remained to be determined. Here, we studied the effects of sevoflurane anesthesia on the transcription of memory genes in the aged rat hippocampus. Then, we investigated changes in DNA methylation of involved genes and verified whether dysregulated DNA methylation would contribute to anesthesia induced cognitive impairment. The results indicated that sevoflurane anesthesia down-regulated the mRNA and protein levels of three memory genes, Arc, Bdnf, and Reln, which were accompanied with promoter hypermethylation and increased Dnmt1, Dnmt3a, and Mecp2 expression, and finally impaired hippocampus dependent memory. Furthermore, inhibition of DNA hypermethylation by 5-Aza rescued sevoflurane induced memory gene expression decrease and cognitive impairment. These findings provide an epigenetic understanding for the pathophysiology of cognitive impairment induced by general anesthesia in aged brain.

MicroRNA-22-3p alleviates spinal cord ischemia/reperfusion injury by modulating M2 macrophage polarization via IRF5

Cell death after spinal cord ischemia/reperfusion (I/R) can occur through necrosis, apoptosis, and autophagy, resulting in changes to the immune environment. However, the molecular mechanism of this immune regulation is not clear. Accumulating evidence indicates that microRNAs (miRs) play a crucial role in the pathogenesis of spinal cord I/R injury. Here, we hypothesized miR-22-3p may be involved in spinal cord I/R injury by interacting with interferon regulatory factor (IRF) 5. Rat models of spinal cord I/R injury were established by 12-min occlusion of the aortic arch followed by 48-hr reperfusion, with L_4-6 segments of spinal cord tissues collected. MiR-22-3p agomir, a lentivirus-delivered siRNA specific for IRF5, or a lentivirus expressing wild-type IRF5 was injected intrathecally to rats with I/R injury to evaluate the effects of miR-22-3p and IRF5 on hindlimb motor function. Macrophages isolated from rats were treated with miR-22-3p mimic or siRNA specific for IRF5 to evaluate their effects on macrophage polarization. The levels of IL-1β and TNF-α in spinal cord tissues were detected by ELISA. miR-22-3p was down-regulated, whereas IRF5 was up-regulated in rat spinal cord tissues following I/R. IRF5 was a target gene of miR-22-3p and could be negatively regulated by miR-22-3p. Silencing IRF5 or over-expressing miR-22-3p relieved inflammation, elevated Tarlov score, and reduced the degree of severity of spinal cord I/R injury. Increased miR-22-3p facilitated M2 polarization of macrophages and inhibited inflammation in tissues by inhibiting IRF5, thereby attenuating spinal cord I/R injury. Taken together, these results demonstrate that increased miR-22-3p can inhibit the progression of spinal cord I/R injury by repressing IRF5 in macrophages, highlighting the discovery of a promising new target for spinal cord I/R injury treatment.

Genome-Wide Screen of the Hippocampus in Aged Rats Identifies Mitochondria, Metabolism and Aging Processes Implicated in Sevoflurane Anesthesia

Previous studies have shown multiple mechanisms and pathophysiological changes after anesthesia, and genome-wide studies have been implemented in the studies of brain aging and neurodegenerative diseases. However, the genome-wide gene expression patterns and modulation networks after general anesthesia remains to be elucidated. Therefore, whole transcriptome microarray analysis was used to explore the coding gene expression patterns in the hippocampus of aged rats after sevoflurane anesthesia. Six hundred and thirty one upregulated and 183 downregulated genes were screened out, then 44 enriched terms of biological process, 16 of molecular function and 18 of the cellular components were identified by Gene Ontology (GO) and KEGG analysis. Among them, oxidative stress, metabolism, aging, and neurodegeneration were the most enriched biological processes and changed functions. Thus, involved genes of these processes were selected for qPCR verification and a good consistency was confirmed. The potential signaling pathways were further constructed including mitochondrion and oxidative stress-related Hifs-Prkcd-Akt-Nfe2l2-Sod1 signaling, multiple metabolism signaling (Scd2, Scap-Hmgcs2, Aldh18a1-Glul and Igf1r), as well as aging and neurodegeneration related signaling (Spidr-Ercc4-Cdkn1a-Pmaip1 and Map1lc3b). These results provide potential therapeutic gene targets for brain function modulation and memory formation process after inhaled anesthesia in the elderly, which could be valuable for preventing postoperative brain disorders and diseases, such as perioperative neurocognitive disorders (PND), from the genetic level in the future.

Exogenous activation of cannabinoid-2 receptor modulates TLR4/MMP9 expression in a spinal cord ischemia reperfusion rat model

Background

Cannabinoid-2 receptor (CB2R) plays an important role in the cascading inflammation following ischemic injury. The toll-like receptors 4 (TLR4)/matrix metalloproteinase 9 (MMP9) signal pathway is involved in blood-brain barrier dysfunction induced by ischemia stroke. The aim of this study is to investigate the roles of exogenous activation of CB2R on attenuating neurological deficit and blood-spinal cord barrier (BSCB) disruption during rat spinal cord ischemia reperfusion (I/R) injury, through modulation of the TLR4/MMP9 axis.

Methods

Animals were intraperitoneally pretreated with TLR4 inhibitor TAK-242, CB2R agonist JWH-133 with or without CB2R antagonist AM630, or equivalent volume of vehicle 1 h before undergoing 14-min occlusion of descending aorta or sham operation. One, two, three, and 7 days after reperfusion, hindlimb locomotor function was evaluated with Basso, Beattie, and Bresnahan (BBB) Locomotor Scale, BSCB integrity was detected by measurement of Evans blue (EB) extravasation and spinal cord edema. The protein expression levels of CB2R, tight junction protein Zonula occluden-1 (ZO-1), TLR4, MMP9, MyD88, NF-κB p65, and NF-κB p-p65 were determined by western blot. The MMP9 activity was analyzed by gelatin zymography. Double immunofluorescence staining was used to identify the perivascular localization of CB2R, TLR4, MMP9, and reactive astrocytes, as well as the colocalization of CB2R, TLR4, and MMP9 with reactive astrocytes.

Results

JWH-133 pretreatment attenuated hindlimb motor functional deficit and BSCB leakage, along with preventing downregulation of ZO-1 and upregulation of TLR4/MMP9, similar to the effects of TAK-242 preconditioning. JWH-133 or TAK-242 pretreatment reduced the perivascular expression of TLR4/MMP9 and reactive astrocytes following injury. JWH-133 pretreatment also downregulated MyD88/NF-κB level, MMP9 activity, and the astrocytic TLR4/MMP9 after I/R injury.

Conclusions

Exogenous activation of CB2R by JWH-133 attenuated neurological deficit and BSCB disruption after spinal cord I/R injury via inhibition of TLR4/MMP9 expression.

May sevoflurane prevent the development of neurogenic pulmonary edema and improve the outcome? Or as a new sedation method for severe brain injury patients

Neurogenic pulmonary edema (NPE) is a life-threatening complication that develops rapidly and dramatically after injury to the central nervous system (CNS). Severe primary brain injury and subsequent secondary brain injury cascade events are thought to be involved in the development of NPE. Activation of the sympathetic nervous system and release of vasoactive substances are also essential prerequisites for NPE. We hypothesize that sevoflurane may be an effective treatment for preventing the development of NPE. Sevoflurane may play a role in protecting brain and lung tissue after acute brain injury through its sympatholytic, antioxidative, ion channel stabilizing, anti-inflammatory, anti-apoptotic, and pulmonary protection effects. It has the potential to be used as a sedative in the neurosurgical intensive care unit (NICU), which can help maintain nervous system and cardiopulmonary function in patients with acute brain injury to improve prognosis. Sevoflurane also has the advantages of fast induction of anesthesia, rapid drug metabolism, little interference to the cardiovascular system, and controllable depth of anesthesia. If our hypothesis is supported by further experiments, use of sevoflurane may open a new door for the treatment of acute brain injury and NPE.

Sevoflurane suppresses migration and invasion of glioma cells by regulating miR-146b-5p and MMP16

Background: Glioma is the most common brain tumor with poor prognosis all over the world. Anesthetics have been demonstrated to have important impacts on cell migration and invasion in different cancers. However, the underlying mechanism that allows anesthetics-mediated progression of glioma cells remains elusive. Methods: Sevoflurane (Sev), a class of common anesthetics, was used to expose to U87-MG and U251 cells. The expressions of microRNA-146b-5p (miR-146b-5p) and matrix metallopeptidase 16 (MMP16)were measured by quantitative real-time polymerase chain reaction or western blot. Transfection was performed in glioma cells with miR-146b-5p inhibitor, inhibitor negative control, MMP16 overexpression vector, empty vector, small interfering RNA against MMP16 or scramble. Cell migration and invasion were analyzed by the trans-well assay. The interaction between miR-146b-5p and MMP16 was explored by luciferase activity and RNA immunoprecipitation assays. Results: Sev treatment inhibited migration and invasion of glioma cells. The expression of miR-146b-5p was enhanced and MMP16 protein was decreased in glioma cells after exposure of Sev. Knockdown of miR-146b-5p or overexpression of MMP16 reversed Sev-induced inhibition of migration and invasion of glioma cells. Moreover, MMP16 was indicated as a target of miR-146b-5p and its silencing attenuated the regulatory role of miR-146b-5p abrogationin Sev-treated glioma cells. Conclusion: Sev impeded cell migration and invasion through regulating miR-146b-5p and MMP16 in glioma, indicating a novel theories foundation for the application of anesthetics like Sev in glioma.

Altered expression of MiR-186-5p and its target genes after spinal cord ischemia-reperfusion injury in rats

Spinal cord ischemia-reperfusion (I/R) injury remains an unresolved problem, and the mechanism is not fully elaborated. In a rat model of spinal cord I/R injury, we performed microarray analysis to examine the altered expression of microRNAs (miRs) at 24 h after the modelling. miR-186-5p was chosen for further study. An miR mimic or anti-miR oligonucleotide was intrathecally infused before the surgical procedure. The participation of miR-186-5p and its potential target genes based on bioinformatics analysis were analysed next. Pre-treatment with the miR-186-5p mimic improved neurological function and histological assessment scores; reduced Evans Blue extravasation; attenuated spinal cord oedema; and decreased interleukin 15 (IL-15), IL-6, IL-1β, and tumour necrosis factor-α (TNF-α) expression at 24 h after the modelling. KEGG analysis showed that the group of potential target genes of miR-186-5p was notably enriched in several signalling cascades, such as the Wnt, Hippo, and PI3K-AKT pathways. Gene Ontology (GO) analysis revealed that the group of potential target genes of miR-186-5p was significantly enriched in several biological processes, such as 'Wnt signalling pathway', 'regulation of inflammatory response', and 'Toll-like receptor signalling pathway'. We further found that Wnt5a, TLR3, and chemokine (C-X-C motif) ligand 13 (CXCL13) were upregulated after the modelling and the miR-186-5p mimic reduced the induction of the aforementioned target genes. These data provide evidence that upregulation of miR-186-5p improves neurological outcomes induced by spinal cord I/R injury and may inhibit neuroinflammation through Wnt5a-, TLR3-, or CXCL13-mediated signal pathway in spinal cord I/R injury.

Effect of sevoflurane pretreatment in relieving liver ischemia/reperfusion-induced pulmonary and hepatic injury

Purpose

To investigate the effect of sevoflurane preconditioning on ischemia/reperfusion (I/R)-induced pulmonary/hepatic injury

Methods

Fifty-one Wistar rats were randomly grouped into sham, I/R, and sevoflurane groups. After reperfusion, the structural change of the lung was measured by Smith score, the wet and dry weights (W/D) were determined, malondialdehyde (MDA) myeloperoxidase (MPO) content was determined colorimetrically and by fluorescence, respectively, and matrix metalloprotein-9 (MMP-9) mRNA was quantified by RT-PCR. Biopsy and morphological analyses were performed on liver tissue, activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were determined, and tumor necrosis factor-alpha (TNF-α) level was determined.

Results

The sham group showed no changes in tissue structure. Structural lesions in the sevoflurane and I/R groups were mild and severe, respectively. Smith score, W/D, MDA, MPO, and MMP mRNA showed the same trend, and were increased in the I/R group and recovered in the sevoflurane group, compared with the sham group (both P<0.05). AST and ALT were significantly increased compared to the sham group (AST: 655±52.06 vs . 29±9.30 U/L; ALT: 693±75.56 vs . 37±6.71 U/L; P<0.05). In the sevoflurane group, AST and ALT levels were significantly decreased (464±47.71 and 516±78.84 U/L; P<0.001). TNF-α presented similar results.

Conclusion

The protection of lung and liver by sevoflurane may be mediated by inhibited leukocyte recruitment and MMP-9 secretion.

The roles of chemokine (C-X-C motif) ligand 13 in spinal cord ischemia-reperfusion injury in rats

Spinal cord ischemia-reperfusion injury (SCII) remains an unresolved complication and its underlying mechanism has not been fully elucidated. In this study, we studied the role of chemokine (C-X-C motif) ligand 13 (CXCL13) in a rat model of SCII. We examined the time course and cellular distribution of CXCL13 protein in rats after SCII. The effects of siRNA targeting CXCL13 or C-X-C chemokine receptor type 5 (CXCR5) in SCII were also investigated. Neurological function, histological assessment, and disruption of the blood-spinal cord barrier (BSCB) were evaluated. The expression levels of CXCL13, CXCR5, phosphorylated extracellular signal-regulated kinase (p-ERK), caspase-3, interleukin 6 (IL-6), TNF-α, and IL-1β were determined. We found that SCII resulted in impaired hind limb function and increased the expression of CXCL13. In addition, CXCL13 expression demonstrated the most pronounced effect at 24 h after SCII. We reveal that CXCL13 protein was co-expressed with the mature neuron marker NeuN and the microglial marker IBA-1 in spinal cord tissues of model rats. SCII also increased the expression of CXCR5, p-ERK, caspase-3, IL-6, TNF-α, and IL-1β at 24 h after SCII. Pre-treatment with CXCL13 siRNA protected the rats against SCII and decreased the expression of signalling pathway proteins and proinflammatory cytokines mentioned above. CXCR5 siRNA also showed similar protective effects. These findings indicate that CXCL13 is involved in SCII. The CXCL13/CXCR5 axis promotes the development of SCII, possibly via ERK-mediated pathways. Targeting the mechanism of CXCL13 involved in the development of SCII might be a potential approach for the treatment of this condition.

Tanshinone IIA inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cells via p53-cyclin B1/CDC2

Tanshinone IIA exhibits natural antioxidative and antineoplastic activity. However, to the best of our knowledge, the effects of tanshinone IIA on human nasopharyngeal carcinoma cells remains unknown. The present study aimed to investigate whether tanshinone IIA inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cells via p53-cyclin B1/cell division cycle gene 2 (CDC2). Cell proliferation, cytotoxicity and apoptosis of 13-9B cells were evaluated by an MTT assay, lactate dehydrogenase assay and flow cytometry, respectively. ELISA and western blot analysis were used to analyze caspase-3 activity and poly (ADP-ribose) polymerase (PARP), p53, cyclin B1 and CDC2 protein expression in 13-9B cells. Treatment of 13-9B cells with tanshinone IIA significantly suppressed cell proliferation and significantly induced cytotoxicity and apoptosis of 13-9B cells. Furthermore, tanshinone IIA significantly increased caspase-3 activity, and significantly increased the protein expression levels of PARP, p53, cyclin B1 and CDC2 in 13-9B cells. In summary, the current results indicate that tanshinone IIA inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cells via PARP, p53, cyclin B1/CDC2 and caspase-3-mediated signaling.

The Pathway of Let-7a-1/2-3p and HMGB1 Mediated Dexmedetomidine Inhibiting Microglia Activation in Spinal Cord Ischemia-Reperfusion Injury Mice

Microglial cell activation after spinal cord ischemia-reperfusion injury (SCIRI) commonly causes the secondary nerve motion function injury. This study aims to study the mechanism by which the drug dexmedetomidine (DEX) inhibits microglial cell activation and improves motion function of SCIRI mice. Mice SCIRI model was established, and microglia from spinal cord were isolated and cultured for subsequent molecule analysis of let-7a-1-3p, let-7a-2-3p, HMGB1, TNF-α, and IL-6. DEX was given by intraperitoneal injection. Mice motion function was evaluated by Basso mouse score. In vitro microglial cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) to imitate ischemia-reperfusion injury stimulation. DEX injection improves the mouse motion function in SCIRI model and upregulates let-7a-1/2-3p expression in the isolated activated microglia from SCIRI mice. In OGD/R-stimulated microglia, DEX treatment also caused the inactivation of cells, the upregulation of let-7a-1/2-3p expression, and the downregulation of HMGB1 expression. While the co-silencing of let-7a-1/2-3p in microglia in addition to DEX treatment restored the activation of microglia. HMGB1 is a targeted gene for let-7a-1/2-3p and negatively regulated by them. HMGB1 knockdown abrogates the pro-activation impact on microglial cell by let-7a-1/2-3p silencing. DEX inhibits the activation of microglial cell in the spinal cord of SCIRI mice, mediated by the let-7a-1/2-3p/HMGB1 pathway.

Knockdown of the AIM2 molecule attenuates ischemia-reperfusion-induced spinal neuronal pyroptosis by inhibiting AIM2 inflammasome activation and subsequent release of cleaved caspase-1 and IL-1β

Ischemia-reperfusion (IR) injury induces activation of several inflammasomes that widely affect neuroinflammation and, subsequently, neuronal viability. The absent in melanoma 2 (AIM2) inflammasome is highly expressed in neurons after traumatic injury. This study was performed to investigate whether the AIM2 molecule acts as an initiator to trigger AIM2 inflammasome activation and regulate neuronal pyroptosis in a mouse IR model. The early motor dysfunction that occurred within the first 8 h post-IR injury was closely associated with a massive increase in dsDNA in serum and cerebrospinal fluid (CSF) at the same observed timepoints. However, the subsequent persistent dysfunction was consistent with the continuously increasing protein levels of apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), cleaved caspase-1 and IL-1β with time. Upregulated AIM2 immunoreactivity was primarily visualized in neurons. The si-AIM2 treatment in vivo preserved part of motor function, accompanied by decreased protein levels of AIM2, ASC, cleaved caspase-1 and IL-1β. In vitro, the direct interactions between the AIM2 molecule and caspase-1 were demonstrated by immunofluorescence staining and coimmunoprecipitation. In this context, both si-AIM2 and Ac-YVAD-CMK treatments effectively maintained neuronal viability, as demonstrated by the decreased percentage of cells with pyroptosis and release of lactate dehydrogenase (LDH), accompanied by weak immunoreactivity and a decreased number of AIM2-caspase-1 positive neurons. By contrast, poly(dA-dT) treatment exacerbated neuronal pyroptosis by reversing the above-mentioned effects. However, no significant differences were observed after si-Con treatment. These results suggest AIM2 molecule played an important role in initiating AIM2 inflammasome activation through IR-induced release of ectopic dsDNA.

MicroRNA-125b mimic inhibits ischemia reperfusion-induced neuroinflammation and aberrant p53 apoptotic signalling activation through targeting TP53INP1

BACKGROUND

Ischemia reperfusion (IR) injury affects neuronal function through multiple pathogeneses that induce neuroinflammation and cellular apoptosis. The important roles of microRNAs (miRs) in the regulation of spinal cord IR have been recently reported. Among these roles, we investigated whether miR-125b and its downstream targets regulated the p53 signalling network and participated in both inflammation and apoptosis.

METHODS

An IR model was established via 12-min occlusion of the aortic arch. The direct interaction between miR-125b and TP53INP1 was demonstrated by Western blotting and luciferase assays. The cellular distributions of TP53INP1 were visualised by double immunofluorescence labelling. The effects of miR-125b on the expression of TP53INP1, p53 and release of proinflammatory cytokines were evaluated by synthetic miRs. Additionally, the detection of hind-limb motor function in vivo and motor neuronal apoptosis in vitro were evaluated to explore the potential mechanisms.

RESULTS

IR-induced alterations in hind-limb motor function were closely related to the temporal changes in miR-125b and TP53INP1 expression. The miR-125b/TP53INP1 gene pair was confirmed by luciferase assay. Compared with Sham controls, IR treatment resulted in increased TP53INP1 immunoreactivity that was primarily distributed in neurons. Treatment with miR-125b mimic markedly decreased the protein levels of TP53INP1, p53 and cytokines interleukin (IL)-1β and tumour necrosis factor (TNF)-α, whereas miR-125b control or inhibitor did not have the above-mentioned effects. Moreover, miR-125b mimic improved motor function in vivo and attenuated neuronal apoptosis in vitro, as demonstrated by the increased average Tarlov scores in lower limbs and lower percentages of neurons in the A4 and A2 quadrants of flow cytometry. Fluorescent staining and quantification further indicated that miR-125b mimic decreased the immunoreactivities of p53 and cleaved caspase 3 in neurons and simultaneously reduced the number of double-labelled cells with TP53INP1.

CONCLUSIONS

miR-125b mimic partially protected neurons against neuroinflammation and aberrant p53 network activation-induced apoptosis during IR injury through downregulation of TP53INP1.

Inhibiting aberrant p53-PUMA feedback loop activation attenuates ischaemia reperfusion-induced neuroapoptosis and neuroinflammation in rats by downregulating caspase 3 and the NF-κB cytokine pathway

Background

Ischaemia reperfusion (IR) induces multiple pathophysiological changes. In addition to its classical role in regulating tumourigenesis, the feedback loop formed by p53 and its driven target p53-upregulated modulator of apoptosis (PUMA) was recently demonstrated to be the common node tightly controlling various cellular responses during myocardial IR. However, the roles of the p53-PUMA feedback loop in the spinal cord remain unclear. This study aimed to elucidate the roles of p53-PUMA feedback interactions in the spinal cord after IR, specifically investigating their regulation of caspase 3-mediated apoptosis and nuclear factor (NF)-κB-mediated cytokine release.

Methods

SD rats subjected to 12 min of aortic arch occlusion served as IR models. Neurological assessment as well as p53 and PUMA mRNA and protein expression analyses were performed at 12-h intervals during a 48-h reperfusion period. The cellular distributions of p53 and PUMA were determined via double immunofluorescence staining. The effects of the p53-PUMA feedback loop on modulating hind-limb function; the number of TUNEL-positive cells; and protein levels of caspase 3, NF-κB and cytokines interleukin (IL)-1β and tumour necrosis factor (TNF)-α, were evaluated by intrathecal treatment with PUMA-specific or scramble siRNA and pifithrin (PFT)-α. Blood-spinal cord barrier (BSCB) breakdown was examined by Evans blue (EB) extravasation and water content analyses.

Results

IR induced significant behavioural deficits as demonstrated by deceased Tarlov scores, which displayed trends opposite those of PUMA and p53 protein and mRNA expression. Upregulated PUMA and p53 fluorescent labels were widely distributed in neurons, astrocytes and microglia. Injecting si-PUMA and PFT-α exerted significant anti-apoptosis effects as shown by the reduced number of TUNEL-positive cells, nuclear abnormalities and cleaved caspase 3 levels at 48 h post-IR. Additionally, p53 colocalized with NF-κB within the cell. Similarly, injecting si-PUMA and PFT-α exerted anti-inflammatory effects as shown by the decreased NF-κB translocation and release of IL-1β and TNF-α. Additionally, injecting si-PUMA and PFT-α preserved the BSCB integrity as determined by decreased EB extravasation and spinal water content. However, injecting si-Con did not induce any of the abovementioned effects.

Conclusions

Inhibition of aberrant p53-PUMA feedback loop activation by intrathecal treatment with si-PUMA and PFT-α prevented IR-induced neuroapoptosis, inflammatory responses and BSCB breakdown by inactivating caspase 3-mediated apoptosis and NF-κB-mediated cytokine release.

Investigating the efficacy of a new intravenous (IV) nanoemulsified sevoflurane/arginine formulation for maintenance of general anesthesia for embolization of cerebral aneurysm

The aim of this research investigation was to profound analysis the mitigating impact of sevoflurane/arginine post-molding on cerebral ischemia-reperfusion damage in rats. The authors fabricated emulsions fusing sevoflurane, perfluorooctyl bromide as a settling specialist, and mixes of arginine polymer. Cell suitability and gene expression of tubulin and NeuN were assessed. The stability, morphology and functional group were evaluated utilizing dynamic light scattering (DLS), Transmission Electron Microscope (TEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FTIR). Cerebral aneurysms were prompted through hypertension and a solitary stereotactic infusion of elastase into the basal storage in rat. The capacity of the emulsions to decreased cerebral aneurysm was tried in vivo by regulating them IV delivery of Se/Arg samples to rats. Se/Arg pre-conditioning expanded cell feasibility in neuroblast (SK-N-DZ) cells. Se/Arg pre-conditioning diminished infarct volume and enhanced neurological result in rats subjected to cerebral hypoxia-ischemia. Se/Arg preconditioning expanded levels of tubulin and NeuN. The prepared sevoflurane/arginine material pre-conditioning-incited neuroprotective impacts in vitro as well as in vivo analyses. Sevoflurane/arginine post-molding decreased cerebral tissue misfortune detected 7 days after cerebrum hypoxia-ischemia. This impact was prompted by clinically significant focuses and canceled by Sevoflurane/arginine. These outcomes recommend that Sevoflurane/arginine post-conditioning ensures neonatal cerebrum against cerebrum hypoxia-ischemia.

Postconditioning with sevoflurane ameliorates spatial learning and memory deficit via attenuating endoplasmic reticulum stress induced neuron apoptosis in a rat model of hemorrhage shock and resuscitation

Hemorrhage shock could initiate endoplasmic reticulum stress (ERS) and then induce neuronal apoptosis. The aim of this study was to investigate whether sevoflurane postconditioning could attenuate brain injury via suppressing apoptosis induced by ERS. Seventy male rats were randomized into five groups: sham, shock, low concentration (sevo1, 1.2%), middle concentration (sevo2, 2.4%) and high concentration (sevo3, 3.6%) of sevoflurane postconditioning. Hemorrhage shock was induced by removing 40% of the total blood volume during an interval of 30 min. 1 h after the completion of bleeding, the animals were reinfused with shed blood during the ensuing 30 min. The spatial learning and memory ability of rats were measured by Morris water maze (MWM) test three days after the operation. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positive cells in the hippocampus CA1 region were assessed after the MWM test. The expression of C/EBP-homologousprotein (CHOP) and glucose-regulated protein 78 (GRP78) in the hippocampus were measured at 24 h after reperfusion. We found that sevoflurane postconditioning with the concentrations of 2.4% and 3.6% significantly ameliorated the spatial learning and memory ability, decreased the TUNEL-positive cells, and reduced the GRP78 and CHOP expression compared with the shock group. These results suggested that sevoflurane postconditioning with the concentrations of 2.4% and 3.6% could ameliorate spatial learning and memory deficit after hemorrhage shock and resuscitation injury via suppressing apoptosis induced by ERS.

Effects of sevoflurane preconditioning on microglia/macrophage dynamics and phagocytosis profile against cerebral ischemia in rats

AIM

The effects of sevoflurane on microglia/macrophages, promoting or suppressing their activation, remains controversy. We aimed to determine whether sevoflurane preconditioning can protect brain via changing microglia/macrophage dynamics and phagocytosis profile after ischemia.

METHODS

The impact of sevoflurane preconditioning was evaluated on microglia/macrophage migration, phagocytosis and proliferation altogether from day 1 to day 7 after transient middle cerebral arterial occlusion (tMCAO) in rats.

RESULTS

Sevoflurane preconditioning was identified to accelerate microglia/macrophage migrating to and invasion in the ischemic core from day 1 to day 5 after damage. Significant accumulation of amoeboid and phagocytic microglia/macrophages was observed in sevoflurane group from day 3 to day 5 after ischemia injury. In addition, sevoflurane pretreatment also promoted the proliferation of microglia/macrophage (Iba1+ /Ki67+ ) dramatically in ischemic core on day 3 postinsult.

CONCLUSIONS

Our current study has identified the impact of sevoflurane preconditioning on microglia/macrophage dynamics, including its migration, phagocytosis, and proliferation at early stage after brain ischemia and reperfusion. Sevoflurane might enhance microglia/macrophage activation and promote brain repair. These results could help to approach more relevant microglia/macrophage cell-based strategy for human stroke therapy.