Analysis of long non-coding RNA expression profiles following focal cerebral ischemia in mice

Docosahexaenoic acid protects against ischemic stroke in diabetic mice by inhibiting inflammatory responses and apoptosis

This study was to explore whether docosahexaenoic acid (DHA) protects against ischemic stroke in diabetic mice and its mechanisms. DHA was administered to mice and its effects on stroke outcomes in type 1 diabetes mellitus were assessed 24 h and 3 days post-reperfusion using RNA sequencing, flow cytometry, multiplex immunoassays, and western-blotting analysis. In diabetic mice, DHA administration post-ischemic stroke significantly reduced cerebral infarct size, brain edema, and neurological impairments. Flow cytometric analysis demonstrated a notable decrease in the percentage of neutrophils in the ischemic brain, suggesting a mitigated inflammatory response. Western blotting assay revealed that pro-apoptotic protein Bax was reduced whereas anti-apoptotic protein Bcl-2 was increased, indicating the attenuation of apoptosis. Additionally, RNA sequencing of brain tissue highlighted significant transcriptomic changes, with downregulation of genes for several inflammatory pathways such as NF-kappa B signaling and upregulation of genes for neuroprotective pathways such as neuroactive ligand-receptor interaction. Similar transcriptomic changes in peripheral blood mononuclear cells indicated that DHA treatment resulted the systemic anti-inflammatory and neuroprotective response. DHA treatment mitigated cerebral ischemic injuries by dampening inflammatory responses and apoptosis in diabetic mice after ischemic stroke, highlighting its therapeutic potential for clinical management of stroke in diabetic patients.

Comprehensive immune modulation mechanisms of Angong Niuhuang Wan in ischemic stroke: Insights from mass cytometry analysis

BACKGROUND

Angong Niuhuang Wan (AGNHW, ), is a classical medicinal formula in Traditional Chinese Medicine (TCM) that has been appreciated for its neuroprotective properties in ischemic cerebral injuries, yet its intricate mechanisms remain only partially elucidated.

AIMS

This study leverages advanced Mass cytometry (CyTOF) to analyze AGNHW's multifaceted immunomodulation effects in-depth, emphasizing previously underexplored areas.

RESULTS

AGNHW mitigated monocyte-derived macrophages (MoDM) infiltration in the brain, distinguishing its effects on those from microglia. While the vehicle group exhibited elevated inflammatory markers like CD4, CD8a, and CD44 in ischemic brains, the AGNHW-treated group attenuated their expressions, indicating AGNHW's potential to temper the post-ischemic inflammatory response. Systemically, AGNHW modulated fundamental immune cell dynamics, notably augmenting CD8+ T cells, B cells, monocytes, and neutrophil counts in the peripheral blood under post-stroke conditions. Intracellularly, AGNHW exhibited its targeted modulation of the signaling pathways, revealing a remarked inhibition of key markers like IκBα, indicating potential suppression of inflammatory responses in ischemic brain injuries.

CONCLUSION

This study offers a comprehensive portrait of AGNHW's immunomodulation effects on ischemic stroke, illuminating its dual sites of action-both cerebral and systemic-and its nuanced modulation of cellular and molecular dynamics.

Prediction of lncRNA and disease associations based on residual graph convolutional networks with attention mechanism

LncRNAs are non-coding RNAs with a length of more than 200 nucleotides. More and more evidence shows that lncRNAs are inextricably linked with diseases. To make up for the shortcomings of traditional methods, researchers began to collect relevant biological data in the database and used bioinformatics prediction tools to predict the associations between lncRNAs and diseases, which greatly improved the efficiency of the study. To improve the prediction accuracy of current methods, we propose a new lncRNA-disease associations prediction method with attention mechanism, called ResGCN-A. Firstly, we integrated lncRNA functional similarity, lncRNA Gaussian interaction profile kernel similarity, disease semantic similarity, and disease Gaussian interaction profile kernel similarity to obtain lncRNA comprehensive similarity and disease comprehensive similarity. Secondly, the residual graph convolutional network was used to extract the local features of lncRNAs and diseases. Thirdly, the new attention mechanism was used to assign the weight of the above features to further obtain the potential features of lncRNAs and diseases. Finally, the training set required by the Extra-Trees classifier was obtained by concatenating potential features, and the potential associations between lncRNAs and diseases were obtained by the trained Extra-Trees classifier. ResGCN-A combines the residual graph convolutional network with the attention mechanism to realize the local and global features fusion of lncRNA and diseases, which is beneficial to obtain more accurate features and improve the prediction accuracy. In the experiment, ResGCN-A was compared with five other methods through 5-fold cross-validation. The results show that the AUC value and AUPR value obtained by ResGCN-A are 0.9916 and 0.9951, which are superior to the other five methods. In addition, case studies and robustness evaluation have shown that ResGCN-A is an effective method for predicting lncRNA-disease associations. The source code for ResGCN-A will be available at https://github.com/Wangxiuxiun/ResGCN-A .

The Novel lncRNA ENST00000530525 Affects ANO1, Contributing to Blood-Brain Barrier Injury in Cultured hCMEC/D3 Cells Under OGD/R Conditions

Ischemic stroke (IS) is a major neurological disease with high fatality and residual disability burdens. Long noncoding RNAs (lncRNAs) have been found to play an important role in IS. However, the roles and significance of most lncRNAs in IS are still unknown. This study was performed to identify differentially expressed (DE) lncRNAs using a lncRNA microarray in whole blood samples of patients suffering from acute cerebral ischemia. Bioinformatics analyses, including GO, KEGG pathway enrichment analysis, and proximity to putative stroke risk location analysis were performed. The novel lncRNA, ENST00000530525, significantly decreased after IS. Furthermore, we evaluated lncRNA ENST00000530525 expression in cultured hCMEC/D3 cells under oxygen-glucose deprivation/reoxygenation (OGD/R) conditions using fluorescent in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (RT-qPCR) analysis. To investigate the function of lncRNA ENST00000530525, its over-expression (OE) and negative control (NC) plasmids were transfected into hCMEC/D3 cells, and cell viability was detected by a cell counting kit-8 (CCK-8) assay after OGD/R. LncRNA ENST00000530525 and ANO1 expression were investigated using RT-qPCR and immunofluorescence. For blood-brain barrier (BBB) permeability, FITC-dextran transendothelial permeability assay and tight junction (TJ) protein immunofluorescence assays were performed. There were 3352 DE lncRNAs in the blood samples of acute IS patients. The validation results were consistent with the gene chip data. The GO and KEGG results showed that these lncRNAs were mainly related to oxygen and glucose metabolism, leukocyte transendothelial migration, mitophagy and cellular senescence. Among these, lncRNA ENST00000530525 was the most highly downregulated lncRNA and it was mapped within the IS-associated gene anoctamin-1 (ANO1). We further found that lncRNA ENST00000530525 was downregulated in hCMEC/D3 cells under 4 h OGD and 20 h reoxygenation (OGD4/R20) conditions. Upregulating lncRNA ENST00000530525 by plasmid transfection decreased cell viability while increasing ANO1 expression and it contributed to BBB injury in hCMEC/D3 cells after OGD4/R20. The lncRNA ENST00000530525 might play deleterious roles in post-stroke pathogenesis. These results show that some DE lncRNAs in humans participate through characteristic roles in post-stroke pathogenesis; thus, the roles and significance of some novel lncRNAs in IS warrant further study.

LncRNA PEG11as silencing sponges miR-874-3p to alleviate cerebral ischemia stroke via regulating autophagy in vivo and in vitro

Long non-coding RNAs (lncRNAs) are reportedly involved in the regulation of physiological and pathophysiological processes. However, the potential role of lncRNAs in stroke remains largely undefined. Here, RNA-Seq analysis of lncRNAs found that the lncRNA PEG11as (PEG11as) levels were significantly increased in ischemic brain tissue in a transient middle cerebral artery occlusion/reperfusion (tMCAO/R) mouse model of stroke. To explore the role of PEG11as in stroke, the lentivirus containing PEG11as silencing construct(siRNA-PEG11as) was microinjected intracerebroventricularly into male or transfected to N2a cells and then exposed to tMCAO/R or oxygen-glucose deprivation/reoxygenation (OGD/R). Knockdown of PEG11as expression significantly reduced infarct volume, alleviated neuronal deficits and inhibited neuronal apoptosis in tMCAO/R mice. Mechanistically, as an endogenous microRNA-874-3p (miR-874-3p) sponge, PEG11as silencing inhibited miR-874-3p activity, resulting in downregulation of ATG16L1 expression and subsequent inhibition of neuronal apoptosis by regulating autophagy. Overall, the results of this current study indicate that PEG11as is involved in the pathophysiology of cerebral ischemia, thus providing translational evidence that PEG11as can be envisioned as a novel biomarker or/and therapeutic target for stroke.

LncRNA SERPINB9P1 expression and polymorphisms are associated with ischemic stroke in a Chinese Han population

Long noncoding RNAs (lncRNAs) were reported to play important roles in the pathogenesis of ischemic stroke (IS). Our study aimed to investigate the role of lncRNA SERPINB9P1 expression in ischemic stroke and the association between SERPINB9P1 polymorphisms and IS risk, as well as examine the correlation of SERPINB9P1 expression and variants with clinical parameters of IS. The SERPINB9P1 levels in human participants and oxygen-glucose deprivation (OGD)-treated human A172 cells were measured by qRT-PCR. The SERPINB9P1 polymorphisms (rs375556 and rs318429) were genotyped by the MassARRAY platform. We found that the SERPINB9P1 expression was significantly downregulated in patients with IS compared with that in healthy controls. On the 14th day in the hospital, the SERPINB9P1 level in patients with moderate and severe stroke was significantly downregulated compared with the normal group. After stratification by gender, the rs375556 polymorphism was significantly associated with susceptibility to female IS in the recessive model, and the significant association remained after adjusting for age. After adjusting for gender and age, rs318429 was significantly associated with FPG and D-D levels, and rs375556 was significantly associated with INR and PTA levels in IS cases. Besides, the lncRNA SERPINB9P1 expressed downregulated in OGD/reoxygenation-treated human A172 cells. In conclusion, the lncRNA SERPINB9P1 may protect against cerebral ischemia-reperfusion injury and neurological impairment after IS. The SERPINB9P1 rs375556 polymorphism was associated with susceptibility to female IS, and SERPINB9P1 polymorphisms may influence the metabolism of blood glucose and regulation of coagulation function in patients with IS.

lncRNA HOTAIR mediates OGD/R-induced cell injury and angiogenesis in a EZH2-dependent manner

Long non-coding RNAs (lncRNA) serve an important role in neonatal hypoxic-ischemic encephalopathy (HIE) have been reported to regulate the activity of HIE-associated proteins. The present study aimed to elucidate the role of Hox transcript antisense intergenic RNA (HOTAIR) in oxygen-glucose deprivation/reperfusion (OGD/R)-induced injury in human brain microvascular endothelial cells (hBMVECs). The levels of HOTAIR were evaluated in the serum of neonatal patients with HIE, and the effects of HOTAIR were evaluated using in vitro assays, such as reverse transcription-quantitative PCR to detect lncRNA and mRNA levels and western blot analysis to determine protein levels. Moreover, RNA immunoprecipitation assays were used to evaluate the association between HOTAIR and enhancer of zeste homolog 2 (EZH2), Cell Counting Kit-8 was used to detect cell viability, an endothelial monolayer cell permeability assay was used to analyze cell viability, TUNEL staining was used to detect the levels of apoptosis, a Transwell assay was used to evaluate cell invasion and a tube formation assay was used to analyze tube formation ability. In addition, the effects of HOTAIR and EZH2 on cell apoptosis and the invasive and tube formation abilities of hBMVECs were investigated using TUNEL, Transwell and tube formation assays, respectively. The results showed that the expression levels of HOTAIR were markedly increased both in neonatal HIE patients and in the OGD/R injury in vitro model. HOTAIR knockdown reduced hBMVEC viability, enhanced cell permeability and apoptosis, in addition to decreasing the expression levels of tight junction-related proteins, such as zonula occludens-1, occluden, Claudin5 and vascular endothelial-cadherin. However, EZH2 overexpression reversed the effects of HOTAIR silencing on hBMVECs. Additionally, HOTAIR knockdown enhanced the migratory and tube formation abilities of OGD/R-induced hBMVECs, which were also reversed by EZH2 overexpression. Overall, the present study revealed an association between the HOTAIR/EZH2 axis and brain microvascular endothelial cell injury and angiogenesis, which provides a novel insight into the molecular mechanism underlying stroke or the development of new pharmacotherapies.

Identifying lncRNA- and Transcription Factor-Associated Regulatory Networks in the Cortex of Rats With Deep Hypothermic Circulatory Arrest

Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are involved in the mechanism underlying cerebral dysfunction after deep hypothermic circulatory arrest (DHCA), although the exact details have not been elucidated. To explore the expression profiles of lncRNAs and miRNAs in DHCA cerebral injury, we determined the lncRNA, miRNA and mRNA expression profiles in the cerebral cortex of DHCA and sham rats. First, a rat model of DHCA was established, and high-throughput sequencing was performed to analyze the differentially expressed RNAs (DERNAs). Then, the principal functions of the significantly deregulated genes were identified using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Expression networks (lncRNAs-miRNAs-mRNAs and transcription factors (TFs)-miRNAs-mRNAs) were also established. Finally, the expression of DERNAs was confirmed by quantitative real-time PCR (RT-qPCR). We identified 89 lncRNAs, 45 miRNAs and 59 mRNAs between the DHCA and sham groups and constructed a comprehensive competitive endogenous RNAs (ceRNAs) network. A TF-miRNA-mRNA regulatory network was also established. Finally, we predicted that Lcorl-miR-200a-3p-Ttr, BRD4-Ccl2 and Ep300-miR-200b-3p-Tmem72 may participate in the pathogenesis of DHCA cerebral injury.

Neuroprotective effects of long noncoding RNAs involved in ischemic postconditioning after ischemic stroke

During acute reperfusion, the expression profiles of long noncoding RNAs in adult rats with focal cerebral ischemia undergo broad changes. However, whether long noncoding RNAs are involved in neuroprotective effects following focal ischemic stroke in rats remains unclear. In this study, RNA isolation and library preparation was performed for long noncoding RNA sequencing, followed by determining the coding potential of identified long noncoding RNAs and target gene prediction. Differential expression analysis, long noncoding RNA functional enrichment analysis, and co-expression network analysis were performed comparing ischemic rats with and without ischemic postconditioning rats. Rats were subjected to ischemic postconditioning via the brief and repeated occlusion of the middle cerebral artery or femoral artery. Quantitative real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of differentially expressed long noncoding RNAs after ischemic postconditioning in a rat model of ischemic stroke. The results showed that ischemic postconditioning greatly affected the expression profile of long noncoding RNAs and mRNAs in the brains of rats that underwent ischemic stroke. The predicted target genes of some of the identified long noncoding RNAs (cis targets) were related to the cellular response to ischemia and stress, cytokine signal transduction, inflammation, and apoptosis signal transduction pathways. In addition, 15 significantly differentially expressed long noncoding RNAs were identified in the brains of rats subjected to ischemic postconditioning. Nine candidate long noncoding RNAs that may be related to ischemic postconditioning were identified by a long noncoding RNA expression profile and long noncoding RNA-mRNA co-expression network analysis. Expression levels were verified by quantitative real-time reverse transcription-polymerase chain reaction. These results suggested that the identified long noncoding RNAs may be involved in the neuroprotective effects associated with ischemic postconditioning following ischemic stroke. The experimental animal procedures were approved by the Animal Experiment Ethics Committee of Kunming Medical University (approval No. KMMU2018018) in January 2018.

Hypoxia related long non-coding RNAs in ischemic stroke

With high rates of mortality and disability, stroke has caused huge social burden, and 85% of which is ischemic stroke. In recent years, it is a progressive discovery of long non-coding RNA (lncRNA) playing an important regulatory role throughout ischemic stroke. Hypoxia, generated from reduction or interruption of cerebral blood flow, leads to changes in lncRNA expression, which then influence disease progression. Therefore, we reviewed studies on expression of hypoxia-related lncRNAs and relevant molecular mechanism in ischemic stroke. Considering that hypoxia-inducible factor (HIF) is a crucial regulator in hypoxic progress, we mainly focus on the HIF-related lncRNA which regulates the expression of HIF or is regulated by HIF, further reveal their pathogenesis and adaption after brain ischemia and hypoxia, so as to find effective biomarker and therapeutic targets.

Expression of Long Non-coding RNA RGD1566344 in the Brain Cortex of Male Mice After Focal Cerebral Ischemia-Reperfusion and the Neuroprotective Effect of a Non-coding RNA RGD1566344 Inhibitor

Ischemic stroke (IS) remains a major cause of disability and death. The changes in long non-coding RNA (lncRNA) RGD1566344 expression in the mouse cerebral cortex, including the infarct and penumbra regions after IS, are not clear. Less is known about the impact and underlying mechanisms of RGD1566344 in IS. In this study, we found that RGD1566344 levels were elevated in the ischemic infarct and penumbra regions 12 h after middle cerebral artery occlusion/reperfusion (MCAO/R) in male mice and in PC12 cells with oxygen glucose deprivation/reperfusion (OGD/R). The inhibition of RGD1566344 by small interference RNA (siRNA) significantly alleviated apoptosis in OGD/R PC12 cells. In cell transfection, quantitative real-time PCR, and Western blot experiments, we demonstrated the possible interaction of non-POU domain-containing octamer-binding protein (NONO) with RGD1566344. The NONO level in OGD/R PC12 cells was obviously increased after inhibiting the RGD1566344 treatment; subsequently the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway was activated. This demonstrated the effect of the RGD1566344-NONO-AKT axis on neural protection after IS. These results revealed a new molecular mechanism of lncRNA RGD1566344 inhibitors through targeting NONO/AKT/mTOR signaling to protect against ischemic neuronal injury, providing strong evidence for the development of promising therapeutic strategies against IS.

Role of lncRNAs in the Development of Ischemic Stroke and Their Therapeutic Potential

Stroke is a major cause of premature mortality and disability around the world. Therefore, identification of cellular and molecular processes implicated in the pathogenesis and progression of ischemic stroke has become a priority. Long non-coding RNAs (lncRNAs) are emerging as significant players in the pathophysiology of cerebral ischemia. They are involved in different signalling pathways of cellular processes like cell apoptosis, autophagy, angiogenesis, inflammation, and cell death, impacting the progression of cerebral damage. Exploring the functions of these lncRNAs and their mechanism of action may help in the development of promising treatment strategies. In this review, the current knowledge of lncRNAs in ischemic stroke, focusing on the mechanism by which they cause cellular apoptosis, inflammation, and microglial activation, has been summarized. Very few lncRNAs have been functionally annotated. Therefore, the therapies based on lncRNAs still face many hurdles since the potential targets are likely to increase with the identification of new ones. Majority of experiments involving the identification and function of lncRNAs have been carried out in animal models, and the role of lncRNAs in human stroke presents a challenge. However, mitigating these issues through more rational experimental design might lead to the development of lncRNA-based stroke therapies to treat ischemic stroke.

LncRNA MEG3 regulates microglial polarization through KLF4 to affect cerebral ischemia-reperfusion injury

This study aimed to explore whether long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) affects the polarization of microglia in cerebral ischemia-reperfusion (I/R) injury through regulating Krüppel-like factor 4 (KLF4). A middle cerebral artery occlusion/reperfusion-induced (MCAO/R-induced) mouse model was established as an in vivo model. Oxygen and glucose confinement/reoxygenation-induced (OGD/R-induced) microglia (BV2 cells) were used as an in vitro model. RNA pull-down and RNA immunoprecipitation were used to detect the binding between MEG3 and KLF4. The MEG3 expression was signally elevated in the MCAO/R-induced mice or OGD/R-induced BV2 cells. The inhibition of MEG3 reversed the effects of OGD/R injury on the polarization and inflammation of BV2 cells. Moreover, MEG3 bound to KLF4 and inhibited its protein expression. Furthermore, the overexpression of MEG3 promoted M1 polarization and inflammation but inhibited M2 polarization by inhibiting KLF4 in BV2 cells. The transfection of small interfering RNAs against MEG3 inhibited M1 polarization and inflammation and promoted M2 polarization in vitro and in vivo. Inhibition of MEG3 can alleviate cerebral I/R injury via regulating the polarization of microglia through KLF4.NEW & NOTEWORTHY To study the role of long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) in cerebral ischemia-reperfusion (I/R) injury, we clarified the mechanism by which lncRNA MEG3 regulates the secretion of inflammatory cytokines in microglia through in vitro and in vivo experiments. We discovered that inhibition of MEG3 could alleviate cerebral I/R injury via inhibiting M1 polarization and promoting M2 polarization through Krüppel-like factor 4 (KLF4), indicating an effective theoretical basis for potential therapeutic targets of cerebral I/R injury.

LncRNAs Stand as Potent Biomarkers and Therapeutic Targets for Stroke

Stroke is a major public health problem worldwide with a high burden of neurological disability and mortality. Long noncoding RNAs (lncRNAs) have attracted much attention in the past decades because of their newly discovered roles in pathophysiological processes in many diseases. The abundance of lncRNAs in the nervous system indicates that they may be part of a complex regulatory network governing physiology and pathology of the brain. In particular, lncRNAs have been shown to play pivotal roles in the pathogenesis of stroke. In this article, we provide a review of the multifaceted functions of lncRNAs in the pathogenesis of ischemic stroke and intracerebral hemorrhage, highlighting their promising use as stroke diagnostic biomarkers and therapeutics. To this end, we discuss the potential of stem cells in aiding lncRNA applications in stroke.

Plasmacytoid Dendritic Cells Protect Against Middle Cerebral Artery Occlusion Induced Brain Injury by Priming Regulatory T Cells

Regulatory T cells (Tregs) play an anti-inflammatory effect to protect against ischemic stroke. Plasmacytoid dendritic cells (pDCs) can induce regulatory T cells tolerance in sterile-inflammation conditions. However, whether and how pDCs-mediated Tregs response play a part in the pathology of ischemic stroke remains unclear. In this study, we showed that pDCs were increased in the brain of middle cerebral artery occlusion (MCAO) mice. Depletion of pDCs with 120G8 exacerbated MCAO-induced brain injury, peripheral pro-inflammation response and decreased the systemic Tregs in mice. Furthermore, the data of mixed lymphocyte reaction (MLR) in vitro demonstrate that splenic pDCs from MCAO mice can significantly promote Tregs proliferation, accompanying with the increased expression of indoleamine 2,3-dioxygenase 1 (IDO1) on pDCs. Taken together, the findings here suggested that under the pathologic state of stroke, pDCs protect against MCAO-induced brain injury by priming Tregs, illustrating that pDCs represented as a therapeutic target for the prevention of ischemic brain injury.

Remote ischemic conditioning reduced cerebral ischemic injury by modulating inflammatory responses and ERK activity in type 2 diabetic mice

Remote ischemic preconditioning (RIPreC) and postconditioning (RIPostC) have been demonstrated to attenuate brain injury after ischemic stroke in healthy animals. This study investigated whether RIPreC and RIPostC exerted neuroprotection against cerebral ischemic injury in type 2 diabetic mice. RIPreC (24 h before ischemia) and RIPostC (immediately after reperfusion) were performed in an ischemia/reperfusion induced stroke model with type 2 diabetes. Ischemic outcomes, flow cytometry, multiplex cytokine assay, and western blotting were analyzed after 45 min of ischemia followed by 48 h of reperfusion. Our data indicated that RIPreC and RIPostC attenuated cerebral injuries and neurological deficits. RIPreC significantly reduced CD4 T cell and CD8 T cell infiltration and increased B cell infiltration into the ischemic brain. It also upregulated CD4 and CD8 T cell levels in the peripheral blood. However, RIPostC significantly decreased CD8 T cells infiltration and increased B cell infiltration into the ischemic brain. RIPreC inhibited IL-6 level in both the brain and blood, while RIPostC treatment attenuated IL-6 level upregulation in the peripheral blood. In addition, both RIPreC and RIPostC significantly increased p-ERK expression in the ipsilateral hemisphere in diabetic mice. This study indicated that RIPreC and RIPostC neuroprotection is present in type 2 diabetic mice via the modulation of brain ERK activity and inflammatory responses in both the peripheral blood and ischemic brain. However, the benefit was lower in RIPostC.

Remote ischemic preconditioning protects against ischemic stroke in streptozotocin-induced diabetic mice via anti-inflammatory response and anti-apoptosis

OBJECTIVE

It has been shown that remote ischemic preconditioning (RIPreC) attenuates ischemic injury after stroke in healthy rats or mice. The present study aims to examine whether RIPreC offers neuroprotection against ischemic stroke in streptozotocin-induced diabetic mice.

METHODS

Streptozotocin (STZ, 120 mg/kg) was intraperitoneally injected into the mice to induce type 1 diabetic model. The immune and inflammatory changes were analyzed 2 days after reperfusion by flow cytometry and multiplex cytokine assay analysis, respectively.

RESULTS

We found that RIPreC reduced infarct sizes and alleviated neurological impairment in diabetic mice. RIPreC decreased CD8 T cells infiltrated into the brain, and attenuated the decreases of CD8 T cells in the blood, CD4 T cells and CD8 T cells in the spleen. Results from multiplex cytokine assay showed that RIPreC treatment decreased IL-6, IL-1 beta and TNF alpha levels in the cortex, while it inhibited IL-6 level in the hippocampus and striatum, and TNF alpha level in the hippocampus. RIPreC treatment also downregulated IL-6 and IFN gamma level in the blood, which increased after cerebral ischemic injury. In addition, RIPreC reduced pro-apoptotic protein BAX expression in the ischemic brain.

CONCLUSIONS

Our results indicate that RIPreC attenuates cerebral injuries in streptozotocin-induced diabetic mice via anti-inflammatory response and anti-apoptosis in the ischemic brain.

Down-regulation of lncRNA GAS5 attenuates neuronal cell injury through regulating miR-9/FOXO3 axis in cerebral ischemic stroke

Cerebral ischemic stroke is a leading cause of neurological disability worldwide. Previous study reported that long noncoding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) was highly expressed in ischemic stroke. However, the mechanism underlying GAS5 in an inflammatory injury during an ischemic stroke remains poorly understood. An in vivo mouse model of middle cerebral artery occlusion (MCAO) and an in vitro cell model of oxygen-glucose deprivation (OGD) were established to induce cerebral ischemic stroke condition. The expressions of GAS5, microRNA-9 (miR-9) and forkhead box O3 (FOXO3) were measured by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot analysis, respectively. The neurological injury in vivo was investigated by neurological score and TTC staining. Cell apoptosis and inflammatory injury were analyzed by western blot, flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively. The interaction between miR-9 and GAS5 or FOXO3 was explored by luciferase activity, RNA pull-down and RNA immunoprecipitation (RIP) assays. GAS5 expression was enhanced in the cerebral ischemic stroke model. Knockdown of GAS5 attenuated the cerebral infarct, neurological injury, apoptosis and inflammatory injury in the mouse MCAO model. miR-9 was bound to GAS5 and its overexpression inhibited cell apoptosis and inflammatory response in OGD-treated bEnd.3 cells, which was attenuated by GAS5. FOXO3 was a target of miR-9 and its restoration reversed the miR-9-mediated suppression of apoptosis and inflammation. Moreover, GAS5 promoted FOXO3 expression by competitively sponging miR-9. GAS5 knockdown alleviated neuronal cell injury by regulating miR-9/FOXO3, providing a new theoretical foundation for cerebral ischemic stroke.

Cerebral ischemic stroke is a leading cause of neurological disability worldwide.

Analysis of long non-coding RNA expression profiles in neonatal rats with hypoxic-ischemic brain damage

Hypoxic-ischemic brain damage (HIBD) which is a common cause of acute mortality and neurological dysfunction in neonates still lacks effective therapeutic methods. Long non-coding RNAs (lncRNAs) were demonstrated to play a crucial role in many diseases. To give a foundation for subsequent functional studies of lncRNAs in HIBD, we investigated the profiling of lncRNAs and messenger RNAs (mRNAs) using neonatal HIBD rat model. Six neonatal rats were divided into sham-operated group (n = 3) and HIBD group (n = 3) randomly. Deep RNA sequencing was implemented to find out the meaningful lncRNAs and mRNAs. Quantitative real-time PCR was used to validate expressions of lncRNAs and mRNAs. The Gene Ontology (GO) and kyoto encyclopedia of genes a genomes (KEGG) database were used to predict functions of lncRNAs. A total of 328 differentially expressed lncRNAs (177 down-regulated vs 151 up-regulated) and 7157 differentially expressed mRNAs (2552 down-regulated vs 4605 up-regulated) were identified. The Quantitative real-time PCR results showed significant differential expressions of five lncRNAs and five mRNAs which were consistent with the RNA-Seq data. Gene ontology and KEGG analysis showed these lncRNAs and their expression-correlated mRNAs were closely related to the Janus tyrosine kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, NF-kappa B signaling pathway, Toll-like receptor signaling pathway, calcium signaling pathway, Notch signaling pathway, mitogen activated protein kinase signaling pathway, neuroactive ligand-receptor interaction pathway and more. The results of our study identified the characterization and expression profiles of lncRNAs in neonatal HIBD and may be a basis for further therapeutic research. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* and *Open Data* because it provided all relevant information to reproduce the study in the manuscript and because it made the data publicly available. The data can be accessed at https://osf.io/yf3da/. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

The Regulatory Role of Long Noncoding RNAs in Different Brain Cell Types Involved in Ischemic Stroke

Stroke results in high morbidity and high mortality worldwide, with ischemic stroke accounting for 80% to 85%. As effective treatments for ischemic stroke remain limited because of the narrow therapeutic time window, a better understanding of the pathologic mechanism and new therapeutic intervention targets are needed. Due to the development of next-generation sequencing technologies and the genome-wide analysis of eukaryotic transcriptomes, a large amount of evidence to date demonstrates that long noncoding RNAs (lncRNAs) play a vital role in gene regulation and in ischemic stroke. In recent years, many studies have been focused on the clinical significance of lncRNAs in ischemic stroke, and data shows that the pathological processes underlying ischemic stroke are driven by interactions among different brain cell types, including neurons, glial cells, and vascular cells, which actively participate in the mechanisms of tissue injury and repair. In this mini review article, we provide an overview of the characteristics and underlying regulation mechanisms of lncRNAs relevant to different brain cell types during the course of ischemic stroke. Moreover, we reveal the roles of lncRNAs as potential biomarkers and treatment targets in ischemic stroke.

Tranilast Treatment Attenuates Cerebral Ischemia-Reperfusion Injury in Rats Through the Inhibition of Inflammatory Responses Mediated by NF-κB and PPARs

Ischemia‐reperfusion injury (IRI) occurs when blood supply returns to tissue after interruption, which is associated with life‐threatening inflammatory response. Tranilast is a widely used antiallergic agent in the treatment against bronchial asthma and keloid. To study the function of tranilast, we used IRI in rat models. The brain tissues of IRI rats with or without tranilast treatment were collected. Neuronal apoptosis in the brain was detected by terminal deoxynucleotidyl transferase nick end labeling assay, and proinflammatory cytokine levels were measured by quantitative real‐time polymerase chain reaction and enzyme‐linked immunosorbent assay. The expression levels of nuclear factor‐kappa B (NF‐κB), inhibitor of κB (IκB) and peroxisome proliferator‐activated receptors (PPARs) were detected by Western blot. The results showed that tranilast treatment reduced neuronal apoptosis in the brain of IRI rats. Tranilast enhanced the short‐term memory and long‐term memory to novel object recognition paradigm. Tranilast treatment decreased the messenger RNA (mRNA) and protein levels of multiple proinflammatory cytokines, and affected NF‐κB and inhibitor of kappa B protein expressions. Tranilast promoted the expressions of PPAR‐α and PPAR‐γ. Our findings demonstrate that tranilast treatment could attenuate cerebral IRI by regulating the inflammatory cytokine production and PPAR expression. Tranilast is a potential drug for IRI treatment in the clinic.

Association between MEG3/miR-181b polymorphisms and risk of ischemic stroke

BACKGROUND

Recent evidence suggests that long non-coding RNAs (lncRNAs) are key regulators in the pathological process of ischemic stroke (IS). Maternally expressed gene 3 (MEG3) was observed to be up-regulated in IS, acting as a competing endogenous RNA for miR-181b to regulate ischemic brain injury. The purpose of this study was to evaluate the association of tagSNPs in MEG3 (i.e., rs7158663 and rs4081134) and miR-181b rs322931 with IS risk.

METHODS

Genomic DNA was extracted from blood samples of 509 patients with IS and 668 healthy controls. Genotyping of MEG3 rs7158663, rs4081134, and miR-181b rs322931 was performed by TaqMan assay. The transcriptional activity was measured using the Dual-Luciferase Reporter Assay kit.

RESULTS

Single-site analysis revealed a significantly higher risk of IS being associated with miR-181b rs322931 CT and CT/TT genotypes (CT vs. CC: adjusted OR = 1.48, 95% CI: 1.13-1.95, P = 0.005; CT/TT vs. CC: adjusted OR = 1.52, 95% CI: 1.17-1.97, P = 0.002). Combined analyses revealed that combined genotypes (rs7158663 GG + rs322931 CT/TT and rs7158663 AG/AA + rs322931 CT/TT) increased IS risk compared to genotypes of rs7158663 GG + rs322931 CC. Stratification analyses showed that patients carrying miR-181b rs322931 CT/TT genotypes had higher levels of low-density lipoprotein cholesterol (LDL_C) (P = 0.01). Moreover, results from logistic regression analysis showed that rs322931 CT/TT genotypes were risk factors besides hypertension, total cholesterol, triglyceride, and LDL_C. Further dual-luciferase reporter assay showed that the rs322931 T allele had lower levels of luciferase activity than the rs322931 C allele.

CONCLUSION

These findings indicate that miR-181b rs322931 may singly or jointly contribute to the risk of IS.

A Functional Polymorphism rs145204276 in the Promoter of Long Noncoding RNA GAS5 Is Associated with an Increased Risk of Ischemic Stroke

Long noncoding RNAs (lncRNAs) play crucial roles in the regulation of pathological process of ischemic stroke (IS) via affecting cell apoptosis, inflammation, cell death, and angiogenesis. LncRNA growth arrest-specific 5 (GAS5) was observed to be up-regulated in IS, acting as a competing endogenous RNA for miR-137 to mediate the Notch1 signaling pathway. In this study, we aimed to whether an insertion/deletion polymorphism (rs145204276) in the promoter of GAS5 was related to the risk of IS. The rs145204276 was genotyped using polymerase chain reaction (PCR)-polyacrylamide gel electrophoresis in 509 patients with IS and 668 healthy controls with frequencies matched to cases regarding age, gender, living area, and ethnicity. The GAS5 expression levels were determined using qPCR and relative luciferase activity was measured using the Dual Luciferase assay system. The presence of del/del genotype and del allele was associated with an increased risk of IS [del/del versus ins/ins: adjusted odds ratio (OR) = 2.06, 95% confidence interval (CI): 1.37-3.11; recessive model: adjusted OR = 2.07, 95% CI: 1.41-3.04; del versus ins: adjusted OR = 1.31, 95% CI: 1.08-1.57]. Results from logistic regression analysis identified risk factors for IS, including hypertension, total cholesterol, triglyceride, low-density lipoprotein cholesterol, and rs145204276 del/del genotype. Furthermore, patients carrying rs145204276 del/del genotype had significantly higher levels of GAS5 and cells transfected with rs145204276 del allele exhibited a larger increase in luciferase activity. These findings indicate that rs145204276 del allele exhibited a significant association with an increased IS susceptibility by elevating the transcriptional activity and subsequently enhancing the expression of lncRNA GAS5.

Deletion of long noncoding RNA EFNA3 aggravates hypoxia-induced injury in PC-12 cells by upregulation of miR-101a

Long noncoding RNAs (lncRNAs) have been reported to be involved in several neurological pathogenesis conditions including cerebral ischemia. In the current study, the functions of lncRNA EFNA3 on hypoxia-injured rat adrenal pheochromocytoma (PC-12) cells and the underlying molecular mechanism were studied. The expression of lncRNA EFNA3 was silenced by short hairpin RNA transfection, after which the cells were subjected with hypoxia. Cell viability, migration, invasion, and apoptosis were, respectively, determined by trypan blue staining, Transwell assay, annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double-staining, and Western blot analysis. The cross regulation between lncRNA EFNA3 and miR-101a, as well as between miR-101a and Rho associated coiled-coil containing protein kinase 2 (ROCK2) were detected by performing quantitative real-time polymerase chain reaction, RNA pull-down, RNA immunoprecipitation, luciferase activity assay, and Western blot analysis. Studies showed that lncRNA EFNA3 was highly expressed in response to hypoxia. Deletion of lncRNA EFNA3 significantly aggravated hypoxia-induced injury in PC-12 cells, as the impairment of cell viability, migration, and invasion, and the inducement of apoptosis. LncRNA EFNA3 worked as a sponging molecule for miR-101a and miR-101a suppression-protected PC-12 cells against hypoxia-induced injury even when lncRNA EFNA3 was silenced. ROCK2 was a target gene of miR-101a. ROCK2 overexpression exhibited neuroprotective activities. Besides, ROCK2 overexpression activated Wnt/β-catenin pathway whereas it deactivated JAK/STAT pathway upon hypoxia. Our study suggests that deletion of lncRNA EFNA3 aggravates hypoxia-induced injury in PC-12 cells by upregulating miR-101a, which further targets ROCK2.

Present Status and Future Challenges of New Therapeutic Targets in Preclinical Models of Stroke in Aged Animals with/without Comorbidities

The aging process, comorbidities, and age-associated diseases are closely dependent on each other. Cerebral ischemia impacts a wide range of systems in an age-dependent manner. However, the aging process has many facets which are influenced by the genetic background and epigenetic or environmental factors, which can explain why some people age differently than others. Therefore, there is an urgent need to identify age-related changes in body functions or structures that increase the risk for stroke and which are associated with a poor outcome. Multimodal imaging, electrophysiology, cell biology, proteomics, and transcriptomics, offer a useful approach to link structural and functional changes in the aging brain, with or without comorbidities, to post-stroke rehabilitation. This can help us to improve our knowledge about senescence firstly, and in this context, aids in elucidating the pathophysiology of age-related diseases that allows us to develop therapeutic strategies or prevent diseases. These processes, including potential therapeutical interventions, need to be studied first in relevant preclinical models using aged animals, with and without comorbidities. Therefore, preclinical research on ischemic stroke should consider age as the most important risk factor for cerebral ischemia. Furthermore, the identification of effective therapeutic strategies, corroborated with successful translational studies, will have a dramatic impact on the lives of millions of people with cerebrovascular diseases.