Microglial lnc-U90926 facilitates neutrophil infiltration in ischemic stroke via MDH2/CXCL2 axis

Microglial CMPK2 promotes neuroinflammation and brain injury after ischemic stroke

Neuroinflammation plays a significant role in ischemic injury, which can be promoted by oxidized mitochondrial DNA (Ox-mtDNA). Cytidine/uridine monophosphate kinase 2 (CMPK2) regulates mtDNA replication, but its role in neuroinflammation and ischemic injury remains unknown. Here, we report that CMPK2 expression is upregulated in monocytes/macrophages and microglia post-stroke in humans and mice, respectively. Microglia/macrophage CMPK2 knockdown using the Cre recombination-dependent adeno-associated virus suppresses the inflammatory responses in the brain, reduces infarcts, and improves neurological outcomes in ischemic CX3CR1Cre/ERT2 mice. Mechanistically, CMPK2 knockdown limits newly synthesized mtDNA and Ox-mtDNA formation and subsequently blocks NLRP3 inflammasome activation in microglia/macrophages. Nordihydroguaiaretic acid (NDGA), as a CMPK2 inhibitor, is discovered to reduce neuroinflammation and ischemic injury in mice and prevent the inflammatory responses in primary human monocytes from ischemic patients. Thus, these findings identify CMPK2 as a promising therapeutic target for ischemic stroke and other brain disorders associated with neuroinflammation.

Noncanonical microprotein regulation of immunity

The immune system is highly regulated but, when dysregulated, suboptimal protective or overly robust immune responses can lead to immune-mediated disorders. The genetic and molecular mechanisms of immune regulation are incompletely understood, impeding the development of more precise diagnostics and therapeutics for immune-mediated disorders. Recently, thousands of previously unrecognized noncanonical microprotein genes encoded by small open reading frames have been identified. Many of these microproteins perform critical functions, often in a cell- and context-specific manner. Several microproteins are now known to regulate immunity; however, the vast majority are uncharacterized. Therefore, illuminating what is often referred to as the "dark proteome," may present opportunities to tune immune responses more precisely. Here, we review noncanonical microprotein biology, highlight recently discovered examples regulating immunity, and discuss the potential and challenges of modulating dysregulated immune responses by targeting microproteins.

RNA therapies for CNS diseases

Neurological disorders are a diverse group of conditions that pose an increasing health burden worldwide. There is a general lack of effective therapies due to multiple reasons, of which a key obstacle is the presence of the blood-brain barrier, which limits drug delivery to the central nervous system, and generally restricts the pool of candidate drugs to small, lipophilic molecules. However, in many cases, these are unable to target key pathways in the pathogenesis of neurological disorders. As a group, RNA therapies have shown tremendous promise in treating various conditions because they offer unique opportunities for specific targeting by leveraging Watson-Crick base pairing systems, opening up possibilities to modulate pathological mechanisms that previously could not be addressed by small molecules or antibody-protein interactions. This potential paradigm shift in disease management has been enabled by recent advances in synthesizing, purifying, and delivering RNA. This review explores the use of RNA-based therapies specifically for central nervous system disorders, where we highlight the inherent limitations of RNA therapy and present strategies to augment the effectiveness of RNA therapeutics, including physical, chemical, and biological methods. We then describe translational challenges to the widespread use of RNA therapies and close with a consideration of future prospects in this field.

Progressive reduction of nuclear receptor Nr4a1 mediates age-dependent cognitive decline

INTRODUCTION

Cognitive decline progresses with age, and Nr4a1 has been shown to participate in memory functions. However, the relationship between age-related Nr4a1 reduction and cognitive decline is undefined.

METHODS

Nr4a1 expressions were evaluated by quantitative PCR and immunochemical approaches. The cognition of mice was examined by multiple behavioral tests. Patch-clamp experiments were conducted to investigate the synaptic function.

RESULTS

NR4A1 in peripheral blood mononuclear cells decreased with age in humans. In the mouse brain, age-dependent Nr4a1 reduction occurred in the hippocampal CA1. Deleting Nr4a1 in CA1 pyramidal neurons (PyrNs) led to the impairment of cognition and excitatory synaptic function. Mechanistically, Nr4a1 enhanced TrkB expression via binding to its promoter. Blocking TrkB compromised the cognitive amelioration with Nr4a1-overexpression in CA1 PyrNs.

DISCUSSION

Our results elucidate the mechanism of Nr4a1-dependent TrkB regulation in cognition and synaptic function, indicating that Nr4a1 is a target for the treatment of cognitive decline.

HIGHLIGHTS

Nr4a1 is reduced in PBMCs and CA1 PyrNs with aging. Nr4a1 ablation in CA1 PyrNs impaired cognition and excitatory synaptic function. Nr4a1 overexpression in CA1 PyrNs ameliorated cognitive impairment of aged mice. Nr4a1 bound to TrkB promoter to enhance transcription. Blocking TrkB function compromised Nr4a1-induced cognitive improvement.

Neutrophil Membrane-Camouflaged Polyprodrug Nanomedicine for Inflammation Suppression in Ischemic Stroke Therapy

Neuroinflammation has emerged as a major concern in ischemic stroke therapy because it exacebates neurological dysfunction and suppresses neurological recovery after ischemia/reperfusion. Fingolimod hydrochloride (FTY720) is an FDA-approved anti-inflammatory drug which exhibits potential neuroprotective effects in ischemic brain parenchyma. However, delivering a sufficient amount of FTY720 through the blood-brain barrier into brain lesions without inducing severe cardiovascular side effects remains challenging. Here, a neutrophil membrane-camouflaged polyprodrug nanomedicine that can migrate into ischemic brain tissues and in situ release FTY720 in response to elevated levels of reactive oxygen species. This nanomedicine delivers 15.2-fold more FTY720 into the ischemic brain and significantly reduces the risk of cardiotoxicity and infection compared with intravenously administered free drug. In addition, single-cell RNA-sequencing analysis identifies that the nanomedicine attenuates poststroke inflammation by reprogramming microglia toward anti-inflammatory phenotypes, which is realized via modulating Cebpb-regulated activation of NLRP3 inflammasomes and secretion of CXCL2 chemokine. This study offers new insights into the design and fabrication of polyprodrug nanomedicines for effective suppression of inflammation in ischemic stroke therapy.

γ-Glutamylcysteine ameliorates blood-brain barrier permeability and neutrophil extracellular traps formation after ischemic stroke by modulating Wnt/β-catenin signalling in mice

During the inflammatory response after stroke, the blood-brain barrier (BBB) is significantly disrupted, compromising its integrity. This disruption allows many peripheral neutrophils to infiltrate the injury site in the brain and release neutrophil extracellular traps (NETs), which further increase BBB permeability. In this study, we aimed to investigate the protective effects of γ-Glutamylcysteine (γ-GC), an immediate precursor of GSH, against BBB breakdown and NET formation after ischemic stroke. Our data indicated that γ-GC treatment effectively attenuated BBB damage, decreased neutrophil infiltration, and suppressed the release of NETs, ultimately leading to the amelioration of ischemic injury. Transcriptomic data and subsequent validation studies revealed that mechanistically, γ-GC exerts its effect by activating the Wnt/β-catenin pathway after ischemic stroke. This research suggests that γ-GC may hold promise as a therapeutic agent for alleviating brain injury following an ischemic stroke.

Upregulation of TRPC1 in microglia promotes neutrophil infiltration after ischemic stroke

Neutrophil infiltration has been linked to worse clinical outcomes after ischemic stroke. Microglia, a key type of immune-competent cell, engage in cross-talk with the infiltrating immune cells in the inflamed brain area, yet the molecular mechanisms involved remain largely unexplored. In this study, we investigated the mechanisms of how canonical transient receptor potential 1 (TRPC1) modulated neutrophil infiltration in male mouse cerebral ischemia and reperfusion injury (CIRI) models. Our findings revealed a notable upregulation of TRPC1 in microglia within both middle cerebral artery occlusion reperfusion (MCAO/R) and in vitro oxygen-glucose deprivation/regeneration (OGD/R) model. Conditional Trpc1 knockdown in microglia markedly reduced infarct volumes and alleviated neurological deficits. Microglia conditional Trpc1 knockdown mice displayed less neutrophil infiltration in peri-infarct area. Trpc1 knockdown microglia exhibited a reduced primed proinflammatory phenotype with less secretion of CC-Chemokines ligand (CCL) 5 and CCL2 after MCAO/R. Blocking CCL5/2 significantly mitigated neutrophil infiltration in microglia/neutrophil transwell co-culture system upon OGD/R condition. Trpc1 knockdown markedly reduced store-operated calcium entry and nuclear factor of activated T-cells c1 (NFATc1) level in OGD/R treated microglia. Overexpression of Nfatc1 reversed the CCL5/2 reducing effect of Trpc1 knockdown, which is mediated by small interfering RNA in BV2 cells upon OGD/R. Our data indicate that upregulation of TRPC1 in microglia stimulates the production of CCL5/2 through the Ca2+/NFATc1 pathway. Upregulated CCL5/2 leads to an increase in neutrophil infiltration into the brain, thereby aggravating reperfusion injury. Our results demonstrate the importance of TRPC1 in microglia-mediated neuroinflammation and suggest a potential means for reducing CIRI induced neurological injury.

SRGN amplifies microglia-mediated neuroinflammation and exacerbates ischemic brain injury

BACKGROUND

Microglia is the major contributor of post-stroke neuroinflammation cascade and the crucial cellular target for the treatment of ischemic stroke. Currently, the endogenous mechanism underlying microglial activation following ischemic stroke remains elusive. Serglycin (SRGN) is a proteoglycan expressed in immune cells. Up to now, the role of SRGN on microglial activation and ischemic stroke is largely unexplored.

METHODS

Srgn knockout (KO), Cd44-KO and wild-type (WT) mice were subjected to middle cerebral artery occlusion (MCAO) to mimic ischemic stroke. Exogenous SRGN supplementation was achieved by stereotactic injection of recombinant mouse SRGN (rSRGN). Cerebral infarction was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Neurological functions were evaluated by the modified neurological severity score (mNSS) and grip strength. Microglial activation was detected by Iba1 immunostaining, morphological analysis and cytokines' production. Neuronal death was examined by MAP2 immunostaining and FJB staining.

RESULTS

The expression of SRGN and its receptor CD44 was significantly elevated in the ischemic mouse brains, especially in microglia. In addition, lipopolysaccharide (LPS) induced SRGN upregulation in microglia in vitro. rSRGN worsened ischemic brain injury in mice and amplified post-stroke neuroinflammation, while gene knockout of Srgn exerted reverse impacts. rSRGN promoted microglial proinflammatory activation both in vivo and in vitro, whereas Srgn-deficiency alleviated microglia-mediated inflammatory response. Moreover, the genetic deletion of Cd44 partially rescued rSRGN-induced excessed neuroinflammation and ischemic brain injury in mice. Mechanistically, SRGN boosted the activation of NF-κB signal, and increased glycolysis in microglia.

CONCLUSION

SRGN acts as a novel therapeutic target in microglia-boosted proinflammatory response following ischemic stroke.

LncRNA U90926 is dispensable for the development of obesity-associated phenotypes in vivo

Obesity is a global health problem characterized by excessive fat accumulation, driven by adipogenesis and lipid accumulation. Long non-coding RNAs (lncRNAs) have recently been implicated in regulating adipogenesis and adipose tissue function. Mouse lncRNA U90926 was previously identified as a repressor of in vitro adipogenesis in 3T3-L1 preadipocytes. Consequently, we hypothesized that, in vivo, U90926 may repress adipogenesis, and hence its deletion would increase weight gain and adiposity. We tested the hypothesis by applying U90926-deficient (U9-KO) mice to a high-throughput phenotyping pipeline. Compared with WT, U9-KO mice showed no major differences across a wide range of behavioral, neurological, and other physiological parameters. In mice fed a standard diet, we have found no differences in obesity-related phenotypes, including weight gain, fat mass, and plasma concentrations of glucose, insulin, triglycerides, and free fatty acids, in U9-KO mice compared to WT. U90926 deficiency lacked a major effect on white adipose tissue morphology and gene expression profile. Furthermore, in mice fed a high-fat diet, we found increased expression of U90926 in adipose tissue stromal vascular cell fraction, yet observed no effect of U90926 deficiency on weight gain, fat mass, adipogenesis marker expression, and immune cell infiltration into the adipose tissue. These data suggest that the U90926 lacks an essential role in obesity-related phenotypes and adipose tissue biology in vivo.

Emerging diagnostic markers and therapeutic targets in post-stroke hemorrhagic transformation and brain edema

Stroke is a devastating condition that can lead to significant morbidity and mortality. The aftermath of a stroke, particularly hemorrhagic transformation (HT) and brain edema, can significantly impact the prognosis of patients. Early detection and effective management of these complications are crucial for improving outcomes in stroke patients. This review highlights the emerging diagnostic markers and therapeutic targets including claudin, occludin, zonula occluden, s100β, albumin, MMP-9, MMP-2, MMP-12, IL-1β, TNF-α, IL-6, IFN-γ, TGF-β, IL-10, IL-4, IL-13, MCP-1/CCL2, CXCL2, CXCL8, CXCL12, CCL5, CX3CL1, ICAM-1, VCAM-1, P-selectin, E-selectin, PECAM-1/CD31, JAMs, HMGB1, vWF, VEGF, ROS, NAC, and AQP4. The clinical significance and implications of these biomarkers were also discussed.

Acute ischemia induces spatially and transcriptionally distinct microglial subclusters

BACKGROUND

Damage in the ischemic core and penumbra after stroke affects patient prognosis. Microglia immediately respond to ischemic insult and initiate immune inflammation, playing an important role in the cellular injury after stroke. However, the microglial heterogeneity and the mechanisms involved remain unclear.

METHODS

We first performed single-cell RNA-sequencing (scRNA-seq) and spatial transcriptomics (ST) on middle cerebral artery occlusion (MCAO) mice from three time points to determine stroke-associated microglial subclusters and their spatial distributions. Furthermore, the expression of microglial subcluster-specific marker genes and the localization of different microglial subclusters were verified on MCAO mice through RNAscope and immunofluorescence. Gene set variation analysis (GSVA) was performed to reveal functional characteristics of microglia sub-clusters. Additionally, ingenuity pathway analysis (IPA) was used to explore upstream regulators of microglial subclusters, which was confirmed by immunofluorescence, RT-qPCR, shRNA-mediated knockdown, and targeted metabolomics. Finally, the infarct size, neurological deficits, and neuronal apoptosis were evaluated in MCAO mice after manipulation of specific microglial subcluster.

RESULTS

We discovered stroke-associated microglial subclusters in the brains of MCAO mice. We also identified novel marker genes of these microglial subclusters and defined these cells as ischemic core-associated (ICAM) and ischemic penumbra-associated (IPAM) microglia, according to their spatial distribution. ICAM, induced by damage-associated molecular patterns, are probably fueled by glycolysis, and exhibit increased pro-inflammatory cytokines and chemokines production. BACH1 is a key transcription factor driving ICAM generation. In contrast, glucocorticoids, which are enriched in the penumbra, likely trigger IPAM formation, which are presumably powered by the citrate cycle and oxidative phosphorylation and are characterized by moderate pro-inflammatory responses, inflammation-alleviating metabolic features, and myelinotrophic properties.

CONCLUSIONS

ICAM could induce excessive neuroinflammation, aggravating brain injury, whereas IPAM probably exhibit neuroprotective features, which could be essential for the homeostasis and survival of cells in the penumbra. Our findings provide a biological basis for targeting specific microglial subclusters as a potential therapeutic strategy for ischemic stroke.

Gene therapy of adeno-associated virus (AAV) vectors in preclinical models of ischemic stroke

Stroke has been associated with devastating clinical outcomes, with current treatment strategies proving largely ineffective. Therefore, there is a need to explore alternative treatment options for addressing post-stroke functional deficits. Gene therapy utilizing adeno-associated viruses (AAVs) as a critical gene vector delivering genes to the central nervous system (CNS) gene delivery has emerged as a promising approach for treating various CNS diseases. This review aims to provide an overview of the biological characteristics of AAV vectors and the therapeutic advancements observed in preclinical models of ischemic stroke. The study further investigates the potential of manipulating AAV vectors in preclinical applications, emphasizing the challenges and prospects in the selection of viral vectors, drug delivery strategies, immune reactions, and clinical translation.

Infiltrating myeloid cell-derived properdin markedly promotes microglia-mediated neuroinflammation after ischemic stroke

BACKGROUND

Emerging evidence has shown that myeloid cells that infiltrate into the peri-infarct region may influence the progression of ischemic stroke by interacting with microglia. Properdin, which is typically secreted by immune cells such as neutrophils, monocytes, and T cells, has been found to possess damage-associated molecular patterns (DAMPs) properties and can perform functions unrelated to the complement pathway. However, the role of properdin in modulating microglia-mediated post-stroke neuroinflammation remains unclear.

METHODS

Global and conditional (myeloid-specific) properdin-knockout mice were subjected to transient middle cerebral artery occlusion (tMCAO). Histopathological and behavioral tests were performed to assess ischemic brain injury in mice. Single-cell RNA sequencing and immunofluorescence staining were applied to explore the source and the expression level of properdin. The transcriptomic profile of properdin-activated primary microglia was depicted by transcriptome sequencing. Lentivirus was used for macrophage-inducible C-type lectin (Mincle) silencing in microglia. Conditioned medium from primary microglia was administered to primary cortex neurons to determine the neurotoxicity of microglia. A series of cellular and molecular biological techniques were used to evaluate the proinflammatory response, neuronal death, protein-protein interactions, and related signaling pathways, etc. RESULTS: The level of properdin was significantly increased, and brain-infiltrating neutrophils and macrophages were the main sources of properdin in the ischemic brain. Global and conditional myeloid knockout of properdin attenuated microglial overactivation and inflammatory responses at the acute stage of tMCAO in mice. Accordingly, treatment with recombinant properdin enhanced the production of proinflammatory cytokines and augmented microglia-potentiated neuronal death in primary culture. Mechanistically, recombinant properdin served as a novel ligand that activated Mincle receptors on microglia and downstream pathways to drive primary microglia-induced inflammatory responses. Intriguingly, properdin can directly bind to the microglial Mincle receptor to exert the above effects, while Mincle knockdown limits properdin-mediated microglial inflammation.

CONCLUSION

Properdin is a new medium by which infiltrating peripheral myeloid cells communicate with microglia, further activate microglia, and exacerbate brain injury in the ischemic brain, suggesting that targeted disruption of the interaction between properdin and Mincle on microglia or inhibition of their downstream signaling may improve the prognosis of ischemic stroke.

Methylation of lncSHGL promotes adipocyte differentiation by regulating miR-149/Mospd3 axis

Obesity poses significant health risks and can negatively impact an individual's quality of life. The human obesity phenotype results from the differentiation of pre-adipocytes into adipocytes, which leads to hypertrophy and hyperplasia in adipose tissue. The molecular mechanisms by which long non-coding RNAs (lncRNAs) modulate adipocyte differentiation, a process implicated in obesity development, remain poorly characterized. A lncRNA which suppressed the hepatic gluconeogenesis and lipogenesis (lncSHGL) was newly identified. Our research aims to elucidate the functional role and mechanistic underpinnings of suppressor of lncSHGL in adipocyte differentiation. We observed that lncSHGL expression progressively diminished during 3T3-L1 differentiation and was downregulated in the liver and perirenal adipose tissue of ob/ob mice. lncSHGL acts as a molecular sponge for miR-149, with Mospd3 identified as a target of miR-149.Overexpression of lncSHGL and inhibition of miR-149 led to suppressed 3T3-L1 proliferation, decreased lipid droplet accumulation, and attenuated promoter activity of PPARγ2 and C/EBPα. These changes consequently resulted in reduced expression of Cyclin D1, LPL, PPARγ2, AP2, and C/EBPα, as well as inhibited the PI3K/AKT/mTOR signaling pathway. In contrast, lncSHGL suppression yielded opposing outcomes. Moreover, the effects of lncSHGL overexpression and miR-149 inhibition on reduced expression of Cyclin D1, LPL, PPARγ2, AP2, and C/EBPα were reversible upon miR-149 overexpression and Mospd3 suppression. These findings were further validated in vivo. We also discovered a significant increase in methylation levels during 3T3-L1 differentiation, with lncSHGL highly expressed in the presence of a methylation inhibitor. In conclusion. lncSHGL methylation facilitates adipocyte differentiation by modulating the miR-149/Mospd3 axis. Targeting lncSHGL expression may represent a promising therapeutic strategy for obesity-associated adipogenesis, particularly in the context of fatty liver disease.

Transcriptomics and metabolomics study in mouse kidney of the molecular mechanism underlying energy metabolism response to hypoxic stress in highland areas

Exposure to hypoxia disrupts energy metabolism and induces inflammation. However, the pathways and mechanisms underlying energy metabolism disorders caused by hypoxic conditions remain unclear. In the present study, a hypoxic animal model was created and transcriptomic and non-targeted metabolomics techniques were applied to further investigate the pathways and mechanisms of hypoxia exposure that disrupt energy metabolism. Transcriptome results showed that 3,007 genes were significantly differentially expressed under hypoxic exposure, and Gene Ontology annotation analysis and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis showed that the differentially expressed genes (DEGs) were mainly involved in energy metabolism and were significantly enriched in the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) pathway. The DEGs IDH3A, SUCLA2, and MDH2 in the TCA cycle and the DEGs NDUFA3, NDUFS7, UQCRC1, CYC1 and UQCRFS1 in the OXPHOS pathway were validated using mRNA and protein expression, and the results showed downregulation. The results of non-targeted metabolomics showed that 365 significant differential metabolites were identified under plateau hypoxia stress. KEGG enrichment analysis showed that the differential metabolites were mainly enriched in metabolic processes, such as energy, nucleotide and amino acid metabolism. Hypoxia exposure disrupted the TCA cycle and reduced the synthesis of amino acids and nucleotides by decreasing the concentration of cis-aconitate, α-ketoglutarate, NADH, NADPH and that of most amino acids, purines, and pyrimidines. Bioinformatics analysis was used to identify inflammatory genes related to hypoxia exposure and some of them were selected for verification. It was shown that the mRNA and protein expression levels of IL1B, IL12B, S100A8 and S100A9 in kidney tissues were upregulated under hypoxic exposure. The results suggest that hypoxia exposure inhibits the TCA cycle and the OXPHOS signalling pathway by inhibiting IDH3A, SUCLA2, MDH2, NDUFFA3, NDUFS7, UQCRC1, CYC1 and UQCRFS1, thereby suppressing energy metabolism, inducing amino acid and nucleotide deficiency and promoting inflammation, ultimately leading to kidney damage.

The regulation of circRNA and lncRNAprotein binding in cardiovascular diseases: Emerging therapeutic targets

Noncoding ribonucleic acids (ncRNAs) are a class of ribonucleic acids (RNAs) that carry cellular information and perform essential functions. This class encompasses various RNAs, such as small nuclear ribonucleic acids (snRNA), small interfering ribonucleic acids (siRNA) and many other kinds of RNA. Of these, circular ribonucleic acids (circRNAs) and long noncoding ribonucleic acids (lncRNAs) are two types of ncRNAs that regulate crucial physiological and pathological processes, including binding, in several organs through interactions with other RNAs or proteins. Recent studies indicate that these RNAs interact with various proteins, including protein 53, nuclear factor-kappa B, vascular endothelial growth factor, and fused in sarcoma/translocated in liposarcoma, to regulate both the histological and electrophysiological aspects of cardiac development as well as cardiovascular pathogenesis, ultimately leading to a variety of genetic heart diseases, coronary heart disease, myocardial infarction, rheumatic heart disease and cardiomyopathies. This paper presents a thorough review of recent studies on circRNA and lncRNAprotein binding within cardiac and vascular cells. It offers insight into the molecular mechanisms involved and emphasizes potential implications for treating cardiovascular diseases.

Blood-brain crosstalk: the roles of neutrophils, platelets, and neutrophil extracellular traps in neuropathologies

Systemic inflammation, neurovascular dysfunction, and coagulopathy often occur concurrently in neuropathologies. Neutrophils and platelets have crucial synergistic roles in thromboinflammation and are increasingly suspected as effector cells contributing to the pathogenesis of neuroinflammatory diseases. In this review, we summarize the roles of platelet-neutrophil interactions in triggering complex pathophysiological events affecting the brain that may lead to the disruption of brain barriers, infiltration of toxic factors into the parenchyma, and amplification of neuroinflammation through the formation of neutrophil extracellular traps (NETs). We highlight the clinical significance of thromboinflammation in neurological disorders and examine the contributions of damage-associated molecular patterns (DAMPs) derived from platelets and neutrophils. These DAMPs originate from both infectious and non-infectious risk factors and contribute to the activation of inflammasomes during brain disorders. Finally, we identify knowledge gaps in the molecular mechanisms underlying neurodegenerative disease pathogenesis and emphasize the potential of interventions targeting platelets and neutrophils to treat neuroinflammatory diseases.

Emerging role of non-coding RNAs in neuroinflammation mediated by microglia and astrocytes

Neuroinflammation has been implicated in the initiation and progression of several central nervous system (CNS) disorders, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, ischemic stroke, traumatic brain injury, spinal cord injury, viral encephalitis, and bacterial encephalitis. Microglia and astrocytes are essential in neural development, maintenance of synaptic connections, and homeostasis in a healthy brain. The activation of astrocytes and microglia is a defense mechanism of the brain against damaged tissues and harmful pathogens. However, their activation triggers neuroinflammation, which can exacerbate or induce CNS injury. Non-coding RNAs (ncRNAs) are functional RNA molecules that lack coding capabilities but can actively regulate mRNA expression and function through various mechanisms. ncRNAs are highly expressed in astrocytes and microglia and are potential mediators of neuroinflammation. We reviewed the recent research progress on the role of miRNAs, lncRNAs, and circRNAs in regulating neuroinflammation in various CNS diseases. Understanding how these ncRNAs affect neuroinflammation will provide important therapeutic insights for preventing and managing CNS dysfunction.

A newly-synthesized compound CP-07 alleviates microglia-mediated neuroinflammation and ischemic brain injury via inhibiting STAT3 phosphorylation

Background and Objectives

Overactivated glial cells, especially microglia, are core components in the progression of pathologic neuroinflammation, and the application of anti-inflammatory reagents has been regarded as a potential therapy in the management of infarction/reperfusion (I/R) brain injury. This research aims to clarify the anti-inflammatory efect of a novel lipophilic compound N-(2-[4-tert-butylphenyl]-2-[pyrrolidine-1-yl]ethyl)-7-methyl-4-oxo-4H-chromene-2-carboxamide (named CP-07 in this study) in LPS-stimulated BV2 cell line and primary mouse microglia, and its therapeutic effect on I/R brain injury.

Method

Cell Counting Kit-8 assay was used to determine the maximal nontoxic dose of CP-07. The mRNA levels of representative proinflammatory cytokines were determined by quantitative real-time polymerase chain reaction both in vitro and in vivo. TTC staining was performed to calculate infarct volumes while behavioral tests were used to assess the neurological deficits at 24 h after middle cerebral artery occlusion (MCAO). Flow cytometry analysis and immunofluorescence staining were performed to calculate the percentage of pro-inflammatory microglia in vivo.A selective JAK2/STAT3 pathway inhibitor, AG490 was used to block STAT3 phosphorylation before the CP-07 anti-inflammation tests in vitro.

Results

CP-07 could effectively suppress the mRNA levels of IL-6, IL-1β, iNOS and TNF-α induced by lipopolysaccharide (LPS) in vitro, and markedly block the evaluation of the fluorescence intensity of Iba-1 in primary mouse microglia. In middle cerebral arteryocclusion models, intraperitoneal injection with 1 mg/kg CP-07 significantly reduced cerebral infarct volumes at 24 h after surgery compared with vehicle treatment group, and promoted the recovery of neurological functions in MCAO mice. Further studies validated that CP-07 administration reduced the percentage of CD86 positive microglia after I/R injury, and the expression level of p-STAT3 was also markedly reduced in both microglial cells and the penumbra tissues. Blocking STAT3 phosphorylation with AG490 could completely eliminate the anti-inflammatory effects of CP-07, at least in vitro.

Conclusion

We showed that a newly synthesized compound, CP-07, could effectively reduce the inflammatory responses in LPS-stimulated BV2 cells and primary mouse microglia, and overproduction of cytokines in middle cerebral artery occlusion mouse models by inhibiting STAT3 phosphorylation, leading to a neuroprotective effect on I/R brain injury.

Targeting p53 for neuroinflammation: New therapeutic strategies in ischemic stroke

Ischemic stroke (IS) is characterized by high incidence, high recurrence, and high mortality and places a heavy burden on society and families. The pathological mechanisms of IS are complex, among which secondary neurological impairment mediated by neuroinflammation is considered to be the main factor in cerebral ischemic injury. At present, there is still a lack of specific therapies to treat neuroinflammation. The tumor suppressor protein p53 has long been regarded as a key substance in the regulation of the cell cycle and apoptosis in the past. Recently, studies have found that p53 also plays an important role in neuroinflammatory diseases, such as IS. Therefore, p53 may be a crucial target for the regulation of the neuroinflammatory response. Here, we provide a comprehensive review of the potential of targeting p53 in the treatment of neuroinflammation after IS. We describe the function of p53, the major immune cells involved in neuroinflammation, and the role of p53 in inflammatory responses mediated by these cells. Finally, we summarize the therapeutic strategies of targeting p53 in regulating the neuroinflammatory response after IS to provide new directions and ideas for the treatment of ischemic brain injury.

Activated neutrophil-derived exosomes contribute to blood-brain barrier damage and hemorrhagic transformation after cerebral ischemia/reperfusion

BACKGROUND

Hemorrhagic transformation (HT) caused by blood-brain barrier (BBB) damage is closely correlated with the poor prognosis of ischemic stroke. Neutrophils are proven to mediate BBB injury after ischemic stroke, but the mechanism remains to be further investigated. Therefore, the present study aims to investigate the effect of neutrophil-derived exosomes on BBB integrity.

METHOD

A tMCAO-HT model was constructed to assess neutrophil infiltration and its co-localization with brain microvascular endothelial cells (BMEC). After using quiet (Q-Neu) and activated neutrophil (A-Neu) and their exosomes to treat the BBB model in vitro, TEER and permeability were assayed to assess the BBB integrity. Small RNA sequencing was performed to identify differentially expressed miRNAs (DE-miRNAs) in A-Neu- and Q-Neu-derived exosomes, and the function and pathways of DE-miRNA targets were analyzed by GO and KEGG enrichment.

RESULT

Different degrees of cerebral hemorrhage were observed in the tMCAO-HT model. The expression of the neutrophil marker Ly6G was significantly increased in tMCAO-HT model compared to the sham group, and co-localized with the BMEC marker CD31. Notably, Ly6G expression was positively correlated with hemoglobin content in brain tissue. A-Neu and its derived exosomes reduced TEER and elevated permeability in the BBB model in vitro. Moreover, BBB-related proteins Claudin 5, Occludin and ZO-1 expression were significantly reduced in BMEC after treatment with A-Neu and its derived exosomes. Nevertheless, Q-Neu and its exosomes had no significant effect on BBB integrity. A total of 84 DE-miRNAs are present in Q-Neu- and A-Neu-derived exosomes, and their target genes are involved in the regulation of "positive regulation of establishment of endothelial barrier", "cell junction", "ECM-receptor interaction" and "VEGF signaling pathway". Moreover, RT-qPCR revealed that the expression trends of miR-409-3p, miR-6909-5p, miR-3473d, miR-370-3p and miR-6904-5p in exosomes were consistent with the sequencing results.

CONCLUSION

Neutrophils are abnormally recruited in HT after ischemic stroke, and are associated with cerebral hemorrhage. In vitro, A-Neu-derived exosomes facilitate BBB injury, which may be accomplished by exosomal transport of miRNAs.

Construction and analysis of circular RNA-associated competing endogenous RNA network in the hippocampus of aged mice for the occurrence of postoperative cognitive dysfunction

Circular RNAs are highly stable single-stranded circular RNAs and enriched in the brain. Previous studies showed that circRNAs, as part of competing endogenous RNAs (ceRNAs) network, play an important role in neurodegenerative and psychiatric diseases. However, the mechanism of circRNA-related ceRNA networks in postoperative cognitive dysfunction (POCD) has not been elucidated yet. POCD usually occurs in elderly patients and is characterized by hippocampal dysfunction. Here, aged C57BL/6 mice were subjected to exploratory laparotomy under sevoflurane anesthesia, and this POCD model was verified by Morris water maze test. Whole-transcriptome sequencing was performed on the hippocampus of control group (Con) and surgery group. One hundred and seventy-seven DEcircRNAs, 221 DEmiRNAs and 2,052 DEmRNAs were identified between two groups. A ceRNA network was established with 92 DEcircRNAs having binding sites with 76 DEmiRNAs and 549 target DEmRNAs. In functional enrichment analysis, a pathological pattern of POCD was highlighted in the ceRNA network: Abnormal metabolic process in neural cells, including oxygen metabolism, could promote apoptosis and then affect the synaptic function, which may undermine the neural plasticity and eventually lead to changes in cognitive function and other behavioral patterns. In conclusion, this specific ceRNA network of circRNAs–miRNAs–mRNAs has provided novel insights into the regulatory mechanisms of POCD and revealed potential therapeutic gene targets.

Long Noncoding RNA U90926 Is Induced in Activated Macrophages, Is Protective in Endotoxic Shock, and Encodes a Novel Secreted Protein

Thousands of long noncoding RNAs are encoded in mammalian genomes, yet most remain uncharacterized. In this study, we functionally characterized a mouse long noncoding RNA named U90926. Analysis of U90926 RNA levels revealed minimal expression across multiple tissues at steady state. However, the expression of this gene was highly induced in macrophages and dendritic cells by TLR activation, in a p38 MAPK- and MyD88-dependent manner. To study the function of U90926, we generated U90926-deficient (U9-KO) mice. Surprisingly, we found minimal effects of U90926 deficiency in cultured macrophages. Given the lack of macrophage-intrinsic effect, we investigated the subcellular localization of U90926 transcript and its protein-coding potential. We found that U90926 RNA localizes to the cytosol, associates with ribosomes, and contains an open reading frame that encodes a novel glycosylated protein (termed U9-ORF), which is secreted from the cell. An in vivo model of endotoxic shock revealed that, in comparison with wild type mice, U9-KO mice exhibited increased sickness responses and mortality. Mechanistically, serum levels of IL-6 were elevated in U9-KO mice, and IL-6 neutralization improved endotoxemia outcomes in U9-KO mice. Taken together, these results suggest that U90926 expression is protective during endotoxic shock, potentially mediated by the paracrine and/or endocrine actions of the novel U9-ORF protein secreted by activated myeloid cells.

The landscape of m1A modification and its posttranscriptional regulatory functions in primary neurons

Cerebral ischaemia‒reperfusion injury (IRI), during which neurons undergo oxygen-glucose deprivation/reoxygenation (OGD/R), is a notable pathological process in many neurological diseases. N1-methyladenosine (m¹A) is an RNA modification that can affect gene expression and RNA stability. The m¹A landscape and potential functions of m¹A modification in neurons remain poorly understood. We explored RNA (mRNA, lncRNA, and circRNA) m¹A modification in normal and OGD/R-treated mouse neurons and the effect of m¹A on diverse RNAs. We investigated the m¹A landscape in primary neurons, identified m¹A-modified RNAs, and found that OGD/R increased the number of m¹A RNAs. m¹A modification might also affect the regulatory mechanisms of noncoding RNAs, e.g., lncRNA-RNA binding proteins (RBPs) interactions and circRNA translation. We showed that m¹A modification mediates the circRNA/lncRNA‒miRNA-mRNA competing endogenous RNA (ceRNA) mechanism and that 3' untranslated region (3'UTR) modification of mRNAs can hinder miRNA-mRNA binding. Three modification patterns were identified, and genes with different patterns had intrinsic mechanisms with potential m¹A-regulatory specificity. Systematic analysis of the m¹A landscape in normal and OGD/R neurons lays a critical foundation for understanding RNA modification and provides new perspectives and a theoretical basis for treating and developing drugs for OGD/R pathology-related diseases.

Characteristics and pathogenesis of chemokines in the post-stroke stage

Chemokines, as small molecular proteins, play a crucial role in the immune and inflammatory responses after stroke. A large amount of evidence showed chemokines and their receptors were increasingly recognized as potential targets for stroke treatment, which were involved in the processing of neovascularization, neurogenesis, and neural network reconstruction. In this review, we summarized the characteristics of chemokine alterations throughout the post-stroke nerve repair phase to gain insight into the pathological mechanisms of chemokines and find effective therapeutic targets for stroke.

Long non-coding RNAs: The modulators of innate and adaptive immune cells

Before very sensitive current genomics platforms were discovered, long non-coding RNAs (lncRNAs) as controllers of gene expression, were thought to be accumulated genetic garbage. The past few years have seen a lot of interest in a large classification of non-coding transcripts with an indeterminate length of more than 200 nucleotides [1]. lncRNAs' association with immunity and disease progression has been revealed by a growing body of experimental research. Only a limited subset of lncRNAs, however, has solid proof of their role. It is also clear that various immune cells express lncRNAs differently. In this review, we concentrated on the role of lncRNA expression in the regulation of immune cell function and response to pathological conditions in macrophages, dendritic cells, natural killer (NK) cells, neutrophils, Myeloid-derived suppressor cells (MDSCs), T cells, and B cells. The innate and adaptive immune response systems may be significantly regulated by lncRNAs, according to emerging research. To discover possible therapeutic targets for the therapy of different diseases, it may be helpful to have a better realization of the molecular mechanisms beyond the role of lncRNAs in the immune response. Therefore, it is crucial to investigate lncRNA expression and comprehend its significance for the immune system.

PPARγ/RAD21 alleviates peripheral secondary brain injury in rat cerebral hemorrhage model through promoting M2 polarization of microglial cells

BACKGROUND

PPARγ has been reported to participate in intracerebral hemorrhage (ICH) progression, and recruit RAD21 through binding DNA. Our study aimed to explore the roles of PPARγ/RAD21 in ICH and their related mechanisms.

METHODS

ICH models in vitro and in vivo were established using thrombin and autologous blood injection, respectively. After that, rosiglitazone (RSG), GW9662, and RAD21 knockdown/overexpression plasmids were used to treat the ICH models. The cell apoptosis, the related inflammatory cytokines levels, and the neurological function of the rats were examined. Real-time quantitative PCR (RT-qPCR), western blot and immunofluorescence were employed to determine the expression of the M1/M2 polarization-related markers. Finally, the interaction of PPARγ and RAD21 in microglial cells was observed using double labeled immunofluorescence and co-immunoprecipitation.

RESULTS

After thrombin induction, the cell apoptosis, and TNF-α, IL-1β and IL-10 contents were all significantly increased (P < 0.05); whereas RSG and RAD21 overexpression evidently inhibited the apoptosis of thrombin-caused microglial cells, reduced TNF-α and IL-1β contents, further increased IL-10 content (P < 0.05). The combination of RAD21 and PPARγ was enhanced by RSG and RAD21 overexpression. In vivo experiments showed that RSG and RAD21 overexpression decreased neurological deficit score, brain water content and hematoma volume. Additionally, RSG and RAD21 overexpression up-regulated the expression of PPARγ, RAD21, Arg1, KLF4, and TGF-β, whereas down-regulated iNOS and CD32 expression. The actions of GW9662 and RAD21 knockdown were opposite to those of RSG and RAD21 overexpression.

CONCLUSION

PPARγ/RAD21 may alleviate ICH progression through promoting M2-type polarization of microglial cells and inhibiting inflammatory response.

A monoamine oxidase B inhibitor ethyl ferulate suppresses microglia-mediated neuroinflammation and alleviates ischemic brain injury

Microglia are the resident macrophages in the brain, which play a critical role in post-stroke neuroinflammation. Accordingly, targeting neuroinflammation could be a promising strategy to improve ischemic stroke outcomes. Ethyl ferulate (EF) has been confirmed to possess anti-inflammatory properties in several disease models, including acute lung injury, retinal damage and diabetes-associated renal injury. However, the effects of EF on microglial activation and the resolution of post-stroke neuroinflammation remains unknown. Here, we found that EF suppressed pro-inflammatory response triggered by lipopolysaccharide (LPS) stimulation in primary microglia and BV2 cell lines, as well as post-stroke neuroinflammation in an in vivo transient middle cerebral artery occlusion (tMCAO) stroke model in C57BL/6 mice, consequently ameliorating ischemic brain injury. Furthermore, EF could directly bind and inhibit the activity of monoamine oxidase B (MAO-B) to reduce pro-inflammatory response. Taken together, our study identified a MAO-B inhibitor, Ethyl ferulate, as an active compound with promising potentials for suppressing post-stroke neuroinflammation.

Microglia-mediated neuroinflammation and neuroplasticity after stroke

Stroke remains a major cause of long-term disability and mortality worldwide. The immune system plays an important role in determining the condition of the brain following stroke. As the resident innate immune cells of the central nervous system, microglia are the primary responders in a defense network covering the entire brain parenchyma, and exert various functions depending on dynamic communications with neurons, astrocytes, and other neighboring cells under both physiological or pathological conditions. Microglia activation and polarization is crucial for brain damage and repair following ischemic stroke, and is considered a double-edged sword for neurological recovery. Microglia can exist in pro-inflammatory states and promote secondary brain damage, but they can also secrete anti-inflammatory cytokines and neurotrophic factors and facilitate recovery following stroke. In this review, we focus on the role and mechanisms of microglia-mediated neuroinflammation and neuroplasticity after ischemia and relevant potential microglia-based interventions for stroke therapy.

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.

Serpine1 Regulates Peripheral Neutrophil Recruitment and Acts as Potential Target in Ischemic Stroke

Introduction

Peripheral neutrophil infiltration can exacerbate ischemia–reperfusion injury. We focused on the relationship between various peripheral immune cells and cerebral ischemia–reperfusion (I/R) injury.

Methods

In this study, we investigated the effects of dauricine on neuronal injury induced by ischemia–reperfusion and peripheral immune cells after ischemic stroke in mouse model, and we explored the undefined mechanisms of regulating peripheral immune cells through RNA sequencing and various biochemical verification in vitro and in vivo.

Results

We found that dauricine improved the neurological deficits of I/R injury, reduced the infarct volume, and improved the neurological scores. Furthermore, dauricine reduced the infiltration of neutrophils into the brain after MCAO-R and increased peripheral neutrophils but unchanged the permeability of the endotheliocyte Transwell system in an in vitro blood-brain barrier (BBB) model. RNA sequencing showed that chemotaxis factors, such as CXCL3, CXCL11, CCL20, CCL22, IL12a, IL23a, and serpine1, might play a crucial role. Overexpression of serpine1 reversed LPS-induced migration of neutrophils. Dauricine can directly bind with serpine1 in ligand–receptor docking performed with the Autodock and analyzed with PyMOL.

Conclusion

We identified chemotaxis factor serpine1 played a crucial role in peripheral neutrophil infiltration, which may contribute to reduce the neuronal injury induced by ischemia–reperfusion. These findings reveal that serpine1 may act as a potential treatment target in the acute stage of ischemic stroke.

SNHG15 is a negative regulator of inflammation by mediating TRAF2 ubiquitination in stroke-induced immunosuppression

BACKGROUND

Abnormal expression of long noncoding RNAs (lncRNAs) has been reported in the acute stage of acute ischemic stroke (AIS). This study aimed to explore differential lncRNA expression in the subpopulations of peripheral blood mononuclear cells (PBMCs) from AIS patients and further evaluate its underlying mechanisms in stroke-induced immunosuppression.

METHODS

We reanalyzed lncRNA microarray data and investigated abnormally expressed lncRNAs in the subpopulations of PBMCs by magnetic cell sorting and real-time quantitative PCR. The potential mechanism of small nucleolar RNA host gene 15 (SNHG15) was explored through in vitro and in vivo approaches.

RESULTS

The stroke-induced SNHG15 acted as a checkpoint to inhibit peripheral inflammatory responses. Functional studies showed that SNHG15 promoted M2 macrophage polarization. Mechanistically, SNHG15 expression was dysregulated through the Janus kinase (JAK)-signal transducer and activator of transcription 6 (STAT6) signaling pathway. SNHG15, localized in the cytoplasm, interfered with K63-linked ubiquitination of tumor necrosis factor receptor-associated factor 2 and thereby repressed the activation of mitogen-activated protein kinase and nuclear factor kappa-B signaling pathways and prevented the production of proinflammatory cytokines. Administration of an adenovirus targeting SNHG15 improved stroke-induced immunosuppression in mice.

CONCLUSIONS

This study identified SNHG15 as a negative regulator of inflammation in stroke-induced immunosuppression, suggesting it as a novel biomarker and therapeutic target in stroke-associated infection. Trial registration ClinicalTrials.gov NCT04175691. Registered November 25, 2019, https://www.clinicaltrials.gov/ct2/show/NCT04175691 .

Long Non-coding RNAs and Circular RNAs: Insights Into Microglia and Astrocyte Mediated Neurological Diseases

Microglia and astrocytes maintain tissue homeostasis in the nervous system. Both microglia and astrocytes have pro-inflammatory phenotype and anti-inflammatory phenotype. Activated microglia and activated astrocytes can contribute to several neurological diseases. Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two groups of non-coding RNAs (ncRNAs), can function as competing endogenous RNAs (ceRNAs) to impair the microRNA (miRNA) inhibition on targeted messenger RNAs (mRNAs). LncRNAs and circRNAs are involved in various neurological disorders. In this review, we summarized that lncRNAs and circRNAs participate in microglia dysfunction, astrocyte dysfunction, neuron damage, and inflammation. Thereby, lncRNAs and circRNAs can positively or negatively regulate neurological diseases, including spinal cord injury (SCI), traumatic brain injury (TBI), ischemia-reperfusion injury (IRI), stroke, neuropathic pain, epilepsy, Parkinson’s disease (PD), multiple sclerosis (MS), and Alzheimer’s disease (AD). Besides, we also found a lncRNA/circRNA-miRNA-mRNA regulatory network in microglia and astrocyte mediated neurological diseases. Through this review, we hope to cast light on the regulatory mechanisms of lncRNAs and circRNAs in microglia and astrocyte mediated neurological diseases and provide new insights for neurological disease treatment.

Emerging Role of LncRNAs in Ischemic Stroke-Novel Insights into the Regulation of Inflammation

As a crucial kind of pervasive gene, long noncoding RNAs (lncRNAs) are abundant and key players in brain function as well as numerous neurological disorders, especially ischemic stroke. The mechanisms underlying ischemic stroke include angiogenesis, autophagy, apoptosis, cell death, and neuroinflammation. Inflammation plays a vital role in the pathological process of ischemic stroke, and systemic inflammation affects the patient’s prognosis. Although a great deal of research has illustrated that various lncRNAs are closely relevant to regulate neuroinflammation and microglial activation in ischemic stroke, the specific interactional relationships and mechanisms between lncRNAs and neuroinflammation have not been described clearly. This review aimed to summarize the therapeutic effects and action mechanisms of lncRNAs on ischemia by regulating inflammation and microglial activation. In addition, we emphasize that lncRNAs have the potential to modulate inflammation by inhibiting and activating various signaling pathways, such as microRNAs, NF‐κB and ERK.

LncRNA AC020978 facilitates non-small cell lung cancer progression by interacting with malate dehydrogenase 2 and activating the AKT pathway

Long non–coding RNA AC020978 (lncRNA AC020978) is an oncogenic regulator of non–small cell lung cancer (NSCLC). However, the function of AC020978 in regulating NSCLC metastasis and the potential molecular mechanism remains largely unknown. In this study, we evaluated the expression levels of AC020978 in a series of NSCLC tissues using FISH assays and found that higher AC020978 expression levels were closely associated with metastasis and unfavorable prognosis. Functional studies showed that AC020978 promoted NSCLC migration and invasion both in vitro and in vivo. Further investigation demonstrated that AC020978 interacted with malate dehydrogenase 2 (MDH2) and maintained MDH2 stability. Knockdown of MDH2 weakened the facilitating effect on cell metastasis and 2‐hydroxyglutarate (2‐HG) metabolism in AC020978‐overexpressed NSCLC cells. RNA sequencing, bioinformatic analysis, and western blotting revealed that AC020978 was associated with the AKT signaling pathway. Taken together, our findings revealed that AC020978 might serve as a prognostic biomarker and activate the AKT pathway by stabilizing MDH2, leading to metastasis and progression of NSCLC.