MicroRNA‑381/Hes1 is a potential therapeutic target for spinal cord injury

Spinal Cord Injury: From MicroRNAs to Exosomal MicroRNAs

Spinal cord injury (SCI) is an unfortunate experience that may generate extensive sensory and motor disabilities due to the destruction and passing of nerve cells. MicroRNAs are small RNA molecules that do not code for proteins but instead serve to regulate protein synthesis by targeting messenger RNA's expression. After SCI, secondary damage like apoptosis, oxidative stress, inflammation, and autophagy occurs, and differentially expressed microRNAs show a function in these procedures. Almost all animal and plant cells release exosomes, which are sophisticated formations of lipid membranes. These exosomes have the capacity to deliver significant materials, such as proteins, RNAs and lipids, to cells in need, regulating their functions and serving as a way of communication. This new method offers a fresh approach to treating spinal cord injury. Obviously, the exosome has the benefit of conveying the transported material across performing regulatory activities and the blood-brain barrier. Among the exosome cargoes, microRNAs, which modulate their mRNA targets, show considerable promise in the pathogenic diagnosis, process, and therapy of SCI. Herein, we describe the roles of microRNAs in SCI. Furthermore, we emphasize the importance of exosomal microRNAs in this disease.

MiRNAs as Promising Translational Strategies for Neuronal Repair and Regeneration in Spinal Cord Injury

Spinal cord injury (SCI) represents a devastating injury to the central nervous system (CNS) that is responsible for impaired mobility and sensory function in SCI patients. The hallmarks of SCI include neuroinflammation, axonal degeneration, neuronal loss, and reactive gliosis. Current strategies, including stem cell transplantation, have not led to successful clinical therapy. MiRNAs are crucial for the differentiation of neural cell types during CNS development, as well as for pathological processes after neural injury including SCI. This makes them ideal candidates for therapy in this condition. Indeed, several studies have demonstrated the involvement of miRNAs that are expressed differently in CNS injury. In this context, the purpose of the review is to provide an overview of the pre-clinical evidence evaluating the use of miRNA therapy in SCI. Specifically, we have focused our attention on miRNAs that are widely associated with neuronal and axon regeneration. “MiRNA replacement therapy” aims to transfer miRNAs to diseased cells and improve targeting efficacy in the cells, and this new therapeutic tool could provide a promising technique to promote SCI repair and reduce functional deficits.

The neuroprotective mechanism of sevoflurane in rats with traumatic brain injury via FGF2

Background

Traumatic brain injury (TBI) is a kind of acquired brain injury, which is caused by external mechanical forces. Moreover, the neuroprotective role of sevoflurane (Sevo) has been identified in TBI. Therefore, this research was conducted to figure out the mechanism of Sevo in TBI via FGF2.

Methods

The key factors of neuroprotective effects of Sevo in TBI rats were predicted by bioinformatics analysis. A TBI model was induced on rats that then inhaled Sevo for 1 h and grouped via lentivirus injection. Modified Neurological Severity Score was adopted to evaluate neuronal damage in rats, followed by motor function and brain water content measurement. FGF2, EZH2, and HES1 expression in brain tissues was evaluated by immunofluorescence staining, and expression of related genes and autophagy factors by RT-qPCR and Western blot analysis. Methylation-specific PCR was performed to assess HES1 promoter methylation level, and ChIP assay to detect the enrichment of EZH2 in the HES1 promoter. Neuronal damage was assessed by cell immunofluorescence staining, and neuronal apoptosis by Nissl staining, TUNEL staining, and flow cytometry.

Results

Sevo diminished brain edema, improved neurological scores, and decreased neuronal apoptosis and autophagy in TBI rats. Sevo preconditioning could upregulate FGF2 that elevated EZH2 expression, and EZH2 bound to the HES1 promoter to downregulate HES1 in TBI rats. Also, FGF2 or EZH2 overexpression or HES silencing decreased brain edema, neurological deficits, and neuronal autophagy and apoptosis in Sevo-treated TBI rats.

Conclusions

Our results provided a novel insight to the neuroprotective mechanism of Sevo in TBI rats by downregulating HES1 via FGF2/EZH2 axis activation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02348-z.

Extracellular vesicles derived from mesenchymal stem cells containing microRNA-381 protect against spinal cord injury in a rat model via the BRD4/WNT5A axis

AIMS

Non-coding microRNA (miRNA) in extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) may promote neuronal repair after spinal cord injury (SCI). In this paper we report on the effects of MSC-EV-microRNA-381 (miR-381) in a rodent model of SCI.

METHODS

In the current study, the luciferase assay confirmed a binding site of bromodomain-containing protein 4 (BRD4) and Wnt family member 5A (WNT5A). Then we detected expression of miR-381, BRD4, and WNT5A in dorsal root ganglia (DRG) cells treated with MSC-isolated EVs and measured neuron apoptosis in culture by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. A rat model of SCI was established to detect the in vivo effect of miR-381 and MSC-EVs on SCI.

RESULTS

We confirmed an interaction between miR-381 and BRD4, and showed that miR-381 overexpression inhibited the expression of BRD4 in DRG cells as well as the apoptosis of DRG cells through WNT5A via activation of Ras homologous A (RhoA)/Rho-kinase activity. Moreover, treatment of MSC-EVs rescued neuron apoptosis and promoted the recovery of SCI through inhibition of the BRD4/WNT5A axis.

CONCLUSION

Taken altogether, miR-381 derived from MSC-EVs can promote the recovery of SCI through BRD4/WNT5A axis, providing a new perspective on SCI treatment. Cite this article: Bone Joint Res 2021;10(5):328-339.

Identification of Novel Hypothalamic MicroRNAs as Promising Therapeutics for SARS-CoV-2 by Regulating ACE2 and TMPRSS2 Expression: An In Silico Analysis

BACKGROUND

Neuroinvasion of severe acute respiratory syndrome coronavirus (SARS-CoV) is well documented and, given the similarities between this virus and SARS-CoV-2, it seems that the neurological impairment that is associated with coronavirus disease 2019 (COVID-19) is due to SARS-CoV-2 neuroinvasion. Hypothalamic circuits are exposed to the entry of the virus via the olfactory bulb and interact centrally with crucial respiratory nuclei. Hypothalamic microRNAs are considered as potential biomarkers and modulators for various diseases and future therapeutic targets. The present study aims to investigate the microRNAs that regulate the expression of hypothalamic angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), essential elements for SARS-CoV-2 cell entry.

METHODS

To determine potential hypothalamic miRNAs that can directly bind to ACE2 and TMPRSS2, multiple target bioinformatics prediction algorithms were used, including miRBase, Target scan, and miRWalk2.029.

RESULTS

Our in silico analysis has revealed that, although there are over 5000 hypothalamic miRNAs, around 31 miRNAs and 29 miRNAs have shown binding sites and strong binding capacity against ACE2 and TMPRSS2, respectively.

CONCLUSION

These novel potential hypothalamic miRNAs can be used to identify new therapeutic targets to treat neurological symptoms in COVID-19 patients via regulation of ACE2 and TMPRSS2 expression.

Effect of M2 macrophage adoptive transfer on transcriptome profile of injured spinal cords in rats

The previous studies showed that alternatively activated anti-inflammatory macrophage (M2) adoptive immunity can improve the proportion of local M2 cells and play the neuroprotective effect after spinal cord injury (SCI). Its molecular mechanism is not yet very clear. Therefore, this study aims to analyze the effect of the M2 adoptive transfer on the local expression of gene transcription. Sprague-Dawley (SD) rats were used for culture of macrophages and establishment of SCI models. After SCI, the polarized M2 macrophages were transferred to the injured rats by tail vein injection. Seven days after operation, the differentially expressed genes (DEGs) in the spinal cords were analyzed by RNA-sequencing (RNA-Seq). Then, the functional enrichment analysis and pathways were performed by using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), respectively. RNA-Seq showed that M2 adoptive immunity can down-regulate many well-studied gene expressions associated with signaling pathways of inflammatory, such as antigen processing and presentation, phagosome, cell adhesion molecules, natural killer cell-mediated cytotoxicity, endocytosis, proteasome, and Toll-like receptor signaling pathway. These may explain the mechanism of our previous adoptive immunization of M2 cells to provide neuroprotection for SCI. In addition, a novel pathway, retinoic acid-inducible gene-1 (RIG-I)-like receptor signaling pathway was found to be involved in the pathological process of SCI and the response to M2 adoptive immunity as well. This will provide a new explanation for the pathological mechanism of SCI and a new theoretical and experimental basis for its clinical treatment. The raw Illumina data are available at http://www.ncbi.nlm.nih.gov/sra (accession number PRJNA517238).

Impact statement

This research aimed to analyze the effect of M2 macrophage adoptive transfer on the local expression of gene transcription after SCI by RNA-Seq. The results showed that M2 adoptive immunity can down-regulate many well-studied gene expressions associated with signaling pathways of inflammatory. These may explain the mechanism of our previous adoptive immunization of M2 cells to provide neuroprotection for SCI. In addition, a novel pathway, RIG-I-like receptor signaling pathway was also found to involve in the pathological process of SCI and the response to M2 adoptive immunity. This will provide a new explanation for the pathological mechanism of SCI and a new theoretical and experimental basis for its clinical treatment.