lncRNA XIST inhibition promotes M2 polarization of microglial and aggravates the spinal cord injury via regulating miR-124-3p / IRF1 axis

Long non-coding RNA GAS5 promotes neuronal apoptosis in spinal cord injury via the miR-21/PTEN axis

BACKGROUND

Spinal cord injury (SCI) is a severe and permanent trauma that often leads to significant motor, sensory, and autonomic dysfunction. Neuronal apoptosis is a major pathomechanism underlying secondary injury in SCI. Long non-coding RNAs (lncRNAs) have emerged as key regulators of gene expression and cellular processes, including apoptosis. However, the role of lncRNA growth arrest-specific transcript 5 (GAS5) in SCI-induced neuronal apoptosis remains unclear.

AIM

To investigate the role of lncRNA GAS5 in SCI-induced neuronal apoptosis via its interaction with microRNA (miR)-21 and the phosphatase and tensin homolog (PTEN)/AKT pathway.

METHODS

SCI rat models and hypoxic neuronal cell models were established. Motor function was assessed using the Basso-Beattie-Bresnahan score. Expression levels of GAS5, miR-21, PTEN, caspase 3, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and AKT were measured using quantitative PCR or Western blot analysis. Neuronal apoptosis was determined by TUNEL staining. Dual-luciferase reporter assays validated GAS5-miR-21 binding. Knockdown and overexpression experiments explored the functional effects of the GAS5/miR-21 axis.

RESULTS

GAS5 was significantly upregulated in the spinal cord following SCI, coinciding with increased neuronal apoptosis and decreased AKT activation. In vitro experiments demonstrated that GAS5 acted as a molecular sponge for miR-21, leading to increased PTEN expression and inhibition of the AKT signaling pathway, thereby promoting apoptosis. In vivo, GAS5 knockdown attenuated neuronal apoptosis, enhanced AKT activation, and improved motor function recovery in SCI rats.

CONCLUSION

GAS5 promotes neuronal apoptosis in SCI by binding to miR-21 and upregulating PTEN expression, inhibiting the AKT pathway. Targeting GAS5 may represent a novel therapeutic strategy for SCI.

Role of lncRNA Xist-miR-124-CCL2 axis in HIV Tat-mediated microglial activation and neuroinflammation

Introduction

HIV proteins, such as the Transactivator of transcription (Tat), mediate neuroinflammation in the central nervous system by promoting the release of pro-inflammatory cytokines and chemokines. Long noncoding RNAs (lncRNAs) regulate gene expression by sponging microRNAs (miRs), but their role in HIV Tat-mediated microglial activation remains poorly understood. This study aimed to investigate the involvement of the lncRNA Xist-miR-124-CCL2 axis in HIV Tat-exposed microglial cells.

Methods

Mouse primary microglial cells were exposed to HIV Tat, and the expression of lncRNA Xist, miR-124, and CCL2 was evaluated using qPCR, Western blotting, and ELISA. Dual-luciferase reporter and Argonaute immunoprecipitation assays were used to confirm molecular interactions. Functional experiments involved lncRNA Xist silencing and miR-124 overexpression. In vivo validation was performed using doxycycline-inducible HIV Tat transgenic mice.

Results

HIV Tat significantly upregulated lncRNA Xist and downregulated miR-124 expression in mouse primary microglial cells. miR-124 was identified as a direct target of lncRNA Xist and the 3'-UTR of CCL2. Silencing lncRNA Xist or overexpressing miR-124 reduced HIV Tat-induced CCL2 expression and microglial activation. In vivo studies corroborated these findings, with doxycycline-fed iTat mice showing elevated lncRNA Xist and CCL2 levels and reduced miR-124 expression in the frontal cortex.

Discussion

Our findings identify a novel regulatory axis whereby HIV Tat-induced upregulation of lncRNA Xist sponges miR-124, leading to CCL2 overexpression and microglial activation. Targeting the lncRNA Xist-miR-124-CCL2 pathway may represent a promising therapeutic strategy to mitigate neuroinflammation associated with NeuroHIV.

Role of Long Non-Coding RNA X-Inactive-Specific Transcript (XIST) in Neuroinflammation and Myelination: Insights from Cerebral Organoids and Implications for Multiple Sclerosis

Background/Objectives: X-inactive-specific transcript (XIST) is a factor that plays a role in neuroinflammation. This study investigated the role of XIST in neuronal development, neuroinflammation, myelination, and therapeutic responses within cerebral organoids in the context of Multiple Sclerosis (MS) pathogenesis. Methods: Human cerebral organoids with oligodendrocytes were produced from XIST-silenced H9 cells, and the mature organoids were subsequently treated with either FTY720 or DMF. Gene expression related to inflammation and myelination was subsequently analyzed via qRT-PCR. Immunofluorescence staining was used to assess the expression of proteins related to inflammation, myelination, and neuronal differentiation. Alpha-synuclein protein levels were also checked via ELISA. Finally, transcriptome analysis was conducted on the organoid samples. Results: XIST-silenced organoids presented a 2-fold increase in the expression of neuronal stem cells, excitatory neurons, microglia, and mature oligodendrocyte markers. In addition, XIST silencing increased IL-10 mRNA expression by 2-fold and MBP and PLP1 expression by 2.3- and 0.6-fold, respectively. Although XIST silencing tripled IBA1 protein expression, it did not affect organoid MBP expression. FTY720, but not DMF, distinguished MBP and IBA1 expression in XIST-silenced organoids. Furthermore, XIST silencing reduced the concentration of alpha-synuclein from 300 to 100 pg/mL, confirming its anti-inflammatory role. Transcriptomic and gene enrichment analyses revealed that the differentially expressed genes are involved in neural development and immune processes, suggesting the role of XIST in neuroinflammation. The silencing of XIST modified the expression of genes associated with inflammation, myelination, and neuronal growth in cerebral organoids, indicating a potential involvement in the pathogenesis of MS. Conclusions: XIST may contribute to the MS pathogenesis as well as neuroinflammatory diseases such as and Alzheimer's and Parkinson's diseases and may be a promising therapeutic target.

LncRNAs Orchestrating Neuroinflammation: A Comprehensive Review

CNS diseases account for a major part of the comorbidity and mortality of the human population; moreover, neuroinflammation has become an indication for different CNS diseases, for instance, Parkinson's and Alzheimer's disease. Microglia and astrocytes are the two main glial cells that can be found in the CNS. Each of these plays an important role in mediating immune responses like inflammation. There are many studies suggesting the role of LncRNAs in mediating neuroinflammation. Indeed, LncRNAs orchestrate neuroinflammation through various mechanisms, namely miRNA sponge, and transcriptional activation/inhibition. In addition, LncRNAs regulate different downstream pathways like NF-κB, and PI3K/AKT. In this study, we gathered the existing studies regarding the mechanisms of action of LncRNAs in the pathogenesis of different CNS diseases like neurodegenerative diseases and traumatic injuries through regulating neuroinflammation. We aim to elaborate on the regulatory roles of LncRNAs in neuroinflammation and bring a more profound understanding of the etiology of CNS diseases in terms of neuroinflammation.

A potential function for MicroRNA-124 in normal and pathological bone conditions

Cells produce short single-stranded non-coding RNAs (ncRNAs) called microRNAs (miRNAs), which actively regulate gene expression at the posttranscriptional level. Several miRNAs have been observed to exert significant impacts on bone health and bone-related disorders. One of these, miR-124, is observed in bone microenvironments and is conserved across species. It affects bone cell growth and differentiation by activating different transcription factors and signaling pathways. In-depth functional analyses of miR-124 have revealed several physiological and pathological roles exerted through interactions with other ncRNAs. Deciphering these RNA-mediated signaling networks and pathways is essential for understanding the potential impacts of dysregulated miRNA functions on bone biology. In this review, we aim to provide a comprehensive analysis of miR-124's involvement in bone physiology and pathology. We highlight the importance of miR-124 in controlling transcription factors and signaling pathways that promote bone growth. This review reveals therapeutic implications for the treatment of bone-related diseases.

Conditioned culture medium of bone marrow mesenchymal stem cells promotes phenotypic transformation of microglia by regulating mitochondrial autophagy

Objective

To study the mechanism by which conditioned medium of bone marrow mesenchymal stem cells (BMSCs-CM) facilitates the transition of pro-inflammatory polarized microglia to an anti-inflammatory phenotype.

Methods

BV2 cells, a mouse microglia cell line, were transformed into a pro-inflammatory phenotype using lipopolysaccharide. The expression of phenotypic genes in BV2 cells was detected using real-time quantitative PCR (RT-qPCR). Enzyme-linked immunosorbent assay was used to measure inflammatory cytokine levels in BV2 cells co-cultured with BMSCs-CM. The expressions of mitophagy-associated proteins were determined using western blot. The mitochondrial membrane potential and ATP levels in BV2 cells were measured using JC-1 staining and an ATP assay kit, respectively. Additionally, we examined the proliferation, apoptosis, and migration of C8-D1A cells, a mouse astrocyte cell line, co-cultured with BV2 cells.

Results

After co- culture with BMSCs -CM, the mRNA expression of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase significantly decreased in pro-inflammatory BV2 cells, whereas the expression of CD206 and arginase-1 significantly increased. Moreover, TNF-α and interleukin-6 levels significantly decreased, whereas transforming growth factor-β and interleukin-10 levels significantly increased. Furthermore, co-culture with BMSCs-CM increased mitophagy-associated protein expression, ATP levels, mitochondrial and lysosomal co-localization in these cells and decreased reactive oxygen species levels. Importantly, BMSCs-CM reversed the decrease in the proliferation and migration of C8-D1A cells co-cultured with pro-inflammatory BV2 cells and inhibited the apoptosis of C8-D1A cells.

Conclusion

BMSCs-CM may promote the transition of polarized microglia from a pro-inflammatory to an anti-inflammatory phenotype by regulating mitophagy and influences the functional state of astrocytes.

Single-cell RNA sequencing reveals the evolution of the immune landscape during perihematomal edema progression after intracerebral hemorrhage

BACKGROUND

Perihematomal edema (PHE) after post-intracerebral hemorrhage (ICH) has complex pathophysiological mechanisms that are poorly understood. The complicated immune response in the post-ICH brain constitutes a crucial component of PHE pathophysiology. In this study, we aimed to characterize the transcriptional profiles of immune cell populations in human PHE tissue and explore the microscopic differences between different types of immune cells.

METHODS

9 patients with basal ganglia intracerebral hemorrhage (hematoma volume 50-100 ml) were enrolled in this study. A multi-stage profile was developed, comprising Group1 (n = 3, 0-6 h post-ICH, G1), Group2 (n = 3, 6-24 h post-ICH, G2), and Group3 (n = 3, 24-48 h post-ICH, G3). A minimal quantity of edematous tissue surrounding the hematoma was preserved during hematoma evacuation. Single cell RNA sequencing (scRNA-seq) was used to map immune cell populations within comprehensively resected PHE samples collected from patients at different stages after ICH.

RESULTS

We established, for the first time, a comprehensive landscape of diverse immune cell populations in human PHE tissue at a single-cell level. Our study identified 12 microglia subsets and 5 neutrophil subsets in human PHE tissue. What's more, we discovered that the secreted phosphoprotein-1 (SPP1) pathway served as the basis for self-communication between microglia subclusters during the progression of PHE. Additionally, we traced the trajectory branches of different neutrophil subtypes. Finally, we also demonstrated that microglia-produced osteopontin (OPN) could regulate the immune environment in PHE tissue by interacting with CD44-positive cells.

CONCLUSIONS

As a result of our research, we have gained valuable insight into the immune-microenvironment within PHE tissue, which could potentially be used to develop novel treatment modalities for ICH.

Neuroinflammation and Neurodegenerative Diseases: How Much Do We Still Not Know?

The term "neuroinflammation" defines the typical inflammatory response of the brain closely related to the onset of many neurodegenerative diseases (NDs). Neuroinflammation is well known, but its mechanisms and pathways are not entirely comprehended. Some progresses have been achieved through many efforts and research. Consequently, new cellular and molecular mechanisms, diverse and conventional, are emerging. In listing some of those that will be the subject of our description and discussion, essential are the important roles of peripheral and infiltrated monocytes and clonotypic cells, alterations in the gut-brain axis, dysregulation of the apelinergic system, alterations in the endothelial glycocalyx of the endothelial component of neuronal vascular units, variations in expression of some genes and levels of the encoding molecules by the action of microRNAs (miRNAs), or other epigenetic factors and distinctive transcriptional factors, as well as the role of autophagy, ferroptosis, sex differences, and modifications in the circadian cycle. Such mechanisms can add significantly to understanding the complex etiological puzzle of neuroinflammation and ND. In addition, they could represent biomarkers and targets of ND, which is increasing in the elderly.