MicroRNA signature of central nervous system-infiltrating dendritic cells in an animal model of multiple sclerosis

The role of miRNAs in multiple sclerosis pathogenesis, diagnosis, and therapeutic resistance

In recent years, microRNAs (miRNAs) have gained increased attention from researchers around the globe. Although it is twenty nucleotides long, it can modulate several gene targets simultaneously. Their mal expression is a signature of various pathologies, and they provide the foundation to elucidate the molecular mechanisms of each pathology. Among the debilitating central nervous system (CNS) disorders with a growing prevalence globally is the multiple sclerosis (MS). Moreover, the diagnosis of MS is challenging due to the lack of disease-specific biomarkers, and the diagnosis mainly depends on ruling out other disabilities. MS could adversely affect patients' lives through its progression, and only symptomatic treatments are available as therapeutic options, but an exact cure is yet unavailable. Consequently, this review hopes to further the study of the biological features of miRNAs in MS and explore their potential as a therapeutic target.

The role of non-coding RNAs in neuroinflammatory process in multiple sclerosis

Multiple sclerosis (MS) is a central nervous system chronic neuroinflammatory disease followed by neurodegeneration. The diagnosis is based on clinical presentation, cerebrospinal fluid testing and magnetic resonance imagining. There is still a lack of a diagnostic blood-based biomarker for MS. Due to the cost and difficulty of diagnosis, new and more easily accessible methods are being sought. New biomarkers should also allow for early diagnosis. Additionally, the treatment of MS should lead to the personalization of the therapy. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) as well as their target genes participate in pathophysiology processes in MS. Although the detailed mechanism of action of non-coding RNAs (ncRNAs, including miRNAs and lncRNAs) on neuroinflammation in MS has not been fully explained, several studies were conducted aiming to analyse their impact in MS. In this article, we review up-to-date knowledge on the latest research concerning the ncRNAs in MS and evaluate their role in neuroinflammation. We also point out the most promising ncRNAs which may be promising in MS as diagnostic and prognostic biomarkers.

MicroRNA-31-3p/RhoA signaling in the dorsal hippocampus modulates methamphetamine-induced conditioned place preference in mice

RATIONALE

MicroRNAs (miRNAs) regulate neuroplasticity-related proteins and are implicated in methamphetamine (METH) addiction. RhoA is a small Rho GTPase that regulates synaptic plasticity and addictive behaviors. Nevertheless, the functional relationship between RhoA and upstream miRNAs of METH addiction remains unclear.

OBJECTIVE

To explore the molecular biology and epigenetic mechanisms of the miR-31-3p/RhoA pathway in METH addiction.

METHODS

RhoA protein and its potential upstream regulator, miR-31-3p, were detected. A dual luciferase reporter was employed to determine whether RhoA constituted a specific target of miR-31-3p. Following adeno-associated virus (AAV)-mediated knockdown or overexpression of miR-31-3p or RhoA in the dorsal hippocampus (dHIP), mice were subjected to conditioned place preference (CPP) to investigate the effects of miR-31-3p and RhoA on METH-induced addictive behaviors.

RESULTS

RhoA protein was significantly decreased in the dHIP of CPP mice with a concomitant increase in miR-31-3p. RhoA was identified as a direct target of miR-31-3p. Knockdown of miR-31-3p in the dHIP was associated with increased RhoA protein and attenuation of METH-induced CPP. Conversely, overexpression of miR-31-3p was associated with decreased RhoA protein and enhancement of METH effects. Similarly, knockdown of RhoA in the dHIP enhanced METH-induced CPP, whereas RhoA overexpression attenuated the effects of METH. Parallel experiments using sucrose preference revealed that the effects of miR-31-3p/RhoA pathway modulation were specific to METH.

CONCLUSIONS

Our findings indicate that the miR-31-3p/RhoA pathway in the dHIP modulates METH-induced CPP in mice. Our results highlight the potential role of epigenetics represented by non-coding RNAs in the treatment of METH addiction.

Immunomodulatory Role and Therapeutic Potential of Non-Coding RNAs Mediated by Dendritic Cells in Autoimmune and Immune Tolerance-Related Diseases

Dendritic cells (DCs) are professional antigen-presenting cells that act as a bridge between innate immunity and adaptive immunity. After activation, DCs differentiate into subtypes with different functions, at which point they upregulate co-stimulatory molecules and produce various cytokines and chemokines. Activated DCs also process antigens for presentation to T cells and regulate the differentiation and function of T cells to modulate the immune state of the body. Non-coding RNAs, RNA transcripts that are unable to encode proteins, not only participate in the pathological mechanisms of autoimmune-related diseases but also regulate the function of immune cells in these diseases. Accumulating evidence suggests that dysregulation of non-coding RNAs contributes to DC differentiation, functions, and so on, consequently producing effects in various autoimmune diseases. In this review, we summarize the main non-coding RNAs (miRNAs, lncRNAs, circRNAs) that regulate DCs in pathological mechanisms and have tremendous potential to give rise to novel therapeutic targets and strategies for multiple autoimmune diseases and immune tolerance-related diseases.

Prediction of Single-Nucleotide Polymorphisms within microRNAs Binding Sites of Neuronal Genes Related to Multiple Sclerosis: A Preliminary Study

Background:

Different genetic variants, including the single-nucleotide polymorphisms (SNPs) present in microRNA recognition elements (MREs) within 3'UTR of genes, can affect miRNA-mediated gene regulation and susceptibility to a variety of human diseases such as multiple sclerosis (MS), a disease of the central nervous system. Since the expression of many genes associated with MS is controlled by microRNAs (miRNAs), the aim of this study was to analyze SNPs within miRNA binding sites of some neuronal genes associated with MS.

Materials and Methods:

Fifty-seven neuronal genes related to MS were achieved using dbGaP, DAVID, DisGeNET, and Oviddatabases. 3'UTR of candidate genes were assessed for SNPs, and miRNAs' target prediction databases were used for predicting miRNA binding sites.

Results:

Three hundred and eight SNPs (minor allele frequency >0.05) were identified in miRNA binding sites of 3'UTR of 44 genes. Among them, 42 SNPs in 22 genes had miRNA binding sites and miRNA prediction tools suggested 71 putative miRNAs binding sites on these genes. Moreover, in silico analysis predicted 22 MRE-modulating SNPs and 22 MRE-creating SNPs in the 3'UTR of these candidate genes.

Conclusions:

These candidate MRE-SNPs can alter miRNAs binding sites and mRNA gene regulation. Therefore, these genetic variants and miRNAs might be involved in MS susceptibility and pathogenesis and hence would be valuable for further functional verification investigation.

Therapeutic induction of tolerogenic dendritic cells via aryl hydrocarbon receptor signaling

Dendritic cells (DCs) are potent antigen-presenting cells (APCs), which sample the exogenous and endogenous cues to control adaptive immunity, balancing effector and regulatory components of the immune response. Multiple subsets of DCs, such as plasmacytoid and conventional DCs, have been defined based on specific phenotypic markers, functions and regulatory transcriptional programs. Tolerogenic DCs (tolDCs) have been functionally defined based on their ability to expand the regulatory T-cell compartment and suppress immune responses. However, it is still unclear whether tolDCs represent a homogeneous population, a specific DC subset and/or a heterogeneous collection of DC activation/maturation states. The ligand-activated transcription factor aryl hydrocarbon receptor (AHR) has been shown to control transcriptional programs associated to tolDCs. In this review, we discuss the role of AHR in the control of tolDCs, and also AHR-targeted approaches for the therapeutic induction of tolDCs in autoimmune diseases and allergy.

Metabolic needs of brain-infiltrating leukocytes and microglia in multiple sclerosis

Metabolism, the umbrella term for complex biochemical pathways that sustain the basic functions of life, has garnered attention in recent years for its role in immune activation. Indeed, metabolic pathways and their intricate and complex connections with immune mechanisms constitute a new area of immunology termed 'immunometabolism'. One highlight is the existence of a switch in the key metabolic programs in immune cells, which executes their effector functions. 'Metabolic reprogramming' is observed in conditions of both peripheral diseases as well as in neurodegenerative conditions associated with inflammation such as multiple sclerosis. Moreover metabolic reprogramming occurs for almost every immune cell type. Whether metabolic changes are cause or effect of immune activation, however, remains to be fully understood. Being central to cellular activation, metabolism has become very topical in terms of exploring therapeutic targets. This review covers the major metabolic programs in immune cells, discuss metabolites as regulators of immune cell functions, and consider metabolic enzymes or pathways as therapeutic targets using examples from multiple sclerosis and its animal models.

Oligodendrocyte-specific Argonaute profiling identifies microRNAs associated with experimental autoimmune encephalomyelitis

BACKGROUND

MicroRNAs (miRNAs) belong to a class of evolutionary conserved, non-coding small RNAs with regulatory functions on gene expression. They negatively affect the expression of target genes by promoting either RNA degradation or translational inhibition. In recent years, converging studies have identified miRNAs as key regulators of oligodendrocyte (OL) functions. OLs are the cells responsible for the formation and maintenance of myelin in the central nervous system (CNS) and represent a principal target of the autoimmune injury in multiple sclerosis (MS).

METHODS

MiRAP is a novel cell-specific miRNA affinity-purification technique which relies on genetically tagging Argonaut 2 (AGO2), an enzyme involved in miRNA processing. Here, we exploited miRAP potentiality to characterize OL-specific miRNA dynamics in the MS model experimental autoimmune encephalomyelitis (EAE).

RESULTS

We show that 20 miRNAs are differentially regulated in OLs upon transition from pre-symptomatic EAE stages to disease peak. Subsequent in vitro differentiation experiments demonstrated that a sub-group of them affects the OL maturation process, mediating either protective or detrimental signals. Lastly, transcriptome profiling highlighted the endocytosis, ferroptosis, and FoxO cascades as the pathways associated with miRNAs mediating or inhibiting OL maturation.

CONCLUSIONS

Altogether, our work supports a dual role for miRNAs in autoimmune demyelination. In particular, the enrichment in miRNAs mediating pro-myelinating signals suggests an active involvement of these non-coding RNAs in the homeostatic response toward neuroinflammatory injury.

microRNAs: key modulators of disease-modifying therapies in multiple sclerosis

There is a high level of heterogeneity in symptom manifestations and response to disease-modifying therapies (DMTs) in multiple sclerosis (MS), an immune-based neurodegenerative disease with ever-increasing prevalence in recent decades. Because of unknown aspects of the etiopathology of MS and mechanism of action of DMTs, the reason for this variability is undetermined, and much remains to be understood. Traditionally, physicians consider switching to other DMTs based on the exacerbation of symptoms and/or change in the results of magnetic resonance imaging and biochemical factors. Therefore, identifying biological treatment response markers that help us recognizing non-responders rapidly and subsequently choosing another DMTs is necessary. microRNAs (miRNAs) are micromanagers of gene expression which have been profiled in different samples of MS patients, highlighting their role in pathogenetic of MS. Recent studies have investigated expression profiling of miRNAs after treatment with DMTs to clarify possible DMTs-mediated mechanism and obtaining response to therapy biomarkers. In this review, we will discuss the modulation of miRNAs by DMTs in cells and pathways involved in MS.

CNS microRNA profiles: a database for cell type enriched microRNA expression across the mouse central nervous system

microRNAs are short, noncoding RNAs that can regulate hundreds of targets and thus shape the expression landscape of a cell. Similar to mRNA, they often exhibit cell type enriched expression and serve to reinforce cellular identity. In tissue with high cellular complexity, such as the central nervous system (CNS), it is difficult to attribute microRNA changes to a particular cell type. To facilitate interpretation of microRNA studies in these tissues, we used previously generated data to develop a publicly accessible and user-friendly database to enable exploration of cell type enriched microRNA expression. We provide illustrations of how this database can be utilized as a reference as well as for hypothesis generation. First, we suggest a putative role for miR-21 in the microglial spinal injury response. Second, we highlight data indicating that differential microRNA expression, specifically miR-326, may in part explain regional differences in inflammatory cells. Finally, we show that miR-383 expression is enriched in cortical glutamatergic neurons, suggesting a unique role in these cells. These examples illustrate the database’s utility in guiding research towards unstudied regulators in the CNS. This novel resource will aid future research into microRNA-based regulatory mechanisms responsible for cellular phenotypes within the CNS.

Environmental Influencers, MicroRNA, and Multiple Sclerosis

Multiple sclerosis (MS) is a complex neurological disorder characterized by an aberrant immune system that affects patients' quality of life. Several environmental factors have previously been proposed to associate with MS pathophysiology, including vitamin D deficiency, Epstein-Barr virus (EBV) infection, and cigarette smoking. These factors may influence cellular molecularity, interfering with cellular proliferation, differentiation, and apoptosis. This review argues that small noncoding RNA named microRNA (miRNA) influences these factors' mode of action. Dysregulation in the miRNAs network may deeply impact cellular hemostasis, thereby possibly resulting in MS pathogenicity. This article represents a literature review and an author's theory of how environmental factors may induce dysregulations in the miRNAs network, which could ultimately affect MS pathogenicity.

Differential Expression of miRNAs and Behavioral Change in the Cuprizone-Induced Demyelination Mouse Model

The demyelinating diseases of the central nervous system involve myelin abnormalities, oligodendrocyte damage, and consequent glia activation. Neurotoxicant cuprizone (CPZ) was used to establish a mouse model of demyelination. However, the effects of CPZ on microRNA (miRNA) expression and behavior have not been clearly reported. We analyzed the behavior of mice administered a diet containing 0.2% CPZ for 6 weeks, followed by 6 weeks of recovery. Rotarod analysis demonstrated that the treated group had poorer motor coordination than control animals. This effect was reversed after 6 weeks of CPZ withdrawal. Open-field tests showed that CPZ-treated mice exhibited significantly increased anxiety and decreased exploratory behavior. CPZ-induced demyelination was observed to be alleviated after 4 weeks of CPZ treatment, according to luxol fast blue (LFB) staining and myelin basic protein (MBP) expression. miRNA expression profiling showed that the expression of 240 miRNAs was significantly changed in CPZ-fed mice compared with controls. Furthermore, miR-155-5p and miR-20a-5p upregulations enhanced NgR induction through Smad 2 and Smad 4 suppression in demyelination. Taken together, our results demonstrate that CPZ-mediated demyelination induces behavioral deficits with apparent alterations in miRNA expression, suggesting that differences in miRNA expression in vivo may be new potential therapeutic targets for remyelination.

miR-126 suppresses neuronal apoptosis in rats after cardiopulmonary resuscitation via regulating p38MAPK

In this study, we aimed to evaluate the effect of microRNA-126 (miR-126) on neuronal apoptosis in cardiopulmonary resuscitation rats and to explore the related molecular mechanism. The expression of miR-126 in brain tissues of rats after cardiopulmonary resuscitation was measured by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR). The basic parameters of cardiopulmonary resuscitation were recorded by miR-126 mimic injection in rats after cardiopulmonary resuscitation. Hematoxylin-eosin staining was used to observe the pathological changes of hippocampus. Immunohistochemistry was used to observe the expression of p38 and caspase-3 protein. Furthermore, the expression of p38 mitogen-activated protein kinase (p38MAPK), Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase 1/2 (ERK1/2) in rat hippocampus was detected by RT-qPCR and Western blot. In order to confirm whether miR-126 takes part in the p38MAPK pathway in the hippocampus of rats after cardiopulmonary resuscitation, the p38MAPK pathway inhibitor (SB203580) and activator (anisomycin) were added. The results showed overexpression of miR-126 could significantly increase the neurological function score and improve the pathological morphology of hippocampus in rats after cardiopulmonary resuscitation. miR-126 overexpression also could reduce the neuronal apoptosis, p38, and caspase-3 expression in the hippocampus. Moreover, the p38MAPK and JNK expression was downregulated and ERK1/2 expression was upregulated after miR-126 mimic injection (p < 0.05). The results of inhibition of p38MAPK pathway were consistent with those of overexpression of miR-126 (p > 0.05). This study indicated miR-126 could significantly reduce neuronal apoptosis of hippocampus in rats after cardiopulmonary resuscitation, which might be involved in the regulation of p38MAPK pathway.

MicroRNA-135b alleviates MPP+-mediated Parkinson's disease in in vitro model through suppressing FoxO1-induced NLRP3 inflammasome and pyroptosis

The present study focused on the novel roles and the underlying mechanisms of miR-135b in pyroptosis of MPP⁺-induced Parkinson's disease (PD). We established an in vitro PD model induced by MPP⁺. Our results demonstrated miR-135b was lower while FoxO1 was inversely higher in MPP⁺-treated SH-SY5Y and PC-12 cells. Luciferase reporter assay showed FoxO1 was a downstream target of miR-135b. MiR-135b mimics suppressed MPP⁺-induced pyroptosis and the upregulation of TXNIP, NLRP3, Caspase-1, ASC, GSDMD^Nterm and IL-1β. Moreover, FoxO1 overexpression had no effect on miR-135b but reversed its own downregulation caused by miR-135b mimics. Meanwhile, overexpression of FoxO1 abolished the inhibitory effects of miR-135b on pyroptosis and reversed the downregulation of pyroptotic genes and LDH release. In summary, miR-135b played a protective role in Parkinson's disease via inhibiting pyroptosis by targeting FoxO1. MiR-135b might serve as a potential therapeutic target in the treatment of Parkinson's disease.

Epstein-Barr Virus and miRNAs: Partners in Crime in the Pathogenesis of Multiple Sclerosis?

MicroRNAs (miRNAs) are small non-coding RNAs that modulate gene expression post transcriptionally. In healthy individuals, miRNAs contribute to maintaining gene expression homeostasis. However, the level of miRNAs expressed is markedly altered in different diseases, including multiple sclerosis (MS). The impact of such changes is being investigated, and thought to shape the immune system into the inflammatory autoimmune phenotype. Much is yet to be learned about the contribution of miRNAs in the molecular pathology of MS. Epstein-Barr virus (EBV) infection is a major risk factor for the development of MS. EBV encodes more than 40 miRNAs, most of which have been studied in the context of EBV associated cancers. These viral miRNAs regulate genes involved in cell apoptosis, antigen presentation and recognition, as well as B cell transformation. If EBV infection contributes to the pathology of MS, it is plausible that EBV miRNAs may be involved. Unfortunately, there are limited studies addressing how EBV miRNAs are involved in the pathogenesis of MS. This review summarizes what has been reported regarding cellular and viral miRNA profiles in MS and proposes possible interactions between the two in the development of MS.

The miRNA Expression Profile of Experimental Autoimmune Encephalomyelitis Reveals Novel Potential Disease Biomarkers

Multiple sclerosis (MS) is a debilitating autoimmune disease affecting over 2.3 million people worldwide, and it is characterized by inflammation and demyelination of nerve cells. The currently available biomarkers for the diagnosis and management of MS have inherent limitations, therefore, additional new biomarkers are needed. We studied the microRNA (miRNA) profile of splenocytes of mice having experimental autoimmune encephalomyelitis (EAE), a model of human MS. A miRNA-microarray analysis revealed increased expression of nine miRNAs (let-7e, miR-23b, miR-31, miR-99b, miR-125a, miR-146b, miR-155, miR-193b, and miR-221) following EAE development. Interestingly, serum levels of miR-99b, miR-125a, and miR-146b were significantly higher in EAE mice compared to normal mice. Bioinformatics analysis revealed the experimentally validated as well as predicted gene targets of specific miRNAs that are important for disease progression in MS. Specifically, we observed inverse correlation in the levels of miR-99b versus LIF, and between miR-125a versus BDNF and LIF. Our results suggest that above-mentioned miRNAs may play a crucial role in the pathogenesis of MS, and that miR-99b, miR-125a, and miR-146b in particular may serve as useful biomarkers for disease activity.