Expression, regulation and function of microRNAs in multiple sclerosis

Altered expression of microRNAs and B lymphocytes during Natalizumab therapy in multiple sclerosis

MicroRNAs (miRNAs) are a family of non-translated small ribonucleic acids (RNAs) measuring 21–25 nucleotides in length that play various roles in multiple sclerosis (MS). By regulating gene expression via either mediating translational repression or cleavage of the target RNA, miRNAs can alter the expression of transcripts in different cells, such as B lymphocytes, also known as B cells. They are crucial in the pathogenesis of MS; however, they have not been extensively studied during the treatment of some drugs such as natalizumab (NTZ). NTZ is a humanized immunoglobulin G4 antibody antagonist for integrin alpha 4 (α4) used in the treatment of MS. The drug reduces the homing of lymphocytes to inflammation sites. Integrin α4 expression on the cell surface of B cells is related to MS severity, indicating a critical component in the pathogenesis of the disease. NTZ plays an important role in modifying the gene expression in B cells and the levels of miRNAs in the treatment of MS. In this review, we have described changes in gene expression in B cells and the levels of miRNAs during NTZ therapy in MS and its relapse. Studies using the experimental autoimmune encephalomyelitis (EAE) model and those involving patients with MS have described changes in the levels of microRNAs in the regulation of proteins affected by specific miRNAs, gene expression in B cells, and certain functions of B cells as well as their subpopulations. Therefore, there is a possibility that some miRNAs could be studied at different stages of MS during NTZ treatment, and these specific miRNAs can be tested as markers of therapeutic response to this drug in future studies. Physiopathology, gene expression in B cells and their subpopulations can help understand this complex puzzle involving miRNAs and the therapeutic response of patients with MS.

Can altered colostrum miRNA expression profile after cesarean delivery be a risk factor for autoimmune diseases?

PROBLEM

The cesarean section (CS) rate has increased significantly in North America, Western Europe, and Latin America. However, it has been reported that the incidence of inflammatory and autoimmune diseases such as asthma and type 1 diabetes increased in parallel with CS in these countries. Our aim was to investigate the expression level of miRNAs associated with inflammatory response and autoimmune diseases in colostrum samples and contribute to elucidating the role of CS in the pathogenesis of immune system-related diseases.

METHOD OF STUDY

Colostrum samples were taken from voluntary mothers who had 40 normal and 50 cesarean births. miRNAs were extracted from colostrums and detected to miRNA expression profiling (eighty-four miRNAs) by quantitative real-time PCR with the Fluidigm integrated microfluidic circuit technology.

RESULTS

There was a statistically significant change in the expression levels of 17 miRNAs in the colostrums of mothers who had normal and cesarean delivery (p < .05), and all of miRNAs were upregulated in the colostrums of mothers who have had cesarean delivery.

CONCLUSION

Our best knowledge is that the study we conducted was the first to investigate the effect of delivery method (CS or normal) on the miRNA profile of colostrum. Cesarean delivery is a potential risk factor for inflammatory and immune system-related diseases in children due to dysregulation in miRNA expression.

Multiple sclerosis is linked to MAPKERK overactivity in microglia

Reassessment of published observations in patients with multiple sclerosis (MS) suggests a microglial malfunction due to inappropriate (over)activity of the mitogen-activated protein kinase pathway ERK (MAPK^ERK). These observations regard biochemistry as well as epigenetics, and all indicate involvement of this pathway. Recent preclinical research on neurodegeneration already pointed towards a role of MAPK pathways, in particular MAPK^ERK. This is important as microglia with overactive MAPK have been identified to disturb local oligodendrocytes which can lead to locoregional demyelination, hallmark of MS. This constitutes a new concept on pathophysiology of MS, besides the prevailing view, i.e., autoimmunity. Acknowledged risk factors for MS, such as EBV infection, hypovitaminosis D, and smoking, all downregulate MAPK^ERK negative feedback phosphatases that normally regulate MAPK^ERK activity. Consequently, these factors may contribute to inappropriate MAPK^ERK overactivity, and thereby to neurodegeneration. Also, MAPK^ERK overactivity in microglia, as a factor in the pathophysiology of MS, could explain ongoing neurodegeneration in MS patients despite optimized immunosuppressive or immunomodulatory treatment. Currently, for these patients with progressive disease, no effective treatment exists. In such refractory MS, targeting the cause of overactive MAPK^ERK in microglia merits further investigation as this phenomenon may imply a novel treatment approach.

miR-155 as an Important Regulator of Multiple Sclerosis Pathogenesis. A Review

Multiple sclerosis (MS) is a chronic, immune-mediated disease and the leading cause of disability among young adults. MicroRNAs (miRNAs) are involved in the post-transcriptional regulation of gene expression. Of them, miR-155 is a crucial regulator of inflammation and plays a role in modulating the autoimmune response in MS. miR-155 is involved in blood–brain barrier (BBB) disruption via down-regulation of key junctional proteins under inflammatory conditions. It drives demyelination processes by contributing to, e.g., microglial activation, polarization of astrocytes, and down-regulation of CD47 protein and affecting crucial transcription factors. miR-155 has a huge impact on the development of neuropathic pain and indirectly influences a regulatory T (Treg) cell differentiation involved in the alleviation of pain hypersensitivity. This review also focused on neuropsychiatric symptoms appearing as a result of disease-associated stressors, brain atrophy, and pro-inflammatory factors. Recent studies revealed the role of miR-155 in regulating anxiety, stress, inflammation in the hippocampus, and treatment-resistant depression. Inhibition of miR-155 expression was demonstrated to be effective in preventing processes involved in the pathophysiology of MS. This review aimed to support the better understanding the great role of miR-155 dysregulation in various aspects of MS pathophysiology and highlight future perspectives for this molecule.

Downregulation of miR-125a-5p and miR-218-5p in Peripheral Blood Mononuclear Cells of Patients with Relapsing-Remitting Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the brain and spinal cord. Evidences have demonstrated that microRNAs (miRNAs) are involved in the pathological process of MS that may confer a valuable diagnostic biomarker for disease diagnosis, prognosis, and treatment. Hence, we assessed the expression pattern of miR-125a-5p and miR-218-5p in the peripheral blood mononuclear cells (PBMCs) of subjects with relapsing-remitting multiple sclerosis (RRMS). We recruited 50 RRMS patients and 50 age- and sex-matched healthy control subjects. PBMCs were isolated from the peripheral blood samples, RNA content was extracted, cDNA was synthesized, and finally expression level of miRNAs was determined using quantitative real-time PCR. Our data indicate significant downregulation of both miR-125a-5p and miR-218-5p in RRMS patients compared to healthy controls (P< .0001). The levels of both miRNAs were significantly downregulated in an age-dependent manner compared with consistent healthy control groups (30-40 years old P< .0001). Expression level of miR-218-5p was significantly changed in only female patients (Female group P< .0001; Male group P= .12). Receiver operating characteristic (ROC) curve data indicated that the expression levels of both miRNAs were able to discriminate RRMS patients from healthy subjects (P< .05). Moreover, bioinformatic enrichment analysis revealed that the target genes of these miRNAs had cardinal roles in the regulation of key biological pathways involved in the clinical course and pathogenesis of MS. Collectively, our results suggested that miR-125a-5p and miR-218-5p play a role in RRMS pathogenesis and have an age- and sex-dependent expression pattern in these patients.

IgGs-Abzymes from the Sera of Patients with Multiple Sclerosis Recognize and Hydrolyze miRNAs

Autoantibodies-abzymes hydrolyzing DNA, myelin basic protein, and oligosaccharides have been revealed in the sera of patients with multiple sclerosis (MS). In MS, specific microRNAs are found in blood and cerebrospinal fluid, which are characterized by increased expression. Autoantibodies, specifically hydrolyzing four different miRNAs, were first detected in the blood of schizophrenia patients. Here, we present the first evidence that 23 IgG antibodies of MS patients effectively recognize and hydrolyze four neuroregulatory miRNAs (miR-137, miR-9-5p, miR-219-2-3p, and miR-219-5p) and four immunoregulatory miRNAs (miR-21-3p, miR-146a-3p, miR-155-5p, and miR-326). Several known criteria were checked to show that the recognition and hydrolysis of miRNAs is an intrinsic property of MS IgGs. The hydrolysis of all miRNAs is mostly site-specific. The major and moderate sites of the hydrolysis of each miRNA for most of the IgG preparations coincided; however, some of them showed other specific sites of splitting. Several individual IgGs hydrolyzed some miRNAs almost nonspecifically at nearly all internucleoside bonds or demonstrated a combination of site-specific and nonspecific splitting. Maximum average relative activity (RA) was observed in the hydrolysis of miR-155-5p for IgGs of patients of two types of MS-clinically isolated syndrome and relapsing-remitting MS-but was also high for patients with primary progressive and secondary progressive MS. Differences between RAs of IgGs of four groups of MS patients and healthy donors were statistically significant (p < 0.015). There was a tendency of decreasing efficiency of hydrolysis of all eight miRNAs during remission compared with the exacerbation of the disease.

MicroRNA in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS). Despite a complex pathogenesis, it appears that an imbalanced immune system plays an important role in the disease process. MicroRNAs (miRNAs) are comprised of short non-coding single-stranded molecules mainly involved in regulating gene expression through the inhibition of transcription and translation. miRNAs are key regulatory molecules in the nucleus and participate in the proliferation, differentiation, and apoptosis of various cells throughout the body. Recent studies, however, have found that miRNAs are also involved in MS pathogenesis, mainly affecting glial cells and peripheral immune cells. Fortunately, miRNAs are highly stable and have high specificity in peripheral body fluids. Accordingly, these molecules have become new diagnostic and therapeutic targets. The present review discusses the role of miRNAs in the pathogenesis of MS. We highlight the potential of miRNAs as new biomarkers of MS and potential therapeutic agents.

Identification of hsa-miR-106a-5p as an impact agent on promotion of multiple sclerosis using multi-step data analysis

Multiple sclerosis (MS) is a chronic, demyelinating disease in which the neuron myelin sheath is disrupted and leading to signal transductions disabilities. The evidence demonstrated that gene expression patterns and their related regulating factors are the most critical agents in MS demyelinating process. A miRNA is a small non-coding RNA which functions in post-transcriptional regulation of gene expression. Identification of specific miRNA dysregulation patterns in MS blood samples compared to healthy control can be used as a diagnostic and prognostic agent. Through the literature review and bioinformatics analysis, it was found that the hsa-miR-106a-5p can be considered a significant MS pathogenic factor, which seems has an abnormal expression pattern in patients' blood. Experimental validation using real-time PCR assay was carried to verifying the miR-106a-5p expression in MS and healthy control blood samples. The obtained results proved the miR-106a dysregulation in MS patients. The expression levels of miR-106a-5p were significantly downregulated (log 2 fold change = - 1.15) in patient blood samples compared to controls (p = 0.055). Our study suggested that miR-106a-5p may have a biomarker potential to the diagnosis of MS patients based on its dysregulation patterns.

Biomarkers in Rare Demyelinating Disease of the Central Nervous System

Rare neurological diseases are a heterogeneous group corresponding approximately to 50% of all rare diseases. Neurologists are among the main specialists involved in their diagnostic investigation. At the moment, a consensus guideline on which neurologists may base clinical suspicion is not available. Moreover, neurologists need guidance with respect to screening investigations that may be performed. In this respect, biomarker research has emerged as a particularly active field due to its potential applications in clinical practice. With respect to autoimmune demyelinating diseases of the Central Nervous System (CNS), although these diseases occur in the frame of organ-specific autoimmunity, pathology of the disease itself is orchestrated among several anatomical and functional compartments. The differential diagnosis is broad and includes, but is not limited to, rare neurological diseases. Multiple Sclerosis (MS) needs to be differentially diagnosed from rare MS variants, Acute Disseminated Encephalomyelitis (ADEM), the range of Neuromyelitis Optica Spectrum Disorders (NMOSDs), Myelin Oligodendrocyte Glycoprotein (MOG) antibody disease and other systemic inflammatory diseases. Diagnostic biomarkers may facilitate timely diagnosis and proper disease management, preventing disease exacerbation due to misdiagnosis and false treatment. In this review, we will describe advances in biomarker research with respect to rare neuroinflammatory disease of the CNS.

A hypothesis-generating scoping review of miRs identified in both multiple sclerosis and dementia, their protein targets, and miR signaling pathways

Cognitive impairment (CI) is a frequent complication affecting people with multiple sclerosis (MS). The causes of CI in MS are not fully understood. Besides MRI measures, few other biomarkers exist to help us predict the development of CI and understand its biology. MicroRNAs (miRs) are relatively stable, non-coding RNA molecules about 22 nucleotides in length that can serve as biomarkers and possible therapeutic targets in several autoimmune and neurodegenerative diseases, including the dementias. In this review, we identify dysregulated miRs in MS that overlap with dysregulated miRs in cognitive disorders and dementia and explore how these overlapping miRs play a role in CI in MS. MiR-15, miR-21, miR-128, miR-132, miR-138, miR-142, miR-146a, miR-155, miR-181, miR-572, and let-7 are known to contribute to various forms of dementia and show abnormal expression in MS. These overlapping miRs are involved in pathways related to apoptosis, neuroinflammation, glutamate toxicity, astrocyte activation, microglial burst activity, synaptic dysfunction, and remyelination. The mechanisms of action suggest that these miRs may be related to CI in MS. From our review, we also delineated miRs that could be neuroprotective in MS, namely miR-23a, miR-219, miR-214, and miR-22. Further studies can help clarify if these miRs are responsible for CI in MS, leading to potential therapeutic targets.

Immune and microRNA responses to Helicobacter muridarum infection and indole-3-carbinol during colitis

BACKGROUND

Indole-3-carbinol (I3C) and other aryl hydrocarbon receptor agonists are known to modulate the immune system and ameliorate various inflammatory and autoimmune diseases in animal models, including colitis induced by dextran sulfate sodium (DSS). MicroRNAs (miRNAs) are also gaining traction as potential therapeutic agents or diagnostic elements. Enterohepatic Helicobacter (EHH) species are associated with an increased risk of inflammatory bowel disease, but little is known about how these species affect the immune system or response to treatment.

AIM

To determine whether infection with an EHH species alters the response to I3C and how the immune and miRNA responses of an EHH species compare with responses to DSS and inflammatory bowel disease.

METHODS

We infected C57BL/6 mice with Helicobacter muridarum (H. muridarum), with and without DSS and I3C treatment. Pathological responses were evaluated by histological examination, symptom scores, and cytokine responses. MiRNAs analysis was performed on mesenteric lymph nodes to further evaluate the regional immune response.

RESULTS

H. muridarum infection alone caused colonic inflammation and upregulated proinflammatory, macrophage-associated cytokines in the colon similar to changes seen in DSS-treated mice. Further upregulation occurred upon treatment with DSS. H. muridarum infection caused broad changes in mesenteric lymph node miRNA expression, but colitis-associated miRNAs were regulated similarly in H. muridarum-infected and uninfected, DSS-treated mice. In spite of causing colitis exacerbation, H. muridarum infection did not prevent disease amelioration by I3C. I3C normalized both macrophage- and T cell-associated cytokines.

CONCLUSION

Thus, I3C may be useful for inflammatory bowel disease patients regardless of EHH infection. The miRNA changes associated with I3C treatment are likely the result of, rather than the cause of immune response changes.

Serum miRNAs Are Pharmacodynamic Biomarkers Associated With Therapeutic Response in Pediatric Inflammatory Bowel Disease

BACKGROUND

We sought to identify microRNAs (miRNAs) associated with response to anti-TNF-α or glucocorticoids in children with inflammatory bowel disease (IBD) to generate candidate pharmacodynamic and monitoring biomarkers.

METHODS

Clinical response was assessed by Pediatric Crohn's Disease Activity Index and Pediatric Ulcerative Colitis Activity Index. Quantitative real-time polymerase chain reaction via Taqman Low-Density Array cards were used to identify miRNAs in a discovery cohort of responders (n = 11) and nonresponders (n = 8). Seven serum miRNAs associated with clinical response to treatment, along with 4 previously identified (miR-146a, miR-146b, miR-320a, miR-486), were selected for further study. Candidates were assessed in a validation cohort of serum samples from IBD patients pre- and post-treatment and from healthy controls. Expression of miRNA was also analyzed in inflamed mucosal biopsies from IBD patients and non-IBD controls.

RESULTS

Discovery cohort analysis identified 7 miRNAs associated with therapeutic response: 5 that decreased (miR-126, miR-454, miR-26b, miR-26a, let-7c) and 2 that increased (miR-636, miR-193b). In the validation cohort, 7 of 11 candidate miRNAs changed in the same direction with response to anti-TNF-α therapies, glucocorticoids, or both. In mucosal biopsies, 7 out of 11 miRNAs were significantly increased in IBD vs healthy controls.

CONCLUSIONS

Five candidate miRNAs associated with clinical response and mucosal inflammation in pediatric IBD patients were identified (miR-126, let-7c, miR-146a, miR-146b, and miR-320a). These miRNAs may be further developed as pharmacodynamic and response monitoring biomarkers for use in clinical care and trials.

The Effect of Sialic Acid on the Expression of miR-218, NF-kB, MMP-9, and TIMP-1

Sialic acid (N-acetylneuraminic acid, NANA) is found at all cell surfaces of vertebrates. Although it is widely accepted that sialic acid is an essential substrate for brain development via a significant role in nerve transfers, structure of glycosides, and synaptogenesis phenomena, there are some reports on the elevated levels of sialic acid and prevalence of neurodegeneration. Matrix metalloproteases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) are involved in neuroinflammation disorders and produced by many cell types, including activated T cells, macrophages, neurons, astrocytes, and microglial cells. It can be hypothesized that sialic acid may have a potentially critical role in regulation of a wide range of uncovered neurodegeneration factors as its downstream targets. In this study, for the first time, we aimed to analyze the possible effect of the sialic acid solution exposure in the human C118 cell line, which was derived from a human brain astrocytoma (glial cells), on the expression patterns of miR-218, NF-kB, MMP-9, and TIMP-1. For MMP-9, protein levels were studied too. Half maximal inhibitory concentration (IC₅₀) value of NANA was obtained by MTT assay. Glial cell line was treated with sialic acid (300, 500, and 1000 µg/ml) for 24 h to investigate the effects of this ligand on the expression of miR-218, NF-kB, MMP-9, and TIMP-1 genes. Protein levels were checked by Western blotting, and by using zymography, the gelatinolytic activity of MMP-9 secreted into conditioned media was assayed. At 300 µM, 500 µM, and 1000 µM sialic acid treatments, the expression of miR-218 was downregulated; subsequently, the NF-kB, MMP-9, and TIMP-1 genes as well as their protein expressions were upregulated. More interestingly, the enzyme activity of secreted MMP-9 was upregulated too (p-values ≤ 0.05). This study could demonstrate the significant effect of sialic acid on miR-218, NF-kB, MMP-9 , and TIMP-1 expressions in gene and protein levels and also the levels of enzyme activity of secreted MMP-9. Therefore, provided information indicates the novel idea of a possible linkage between sialic acid species and regulation of these neuroinflammation genes in Glial cell line.

A miRNA-Based Blood and Mucosal Approach for Detecting and Monitoring Celiac Disease

BACKGROUND

The role of microRNAs (miRNAs) in celiac disease (CD) is unclear.

AIMS

We evaluated inflammation-related miRNA-146a, miRNA-155, miRNA-21, and miRNA-125b expression in peripheral blood and intestinal mucosa of CD adults.

METHODS

Thirty patients with CD were included: patients with active CD on a gluten-containing diet (CD-active, n = 10), patients on a gluten-free diet (for at least 1 year), and patients with negative blood antibodies (CD-inactive^PE, n = 10). In addition, ten healthy volunteers formed the comparison/control group. MiRNA expression was measured in duodenal biopsies from patients (CD-inactive^MU, n = 10) after in vitro exposure to PT gliadin and 33-mer peptide. MiRNAs expression was measured in plasma and in peripheral blood mononuclear cells (PBMCs) and monocytes, before and after in vitro exposure to native gliadin (gliadin^N).

RESULTS

Expression levels of miRNA-146a, miRNA-155, and miRNA-21 in PBMCs, miRNA-155 in monocytes and miRNA-155, miRNA-21, and miRNA-125b in plasma were elevated in both groups of celiac patients. After in vitro exposure with gliadin^N, miRNA-146a and miRNA-155 expression markedly increased in PBMCs and monocytes, while miRNA-155 and miRNA-21 increased in the CD-active group. MiRNAs expression in intestinal mucosa did not change. MiRNA-146a and miRNA-155 expression showed high sensitivity and specificity for the presence of CD, irrespective of the current dietary treatment.

CONCLUSIONS

Selected inflammation-related miRNAs expression is elevated in the peripheral blood of celiac. This suggests their participation in the immune processes underlying the pathology. Their similar response in active and inactive CD suggests that they should be further evaluated, as potential diagnostic biomarkers for CD.

Early diagnosis of secondary progressive multiple sclerosis: focus on fluid and neurophysiological biomarkers

BACKGROUND AND AIMS

Most patients with multiple sclerosis presenting with a relapsing-remitting disease course at diagnosis transition to secondary progressive multiple sclerosis (SPMS) 1-2 decades after onset. SPMS is characterized by predominant neurodegeneration and atrophy. These pathogenic hallmarks result in unsatisfactory treatment response in SPMS patients. Therefore, early diagnosis of SPMS is necessary for prompt treatment decisions. The aim of this review was to assess neurophysiological and fluid biomarkers that have the potential to monitor disease progression and support early SPMS diagnosis.

METHODS

We performed a systematic review of studies that analyzed the role of neurophysiological techniques and fluid biomarkers in supporting SPMS diagnosis using the preferred reporting items for systematic reviews and meta-analyses statement.

RESULTS

From our initial search, we selected 24 relevant articles on neurophysiological biomarkers and 55 articles on fluid biomarkers.

CONCLUSION

To date, no neurophysiological or fluid biomarker is sufficiently validated to support the early diagnosis of SPMS. Neurophysiological measurements, including short interval intracortical inhibition and somatosensory temporal discrimination threshold, and the neurofilament light chain fluid biomarker seem to be the most promising. Cross-sectional studies on an adequate number of patients followed by longitudinal studies are needed to confirm the diagnostic and prognostic value of these biomarkers. A combination of neurophysiological and fluid biomarkers may be more sensitive in detecting SPMS conversion.

Muscle Weakness in Myositis: MicroRNA-Mediated Dystrophin Reduction in a Myositis Mouse Model and Human Muscle Biopsies

Objective

Muscle inflammation is a feature in myositis and Duchenne muscular dystrophy (DMD). Autoimmune mechanisms are thought to contribute to muscle weakness in patients with myositis. However, a lack of correlation between the extent of inflammatory cell infiltration and muscle weakness indicates that nonimmune pathologic mechanisms may play a role. The present study focused on 2 microRNA (miRNA) sets previously identified as being elevated in the muscle of patients with DMD—an “inflammatory” miRNA set that is dampened with glucocorticoids, and a “dystrophin‐targeting” miRNA set that inhibits dystrophin translation—to test the hypothesis that these miRNAs are similarly dysregulated in the muscle of patients with myositis, and could contribute to muscle weakness and disease severity.

Methods

A major histocompatibility complex class I–transgenic mouse model of myositis was utilized to study gene and miRNA expression and histologic features in the muscle tissue, with the findings validated in human muscle biopsy tissue from 6 patients with myositis. Mice were classified as having mild or severe myositis based on transgene expression, body weight, histologic disease severity, and muscle strength/weakness.

Results

In mice with severe myositis, muscle tissue showed mononuclear cell infiltration along with elevated expression of type I interferon and NF‐κB–regulated genes, including Tlr7 (3.8‐fold increase, P < 0.05). Furthermore, mice with severe myositis showed elevated expression of inflammatory miRNAs (miR‐146a, miR‐142‐3p, miR‐142‐5p, miR‐455‐3p, and miR‐455‐5p; ~3–40‐fold increase, P < 0.05) and dystrophin‐targeting miRNAs (miR‐146a, miR‐146b, miR‐31, and miR‐223; ~3–38‐fold increase, P < 0.05). Bioinformatics analyses of chromatin immunoprecipitation sequencing (ChIP‐seq) data identified at least one NF‐κB consensus element within the promoter/enhancer regions of these miRNAs. Western blotting and immunofluorescence analyses of the muscle tissue from mice with severe myositis demonstrated reduced levels of dystrophin. In addition, elevated levels of NF‐κB–regulated genes, TLR7, and miRNAs along with reduced dystrophin levels were observed in muscle biopsy tissue from patients with histologically severe myositis.

Conclusion

These data demonstrate that an acquired dystrophin deficiency may occur through NF‐κB–regulated miRNAs in myositis, thereby suggesting a unifying theme in which muscle injury, inflammation, and weakness are perpetuated both in myositis and in DMD.

Investigation of the miRNA146a and miRNA155 gene expression levels in patients with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease and the most common neurodegenerative status. MicroRNAs play an important role in macrophage response to inflammatory processes, and alterations in miRNA levels trigger the inactivation of specific T lymphocytes. As a result, these factors can lead to autoimmune diseases such as MS. Therefore, to determine the role of MicroRNA-146a and MicroRNA-155 in MS patients, their expression levels in serum of MS patients were compared with healthy controls. In this study, the expression levels of MicroRNA-146a and MicroRNA-155 in 30 serum samples of MS and healthy patients as a control group. MicroRNA extraction and cDNA synthesis was performed according manufacture protocols. The expression levels of MicroRNAs were evaluated by Real Time-PCR. MicroRNA-146a and MicroRNA-155 levels were increased in patients with MS compared to controls. The results demonstrated that EDSS score are increased with increasing level of MicroRNA-146a and MicroRNA-155. ROC curve analysis showed that the area under curve (AUC) was significant for MicroRNA-146a and MicroRNA-155. Increased expression levels of MicroRNA-146a and MicroRNA-155 may be associated with the pathogenesis of MS disease. If this study is conducted in a larger sample population and the above results can be used to identify patients or control patients who are under medical care.

Alcohol and multiple sclerosis: an immune system-based review

Multiple sclerosis is a chronic inflammatory disease of the central nervous system (CNS). Although the exact etiology of multiple sclerosis is unknown, researchers suggest that genetic, environmental, and microbial factors play a central role in causing multiple sclerosis. Pathology of multiple sclerosis is based on inflammation as T cells enter the brain via disruptions in the blood-brain barrier, recognizing myelin as foreign antigen; and as a result, the T cells attack myelin and start the inflammatory processes, enhancing inflammatory cytokines and antibodies. Since previous studies show ethanol can suppress the immune system such as innate, humoral, and cellular immunity and increases the production of anti-inflammatory cytokines, we hypothesized maybe ethanol also have ameliorating effects on multiple sclerosis symptoms. Although alcohol induces apoptosis in oligodendrocytes and neurons, causing demyelination and affects CNS directly, in this study we will investigate ethanol's effects on some aspects of the immune system in multiple sclerosis.

A genetic variant of pri-miR-182 may impact the risk for the onset of multiple sclerosis in the Iranian population

BACKGROUND

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system affecting young adults. SNPs can be used as genetic biomarkers to identify disease-related genes such as MS. Moreover, SNPs can be considered as important determinants for an increased risk of autoimmune diseases such as MS. Studies have shown that miR-182 is of importance in Treg cell development and function as critical regulators in autoimmune disease. So far, no study has been conducted to investigate the association between rs4541843 polymorphism in pri-miR-182 and MS. In the present study, we assessed the frequency of rs4541843 different alleles and genotypes and their association with MS risk in Iranian population.

METHODS

The rs4541843 was genotyped in 81 patients with MS and 89 healthy subjects, using the PCR-RFLP method. The frequency of alleles and genotypes and the association of this polymorphism with MS risk and the gender of the patients was then statistically analyzed.

RESULTS

Statistical analysis showed the protective role of AA genotype against MS risk (P = .031, OR = 0.348) while there was no significance correlation between the frequency of rs4541843 different alleles and the other genotypes.

CONCLUSION

Our findings illustrated that the pri-miR-182 rs4541843 G>A polymorphism is associated with the risk of MS in Isfahan population. However, additional large-scale association studies in various ethnicities and more molecular studies are necessary to elaborate our findings.

miR-146a in Myasthenia Gravis Thymus Bridges Innate Immunity With Autoimmunity and Is Linked to Therapeutic Effects of Corticosteroids

Toll-like receptor (TLR)-mediated innate immune responses are critically involved in the pathogenesis of myasthenia gravis (MG), an autoimmune disorder affecting neuromuscular junction mainly mediated by antiacetylcholine receptor antibodies. Considerable evidence indicate that uncontrolled TLR activation and chronic inflammation significantly contribute to hyperplastic changes and germinal center (GC) formation in the MG thymus, ultimately leading to autoantibody production and autoimmunity. miR-146a is a key modulator of innate immunity, whose dysregulation has been associated with autoimmune diseases. It acts as inhibitor of TLR pathways, mainly by targeting the nuclear factor kappa B (NF-κB) signaling transducers, interleukin 1 receptor associated kinase 1 (IRAK1) and tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6); miR-146a is also able to target c-REL, inducible T-cell costimulator (ICOS), and Fas cell surface death receptor (FAS), known to regulate B-cell function and GC response. Herein, we investigated the miR-146a contribution to the intrathymic MG pathogenesis. By real-time PCR, we found that miR-146a expression was significantly downregulated in hyperplastic MG compared to control thymuses; contrariwise, IRAK1, TRAF6, c-REL, and ICOS messenger RNA (mRNA) levels were upregulated and negatively correlated with miR-146a levels. Microdissection experiments revealed that miR-146a deficiency in hyperplastic MG thymuses was not due to GCs, but restricted to the GC-surrounding medulla, characterized by IRAK1 overexpression. We also showed higher c-REL and ICOS mRNA levels, and lower FAS mRNA levels, in GCs than in the remaining medulla, according to the contribution of these molecules in GC formation. By double immunofluorescence, an increased proportion of IRAK1-expressing dendritic cells and macrophages was found in hyperplastic MG compared to control thymuses, along with GC immunoreactivity for c-REL. Interestingly, in corticosteroid-treated MG patients intrathymic miR-146a and mRNA target levels were comparable to those of controls, suggesting that immunosuppressive therapy may restore the microRNA (miRNA) levels. Indeed, an effect of prednisone on miR-146a expression was demonstrated in vitro on peripheral blood cells. Serum miR-146a levels were lower in MG patients compared to controls, indicating dysregulation of the circulating miRNA. Our overall findings strongly suggest that defective miR-146a expression could contribute to persistent TLR activation, lack of inflammation resolution, and hyperplastic changes in MG thymuses, thus linking TLR-mediated innate immunity to B-cell-mediated autoimmunity. Furthermore, they unraveled a new mechanism of action of corticosteroids in inducing control of autoimmunity in MG via miR-146a.

Identification of differentially expressed miRNAs and mRNAs in synovial of osteoarthritis via RNA-sequencing

Background

Osteoarthritis (OA) is the most common form of arthritis and a leading cause of disability. This study attempted to investigate the key mRNAs and miRNAs related to OA.

Patients and methods

From April 17th, 2018 to May 17th, 2018, five patients with OA and three normal controls were enrolled in this present study. To identify the differentially expressed mRNAs (DEmRNAs) and miRNAs (DEmiRNAs) between patients with OA and normal controls, RNA-sequencing was performed. Then, DEmiRNA-target DEmRNAs analysis and functional annotation of DEmiRNA-target DEmRNAs were performed. To validate the RNA-sequencing results, quantitative real time-PCR (RT-PCR) and western blot analysis were performed as well.

Results

A total of 1068 DEmRNAs, 21 DEmiRNAs and 395 DEmiRNA-DEmRNA pairs were identified in synovial tissues of patients with OA. The functional annotation of DEmiRNA-target DEmRNAs revealed that Pathways in cancer and PI3K-Akt signaling pathway were significantly enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. QRT-PCR and western blot results revealed that except for TLR7, the expression level of the others was consistent with the RNA-sequencing results, generally.

Conclusion

The findings of this present study may provide new clues for the roles of DEmRNAs and DEmiRNAs in the pathogenesis of OA.

Circulating exosomal microRNAs in bipolar disorder

INTRODUCTION

Emerging evidence suggests central roles of miRNAs in the pathogenesis of bipolar disorder (BD). Exosomes are membrane-bound vesicles acting as "biological cargo carriers" of various types of molecules including microRNAs. In this study, we aimed to investigate circulating exosomal microRNAs as potential diagnostic biomarkers for BD.

METHODS

The exosomes were precipitated from plasma samples of patients with BD (n = 69; 15 depressed, 27 manic, 27 euthymic) and healthy controls (n = 41). Total RNA was extracted from the exosomes and the levels of miRNAs were assayed by qPCR. Dysregulated miRNAs were subjected to Kyoto Encyclopedia of Genes and Genomes" (KEGG) pathway analysis by DIANA-miRPath v3.0 to identify the predicted targets and the related pathways.

RESULTS

Thirteen miRNAs showed significant differences between patients with BD and healthy individuals; among these, MiR-484, -652-3p, -142-3p remained significantly downregulated and miR-185-5p remained significantly upregulated after accounting for multiple comparisons and adjustments for potential confounders. There were no significant alterations among different states of BD. The KEEG analysis of four dysregulated miRNAs highlighted several target pathways including PI3K/Akt signaling, fatty acid biosynthesis/metabolism, extracellular matrix and adhesion pathways.

CONCLUSION

Our findings suggest that dysregulation of miRNAs might be involved in the underlying pathophysiology of BD through several biological pathways; and highlight the importance of the exosomal miRNAs for biomarker research in BD. Further longitudinal studies may clarify the roles of exosomal miRNAs and their targets in the neurobiology of BD.

miRNAs as Biomarkers in Disease: Latest Findings Regarding Their Role in Diagnosis and Prognosis

MicroRNAs (miRNAs) represent a class of small, non-coding RNAs with the main roles of regulating mRNA through its degradation and adjusting protein levels. In recent years, extraordinary progress has been made in terms of identifying the origin and exact functions of miRNA, focusing on their potential use in both the research and the clinical field. This review aims at improving the current understanding of these molecules and their applicability in the medical field. A thorough analysis of the literature consulting resources available in online databases such as NCBI, PubMed, Medline, ScienceDirect, and UpToDate was performed. There is promising evidence that in spite of the lack of standardized protocols regarding the use of miRNAs in current clinical practice, they constitute a reliable tool for future use. These molecules meet most of the required criteria for being an ideal biomarker, such as accessibility, high specificity, and sensitivity. Despite present limitations, miRNAs as biomarkers for various conditions remain an impressive research field. As current techniques evolve, we anticipate that miRNAs will become a routine approach in the development of personalized patient profiles, thus permitting more specific therapeutic interventions.

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.

Differentiation of Pathogenic Th17 Cells Is Negatively Regulated by Let-7 MicroRNAs in a Mouse Model of Multiple Sclerosis

Multiple sclerosis (MS) is a disabling demyelinating autoimmune disorder of the central nervous system (CNS) which is driven by IL-23- and IL-1β-induced autoreactive Th17 cells that traffic to the CNS and secrete proinflammatory cytokines. Th17 pathogenicity in MS has been correlated with the dysregulation of microRNA (miRNA) expression, and specific miRNAs have been shown to promote the pathogenic Th17 phenotype. In the present study, we demonstrate, using the animal model of MS, experimental autoimmune encephalomyelitis (EAE), that let-7 miRNAs confer protection against EAE by negatively regulating the proliferation, differentiation and chemokine-mediated migration of pathogenic Th17 cells to the CNS. Specifically, we found that let-7 miRNAs may directly target the cytokine receptors Il1r1 and Il23r, as well as the chemokine receptors Ccr2 and Ccr5. Therefore, our results identify a novel regulatory role for let-7 miRNAs in pathogenic Th17 differentiation during EAE development, suggesting a promising therapeutic application for disease treatment.

MicroRNAs as disease progression biomarkers and therapeutic targets in experimental autoimmune encephalomyelitis model of multiple sclerosis

Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain, spinal cord and optic nerve leading to demyelination. Focal demyelination is associated with relapsing-remitting multiple sclerosis, while progressive forms of the disease show axonal degeneration and neuronal loss. The tests currently used in the clinical diagnosis and management of multiple sclerosis have limitations due to specificity and sensitivity. MicroRNAs (miRNAs) are dysregulated in many diseases and disorders including demyelinating and neuroinflammatory diseases. A review of recent studies with the experimental autoimmune encephalomyelitis animal model (mostly female mice 6–12 weeks of age) has confirmed miRNAs as biomarkers of experimental autoimmune encephalomyelitis disease and importantly at the pre-onset (asymptomatic) stage when assessed in blood plasma and urine exosomes, and spinal cord tissue. The expression of certain miRNAs was also dysregulated at the onset and peak of disease in blood plasma and urine exosomes, brain and spinal cord tissue, and at the post-peak (chronic) stage of experimental autoimmune encephalomyelitis disease in spinal cord tissue. Therapies using miRNA mimics or inhibitors were found to delay the induction and alleviate the severity of experimental autoimmune encephalomyelitis disease. Interestingly, experimental autoimmune encephalomyelitis disease severity was reduced by overexpression of miR-146a, miR-23b, miR-497, miR-26a, and miR-20b, or by suppression of miR-182, miR-181c, miR-223, miR-155, and miR-873. Further studies are warranted on determining more fully miRNA profiles in blood plasma and urine exosomes of experimental autoimmune encephalomyelitis animals since they could serve as biomarkers of asymptomatic multiple sclerosis and disease course. Additionally, studies should be performed with male mice of a similar age, and with aged male and female mice.

An explorative study identifies miRNA signatures for the diagnosis of non-celiac wheat sensitivity

Non-celiac wheat sensitivity (NCWS), also referred to as non-celiac gluten sensitivity, is a recently described disorder triggered by wheat/gluten ingestion. NCWS elicits a wide range of symptoms including diarrhoea, intestinal discomfort, and fatigue in analogy with other wheat/gluten-related disorders and celiac disease in particular. From the pathological standpoint, NCWS patients only have a slight increase of intraepithelial lymphocytes, while antibodies to tissue transglutaminase (tTG) and villous atrophy, otherwise diagnostic features of celiac disease, are absent. To date, the diagnosis of NCWS relies on symptoms and exclusion of confounding diseases, since biomarkers are not yet available. Here, the expression levels of selected miRNAs were examined in duodenal biopsies and peripheral blood leukocytes collected from newly diagnosed patients with NCWS and, as controls, from patients with celiac disease and gluten-independent gastrointestinal problems. We identified a few miRNAs whose expression is higher in the intestinal mucosa of patients affected by NCWS in comparison to control patients affect by gluten-independent dyspeptic symptoms (Helicobacter pylori-negative) and celiac disease. The present study provided the first evidence that NCWS patients have a characteristic miRNA expression patterns, such peculiarity could be exploited as a biomarker to the diagnosis of this disease.

Analysis of miRNA signatures in CSF identifies upregulation of miR-21 and miR-146a/b in patients with multiple sclerosis and active lesions

BACKGROUND

MicroRNAs (miRNAs) have been reported as deregulated in active brain lesions derived from patients with multiple sclerosis (MS). In there, these post-transcriptional regulators may elicit very important effects but proper identification of miRNA candidates as potential biomarkers and/or therapeutic targets is scarcely available.

OBJECTIVE

The aim of the study was to detect the presence of a set of candidate miRNAs in cell-free cerebrospinal fluid (CSF) and to determine their association with gadolinium-enhancing (Gd+) lesions in order to assess their value as biomarkers of MS activity.

METHODS

Assessment of 28 miRNA candidates in cell-free CSF collected from 46 patients with MS (26 Gd+ and 20 Gd- patients) was performed by TaqMan assays and qPCR. Variations in their relative abundance were analyzed by the Mann-Whitney U test and further evaluated by receiver operating characteristic (ROC) analysis. Signaling pathways and biological functions of miRNAs were analyzed using bioinformatic tools (miRTarBase, Enrichr, REVIGO, and Cytoscape softwares).

RESULTS

Seven out of 28 miRNA candidates were detected in at least 75% of CSF samples. Consistent increase of miR-21 and miR-146a/b was found in Gd+ MS patients. This increase was in parallel to the number of Gd+ lesions and neurofilament light chain (NF-L) levels. Gene Ontology enrichment analysis revealed that the target genes of these miRNAs are involved in biological processes of key relevance such as apoptosis, cell migration and proliferation, and in cytokine-mediated signaling pathways.

CONCLUSION

Levels of miR-21 and miR-146a/b in cell-free CSF may represent valuable biomarkers to identify patients with active MS lesions.

Cannabidiol Regulates Gene Expression in Encephalitogenic T cells Using Histone Methylation and noncoding RNA during Experimental Autoimmune Encephalomyelitis

Cannabidiol (CBD) has been shown by our laboratory to attenuate experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). In this study, we used microarray and next generation sequencing (NGS)-based approaches to determine whether CBD would alter genome-wide histone modification and gene expression in MOG sensitized lymphocytes. We compared H3K4me3 and H3K27me3 marks in CD4+ T cells from naïve, EAE and CBD treated EAE mice by ChIP-seq. Although the overall methylation level of these two histone marks did not change significantly, the signal intensity and coverage differed in individual genes, suggesting that CBD may modulate gene expression by altering histone methylation. Further analysis showed that these histone methylation signals were differentially enriched in the binding sites of certain transcription factors, such as ZNF143 and FoxA1, suggesting that these transcription factors may play important roles in CBD mediated immune modulation. Using microarray analysis, we found that the expression pattern of many EAE-induced genes was reversed by CBD treatment which was consistent with its effect on attenuating the clinical symptoms of EAE. A unique finding of this study was that the expression of many miRNAs and lncRNAs was dramatically affected by CBD. In summary, this study demonstrates that CBD suppresses inflammation through multiple mechanisms, from histone methylation to miRNA to lncRNA.

Intranasal Administration of miR-146a Agomir Rescued the Pathological Process and Cognitive Impairment in an AD Mouse Model

Alzheimer’s disease (AD) is the most common cause of dementia and cannot be cured. The etiology and pathogenesis of AD is still not fully understood, the genetics is considered to be one of the most important factors for AD onset, and the identified susceptible genes could provide clues to the AD mechanism and also be the potential targets. MicroRNA-146a-5p (miR-146a) is well known in the regulation of the inflammatory response, and the functional SNP of miR-146a was associated with AD risk. In this study, using a noninvasive nasal administration, we discovered that a miR-146a agomir (M146AG) rescued cognitive impairment in the APP/PS1 transgenic mouse and alleviated the overall pathological process in the AD mouse model, including neuroinflammation, glia activation, Aβ deposit, and tau phosphorylation in hippocampi. Furthermore, the transcriptional analysis revealed that besides the effect of neuroinflammation, M146AG may serve as a multi-potency target for intervention in AD. In addition, Srsf6 was identified as a target of miR-146a, which may play a role in AD progression. In conclusion, our study supports that the nasal-to-brain pathway is efficient and operable for the brain administration of microRNAs (miRNAs), and that miR-146a may be a new potential target for AD treatment.

Comparison of The Expression of miR-326 between Interferon beta Responders and Non-Responders in Relapsing-Remitting Multiple Sclerosis

Objective

Multiple sclerosis (MS) is an inflammatory disease resulting in demyelination of the central nervous system (CNS). T helper 17 (Th17) subset protects the human body against pathogens and induces neuroinflammation, which leads to neurodegeneration. MicroRNAs (miRNAs) are a specific class of small (~22 nt) non-coding RNAs that act as post-transcriptional regulators. The expression of the miR-326 is highly associated with the pathogenesis of MS disease in patients through the promotion of Th17 development. Recently, studies showed that disease-modifying therapies (DMTs) could balance the dysregulation of miRNAs in the immune cells of patients with relapsing-remitting MS (RRMS). Interferon-beta (IFN-β) has emerged as one of the most common drugs for the treatment of RR-MS patients. The purpose of this study was to evaluate the expression of the miR-326 in RRMS patients who were responders and non- responders to IFN-β treatment.

Materials and Methods

In this cross-sectional study, a total of 70 patients (35 responders and 35 non-responders) were enrolled. We analyzed the expression of the miR-326 in peripheral blood mononuclear cells (PBMCs) of RRMS patients at least one year after the initiation of IFN-β therapy. Real-time polymerase chain reaction (RT-PCR) was applied to measure the expression of the miR-326.

Results

The results showed no substantial change in the expression of the miR-326 between responders and non- responders concerning the treatment with IFN-β. Although the expression of the miR-326 was slightly reduced in IFN-β-responders compared with IFN-β-non-responders; however, the reduction of the miR-326 was not statistically significant.

Conclusion

Overall, since IFN-β doesn’t normalize abnormal expression of miR-326, this might suggest that IFN-β affects Th17 development through epigenetic mechanisms other than miR-326 regulation.

Gene Regulatory Networks in Peripheral Mononuclear Cells Reveals Critical Regulatory Modules and Regulators of Multiple Sclerosis

Multiple sclerosis (MS) is a complex, demyelinating disease with the involvement of autoimmunity and neurodegeneration. Increasing efforts have been made towards identifying the diagnostic markers to differentiate the classes of MS from other similar neurological conditions. Using a systems biology approach, we constructed four types of gene regulatory networks (GRNs) involved in peripheral blood mononuclear cells (PBMCs). The regulatory strength of each GRN across primary progressive MS (PPMS), relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), and control were evaluated by an integrity algorithm. Among the constructed GRNs (referred as TF_gene_miRNA), POU3F2_CDK6_hsa-miR-590-3p, MEIS1_CASC3_hsa-miR-1261, STAT3_OGG1_hsa-miR-298, and TCF4_FMR1_hsa-miR-301b were top-ranked and differentially regulated in all classes of MS compared to control. These GRNs showed potential involvement in regulating various molecular pathways such as interleukin, integrin, glypican, sphingosine phosphate, androgen, and Wnt signaling pathways. For validation, the qPCR analysis of the GRN components (TFs, gene, and miRNAs) in PBMCs of healthy controls (n = 30), RRMS (n = 14), PPMS (n = 13) and SPMS (n = 12) were carried out. Real-time expression analysis of GRNs showed a similar regulatory pattern as derived from our systems biology approach. Also, our study provided several novel GRNs that regulate unique and common molecular mechanisms between MS conditions. Hence, these regulatory components of GRNs will help to understand the disease mechanism across MS classes and further insight may though light towards diagnosis.

Recent advances on nanomaterials-based fluorimetric approaches for microRNAs detection

MicroRNAs are types of small single-stranded endogenous highly conserved non-coding RNAs, which play main regulatory functions in a wide range of cellular and physiological events, such as proliferation, differentiation, neoplastic transformation, and cell regeneration. Recent findings have proved a close association between microRNAs expression and the development of many diseases, indicating the importance of microRNAs as clinical biomarkers and targets for drug discovery. However, due to a number of prominent characteristics like small size, high sequence similarity and low abundance, sensitive and selective identification of microRNAs has rather been a hardship through routine traditional assays, including quantitative polymerase chain reaction, microarrays, and northern blotting analysis. More recently, the soaring progression in nanotechnology and fluorimetric methodologies in combination with nanomaterials have promised microRNAs detection with high sensitivity, efficiency and selectivity, excellent reproducibility and lower cost. Therefore, this review will represent an overview of latest advances in microRNAs detection through nanomaterials-based fluorescent methods, like gold nanoparticles, silver and copper nanoclusters, graphene oxide, and magnetic silicon nanoparticles.

Adenovirus-mediated down-regulation of miR-21-5p alleviates experimental autoimmune uveoretinitis in mice

MiR-21-5p has been found to be up-regulated in the retina of experimental autoimmune uveoretinitis (EAU) mice and correlated with the pathogenesis of EAU. The objective of the present study is to explore the role of miR-21-5p in EAU. C57 mice were immunized with residue1-20 (IRBP_1-20) in complete Freund's adjuvant supplemented with Mycobacterium tuberculosis H37Ra to induce EAU, and miR-21-5p was knocked down via subretinal injection of anti-miR-21-5p adenovirus. The pathological score, TUNEL positive cells and the expression of pro-inflammatory factors in the retina were reduced, and the expression of IL-10 was increased by down-regulation of miR-21-5p. Up-regulation of miR-21-5p significantly decreased the mRNA and protein levels of IL-10 in ARPE-19 cells. The binding activity of miR-21-5p on the 3'UTR of IL-10 mRNA was confirmed by luciferase reporter assay. Moreover, the miR-21-5p level in splenic lymphocytes of EAU mice was increased at the 7th day after immunization and reached its peak at the 14th day, that was in accordance with the changing trend with the Th17 cell frequency in the spleen. Besides, lentivirus-mediated down-regulation of miR-21-5p reduced the Th17 cell frequency and increased the Treg cell fraction of IRBP_1-20-stimulated lymphocytes in vitro. Taken together, in situ down-regulation of miR-21-5p attenuates EAU by inhibiting inflammatory responses and reducing retinal cell apoptosis. miR-21-5p may also participate in the progress of EAU by affecting Th17/Treg balance via the regulation of IL-10. Therefore, we demonstrate that miR-21-5p can serve as a therapeutic target in the management of uveitis and other autoimmune diseases.

Circular RNAs as a novel layer of regulatory mechanism in multiple sclerosis

Multiple sclerosis (MS) is believed to be an autoimmune disease of the central nervous system (CNS) in which autoreactive immune cells recognizing myelin antigens lead to demyelination and axonal injury. Mechanisms inducing and controlling the pathogenesis of MS have not been fully elucidated. Recent studies suggest an important role of epigenetic processes during the development of MS. One of the most significant discoveries in the field of epigenetic contribution to immune response has been the recognition of a group of microRNAs (miRNAs). These single-stranded non-coding RNA molecules regulate the expression of genes encoding proteins and have already been shown to be involved in pathogenesis of MS. Some miRNAs enhance generation of pro-inflammatory immune cells by promoting Th1 and Th17 pathways and others contribute to regulatory and tissue repair processes. The miRNA-dependent controlling process of autoimmune reactions is highly complex because of miRNA redundancy and multitarget nature of most of these molecules. Recently it was discovered that circular RNAs (circRNA) representing a new class of RNA possess a unique ability to control miRNAs by blocking their activity. CircRNAs are called natural miRNA "sponges" as the single circRNA molecule is able to neutralize several miRNAs and thus might determine the availability of miRNAs for their posttranscription regulation. Thus, circRNAs emerged as critical factors in epigenetic regulation of many human diseases including MS. In addition, in contrary to other RNA species they are very stable in the blood and other biological fluids and thus might be considered as a candidate for a biomarker of MS.

Panoramic Visualization of Circulating MicroRNAs Across Neurodegenerative Diseases in Humans

Neurodegenerative diseases (NDs) such as Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and dementia pose one of the greatest health challenges this century. Although these NDs have been looked at as single entities, the underlying molecular mechanisms have never been collectively visualized to date. With the advent of high-throughput genomic and proteomic technologies, we now have the opportunity to visualize these diseases in a whole new perspective, which will provide a clear understanding of the primary and secondary events vital in achieving the final resolution of these diseases guiding us to new treatment strategies to possibly treat these diseases together. We created a knowledge base of all microRNAs known to be differentially expressed in various body fluids of ND patients. We then used several bioinformatic methods to understand the functional intersections and differences between AD, PD, ALS, and MS. These results provide a unique panoramic view of possible functional intersections between AD, PD, MS, and ALS at the level of microRNA and their cognate genes and pathways, along with the entities that unify and separate them. While the microRNA signatures were apparent for each ND, the unique observation in our study was that hsa-miR-30b-5p overlapped between all four NDS, and has significant functional roles described across NDs. Furthermore, our results also show the evidence of functional convergence of miRNAs which was associated with the regulation of their cognate genes represented in pathways that included fatty acid synthesis and metabolism, ECM receptor interactions, prion diseases, and several signaling pathways critical to neuron differentiation and survival, underpinning their relevance in NDs. Envisioning this group of NDs together has allowed us to propose new ways of utilizing circulating miRNAs as biomarkers  and in visualizing diverse NDs more holistically . The critical molecular insights gained through the discovery of ND-associated miRNAs, overlapping miRNAs, and the functional convergence of microRNAs on vital pathways strongly implicated in neurodegenerative processes can prove immensely valuable in the identifying new generation of biomarkers, along with the development of miRNAs into therapeutics.

microRNA diagnostic panel for Alzheimer's disease and epigenetic trade-off between neurodegeneration and cancer

microRNAs (miRNAs) have been extensively studied as potential biomarkers for Alzheimer's disease (AD). Their profiles have been analyzed in blood, cerebrospinal fluid (CSF) and brain tissue. However, due to the high variability between the reported data, stemming from the lack of methodological standardization and the heterogeneity of AD, the most promising miRNA biomarker candidates have not been selected. Our literature review shows that out of 137 miRNAs found to be altered in AD blood, 36 have been replicated in at least one independent study, and out of 166 miRNAs reported as differential in AD CSF, 13 have been repeatedly found. Only 3 miRNAs have been consistently reported as altered in three analyzed specimens: blood, CSF and the brain (hsa-miR-146a, hsa-miR-125b, hsa-miR-135a). Nonetheless, all 36 repeatedly differential miRNAs in AD blood are promising as components of the diagnostic panel. Given their predicted functions, such miRNA panel may report multiple pathways contributing to AD pathology, enabling the design of personalized therapies. In addition, the analysis revealed that the miRNAs dysregulated in AD overlap highly with miRNAs implicated in cancer. However, the directions of the miRNA changes are usually opposite in cancer and AD, indicative of an epigenetic trade-off between the two diseases.

Increased expression of mir-301a in PBMCs of patients with relapsing-remitting multiple sclerosis is associated with reduced NKRF and PIAS3 expression levels and disease activity

Most of the multiple sclerosis (MS) patients are initially diagnosed with relapsing remitting multiple sclerosis (RRMS). Th17 cells and macrophages have been shown to play critical roles in pathogenesis of MS and initiation of CNS tissue damage. MiR-301a have recently been exposed as an activator of STAT3 in Th17 cells as well as an activator of NF-κB in macrophages by targeting PIAS3 and NKRF correspondingly. However, the possible role of miR-301a in RRMS has not yet been elucidated. Herewith, for the first time, we have studied the expression of miR-301a, NKRF and PIAS3 by quantitative real-time PCR and western blotting method in peripheral blood mononuclear cells (PBMCs) of 71 RRMS patients, including two groups of patients in relapse phase (n = 44) and a group of remitting phase patients (n = 28) in comparison to healthy volunteers (n = 28). In this work, we demonstrate a significant upregulation of miR-301a in relapse phase of MS patients compared to healthy controls and remitting phase patients (P < .05). Our findings also showed a striking decrease of NKRF and PIAS3 expression in relapse phase patients, in contrast to miR-301a and, NF-κB and STAT3 downstream genes (SKA2 and RORc) (P < .05). Subsequently, using luciferase reporter system we confirmed that miR-301a directly targets the mRNA encoding PIAS3 and NKRF proteins. We also showed that miR-301a increasing expression is correlated with down-regulation of PIAS3 and NKRF expression in RRMS patients. Our findings suggest that miR-301a, PIAS3 and NKRF play crucial roles in RRMS and could be considered as promising therapeutic targets.

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.

Investigating the Role of MicroRNA and Transcription Factor Co-regulatory Networks in Multiple Sclerosis Pathogenesis

MicroRNAs (miRNAs) and transcription factors (TFs) play key roles in complex multifactorial diseases like multiple sclerosis (MS). Starting from the miRNomic profile previously associated with a cohort of pediatric MS (PedMS) patients, we applied a combined molecular and computational approach in order to verify published data in patients with adult-onset MS (AOMS). Six out of the 13 selected miRNAs (miR-320a, miR-125a-5p, miR-652-3p, miR-185-5p, miR-942-5p, miR-25-3p) were significantly upregulated in PedMS and AOMS patients, suggesting that they may be considered circulating biomarkers distinctive of the disease independently from age. A computational and unbiased miRNA-based screening of target genes not necessarily associated to MS was then performed in order to provide an extensive view of the genetic mechanisms underlying the disease. A comprehensive MS-specific miRNA-TF co-regulatory network was hypothesized; among others, SP1, RELA, NF-κB, TP53, AR, MYC, HDAC1, and STAT3 regulated the transcription of 61 targets. Interestingly, NF-κB and STAT3 cooperatively regulate the expression of immune response genes and control the cross-talk between inflammatory and immune cells. Further functional analysis will be performed on the identified critical hubs. Above all, in our view, this approach supports the need of multidisciplinary strategies for shedding light into the pathogenesis of MS.

The Micro-RNA Expression Profiles of Autoimmune Arthritis Reveal Novel Biomarkers of the Disease and Therapeutic Response

Rheumatoid arthritis (RA) is a chronic autoimmune disease of the joints affecting about 0.3–1% of the population in different countries. About 50–60 percent of RA patients respond to presently used drugs. Moreover, the current biomarkers for RA have inherent limitations. Consequently, there is a need for additional, new biomarkers for monitoring disease activity and responsiveness to therapy of RA patients. We examined the micro-RNA (miRNA) profile of immune (lymphoid) cells of arthritic Lewis rats and arthritic rats treated with celastrol, a natural triterpenoid. Experimental and bioinformatics analyses revealed 8 miRNAs (miR-22, miR-27a, miR-96, miR-142, miR-223, miR-296, miR-298, and miR-451) and their target genes in functional pathways important for RA pathogenesis. Interestingly, 6 of them (miR-22, miR-27a, miR-96, miR-142, miR-223, and miR-296) were further modulated by celastrol treatment. Interestingly, serum levels of miR-142, miR-155, and miR-223 were higher in arthritic versus control rats, whereas miR-212 showed increased expression in celastrol-treated rats compared with arthritic rats or control rats. This is the first study on comprehensive miRNA expression profiling in the adjuvant-induced arthritis (AA) model and it also has revealed new miRNA targets for celastrol in arthritis. We suggest that subsets of the above miRNAs may serve as novel biomarkers of disease activity and therapeutic response in arthritis.

The MicroRNA-326: Autoimmune diseases, diagnostic biomarker, and therapeutic target

MicroRNAs (miRNAs) are uniquely regulated in healthy, inflamed, activated, cancerous, or other cells and tissues of a pathological state. Many studies confirm that immune dysregulation and autoimmune diseases with inflammation are correlated with various miRNA expression changes in targeted tissues and cells in innate or adaptive immunity. In this review, we will explain the history and classification of epigenetic changes. Next, we will describe the role of miRNAs changes, especially mir-326 in autoimmunity, autoinflammatory, and other pathological conditions. A systematic search of MEDLINE, Embase, and Cochrane Library was presented for all related studies from 1899 to 2017 with restrictions in the English language. In recent years, researchers have concentrated on mostly those roles of miRNA that are correlated with the inflammatory and anti-inflammatory process. Latest studies have proposed a fundamental pathogenic role in cancers and autoinflammatory diseases. Studies have described the role of microRNAs in autoimmunity and autoinflammatory diseases, cancers, and so on. The miRNA-326 expression plays a significant role in autoimmune and other types of diseases.

Do Human Endogenous Retroviruses Contribute to Multiple Sclerosis, and if So, How?

The gammaretroviral human endogenous retrovirus (HERV) families MRSV/HERV-W and HERV-H (including the closely related HERV-Fc1) are associated with an increased risk of multiple sclerosis (MS). Complete HERV sequences betray their endogenous retroviral origin, with open reading frames in gag, pro, pol and env being flanked by two long terminal repeats containing promoter and enhancer sequences with the capacity to regulate HERV transactivation and the activity of host genes in spite of endogenous epigenetic repression mechanisms. HERV virions, RNA, cDNA, Gag and Env, and antibodies to HERV transcriptional products, have variously been found in the blood and/or brain and/or cerebrospinal fluid of MS patients, with the HERV expression level being associated with disease status. Furthermore, some HERV-associated single nucleotide polymorphisms (SNPs), such as rs662139 T/C in a 3-kb region of Xq22.3 containing a HERV-W env locus, and rs391745, upstream of the HERV-Fc1 locus on the X chromosome, are associated with MS susceptibility, while a negative association has been reported with SNPs in the tripartite motif-containing (TRIM) protein-encoding genes TRIM5 and TRIM22. Factors affecting HERV transcription include immune activation and inflammation, since HERV promoter regions possess binding sites for related transcription factors; oxidative stress, with oxidation of guanine to 8-oxoguanine and conversion of cytosine to 5-hydroxymethylcytosine preventing binding of methyl groups transferred by DNA methyltransferases; oxidative stress also inhibits the activity of deacetylases, thereby favouring the acetylation of histone lysine residues favouring gene expression; interferon beta; natalizumab treatment; impaired epigenetic regulation; and the sex of patients.

Serum and thyroid tissue level of let-7b and their correlation with TRAb in Graves' disease

BACKGROUND

Abnormal microRNAs (miRNAs) were reported to be involved in the mechanism of Graves' disease (GD). Dysregulated miRNAs may be overlapping in different cells and can be secreted to circulation. We chose miRNAs which were previously reported to be differentially expressed in peripheral blood mononuclear cells (PBMCs) in patients with GD with different disease stage, detected the expression of those miRNAs in serum, corroborated the findings in thyroid tissue, and validated the target gene in vitro to investigate the possible role of circulating miRNAs in GD.

METHODS

A total of 54 individuals with untreated GD, 12 individuals with GD in remission and 14 disease-free controls were enrolled. The expression of miR-142-3p, miR-154-3p, miR-431-3p, miR-590-5p, and let-7b was detected in the serum. Ten thyroid tissue samples from patients with GD and six disease-free thyroid samples were used for further validation. The potential target genes were identified and validated in vitro.

RESULTS

miR-142-3p, miR-154-3p, miR-431-3p, miR-590-5p, and let-7b were present in serum and two of them (miR-142-3p and let-7b) were significantly increased in serum of patients with untreated GD (for serum miR-142-3p, P = 0.033, for serum let-7b, P = 0.026) and gradually decreased to normal levels in patients with GD in remission. Correlation analysis showed that let-7b level was strongly correlated with TRAb level (r = 0.305, P = 0.001). let-7b directly inhibited promyelocytic leukemia zinc finger (PLZF) expression and increased the expression of TSHR in thyroid cells in vitro. Furthermore, let-7b levels in GD thyroid tissue were found to be inversely correlated with PLZF levels (r = - 0.849, P = 0.033). Decreased PLZF and increased TSHR was validated in thyroid tissue in patients with GD.

CONCLUSIONS

The present study confirmed that a portion of miRNAs in PBMCs were also presented and differentially expressed in serum and thyroid tissue. Upregulated in all these three compartments, let-7b may be used as a disease biomarker and therapeutic targets in patients with GD. Circulating let-7b had a strong correlation with disease severity and let-7b may participate in the production of TRAb via targeting PLZF in patients with GD.