MicroRNA 182 inhibits CD4+CD25+Foxp3+ Treg differentiation in experimental autoimmune encephalomyelitis

The role of microRNA-142a in Toxoplasma gondii infection-induced downregulation of Foxp3: implications for adverse pregnancy outcomes

BACKGROUND

Toxoplasma gondii (T. gondii) is capable of infecting nearly all warm-blooded animals and approximately 30% of the global population. Though most infections are subclinical in immunocompetent individuals, congenital contraction can lead to severe consequences such as spontaneous abortion, stillbirth, and a range of cranio-cerebral and/or ocular abnormalities. Previous studies reported that T. gondii-infected pregnancy mice unveiled a deficit in both the amount and suppressive functions of regulatory T (Treg) cells, accompanied with reduced levels of forkhead box p3 (Foxp3). Recently, accumulative studies have demonstrated that microRNAs (miRNAs) are, to some extent, relevant to T. gondii infection. However, the link between alterations in miRNAs and downregulation of Foxp3 triggered by T. gondii has been only sporadically studied.

METHODS

Quantitative reverse transcription polymerase chain reaction (RT-qPCR), protein blotting and immunofluorescence were employed to evaluate the impact of T. gondii infection and antigens on miRNA transcription and Foxp3 expression. Dual-luciferase reporter gene assays were performed to examine the fluorescence activity in EL4 cells, which were transfected with recombinant plasmids containing full-length/truncated/mutant microRNA-142a-3p (miR-142a) promoter sequence or wild type/mutant of Foxp3 3' untranslated region (3' UTR).

RESULTS

We found a pronounced increase in miR-142a transcription, concurrent with a decrease in Foxp3 expression in T. gondii-infected mouse placental tissue. Similarly, comparable findings have been experimentally confirmed through the treatment of EL4 cells with T. gondii antigens (TgAg) in vitro. Simultaneously, miR-142a mimics attenuated Foxp3 expression, whereas its inhibitors markedly augmented Foxp3 expression. miR-142a promoter activity was elevated upon the stimulation of T. gondii antigens, which mitigated co-transfection of mutant miR-142a promoter lacking P53 target sites. miR-142a mimics deceased the fluorescence activity of Foxp3 3' untranslated region (3' UTR), but it did not affect the fluorescence activity upon the co-transfection of mutant Foxp3 3' UTR lacking miR-142a target site.

CONCLUSION

In both in vivo and in vitro studies, a negative correlation was discovered between Foxp3 expression and miR-142a transcription. TgAg enhanced miR-142a promoter activity to facilitate miR-142a transcription through a P53-dependent mechanism. Furthermore, miR-142a directly targeted Foxp3 3' UTR, resulting in the downregulation of Foxp3 expression. Therefore, harnessing miR-142a may be a possible therapeutic approach for adverse pregnancy caused by immune imbalances, particularly those induced by T. gondii infection.

Inhibition of Foxp3 expression in the placenta of mice infected intraperitoneally by toxoplasma gondii tachyzoites: insights into the PPARγ/miR-7b-5p/Sp1 signaling pathway

BACKGROUND

Toxoplasma gondii, an obligate intracellular parasitic protozoa, infects approximately 30% of the global population. Contracting T. gondii at the primary infection of the mother can result in neonatal microcephaly, chorioretinitis, hydrocephalus, or mortality. Our previous study indicated that pregnant mice infected with T. gondii displayed a decrease in both the number and the suppressive ability of regulatory T cells, accompanied by the reduced Forkhead box P3 (Foxp3). Numerous studies have proved that microRNAs (miRNAs) are implicated in T. gondii infection, but there is meager evidence on the relationship between alterations of miRNAs and downregulation of Foxp3 induced by T. gondii.

METHODS

Quantitative reverse transcription polymerase chain reaction was utilized to detect the transcriptions of miRNAs and Foxp3. Protein blotting and immunofluorescence were used to detect the expressions of Foxp3 and related transcription factors. The structure of mouse placenta was observed by hematoxylin and eosin (HE) staining. To examine the activity of miR-7b promoter and whether miR-7b-5p targets Sp1 to suppress Foxp3 expression, we constructed recombinant plasmids containing the full-length/truncated/mutant miR-7b promoter sequence or wildtype/mutant of Sp1 3' untranslated region (3' UTR) to detect the fluorescence activity in EL4 cells.

RESULTS

In T. gondii-infected mice, miR-7b transcription was significantly elevated, while Foxp3 expression was decreased in the placenta. In vitro, miR-7b mimics downregulated Foxp3 expression, whereas its inhibitors significantly upregulated Foxp3 expression. miR-7b promoter activity was elevated upon the stimulation of T. gondii antigens, which was mitigated by co-transfection of mutant miR-7b promoter lacking peroxisome proliferator-activated receptor γ (PPARγ) target sites. Additionally, miR-7b mimics diminished Sp1 expression, while miR-7b inhibitors elevated its expression. miR-7b mimics deceased the fluorescence activity of Sp1 3' untranslated region (3' UTR), but it failed to impact the fluorescence activity upon the co-transfection of mutant Sp1 3' UTR lacking miR-7b target site.

CONCLUSIONS

T. gondii infection and antigens promote miR-7b transcription but inhibit Foxp3 protein and gene levels. T. gondii antigens promote miR-7b promoter activity by a PPARγ-dependent mechanism. miR-7b directly binds to Sp1 3' UTR to repress Sp1 expression. Understanding the regulatory functions by which T. gondii-induced miR-7b suppresses Foxp3 expression can provide new perspectives for the possible therapeutic avenue of T. gondii-induced adverse pregnancy outcomes.

The miR-183/96/182 cluster regulates sensory innervation, resident myeloid cells and functions of the cornea through cell type-specific target genes

The conserved miR-183/96/182 cluster (miR-183C) is expressed in both corneal resident myeloid cells (CRMCs) and sensory nerves (CSN) and modulates corneal immune/inflammatory responses. To uncover cell type-specific roles of miR-183C in CRMC and CSN and their contributions to corneal physiology, myeloid-specific miR-183C conditional knockout (MS-CKO), and sensory nerve-specific CKO (SNS-CKO) mice were produced and characterized in comparison to the conventional miR-183C KO. Immunofluorescence and confocal microscopy of flatmount corneas, corneal sensitivity, and tear volume assays were performed in young adult naïve mice; 3' RNA sequencing (Seq) and proteomics in the trigeminal ganglion (TG), cornea and CRMCs. Our results showed that, similar to conventional KO mice, the numbers of CRMCs were increased in both MS-CKO and SNS-CKO vs age- and sex-matched WT control littermates, suggesting intrinsic and extrinsic regulations of miR-183C on CRMCs. The number of CRMCs was increased in male vs female MS-CKO mice, suggesting sex-dependent regulation of miR-183C on CRMCs. In the miR-183C KO and SNS-CKO, but not the MS-CKO mice, CSN density was decreased in the epithelial layer of the cornea, but not the stromal layer. Functionally, corneal sensitivity and basal tear volume were reduced in the KO and SNS-CKO, but not the MS-CKO mice. Tear volume in males is consistently higher than female WT mice. Bioinformatic analyses of the transcriptomes revealed a series of cell-type specific target genes of miR-183C in TG sensory neurons and CRMCs. Our data elucidate that miR-183C imposes intrinsic and extrinsic regulation on the establishment and function of CSN and CRMCs by cell-specific target genes. miR-183C modulates corneal sensitivity and tear production through its regulation of corneal sensory innervation.

Cuproptosis-related gene identification and immune infiltration analysis in systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by loss of tolerance to self-antigen, autoantibody production, and abnormal immune response. Cuproptosis is a recently reported cell death form correlated with the initiation and development of multiple diseases. This study intended to probe cuproptosis-related molecular clusters in SLE and constructed a predictive model.

Methods

We analyzed the expression profile and immune features of cuproptosis-related genes (CRGs) in SLE based on GSE61635 and GSE50772 datasets and identified core module genes associated with SLE occurrence using the weighted correlation network analysis (WGCNA). We selected the optimal machine-learning model by comparing the random forest (RF) model, support vector machine (SVM) model, generalized linear model (GLM), and the extreme gradient boosting (XGB) model. The predictive performance of the model was validated by nomogram, calibration curve, decision curve analysis (DCA), and external dataset GSE72326. Subsequently, a CeRNA network based on 5 core diagnostic markers was established. Drugs targeting core diagnostic markers were acquired using the CTD database, and Autodock vina software was employed to perform molecular docking.

Results

Blue module genes identified using WGCNA were highly related to SLE initiation. Among the four machine-learning models, the SVM model presented the best discriminative performance with relatively low residual and root-mean-square error (RMSE) and high area under the curve (AUC = 0.998). An SVM model was constructed based on 5 genes and performed favorably in the GSE72326 dataset for validation (AUC = 0.943). The nomogram, calibration curve, and DCA validated the predictive accuracy of the model for SLE as well. The CeRNA regulatory network includes 166 nodes (5 core diagnostic markers, 61 miRNAs, and 100 lncRNAs) and 175 lines. Drug detection showed that D00156 (Benzo (a) pyrene), D016604 (Aflatoxin B1), D014212 (Tretinoin), and D009532 (Nickel) could simultaneously act on the 5 core diagnostic markers.

Conclusion

We revealed the correlation between CRGs and immune cell infiltration in SLE patients. The SVM model using 5 genes was selected as the optimal machine learning model to accurately evaluate SLE patients. A CeRNA network based on 5 core diagnostic markers was constructed. Drugs targeting core diagnostic markers were retrieved with molecular docking performed.

MicroRNA-183/96/182 cluster in immunity and autoimmunity

MicroRNAs (miRNAs) are crucial post-transcriptional regulators of gene expression in ubiquitous biological processes, including immune-related pathways. This review focuses on the miR-183/96/182 cluster (miR-183C), which contains three miRNAs, miR-183, -96, and -182, having almost identical seed sequences with minor differences. The similarity among seed sequences allows these three miRNAs to act cooperatively. In addition, their minor differences permit them to target distinct genes and regulate unique pathways. The expression of miR-183C was initially identified in sensory organs. Subsequently, abnormal expression of miR-183C miRNAs in various cancers and autoimmune diseases has been reported, implying their potential role in human diseases. The regulatory effects of miR-183C miRNAs on the differentiation and function of both innate and adaptive immune cells have now been documented. In this review, we have discussed the complex role of miR-183C in the immune cells in both normal and autoimmune backgrounds. We highlighted the dysregulation of miR-183C miRNAs in several autoimmune diseases, including systemic lupus erythematosus (SLE), multiple sclerosis (MS), and ocular autoimmune disorders, and discussed the potential for utilizing miR-183C as biomarkers and therapeutic targets of specific autoimmune diseases.

Deletion of microRNA-183-96-182 Cluster in Lymphocytes Suppresses Anti-DsDNA Autoantibody Production and IgG Deposition in the Kidneys in C57BL/6-Faslpr/lpr Mice

Dysregulated miRNAs have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). Our previous study reported a substantial increase in three miRNAs located at the miR-183-96-182 cluster (miR-183C) in several autoimmune lupus-prone mice, including MRL/lpr and C57BL/6-lpr (B6/lpr). This study reports that in vitro inhibition of miR-182 alone or miR-183C by specific antagomirs in activated splenocytes from autoimmune-prone MRL/lpr and control MRL mice significantly reduced lupus-related inflammatory cytokines, interferon-gamma (IFNγ), and IL-6 production. To further characterize the role of miR-182 and miR-183C cluster in vivo in lupus-like disease and lymphocyte phenotypes, we used hCD2-iCre to generate B6/lpr mice with conditional deletion of miR-182 or miR-183C in CD2+ lymphocytes (miR-182-/-B6/lpr and miR-183C-/-B6/lpr). The miR-182-/-B6/lpr and miR-183C-/-B6/lpr mice had significantly reduced deposition of IgG immunocomplexes in the kidney when compared to their respective littermate controls, although there appeared to be no remarkable changes in renal pathology. Importantly, we observed a significant reduction of serum anti-dsDNA autoantibodies in miR-183C-/-B6/lpr mice after reaching 24 weeks-of age compared to age-matched miR-183Cfl/flB6/lpr controls. In vitro activated splenocytes from miR-182-/-B6/lpr mice and miR-183C-/-B6/lpr mice showed reduced ability to produce lupus-associated IFNγ. Forkhead box O1(Foxo1), a previously validated miR-183C miRNAs target, was increased in the splenic CD4+ cells of miR-182-/-B6/lpr and miR-183C-/-B6/lpr mice. Furthermore, in vitro inhibition of Foxo1 with siRNA in splenocytes from miR-182-/-B6/lpr and miR-183C-/-B6/lpr mice significantly increased IFNγ expression following anti-CD3/CD28 stimulation, suggesting that miR-182 and miR-183C miRNAs regulate the inflammatory IFNγ in splenocytes via targeting Foxo1. The deletion of either miR-182 alone or the whole miR-183C cluster, however, had no marked effect on the composition of T and B cell subsets in the spleens of B6/lpr mice. There were similar percentages of CD4+, CD8+, CD19+, as well as Tregs, follicular helper T (TFH), germinal center B (GCB), and plasma cells in the miR-183C-/-B6/lpr and miR-182-/-B6/lpr mice and their respective littermate controls, miR-183Cfl/flB6/lpr and miR-182fl/flB6/lpr mice. Together, our data demonstrate a role of miR-183C in the regulation of anti-dsDNA autoantibody production in vivo in B6/lpr mice and the induction of IFNγ in in vitro activated splenocytes from B6/lpr mice.

microRNA-92a promotes CNS autoimmunity by modulating the regulatory and inflammatory T cell balance

A disequilibrium between immunosuppressive Tregs and inflammatory IL-17-producing Th17 cells is a hallmark of autoimmune diseases, including multiple sclerosis (MS). However, the molecular mechanisms underlying the Treg and Th17 imbalance in CNS autoimmunity remain largely unclear. Identifying the factors that drive this imbalance is of high clinical interest. Here, we report a major disease-promoting role for microRNA-92a (miR-92a) in CNS autoimmunity. miR-92a was elevated in experimental autoimmune encephalomyelitis (EAE), and its loss attenuated EAE. Mechanistically, miR-92a mediated EAE susceptibility in a T cell-intrinsic manner by restricting Treg induction and suppressive capacity, while supporting Th17 responses, by directly repressing the transcription factor Foxo1. Although miR-92a did not directly alter Th1 differentiation, it appeared to indirectly promote Th1 cells by inhibiting Treg responses. Correspondingly, miR-92a inhibitor therapy ameliorated EAE by concomitantly boosting Treg responses and dampening inflammatory T cell responses. Analogous to our findings in mice, miR-92a was elevated in CD4+ T cells from patients with MS, and miR-92a silencing in patients' T cells promoted Treg development but limited Th17 differentiation. Together, our results demonstrate that miR-92a drives CNS autoimmunity by sustaining the Treg/Th17 imbalance and implicate miR-92a as a potential therapeutic target for MS.

Phenotypic Drift in Lupus-Prone MRL/lpr Mice: Potential Roles of MicroRNAs and Gut Microbiota

MRL/lpr mice have been extensively used as a murine model of lupus. Disease progression in MRL/lpr mice can differ among animal facilities, suggesting a role for environmental factors. We noted a phenotypic drift of our in-house colony, which was the progeny of mice obtained from The Jackson Laboratory (JAX; stocking number 000485), that involved attenuated glomerulonephritis, increased splenomegaly, and reduced lymphadenopathy. To validate our in-house mice as a model of lupus, we compared these mice with those newly obtained from JAX, which were confirmed to be genetically identical to our in-house mice. Surprisingly, the new JAX mice exhibited a similar phenotypic drift, most notably the attenuation of glomerulonephritis. Interestingly, our in-house colony differed from JAX mice in body weight and kidney size (both sexes), as well as in splenic size, germinal center formation, and level of anti-dsDNA auto-IgG in the circulation (male only). In addition, we noted differential expression of microRNA (miR)-21 and miR-183 that might explain the splenic differences in males. Furthermore, the composition of gut microbiota was different between in-house and new JAX mice at early time points, which might explain some of the renal differences (e.g., kidney size). However, we could not identify the reason for attenuated glomerulonephritis, a shared phenotypic drift between the two colonies. It is likely that this was due to certain changes of environmental factors present in both JAX and our facilities. Taken together, these results suggest a significant phenotypic drift in MRL/lpr mice in both colonies that may require strain recovery from cryopreservation.

Scavenging the hidden impacts of non-coding RNAs in multiple sclerosis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease that causes severe neurological dysfunction leading to disabilities in patients. The prevalence of the disease has been increasing gradually worldwide, and the specific etiology behind the disease is not yet fully understood. Therapies aimed against treating MS patients have been growing lately, intending to delay the disease progression and increase the patients' quality of life. Various pathways play crucial roles in developing the disease, and several therapeutic approaches have been tackling those pathways. However, these strategies have shown several side effects and inconsistent efficacy. MicroRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) have been shown to act as key players in various disease pathogenesis and development. Several proinflammatory and anti-inflammatory miRNAs have been reported to participate in the development of MS. Hence, the review assesses the role of miRNAs, lncRNAs, and circRNAs in regulating immune cell functions better to understand their impact on the molecular mechanics of MS.

Crosstalk Between microRNAs and the Pathological Features of Secondary Lymphedema

Secondary lymphedema is characterized by lymphatic fluid retention and subsequent tissue swelling in one or both limbs that can lead to decreased quality of life. It often arises after loss, obstruction, or blockage of lymphatic vessels due to multifactorial modalities, such as lymphatic insults after surgery, immune system dysfunction, deposition of fat that compresses the lymphatic capillaries, fibrosis, and inflammation. Although secondary lymphedema is often associated with breast cancer, the condition can occur in patients with any type of cancer that requires lymphadenectomy such as gynecological, genitourinary, or head and neck cancers. MicroRNAs demonstrate pivotal roles in regulating gene expression in biological processes such as lymphangiogenesis, angiogenesis, modulation of the immune system, and oxidative stress. MicroRNA profiling has led to the discovery of the molecular mechanisms involved in the pathophysiology of auto-immune, inflammation-related, and metabolic diseases. Although the role of microRNAs in regulating secondary lymphedema is yet to be elucidated, the crosstalk between microRNAs and molecular factors involved in the pathological features of lymphedema, such as skin fibrosis, inflammation, immune dysregulation, and aberrant lipid metabolism have been demonstrated in several studies. MicroRNAs have the potential to serve as biomarkers for diseases and elucidation of their roles in lymphedema can provide a better understanding or new insights of the mechanisms underlying this debilitating condition.

miR-183-5p Is a Potential Molecular Marker of Systemic Lupus Erythematosus

Objective

To investigate microRNA (miRNA) expression profiles in individuals with systemic lupus erythematosus (SLE) and identify the valuable miRNA biomarkers in diagnosing and monitoring SLE.

Methods

Next-generation sequencing (NGS) was performed to assess miRNA amounts in peripheral blood mononuclear cells (PBMCs) from four SLE cases and four healthy controls. Quantitative polymerase chain reaction (qPCR) was carried out for validating candidate miRNAs in 32 SLE cases and 32 healthy controls. In addition, receiver operating characteristic (ROC) curve analysis was completed to evaluate diagnostic performance. Finally, the associations of candidate miRNAs with various characteristics of SLE were analyzed.

Results

A total of 157 miRNAs were upregulated, and 110 miRNAs were downregulated in PBMCs from SLE cases in comparison to healthy controls, of which the increase of miR-183-5p and decrease of miR-374b-3p were validated by qPCR and both showed good diagnostic performance for SLE diagnosis. Besides, miR-183-5p expression levels displayed a positive association with SLE disease activity index (SLEDAI) and anti-dsDNA antibody amounts.

Conclusion

Our data indicated that miR-183-5p is a promising biomarker of SLE.

Mutation Screening in the miR-183/96/182 Cluster in Patients With Inherited Retinal Dystrophy

Inherited retinal dystrophy (IRD) is a heterogenous blinding eye disease and affects more than 200,000 Americans and millions worldwide. By far, 270 protein-coding genes have been identified to cause IRD when defective. However, only one microRNA (miRNA), miR-204, has been reported to be responsible for IRD when a point-mutation occurs in its seed sequence. Previously, we identified that a conserved, polycistronic, paralogous miRNA cluster, the miR-183/96/182 cluster, is highly specifically expressed in all photoreceptors and other sensory organs; inactivation of this cluster in mice resulted in syndromic IRD with multi-sensory defects. We hypothesized that mutations in the miR-183/96/182 cluster in human cause IRD. To test this hypothesis, we perform mutation screening in the pre-miR-183, -96, -182 in >1000 peripheral blood DNA samples of patients with various forms of IRD. We identified six sequence variants, three in pre-miR-182 and three in pre-miR-96. These variants are in the pre-miRNA-182 or -96, but not in the mature miRNAs, and are unlikely to be the cause of the IRD in these patients. In spite of this, the nature and location of these sequence variants in the pre-miRNAs suggest that some may have impact on the biogenesis and maturation of miR-182 or miR-96 and potential roles in the susceptibility to diseases. Although reporting on negative results so far, our study established a system for mutation screening in the miR-183/96/182 cluster in human for a continued effort to unravel and provides deeper insight into the potential roles of miR-183/96/182 cluster in human diseases.

miRNA Regulation of T Cells in Islet Autoimmunity and Type 1 Diabetes

PURPOSE OF REVIEW

Regulatory T cells (Tregs) are critical contributors to immune homeostasis and their dysregulation can lead to the loss of immune tolerance and autoimmune diseases like type 1 diabetes (T1D). Recent studies have highlighted microRNAs (miRNAs) as important regulators of the immune system, by fine-tuning relevant genes in various immune cell types. In this review article, we discuss recent insights into miRNA regulation of immune tolerance and activation. Specifically, we discuss how the dysregulation of miRNAs in T cells contributes to their aberrant function and the onset of islet autoimmunity, as well as their potential as targets of novel intervention strategies to interfere with autoimmune activation.

RECENT FINDINGS

Several studies have shown that the dysregulation of individual miRNAs in T cells can contribute to impaired immune tolerance, contributing to onset and progression of islet autoimmunity. Importantly, the targeting of these miRNAs, including miR-92a, miR-142-3p and miR-181a, resulted in relevant effects on downstream pathways, improved Treg function and reduced islet autoimmunity in murine models. miRNAs are critical regulators of immune homeostasis and the dysregulation of individual miRNAs in T cells contributes to aberrant T cell function and autoimmunity. The specific targeting of individual miRNAs could improve Treg homeostasis and therefore limit overshooting T cell activation and islet autoimmunity.

Epigenetics in Multiple Sclerosis

Multiple sclerosis (MS) is an aggravating autoimmune disease that cripples young patients slowly with physical, sensory and cognitive deficits. The break of self-tolerance to neuronal antigens is the key to the pathogenesis of MS, with autoreactive T cells causing demyelination that subsequently leads to inflammation-mediated neurodegenerative events in the central nervous system. The exact etiology of MS remains elusive; however, the interplay of genetic and environmental factors contributes to disease development and progression. Given that genetic variation only accounts for a fraction of risk for MS, extrinsic risk factors including smoking, infection and lack of vitamin D or sunshine, which cause changes in gene expression, contribute to disease development through epigenetic regulation. To date, there is a growing body of scientific evidence to support the important roles of epigenetic processes in MS. In this chapter, the three main layers of epigenetic regulatory mechanisms, namely DNA methylation, histone modification and microRNA-mediated gene regulation, will be discussed, with a particular focus on the role of epigenetics on dysregulated immune responses and neurodegenerative events in MS. Also, the potential for epigenetic modifiers as biomarkers and therapeutics for MS will be reviewed.

miRNA-Mediated Immune Regulation in Islet Autoimmunity and Type 1 Diabetes

The important role of microRNAs as major modulators of various physiological processes, including immune regulation and homeostasis, has been increasingly recognized. Consequently, aberrant miRNA expression contributes to the defective regulation of T cell development, differentiation, and function. This can result in immune activation and impaired tolerance mechanisms, which exert a cardinal function for the onset of islet autoimmunity and the progression to T1D. The specific impact of miRNAs for immune regulation and how miRNAs and their downstream targets are involved in the pathogenesis of islet autoimmunity and T1D has been investigated recently. These studies revealed that increased expression of individual miRNAs is involved in several layers of tolerance impairments, such as inefficient Treg induction and Treg instability. The targeted modulation of miRNAs using specific inhibitors, resulting in improved immune homeostasis, as well as improved methods for the targeting of miRNAs, suggest that miRNAs, especially in T cells, are a promising target for the reestablishment of immune tolerance.

MicroRNA 182 promotes T helper 1 cell by repressing hypoxia induced factor 1 alpha in experimental autoimmune encephalomyelitis

MicroRNA 182 is important for the clonal expansion of CD4⁺ T cells (Th) following IL-2 stimulation and is a potential therapeutic target for autoimmune diseases. In the present study, we investigated the role of microRNA 182 in the differentiation of pro-inflammatory CD4⁺ T helper cell by overexpressing or silencing microRNA 182 expression both in in vivo and in vitro settings. We report that in the studied Chinese cohort, microRNA 182 is upregulated in patients with relapse and remitting multiple sclerosis (RRMS) and this upregulation is associated with increased IFN-γ producing CD4⁺ Th1 cells in the circulation. In the murine experimental autoimmune encephalomyelitis (EAE) model, global microRNA 182 overexpression exacerbates clinical symptoms and results in augmented CD4⁺ IFN-γ⁺ Th1 and CD4⁺ IL-17⁺ Th17 differentiation in vivo. Addition of microRNA 182 mimics in vitro represses both the protein expression and transcriptional activity of hypoxia induced factor 1α (HIF-1α) but increases the level of IFN-γ transcripts in sorted murine CD4⁺ T cells. Together, our results provide evidence that microRNA 182 may be one of the transitional hubs contribution to regulate Th cells expansion in response to self-antigens and differentiation of antigen specific Th cells during the progression of autoimmune inflammations.

MicroRNA-mediated regulation of T helper type 17/regulatory T-cell balance in autoimmune disease

T helper type 17 (Th17) cells and regulatory T (Treg) cells are two distinct T-cell subsets with opposite effects on immune functions. While Th17 cells are a key effector in the immune response and play critical roles in the development of autoimmunity and inflammation, Treg cells orchestrate the overall immune response and maintain peripheral immune tolerance by regulating the activity of the effector T cells. However, the developmental pathways for Th17 and Treg cells are reciprocally interconnected and there is a significant amount of plasticity between them. Disturbed Th17/Treg balance contributes to the development of autoimmune diseases, like experimental autoimmune encephalomyelitis and multiple sclerosis. MicroRNAs (miRNAs) are small non-coding RNA molecules that post-transcriptionally regulate gene expression. Recently, emerging evidence demonstrates that miRNAs play an important role in regulating the pathogenesis of autoimmune diseases through the modulation of Th17/Treg balance. This review will provide an overview of the dysregulated miRNAs and their functions in modulating the Th17/Treg balance in autoimmune diseases.

Therapeutic Potential of Targeting the Th17/Treg Axis in Autoimmune Disorders

A disruption of the crucial balance between regulatory T-cells (Tregs) and Th17-cells was recently implicated in various autoimmune disorders. Tregs are responsible for the maintenance of self-tolerance, thus inhibiting autoimmunity, whereas pro-inflammatory Th17-cells contribute to the induction and propagation of inflammation. Distortion of the Th17/Treg balance favoring the  pro-inflammatory Th17 side is hence suspected to contribute to exacerbation of autoimmune disorders. This review aims to summarize recent data and advances in targeted therapeutic modification of the Th17/Treg-balance, as well as information on the efficacy of candidate therapeutics with respect to the treatment of autoimmune diseases.