miR-223-3p promotes autoreactive Th17 cell responses in experimental autoimmune uveitis (EAU) by inhibiting transcription factor FOXO3 expression

Longevity factor FOXO3a: A potential therapeutic target for age-related ocular diseases

The forkhead box protein O3 (FOXO3a) belongs to the subgroup O of the forkhead transcription factor family and plays an important role in regulating the aging process by participating in the regulation of various life processes, including cell cycle arrest, apoptosis, autophagy, oxidative stress, and DNA repair. The eye is an organ that is affected by aging earlier. However, the functional role and potential clinical applications of FOXO3a in age-related eye diseases have not received widespread attention and lacked comprehensive and clear clarification. In this review, we demonstrated the relationship between FOXO3a and visual system health, summarized the functional roles of FOXO3a in various eye diseases, and potential ocular-related therapies and drugs targeting FOXO3a in visual system diseases through a review and summary of relevant literature. This review indicates that FOXO3a is an important factor in maintaining the normal function of various tissues in the eye, and is closely related to the occurrence and development of ophthalmic-related diseases. Based on its vital role in the normal function of the visual system, FOXO3a has potential clinical application value in related ophthalmic diseases. At present, multiple molecules and drugs targeting FOXO3a have been reported to have the potential for the treatment of related ophthalmic diseases, but further clinical trials are needed. In conclusion, this review can facilitate us to grasp the role of FOXO3a in the visual system and provide new views and bases for the treatment strategy research of age-related eye diseases.

Study of IL-17 and Intercellular Adhesion Molecule-1 in Conjunctivochalasis Using Correlation Analysis

PURPOSE

The aim of this study was to observe the expression of interleukin (IL)-17 and intercellular adhesion molecule (ICAM)-1 in conjunctivochalasis (CCH) and to analyze the correlations between cytokines and the severity of CCH.

METHODS

Serum samples were collected from 22 patients with CCH and 18 normal controls (NCs). The Ocular Surface Disease Index, tear film break-up time, Schirmer I test, and corneal fluorescein staining were used to evaluate the ocular surface signs and symptoms. The concentrations of IL-17, IL-23, and ICAM-1 in serum and cellular supernatants were measured by enzyme-linked immunosorbent assays, and the gene expression levels of cytokines were measured by a quantitative real-time polymerase chain reaction. The relationships between serum concentrations of IL-17, IL-23, and ICAM-1 with clinical ocular surface parameters in CCH were analyzed using the Spearman correlation analysis.

RESULTS

The concentrations of IL-17 and ICAM-1 in serum and cellular supernatants of CCH were significantly higher than those of NCs (all P < 0.001). The concentrations of IL-23 in serum and cellular supernatants of CCH showed no significant difference from those of NCs ( P > 0.05). The mRNA expression levels of IL-17 and ICAM-1 in conjunctival fibroblasts of CCH were significantly higher than those of NCs (all P < 0.001). The mRNA expression of IL-23 in conjunctival fibroblasts of CCH was higher than that of NCs, without a significant difference ( P > 0.05). Furthermore, the serum concentrations of IL-17 and ICAM-1 were positively correlated with Ocular Surface Disease Index and fluorescein staining (all P < 0.05), and negatively correlated with break-up time and Schirmer I test of CCH (all P < 0.05).

CONCLUSIONS

The expression levels of IL-17 and ICAM-1 were significantly increased in CCH serum and associated with the disease severity. We postulate that IL-17 and ICAM-1 may play a role in the pathogenesis of CCH. IL-17 and ICAM-1 antagonists may be a potential treatment option for CCH in the future.

Dimethyl itaconate inhibits antigen-specific Th17 cell responses and autoimmune inflammation via modulating NRF2/STAT3 signaling

Pathogenic Th17 cells play a crucial role in autoimmune diseases like uveitis and its animal model, experimental autoimmune uveitis (EAU). Dimethyl itaconate (DMI) possesses potent anti-inflammatory effects. However, there is still a lack of knowledge about the role of DMI in regulating pathogenic Th17 cells and EAU. Here, we reported that intraperitoneal administration of DMI significantly inhibited the severity of EAU via selectively suppressing Th17 cell responses. In vitro antigen stimulation studies revealed that DMI dramatically decreased the frequencies and function of antigen-specific Th17, but not Th1, cells. Moreover, DMI hampered the differentiation of naive CD4+ T cells toward pathogenic Th17 cells. DMI-treated DCs produced less IL-1β, IL-6, and IL-23, and displayed an impaired ability to stimulate antigen-specific Th17 activation. Mechanistically, DMI activated the NRF2/HO-1 pathway and suppressed STAT3 signaling, which subsequently restrains p-STAT3 nuclear translocation, leading to decreased pathogenic Th17 cell responses. Thus, we have identified an important role for DMI in regulating pathogenic Th17 cells, supporting DMI as a promising therapy in Th17 cell-driven autoimmune diseases including uveitis.

The role of miRNAs in T helper cell development, activation, fate decisions and tumor immunity

T helper (Th) cells are central members of adaptive immunity and comprise the last line of defense against pathogen infection and malignant cell invasion by secreting specific cytokines. These cytokines then attract or induce the activation and differentiation of other immune cells, including antibody-producing B cells and cytotoxic CD8+ T cells. Therefore, the bidirectional communication between Th cells and tumor cells and their positioning within the tumor microenvironment (TME), especially the tumor immune microenvironment (TIME), sculpt the tumor immune landscape, which affects disease initiation and progression. The type, number, and condition of Th cells in the TME and TIME strongly affect tumor immunity, which is precisely regulated by key effectors, such as granzymes, perforins, cytokines, and chemokines. Moreover, microRNAs (miRNAs) have emerged as important regulators of Th cells. In this review, we discuss the role of miRNAs in regulating Th cell mediated adaptive immunity, focusing on the development, activation, fate decisions, and tumor immunity.

MiR-223-3p attenuates M1 macrophage polarization via suppressing the Notch signaling pathway and NLRP3-mediated pyroptosis in experimental autoimmune uveitis

Autoimmune uveitis is an intraocular inflammatory disease with a high blindness rate in developed countries such as the United States. It is pressing to comprehend the pathogenesis of autoimmune uveitis and develop novel schemes for its treatment. In the present research, we demonstrated that the Notch signaling pathway was activated, and the level of miR-223-3p was significantly reduced in rats with experimental autoimmune uveitis (EAU) compared with the level of normal rats. To investigate the relationship between miR-223-3p and Notch signaling, EAU rats received miR-223-3p-carrying lentivirus, miR-223-3p vector-carrying lentivirus (miR-223-3p-N), and γ-secretase inhibitor (DAPT), respectively. The results of Q-PCR, immunological experiments, and flow cytometry analysis all support the hypothesis that both miR-223-3p and DAPT, a Notch signaling pathway inhibitor, had similar inhibitory effects on the EAU pathological process. That is to say, they could both inhibit the activation of the Notch signaling pathway via modulating recombination signal binding protein-Jκ (RBPJ) to restore the polarization imbalance of M/M2 macrophages in EAU rats. In addition, miR-223-3p could also inhibit NLRP3 inflammasome activation and inflammasome-induced pyroptosis in ocular tissues. Taken together, our findings indicate that miR-223-3p serves as an important regulator in M1 macrophage polarization and pyroptosis, thereby alleviating the inflammatory response in uveitis.

Mettl3 induced miR-338-3p expression in dendritic cells promotes antigen-specific Th17 cell response via regulation of Dusp16

Pathogenic Th17 cells are critical drivers of multiple autoimmune diseases, including uveitis and its animal model, experimental autoimmune uveitis (EAU). However, how innate immune signals modulate pathogenic Th17 responses remains largely unknown. Here, we showed that miR-338-3p endowed dendritic cells (DCs) with an increased ability to activate interphotoreceptor retinoid-binding protein (IRBP)1-20 -specific Th17 cells by promoting the production of IL-6, IL-1β, and IL-23. In vivo administration of LV-miR-338-infected DCs promoted pathogenic Th17 responses and exacerbated EAU development. Mechanistically, dual-specificity phosphatase 16 (Dusp16) was a molecular target of miR-338-3p. miR-338-3p repressed Dusp16 and therefore strengthened the mitogen-activated protein kinase (MAPK) p38 signaling, resulting in increased production of Th17-polarizing cytokines and subsequent pathogenic Th17 responses. In addition, methyltransferase like 3 (Mettl3), a key m6A methyltransferase, mediated the upregulation of miR-338-3p in activated DCs. Together, our findings identify a vital role for Mettl3/miR-338-3p/Dusp16/p38 signaling in DCs-driven pathogenic Th17 responses and suggest a potential therapeutic avenue for uveitis and other Th17 cell-related autoimmune disorders.

The emerging role of epigenetics and gut microbiota in Vogt-Koyanagi-Harada syndrome

Vogt-Koyanagi-Harada (VKH) syndrome is an autoimmune disorder characterized often by acute diffuse uveitis, also known as idiopathic uveoencephalitis. The associated complications can potentially affect multiple systems throughout the body, including eyes, ears, skin and nervous system. Although the pathogenesis of VKH syndrome remains unclear, it has been established that the various genetic factors, epigenetic factors and the imbalance in immune regulation can significantly contribute to the development of this disease. In addition, the experimental autoimmune uveitis (EAU) has been commonly used to further explore the pathogenesis of the disease. Herein, in this review article, we discuss about the major research advances made in understanding of the different epigenetic factors and gut microbes involved in the pathogenesis of VKH syndrome as well as EAU. The information discussed can help to better understand the pathogenesis of VKH syndrome, and thereby might provide a basis for finding novel molecular targets and innovative treatment strategies in the future.

Epigenetic Modifications and Therapy in Uveitis

Uveitis is a sight-threatening intraocular inflammation, and the exact pathogenesis of uveitis is not yet clear. Recent studies, including multiple genome-wide association studies (GWASs), have identified genetic variations associated with the onset and progression of different types of uveitis, such as Vogt–Koyanagi–Harada (VKH) disease and Behcet’s disease (BD). However, epigenetic regulation has been shown to play key roles in the immunoregulation of uveitis, and epigenetic therapies are promising treatments for intraocular inflammation. In this review, we summarize recent advances in identifying epigenetic programs that cooperate with the physiology of intraocular immune responses and the pathology of intraocular inflammation. These attempts to understand the epigenetic mechanisms of uveitis may provide hope for the future development of epigenetic therapies for these devastating intraocular inflammatory conditions.

Emerging Role of Non-Coding RNAs in Regulation of T-Lymphocyte Function

T-lymphocytes (T cells) play a major role in adaptive immunity and current immune checkpoint inhibitor-based cancer treatments. The regulation of their function is complex, and in addition to cytokines, receptors and transcription factors, several non-coding RNAs (ncRNAs) have been shown to affect differentiation and function of T cells. Among these non-coding RNAs, certain small microRNAs (miRNAs) including miR-15a/16-1, miR-125b-5p, miR-99a-5p, miR-128-3p, let-7 family, miR-210, miR-182-5p, miR-181, miR-155 and miR-10a have been well recognized. Meanwhile, IFNG-AS1, lnc-ITSN1-2, lncRNA-CD160, NEAT1, MEG3, GAS5, NKILA, lnc-EGFR and PVT1 are among long non-coding RNAs (lncRNAs) that efficiently influence the function of T cells. Recent studies have underscored the effects of a number of circular RNAs, namely circ_0001806, hsa_circ_0045272, hsa_circ_0012919, hsa_circ_0005519 and circHIPK3 in the modulation of T-cell apoptosis, differentiation and secretion of cytokines. This review summarizes the latest news and regulatory roles of these ncRNAs on the function of T cells, with widespread implications on the pathophysiology of autoimmune disorders and cancer.

MicroRNA-590-3p inhibits T helper 17 cells and ameliorates inflammation in lupus mice

T helper 17 (Th17) cells have a pathogenic effect in many autoimmune diseases. Inhibition of Th17 cells can alleviate the inflammatory damage in autoimmune diseases. Our previous study found that microRNA-590-3p (miR-590-3p) was involved in the differentiation of Th17 cells in systemic lupus erythematosus (SLE). Here, we demonstrated that an increase in Th17 cells was correlated with low expression of miR-590-3p in patients with SLE and in lupus mice. Upregulation of miR-590-3p reduced the differentiation and promoted apoptosis of Th17 cells. Subsequent experiments demonstrated that miR-590-3p promoted apoptosis in Th17 cells by inhibiting autophagy. Autophagy-related 7 (Atg7) was the direct target of miR-590-3p that blocked the autophagy pathway. Finally, treatment of MRL/lpr mice with miR-590-3p agomir ameliorated lupus nephritis and skin lesions. Our work revealed that miR-590-3p inhibited Th17 cells by suppressing autophagy and that increased miR-590-3p expression was able to ameliorate the clinical symptoms of lupus. Therefore, miR-590-3p may be a promising therapeutic target for SLE and other Th17 cell-dependent autoimmune diseases.

CD4+ T-Cell Plasticity in Non-Infectious Retinal Inflammatory Disease

Non-infectious uveitis (NIU) is a potentially sight-threatening disease. Effector CD4⁺ T cells, especially interferon-γ-(IFNγ) producing Th1 cells and interleukin-17-(IL-17) producing Th17 cells, are the major immunopathogenic cells, as demonstrated by adoptive transfer of disease in a model of experimental autoimmune uveitis (EAU). CD4⁺FoxP3⁺CD25⁺ regulatory T cells (Tregs) were known to suppress function of effector CD4⁺ T cells and contribute to resolution of disease. It has been recently reported that some CD4⁺ T-cell subsets demonstrate shared phenotypes with another CD4⁺ T-cell subset, offering the potential for dual function. For example, Th17/Th1 (co-expressing IFNγ and IL-17) cells and Th17/Treg (co-expressing IL-17 and FoxP3) cells have been identified in NIU and EAU. In this review, we have investigated the evidence as to whether these ‘plastic CD4⁺ T cells’ are functionally active in uveitis. We conclude that Th17/Th1 cells are generated locally, are resistant to the immunosuppressive effects of steroids, and contribute to early development of EAU. Th17/Treg cells produce IL-17, not IL-10, and act similar to Th17 cells. These cells were considered pathogenic in uveitis. Future studies are needed to better clarify their function, and in the future, these cell subsets may in need to be taken into consideration for designing treatment strategies for disease.

Quercetin prevents isoprenaline-induced myocardial fibrosis by promoting autophagy via regulating miR-223-3p/FOXO3

Atrial fibrillation (AF) is the common arrhythmias. Myocardial fibrosis (MF) is closely related to atrial remodeling and leads to AF. MF is the main cause of cardiovascular diseases and a pathological basis of AF. Thus, the underlying mechanism in MF and AF development should be fully elucidated for AF therapeutic innovation. Autophagy is a highly conserved lysosomal degradation pathway, and the relationship between autophagy and MF has been previously shown. Moreover, research reported that quercetin (Que) could ameliorate MF. The current study aimed to explore the mechanism of Que in MF. The results in this study showed that in clinical AF patients and in aged rats, miR-223-3p was high-expressed, while FOXO3 and autophagy pathway related proteins, such as ATG7, p62/SQSTM1 and the ratio of LC3B-II/LC3B-I were significantly inhibited. In vivo and in vitro studies, we found that Que can effectively inhibit the expression of miR-223-3p in AF model cells and rats myocardial tissues, and meanwhile enhance the expression of FOXO3 and activate the autophagy pathway, and significantly inhibit myocardial fibrosis, and improve myocardial remodeling in atrial fibrillation. All in all, in this study, we found that Que prevents isoprenaline-induced MF by increasing autophagy via regulating miR-223-3p/FOXO3.

MiR-141-3p and miR-200a-3p are involved in Th17 cell differentiation by negatively regulating RARB expression

Among T helper (Th) lineages differentiated from naïve CD4⁺ T cells, interleukin (IL)-17-producing Th17 cells are highly correlated with the pathogenesis of autoimmune disorders. This study aimed to clarify the involvement of miR-141-3p and miR-200a-3p in Th17 cell differentiation as well as explore their potential target genes involved. For this purpose, human naïve CD4⁺ T cells were cultured under Th17 cell polarizing condition. The differentiation process was confirmed through measurement of IL-17 secretion using the ELISA method and assessment of Th17 cell-defining genes expression during the differentiation period. MiR-141-3p and miR-200a-3p downstream genes were identified via consensus and integration in silico approach and their expression pattern and alterations were evaluated by quantitative real-time PCR. Finally, direct interaction between both microRNAs (miRNAs) and their common predicted target sequences was approved by dual-luciferase reporter assay. Highly increased IL-17 secretion and Th17 lineage-specific genes expression confirmed Th17 cell differentiation. Our results have demonstrated that miR-141-3p and miR-200a-3p are Th17 cell-associated miRNAs and their expression level is upregulated significantly during Th17 cell induction. We have also found that retinoic acid receptor beta (RARB) gene, whose product has been reported as a negative regulator of Th17 cell generation, is a direct target of both miRNAs and its downregulation can affect the transcriptional level of JAK/STAT pathway genes. Overall, our results have identified two novel Th17 lineage-associated miRNAs and have provided evidence for the RARB-dependent mechanism of miR-141-3p and miR-200a-3p-induced Th17 cell differentiation and hence Th17-mediated autoimmunity.

A Role for Folate in Microbiome-Linked Control of Autoimmunity

The microbiome exerts considerable control over immune homeostasis and influences susceptibility to autoimmune and autoinflammatory disease (AD/AID) such as inflammatory bowel disease (IBD), multiple sclerosis (MS), type 1 diabetes (T1D), psoriasis, and uveitis. In part, this is due to direct effects of the microbiome on gastrointestinal (GI) physiology and nutrient transport, but also to indirect effects on immunoregulatory controls, including induction and stabilization of T regulatory cells (T _reg). Secreted bacterial metabolites such as short-chain fatty acids (SCFA) are under intense investigation as mediators of these effects. In contrast, folate (vitamin B9), an essential micronutrient, has attracted less attention, possibly because it exerts global physiological effects which are difficult to differentiate from specific effects on the immune system. Here, we review the role of folate in AD/AID with some emphasis on sight-threatening autoimmune uveitis. Since folate is required for the generation and maintenance of T _{reg ,} we propose that one mechanism for microbiome-based control of AD/AID is via folate-dependent induction of GI tract T _{reg ,} particularly colonic T _reg, via anergic T cells (T _an). Hence, folate supplementation has potential prophylactic and/or therapeutic benefit in AID/AD.

Down-regulated gga-miR-223 inhibits proliferation and induces apoptosis of MG-infected DF-1 cells by targeting FOXO3

Mycoplasma gallisepticum (MG) is a major poultry pathogen that can induce Chronic Respiratory Disease (CRD) in chickens, causing serious economic losses in the poultry industry worldwide. Increasing evidence suggests that microRNAs (miRNAs) act as a vital role in resisting microbial pathogenesis and maintaining cellular mechanism. Our previous miRNAs sequencing data showed that gga-miR-223 expression level significantly decreased in MG-infected chicken lungs. The aim of this study was to reveal the role of gga-miR-223 in MG-induced CRD progression. We found that gga-miR-223 was remarkably down regulated and forkhead box O3 (FOXO3) was up-regulated in both MG-infected chicken embryos lungs and the chicken embryonic fibroblast cell line (DF-1) by qPCR. FOXO3 was verified as the target gene of gga-miR-223 through bioinformatics analysis and dual-luciferase reporter assay. Further studies showed that overexpressed gga-miR-223 could promote cell proliferation, cell cycle, and inhibit cell apoptosis by notably promoting the expression of cell cycle marker genes cyclin-dependent kinase 1 (CDK1), cyclin-dependent kinase 6 (CDK6) and Cyclin D1 (CCND1) and inhibiting the expression of apoptosis markers Bcl-2-like 11(BIM), FAS ligand (FASLG) and TNF-related apoptosis-inducing ligand (TRAIL). As expected, FOXO3 knockdown group got similar results. Overexpression of gga-miR-223 observably promoted cell multiplication, cell cycle progression, and inhibited apoptosis of MG-infected DF-1 cells, while inhibited gga-miR-223 had the opposite effect. Taken together, upon MG-infection, downregulated gga-miR-223 could decrease proliferation, cycle progression, and increase apoptosis through directly targeting FOXO3 to exert an aggravating MG-infectious effect.

miRNAs Alter T Helper 17 Cell Fate in the Pathogenesis of Autoimmune Diseases

T helper 17 (Th17) cells are characterized by the secretion of the IL-17 cytokine and are essential for the immune response against bacterial and fungal infections. Despite the beneficial roles of Th17 cells, unrestrained IL-17 production can contribute to immunopathology and inflammatory autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease. Although these diverse outcomes are directed by the activation of Th17 cells, the regulation of Th17 cells is incompletely understood. The discovery that microRNAs (miRNAs) are involved in the regulation of Th17 cell differentiation and function has greatly improved our understanding of Th17 cells in immune response and disease. Here, we provide an overview of the biogenesis and function of miRNA and summarize the role of miRNAs in Th17 cell differentiation and function. Finally, we focus on recent advances in miRNA-mediated dysregulation of Th17 cell fate in autoimmune diseases.

Cytokines that Modulate the Differentiation of Th17 Cells in Autoimmune Uveitis

Increasing evidence has suggested that T helper 17 (Th17) cells play a central role in the pathogenesis of ocular immune disease. The association between pathogenic Th17 cells and the development of uveitis has been confirmed in experimental and clinical studies. Several cytokines affect the initiation and stabilization of the differentiation of Th17 cells. Therefore, understanding the mechanism of related cytokines in the differentiation of Th17 cells is important for exploring the pathogenesis and the potential therapeutic targets of uveitis. This article briefly describes the structures, mechanisms, and targeted drugs of cytokines-including interleukin (IL)-6, transforming growth factor-β1 (TGF-β1), IL-1β, IL-23, IL-27, IL-35, IL-2, IL-4, IL-21, and interferon (IFN)-γ-which have an important influence on the differentiation of Th17 cells and discusses their potential as therapeutic targets for treating autoimmune uveitis.

Deletion of Mir223 Exacerbates Lupus Nephritis by Targeting S1pr1 in Faslpr/lpr Mice

Objective

The micro RNAs (miRNAs) and their target mRNAs are differentially expressed in various immune-mediated cells. Here, we investigated the role of Mir223 and sphingosine-1-phosphate receptor 1 (S1pr1) in the pathogenesis of systemic lupus erythematosus.

Methods

We analyzed miRNA and mRNA profiling data of CD4+ splenic T cells derived from MRL/MpJ-Faslpr /J mice. We performed 3' untranslated region (UTR) luciferase reporter gene assay using human umbilical vein endothelial cells (HUVECs). We generated the B6-Mir223-/-Faslpr/lpr mice and the lupus phenotypes were analyzed.

Results

In CD4+ splenic T cells, we identified upregulation of miR-223-3p and downregulation of the possible target, S1pr1 by RNA sequencing of MRL/MpJ-Faslpr /J mice. The transfection with miR-223-3p mimic significantly suppressed a luciferase activity in HUVEC treated with a Lentivirus vector containing 3' UTR of S1pr1. The mRNA levels of S1pr1 were significantly decreased after miR-223-3p overexpression. In B6-Mir223-/-Faslpr/lpr mice, the proportion of CD3+ T cells, CD3+CD4-CD8- cells, B cells, plasma cells, and S1PR1+CD4+ T cells in the spleen was significantly increased compared with that in B6-Mir223+/+Faslpr/lpr mice by flow cytometry. B6-Mir223-/-Faslpr/lpr mice demonstrated the elevation of glomerular and renal vascular scores associated with enhanced intraglomerular infiltration of S1PR1+CD4+ T cells.

Conclusion

Unexpectedly, the deletion of Mir223 exacerbated the lupus phenotypes associated with increased population of S1PR1+CD4+ T in spleen and the enhanced infiltration of S1PR1+CD4+ T cells in inflamed kidney tissues, suggesting compensatory role of Mir223 in the pathogenesis of lupus nephritis.

MicroRNAs and Autoimmune-Mediated Eye Diseases

MicroRNAs (miRNAs) are evolutionarily conserved short non-coding RNAs that act at post-transcriptional regulation of gene expression by destroying target messenger RNA or inhibiting its translation. Recently, miRNAs have been identified as important regulators in autoimmunity. Aberrant expression and function of miRNAs can lead to dysfunction of immune system and mediate autoimmune disorders. Here, we summarize the roles of miRNAs that have been implicated in three representative ocular autoimmune disorders, including autoimmune uveitis, Grave's ophthalmopathy, and Sjögren's syndrome dry eye, and discuss the potential of miRNAs as biomarkers and therapeutic targets for the diagnosis and treatment of these diseases.

miR-182-5p inhibits the pathogenic Th17 response in experimental autoimmune uveitis mice via suppressing TAF15

BACKGROUND

CD4⁺ T helper 17 (Th17) cells play a contributory role in uveitis and other autoimmune disorders. However, less is understood about the contribution of microRNAs (miRNAs) in regulating the pathogenic Th17 response in uveitis.

METHODS

The in vivo experimental autoimmune uveitis (EAU) model was constructed in female C57BL/6 mice. Primary EAU mouse CD4⁺ T-cells and the murine T-cell line EL4 were used for in vitro experiments. miRNA mimic/inhibitor, lentiviral overexpression plasmids, and small interfering RNAs (siRNAs) were used to modulate miR-182-5p and TAF15 expression. CD4⁺ T-cells from healthy controls (HC, n = 15), active Behçet's disease with uveitis (BD, n = 15), or active sympathetic ophthalmia with uveitis (SO, n = 15) were analyzed for miR-182-5p, TAF15, and Th17 marker gene expression.

RESULTS

miR-182-5p was downregulated in EAU mouse-derived Th17 cells. miR-182-5p negatively regulated Th17 cell development in vitro. miR-182-5p mimic therapy in transplanted Th17 cells ameliorated EAU severity in vivo. Mechanistically, miR-182-5p directly inhibited the transcriptional initiator TATA-binding protein-associated factor 15 (TAF15, TAFII68). miR-182-5p's inhibition of TAF15 negatively regulated Th17 cell development by suppressing STAT3 phosphorylation. TAF15 and Th17 marker expression were positively correlated in CD4⁺ T-cells from BD and SO patients.

CONCLUSION

miR-182-5p mimic therapy inhibits the pathogenic Th17 response in EAU mice. miR-182-5p's inhibition of TAF15 negatively regulates Th17 cell development by suppressing STAT3 phosphorylation. As TAF15 shows a positive relationship with Th17 cell markers in uveitis patients, the miR-182-5p/TAF15 axis shows promise as a therapeutic target for uveitis.

MicroRNA-223 Regulates Retinal Function and Inflammation in the Healthy and Degenerating Retina

INTRODUCTION

MicroRNAs (miRNAs) are small, non-coding RNA molecules that have powerful regulatory properties, with the ability to regulate multiple messenger RNAs (mRNAs) and biological pathways. MicroRNA-223-3p (miR-223) is known to be a critical regulator of the innate immune response, and its dysregulation is thought to play a role in inflammatory disease progression. Despite miR-223 upregulation in numerous neurodegenerative conditions, largely in cells of the myeloid lineage, the role of miR-223 in the retina is relatively unexplored. Here, we investigated miR-223 in the healthy retina and in response to retinal degeneration.

METHODS

miR-223-null mice were investigated in control and photo-oxidative damage-induced degeneration conditions. Encapsulated miR-223 mimics were intravitreally and intravenously injected into C57BL/6J wild-type mice. Retinal functional responses were measured using electroretinography (ERG), while extracted retinas were investigated by retinal histology (TUNEL and immunohistochemistry) and molecular analysis (qPCR and FACS).

RESULTS

Retinal function in miR-223-/- mice was adversely affected, indicating that miR-223 may be critical in regulating the retinal response. In degeneration, miR-223 was elevated in the retina, circulating serum, and retinal extracellular vesicles. Conversely, retinal microglia and macrophages displayed a downregulation of miR-223. Further, isolated CD11b+ inflammatory cells from the retinas and circulation of miR-223-null mice showed an upregulation of pro-inflammatory genes that are critically linked to retinal inflammation and progressive photoreceptor loss. Finally, both local and systemic delivery of miR-223 mimics improved retinal function in mice undergoing retinal degeneration.

CONCLUSION

miR-223 is required for maintaining normal retinal function, as well as regulating inflammation in microglia and macrophages. Further investigations are required to determine the targets of miR-223 and their key biological pathways and interactions that are relevant to retinal diseases. Future studies should investigate whether sustained delivery of miR-223 into the retina is sufficient to target these pathways and protect the retina from progressive degeneration.

Circulating microRNA Expression Profiling Identifies miR-125a-5p Promoting T Helper 1 Cells Response in the Pathogenesis of Hashimoto's Thyroiditis

MicroRNAs (miRNAs) have emerged as key regulators of cellular processes by suppressing target mRNAs at the posttranscriptional level. However, little is known regarding the expression of miRNAs in peripheral blood mononuclear cells (PBMCs) from Hashimoto's thyroiditis (HT) patients. Therefore, 38 HT patients and 36 healthy volunteers were enrolled in this study to identify HT-mediated changes in miRNA expression. Over 1,000 dysregulated miRNAs and their biological functions in the HT patients were identified. Among them, miR-125a-5p expression was upregulated and inversely correlated with low levels of MAF, a transcription factor that inhibits Th1 cells activity and the production of IFN-γ. Luciferase assay results demonstrated that MAF is a direct target gene of miR-125a-5p. Moreover, the proportion of circulating Th1 cells and the transcript levels of IFN-γ were increased in the HT patients. MiR-125a-5p expression positively correlated with the proportion of circulating Th1 cells and the serum concentrations of anti-thyroperoxidase antibodies in the HT patients. Interestingly, knockdown of miR-125a-5p in CD4⁺ T cells resulted in an elevated level of MAF but decreased the proportion of Th1 cells and the transcript level of IFN-γ in vitro. Furthermore, upregulated miR-125a-5p and IFN-γ transcript levels and downregulated MAF expression were detected in thyroid tissues from HT patients. Receiver operating characteristic (ROC) curves suggested that miR-125a-5p has a crucial role in the HT. Our results demonstrate that the elevated levels of miR-125a-5p contribute to the Th1 cells response in the HT patients and may be involved in the pathogenesis of HT.

MicroRNA expression profile of Lacrimal Glands in rabbit autoimmune dacryoadenitis model

Purpose: To identify the differential expression of microRNAs (miRs) and the related gene networks and signal pathways in lacrimal glands (LGs) of rabbit autoimmune dacryoadenitis. Methods: Autoimmune dacryoadenitis in rabbits was induced by transferring activated peripheral blood lymphocytes (PBLs). The LGs of normal and model group rabbits were collected for small RNA sequencing. The most differentially expressed miRs were validated by quantitative real time-polymerase chain reaction (qRT-PCR). Further, bioinformatics analysis including target gene prediction, Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. Results: A total of 15 miRs were differentially expressed in the LGs of rabbit autoimmune dacryoadenitis relative to normal controls. GO and KEGG analysis revealed that most target genes of these dysregulated miRs were implicated in MAPK signaling pathway. Conclusion: Our results showed for the first time the differentially expressed miRs and the related pathways involved in the pathogenesis of rabbit autoimmune dacryoadenitis. These results may contribute to elucidating molecular pathogenesis of Sjögren's syndrome (SS) dry eye.