T cells are influenced by a long non-coding RNA in the autoimmune associated PTPN2 locus

LncRNA HOTTIP regulates TLR4 promoter methylation by recruiting H3K4 methyltransferase MLL1 to affect apoptosis and inflammatory response of fibroblast-like synoviocyte in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease, and the role of HOXA transcript at the distal tip (HOTTIP) in its pathogenesis remains underexplored. This study investigates the mechanism by which HOTTIP influences apoptosis and the inflammatory response of fibroblast-like synoviocytes (FLS). An RA mouse model was established, and clinical scores were analyzed. Pathological changes in synovial tissues, bone mineral density (BMD) of the paws, serum tartrate-resistant acid phosphatase (TRAP) activity, and TNF-α and IL-1β levels were assessed. FLS were transfected, and cell proliferation and apoptosis were examined. The RNA-pull-down assay determined HOTTIP's interaction with mixed-lineage leukemia 1 (MLL1), while RNA immunoprecipitation assay measured HOTTIP expression pulled down by MLL1. The levels of MLL1 and toll-like receptor 4 (TLR4) after MLL1 overexpression based on HOTTIP silencing were determined. Chromatin immunoprecipitation (ChIP) was performed with H3K4me3 as an antibody, followed by the evaluation of TLR4 expression. HOTTIP expression was elevated in RA mouse synovial tissues. Inhibition of HOTTIP led to reduced clinical scores, inflammatory infiltration, synovial hyperplasia, TRAP activity, and TNF-α and IL-1β levels, along with increased BMD. In vitro Interference with HOTTIP suppressed RA-FLS apoptosis and inflammation. HOTTIP upregulated TLR4 expression by recruiting MLL1 to facilitate TLR4 promoter methylation. MLL1 overexpression reversed HOTTIP silencing-mediated repression of RA-FLS apoptosis. Activation of H3K4 methylation counteracted HOTTIP knockout, ameliorating the inflammatory response. HOTTIP regulates TLR4 expression by recruiting MLL1, leading to TLR4 promoter methylation, thereby suppressing RA-FLS proliferation and inducing cell apoptosis and inflammatory response in RA.

Long Non-Coding RNAs and Their "Discrete" Contribution to IBD and Johne's Disease-What Stands out in the Current Picture? A Comprehensive Review

Non-coding RNAs (ncRNA) have paved the way to new perspectives on the regulation of gene expression, not only in biology and medicine, but also in associated fields and technologies, ensuring advances in diagnostic means and therapeutic modalities. Critical in this multistep approach are the associations of long non-coding RNA (lncRNA) with diseases and their causal genes in their networks of interactions, gene enrichment and expression analysis, associated pathways, the monitoring of the involved genes and their functional roles during disease progression from one stage to another. Studies have shown that Johne's Disease (JD), caused by Mycobacterium avium subspecies partuberculosis (MAP), shares common lncRNAs, clinical findings, and other molecular entities with Crohn's Disease (CD). This has been a subject of vigorous investigation owing to the zoonotic nature of this condition, although results are still inconclusive. In this review, on one hand, the current knowledge of lncRNAs in cells is presented, focusing on the pathogenesis of gastrointestinal-related pathologies and MAP-related infections and, on the other hand, we attempt to dissect the associated genes and pathways involved. Furthermore, the recently characterized and novel lncRNAs share common pathologies with IBD and JD, including the expression, molecular networks, and dataset analysis results. These are also presented in an attempt to identify potential biomarkers pertinent to cattle and human disease phenotypes.

Regulation of T cell differentiation and function by long noncoding RNAs in homeostasis and cancer

Long noncoding RNAs (lncRNAs) increase in genomes of complex organisms and represent the largest group of RNA genes transcribed in mammalian cells. Previously considered only transcriptional noise, lncRNAs comprise a heterogeneous class of transcripts that are emerging as critical regulators of T cell-mediated immunity. Here we summarize the lncRNA expression landscape of different T cell subsets and highlight recent advances in the role of lncRNAs in regulating T cell differentiation, function and exhaustion during homeostasis and cancer. We discuss the different molecular mechanisms of lncRNAs and highlight lncRNAs that can serve as novel targets to modulate T cell function or to improve the response to cancer immunotherapies by modulating the immunosuppressive tumor microenvironment.

Long noncoding RNA00324 is involved in the inflammation of rheumatoid arthritis by targeting miR-10a-5p via the NF-κB pathway

BACKGROUND

Altered expressions of genes in immune cells and synovial tissues are involved in the pathology of rheumatoid arthritis (RA). Long noncoding RNAs act as competing endogenous RNAs and can cause immune disorders. The goal of this study was to reveal the association between noncoding RNA linc00324 and RA, and a plausible action mechanism was proposed.

METHODS

RT-qPCR was used to evaluate the expression of linc00324 in peripheral blood mononuclear cells isolated from 50 RA patients and 50 healthy controls, and the correlations between linc00324 level and the clinical indicators were analyzed. Flow cytometry was used to characterize CD4⁺ T cells. The effects of linc00324 on cytokine production and cell proliferation of CD4⁺ T cells were evaluated by ELISA assay and Western blot. The interaction between linc00324 and miR-10a-5p was investigated by RNA immunoprecipitation and dual-luciferase assays.

RESULTS

The linc00324 expression was significantly enhanced in RA patients, and linc00324 expression was positively correlated with rheumatoid factor and CD4⁺ T cells. Overexpression of linc00324 promoted CD4⁺ T cells proliferation, and enhanced chemokine MIP-1α secretion and NF-κB phosphorylation level, whereas knockout of linc00324 blocked CD4⁺ T cell proliferation and NF-κB phosphorylation. Overexpression of miR-10a-5p led to the decrease of CD4⁺ T cells proliferation and NF-κB phosphorylation, and reversed the effects of linc00324 on cell proliferation and NF-κB activity.

CONCLUSION

Linc00324 was upregulated in RA and may exaggerate inflammation by targeting miR-10a-5p through NF-κB signaling pathway.

Rheumatoid arthritis and non-coding RNAs; how to trigger inflammation

Rheumatoid arthritis (RA) is a systemic and chronic inflammatory disease categorized by continuous synovitis in the joints and systemic inflammatory responses that can cause lifelong disability. The major cause of RA is the dysregulation of the immune response. The development of RA disease includes multiplex association of several interleukins and cells, which leads to synovial cell growth, cartilage and bone damage. The primary stage of RA disease is related to the modification of both the innate and adaptive immune systems, which leads to the formation of autoantibodies. This process results in many damaged molecules and epitope spreading. Both the innate (e.g., dendritic cells, macrophages, and neutrophils) and acquired immune cells (e.g., T and B lymphocytes) will increase and continue the chronic inflammatory condition in the next stages of the RA disease. In recent years, non-coding RNAs have been proved as significant controllers of biological functions, especially immune cell expansion and reactions. Non-coding RNAs were primarily containing microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). Various studies confirmed non-coding RNAs as hopeful markers for diagnosing and curing RA. This review will describe and cover existing knowledge about RA pathogenesis, which might be favorable for discovering possible ncRNA markers for RA.

Long noncoding RNA LINC01882 ameliorates aGVHD via skewing CD4+ T cell differentiation toward Treg cells

Acute graft-versus-host disease (aGVHD) is a severe T cell-mediated immune response after allogeneic hematopoietic stem cell transplantation (allo-HSCT), the molecular mechanisms remain to be elucidated and novel treatments are necessary to be developed. In the present study, we found that the expression of long noncoding RNA (lncRNA) LINC01882 decreased significantly in the peripheral blood CD4⁺ T lymphocytes of patients with aGVHD than non-aGVHD patients. In addition, lncRNA LINC01882 overexpression promoted Treg differentiation but exhibited no effects on Th17 percentages, while its knockdown resulted in opposite effects. Mechanistically, lncRNA LINC01882 could competitively bind with let-7b-5p to prevent the degradation of its target gene smad2, which acts as a promoter in Treg differentiation. Furthermore, the mice cotransplanted with LINC01882-overexpressed CD4⁺ T cells with PBMCs had a lower histological GVHD score and higher survival rate compared with control mice. In conclusion, our study discloses a novel LINC01882/let-7b-5p/smad2 pathway in the modulation of aGVHD and indicates that lncRNA LINC01882 could be a promising biomarker and therapeutic target for patients with aGVHD.

Non-coding RNAs in immunoregulation and autoimmunity: Technological advances and critical limitations

Immune cell function is critically dependent on precise control over transcriptional output from the genome. In this respect, integration of environmental signals that regulate gene expression, specifically by transcription factors, enhancer DNA elements, genome topography and non-coding RNAs (ncRNAs), are key components. The first three have been extensively investigated. Even though non-coding RNAs represent the vast majority of cellular RNA species, this class of RNA remains historically understudied. This is partly because of a lag in technological and bioinformatic innovations specifically capable of identifying and accurately measuring their expression. Nevertheless, recent progress in this domain has enabled a profusion of publications identifying novel sub-types of ncRNAs and studies directly addressing the function of ncRNAs in human health and disease. Many ncRNAs, including circular and enhancer RNAs, have now been demonstrated to play key functions in the regulation of immune cells and to show associations with immune-mediated diseases. Some ncRNAs may function as biomarkers of disease, aiding in diagnostics and in estimating response to treatment, while others may play a direct role in the pathogenesis of disease. Importantly, some are relatively stable and are amenable to therapeutic targeting, for example through gene therapy. Here, we provide an overview of ncRNAs and review technological advances that enable their study and hold substantial promise for the future. We provide context-specific examples by examining the associations of ncRNAs with four prototypical human autoimmune diseases, specifically rheumatoid arthritis, psoriasis, inflammatory bowel disease and multiple sclerosis. We anticipate that the utility and mechanistic roles of these ncRNAs in autoimmunity will be further elucidated in the near future.

lncRNA-mediated synovitis in rheumatoid arthritis: A perspective for biomarker development

Long noncoding RNAs (lncRNAs) are a regulatory class of noncoding RNAs with a wide range of activities such as transcriptional and post-transcriptional regulations. Emerging evidence has demonstrated that various lncRNAs contribute to the initiation and progression of Rheumatoid Arthritis (RA) through distinctive mechanisms. The present study reviews the recent findings on lncRNA role in RA development. It focuses on the involvement of different lncRNAs in the main steps of RA pathogenesis including T cell activation, cytokine dysregulation, fibroblast-like synoviocyte (FLS) activation and joint destruction. Besides, it discusses the current findings on RA diagnosis and the potential of lncRNAs as diagnostic, prognostic and predictive biomarkers in Rheumatology clinic.

LncRNAs and Rheumatoid Arthritis: From Identifying Mechanisms to Clinical Investigation

Rheumatoid arthritis (RA) is a systemic chronic autoinflammatory disease, and the synovial hyperplasia, pannus formation, articular cartilage damage and bone matrix destruction caused by immune system abnormalities are the main features of RA. The use of Disease Modifying Anti-Rheumatic Drugs (DMARDs) has achieved great advances in the therapy of RA. Yet there are still patients facing the problem of poor response to drug therapy or drug intolerance. Current therapy methods can only moderate RA progress, but cannot stop or reverse the damage it has caused. Recent studies have reported that there are a variety of long non-coding RNAs (LncRNAs) that have been implicated in mediating many aspects of RA. Understanding the mechanism of LncRNAs in RA is therefore critical for the development of new therapy strategies and prevention strategies. In this review, we systematically elucidate the biological roles and mechanisms of action of LncRNAs and their mechanisms of action in RA. Additionally, we also highlight the potential value of LncRNAs in the clinical diagnosis and therapy of RA.

Genetics of rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease involving symmetric joints and is generally characterized by persistent pain, tenderness, and destruction of joints. The vast majority of RA patients produce autoantibodies, and immune cell involvement in disease development is well recognized, as is the contribution of other types of cells in synovial tissue, like fibroblasts. It is known that there are major genetic associations with the HLA locus, while multiple non-HLA genetic variants display relatively low risk of RA. Both HLA and non-HLA associations suggest that the profiles of genetic associations for autoantibody-positive vs. autoantibody-negative RA are different. Several alleles of HLA-DRB1 are associated with high risk for autoantibody-positive RA, with the strongest risk characterized by valine at position 11 of the protein sequence (HLA-DRB1*04 and *10 alleles). There is a strong protective effect for the risk of autoantibody-positive RA associated with HLA-DRB1*13 alleles. Although major genetic associations have been known for several years, understanding of the specific mechanisms in the development of increased risk of RA for these variations is work in progress. Current studies focus on the binding of immune receptors involved in recognition of putative peptides in activation of T cells, as well as investigation of cell signaling mechanisms. At least a part of RA risk could be explained by gene-gene and gene-environment interactions. There are currently more than 150 candidate loci with polymorphisms that associate with RA, mainly related to seropositive disease, and new discoveries are anticipated in the future from investigation of diverse human populations. This new research will help create a strong foundation for the continuing process of integrating genetic, epigenetic, transcriptomic, and proteomic data in studies of RA.

Dysregulation of lncRNAs in Rheumatoid Arthritis: Biomarkers, Pathogenesis and Potential Therapeutic Targets

Rheumatoid arthritis (RA) is a chronic autoimmune disease of unknown etiology, mainly manifested by persistent abnormal proliferation of fibroblast-like synoviocytes (FLSs), inflammation, synovial hyperplasia and cartilage erosion, accompanied by joint swelling and joint destruction. Abnormal expression or function of long noncoding RNAs (lncRNAs) are closely related to human diseases, including cancers, mental diseases, autoimmune diseases and others. The abnormal sequence and spatial structure of lncRNAs, the disorder expression and the abnormal interaction with the binding protein will lead to the change of gene expression in the way of epigenetic modification. Increasing evidence demonstrated that lncRNAs were involved in the activation of FLSs, which played a key role in the pathogenesis of RA. In this review, the research progress of lncRNAs in the pathogenesis of RA was systematically summarized, including the role of lncRNAs in the diagnosis of RA, the regulatory mechanism of lncRNAs in the pathogenesis of RA, and the intervention role of lncRNAs in the treatment of RA. Furthermore, the activated signal pathways, the role of DNA methylation and other mechanism have also been overview in this review.

lncRNAs in T lymphocytes: RNA regulation at the heart of the immune response

Genome-wide analyses in the last decade have uncovered the presence of a large number of long non-protein-coding transcripts that show highly tissue- and state-specific expression patterns. High-throughput sequencing analyses in diverse subsets of immune cells have revealed a complex and dynamic expression pattern for these long noncoding RNAs (lncRNAs) that correlate with the functional states of immune cells. Although the vast majority of lncRNAs expressed in immune cells remain unstudied, functional studies performed on a small subset have indicated that their state-specific expressions pattern frequently has a regulatory impact on the function of immune cells. In vivo and in vitro studies have pointed to the involvement of lncRNAs in a wide variety of cellular processes, including both the innate and adaptive immune response through mechanisms ranging from epigenetic and transcriptional regulation to sequestration of functional molecules in subcellular compartments. This review will focus mainly on the role of lncRNAs in CD4⁺ and CD8⁺ T cells, which play pivotal roles in adaptive immunity. Recent studies have pointed to key physiological functions for lncRNAs during several developmental and functional stages of the life cycle of lymphocytes. Although lncRNAs play important physiological roles in lymphocytic response to antigenic stimulation, differentiation into effector cells, and secretion of cytokines, their dysregulated expression can promote or sustain pathological states such as autoimmunity, chronic inflammation, cancer, and viremia. This, together with their highly cell type-specific expression patterns, makes lncRNAs ideal therapeutic targets and underscores the need for additional studies into the role of these understudied transcripts in adaptive immune response.

LncRNA-AK149641 associated with airway inflammation in an OVA-induced asthma mouse model

Asthma is defined as a heterogeneous disease, usually characterized by chronic airway inflammation. Long noncoding RNAs (lncRNAs) play important roles in various biological processes. To know more about the relationships between lncRNAs and asthma, gene microarray analysis was performed to screen differentially expressed lncRNAs between the lung tissue of ovalbumin (OVA) mice and control mice. Further studies showed that downregulating differentially expressed lncRNA-AK149641 by adeno-associated virus 6 (AAV6) in OVA mice inhibited airway inflammation, with improved airway compliance and resistance, diminished infiltration of inflammatory cells, as well as less secretions of mucus, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Moreover, the activity of nuclear factor-kappa B (NF-κB) in the lung tissue was reduced after downregulating lncRNA-AK149641. In conclusion, we proposed that downregulation of lncRNA-AK149641 attenuated the airway inflammatory response in an OVA-induced asthma mouse model, probably in association with modulation of the NF-κB signaling pathway.

Long Noncoding RNAs and Circular RNAs in Autoimmune Diseases

Immune responses are essential for the clearance of pathogens and the repair of injured tissues; however, if these responses are not properly controlled, autoimmune diseases can occur. Autoimmune diseases (ADs) are a family of disorders characterized by the body's immune response being directed against its own tissues, with consequent chronic inflammation and tissue damage. Despite enormous efforts to identify new drug targets and develop new therapies to prevent and ameliorate AD symptoms, no definitive solutions are available today. Additionally, while substantial progress has been made in drug development for some ADs, most treatments only ameliorate symptoms and, in general, ADs are still incurable. Hundreds of genetic loci have been identified and associated with ADs by genome-wide association studies. However, the whole list of molecular factors that contribute to AD pathogenesis is still unknown. Noncoding (nc)RNAs, such as microRNAs, circular (circ)RNAs, and long noncoding (lnc)RNAs, regulate gene expression at different levels in various diseases, including ADs, and serve as potential drug targets as well as biomarkers for disease progression and response to therapy. In this review, we will focus on the potential roles and genetic regulation of ncRNA in four autoimmune diseases-systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, and type 1 diabetes mellitus.

Which long noncoding RNAs and circular RNAs contribute to inflammatory bowel disease?

Inflammatory bowel disease (IBD), a chronic relapsing gastrointestinal inflammatory disease, mainly comprises ulcerative colitis (UC) and Crohn’s disease (CD). Although the mechanisms and pathways of IBD have been widely examined in recent decades, its exact pathogenesis remains unclear. Studies have focused on the discovery of new therapeutic targets and application of precision medicine. Recently, a strong connection between IBD and noncoding RNAs (ncRNAs) has been reported. ncRNAs include microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). The contributions of lncRNAs and circRNAs in IBD are less well-studied compared with those of miRNAs. However, lncRNAs and circRNAs are likely to drive personalized therapy for IBD. They will enable accurate diagnosis, prognosis, and prediction of therapeutic responses and promote IBD therapy. Herein, we briefly describe the molecular functions of lncRNAs and circRNAs and provide an overview of the current knowledge of the altered expression profiles of lncRNAs and circRNAs in patients with IBD. Further, we discuss how these RNAs are involved in the nosogenesis of IBD and are emerging as biomarkers.

The effects of long non-coding ribonucleic acids on various cellular components in rheumatoid arthritis

RA is a chronic, autoimmune-mediated inflammatory pathology. Long non-coding RNAs (lncRNAs) are a novel group of non-coding RNAs with a length of >200 nucleotides. There are reports emerging that suggest that lncRNAs participate in establishing and sustaining autoimmune diseases, including RA. In this review article, we highlight the functions of lncRNAs in different cell types in RA. Our review indicates that lncRNAs affect various cellular components and are novel candidates that could constitute promising targets for the diagnosis and treatment of RA.

Detection and Comparative Analysis of Methylomic Biomarkers of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a common autoimmune disorder influenced by both genetic and environmental factors. To investigate possible contributions of DNA methylation to the etiology of RA with minimum confounding genetic heterogeneity, we investigated genome-wide DNA methylation in disease-discordant monozygotic twin pairs. This study hypothesized that methylomic biomarkers might facilitate accurate RA detection. A comprehensive series of biomarker detection algorithms were utilized to find the best methylomic biomarkers for detecting RA patients using the methylomic data of the peripheral blood samples. The best model achieved 100.00% in accuracy (Acc) with 81 methylomic biomarkers and a 10-fold cross-validation (10FCV) strategy. Some of the methylomic biomarkers were experimentally confirmed to be associated with the onset or development of RA. It is also interesting to observe that many of the detected biomarkers were from chromosome Y, supporting the knowledge that RA has a significant gender discrepancy.

Tissue alarmins and adaptive cytokine induce dynamic and distinct transcriptional responses in tissue-resident intraepithelial cytotoxic T lymphocytes

The respective effects of tissue alarmins interleukin (IL)-15 and interferon beta (IFNβ), and IL-21 produced by T cells on the reprogramming of cytotoxic T lymphocytes (CTLs) that cause tissue destruction in celiac disease is poorly understood. Transcriptomic and epigenetic profiling of primary intestinal CTLs showed massive and distinct temporal transcriptional changes in response to tissue alarmins, while the impact of IL-21 was limited. Only anti-viral pathways were induced in response to all the three stimuli, albeit with differences in dynamics and strength. Moreover, changes in gene expression were primarily independent of changes in H3K27ac, suggesting that other regulatory mechanisms drive the robust transcriptional response. Finally, we found that IL-15/IFNβ/IL-21 transcriptional signatures could be linked to transcriptional alterations in risk loci for complex immune diseases. Together these results provide new insights into molecular mechanisms that fuel the activation of CTLs under conditions that emulate the inflammatory environment in patients with autoimmune diseases.

Non-coding RNAs in Rheumatoid Arthritis: From Bench to Bedside

Rheumatoid arthritis is a common systemic and autoimmune disease characterized by symmetrical and inflammatory destruction of distal joints. Its primary pathological characters are synovitis and vasculitis. Accumulating studies have implicated the critical role of non-coding RNAs (ncRNAs) in inflammation and autoimmune regulation, primarily including microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). NcRNAs are significant regulators in distinct physiological and pathophysiological processes. Many validated non-coding RNAs have been identified as promising biomarkers for the diagnosis and treatment of RA. This review will shed some light on RA pathogenesis and be helpful for identifying potential ncRNA biomarkers for RA.

Silencing of Long Non-coding RNA HOTTIP Reduces Inflammation in Rheumatoid Arthritis by Demethylation of SFRP1

Accumulating evidence suggests long non-coding RNAs (lncRNAs) play crucial roles in the pathogenesis of rheumatoid arthritis (RA). Here, we aimed to define the role of HOXA transcript at the distal tip (HOTTIP) in RA pathogenesis in relation to SFRP1 methylation and Wnt signaling pathway. HOTTIP was found highly expressed, and SFRP1 was hypermethylated in RA synovial fibroblasts (RASFs). Next, gain- or loss-of-function experiments were conducted in RASFs to explore the effects of HOTTIP on the biological behaviors of RASFs. Silencing of HOTTIP or overexpression of SFRP1 inhibited RASF proliferation, invasion, and migration, while enhancing apoptosis. The relationship among HOTTIP, SFRP1, and Dnmt3b was determined using methylation-specific PCR (MSP), bisulfite sequencing PCR (BSP), RNA pull-down, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP) assays. The regulatory mechanisms of HOTTIP/Dnmt3b/SFRP1 were explored by altering their expression in RASFs. It was noted that HOTTIP could induce SFRP1 promoter methylation through recruitment of Dnmt3b and activate the Wnt signaling pathway. Finally, a rat RA model was established in order to evaluate the in vivo effects of HOTTIP and SFRP1, which suggested that HOTTIP silencing or SFRP1 elevation inhibited the progression of RA in vivo. Our key findings demonstrate the anti-inflammatory ability of HOTTIP silencing in RA through SFRP1 promoter demethylation. These findings support HOTTIP as a candidate anti-arthritis target.

Identification of PBMC-expressed miRNAs for rheumatoid arthritis

Post-transcriptional regulation by miRNAs plays an important role in the pathogenesis of rheumatoid arthritis (RA), however, the roles of specific miRNAs in RA pathogenesis remain largely unclear. This study performed dual-omics (miRNA and mRNA) integration analysis and in-depth cellular and molecular functional exploration to identify novel RA-associated miRNAs and to understand their underlying pathogenic mechanism. Based on the miRNA and mRNA expression profiles in peripheral blood mononuclear cells (PBMCs) from a discovery sample set (25 RA cases and 18 healthy controls), 18 differentially expressed miRNAs (DEMIRs) (|Fold-change|>2 and P < 0.05) were identified and corresponding interaction networks of DEMIRs and mRNA were constructed. After the expression validation of the DEMIRs in a validation sample set (35 RA cases and 35 healthy controls), miR-99b-5p was highlighted. The over-expression of newly discovered miR-99b-5p is able to suppress T cell apoptosis, promote cell proliferation and activation, increase expression of proinflammatory cytokines (IL-2, IL-6, TNF-α, and IFN-γ), and inhibit expression of its target genes mTOR and RASSF4. This study comprehensively identified PBMC-expressed miRNAs along with corresponding regulatory networks significant for RA and discovered miR-99b-5p as a novel post-transcriptional mediator involved in RA pathogenesis. The findings improved our understanding of RA pathogenesis and provided novel insights into the molecular mechanisms underlying RA pathogenesis.