Exploring the Role of Non-Coding RNAs in the Pathophysiology of Systemic Lupus Erythematosus

A novel long noncoding RNA ENST00000597482 serves as a potential biomarker for disease activity and diagnosis of systemic lupus erythematosus

OBJECTIVES

Emerging evidence indicate that long noncoding RNAs (lncRNAs) may play an important role in the pathogenesis of systemic lupus erythematosus (SLE) however, the contribution of lncRNAs to SLE remains largely unclear. Our study aimed to explore the lncRNA expression profiles in peripheral blood mononuclear cells (PBMCs) from SLE patients.

METHODS

LncRNA sequencing was used to detect differentially expressed genes in PBMCs from 5 SLE-MIX samples and 3 healthy controls (HC)-MIX samples, and the expression of selected lncRNAs was further verified by real-time quantitative polymerase chain reaction (RT‒qPCR). The correlation of lncRNA expression with laboratory indicators as well the SLE disease activity index 2000 (SLEDAI‒2K) score from 72 SLE patients was assessed by Spearman's test. The association between lncRNA ENST00000597482 and organ involvement in SLE patients was determined by the Mann‒Whitney U test. Moreover, lymphocyte subsets in peripheral blood from SLE patients were measured by flow cytometry. In addition, the diagnostic value of lncRNAs in predicting SLE was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

The lncRNA expression profiles demonstrated 218 differentially expressed lncRNAs, including 121 upregulated genes and 97 downregulated genes, in PBMCs from SLE patients compared to HCs. Among the 10 candidate genes selected, only lncRNA ENST00000597482, which was lower in SLE PBMCs than in HCs, was consistent with the sequencing results. LncRNA ENST00000597482 expression was negatively correlated with SLEDAI-2K score and the titres of ANA antibodies and anti-double-stranded DNA (anti-dsDNA) antibodies. Of note, SLE patients with lower expression of lncRNA ENST00000597482 were prone to develop organ involvement. Furthermore, lncRNA ENST00000597482 exhibited potential diagnostic value in differentiating SLE patients from HCs.

CONCLUSIONS

LncRNA ENST00000597482 expression was lower in PBMCs from SLE patients than HCs and was negatively correlated with the SLEDAI-2K score and autoantibody titres. In addition, lncRNA ENST00000597482 could act as a novel biomarker for disease activity and diagnosis of SLE.

tRF-His-GTG-1 enhances NETs formation and interferon-α production in lupus by extracellular vesicle

BACKGROUND

Hyperactive neutrophil extracellular traps (NETs) formation plays a crucial role in active severe systemic lupus erythematosus (SLE). However, what triggers the imbalance in dysregulated NETs formation in SLE is elusive. Transfer RNA-derived small RNAs (tsRNAs) are novel non-coding RNAs, which participate in various cellular processes. We explore the role of tsRNAs on NETs formation in SLE.

METHODS

We analyzed the levels of NETs DNA and platelet-derived extracellular vesicles (pEVs) from 50 SLE patients and 20 healthy control subjects. The effects of pEVs on NETs formation were evaluated by using immunofluorescence assay and myeloperoxidase-DNA PicoGreen assay. The regulatory mechanism of pEVs on NETs formation and inflammatory cytokines production were investigated using an in vitro cell-based assay.

RESULTS

Increased circulating NETs DNA and pEVs were shown in SLE patients and were associated with disease activity (P < 0.005). We demonstrated that SLE patient-derived immune complexes (ICs) induced platelet activation, followed by pEVs release. ICs-triggered NETs formation was significantly enhanced in the presence of pEVs through Toll-like receptor (TLR) 8 activation. Increased levels of tRF-His-GTG-1 in pEVs and neutrophils of SLE patients were associated with disease activity. tRF-His-GTG-1 interacted with TLR8 to prime p47phox phosphorylation in neutrophils, resulting in reactive oxygen species production and NETs formation. Additionally, tRF-His-GTG-1 modulated NF-κB and IRF7 activation in neutrophils upon TLR8 engagement, resulting IL-1β, IL-8, and interferon-α upregulation, respectively.

CONCLUSIONS

The level of tRF-His-GTG-1 was positively correlated with NETs formation in SLE patients; tRF-His-GTG-1 inhibitor could efficiently suppress ICs-triggered NETs formation/hyperactivation, which may become a potential therapeutic target.

Long noncoding nuclear enriched abundant transcript 1_2 is a promising biomarker for childhood-onset systemic lupus erythematosus

Importance

Systemic lupus erythematosus (SLE) is a diffuse connective tissue disease with complex clinical manifestations and prolonged course. The early diagnosis and condition monitoring of SLE are crucial to disease prognosis.

Objective

To assess the diagnostic value of long noncoding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) in childhood-onset SLE (cSLE).

Methods

Fifty-seven children diagnosed with SLE, 40 children diagnosed with juvenile idiopathic arthritis (JIA), and 40 healthy children were included. Peripheral blood samples from each patient were collected. A quantitative polymerase chain reaction was used to confirm the expression of lncNEAT1_1 and lncNEAT1_2 in peripheral blood. Associations among parameters were analyzed using the Mann-Whitney U test or independent sample t-test.

Results

The expression of both lncNEAT1_1 and lncNEAT1_2 in patients with cSLE were significantly higher than that of healthy control and patients with JIA. Receiver operating characteristic curves revealed an area under the curve (AUC) of 0.633 (95% confidence interval [CI], 0.524-0.742; P = 0.024) for lncNEAT1_1. The AUC of lncNEAT1_2 was 0.812 (95% CI, 0.727-0.897; P < 0.0001) to discriminate individuals with cSLE from health control and children with JIA with a sensitivity of 0.622 and a specificity of 0.925. Moreover, lncNEAT1_2 expression was higher in patients with cSLE presenting with fever, lupus nephritis, elevated erythrocyte sedimentation rate, active disease activity, and decreased C3 level, compared with those without these conditions. However, no similar correlation was observed for lncNEAT1_1.

Interpretation

The expression of lncNEAT1_2 was significantly elevated in children with SLE, especially those with fever, renal involvement, and low C3 levels. These findings suggest that lncNEAT1_2 may represent a potential biomarker for cSLE.

Genetic interrogation for sequence and copy number variants in systemic lupus erythematosus

Early-onset systemic lupus erythematosus presents with a more severe disease and is associated with a greater genetic burden, especially in patients from Black, Asian or Hispanic ancestries. Next-generation sequencing techniques, notably whole exome sequencing, have been extensively used in genomic interrogation studies to identify causal disease variants that are increasingly implicated in the development of autoimmunity. This Review discusses the known casual variants of polygenic and monogenic systemic lupus erythematosus and its implications under certain genetic disparities while suggesting an age-based sequencing strategy to aid in clinical diagnostics and patient management for improved patient care.

Long Non-Coding RNA TUG1 Gene Polymorphism and TUG1 Expression Level as Molecular Biomarkers of Systemic Lupus Erythematosus and Lupus Nephritis

Long non-coding RNA (lncRNA) TUG1 acts as a proto-oncogene, allowing the proliferation of tumor cells, and it has been related to inflammation. Therefore, we aimed in this study to investigate for the first time the role of TUG1 gene polymorphism and the TUG1 level as biomarkers in systemic lupus erythematosus (SLE) and their link to lupus nephritis 145 SLE. A total of 145 healthy controls were subjected to clinical and laboratory evaluation. The disease activity was assessed by the SLE disease activity index (SLEDAI) score. SLE patients were divided into two subgroups according to the presence of lupus nephritis. The TUG1 gene polymorphisms rs5749201 and rs886471 were determined by Sanger sequencing, and TUG1 expression was assessed by qRT-PCR. There was a significant increase in the risk of SLE AA, TA, dominant genotypes, and the A allele of rs5749201 (p < 0.001) by 4.9-, 10.1-, 6.5-, and 2.5-fold in comparison to the relative control. GG and TG, dominant genotypes and the G allele of rs886471 (p < 0.01) increased the risk by 5.09-, 11.9-, 6.5-, and 2.6-fold. AA, A allele, dominant and recessive rs5749201genotypes increased the risk of lupus nephritis by 16.6-, 7.4-, 7.1-, and 12.2-fold, respectively (p < 0.05). GG, dominant and recessive genotypes, and the G allele of rs886471 increased the risk of lupus nephritis by 17.04-, 7.8-, 9.4-, and 6.08-fold, respectively (p < 0.05). Additionally, the AG haplotype increased the risk of SLE and lupus nephritis by 2.7- and 7.8-fold, respectively. The AA rs5749201 and GG rs886471 variants are significantly associated with more severe disease (p < 0.001). TUG1 expression was significantly higher in SLE than in the control and in the lupus nephritis than in non-lupus nephritis cases (p < 0.05). Interestingly, AA rs5749201 and GG rs886471 were significantly associated with higher TUG1 levels (p < 0.001). It was also found that AA rs5749201 and high SLEDAI were predictors of lupus nephritis. Overall, our findings illustrated for the first time that TUG1 gene rs5749201 and rs886471 variants were associated with increased risk of SLE, more severe disease, and lupus nephritis, and the TUG1 level could be used as a diagnostic biomarker of SLE and lupus nephritis.

Long noncoding RNA SNHG16 regulates TLR4-mediated autophagy and NETosis formation in alveolar hemorrhage associated with systemic lupus erythematosus

BACKGROUND

Dysregulated long noncoding RNA (lncRNA) expression with increased apoptosis has been demonstrated in systemic lupus erythematosus (SLE) patients with alveolar hemorrhage (AH). SNHG16, a lncRNA, can enhance pulmonary inflammation by sponging microRNAs, and upregulate toll-like receptor 4 (TLR4) expression via stabilizing its mRNAs. TRAF6, a TLR4 downstream signal transducer, can induce autophagy and NETosis formation. In this study, we investigated whether SNHG16 could regulate TLR4-mediated autophagy and NETosis formation in SLE-associated AH.

METHODS

Expression of SNHG16, TLR4 and TRAF6 and cell death processes were examined in lung tissues and peripheral blood (PB) leukocytes from AH patients associated with SLE and other autoimmune diseases, and in the lungs and spleen from a pristane-induced C57BL/6 mouse AH model. SNHG16-overexpressed or -silenced alveolar and myelocytic cells were stimulated with lipopolysaccharide (LPS), a TLR4 agonist, for analyzing autophagy and NETosis, respectively. Pristane-injected mice received the intra-pulmonary delivery of lentivirus (LV)-SNHG16 for overexpression and prophylactic/therapeutic infusion of short hairpin RNA (shRNA) targeting SNHG16 to evaluate the effects on AH. Renal SNHG16 expression was also examined in lupus nephritis (LN) patients and a pristane-induced BALB/c mouse LN model.

RESULTS

Up-regulated SNHG16, TLR4 and TRAF6 expression with increased autophagy and NETosis was demonstrated in the SLE-AH lungs. In such patients, up-regulated SNHG16, TLR4 and TRAF6 expression was found in PB mononuclear cells with increased autophagy and in PB neutrophils with increased NETosis. There were up-regulated TLR4 expression and increased LPS-induced autophagy and NETosis in SNHG16-overexpressed cells, while down-regulated TLR4 expression and decreased LPS-induced autophagy and NETosis in SNHG16-silenced cells. Pristane-injected lung tissues had up-regulated SNHG16, TLR4/TRAF6 levels and increased in situ autophagy and NETosis formation. Intra-pulmonary LV-SNHG16 delivery enhanced AH through up-regulating TLR4/TRAF6 expression with increased cell death processes, while intra-pulmonary prophylactic and early therapeutic sh-SNHG16 delivery suppressed AH by down-regulating TLR4/TRAF6 expression with reduced such processes. In addition, there was decreased renal SNHG16 expression in LN patients and mice.

CONCLUSIONS

Our results demonstrate that lncRNA SNHG16 regulates TLR4-mediated autophagy and NETosis formation in the human and mouse AH lungs, and provide a therapeutic potential of intra-pulmonary delivery of shRNA targeting SNHG16 in this SLE-related lethal manifestation.

Regulatory Mechanism of M1/M2 Macrophage Polarization in the Development of Autoimmune Diseases

Macrophages are innate immune cells in the organism and can be found in almost tissues and organs. They are highly plastic and heterogeneous cells and can participate in the immune response, thereby playing a crucial role in maintaining the immune homeostasis of the body. It is well known that undifferentiated macrophages can polarize into classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2 macrophages) under different microenvironmental conditions. The directions of macrophage polarization can be regulated by a series of factors, including interferon, lipopolysaccharide, interleukin, and noncoding RNAs. To elucidate the role of macrophages in various autoimmune diseases, we searched the literature on macrophages with the PubMed database. Search terms are as follows: macrophages, polarization, signaling pathways, noncoding RNA, inflammation, autoimmune diseases, systemic lupus erythematosus, rheumatoid arthritis, lupus nephritis, Sjogren's syndrome, Guillain-Barré syndrome, and multiple sclerosis. In the present study, we summarize the role of macrophage polarization in common autoimmune diseases. In addition, we also summarize the features and recent advances with a particular focus on the immunotherapeutic potential of macrophage polarization in autoimmune diseases and the potentially effective therapeutic targets.

Metastasis-associated lung adenocarcinoma transcript 1 induces methyl-CpG-binding domain protein 4 in mice with recurrent spontaneous abortion caused by anti-phospholipid antibody positivity

INTRODUCTION

Antiphospholipid syndrome is an autoimmune disease characterized by pregnancy-related morbidity, related to persistent positivity of antiphospholipid antibodies (APL). One of the characteristics of pregnancy-related morbidity in patients with antiphospholipid syndrome is recurrent spontaneous abortion (RSA). This study aimed to examine the mechanism through which metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) regulates methyl-CpG-binding domain protein 4 (MBD4) expression in APL-positive RSA.

METHODS

Clinical samples were subjected to microarray analysis to filter differentially expressed genes. RSA mice with APL positivity were generated, followed by adenoviral vector injection to artificially upregulate MALAT1. The effects of MALAT1 on the biological behavior of trophoblast cells were assessed. The downstream mechanism of MALAT1 was analyzed using subcellular fractionation and bioinformatics prediction, and the relationship between MALAT1 and CREB binding protein (CREBBP) or MBD4 was investigated in trophoblast cells.

RESULTS

MALAT1 was downregulated in APL-positive RSA patients. MALAT1 was predominantly localized in the nucleus and recruited CREBBP to mediate the MBD4 transcription. In the APL-positive RSA mice overexpressing MALAT1, the expression of soluble Fms-related tyrosine kinase 1 and anticardiolipin antibody and the embryonic resorption rate were decreased, indicating that MALAT1 reduced the occurrence of RSA in mice. Moreover, MALAT1 enhanced proliferation, migration, and invasion of trophoblast cells through recruiting CREBBP to promote MBD4 expression. Silencing of CREBBP or MBD4 increased embryonic resorption rate in RSA mice overexpressing MALAT1.

DISCUSSION

MALAT1 suppresses APL-positive RSA by promoting MBD4 transcription through recruitment of CREBBP to the MBD4 promoter region.

Interaction between Long Noncoding RNAs and Syncytin-1/Syncytin-2 Genes and Transcripts: How Noncoding RNAs May Affect Pregnancy in Patients with Systemic Lupus Erythematosus

BACKGROUND

Patients with systemic lupus erythematosus (SLE) often suffer from obstetric complications not necessarily associated with the antiphospholipid syndrome. These events may potentially result from the reduced placental synthesis of the fusogenic proteins syncytin-1 and syncytin-2, observed in women with pregnancy-related disorders. SLE patients have an aberrant noncoding (nc)RNA signature that may in turn dysregulate the expression of syncytin-1 and syncytin-2 during placentation. The aim of this research is to computationally evaluate and characterize the interaction between syncytin-1 and syncytin-2 genes and human ncRNAs and to discuss the potential implications for SLE pregnancy adverse outcomes.

METHODS

The FASTA sequences of the syncytin-1 and syncytin-2 genes were used as inputs to the Ensembl.org library to find any alignments with human ncRNA genes and their transcripts, which were characterized for their tissue expression, regulatory activity on adjacent genes, biological pathways, and potential association with human disease.

RESULTS

BLASTN analysis revealed a total of 100 hits with human long ncRNAs (lncRNAs) for the syncytin-1 and syncytin-2 genes, with median alignment scores of 151 and 66.7, respectively. Only lncRNAs TP53TG1, TTTY14, and ENSG00000273328 were reported to be expressed in placental tissue. Dysregulated expression of lncRNAs TP53TG1, LINC01239, and LINC01320 found in this analysis has previously been described in SLE patients as well as in women with a high-risk pregnancy. In addition, some of the genes adjacent to lncRNAs aligned with syncytin-1 or syncytin-2 in a regulatory region might increase the risk of pregnancy complications or SLE.

CONCLUSIONS

This is the first computational study showing alignments between syncytin-1 and syncytin-2 genes and human lncRNAs. Whether this mechanism affects syncytiotrophoblast morphogenesis in SLE females is unknown and requires further investigation.

The emerging role of noncoding RNAs in systemic lupus erythematosus: new insights into the master regulators of disease pathogenesis

Auto-immune diseases are a form of chronic disorders in which the immune system destroys the body's cells due to a loss of tolerance to self-antigens. Systemic lupus erythematosus (SLE), identified by the production of autoantibodies in different body parts, is one of the most well-known examples of these diseases. Although the etiology of SLE is unclear, the disease's progression may be affected by genetic and environmental factors. As studies in twins provide adequate evidence for genetic involvement in the SLE, other phenomena such as metallization, histone modifications, and alterations in the expression of noncoding RNAs (ncRNAs) also indicate the involvement of epigenetic factors in this disease. Among all the epigenetic alterations, ncRNAs appear to have the most crucial contribution to the pathogenesis of SLE. The ncRNAs' length and size are divided into three main classes: micro RNAs, long noncoding RNAs (LncRNA), and circular RNAs (circRNAs). Accumulating evidence suggests that dysregulations in these ncRNAs contributed to the pathogenesis of SLE. Hence, clarifying the function of these groups of ncRNAs in the pathophysiology of SLE provides a deeper understanding of the disease. It also opens up new opportunities to develop targeted therapies for this disease.

Novel role of long non-coding RNAs in autoimmune cutaneous disease

Systemic autoimmune rheumatic diseases (SARDs) are a heterogeneous group of chronic multisystem inflammatory disorders that are thought to have a complex pathophysiology, which is not yet fully understood. Recently, the role of non-coding RNAs, including long non-coding RNA (lncRNA), has been of particular interest in the pathogenesis of SARDs. We aimed to summarize the potential roles of lncRNA in SARDs affecting the skin including, systemic sclerosis (SSc), dermatomyositis (DM) and cutaneous lupus erythematosus (CLE). We conducted a narrative review summarizing original articles published until July 19, 2021, regarding lncRNA associated with SSc, DM, and CLE. Several lncRNAs were hypothesized to play an important role in disease pathogenesis of SSc, DM and CLE. In SSc, Negative Regulator of IFN Response (NRIR) was thought to modulate Interferon (IFN) response in monocytes, anti-sense gene to X-inactivation specific transcript (TSIX) to regulate increased collagen stability, HOX transcript antisense RNA (HOTAIR) to increase numbers of myofibroblasts, OTUD6B-Anti-Sense RNA 1 to decrease fibroblast apoptosis, ncRNA00201 to regulate pathways in SSc pathogenesis and carcinogenesis, H19X potentiating TGF-β-driven extracellular matrix production, and finally PSMB8-AS1 potentiates IFN response. In DM, linc-DGCR6-1 expression was hypothesized to target the USP18 protein, a type 1 IFN-inducible protein that is considered a key regulator of IFN signaling. Additionally, AL136018.1 is suggested to regulate the expression Cathepsin G, which increases the permeability of vascular endothelial cells and the chemotaxis of inflammatory cells in peripheral blood and muscle tissue in DM. Lastly, lnc-MIPOL1-6 and lnc-DDX47-3 in discoid CLE were thought to be associated with the expression of chemokines, which are significant in Th1 mediated disease. In this review, we summarize the key lncRNAs that may drive pathogenesis of these connective tissue diseases and could potentially serve as therapeutic targets in the future.

Epigenetic regulation and T-cell responses in endometriosis – something other than autoimmunity

Endometriosis is defined as the presence of endometrial-like glands and stroma located outside the uterine cavity. This common, estrogen dependent, inflammatory condition affects up to 15% of reproductive-aged women and is a well-recognized cause of chronic pelvic pain and infertility. Despite the still unknown etiology of endometriosis, much evidence suggests the participation of epigenetic mechanisms in the disease etiopathogenesis. The main rationale is based on the fact that heritable phenotype changes that do not involve alterations in the DNA sequence are common triggers for hormonal, immunological, and inflammatory disorders, which play a key role in the formation of endometriotic foci. Epigenetic mechanisms regulating T-cell responses, including DNA methylation and posttranslational histone modifications, deserve attention because tissue-resident T lymphocytes work in concert with organ structural cells to generate appropriate immune responses and are functionally shaped by organ-specific environmental conditions. Thus, a failure to precisely regulate immune cell transcription may result in compromised immunological integrity of the organ with an increased risk of inflammatory disorders. The coexistence of endometriosis and autoimmunity is a well-known occurrence. Recent research results indicate regulatory T-cell (Treg) alterations in endometriosis, and an increased number of highly active Tregs and macrophages have been found in peritoneal fluid from women with endometriosis. Elimination of the regulatory function of T cells and an imbalance between T helper cells of the Th1 and Th2 types have been reported in the endometria of women with endometriosis-associated infertility. This review aims to present the state of the art in recognition epigenetic reprogramming of T cells as the key factor in the pathophysiology of endometriosis in the context of T-cell-related autoimmunity. The new potential therapeutic approaches based on epigenetic modulation and/or adoptive transfer of T cells will also be outlined.

Lactate Metabolism-Associated lncRNA Pairs: A Prognostic Signature to Reveal the Immunological Landscape and Mediate Therapeutic Response in Patients With Colon Adenocarcinoma

Background

Lactate metabolism is critically involved in the tumor microenvironment (TME), as well as cancer progression. It is important to note, however, that lactate metabolism-related long non-coding RNAs (laRlncRNAs) remain incredibly understudied in colon adenocarcinoma (COAD).

Methods

A gene expression profile was obtained from the Cancer Genome Atlas (TCGA) database to identify laRlncRNA expression in COAD patients. A risk signature with prognostic value was identified from TCGA and Gene Expression Omnibus (GEO) cohort based on laRlncRNA pairs by the least absolute shrinkage and selection operator (LASSO) and Cox regression analyses. Quantitative real-time polymerase chain reaction (qRT-PCR) and functional experiments were carried out to verify the expression of laRlncRNAs in COAD. The relationship of laRlncRNA pairs with immune landscape as well as the sensitivity of different therapies was explored.

Results

In total, 2378 laRlncRNAs were identified, 1,120 pairs of which were studied to determine their prognostic validity, followed by a risk signature established based on the screened 5 laRlncRNA pairs. The laRlncRNA pairs-based signature provided a better overall survival (OS) prediction than other published signatures and functioned as a prognostic marker for COAD patients. According to the calculated optimal cut-off point, patients were divided into high- and low-risk groups. The OS of COAD patients in the high-risk group were significantly shorter than that of those in the low-risk group (P=4.252e-14 in the TCGA cohort and P=2.865-02 in the GEO cohort). Furthermore, it remained an effective predictor of survival in strata of gender, age, TNM stage, and its significance persisted after univariate and multivariate Cox regressions. Additionally, the risk signature was significantly correlated with immune cells infiltration, tumor mutation burden (TMB), microsatellite instability (MSI) as well as immunotherapeutic efficacy and chemotherapy sensitivity. Finally, one of the laRlncRNA, LINC01315, promotes proliferation and migration capacities of colon cancer cells.

Conclusion

The newly identified laRlncRNAs pairs-based signature exhibits potential effects in predicting prognosis, deciphering patients’ immune landscape, and mediating sensitivity to immunotherapy and chemotherapy. Findings in our study may provide evidence for the role of laRlncRNAs pairs as novel prognostic biomarkers and potentially individualized therapy targets for COAD patients.

Genotype Triad for HOTAIR rs10783618, LINC-ROR rs1942347, and MALAT1 rs3200401 as Molecular Markers in Systemic Lupus Erythematous

Accumulating evidence supports the implication of long non-coding RNAs (lncRNAs) in autoimmune diseases, including systemic lupus erythematosus (SLE). LncRNA variants could impact the development and/or outcome of the disease with variable diagnostic/prognostic utility in the clinic. We aimed to explore the contribution of HOTAIR (rs10783618), LINC-ROR (rs1942347), and MALAT1 (rs3200401) variants to SLE susceptibility and/or severity in 163 SLE patients and age-/sex-matched controls using real-time TaqMan allelic discrimination PCR. HOTAIR rs10783618*C/C was associated with a 77% increased risk of SLE (OR = 1.77, 95%CI = 1.09−2.87, p = 0.020) under the recessive model. Similarly, MALAT1 rs3200401*T/T carriers were three times more likely to develop SLE (OR = 2.89, 95%CI = 1.42−5.90) under the recessive model. While the rs3200401*T/C genotype was associated with a 49−57% decreased risk of SLE under codominant (OR = 0.51, 95%CI = 0.31−0.82, p < 0.001) and over-dominant (OR = 0.43, 95%CI = 0.27−0.68, p < 0.001) models. LINC-ROR rs1942347*A/A patients were more likely to have a positive family history of SLE. At the same time, HOTAIR rs10783618*C/C was associated with a higher frequency of arthritis (p = 0.001) and the presence of oral ulcers (p = 0.002), while patients carrying rs10783618*T/T genotype were more likely to develop hair loss (p < 0.001), weight loss (p = 0.001), and neurological symptoms (p = 0.003). In conclusion, the studied lncRNAs, HOTAIR, and MALAT1 gene polymorphisms confer susceptibility for SLE, providing a potential theoretical basis for their clinical translation in SLE disease.

Roles of Long Non-coding RNAs in the Development of Aging-Related Neurodegenerative Diseases

Aging-related neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS), are gradually becoming the primary burden of society and cause significant health-care concerns. Aging is a critical independent risk factor for neurodegenerative diseases. The pathological alterations of neurodegenerative diseases are tightly associated with mitochondrial dysfunction, inflammation, and oxidative stress, which in turn stimulates the further progression of neurodegenerative diseases. Given the potential research value, lncRNAs have attracted considerable attention. LncRNAs play complex and dynamic roles in multiple signal transduction axis of neurodegeneration. Emerging evidence indicates that lncRNAs exert crucial regulatory effects in the initiation and development of aging-related neurodegenerative diseases. This review compiles the underlying pathological mechanisms of aging and related neurodegenerative diseases. Besides, we discuss the roles of lncRNAs in aging. In addition, the crosstalk and network of lncRNAs in neurodegenerative diseases are also explored.

Epigenetic Alterations in Immune Cells of Systemic Lupus Erythematosus and Therapeutic Implications

Systemic lupus erythematosus (SLE) is an autoimmune disorder that is characterized by autoantibody production and dysregulated immune cell activation. Although the exact etiology of SLE remains unknown, genetic, hormonal, and complex environmental factors are known to be critical for pathologic immune activation. In addition to the inherited genetic predisposition, epigenetic processes that do not change the genomic code, such as DNA methylation, histone modification, and noncoding RNAs are increasingly appreciated to play important roles in lupus pathogenesis. We herein focus on the up-to-date findings of lupus-associated epigenetic alterations and their pathophysiology in lupus development. We also summarize the therapeutic potential of the new findings. It is likely that advances in the epigenetic study will help to predict individual disease outcomes, promise diagnostic accuracy, and design new target-directed immunotherapies.

Involvement of lncRNA IL21-AS1 in interleukin-2 and T follicular regulatory cell activation in systemic lupus erythematosus

BACKGROUND

The single nucleotide polymorphism (SNP) rs62324212, located in IL21 antisense RNA 1 (IL21-AS1), has been identified as a genetic risk variant associated with systemic lupus erythematosus (SLE). We aimed to probe the characteristics of IL21-AS1 and explore its clinical relevance focusing on T helper subsets and disease activity in patients with SLE.

METHODS

rs62324212 genotyping was determined using allelic discrimination by quantitative PCR. Gene expression in peripheral blood mononuclear cells and cell surface markers in CD4⁺ T cells were analyzed using PCR and flow cytometry. The association among IL21-AS1, CD4⁺ T cell subsets, and SLE disease activity was accessed.

RESULTS

Ensembl Genome Browser analysis revealed that rs62324212 (C>A) was located in the predicting enhancer region of IL21-AS1. IL21-AS1 was expressed in the nucleus of CD4⁺ T and B cells, but its expression was decreased in patients with SLE. IL21-AS1 expression was positively correlated with mRNA levels of IL-2 but not IL-21, and it was associated with the proportion of activated T follicular regulatory (Tfr) cells. Furthermore, we observed a significant negative correlation between IL21-AS1 expression and disease activity in patients with SLE (n = 53, p < 0.05).

CONCLUSION

IL21-AS1 has an effect on disease activity through an involvement of IL-2-mediated activation of Tfr cells in SLE. Thus, targeting the IL21-AS1 may provide therapeutic approaches for SLE.

Targeting Intra-Pulmonary P53-Dependent Long Non-Coding RNA Expression as a Therapeutic Intervention for Systemic Lupus Erythematosus-Associated Diffuse Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH) in systemic lupus erythematosus (SLE) is associated with significant mortality, requiring a thorough understanding of its complex mechanisms to develop novel therapeutics for disease control. Activated p53-dependent apoptosis with dysregulated long non-coding RNA (lncRNA) expression is involved in the SLE pathogenesis and correlated with clinical activity. We examined the expression of apoptosis-related p53-dependent lncRNA, including H19, HOTAIR and lincRNA-p21 in SLE-associated DAH patients. Increased lincRNA-p21 levels were detected in circulating mononuclear cells, mainly in CD4+ and CD14+ cells. Higher expression of p53, lincRNA-p21 and cell apoptosis was identified in lung tissues. Lentivirus-based short hairpin RNA (shRNA)-transduced stable transfectants were created for examining the targeting efficacy in lncRNA. Under pristane stimulation, alveolar epithelial cells had increased p53, lincRNA-p21 and downstream Bax levels with elevated apoptotic ratios. After pristane injection, C57/BL6 mice developed DAH with increased pulmonary expression of p53, lincRNA-p21 and cell apoptosis. Intra-pulmonary delivery of shRNA targeting lincRNA-p21 reduced hemorrhage frequencies and improved anemia status through decreasing Bax expression and cell apoptosis. Our findings demonstrate increased p53-dependent lncRNA expression with accelerated cell apoptosis in the lungs of SLE-associated DAH patients, and show the therapeutic potential of targeting intra-pulmonary lncRNA expression in a pristane-induced model of DAH.

Epigenetic Contribution and Genomic Imprinting Dlk1-Dio3 miRNAs in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease that afflicts multiple organs, especially kidneys and joints. In addition to genetic predisposition, it is now evident that DNA methylation and microRNAs (miRNAs), the two major epigenetic modifications, are critically involved in the pathogenesis of SLE. DNA methylation regulates promoter accessibility and gene expression at the transcriptional level by adding a methyl group to 5' cytosine within a CpG dinucleotide. Extensive evidence now supports the importance of DNA hypomethylation in SLE etiology. miRNAs are small, non-protein coding RNAs that play a critical role in the regulation of genome expression. Various studies have identified the signature lupus-related miRNAs and their functional contribution to lupus incidence and progression. In this review, the mutual interaction between DNA methylation and miRNAs regulation in SLE is discussed. Some lupus-associated miRNAs regulate DNA methylation status by targeting the DNA methylation enzymes or methylation pathway-related proteins. On the other hand, DNA hyper- and hypo-methylation are linked with dysregulated miRNAs expression in lupus. Further, we specifically discuss the genetic imprinting Dlk1-Dio3 miRNAs that are subjected to DNA methylation regulation and are dysregulated in several autoimmune diseases, including SLE.

Up-Regulated Expression of Pro-Apoptotic Long Noncoding RNA lincRNA-p21 with Enhanced Cell Apoptosis in Lupus Nephritis

Accelerated cell apoptosis with dysregulated long noncoding RNAs is the crucial pathogenesis in lupus nephritis (LN). Pro-apoptotic lincRNA-p21 was studied in LN patients, cell lines with lentivirus-mediated overexpression and CRISPR interference (CRISPRi)-conducted repression, and a mouse model. Clinical samples were from patients and age/sex-matched controls. Expression of lincRNA-p21 and endogenous RNA target miR-181a, were examined in mononuclear and urine cells. Guide RNA sequences targeting lincRNA-p21 were cloned into CRISPRi with dCas9/ Krüppel-associated box (KRAB) domain. LincRNA-p21-silened transfectants were investigated for apoptosis and miR-181a expression. LincRNA-p21-overexpressed cells were evaluated for apoptosis and p53-related down-stream molecules. Balb/C mice were injected with pristane to induce LN and examined for apoptosis and lincRNA-p21. Higher lincRNA-p21 levels were found in LN mononuclear and urine cells, positively correlated with activity. There were lower miR-181a levels in LN mononuclear cells, negatively correlated with activity. Doxorubicin-induced apoptotic cells had up-regulated lincRNA-p21 levels. CRISPRi with dCas9/KARA domain showed efficient repression ability on transcription initiation/elongation. CRISPRi-conducted lincRNA-p21-silenced transfectants displayed reduced apoptosis with up-regulated miR-181a levels, whereas lentivirus-mediated lincRNA-p21-overexpressed cells revealed enhanced apoptosis with up-regulated downstream PUMA/Bax expression. LN mice had glomerular apoptosis with progressive increased lincRNA-p21 levels. Our results demonstrate up-regulated lincRNA-p21 expression in LN, implicating a potential diagnostic marker and therapeutic target.