Search

Underexpression of p53 is considered the leading cause of the decreased miR-1246 expression in B cells of systemic lupus erythematosus (SLE) patients, yet the exact mechanism of action still remains unclear. To further explore the molecular mechanism of p53 upregulating miR-1246 expression, we targeted the methylation and acetylation of histone H3 in the miR-1246 promoter region of SLE B cells. We found that increased histone H3 trimethylation at Lys27 (H3K27me3) and decreased histone H3 acetylation at Lys9 and Lys14 (H3K9/K14ac) in the miR-1246 promoter region are essential for the low expression of miR-1246 in SLE B cells. p53 can promote miR-1246 transcription by recruiting Jumonji domain–containing protein 3 (JMJD3), E1A-binding protein p300 (EP300), and CREB-binding protein (CBP) to bind to the miR-1246 promoter, downregulating H3K27me3 and upregulating H3K9/K14ac. Furthermore, early B cell factor 1 (EBF1), CD40, CD38, and X box binding protein-1 (XBP-1) expression levels in SLE B cells transfected with p53 expression plasmid were significantly decreased, whereas autoantibody IgG production in autologous CD4+ T cells cocultured with overexpressed p53 SLE B cells was reduced. Collectively, our data suggest that the reduction of p53 decreases miR-1246 expression via upregulation of H3K27me3 and downregulation of H3K9/14ac, which in turn results in SLE B cell hyperactivity.

The reduced expression of miR-142-3p/5p in CD4+ T cells of SLE patients caused T cell hyperactivity and B cell hyperstimulation. This study aimed to investigate the mechanisms of regulating miR-142-3p/5p expression in SLE CD4+ T cells. The BCL-6 expression was significantly increased in SLE CD4+ T cells compared with normal controls, and the BCL-6 expression was inversely correlated with miR-142-3p/5p expression. BCL-6 suppresses the expression of miR-142-3p/5p by increasing H3K27me3 level and reducing H3K9/K14ac levels in SLE CD4+ T cells. BCL-6 regulates histone modifications in miR-142 promoter by recruiting EZH2 and HDAC5. Furthermore, we observed significantly decreased CD40L, ICOS, and IL-21 expression levels in SLE CD4+ T cells with BCL-6 interference, and obviously reduced autoantibody IgG production in autologous B cells co-cultured with BCL-6 inhibited SLE CD4+ T cells. Our study found that increased BCL-6 up-regulates H3K27me3 and down-regulates H3K9/14ac at miR-142 promoter in SLE CD4+ T cells. These factors induce a declination in miR-142-3p/5p expression, consequently resulting in CD4+ T cell hyperactivity.

Systemic lupus erythematosus (SLE) is a spectrum of autoimmune disorders characterized by continuous inflammation and the production of autoantibodies. Monocytes, as precursors of dendritic cells and macrophages, are involved in the pathogenesis of SLE, particularly in the inflammatory reactions. Previous studies have proved that Pam3CSK4, as a synthetic ligand of TLR2, could stimulate monocytes to differentiated into a M2-like phenotype which presented immunosuppressive functions. However, the underlying mechanisms remain to be further studied. Here, we reported an increased expression of PPAR-γ in the CD14+ monocytes from SLE patients, particularly in the treated group of SLE patients and the group with positive anti-dsDNA antibodies. Additionally, PPAR-γ expression decreased in the SLE patients with skin lesion. Furthermore, we demonstrated that Pam3CSK4 stimulation can decrease the expression of CCR7, CD80, IL-1β, IL-6, IL-12, and NF-κB which were related to the M1-like subset of monocytes and increased the expression of ARG1 which was related to the M2-like subset through upregulated PPAR-γ expression and consequently downregulated NF-κB expression in the CD14+ monocytes in a time-dependent manner. ChIP-qPCR results further demonstrated that Pam3CSK4 pretreatment could modulate PPAR-γ expression by regulating histone modification through the inhibition of Sirt1 binding to the PPAR-γ promoter. Taken together, our study indicated a protective role of TLR2/Sirt1/PPAR-γ pathway in the pathogenesis of SLE which provided potential therapeutic strategies.

ObjectiveT cell receptor (TCR) diversity determines the autoimmune responses in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) and is closely associated with autoimmune diseases prognosis and prevention. However, the characteristics of variations in TCR diversity and their clinical significance is still unknown. Large series of patients must be studied in order to elucidate the effects of these variations.MethodsPeripheral blood from 877 SLE patients, 206 RA patients and 439 healthy controls (HC) were amplified for the TCR repertoire and sequenced using a high-throughput sequencer. We have developed a statistical model to identify disease-associated TCR clones and diagnose autoimmune diseases.ResultsSignificant differences were identified in variable (V), joining (J) and V-J pairing between the SLE or RA and HC groups. These differences can be utilised to discriminate the three groups with perfect accuracy (V: area under receiver operating curve > 0.99). One hundred ninety-eight SLE-associated and 53 RA-associated TCRs were identified and used for diseases classification by cross validation with high specificity and sensitivity. Disease-associated clones showed common features and high similarity between both autoimmune diseases. SLE displayed higher TCR heterogeneity than RA with several organ specific properties. Furthermore, the association between clonal expansion and the concentration of disease-associated clones with disease severity were identified, and pathogen-related TCRs were enriched in both diseases.ConclusionsThese characteristics of the TCR repertoire, particularly the disease-associated clones, can potentially serve as biomarkers and provide novel insights for disease status and therapeutical targets in autoimmune diseases.

The peripheral blood of systemic lupus erythematosus patients showed an increased expression of CXCR5 positive T cells. However, the molecular mechanism of the abnormal expression of CXCR5 in SLE CD4+ T cells remains unclear. The present study demonstrated that the levels of H3K4me3 and H3K36me3 in CXCR5 promoter were significantly higher in SLE patients than those in healthy controls. Furthermore, the expression of SETD3 was upregulated in SLE CD4+ T cells as compared to the healthy controls. Excessive SETD3 increased the level of H3K4me3 and H3K36me3 and promoted the expression of CXCR5. These data strongly suggested that SETD3 plays a major role in the regulation of CXCR5 expression and the progression of SLE.

Henoch-Schönlein purpura (HSP), the most common type of leukocytoclastic vasculitis, is caused by T cell-mediated autoimmune reactions. In this study, we analyze histone modification patterns in peripheral blood mononuclear cells (PBMCs) of HSP patients, and investigate the expression levels of inflammatory cytokines (IFN-γ, IL-2, IL-4, IL-6 and IL-13), transcription factors (T-bet, GATA-3 and TIM-1) and chemokines (CXCL4 and CXCL10) in HSP patients. Our results show that histone H3 acetylation and methylation are significantly enhanced in PBMCs from HSP patients. We also demonstrate specifically that marked increases in histone H3 acetylation and H3 lysine 4 trimethylation occur at the IL-4 loci in these patients. In addition, the expression levels of IL-4, IL-6, IL-13, GATA-3, TIM-1 and CXCL4 are also increased. These findings suggest that abnormal histone modifications are present in the PBMCs of patients with HSP, possibly contributing to the activation of pathological immune responses associated with HSP.

Total glucosides of paeony (TGP), an active compound extracted from Paeony root, has been used in therapy for autoimmune diseases. However the molecular mechanism of TGP in the prevention of autoimmune response remains unclear. In this study, we found that TGP treatment significantly increased the percentage and number of Treg cells in lupus CD4(+) T cells. Further investigation revealed that treatment with TGP increased the expression of Foxp3 in lupus CD4(+) T cells by down-regulating Foxp3 promoter methylation levels. However, we couldn't observe similar results in healthy control CD4(+) T cells treated by TGP. Moreover, our results also showed that IFN-γ and IL-2 expression was enhanced in TGP-treated lupus CD4(+) T cells. These findings indicate that TGP inhibits autoimmunity in SLE patients possibly by inducing Treg cell differentiation, which may in turn be due to its ability to regulate the methylation status of the Foxp3 promoter and activate IFN-γ and IL-2 signaling.

Background The pathogenesis of systemic lupus erythematosus (SLE) has not yet been completely elucidated. One of the hallmarks of SLE is the production of autoantibodies by uncontrolled over-activated B cells. Early B cell factor 1 (EBF1) contributes to the development, activation, and proliferation of B cells through activation of the AKT signaling pathway. Accumulating evidence has demonstrated that several microRNAs (miRNAs) contribute to the pathogenesis of autoimmune diseases through the regulation of B cells in SLE. We aim to investigate the expression patterns of miR-1246 in B cells and its contribution to pathogenesis of SLE. Results Our results showed that the expression of miR-1246 was significantly decreased in B cells from SLE patients. We verified that miR-1246 specifically targeted the EBF1 messenger RNA (mRNA) by interacting with its 3′-untranslated region (3′-UTR) and regulated the expression of EBF1. Transfection of miR-1246 inhibitors into healthy B cells upregulated the expression of EBF1, enhanced B cell function, and increased the production of B cell surface co-stimulatory molecules CD40, CD80, and CD86. We also observed that abnormal activation of the AKT signaling pathway was associated with decreased P53 expression, leading to the downregulation of the miR-1246 expression; and upregulation of the miR-1246 expression reversed the responsiveness of B cells by inhibiting EBF1 expression. Conclusions Activated B cells in lupus could decrease the expression of miR-1246 through the AKT-P53 signaling pathway, which in turn enhances the expression of EBF1, thereby promoting further activation of B cells. Conversely, upregulation of miR-1246 could interrupt this amplification pathway. Our findings thus provide a theoretical framework towards the research of novel biological targets in SLE treatment. Electronic supplementary material The online version of this article (doi:10.1186/s13148-015-0063-7) contains supplementary material, which is available to authorized users.

Systemic lupus erythematosus (SLE) is an autoimmune disease well known for its clinical heterogeneity, and its etiology secondary to a cross-talk involving genetic predisposition and environmental stimuli. Although genome-wide analysis has contributed greatly to our understanding of the genetic basis of SLE, there is increasing evidence for a role of epigenetics. Indeed, recent data have demonstrated that in patients with SLE, there are striking alterations of DNA methylation, histone modifications, and deregulated microRNA expression, the sum of which contribute to over-expression of select autoimmune-related genes and loss of tolerance. To address this issue at the level of clinical phenotype, we performed DNA methylation, mRNA and microRNA expression screening using high-throughput sequencing of purified CD4+ T cells from patients with SLE, compared to age and sex matched controls. In particular, we studied 42 patients with SLE and divided this group into three clinical phenotypes: a) the presence of skin lesions without signs of systemic pathology; b) skin lesions but also chronic renal pathology; and c) skin lesions, chronic renal pathology and polyarticular disease. Interestingly, and as expected, sequencing data revealed changes in DNA methylation in SLE compared to controls. However, and more importantly, although there were common methylation changes found in all groups of SLE compared to controls, there was specific DNA methylation changes that correlated with clinical phenotype. These included changes in the novel key target genes NLRP2, CD300LB and S1PR3, as well as changes in the critical pathways, including the adherens junction and leukocyte transendothelial migration. We also noted that a significant proportion of genes undergoing DNA methylation changes were inversely correlated with gene expression and that miRNA screening revealed the existence of subsets with changes in expression. Integrated analysis of this data highlights specific sets of miRNAs controlled by DNA methylation, and genes that are altered by methylation and targeted by miRNAs. In conclusion, our findings suggest select epigenetic mechanisms that contribute to clinical phenotypes and further shed light on a new venue for basic SLE research.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by T cell overactivation and B cell hyper-stimulation. Hematopoietic progenitor kinase 1 (HPK1, also called MAP4K1) negatively regulates T cell-mediated immune responses. However, the role of HPK1 and the mechanisms that regulate HPK1 expression in SLE remain poorly understood. Using chromatin immunoprecipitation (ChIP) microarray data, we identified markedly increased histone H3 lysine 27 trimethylation (H3K27me3) enrichment at the HPK1 promoter of SLE CD4+ T cells relative to controls, and confirmed this observation using ChIP and real-time PCR experiments. We further found that HPK1 mRNA and protein levels were significantly decreased in CD4+ T cells of patients with SLE, and that this decrease was not caused by exposure to standard SLE medications. Down-regulating HPK1 in healthy CD4+ T cells significantly accelerated T cell proliferation and production of IFNγ and IgG. Consistent with these findings, overexpressing HPK1 in SLE CD4+ T cells caused a significant decrease in T cell reactivity. In addition, we observed a striking decrease in jumonji domain containing 3 (JMJD3) binding, but no marked change in enhancer of zeste homolog 2 (EZH2) binding, at the HPK1 promoter region in SLE CD4+ T cells compared to healthy controls. SiRNA knock down of JMJD3 in healthy CD4+ T cells led to decreased JMJD3 binding and increased H3K27me3 enrichment at the HPK1 promoter region, thus inhibiting the expression of HPK1. Concordantly, plasmid-induced overexpression of JMJD3 in SLE CD4+ T cells led to increased JMJD3 binding, decreased H3K27me3 enrichment, and up-regulated HPK1 expression. Our results show for the first time that inhibited HPK1 expression in SLE CD4+ T cells is associated with loss of JMJD3 binding and increased H3K27me3 enrichment at the HPK1 promoter, contributing to T cell overactivation and B cell overstimulation in SLE. These findings suggest that HPK1 may serve as a novel target for effective SLE therapy.

Introduction Regulatory factor X-box 1 (RFX1) can interact with DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1), and RFX1 down-regulation contributes to DNA hypomethylation and histone H3 hyperacetylation at the cluster of differentiation (CD) 11a and CD70 promoters in CD4+ T cells of patients with systemic lupus erythematosus (SLE). This leads to CD11a and CD70 overexpression, thereby triggering autoimmune responses. In order to provide more insight into the epigenetic mechanisms leading to the deregulation of autoimmune-related genes in SLE, we asked whether RFX1 is involved in regulating histone 3 lysine 9 (H3K9) tri-methylation at the CD11a and CD70 promoters in SLE CD4+ T cells. Methods CD4+ T cell samples were isolated from 15 SLE patients and 15 healthy controls. H3K9 tri-methylation levels were measured by chromatin immunoprecipitation (ChIP) and real-time quantitative PCR. CD4+ T cells were transfected with plasmids using the Human T cell Nucleofector Kit. RFX1 and histone methyltransferase suppressor of variegation 3-9 (Drosophila) homolog 1 (SUV39H1) interaction was determined by co-immunoprecipation (co-IP) and Western blot and immunofluorescence staining. CD11a and CD70 mRNA levels were measured by real-time RT-PCR. Results H3K9 tri-methylation levels were significantly reduced within the CD11a and CD70 promoter regions in SLE CD4+ T cells. RFX1 co-immunoprecipitated with SUV39H1 at the CD11a and CD70 promoters in healthy control CD4+ T cells. Overexpressing or knocking-down RFX1 revealed that RFX1 expression correlated with H3K9 tri-methylation levels, as well as CD11a and CD70 expression levels in CD4+ T cells. Conclusions RFX1 recruits SUV39H1 to the promoter regions of the CD11a and CD70 genes in CD4+ T cells, thereby regulating local H3K9 tri-methylation levels. These findings shed further light on the central role of RFX1 down-regulation in the epigenetic de-repression of auto-immune genes in SLE.