Article

IL-6 Modulates CD5 Expression in B Cells from Patients with Lupus by Regulating DNA Methylation

Research Unit EA2216 Immunology and Pathology, IFR148 ScInBioS, Université de Brest, Brest, France.
The Journal of Immunology (Impact Factor: 4.92). 06/2009; 182(9):5623-32. DOI: 10.4049/jimmunol.0802412
Source: PubMed

ABSTRACT

B lymphocytes from patients with systemic lupus erythematosus (SLE) are characterized by reduced expression levels of membrane CD5. Recent studies from our laboratory have revealed that the level of membrane CD5 is determined by the relative level of two alternative CD5 isoforms; CD5-E1A, which is expressed on the membrane, and CD5-E1B, which is retained in the cytoplasm. Using bisulfite sequencing and methylation-sensitive endonuclease assays we show that the promoter for the alternative CD5-E1B isoform is demethylated in B cells from patients with SLE but not in healthy controls. We go on to show that differential methylation is more pronounced following BCR engagement. As a result of this demethylation, CD5-E1B mRNA is transcribed at the expense of CD5-E1A mRNA transcription. We provide further evidence that production of high IL-6 levels by SLE B cells abrogates the ability of SLE B cells to induce DNA methyl transferase (DNMT1) and then to methylate DNA, an effect that is reversed in the presence of a blocking Ab to the IL-6 receptor. The pattern of demethylation of CpG islands in the CD5-E1B promoter in SLE B cells is similar to those in B cells from healthy controls stimulated in the presence of IL-6, or treated with the methylation inhibitor PD98059. The study reveals that engagement of the BCR with constitutive IL-6 down-regulates the level of membrane CD5, which negatively regulates BCR signaling, in SLE B cells. This altered signaling could, in turn, promote the activation and expansion of autoreactive B cells in SLE patients.

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    • "When comparing pSS patients and controls, recent studies, including ours, have reported differential methylation profiles in interferon (IFN) regulated genes when testing CD4 þ T cells [6], DNA methylation deregulation patterns in B cells [7], and important global DNA methylation changes in minor salivary gland (MSG) epithelial cells [8]. Interestingly, epigenetic mechanisms are interconnected with pSS genetic risk factors [9] and reversible, thus opening new therapeutic perspectives in pSS and other autoimmune diseases [8] [10] [11]. "
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    ABSTRACT: The pathogenesis of primary Sjögren's syndrome (pSS) is complex, in part due to DNA methylation abnormalities. This study was undertaken to evaluate the importance of global DNA methylation (5mC) as determined in minor salivary glands (MSG) from well characterized pSS patients. Twenty-two pSS patients and ten controls were selected, and MSG were stained with anti-5mC, anti-5mC/anti-cytokeratin (KRT)19, or with anti-SSB/La antibodies (Ab). The DNA methylation status at the SSB gene promoter P1 and P1′ was evaluated by methylation-sensitive restriction enzymes (MSRE) coupled with PCR. The effect of the DNA demethylating drug 5 azacytidine (5-Aza) was tested in the human salivary gland (HSG) cell line. In pSS, the reduction of global DNA methylation (5mC) was associated with lymphocyte infiltration, the emergence of 5mClow and KRT19high acini, and the detection of circulating anti-SSB/La Ab, but not with disease activity (ESSDAI). Next, treating HSG cells with 5-Aza was effective in inducing SSB expression. Finally in pSS patients positive for anti-SSB/La Ab, we further observed DNA demethylation at the SSB gene promoter P1 with consequent SSB overexpression at both the transcriptional and protein levels in salivary gland epithelial cells. In conclusion, our results highlight the importance of DNA methylation in the pathophysiology of pSS and to the emergence of anti-SSB/La Ab.
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    • "At the same time, Brookes et al. (1992) mentioned that the human T cell lymphotropic virus (HTLV) related endogenous sequence, HRES1, was overexpressed in the epithelium of labial salivary glands obtained from patients with primary SS (pSS). HRES1 regulation by DNA methylation was recently provided (Garaud et al., 2009; Fali et al., 2013) Later, the HERV- K113, and HRV-5 retroviral elements were found overexpressed in pSS patients (Murovska et al., 2000; Moyes et al., 2005). More recently, using a RT-PCR approach we have observed that at least one HERV-E element was detected when testing labial salivary glands from SS patients (Le Dantec et al., 2012). "
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    ABSTRACT: Sjögren's syndrome (SS) is a chronic autoimmune epithelitis that combines exocrine gland dysfunctions and lymphocytic infiltrations. While the pathogenesis of SS remains unclear, its etiology is multifunctional and includes a combination of genetic predispositions, environmental factors, and epigenetic factors. Recently, interest has grown in the involvement of epigenetics in autoimmune diseases. Epigenetics is defined as changes in gene expression, that are inheritable and that do not entail changes in the DNA sequence. In SS, several epigenetic mechanisms are defective including DNA demethylation that predominates in epithelial cells, an abnormal expression of microRNAs, and abnormal chromatin positioning-associated with autoantibody production. Last but not least, epigenetic modifications are reversible as observed in minor salivary glands from SS patients after B cell depletion using rituximab. Thus epigenetic findings in SS open new perspectives for therapeutic approaches as well as the possible identification of new biomarkers.
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    • "On the other hand, B cells expressing high levels of CD5-E1B, induced probably by external stimuli, would more likely to be activated. To support these results, in B lymphocytes from SLE patients, the levels of CD5-E1B are higher, indicating a more activating B cell [85]. These high levels of CD5-E1B traduces in reduced expression of membrane CD5. "
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    ABSTRACT: B lymphocytes are the effectors of humoral immunity, providing defense against pathogens through different functions including antibody production. B cells constitute approximately 15% of peripheral blood leukocytes and arise from hemopoietic stem cells in the bone marrow. It is here that their antigen receptors (surface immunoglobulin) are assembled. In the context of autoimmune diseases defined by B and/or T cell autoreactive that upon activation lead to chronic tissue inflammation and often irreversible structural and functional damage, B lymphocytes play an essential role by not only producing autoantibodies but also functioning as antigen-presenting cells (APC) and as a source of cytokines. In this paper, we describe B lymphocyte functions in autoimmunity and autoimmune diseases with a special focus on their abnormalities in systemic lupus erythematosus.
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