Expression of recombination activating genes 1 and 2 in peripheral B cells of patients with systemic lupus erythematosus (original) (raw)
Related papers
Immunology, 2007
Defective regulation of secondary immunoglobulin V(D)J gene rearrangement promotes the production of autoantibodies in systemic lupus erythematosus (SLE). It remains unclear, however, whether the regulation of the recombination-activating genes RAG1 and RAG2 is effective in SLE. RAG1 and RAG2 messenger RNA expression was analysed before and after in vitro activation of sorted CD19+ CD5– B cells with anti-immunoglobulin M antibodies, in 20 SLE patients and 17 healthy controls. The expression of CDK2 and p27Kip1 regulators of the RAG2 protein, were examined. The levels of interleukin-6 (IL-6) and its influence on RAG regulation were also evaluated in vitro. SLE patients had increased frequency of RAG-positive B cells. B-cell receptor (BCR) engagement induced a shift in the frequency of κ- and λ-positive cells, associated with a persistence of RAG messenger RNA and the maintenance of RAG2 protein within the nucleus. While expression of the RAG2-negative regulator CDK2 was normal, the positive regulator p27Kip1 was up-regulated and enhanced by BCR engagement. This effect was the result of the aberrant production of IL-6 by SLE B cells. Furthermore, IL-6 receptor blockade led to a reduction in p27Kip1 expression, and allowed the translocation of RAG2 from the nucleus to the cytoplasm. Our study indicates that aberrant production of IL-6 contributes to the inability of SLE B cells to terminate RAG protein production. Therefore, we hypothesize that because of constitutive IL-6 signalling in association with BCR engagement, SLE B cells would become prone to secondary immunoglobulin gene rearrangements and autoantibody production.
PLOS ONE, 2017
Background Hyperactive B cells and a continuous interferon (IFN)-α production by plasmacytoid dendritic cells (pDCs) play a key role in systemic lupus erythematosus (SLE). We asked whether the interaction between B cells and pDCs stimulated with RNA-containing immune complexes affects peripheral B cell subsets. Methods B cells and pDCs were isolated from blood of healthy individuals and stimulated with immune complexes consisting of SLE-IgG and U1snRNP (RNA-IC). Expression of cell surface molecules as well as IL-6 and IL-10 production were determined by flow cytometry and immunoassays. Gene expression profiles were determined by a NanoString nCounter expression array. Results We found a remarkable increase of double negative CD27-IgD-B cells, from 7% within fresh CD19+ B cells to 37% in the RNA-IC-stimulated co-cultures of B cells and pDCs, comparable to the frequency of double negative B cells in SLE patients. Gene expression analysis of the double negative CD27-IgDand the CD27 + IgDmemory B cells revealed that twenty-one genes were differentially expressed between the two B cell subsets (! 2-fold, p<0.001). The, IL21R, IL4R, CCL4, CCL3, CD83 and the IKAROS Family Zinc Finger 2 (IKZ2) showed higher expression in the double negative CD27-IgD-B cells. Conclusion The interactions between B cells and pDCs together with RNA-containing IC led to an expansion of B cells with similar phenotype as seen in SLE, suggesting that the pDC-B cell crosstalk contributes to the autoimmune feed-forward loop in SLE.
Clinical and Experimental Immunology, 1996
A semiquantitative polymerase chain reaction (PCR) assay described in this study has been used to analyse the V H 1, V H 3 and V H 4 repertoire expressed by total IgM and IgG B cells from normal individuals and lupus patients. This approach consists of a combination of B cell selection, utilization of the anchored PCR technique to avoid technical bias in the amplification of different V H gene family cDNA templates, and screening of the amplified IgM or IgG cDNA rearrangements by family-specific oligonucleotide probes. In four lupus patients, V H family representation in IgM and IgG in vivo activated B cells, selected by anti-CD71 antibody, and in total CD19 B cells were compared. In all patients, V H 4 gene family segments were preferentially under-represented in IgM activated B cells. In IgG B cells the results suggest that V H 4 expression is variable, depending on the phase of the disease. Polyclonal B cell activation, which is usually considered as being the first event in autoantibody production in SLE, cannot explain our results. The data evoke the possible involvement of a V H 4specific B cell superantigen in the onset or development of SLE. This hypothesis is also supported by the sequence conservation of the fourth loop-a putative superantigen binding site-of functional V H 4 gene segments which are preferentially used by anti-dsDNA lupus antibodies of established clones and hybridomas.
Clinical Immunology and Immunopathology, 1981
Peripheral blood lymphocytes from 20 patients with systemic lupus erythematosus (SLE) were defective in their ability to secrete immunoglobulin M (IgM) in a pokeweed mitogen (PWM)-stimulated in vitro culture system. To characterize this abnormality, the mononuclear cells were separated into three functional subpopulations: (i) bone marrow-derived (B) cells which secrete immunoglobulin; (ii) a thymus-derived (T) lymphocyte fraction; and (iii) an irradiated T-cell fraction with predominant helper function. Coculture experiments with subsequent radioimmunoassay of the quantity of immunoglobulin secreted allowed comparisons of the immunoregulatory functions of the SLEhelper T, SLE suppressor T, and SLE B cells with functions of control lymphocyte fractions. The major defect defined was an inability of the SLE B cell to secrete normal amounts of IgM This was not due to suppression by monocytes since the removal of phagocytic cells and the addition of separated monocytes to the cultures demonstrated generation of normal helper signals by SLE monocytes. Nor were inadequate numbers of IgM secreting B cells available since limiting dilution studies showed a normal precursor frequency of PWM-stimulatable, IgM secreting SLE B cells. SLE T cells showed a normal helper effect on the secretion of IgM by control B cells. Thus, these in vitro coculture studies designate a primary immunologic defect in SLE to the B cell and not in the suppressor or helper functions of the T cell.
The Journal of Rheumatology, 2011
Objective.To examine the relationship between interferon-α (IFN-α) and dysregulation of B cell activation factor (BAFF) and specific B cell phenotypes in systemic lupus erythematosus (SLE).Methods.Four-color flow cytometry was used to examine the peripheral B cell populations in patients with SLE. RNA was isolated from the peripheral blood of 87 patients and BAFF expression was determined by quantitative polymerase chain reaction (PCR) and normalized to GAPDH. The expression levels of 5 IFN-responsive genes (LY6E, OAS1, IFIT1, ISG15, and MX1) were determined by quantitative PCR and totaled to generate a global IFN score. The correlations were examined between peripheral B cell populations (including transitional, pregerminal, plasmablasts, and memory) and the expression of BAFF and the global IFN score.Results.Examination of the peripheral B cell populations in SLE demonstrated a relative expansion of the transitional B cell and plasmablast compartment and a reduction in the memory ...
B lymphocytes and systemic lupus erythematosus
Current Rheumatology Reports, 2003
Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by B cell hyperactivity in association with autoantibodies, most prominently those directed to components of the cell nucleus. The source of the antigens that drive B cell responses in SLE is unknown, although recent studies suggest mechanisms by which the self-antigens become immunogenic and stimulate responses. Among these mechanisms, abnormalities in the generation of apoptotic cells or their clearance may increase the availability of nuclear antigens to drive responses. In addition, autoantibody crossreactivity may promote induction of responses to disparate antigens, foreign and self, and enable a single autoantibody to cause disease by crossreactive binding. In addition to reflecting increased exposure to self-antigen, autoantibody responses in SLE may result from abnormalities in B cell signaling and regulation by cytokines. New approaches to therapy aim to abrogate autoantibody production by targeting specific steps in B cell activation, including blockade of T cell costimulation.
B-cell Biology and Related Therapies in Systemic Lupus Erythematosus
Rheumatic Disease Clinics of North America, 2010
Systemic lupus erythematosus (SLE) is a complex disease characterized by numerous autoantibodies and clinical involvement in multiple organ systems. The immunological events triggering the onset and progression of clinical manifestations have not yet been fully defined, but a central role for B cells in the pathogenesis has been brought to the fore in the last several years. The breakdown of B cell tolerance is likely a defining and early event in the disease process and may occur by multiple pathways, including alterations in factors that affect B cell activation thresholds, B cell longevity, and apoptotic cell processing. Both antibody dependent and independent mechanisms of B cells are important in SLE. Thus, autoantibodies contribute to autoimmunity by multiple mechanisms including immune-complex mediated Type III hypersensitivity reactions, type II antibody-dependent cytotoxicity, and by instructing innate immune cells to produce pathogenic cytokines including IFNα, TNF and IL-1. Recent data have highlighted the critical role of toll-like receptors as a link between the innate and adaptive immune system in SLE immunopathogenesis. Given the large body of evidence implicating abnormalities in the B cell compartment in SLE, there has been a therapeutic focus on developing interventions that target the B cell compartment. A number of different approaches to targeting B cells have been utilized including B cell depletion with monoclonal antibodies against B cell-specific molecules, induction of negative signaling in B cells, and blocking B cell survival and activation factors. Overall, therapies targeting B cells are beginning to show promise in the treatment of SLE and continue to elucidate the diverse roles of B cells in this complex disease.
Dysfunctional B cells in systemic lupus erythematosus
Autoimmunity Reviews, 2004
The classical view of B cells in the biology of autoimmune responses to infectious and self-antigens (Ag) that they promote immunity primarily by producing antibodies (Ab) is far from being complete. Indeed, studies over the last decade suggest that B cells have extraordinarily diverse functions within the immune system other than Ab production, which could contribute to autoimmunity. They normally play a role in the development of lymphoid architecture, regulating dentritic cells (DC) and T cell subsets function through cytokine production, and in activation of T cells. Receptor editing is also important in B cells which aids in immunity to infection and, possibly, prevention of autoimmunity. Both abnormalities in the distribution of B cells subsets and clinical benefit response to B cell depletion in autoimmune diseases, including systemic lupus erythematosus (SLE), highlight their pivotal function. Transgenic (Tg) animal models have shown that sensitivity of B cells to B cell Ag receptor (BCR) cross-linking is correlated to autoimmunity. Indeed, negative signaling by CD5 and other molecules, such as CD22, in maintaining tolerance through recruitment of src-homology two domain-containing protein tyrosine phosphatase-1 (SHP-1) has also been documented. In fact, we have now reached a newer area whereby B cells returned as an important contributor to autoimmune disorders. D