The advent of therapies that specifically target the B-lymphocyte lineage in human disease has rejuvenated interest in the mechanistic biology by which B cells mediate autoimmunity. B cells have a multitude of effector functions including production of self-reactive antibodies, ability to present antigen to T lymphocytes in the context of costimulation, involvement in generation and maintenance of neo-organogenesis at sites of disease, and opposing function through production of both immunostimulatory and immunomodulatory cytokines. In this review, we first discuss the role of B cells in driving autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, and Sjögren's syndrome, and discuss how studies in these diseases have revealed differentially important roles for the multiple B-cell effector functions. These data reveal the complex and interrelated roles of B cells working in concert with other components of the innate and adaptive immune system to drive pathogenesis. We then focus on data from mouse and human in which B cells in the setting of disease have been targeted with drugs directed against CD20, CD22, and the BAFF (B-cell activating factor belonging to the tumor necrosis factor family)/APRIL (a proliferation inducing ligand) pathways. Pre-clinical studies in animal models in addition to and clinical trials targeting B cells have added further to the understanding of the differential roles B cells play in disease both through demonstration of clinical efficacy in the context of B-cell depletion or modulation, and also by failure of B-cell targeting in some diseases and disease patient subgroups. Moving forward, it will be imperative to apply these lessons to new interventional trials to ensure better targeting of the B-cell lineage and concomitantly better selection of patients most likely to benefit from these therapies.
"A recent study showed that Bregs could still secrete antibodies especially with IgM subtype as the activated plasmablast/plasma B cells. Immunoglobulins could also mediate inflammation to promote cancer as described above [44, 52]. "
[Show abstract][Hide abstract] ABSTRACT: Regulatory B cells (Bregs), a newly described subset of B cells, have been proved to play a suppressive role in immune system. Bregs can inhibit other immune cells through cytokines secretion and antigen presentation, which give them the role in the pathogenesis of autoimmune diseases and cancers. There are no clear criteria to identify Bregs; different markers were used in the different experimental conditions. Massive researches had described the functions of immune cells such as regulatory T cells (Tregs), dendritic cells (DCs), and B cells in the autoimmune disorder diseases and cancers. More and more researches focused on the roles of Bregs and the cytokines such as Interleukin-10 (IL-10) and transforming growth factor beta (TGF- β ) secreted by Bregs. The aim of this review is to summarize the characteristics of Bregs and the roles of Bregs in cancer.
Research Journal of Immunology 06/2014; 2014:215471. DOI:10.1155/2014/215471
"Rituximab is a chimeric monoclonal antibody directed against the human CD20 receptor, which is present only on B cells . It has not been used much in children with JIA, perhaps out of a concern that it will only be effective in diseases with an identifiable antibody. "
[Show abstract][Hide abstract] ABSTRACT: A generation ago, children with arthritis faced a lifetime of pain and disability. Today, there are a multitude of treatment options, including a variety of biologics targeting key cytokines and other inflammatory mediators. While non-steroidal anti-inflammatory drugs and corticosteroids were once the mainstay of therapy, they are now largely used as bridge or adjunctive therapies. Among the conventional disease-modifying anti-rheumatic drugs, methotrexate remains first-line therapy for most children with juvenile idiopathic arthritis (JIA) due to its long track record of safety and effectiveness in the management of peripheral arthritis. Sulfasalazine and leflunomide may also have a secondary role. The tumor necrosis factor inhibitors (TNFi) have shown tremendous benefit in children with polyarticular JIA and likely in enthesitis-related arthritis and psoriatic JIA as well. There may be additional benefit in combining TNFi with methotrexate. Abatacept and tocilizumab also appear to benefit polyarticular JIA; the role of rituximab remains unclear. For the treatment of systemic JIA, while the TNFi are of less benefit, blockade of interleukin-1 or interleukin-6 is highly effective. Additionally, interleukin-1 blockade appears to be effective treatment of macrophage activation syndrome, one of the most dangerous complications of JIA; specifically, anakinra in combination with cyclosporine and corticosteroids may obviate the need for cytotoxic approaches. In contrast, methotrexate along with the TNFi and abatacept are effective agents for the management of uveitis, another complication of JIA. Overall, the biologics have demonstrated an impressive safety record in children with JIA, although children do need to be monitored for rare but potentially dangerous adverse events, such as tuberculosis and other infections; paradoxical development of additional autoimmune diseases; and possibly an increased risk of malignancy. Finally, there may be a window of opportunity during which children with JIA will demonstrate most optimal responses to aggressive therapy, underscoring the need for rapid diagnosis and initiation of treatment.
"extra-follicularly, could result in DNA damage response (DDR) activation with untoward consequences on cell proliferation or survival. In fact, uncontrolled activation coupled with cellular proliferation have been linked to pathologies such as autoimmune disorders  and lymphomas . "
[Show abstract][Hide abstract] ABSTRACT: B-cell activation and proliferation can be induced by a variety of extracellular stimuli. The fate of an activated B cell following mitogen stimulation can be dictated by the strength or duration of the signal, the expression of downstream signaling components necessary to promote proliferation, and the cell intrinsic sensors and regulators of the proliferative program. Previously we have identified the DNA damage response (DDR) signaling pathway as a cell intrinsic sensor that is activated upon latent infection of primary human B cells by Epstein-Barr virus (EBV). Here we have assessed the role of the DDR as a limiting factor in the proliferative response to non-viral B-cell mitogens. We report that TLR9 activation through CpG-rich oligonucleotides induced B-cell hyper-proliferation and an ATM/Chk2 downstream signaling pathway. However, B-cell activation through the CD40 pathway coupled with interleukin-4 (IL-4) promoted proliferation less robustly and only a modest DDR. These two mitogens, but not EBV, modestly induced intrinsic apoptosis that was independent from the DDR. However, all three mitogens triggered a DDR-dependent G1/S phase cell cycle arrest preventing B-cell proliferation. The extent of G1/S arrest, as evidenced by release through Chk2 inhibition, correlated with B-cell proliferation rates. These findings have implications for the regulation of extra-follicular B-cell activation as it may pertain to the development of auto-immune diseases or lymphoma.
PLoS ONE 01/2014; 9(1):e87299. DOI:10.1371/journal.pone.0087299 · 3.23 Impact Factor
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