The use of B-cell targeted therapies for the treatment of systemic lupus erythematosus (SLE) has generated great interest owing to the multiple pathogenic roles carried out by B cells in this disease. Strong support for targeting B cells is provided by genetic, immunological and clinical observations that place these cells at the center of SLE pathogenesis, as initiating, amplifying and effector cells. Interest in targeting B cells has also been fostered by the successful use of similar interventions to treat other autoimmune diseases such as rheumatoid arthritis, and by the initial promise shown by B-cell depletion to treat SLE in early studies. Although the initial high enthusiasm has been tempered by negative results from phase III trials of the B-cell-depleting agent rituximab in SLE, renewed vigor should be instilled in the field by the convergence of the latest results using agents that inhibit B-cell-activating factor (BAFF, also known as BLyS and tumor necrosis factor ligand superfamily, member 13b), further analysis of data from trials using rituximab and greatly improved understanding of B-cell biology. Combined, the available information identifies several new avenues for the therapeutic targeting of B cells in SLE.
"Based on these observations, we hypothesized that iguratimod is a plausible candidate for the treatment of another autoimmune disease, systemic lupus erythematosus (SLE), since all of the mechanisms described participate in the development of this disease. – "
[Show abstract][Hide abstract] ABSTRACT: Objective
This study was performed to investigate the therapeutic effects of iguratimod in a lupus mouse model.
Female MRL/lpr mice were treated with iguratimod, vehicle solution or cyclophosphamide. Proteinuria was monitored and kidney injury was blindly scored by a renal pathologist. Serum anti-double-stranded DNA antibodies were monitored by radioimmunoassay. Kidney IgG and CD20 were stained by immunohistochemistry. Splenic lymphocyte phenotypes were analyzed by flow cytometry. BAFF, IL-17A, IL-6, and IL-21 levels in serum and splenic lymphocytes were detected by ELISA or quantitative PCR.
Compared with the vehicle-treated controls, MRL/lpr mice treated with iguratimod showed less protenuria, less acute pathological lesions and no chronic changes in the kidneys. There were significant differences in glomerular injury and vasculitis scores, as well as in the semi-quantitave analysis of immune complex deposition between the two groups. Disease activity markers in sera (anti-dsDNA antibodies and immunoglobulin levels) were reduced and hypocomplementemia was attenuated. Lymphocyte expression of BAFF, IL-6, IL-17A and IL-21 was decreased. The abnormal splenic B220+ T cell and plasma cell populations in MRL/lpr mice were reduced by iguratimod treatment, with recovery of the total B cell population and inhibition of B cell infiltration of the kidney tissue. The dosage of iguratimod used in this study showed no significant cytotoxic effects in vivo and no overt side-effects were observed.
Iguratimod ameliorates immune nephritis in MRL/lpr mice via a non-antiproliferative mechanism. Our data suggest a potential therapeutic role of iguratimod in lupus.
PLoS ONE 10/2014; 9(10):e108273. DOI:10.1371/journal.pone.0108273 · 3.23 Impact Factor
"In many autoimmune diseases, B cells are often major drivers of the autoimmune response through production of autoantibodies, and other functions such as antigen presentation and cytokine or chemokine production –. Thus, although the major clinical immunosuppressive agents are targeting T cell activation, there is increasing interest in treating autoimmune diseases by depleting B cells or suppressing B cell survival with drugs such as rituximab (anti-CD20 mAb) and belimumab (anti-BAFF mAbs) , . "
[Show abstract][Hide abstract] ABSTRACT: The antimalarial drug artemisinin and its derivatives exhibit potent immunosuppressive activity in several autoimmune disease models, however the mechanisms are not well-understood. This study was designed to investigate the therapeutic effects and the underlying mechanisms of the artemisinin analog artesunate using the K/BxN mouse model of rheumatoid arthritis. The well-studied disease mechanisms of K/BxN model allowed us to pinpoint the effect of artesunate on disease. Artesunate treatment prevented arthritis development in young K/BxN mice by inhibiting germinal center (GC) formation and production of autoantibodies. In adult K/BxN mice with established arthritis, artesunate diminished GC B cells in a few days. However, artesunate did not affect the follicular helper T cells (Tfh). In contrast to the spontaneous K/BxN model, artesunate treatment exerted minor influence on K/BxN serum transfer induced arthritis suggesting that artesunate has minimal effect on inflammatory responses downstream of antibody production. Finally, we showed that artesunate preferentially inhibits proliferating GC B cells. These results identify GC B cells as a target of artesunate and provide a new rationale for using artemisinin analogues to treat autoimmune diseases mediated by autoantibodies.
PLoS ONE 08/2014; 9(8):e104762. DOI:10.1371/journal.pone.0104762 · 3.23 Impact Factor
"Activity of Human CD20-Specific IgG Subclasses in Humanized Mice Because CD20 is the major target for therapeutic B celldepleting antibodies, we next assessed the CD20 expression pattern on human B cells developing in humanized mice and humans (Johnson and Press, 2000; Sanz and Lee, 2010). As shown in Figure 5A, CD20 was highly expressed on all IgM+ B cell populations in the blood, spleen, and bone marrow of humanized mice. "
[Show abstract][Hide abstract] ABSTRACT: Genetic differences between humans and in vivo model systems, including mice and nonhuman primates, make it difficult to predict the efficacy of immunoglobulin G (IgG) activity in humans and understand the molecular and cellular mechanisms underlying that activity. To bridge this gap, we established a small-animal model system that allowed us to study human IgG effector functions in the context of an intact human immune system without the interference of murine Fcγ receptors expressed on mouse innate immune effector cells in vivo. Using a model of B cell depletion with different human IgG variants that recognize CD20, we show that this humanized mouse model can provide unique insights into the mechanism of human IgG activity in vivo. Importantly, these studies identify the bone marrow as a niche with low therapeutic IgG activity.
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