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Tobon G.J.,University of Western Brittany | Renaudineau Y.,University of Western Brittany | Hillion S.,University of Western Brittany | Cornec D.,Brest University Medical School Hospital | And 3 more authors.
Arthritis and Rheumatism | Year: 2010

Objective To determine if the Fms-like tyrosine kinase 3 ligand (Flt-3L), a cytokine implicated in B cell ontogenesis and proliferation in hematologic malignancies, might be responsible for the increased numbers of circulating Bm2 and Bm2- B cell subsets in patients with primary Sjögren's syndrome (SS). Methods Serum levels of Flt-3L were measured in 64 patients with primary SS and in 20 healthy controls matched for age and sex. Flt-3L and its receptor Flt-3 were quantified in circulating B cells and in salivary gland (SG) biopsy tissues by immunofluorescence analysis. The effect of Flt-3L on circulating B lymphocytes was then determined by coculture with cells of a human SG (HSG) epithelial cell line. Results Serum levels of Flt-3L were increased in patients with primary SS as compared with controls (mean ± SD 135.8 ± 5.5 versus 64.4 ± 4.5 pg/ml; P < 0.001). Serum levels of Flt-3L in primary SS patients correlated with the numbers of Bm2 and Bm2- cells (r = 0.46, P < 0.0006), and Flt-3 was selectively expressed in Bm2 and Bm2- cells. B cell culture experiments showed that Flt-3L potentiated the proliferative effect of anti-IgM stimulation. In SGs, we found that infiltrating B cells expressed Flt-3 and epithelial cells produced Flt-3L. Finally, Flt-3L levels were associated with high disease activity scores and increased risk of developing lymphoma. Conclusion Serum levels of Flt-3L are elevated in patients with primary SS and correlate with abnormal B cell distribution. Flt-3 is mainly expressed by Bm2 and Bm2- cells. Serum levels of Flt-3L might explain the clinical evolution of primary SS to B cell lymphoma that is observed in some patients, thus opening the possibility of new avenues for therapy. © 2010 by the American College of Rheumatology.

Agmon-Levin N.,The Zabludowicz Center for Autoimmune Diseases | Kivity S.,The Zabludowicz Center for Autoimmune Diseases | Kivity S.,Sheba Medical Center | Kivity S.,Rheumatic Disease Unit | And 10 more authors.
Journal of Autoimmunity | Year: 2012

Background/purpose: Primary Sjögren's syndrome (SS) is a chronic autoimmune disease primarily involving the exocrine glands. The clinical picture of SS ranges from exocrinopathy to systemic disease affecting the lung, kidney, liver, skin, musculockeletal and nervous systems. The morbidity of SS is mainly determined by extraglandular disease and increased prevalence of lymphoma. Environmental and hormonal factors, such as vitamin-D may play a role in the pathogenic process and disease expression. Thus, we aimed to evaluate levels of vitamin-D and their association with manifestations of SS. Methods: Vitamin-D levels were determined in 176 primary SS patients and 163 matched healthy volunteers utilizing the LIAISON chemiluminescent immunoassays (DiaSorin-Italy). A correlation between vitamin-D levels and clinical and serological manifestations of SS was performed. Results: Mean vitamin-D levels were comparable between SS patients and control 21.2 ± 9.4 ng/ml and 22.4 ± 10 ng/ml, respectively. Peripheral neuropathy was diagnosed in 23% of SS patients and associated with lower vitamin-D levels (18.6 ± 5.5 ng/ml vs. 22.6±8 ng/ml (p = 0.04)). Lymphoma was diagnosed in 4.3% of SS patients, who had lower levels of vitamin-D (13.2 ± 6.25 ng/ml), compared to SS patients without lymphoma (22 ± 8 ng/ml), (p = 0.03). Other clinical and serological manifestations did not correlate with vitamin-D status. Conclusions: In this study, low levels of vitamin-D correlated with the presence of peripheral neuropathy and lymphoma among SS patients. The link between vitamin-D and neuropathy or lymphoma was reported in other conditions, and may support a role for vitamin-D in the pathogenesis of these processes. Plausible beneficial effect for vitamin-D supplementation may thus be suggested. © 2012 Elsevier Ltd.

Cosimo E.,University of Glasgow | McCaig A.M.,University of Glasgow | Carter-Brzezinski L.J.M.,University of Glasgow | Wheadon H.,University of Glasgow | And 9 more authors.
Clinical Cancer Research | Year: 2013

Purpose: Chronic lymphocytic leukemia (CLL) is currently incurable with standard chemotherapeutic agents, highlighting the need for novel therapies. Overcoming proliferative and cytoprotective signals generated within the microenvironment of lymphoid organs is essential for limiting CLL progression and ultimately developing a cure. Experimental Design: We assessed the potency of cyclin-dependent kinase (CDK) inhibitor CR8, a roscovitine analog, to induce apoptosis in primary CLL from distinct prognostic subsets using flow cytometry-based assays. CLL cells were cultured in in vitro prosurvival and proproliferative conditions to mimic microenvironmental signals in the lymphoid organs, to elucidate the mechanism of action of CR8 in quiescent and proliferating CLL cells using flowcytometry, Western blotting, and quantitative real-time PCR. Results: CR8 was 100-fold more potent at inducing apoptosis in primary CLL cells than roscovitine, both in isolated culture and stromal-coculture conditions. Importantly, CR8 induced apoptosis in CD40-ligated CLL cells and preferentially targeted actively proliferating cells within these cultures. CR8 treatment induced downregulation of the antiapoptotic proteins Mcl-1 and XIAP, through inhibition of RNA polymerase II, and inhibition of NF-κB signaling at the transcriptional level and through inhibition of the inhibitor of IκB kinase (IKK) complex, resulting in stabilization of Ik Ba expression. Conclusions: CR8 is a potent CDK inhibitor that subverts pivotal prosurvival and proproliferative signals present in the tumor microenvironment of CLL patient lymphoid organs. Our data support the clinical development of selective CDK inhibitors as novel therapies for CLL. ©2013 AACR.

Lemoine S.,European University of Brittany | Lemoine S.,Brest University Medical School Hospital | Morva A.,European University of Brittany | Youinou P.,European University of Brittany | And 3 more authors.
Journal of Autoimmunity | Year: 2011

Regulatory functions for B lymphocytes have been reported in murine models of autoimmune diseases in which B-cell deficient mice were shown to exhibit exacerbated disease. The B cells responsible for the immune regulations were identified as a subpopulation of interleukin 10-secreting cells. However, the mechanism of induction and the characteristics of regulatory B cells in humans have been hardly studied. This study reports that regulation of T cell responses can be induced by B cells following CD40-dependent cognate interaction. T cell proliferation and cytokine production were differentially regulated. Thus, CD40-induced regulatory B cells partially inhibited T cell proliferation following CD40 interaction without requirement of soluble factor. In contrast, modulation of Th1 differentiation resulted from CD80- and CD86-dependent interactions and from IL-10 production. The suppressive effects were mediated by CD19highIgD+CD38highCD24highCD5high B cells and appeared to be indirect, through the induction of regulatory T cells as indicated by the appearance of Foxp3+CD4+CD25+T cells. These data suggest that activation signals from T cells initiate regulatory properties in B cells that modulate T cell responses involving regulatory T cells. Finally, studies in autoimmune patients revealed that regulation of T cell proliferation was defective in systemic lupus erythematosus but efficient in other diseases. Restoration of efficient B-cell regulatory activity could provide innovative B-cell based treatment of autoimmune diseases. © 2011 Elsevier Ltd.

Youinou P.,European University of Brittany | Youinou P.,Brest University Medical School Hospital | Saraux A.,European University of Brittany | Saraux A.,Brest University Medical School Hospital | And 2 more authors.
Current Pharmaceutical Biotechnology | Year: 2012

T cells have originally occupied central stage of the debate on the type of lymphocytes governing the pathogenesis of Sjögren's syndrome (SS). However, B cells has since been substituted for T cells, and insights into their functions have revealed that they accomplish various tasks. Beyond the paradigm that T lymphocytes maintain strict control over B lymphocytes, these latter cells solicit their own help from the former, release a flurry of cytokines, and act as antigen- presenting cells. In SS, excessive of the B cell-activating factor (BAFF) may cause B-cell quantitative anomalies, such as inflation of mature B (Bm)2/Bm2' cells in the circulation, or accumulation of transitional type 2, marginal zone (MZ) and memory B cells within the exocrine gland infiltrates. These excesses are also associated with B-cell qualitative anomalies, such as the internal synthesis of BAFF, and a default mechanism that promotes the autoantibody production in ectopic germinal centers or MZ equivalents. Thus, SS should rather be conceived as a quintessential model for B cellinduced autoimmunity. Such a view opens novel prospects for treatment, and indeed B cell-ablative therapy has already been shown to be beneficial to these patients. © 2012 Bentham Science Publishers.

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