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The conventional classification of mature B cells overlooks the diversity within IgD+ CD27− naïve B cells. Here, to identify distinct mature naïve B cells, we categorized CD45RBMEM55- B cells (NA RB-) and CD45RBMEM55+ B cells (NA RB+) and explore their function and localization in circulation and tissues under physiological and pathological conditions. NA RB+ B cells, found in secondary lymphoid organs, differentiate into plasmablasts and secrete IgM. In Sjögren's disease, their numbers decrease, and they show over-activation and abnormal migration, suggesting an adaptive disease response. NA RB+ B cells also appear in inflamed salivary glands, indicating involvement in local immune responses. These findings highlight the distinct roles of NA RB+ B cells in health and Sjögren's disease. [Display omitted] •.IgD+ CD45RBMEM55+ (NA RB+) and IgD+ CD45RBMEM55- B cells are phenotypically, transcriptionally, and functionally distinct. • NA RB+ B cells normally circulate between lymphoid organs but are recruited to inflamed salivary glands in Sjögren's Disease. • In Sjögren's Disease, NA RB+ B cells show an activated phenotype, altered migration, and are near ectopic lymphoid structures. [ABSTRACT FROM AUTHOR]

Abstract: Be they follicular cells within the germinal centers (GCs) or marginal zone (MZ), all naïve mature B lymphocytes need tonic signaling to stay alive. We reasoned that the same holds true for those B lymphocytes that proliferate in the salivary glands (SGs) of patients with primary Sjögren’s syndrome. Based on B cell infiltration, 11 SGs and three tonsil samples were selected for further examination. Tissue sections were stained using CD20 combined with CD10, CD21, CD27, CD38 or IgD. They were also laser-microdissected for quantitative RT-PCR of transcription factors, GC-specific activation-induced cytidine deaminase (AID) and TLR9. Some B cell aggregates proved to be real GCs according to their membrane markers, whereas others were clusters of transitional type II B cells. These contained mRNAs for Notch-2 and Blimp-1, but not for Pax-5, Bcl-6 and AID. Unanticipated was the finding of mRNAs for TLR9 in these clusters of MZ B-cells, but not in the real GCs. Not only do TLR9 deliver sufficiency of tonic signaling to keep B cells alive, but they also confer autoreactive B cells with an MZ-like phenotype. Thus, TLRs might be targets for forthcoming biotherapies. [Copyright &y& Elsevier]

Abstract: Sjögren''s syndrome (SS) is an autoimmune exocrinopathy characterized by an epithelium injury with dense lymphocytic infiltrates, mainly composed of activated T and B cells. Present at the interface of genetic and environmental risk factors, DNA methylation is suspected to play a key role in SS. To clarify this point, global DNA methylation was tested within salivary gland epithelial cells (SGEC), peripheral T cells and B cells from SS patients. Global DNA methylation was reduced in SGEC from SS patients, while no difference was observed in T and B cells. SGEC demethylation in SS patients was associated with a 7-fold decrease in DNA methyl transferase (DNMT) 1 and a 2-fold increase in Gadd45-alpha expression. The other DNA methylation/demethylation partners, tested by real time PCR (DNMT3a/b, PCNA, UHRF1, MBD2, and MBD4), were not different. Interestingly, SGEC demethylation may be attributed in part to the infiltrating B cells as suspected in patients treated with anti-CD20 antibodies to deplete B cells. Such hypothesis was confirmed using co-culture experiments with human salivary gland cells and B cells. Furthermore, B cell-mediated DNA demethylation could be ascribed to an alteration of the PKC delta/ERK/DNMT1 pathway. As a consequence, part of the SGEC dysfunction in SS may be linked to epigenetic modifications, thus opening new therapeutic perspectives in SS. [Copyright &y& Elsevier]

Abstract: CD6 is one of a pair of related genes encoding CD5-associated receptors on all T cells and a subset of B cells. The current availability of “T1h”, a humanized anti-CD6 monoclonal antibody for B cell-mediated autoimmune disorders revives analysis of the B-cell subset expression of CD6, particularly in primary Sjögren’s syndrome (SS). Refined phenotype of B-lymphocytes peripheral blood (PB), bone marrow and tonsils revealed that the overlap between the expression of CD6 is less close to that of CD5 than currently acknowledged. In contrast to CD5, CD6 is absent on transitional B cells, while present on mature and memory B cells. Interestingly, the PB proportion of CD6+ B cells is decreased in patients with primary SS, as opposed to those with rheumatoid arthritis. The reduction in primary SS does not result from the shedding of CD6 from the membrane of B cells, but from the lowering of memory B lymphocytes. It may result from the ability of CD6 to make transmigration of CD27+ memory B cells into the salivary glands (SGs) easier. Consistent with this view is our finding that CD166 (one of the ligands for CD6) is highly expressed on epithelial cells of patients’ SGs. This study is relevant in that the humanized T1h anti-CD6 becomes an alternative to anti-CD20 for treatment of primary SS. [Copyright &y& Elsevier]

Abstract: There is a crucial need for reliable diagnostic criteria for SS. Our objective was to evaluate the frequency of xerosis in patients with primary Sjögren’s syndrome (SS), and compare histopathology of cutaneous sweat glands and labial salivary glands (LSGs), with respect to their contribution to the diagnosis. Twenty-two patients with primary SS and 22 matched normal volunteers were invited to rate their skin dryness on a visual analog scale. The skin was dryer (58.3 ± 10.1 versus 38.9 ± 7.6, P < 0.01), and xerosis more frequent (9 of 22 versus 2 of 22, P < 0.02) in the patients than in the controls. The axilla skin was chosen for a 6-mm punch biopsy. Lymphocytic infiltration was seen in the skin of 8 of the 12 patients tested. Two of them had normal LSGs. Most interestingly, B cell infiltrates were identified in patients’ skin infiltrates, so that their presence might be a clue to the diagnosis of primary SS. These cell aggregates associated memory CD10−/CD20+/CD27+/IgD− B lymphocytes and immature CD20+/CD24 + lymphocytes. These latter findings strongly suggest that skin biopsies warrant inclusion into the routine clinical care of patients suspected of suffering from primary SS. [ABSTRACT FROM AUTHOR]