Objective. There is evidence to support a dominant role for B cells in the pathophysiology of primary Sjö gren's syndrome (SS). Therefore, we evaluated the safety and efficacy of anti-CD20 monoclonal antibody.

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Objective. Treatment with rituximab depletes B cells from the peripheral blood (PB) and salivary glands (SGs) of patients with primary Sjögren's syndrome (SS). The purpose of this study was to track the repopulation of B cell subsets in PB as well as their subsequent homing into SGs in patients with primary SS treated with rituximab.Methods. A series of 4-color flow cytometry experiments delineated B cell subsets in 15 patients with primary SS. All were tested on days 8 and 15 of treatment. Nine of the patients were followed up monthly for 10 months, and the remaining 6 patients were followed up monthly for 24 months. Enzyme-linked immunosorbent assays were developed to measure serum levels of BAFF and rituximab. SGs were biopsied at the start of the study and 4 months after treatment in 15 patients, 12 months after treatment in 3 patients, and 24 months after treatment in 2 patients.Results. Baseline serum levels of BAFF correlated inversely (r ‫؍‬ ؊0.92, P < 5 ؋ 10 ؊4 ) with the duration of B cell depletion: the higher the BAFF levels, the shorter the duration of B cell depletion. Conclusion. The timing of B cell repopulation is modulated by BAFF and is followed by reconstitution of the preexisting abnormalities.

B lymphocytes from patients with systemic lupus erythematosus (SLE) are characterized by reduced expression levels of membrane CD5. Recent studies from our laboratory have revealed that the level of membrane CD5 is determined by the relative level of two alternative CD5 isoforms; CD5-E1A, which is expressed on the membrane, and CD5-E1B, which is retained in the cytoplasm. Using bisulfite sequencing and methylation-sensitive endonuclease assays we show that the promoter for the alternative CD5-E1B isoform is demethylated in B cells from patients with SLE but not in healthy controls. We go on to show that differential methylation is more pronounced following BCR engagement. As a result of this demethylation, CD5-E1B mRNA is transcribed at the expense of CD5-E1A mRNA transcription. We provide further evidence that production of high IL-6 levels by SLE B cells abrogates the ability of SLE B cells to induce DNA methyl transferase (DNMT1) and then to methylate DNA, an effect that is reversed in the presence of a blocking Ab to the IL-6 receptor. S ystemic lupus erythematosus (SLE)4 is associated with diverse clinical manifestations (1). The main features of autoimmunity in SLE are B cell hyperactivity, spontaneous lymphocyte proliferation, and the production of pathogenic Abs to self-Ags. B cell abnormalities in SLE also include excess cytokine production, autoantigen presentation to T cells and modulation of the function of other immune cells (2). Thus, SLE is generally considered a B cell disease, a theme strengthened by the efficacy of therapies targeting B cells. For example, therapeutic approaches using depleting anti-CD20 has proved to be highly beneficial in treatment of SLE (3). Further, neutralization of cytokines that promote B cell responses such as IL-6, or interruption of cognate T cell and B cell interactions has been successful in early clinical trials (4,5). All this provides the rationale for further investigation of mechanisms of B cell involvement in driving autoimmunity and to develop more selective therapeutic targets.The central role played by B cells in immunity necessitates that its responses are tightly regulated. B cell responses are initiated by signaling through the BCR. Signaling initiated following BCR engagement is regulated by coreceptors and by a network of protein tyrosine kinases and phosphatases. Recent findings suggest that defects in BCR-mediated signaling can result in lupus autoimmunity. For example, there is an association between SLE autoimmunity and mutations in a number of genes that encode B cellspecific signaling molecules including protein tyrosine kinases, non-receptor phosphatase type 22, B cell scaffold protein with ankyrin repeats 1 and the inhibitory IgG Fc␥RIIb (6). In addition to direct evidence for the effect of mutations in signaling molecules on BCR-mediated signaling, the contribution of epigenetic factors has also been proposed (7). The most commonly observed epigenetic abnormality implicated in SLE pathology is altered DNA methylation at the 5-carbon positio...

BackgroundGlucocorticoids are the cornerstone treatment of polymyalgia rheumatica (PMR) but induce adverse events.ObjectivesTo evaluate the efficacy and safety of first-line tocilizumab in PMR.MethodsIn a prospective open-label study (ClinicalTrials.gov: NCT01713842), 20 glucocorticoid-free patients fulfilling Chuang's PMR criteria, with symptom onset within the last 12 months and a PMR activity score (PMR-AS) >10, each received three tocilizumab infusions at 4-week intervals, without glucocorticoids, followed by oral prednisone from weeks 12 to 24 (0.15 mg/kg if PMR-AS ≤10 and 0.30 mg/kg otherwise). The primary end point was the proportion of patients with PMR-AS≤10 at week 12.ResultsBaseline median PMR-AS was 36.6 (IQR 30.4–43.8). At week 12, all patients had PMR-AS≤10 and received the low prednisone dosage. Median PMR-AS at weeks 12 and 24 was 4.5 (3.2–6.8) and 0.95 (IQR 0.4–2), respectively (p<0.001 vs baseline for both time points). No patient required rescue treatment. Positron emission tomography-CT showed significant improvements. The most common adverse events were transient neutropenia (n=3) and leucopenia (n=5); in one patient, the second tocilizumab infusion was omitted due to leucopenia.ConclusionsTocilizumab monotherapy is effective in recent-onset PMR. Randomised controlled trials are warranted.Trial registration numberNCT01713842.

10Epigenetics signifies stable and heritable changes in gene expression without changes in the genetic code. There is a wealth of emerging evidence for such processes in promoting autoimmunity. The first clue is that inhibition of DNA methyl transferases (DNMTs) induces systemic lupus erythematosus (SLE) in animals. Similar immune-mediated disorders have been generated by injecting normal T cells incubated with DNMT inhibitors into healthy mice. Further, monozygotic twins display differences in DNA methylation that parallel discordances in SLE. Moreover, defects in DNA methylation characterize lymphocytes from SLE, synoviocytes from rheumatoid arthritis, and neural cells from multiple sclerosis patients. It has also been shown that DNA hypomethylation of T and B cells correlates with reduced DNMT efficacy and histone acetylation in SLE. Once a gene promoter has been demethylated, the gene recovers its capacity to be transcribed, e.g., genes for cytokines, activation receptors on cells, and endogenous retroviruses. This outcome has been associated with a blockage of the Erk pathway and/ or a growth arrest at the G0/G1 interface of the cell cycle. Of importance is the fact that these changes can be reversed.

IntroductionAlthough intravenous immunoglobulin (IVIg) is widely used to treat idiopathic thrombocytopenic purpura, Kawasaki disease, systemic lupus erythrematosus and Guillain-Barré syndrome, 1 the mechanisms by which immune functions are influenced by such preparations remain to be delineated. 2 Because B lymphocytes play a central role in the immunopathologic processes that cause these diseases, several studies have suggested that B cells are the target cells for the beneficial effect of IVIg. For this hypothesis to apply, IVIg would modulate a broad range of B lymphocyte functions including activation, proliferation, 3 and survival. 4 In other words, IVIg would interfere with the expression of genes and, potentially, the functions of proteins involved in cell growth and death.The interaction between IVIg and B lymphocytes could thus modulate intracellular signaling resulting from the engagement of the B-cell antigen (Ag) receptor (BCR). The earliest signaling events of the ensuing cascade involves activation of the Src-family protein-tyrosine kinase (PTK) Lyn. 5 Activated Lyn phosphorylates immunoreceptor tyrosine-based activation motifs (ITAMs) on the cytoplasmic domain of the membrane ␣ and ␤ proteins (CD79␣ and CD79␤). Once phosphorylated, CD79␣ and CD79␤ recruit another PTK protein, Syk. Syk associates with phospho-ITAMs via its tandem Src-homology 2 (SH2) domains, is phosphorylated, and in turn, phosphorylates the adaptor protein B-cell linker protein (BLNK). The adaptor thus acquires the capacity to bind to and activate Bruton's tyrosine kinase (Btk). This sequence of signaling events leads to the activation of phospholipase C␥2 (PLC␥2), hydrolysis of phosphatidylinisitol-4,5-bisphosphate and the production of inositol-1,4,5-trisphosphate.As a result, released intracellular calcium synergizes with other signals to induce gene transcription. 6 This promotion implies the recruitment of several transcription factors (TFs) that influence B-cell proliferation, differentiation, cytokine production, and apoptosis. 7,8 The outcome of BCR engagement is variable, depending on the status of the B cell and commitment of coreceptors. The latter dictate the ultimate response and associate positive regulators (such as CD19 and CD21) and negative regulators (such as CD22 and CD32) and these ultimately determine the outcome of B-cell responses. Under normal conditions, both groups of proteins are expressed at varying levels on the surface of all B lymphocytes and their engagement contributes to setting the threshold of B-cell activation. This is often achieved by increasing or decreasing tyrosine phosphorylation, thereby enhancing or reducing signal transduction. 9 CD22 conveys the SH2 domain-containing phosphatase 1 (SHP-1) over to the BCR through the immunoreceptor tyrosinebased inhibition motifs (ITIMs) located in its cytoplasmic domain. 10 This membrane protein belongs to the sialic acid (SA)-binding Ig-like lectin (Siglec) superfamily, with 7 Ig-like extracellular domains and an amino-terminal Ig domain. CD22 is u...

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