Survival of plasma cells is regulated by B-cell maturation antigen (BCMA), a membrane-bound receptor activated by its agonist ligands BAFF and APRIL. Here we report that γ-secretase directly cleaves BCMA, without prior truncation by another protease. This direct shedding is facilitated by the short length of BCMA's extracellular domain. In vitro, γ-secretase reduces BCMA-mediated NF-κB activation. In addition, γ-secretase releases soluble BCMA (sBCMA) that acts as a decoy neutralizing APRIL. In vivo, inhibition of γ-secretase enhances BCMA surface expression in plasma cells and increases their number in the bone marrow. Furthermore, in multiple sclerosis, sBCMA levels in spinal fluid are elevated and associated with intracerebral IgG production; in systemic lupus erythematosus, sBCMA levels in serum are elevated and correlate with disease activity. Together, shedding of BCMA by γ-secretase controls plasma cells in the bone marrow and yields a potential biomarker for B-cell involvement in human autoimmune diseases.

In contrast to the other mutations and polymorphisms, heterozygous PTM is more common in patients with abortions in the first trimester. This might reflect an influence of PTM on pathogenesis of early pregnancy loss.

BackgroundFingolimod (FTY720) is the first sphingosine-1-phosphate (S1P) receptor modulator approved for the treatment of multiple sclerosis. The phosphorylated active metabolite FTY720-phosphate (FTY-P) interferes with lymphocyte trafficking. In addition, it accumulates in the CNS and reduces brain atrophy in multiple sclerosis (MS), and neuroprotective effects are hypothesized.MethodsHuman primary astrocytes as well as human astrocytoma cells were stimulated with FTY-P or S1P. We analyzed gene expression by a genome-wide microarray and validated induced candidate genes by quantitative PCR (qPCR) and ELISA. To identify the S1P-receptor subtypes involved, we applied a membrane-impermeable S1P analog (dihydro-S1P), receptor subtype specific agonists and antagonists, as well as RNAi silencing.ResultsFTY-P induced leukemia inhibitory factor (LIF), interleukin 11 (IL11), and heparin-binding EGF-like growth factor (HBEGF) mRNA, as well as secretion of LIF and IL11 protein. In order to mimic an inflammatory milieu as observed in active MS lesions, we combined FTY-P application with tumor necrosis factor (TNF). In the presence of this key inflammatory cytokine, FTY-P synergistically induced LIF, HBEGF, and IL11 mRNA, as well as secretion of LIF and IL11 protein. TNF itself induced inflammatory, B-cell promoting, and antiviral factors (CXCL10, BAFF, MX1, and OAS2). Their induction was blocked by FTY-P. After continuous exposure of cells to FTY-P or S1P for up to 7 days, the extent of induction of neurotrophic factors and the suppression of TNF-induced inflammatory genes declined but was still detectable. The induction of neurotrophic factors was mediated via surface S1P receptors 1 (S1PR1) and 3 (S1PR3).ConclusionsWe identified effects of FTY-P on astrocytes, namely induction of neurotrophic mediators (LIF, HBEGF, and IL11) and inhibition of TNF-induced inflammatory genes (CXCL10, BAFF, MX1, and OAS2). This supports the view that a part of the effects of fingolimod may be mediated via astrocytes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-015-0393-6) contains supplementary material, which is available to authorized users.

Objective. Tumor necrosis factor receptorassociated periodic syndrome (TRAPS) is an autosomal-dominantly inherited autoinflammatory disorder caused by mutations in the TNFRSF1A gene. It is characterized by episodes of autoinflammation usually associated with fever, abdominal pain, myalgia, exanthema, arthralgia/arthritis, and ocular involvement. We undertook this study to investigate the prevalence of TRAPS in patients with multiple sclerosis (MS) who reported, in addition to their neurologic symptoms, at least 2 other symptoms compatible with TRAPS.Methods. Twenty-five unrelated MS patients were prospectively screened for TNFRSF1A mutations. In addition, blood samples from 365 unrelated MS patients and 407 unrelated Caucasian controls were analyzed to determine the R92Q carrier frequency.Results. Six of 25 adult MS patients (24%) with symptoms suggestive of TRAPS were found to carry the identical arginine-to-glutamine substitution at amino acid position 92 (R92Q or p.Arg121Gln) encoded by exon 4 of the TNFRSF1A gene. All R92Q heterozygotes had similar symptoms, including arthralgias/arthritis, myalgias, urticarial rash, and severe fatigue, which began before the onset of MS. In 5 of the 6 patients, we could identify family members who had TRAPS symptoms and had inherited the identical mutation. The R92Q exchange was also detected in 17 of 365 unselected MS patients (4.66%) and in 12 of 407 controls (2.95%) (P ‫؍‬ 0.112). Three patients were heterozygous carriers of MEFV variants, in 1 patient in combination with the R92Q mutation.Conclusion. Autoinflammatory syndromes and especially late-onset TRAPS should be considered in MS patients who report symptoms such as arthralgias/ arthritis, myalgias, urticarial rash, and severe fatigue.

While some COVID-19 patients maintain SARS-CoV-2-specific serum IgGs for more than 6 months post-infection, others eventually lose IgG levels. We assessed the persistence of SARS-CoV-2-specific B cells in 17 patients, five of whom had lost specific IgGs after 5–8 months. Differentiation of blood-derived B cells in vitro revealed persistent SARS-CoV-2-specific IgG B-cells in all patients, whereas IgA-B cells were maintained in 11. Antibodies derived from cultured B cells blocked binding of viral receptor-binding domain (RBD) to the cellular receptor ACE-2, had neutralizing activity to authentic virus and recognized the RBD of the variant of concern Alpha similarly to the wild-type, while reactivity to Beta and Gamma were decreased. Thus, differentiation of memory B-cells could be more sensitive for detecting previous infection than measuring serum antibodies. Understanding the persistence of SARS-CoV-2 specific B cells even in the absence of specific serum IgG will help to promote long-term immunity.