CD11c + B cells have been reported to be increased in autoimmune diseases, but they are detected in the blood of healthy individuals as well. We aimed to characterize CD11c + B cells from healthy donors by flow cytometry, microarray analysis, and in vitro functional assays. Here, we report that CD11c + B cells are a distinct subpopulation of B cells, enriched in the memory subpopulation even if their phenotype is heterogeneous, with overexpression of genes involved in B-cell activation and differentiation as well as in antigen presentation. Upon activation, CD11c + B cells can differentiate into antibody-secreting cells, and CD11c could be upregulated in CD11c − B cells by B-cell receptor activation. Finally, we show that patients with pemphigus, an autoimmune disease mediated by B cells, have a decreased frequency of CD11c + B cell after treatment, relative to baseline. Our findings show that CD11c + B cells are mainly memory B cells prone to differentiate into antibody secreting cells that accumulate with age, independently of gender.

Background Corticosteroids (CS) with or without adjuvant immunosuppressant agents are standard treatment for pemphigus vulgaris (PV). The efficacy of adjuvant therapies in minimizing steroid-related adverse events (AEs) is unproven. Objectives To utilize data collected in a French investigator-initiated, phase III, open-label, randomized controlled trial to demonstrate the efficacy and safety of rituximab and seek approval for its use in PV.Methods This was an independently conducted post hoc analysis of the moderateto-severe PV subset enrolled in the Ritux 3 study. Patients were randomized to rituximab plus 0Á5 or 1Á0 mg kg À1 per day prednisone tapered over 3 or 6 months, or 1Á0 or 1Á5 mg kg À1 per day prednisone alone tapered over 12 or 18 months, respectively (according to disease severity). The primary end point was complete remission at month 24 without CS (CRoff) for ≥ 2 months, and 24month efficacy and safety results were also reported.Results At month 24, 34 of 38 patients (90%) on rituximab plus prednisone achieved CRoff ≥ 2 months vs. 10 of 36 patients (28%) on prednisone alone. Median total cumulative prednisone dose was 5800 mg in the rituximab plus prednisone arm vs. 20 520 mg for prednisone alone. Eight of 36 patients (22%) who received prednisone alone withdrew from treatment owing to AEs; one rituximab-plus-prednisone patient withdrew due to pregnancy. Overall, 24 of 36 patients (67%) on prednisone alone experienced a grade 3/4 CS-related AE vs. 13 of 38 patients (34%) on rituximab plus prednisone. Conclusions In patients with moderate-to-severe PV, rituximab plus short-term prednisone was more effective than prednisone alone. Patients treated with rituximab had less CS exposure and were less likely to experience severe or life-threatening CS-related AEs. What's already known about this topic?Rituximab in pemphigus vulgaris, D.M. Chen et al. 1113 CI, confidence interval; CRoff, complete remission off prednisone therapy; IQR, interquartile range; N/A, not applicable; CRmin, complete remission on minimal prednisone therapy (prednisone dose ≤ 10 mg per day). a No adjustment for multiplicity was made for any secondary end points and the P-values should be interpreted with caution. b 95% confidence interval (CI) calculated using the corrected Newcombe interval. c P-value calculated using Fisher's exact test with mid-P correction. d P-value calculated using Mann-Whitney U-test.

for the French Study Group on Autoimmune Bullous Skin Diseases IMPORTANCE Rituximab and short-term corticosteroid therapy are the criterion standard treatments for patients with newly diagnosed moderate to severe pemphigus. OBJECTIVE To examine factors associated with short-term relapse in patients with pemphigus treated with rituximab. DESIGN, SETTING, AND PARTICIPANTS This post hoc analysis of a randomized clinical trial (Comparison Between Rituximab Treatment and Oral Corticosteroid Treatment in Patients With Pemphigus [RITUX 3]) conducted from January 1, 2010, to December 31, 2015, included patients from 20 dermatology departments of tertiary care centers in France from the RITUX 3 trial and 3 newly diagnosed patients treated according to the trial protocol. Data analysis was performed from February 1 to June 30, 2019.EXPOSURE Patients randomly assigned to the rituximab group in the RITUX 3 trial and the 3 additional patients were treated with 1000 mg of intravenous rituximab on days 0 and 14 and 500 mg at months 12 and 18 combined with a short-term prednisone regimen.MAIN OUTCOMES AND MEASURES Baseline (pretreatment) clinical and biological characteristics (Pemphigus Disease Area Index [PDAI] score, ranging from 0-250 points, with higher values indicating more severe disease) and changes in anti-desmoglein (DSG) 1 and anti-DSG3 values as measured by enzyme-linked immunosorbent assay during the 3 months after rituximab treatment were compared between patients with disease relapse and those who maintained clinical remission during the first 12 months after treatment. The positive and negative predictive values of these factors were calculated. RESULTS Among 47 patients (mean [SD] age, 54.3 [17.0] years; 17 [36%] male and 30 [64%] female) included in the study, the mean (SD) baseline PDAI score for patients with relapsing disease was higher than that of the patients with nonrelapsing disease (54 [33] vs 28 [24]; P = .03). At month 3, 7 of 11 patients with relapsing disease (64%) vs 7 of 36 patients with nonrelapsing disease (19%) had persistent anti-DSG1 antibody values of 20 IU/mL or higher and/or anti-DSG3 antibody values of 130 IU/mL or higher (P = .01). A PDAI score of 45 or higher defining severe pemphigus and/or persistent anti-DSG1 antibody values of 20 IU/mL or higher and/or anti-DSG3 antibody values of 130 IU/mL or higher at month 3 provided a positive predictive value of 50% (95% CI, 27%-73%) and a negative predictive value of 94% (95% CI, 73%-100%) for the occurrence of relapse after rituximab. CONCLUSIONS AND RELEVANCEThe findings suggest that initial PDAI score and changes in anti-DSG antibody values after the initial cycle of rituximab might help differentiate a subgroup of patients with high risk of relapse who might benefit from maintenance rituximab infusion at month 6 from a subgroup of patients with low risk of relapse who do not need early maintenance therapy. TRIAL REGISTRATION NCT00784589

Rheumatoid arthritis (RA) is the most common form of chronic inflammatory rheumatism. Identifying auto-antigens targeted by RA auto-antibodies is of major interest. Alpha-enolase (ENO1) is considered to be a pivotal auto-antigen in early RA but its pathophysiologic role remains unknown. The main objective of this study was to investigate the in vitro effects of soluble ENO1 on peripheral blood mononuclear cells (PBMC) from healthy donors and RA patients in order to determine the potential pathogenic role of ENO1. ELISA, transcriptomic analysis, experiments of receptor inhibition and flow cytometry analysis were performed to determine the effect, the target cell population and the receptor of ENO1. We showed that ENO1 has the ability to induce early production of pro-inflammatory cytokines and chemokines with delayed production of IL-10 and to activate the innate immune system. We demonstrated that ENO1 binds mainly to monocytes and activates the CD14-dependent TLR4 pathway both in healthy subjects and in RA patients. Our results establish for the first time that ENO1 is able to activate in vitro the CD14-dependent TLR4 pathway on monocytes involving a dual mechanism firstly pro-inflammatory and secondly anti-inflammatory. These results contribute to elucidating the role of this auto-antigen in the pathophysiologic mechanisms of RA.

Pemphigus is an autoimmune blistering disease mediated by autoantibodies directed against desmogleins (DSGs). We recently showed that first-line treatment with rituximab (RTX) enables more patients to achieve long-lasting remission off therapy than corticosteroids alone. To understand the immunological mechanisms that mediate long-lasting clinical remission after RTX treatment, we analyzed the phenotype of DSG-specific memory B cells and DSG-specific T follicular helper cells by flow cytometry and measured antibodysecreting cells by enzyme-linked immune absorbent spot in patients treated with corticosteroids alone or RTX. This post hoc analysis of the RITUX3 trial showed that RTX induced a significant decrease of IgG-switched DSG-specific memory B cells. Accordingly, anti-DSG antibody-secreting cells were no longer detected in patients in complete remission after RTX. In contrast, corticosteroids did not modify the frequency or the phenotype of DSG-specific memory B cells, and anti-DSG antibody-secreting cells were still detected after treatment, even in patients in remission. Using peptide-HLADRB1*0402 tetramer staining, we identified DSG-3especific T follicular helper cells, which dramatically decreased after RTX, while remaining stable after corticosteroid treatment. Our findings suggest that long-lasting response to RTX in pemphigus relies on the decrease of DSG-specific circulating T follicular helper cells, which correlates with a sustained depletion of IgG-switched memory autoreactive B cells, leading to the disappearance of anti-DSG antibody-secreting cells.

Bullous Pemphigoid is the most common auto-immune bullous skin disease. It is characterized by the production of auto-antibodies directed against 2 proteins of the hemi-desmosome (BP180 and BP230). We assessed the efficacy and mechanisms of action of rituximab, an anti-CD20 monoclonal antibody, in 17 patients with severe and relapsing type of bullous pemphigoid. The phenotype, cytokine gene expression, and rearrangement of BP180-specific B-cell receptor genes were performed over 2 years following treatment. At the end of the study, 5 patients had died, 3 had withdrawn from the study, and 9 patients were in complete remission. The one- and two-year relapse rates were 44.1% (95% Confidence Interval (CI): 21.0–76.0%) and 66.5%, (95% CI: 38.4–91.4%), respectively. Phenotypic analyses confirmed dramatic B-cell depletion, which lasted for 9 to 12 months. The ELISA values of serum anti-BP180 antibodies and the frequency of BP180-specific circulating B cells decreased dramatically following treatment, which paralleled the improvement of skin lesions. During B-cell reconstitution, a polyclonal IgM repertoire appeared and a shift in the rearrangement of the B-cell receptor genes of BP180-specific circulating B cells was observed. Concurrently, we observed a decrease of IL-15, IL-6 and TNFα expressing BP180-specific B cells, and the emergence of IL-10 and IL-1RA-expressing BP180-specific IgM+ B cells in patients in complete remission off therapy, suggesting the functional plasticity of BP180-specific auto-immune B cells after rituximab treatment.

Pemphigus Vulgaris is an autoimmune disease of the skin and mucous membranes, which is due to the production of pathogenic autoantibodies targeting desmoglein (DSG) 1 and 3, which are adhesion proteins of the keratinocytes. Rituximab is an anti-CD20 mAb which induces a prolonged depletion of blood B cells. We recently showed that rituximab was more effective than a standard oral corticosteroid (CS) treatment, allowing 90% of patients to achieve complete remission (CR). Additionally, we showed that DSG-specific-B (DSG positive) cells were still detectable during the B cell recovery which follows the initial rituximab-induced B cell depletion, even in patients in CR. In order to characterize DSG positive B cells in patients in CR after rituximab or CS treatment relative to those detectable at baseline in patients with an active pemphigus, we studied the expression profile of 31 genes of interest related to inflammatory cytokines, TNF receptors and activation markers. Using quantitative Polymerase Chain Reaction performed on one cell with a microfluidic technique, we found that patients' autoreactive B cells collected at baseline had a significantly higher expression of genes encoding for IL-1β, IL-23p19, and IL-12p35 pro-inflammatory cytokines and the IRF5 transcription factor, than non-autoreactive B cells. Surprisingly, the gene expression profile of DSG positive B cells collected after rituximab treatment in patients in CR was close to that of DSG positive B cells at baseline in patients with active pemphigus, except for the IL-1β and the CD27 memory marker genes, which were under-expressed after rituximab compared to baseline. Conversely, we observed a decreased expression of genes encoding for IL-1β and IL-23p19 in patients treated with CS relative to baseline. This study showed that: (i) DSG positive autoreactive B cells have a different gene expression profile than non-autoreactive B cells; (ii) rituximab and CS have different effects on the genes' expression in autoreactive DSG positive B cells from pemphigus patients.

BackgroundB and T cells play a key role in rheumatoid arthritis (RA) pathophysiology. RasGRP1 and RasGRP3 are involved in T and B cell receptors signaling, and belong to gene combination able to predict infliximab responsiveness, leading to the question of RasGRP1 and RasGRP3 involvement in RA.MethodsRasGRP1 and RasGRP3 expression levels were measured by qRT-PCR and/or western-blot in peripheral blood mononuclear cells (PBMCs), in T and B cells from untreated RA patients and in RA patients treated by TNFα inhibitors. T and B cells from healthy controls (HC) were cultured with TNFα, and TNFα receptors neutralizing antibodies to highlight the TNFα effects on RasGRP1 and RasGRP3 pathways. MAPK pathways and apoptosis were respectively analyzed using the Proteome Profiler arrays and flow cytometry.ResultsIn PBMCs from RA patients, gene expression levels of RasGRP1 were invariant while RasGRP3 was downregulated under TNFα inhibitors and upregulated under TNFα. In T cells from RA patients, RasGRP1 was decreased and its gene expression level was correlated with disease activity. In T cells from HC, TNFα stimulation increased RasGRP1 gene expression level while it reduced RasGRP1 protein expression level. Bryostatin-1 experiments have confirmed that the TNFα effect observed on T cells proliferation was due to the decrease of RasGRP1 expression. Besides, RasGRP3 expression level increased in PBMCs from RA patients under TNFα and in B cells from HC leading us to conclude that RasGRP3 in B cells was modulated by TNFα.ConclusionThis study demonstrates RasGRP1 dysregulation in RA patients while RasGRP3 is characterized as a biomarker linked to TNFα inhibitors. After binding to TNFR1, TNFα reduced RasGRP1 protein expression resulting in inhibition of T cell activation.Trial registrationClinicaltrials.gov NCT00234234, registered 04 November 2008; NCT00767325, registered 05 October 2005.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0894-9) contains supplementary material, which is available to authorized users.