Myelin-reactive T cells have been identified in patients with multiple sclerosis (MS) and healthy subjects with comparable frequencies, but the functional programs of self-reactive T cells that promote disease remain unknown. A total of 13,324 T cell libraries generated from blood of 23 patients and 22 healthy controls were interrogated for reactivity to myelin antigens. Libraries derived from CCR6+ myelin-reactive T cells from patients with MS exhibited significantly enhanced production of IFN-γ, IL-17, and GM-CSF compared to healthy controls. Single-cell clones isolated by MHC/peptide tetramers from CCR6+ T cell libraries also secreted more pro-inflammatory cytokines while clones isolated from controls secreted more IL-10. The transcriptomes of myelin-specific CCR6+ T cells from patients with MS were distinct from those derived from healthy controls, and of note, were enriched in Th17-induced experimental autoimmune encephalitis (EAE) gene signatures and gene signatures derived from Th17 cells isolated other human autoimmune diseases. These data, although not casual, imply that functional differences between antigen specific T cells from MS and healthy controls is fundamental to disease development and support the notion that IL-10 production from myelin-reactive T cells may act to limit disease progression, or even pathogenesis.

communications Figure 6. a) SEM image of the free-standing silver pillar on the cover slip, made by using a laser power of 1.14 mW and a linear scanning speed of 3 mm s À1 , taken at an observation angle of 45 8. The inset is a close-up view of the silver pillar parallel to the substrate, which demonstrates the linewidth of the smallest portion of the silver pillar as 180 nm. b) SEM image of silver pyramids, fabricated with a laser power of 1.3 mW and scanning speed of 2.5 mm s À1 , taken at an observation angle of 45 8. The inset on the left is a top view of the silver-pyramid array. The inset on the right is a close-up view of the silver pyramid.

IL-10-producing B cells have a regulatory effect in various mouse models for immunemediated disorders via secretion of IL-10, a potent immunoregulatory cytokine. However, currently, the signaling pathways that regulate IL-10 production in B cells are not well understood. Here, we show that TLR signaling, but not BCR activation or CD40 ligation, induces potent production of IL-10 in human B cells. We demonstrate that the activation of STAT3 and ERK is required for TLR-induced IL-10 production by B cells, since inhibition of STAT3 or ERK activation abrogates TLR-induced IL-10 production. We also uncover a novel function of the TLR-MyD88-STAT3 pathway in B cells, namely controlling IL-10 production, in addition to the known role for this pathway in antibody production. Furthermore, IFN-α, a member of the type I IFN family, differentially modulates TLR7/8-and TLR9-activated STAT3 and ERK in B cells, which provides an explanation for our findings that IFN-α enhances TLR7/8-induced, but not TLR9-induced IL-10 production. These results yield insights into the mechanisms by which TLR signaling regulates IL-10 production in B cells and how type I IFN modulates TLR-mediated IL-10 production by B cells, therefore providing potential targets to modulate the function of IL-10-producing B cells.Keywords: B10 cells r IL-10-producing B cells r Regulatory B cells r Toll-like receptor r Type I interferon Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionSeveral studies have demonstrated a regulatory effect of IL-10-producing B cells in various mouse models for immune-mediated diseases such as EAE, collagen-induced arthritis, and colitis [1][2][3][4][5]. The main mechanism of suppression by IL-10-producing B cells is via the release of IL-10, leading to the suppression of Th1-and Th17-cell responses [6,7] as well as suppression of TNF production by monocytes [8]. Although the expression of CD24, Correspondence: Dr. Bi-Sheng Liu e-mail: b.liu@lumc.nl CD27, and CD38 for human and CD1d and CD5 for murine B cells have been associated with IL-10 production, no specific markers or master-regulator transcription factors have, until now, been identified.It is believed that all mature B cells can produce IL-10, depending on the stimuli received [9,10]. TLR agonists, such as R848 or CpG, potently activate B cells and can induce IL-10 production by B cells [8][9][10][11]. TLR-triggering can directly be involved in the regulatory effect of B cells, since B-cell-specific MyD88-deficient mice do not recover from EAE [9]. Upon TLR stimulation, several signaling pathways, such as, the NF-κB, MAP kinase, and the PI-3K-Akt pathways are activated [12]. Yet, the signaling pathways responsible for IL-10 production in B cells are largely unknown.www.eji-journal.eu2122 Bi-Sheng Liu et al. Eur. J. Immunol. 2014. 44: 2121-2129 In APCs, stimulation of cells with TLR agonists can also lead to the production of . For monocytes and macrophages it is reported that TLR-triggering media...