Regulatory B cells (Breg cells) differentiate in response to inflammation and subsequently restrain excessive immune responses via the release of interleukin-10 (IL-10). However, the precise inflammatory signals governing their differentiation remain to be elucidated. Here we show that the gut microbiota promotes the differentiation of Breg cells in the spleen as well as in the mesenteric lymph nodes. Perturbation of the gut microbiome imposed either by antibiotic treatment or by changes in the sterility of housing conditions reduces the number and function of Breg cells. Following the induction of arthritis, IL-1β and IL-6 are produced only in conventionally housed mice and both cytokines directly promote Breg cell differentiation and IL-10 production. Mice lacking IL-6 receptor (IL-6R) or IL-1 receptor 1 (IL-1R1) specifically on B cells have a reduced number of IL-10-producing B cells and develop exacerbated arthritis compared to control animals. Thus, in response to inflammatory signals induced by both the gut flora and arthritis, Breg cells increase in number and restrain excessive inflammation.

IL-10–producing B cells, also known as regulatory B cells (Bregs), play a key role in controlling autoimmunity. In this study, we report that chimeric mice specifically lacking IL-10–producing B cells (IL-10−/−B cell) developed an exacerbated arthritis compared with chimeric wild-type (WT) B cell mice. A significant decrease in the absolute numbers of Foxp3 regulatory T cells (Tregs), in their expression level of Foxp3, and a marked increase in inflammatory Th1 and Th17 cells were detected in IL-10−/− B cell mice compared with WT B cell mice. Reconstitution of arthritic B cell deficient (μMT) mice with different B cell subsets revealed that the ability to modulate Treg frequencies in vivo is exclusively restricted to transitional 2 marginal zone precursor Bregs. Moreover, transfer of WT transitional 2 marginal zone precursor Bregs to arthritic IL-10−/− mice increased Foxp3+ Tregs and reduced Th1 and Th17 cell frequencies to levels measured in arthritic WT mice and inhibited inflammation. In vitro, IL-10+/+ B cells established longer contact times with arthritogenic CD4+CD25− T cells compared with IL-10−/− B cells in response to Ag stimulation, and using the same culture conditions, we observed upregulation of Foxp3 on CD4+ T cells. Thus, IL-10–producing B cells restrain inflammation by promoting differentiation of immunoregulatory over proinflammatory T cells.

IntroductionInterleukin-10 (IL-10) producing B cells, also known as regulatory B (Breg) cells, play a key role in controlling autoimmunity. Our laboratory and others have demonstrated a pivotal role for Bregs in rheumatological disorders, including experimental models of arthritis and lupus. The aim of this study was to identify the role of endogenous IL-10 secreting B cells in vivo in controlling the induction and disease progression of collagen-induced arthritis (CIA).MethodsWe generated chimeric mice that had IL-10 knocked-out specifically in the B cell population. These mice were compared with wild-type (WT) B cell chimeric mice for their susceptibility to CIA.ResultsHere we report that chimeric mice specifically lacking IL-10 producing B cells (IL-10-/- B cell) developed an exacerbated CIA compared to chimeric wild type B cell (WT B cell) mice. A marked increase in inflammatory Th1 and Th17 cells were detected in IL-10-/-B cell mice compared to WT B cell mice. Furthermore, there was a reduction in IL-10 secreting CD4+ Tr1 cells in these animals.ConclusionsIL-10 producing B cells restrain inflammation by promoting differentiation of immuno-regulatory over pro-inflammatory T cells and, hence, act to maintain tolerance.

Patients deficient in the cytoskeletal regulator Wiskott–Aldrich syndrome protein (WASp) are predisposed to varied autoimmunity, suggesting it has an important controlling role in participating cells. IL-10-producing regulatory B (Breg) cells are emerging as important mediators of immunosuppressive activity. In experimental, antigen-induced arthritis WASp-deficient (WASp knockout [WAS KO]) mice developed exacerbated disease associated with decreased Breg cells and regulatory T (Treg) cells, but increased Th17 cells in knee-draining LNs. Arthritic WAS KO mice showed increased serum levels of B-cell-activating factor, while their B cells were unresponsive in terms of B-cell-activating factor induced survival and IL-10 production. Adoptive transfer of WT Breg cells ameliorated arthritis in WAS KO recipients and restored a normal balance of Treg and Th17 cells. Mice with B-cell-restricted WASp deficiency, however, did not develop exacerbated arthritis, despite exhibiting reduced Breg- and Treg-cell numbers during active disease, and Th17 cells were not increased over equivalent WT levels. These findings support a contributory role for defective Breg cells in the development of WAS-related autoimmunity, but demonstrate that functional competence in other regulatory populations can be compensatory. A properly regulated cytoskeleton is therefore important for normal Breg-cell activity and complementation of defects in this lineage is likely to have important therapeutic benefits.

Contrasting results have emerged from studies performed using IL-12p35−/− mice. Animals lacking the IL-12p35 subunit can either be protected from or develop exacerbated autoimmune diseases, intracellular infections, and delayed-type hypersensitivity responses. In this study, we report that mice lacking the IL-12p35 subunit develop a significantly milder Ag-induced arthritis compared with wild-type (WT) mice. Lack of severe inflammation is accompanied by an increase in the mRNA levels of the Ebi-3 and p28 subunits and increased secretion of IL-27 and IL-10. This anti-inflammatory environment contributed to increased differentiation of regulatory T and B cells with intact suppressive function. Furthermore, IL-12p35−/− mice display reduced numbers of Th17 cells compared with WT arthritic mice. Neutralization of IL-27, but not the systemic administration of IL-12, restored inflammation and Th17 to levels seen in WT mice. The restoration of disease phenotype after anti–IL-27 administration indicates that the IL-12p35 subunit acts as negative regulator of the developing IL-27 response in this model of arthritis.

Inuit living in Nunavut have harvested light geese and lived near goose colonies for generations. Inuit knowledge includes important information about light goose ecology and management that can inform co-management and enhance scientific research and monitoring. Since the 1970s, populations of light geese (Snow and Ross’ Geese; kanguit and kangunnait in Inuktut; Chen caerulescens and Chen rossii) have experienced significant increases in abundance which led to habitat alteration in some portions of the central and eastern Canadian Arctic. In response to concerns expressed by Inuit and wildlife managers about light goose abundance, we conducted a collaborative research project in Arviat and Salliq (Coral Harbour), Nunavut, aiming to mobilize and document Inuit knowledge about light goose ecology and management in the Kivalliq region. Here we explore the potential of collaborative research for mobilizing Inuit knowledge to support informed and inclusive decision-making about wildlife resources. First, we describe the participatory research methods employed to explore Inuit-identified management recommendations for light geese, and engage co-management partners and research contributors to explore select management options. Then, we present these light goose management recommendations and options. Lastly, we discuss opportunities and challenges around the use of collaborative research to support wildlife co-management and Inuit self-determination.

IntroductionApoptosis plays a key role in the selection processes that result in clonal deletion of autoreactive B lymphocytes during their development. 1,2 The murine B-cell lymphoma cell line WEHI-231 has been widely used as a model for dissecting the molecular mechanisms underlying clonal deletion of immature B lymphocytes. This is because WEHI-231 cells have the cell surface phenotype of immature B cells (membrane immunoglobulin M-positive [mIgM ϩ ], mIgD Ϫ/low , FcR low , Fas low , and major histocompatibility complex [MHC] class II low ) and undergo growth arrest and apoptosis following ligation of the B-cell receptor (BCR). Moreover, WEHI-231 B cells can be rescued from BCR-mediated apoptosis by T-cell-dependent factors such as costimulation via CD40 ligation. [3][4][5] The precise signaling mechanisms underlying such commitment to apoptosis or rescue of immature B cells remain to be defined. We have recently shown, however, that the BCR couples to up-regulation of cytosolic phospholipase A 2 (cPLA 2 ) expression, induction of mitochondrial phospholipase A 2 activity, arachidonic acid-mediated collapse of mitochondrial potential (⌬ m ), and depletion of cellular adenosine triphosphate (ATP) under conditions of apoptotic, but not proliferative, signaling in WEHI-231 B cells. 6,7 Importantly, such disruption of ⌬ m , ATP depletion, and apoptosis can be prevented by rescue signals via CD40. 6,7 It is well established that CD40-mediated induction of Bcl-x L , and other antiapoptotic Bcl-2 family members, plays a key role in protecting WEHI-231 cells from BCR-driven apoptosis by stabilizing ⌬ m and mitochondrial homeostasis. 5,[8][9][10][11][12][13][14] Protection of mitochondrial integrity is central to cell survival as collapse of ⌬ m results in the release of factors that promote apoptosis. These factors (eg, cytochrome C, apoptosis-inducing factor, caspaseindependent endonuclease) act to promote the activation of effector caspases, alternative executioner proteases, or directly induce apoptosis. [15][16][17][18][19][20][21] The relative roles of various putative executioner proteases in BCR-driven apoptosis of WEHI-231 B cells are as yet unclear. For example, although caspase activation has been reported to be associated with such BCR-driven apoptosis, 8,13,22,23 the release of cytochrome C from the mitochondria, which is critical for activation of effector caspases, 15,24 does not appear to occur in these cells. 6,23 Moreover, alternative executioner proteases such as calpains and cathepsins 21,24,25 have recently been shown to play a role in BCR-driven apoptosis of WEHI-231 cells. 6,23 Indeed, apoptosis of WEHI-231 cells resulting from BCR coupling to the mitochondrial PLA 2 pathway is cathepsin B-dependent and occurs even in the presence of caspase inhibition. These apparently conflicting findings are likely to be reconciled, however, by the increasing evidence that caspases are not necessarily sufficient for apoptosis and that complex interactions of death signaling pathways are required for commitmen...

Bio-electrospraying (BES) and aerodynamically assisted bio-jetting (AABJ), two non-contact direct cell handling approaches, have recently undergone rigorous scientific testing to assess whether cells retain chemical, physical and more importantly biological functions similarly to their unmanipulated counterparts. Previous in vitro validation of these two approaches has shown that they are inert for the direct handling and distributing of cells with great accuracy. In the present investigation we aim to validate, in vivo, that the spray techniques do not functionally or phenotypically alter splenic cells. By taking advantage of an adoptive transfer mouse model we demonstrated that the in vivo behaviour of treated cells is indistinguishable from unmanipulated cells following adoptive transfer into C57/BL6 mice. Indeed, sprayed cells survived and proliferated in response to antigen activation to similar levels observed in unmanipulated cells. In addition, in vivo sprayed cells displayed identical migratory characteristics to those observed in unmanipulated cells. Thus, demonstrating the inertness of these biosprays. Hence these biotechniques hold great potential for use in the development of three-dimensional cultures, tracking and monitoring cell-interactions and in vitro modelling of disease-states and therapeutics.