Patients with type 2 diabetes (T2D) have disease-associated changes in B-cell function, but the role these changes play in disease pathogenesis is not well established. Data herein show B cells from obese mice produce a proinflammatory cytokine profile compared with B cells from lean mice. Complementary in vivo studies show that obese B cell-null mice have decreased systemic inflammation, inflammatory B-and T-cell cytokines, adipose tissue inflammation, and insulin resistance (IR) compared with obese WT mice. Reduced inflammation in obese/insulin resistant B cell-null mice associates with an increased percentage of anti-inflammatory regulatory T cells (Tregs). This increase contrasts with the sharply decreased percentage of Tregs in obese compared with lean WT mice and suggests that B cells may be critical regulators of T-cell functions previously shown to play important roles in IR. We demonstrate that B cells from T2D (but not non-T2D) subjects support proinflammatory T-cell function in obesity/T2D through contact-dependent mechanisms. In contrast, human monocytes increase proinflammatory T-cell cytokines in both T2D and non-T2D analyses. These data support the conclusion that B cells are critical regulators of inflammation in T2D due to their direct ability to promote proinflammatory T-cell function and secrete a proinflammatory cytokine profile. Thus, B cells are potential therapeutic targets for T2D.immunometabolism | lymphocytes M ultiple studies support the concept that inflammation strongly associates with insulin resistance (IR), which, in addition to loss of islet function, defines type 2 diabetes (T2D) (1). Work implicating B cells in IR/T2D is limited. We showed B cells from T2D subjects secrete a proinflammatory cytokine profile, including an extraordinary inability to secrete the potent anti-inflammatory cytokine IL-10 and an elevated production of proinflammatory IL-8 compared with B cells from non-T2D subjects (2). Given the importance of B-cell IL-10 in preventing numerous inflammatory diseases (3, 4) and the links between IL-8 and T2D (5, 6), these data suggest that altered B-cell cytokine production plays an important role in initiating or promoting IR/T2D. Published analyses further support a role for B cells in IR and include studies of B cell-null New Zealand Obese (NZO) mice, which, in contrast to B cell-sufficient NZOs, fail to develop IR in response to obesity (7). These findings have been recently reproduced in studies showing obese B cell-null or B cell-depleted mice have less inflammation and IR than obese WT mice (8). Interestingly, T-cell cytokine production is decreased in obese B cell-null mouse adipose tissue (AT) (8), which raises the possibility that, in addition to production of a proinflammatory cytokine profile, B cells may function in IR by regulating the T cell-mediated inflammation known to drive disease pathogenesis (9, 10). We identified a proinflammatory T-cell ratio [defined by increased Th17 cells plus decreased regulatory T cells (Tregs)] in T2D patients that mirror...

IL-10 plays a central role in restraining the vigor of inflammatory responses, but the critical cellular sources of this counter-regulatory cytokine remain speculative in many disease models. Using a novel IL-10 transcriptional reporter mouse, we found an unexpected predominance of B cells (including plasma cells) among IL-10-expressing cells in peripheral lymphoid tissues at baseline and during diverse models of in vivo immunological challenge. Use of a novel B cell-specific IL-10 knockout mouse revealed that B cell-derived IL-10 nonredundantly decreases virus-specific CD8+ T cell responses and plasma cell expansion during murine cytomegalovirus infection and modestly restrains immune activation after challenge with foreign Abs to IgD. In contrast, no role for B cell-derived IL-10 was evident during endotoxemia; however, although B cells dominated lymphoid tissue IL-10 production in this model, myeloid cells were dominant in blood and liver. These data suggest that B cells are an underappreciated source of counter-regulatory IL-10 production in lymphoid tissues, provide a clear rationale for testing the biological role of B cell-derived IL-10 in infectious and inflammatory disease, and underscore the utility of cell type-specific knockouts for mechanistic limning of immune counter-regulation.

ECM stiffness enhances chondrocyte differentiation by priming cells for a potent response to TGFβ. ECM stiffness modifies the TGFβ pathway at multiple levels, including stiffness-sensitive induction of TGFβ1 expression, Smad3 phosphorylation, and synergistic activation of chondrocyte differentiation, by combining TGFβ and an inductive ECM stiffness.

Recent data reveal an important role for B cells in the pathogenesis of chronic GVHD (cGVHD).