DOCK8 deficiency has been shown to affect the migration, function, and survival of immune cells in innate and adaptive immune responses. The immunological mechanisms underlying autosomal recessive (AR) hyper-IgE syndrome (AR-HIES) caused by DOCK8 mutations remain unclear, leading to a lack of specific therapeutic options. In this study, we used CRISPR/Cas9 technology to develop a mouse model with a specific DOCK8 point mutation in exon 45 (c.5846C>A), which is observed in patients with AR-HIES. We then investigated the effect of this mutation on B cell development, cell metabolism, and function in a mouse model with Dock8 gene mutation. The results demonstrated that Dock8 gene mutation inhibited splenic MZ and GC B cell development and crippled BCR signaling. In addition, it resulted in enhanced glycolysis in B cells. Mechanistically, the reduced BCR signaling was related to decreased B cell spreading, BCR clustering, and signalosomes, mediated by inhibited activation of WASP. Furthermore, the DOCK8 mutation led to increased expression of c-Myc in B cells, which plays an important role in glycolysis. As such, GC B cells' formation and immune responses were disturbed in LCMV-infected mice. These findings will provide new insights into the immunological pathogenesis of primary immunodeficiency disorder caused by DOCK8 mutation.
© 2024. The Author(s).

Since the description of age-associated or autoimmune-associated B cells (ABCs), there has been a growing interest in the role of these cells in autoimmunity. ABCs are differently defined depending on the research group and are heterogenous subsets. Here, we sought to characterize ABCs in Sle1/2/3 triple congenic (TC) mice, which is a well accepted mouse model of lupus. Compared to follicular (FO) B cells, ABCs have many distinct functional properties, including antigen presentation. They express key costimulatory molecules for T cell activation and a distinct profile of cytokines. Moreover, they exhibit an increased capacity for antigen uptake. ABCs were also compared with germinal center (GC) B cells, which are antigen activated B cell population. There are several phenotypic similarities between ABCs and GC B cells, but GC B cells do not produce proinflammatory cytokines or take up antigen. While T cell proliferation and activation is induced by both FO B and ABCs in an antigen-dependent manner, ABCs induce stronger T cell receptor signaling in naïve CD4+ T cells and preferentially induce differentiation of T follicular helper (Tfh) cells. We found that ABCs exhibit a distinct transcriptomic profile which is focused on metabolism, cytokine signaling and antigen uptake and processing. ABCs exhibit an increase in both glycolysis and oxidative phosphorylation compared to FO B cells. Treatment of ABCs with metformin suppresses antigen presentation by decreasing antigen uptake, resulting in decreased Tfh differentiation. Taken together, these findings define a fundamental connection between metabolism and function within ABCs.
Copyright © 2023 Ramirez De Oleo, Kim, Atisha-Fregoso, Shih, Lee, Diamond and Kim.

Germline CARD11 gain-of-function (GOF) mutations cause B cell Expansion with NF-κB and T cell Anergy (BENTA) disease, whilst somatic GOF CARD11 mutations recur in diffuse large B cell lymphoma (DLBCL) and in up to 30% of the peripheral T cell lymphomas (PTCL) adult T cell leukemia/lymphoma (ATL), cutaneous T cell lymphoma (CTCL) and Sezary Syndrome. Despite their frequent acquisition by PTCL, the T cell-intrinsic effects of CARD11 GOF mutations are poorly understood.
Here, we studied B and T lymphocytes in mice with a germline Nethyl-N-nitrosourea (ENU)-induced Card11M365K mutation identical to a mutation identified in DLBCL and modifying a conserved region of the CARD11 coiled-coil domain recurrently mutated in DLBCL and PTCL.
Our results demonstrate that CARD11.M365K is a GOF protein that increases B and T lymphocyte activation and proliferation following antigen receptor stimulation. Germline Card11M365K mutation was insufficient alone to cause B or T-lymphoma, but increased accumulation of germinal center (GC) B cells in unimmunized and immunized mice. Card11M365K mutation caused cell-intrinsic over-accumulation of activated T cells, T regulatory (TREG), T follicular (TFH) and T follicular regulatory (TFR) cells expressing increased levels of ICOS, CTLA-4 and PD-1 checkpoint molecules. Our results reveal CARD11 as an important, cell-autonomous positive regulator of TFH, TREG and TFR cells. They highlight T cell-intrinsic effects of a GOF mutation in the CARD11 gene, which is recurrently mutated in T cell malignancies that are often aggressive and associated with variable clinical outcomes.
Copyright © 2023 Masle-Farquhar, Jeelall, White, Bier, Deenick, Brink, Horikawa and Goodnow.

Follicular T cells including T follicular helper (TFH) and T follicular regulatory (TFR) cells are essential in supporting and regulating the quality of antibody responses that develop in the germinal centre (GC). Follicular T cell migration during the propagation of antibody responses is largely attributed to the chemokine receptor CXCR5, however CXCR5 is reportedly redundant in migratory events prior to formation of the GC, and CXCR5-deficient TFH and TFR cells are still capable of localizing to GCs. Here we comprehensively assess chemokine receptor expression by follicular T cells during a model humoral immune response in the spleen. In addition to the known follicular T cell chemokine receptors Cxcr5 and Cxcr4, we show that follicular T cells express high levels of Ccr6, Ccr2 and Cxcr3 transcripts and we identify functional expression of CCR6 protein by both TFH and TFR cells. Notably, a greater proportion of TFR cells expressed CCR6 compared to TFH cells and gating on CCR6+CXCR5hiPD-1hi T cells strongly enriched for TFR cells. Examination of Ccr6-/- mice revealed that CCR6 is not essential for development of the GC response in the spleen, and mixed bone marrow chimera experiments found no evidence for an intrinsic requirement for CCR6 in TFR cell development or localisation during splenic humoral responses. These findings point towards multiple functionally redundant chemotactic signals regulating T cell localisation in the GC.
Copyright © 2022 Bastow, Kara, Tyllis, Vinuesa, McColl and Comerford.

The poor immunogenicity of solid tumors limits the efficacy ofanti-programmed cell death protein 1 (anti-PD1)-based immune checkpoint blockade (ICB); thus, less than 30% of patients with cancer exhibit a response. Currently, there is still a lack of effective strategies for improving tumor immunogenicity.
The antitumor effect of ultrasound-stimulated nanobubbles (USNBs) alone and in combination with an anti-PD1 antibody was evaluated in RM1 (prostate cancer), MC38 (colon cancer) and B16 (melanoma) xenograft mouse models. The phenotypes of antigen-presenting cells and CD8+ T cells were evaluated by flow cytometry. Damage-associated molecular pattern (DAMP) release, antigen release and tumor cell necrosis were assessed via western blot, flow cytometry, transmission electron microscopy and confocal microscopy.
USNB promoted the infiltration and antitumor activity of CD8+ T cells. The combination of USNB and anti-PD1 blockade improved systemic antitumor immunity and resulted in an abscopal effect and long-term immune memory protection after complete tumor remission. Mechanistically, tumor-targeting USNB induced tumor cell necrosis through an ultrasound-mediated cavitation effect, which significantly increased DAMP release and tumor antigen presentation, consequently sensitizing tumors to ICB treatment.
The administration of USNB increased tumor immunogenicity by remodeling the tumor-immune microenvironment, providing a promising strategy for sensitizing poorly immunogenic solid tumors to immunotherapy in the clinic.
© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.