Tox2 is required for the maintenance of GC TFH cells and the generation of memory TFH cells

Transcription factor Tox2 is required for metabolic adaptation and tissue residency of ILC3 in the gut

Group 3 innate lymphoid cells (ILC3) are the major subset of gut-resident ILC with essential roles in infections and tissue repair, but how they adapt to the gut environment to maintain tissue residency is unclear. We report that Tox2 is critical for gut ILC3 maintenance and function. Gut ILC3 highly expressed Tox2, and depletion of Tox2 markedly decreased ILC3 in gut but not at central sites, resulting in defective control of Citrobacter rodentium infection. Single-cell transcriptional profiling revealed decreased expression of Hexokinase-2 in Tox2-deficient gut ILC3. Consistent with the requirement for hexokinases in glycolysis, Tox2-/- ILC3 displayed decreased ability to utilize glycolysis for protein translation. Ectopic expression of Hexokinase-2 rescued Tox2-/- gut ILC3 defects. Hypoxia and interleukin (IL)-17A each induced Tox2 expression in ILC3, suggesting a mechanism by which ILC3 adjusts to fluctuating environments by programming glycolytic metabolism. Our results reveal the requirement for Tox2 to support the metabolic adaptation of ILC3 within the gastrointestinal tract.

Help me help you: emerging concepts in T follicular helper cell differentiation, identity, and function

Effective high-affinity, long-term humoral immunity requires T cell help provided by a subset of differentiated CD4+ T cells known as T follicular helper (Tfh) cells. Classically, Tfh cells provide contact-dependent help for the generation of germinal centers (GCs) in secondary lymphoid organs (SLOs). Recent studies have expanded the conventional definition of Tfh cells, revealing new functions, new descriptions of Tfh subsets, new factors regulating Tfh differentiation, and new roles outside of SLO GCs. Together, these data suggest that one Tfh is not equivalent to another, helping redefine our understanding of Tfh cells and their biology.

Ex Pluribus Unum: The CD4 T Cell Response against Influenza A Virus

Current Influenza A virus (IAV) vaccines, which primarily aim to generate neutralizing antibodies against the major surface proteins of specific IAV strains predicted to circulate during the annual 'flu' season, are suboptimal and are characterized by relatively low annual vaccine efficacy. One approach to improve protection is for vaccines to also target the priming of virus-specific T cells that can protect against IAV even in the absence of preexisting neutralizing antibodies. CD4 T cells represent a particularly attractive target as they help to promote responses by other innate and adaptive lymphocyte populations and can also directly mediate potent effector functions. Studies in murine models of IAV infection have been instrumental in moving this goal forward. Here, we will review these findings, focusing on distinct subsets of CD4 T cell effectors that have been shown to impact outcomes. This body of work suggests that a major challenge for next-generation vaccines will be to prime a CD4 T cell population with the same spectrum of functional diversity generated by IAV infection. This goal is encapsulated well by the motto 'ex pluribus unum': that an optimal CD4 T cell response comprises many individual specialized subsets responding together.

Distinct transcriptomes and autocrine cytokines underpin maturation and survival of antibody-secreting cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple autoantibody types, some of which are produced by long-lived plasma cells (LLPC). Active SLE generates increased circulating antibody-secreting cells (ASC). Here, we examine the phenotypic, molecular, structural, and functional features of ASC in SLE. Relative to post-vaccination ASC in healthy controls, circulating blood ASC from patients with active SLE are enriched with newly generated mature CD19-CD138+ ASC, similar to bone marrow LLPC. ASC from patients with SLE displayed morphological features of premature maturation and a transcriptome epigenetically initiated in SLE B cells. ASC from patients with SLE exhibited elevated protein levels of CXCR4, CXCR3 and CD138, along with molecular programs that promote survival. Furthermore, they demonstrate autocrine production of APRIL and IL-10, which contributed to their prolonged in vitro survival. Our work provides insight into the mechanisms of generation, expansion, maturation and survival of SLE ASC.

Bob1 maintains T follicular helper cells for long-term humoral immunity

Humoral immunity is vital for host protection, yet aberrant antibody responses can trigger harmful inflammation and immune-related disorders. T follicular helper (Tfh) cells, central to humoral immunity, have garnered significant attention for unraveling immune mechanisms. This study shows the role of B-cell Oct-binding protein 1 (Bob1), a transcriptional coactivator, in Tfh cell regulation. Our investigation, utilizing conditional Bob1-deficient mice, suggests that Bob1 plays a critical role in modulating inducible T-cell costimulator expression and cellular respiration in Tfh cells. This regulation maintains the long-term functionality of Tfh cells, enabling their reactivation from central memory T cells to produce antibodies during recall responses. In a bronchial asthma model induced by house dust mite (HDM) inhalation, Bob1 is observed to enhance HDM-specific antibodies, including IgE, highlighting its pivotal function in Tfh cell regulation. Further exploration of Bob1-dependent mechanisms in Tfh cells holds promise for governing protective immunity and addressing immune-related disorders.

TGFβ prevents IgE-mediated allergic disease by restraining T follicular helper 2 differentiation

Allergic diseases are common, affecting more than 20% of the population. Genetic variants in the TGFβ pathway are strongly associated with atopy. To interrogate the mechanisms underlying this association, we examined patients and mice with Loeys-Dietz syndrome (LDS) who harbor missense mutations in the kinase domain of TGFΒR1/2. We demonstrate that LDS mutations lead to reduced TGFβ signaling and elevated total and allergen-specific IgE, despite the presence of wild-type T regulatory cells in a chimera model. Germinal center activity was enhanced in LDS and characterized by a selective increase in type 2 follicular helper T cells (TFH2). Expression of Pik3cg was increased in LDS TFH cells and associated with reduced levels of the transcriptional repressor SnoN. PI3Kγ/mTOR signaling in LDS naïve CD4+ T cells was elevated after T cell receptor cross-linking, and pharmacologic inhibition of PI3Kγ or mTOR prevented exaggerated TFH2 and antigen-specific IgE responses after oral antigen exposure in an adoptive transfer model. Naïve CD4+ T cells from nonsyndromic allergic individuals also displayed decreased TGFβ signaling, suggesting that our mechanistic discoveries may be broadly relevant to allergic patients in general. Thus, TGFβ plays a conserved, T cell-intrinsic, and nonredundant role in restraining TFH2 development via the PI3Kγ/mTOR pathway and thereby protects against allergic disease.

Tox induces T cell IL-10 production in a BATF-dependent manner

Tox is a member of the high mobility group (HMG)-Box transcription factors and plays important roles in thymic T cell development. Outside of the thymus, however, Tox is also highly expressed by CD8 and CD4 T cells in various states of activation and in settings of cancer and autoimmune disease. In CD4 T cells, Tox has been primarily studied in T follicular helper (TFH) cells where it, along with Tox2, promotes TFH differentiation by regulating key TFH-associated genes and suppressing CD4 cytotoxic T cell differentiation. However, the role of Tox in other T helper (Th) cell subtypes is less clear. Here, we show that Tox is expressed in several physiologically-activated Th subtypes and its ectopic expression enhances the in vitro differentiation of Th2 and T regulatory (Treg) cells. Tox overexpression in unpolarized Th cells also induced the expression of several genes involved in cell activation (Pdcd1), cellular trafficking (Ccl3, Ccl4, Xcl1) and suppressing inflammation (Il10) across multiple Th subtypes. We found that Tox binds the regulatory regions of these genes along with the transcription factors BATF, IRF4, and JunB and that Tox-induced expression of IL-10, but not PD-1, is BATF-dependent. Based on these data, we propose a model where Tox regulates Th cell chemotactic genes involved in facilitating dendritic cell-T cell interactions and aids in the resolution or prevention of inflammation through the production of IL-10.

T follicular helper cells and T peripheral helper cells in rheumatic and musculoskeletal diseases

Recent technological progress has greatly advanced our understanding of human immunology. In particular, the discovery of human T follicular helper (Tfh) and T peripheral helper (Tph) cells has significantly advanced our understanding of human adaptive immune system. Tfh and Tph cells share similar molecular characteristics and both play critical roles in B cell differentiation and maturation. However, they differ in their functional properties, such as chemokine receptor expression and cytokine production. As a result, Tfh cells are mainly involved in B cell differentiation and maturation in germinal centres of secondary lymphoid tissues, while Tph cells are involved in B cell differentiation and tissue damage in peripheral inflammatory lesions. Importantly, the involvement of Tfh and Tph cells in the pathogenesis of rheumatic and musculoskeletal diseases has become clear. In rheumatoid arthritis and systemic lupus erythematosus, Tph cell infiltration is predominant in peripheral inflammatory lesions, whereas Tfh cell infiltration is predominant in the affected lesions of IgG4-related disease. Therefore, the contribution of Tfh and Tph cells to the development of rheumatic and musculoskeletal diseases varies depending on each disease. In this review, we provide an overview of human Tfh and Tph cells and summarise the latest findings on these novel T cell subsets in various rheumatic and musculoskeletal diseases.

Designing Selenium Nanoadjuvant as Universal Agent for Live-Killed Virus-Based Vaccine

Inactivated virus vaccines with whole antigen spectra and good safety are the commonly used modality for preventing infections. However, the poor immunogenicity greatly limits its clinical applications. Herein, by taking advantages of the crucial roles of Se in the functions of immune cells and its biomineralization property, it successfully in-situ synthesized Se nanoadjuvant on inactivated viruses such as porcine epidemic diarrhea virus (PEDV), pseudorabies virus (PRV), and porcine reproductive and respiratory syndrome virus (PRRSV) in a facile method, which is universal to construct other inactivated virus vaccines. The nanovaccine can highly effectively enhance the uptake of PEDV/PRV/PRRSV into dendritic cells (DCs) and activate DCs via triggering TLR4 signaling pathways and regulating selenoproteins expressions. Furthermore, it exhibited better activities in triggering macrophages and natural killer cells-mediated innate immunity and T cells-mediated cellular immunity compared to PEDV and the commercial inactivated PEDV vaccine on both mice and swine models. This study provides a universal Se nanoadjuvant for developing inactivated viruses-based nanovaccines for preventing virus infections.

Immune landscape of tertiary lymphoid structures in hepatocellular carcinoma (HCC) treated with neoadjuvant immune checkpoint blockade

Neoadjuvant immunotherapy is thought to produce long-term remissions through induction of antitumor immune responses before removal of the primary tumor. Tertiary lymphoid structures (TLS), germinal center-like structures that can arise within tumors, may contribute to the establishment of immunological memory in this setting, but understanding of their role remains limited. Here, we investigated the contribution of TLS to antitumor immunity in hepatocellular carcinoma (HCC) treated with neoadjuvant immunotherapy. We found that neoadjuvant immunotherapy induced the formation of TLS, which were associated with superior pathologic response, improved relapse free survival, and expansion of the intratumoral T and B cell repertoire. While TLS in viable tumor displayed a highly active mature morphology, in areas of tumor regression we identified an involuted TLS morphology, which was characterized by dispersion of the B cell follicle and persistence of a T cell zone enriched for ongoing antigen presentation and T cell-mature dendritic cell interactions. Involuted TLS showed increased expression of T cell memory markers and expansion of CD8+ cytotoxic and tissue resident memory clonotypes. Collectively, these data reveal the circumstances of TLS dissolution and suggest a functional role for late-stage TLS as sites of T cell memory formation after elimination of viable tumor.

Tertiary lymphoid structures correlate with enhancement of antitumor immunity in esophageal squamous cell carcinoma

BACKGROUND

Tertiary lymphoid structures (TLSs) are associated with a favorable prognosis in several cancers. However, the correlation between TLSs and outcomes of esophageal squamous cell carcinoma (ESCC) and the impact of TLSs on the tumor immune microenvironment (TIME) remain unknown.

METHODS

We pathologically evaluated the significance of TLSs in ESCC focusing on TLS maturation using 180 ESCC specimens and performed single-cell RNA sequencing (scRNA-seq) using 14 ESCC tissues to investigate functional differences of immune cells according to TLS presence.

RESULTS

TLS+ cases had better recurrence-free-survival (RFS) (p < 0.0001) and overall survival (OS) (p = 0.0016) compared with TLS- cases. Additionally, mature TLS+ cases had better RFS and OS compared with immature TLS+ cases (p = 0.019 and p = 0.015) and TLS- cases (p < 0.0001 and p = 0.0002). The scRNA-seq showed that CD8+ T cells in TLS+ tumors expressed high levels of cytotoxic signatures and antigen-presentation of dendritic cells (DCs) was enhanced in TLS+ tumors. Immunohistochemistry showed that the densities of tumor-infiltrating CD8+ T cells and DCs were significantly higher in TLS+ tumors than those in TLS- tumors.

CONCLUSIONS

These data suggest the prognostic and functional significance of TLSs in ESCC and provides new insights into TLSs on the TIME.

Stem-like CD4+ T cells in perivascular tertiary lymphoid structures sustain autoimmune vasculitis

Autoimmune vasculitis of the medium and large elastic arteries can cause blindness, stroke, aortic arch syndrome, and aortic aneurysm. The disease is often refractory to immunosuppressive therapy and progresses over decades as smoldering aortitis. How the granulomatous infiltrates in the vessel wall are maintained and how tissue-infiltrating T cells and macrophages are replenished are unknown. Single-cell and whole-tissue transcriptomic studies of immune cell populations in vasculitic arteries identified a CD4+ T cell population with stem cell-like features. CD4+ T cells supplying the tissue-infiltrating and tissue-damaging effector T cells survived in tertiary lymphoid structures around adventitial vasa vasora, expressed the transcription factor T cell factor 1 (TCF1), had high proliferative potential, and gave rise to two effector populations, Eomesodermin (EOMES)+ cytotoxic T cells and B cell lymphoma 6 (BCL6)+ T follicular helper-like cells. TCF1hiCD4+ T cells expressing the interleukin 7 receptor (IL-7R) sustained vasculitis in serial transplantation experiments. Thus, TCF1hiCD4+ T cells function as disease stem cells and promote chronicity and autonomy of autoimmune tissue inflammation. Remission-inducing therapies will require targeting stem-like CD4+ T cells instead of only effector T cells.

SLE Antibody-Secreting Cells Are Characterized by Enhanced Peripheral Maturation and Survival Programs

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by multiple autoantibodies, some of which are present in high titers in a sustained, B cell-independent fashion consistent with their generation from long-lived plasma cells (LLPC). Active SLE displays high numbers of circulating antibody-secreting cells (ASC). Understanding the mechanisms of generation and survival of SLE ASC would contribute important insight into disease pathogenesis and novel targeted therapies. We studied the properties of SLE ASC through a systematic analysis of their phenotypic, molecular, structural, and functional features. Our results indicate that in active SLE, relative to healthy post-immunization responses, blood ASC contain a much larger fraction of newly generated mature CD19- CD138+ ASC similar to bone marrow (BM) LLPC. SLE ASC were characterized by morphological and structural features of premature maturation. Additionally, SLE ASC express high levels of CXCR4 and CD138, and molecular programs consistent with increased longevity based on pro-survival and attenuated pro-apoptotic pathways. Notably, SLE ASC demonstrate autocrine production of APRIL and IL-10 and experience prolonged in vitro survival. Combined, our findings indicate that SLE ASC are endowed with enhanced peripheral maturation, survival and BM homing potential suggesting that these features likely underlie BM expansion of autoreactive PC.

Spatiotemporal resolution of germinal center Tfh cell differentiation and divergence from central memory CD4+ T cell fate

Follicular helper T (Tfh) cells are essential for germinal center (GC) B cell responses. However, it is not clear which PD-1+CXCR5+Bcl6+CD4+ T cells will differentiate into PD-1hiCXCR5hiBcl6hi GC-Tfh cells and how GC-Tfh cell differentiation is regulated. Here, we report that the sustained Tigit expression in PD-1+CXCR5+CD4+ T cells marks the precursor Tfh (pre-Tfh) to GC-Tfh transition, whereas Tigit-PD-1+CXCR5+CD4+ T cells upregulate IL-7Rα to become CXCR5+CD4+ T memory cells with or without CCR7. We demonstrate that pre-Tfh cells undergo substantial further differentiation at the transcriptome and chromatin accessibility levels to become GC-Tfh cells. The transcription factor c-Maf appears critical in governing the pre-Tfh to GC-Tfh transition, and we identify Plekho1 as a stage-specific downstream factor regulating the GC-Tfh competitive fitness. In summary, our work identifies an important marker and regulatory mechanism of PD-1+CXCR5+CD4+ T cells during their developmental choice between memory T cell fate and GC-Tfh cell differentiation.