T-bet and eomesodermin play critical roles in directing T cell differentiation to Th1 versus Th17

Eomesodermin spatiotemporally orchestrates the early and late stages of NK cell development by targeting KLF2 and T-bet, respectively

Eomesodermin (Eomes) is a critical factor in the development of natural killer (NK) cells, but its precise role in temporal and spatial coordination during this process remains unclear. Our study revealed that Eomes plays distinct roles during the early and late stages of NK cell development. Specifically, the early deletion of Eomes via the CD122-Cre transgene resulted in significant blockade at the progenitor stage due to the downregulation of KLF2, another important transcription factor. ChIP-seq revealed direct binding of Eomes to the conserved noncoding sequence (CNS) of Klf2. Utilizing the CHimeric IMmune Editing (CHIME) technique, we found that deletion of the CNS region of Klf2 via CRISPRi led to a reduction in the NK cell population and developmental arrest. Moreover, constitutive activation of this specific CNS region through CRISPRa significantly reversed the severe defects in NK cell development caused by Eomes deficiency. Conversely, Ncr1-Cre-mediated terminal deletion of Eomes expedited the transition of NK cell subsets from the CD27+CD11b+ phenotype to the CD27-CD11b+ phenotype. Late-stage deficiency of Eomes led to a significant increase in T-bet expression, which subsequently increased the expression of the transcription factor Zeb2. Genetic deletion of one allele of Tbx21, encoding T-bet, effectively reversed the aberrant differentiation of Eomes-deficient NK cells. In summary, we utilized two innovative genetic models to elucidate the intricate mechanisms underlying Eomes-mediated NK cell commitment and differentiation.

Eomes-dependent mitochondrial regulation promotes survival of pathogenic CD4+ T cells during inflammation

The mechanisms whereby Eomes controls tissue accumulation of T cells and strengthens inflammation remain ill-defined. Here, we show that Eomes deletion in antigen-specific CD4+ T cells is sufficient to protect against central nervous system (CNS) inflammation. While Eomes is dispensable for the initial priming of CD4+ T cells, it is required for long-term maintenance of CNS-infiltrating CD4+ T cells. We reveal that the impact of Eomes on effector CD4+ T cell longevity is associated with sustained expression of multiple genes involved in mitochondrial organization and functions. Accordingly, epigenetic studies demonstrate that Eomes supports mitochondrial function by direct binding to either metabolism-associated genes or mitochondrial transcriptional modulators. Besides, the significance of these findings was confirmed in CD4+ T cells from healthy donors and multiple sclerosis patients. Together, our data reveal a new mechanism by which Eomes promotes severity and chronicity of inflammation via the enhancement of CD4+ T cell mitochondrial functions and resistance to stress-induced cell death.

Curcumin alleviated dextran sulfate sodium-induced colitis by recovering memory Th/Tfh subset balance

BACKGROUND

Restoration of immune homeostasis by targeting the balance between memory T helper (mTh) cells and memory follicular T helper (mTfh) cells is a potential therapeutic strategy against ulcerative colitis (UC). Because of its anti-inflammatory and immunomodulatory properties, curcumin (Cur) is a promising drug for UC treatment. However, fewer studies have demonstrated whether Cur can modulate the mTh/mTfh subset balance in mice with colitis.

AIM

To explore the potential mechanism underlying Cur-mediated alleviation of colitis induced by dextran sulfate sodium (DSS) in mice by regulating the mTh and mTfh immune homeostasis.

METHODS

Balb/c mice were administered 3% and 2% DSS to establish the UC model and treated with Cur (200 mg/kg/d) by gavage on days 11-17. On the 18th d, all mice were anesthetized and euthanized, and the colonic length, colonic weight, and colonic weight index were evaluated. Histomorphological changes in the mouse colon were observed through hematoxylin-eosin staining. Levels of Th/mTh and Tfh/mTfh cell subsets in the spleen were detected through flow cytometry. Western blotting was performed to detect SOCS-1, SOCS-3, STAT3, p-STAT3, JAK1, p-JAK1, and NF-κB p65 protein expression levels in colon tissues.

RESULTS

Cur effectively mitigates DSS-induced colitis, facilitates the restoration of mouse weight and colonic length, and diminishes the colonic weight and colonic weight index. Simultaneously, it hinders ulcer development and inflammatory cell infiltration in the colonic mucous membrane. While the percentage of Th1, mTh1, Th7, mTh7, Th17, mTh17, Tfh1, mTfh1, Tfh7, mTfh7, Tfh17, and mTfh17 cells decreased after Cur treatment of the mice for 7 d, and the frequency of mTh10, Th10, mTfh10, and Tfh10 cells in the mouse spleen increased. Further studies revealed that Cur administration prominently decreased the SOCS-1, SOCS-3, STAT3, p-STAT3, JAK1, p-JAK1, and NF-κB p65 protein expression levels in the colon tissue.

CONCLUSION

Cur regulated the mTh/mTfh cell homeostasis to reduce DSS-induced colonic pathological damage, potentially by suppressing the JAK1/STAT3/SOCS signaling pathway.

A three-stage developmental pathway for human Vγ9Vδ2 T cells within the postnatal thymus

Vγ9Vδ2 T cells are the largest population of γδ T cells in adults and can play important roles in providing effective immunity against cancer and infection. Many studies have suggested that peripheral Vγ9Vδ2 T cells are derived from the fetal liver and thymus and that the postnatal thymus plays little role in the development of these cells. More recent evidence suggested that these cells may also develop postnatally in the thymus. Here, we used high-dimensional flow cytometry, transcriptomic analysis, functional assays, and precursor-product experiments to define the development pathway of Vγ9Vδ2 T cells in the postnatal thymus. We identify three distinct stages of development for Vγ9Vδ2 T cells in the postnatal thymus that are defined by the progressive acquisition of functional potential and major changes in the expression of transcription factors, chemokines, and other surface markers. Furthermore, our analysis of donor-matched thymus and blood revealed that the molecular requirements for the development of functional Vγ9Vδ2 T cells are delivered predominantly by the postnatal thymus and not in the periphery. Tbet and Eomes, which are required for IFN-γ and TNFα expression, are up-regulated as Vγ9Vδ2 T cells mature in the thymus, and mature thymic Vγ9Vδ2 T cells rapidly express high levels of these cytokines after stimulation. Similarly, the postnatal thymus programs Vγ9Vδ2 T cells to express the cytolytic molecules, perforin, granzyme A, and granzyme K. This study provides a greater understanding of how Vγ9Vδ2 T cells develop in humans and may lead to opportunities to manipulate these cells to treat human diseases.

IKK2/NFkB signaling controls lung resident CD8+ T cell memory during influenza infection

CD8⁺ T cell tissue resident memory (T_RM) cells are especially suited to control pathogen spread at mucosal sites. However, their maintenance in lung is short-lived. TCR-dependent NFkB signaling is crucial for T cell memory but how and when NFkB signaling modulates tissue resident and circulating T cell memory during the immune response is unknown. Here, we find that enhancing NFkB signaling in T cells once memory to influenza is established, increases pro-survival Bcl-2 and CD122 levels thus boosting lung CD8⁺ T_RM maintenance. By contrast, enhancing NFkB signals during the contraction phase of the response leads to a defect in CD8⁺ T_RM differentiation without impairing recirculating memory subsets. Specifically, inducible activation of NFkB via constitutive active IKK2 or TNF interferes with TGFβ signaling, resulting in defects of lung CD8⁺ T_RM imprinting molecules CD69, CD103, Runx3 and Eomes. Conversely, inhibiting NFkB signals not only recovers but improves the transcriptional signature and generation of lung CD8⁺ T_RM. Thus, NFkB signaling is a critical regulator of tissue resident memory, whose levels can be tuned at specific times during infection to boost lung CD8⁺ T_RM.

T-BET and EOMES sustain mature human NK cell identity and antitumor function

Since the T-box transcription factors (TFs) T-BET and EOMES are necessary for initiation of NK cell development, their ongoing requirement for mature NK cell homeostasis, function, and molecular programming remains unclear. To address this, T-BET and EOMES were deleted in unexpanded primary human NK cells using CRISPR/Cas9. Deleting these TFs compromised in vivo antitumor response of human NK cells. Mechanistically, T-BET and EOMES were required for normal NK cell proliferation and persistence in vivo. NK cells lacking T-BET and EOMES also exhibited defective responses to cytokine stimulation. Single-cell RNA-Seq revealed a specific T-box transcriptional program in human NK cells, which was rapidly lost following T-BET and EOMES deletion. Further, T-BET- and EOMES-deleted CD56bright NK cells acquired an innate lymphoid cell precursor-like (ILCP-like) profile with increased expression of the ILC-3-associated TFs RORC and AHR, revealing a role for T-box TFs in maintaining mature NK cell phenotypes and an unexpected role of suppressing alternative ILC lineages. Our study reveals the critical importance of sustained EOMES and T-BET expression to orchestrate mature NK cell function and identity.

Human CCR6+ Th Cells Show Both an Extended Stable Gradient of Th17 Activity and Imprinted Plasticity

Th17 cells have been investigated in mice primarily for their contributions to autoimmune diseases. However, the pathways of differentiation of Th17 and related Th cells (type 17 cells) and the structure of the type 17 memory population in humans are not well understood; such understanding is critical for manipulating these cells in vivo. By exploiting differences in levels of surface CCR6, we found that human type 17 memory cells, including individual T cell clonotypes, form an elongated continuum of type 17 character along which cells can be driven by increasing RORγt. This continuum includes cells preserved within the memory pool with potentials that reflect the early preferential activation of multiple over single lineages. The phenotypes and epigenomes of CCR6+ cells are stable across cell divisions under noninflammatory conditions. Nonetheless, activation in polarizing and nonpolarizing conditions can yield additional functionalities, revealing, respectively, both environmentally induced and imprinted mechanisms that contribute differentially across the type 17 continuum to yield the unusual plasticity ascribed to type 17 cells.

Staphylococcus aureus-derived factors promote human Th9 cell polarization and enhance a transcriptional program associated with allergic inflammation

T helper (Th) 9 cells, characterized by robust secretion of IL-9, have been increasingly associated with allergic diseases. However, whether and how Th9 cells are modulated by environmental stimuli remains poorly understood. In this study, we show that in vitro exposure of human PBMCs or isolated CD4 T-cells to Staphylococcus (S.) aureus-derived factors, including its toxins, potently enhances Th9 cell frequency and IL-9 secretion. Furthermore, as revealed by RNA sequencing analysis, S. aureus increases the expression of Th9-promoting factors at the transcriptional level, such as FOXO1, miR-155, and TNFRSF4. The addition of retinoic acid (RA) dampens the Th9 responses promoted by S. aureus and substantially changes the transcriptional program induced by this bacterium, while also altering the expression of genes associated with allergic inflammation. Together, our results demonstrate a strong influence of microbial and dietary factors on Th9 cell polarization, which may be important in the context of allergy development and treatment.

Comparison of dynamic changes in the peripheral CD8+ T cells function and differentiation in ESCC patients treated with radiotherapy combined with anti-PD-1 antibody or concurrent chemoradiotherapy

Objective

The systematic immune status of cancer patients undergoing immunotherapy is little known. We prospectively identified the function and differentiation traits of peripheral CD8⁺ T cells based on our phase 1b clinical trial (NCT03222440) of radiotherapy combined with camrelizumab in patients with locally advanced esophageal squamous cell carcinoma (ESCC) and compared it with concurrent chemoradiotherapy (CCRT).

Methods

19 and 18 patients were included in the cohort of radiotherapy plus camrelizumab and cohort of CCRT treatment. By using flow cytometry, we evaluated the expression levels of PD-1, Eomes, T-bet and IFN-γ (function), CD38 and HLA-DR (activation), and differentiation subsets classified according to the expression levels of CD45RA and CD62L in peripheral CD8⁺ T cells before and during treatment.

Results

Effective binding of anti-PD-1 antibody camrelizumab with PD-1 on CD8⁺ T cells was detected during treatment. Both two treatments elevated the expression levels of activation molecules CD38 and HLA-DR on CD8⁺ T cells. PD-1⁺CD8⁺ T cells had more activation features than PD-1^-CD8⁺ T cells in two groups and the treatments did not alter these differences. The two treatments activated both PD-1⁺ and PD-1^- CD8⁺ T cells. PD-1⁺CD8⁺ T cells had less Naïve and TEMRA but more Tcm and Tem than PD-1^-CD8⁺ T cells in two groups and both two treatments changed the ratio of memory T cells in PD-1⁺ and PD-1^- cells. RT plus camrelizumab treatment reduced Naïve T cells and TEMRA subsets both in PD-1⁺ and PD-1^- CD8⁺ T cells while elevated Tcm subset in PD-1⁺CD8⁺ T cells and Tem subset in PD-1^-CD8⁺ T cells. CCRT elevated Tcm subset and reduced TEMRA subset in PD-1^-CD8⁺ T cells while did not change any subset in PD-1⁺CD8⁺ T cells. Furthermore, patients undergoing radiotherapy plus immunotherapy were found to obtain better prognosis than those receiving CCRT.

Conclusions

This study identified the dynamic changes of systematic immune status of patients undergoing treatment. The two treatments had similar activation effects on peripheral CD8⁺ T cells with different PD-1 properties but had different effects on their differentiation status. These results provided potential clues to the reasons underlying the difference in prognosis of the two treatments.

Regulation of CD4 T Cell Responses by the Transcription Factor Eomesodermin

Central to the impacts of CD4 T cells, both positive in settings of infectious disease and cancer and negative in the settings of autoimmunity and allergy, is their ability to differentiate into distinct effector subsets with specialized functions. The programming required to support such responses is largely dictated by lineage-specifying transcription factors, often called ‘master regulators’. However, it is increasingly clear that many aspects of CD4 T cell immunobiology that can determine the outcomes of disease states involve a broader transcriptional network. Eomesodermin (Eomes) is emerging as an important member of this class of transcription factors. While best studied in CD8 T cells and NK cells, an increasing body of work has focused on impacts of Eomes expression in CD4 T cell responses in an array of different settings. Here, we focus on the varied impacts reported in these studies that, together, indicate the potential of targeting Eomes expression in CD4 T cells as a strategy to improve a variety of clinical outcomes.

Unexpected connections of the IL-23/IL-17 and IL-4/IL-13 cytokine axes in inflammatory arthritis and enthesitis

The IL-23/IL-17 cytokine axis is related to spondyloarthropathy (SpA) pattern diseases that target the skin, eye, gut and joints. These share overlapping target tissues with Th2 type or allergic diseases, including the skin, eye and gut but SpA diseases exhibit distinct microanatomical topography, molecular characteristics, and clinical features including uveitis, psoriasis, apical pulmonary involvement, lower gastrointestinal involvement with colitis, and related arthritides including psoriatic arthritis and ankylosing spondylitis. Inflammatory arthritis is conspicuously absent from the Th2 diseases which are characterised IL-4/IL-13 dependent pathway activation including allergic rhino-conjunctivitis, atopic eczema, allergic asthma and food allergies. This traditional understanding of non-overlap of musculoskeletal territory between that atopic diseases and the IL-17 -mediated SpA diseases is undergoing a critical reappraisal with the recent demonstration of IL-4/IL-13 blockade, may be associated with the development of SpA pattern arthritis, psoriasiform skin disease and occasional anterior uveitis. Given the known plasticity within Th paradigm pathways, these findings suggest dynamic Th2 cytokine and Th17 cytokine counter regulation in vivo in humans. Unexpected, this is the case in peripheral enthesis and when the IL-4/13 immunological brake on IL-23/17 cytokines is removed, a SpA phenotype may emerge. We discuss hitherto unexpected observations in SpA, showing counter regulation between the Th17 and Th2 pathways at sites including the entheses that collectively indicate that the emergent reverse translational therapeutic data is more than coincidental and offers new insights into the "Th paradigms" in atopy and SpA.

Arkadia-SKI/SnoN signaling differentially regulates TGF-β-induced iTreg and Th17 cell differentiation

TGF-β signaling is fundamental for both Th17 and regulatory T (Treg) cell differentiation. However, these cells differ in requirements for downstream signaling components, such as SMAD effectors. To further characterize mechanisms that distinguish TGF-β signaling requirements for Th17 and Treg cell differentiation, we investigated the role of Arkadia (RNF111), an E3 ubiquitin ligase that mediates TGF-β signaling during development. Inactivation of Arkadia in CD4⁺ T cells resulted in impaired Treg cell differentiation in vitro and loss of RORγt⁺FOXP3⁺ iTreg cells in the intestinal lamina propria, which increased susceptibility to microbiota-induced mucosal inflammation. In contrast, Arkadia was dispensable for Th17 cell responses. Furthermore, genetic ablation of two Arkadia substrates, the transcriptional corepressors SKI and SnoN, rescued Arkadia-deficient iTreg cell differentiation both in vitro and in vivo. These results reveal distinct TGF-β signaling modules governing Th17 and iTreg cell differentiation programs that could be targeted to selectively modulate T cell functions.

Interleukin-10 induces interferon-γ-dependent emergency myelopoiesis

In emergency myelopoiesis (EM), expansion of the myeloid progenitor compartment and increased myeloid cell production are observed and often mediated by the pro-inflammatory cytokine interferon gamma (IFN-γ). Interleukin-10 (IL-10) inhibits IFN-γ secretion, but paradoxically, its therapeutic administration to humans causes hematologic changes similar to those observed in EM. In this work, we use different in vivo systems, including a humanized immune system mouse model, to show that IL-10 triggers EM, with a significant expansion of the myeloid progenitor compartment and production of myeloid cells. Hematopoietic progenitors display a prominent IFN-γ transcriptional signature, and we show that IFN-γ mediates IL-10-driven EM. We also find that IL-10, unexpectedly, reprograms CD4 and CD8 T cells toward an activation state that includes IFN-γ production by these T cell subsets in vivo. Therefore, in addition to its established anti-inflammatory properties, IL-10 can induce IFN-γ production and EM, opening additional perspectives for the design of IL-10-based immunotherapies.

Bone Morphogenic Proteins Are Immunoregulatory Cytokines Controlling FOXP3+ Treg Cells

Bone morphogenic proteins (BMPs) are members of the transforming growth factor β (TGF-β) cytokine family promoting differentiation, homeostasis, and self-renewal of multiple tissues. We show that signaling through the bone morphogenic protein receptor 1α (BMPR1α) sustains expression of FOXP3 in T_reg cells in peripheral lymphoid tissues. BMPR1α signaling promotes molecular circuits supporting acquisition and preservation of T_reg cell phenotype and inhibiting differentiation of pro-inflammatory effector Th1/Th17 CD4⁺ T cell. Mechanistically, increased expression of KDM6B (JMJD3) histone demethylase, an antagonist of the polycomb repressive complex 2, underlies lineage-specific changes of T cell phenotypes associated with abrogation of BMPR1α signaling. These results reveal that BMPs are immunoregulatory cytokines mediating maturation and stability of peripheral FOXP3⁺ regulatory T cells (T_reg cells) and controlling generation of iT_reg cells. Thus, we establish that BMPs, a large cytokine family, are an essential link between stromal tissues and the adaptive immune system involved in sustaining tissue homeostasis by promoting immunological tolerance.

Sequential actions of EOMES and T-BET promote stepwise maturation of natural killer cells

EOMES and T-BET are related T-box transcription factors that control natural killer (NK) cell development. Here we demonstrate that EOMES and T-BET regulate largely distinct gene sets during this process. EOMES is dominantly expressed in immature NK cells and drives early lineage specification by inducing hallmark receptors and functions. By contrast, T-BET is dominant in mature NK cells, where it induces responsiveness to IL-12 and represses the cell cycle, likely through transcriptional repressors. Regardless, many genes with distinct functions are co-regulated by the two transcription factors. By generating two gene-modified mice facilitating chromatin immunoprecipitation of endogenous EOMES and T-BET, we show a strong overlap in their DNA binding targets, as well as extensive epigenetic changes during NK cell differentiation. Our data thus suggest that EOMES and T-BET may distinctly govern, via differential expression and co-factors recruitment, NK cell maturation by inserting partially overlapping epigenetic regulations.

EOMES and IL-10 regulate antitumor activity of T regulatory type 1 CD4+ T cells in chronic lymphocytic leukemia

The transcription factor eomesodermin (EOMES) promotes interleukin (IL)-10 expression in CD4+ T cells, which has been linked to immunosuppressive and cytotoxic activities. We detected cytotoxic, programmed cell death protein-1 (PD-1) and EOMES co-expressing CD4+ T cells in lymph nodes (LNs) of patients with chronic lymphocytic leukemia (CLL) or diffuse large B-cell lymphoma. Transcriptome and flow cytometry analyses revealed that EOMES does not only drive IL-10 expression, but rather controls a unique transcriptional signature in CD4+ T cells, that is enriched in genes typical for T regulatory type 1 (TR1) cells. The TR1 cell identity of these CD4+ T cells was supported by their expression of interferon gamma and IL-10, as well as inhibitory receptors including PD-1. TR1 cells with cytotoxic capacity accumulate also in Eµ-TCL1 mice that develop CLL-like disease. Whereas wild-type CD4+ T cells control TCL1 leukemia development after adoptive transfer in leukopenic Rag2-/- mice, EOMES-deficient CD4+ T cells failed to do so. We further show that TR1 cell-mediated control of TCL1 leukemia requires IL-10 receptor (IL-10R) signaling, as Il10rb-deficient CD4+ T cells showed impaired antileukemia activity. Altogether, our data demonstrate that EOMES is indispensable for the development of IL-10-expressing, cytotoxic TR1 cells, which accumulate in LNs of CLL patients and control TCL1 leukemia in mice in an IL-10R-dependent manner.

Down-regulation of EOMES drives T-cell exhaustion via abolishing EOMES-mediated repression of inhibitory receptors of T cells in liver cancer

T‐cell exhaustion is one of the hallmarks in cancer, but the mechanisms underlying T‐cell dysregulation remains unclear. Here, we reported that down‐regulation of transcription factor EOMES contributed to increased levels of inhibitory receptors in T cell among the tumour tissues and resulted in the poor prognosis of hepatocellular carcinoma (HCC). By analysing the correlation between EOMES in tumour‐infiltrating T cells and the clinical features, we demonstrated that the EOMES was related to the advanced stage and poor prognosis of HCC. Further mechanistic studies revealed that the EOMES mainly expressed in the CD8⁺ T cells and were down‐regulated in tumour samples. Moreover, we demonstrated that the EOMES directly bound at the transcriptional regulatory regions of the key inhibitory factors including PD‐1, CTAL‐4 and CD39, and lower levels of EOMES contributed to overexpression of these factors in T cells. Together, our studies provide new insight into the transcriptional deregulation of the inhibitory receptors on T cells during the tumorigenesis.

T-bet and STAT6 Coordinately Suppress the Development of IL-9-Mediated Atopic Dermatitis-Like Skin Inflammation in Mice

T-bet and signal transducer and activator of transcription (STAT) 6 are critical factors for helper T-cell differentiation in humans and mice. Additionally, polymorphisms in TBX21 (T-bet) and STAT6 are associated with the susceptibility of allergic diseases. However, precise mechanisms of the reciprocal regulation between T-bet and STAT6 in allergy remain unclear. To determine the reciprocal regulation in vivo, we investigated the phenotype of T-bet/STAT6 double-deficient (T-bet^-/- STAT6^-/-) mice. Unexpectedly, T-bet^-/- STAT6^-/- mice but not T-bet^-/- mice or STAT6^-/- mice spontaneously developed severe dermatitis. Not only eosinophils and mast cells but also CD4⁺ T cells infiltrated into the skin of T-bet^-/- STAT6^-/- mice. Adoptive transfer of CD4⁺ T cells of T-bet^-/- STAT6^-/- mice into severe combined immunodeficient mice induced the accumulation of eosinophils and mast cells in the skin, whereas depletion of CD4⁺ T cells ameliorated the dermatitis in T-bet^-/- STAT6^-/- mice. Comprehensive transcriptome analyses revealed that IL-9 expression was enhanced in T-bet^-/- STAT6^-/- CD4⁺ T cells. Indeed, IL-9 neutralization ameliorated the dermatitis in T-bet^-/- STAT6^-/- mice. T-bet^-/- STAT6^-/- CD4⁺ T cells expressed functional thymic stromal lymphopoietin receptors and produced large amounts of IL-9 on thymic stromal lymphopoietin stimulation. These results indicate that T-bet and STAT6 coordinately suppress atopic dermatitis-like skin inflammation, possibly by inhibiting thymic stromal lymphopoietin-dependent IL-9 production in CD4⁺ T cells.

sLeX Expression Delineates Distinct Functional Subsets of Human Blood Central and Effector Memory T Cells

Sialyl Lewis X (sLeX) regulates T cell trafficking from the vasculature into skin and sites of inflammation, thereby playing a critical role in immunity. In healthy persons, only a small proportion of human blood T cells express sLeX, and their function is not fully defined. Using a combination of biochemical and functional studies, we find that human blood sLeX+CD4+T cells comprise a subpopulation expressing high levels of Th2 and Th17 cytokines, chemokine receptors CCR4 and CCR6, and the transcription factors GATA-3 and RORγT. Additionally, sLeX+CD4+T cells exclusively contain the regulatory T cell population (CD127lowCD25high and FOXP3+) and characteristically display immune-suppressive molecules, including the coinhibitor receptors PD-1 and CTLA-4. Among CD8+T cells, sLeX expression distinguishes a subset displaying low expression of cytotoxic effector molecules, perforin and granzyme β, with reduced degranulation and CD57 expression and, consistently, marginal cytolytic capacity after TCR engagement. Furthermore, sLeX+CD8+T cells present a pattern of features consistent with Th cell-like phenotype, including release of pertinent Tc2 cytokines and elevated expression of CD40L. Together, these findings reveal that sLeX display is associated with unique functional specialization of both CD4+ and CD8+T cells and indicate that circulating T cells that are primed to migrate to lesional sites at onset of inflammation are not poised for cytotoxic function.

Role of γδT cells in liver diseases and its relationship with intestinal microbiota

γδT cells are unconventional T lymphocytes that bridge innate and adaptive immunity. Based on the composition of T cell receptor and the cytokines produced, γδT cells can be divided into diverse subsets that may be present at different locations, including the liver, epithelial layer of the gut, the dermis and so on. Many of these cells perform specific functions in liver diseases, such as viral hepatitis, autoimmune liver diseases, non-alcoholic fatty liver disease, liver cirrhosis and liver cancers. In this review, we discuss the distribution, subsets, functions of γδT cells and the relationship between the microbiota and γδT cells in common hepatic diseases. As γδT cells have been used to cure hematological and solid tumors, we are interested in γδT cell-based immunotherapies to treat liver diseases.

Programmed T cell differentiation: Implications for transplantation

While T cells play a critical role in protective immunity against infection, they are also responsible for graft rejection in the setting of transplantation. T cell differentiation is regulated by both intrinsic transcriptional pathways as well as extrinsic factors such as antigen encounter and the cytokine milieu. Herein, we review recent discoveries in the transcriptional regulation of T cell differentiation and their impact on the field of transplantation. Recent studies uncovering context-dependent differentiation programs that differ in the setting of infection or transplantation will also be discussed. Understanding the key transcriptional pathways that underlie T cell responses in transplantation has important clinical implications, including development of novel therapeutic agents to mitigate graft rejection.

Pharmacological Activation of Pyruvate Kinase M2 Inhibits CD4+ T Cell Pathogenicity and Suppresses Autoimmunity

Pyruvate kinase (PK) catalyzes the conversion of phosphoenolpyruvate to pyruvate during glycolysis. The PK isoform PKM2 has additional roles in regulation of gene transcription and protein phosphorylation. PKM2 has been shown to control macrophage metabolic remodeling in inflammation, but its role in T cell biology is poorly understood. Here, we report PKM2 upregulation, phosphorylation, and nuclear accumulation in murine and human CD4+ T cells following activation in vitro. Treatment of T cells with TEPP-46, an allosteric activator that induces PKM2 tetramerization and blocks its nuclear translocation, strongly reduces their activation, proliferation, and cytokine production by inhibiting essential signaling pathways and thus preventing the engagement of glycolysis. TEPP-46 limits the development of both T helper 17 (Th17) and Th1 cells in vitro and ameliorates experimental autoimmune encephalomyelitis (EAE) in vivo. Overall, our results suggest that pharmacological targeting of PKM2 may represent a valuable therapeutic approach in T cell-mediated inflammation and autoimmunity.

Regulatory T Cells Restrain Interleukin-2- and Blimp-1-Dependent Acquisition of Cytotoxic Function by CD4+ T Cells

In addition to helper and regulatory potential, CD4+ T cells also acquire cytotoxic activity marked by granzyme B (GzmB) expression and the ability to promote rejection of established tumors. Here, we examined the molecular and cellular mechanisms underpinning the differentiation of cytotoxic CD4+ T cells following immunotherapy. CD4+ transfer into lymphodepleted animals or regulatory T (Treg) cell depletion promoted GzmB expression by tumor-infiltrating CD4+, and this was prevented by interleukin-2 (IL-2) neutralization. Transcriptional analysis revealed a polyfunctional helper and cytotoxic phenotype characterized by the expression of the transcription factors T-bet and Blimp-1. While T-bet ablation restricted interferon-γ (IFN-γ) production, loss of Blimp-1 prevented GzmB expression in response to IL-2, suggesting two independent programs required for polyfunctionality of tumor-reactive CD4+ T cells. Our findings underscore the role of Treg cells, IL-2, and Blimp-1 in controlling the differentiation of cytotoxic CD4+ T cells and offer a pathway to enhancement of anti-tumor activity through their manipulation.

Regulators of T-cell fate: Integration of cell migration, differentiation and function

A fundamental question in immunology is how cells decide between distinct T helper, effector or memory differentiation fates. These decisions are paramount to overcome infection and establish long-lasting protection. The impact of cell location for the determination of T-cell fate decisions is an emerging field. This review will discuss our current understanding of the migration path that T cells follow, within draining lymph nodes, to steer differentiation down distinct paths of either effector or memory fates. In particular, the regulation of migration and cellular encounters mediated by the chemokine receptor CXCR3 and its ligands will be discussed. The combination of increased antigen density and unique cellular partners play a central role in facilitating the site-specific differentiation of effector T cells, within the interfollicular regions of draining lymph nodes. Recent advances have applied this knowledge to optimize vaccine design to target antigen to lymph nodes. Increased understanding of the regulation of CXCR3 ligands and how T cells integrate multiple chemokine cues will help further progress in this field and allow additional applications to direct cell differentiation outside the lymph node, to enhance memory residency in peripheral tissues and effector anti-tumor responses.

A Double-Blind, Phase I, Single Ascending Dose Study to Assess the Safety, Pharmacokinetics, and Pharmacodynamics of BOS161721 in Healthy Subjects

The purpose of this study was to assess the safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity of BOS161721, a humanized immunoglobulin G1 triple mutation (M252Y/S254T/T256E) monoclonal antibody that inhibits interleukin‐21 (IL‐21) bioactivity. This randomized, single‐center, double‐blind, placebo‐controlled study randomized healthy volunteers 3:1 to single ascending intravenous and subcutaneous doses of BOS161721 (range 1–240 mg) or placebo. BOS161721 and placebo groups had similar rates of adverse events, mostly mild; none led to study discontinuation. There were no clinically significant findings in physical examination, vital signs, or laboratory assessment. In the pooled BOS161721 population, four subjects (8.5%) tested antidrug antibody‐positive predose, and seven (14.9%) postdose. Absolute CD4+ lymphocyte count remained normal throughout follow‐up. BOS161721 administered subcutaneously was absorbed slowly, with a median time to maximum concentration (T_max) of 144 hours across doses (range 1–15 days) and a mean apparent terminal elimination half‐life of 80–87 days for doses ≥ 30 mg. Area under the concentration‐time curve from time zero to infinity (AUC_0‐inf) and maximum observed concentration (C_max) were linear across doses > 10 mg. Subcutaneous bioavailability was 64%. Phosphorylated signal transducer and activator of transcription 3 (pSTAT3) decreased dose‐dependently with threshold characteristics at doses of ≥ 10 mg. Downregulation in BATF, IL6, LAG3, and SOCS3 genes caused by IL‐21 stimulation was reversed dose‐dependently. BOS161721 was well‐tolerated across doses, suppressed IL‐21‐induced pSTAT3 dose‐dependently, and reversed downregulation of genes critical to tolerance induction and T‐cell exhaustion induced by IL‐21. Further clinical studies are ongoing in patients with systemic lupus erythematosus, in which IL‐21 has a pathogenetic role.

T-bet optimizes CD4 T-cell responses against influenza through CXCR3-dependent lung trafficking but not functional programming

Although clearance of many intracellular pathogens requires T-bet-dependent CD4 T cell programming, the extent to which T-bet is needed to direct protective CD4 responses against influenza is not known. Here, we characterize wild-type and T-bet-deficient CD4 cells during murine influenza infection. Surprisingly, although T-bet expression has broad impacts on cytokine production by virus-specific CD4 cells, the protective efficacy of T-bet-deficient effector cells is only marginally reduced. This reduction is due to lower CXCR3 expression, leading to suboptimal accumulation of activated T-bet-deficient cells in the infected lung. However, T-bet-deficient cells outcompete wild-type cells to form lung-resident and circulating memory populations following viral clearance, and primed T-bet-deficient mice efficiently clear supralethal heterosubtypic influenza challenges even when depleted of CD8 T cells. These results are relevant to the identification of more incisive correlates of protective T cells and for vaccines that aim to induce durable cellular immunity against influenza.

Phenotypic and functional analysis of malignant mesothelioma tumor-infiltrating lymphocytes

Given the growing interest and promising preliminary results of immunotherapy in malignant pleural mesothelioma (MPM), it has become important to more fully understand the immune landscape in this tumor. This may be especially relevant in deciding who might benefit most from checkpoint blockade or agonist antibody therapy. Since the phenotype of tumor infiltrating lymphocytes (TILs) in MPM has not been fully described and their function has not been carefully assessed, we collected fresh tumor and blood from 22 patients undergoing surgical resection and analysed single cell suspensions by flow cytometry. The functionality of TILs was assessed by measurement of cytokine expression (IFN-γ) following overnight stimulation ex vivo. Results showed low numbers of CD8+ TILs whose function was either moderately or severely suppressed. The degree of TIL hypofunction did not correlate with the presence of co-existing macrophages or neutrophils, nor with expression of the inhibitory receptors PD-1, CD39 and CTLA-4. Hypofunction was associated with higher numbers of CD4 regulatory T cells (Tregs) and with expression of the inhibitory receptor TIGIT. On the other hand, presence of tissue-resident memory (Trm) cells and expression of TIM-3 on CD8+ cells were positively associated with cytokine production. However, Trm function was partially suppressed when the transcription factor Eomesodermin (Eomes) was co-expressed. Understanding the function of TILs in malignant mesothelioma may have clinical implications for immunotherapy, especially in choosing the best immunotherapy targets. Our data suggests that Treg cell blocking agents or TIGIT inhibitor antibodies might be especially valuable in these patients.

The role of Eomes in human CD4 T cell differentiation: A question of context

Eomesodermin (Eomes) is a transcription factor (TF) of the T-box family closely related to T-bet known for its role in CD8 T cell and natural killer cell differentiation. However, the role of Eomes in CD4 T-cell differentiation is less well appreciated. In this issue of the European Journal of Immunology [Eur. J. Immunol. 2019. 49: 79-95] Mazzoni et al. and [Eur. J. Immunol. 2019. 49: 96-111] Gruarin et al. studied the role of Eomes in human CD4 T-cell differentiation. Mazzoni et al. showed that Eomes plays a key role in helper T cell (Th) plasticity by favoring the phenotype shift of Th17 cells toward non-classic Th1 cells; while Gruarin et al. proposed Eomes as a lineage-defining TF for human IL-10 and IFN-γ co-producing regulatory T-cells (Tr1 cells). Both studies show that Eomes drives IFN-γ secretion and stamps a "cytotoxic" signature, while it also represses Th17 features. However, additional signals including the cytokine milieu may further influence the fate of Eomes⁺ CD4 T cells. A common feature of Eomes⁺ CD4 T cells appears to be their accumulation in inflamed tissues in patients with chronic inflammatory disorders. Whether Eomes favors expression of the proinflammatory cytokines or on the contrary, promotes the anti-inflammatory cytokines, remains a matter of debate.

Chronic retroviral infection of mice promotes tumor development, but CD137 agonist therapy restores effective tumor immune surveillance

T cell responses are crucial for anti-tumor immunity. In chronic viral infections, anti-tumor T cell responses can be compromised due to various immunological mechanisms, including T cell exhaustion. To study mechanisms of anti-tumor immunity during a chronic viral infection, we made use of the well-established Friend virus (FV) mouse model. Chronically FV-infected mice are impaired in their ability to reject FBL-3 cells-a virus-induced tumor cell line of C57BL/6 origin. Here we aimed to explore therapeutic strategies to overcome the influence of T cell exhaustion during chronic viral infection, and reactivate effector CD8+ and CD4+ T cells to eliminate tumor cells. For T cell stimulation, agonistic antibodies against the tumor necrosis factor receptor (TNFR) superfamily members CD137 and CD134 were used, because they were reported to augment the cytotoxic program of T cells. αCD137 agonistic therapy, but not αCD134 agonistic therapy, resulted in FBL-3 tumor elimination in chronically FV-infected mice. CD137 stimulation significantly enhanced the cytotoxic activity of both CD4+ and CD8+ T cells, which were both required for efficient tumor control. Our study suggests that agonistic antibodies to CD137 can efficiently enhance anti-tumor immunity even in the setting of chronic viral infection, which might have promising therapeutic applications.

Assessing the role of the T-box transcription factor Eomes in B cell differentiation during either Th1 or Th2 cell-biased responses

Successful T-dependent humoral responses require the production of antibody-secreting plasmablasts, as well as the formation of germinal centers which eventually form high-affinity B cell memory. The ability of B cells to differentiate into germinal center and plasma cells, as well as the ability to tailor responses to different pathogens, is driven by transcription factors. In T cells, the T-box transcription factors T-bet and Eomesodermin (Eomes) regulate effector and memory T cell differentiation, respectively. While T-bet has a critical role in regulating anti-viral B cell responses, a role for Eomes in B cells has yet to be described. We therefore investigated whether Eomes was required for B cell differentiation during either Th1 or Th2 cell-biased immune responses. Here, we demonstrate that deletion of Eomes specifically in B cells did not affect B cell differentiation in response to vaccination, as well as following viral or helminth infection. In contrast to its established role in CD8⁺ T cells, Eomes did not influence memory B cell differentiation. Finally, the use of an Eomes reporter mouse confirmed the lack of Eomes expression during immune responses. Thus, germinal center and plasma cell differentiation and the formation of isotype-switched memory B cells in response to infection are independent of Eomes expression.

The role of transforming growth factor β in T helper 17 differentiation

T helper 17 (Th17) cells play critical roles in inflammatory and autoimmune diseases. The lineage-specific transcription factor RORγt is the key regulator for Th17 cell fate commitment. A substantial number of studies have established the importance of transforming growth factor β (TGF-β) -dependent pathways in inducing RORγt expression and Th17 differentiation. TGF-β superfamily members TGF-β1 , TGF-β3 or activin A, in concert with interleukin-6 or interleukin-21, differentiate naive T cells into Th17 cells. Alternatively, Th17 differentiation can occur through TGF-β-independent pathways. However, the mechanism of how TGF-β-dependent and TGF-β-independent pathways control Th17 differentiation remains controversial. This review focuses on the perplexing role of TGF-β in Th17 differentiation, depicts the requirement of TGF-β for Th17 development, and underscores the multiple mechanisms underlying TGF-β-promoted Th17 generation, pathogenicity and plasticity. With new insights and comprehension from recent findings, this review specifically tackles the involvement of the canonical TGF-β signalling components, SMAD2, SMAD3 and SMAD4, summarizes diverse SMAD-independent mechanisms, and highlights the importance of TGF-β signalling in balancing the reciprocal conversion of Th17 and regulatory T cells. Finally, this review includes discussions and perspectives and raises important mechanistic questions about the role of TGF-β in Th17 generation and function.

Clinical significance of CD161+CD4+ T cells in the development of chronic antibody-mediated rejection in kidney transplant recipients

In this study, we investigated whether CD161⁺CD4⁺ T cells can reflect the Th17 pathway in kidney transplant recipients (KTRs) and investigated the clinical significance of this cell type in chronic antibody-mediated rejection (cAMR) in KT. First, we investigated the relationship between CD161⁺CD4⁺ T and Th17 cells by flow cytometry and microarray analysis in an in vitro study. Second, we compared the proportion of T cell subsets including CD161⁺CD4⁺ T cells in cAMR (n = 18), long-term graft survival (LTGS) (n = 46), and interstitial fibrosis/tubular atrophy (IF/TA) (n = 22). We compared CD161⁺ cell infiltration between cAMR and IF/TA and also examined the effect of CD161⁺ T cells on human renal proximal tubular epithelial cells (HRPTEpiC). In flow cytometry, the proportion of CD161⁺CD4⁺ T cells showed a significant correlation with the proportion of Th17 cells. In microarray analysis, transcripts associated with the Th17 pathway such as IL18RAP, IL-18R1, IL23R, IL12RB2, RORC, TBX21, and EOMES were upregulated in CD161⁺ cells compared with CD161^- cells. In an ex vivo study, only CD161⁺CD4⁺ T cells showed a significant increase in the cAMR group compared with IF/TA and LTGS groups. In allograft tissue, CD161⁺ cells showed a higher level of infiltration in the cAMR group than the IF/TA group. Lastly, CD161⁺ T cells increased the production of inflammatory cytokines from HRPTEpiC in a dose-dependent manner. This study suggests that monitoring of CD161⁺ T cells can be useful to detect the progression of cAMR.

A novel model for dissecting roles of IL-17 in lung transplantation

Background

The long-term success of lung transplantation is limited by the development of chronic lung allograft dysfunction (CLAD) in which IL-17 plays an important role. Direct evidence of IL-17-mediated allograft rejection has been observed when T-bet is absent. However, lack of T-bet also leads to failure in production of IFN-γ which is required for tolerance induction and allograft acceptance, as T-bet deficiency results in IL-17-expressing CD8+ T cells mediated costimulation blockade-resistant allograft rejection. Our previous research demonstrated that additional STAT6 deficiency to T-bet deficiency resulted in Th17-dominant immune responses, and importantly, restored IFN-γ production. Here we investigated whether T-bet/STAT6 double knout-out (DKO) mice as allograft recipients could provide a useful model to study IL-17 and Th17 in lung transplantation.

Methods

Murine orthotopic allogeneic lung transplants were performed in C57BL/6 wild type (WT) or T-bet/STAT6 DKO (C57BL/6 background) mice using MHC fully mismatched BALB/c donors. Syngeneic transplants were also performed in WT C57BL/6 mice using C57BL/6 donors. At day 10, histopathologic characteristics and rejection status of transplanted grafts were assessed; graft-infiltrating cells were isolated and real-time RT-PCR was performed for IL-17, IFN-γ and IL-4 expressions.

Results

Isografts showed no apparent rejection as anticipated. Allografts of both WT and DKO recipients displayed vigorous acute rejection and expressed comparable levels of IFN-γ; while T-bet/STAT6 double deficiency resulted in much more IL-17 and less IL-4 production. Histopathologic examination demonstrated that allografts of both WT and DKO recipients have marked inflammatory cell infiltration and pulmonary parenchyma lesion. In contrast to lymphocyte-predominant inflammation observed in WT recipients, allografts of DKO recipients displayed obvious polymorphonuclear cell infiltration and severer obliterative airway inflammation. Compared to WT recipients, the ratio of graft-infiltrating CD8+ versus CD4+ T cells increased significantly with much higher numbers of neutrophils in allografts of DKO recipients.

Conclusions

T-bet/STAT6 DKO recipients of lung allografts result in IL-17-dominant transplant immunity, retain IFN-γ responses, and develop neutrophilia, obliterative airway inflammation and acute transplant rejection. Our results indicate that T-bet/STAT6 DKO mice serving as allograft recipient could be utilized as a new viable model to study the roles of IL-17 in lung transplantation.

Mucosa-associated invariant T cells link intestinal immunity with antibacterial immune defects in alcoholic liver disease

BACKGROUND/AIMS

Intestinal permeability with systemic distribution of bacterial products are central in the immunopathogenesis of alcoholic liver disease (ALD), yet links with intestinal immunity remain elusive. Mucosa-associated invariant T cells (MAIT) are found in liver, blood and intestinal mucosa and are a key component of antibacterial host defences. Their role in ALD is unknown.

METHODS/DESIGN

We analysed frequency, phenotype, transcriptional regulation and function of blood MAIT cells in severe alcoholic hepatitis (SAH), alcohol-related cirrhosis (ARC) and healthy controls (HC). We also examined direct impact of ethanol, bacterial products from faecal extracts and antigenic hyperstimulation on MAIT cell functionality. Presence of MAIT cells in colon and liver was assessed by quantitative PCR and immunohistochemistry/gene expression respectively.

RESULTS

In ARC and SAH, blood MAIT cells were dramatically depleted, hyperactivated and displayed defective antibacterial cytokine/cytotoxic responses. These correlated with suppression of lineage-specific transcription factors and hyperexpression of homing receptors in the liver with intrahepatic preservation of MAIT cells in ALD. These alterations were stronger in SAH, where surrogate markers of bacterial infection and microbial translocation were higher than ARC. Ethanol exposure in vitro, in vivo alcohol withdrawal and treatment with Escherichia coli had no effect on MAIT cell frequencies, whereas exposure to faecal bacteria/antigens induced functional impairments comparable with blood MAIT cells from ALD and significant MAIT cell depletion, which was not observed in other T cell compartments.

CONCLUSIONS

In ALD, the antibacterial potency of MAIT cells is compromised as a consequence of contact with microbial products and microbiota, suggesting that the 'leaky' gut observed in ALD drives MAIT cell dysfunction and susceptibility to infection in these patients.

Limited immune surveillance in lymphoid tissue by cytolytic CD4+ T cells during health and HIV disease

CD4+ T cells subsets have a wide range of important helper and regulatory functions in the immune system. Several studies have specifically suggested that circulating effector CD4+ T cells may play a direct role in control of HIV replication through cytolytic activity or autocrine β-chemokine production. However, it remains unclear whether effector CD4+ T cells expressing cytolytic molecules and β-chemokines are present within lymph nodes (LNs), a major site of HIV replication. Here, we report that expression of β-chemokines and cytolytic molecules are enriched within a CD4+ T cell population with high levels of the T-box transcription factors T-bet and eomesodermin (Eomes). This effector population is predominately found in peripheral blood and is limited in LNs regardless of HIV infection or treatment status. As a result, CD4+ T cells generally lack effector functions in LNs, including cytolytic capacity and IFNγ and β-chemokine expression, even in HIV elite controllers and during acute/early HIV infection. While we do find the presence of degranulating CD4+ T cells in LNs, these cells do not bear functional or transcriptional effector T cell properties and are inherently poor to form stable immunological synapses compared to their peripheral blood counterparts. We demonstrate that CD4+ T cell cytolytic function, phenotype, and programming in the peripheral blood is dissociated from those characteristics found in lymphoid tissues. Together, these data challenge our current models based on blood and suggest spatially and temporally dissociated mechanisms of viral control in lymphoid tissues.

CD4+ T cells have classically been divided into different subsets based on their different abilities to help and regulate specific parts of the immune system. Recent work in the HIV field has demonstrated that HIV-specific CD4+ T cells with unique effector functions, such as cytolytic activity and β-chemokine production, can play a direct role in control of HIV replication. However, HIV infection is generally considered to be a disease centered in lymphoid tissues, where unique CD4+ T helper cell subsets are present to orchestrate the maturation and priming of adaptive immunity. In this study, we identify that two specific transcription factors, T-bet and Eomes, mark cytolytic and β-chemokine producing CD4+ T cells. While this effector CD4+ T cell population is part of immunosurveillance mechanisms in blood, we find that lymph nodes largely lack this effector population–independent of HIV infection or disease progression status. These results indicate that current effector CD4+ T cell mediated correlates of HIV control are limited to blood and not representative of potential correlates of control in lymphoid tissues.

T-bet and Eomes govern differentiation and function of mouse and human NK cells and ILC1

T-bet and Eomes are T-box transcription factors that drive the differentiation and function of cytotoxic lymphocytes such as NK cells. Their DNA-binding domains are highly similar, suggesting redundant transcriptional activity. However, while these transcription factors have different patterns of expression, the phenotype of loss-of-function mouse models suggests that they play distinct roles in the development of NK cells and other innate lymphoid cells (ILCs). Recent technological advances using reporter mice and conditional knockouts were fundamental in defining the regulation and function of these factors at steady state and during pathological conditions such as various types of cancer or infection. Here, we review these recent developments, focusing on NK cells as prototypical cytotoxic lymphocytes and their development, and also discuss parallels between NK cells and T cells. We also examine the role of T-bet and Eomes in human NK cells and ILC1s. Considering divergent findings on mouse and human ILC1s, we propose that NK cells are defined by coexpression of T-bet and Eomes, while ILC1s express only one of these factors, either T-bet or Eomes, depending on the tissue or the species.

New traffic light on Th17 Avenue

Activation of STAT3-coupled receptors along with TGF-β signaling are fundamental for Th17 cell differentiation both in vivo and in vitro. A recent paper shows that TGF-β signaling relieves SKI-mediated transcriptional repression of Rorc, the key regulator of the Th17 program.

Enhanced Rg3 negatively regulates Th1 cell responses

Background

Korean Red Ginseng (KRG; Panax ginseng Meyer) is a widely used medicinal herb known to exert various immune modulatory functions. KRG and one of its purified components, ginsenoside Rg3, are known to possess anti-inflammatory activities. How they impact helper T cell-mediated responses is not fully explored. In this study, we attempted to evaluate the effect of KRG extract (KRGE) and ginsenoside Rg3 on Th1 cell responses.

Methods

Using well-characterized T cell in vitro differentiation systems, we examined the effects of KRGE or enhanced Rg3 on the Th1-inducing cytokine production from dendritic cells (DC) and the naïve CD4⁺ T cells differentiation to Th1 cells. Furthermore, we examined the change of Th1 cell population in the intestine after treatment of enhanced Rg3. The influence of KRGE or enhanced Rg3 on Th1 cell differentiation was evaluated by fluorescence-activated cell sorting, enzyme-linked immunosorbent assay, and quantitative real-time polymerase chain reaction.

Results

KRGE significantly inhibited the production level of IL-12 from DCs and subsequent Th1 cell differentiation. Similarly, enhanced Rg3 significantly suppressed the expression of interferon gamma (IFNγ) and T-bet in T cells under Th1-skewing condition. Consistent with these effects in vitro, oral administration of enhanced Rg3 suppressed the frequency of Th1 cells in the Peyer's patch and lamina propria cells in vivo.

Conclusion

Enhanced Rg3 negatively regulates the differentiation of Th1 cell in vitro and Th1 cell responses in the gut in vivo, providing fundamental basis for the use of this agent to treat Th1-related diseases.

Langerhans Cells Express IL-17A in the Epidermis of Chromoblastomycosis Lesions

Chromoblastomycosis (CBM) is a chronic fungal infection that affects skin and subcutaneous tissue, and little is known about the immunological aspects of such lesions. We have previously described the high expression of IL-17 in this group. Understanding the innate immune response of patients with CBM would improve the knowledge of its immunopathogenesis and contribute to the most appropriate therapies. Nineteen biopsies of verrucous form were obtained from patients with clinical and histopathological diagnosis of CBM, without treatment. This was done with a double immunostaining with conventional immunohistochemistry and immunofluorescence technique as well as confocal microscopy to detect Langerin and IL-17 expression. All of the specimens that were analyzed showed expression of Langerin in the epidermis - the same as the control group. However, only the CBM group presented cells expressing CD207 in the dermis. Interestingly, the coexpression of IL-17 and Langerin was visualized along the epidermis and dermis in 100% of the lesion group. We demonstrated for the first time in situ coexpression of IL-17 and Langerin (CD207) in epidermal cells of patients with CBM and speculated on their role as IL-17-producing cells or whether they could be a new subpopulation of dendritic cells distinct from Langerhans cells.

1,25(OH)2D3 Protects Liver Fibrosis Through Decreasing the Generation of TH17 Cells

BACKGROUND The aim of this study was to study the effects of 1-alpha,25-dihydroxy-cholecalcifero (1,25(OH)2D3) on liver fibrosis and the generation of Th17 cells in vivo and in vitro. MATERIAL AND METHODS Thirty C57 mice were randomly divided into control, model, and treatment groups. Hepatic fibrosis was induced by subcutaneous injection of CCl4. Liver fibrosis condition was evaluated through pathological inspection and blood biochemical examination of liver function. Immunohistochemical assays were used to detect the expression of α-SMA, TGF-β, and collagen I to observe hepatic stellate cell activation level. Flow cytometry, ELISA, and RT-PCR were performed to explore the association between 1,25(OH)2D3 and Th17 cell differentiation. RESULTS Collagen I, TGF-β, and α-SMA were decreased after 1,25(OH)2D3 treatment. Consistently, RORγt mRNA and the rate of Th17 cells was significantly reduced after 1,25(OH)2D3 treatment. In vitro, the proportion of Th17 cells was also obviously reduced in the 1,25(OH)2D3 group, and mRNA levels of IL-17A, IL-22, RORγt, and RORa were significantly decrease in the 1,25(OH)2D3 group compared to the control group. CONCLUSIONS Treatment with 1,25(OH)2D3 can alleviate the damage caused by liver fibrosis. Experiments in vivo and in vitro showed that 1,25(OH)2D3 treatment deceased the rates of Th1 and Th17 cells and increased the rate of Th2 cells. The level of IL-17A, IL-22 and IFN-γ were decreased, while the level of IL-4 was increased by the treatment of 1,25(OH)2D3.

B cells expressing the transcription factor T-bet drive lupus-like autoimmunity

B cells contribute to multiple aspects of autoimmune disorders and may play a role in triggering disease. Thus, targeting B cells may be a promising strategy for treating autoimmune disorders. Better understanding of the B cell subsets that are responsible for the development of autoimmunity will be critical for developing efficient therapies. Here we have reported that B cells expressing the transcription factor T-bet promote the rapid appearance of autoantibodies and germinal centers in spontaneous murine models of systemic lupus erythematosus (SLE). Conditional deletion of T-bet from B cells impaired the formation of germinal centers and mitigated the development of kidney damage and rapid mortality in SLE mice. B cell-specific deletion of T-bet was also associated with lower activation of both B cells and T cells. Taken together, our results suggest that targeting T-bet-expressing B cells may be a potential target for therapy for autoimmune diseases.

The High Mobility Group A1 (HMGA1) Transcriptome in Cancer and Development

BACKGROUND & OBJECTIVES

Chromatin structure is the single most important feature that distinguishes a cancer cell from a normal cell histologically. Chromatin remodeling proteins regulate chromatin structure and high mobility group A (HMGA1) proteins are among the most abundant, nonhistone chromatin remodeling proteins found in cancer cells. These proteins include HMGA1a/HMGA1b isoforms, which result from alternatively spliced mRNA. The HMGA1 gene is overexpressed in cancer and high levels portend a poor prognosis in diverse tumors. HMGA1 is also highly expressed during embryogenesis and postnatally in adult stem cells. Overexpression of HMGA1 drives neoplastic transformation in cultured cells, while inhibiting HMGA1 blocks oncogenic and cancer stem cell properties. Hmga1 transgenic mice succumb to aggressive tumors, demonstrating that dysregulated expression of HMGA1 causes cancer in vivo. HMGA1 is also required for reprogramming somatic cells into induced pluripotent stem cells. HMGA1 proteins function as ancillary transcription factors that bend chromatin and recruit other transcription factors to DNA. They induce oncogenic transformation by activating or repressing specific genes involved in this process and an HMGA1 "transcriptome" is emerging. Although prior studies reveal potent oncogenic properties of HMGA1, we are only beginning to understand the molecular mechanisms through which HMGA1 functions. In this review, we summarize the list of putative downstream transcriptional targets regulated by HMGA1. We also briefly discuss studies linking HMGA1 to Alzheimer's disease and type-2 diabetes.

CONCLUSION

Further elucidation of HMGA1 function should lead to novel therapeutic strategies for cancer and possibly for other diseases associated with aberrant HMGA1 expression.

Block of both TGF-β and IL-2 signaling impedes Neurophilin-1+ regulatory T cell and follicular regulatory T cell development

Understanding the mechanisms that lead to autoimmunity is critical for defining potential therapeutic pathways. In this regard there have been considerable efforts in investigating the interacting roles of TGF-β and IL-2 on the function regulatory T cells. We have taken advantage of dnTGF-βRII Il2ra-/- (abbreviated as Il2ra-/-Tg) mouse model, which allows a direct mechanistic approach to define the relative roles of TGF-β and IL-2 on Treg development. Il2ra-/-Tg mice spontaneously developed multi-organ autoimmune diseases with expansion of pathogenic T cells and enhanced germinal center response at 3-4 weeks of age. Importantly, peripheral Treg cells from Il2ra-/-Tg mice demonstrated an activated Th1-like stable phenotype and normal in vitro suppressive function, while thymus Treg increased but manifested decreased suppressive function. Interestingly, neither thymus nor peripheral Treg cells of Il2ra-/-Tg mice contained Neuropilin-1+ or PD-1hi phenotype, resulting in defective follicular regulatory T (Tfr) cell development. Such defective Tfr development led to elevated follicular T helper cells, enhanced germinal center responses and increased plasma cell infiltration. These data demonstrate an important synergetic role of TGF-β and IL-2 in the generation, activation and stability of Treg cells, as well as their subsequent development into Tfr cells.

Foxo3 Transcription Factor Drives Pathogenic T Helper 1 Differentiation by Inducing the Expression of Eomes

The transcription factor Foxo3 plays a crucial role in myeloid cell function but its role in lymphoid cells remains poorly defined. Here, we have shown that Foxo3 expression was increased after T cell receptor engagement and played a specific role in the polarization of CD4⁺ T cells toward pathogenic T helper 1 (Th1) cells producing interferon-γ (IFN-γ) and granulocyte monocyte colony stimulating factor (GM-CSF). Consequently, Foxo3-deficient mice exhibited reduced susceptibility to experimental autoimmune encephalomyelitis. At the molecular level, we identified Eomes as a direct target gene for Foxo3 in CD4⁺ T cells and we have shown that lentiviral-based overexpression of Eomes in Foxo3-deficient CD4⁺ T cells restored both IFN-γ and GM-CSF production. Thus, the Foxo3-Eomes pathway is central to achieve the complete specialized gene program required for pathogenic Th1 cell differentiation and development of neuroinflammation.

Osteoclast-Primed Foxp3+ CD8 T Cells Induce T-bet, Eomesodermin, and IFN-γ To Regulate Bone Resorption

Osteoimmunology arose from the recognition that cytokines produced by lymphocytes can affect bone homeostasis. We have previously shown that osteoclasts, cells that resorb bone, act as APCs. Cross-presentation of Ags by osteoclasts leads to expression of CD25 and Foxp3, markers of regulatory T cells in the CD8 T cells. Octeoclast-induced Foxp3(+) CD25(+) regulatory CD8 T cells (OC-iTcREG) suppress priming of CD4 and CD8 T cells by dendritic cells. OC-iTcREG also limit bone resorption by osteoclasts, forming a negative feedback loop. In this study, we show that OC-iTcREG express concurrently T-bet and Eomesodermin (Eomes) and IFN-γ. Pharmacological inhibition of IκK blocked IFN-γ, T-bet, and Eomes production by TcREG Furthermore, we show, using chromatin immunoprecipitation, NF-κB enrichment in the T-bet and Eomes promoters. We demonstrate that IFN-γ produced by TcREG is required for suppression of osteoclastogenesis and for degradation of TNFR-associated factor 6 in osteoclast precursors. The latter prevents signaling by receptor activator of NF-κB ligand needed for osteoclastogenesis. Knockout of IFN-γ rendered TcREG inefficient in preventing actin ring formation in osteoclasts, a process required for bone resorption. TcREG generated in vivo using IFN-γ(-/-) T cells had impaired ability to protect mice from bone resorption and bone loss in response to high-dose receptor activator of NF-κB ligand. The results of this study demonstrate a novel link between NF-κB signaling and induction of IFN-γ in TcREG and establish an important role for IFN-γ in TcREG-mediated protection from bone loss.

GWAS analysis implicates NF-κB-mediated induction of inflammatory T cells in multiple sclerosis

To identify genes and biologically relevant pathways associated with risk to develop multiple sclerosis (MS), the Genome-Wide Association Studies noise reduction method (GWAS-NR) was applied to MS genotyping data. Regions of association were defined based on the significance of linkage disequilibrium blocks. Candidate genes were cross-referenced based on a review of current literature, with attention to molecular function and directly interacting proteins. Supplementary annotations and pathway enrichment scores were generated using The Database for Annotation, Visualization and Integrated Discovery. The candidate set of 220 MS susceptibility genes prioritized by GWAS-NR was highly enriched with genes involved in biological pathways related to positive regulation of cell, lymphocyte and leukocyte activation (P=6.1E-15, 1.2E-14 and 5.0E-14, respectively). Novel gene candidates include key regulators of NF-κB signaling and CD4+ T helper type 1 (Th1) and T helper type 17 (Th17) lineages. A large subset of MS candidate genes prioritized by GWAS-NR were found to interact in a tractable pathway regulating the NF-κB-mediated induction and infiltration of pro-inflammatory Th1/Th17 T-cell lineages, and maintenance of immune tolerance by T-regulatory cells. This mechanism provides a biological context that potentially links clinical observations in MS to the underlying genetic landscape that may confer susceptibility.

T-bet is a key modulator of IL-23-driven pathogenic CD4(+) T cell responses in the intestine

IL-23 is a key driver of pathogenic Th17 cell responses. It has been suggested that the transcription factor T-bet is required to facilitate IL-23-driven pathogenic effector functions; however, the precise role of T-bet in intestinal T cell responses remains elusive. Here, we show that T-bet expression by T cells is not required for the induction of colitis or the differentiation of pathogenic Th17 cells but modifies qualitative features of the IL-23-driven colitogenic response by negatively regulating IL-23R expression. Consequently, absence of T-bet leads to unrestrained Th17 cell differentiation and activation characterized by high amounts of IL-17A and IL-22. The combined increase in IL-17A/IL-22 results in enhanced epithelial cell activation and inhibition of either IL-17A or IL-22 leads to disease amelioration. Our study identifies T-bet as a key modulator of IL-23-driven colitogenic responses in the intestine and has important implications for understanding of heterogeneity among inflammatory bowel disease patients.

CD4+ Group 1 Innate Lymphoid Cells (ILC) Form a Functionally Distinct ILC Subset That Is Increased in Systemic Sclerosis

Innate lymphoid cells (ILC) are a heterogeneous group of cellular subsets that produce large amounts of T cell-associated cytokines in response to innate stimulation in the absence of Ag. In this study, we define distinct patterns of surface marker and cytokine expression among the ILC subsets that may further delineate their migration and function. Most notably, we found that the subset previously defined as group 1 ILC (ILC1) contains CD4(+) CD8(-), CD4(-) CD8(+), and CD4(-) CD8(-) populations. Although all ILC1 subsets shared characteristics with Th1 cells, CD4(+) ILC1 also demonstrated significant phenotypic and functional heterogeneity. We also show that the frequencies of CD4(+) ILC1 and NKp44(+) group 3 ILC, but not CD4(-) ILC1 or group 2 ILC, are increased in the peripheral blood of individuals with systemic sclerosis (SSc), a disease characterized by fibrotic and vascular pathology, as well as immune dysregulation. Furthermore, we demonstrate that CD4(+) and CD4(-) ILC1 are functionally divergent based on their IL-6Rα expression and that the frequency of IL-6Rα expression on ILC is altered in SSc. The distinct phenotypic and functional features of CD4(+) and CD4(-) ILC1 suggest that they may have differing roles in the pathogenesis of immune-mediated diseases, such as SSc.

Identification of novel HIV-1 dependency factors in primary CCR4(+)CCR6(+)Th17 cells via a genome-wide transcriptional approach

BACKGROUND

The HIV-1 infection is characterized by profound CD4(+) T cell destruction and a marked Th17 dysfunction at the mucosal level. Viral suppressive antiretroviral therapy restores Th1 but not Th17 cells. Although several key HIV dependency factors (HDF) were identified in the past years via genome-wide siRNA screens in cell lines, molecular determinants of HIV permissiveness in primary Th17 cells remain to be elucidated.

RESULTS

In an effort to orient Th17-targeted reconstitution strategies, we investigated molecular mechanisms of HIV permissiveness in Th17 cells. Genome-wide transcriptional profiling in memory CD4(+) T-cell subsets enriched in cells exhibiting Th17 (CCR4(+)CCR6(+)), Th1 (CXCR3(+)CCR6(-)), Th2 (CCR4(+)CCR6(-)), and Th1Th17 (CXCR3(+)CCR6(+)) features revealed remarkable transcriptional differences between Th17 and Th1 subsets. The HIV-DNA integration was superior in Th17 versus Th1 upon exposure to both wild-type and VSV-G-pseudotyped HIV; this indicates that post-entry mechanisms contribute to viral replication in Th17. Transcripts significantly enriched in Th17 versus Th1 were previously associated with the regulation of TCR signaling (ZAP-70, Lck, and CD96) and Th17 polarization (RORγt, ARNTL, PTPN13, and RUNX1). A meta-analysis using the NCBI HIV Interaction Database revealed a set of Th17-specific HIV dependency factors (HDFs): PARG, PAK2, KLF2, ITGB7, PTEN, ATG16L1, Alix/AIP1/PDCD6IP, LGALS3, JAK1, TRIM8, MALT1, FOXO3, ARNTL/BMAL1, ABCB1/MDR1, TNFSF13B/BAFF, and CDKN1B. Functional studies demonstrated an increased ability of Th17 versus Th1 cells to respond to TCR triggering in terms of NF-κB nuclear translocation/DNA-binding activity and proliferation. Finally, RNA interference studies identified MAP3K4 and PTPN13 as two novel Th17-specific HDFs.

CONCLUSIONS

The transcriptional program of Th17 cells includes molecules regulating HIV replication at multiple post-entry steps that may represent potential targets for novel therapies aimed at protecting Th17 cells from infection and subsequent depletion in HIV-infected subjects.