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In exploring persistent infections and malignancies, a distinctive subgroup of CD8+ T cells, progenitor exhausted CD8+ T (Tpex) cells, has been identified. These Tpex cells are notable for their remarkable self-renewal and rapid proliferation abilities. Recent strides in immunotherapy have demonstrated that Tpex cells expand and differentiate into responsive exhausted CD8+ T cells, thus underscoring their critical role in the immunotherapeutic retort. Clinical examinations have further clarified a robust positive correlation between the proportional abundance of Tpex cells and enhanced clinical prognosis. Tpex cells have found noteworthy applications in the formulation of inventive immunotherapeutic approaches against tumors. This review describes the functions of Tpex cells in the tumor milieu, particularly their potential utility in tumor immunotherapy. Precisely directing Tpex cells may be essential to achieving successful outcomes in immunotherapy against tumors.

Abstract Background Epigenetic remodeling at effector gene loci has been reported to be critical in regulating T cell differentiation and function. However, efforts to investigate underlying epigenetic mechanisms that control T cell behaviors have been largely hindered by very limited experimental tools, especially in humans. Results In this study, we employed a flow cytometric assay to analyze histone acetylation at single-cell level in human T cells. The data showed that histone acetylation was increased during T cell activation. Among T cell subsets, terminally differentiated effector memory T (TEMRA) cells robustly producing effector cytokines were hyper-acetylated. Conversely, these TEMRA cells had lower expression levels of TCF-1, a key transcription factor for maintaining stem cell features. Pharmaceutical inhibition of histone acetylation using a small molecule C646 restrained the production of effector molecules, but retained stem cell-like properties in T cells after expansion. Conclusions Per-cell histone acetylation is associated with terminal differentiation and poor stemness in human T cells. These observations suggest a new approach to enhance the stem cell-like properties of T cells and improve the efficacy of immunotherapy.

Background: Epigenetic remodeling at effector gene loci has been reported to be critical in regulating T cell differentiation and function. However, efforts to investigate underlying epigenetic mechanisms that control T cell behaviors have been largely hindered by very limited experimental tools, especially in humans. Results: In this study, we employed a flow cytometric assay to analyze histone acetylation at single-cell level in human T cells. The data showed that histone acetylation was increased during T cell activation. Among T cell subsets, terminally differentiated effector memory T (TEMRA) cells robustly producing effector cytokines were hyper-acetylated. Conversely, these TEMRA cells had lower expression levels of TCF-1, a key transcription factor for maintaining stem cell features. Pharmaceutical inhibition of histone acetylation using a small molecule C646 restrained the production of effector molecules, but retained stem cell-like properties in T cells after expansion. Conclusions: Per-cell histone acetylation is associated with terminal differentiation and poor stemness in human T cells. These observations suggest a new approach to enhance the stem cell-like properties of T cells and improve the efficacy of immunotherapy. [ABSTRACT FROM AUTHOR]

ABSTRACTThe immunocytokine PD1-IL2v was designed to overcome liabilities and improve efficacy of IL-2 therapies. PD1-IL2v preferentially targets PD-1+ T-cells and acts on antigen-specific stem-like PD-1+ TCF-1+ CD8+ T-cells expanding and differentiating them towards better effectors resulting in superior efficacy in LCMV chronic infection and tumor models compared to checkpoint inhibition.

Cytotoxic T lymphocyte (CTL) responses against tumors are maintained by stem-like memory cells that self-renew but also give rise to effector-like cells. The latter gradually lose their anti-tumor activity and acquire an epigenetically fixed, hypofunctional state, leading to tumor tolerance. Here, we show that the conversion of stem-like into effector-like CTLs involves a major chemotactic reprogramming that includes the upregulation of chemokine receptor CXCR6. This receptor positions effector-like CTLs in a discrete perivascular niche of the tumor stroma that is densely occupied by CCR7+ dendritic cells (DCs) expressing the CXCR6 ligand CXCL16. CCR7+ DCs also express and trans-present the survival cytokine interleukin-15 (IL-15). CXCR6 expression and IL-15 trans-presentation are critical for the survival and local expansion of effector-like CTLs in the tumor microenvironment to maximize their anti-tumor activity before progressing to irreversible dysfunction. These observations reveal a cellular and molecular checkpoint that determines the magnitude and outcome of anti-tumor immune responses.

Cancer immunotherapy relies on improving T cell effector functions against malignancies, but despite the identification of several key transcription factors (TFs), the biological functions of these TFs are not entirely understood. We developed and utilized a novel, clinically relevant murine model to dissect the functional properties of crucial T cell transcription factors during anti-tumor responses. Our data showed that the loss of TCF-1 in CD8 T cells also leads to loss of key stimulatory molecules such as CD28. Our data showed that TCF-1 suppresses surface NKG2D expression on naïve and activated CD8 T cells via key transcriptional factors Eomes and T-bet. Using both in vitro and in vivo models, we uncovered how TCF-1 regulates critical molecules responsible for peripheral CD8 T cell effector functions. Finally, our unique genetic and molecular approaches suggested that TCF-1 also differentially regulates essential kinases. These kinases, including LCK, LAT, ITK, PLC-γ1, P65, ERKI/II, and JAK/STATs, are required for peripheral CD8 T cell persistent function during alloimmunity. Overall, our molecular and bioinformatics data demonstrate the mechanism by which TCF-1 modulated several critical aspects of T cell function during CD8 T cell response to cancer. Summary Figure: TCF-1 is required for persistent function of CD8 T cells but dispensable for anti-tumor response. Here, we have utilized a novel mouse model that lacks TCF-1 specifically on CD8 T cells for an allogeneic transplant model. We uncovered a molecular mechanism of how TCF-1 regulates key signaling pathways at both transcriptomic and protein levels. These key molecules included LCK, LAT, ITK, PLC-γ1, p65, ERK I/II, and JAK/STAT signaling. Next, we showed that the lack of TCF-1 impacted phenotype, proinflammatory cytokine production, chemokine expression, and T cell activation. We provided clinical evidence for how these changes impact GVHD target organs (skin, small intestine, and liver). Finally, we provided evidence that TCF-1 regulates NKG2D expression on mouse naïve and activated CD8 T cells. We have shown that CD8 T cells from TCF-1 cKO mice mediate cytolytic functions via NKG2D. [ABSTRACT FROM AUTHOR]

Regulatory T cells are suppressive immune cells used in various clinical and therapeutic applications. Canonical regulatory T cells express CD4, FOXP3, and CD25, which are considered definitive markers of their regulatory T-cell status when expressed together. However, a subset of noncanonical regulatory T cells expressing only CD4 and FOXP3 have recently been described in some infection contexts. Using a unique mouse model for the first time demonstrated that the TCF-1 regulation of regulatory T-cell suppressive function is not limited to the thymus during development. Our data showed that TCF-1 also regulated regulatory T cells' suppressive ability in secondary organs and graft-vs-host disease target organs as well as upregulating noncanonical regulatory T cells. Our data demonstrated that TCF-1 regulates the suppressive function of regulatory T cells through critical molecules like GITR and PD-1, specifically by means of noncanonical regulatory T cells. Our in vitro approaches show that TCF-1 regulates the regulatory T-cell effector-phenotype and the molecules critical for regulatory T-cell migration to the site of inflammation. Using in vivo models, we show that both canonical and noncanonical regulatory T cells from TCF-1 cKO mice have a superior suppressive function, as shown by their ability to control conventional T-cell proliferation, avert acute graft-vs-host disease, and limit tissue damage. Thus, for the first time, we provide evidence that TCF-1 negatively regulates the suppressive ability of canonical and noncanonical regulatory T cells. These findings provide evidence that TCF-1 is a novel target for developing strategies to treat alloimmune disorders. [ABSTRACT FROM AUTHOR]

CD4+ T cells are typically considered as 'helper' or 'regulatory' populations that support and orchestrate the responses of other lymphocytes. However, they can also develop potent granzyme (Gzm)-mediated cytotoxic activity and CD4+ cytotoxic T cells (CTLs) have been amply documented both in humans and in mice, particularly in the context of human chronic infection and cancer. Despite the established description of CD4+ CTLs, as well as of the critical cytotoxic activity they exert against MHC class II-expressing targets, their developmental and memory maintenance requirements remain elusive. This is at least in part owing to the lack of a murine experimental system where CD4+ CTLs are stably induced. Here, we show that viral and bacterial vectors encoding the same epitope induce distinct CD4+ CTL responses in challenged mice, all of which are nevertheless transient in nature and lack recall properties. Consistent with prior reports, CD4+ CTL differentiation is accompanied by loss of TCF-1 expression, a transcription factor considered essential for memory T cell survival. Using genetic ablation of Tcf7, which encodes TCF-1, at the time of CD4+ T cell activation, we further show that, contrary to observations in CD8+ T cells, continued expression of TCF-1 is not required for CD4+ T cell memory survival. Whilst Tcf7-deficient CD4+ T cells persisted normally following retroviral infection, the CD4+ CTL subset still declined, precluding conclusive determination of the requirement for TCF-1 for murine CD4+ CTL survival. Using xenotransplantation of human CD4+ T cells into murine recipients, we demonstrate that human CD4+ CTLs develop and persist in the same experimental conditions where murine CD4+ CTLs fail to persist. These observations uncover a species-specific defect in murine CD4+ CTL persistence with implications for their use as a model system. [ABSTRACT FROM AUTHOR]

The transcription factor T cell factor-1 (TCF-1) is encoded by Tcf7 and plays a significant role in regulating immune responses to cancer and pathogens. TCF-1 plays a central role in CD4 T cell development; however, the biological function of TCF-1 on mature peripheral CD4 T cell-mediated alloimmunity is currently unknown. This report reveals that TCF-1 is critical for mature CD4 T cell stemness and their persistence functions. Our data show that mature CD4 T cells from TCF-1 cKO mice did not cause graft versus host disease (GvHD) during allogeneic CD4 T cell transplantation, and donor CD4 T cells did not cause GvHD damage to target organs. For the first time, we showed that TCF-1 regulates CD4 T cell stemness by regulating CD28 expression, which is required for CD4 stemness. Our data showed that TCF-1 regulates CD4 effector and central memory formation. For the first time, we provide evidence that TCF-1 differentially regulates key chemokine and cytokine receptors critical for CD4 T cell migration and inflammation during alloimmunity. Our transcriptomic data uncovered that TCF-1 regulates critical pathways during normal state and alloimmunity. Knowledge acquired from these discoveries will enable us to develop a target-specific approach for treating CD4 T cell-mediated diseases. [ABSTRACT FROM AUTHOR]

CD4+ T cells are typically considered as ‘helper’ or ‘regulatory’ populations that support and orchestrate the responses of other lymphocytes. However, they can also develop potent granzyme (Gzm)-mediated cytotoxic activity and CD4+ cytotoxic T cells (CTLs) have been amply documented both in humans and in mice, particularly in the context of human chronic infection and cancer. Despite the established description of CD4+ CTLs, as well as of the critical cytotoxic activity they exert against MHC class II-expressing targets, their developmental and memory maintenance requirements remain elusive. This is at least in part owing to the lack of a murine experimental system where CD4+ CTLs are stably induced. Here, we show that viral and bacterial vectors encoding the same epitope induce distinct CD4+ CTL responses in challenged mice, all of which are nevertheless transient in nature and lack recall properties. Consistent with prior reports, CD4+ CTL differentiation is accompanied by loss of TCF-1 expression, a transcription factor considered essential for memory T cell survival. Using genetic ablation of Tcf7, which encodes TCF-1, at the time of CD4+ T cell activation, we further show that, contrary to observations in CD8+ T cells, continued expression of TCF-1 is not required for CD4+ T cell memory survival. Whilst Tcf7-deficient CD4+ T cells persisted normally following retroviral infection, the CD4+ CTL subset still declined, precluding conclusive determination of the requirement for TCF-1 for murine CD4+ CTL survival. Using xenotransplantation of human CD4+ T cells into murine recipients, we demonstrate that human CD4+ CTLs develop and persist in the same experimental conditions where murine CD4+ CTLs fail to persist. These observations uncover a species-specific defect in murine CD4+ CTL persistence with implications for their use as a model system.

Liver X receptor (LXR) is a critical regulator of cholesterol homeostasis that inhibits T cell receptor (TCR)-induced proliferation by altering intracellular sterol metabolism. However, the mechanisms by which LXR regulates helper T cell subset differentiation remain unclear. Here, we demonstrate that LXR is a crucial negative regulator of follicular helper T (Tfh) cells in vivo. Both mixed bone marrow chimera and antigen-specific T cell adoptive cotransfer studies show a specific increase in Tfh cells among LXRβdeficient CD4+ T cell population in response to immunization and lymphocytic choriomeningitis mammarenavirus (LCMV) infection. Mechanistically, LXRβ-deficient Tfh cells express augmented levels of T cell factor 1 (TCF-1) but comparable levels of Bcl6, CXCR5, and PD-1 in comparison with those of LXRβ-sufficient Tfh cells. Loss of LXRβ confers inactivation of GSK3β induced by either AKT/Extracellular signal-regulated kinase (ERK) activation or Wnt/β-catenin pathway, leading to elevated TCF-1 expression in CD4+ T cells. Conversely, ligation of LXR represses TCF-1 expression and Tfh cell differentiation in both murine and human CD4+ T cells. LXR agonist significantly diminishes Tfh cells and the levels of antigen-specific IgG upon immunization. These findings unveil a cell-intrinsic regulatory function of LXR in Tfh cell differentiation via the GSK3β-TCF1 pathway, which may serve as a promising target for pharmacological intervention in Tfh-mediated diseases. [ABSTRACT FROM AUTHOR]

During chronic antigen exposure, a subset of exhausted CD8+ T cells differentiate into stem cell-like or progenitor-like T cells expressing both transcription factor Tcf-1 (T cell factor-1) and co-inhibitory receptor PD-1. These Tcf-1+ stem-like or progenitor exhausted T cells represent the key target for immunotherapies. Deeper understanding of the biology of Tcf-1+PD-1+ CD8+ T cells will lead to rational design of future immunotherapies. Here, we summarize recent findings about the migratory and resident behavior of Tcf-1+ T cells. Specifically, we will focus on TGF-b-dependent lymphoid tissue residency program of Tcf-1+ T cells, which may represent a key to understanding the differentiation and maintenance of Tcf-1+ stem-like CD8+ T cells during persistent antigen stimulation. [ABSTRACT FROM AUTHOR]

Background: T-cell longevity is undermined by antigen-driven differentiation programs that render cells prone to attrition through several mechanisms. CD8 + T cells that express the Tcf-1 transcription factor have undergone limited differentiation and exhibit stem-cell-like replenishment functions that facilitate persistence. We engineered human CD8 + T cells to constitutively express Tcf-1 and a TCR specific for the NY-ESO-1 cancer-associated antigen. Co-engineered cells were assessed for their potential for adoptive cellular immunotherapy. Methods: Tcf-1 mRNA encoding TCF-1B and TCF-1E isoforms, along with GzmB expression were assessed in CD62L + CD57 −, CD62L − CD57 −, and CD62L − CD57 + CD8 + T cells derived from normal donor lymphocytes. The impact of stable Tcf-1B expression on CD8 + T-cell phenotype, anti-tumor activity, and cell-cycle activity was assessed in vitro and in an in vivo tumor xenograft model. Results: TCF-1B and TCF-1E were dynamically regulated during self-renewal, with progeny of recently activated naïve T cells more enriched for TCF-1B mRNA. Constitutive TCF-1B expression improved the survival of TCR-engineered CD8 + T cells upon engagement with tumor cells. Tcf-1B prohibited the acquisition of a GzmB High state, and protected T cells from apoptosis associated with elicitation of effector function, and promoted stem cell-like characteristics. Conclusions: Tcf-1 protects TCR-engineered CD8 + T cells from activation induced cell death by restricting GzmB expression. Our study presents constitutive Tcf-1B expression as a potential means to impart therapeutic T cells with attributes of persistence for durable anti-tumor activity. [ABSTRACT FROM AUTHOR]

During chronic antigen exposure, a subset of exhausted CD8+ T cells differentiate into stem cell-like or progenitor-like T cells expressing both transcription factor Tcf-1 (T cell factor-1) and co-inhibitory receptor PD-1. These Tcf-1+ stem-like or progenitor exhausted T cells represent the key target for immunotherapies. Deeper understanding of the biology of Tcf-1+PD-1+ CD8+ T cells will lead to rational design of future immunotherapies. Here, we summarize recent findings about the migratory and resident behavior of Tcf-1+ T cells. Specifically, we will focus on TGF-β-dependent lymphoid tissue residency program of Tcf-1+ T cells, which may represent a key to understanding the differentiation and maintenance of Tcf-1+ stem-like CD8+ T cells during persistent antigen stimulation.

Summary: Background: Harnessing CD8+ T cell responses is being explored to achieve HIV remission. Although HIV-specific CD8+ T cells become dysfunctional without treatment, antiretroviral therapy (ART) partially restores their function. However, the extent of this recovery under long-term ART is less understood. Methods: We analyzed the differentiation status and function of HIV-specific CD8+ T cells after long-term ART initiated in acute or chronic HIV infection ex vivo and upon in vitro recall. Findings: ART initiation in any stage of acute HIV infection promoted the persistence of long-lived HIV-specific CD8+ T cells with high expansion (P

Understanding the mechanisms promoting chromosomal translocations of the rearranging receptor loci in leukemia and lymphoma remains incomplete. Here we show that leukemias induced by aberrant activation of ß-catenin in thymocytes, which bear recurrent Tcra/Myc-Pvt1 translocations, depend on Tcf-1. The DNA double strand breaks (DSBs) in the Tcra site of the translocation are Rag-generated, whereas the Myc-Pvt1 DSBs are not. Aberrantly activated ß-catenin redirects Tcf-1 binding to novel DNA sites to alter chromatin accessibility and down-regulate genome-stability pathways. Impaired homologous recombination (HR) DNA repair and replication checkpoints lead to retention of DSBs that promote translocations and transformation of double-positive (DP) thymocytes. The resulting lymphomas, which resemble human T cell acute lymphoblastic leukemia (T-ALL), are sensitive to PARP inhibitors (PARPis). Our findings indicate that aberrant ß-catenin signaling contributes to translocations in thymocytes by guiding Tcf-1 to promote the generation and retention of replication-induced DSBs allowing their coexistence with Rag-generated DSBs. Thus, PARPis could offer therapeutic options in hematologic malignancies with activeWnt/ß-catenin signaling. [ABSTRACT FROM AUTHOR]

Exhausted CD8+ T (Tex) cells are a distinct cell population that arise during persistent antigen exposure in the context of chronic infections and cancers. Although characterized by progressive loss of effector functions, high and sustained inhibitory receptor expression and distinct transcriptional and epigenetic programs, Tex cells are heterogeneous. Among these, a self-renewing TCF-1+ Tex population, having unique characteristics and the ability to respond to immune-checkpoint blockade, gives rise to TCF-1-terminally Tex cells. These TCF-1+ cells have stem cell-like properties similar to memory T cell populations, but the signals that regulate the developmental pathways and relationships among exhausted cell populations are still unclear. Here, we review our current understanding of Tex cell biology, and discuss some less appreciated molecules and pathways affecting T cell exhaustion. We highlight two co-stimulatory receptors, CD226 and CD137, and their role in inducing or restraining T cell exhaustion, as well as signaling pathways that may be amenable to pharmacological inhibition with a focus on Phosphoinositide-3 Kinase and IL-2 partial agonists. Finally, we discuss novel methods that may increase TCF-1+ populations and therefore improve immunotherapy responsiveness. Understanding features of and pathways to exhaustion has important implications for the success of immunotherapy, including checkpoint blockade and adoptive T-cell transfer therapies. [ABSTRACT FROM AUTHOR]

Exhausted CD8+ T (Tex) cells are a distinct cell population that arise during persistent antigen exposure in the context of chronic infections and cancers. Although characterized by progressive loss of effector functions, high and sustained inhibitory receptor expression and distinct transcriptional and epigenetic programs, Tex cells are heterogeneous. Among these, a self-renewing TCF-1+ Tex population, having unique characteristics and the ability to respond to immune-checkpoint blockade, gives rise to TCF-1- terminally Tex cells. These TCF-1+ cells have stem cell-like properties similar to memory T cell populations, but the signals that regulate the developmental pathways and relationships among exhausted cell populations are still unclear. Here, we review our current understanding of Tex cell biology, and discuss some less appreciated molecules and pathways affecting T cell exhaustion. We highlight two co-stimulatory receptors, CD226 and CD137, and their role in inducing or restraining T cell exhaustion, as well as signaling pathways that may be amenable to pharmacological inhibition with a focus on Phosphoinositide-3 Kinase and IL-2 partial agonists. Finally, we discuss novel methods that may increase TCF-1+ populations and therefore improve immunotherapy responsiveness. Understanding features of and pathways to exhaustion has important implications for the success of immunotherapy, including checkpoint blockade and adoptive T-cell transfer therapies.

The immunocytokine PD1-IL2v was designed to overcome liabilities and improve efficacy of IL-2 therapies. PD1-IL2v preferentially targets PD-1+ T-cells and acts on antigen-specific stem-like PD-1+ TCF-1+ CD8+ T-cells expanding and differentiating them towards better effectors resulting in superior efficacy in LCMV chronic infection and tumor models compared to checkpoint inhibition. [ABSTRACT FROM AUTHOR]

The transcription factor T cell factor-1 (TCF-1) is encoded by Tcf7 and plays a significant role in regulating immune responses to cancer and pathogens. TCF-1 plays a central role in CD4 T cell development; however, the biological function of TCF-1 on mature peripheral CD4 T cell-mediated alloimmunity is currently unknown. This report reveals that TCF-1 is critical for mature CD4 T cell stemness and their persistence functions. Our data show that mature CD4 T cells from TCF-1 cKO mice did not cause graft versus host disease (GvHD) during allogeneic CD4 T cell transplantation, and donor CD4 T cells did not cause GvHD damage to target organs. For the first time, we showed that TCF-1 regulates CD4 T cell stemness by regulating CD28 expression, which is required for CD4 stemness. Our data showed that TCF-1 regulates CD4 effector and central memory formation. For the first time, we provide evidence that TCF-1 differentially regulates key chemokine and cytokine receptors critical for CD4 T cell migration and inflammation during alloimmunity. Our transcriptomic data uncovered that TCF-1 regulates critical pathways during normal state and alloimmunity. Knowledge acquired from these discoveries will enable us to develop a target-specific approach for treating CD4 T cell-mediated diseases.

The immune checkpoint blockade (ICB) response in human cancers is closely linked to the gut microbiota. Here, we report that the abundance of commensal Lactobacillus johnsonii is positively correlated with the responsiveness of ICB. Supplementation with Lactobacillus johnsonii or tryptophan-derived metabolite indole-3-propionic acid (IPA) enhances the efficacy of CD8+ T cell-mediated αPD-1 immunotherapy. Mechanistically, Lactobacillus johnsonii collaborates with Clostridium sporogenes to produce IPA. IPA modulates the stemness program of CD8+ T cells and facilitates the generation of progenitor exhausted CD8+ T cells (T pex) by increasing H3K27 acetylation at the super-enhancer region of Tcf7. IPA improves ICB responsiveness at the pan-cancer level, including melanoma, breast cancer, and colorectal cancer. Collectively, our findings identify a microbial metabolite-immune regulatory pathway and suggest a potential microbial-based adjuvant approach to improve the responsiveness of immunotherapy. [Display omitted] • L. johnsonii enhances ICB efficacy via CD8+ T cells • L. johnsonii cooperates with C. sporogenes to produce IPA • IPA activates progenitor exhausted CD8+ T cells by H3K27 acetylation modification • IPA improves ICB responsiveness at the pan-cancer level L. johnsonii and C. sporogenes collaborate to produce indole-3-propionic acid, which modulates CD8+ T cell stemness by increasing H3K27 acetylation at the Tcf7 super-enhancer, thereby enhancing the anti-tumor effect of immune checkpoint blockade in pan-cancer. [ABSTRACT FROM AUTHOR]

T cell factor‐1 (TCF‐1) (encoded by the TCF7 gene) is a transcription factor that plays important role during the T cell development and differentiation for T cell to exercise its functions including producing memory T cells. Not only TCF‐1 can modulate the T cell development but also exerts various effects on the differentiation and function of mature CD8+ T cells. In addition, it drives the production and maintenance of the immune response of CD8+ T cells after PD‐1 checkpoint blockade therapy. TCF‐1 can serve as a potential target of immunotherapy and may provide promising novel treatment strategies for patients with cancer and infections. Moreover, TCF‐1 is a potential biomarker of CD8+ T cell functionality to predict the efficacy of immunotherapy in fighting against cancer and infections. Herein, we summarize the role of TCF‐1 in T cell development and its applications in the treatment of cancer and infectious diseases. [ABSTRACT FROM AUTHOR]

The kinase PDK1 is a crucial regulator for immune cell development by connecting PI3K to downstream AKT signaling. However, the roles of PDK1 in CD4+ T cell differentiation, especially in T follicular helper (Tfh) cell, remain obscure. Here we reported PDK1 intrinsically promotes the Tfh cell differentiation and germinal center responses upon acute infection by using conditional knockout mice. PDK1 deficiency in T cells caused severe defects in both early differentiation and late maintenance of Tfh cells. The expression of key Tfh regulators was remarkably downregulated in PDK1-deficient Tfh cells, including Tcf7, Bcl6, Icos, and Cxcr5. Mechanistically, ablation of PDK1 led to impaired phosphorylation of AKT and defective activation of mTORC1, resulting in substantially reduced expression of Hif1α and p-STAT3. Meanwhile, decreased p-AKT also suppresses mTORC2-associated GSK3β activity in PDK1-deficient Tfh cells. These integrated effects contributed to the dramatical reduced expression of TCF1 and ultimately impaired the Tfh cell differentiation.

The inhibitory receptor TIGIT, as well as theectonucleotidases CD39 and CD73 constitute potential exhaustion markers for T cells. Detailed analysis of these markers can shed light into dysregulation of the T-cell response in acute myeloid leukemia (AML) and will help to identify potential therapeutic targets. The phenotype and expression of transcription factors was assessed on different T-cell populations derived from peripheral blood (PB, n = 38) and bone marrow (BM, n = 43). PB and BM from patients with AML diagnosis, in remission and at relapse were compared with PB from healthy volunteers (HD) (n = 12) using multiparameter flow cytometry. An increased frequency of terminally differentiated (CD45R−CCR7−)CD8+ T cells was detected in PB and BM regardless of the disease state. Moreover, we detected an increased frequency of two distinct T-cell populations characterized by the co-expression of PD-1 or CD39 on TIGIT+CD73−CD8+ T cells in newly diagnosed and relapsed AML in comparison to HDs. In contrast to the PD-1+TIGIT+CD73−CD8+ T-cell population, the frequency of CD39+TIGIT+CD73−CD8+ T cells was normalized in remission. PD-1+- and CD39+TIGIT+CD73−CD8+ T cells exhibited additional features of exhaustion by decreased expression of CD127 and TCF-1 and increased intracellular expression of the transcription factor TOX. CD8+ T cells in AML exhibit a key signature of two subpopulations, PD-1+TOX+TIGIT+CD73−CD8+- and CD39+TOX+TIGIT+CD73−CD8+ T cells that were increased at different stages of the disease. These results provide a rationale to analyze TIGIT blockade in combination with inhibition of the purinergic signaling and depletion of TOX to improve T-cell mediated cytotoxicity in AML. Abbreviations: AML: Acute myeloid leukemia; pAML: newly diagnosed AML; rAML: relapse AML; lrAML: AML in remission; HD: healthy donor; PB: peripheral blood; BM: bone marrow; TIGIT: T-cell immunoreceptor with Ig and ITIM domains; PD-1: Programmed cell death protein 1; CD73: ecto-5′-nucleotidase; CD39: ectonucleoside triphosphate diphosphohydrolase 1; ATP: adenosine triphosphate; ADO: adenosine; CD127: interleukin-7 receptor; CAR-T cell: chimeric antigen receptor T cell; TCF-1: transcription factor T-cell factor 1; TOX: Thymocyte selection-associated high mobility group box protein; NFAT: nuclear factor of activated T cells; NA: Naïve; CM: Central Memory; EM Effector Memory; EMRA: Terminal Effector Memory cells; FMO: Fluorescence minus one; PVR: poliovirus receptor; PVRL2: poliovirus receptor-related 2; IFN-γ: Interferon-γ; IL-2: interleukin-2; MCF: multiparametric flow cytometry; TNFα: Tumornekrosefaktor α; RT: room temperature.

The inhibitory receptor TIGIT, as well as theectonucleotidases CD39 and CD73 constitute potential exhaustion markers for T cells. Detailed analysis of these markers can shed light into dysregulation of the T-cell response in acute myeloid leukemia (AML) and will help to identify potential therapeutic targets. The phenotype and expression of transcription factors was assessed on different T-cell populations derived from peripheral blood (PB, n = 38) and bone marrow (BM, n = 43). PB and BM from patients with AML diagnosis, in remission and at relapse were compared with PB from healthy volunteers (HD) (n = 12) using multiparameter flow cytometry. An increased frequency of terminally differentiated (CD45R-CCR7-)CD8+ T cells was detected in PB and BM regardless of the disease state. Moreover, we detected an increased frequency of two distinct T-cell populations characterized by the co-expression of PD-1 or CD39 on TIGIT+CD73-CD8- T cells in newly diagnosed and relapsed AML in comparison to HDs. In contrast to the PD-1+TIGIT+CD73-CD8+ T-cell population, the frequency of CD39+TIGIT+CD73-CD8+ T cells was normalized in remission. PD-1+- and CD39+TIGIT+CD73-CD8+ T cells exhibited additional features of exhaustion by decreased expression of CD127 and TCF-1 and increased intracellular expression of the transcription factor TOX. CD8+ T cells in AML exhibit a key signature of two subpopulations, PD-1+TOX+TIGIT+CD73-CD8+- and CD39+TOX+TIGIT+CD73-CD8+ T cells that were increased at different stages of the disease. These results provide a rationale to analyze TIGIT blockade in combination with inhibition of the purinergic signaling and depletion of TOX to improve T-cell mediated cytotoxicity in AML. [ABSTRACT FROM AUTHOR]

In exploring persistent infections and malignancies, a distinctive subgroup of CD8 + T cells, progenitor exhausted CD8 + T (Tpex) cells, has been identified. These Tpex cells are notable for their remarkable self-renewal and rapid proliferation abilities. Recent strides in immunotherapy have demonstrated that Tpex cells expand and differentiate into responsive exhausted CD8 + T cells, thus underscoring their critical role in the immunotherapeutic retort. Clinical examinations have further clarified a robust positive correlation between the proportional abundance of Tpex cells and enhanced clinical prognosis. Tpex cells have found noteworthy applications in the formulation of inventive immunotherapeutic approaches against tumors. This review describes the functions of Tpex cells in the tumor milieu, particularly their potential utility in tumor immunotherapy. Precisely directing Tpex cells may be essential to achieving successful outcomes in immunotherapy against tumors., Competing Interests: No potential conflicts of interest are disclosed., (Copyright: © 2024, The Authors.)

The transcription factor TCF-1 (encoded by Tcf7) plays critical roles in several lineages of hematopoietic cells. In this study, we examined the molecular basis for Tcf7 regulation in T cells, innate lymphoid cells, and migratory conventional dendritic cells that we find express Tcf7. We identified a 1 kb regulatory element crucial for the initiation of Tcf7 expression in T cells and innate lymphoid cells, but dispensable for Tcf7 expression in Tcf7-expressing dendritic cells. Within this region, we identified a Notch binding site important for the initiation of Tcf7 expression in T cells but not in innate lymphoid cells. Our work establishes that the same regulatory element is used by distinct transcriptional controllers to initiate Tcf7 expression in T cells and ILCs.

Osteosarcoma (OS) is the most common bone tumor that occurs predominantly in children and teenagers. Although many genes, such as p53 and Rb1, have been shown to be mutated, deregulation of the canonical Wnt/β‐catenin signaling pathway is frequently observed in OS. We recently demonstrated that heat shock protein 90 (HSP90) is involved in the regulation of runt‐related transcription factor 2 via the AKT/GSK‐3β/β‐catenin signaling pathway in OS. However, the precise role of T cell factors/lymphoid enhancer‐binding factor (TCFs/LEF) family members, which are the major binding complex of β‐catenin, in OS is poorly understood. In the present study, we first demonstrated that TCF‐1 is overexpressed in OS compared with other bone tumors. Knockdown of TCF‐1 significantly induced cell cycle arrest, severe DNA damage, and subsequent caspase‐3‐dependent apoptosis. Interestingly, coexpression of HSP90 and TCF‐1 was observed in OS, and mechanistically, we demonstrated that TCF‐1 expression is regulated by HSP90 either through a β‐catenin‐dependent mechanism or a direct degradation of the proteasome. We also found that overexpression of TCF‐1 partially abolishes the apoptosis induced by HSP90 inhibition. Furthermore, we provided evidence that p53, but not miR‐34a, plays a crucial role in the HSP90‐regulated TCF‐1 expression and subsequent apoptosis. Given the diverse combination regimens of HSP90 inhibition with some other treatments, we propose that the p53 status and the expression level of TCF‐1 should be taken into consideration to enhance the therapeutic efficacy of HSP90 inhibition. [ABSTRACT FROM AUTHOR]

Constitutive activation of the Wnt/beta-catenin pathway has been implicated as the primary cause of colon cancer. However, the major transducers of Wnt signaling in the intestine, T-cell factor 1 (TCF-1) and TCF-4, have opposing functions. Knockout of TCF-4 suppresses growth and maintenance of crypt stem cells, whereas knockout of TCF-1 leads to adenomas. These phenotypes suggest that TCF-4 is Wnt-promoting, whereas TCF-1 acts like a tumor suppressor. Our study of TCF expression in human colon crypts reveals a mechanistic basis for this paradox. In normal colon cells, a dominant-negative isoform of TCF-1 (dnTCF-1) is expressed that is equally distributed between nuclear and cytoplasmic compartments. In colon cancer cells, TCF-1 is predominantly cytoplasmic. Localization is because of active nuclear export and is directed by an autocrine-acting Wnt ligand that requires Ca2+/calmodulin-dependent kinase II (CaMKII) activity for secretion and a downstream step in the export pathway. TCF-4 remains nuclear; its unopposed activity is accompanied by downregulation of dnTCF-1 and increased expression of full-length isoforms. Thus, the dnTCF-1 and TCF-4 balance is corrupted in cancer by two mechanisms, a Wnt/CaMKII kinase signal for nuclear export and decreased dnTCF-1 expression. We propose that dnTCF-1 provides homeostatic regulation of Wnt signaling and growth in normal colon, and the alterations in nuclear export and promoter usage contribute to aberrant Wnt activity in colon cancer.

T cell factor-1 (TCF-1), encoded by Tcf7 , is a transcription factor and histone deacetylase (HDAC) essential for commitment to both the T cell and the innate lymphoid cell (ILC) lineages in mammals. In this review, we discuss the multifunctional role of TCF-1 in establishing these lineages and the requirement for TCF-1 throughout lineage differentiation and maintenance of lineage stability. We highlight recent reports showing promise for TCF-1 as a novel biomarker to identify recently characterized subsets of exhausted CD8+ T cells that may help to predict patient responses to immune checkpoint blockade (ICB). T cell factor-1 (TCF-1) acts as a transcription factor and histone deacetylase (HDAC) in both mouse and humans to shape innate and adaptive immunity. Expression of TCF-1 is necessary for the development of ILC progenitor cells in mouse bone marrow. In murine T cell development, TCF-1 is critical for ETP development, commitment to the CD4+ T cell lineage, and stabilization of CD8+ T cells by suppressing alternative fate differentiation. Increased TCF-1 expression is important for the development of central memory CD8+ T cells that provide long-term protection following acute viral infection in mice. TCF-1 is critical for the development of Tex-stem cells that replenish Tex-term cells following chronic viral infection and in response to tumor formation. The presence of Tex-stem cells can be predictive of good prognosis in various cancer types and help to mediate patient responses to ICB. [ABSTRACT FROM AUTHOR]

Lymphoid Enhancer Factor-1 (LEF-1) is a member of a family of transcription factors that function as downstream mediators of the Wnt signal transduction pathway. In the absence of Wnt signals, specific LEF/TCF isoforms repress rather than activate gene targets through recruitment of the co-repressor CtBP. Characterization of the full-length human LEF-1 gene locus and its complete set of mRNA products shows that this family member exists as a unique set of alternatively spliced isoforms; none are homologous to TCF-1E/TCF-4E. Therefore LEF-1 is distinct from its TCF family members in that it cannot engage in activities specific to this isoform such as recruitment of the co-repressor CtBP. Expression of alternatively spliced LEF-1 isoforms are driven by a promoter that is highly active in lymphocyte cell lines. Transcription initiates within a TATA-less core promoter region that contains consensus binding sites for Sp1, an E box, an Initiator element and a LEF/TCF binding site, all juxtaposed to the start sites of transcription. The promoter is most active in a B lymphocyte cell line (Raji) in which the endogenous LEF-1 gene is silent, suggesting that the promoter region is actively repressed by a silencing mechanism.

Lymphoid tissue inducer (LTi) cells, a subset of innate lymphoid cells (ILCs), play an essential role in the formation of secondary lymphoid tissues. However, the regulation of the development and functions of this ILC subset is still elusive. In this study, we report that the transcription factor T cell factor 1 (TCF-1), just as GATA3, is indispensable for the development of non-LTi ILC subsets. While LTi cells are still present in TCF-1-deficient mice, the organogenesis of Peyer's patches (PPs), but not of lymph nodes, is impaired in these mice. LTi cells from different tissues have distinct gene expression patterns, and TCF-1 regulates the expression of lymphotoxin specifically in PP LTi cells. Mechanistically, TCF-1 may directly and/or indirectly regulate Lta , including through promoting the expression of GATA3. Thus, the TCF-1-GATA3 axis, which plays an important role during T cell development, also critically regulates the development of non-LTi cells and tissue-specific functions of LTi cells. [Display omitted] • TCF-1 is required for LTi's function selectively in Peyer's patch (PP) formation • TCF-1 promotes optimal expression of lymphotoxin and GATA3 in PP LTi cells • LTi cells from PPs and small intestine laminal propria (siLP) are transcriptionally distinct • TCF-1 negatively regulates IL-17 expression in siLP LTi cells Zheng et al. show that TCF-1 regulates the functions, but not the development, of LTi cells in different tissues. It is specifically required for optimal expression of lymphotoxin in LTi cells from Peyer's patches and inhibits IL-17 production by LTi cells from small intestine laminal propria. [ABSTRACT FROM AUTHOR]

T cell factor 1 (Tcf-1) expressing CD8+ T cells exhibit stem-like self-renewing capacity, rendering them key for immune defense against chronic viral infection and cancer. Yet, the signals that promote the formation and maintenance of these stem-like CD8+ T cells (CD8+SL) remain poorly defined. Studying CD8+ T cell differentiation in mice with chronic viral infection, we identified the alarmin interleukin-33 (IL-33) as pivotal for the expansion and stem-like functioning of CD8+SL as well as for virus control. IL-33 receptor (ST2)-deficient CD8+ T cells exhibited biased end differentiation and premature loss of Tcf-1. ST2-deficient CD8+SL responses were restored by blockade of type I interferon signaling, suggesting that IL-33 balances IFN-I effects to control CD8+SL formation in chronic infection. IL-33 signals broadly augmented chromatin accessibility in CD8+SL and determined these cells' re-expansion potential. Our study identifies the IL-33-ST2 axis as an important CD8+SL-promoting pathway in the context of chronic viral infection. [Display omitted] • Interleukin-33 (IL-33) promotes the expansion of stem-like CD8 T cells (CD8+SL) • IL-33 signals augment chromatin accessibility of CD8+SL in chronic viral infection • IL-33 prevents the loss of Tcf-1 expression by balancing type I interferon effects • IL-33 signaling to CD8+SL preserves these cells' stemness and re-expansion capacity Stem-like Tcf-1-expressing CD8 T cells (CD8+SL) are key to immune defense in chronic infection and cancer, but the cytokine signals that promote CD8+SL cell expansion and stemness remain undefined. Marx et al. reveal that interleukin-33 assumes this role by balancing type I interferon signals and augmenting chromatin accessibility of CD8+SL. [ABSTRACT FROM AUTHOR]

In allogeneic hematopoietic stem cell transplantation, donor αβ T cells attack recipient tissues, causing graft-versus-host disease (GVHD), a major cause of morbidity and mortality. A central question has been how GVHD is sustained despite T cell exhaustion from chronic antigen stimulation. The current model for GVHD holds that disease is maintained through the continued recruitment of alloreactive effectors from blood into affected tissues. Here, we show, using multiple approaches including parabiosis of mice with GVHD, that GVHD is instead primarily maintained locally within diseased tissues. By tracking 1,203 alloreactive T cell clones, we fitted a mathematical model predicting that within each tissue a small number of progenitor T cells maintain a larger effector pool. Consistent with this, we identified a tissue-resident TCF-1+ subpopulation that preferentially engrafted, expanded, and differentiated into effectors upon adoptive transfer. These results suggest that therapies targeting affected tissues and progenitor T cells within them would be effective. [Display omitted] • During early GVHD, alloreactive T cell clones enter target tissues broadly but unevenly • Late-phase GVHD is maintained within affected tissues with only minor input from blood • Tissue-resident TCF-1+ T cells maintain effector cells within most affected tissues Alloreactive T cells cause graft-versus-host disease (GVHD), but how GVHD is maintained once established is unclear. Using T cell clone tracking, parabiosis of GVHD mice and computational modeling, Sacirbegovic et al. demonstrate that progenitor-like T cells within affected tissues maintain GVHD locally, mostly independent of blood-derived T cells. [ABSTRACT FROM AUTHOR]

CD4 + T cells are typically considered as 'helper' or 'regulatory' populations that support and orchestrate the responses of other lymphocytes. However, they can also develop potent granzyme (Gzm)-mediated cytotoxic activity and CD4 + cytotoxic T cells (CTLs) have been amply documented both in humans and in mice, particularly in the context of human chronic infection and cancer. Despite the established description of CD4 + CTLs, as well as of the critical cytotoxic activity they exert against MHC class II-expressing targets, their developmental and memory maintenance requirements remain elusive. This is at least in part owing to the lack of a murine experimental system where CD4 + CTLs are stably induced. Here, we show that viral and bacterial vectors encoding the same epitope induce distinct CD4 + CTL responses in challenged mice, all of which are nevertheless transient in nature and lack recall properties. Consistent with prior reports, CD4 + CTL differentiation is accompanied by loss of TCF-1 expression, a transcription factor considered essential for memory T cell survival. Using genetic ablation of Tcf7 , which encodes TCF-1, at the time of CD4 + T cell activation, we further show that, contrary to observations in CD8 + T cells, continued expression of TCF-1 is not required for CD4 + T cell memory survival. Whilst Tcf7 -deficient CD4 + T cells persisted normally following retroviral infection, the CD4 + CTL subset still declined, precluding conclusive determination of the requirement for TCF-1 for murine CD4 + CTL survival. Using xenotransplantation of human CD4 + T cells into murine recipients, we demonstrate that human CD4 + CTLs develop and persist in the same experimental conditions where murine CD4 + CTLs fail to persist. These observations uncover a species-specific defect in murine CD4 + CTL persistence with implications for their use as a model system., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Hofland, Danelli, Cornish, Donnarumma, Hunt, de Carvalho and Kassiotis.)

Background: Fingolimod (FTY720), the first oral treatment for multiple sclerosis (MS), blocks immune cell trafficking and prevents disease relapses by downregulation of sphingosine-1-phosphate receptor. We determined the effect of FTY720 on human T cell activation and effector function.Methods: T cells from MS patients and healthy controls were isolated to measure gene expression profiles in the presence or absence of FTY720 using nanostring and quantitative real-time polymerase chain reaction (qPCR). Cytokine protein expression was measured using luminex assay and flow cytometry analysis. Lentivirus vector carrying short hairpin RNA (shRNA) was used to knock down the expression of specific genes in CD4+ T cells. Chromatin immunoprecipitation was performed to assess T cell factor 1 (TCF-1) binding to promoter regions. Luciferase assays were performed to test the direct regulation of interferon gamma (IFN-γ) and granzyme B (GZMB) by TCF-1. Western blot analysis was used to assess the phosphorylation status of Akt and GSK3β.Results: We showed that FTY720 treatment not only affects T cell trafficking but also T cell activation. Patients treated with FTY720 showed a significant reduction in circulating CD4 T cells. Activation of T cells in presence of FTY720 showed a less inflammatory phenotype with reduced production of IFN-γ and GZMB. This decreased effector phenotype of FTY720-treated T cells was dependent on the upregulation of TCF-1. FTY720-induced TCF-1 downregulated the pathogenic cytokines IFN-γ and GZMB by binding to their promoter/enhancer regions and mediating epigenetic modifications. Furthermore, we observed that TCF-1 expression was lower in T cells from multiple sclerosis patients than in those from healthy individuals, and FTY720 treatment increased TCF-1 expression in multiple sclerosis patients.Conclusions: These results reveal a previously unknown mechanism of the effect of FTY720 on human CD4+ T cell modulation in multiple sclerosis and demonstrate the role of TCF-1 in human T cell activation and effector function. [ABSTRACT FROM AUTHOR]

Liver X receptor (LXR) is a critical regulator of cholesterol homeostasis that inhibits T cell receptor (TCR)-induced proliferation by altering intracellular sterol metabolism. However, the mechanisms by which LXR regulates helper T cell subset differentiation remain unclear. Here, we demonstrate that LXR is a crucial negative regulator of follicular helper T (Tfh) cells in vivo. Both mixed bone marrow chimera and antigen-specific T cell adoptive cotransfer studies show a specific increase in Tfh cells among LXRβ-deficient CD4 + T cell population in response to immunization and lymphocytic choriomeningitis mammarenavirus (LCMV) infection. Mechanistically, LXRβ-deficient Tfh cells express augmented levels of T cell factor 1 (TCF-1) but comparable levels of Bcl6, CXCR5, and PD-1 in comparison with those of LXRβ-sufficient Tfh cells. Loss of LXRβ confers inactivation of GSK3β induced by either AKT/Extracellular signal-regulated kinase (ERK) activation or Wnt/β-catenin pathway, leading to elevated TCF-1 expression in CD4 + T cells. Conversely, ligation of LXR represses TCF-1 expression and Tfh cell differentiation in both murine and human CD4 + T cells. LXR agonist significantly diminishes Tfh cells and the levels of antigen-specific IgG upon immunization. These findings unveil a cell-intrinsic regulatory function of LXR in Tfh cell differentiation via the GSK3β-TCF1 pathway, which may serve as a promising target for pharmacological intervention in Tfh-mediated diseases.

Lung disease is the major cause of death and hospitalization worldwide. Transcription factors such as transcription factor 7 (TCF7) are involved in the pathogenesis of lung diseases. TCF7 is important for T cell development and differentiation, embryonic development, or tumorogenesis. Multiple TCF7 isoforms can be characterized by the full-length isoform (FL-TCF7) as a transcription activator, or dominant negative isoform (dn-TCF7) as a transcription repressor. TCF7 interacts with multiple proteins or target genes and participates in several signal pathways critical for lung diseases. TCF7 is involved in pulmonary infection, allergy or asthma through promoting T cells differentiating to Th2 or memory T cells. TCF7 also works in tissue repair and remodeling after acute lung injury. The dual roles of TCF7 in lung cancers were discussed and it is associated with the cellular proliferation, invasion or metastasis. Thus, TCF7 plays critical roles in lung diseases and should be considered as a new therapeutic target. [ABSTRACT FROM AUTHOR]

During chronic antigen exposure, a subset of exhausted CD8 + T cells differentiate into stem cell-like or progenitor-like T cells expressing both transcription factor Tcf-1 (T cell factor-1) and co-inhibitory receptor PD-1. These Tcf-1 + stem-like or progenitor exhausted T cells represent the key target for immunotherapies. Deeper understanding of the biology of Tcf-1 + PD-1 + CD8 + T cells will lead to rational design of future immunotherapies. Here, we summarize recent findings about the migratory and resident behavior of Tcf-1 + T cells. Specifically, we will focus on TGF-β-dependent lymphoid tissue residency program of Tcf-1 + T cells, which may represent a key to understanding the differentiation and maintenance of Tcf-1 + stem-like CD8 + T cells during persistent antigen stimulation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ma and Zhang.)

The differentiation of innate lymphoid cells (ILCs) from hematopoietic stem cells needs to go through several multipotent progenitor stages. However, it remains unclear whether the fates of multipotent progenitors are predefined by epigenetic states. Here, we report the identification of distinct accessible chromatin regions in all lymphoid progenitors (ALPs), EILPs, and ILC precursors (ILCPs). Single-cell MNase-seq analyses revealed that EILPs contained distinct subpopulations epigenetically primed toward either dendritic cell lineages or ILC lineages. We found that TCF-1 and GATA3 co-bound to the lineage-defining sites for ILCs (LDS-Is), whereas PU.1 binding was enriched in the LDSs for alternative dendritic cells (LDS-As). TCF-1 and GATA3 were indispensable for the epigenetic priming of LDSs at the EILP stage. Our results suggest that the multipotency of progenitor cells is defined by the existence of a heterogeneous population of cells epigenetically primed for distinct downstream lineages, which are regulated by key transcription factors. • Thousands of LDSs are detected during EILP differentiation • EILPs contain distinct subpopulations epigenetically primed for different cell fates • TCF-1 and GATA3 co-bind to a large fraction of LDSs for ILC differentiation • TCF-1 and GATA3 are indispensable for the epigenetic priming of LDSs at the EILP stage EILPs have multiple lineage potentials toward either myeloid or ILC lineages, but the role of epigenetic modifications in the cell-fate decision is presently unclear. Ren et al. reveal that EILPs contain distinct epigenetically primed subpopulations, which are dependent on the presence of transcription factors TCF-1 and GATA3. [ABSTRACT FROM AUTHOR]

• High-dose radiation can improve mouse survival through regulating the T cells stemness in tumor micro-environment. • This paper is the first time proposed that radiation can enhance the expression of TCF-1 + T cells through cGAS/STING axis. • The study provides evidence for the rational combination of radiation and STING agonists. Radiotherapy is a very effective cancer treatment, mainly through inducing DNA damage of cancer cells. Meanwhile, there is evidence that irradiation can also mobilize tumor-specific immunity, and recent investigations demonstrate that the efficiency of local high-dose radiotherapy is attributable to the presence of CD8+T cells. Here, we observed that high-dose radiation remarkably increased the enrichment of stem cell-like CD8+T cells. Moreover, cGAS/STING signaling augmented stem cell-like CD8+T cells and T stem-like central memory CD8+T cells in a mice tumor model after radiation. These findings raise our understanding of stem cell-like CD8+T cells after radiation stimulation and improve radiation therapy by driving the cGAS/STING signaling pathway for cancer multimodality therapy. [ABSTRACT FROM AUTHOR]

Wnt signaling regulates small intestinal stem cell maintenance and Paneth cell differentiation. In patients with ileal Crohn's disease (CD), a decrease of Paneth cell α-defensins has been observed that is partially caused by impaired TCF-4 and LRP6 function. Here we show reduced expression of the Wnt signaling effector TCF-1 (also known as TCF-7) in patients with ileal CD. Reporter gene assays and in vitro promoter binding analysis revealed that TCF-1 activates α-defensin HD-5 and HD-6 transcription in cooperation with β-catenin and that activation is mediated by three distinct TCF binding sites. EMSA analysis showed binding of TCF-1 to the respective motifs. In ileal CD patients, TCF-1 mRNA expression levels were significantly reduced. Moreover, we found specifically reduced expression of active TCF-1 mRNA isoforms. Tcf-1 knockout mice exhibited reduced cryptdin expression in the jejunum, which was not consistently seen at other small intestinal locations. Our data provide evidence that TCF-1-mediated Wnt signaling is disturbed in small intestinal CD, which might contribute to the observed barrier dysfunction in the disease. [ABSTRACT FROM AUTHOR]

Background: Harnessing CD8 + T cell responses is being explored to achieve HIV remission. Although HIV-specific CD8 + T cells become dysfunctional without treatment, antiretroviral therapy (ART) partially restores their function. However, the extent of this recovery under long-term ART is less understood., Methods: We analyzed the differentiation status and function of HIV-specific CD8 + T cells after long-term ART initiated in acute or chronic HIV infection ex vivo and upon in vitro recall., Findings: ART initiation in any stage of acute HIV infection promoted the persistence of long-lived HIV-specific CD8 + T cells with high expansion (P<0·0008) and cytotoxic capacity (P=0·02) after in vitro recall, albeit at low cell number (P=0·003). This superior expansion capacity correlated with stemness (r=0·90, P=0·006), measured by TCF-1 expression, similar to functional HIV-specific CD8 + T cells found in spontaneous controllers. Importanly, TCF-1 expression in these cells was associated with longer time to viral rebound ranging from 13 to 48 days after ART interruption (r =0·71, P=0·03). In contrast, ART initiation in chronic HIV infection led to more differentiated HIV-specific CD8 + T cells lacking stemness properties and exhibiting residual dysfunction upon recall, with reduced proliferation and cytolytic activity., Interpretation: ART initiation in acute HIV infection preserves functional HIV-specific CD8 + T cells, albeit at numbers too low to control viral rebound post-ART. HIV remission strategies may need to boost HIV-specific CD8 + T cell numbers and induce stem cell-like properties to reverse the residual dysfunction persisting on ART in people treated after acute infection prior to ART release., Funding: U.S. National Institutes of Health and U.S. Department of Defense., Competing Interests: Declaration of interests All the other authors declare that they have no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Aims/hypothesis: HNF1A-MODY is a monogenic form of diabetes caused by mutations in the HNF1A gene. Here we identify, for the first time, HNF1A-MODY-associated microRNAs (miRNAs) that can be detected in the serum of HNF1A-MODY carriers. Methods: An miRNA array was carried out in rat INS-1 insulinoma cells inducibly expressing the common human Pro291fsinsC-HNF1A frame shift mutation. Differentially expressed miRNAs were validated by quantitative real-time PCR. Expression of miRNAs in the serum of HNF1A-MODY carriers ( n = 31), MODY-negative family members ( n = 10) and individuals with type 2 diabetes mellitus ( n = 17) was quantified by absolute real-time PCR analysis. Results: Inducible expression of Pro291fsinsC-HNF1A in INS-1 cells caused a significant upregulation of three miRNAs (miR-103, miR-224, miR-292-3p). The differential expression of two miRNAs (miR-103 and miR-224) was validated in vitro. Strongly elevated levels of miR-103 and miR-224 could be detected in the serum of HNF1A-MODY carriers compared with MODY-negative family controls. Serum levels of miR-103 distinguished HNF1A-MODY carriers from HbA-matched individuals with type 2 diabetes mellitus. Conclusions/interpretation: Our study demonstrates that the pathophysiology of HNF1A-MODY is associated with the overexpression of miR-103 and miR-224. Furthermore, our study demonstrates that these miRNAs can be readily detected in the serum of HNF1A-MODY carriers. [ABSTRACT FROM AUTHOR]