搜索结果: 'gmp t cell activator'

Despite the clinical success of cancer immunotherapies,the majority of patients fail to respond or develop resistance through disruption of pathways that promote neo-antigen presentation on MHC I molecules. Here,we conducted a series of unbiased,genome-wide CRISPR/Cas9 screens to identify genes that limit natural killer (NK) cell anti-tumor activity. We identified that genes associated with antigen presentation and/or interferon-$\gamma$ (IFN-$\gamma$) signaling protect tumor cells from NK cell killing. Indeed,Jak1-deficient melanoma cells were sensitized to NK cell killing through attenuated NK cell-derived IFN-$\gamma$-driven transcriptional events that regulate MHC I expression. Importantly,tumor cells that became resistant to T cell killing through enrichment of MHC I-deficient clones were highly sensitive to NK cell killing. Taken together,we reveal the genes targeted by tumor cells to drive checkpoint blockade resistance but simultaneously increase their vulnerability to NK cells,unveiling NK cell-based immunotherapies as a strategy to antagonize tumor immune escape. View Publication

A proposed strategy to cure HIV uses latency-reversing agents (LRAs) to reactivate latent proviruses for purging HIV reservoirs. A variety of LRAs have been identified,but none has yet proven effective in reducing the reservoir size in vivo. Nanocarriers could address some major challenges by improving drug solubility and safety,providing sustained drug release,and simultaneously delivering multiple drugs to target tissues and cells. Here,we formulated hybrid nanocarriers that incorporate physicochemically diverse LRAs and target lymphatic CD4+ T cells. We identified one LRA combination that displayed synergistic latency reversal and low cytotoxicity in a cell model of HIV and in CD4+ T cells from virologically suppressed patients. Furthermore,our targeted nanocarriers selectively activated CD4+ T cells in nonhuman primate peripheral blood mononuclear cells as well as in murine lymph nodes,and substantially reduced local toxicity. This nanocarrier platform may enable new solutions for delivering anti-HIV agents for an HIV cure. View Publication

T cell activation is predicated on the interaction between the T cell receptor and peptide-major histocompatibility (pMHC) ligands. The factors that determine the stimulatory potency of a pMHC molecule remain unclear. We describe results showing that a peptide exhibiting many hallmarks of a weak agonist stimulates T cells to proliferate more than the wild-type agonist ligand. An in silico approach suggested that the inability to form the central supramolecular activation cluster (cSMAC) could underlie the increased proliferation. This conclusion was supported by experiments that showed that enhancing cSMAC formation reduced stimulatory capacity of the weak peptide. Our studies highlight the fact that a complex interplay of factors determines the quality of a T cell antigen. View Publication

Upon infection,antigen-specific naive CD8 T cells are activated and differentiate into short-lived effector cells (SLECs) and memory precursor cells (MPECs). The underlying signaling pathways remain largely unresolved. We show that Rictor,the core component of mammalian target of rapamycin complex 2 (mTORC2),regulates SLEC and MPEC commitment. Rictor deficiency favors memory formation and increases IL-2 secretion capacity without dampening effector functions. Moreover,mTORC2-deficient memory T cells mount more potent recall responses. Enhanced memory formation in the absence of mTORC2 was associated with Eomes and Tcf-1 upregulation,repression of T-bet,enhanced mitochondrial spare respiratory capacity,and fatty acid oxidation. This transcriptional and metabolic reprogramming is mainly driven by nuclear stabilization of Foxo1. Silencing of Foxo1 reversed the increased MPEC differentiation and IL-2 production and led to an impaired recall response of Rictor KO memory T cells. Therefore,mTORC2 is a critical regulator of CD8 T cell differentiation and may be an important target for immunotherapy interventions. View Publication

CD4 and CD8 T lymphocyte activation requires the generation of sufficient energy to support new biosynthetic demands. Following T cell receptor (TCR) engagement,these requirements are met by an increased glycolysis,due,at least in part,to induction of the Glut1 glucose transporter. As Glut1 is upregulated on tumor cells in response to hypoxia,we assessed whether surface Glut1 levels regulate the antigen responsiveness of human T lymphocytes in both hypoxic and atmospheric oxygen conditions. Notably,Glut1 upregulation in response to TCR stimulation was significantly higher in T lymphocytes activated under hypoxic as compared to atmospheric oxygen conditions. Furthermore,TCR-stimulated human T lymphocytes sorted on the basis of Glut1-Lo and Glut1-Hi profiles maintained distinct characteristics,irrespective of the oxygen tension. While T cells activated in hypoxia divided less than those activated in atmospheric oxygen,Glut1-Hi lymphocytes exhibited increased effector phenotype acquisition,augmented proliferation,and an inverted CD4/CD8 ratio in both oxygen conditions. Moreover,Glut1-Hi T lymphocytes exhibited a significantly enhanced ability to produce IFN-γ and this secretion potential was completely dependent on continued glycolysis. Thus,Glut1 surface levels identify human T lymphocytes with distinct effector functions in both hypoxic and atmospheric oxygen tensions. View Publication

Chemokine receptors on T cells are frequently categorized as functioning either in immune system homeostasis within lymphoid organs,or in peripheral inflammation. CXCR3 is in the latter category and is reported to be expressed selectively on Th1 cells. We found that CXCR3 was expressed in vivo on newly activated tonsillar CD4(+) T cells. Using CD4(+) T cells from cord blood,we found that CXCR3 was induced by cellular activation in vitro independently of the cytokine milieu,although on resting cells,expression was maintained preferentially on those that had been activated in type 1 conditions. In inflamed tonsils,CXCR3(+)CD4(+) T cells were localized around and within germinal centers. The inference that CXCR3 has a role in germinal center reactions was supported by the finding that the CXCR3 ligand CXC chemokine ligand 9 was expressed in a pattern demarcating a subset of germinal centers both in tonsil and in lymph nodes from an HIV-infected individual. We next investigated the role of CXCR3 on peripheral effector/memory CD4(+) T cells by comparing its pattern of expression with that of CCR5,another Th1-cell associated chemokine receptor. Analysis of cells directly from peripheral blood and after activation in vitro suggested that CXCR3 expression preceded that of CCR5,supporting a model of sequential induction of chemokine receptors during CD4(+) T cell differentiation. Taken together,our data show that CXCR3 can be expressed at all stages of CD4(+) T cell activation and differentiation,bridging central function in lymphoid organs and effector function in peripheral tissues. View Publication

Accumulating evidence suggests elements within tumors induce exhaustion of effector T cells and infiltration of immunosuppressive regulatory T cells (Tregs),thus preventing the development of durable antitumor immunity. Therefore,the discovery of agents that simultaneously block Treg suppressive function and reinvigorate effector function of lymphocytes is key to the development of effective cancer immunotherapy. Previous studies have shown that TLR ligands (TLRLs) could modulate the function of these T cell targets; however,those studies relied on cell-free or accessory cell-based assay systems that do not accurately reflect in vivo responses. In contrast,we used a human PBMC-based proliferation assay system to simultaneously monitor the effect of TLRLs on T cells (CD4(+),CD8(+),Tregs),B cells,and NK cells,which gave different and even conflicting results. We found that the TLR7/8L:CL097 could simultaneously activate CD8(+) T cells,B cells,and NK cells plus block Treg suppression of T cells and B cells. The TLRLs TLR1/2L:Pam3CSK4,TLR5L:flagellin,TLR4L:LPS,and TLR8/7L:CL075 also blocked Treg suppression of CD4(+) or CD8(+) T cell proliferation,but not B cell proliferation. Besides CL097,TLR2L:PGN,CL075,and TLR9L:CpG-A,CpG-B,and CpG-C) were strong activators of NK cells. Importantly,we found that Pam3CSK4 could: 1) activate CD4(+) T cell proliferation,2) inhibit the expansion of IL-10(+) naturally occurring FOXP3(+) Tregs and induction of IL-10(+) CD4(+) Tregs (IL-10-producing type 1 Treg),and 3) block naturally occurring FOXP3(+) Tregs suppressive function. Our results suggest these agents could serve as adjuvants to enhance the efficacy of current immunotherapeutic strategies in cancer patients. View Publication

The incidence of human papillomavirus (HPV)-related head and neck squamous cell carcinoma has increased in recent decades,though HPV prevention vaccines may reduce this rise in the future. HPV-related cancers express the viral oncoproteins E6 and E7. The latter inactivates the tumor suppressor protein retinoblastoma (Rb),which leads to the overexpression of p16(INK4) protein,providing unique Ags for therapeutic HPV-specific cancer vaccination. We developed potential adenoviral vaccines that express a fusion protein of HPV-16 E6 and E7 (Ad.E6E7) alone or fused with p16 (Ad.E6E7p16) and also encoding an anti-programmed death (PD)-1 Ab. Human monocyte-derived dendritic cells (DC) transduced with Ad.E6E7 or Ad.E6E7p16 with or without Ad.αPD1 were used to activate autologous CD8 CTL in vitro. CTL responses were tested against naturally HPV-infected head and neck squamous cell carcinoma cells using IFN-γ ELISPOT and [(51)Cr]release assay. Surprisingly,stimulation and antitumor activity of CTL were increased after incubation with Ad.E6E7p16-transduced DC (DC.E6E7p16) compared with Ad.E6E7 (DC.E6E7),a result that may be due to an effect of p16 on cyclin-dependent kinase 4 levels and IL-12 secretion by DC. Moreover,the beneficial effect was most prominent when anti-PD-1 was introduced during the second round of stimulation (after initial priming). These data suggest that careful sequencing of Ad.E6E7.p16 with Ad.αPD1 could improve antitumor immunity against HPV-related tumors and that p16 may enhance the immunogenicity of DC,through cyclin-dependent pathways,Th1 cytokine secretion,and by adding a nonviral Ag highly overexpressed in HPV-induced cancers. View Publication

Cancer immunotherapy restores or enhances the effector function of CD8+ T cells in the tumour microenvironment1,2. CD8+ T cells activated by cancer immunotherapy clear tumours mainly by inducing cell death through perforin-granzyme and Fas-Fas ligand pathways3,4. Ferroptosis is a form of cell death that differs from apoptosis and results from iron-dependent accumulation of lipid peroxide5,6. Although it has been investigated in vitro7,8,there is emerging evidence that ferroptosis might be implicated in a variety of pathological scenarios9,10. It is unclear whether,and how,ferroptosis is involved in T cell immunity and cancer immunotherapy. Here we show that immunotherapy-activated CD8+ T cells enhance ferroptosis-specific lipid peroxidation in tumour cells,and that increased ferroptosis contributes to the anti-tumour efficacy of immunotherapy. Mechanistically,interferon gamma (IFNgamma) released from CD8+ T cells downregulates the expression of SLC3A2 and SLC7A11,two subunits of the glutamate-cystine antiporter system xc-,impairs the uptake of cystine by tumour cells,and as a consequence,promotes tumour cell lipid peroxidation and ferroptosis. In mouse models,depletion of cystine or cysteine by cyst(e)inase (an engineered enzyme that degrades both cystine and cysteine) in combination with checkpoint blockade synergistically enhanced T cell-mediated anti-tumour immunity and induced ferroptosis in tumour cells. Expression of system xc- was negatively associated,in cancer patients,with CD8+ T cell signature,IFNgamma expression,and patient outcome. Analyses of human transcriptomes before and during nivolumab therapy revealed that clinical benefits correlate with reduced expression of SLC3A2 and increased IFNgamma and CD8. Thus,T cell-promoted tumour ferroptosis is an anti-tumour mechanism,and targeting this pathway in combination with checkpoint blockade is a potential therapeutic approach. View Publication

Heterologous immunity is recognized as a significant barrier to transplant tolerance. Whereas it has been established that pathogen-elicited memory T cells can have high or low affinity for cross-reactive allogeneic peptide-MHC,the role of TCR affinity during heterologous immunity has not been explored. We established a model with which to investigate the impact of TCR-priming affinity on memory T cell populations following a graft rechallenge. In contrast to high-affinity priming,low-affinity priming elicited fully differentiated memory T cells with a CD45RB(hi) status. High CD45RB status enabled robust secondary responses in vivo,as demonstrated by faster graft rejection kinetics and greater proliferative responses. CD45RB blockade prolonged graft survival in low affinity-primed mice,but not in high affinity-primed mice. Mechanistically,low affinity-primed memory CD8(+) T cells produced more IL-2 and significantly upregulated IL-2Rα expression during rechallenge. We found that CD45RB(hi) status was also a stable marker of priming affinity within polyclonal CD8(+) T cell populations. Following high-affinity rechallenge,low affinity-primed CD45RB(hi) cells became CD45RB(lo),demonstrating that CD45RB status acts as an affinity-based differentiation switch on CD8(+) T cells. Thus,these data establish a novel mechanism by which CD45 isoforms tune low affinity-primed memory CD8(+) T cells to become potent secondary effectors following heterologous rechallenge. These findings have direct implications for allogeneic heterologous immunity by demonstrating that despite a lower precursor frequency,low-affinity priming is sufficient to generate memory cells that mediate potent secondary responses against a cross-reactive graft challenge. View Publication

Regulatory T cells (Tregs) are crucial immune cells for tissue repair and regeneration. However,their potential as a cell-based regenerative therapy is not yet fully understood. Here,we show that local delivery of exogenous Tregs into injured mouse bone,muscle,and skin greatly enhances tissue healing. Mechanistically,exogenous Tregs rapidly adopt an injury-specific phenotype in response to the damaged tissue microenvironment,upregulating genes involved in immunomodulation and tissue healing. We demonstrate that exogenous Tregs exert their regenerative effect by directly and indirectly modulating monocytes/macrophages (Mo/MΦ) in injured tissues,promoting their switch to an anti-inflammatory and pro-healing state via factors such as interleukin (IL)-10. Validating the key role of IL-10 in exogenous Treg-mediated repair and regeneration,the pro-healing capacity of these cells is lost when Il10 is knocked out. Additionally,exogenous Tregs reduce neutrophil and cytotoxic T cell accumulation and IFN-γ production in damaged tissues,further dampening the pro-inflammatory Mo/MΦ phenotype. Highlighting the potential of this approach,we demonstrate that allogeneic and human Tregs also promote tissue healing. Together,this study establishes exogenous Tregs as a possible universal cell-based therapy for regenerative medicine and provides key mechanistic insights that could be harnessed to develop immune cell-based therapies to enhance tissue healing. Regulatory T cells (Tregs) are known for suppressing inflammatory processes,but their full capacity for tissue regeneration is yet to be harnessed. Here,the authors demonstrate the efficiency of Tregs in facilitating tissue healing in mouse models of bone,muscle,and skin injury,with monocytes/macrophages and interleukin-10 playing a key mechanistic role in the process. View Publication

Iron is an irreplaceable co-factor for metabolism. Iron deficiency affects >1 billion people and decreased iron availability impairs immunity. Nevertheless,how iron deprivation impacts immune cell function remains poorly characterised. We interrogate how physiologically low iron availability affects CD8+ T cell metabolism and function,using multi-omic and metabolic labelling approaches. Iron limitation does not substantially alter initial post-activation increases in cell size and CD25 upregulation. However,low iron profoundly stalls proliferation (without influencing cell viability),alters histone methylation status,gene expression,and disrupts mitochondrial membrane potential. Glucose and glutamine metabolism in the TCA cycle is limited and partially reverses to a reductive trajectory. Previous studies identified mitochondria-derived aspartate as crucial for proliferation of transformed cells. Despite aberrant TCA cycling,aspartate is increased in stalled iron deficient CD8+ T cells but is not utilised for nucleotide synthesis,likely due to trapping within depolarised mitochondria. Exogenous aspartate markedly rescues expansion and some functions of severely iron-deficient CD8+ T cells. Overall,iron scarcity creates a mitochondrial-located metabolic bottleneck,which is bypassed by supplying inhibited biochemical processes with aspartate. These findings reveal molecular consequences of iron deficiency for CD8+ T cell function,providing mechanistic insight into the basis for immune impairment during iron deficiency. Iron has been shown to be necessary for the activation and differentiation of CD8+ T cells. Here the authors investigate changes in CD8+ T cell metabolism in iron limiting conditions and find that aspartate is increased yet downstream nucleotide synthesis is suppressed and addition of exogenous aspartate partially rescues T cell function. View Publication