Project description:Depleting the NURF chromatin remodeling complex results in enhanced antitumor immunity using mouse tumor models syngenic to two strain backgrounds. Selective depletion of immune cells from tumor-bearing mice discovers that both CD8+ and CD4+ cells are necessary for enhanced antitumor immunity to NURF-depleted cells. Our results suggest that NURF-depleted cells have significant differences in antigenicity compared to control cells.
Project description:Here, we elucidate a critical microbial-host crosstalk between probiotic-released aryl hydrocarbon receptor (AhR) agonist indole-3-aldehyde (I3A) and CD8 T cells within the tumor microenvironment that potently enhances spontaneous antitumor immunity and facilitates ICI therapy in preclinical melanoma. We used single cell RNA sequencing to phenotype CD8+ T cells within tumors of L. reuteri -treated or untreated mice.
Project description:The activation of TLR-MyD88 (Toll like receptor- Myeloid differentiation factor 88) signaling within T cells functions as a potent costimulatory signal that boosts antitumor and antiviral responses. However, the molecular mechanisms underlying the costimulatory processes are poorly understood. We compared microarray gene analysis data between TLR1-TLR2 stimulated and unstimulated T cell receptor transgenic âpmelâ and MyD88-/-pmel CD8+ T cells and identified changes in the expression levels of several TNF family members. In particular, TLR-stimulation increased 4-1BB levels in pmel but not in MyD88-/-pmel T cells. A link between 4-1BB and TLR1-TLR2 signaling in CD8+ T cells was highlighted by in fact that 4-1BB-/- T cells exhibited suboptimal responses to TLR1-TLR2 agonist, but responded normally to CD28 or OX40 costimulation. Moreover, blocking 4-1BB signaling with antibodies also hindered the costimulatory effects of the TLR1-TLR2 agonist. The elevated levels of 4-1BB transcripts in TLR1-TLR2âstimulated cells were not due to increased mRNA stability nor increased histone activation but instead were associated with increased binding of p65 and c-Jun to two distinct 4-1BB promoter sites. Combining TLR1-TLR2 ligand with an agonistic anti-4-1BB antibody enhanced the antitumor activity in mice with established melanoma tumors. These studies reveal that the costimulatory effects of TLR1-TLR2 signaling in CD8+ T cells are in part mediated by 4-1BB and are important for mounting an effective antitumor immune response. CD8+ T cells from the B6.Cg-Thy1/Cy Tg(TcraTcrb)8Rest/J mice, referred to as âpmelâ T cells or from MyD88 knockout pmel mice (MyD88â/âpmel) were sorted. pmel and MyD88â/âpmel T cells were activated using MyD88â/â CD8 T cell-depleted splenocytes pulsed with 10ng/ml of mgp100. This was with or without 10µg/ml of Pam3CSK4. pmel or MyD88â/âpmel CD8 T cells were enriched and used for the extraction of RNA used for genomic analysis.
Project description:RIG-I is a pattern recognition receptor involved in innate immunity, but its role in adaptive immunity remains unclear. Here, we demonstrate that RIG-I is upregulated in tumor infiltrating CD8+ T cells, where it functions as an intracellular checkpoint to negatively regulate CD8+ T cell function and limit antitumor immunity. Mechanically, up-regulation of RIG-I in CD8+ T cells is induced by retinoic acid (RA), a metabolite of vitamin A in TME, and direct inhibits the AKT/glycolysis signaling pathway. In addition, deletion of RIG-I enhances the efficacy of adoptively transferred T cells against solid tumors and inhibition of RIG-I enhances the response to PD-1 blockade. Our findings identify RIG-I as an intracellular checkpoint and a potential target for alleviating inhibitory constraints on T cells in cancer immunotherapy, either alone or in combination with immune checkpoint blockade.
Project description:<p>Plasmacytoid dendritic cells (pDC) are a subset of dendritic cells with unique immunophenotypic properties and functions. While their role in antiviral immunity through production of type I interferons is well-established, their contributions to anti-tumor immunity are less clear. While some evidence demonstrates that pDC in the tumor microenvironment (TME) may drive CD4+ T cell to become <a href="https://www.ncbi.nlm.nih.gov/gene/50943">Foxp3</a>+ T regulatory cells, little is understood about the relationship of pDC with cytotoxic CD8+ T cell, the key player in antitumor immune responses.</p> <p>In this study, we perform comprehensive immunophenotyping and functional analysis of pDC from the TME and draining lymph nodes of patients with head and neck squamous cell carcinoma (HNSCC) and identify a novel pDC subset characterized by expression of the TNF receptor superfamily member <a href="https://www.ncbi.nlm.nih.gov/gene/?term=7293">CD134 (OX40)</a>. We show that OX40 expression is expressed on intratumoral pDC in both humans and mice in a tumor-model specific fashion and that this subset of pDC enhances tumor associated-antigen (TAA)-specific CD8+ T cell responses. Through transcriptomic profiling of OX40-expressing pDC from the TME, we further characterize gene signatures unique to this pDC subset that support its role as an important immunostimulatory immune population in the TME.</p>
Project description:We report an in situ vaccination, adaptable to nearly any type of cancer, that combines radiotherapy targeting one tumor and intratumoral injection of this site with tumor-specific antibody and interleukin-2 (IL-2; 3xTx). In a phase I clinical trial, administration of 3xTx (with an immunocytokine fusion of tumor-specific antibody and IL-2, hu14.18-IL2) to subjects with metastatic melanoma increases peripheral CD8+ T cell effector polyfunctionality. This suggests the potential for 3xTx to promote antitumor immunity against metastatic tumors. In poorly immunogenic syngeneic murine melanoma or head and neck carcinoma models, 3xTx stimulates CD8+ T cell-mediated antitumor responses at targeted and non-targeted tumors. During 3xTx treatment, natural killer (NK) cells promote CTLA4+ regulatory T cell (Treg) apoptosis in non-targeted tumors. This is dependent on NK cell expression of CD86, which is upregulated downstream of KLRK1. NK cell depletion increases Treg infiltration, diminishing CD8+ T cell-dependent antitumor response. These findings demonstrate that NK cells sustain and propagate CD8+ T cell immunity following 3xTx
Project description:MAVS-mediated cytosolic RNA sensing plays a central role in tumor immunogenicity. However, the effects of host MAVS signaling on antitumor immunity remains uncertain. Here, we demonstrate that host MAVS pathway drives accelerated tumor growth and impairs antitumor immunity, while MAVS knockout in dendritic cells (DCs) promotes tumor-reactive CD8+ T cell responses. Specifically, the CD8+ T cell priming capacity is enhanced by lack of functional MAVS in a type I interferon-independent, but IL-12-dependent, manner. Mechanistically, loss of RIG-I/MAVS cascade activates non-canonical NF-κB pathway and in turn induces IL-12 production by DCs, resulting in CD8+ T cell: DC crosstalk licensed by IFN-γ and IL-12. Moreover, ablation of host MAVS sensitizes tumors to immunotherapy and attenuates radiation resistance, thereby facilitating the maintenance of effector CD8+ T cells. These findings identify that host MAVS pathway acts as an immune checkpoint of DC-driven antitumor immunity, indicating the development of DC-based immunotherapies through MAVS signaling antagonism.
Project description:Taurine is a supplement used to bolster immunity, but how taurine affects antitumor immunity remains largely unknown. We report that SLC6A6-mediated uptake of taurine by gastric cancer (GC) cells results in T cell exhaustion and cancer progression. SLC6A6 was correlated with GC aggressiveness and poor outcomes, and taurine uptake increased GC proliferation, survival, and cell motility. Taurine significantly increased CD8+ T cell infiltration and cytotoxic effector expression in GC tumors. Mechanistically, taurine deprivation in CD8+ T cells increased ER stress and the unfolded protein response, resulting in AT4 transcription, which acts as a switch for T cell exhaustion. SLC6A6 was transactivated by SP1 in GC cells, with a strong correlation between SP1 and SLC6A6 in GC patients. The SP1-SLC6A6 axis was triggered by chemotherapy. Our findings reveal that SLC6A6-mediated taurine consumption impacts immune evasion and propose that taurine supplementation might reinvigorate CD8+ T cell response and enhance therapy efficacy.
Project description:Here we report a new way to reverse the tolerant state of adoptively transferred CD8+ T cells against melanoma through ex vivo expansion with the TLR9 agonist CpG. CpG-generated T cells elicited potent immunity without co-administration of high dose IL-2 or vaccination, which are adjuvants classically required to effectively treat solid tumors. CpG-expanded T cells exhibited an IL-2RhighICOShighCD39low phenotype ex vivo and engrafted robustly in vivo. In culture, B cells were the only cell type essential for imprinting T cells with this phenotype and potent tumor immunity. CpG agonists targeting B cells, but not dendritic cells, generated CD8+ T cell products with remarkable antitumor properties. Purified B cells were sufficient to mediate the CpG-associated changes in T cells. These findings reveal a vital role for B cells in the generation of effective antitumor T cells and have immediate implications for profoundly improving immunotherapy for patients.