Disturbed mitochondrial dynamics in CD8+ TIL reinforce epigenetic programming linked with T cell exhaustion
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ABSTRACT: The metabolic challenges present in tumors attenuate the metabolic fitness and anti-tumor activity of tumor-infiltrating T lymphocytes (TILs). However, it remains unclear whether persistent metabolic insufficiency can imprint permanent T cell dysfunction. We found that TILs accumulating depolarized mitochondria as a result of declined mitophagy activity display functional, transcriptomic and epigenetic characteristics of terminally exhausted T cells. Mechanistically, declined mitochondrial fitness in TILs is induced by the coordination of T cell receptor stimulation, microenvironmental stressors and PD-1 signal. Forcing the accumulation of depolarized mitochondria with pharmacological interventions induces epigenetic reprogramming for terminal exhaustion, indicating that mitochondrial deregulation is indeed a cause – rather than a consequence – of T cell exhaustion. Furthermore, supplementation with nicotinamide riboside enhances T cell mitochondrial fitness and improved responsiveness to anti-PD-1 treatment. Together, our results reveal new insights on how mitochondrial dynamics and quality orchestrate T cell anti-tumor responses and commitment to the exhaustion program.
Project description:The metabolic challenges present in tumors attenuate the metabolic fitness and anti-tumor activity of tumor-infiltrating T lymphocytes (TILs). However, it remains unclear whether persistent metabolic insufficiency can imprint permanent T cell dysfunction. We found that TILs accumulating depolarized mitochondria as a result of declined mitophagy activity display functional, transcriptomic and epigenetic characteristics of terminally exhausted T cells. Mechanistically, declined mitochondrial fitness in TILs is induced by the coordination of T cell receptor stimulation, microenvironmental stressors and PD-1 signal. Forcing the accumulation of depolarized mitochondria with pharmacological interventions induces epigenetic reprogramming for terminal exhaustion, indicating that mitochondrial deregulation is indeed a cause – rather than a consequence – of T cell exhaustion. Furthermore, supplementation with nicotinamide riboside enhances T cell mitochondrial fitness and improved responsiveness to anti-PD-1 treatment. Together, our results reveal new insights on how mitochondrial dynamics and quality orchestrate T cell anti-tumor responses and commitment to the exhaustion program.
Project description:The metabolic challenges present in tumors attenuate the metabolic fitness and anti-tumor activity of tumor-infiltrating T lymphocytes (TILs). However, it remains unclear whether persistent metabolic insufficiency can imprint permanent T cell dysfunction. We found that TILs accumulating depolarized mitochondria as a result of declined mitophagy activity display functional, transcriptomic and epigenetic characteristics of terminally exhausted T cells. Mechanistically, declined mitochondrial fitness in TILs is induced by the coordination of T cell receptor stimulation, microenvironmental stressors and PD-1 signal. Forcing the accumulation of depolarized mitochondria with pharmacological interventions induces epigenetic reprogramming for terminal exhaustion, indicating that mitochondrial deregulation is indeed a cause – rather than a consequence – of T cell exhaustion. Furthermore, supplementation with nicotinamide riboside enhances T cell mitochondrial fitness and improved responsiveness to anti-PD-1 treatment. Together, our results reveal new insights on how mitochondrial dynamics and quality orchestrate T cell anti-tumor responses and commitment to the exhaustion program.
Project description:The local mechanisms regulating exhaustion of tumor-infiltrating lymphocytes (TILs) and responsiveness to PD-1 blockade remain partly elucidated. In human ovarian cancer we show that tumor-reactive intraepithelial (ie)CD8+ TILs engaged by antigen are polyfunctional and upregulate PD-1, which restrains their effectiveness. PD-1+ TILs exhibit a continuum of TCR-engaged/exhausted states with variable effector fitness related to CD28 costimulation, which they receive in intraepithelial niches involving myeloid antigen-presenting cells (mAPC). Following PD-1 blockade, activation of TILs requires CD28 costimulation mediated in situ by tumor mAPCs, which is locally enhanced by CTLA-4 blockade. CD40 ligand also amplifies TIL responses in situ, especially in tumors in which mAPCs are not activated. Thus, dysfunctional and exhausted TILs, in a state of TCR engagement but without proper CD28 costimulation by mAPCs in situ, are unlikely to fully benefit from PD-1 blockade.
Project description:Tissue-resident memory CD8+ T cells (Trm) share characteristics and core residency gene programs with tumor-infiltrating lymphocytes (TILs). However, the transcriptional, metabolic and epigenetic regulation of Trm cell and TIL differentiation, maintenance and function are largely undefined. Furthermore, it is unknown whether metabolic and epigenetic manipulations can be employed to promote Trm/TIL functional programs for cancer immunotherapy. Here we report a critical mechanism programming the mitochondrial and epigenetic regulation of Trm/TIL functionality in situ. We found that mouse and human Trm/TIL expressed the transcription factor BHLHE40 and the BHLHE40-associated gene signature. Bhlhe40 was specifically required for Trm and TIL development and polyfunctionality. Local PD-1 signaling inhibited TIL Bhlhe40 expression, and Bhlhe40 was critical for TILs reinvigoration following anti-PD therapy. Mechanistically, Bhlhe40 sustained Trm/TIL mitochondrial fitness for the promotion of a functional epigenetic state. Building on these findings, we also identified an epigenetic and metabolic regimen that promoted Trm/TIL gene signatures associated with tissue residency and poly-functionality through in vitro T cell screening. Strikingly, this regimen empowered the anti-tumor activity of CD8+ T cells and possessed therapeutic potential even at an advanced tumor stage in mouse models. Our results provide mechanistic insights on the local regulation of Trm and TIL function, and offer a viable strategy for developing novel immunotherapeutic means for cancer.
Project description:CD8+ T cells isolated from HCC tissue were divided into three groups: PD1-TIM3- CD8+ TILs, exhibiting full effector function; PD1-intTIM3+ CD8+ TILs, exhibiting partial exhaustion; and PD1-hiTIM3+ CD8+ TILs, exhibiting severe exhaustion, as reflected by the differences in their ability to produce effector cytokines respectively. Transcriptome sequence analysis was performed to investigate the gene expression profile was performed.
Project description:The growing tumor avoids recognition and destruction by immune system. During continuous stimulation of tumor infiltrating lymphocytes (TILs) by tumor, TILs become functionally exhausted. Thus, they become unable to kill tumor cells and to produce some cytokines, and lose their ability to proliferate. It collectively results in the immune escape of cancer cells. Here, we show that breast cancer cells expressing PD-L1 can accelerate exhaustion of persistently activated human effector CD4+ T cells, manifesting in high PD-1 and PD-L1 expression level on cell surface, decreased glucose metabolism genes, strong downregulation of SWI/SNF chromatin remodeling complex subunits and p21 cell cycle inhibitor upregulation. This results in inhibition of T cell proliferation and reduction of T cells number. The RNAseq analysis on exhausted CD4+ T cells indicated strong overexpression of IDO1 and genes encoding pro-inflammatory cytokines and chemokines. The PD-L1 overexpression was also observed in CD4+ T cells after co-cultivation with other cell line overexpressing PD-L1 that suggested the existence of general mechanism of CD4+ T cell exhaustion induced by cancer cells. The ChIP analysis on PD-L1 promoter region indicated that the strong BRM recruitment in control CD4+ T cells is replaced by BRG1 and EZH2 in CD4+ T cells strongly exhausted by cancer cells. These findings suggest that such epi-drugs as EZH2 inhibitors may be used as immunomodulators in cancer treatment.
Project description:Blockade of programmed death-1 (PD-1) reinvigorates exhausted CD8+ T cells, resulting in tumor regression in cancer patients. Recently, reinvigoration of exhausted CD8+ T cells following PD-1 blockade was shown to be CD28-dependent in mouse models. Herein, we examined the role of CD28 in anti-PD-1-induced human T-cell reinvigoration using tumor-infiltrating CD8+ T cells (CD8+ TILs) obtained from non-small cell lung cancer patients. Single cell analysis demonstrated a distinct expression pattern of CD28 between mouse and human CD8+ TILs. Furthermore, we found that human CD28+CD8+, but not CD28–CD8+ TILs, responded to PD-1 blockade irrespective of B7/CD28 blockade, indicating that CD28 co-stimulation in human CD8+ TILs is dispensable for PD-1 blockade-induced reinvigoration, and loss of CD28 expression rather serve as a marker of anti-PD-1-unresponsive CD8+ TILs. Transcriptionally and phenotypically, PD-1 blockade-unresponsive human CD28–PD-1+CD8+ TILs exhibited characteristics of terminally exhausted CD8+ T cells with low TCF1 expression. Notably, CD28–PD-1+CD8+ TILs had preserved machinery to respond to IL-15, and IL-15 treatment enhanced proliferation of CD28–PD-1+CD8+ TILs as well as CD28+PD-1+CD8+ TILs. Taken together, we demonstrate loss of CD28 expression as a marker of PD-1 blockade-unresponsive human CD8+ TILs with TCF1– signature and provide mechanistic insights into combining IL-15 with anti-PD-1.
Project description:T cell metabolic fitness plays a pivotal role in anti-tumor immunity and metabolic deregulation causes T cell dysfunction in cancer. We identify that CD36 limits anti-tumor CD8+ T cell effector functions through lipid peroxidation. In murine tumors, oxidized phospholipids (OxPLs) were highly abundant and CD8+ TILs increased uptake and accumulation of lipids and lipid peroxidation. Functionally ‘exhausted’ CD8+ TILs increased CD36 expression and CD36-deficient CD8+ TILs had more robust anti-tumor activity and cytokine production than wild-type cells. We further show that CD36 promotes uptake of oxidized low-density lipoproteins (OxLDL), induces lipid peroxidation in CD8+ TILs, and enhances p38 kinase phosphorylation. Moreover, we found that OxLDL inhibits CD8+ T cell functions in a CD36/p38-dependent manner. Furthermore, glutathione peroxidase 4 (GPX4) over-expression lowers lipid peroxidation and restores functionalities in CD8+ TILs. These results define a key role for an oxidized lipid-CD36-p38 axis in promoting intratumoral CD8+ T cell dysfunction.
Project description:Rapid, simple and reliable blood tests for Parkinson’s disease (PD) may enable pre-symptomatic diagnosis and facilitate disease-changing treatments. Here, we report escalated elevated levels of angiogenin-cleaved a disease specific group of nuclear genome-originated tRNA fragments (hereafter, PD-tRFs) carrying a unique seven-nucleotide motif in substantia nigra, cerebrospinal fluid and blood of PD patients. A blood test using RNA isolated from whole blood and dual multiplexl qPCR primers for PD-tRFs and mitochondrial-originated tRFs (MT-tRFs) successfully distinguished pre-symptomatic PD patients from controls, outperforming traditional clinical scoring (ROC-AUC of 0.86 vs. 0.73). Indicating relevance to disease symptoms, PD patients carrying GBA, SNCA or LRRK2 mutations presented elevated blood PD/MT-tRF ratios compared to mutations-carrying non-symptomatic individuals which indicates relevance to disease symptoms. Furthermore, PD-tRFs’ potential for ribosomal association predicted translational inhibition. Intriguingly, PD-tRFs levels declined both in patients’ blood following deep brain stimulation andas well as in in depolarized neuroblastoma cells where PD-tRFs presented transientlydepolirization impaired impacted ribosomal associations. Our findings facilitate a sensitive and accurate blood test for early PD.
Project description:Dysregulated metabolism is a key driver of maladaptive tumor-reactive T lymphocytes within the tumor microenvironment (TME). Actionable mechanisms that rescue the effector activity of anti-tumor T cells in a metabolically restricted TME remain elusive. Here, we report that the Sirtuin-2 (Sirt2) protein deacetylase functions as a master metabolic checkpoint that inhibits T cell metabolic fitness and impairs T cell effector functions and anti-tumor immunity. Mechanistically, Sirt2 suppresses glycolysis and oxidative-phosphorylation (OxPhos) by deacetylating key enzymes involved in glycolysis, tricarboxylic acid (TCA)-cycle, fatty acid oxidation (FAO) and glutaminolysis. Accordingly, Sirt2-deficient T cells exhibit a hyper-metabolic activity with increased glycolysis and OxPhos, resulting in enhanced proliferation and effector functions at tumor beds and subsequently exhibiting superior anti-tumor activity. Importantly, pharmacologic inhibition of Sirt2 endows human lung tumor-infiltrating lymphocytes (TILs) with these superior metabolic fitness and enhanced effector functions. Furthermore, upregulation of Sirt2 expression in human TILs negatively correlates with response to Nivolumab and TIL therapy in non-small cell lung cancer (NSCLC). Our findings unveil Sirt2 as an unexpected actionable target for reprogramming T cell metabolism to augment a broad spectrum of cancer immunotherapies.