bims-imseme 2020-09-06 papers

bims-imseme

Biomed News

on Immunosenescence and T cell metabolism

Issue of 2020–09–06
34 papers selected by
Pierpaolo Ginefra, Ludwig Institute for Cancer Research

Single Cell Glucose Uptake Assays: A Cautionary Tale.
A Complex Acetate-ment: Timing of Exposure Determines Memory T Cell Fate.
The PD-1 expression balance between effector and regulatory T cells predicts the clinical efficacy of PD-1 blockade therapies.
CD4 T cells differentially express cellular machinery for serotonin signaling, synthesis, and metabolism.
Time-dependent replicative senescence vs. disturbed flow-induced pre-mature aging in atherosclerosis.
Human immunology and immunotherapy: main achievements and challenges.
MicroRNA miR-181-A Rheostat for TCR Signaling in Thymic Selection and Peripheral T-Cell Function.
Human γδ T cells recognize CD1b by two distinct mechanisms.
Single-cell metabolic profiling of human cytotoxic T cells.
Antibody-Mediated Inhibition of CTLA4 Aggravates Atherosclerotic Plaque Inflammation and Progression in Hyperlipidemic Mice.
Immune surveillance of the liver by T cells.
Cancer immunotherapy harnessing γδ T cells and programmed death-1.
Single-cell RNA sequencing identifies shared differentiation paths of mouse thymic innate T cells.
Spatial Distribution and Prognostic Implications of Tumor-Infiltrating FoxP3- CD4+ T Cells in Biliary Tract Cancer.
CD70 Inversely Regulates Regulatory T Cells and Invariant NKT Cells and Modulates Type 1 Diabetes in NOD Mice.
A Protocol to Study Mitochondrial Function in Human Neural Progenitors and iPSC-Derived Astrocytes.
CD49a Regulates Cutaneous Resident Memory CD8+ T Cell Persistence and Response.
Cancer SLC43A2 alters T cell methionine metabolism and histone methylation.
Clinical Pharmacology and Interplay of Immune Checkpoint Agents: A Yin-Yang Balance.
Analysis of chromatin organization and gene expression in T cells identifies functional genes for rheumatoid arthritis.
sLeX Expression Delineates Distinct Functional Subsets of Human Blood Central and Effector Memory T Cells.
Alpha-Ketoglutarate, the Metabolite that Regulates Aging in Mice.
Novel roles of Immunometabolism and Non-Myocyte Metabolism in Cardiac Remodeling and Injury.
The hepatic microenvironment and regulatory T cells.
Hematopoietic Progenitor Kinase1 (HPK1) Mediates T Cell Dysfunction and Is a Druggable Target for T Cell-Based Immunotherapies.
A High-Density Human Mitochondrial Proximity Interaction Network.
Resident macrophages as potential therapeutic targets for cardiac ageing and injury.
Alpha-Ketoglutarate, an Endogenous Metabolite, Extends Lifespan and Compresses Morbidity in Aging Mice.
Bispecific Targeting of PD-1 and PD-L1 Enhances T-cell Activation and Antitumor Immunity.
Microenvironmental Aspartate Preserves Leukemic Cells from Therapy-Induced Metabolic Collapse.
Therapeutic Targeting of Mitochondrial One-Carbon Metabolism in Cancer.
Heterochromatin: an epigenetic point of view in aging.
IFN-γ treatment protocol for MHC-Ilo/PD-L1+ pancreatic tumor cells selectively restores their TAP-mediated presentation competence and CD8 T-cell priming potential.
Dietary magnesium supplementation improves lifespan in a mouse model of progeria.

Immunometabolism. 2020 ;2(4): e200029

Single Cell Glucose Uptake Assays: A Cautionary Tale.

Linda V Sinclair, Celine Barthelemy, Doreen A Cantrell.

  Assays to monitor the metabolic state or nutrient uptake capacity of immune cells at a single cell level are increasingly in demand. One assay, used by many immunologists, employs 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG), a fluorescent analogue of 2-deoxyglucose (2DG), as a substrate for glucose transporters. This molecule has been validated as a substrate for the glucose transporter Glut2 (Slc2a2) in mammalian cells but 2-NDBG selectivity for the glucose transporters expressed by T cells, Glut1 (Slc2a1) and Glut3 (Slc2a3), has never been explored. Nor has the possibility that 2-NBDG might bind to T cells that do not express glucose transporters been assessed. In this technical commentary we interrogate the specificity of 2-NBBG labelling as a readout for glucose transport in T lymphocytes. We compare flow cytometric 2-NBDG staining against well validated radiolabelled glucose transport assays in murine T cells. Our data show there can be a large discordance between glucose transport capacity and 2-NBDG labelling in T cells. We also find that 2-NBDG uptake into murine T cells is not inhibited by competitive substrates or facilitative glucose transporter inhibitors, nor can 2-NBDG competitively block glucose uptake in T cells. Collectively, these data argue that 2-NBDG uptake alone is not a reliable tool for the assessment of cellular glucose transport capacity.

Keywords:  2-NBDG; T cells; T lymphocytes; glucose uptake

DOI:  https://doi.org/10.20900/immunometab20200029
Cell Metab. 2020 Sep 01. pii: S1550-4131(20)30423-X. [Epub ahead of print]32(3): 325-327

A Complex Acetate-ment: Timing of Exposure Determines Memory T Cell Fate.

Graham A Heieis, Bart Everts.

In this issue of Cell Metabolism, Balmer et al. show that the timing and concentration of acetate exposure is critical to how it is metabolized by and affects the function of CD8 T cells. When abundantly present at the time of reactivation, acetate rewires CD8 T cell metabolism to suppress their reactivation and limit inflammation.

DOI: https://doi.org/10.1016/j.cmet.2020.08.010
Nat Immunol. 2020 Aug 31.

The PD-1 expression balance between effector and regulatory T cells predicts the clinical efficacy of PD-1 blockade therapies.

Shogo Kumagai, Yosuke Togashi, Takahiro Kamada, Eri Sugiyama, Hitomi Nishinakamura, Yoshiko Takeuchi, Kochin Vitaly, Kota Itahashi, Yuka Maeda, Shigeyuki Matsui, Takuma Shibahara, Yasuho Yamashita, Takuma Irie, Ayaka Tsuge, Shota Fukuoka, Akihito Kawazoe, Hibiki Udagawa, Keisuke Kirita, Keiju Aokage, Genichiro Ishii, Takeshi Kuwata, Kenta Nakama, Masahito Kawazu, Toshihide Ueno, Naoya Yamazaki, Koichi Goto, Masahiro Tsuboi, Hiroyuki Mano, Toshihiko Doi, Kohei Shitara, Hiroyoshi Nishikawa.

Immune checkpoint blockade has provided a paradigm shift in cancer therapy, but the success of this approach is very variable; therefore, biomarkers predictive of clinical efficacy are urgently required. Here, we show that the frequency of PD-1+CD8+ T cells relative to that of PD-1+ regulatory T (Treg) cells in the tumor microenvironment can predict the clinical efficacy of programmed cell death protein 1 (PD-1) blockade therapies and is superior to other predictors, including PD ligand 1 (PD-L1) expression or tumor mutational burden. PD-1 expression by CD8+ T cells and Treg cells negatively impacts effector and immunosuppressive functions, respectively. PD-1 blockade induces both recovery of dysfunctional PD-1+CD8+ T cells and enhanced PD-1+ Treg cell-mediated immunosuppression. A profound reactivation of effector PD-1+CD8+ T cells rather than PD-1+ Treg cells by PD-1 blockade is necessary for tumor regression. These findings provide a promising predictive biomarker for PD-1 blockade therapies.

DOI: https://doi.org/10.1038/s41590-020-0769-3
Int Immunopharmacol. 2020 Aug 28. pii: S1567-5769(20)32094-4. [Epub ahead of print]88 106922

CD4 T cells differentially express cellular machinery for serotonin signaling, synthesis, and metabolism.

Hera Wu, DeVon Herr, Nancie J MacIver, Jeffrey C Rathmell, Valerie A Gerriets.

  CD4 T cells play a major role to orchestrate the immune response. Upon activation, CD4 T cells differentiate into effector T cell (Teff) or regulatory T cell (Treg) subsets that promote or suppress the immune response, respectively. Along with these unique immunological roles, CD4 T cell subsets have specific metabolic requirements and programs that can influence the immune response. We therefore examined the metabolite levels of Teff and Treg in detail. Surprisingly, the metabolite showing the largest difference between Teff and Treg was serotonin (5-HT), revealing a potentially distinct role for serotonin in CD4 T cell function. 5-HT is well known as a neurotransmitter and recently has been recognized to play a role in the immune response; however, little is known about the immune cell type-specific expression of the serotonergic machinery and receptors. We therefore examined the serotonergic-related machinery in Teff and Treg and found differential expression of the serotonin transporter SERT and 5-HT1a and 5-HT2 receptors. We also found that Treg express tryptophan hydroxylase, which converts tryptophan to serotonin, suggesting for the first time that Treg synthesize serotonin. Our results in this study expand the potential immunomodulatory role of serotonin in CD4 T cell biology and could ultimately aid the development of novel immunomodulatory targets for treatment of autoimmune and neuropsychiatric disorders.

Keywords:  5-HT; Lymphocytes; Regulatory T cells; Serotonin; T cells; Treg

DOI:  https://doi.org/10.1016/j.intimp.2020.106922
Redox Biol. 2020 Jun 24. pii: S2213-2317(20)30819-3. [Epub ahead of print] 101614

Time-dependent replicative senescence vs. disturbed flow-induced pre-mature aging in atherosclerosis.

Abishai Dominic, Priyanka Banerjee, Dale J Hamilton, Nhat-Tu Le, Jun-Ichi Abe.

  Accumulation of senescent cells has a causative role in the pathology of age-related disorders including atherosclerosis (AS) and cardiovascular diseases (CVDs). However, the concept of senescence is now drastically changing, and the new concept of senescence-associated reprogramming/stemness has emerged, suggesting that senescence is not merely related to "cell cycle arrest" or halting various cellular functions. It is well known that disturbed flow (D-flow) accelerates pre-mature aging and plays a significant role in the development of AS. We will discuss in this review that pre-mature aging induced by D-flow is not comparable to time-dependent aging, particularly with a focus on the possible involvement of senescence-associated secretory phenotype (SASP) in senescence-associated reprogramming/stemness, or increasing cell numbers. We will also present our outlook of nicotinamide adenine dinucleotides (NAD)+ deficiency-induced mitochondrial reactive oxygen species (mtROS) in evoking SASP by activating DNA damage response (DDR). MtROS plays a key role in developing cross-talk between nuclear-mitochondria, SASP, and ultimately atherosclerosis formation. Although senescence induced by time and various stress factors is a classical concept, we wish that the readers will see the undergoing Copernican-like change in this concept, as well as to recognize the significant contrast between pre-mature aging induced by D-flow and time-dependent aging.

Keywords:  Aging; Atherosclerosis; Oxidative stress; Senescence; Senescent-associated stemness; Telomere shortening

DOI:  https://doi.org/10.1016/j.redox.2020.101614
Cell Mol Immunol. 2020 Sep 02.

Human immunology and immunotherapy: main achievements and challenges.

Jezabel Varadé, Susana Magadán, África González-Fernández.

  The immune system is a fascinating world of cells, soluble factors, interacting cells, and tissues, all of which are interconnected. The highly complex nature of the immune system makes it difficult to view it as a whole, but researchers are now trying to put all the pieces of the puzzle together to obtain a more complete picture. The development of new specialized equipment and immunological techniques, genetic approaches, animal models, and a long list of monoclonal antibodies, among many other factors, are improving our knowledge of this sophisticated system. The different types of cell subsets, soluble factors, membrane molecules, and cell functionalities are some aspects that we are starting to understand, together with their roles in health, aging, and illness. This knowledge is filling many of the gaps, and in some cases, it has led to changes in our previous assumptions; e.g., adaptive immune cells were previously thought to be unique memory cells until trained innate immunity was observed, and several innate immune cells with features similar to those of cytokine-secreting T cells have been discovered. Moreover, we have improved our knowledge not only regarding immune-mediated illnesses and how the immune system works and interacts with other systems and components (such as the microbiome) but also in terms of ways to manipulate this system through immunotherapy. The development of different types of immunotherapies, including vaccines (prophylactic and therapeutic), and the use of pathogens, monoclonal antibodies, recombinant proteins, cytokines, and cellular immunotherapies, are changing the way in which we approach many diseases, especially cancer.

Keywords:  CAR T cells; Cancer; Microbiota; Monoclonal antibodies; Trained immunity; Vaccines

DOI:  https://doi.org/10.1038/s41423-020-00530-6
Int J Mol Sci. 2020 Aug 27. pii: E6200. [Epub ahead of print]21(17):

MicroRNA miR-181-A Rheostat for TCR Signaling in Thymic Selection and Peripheral T-Cell Function.

Zoe Grewers, Andreas Krueger.

  The selection of T cells during intra-thymic d evelopment is crucial to obtain a functional and simultaneously not self-reactive peripheral T cell repertoire. However, selection is a complex process dependent on T cell receptor (TCR) thresholds that remain incompletely understood. In peripheral T cells, activation, clonal expansion, and contraction of the active T cell pool, as well as other processes depend on TCR signal strength. Members of the microRNA (miRNA) miR-181 family have been shown to be dynamically regulated during T cell development as well as dependent on the activation stage of T cells. Indeed, it has been shown that expression of miR-181a leads to the downregulation of multiple phosphatases, implicating miR-181a as ''rheostat'' of TCR signaling. Consistently, genetic models have revealed an essential role of miR-181a/b-1 for the generation of unconventional T cells as well as a function in tuning TCR sensitivity in peripheral T cells during aging. Here, we review these broad roles of miR-181 family members in T cell function via modulating TCR signal strength.

Keywords:  T cell receptor; miR-181; microRNA; selection; signaling; thymus; unconventional T cell

DOI:  https://doi.org/10.3390/ijms21176200
Proc Natl Acad Sci U S A. 2020 Aug 31. pii: 202010545. [Epub ahead of print]

Human γδ T cells recognize CD1b by two distinct mechanisms.

Josephine F Reijneveld, Tonatiuh A Ocampo, Adam Shahine, Benjamin S Gully, Pierre Vantourout, Adrian C Hayday, Jamie Rossjohn, D Branch Moody, Ildiko Van Rhijn.

  γδ T cells form an abundant part of the human cellular immune system, where they respond to tissue damage, infection, and cancer. The spectrum of known molecular targets recognized by Vδ1-expressing γδ T cells is becoming increasingly diverse. Here we describe human γδ T cells that recognize CD1b, a lipid antigen-presenting molecule, which is inducibly expressed on monocytes and dendritic cells. Using CD1b tetramers to study multiple donors, we found that many CD1b-specific γδ T cells use Vδ1. Despite their common use of Vδ1, three CD1b-specific γδ T cell receptors (TCRs) showed clear differences in the surface of CD1b recognized, the requirement for lipid antigens, and corecognition of butryophilin-like proteins. Several Vγ segments were present among the CD1b-specific TCRs, but chain swap experiments demonstrated that CD1b specificity was mediated by the Vδ1 chain. One of the CD1b-specific Vδ1+ TCRs paired with Vγ4 and shows dual reactivity to CD1b and butyrophilin-like proteins. αβ TCRs typically recognize the peptide display platform of MHC proteins. In contrast, our results demonstrate the use of rearranged receptors to mediate diverse modes of recognition across the surface of CD1b in ways that do and do not require carried lipids.

Keywords:  CD1b; Vd1; butyrophilin-like molecule; gd T cell; lipid antigen

DOI:  https://doi.org/10.1073/pnas.2010545117
Nat Biotechnol. 2020 Aug 31.

Single-cell metabolic profiling of human cytotoxic T cells.

Felix J Hartmann, Dunja Mrdjen, Erin McCaffrey, David R Glass, Noah F Greenwald, Anusha Bharadwaj, Zumana Khair, Sanne G S Verberk, Alex Baranski, Reema Baskar, William Graf, David Van Valen, Jan Van den Bossche, Michael Angelo, Sean C Bendall.

Cellular metabolism regulates immune cell activation, differentiation and effector functions, but current metabolic approaches lack single-cell resolution and simultaneous characterization of cellular phenotype. In this study, we developed an approach to characterize the metabolic regulome of single cells together with their phenotypic identity. The method, termed single-cell metabolic regulome profiling (scMEP), quantifies proteins that regulate metabolic pathway activity using high-dimensional antibody-based technologies. We employed mass cytometry (cytometry by time of flight, CyTOF) to benchmark scMEP against bulk metabolic assays by reconstructing the metabolic remodeling of in vitro-activated naive and memory CD8+ T cells. We applied the approach to clinical samples and identified tissue-restricted, metabolically repressed cytotoxic T cells in human colorectal carcinoma. Combining our method with multiplexed ion beam imaging by time of flight (MIBI-TOF), we uncovered the spatial organization of metabolic programs in human tissues, which indicated exclusion of metabolically repressed immune cells from the tumor-immune boundary. Overall, our approach enables robust approximation of metabolic and functional states in individual cells.

DOI: https://doi.org/10.1038/s41587-020-0651-8
Cells. 2020 Aug 29. pii: E1987. [Epub ahead of print]9(9):

Antibody-Mediated Inhibition of CTLA4 Aggravates Atherosclerotic Plaque Inflammation and Progression in Hyperlipidemic Mice.

Kikkie Poels, Mandy M T van Leent, Myrthe E Reiche, Pascal J H Kusters, Stephan Huveneers, Menno P J de Winther, Willem J M Mulder, Esther Lutgens, Tom T P Seijkens.

  T cell-driven inflammation plays a critical role in the initiation and progression of atherosclerosis. The co-inhibitory protein Cytotoxic T-Lymphocyte Associated protein (CTLA) 4 is an important negative regulator of T cell activation. Here, we studied the effects of the antibody-mediated inhibition of CTLA4 on experimental atherosclerosis by treating 6-8-week-old Ldlr-/- mice, fed a 0.15% cholesterol diet for six weeks, biweekly with 200 μg of CTLA4 antibodies or isotype control for six weeks. 18F-fluorodeoxyglucose Positron Emission Tomography-Computed Tomography showed no effect of the CTLA4 inhibition of activity in the aorta, spleen, and bone marrow, indicating that monocyte/macrophage-driven inflammation was unaffected. Correspondingly, flow cytometry demonstrated that the antibody-mediated inhibition of CTLA4 did not affect the monocyte populations in the spleen. αCTLA4 treatment induced an activated T cell profile, characterized by a decrease in naïve CD44-CD62L+CD4+ T cells and an increase in CD44+CD62L- CD4+ and CD8+ T cells in the blood and lymphoid organs. Furthermore, αCTLA4 treatment induced endothelial activation, characterized by increased ICAM1 expression in the aortic endothelium. In the aortic arch, which mainly contained early atherosclerotic lesions at this time point, αCTLA4 treatment induced a 2.0-fold increase in the plaque area. These plaques had a more advanced morphological phenotype and an increased T cell/macrophage ratio, whereas the smooth muscle cell and collagen content decreased. In the aortic root, a site that contained more advanced plaques, αCTLA4 treatment increased the plaque T cell content. The short-term antibody-mediated inhibition of CTLA4 thus accelerated the progression of atherosclerosis by inducing a predominantly T cell-driven inflammation, and resulted in the formation of plaques with larger necrotic cores and less collagen. This indicates that existing therapies that are based on αCTLA4 antibodies may promote CVD development in patients.

Keywords:  Cytotoxic T-Lymphocyte Associated protein (CTLA) 4; T cells; atherosclerosis; immune checkpoint inhibitors; inflammation

DOI:  https://doi.org/10.3390/cells9091987
Sci Immunol. 2020 Sep 04. pii: eaba2351. [Epub ahead of print]5(51):

Immune surveillance of the liver by T cells.

Xenia Ficht, Matteo Iannacone.

The liver is the target of several infectious, inflammatory, and neoplastic diseases, which affect hundreds of millions of people worldwide and cause an estimated death toll of more than 2 million people each year. Dysregulation of T cell responses has been implicated in the pathogenesis of these diseases; hence, it is critically important to understand the function and fate of T cells in the liver. Here, we provide an overview of the current knowledge on liver immune surveillance by conventional and invariant T cells and explore the complex cross-talk between immune cell subsets that determines the balance between hepatic immunity and tolerance.

DOI: https://doi.org/10.1126/sciimmunol.aba2351
Immunol Rev. 2020 Sep 05.

Cancer immunotherapy harnessing γδ T cells and programmed death-1.

Yoshimasa Tanaka.

Cancer immunotherapy has received increasing attention since the success of CTLA-4 and programmed death-1 (PD-1) immune checkpoint inhibitors and CAR-T cells. One of the most promising next-generation cancer treatments is adoptive transfer of immune effector cells. Developing an efficacious adoptive transfer therapy requires growing large numbers of highly purified immune effector cells in a short period of time. γδ T cells can be effectively expanded using synthetic antigens such as pyrophosphomonoesters and nitrogen-containing bisphosphonates (N-BPs). Pyrophosphomonoester antigens, initially identified in mycobacterial extracts, were used for this purpose in the early years of the development of γδ T cell-based therapy. GMP-grade N-BPs, which are now commercially available, are used in many clinical trials worldwide. In order to develop N-BPs for cancer immunotherapy, N-BP prodrugs have been synthesized; among these, tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino)ethylidene-1,1-bisphosphonate (PTA) is the most potent compound for stimulating γδ T cells. The activated γδ T cells express high levels of PD-1, suggesting the potential for a combination therapy harnessing γδ T cells and PD-1 immune checkpoint inhibitors. In addition, the functions of γδ T cells can be modified by IL-18. Collectively, the recent findings show that γδ T cells are one of the most promising immune effector subsets for the development of novel cancer immunotherapy.

DOI: https://doi.org/10.1111/imr.12917
Nat Commun. 2020 08 31. 11(1): 4367

Single-cell RNA sequencing identifies shared differentiation paths of mouse thymic innate T cells.

Minji Lee, Eunmin Lee, Seong Kyu Han, Yoon Ha Choi, Dong-Il Kwon, Hyobeen Choi, Kwanghwan Lee, Eun Seo Park, Min-Seok Rha, Dong Jin Joo, Eui-Cheol Shin, Sanguk Kim, Jong Kyoung Kim, You Jeong Lee.

Invariant natural killer T (iNKT), mucosal-associated invariant T (MAIT), and γδ T cells are innate T cells that acquire memory phenotype in the thymus and share similar biological characteristics. However, how their effector differentiation is developmentally regulated is still unclear. Here, we identify analogous effector subsets of these three innate T cell types in the thymus that share transcriptional profiles. Using single-cell RNA sequencing, we show that iNKT, MAIT and γδ T cells mature via shared, branched differentiation rather than linear maturation or TCR-mediated instruction. Simultaneous TCR clonotyping analysis reveals that thymic maturation of all three types is accompanied by clonal selection and expansion. Analyses of mice deficient of TBET, GATA3 or RORγt and additional in vivo experiments corroborate the predicted differentiation paths, while human innate T cells from liver samples display similar features. Collectively, our data indicate that innate T cells share effector differentiation processes in the thymus.

DOI: https://doi.org/10.1038/s41467-020-18155-8
Cancer Res Treat. 2020 Aug 31.

Spatial Distribution and Prognostic Implications of Tumor-Infiltrating FoxP3- CD4+ T Cells in Biliary Tract Cancer.

Hyung-Don Kim, Jwa Hoon Kim, Yeon-Mi Ryu, Danbee Kim, Sunmin Lee, Jaehoon Shin, Seung-Mo Hong, Ki-Hun Kim, Dong-Hwan Jung, Gi-Won Song, Dae Wook Hwang, Jae Hoon Lee, Ki Byung Song, Baek-Yeol Ryoo, Jae Ho Jeong, Kyu-Pyo Kim, Sang-Yeob Kim, Changhoon Yoo.

   Purpose: The clinical implications of tumor-infiltrating T cell subsets and their spatial distribution in biliary tract cancer (BTC) patients treated with gemcitabine plus cisplatin were investigated.
Materials and Methods: A total of 52 BTC patients treated with palliative gemcitabine plus cisplatin were included. Multiplexed immunohistochemistry was performed on tumor tissues, and immune infiltrates were separately analyzed for the stroma, tumor margin, and tumor core.
Results: The density of CD8+ T cells, FoxP3- CD4+ helper T cells, and FoxP3+ CD4+ regulatory T cells was significantly higher in the tumor margin than in the stroma and tumor core. The density of LAG3- or TIM3-expressing CD8+ T cell and FoxP3- CD4+ helper T cell infiltrates was also higher in the tumor margin. In extrahepatic cholangiocarcinoma, there was a higher density of T cell subsets in the tumor core and regulatory T cells in all regions. A high density of FoxP3- CD4+ helper T cells in the tumor margin showed a trend toward better progression-free survival (PFS) (p=0.092) and significantly better overall survival (OS) (p=0.012). In multivariate analyses, a high density of FoxP3- CD4+ helper T cells in the tumor margin was independently associated with favorable PFS and OS.
Conclusion: The tumor margin is the major site for the active infiltration of T cell subsets with higher levels of LAG3 and TIM3 expression in BTC. The density of tumor margin-infiltrating FoxP3- CD4+ helper T cells may be associated with clinical outcomes in BTC patients treated with gemcitabine plus cisplatin.

Keywords:  Biliary tract neoplasms; CD4+ helper T cells; Multiplexed immunohistochemistry; Tumor margin

DOI:  https://doi.org/10.4143/crt.2020.704
J Immunol. 2020 Aug 31. pii: ji2000148. [Epub ahead of print]

CD70 Inversely Regulates Regulatory T Cells and Invariant NKT Cells and Modulates Type 1 Diabetes in NOD Mice.

Cheng Ye, Benjamin E Low, Michael V Wiles, Todd M Brusko, David V Serreze, John P Driver.

The CD27-CD70 costimulatory pathway is essential for the full activation of T cells, but some studies show that blocking this pathway exacerbates certain autoimmune disorders. In this study, we report on the impact of CD27-CD70 signaling on disease progression in the NOD mouse model of type 1 diabetes (T1D). Specifically, our data demonstrate that CD70 ablation alters thymocyte selection and increases circulating T cell levels. CD27 signaling was particularly important for the thymic development and peripheral homeostasis of Foxp3+Helios+ regulatory T cells, which likely accounts for our finding that CD70-deficient NOD mice develop more-aggressive T1D onset. Interestingly, we found that CD27 signaling suppresses the thymic development and effector functions of T1D-protective invariant NKT cells. Thus, rather than providing costimulatory signals, the CD27-CD70 axis may represent a coinhibitory pathway for this immunoregulatory T cell population. Moreover, we showed that a CD27 agonist Ab reversed the effects of CD70 ablation, indicating that the phenotypes observed in CD70-deficient mice were likely due to a lack of CD27 signaling. Collectively, our results demonstrate that the CD27-CD70 costimulatory pathway regulates the differentiation program of multiple T cell subsets involved in T1D development and may be subject to therapeutic targeting.

DOI: https://doi.org/10.4049/jimmunol.2000148
Curr Protoc Toxicol. 2020 Sep;85(1): e97

A Protocol to Study Mitochondrial Function in Human Neural Progenitors and iPSC-Derived Astrocytes.

Gabriela Assis-de-Lemos, Pítia Flores Ledur, Karina Karmirian, Stevens Kastrup Rehen, Antonio Galina.

  Mitochondrial dysfunction is a central component in the pathophysiology of multiple neuropsychiatric and degenerative disorders. Evaluating mitochondrial function in human-derived neural cells can help characterize dysregulation in oxidative metabolism associated with the onset of brain disorders, and may also help define targeted therapies. Astrocytes play a number of different key roles in the brain, being implicated in neurogenesis, synaptogenesis, blood-brain-barrier permeability, and homeostasis, and, consequently, the malfunctioning of astrocytes is related to many neuropathologies. Here we describe protocols for generating induced pluripotent stem cell (iPSC)-derived astrocytes and evaluating multiple aspects of mitochondrial function. We use a high-resolution respirometry assay that measures real-time variations in mitochondrial oxygen flow, allowing the evaluation of cellular respiration in the context of an intact intracellular microenvironment, something not possible with permeabilized cells or isolated mitochondria, where the cellular microenvironment is disrupted. Given that an impairment in the mitochondrial regulation of intracellular calcium homeostasis is involved in many pathologic stresses, we also describe a protocol to evaluate mitochondrial calcium dynamics in human neural cells, by fluorimetry. Lastly, we outline a mitochondrial function assay that allows for the measurement of the enzymatic activity of mitochondrial hexokinase (mt-HK), an enzyme that is functionally coupled to oxidative phosphorylation and is involved in redox homeostasis, particularly in the brain. In all, these protocols allow a detailed characterization of mitochondrial function in human neural cells. High-resolution respirometry, calcium dynamics, and mt-HK activity assays provide data regarding the functional status of mitochondria, which may reflect mitochondrial stress or dysfunction. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Generation of iPSC-derived human astrocytes Basic Protocol 2: Measuring real-time oxygen flux in human iPSC-derived astrocytes using a high-resolution OROBOROS Oxygraph 2k (O2k) Basic Protocol 3: Measuring mitochondrial calcium dynamics fluorometrically in permeabilized human neural cells Basic Protocol 4: Measuring OXPHOS-dependent activity of mitochondrial hexokinase in permeabilized human neural cells using a spectrophotometer.

Keywords:  astrocytes; calcium dynamics; iPSC; mitochondrial stress; respirometry

DOI:  https://doi.org/10.1002/cptx.97
Cell Rep. 2020 Sep 01. pii: S2211-1247(20)31074-3. [Epub ahead of print]32(9): 108085

CD49a Regulates Cutaneous Resident Memory CD8+ T Cell Persistence and Response.

Shannon K Bromley, Hasan Akbaba, Vinidhra Mani, Rut Mora-Buch, Alexandra Y Chasse, Andrea Sama, Andrew D Luster.

  CD8+ tissue-resident memory T cells (TRM) persist at sites of previous infection, where they provide rapid local protection against pathogen challenge. CD8+ TRM expressing the α1 chain (CD49a) of integrin VLA-1 have been identified within sites of resolved skin infection and in vitiligo lesions. We demonstrate that CD49a is expressed early following T cell activation in vivo, and TGF-β and IL-12 induce CD49a expression by CD8+ T cells in vitro. Despite this rapid expression, CD49a is not required for the generation of a primary CD8+ T cell response to cutaneous herpes simplex virus (HSV) infection, migration of CD8+ T cells across the epidermal basement membrane, or positioning of TRM within basal epidermis. Rather, CD49a supports CD8+ TRM persistence within skin, regulates epidermal CD8+ TRM dendritic extensions, and increases the frequency of IFN-γ+ CD8+ TRM following local antigen challenge. Our results suggest that CD49a promotes optimal cutaneous CD8+ TRM-mediated immunity.

Keywords:  CD49a; CD8(+) T cells; IFN-g; cytokines; herpes simplex virus; morphology; skin; tissue-resident memory T cells

DOI:  https://doi.org/10.1016/j.celrep.2020.108085
Nature. 2020 Sep 02.

Cancer SLC43A2 alters T cell methionine metabolism and histone methylation.

Yingjie Bian, Wei Li, Daniel M Kremer, Peter Sajjakulnukit, Shasha Li, Joel Crespo, Zeribe C Nwosu, Li Zhang, Arkadiusz Czerwonka, Anna Pawłowska, Houjun Xia, Jing Li, Peng Liao, Jiali Yu, Linda Vatan, Wojciech Szeliga, Shuang Wei, Sara Grove, J Rebecca Liu, Karen McLean, Marcin Cieslik, Arul M Chinnaiyan, Witold Zgodziński, Grzegorz Wallner, Iwona Wertel, Karolina Okła, Ilona Kryczek, Costas A Lyssiotis, Weiping Zou.

Abnormal epigenetic patterns correlate with effector T cell malfunction in tumours1-4, but the cause of this link is unknown. Here we show that tumour cells disrupt methionine metabolism in CD8+ T cells, thereby lowering intracellular levels of methionine and the methyl donor S-adenosylmethionine (SAM) and resulting in loss of dimethylation at lysine 79 of histone H3 (H3K79me2). Loss of H3K79me2 led to low expression of STAT5 and impaired T cell immunity. Mechanistically, tumour cells avidly consumed methionine and outcompeted T cells for methionine by expressing high levels of the methionine transporter SLC43A2. Genetic and biochemical inhibition of tumour SLC43A2 restored H3K79me2 in T cells, thereby boosting spontaneous and checkpoint-induced tumour immunity. Moreover, methionine supplementation improved the expression of H3K79me2 and STAT5 in T cells, and this was accompanied by increased T cell immunity in tumour-bearing mice and patients with colon cancer. Clinically, tumour SLC43A2 correlated negatively with T cell histone methylation and functional gene signatures. Our results identify a mechanistic connection between methionine metabolism, histone patterns, and T cell immunity in the tumour microenvironment. Thus, cancer methionine consumption is an immune evasion mechanism, and targeting cancer methionine signalling may provide an immunotherapeutic approach.

DOI: https://doi.org/10.1038/s41586-020-2682-1
Annu Rev Pharmacol Toxicol. 2020 Sep 01.

Clinical Pharmacology and Interplay of Immune Checkpoint Agents: A Yin-Yang Balance.

Arthur Geraud, Paul Gougis, Aurore Vozy, Celine Anquetil, Yves Allenbach, Emanuela Romano, Elisa Funck-Brentano, Javid J Moslehi, Douglas B Johnson, Joe-Elie Salem.

T cells have a central role in immune system balance. When activated, they may lead to autoimmune diseases. When too anergic, they contribute to infection spread and cancer proliferation. Immune checkpoint proteins regulate T cell function, including cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death-1 (PD-1) and its ligand (PD-L1). These nodes of self-tolerance may be exploited pharmacologically to downregulate (CTLA-4 agonists) and activate [CTLA-4 and PD-1/PD-L1 antagonists, also called immune checkpoint inhibitors (ICIs)] the immune system. CTLA-4 agonists are used to treat rheumatologic immune disorders and graft rejection. CTLA-4, PD-1, and PD-L1 antagonists are approved for multiple cancer types and are being investigated for chronic viral infections. Notably, ICIs may be associated with immune-related adverse events (irAEs), which can be highly morbid or fatal. CTLA-4 agonism has been a promising method to reverse such life-threatening irAEs. Herein, we review the clinical pharmacology of these immune checkpoint agents with a focus on their interplay in human diseases. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 61 is January 8, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

DOI: https://doi.org/10.1146/annurev-pharmtox-022820-093805
Nat Commun. 2020 Sep 02. 11(1): 4402

Analysis of chromatin organization and gene expression in T cells identifies functional genes for rheumatoid arthritis.

Jing Yang, Amanda McGovern, Paul Martin, Kate Duffus, Xiangyu Ge, Peyman Zarrineh, Andrew P Morris, Antony Adamson, Peter Fraser, Magnus Rattray, Stephen Eyre.

Genome-wide association studies have identified genetic variation contributing to complex disease risk. However, assigning causal genes and mechanisms has been more challenging because disease-associated variants are often found in distal regulatory regions with cell-type specific behaviours. Here, we collect ATAC-seq, Hi-C, Capture Hi-C and nuclear RNA-seq data in stimulated CD4+ T cells over 24 h, to identify functional enhancers regulating gene expression. We characterise changes in DNA interaction and activity dynamics that correlate with changes in gene expression, and find that the strongest correlations are observed within 200 kb of promoters. Using rheumatoid arthritis as an example of T cell mediated disease, we demonstrate interactions of expression quantitative trait loci with target genes, and confirm assigned genes or show complex interactions for 20% of disease associated loci, including FOXO1, which we confirm using CRISPR/Cas9.

DOI: https://doi.org/10.1038/s41467-020-18180-7
J Immunol. 2020 Aug 31. pii: ji1900679. [Epub ahead of print]

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

Mariana Silva, Kyle C Martin, Nandini Mondal, Robert Sackstein.

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

DOI: https://doi.org/10.4049/jimmunol.1900679
Cell Metab. 2020 Sep 01. pii: S1550-4131(20)30422-8. [Epub ahead of print]32(3): 323-325

Alpha-Ketoglutarate, the Metabolite that Regulates Aging in Mice.

Timothy W Rhoads, Rozalyn M Anderson.

In this issue of Cell Metabolism, Asadi Shahmirzadi et al. (2020) demonstrate that late-onset dietary supplementation with calcium alpha-ketoglutarate results in increased survival, compressed morbidity, and reduced frailty in mice. The study provides further evidence for critical links between metabolism, inflammation, and aging.

DOI: https://doi.org/10.1016/j.cmet.2020.08.009
Am J Physiol Regul Integr Comp Physiol. 2020 Sep 02.

Novel roles of Immunometabolism and Non-Myocyte Metabolism in Cardiac Remodeling and Injury.

Alan J Mouton, John E Hall.

  Changes in cardiomyocyte metabolism have been heavily implicated in cardiac injury and heart failure (HF). However, there is emerging evidence that metabolism in non-myocyte populations, including cardiac fibroblasts, immune cells, and endothelial cells, plays an important role in cardiac remodeling and adaptation to injury. Here, we discuss recent advances and insights into non-myocyte metabolism in the healthy and injured heart. Metabolic switching from mitochondrial oxidative phosphorylation to glycolysis is critical for immune cell (macrophage and T lymphocyte) and fibroblast phenotypic switching in the inflamed and fibrotic heart. On the other hand, cardiac endothelial cells are heavily reliant on glycolytic metabolism, and thus impairments in glycolytic metabolism underlie endothelial cell dysfunction. Finally, we review current and ongoing metabolic therapies for HF and the potential implications for non-myocyte metabolism.

Keywords:  cardiac remodeling; fibrosis; heart failure; inflammation; metabolism

DOI:  https://doi.org/10.1152/ajpregu.00188.2020
Cell Immunol. 2020 Aug 14. pii: S0008-8749(20)30355-5. [Epub ahead of print]357 104195

The hepatic microenvironment and regulatory T cells.

Daniel Osei-Bordom, Amber G Bozward, Ye Htun Oo.

  The human liver is regarded as a lymphoid organ that contributes to both local and systemic immune response. Intrahepatic immune cells including regulatory T cells (Tregs) reside in the hepatic microenvironment which is enriched with proinflammatory cytokines, chemokines and metabolites. In addition, the hepatic microenvironment has the unique ability to establish and maintain immune tolerance despite the continuous influx of the gut derived microbial products via the portal vein. Regulatory T cells play a crucial role in maintaining the hepatic tolerogenic state; however, the phenotypic stability, function and survival of Tregs in the inflamed liver microenvironment is still poorly understood. Despite this, Tregs immunotherapy remains as an appealing therapeutic option in autoimmune and immune mediated liver diseases. In order to advance cell therapy, it is important for us to further our understanding of the hepatic microenvironment, with the aim of developing ways to modify the hostile, inflamed environment to one which is more favourable. By doing so, T cell stability and function would be enhanced, resulting in improved clinical outcomes.

Keywords:  Chemokines; Cytokines; Hepatic microenvironment; Lactic acid; Metabolites; Microbes; Plasticity; Regulatory T cells

DOI:  https://doi.org/10.1016/j.cellimm.2020.104195
Cancer Cell. 2020 Aug 19. pii: S1535-6108(20)30375-5. [Epub ahead of print]

Hematopoietic Progenitor Kinase1 (HPK1) Mediates T Cell Dysfunction and Is a Druggable Target for T Cell-Based Immunotherapies.

Jingwen Si, Xiangjun Shi, Shuhao Sun, Bin Zou, Yaopeng Li, Dongjie An, Xingyu Lin, Yan Gao, Fei Long, Bo Pang, Xing Liu, Tian Liu, Wenna Chi, Ligong Chen, Dimiter S Dimitrov, Yan Sun, Xinru Du, Wen Yin, Guangxun Gao, Junxia Min, Lai Wei, Xuebin Liao.

  Ameliorating T cell exhaustion and enhancing effector function are promising strategies for the improvement of immunotherapies. Here, we show that the HPK1-NFκB-Blimp1 axis mediates T cell dysfunction. High expression of MAP4K1 (which encodes HPK1) correlates with increased T cell exhaustion and with worse patient survival in several cancer types. In MAP4K1KO mice, tumors grow slower than in wild-type mice and infiltrating T cells are less exhausted and more active and proliferative. We further show that genetic depletion, pharmacological inhibition, or proteolysis targeting chimera (PROTAC)-mediated degradation of HPK1 improves the efficacy of CAR-T cell-based immunotherapies in diverse preclinical mouse models of hematological and solid tumors. These strategies are more effective than genetically depleting PD-1 in CAR-T cells. Thus, we demonstrate that HPK1 is a mediator of T cell dysfunction and an attractive druggable target to improve immune therapy responses.

Keywords:  CAR-T; HPK1; PROTACs; T cell exhaustion; cancer immunotherapy

DOI:  https://doi.org/10.1016/j.ccell.2020.08.001
Cell Metab. 2020 Sep 01. pii: S1550-4131(20)30412-5. [Epub ahead of print]32(3): 479-497.e9

A High-Density Human Mitochondrial Proximity Interaction Network.

Hana Antonicka, Zhen-Yuan Lin, Alexandre Janer, Mari J Aaltonen, Woranontee Weraarpachai, Anne-Claude Gingras, Eric A Shoubridge.

  We used BioID, a proximity-dependent biotinylation assay with 100 mitochondrial baits from all mitochondrial sub-compartments, to create a high-resolution human mitochondrial proximity interaction network. We identified 1,465 proteins, producing 15,626 unique high-confidence proximity interactions. Of these, 528 proteins were previously annotated as mitochondrial, nearly half of the mitochondrial proteome defined by Mitocarta 2.0. Bait-bait analysis showed a clear separation of mitochondrial compartments, and correlation analysis among preys across all baits allowed us to identify functional clusters involved in diverse mitochondrial functions and to assign uncharacterized proteins to specific modules. We demonstrate that this analysis can assign isoforms of the same mitochondrial protein to different mitochondrial sub-compartments and show that some proteins may have multiple cellular locations. Outer membrane baits showed specific proximity interactions with cytosolic proteins and proteins in other organellar membranes, suggesting specialization of proteins responsible for contact site formation between mitochondria and individual organelles.

Keywords:  BioID proximity interactions; functional modules; mitochondrial protein proximity map; mitochondrial translation initiation; organellar contact sites; sub-mitochondrial organization

DOI:  https://doi.org/10.1016/j.cmet.2020.07.017
Clin Transl Immunology. 2020 ;9(8): e1167

Resident macrophages as potential therapeutic targets for cardiac ageing and injury.

Shiqing Zhang, Rong Chen, Subrata Chakrabarti, Zhaoliang Su.

  Cardiac-resident macrophages (CRMs) play critical roles in maintaining cardiac homoeostasis and removing senescent and dying cells. Recent preclinical data have re-energised the area of cardioimmunology and provided improved understanding of the modulation of compositional and functional phenotypes of CRMs. These data can aid in achieving improved cardiac regeneration, repair and functional remodelling following cardiac injury. In this review, we discuss the composition and renewal of various subsets of CRMs. Specific attention has been given to delineate the roles of various CRM subsets with respect to (1) facilitation of cardiac development and maintenance of physiological function such as electrical conduction and rhythm; (2) promotion of cardiac regeneration, inflammation resolution and functional remodelling following a cardiac injury; and (3) therapeutic potential. We have also highlighted the relationship between CRM replenishment and cardiomyocyte senescence as well as cardiovascular diseases development. Finally, we have addressed future perspectives and directions in basic research and potentially clinical applications of CRMs.

Keywords:  cardiac development; cardiac injury; cardiac regeneration; cardiac‐resident macrophages; cardiomyocyte senescence

DOI:  https://doi.org/10.1002/cti2.1167
Cell Metab. 2020 Sep 01. pii: S1550-4131(20)30417-4. [Epub ahead of print]32(3): 447-456.e6

Alpha-Ketoglutarate, an Endogenous Metabolite, Extends Lifespan and Compresses Morbidity in Aging Mice.

Azar Asadi Shahmirzadi, Daniel Edgar, Chen-Yu Liao, Yueh-Mei Hsu, Mark Lucanic, Arash Asadi Shahmirzadi, Christopher D Wiley, Garbo Gan, Dong Eun Kim, Herbert G Kasler, Chisaka Kuehnemann, Brian Kaplowitz, Dipa Bhaumik, Rebeccah R Riley, Brian K Kennedy, Gordon J Lithgow.

  Metabolism and aging are tightly connected. Alpha-ketoglutarate is a key metabolite in the tricarboxylic acid (TCA) cycle, and its levels change upon fasting, exercise, and aging. Here, we investigate the effect of alpha-ketoglutarate (delivered in the form of a calcium salt, CaAKG) on healthspan and lifespan in C57BL/6 mice. To probe the relationship between healthspan and lifespan extension in mammals, we performed a series of longitudinal, clinically relevant measurements. We find that CaAKG promotes a longer, healthier life associated with a decrease in levels of systemic inflammatory cytokines. We propose that induction of IL-10 by dietary AKG suppresses chronic inflammation, leading to health benefits. By simultaneously reducing frailty and enhancing longevity, AKG, at least in the murine model, results in a compression of morbidity.

Keywords:  IL-10; SASP; alpha-ketoglutarate; frailty; healthspan; inflammation; lifespan; longevity

DOI:  https://doi.org/10.1016/j.cmet.2020.08.004
Cancer Immunol Res. 2020 Jul 27.

Bispecific Targeting of PD-1 and PD-L1 Enhances T-cell Activation and Antitumor Immunity.

Helen Kotanides, Yiwen Li, Maria Malabunga, Carmine Carpenito, Scott W Eastman, Yang Shen, George Wang, Ivan Inigo, David Surguladze, Anthony L Pennello, Krishnadatt Persaud, Sagit Hindi, Michael Topper, Xinlei Chen, Yiwei Zhang, Danielle K Bulaon, Tim Bailey, Yanbin Lao, Bing Han, Stacy Torgerson, Darin Chin, Andreas Sonyi, Jaafar N Haidar, Ruslan D Novosiadly, Christopher M Moxham, Gregory D Plowman, Dale L Ludwig, Michael Kalos.

The programmed cell death protein 1 receptor (PD-1) and programmed death ligand 1 (PD-L1) coinhibitory pathway suppresses T-cell-mediated immunity. We hypothesized that cotargeting of PD-1 and PD-L1 with a bispecific antibody molecule could provide an alternative therapeutic approach, with enhanced antitumor activity, compared with monospecific PD-1 and PD-L1 antibodies. Here, we describe LY3434172, a bispecific IgG1 mAb with ablated Fc immune effector function that targets both human PD-1 and PD-L1. LY3434172 fully inhibited the major inhibitory receptor-ligand interactions in the PD-1 pathway. LY3434172 enhanced functional activation of T cells in vitro compared with the parent anti-PD-1 and anti-PD-L1 antibody combination or respective monotherapies. In mouse tumor models reconstituted with human immune cells, LY3434172 therapy induced dramatic and potent antitumor activity compared with each parent antibody or their combination. Collectively, these results demonstrated the enhanced immunomodulatory (immune blockade) properties of LY3434172, which improved antitumor immune response in preclinical studies, thus supporting its evaluation as a novel bispecific cancer immunotherapy.

DOI: https://doi.org/10.1158/2326-6066.CIR-20-0304
Cell Metab. 2020 Sep 01. pii: S1550-4131(20)30421-6. [Epub ahead of print]32(3): 321-323

Microenvironmental Aspartate Preserves Leukemic Cells from Therapy-Induced Metabolic Collapse.

Lucille Stuani, Jean-Emmanuel Sarry.

Metabolic dialogue between tumors and their microenvironment emerges as a key regulator of chemoresistance, the major barrier for the treatment of several cancers. In this issue of Cell Metabolism, van Gastel et al. decipher the pivotal role of stromal glutamine-derived aspartate to sustain pyrimidine biosynthesis in chemoresistant acute myeloid leukemia (AML) and thus state it as a target for anti-cancer therapy.

DOI: https://doi.org/10.1016/j.cmet.2020.08.008
Mol Cancer Ther. 2020 Sep 02. pii: molcanther.0423.2020. [Epub ahead of print]

Therapeutic Targeting of Mitochondrial One-Carbon Metabolism in Cancer.

Aamod S Dekhne, Zhanjun Hou, Aleem Gangjee, Larry H Matherly.

One-carbon (1C) metabolism encompasses folate-mediated 1C transfer reactions and related processes, including nucleotide and amino acid biosynthesis, antioxidant regeneration, and epigenetic regulation. 1C pathways are compartmentalized in the cytosol, mitochondria and nucleus. 1C metabolism in the cytosol has been an important therapeutic target for cancer since the inception of modern chemotherapy and "antifolates" targeting cytosolic 1C pathways continue to be a mainstay of the chemotherapy armamentarium for cancer. Recent insights into the complexities of 1C metabolism in cancer cells, including the critical role of the mitochondrial 1C pathway as a source of 1C units, glycine, reducing equivalents, and ATP, have spurred the discovery of novel compounds that target these reactions, with particular focus on 5,10-methylene tetrahydrofolate dehydrogenase 2 and serine hydroxymethyltransferase 2. In this review, we discuss key aspects of 1C metabolism, with emphasis on the importance of mitochondrial 1C metabolism to metabolic homeostasis, and its relationship to the oncogenic phenotype and therapeutic potential for cancer.

DOI: https://doi.org/10.1158/1535-7163.MCT-20-0423
Exp Mol Med. 2020 Sep 04.

Heterochromatin: an epigenetic point of view in aging.

Jong-Hyuk Lee, Edward W Kim, Deborah L Croteau, Vilhelm A Bohr.

Aging is an inevitable process of life. Defined by progressive physiological and functional loss of tissues and organs, aging increases the risk of mortality for the organism. The aging process is affected by various factors, including genetic and epigenetic ones. Here, we review the chromatin-specific epigenetic changes that occur during normal (chronological) aging and in premature aging diseases. Taking advantage of the reversible nature of epigenetic modifications, we will also discuss possible lifespan expansion strategies through epigenetic modulation, which was considered irreversible until recently.

DOI: https://doi.org/10.1038/s12276-020-00497-4
J Immunother Cancer. 2020 Aug;pii: e000692. [Epub ahead of print]8(2):

IFN-γ treatment protocol for MHC-Ilo/PD-L1+ pancreatic tumor cells selectively restores their TAP-mediated presentation competence and CD8 T-cell priming potential.

Katja Stifter, Jana Krieger, Leonie Ruths, Johann Gout, Medhanie Mulaw, Andre Lechel, Alexander Kleger, Thomas Seufferlein, Martin Wagner, Reinhold Schirmbeck.

   BACKGROUND: Many cancer cells express a major histocompatibility complex class I low/ programmed cell death 1 ligand 1 positive (MHC-Ilo/PD-L1+) cell surface profile. For immunotherapy, there is, thus, an urgent need to restore presentation competence of cancer cells with defects in MHC-I processing/presentation combined with immune interventions that tackle the tumor-initiated PD-L1/PD-1 signaling axis. Using pancreatic ductal adenocarcinoma cells (PDACCs) as a model, we here explored if (and how) expression/processing of tumor antigens via transporters associated with antigen processing (TAP) affects priming of CD8 T cells in PD-1/PD-L1-competent/-deficient mice.
METHODS: We generated tumor antigen-expressing vectors, immunized TAP-competent/-deficient mice and determined de novo primed CD8 T-cell frequencies by flow cytometry. Similarly, we explored the antigenicity and PD-L1/PD-1 sensitivity of PDACCs versus interferon-γ (IFN-γ)-treated PDACCs in PD-1/PD-L1-competent/deficient mice. The IFN-γ-induced effects on gene and cell surface expression profiles were determined by microarrays and flow cytometry.
RESULTS: We identified two antigens (cripto-1 and an endogenous leukemia virus-derived gp70) that were expressed in the Endoplasmic Reticulum (ER) of PDACCs and induced CD8 T-cell responses either independent (Cripto-1:Kb/Cr16-24) or dependent (gp70:Kb/p15E) on TAP by DNA immunization. IFN-γ-treatment of PDACCs in vitro upregulated MHC-I- and TAP- but also PD-L1-expression. Mechanistically, PD-L1/PD-1 signaling was superior to the reconstitution of MHC-I presentation competence, as subcutaneously transplanted IFN-γ-treated PDACCs developed tumors in C57BL/6J and PD-L1-/- but not in PD-1-/- mice. Using PDACCs, irradiated at day 3 post-IFN-γ-treatment or PD-L1 knockout PDACCs as vaccines, we could selectively bypass upregulation of PD-L1, preferentially induce TAP-dependent gp70:Kb/p15E-specific CD8 T cells associated with a weakened PD-1+ exhaustion phenotype and reject consecutively injected tumor transplants in C57BL/6J mice.
CONCLUSIONS: The IFN-γ-treatment protocol is attractive for cell-based immunotherapies, because it restores TAP-dependent antigen processing in cancer cells, facilitates priming of TAP-dependent effector CD8 T-cell responses without additional check point inhibitors and could be combined with genetic vaccines that complement priming of TAP-independent CD8 T cells.

Keywords:  B7-H1 antigen; CD8-positive T-lymphocytes; antigen presentation; gastrointestinal neoplasms; immunogenicity; vaccine

DOI:  https://doi.org/10.1136/jitc-2020-000692
EMBO Mol Med. 2020 Aug 16. e12423

Dietary magnesium supplementation improves lifespan in a mouse model of progeria.

Ricardo Villa-Bellosta.

  Aging is associated with redox imbalance according to the redox theory of aging. Consistently, a mouse model of premature aging (LmnaG609G/+) showed an increased level of mitochondrial reactive oxygen species (ROS) and a reduced basal antioxidant capacity, including loss of the NADPH-coupled glutathione redox system. LmnaG609G/+ mice also exhibited reduced mitochondrial ATP synthesis secondary to ROS-induced mitochondrial dysfunction. Treatment of LmnaG609G/+ vascular smooth muscle cells with magnesium-enriched medium improved the intracellular ATP level, enhanced the antioxidant capacity, and thereby reduced mitochondrial ROS production. Moreover, treatment of LmnaG609G/+ mice with dietary magnesium improved the proton pumps (complexes I, III, and IV), stimulated extramitochondrial NADH oxidation and enhanced the coupled mitochondrial membrane potential, and thereby increased H+-coupled mitochondrial NADPH and ATP synthesis, which is necessary for cellular energy supply and survival. Consistently, magnesium treatment reduced calcification of vascular smooth muscle cells in vitro and in vivo, and improved the longevity of mice. This antioxidant property of magnesium may be beneficial in children with HGPS.

Keywords:  HGPS; aging; magnesium; progeria; vascular calcification

DOI:  https://doi.org/10.15252/emmm.202012423