bims-imseme Biomed News
on Immunosenescence and T cell metabolism
Issue of 2020‒08‒30
27 papers selected by
Pierpaolo Ginefra
Ludwig Institute for Cancer Research

  1. Immunol Rev. 2020 Aug 24.
    Suzuki T, Hayman L, Kilbey A, Edwards J, Coffelt SB.
      Colorectal cancer is the third most common cancer worldwide with nearly 2 million cases per year. Immune cells and inflammation are a critical component of colorectal cancer progression, and they are used as reliable prognostic indicators of patient outcome. With the growing appreciation for immunology in colorectal cancer, interest is growing on the role γδ T cells have to play, as they represent one of the most prominent immune cell populations in gut tissue. This group of cells consists of both resident populations-γδ intraepithelial lymphocytes (γδ IELs)-and transient populations that each has unique functions. The homeostatic role of these γδ T cell subsets is to maintain barrier integrity and prevent microorganisms from breaching the mucosal layer, which is accomplished through crosstalk with enterocytes and other immune cells. Recent years have seen a surge in discoveries regarding the regulation of γδ IELs in the intestine and the colon with particular new insights into the butyrophilin family. In this review, we discuss the development, specialities, and functions of γδ T cell subsets during cancer progression. We discuss how these cells may be used to predict patient outcome, as well as how to exploit their behavior for cancer immunotherapy.
    Keywords:  IL-17; colorectal cancer; gut; intestine; intraepithelial lymphocyte; γδ T cells
  2. Int Rev Neurobiol. 2020 ;pii: S0074-7742(20)30050-7. [Epub ahead of print]155 203-234
    Wissler Gerdes EO, Zhu Y, Weigand BM, Tripathi U, Burns TC, Tchkonia T, Kirkland JL.
      Aging is the major predictor for developing multiple neurodegenerative diseases, including Alzheimer's disease (AD) other dementias, and Parkinson's disease (PD). Senescent cells, which can drive aging phenotypes, accumulate at etiological sites of many age-related chronic diseases. These cells are resistant to apoptosis and can cause local and systemic dysfunction. Decreasing senescent cell abundance using senolytic drugs, agents that selectively target these cells, alleviates neurodegenerative diseases in preclinical models. In this review, we consider roles of senescent cells in neurodegenerative diseases and potential implications of senolytic agents as an innovative treatment.
    Keywords:  Alzheimer's disease; Cellular senescence; Dasatinib; Fisetin; Navitoclax; Parkinson's disease; Quercetin; Senescence-associated secretory phenotype; Senescent cell anti-apoptotic pathways; Senolytics
  3. Immunol Cell Biol. 2020 Aug 25.
    Hajdu KL, Bonamino MH.
      We discuss in this News and Commentary article the implications of senolytic chimeric antigen receptor T cells.
  4. Exp Mol Med. 2020 Aug 28.
    Kim SY, Yang EJ, Lee SB, Lee YS, Cho KA, Park SC.
      Nucleocytoplasmic trafficking (NCT) of macromolecules is a fundamental process in eukaryotes that requires tight controls to maintain proper cell functions. Downregulation of the classical NCT pathway in senescent cells has been reported. However, whether this is a hallmark that exists across all types of cellular senescence remains unknown, and whether the mRNA export machinery is altered during senescence has not been demonstrated. Here, we show that the global transcriptomic downregulation of both the TREX (transcription-export) machinery and classical NLS-dependent protein transport machinery is a hallmark of varying types of senescence. A gene set-based approach using 25 different studies showed that the TREX-NCT gene set displays distinct common downregulated patterns in senescent cells versus its expression in their nonsenescent counterparts regardless of the senescence type, such as replicative senescence (RS), tumor cell senescence (TCS), oncogene-induced senescence (OIS), stem cell senescence (SCS), progeria and endothelial cell senescence (ECS). Similar patterns of TREX-NCT gene downregulation were also shown in two large human tissue genomic databases, the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases. We also found that early-stage cancer tissues show consistent age-related patterns of TREX-NCT enrichment, suggesting the potential significance of TREX-NCT genes in determining cell fate in the early stage of tumorigenesis. Moreover, human cancer tissues exhibit an opposite TREX-NCT enrichment pattern with aging, indicating that deviation from age-related changes in TREX-NCT genes may provide a novel but critical clue for the age-dependent pathogenesis of cancer and increase in cancer incidence with aging.
  5. Nat Immunol. 2020 Aug 24.
    Utzschneider DT, Gabriel SS, Chisanga D, Gloury R, Gubser PM, Vasanthakumar A, Shi W, Kallies A.
      CD8+ T cells responding to chronic infections or tumors acquire an 'exhausted' state associated with elevated expression of inhibitory receptors, including PD-1, and impaired cytokine production. Exhausted T cells are continuously replenished by T cells with precursor characteristics that self-renew and depend on the transcription factor TCF1; however, their developmental requirements are poorly understood. In the present study, we demonstrate that high antigen load promoted the differentiation of precursor T cells, which acquired hallmarks of exhaustion within days of infection, whereas early effector cells retained polyfunctional features. Early precursor T cells showed epigenetic imprinting characteristic of T cell receptor-dependent transcription factor binding and were restricted to the generation of cells displaying exhaustion characteristics. Transcription factors BACH2 and BATF were key regulators with opposing functions in the generation of early precursor T cells. Overall, we demonstrate that exhaustion manifests first in TCF1+ precursor T cells and is propagated subsequently to the pool of antigen-specific T cells.
  6. Front Immunol. 2020 ;11 1528
    P P, Tomar A, Madhwal S, Mukherjee T.
      A large body of research implicates the brain and fat body (liver equivalent) as central players in coordinating growth and nutritional homeostasis in multicellular animals. In this regard, an underlying connection between immune cells and growth is also evident, although mechanistic understanding of this cross-talk is scarce. Here, we explore the importance of innate immune cells in animal growth during homeostasis and in conditions of nutrient stress. We report that Drosophila larvae lacking blood cells eclose as small adults and show signs of insulin insensitivity. Moreover, when exposed to dietary stress of a high-sucrose diet (HSD), these animals are further growth retarded than normally seen in regular animals raised on HSD. In contrast, larvae carrying increased number of activated macrophage-like plasmatocytes show no defects in adult growth when raised on HSD and grow to sizes almost comparable with that seen with regular diet. These observations imply a central role for immune cell activity in growth control. Mechanistically, our findings reveal a surprising influence of immune cells on balancing fat body inflammation and insulin signaling under conditions of homeostasis and nutrient overload as a means to coordinate systemic metabolism and adult growth. This work integrates both the cellular and humoral arm of the innate immune system in organismal growth homeostasis, the implications of which may be broadly conserved across mammalian systems as well.
    Keywords:  high sugar; inflammation; innate immunity; insulin; metabolism; myeloid cells; stress
  7. Cold Spring Harb Perspect Biol. 2020 Aug 24. pii: a037796. [Epub ahead of print]
    Parga-Vidal L, van Gisbergen KPJM.
      Immunological memory, defined as the ability to respond in an enhanced manner upon secondary encounter with the same pathogen, can provide substantial protection against infectious disease. The improved protection is mediated in part by different populations of memory CD8 T cells that are retained after primary infection. Memory cells persist in the absence of pathogen-derived antigens and enable secondary CD8 T-cell responses with accelerated kinetics and of larger magnitude after reencounter with the same pathogen. At least three subsets of memory T cells have been defined that are referred to as central memory CD8 T cells (Tcm), effector memory CD8 T cells (Tem), and tissue-resident memory CD8 T cells (Trm). Tcm and Tem are circulating memory T cells that mediate bodywide immune surveillance in search of invading pathogens. In contrast, Trm permanently reside in peripheral barrier tissues, where they form a stationary defensive line of sentinels that alert the immune system upon pathogen reencounter. The characterization of these different subsets has been instrumental in our understanding of the strategies that memory T cells employ to counter invading pathogens. It is clear that memory T cells not only have a numerical advantage over naive T cells resulting in improved protection in secondary responses, but also acquire distinct sets of competencies that assist in pathogen clearance. Nevertheless, inherent challenges are associated with the allocation of memory T cells to a limited number of subsets. The classification of memory T cells into Tcm, Tem, and Trm may not take into account the full extent of the heterogeneity that is observed in the memory population. Therefore, in this review, we will revisit the current classification of memory subsets, elaborate on functional and migratory properties attributed to Tcm, Tem, and Trm, and discuss how potential heterogeneity within these populations arises and persists.
  8. Cell Rep. 2020 Aug 25. pii: S2211-1247(20)31063-9. [Epub ahead of print]32(8): 108078
    Sandu I, Cerletti D, Oetiker N, Borsa M, Wagen F, Spadafora I, Welten SPM, Stolz U, Oxenius A, Claassen M.
      A hallmark of chronic infections is the presence of exhausted CD8 T cells, characterized by a distinct transcriptional program compared with functional effector or memory cells, co-expression of multiple inhibitory receptors, and impaired effector function, mainly driven by recurrent T cell receptor engagement. In the context of chronic lymphocytic choriomeningitis virus (LCMV) infection in mice, most studies focused on studying splenic virus-specific CD8 T cells. Here, we provide a detailed characterization of exhausted CD8 T cells isolated from six different tissues during established LCMV infection, using single-cell RNA sequencing. Our data reveal that exhausted cells are heterogeneous, adopt organ-specific transcriptomic profiles, and can be divided into five main functional subpopulations: advanced exhaustion, effector-like, intermediate, proliferating, or memory-like. Adoptive transfer experiments showed that these phenotypes are plastic, suggesting that the tissue microenvironment has a major impact in shaping the phenotype and function of virus-specific CD8 T cells during chronic infection.
    Keywords:  CD8 T cells; chronic viral infection; phenotypic plasticity; singe cell RNA sequencing; tissue-specific phenotypes
  9. Nat Metab. 2020 Aug 24.
    Li L, Chen K, Wang T, Wu Y, Xing G, Chen M, Hao Z, Zhang C, Zhang J, Ma B, Liu Z, Yuan H, Liu Z, Long Q, Zhou Y, Qi J, Zhao D, Gao M, Pei D, Nie J, Ye D, Pan G, Liu X.
      Somatic cell reprogramming provides insight into basic principles of cell fate determination, which remain poorly understood. Here we show that the transcription factor Glis1 induces multi-level epigenetic and metabolic remodelling in stem cells that facilitates the induction of pluripotency. We find that Glis1 enables reprogramming of senescent cells into pluripotent cells and improves genome stability. During early phases of reprogramming, Glis1 directly binds to and opens chromatin at glycolytic genes, whereas it closes chromatin at somatic genes to upregulate glycolysis. Subsequently, higher glycolytic flux enhances cellular acetyl-CoA and lactate levels, thereby enhancing acetylation (H3K27Ac) and lactylation (H3K18la) at so-called 'second-wave' and pluripotency gene loci, opening them up to facilitate cellular reprogramming. Our work highlights Glis1 as a powerful reprogramming factor, and reveals an epigenome-metabolome-epigenome signalling cascade that involves the glycolysis-driven coordination of histone acetylation and lactylation in the context of cell fate determination.
  10. Proc Natl Acad Sci U S A. 2020 Aug 26. pii: 201921930. [Epub ahead of print]
    McIntyre CL, Monin L, Rop JC, Otto TD, Goodyear CS, Hayday AC, Morrison VL.
      The γδ T cells reside predominantly at barrier sites and play essential roles in immune protection against infection and cancer. Despite recent advances in the development of γδ T cell immunotherapy, our understanding of the basic biology of these cells, including how their numbers are regulated in vivo, remains poor. This is particularly true for tissue-resident γδ T cells. We have identified the β2 family of integrins as regulators of γδ T cells. β2-integrin-deficient mice displayed a striking increase in numbers of IL-17-producing Vγ6Vδ1+ γδ T cells in the lungs, uterus, and circulation. Thymic development of this population was normal. However, single-cell RNA sequencing revealed the enrichment of genes associated with T cell survival and proliferation specifically in β2-integrin-deficient IL-17+ cells compared to their wild-type counterparts. Indeed, β2-integrin-deficient Vγ6+ cells from the lungs showed reduced apoptosis ex vivo, suggesting that increased survival contributes to the accumulation of these cells in β2-integrin-deficient tissues. Furthermore, our data revealed an unexpected role for β2 integrins in promoting the thymic development of the IFNγ-producing CD27+ Vγ4+ γδ T cell subset. Together, our data reveal that β2 integrins are important regulators of γδ T cell homeostasis, inhibiting the survival of IL-17-producing Vγ6Vδ1+ cells and promoting the thymic development of the IFNγ-producing Vγ4+ subset. Our study introduces unprecedented mechanisms of control for γδ T cell subsets.
    Keywords:  immune homeostasis; β2 integrins; γδ T cells
  11. Immunol Cell Biol. 2020 Aug 25.
    Gubser PM, Kallies A.
      Tumor cells steal methionine from CD8 T cells. High expression of the methionine transporters SLC7A5 and SLC43A2 allows tumor cells to outcompete CD8 T cells for methionine uptake. Lower methionine concentrations in CD8 T cells lead to reduced levels of dimethylated H3K79, an active epigenetic mark, which in turn results in reduced STAT5 expression and activity.
  12. Nat Commun. 2020 Aug 27. 11(1): 4289
    Iske J, Seyda M, Heinbokel T, Maenosono R, Minami K, Nian Y, Quante M, Falk CS, Azuma H, Martin F, Passos JF, Niemann CU, Tchkonia T, Kirkland JL, Elkhal A, Tullius SG.
      Older organs represent an untapped potential to close the gap between demand and supply in organ transplantation but are associated with age-specific responses to injury and increased immunogenicity, thereby aggravating transplant outcomes. Here we show that cell-free mitochondrial DNA (cf-mt-DNA) released by senescent cells accumulates with aging and augments immunogenicity. Ischemia reperfusion injury induces a systemic increase of cf-mt-DNA that promotes dendritic cell-mediated, age-specific inflammatory responses. Comparable events are observed clinically, with the levels of cf-mt-DNA elevated in older deceased organ donors, and with the isolated cf-mt-DNA capable of activating human dendritic cells. In experimental models, treatment of old donor animals with senolytics clear senescent cells and diminish cf-mt-DNA release, thereby dampening age-specific immune responses and prolonging the survival of old cardiac allografts comparable to young donor organs. Collectively, we identify accumulating cf-mt-DNA as a key factor in inflamm-aging and present senolytics as a potential approach to improve transplant outcomes and availability.
  13. Int J Mol Sci. 2020 Aug 25. pii: E6118. [Epub ahead of print]21(17):
    Szczypka M.
      Phosphodiesterase 7 (PDE7), a cAMP-specific PDE family, insensitive to rolipram, is present in many immune cells, including T lymphocytes. Two genes of PDE7 have been identified: PDE7A and PDE7B with three or four splice variants, respectively. Both PDE7A and PDE7B are expressed in T cells, and the predominant splice variant in these cells is PDE7A1. PDE7 is one of several PDE families that terminates biological functions of cAMP-a major regulating intracellular factor. However, the precise role of PDE7 in T cell activation and function is still ambiguous. Some authors reported its crucial role in T cell activation, while according to other studies PDE7 activity was not pivotal to T cells. Several studies showed that inhibition of PDE7 by its selective or dual PDE4/7 inhibitors suppresses T cell activity, and consequently T-mediated immune response. Taken together, it seems quite likely that simultaneous inhibition of PDE4 and PDE7 by dual PDE4/7 inhibitors or a combination of selective PDE4 and PDE7 remains the most interesting therapeutic target for the treatment of some immune-related disorders, such as autoimmune diseases, or selected respiratory diseases. An interesting direction of future studies could also be using a combination of selective PDE7 and PDE3 inhibitors.
    Keywords:  PDE7; T cells; allergic and autoimmune diseases; families of PDE; intracellular cAMP; phosphodiesterase 7; selective PDE inhibitors
  14. J Immunol. 2020 Aug 24. pii: ji1901480. [Epub ahead of print]
    Vallion R, Divoux J, Glauzy S, Ronin E, Lombardi Y, Lubrano di Ricco M, Grégoire S, Nemazanyy I, Durand A, Fradin D, Lucas B, Salomon BL.
      CD4+ Foxp3+ regulatory T cells (Treg) are essential to maintain immune tolerance, as their loss leads to a fatal autoimmune syndrome in mice and humans. Conflicting findings have been reported concerning their metabolism. Some reports found that Treg have low mechanistic target of rapamycin (mTOR) activity and would be less dependent on this kinase compared with conventional T cells, whereas other reports suggest quite the opposite. In this study, we revisited this question by using mice that have a specific deletion of mTOR in Treg. These mice spontaneously develop a severe and systemic inflammation. We show that mTOR expression by Treg is critical for their differentiation into effector Treg and their migration into nonlymphoid tissues. We also reveal that mTOR-deficient Treg have reduced stability. This loss of Foxp3 expression is associated with partial Foxp3 DNA remethylation, which may be due to an increased activity of the glutaminolysis pathway. Thus, our work shows that mTOR is crucial for Treg differentiation, migration, and identity and that drugs targeting this metabolism pathway will impact on their biology.
  15. Curr Opin Pharmacol. 2020 Aug 24. pii: S1471-4892(20)30040-0. [Epub ahead of print]53 91-97
    Sek K, Kats LM, Darcy PK, Beavis PA.
      Adoptive cellular therapy involves the ex vivo expansion of immune cells, conventionally T cells, before reinfusion back to the patient. Variations in adoptive cellular therapy include transduction of a patient's T cells with either a transgenic T cell receptor or chimeric antigen receptor (CAR) to recognize a defined tumor antigen. Given that adenosine is a major axis of immunosuppression of T cells, particularly in hypoxic tumor microenvironments, therapeutics targeting this pathway are currently being assessed for their potential to enhance adoptive T cell therapies. The use of gene-editing technology, commonly used in tandem with CAR and transgenic T cell receptor (TCR) based adoptive cellular therapy, offers further opportunities to specifically modulate responses to adenosine. This review will discuss recent advances in targeting the adenosine pathway for enhancing the effectiveness of adoptive cellular therapy in the treatment of solid cancers.
  16. Elife. 2020 Aug 25. pii: e56221. [Epub ahead of print]9
    Baran-Gale J, Morgan MD, Maio S, Dhalla F, Calvo-Asensio I, Deadman ME, Handel AE, Maynard A, Chen S, Green F, Sit RV, Neff NF, Darmanis S, Tan W, May AP, Marioni JC, Ponting CP, Holländer GA.
      Ageing is characterised by cellular senescence, leading to imbalanced tissue maintenance, cell death and compromised organ function. This is first observed in the thymus, the primary lymphoid organ that generates and selects T cells. However, the molecular and cellular mechanisms underpinning these ageing processes remain unclear. Here, we show that mouse ageing leads to less efficient T cell selection, decreased self-antigen representation and increased T cell receptor repertoire diversity. Using a combination of single-cell RNA-seq and lineage-tracing, we find that progenitor cells are the principal targets of ageing, whereas the function of individual mature thymic epithelial cells is compromised only modestly. Specifically, an early-life precursor cell population, retained in the mouse cortex postnatally, is virtually extinguished at puberty. Concomitantly, a medullary precursor cell quiesces, thereby impairing maintenance of the medullary epithelium. Thus, ageing disrupts thymic progenitor differentiation and impairs the core immunological functions of the thymus.
    Keywords:  immunology; inflammation; mouse
  17. Med Princ Pract. 2020 Aug 25.
    Jain KK.
      Cancer immunotherapy aims to control the immune system to eradicate cancer cells and prevent their spread. It needs to be personalized because anticancer immune responses can be inhibited in several ways which vary from patient to patient. Therapeutic approaches to cancer immunotherapy include pharmaceuticals such as immune checkpoint inhibitors (ICIs) and monoclonal antibodies (MAbs). Non-pharmaceutical approaches include cell-based and immunogene therapy as well as vaccines. Combination of PD-1/PD-L1 drugs with other immunotherapy drugs, e.g., antibody-drug conjugates (ADCs), are as well as with other therapies, e.g., chemotherapy, and radiation therapy are also being explored. Biomarkers are important for predicting response to immunotherapy. Levels of tumor-infiltrating lymphocytes (TILs) are being correlated with clinicopathological features in determining prognosis of different malignancies. Tumor organoids may enable evaluation of response to therapy to select patients who are likely to respond to immunotherapy and avoid treatment-related complications in non-responders. Molecular diagnostics and sequencing are important technologies for guiding treatment in immuno-oncology. Genomic profiling of tumor mutational burden (TMB) may enhance the predictive utility of PD-L1 expression and facilitate personalized combination immunotherapy approaches. Optimization of personalized immuno-oncology requires integration of several technologies and selection of those best suited for an individual patient. Advances in immuno-oncology are attributed to progress in immunology of cancer, availability of biological therapies for cancer and technologies for targeted delivery of anticancer therapeutics such as antigen-capturing nanoparticles for precision targeted and selective delivery of immunotherapy. A breakthrough in cell therapy of cancer is a chimeric antigen receptors (CAR)-T cell, which combines the antigen binding site of a MAb with the signal activating machinery of a T cell, freeing antigen recognition from major histocompatibility complex (MHC) restriction. Cancer vaccines have a high failure rate in clinical trials but gene-editing tools, such as clustered regularly interspaced short palindromic repeats (CRISPR) have a promising application for removing alloreactivity and decreasing immunogenicity of third-party T cells. In conclusion, immuno-oncology, one of the most promising approaches to management of cancer fits in well with the principles of personalized medicine.
  18. J Allergy Clin Immunol. 2020 Aug 24. pii: S0091-6749(20)31173-8. [Epub ahead of print]
    Longo VD, Cortellino S.
    Keywords:  dietary intervention; exhausted T cell; hematopoietic stem cell; inflammation; metabolism
  19. Med Res Rev. 2020 Aug 25.
    Hossain MA, Liu G, Dai B, Si Y, Yang Q, Wazir J, Birnbaumer L, Yang Y.
      Immunotherapy has revolutionized the treatment of cancer in recent years and achieved overall success and long-term clinical benefit in patients with a wide variety of cancer types. However, there is still a large proportion of patients exhibiting limited or no responses to immunotherapeutic strategy, some of which were even observed with hyperprogressive disease. One major obstacle restricting the efficacy is that tumor-reactive CD8+ T cells, which are central for tumor control, undergo exhaustion, and lose their ability to eliminate cancer cells after infiltrating into the strongly immunosuppressive tumor microenvironment. Thus, as a potential therapeutic rationale in the development of cancer immunotherapy, targeting or reinvigorating exhausted CD8+ T cells has been attracting much interest. Hitherto, both intrinsic and extrinsic mechanisms that govern CD8+ T-cell exhaustion have been explored. Specifically, the transcriptional and epigenetic landscapes have been depicted utilizing single-cell RNA sequencing or mass cytometry (CyTOF). In addition, cellular metabolism dictating the tumor-infiltrating CD8+ T-cell fate is currently under investigation. A series of clinical trials are being carried out to further establish the current strategies targeting CD8+ T-cell exhaustion. Taken together, despite the proven benefit of immunotherapy in cancer patients, additional efforts are still needed to fully circumvent limitations of exhausted T cells in the treatment. In this review, we will focus on the current cellular and molecular understanding of metabolic changes, epigenetic remodeling, and transcriptional regulation in CD8+ T-cell exhaustion and describe hypothetical treatment approaches based on immunotherapy aiming at reinvigorating exhausted CD8+ T cells.
    Keywords:  T-cell exhaustion; cancer immunotherapy; immune checkpoint inhibitors I immunometabolism; transcription factor
  20. Nat Rev Immunol. 2020 Aug 24.
    Certo M, Tsai CH, Pucino V, Ho PC, Mauro C.
      The microenvironment in cancerous tissues is immunosuppressive and pro-tumorigenic, whereas the microenvironment of tissues affected by chronic inflammatory disease is pro-inflammatory and anti-resolution. Despite these opposing immunological states, the metabolic states in the tissue microenvironments of cancer and inflammatory diseases are similar: both are hypoxic, show elevated levels of lactate and other metabolic by-products and have low levels of nutrients. In this Review, we describe how the bioavailability of lactate differs in the microenvironments of tumours and inflammatory diseases compared with normal tissues, thus contributing to the establishment of specific immunological states in disease. A clear understanding of the metabolic signature of tumours and inflammatory diseases will enable therapeutic intervention aimed at resetting the bioavailability of metabolites and correcting the dysregulated immunological state, triggering beneficial cytotoxic, inflammatory responses in tumours and immunosuppressive responses in chronic inflammation.
  21. Front Immunol. 2020 ;11 1711
    Van Herck MA, Vonghia L, Kwanten WJ, Vanwolleghem T, Ebo DG, Michielsen PP, De Man JG, Gama L, De Winter BY, Francque SM.
      Background and Aims: Non-alcoholic steatohepatitis (NASH) is a multisystem condition, involving the liver, adipose tissue, and immune system. Regulatory T (Treg) cells are a subset of T cells that exert an immune-controlling effect. Previously, a reduction of Treg cells in the visceral adipose tissue (VAT) was shown to be associated with a more severe degree of liver disease. We aimed to correct this immune disruption through adoptive cell transfer (ACT) of Treg cells. Methods: Male 8-week-old C57BL/6J mice were fed a high-fat high-fructose diet (HFHFD) for 20 weeks. Treg cells were isolated from the spleens of healthy 8 to 10-week-old C57BL/6J mice and were adoptively transferred to HFHFD-fed mice. PBS-injected mice served as controls. Plasma ALT and lipid levels were determined. Liver and adipose tissue were assessed histologically. Cytotoxic T (Tc), Treg, T helper (Th) 1 and Th17 cells were characterized in VAT, liver, subcutaneous adipose tissue (SAT), blood, and spleen via flow cytometry. Gene expression analysis was performed in SAT and VAT of mice fed either the HFHFD or a control diet for 10-32 weeks. Results: ACT increased Treg cells in SAT, but not in any of the other tissues. Moreover, the ACT induced a decrease in Th1 cells in SAT, liver, blood, and spleen. Higher plasma ALT levels and a higher degree of steatosis were observed in ACT mice, whereas the other HFHFD-induced metabolic and histologic disruptions were unaffected. Expression analysis of genes related to Treg-cell proliferation revealed a HFHFD-induced decrease in all investigated genes in the SAT, while in the VAT the expression of these genes was largely unaffected, except for a decrease in Pparg. Conclusion: ACT of Treg cells in HFHFD-fed mice exacerbated hepatic steatosis, which was possibly related to the increase of Treg cells in the SAT and/or the general decrease in Th1 cells. Moreover, the HFHFD-induced decrease in Pparg expression appeared critical in the decrease of Treg cells at the level of the VAT and the inability to replenish the amount of Treg cells by the ACT, while the mechanism of Treg cell accumulation at the level of the SAT remained unclear.
    Keywords:  PPAR-γ; T helper 1 cells; adipose tissue inflammation; adoptive cell transfer; non-alcoholic steatohepatitis; regulatory T cells
  22. Carcinogenesis. 2020 Aug 24. pii: bgaa092. [Epub ahead of print]
    Chatterjee S, Chatterjee A, Jana S, Dey S, Roy H, Das MK, Alam J, Adhikary A, Chowdhury A, Biswas A, Manna D, Bhattacharyya A.
      Tumor cells promote immune evasion through up regulation of PD-L1 that binds with PD1 on cytotoxic T cells and promote dysfunction. Though therapeutic efficacy of anti PD1 antibody has remarkable effects on different type of cancers it is less effective in breast cancer. Hence more details understanding of PD-L1 mediated immune evasion is necessary. Here we report breast cancer cells secrete extra cellular vesicles in form of exosomes carry PD-L1 and is highly immunosuppressive. TGF-β present in tumor micro-environment orchestrates breast cancer cell secreted exosomal PD-L1 load. Circulating exosomal PD-L1 content is highly correlated with tumor TGF-β level. The later also found to be significantly associated with CD8+CD39+, CD8+PD1+ T cell phenotype. Recombinant TGF-β1 dose dependently induces PD-L1 expression in Texos in vitro and blocking of TGF-β dimmed exosomal PD-L1 level. PD-L1 knocked down exosomes failed to suppress effector activity of activated CD8 T cells like tumor exosomes. While understanding its effect on TCR signalling we found siPD-L1 exosomes failed to block phosphorylation of src family proteins, LAT and PLCγ of CD8 T cells more than PD-L1 exosomes. In-vivo inhibition of exosome release and TGF-β synergistically attenuates tumor burden by promoting Granzyme and IFN-γ release in tumor tissue depicting rejuvenation of exhausted T cells. Thus we establish TGF-β as a promoter of exosomal PD-L1 and unveil a mechanism that tumor cells follow to promote CD8 T cell dysfunction.
    Keywords:  PD-L1; T cell dysfunction; TGF-β; Tumor derived exosomes; breast cancer
  23. Front Immunol. 2020 ;11 1633
    Ngiow SF, Young A.
      The clinical success of cancer immunotherapies targeting PD-1 and CTLA-4 has ignited a substantial research effort to improve our understanding of tumor immunity. Recent studies have revealed that the immune contexture of a tumor influences therapeutic response and survival benefit for cancer patients. Identifying treatment modalities that limit immunosuppression, relieve T cell exhaustion, and potentiate effector functions in the tumor microenvironment (TME) is of much interest. In particular, combinatorial therapeutic approaches that re-educate the TME by limiting the accumulation of immunosuppressive immune cells, such as Foxp3 regulatory T cells (Tregs) and tumor-associated macrophages (TAMs), while promoting CD8+ and CD4+ effector T cell activity is critical. Here, we review key approaches to target these immunosuppressive immune cell subsets and signaling molecules and define the impact of these changes to the tumor milieu. We will highlight the preclinical and clinical evidence for their ability to improve anti-tumor immune responses as well as strategies and challenges for their implementation. Together, this review will provide understanding of therapeutic approaches to efficiently shape the TME and reinvigorate the immune response against cancer.
    Keywords:  adenosine; immune toxicity; mucosal-associated invariant T (MAIT) cells; natural killer T (NKT) cells; prostaglandin; regulatory T cells (Tregs); transforming growth factor (TGF)β; tumor-associated myeloid cells
  24. Cytometry B Clin Cytom. 2020 Aug 24.
    Kasakovski D, Zeng X, Lai J, Yu Z, Yao D, Chen S, Zha X, Li Y, Xu L.
      BACKGROUND: KIR+NKG2A + Eomes+ CD8+ T cells, which are preferentially found with a TEMRA (CD45RA + CCR7-) phenotype while having the capacity to rapidly produce IFN-γ in response to innate stimulation (IL-12 and IL-18), have been demonstrated to exist in human cord blood and the adult blood circulation. This highly responsive T-cell type was termed NK-like CD8+ T cells due to their capability to act in an innate immune fashion in mice similar to NK cells. However, KIR+NKG2A + CD8+ T cells that are Eomes- represent a small proportion of unconventional T cells that have not been described until now.METHODS: We compare the distribution of the memory phenotypes and senescence-associated markers of two T-cell subsets by multicolor flow cytometry in 10 cord blood samples and 105 healthy individuals (HIs) ranging from 6 to 84 years of age.
    RESULTS: We found that the Eomes+ population has a higher differentiation degree than the Eomes- population. T cells in the Eomes- subset show proportionally less TEMRA phenotypes while instead preferentially displaying a more naïve and TCM phenotype. Furthermore, the Eomes- population was shown to linearly decrease with age, while the Eomes+ population exhibited more senescence-associated characteristics, such as CD57 expression and loss of CD28.
    CONCLUSION: Overall, the KIR+NKG2A + Eomes- CD8+ T-cell population shares similar characteristics with the Eomes+ population, although with a lower degree of differentiation, lower senescence marker expression, and a proportional decrease with age. Thus, we suspect that KIR+NKG2A + Eomes-CD8+ T cells may represent a less differentiated stage of the NK-like CD8+ T-cell subset.
    Keywords:  NK-like CD8+ T cells; aging; differentiation; memory T cell
  25. Cell Res. 2020 Aug 24.
    Lv M, Chen M, Zhang R, Zhang W, Wang C, Zhang Y, Wei X, Guan Y, Liu J, Feng K, Jing M, Wang X, Liu YC, Mei Q, Han W, Jiang Z.
      CD8+ T cell-mediated cancer clearance is often suppressed by the interaction between inhibitory molecules like PD-1 and PD-L1, an interaction acts like brakes to prevent T cell overreaction under normal conditions but is exploited by tumor cells to escape the immune surveillance. Immune checkpoint inhibitors have revolutionized cancer therapeutics by removing such brakes. Unfortunately, only a minority of cancer patients respond to immunotherapies presumably due to inadequate immunity. Antitumor immunity depends on the activation of the cGAS-STING pathway, as STING-deficient mice fail to stimulate tumor-infiltrating dendritic cells (DCs) to activate CD8+ T cells. STING agonists also enhance natural killer (NK) cells to mediate the clearance of CD8+ T cell-resistant tumors. Therefore STING agonists have been intensively sought after. We previously discovered that manganese (Mn) is indispensable for the host defense against cytosolic dsDNA by activating cGAS-STING. Here we report that Mn is also essential in innate immune sensing of tumors and enhances adaptive immune responses against tumors. Mn-insufficient mice had significantly enhanced tumor growth and metastasis, with greatly reduced tumor-infiltrating CD8+ T cells. Mechanically, Mn2+ promoted DC and macrophage maturation and tumor-specific antigen presentation, augmented CD8+ T cell differentiation, activation and NK cell activation, and increased memory CD8+ T cells. Combining Mn2+ with immune checkpoint inhibition synergistically boosted antitumor efficacies and reduced the anti-PD-1 antibody dosage required in mice. Importantly, a completed phase 1 clinical trial with the combined regimen of Mn2+ and anti-PD-1 antibody showed promising efficacy, exhibiting type I IFN induction, manageable safety and revived responses to immunotherapy in most patients with advanced metastatic solid tumors. We propose that this combination strategy warrants further clinical translation.
  26. Nat Commun. 2020 Aug 24. 11(1): 4227
    Zhou M, Sacirbegovic F, Zhao K, Rosenberger S, Shlomchik WD.
      In hematopoietic cell transplants, alloreactive T cells mediate the graft-versus-leukemia (GVL) effect. However, leukemia relapse accounts for nearly half of deaths. Understanding GVL failure requires a system in which GVL-inducing T cells can be tracked. We used such a model wherein GVL is exclusively mediated by T cells that recognize the minor histocompatibility antigen H60. Here we report that GVL fails due to insufficient H60 presentation and T cell exhaustion. Leukemia-derived H60 is inefficiently cross-presented whereas direct T cell recognition of leukemia cells intensifies exhaustion. The anti-H60 response is augmented by H60-vaccination, an agonist αCD40 antibody (FGK45), and leukemia apoptosis. T cell exhaustion is marked by inhibitory molecule upregulation and the development of TOX+ and CD39-TCF-1+ cells. PD-1 blockade diminishes exhaustion and improves GVL, while blockade of Tim-3, TIGIT or LAG3 is ineffective. Of all interventions, FGK45 administration at the time of transplant is the most effective at improving memory and naïve T cell anti-H60 responses and GVL. Our studies define important causes of GVL failure and suggest strategies to overcome them.
  27. Nat Cell Biol. 2020 Aug 24.
    Gao Y, Nihira NT, Bu X, Chu C, Zhang J, Kolodziejczyk A, Fan Y, Chan NT, Ma L, Liu J, Wang D, Dai X, Liu H, Ono M, Nakanishi A, Inuzuka H, North BJ, Huang YH, Sharma S, Geng Y, Xu W, Liu XS, Li L, Miki Y, Sicinski P, Freeman GJ, Wei W.
      Immunotherapies that target programmed cell death protein 1 (PD-1) and its ligand PD-L1 as well as cytotoxic T-lymphocyte-associated protein 4 (CTLA4) have shown impressive clinical outcomes for multiple tumours. However, only a subset of patients achieves durable responses, suggesting that the mechanisms of the immune checkpoint pathways are not completely understood. Here, we report that PD-L1 translocates from the plasma membrane into the nucleus through interactions with components of the endocytosis and nucleocytoplasmic transport pathways, regulated by p300-mediated acetylation and HDAC2-dependent deacetylation of PD-L1. Moreover, PD-L1 deficiency leads to compromised expression of multiple immune-response-related genes. Genetically or pharmacologically modulating PD-L1 acetylation blocks its nuclear translocation, reprograms the expression of immune-response-related genes and, as a consequence, enhances the anti-tumour response to PD-1 blockade. Thus, our results reveal an acetylation-dependent regulation of PD-L1 nuclear localization that governs immune-response gene expression, and thereby advocate targeting PD-L1 translocation to enhance the efficacy of PD-1/PD-L1 blockade.