1、Immunological Reviews.2020;00:112.| INTRODUCTION ON ANTIGEN RECOGNITION BY T CELLSHuman T lymphocytes are typically classified based on the V chain used to make their T cell receptor(TCR).The prevalent(70%)T lymphocytes in human blood and secondary lymphoid organs of adult individuals express a TCR
2、heterodimer composed of the V9 and V2 chains.1 These cells are commonly named as V9V2 T lymphocytes,and recognize non-proteic pyrophosphate metabolites called phosphoantigens(PAgs),which derive either from the meva-lonic acid(MVA)pathway2 or the microbial non-mevalonate Rohmer cycle(E)-4-hydroxy-3-m
3、ethylbut-2-enyl pyrophosphate,HMB-PP).3Butyrophilin-3A1(CD277)is necessary but not sufficient for PAg recognition by V9V2 T cells.4-6 Another BTN mole-cule,BTN2A1,has been recently identified as a key ligand that Received:15 April 2020|Revised:21 June 2020|Accepted:30 June 2020DOI:10.1111/imr.12904
4、I N V I T E D R E V I E WDeciphering human T cell response in cancer:Lessons from tumor-infiltrating T cellsElena Lo Presti1,2|Francesco Dieli1,2|Jean Jacques Fourni3,4,5,6,7|Serena Meraviglia1,2 2020 John Wiley&Sons A/S.Published by John Wiley&Sons LtdThis article is part of a series of reviews cov
5、ering T Cells appearing in Volume 298 of Immunological Reviews.1Central Laboratory of Advanced Diagnosis and Biomedical Research(CLADIBIOR),University of Palermo,Palermo,Italy2Department of Biomedicine,Neurosciences and Advanced Diagnosis(BIND),University of Palermo,Palermo,Italy3Centre de Recherche
6、s en Cancrologie de Toulouse,Toulouse,France4Toulouse University,Toulouse,France5ERL 5294 CNRS,Toulouse,France6Institut Universitaire du Cancer-Oncopole de Toulouse,Toulouse,France7Laboratoire dExcellence TOUCAN,Toulouse,FranceCorrespondenceFrancesco Dieli and Serena Meraviglia,Central Laboratory of
7、 Advanced Diagnosis and Biomedical Research(CLADIBIOR),Universit di Palermo,Via del Vespro 129,Palermo 90127,Italy.Emails:francesco.dieliunipa.it;serena.meravigliaunipa.itFunding informationLabEX TOUCAN2;Centre National de la Recherche Scientifique;Institut National de la Sant et de la Recherche Mdi
8、cale;Italian Ministry of Education and Research,Grant/Award Number:PRIN 2017-2017M8YMR8_001;Italian Ministry of Health,Grant/Award Number:GR 2016-02364931AbstractThe finding that T cells are present among tumor-infiltrating lymphocytes in hu-mans suggests they participate in tumor immune surveillanc
9、e,but their relevance is unclear because the relative abundance of tumor-infiltrating T cells correlates with positive or negative,or even do not correlate with prognosis.This likely depends on the fact that tumor-infiltrating T cells may play substantially different effector or regulatory functions
10、,and correlation with patients prognosis relies on distinct T cell subsets in the context of the tumor.There is interest to exploit T cells in tumor immunotherapy,but to make this approach successful there is urgent need to fully understand the biological functions of T cells and of how they can be
11、manipulated in vivo and ex vivo to safely provide benefit to the host.This review focuses on our previous and ongoing studies of tumor-infiltrating T lymphocytes in different types of human cancer.Moreover,we discuss the interaction of tumor-infiltrating T cells with other cells and molecules presen
12、t in the tumor microenvironment,and their clinical relevance on the ground,that deep knowledge in this field can be used further for better immunotherapeutic intervention in cancer.K E Y W O R D Sclinical correlation,colon cancer,tumor microenvironment,tumor-infiltrating lymphocytes,T lymphocytes2|L
13、O PRESTI ET aL.associates on the cell surface with BTN3A1 independent of PAg and binds to the V9V2 TCR.In particular,the surface of the BTN2A1 IgV domain directly binds to germline-encoded V9 re-gions of the V9V2 TCR,while somatically recombined CDR3 re-gions implicated in PAg recognition are uninvo
14、lved.It is then likely that binding of a second ligand,possibly BTN3A1,to a separate TCR V2 domain is also required.7,8In agreement with the very restricted antigen recognition pattern,the V9V2 TCR repertoire is invariant or semi-invari-ant,suggestive of an innate-like modality of PAg recognition.9,
15、10 However,there is evidence11 that in addition to the PAg-reactive V9+T lymphocytes,the V2 population also includes another subset of V9 T lymphocytes with a diverse repertoire and with adaptive-like characteristics,as indicated by the finding that this population clonally expands during acute cyto
16、megalovirus(CMV)infection.T lymphocytes,expressing the V1 or V3 TCRs,are less rep-resented than V9V2 T cells in adult blood but predominate in tis-sues1 and have quite different antigen reactivity.V1 T lymphocytes physiologically reside in the skin,lung,intestine,and colon epithelia where they repre
17、sent the major T cell subset and recognize stress antigens overexpressed upon CMV infection and tumor transforma-tion.12-15 V3 T cells are even rarer than V1 T cells in blood but abound in the liver and gut and are expanded in patients with CMV infection or B cell leukemia.There is very limited evid
18、ence for MHC class I-and CD1d-restricted V1 T cells,16 and a V8V3 T lympho-cyte population recognizes Annexin A2 overexpressed by stressed and tumor cells.17Differently than T cells,and with the exception of very rare V3 T cells,T cells lack genetic(ie,HLA,CD1,or MR1)restriction and are independent
19、on co-stimulatory signals like CD28.1 However,T cells share several features with T cells:in fact,and similar to T CD8 subset,they can be distinguished into“naive,”“central memory,”“effector memory,”and“terminally differentiated”sub-sets with different recirculation pattern and effector functions.18
20、 Moreover,T cells may acquire highly diverse effector functions in the presence of certain cytokine combinations and polarize to Th1,Th2,Th17,follicular T helper,Th9,and T regulatory(Treg)cells,19-28 and this wide flexibility highlights the capacity of T cells to rapidly respond to different antigen
21、ic challenges.2|T CELL FUNCTIONS IN TUMOR IMMUNOLOGYThe evolutionary divergence between human and rodents has been the major obstacle in the scientific research in the field of T lym-phocyte.In fact,cells with repertoire and reactivity of human T lymphocytes,particularly V9V2 T lymphocytes,are only
22、found in humans and higher primates,but absent from mice,1 in which pre-clinical studies are performed.Thus,the lack of a suitable animal model has greatly hampered our knowledge of the role of T lym-phocytes in immune responses to pathogens.Nevertheless,robust evidence that T cells may have anti-tu
23、-mor activity has been firmly established by studies of Hayday and coworkers demonstrating that T lymphocytes control the devel-opment of skin cancer in mice,29 and by the finding that human T lymphocytes are able to exert potent HLA-unrestricted cytotoxic-ity in vitro against a variety of tumor cel
24、ls.30 Moreover,human T lymphocytes expanded ex vivo and then adoptively transferred into immunodeficient mice xenografted with tumor cells,have demon-strated efficient anti-tumor activity(reviewed in 31).The most important effector function of T cells that is rele-vant to tumor immunology is their c
25、ytotoxic activity.T cells rec-ognize antigens(stress molecules,PAgs/BTN3A1 complexes,other unknown molecules)broadly expressed on many different tumor cells and in the absence of genetic restriction.Thus,the capacity to recognize antigens,which are common to many different tumors and in the absence
26、of genetic restriction,may allow a broader clinical uti-lization of T cells in the global heterogenic population and across many different tumor types.Upon tumor antigen recognition by the TCR or NKG2D and NCRs receptors,32-35 T lymphocytes establish immunological syn-apses with target tumor cells a
27、nd kill them using the same mecha-nisms as NK and CD8 cytotoxic T cells,namely granule exocytosis with release of perforin,granzymes and granulysin,and activation of death receptors by the respective ligands.36-40 Moreover,human (both V1 and V2)T lymphocytes express CD16(the low-affinity FcRIII)and
28、perform antibody-dependent cell-mediated cytotoxicity(ADCC).41In addition to their prominent cytolytic activity,upon antigen stimulation in the presence of polarizing cytokines,human T lymphocytes undergo a differentiation program toward different phenotypic subsets18-28 and acquire different cytoki
29、ne secretion patterns see above,and can influence tumor growth by orchestrat-ing downstream immune responses.Thus,human T lymphocytes help B lymphocytes to produce different antibody classes,26,27 pro-mote 4-1BB-mediated NK cell cytotoxicity,42 induce dendritic cells maturation,43,44 and reprogram t
30、heir functions to become profes-sional antigen-presenting cells to induce priming and expansion of conventional CD8 cytotoxic T lymphocytes.45-473|TUMOR-INFILTRATING T CELLS:HOW CAN WE DETECT THEM?The identification of tumor-infiltrating T lymphocytes in humans is a major issue for establishing thei
31、r prognostic value and for can-cer immunotherapy,as these pleomorphic cells which are located in most healthy organs are often misidentified or even not uniden-tified at all.48,49 Typically,detection and characterization of T lymphocytes in healthy or tumor tissues rely on a combination of cell surf
32、ace markers labeled by immunostaining and visualized by immunohistochemistry.This technique requires access to fresh tumor samples,and furthermore,immunohistochemical spotting of T cells remains largely hampered by the paucity of anti-TCR|3LO PRESTI ET aL.reagents compatible with staining of formali
33、n-fixed and paraffin-embedded samples.There is only one anti-pan TCR mAb on the market which works well on paraffin-embedded tissues and which has been made commercially available only very recently,50 but this mAb does not distinguish between V1,V2 and V3 subsets of T cells.Alternatively,or in addi
34、tion,T lymphocytes in tissues may be visualized by flow cytometry.48,49 However,this is a quite demand-ing process that requires digestion of tissue samples large enough to obtain a sufficient number of viable cells for subsequent phenotypic and functional analysis.Nevertheless,both these techniques
35、 have been used to estimate the frequency,phenotypes,and functions by T lymphocytes obtained from different types of human cancer tissues.However,given the recent developments in T cellbased thera-pies of cancer,it is important to know not only the rate of tumor-infil-trating T lymphocytes from any
36、tumor biopsy,but also their subset distribution,maturation/activation/exhaustion states,and functional profiles likewise,but this has remained unclear so far.The large num-ber of transcriptomic datasets obtained using microarrays or mRNA sequencing(RNAseq)of bulk tumor biopsies,and currently availab
37、le from public databases(GEO database,The Cancer Genome Atlas,etc)represent an invaluable resource and unique opportunity to address these issues by data mining approaches.One such method,called de-convolution,consists in algorithmic learning transcriptomic profiles of several specific cell types ta
38、ken individually,followed by algorithmic deduction of their respective rates from the bulk transcriptome of a complex cell mixture.51 Using this approach Gentles et al found that tumor-infiltrating T cells were the most significant favorable can-cer-wide prognostic populations among 19,000 tumors.52
39、 In a sub-sequent analysis of 15 000 biopsies from 50 solid and hematologic malignancies however,we showed that the Gentless study misidenti-fies,CD8,and NK cell types,53,54 indicating that current published deconvolution studies might provide us with misleading conclusions about T cell infiltrating
40、 human cancers.The recent developments in single-cell RNA sequencing are complementing and updating immunochemistry and flow cytometer methodologies,and now provide us with the finest level of resolu-tion for the gene expression patterns of large sets of cells,unveiling much finer aspects and allowi
41、ng their classifications from human tissues.Nevertheless,for the same above reasons,plus impossibility to determine TCRV and gene usage from short reads of 3 mRNA ends,the identification of T lymphocytes in scRNA-seq data re-mained elusive,so T cells remain barely identified in most scRNA-seq studie
42、s of PBMC or tissues.By providing the first scRNA-seq dataset of cell-sorted TCRV and TCRV T lymphocytes purified from PBMC of healthy in-dividuals with known CMV serology,we defined a gene signature identifying human T cells in scRNAseq datasets55(Figure 1).By this approach,scarce tumor-infiltratin
43、g T cells of either TCRV1 or TCRV2 subtypes could be detected in a small series of published cancer scRNA-seq datasets,with cell counts suggesting a decorrela-tion of tumor-infiltrating and cells across human cancers.These advances paved the way to further meta-analyses of tumor-infiltrat-ing cells
44、aiming at reliably determining their presence,TCR usage,maturation/differentiation,and activation/exhaustion status in the tumor microenvironment of a large spectrum of human cancers.4|T LYMPHOCYTES IN CHRONIC INFLAMMATORY BOWEL DISEASE AND COLORECTAL CANCERPatients with inflammatory bowel disease(I
45、BD)have an elevated risk to develop colorectal cancer(CRC)that is associated with the duration and extent of chronic inflammation.56,57 The role of T cells in the pathogenesis of IBD is still poorly known,because of the conflicting findings showing either increased or decreased frequen-cies of T cel
46、ls in IBD patients,as compared to control subjects.Moreover,most studies have looked at circulating T cells,which do not necessarily mirror the situation in gut tissue.58,59In a murine model of IBD,T cells that participate to chronic in-flammation,express the gut-homing molecules CD103 and 47 and pr
47、oduce IL-17,60 which is known to sustain chronic inflammation in FIGURE 1The T lymphocytes in t-SNE map of an scRNAseq dataset from human PBMC.Cells are clustered according to transcriptomic similarity,constituting clouds of cell from the same lineage and subset.PBMC datasets typically comprise a gr
48、oup of moreless continuous T cell clusters neighbored by an NK cell cluster,a myeloid cluster encompassing monocytes and DCs,as well as a separate but compact cluster of B lymphocytes.Minor clusters of plasma cells,plasmacytoid DC,and scarce megakaryocytes or erythroid precursors are eventually obse
49、rved in larger datasets.In t-SNE maps from such samples,most T lymphocytes are embedded between TCD4,TCD8,and NK cells,although with slight differences between cells of the TCRV1 and TCRV2 subset from CMV+individuals.For visual clarity,the T cells are shown with larger symbols4|LO PRESTI ET aL.the i
50、ntestine and contribute to cancer development.53,61 Moreover,a population of gut-tropic T cells that express integrin and pro-duce TNF-has been detected in the blood and in mucosa samples of IBD patients.62As T cells may play a role in the regulation of the integrity of the mucosa barrier,63 it is i
