Human MAIT cells endowed with HBV specificity are cytotoxic and migrate towards HBV-HCC while retaining antimicrobial functions

Background & Aims: Virus-specific T cell dysfunction is a common feature of HBV-related hepatocellular carcinoma (HBV-HCC). Conventional T (ConT) cells can be redirected towards viral antigens in HBV-HCC when they express an HBV-specific receptor; however, their efficacy can be impaired by liver-specific physical and metabolic features. Mucosal-associated invariant T (MAIT) cells are the most abundant innate-like T cells in the liver and can elicit potent intrahepatic effector functions. Here, we engineered ConT and MAIT cells to kill HBV expressing hepatoma cells and compared their functional properties. Methods: Donor-matched ConT and MAIT cells were engineered to express an HBV-specific T cell receptor (TCR). Cytotoxicity and hepatocyte homing potential were investigated using flow cytometry, real-time killing assays, and confocal microscopy in 2D and 3D HBV-HCC cell models. Major histocompatibility complex (MHC) class I-related molecule (MR1)-dependent and MR1-independent activation was evaluated in an Escherichia coli THP-1 cell model and by IL-12/IL-18 stimulation, respectively. Results: HBV TCR-MAIT cells demonstrated polyfunctional properties (CD107a, interferon [IFN] γ, tumour necrosis factor [TNF], and IL-17A) with strong HBV target sensitivity and liver-homing chemokine receptor expression when compared with HBV TCR-ConT cells. TCR-mediated lysis of hepatoma cells was comparable between the cell types and augmented in the presence of inflammation. Coculturing with HBV+ target cells in a 3D microdevice mimicking aspects of the liver microenvironment demonstrated that TCR-MAIT cells migrate readily towards hepatoma targets. Expression of an ectopic TCR did not affect the ability of the MAIT cells to be activated via MR1-presented bacterial antigens or IL-12/IL-18 stimulation. Conclusions: HBV TCR-MAIT cells demonstrate anti-HBV functions without losing their endogenous antimicrobial mechanisms or hepatotropic features. Our results support future exploitations of MAIT cells for liver-directed immunotherapies. Lay summary: Chronic HBV infection is a leading cause of liver cancer. T cell receptor (TCR)-engineered T cells are patients’ immune cells that have been modified to recognise virus-infected and/or cancer cells. Herein, we evaluated whether mucosal-associated invariant T cells, a large population of unconventional T cells in the liver, could recognise and kill HBV infected hepatocytes when engineered with an HBV-specific TCR. We show that their effector functions may exceed those of conventional T cells currently used in the clinic, including antimicrobial properties and chemokine receptor profiles better suited for targeting liver tumours

Robust T Cell Immunity in Convalescent Individuals with Asymptomatic or Mild COVID-19

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. Here, we systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in unexposed individuals, exposed family members, and individuals with acute or convalescent COVID-19. Acute-phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent-phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative exposed family members and convalescent individuals with a history of asymptomatic and mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits broadly directed and functionally replete memory T cell responses, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19.Fil: Sekine, Takuya. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Perez Potti, André. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Rivera Ballesteros, Olga. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Strålin, Kristoffer. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Gorin, Jean Baptiste. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Olsson, Annika. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Llewellyn Lacey, Sian. University Hospital of Wales; Reino UnidoFil: Kamal, Habiba. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Bogdanovic, Gordana. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Muschiol, Sandra. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Wullimann, David J.. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Kammann, Tobias. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Emgård, Johanna. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Parrot, Tiphaine. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Folkesson, Elin. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Rooyackers, Olav. Karolinska Huddinge Hospital. Karolinska Institutet; Suecia. Karolinska University Hospital; SueciaFil: Eriksson, Lars I.. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Henter, Jan Inge. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Sönnerborg, Anders. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Allander, Tobias. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Albert, Jan. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Nielsen, Morten. Technical University of Denmark; Dinamarca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Klingstrom, Jonas. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Gredmark Russ, Sara. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Björkström, Niklas K.. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Sandberg, Johan K.. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Price, David A.. Cardiff University School of Medicine; Reino UnidoFil: Ljunggren, Hans Gustaf. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Aleman, Soo. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Buggert, Marcus. Karolinska Huddinge Hospital. Karolinska Institutet; Sueci

Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. Here, we systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in unexposed individuals, exposed family members, and individuals with acute or convalescent COVID-19. Acute-phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent-phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative exposed family members and convalescent individuals with a history of asymptomatic and mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits broadly directed and functionally replete memory T cell responses, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19

Study of intra-melanoma CD4+CD8+ double positive αβT cells in the anti-tumor immune response

L’infiltrat immunitaire joue un rôle déterminant dans la progression tumorale et sert d’indicateur quant à la réussite ou à la mise en échec des traitements antitumoraux, notamment dans le cadre des immunothérapies. Une dissection fine de ses composants cellulaires et de leurs interactions est donc fondamentale pour améliorer à terme les essais thérapeutiques. C’est dans ce contexte que notre équipe a identifié parmi les lymphocytes T infiltrant les mélanomes, des lymphocytes Tαβ co-exprimant les récepteurs CD4 et CD8 (LT DP) et réactifs à la tumeur de façon HLA-I restreinte. Nos travaux écartent l’hypothèse d’un rôle cytotoxique ou régulateur de ces cellules et mettent en évidence une fonction de type helper via l’expression de la molécule CD40L. L’interaction CD40L/CD40 permet aux LT DP d’induire la prolifération et la différenciation des lymphocytes B d’une part, et d’autre part, de promouvoir la maturation de cellules dendritiques capables d’induire efficacement une réponse lymphocytaire cytotoxique contre des antigènes tumoraux. Par ailleurs, nos travaux attribuent un rôle à la cytokine IL-9 dans la modulation fonctionnelle et dans l’homéostasie des LT DP. Nous montrons que via le récepteur à l’IL-9 exprimé par les LT DP, l’IL-9 impacte positivement leur survie et leur prolifération. De plus, l’IL-9 optimise leur réactivité face à la tumeur en potentialisant leur production cytokinique, en augmentant leur potentiel tumoricide et vraisemblablement leur fonction helper. Il serait désormais intéressant d’évaluer ex vivo la pertinence de ces cellules dans la réponse immune antitumorale en corrélant leur fréquence à l’évolution clinique du patient.The immune infiltrate is a key factor in the tumor progression and has a prognostic value for the efficacy of anti-tumor treatments especially for immunotherapies. Therefore, the understanding of the cellular components and their interactions taking place within the tumor microenvironment is necessary for the future optimization of anti-tumor therapeutic strategies. We previously documented among melanoma-infiltrating lymphocytes, an atypical tumor reactive and class-Irestricted T cell population co-expressing both CD4 and CD8 co-receptors. In this study, we excluded a cytotoxic and regulatory function for these cells and ascribed helper properties through the expression of the CD40L costimulatory molecule. Through the CD40L/CD40 interaction, DP T cells allow B cell proliferation and differentiation, as well as, the licensing of dendritic cells for the efficient priming of an anti-tumor cytotoxic CD8 T cell response. Also, our results described a potential role of the interleukin-9 cytokine in DP T cell function and homeostasis. Through its interaction with its cognate receptor, the IL-9 receptor, expressed by DP T cells, IL-9 increases their survival and proliferation and could enhance their enrichment in the tumor microenvironment. In addition, IL-9 enhances their functional properties including cytokine production, cytolytic activity and probably their helper potential. It would be interesting to now define the relevance of this population ex vivo in the anti-tumor immune response by correlating their intra-tumor frequency with the clinical status of the patients

MAIT cell counts are associated with the risk of hospitalization in COPD

Background Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation associated with chronic inflammation in the airways. Mucosal-associated invariant T (MAIT) cells are unconventional, innate-like T cells highly abundant in mucosal tissues including the lung. We hypothesized that the characteristics of MAIT cells in circulation may be prospectively associated with COPD morbidity. Methods COPD subjects (n = 61) from the Tools for Identifying Exacerbations (TIE) study were recruited when in stable condition. At study entry, forced expiratory volume in 1 s (FEV1) was measured and peripheral blood mononuclear cells were cryopreserved for later analysis by flow cytometry. Patients were followed for 3 years to record clinically meaningful outcomes. Results Patients who required hospitalization at one or more occasions during the 3-year follow-up (n = 21) had lower MAIT cell counts in peripheral blood at study inclusion, compared with patients who did not get hospitalized (p = 0.036). In contrast, hospitalized and never hospitalized patients did not differ in CD8 or CD4 T cell counts (p = 0.482 and p = 0.221, respectively). Moreover, MAIT cells in hospitalized subjects showed a more activated phenotype with higher CD38 expression (p = 0.014), and there was a trend towards higher LAG-3 expression (p = 0.052). Conventional CD4 and CD8 T cells were similar between the groups. Next we performed multi-variable logistic regression analysis with hospitalizations as dependent variable, and FEV1, GOLD 2017 group, and quantity or activation of MAIT and conventional T cells as independent variables. MAIT cell count, CD38 expression on MAIT cells, and LAG-3 expression on both MAIT and CD8 T cells were all independently associated with the risk of hospitalization. Conclusions These findings suggest that MAIT cells might reflect a novel, FEV1-independent immunological dimension in the complexity of COPD. The potential implication of MAIT cells in COPD pathogenesis and MAIT cells’ prognostic potential deserve further investigation

Expansion of donor-unrestricted MAIT cells with enhanced cytolytic function suitable for TCR redirection

Progress in our understanding of MR1-restricted mucosa-associated invariant T (MAIT) cells has raised interest in harnessing these cells for immunotherapy. The innate-like response characteristics, abundance in the blood, donor-unrestricted nature, and tropism for tissues make MAIT cells suitable candidates for adoptive cell transfer therapies. However, reliable methods and tools to utilize MAIT cells in such approaches are lacking. Here, we established methodology for efficient expansion of human MAIT cells in culture with high purity and yield, while preserving their functional response toward their natural ligand and increasing their cytotoxic potential. The cultured MAIT cells retained their effector memory characteristics without signs of terminal differentiation and expressed a more diverse set of chemokine receptors, potentially widening their already broad tissue tropism. To investigate the potential of MAIT cells in a context outside their main role in controlling bacterial infection, we engineered cultured MAIT cells with a new TCR specificity to mediate effective antiviral HLA class I–restricted effector function. In summary, we developed robust and effective methodology for the expansion of human MAIT cells with enhanced cytolytic capacity and for their engineering with a new specificity. These findings form a basis for the development of MAIT cells as a platform for adoptive immunotherapy

Emergence of High-Avidity Melan-A–Specific Clonotypes as a Reflection of Anti–PD-1 Clinical Efficacy

International audienceTherapeutic strategies using anti-PD-1-blocking antibodies reported unparalleled effectiveness for melanoma immunotherapy, but deciphering immune responses modulated by anti-PD-1 treatment remains a crucial issue. Here, we analyzed the composition and functions of the large Melan-A-specific T-cell repertoire in the peripheral blood of 9 melanoma patients before and after 2 months of treatment with anti-PD-1. We observed amplification of Melan-A-specific Vß subfamilies undetectable before therapy (thereafter called emerging Vß subfamilies) in responding patients, with a predominant expansion in patients with a complete response. These emerging Vß subfamilies displayed a higher functional avidity for their cognate antigen than Vß subfamilies not amplified upon anti-PD-1 therapy and could be identified by a sustained coexpression of PD-1 and TIGIT receptors. Thus, in addition to the emergence of neoantigen-specific T cells previously documented upon anti-PD-1 therapy, our work describes the emergence of high-avidity Melan-A-specific clonotypes as a surrogate marker of treatment efficacy

Deciphering anti-HCMV HLA-E-restricted unconventional CD8 T-cell responses in seropositive HCMV+ hosts

International audienceHuman cytomegalovirus (HCMV) causes severe illness and poor outcome in immunocompromised hosts such as transplant recipients and HIV-infected patients. Cytotoxic CD8 T cells against HCMV antigens (pp65, IE1) presented by classical HLA class-I molecules are major cellular components of the protective anti-HCMV immunity. HLA-E-restricted CD8 T cells targeting HCMV UL40 leader peptides (Lp) have been recently reported as unconventional T-cell responses also observed in some hosts but they still need clinical and functional characterization. Our study aimed to provide a qualitative and quantitative ex vivo analysis of HLA-EUL40 CD8 Tcell responses, in a large cohort (n=144) of kidney transplant recipients and healthy volunteers, and to elucidate determining factors. HLA-EUL40 CD8 T-cells were detected in >30% of seropositive HCMV+ hosts and may represent >30% of total circulating CD8 αβT cells at a time point. We identified host-related genetic factors (HLA-A*02 and HLA-E genotype) and HCMV strain, determining the sequence of UL40Lp, as critical parameters for this response. HLA-EUL40 CD8 are effector memory T cells that appear early post-infection as monoclonal/oligoclonal populations and persist for life. Although specifically induced in response to HCMV infection, a key feature of these cells is their potential ability to be also responsive against self and allogeneic HLA resulting from sequence homology between HLA-ILp and UL40Lp. Thus we established that unconventional HLA-EUL40 CD8 T cells belong to the common immune arsenal against HCMV. Their functions remain to be defined toward infection as well as their potential side effect in contexts such as autoimmunity and transplantation

HCMV triggers frequent and persistent UL40- specific unconventional HLA-E-restricted CD8 T-cell responses with potential autologous and allogeneic peptide recognition

International audienceImmune response against human cytomegalovirus (HCMV) includes a set of persistent cytotoxic NK and CD8 T cells devoted to eliminate infected cells and to prevent reactivation. CD8 T cells against HCMV antigens (pp65, IE1) presented by HLA class-I molecules are well characterized and they associate with efficient virus control. HLA-E-restricted CD8 T cells targeting HCMV UL40 signal peptides (HLA-E[UL40]) have recently emerged as a non-conventional T-cell response also observed in some hosts. The occurrence, specificity and features of HLA-E[UL40] CD8 T-cell responses remain mostly unknown. Here, we detected and quantified these responses in blood samples from healthy blood donors (n = 25) and kidney transplant recipients (n = 121) and we investigated the biological determinants involved in their occurrence. Longitudinal and phenotype ex vivo analyses were performed in comparison to HLA-A*02/pp65-specific CD8 T cells. Using a set of 11 HLA-E/UL40 peptide tetramers we demonstrated the presence of HLA-E[UL40] CD8 αβT cells in up to 32% of seropositive HCMV+ hosts that may represent up to 38% of total circulating CD8 T-cells at a time point suggesting a strong expansion post-infection. Host's HLA-A*02 allele, HLA-E *01:01/*01:03 genotype and sequence of the UL40 peptide from the infecting strain are major factors affecting the incidence of HLA-E[UL40] CD8 T cells. These cells are effector memory CD8 (CD45RA[high]RO[low], CCR7-, CD27-, CD28-) characterized by a low level of PD-1 expression. HLA-E[UL40] responses appear early post-infection and display a broad, unbiased, Vβ repertoire. Although induced in HCMV strain-dependent, UL40[15-23]-specific manner, HLA-E[UL40] CD8 T cells are reactive toward a broader set of nonapeptides varying in 1-3 residues including most HLA-I signal peptides. Thus, HCMV induces strong and lifelong lasting HLA-E[UL40] CD8 T cells with potential allogeneic or/and autologous reactivity that take place selectively in at least a third of infections according to virus strain and host HLA concordance