Search

Heterologous polyclonal antibodies might represent an alternative to the use of convalescent plasma or monoclonal antibodies (mAbs) in coronavirus disease (COVID‐19) by targeting multiple antigen epitopes. However, heterologous antibodies trigger human natural xenogeneic antibody responses particularly directed against animal‐type carbohydrates, mainly the N‐glycolyl form of the neuraminic acid (Neu5Gc) and the α1,3‐galactose, potentially leading to serum sickness or allergy. Here, we immunized cytidine monophosphate‐N‐acetylneuraminic acid hydroxylase and α1,3‐galactosyl‐transferase (GGTA1) double KO pigs with the Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike receptor binding domain to produce glyco‐humanized polyclonal neutralizing antibodies lacking Neu5Gc and α1,3‐galactose epitopes. Animals rapidly developed a hyperimmune response with anti‐SARS‐CoV‐2 end‐titers binding dilutions over one to a million and end‐titers neutralizing dilutions of 1:10 000. The IgG fraction purified and formulated following clinical Good Manufacturing Practices, named XAV‐19, neutralized spike/angiotensin converting enzyme‐2 interaction at a concentration, GGTA1/CMAH double KO pigs produced high titers of XAV‐19, an anti‐SARS‐Cov‐2 RBD glyco‐humanized polyclonal antibody. XAV‐19 is presented with a high complement activation and a high neutralization potency in vitro and in cell‐based neutralization assays. XAV‐19 does not interact with human Fc gamma receptors, preventing Fc‐dependent enhancement or immune cells skewing.

Peripheral CD4+CD8+ double positive (DP) T cells are a phenotypically and functionally heterogeneous population depending on their origin and pathologic context. We previously identified among tumour infiltrating lymphocytes in melanoma, a tumour-reactive MHC class-I restricted CD4lowCD8high DP αβ T-cell subpopulation with CD4-like function. In this study, we used an in-depth comparative transriptomic analysis of intra-melanoma DP T cells and CD4 and CD8 single positive (SP) T cells, to better comprehend the origin of this DP phenotype, and define the transcriptomic signature of activated DP T cells. We observed that intra-melanoma DP T cells were transcriptome-wise closer to their CD8 SP T-cell counterparts in terms of number of genes differentially expressed (97 in common with CD8 SP T cells and 15 with CD4 SP T cells) but presented hallmarks of a transition to a CD4-like functional profile (CD40LG) with a decreased cytotoxic signature (KLRC1) in favour of an increased cytokine-receptor interaction signature (IL4, IL24, IL17A…). This unleashed CD4-like program could be the results of the observed unbalanced expression of the THPOK/Runx3 transcription factors in DP T cells. Overall, this study allow us to speculate that intra-melanoma DP T cells arise from CD8 SP T cells being reprogrammed to a helper function.

International audience; We previously demonstrated that HLA-E/β2m overexpression by tumor cells in colorectal cancers is associated with an unfavorable prognosis. However, the expression of its specific receptor CD94/NKG2 by intraepithelial tumor-infiltrating lymphocytes, their exact phenotype and function, as well as the relation with the molecular status of colorectal cancer and prognosis remain unknown. Based on a retrospective cohort of 234 colorectal cancer patients, we assessed the expression of HLA-E, β2m, CD94, CD8, and NKp46 by immunohistochemistry on tissue microarray. The expression profile of HLA-E/ β2m on tumor cells and the density of tumor-infiltrating lymphocytes were correlated to the clinicopathological and molecular features (Microsatellite status, BRAF and RAS mutations). Then, from the primary tumors of 27 prospective colorectal cancers, we characterized by multiparameter flow cytometry the nature (T and/or NK cells) and the co-expression of the inhibitory NKG2A or activating NKG2C chain of ex vivo isolated CD94 + tumor-infiltrating lymphocytes. Their biological function was determined using an in vitro redirected cytolytic activity assay. Our results showed that HLA-E/β2m was preferentially overexpressed in microsatellite instable tumors compared with microsatellite stable ones (45% vs. 19%, respectively, p = 0.0001), irrespective of the RAS or BRAF mutational status. However, HLA-E/β2m + colorectal cancers were significantly enriched in CD94 + intraepithelial tumor-infiltrating lymphocytes in microsatellite instable as well as in microsatellite stable tumors. Those CD94 + tumor-infiltrating lymphocytes mostly corresponded to CD8 + αβ T cells, and to a lesser extent to NK cells, and mainly co-expressed a functional inhibitory NKG2A chain. Finally, a high number of CD94 + intraepithelial tumor-infiltrating lymphocytes in close contact with tumor cells was independently associated with a worse overall survival. In conclusion, these findings strongly suggest that HLA-E/β2m-CD94/NKG2A represents a new druggable inhibitory immune checkpoint, preferentially expressed in microsatellite instable tumors, but also in a subgroup of microsatellite stable tumors, leading to a new opportunity in colorectal cancer immunotherapies.

We previously demonstrated that HLA-E/β2m overexpression by tumor cells in colorectal cancers is associated with an unfavorable prognosis. However, the expression of its specific receptor CD94/NKG2 by intraepithelial tumor-infiltrating lymphocytes, their exact phenotype and function, as well as the relation with the molecular status of colorectal cancer and prognosis remain unknown. Based on a retrospective cohort of 234 colorectal cancer patients, we assessed the expression of HLA-E, β2m, CD94, CD8, and NKp46 by immunohistochemistry on tissue microarray. The expression profile of HLA-E/β2m on tumor cells and the density of tumor-infiltrating lymphocytes were correlated to the clinicopathological and molecular features (Microsatellite status, BRAF and RAS mutations). Then, from the primary tumors of 27 prospective colorectal cancers, we characterized by multiparameter flow cytometry the nature (T and/or NK cells) and the co-expression of the inhibitory NKG2A or activating NKG2C chain of ex vivo isolated CD94

International audience; We previously demonstrated an accumulation of tumor-reactive CD4 + CD8 + double positive (DP) T cells within melanoma-infiltrating lymphocytes, supporting their role in the regulation of anti-tumor immune responses. Similarly to their CD8 + counterparts, intra-tumor DP T cells are MHC class-I restricted but differed by a limited lytic activity against autologous melanoma cells. Based on these observations and to further characterize DP T cells, both populations were compared at the transcriptional level. Our results revealed the overexpression of the IL-9 receptor (IL-9R) by DP T cells and prompted us to investigate the impact of IL-9 on their biology. We show that IL-9 favors DP T-cell survival by protecting them from apoptosis and by promoting their proliferation. In addition, IL-9 enhances their ability to produce cytokines and increased their levels of granzyme B/perforin as well as degranulation capacity, leading to a strengthened cytotoxic activity against melanoma cells. Taken together, the IL-9R high DP T-cell population could be a new preferential target for IL-9, which could take part in their retention within the melanoma infiltrate while also favoring their anti-tumor activity. More generally, our results extend the pleiotropic effects of IL-9 to IL-9R-expressing intra-tumor T cells, which could further potentiate anti-tumor immune responses. Keywords: CD4 + CD8 + double-positive T lymphocyte r IL-9R r IL-9 r Melanoma r TIL Additional supporting information may be found in the online version of this article at the publisher's web-site

In colorectal cancer (CRC), little is known about mechanisms by which tumor cells can influence the biology of Tumor Infiltrating T lymphocytes (TILs) present in the tumor microenvironment. One of these mechanisms could be modulation of the inflammasome of tumor cells. The inflammasome is a molecular platform present in normal intestinal epithelial cells, whose effector protein, caspase-1, can rapidly mature IL-18 and generate a mucosal Th1 (IFNγ) response. However, the inflammasome status of tumor cells in CRC and its potential role in the biology of TILs are unknown yet. This prospective study aimed to determine in CRC patients (n = 50) : i) the status of the inflammasome (caspase-1 / IL-18 axis) in tumor cells according to their microsatellite status [unstable (MSI) or stable (MSS)], in relation with the density of Th1/Tc1 TILs (T-bet+) and with the levels of the prototype Th1 cytokine IFNγ, secreted in an ex vivo explant culture model of CRC we developed and ii) the impact of the inflammasome-dependent cytokines potentially secreted by tumor cells on the biology of isolated TILs. Our study delineates two major groups of patients. The first group (33% of cases, mostly MSS with a low immunoscore) featured no active caspase-1 in tumor cells, no or low levels of mature IL-18 and IFNγ and only few T-bet+ TILs in the tumor microenvironment. This profile could correspond to an immune escape mechanism facilitating tumor progression. The second group (66% of cases, both MSI and MSS with high immunoscore) featured active caspase-1 in tumor cells associated with mature IL-18 secretion, high density of T-bet+ TILs expressing IL-18Rα and IFNγ release in most cases. In addition, isolated IL-18Rα+ TILs cultured with recombinant IL-18 were able to secrete IFNγ, either left unstimulated or stimulated with anti-CD3. In these CRC, the inflammasome of tumor cells, maintained and active, can contribute to a Th1/Tc1 antitumor response elicited by TILs present in the microenvironment that can modulate tumor growth. Interestingly, in a few cases of this second group (MSI CRC), the numerous T-bet+ TILs were unable to generate a Th1 response. Noticeably, these TILs express numerous immune checkpoints including PD1 and TIGIT, potentially responsible for their exhaustion. This study is the first to delineate functional interactions between tumor cells and TILs in CRC, using ex vivo explant cultures. Altogether, our findings support the inflammasome of tumor cells as a potential new therapeutic target to strengthen the Th1/Tc1 immune response in CRC, in association with immune checkpoint blockers. This work is supported by the “Ligue contre le Cancer Grand Ouest” Citation Format: Linda Bilonda, Delphine Dansette, Cecile Deleine, Romain Oger, Nicolas Jouand, Juliette Podevin, Pierre Fourquier, Emilie Thibaudeau, Jerome Chetritt, Jean-François Mosnier, Celine Bossard, Nadine Gervois, Anne Jarry. The inflammasome of tumor cells modulates the biology of tumor-infiltrating T lymphocytes in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4061.

International audience; Although CD4 C CD8 C double positive (DP) T cells represent a small fraction of peripheral T lymphocytes in healthy human donors, their frequency is often increased under pathological conditions (in blood and targeted tissues). In solid cancers such as melanoma, we previously demonstrated an enrichment of tumor reactive CD4 low CD8 high ab DP T cells among tumor-infiltrating lymphocytes of unknown function. Similarly to their single positive (SP) CD8 C counterparts, intra-melanoma DP T cells recognized melanoma cell lines in an HLA-class-I restricted context. However, they presented a poor cytotoxic activity but a strong production of diverse Th1 and Th2 cytokines. The aim of this study was to clearly define the role of intra-melanoma CD4 low CD8 high ab DP T cells in the antitumor immune response. Based on a comparative transcriptome analysis between intra-melanoma SP CD4 C , SP CD8 C and DP autologous melanoma-infiltrating T-cell compartments, we evidenced an overexpression of the CD40L co-stimulatory molecule on activated DP T cells. We showed that, like SP CD4 C T cells, and through CD40L involvement, DP T cells are able to induce both proliferation and differentiation of B lymphocytes and maturation of functional DCs able to efficiently prime cytotoxic melanoma-specific CD8 T-cell responses. Taken together, these results highlight the helper potential of atypical DP T cells and their role in potentiating antitumor response.

e23087 Background: In colorectal cancer (CRC), little is known about mechanisms by which tumor cells can influence the phenotype and biology of Tumor Infiltrating T lymphocytes (TILs) of the tumor microenvironment. One of these mechanisms could be the inflammasome, a molecular platform present in normal intestinal epithelial cells, whose effector protein, caspase-1, can rapidly mature IL18 and generate a mucosal Th1/Tc1 (IFNγ) response. However, the inflammasome status of tumor cells in CRC and its potential role on TILs are unknown yet. Methods: Prospective and retrospective cohort studies aimed to determine in CRC patients: the status of the inflammasome in tumor cells (IL18 immunostaining on tissue microarrays (TMA) and in situ detection of active caspase-1 on frozen sections) and the density of TILs (CD8+, T-bet+) in relation with i) the microsatellite stable (MSS) or unstable (MSI) status of CRC, and ii) the levels of cytokines (IL18, IFNγ) secreted in an ex vivo explant culture model of CRC. Finally, we assessed the effect of recombinant human IL18 (rhIL18) on the IFNγ response of isolated TILs. Results: TMA analysis of the retrospective cohort showed that IL18 was significantly expressed (in more than 50% of tumor cells) in 80% of CRC, especially in MSI CRC, and correlated with a high density of T-bet+ and CD8+ intraepithelial TILs (IEL-TILs). Active caspase-1 was detected in tumor cells in 60% of CRC. In the prospective cohort, the presence of active caspase-1 in tumor cells was associated with high levels of mature IL18 secreted in explant cultures, with high density of T-bet+ TILs and with IFNγ release in most cases. In addition, isolated TILs expressing IL18 receptors (IL18Rα), cultured with rhIL18, were able to secrete IFNγ either unstimulated or stimulated with OKT3. Conclusions: The inflammasome of tumor cells, when maintained and active, can contribute to a Th1/Tc1 antitumor immune response elicited by TILs, that can modulate tumor growth. The inflammasome of tumor cells can thus be considered as a potential new therapeutic target to strengthen the antitumor immune response in CRC, in association with other immunotherapies.

Accumulating evidence that serum levels of soluble class I HLA molecules (sHLA-I) can, under various pathological conditions, correlate with disease stage and/or patient survival, has stimulated interest in defining whether sHLA-I can exert immunological functions. However, despite a mounting number of publications suggesting the ability of sHLA-I to affect immune effectors in vitro, the precise underlying mechanism still remains controversial. In this article, we address potential functions of both classical and nonclassical sHLA-I, using soluble recombinant HLA-I/peptide monomers, and clearly demonstrate their ability to trigger Ag-specific activation of CD8 T cells in vitro. Furthermore, we provide strong evidence that this behavior results from the passive transfer of peptides from monomers to T cell–bound HLA-I molecules, allowing for fratricide representation and activation. Hence, we proposed a unifying model of T cell activation by HLA-I/peptide monomers, reappraising the potential involvement of sHLA-I molecules in the immune response.

International audience; Although association between CMV infection and allograft rejection is well admitted, the precise mechanisms involved remain uncertain. Here, we report the characterization of an alloreactive HLA-E-restricted CD8 T cell population that was detected in the PBL of a kidney transplant patient after its CMV conversion. This monoclonal CD8 T cell population represents a sizable fraction in the blood (3% of PBL) and is characterized by an effector-memory phenotype and the expression of multiple NK receptors. Interestingly, these unconventional T cells display HLA-E-dependent reactivity against peptides derived from the leader sequences of both various HCMV-UL40 and allogeneic classical HLA-I molecules. Consequently, while HLA-E-restricted CD8 T cells have potential to contribute to the control of CMV infection in vivo, they may also directly mediate graft rejection through recognition of peptides derived from allogeneic HLA-I molecules on graft cells. Therefore, as HLA-E expression in nonlymphoid organs is mainly restricted to endothelial cells, we investigated the reactivity of this HLA-E-restricted T cell population towards allogeneic endothelial cells. We clearly demonstrated that CMV-associated HLA-E-restricted T cells efficiently recognized and killed allogeneic endothelial cells in vitro. Moreover, our data indicate that this alloreactivity is tightly regulated by NK receptors, especially by inhibitory KIR2DL2 that strongly prevents TCR-induced activation through recognition of HLA-C molecules. Hence, a better evaluation of the role of CMV-associated HLA-E-restricted T cells in transplantation and of the impact of HLA-genotype, especially HLA-C, on their alloreactivity may determine whether they indeed represent a risk factor following organ transplantation. Citation: Allard M, Tonnerre P, Nedellec S, Oger R, Morice A, et al. (2012) HLA-E-Restricted Cross-Recognition of Allogeneic Endothelial Cells by CMV-Associated CD8 T Cells: A Potential Risk Factor following Transplantation. PLoS ONE 7(11): e50951.