Papers by Nathalie Demotte
Purpose: Several galectins are released by tumor cells and macrophages and accumulate in the tumo... more Purpose: Several galectins are released by tumor cells and macrophages and accumulate in the tumor microenvironment. Galectin-1 and -3 were found to bind to glycosylated receptors at the surface of tumor-infiltrating lymphocytes (TIL), forming glycoprotein–galectin lattices that could reduce the motility and therefore the functionality of surface molecules. In contrast to blood T cells, human TIL show defective IFN-γ secretion upon ex vivo stimulation. We have previously shown that extracellular galectin-3 participates in the impairment of TIL functions. Indeed, disruption of glycoprotein–galectin-3 lattices using anti-galectin-3 antibodies, or N-acetyllactosamine as a competing sugar, boosted cytokine secretion by TIL. Here we have tested a clinical grade galectin antagonist: GM-CT-01, a galactomannan obtained from guar gum reported to be safe in more than 50 patients with cancer.Experimental Design: TIL were isolated from human tumor ascites, treated for 2 to 20 hours with galecti...
Immunity, 2008
For several days after antigenic stimulation, human cytolytic T lymphocyte (CTL) clones exhibit a... more For several days after antigenic stimulation, human cytolytic T lymphocyte (CTL) clones exhibit a decrease in their effector activity and in their binding to human leukocyte antigen (HLA)-peptide tetramers. We observed that, when in this state, CTLs lose the colocalization of the T cell receptor (TCR) and CD8. Effector function and TCR-CD8 colocalization were restored with galectin disaccharide ligands, suggesting that the binding of TCR to galectin plays a role in the distancing of TCR from CD8. These findings appear to be applicable in vivo, as TCR was observed to be distant from CD8 on human tumor-infiltrating lymphocytes, which were anergic. These lymphocytes recovered effector functions and TCR-CD8 colocalization after ex vivo treatment with galectin disaccharide ligands. The separation of TCR and CD8 molecules could be one major mechanism of anergy in tumors and other chronic stimulation conditions.
Cancer Research, 2010
Human CD8 + tumor-infiltrating T lymphocytes (TIL), in contrast with CD8 + blood cells, show impa... more Human CD8 + tumor-infiltrating T lymphocytes (TIL), in contrast with CD8 + blood cells, show impaired IFN-γ secretion on ex vivo restimulation. We have attributed the impaired IFN-γ secretion to a decreased mobility of T-cell receptors on trapping in a lattice of glycoproteins clustered by extracellular galectin-3. Indeed, we have previously shown that treatment with N-acetyllactosamine, a galectin ligand, restored this secretion. We strengthened this hypothesis here by showing that CD8 + TIL treated with an anti-galectin-3 antibody had an increased IFN-γ secretion. Moreover, we found that GCS-100, a polysaccharide in clinical development, detached galectin-3 from TIL and boosted cytotoxicity and secretion of different cytokines. Importantly, we observed that not only CD8 + TIL but also CD4 + TIL treated with GCS-100 secreted more IFN-γ on ex vivo restimulation. In tumor-bearing mice vaccinated with a tumor antigen, injections of GCS-100 led to tumor rejection in half of the mice, whereas all control mice died. In nonvaccinated mice, GCS-100 had no effect by itself. These results suggest that a combination of galectin-3 ligands and therapeutic vaccination may induce more tumor regressions in cancer patients than vaccination alone. Cancer Res; 70(19); 7476-88. ©2010 AACR.
MAGE genes are expressed by many human tumors of different histological types but not by normal c... more MAGE genes are expressed by many human tumors of different histological types but not by normal cells, except for male germline cells. The Ags encoded by MAGE genes and recognized by T cells are therefore strictly tumor-specific. Clinical trials involving therapeutic vaccination of cancer patients with MAGE antigenic peptides or proteins are in progress. To increase the range of patients eligible for therapy with peptides, it is important to identify additional MAGE epitopes recognized by CTL. Candidate peptides known to bind to a given HLA have been used to stimulate T lymphocytes in vitro. In some instances, CTL clones directed against these synthetic peptides have been obtained, but these clones often failed to recognize tumor cells expressing the relevant gene. Therefore, we designed a method to identify CTL epitopes that selects naturally processed peptides. Monocyte-derived dendritic cells infected with a recombinant canarypoxvirus (ALVAC) containing the entire MAGE-A1 gene we...
distinct red/green only red only green overlapping red/green undefined tetramerlo 131 10 13 0 6 t... more distinct red/green only red only green overlapping red/green undefined tetramerlo 131 10 13 0 6 tetramerhi 34 3 12 108 3 For both the tetramerhi and the tetramerlo subpopulations, 40 cells were analyzed as in Figure 2A. Cells were round and not in contact with other cells. For each cell, intensity profiles were obtained at four different membrane locations. Each profile was scored as follows: distinct red/green profiles where the peak are separated by ~0.5 µm, only a red peak, only a green peak, or a green peak overlapping the red peak.
Purpose: Several galectins are released by tumor cells and macrophages and accumulate in the tumo... more Purpose: Several galectins are released by tumor cells and macrophages and accumulate in the tumor microenvironment. Galectin-1 and -3 were found to bind to glycosylated receptors at the surface of tumor-infiltrating lymphocytes (TIL), forming glycoprotein-galectin lattices that could reduce the motility and therefore the functionality of surface molecules. In contrast to blood T cells, human TIL show defective IFNsecretion upon ex vivo stimulation. We have previously shown that extracellular galectin-3 participates in the impairment of TIL functions. Indeed, disruption of glycoprotein-galectin-3 lattices using anti-galectin-3 antibodies, or N-acetyllactosamine as a competing sugar, boosted cytokine secretion by TIL. Here we have tested a clinical grade galectin antagonist: GM-CT-01, a galactomannan obtained from guar gum reported to be safe in more than 50 cancer patients. Experimental Design: TIL were isolated from human tumor ascites, treated for 2-20 h with galectin antagonists ...
MAGE genes are expressed by many human tumors of different histological types but not by normal c... more MAGE genes are expressed by many human tumors of different histological types but not by normal cells, except for male germline cells. The Ags encoded by MAGE genes and recognized by T cells are therefore strictly tumor-specific. Clinical trials involving therapeutic vaccination of cancer patients with MAGE antigenic peptides or proteins are in progress. To increase the range of patients eligible for therapy with peptides, it is important to identify additional MAGE epitopes recognized by CTL. Candidate peptides known to bind to a given HLA have been used to stimulate T lymphocytes in vitro. In some instances, CTL clones directed against these synthetic peptides have been obtained, but these clones often failed to recognize tumor cells expressing the relevant gene. Therefore, we designed a method to identify CTL epitopes that selects naturally processed peptides. Monocyte-derived dendritic cells infected with a recombinant canarypoxvirus (ALVAC) containing the entire MAGE-A1 gene were used to stimulate CD8 ؉ T lymphocytes from the blood of individuals without cancer. Responder cell microcultures that specifically lysed autologous cells expressing MAGE-A1 were cloned using autologous stimulator cells either transduced with a retrovirus coding for MAGE-A1 or infected with recombinant Yersinia-MAGE-A1 bacteria. The CTL clones were tested for their ability to lyse autologous cells loaded with each of a set of overlapping MAGE-A1 peptides. This strategy led to the identification of five new MAGE-A1 epitopes recognized by CTL clones on HLA-A3,-A28,-B53,-Cw2, and-Cw3 molecules. All of these CTL clones recognized target cells expressing gene MAGE-A1.
Il y a dix ans, nous avons observe que des clones CTL perdaient leur capacite a lyser des cellule... more Il y a dix ans, nous avons observe que des clones CTL perdaient leur capacite a lyser des cellules cibles presentant un antigene si, au lieu d’etre stimules par des cellules tumorales, ils etaient stimules avec des lymphocytes B immortalisees par le virus EBV prealablement incubees avec le peptide antigenique. Nous avons decrit pour deux clones CTL que la perte de capacite a lyser etait correlee a une diminution de la capacite a se lier a un tetramere CMHpeptide. Ces resultats presentaient un nouveau type d’anergie et suggeraient l’existence de CTL furtifs qui echappent a la detection par un tetramere CMH-peptide alors qu’ils peuvent jouer un role dans une reponse anti-tumorale. Nous avons ensuite analyse l’evolution de la capacite a lier un tetramere CMHpeptide apres stimulation et nous avons observe que presque tous les clones CTL perdaient cette capacite dans les heures qui suivent une stimulation antigenique. Cette propriete etait recuperee endeans les deux semaines. La diminuti...
Nature communications, Jul 22, 2016
Surface galectin has been shown to contribute to dysfunctions of human tumour-infiltrating lympho... more Surface galectin has been shown to contribute to dysfunctions of human tumour-infiltrating lymphocytes (TILs). We show here that galectin-covered CD8 TILs produce normal amounts of intracellular cytokines, but fail to secrete them because of defective actin rearrangements at the synapse. The non-secreting TILs also display reduced adhesion to their targets, together with defective LFA-1 recruitment and activation at the synapse. These defects are relieved by releasing surface galectin. As mild LFA-1 blockade on normal blood T cells emulate the defects of galectin-covered TILs, we conclude that galectin prevents the formation of a functional secretory synapse by preventing optimal LFA-1 triggering. Our results highlight a major secretory defect of TILs that is not revealed by widely used intracellular cytokine immunomonitoring assays. They also provide additional insights into the T-cell response, by showing that different thresholds of LFA-1 triggering are required to promote the in...
The identification of tumor-specific antigens recognized by T lymphocytes on human cancer cells h... more The identification of tumor-specific antigens recognized by T lymphocytes on human cancer cells has elicited numerous vaccination trials of cancer patients with defined tumor antigens. These treatments have induced T cell responses but have shown a low clinical efficacy in tumor-bearing melanoma patients. Immunosuppression at the tumor sites is the most likely explanation for the poor effectiveness of cancer vaccines. Many researchers are trying to decipher the underlying immunosuppressive mechanism. Galectin-3, a lectin secreted by tumor cells and macrophages, plays a role in the dysfunction of tumor-infiltrating T lymphocytes (TIL). We have observed that human TIL, in contrast with CD8 blood cells, show impaired IFN-γ secretion and cytotoxicity. TIL dysfunction correlates with the segregation of T cell receptor (TCR) and CD8 co-receptor at the T cell surface. Treating TIL with soluble galectin ligands or an anti-galectin-3 antibody restored IFN-γ secretion, cytotoxicity and TCR/CD8 co-localization. Our working hypothesis is that TIL, having been stimulated recently by their antigen, harbor a set of glycans that contain numerous ligands for galectins, which block their proper function. In agreement with this hypothesis, we have recently observed that, compared to resting CD8 T cell clones, the N-glycans of recently activated clones contains more multi-antennary N-glycans and consists of longer LacNAc chains. We propose that therapeutic vaccines combined with soluble galectin ligands could reverse local immunosuppression at the tumor site and may induce more tumor regressions in cancer patients than vaccination alone
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Papers by Nathalie Demotte