αvβ3-dependent cross-presentation of matrix metalloproteinase–2 by melanoma cells gives rise to a new tumor antigen

A large array of antigens that are recognized by tumor-specific T cells has been identified and shown to be generated through various processes. We describe a new mechanism underlying T cell recognition of melanoma cells, which involves the generation of a major histocompatibility complex class I–restricted epitope after tumor-mediated uptake and processing of an extracellular protein—a process referred to as cross-presentation—which is believed to be restricted to immune cells. We show that melanoma cells cross-present, in an αvβ3-dependent manner, an antigen derived from secreted matrix metalloproteinase–2 (MMP-2) to human leukocyte antigen A*0201-restricted T cells. Because MMP-2 activity is critical for melanoma progression, the MMP-2 peptide should be cross-presented by most progressing melanomas and represents a unique antigen for vaccine therapy of these tumors

CD4CD8αα Lymphocytes, A Novel Human Regulatory T Cell Subset Induced by Colonic Bacteria and Deficient in Patients with Inflammatory Bowel Disease

It has become evident that bacteria in our gut affect health and disease, but less is known about how they do this. Recent studies in mice showed that gut Clostridium bacteria and their metabolites can activate regulatory T cells (Treg) that in turn mediate tolerance to signals that would ordinarily cause inflammation. In this study we identify a subset of human T lymphocytes, designated CD4CD8αα T cells that are present in the surface lining of the colon and in the blood. We demonstrate Treg activity and show these cells to be activated by microbiota; we identify F. prausnitzii, a core Clostridium strain of the human gut microbiota, as a major inducer of these Treg cells. Interestingly, there are fewer F. prausnitzii in individuals suffering from inflammatory bowel disease (IBD), and accordingly the CD4CD8αα T cells are decreased in the blood and gut of patients with IBD. We argue that CD4CD8αα colonic Treg probably help control or prevent IBD. These data open the road to new diagnostic and therapeutic strategies for the management of IBD and provide new tools to address the impact of the intestinal microbiota on the human immune system

Folding of Matrix Metalloproteinase-2 Prevents Endogenous Generation of MHC Class-I Restricted Epitope

BACKGROUND: We previously demonstrated that the matrix metalloproteinase-2 (MMP-2) contained an antigenic peptide recognized by a CD8 T cell clone in the HLA-A*0201 context. The presentation of this peptide on class I molecules by human melanoma cells required a cross-presentation mechanism. Surprisingly, the classical endogenous processing pathway did not process this MMP-2 epitope. METHODOLOGY/PRINCIPAL FINDINGS: By PCR directed mutagenesis we showed that disruption of a single disulfide bond induced MMP-2 epitope presentation. By Pulse-Chase experiment, we demonstrated that disulfide bonds stabilized MMP-2 and impeded its degradation. Finally, using drugs, we documented that mutated MMP-2 epitope presentation used the proteasome and retrotranslocation complex. CONCLUSIONS/SIGNIFICANCE: These data appear crucial to us since they established the existence of a new inhibitory mechanism for the generation of a T cell epitope. In spite of MMP-2 classified as a self-antigen, the fact that cross-presentation is the only way to present this MMP-2 epitope underlines the importance to target this type of antigen in immunotherapy protocols

Rôle du récepteur CD94/NKG2-A dans la réponse T anti-tumorale et recherche d'antigènes reconnus par les lymphocytes T CD8+ infiltrant les tumeurs du sein

La première partie porte sur le rôle du récepteur inhibiteur CD94/NKG2-A dans la réponse T anti-tumorale. Les résultats montrent que 1) l'IL-12 induit l'expression de ce récepteur à la surface des lymphocytes T CD8+, 2) la plupart des lignées de mélanome exprime le ligand de ce récepteur : la molécule HLA-E, à différents niveaux, 3) l'expression de HLA-E est augmentée par l'IFN-g. De plus, nous avons observé l'existence d'une balance entre le signal d'activation dépendant du TCR et le signal d'inhibition médié par l'interaction CD94/NKG2-A/HLA-E. Ces résultats suggèrent que le récepteur CD94/NKG2-A et la molécule HLA-E, dont l'expression est régulée par différents facteurs, participeraient au phénomène d'échappement tumoral. Dans une deuxième partie, nous avons recherché la présence de lymphocytes T CD8+ spécifiques d'antigènes de tumeurs de sein parmi les TIL (Tumor Infiltrating Lymphocytes). Sur les 34 populations de TIL testés contre 48 antigènes de cancer du sein, quatre répondent aux antigènes P53, GAGE-6 et LAGE-1a dans quatre contextes HLA-A, B, ou Cw différents. Nous recherchons à définir les épitopes reconnus, dont la caractérisation permettra de réaliser de nouveaux protocoles d'immunothérapies visant ces antigènes.In the first part, we have studies the role of the CD94/NKG2-A receptor in anti-tumoral T cell response The results show that 1) IL-12 induce the expression of this receptor in CD8 T cell, 2) the ligand of this NKR : HLA-E is expressed, although at different levels, by human melanoma cell lines, 3) IFN-gamma-treatment up-regulates this expression. We further show that inhibition of the response of melanoma antigen specific T cell clones was correlated with the density of HLA-E on melanoma cells and the density of CD94/NKG2-A on the CTL, but inversely correlated with the strength of the TCR-dependant. In the second part, 34 tumor infiltrating lymphocytes (TIL) cultures established from breast tumor or invaded lymph nodes were screened for recognition of 48 breast associated antigens. Four TIL lines reacted to three antigens (P53, GAGE-6 and LAGE-1a) in association with four differents HLA molecules. The caraterisation of this new epitopes could lead to realise new immunotherapy protocols for breast cancer patients targeting this antigens.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Adoptive transfer with high-affinity TCR to treat human solid tumors: how to improve the feasibility?

International audienceThe adoptive transfer of tumor antigen-specific T cells recently achieved clinical efficacy for a fraction of melanoma patients refractory to other therapies. Unfortunately , the application of this strategy to the remaining melanoma and most other cancer patients is hampered by the difficulty to generate high-affinity tumor-reactive T cells. Two strategies are currently developed to extend the feasibility of this therapeutic approach: clinical grade tool production for MHC-peptide multimer-driven sorting of antigen-specific T cells from the endogenous peripheral T cell repertoire and de novo engineering of the missing repertoire by genetic transfer of cloned specific T cell receptor (TCR) into T cells. The expected multiplication of adoptive transfer treatments, by these strategies, and their careful evaluation should enable the cure of a number of otherwise compromised cancer patients and to gain insight into the characteristics of transferred T cells best fitted to eradicate tumor cells, in terms of antigen specificities, phenotype, and functions. In particular, identification of tumor-rejection antigens by this approach would improve the design and efficacy of all immuno-therapeutic approaches

Lymphocyte Biomarkers of Clinical Responses to Adoptive Immunotherapy of Malignant Melanoma

International audienceDuring the last few years, adoptive cellular therapy (ACT)-the isolation of antigen-specific lymphocytes, their ex vivo expansion and activation, and subsequent autologous administration-has been tested for treatment of melanoma tumours. Initial ACT used melanoma-infiltrating lymphocytes (TIL) that often contain tumour reactive lym-phocytes, of diverse, mostly unknown, specificities [1, 2]. Recently, the identification of melanoma antigens [3] and the development of techniques for selection and expansion of epitope specific T cells has opened the way to the use of tumour antigen specific T cells, and importantly to immune follow up of ACT [4-9]. Despite these advances, several issues remain to address to achieve the major aims of ACT, as the rapid production of clinical grade T cells capable of eliciting a significant destruction of tumour tissue