Changes in transcriptomic landscape with macronutrients intake switch are independent from O-GlcNAcylation levels in heart throughout postnatal development in rats

Background

Dietary intake and metabolism variations are associated with molecular changes and more particularly in the transcriptome. O-GlcNAcylation is a post-translational modification added and removed respectively by OGT and OGA. The UDP-GlcNAc, the substrate of OGT, is produced by UAP1 and UAP1L1. O-GlcNAcylation is qualified as a metabolic sensor and is involved in the modulation of gene expression. We wanted to unveil if O-GlcNAcylation is linking metabolic transition to transcriptomic changes and to highlight modifications of O-GlcNAcylation during the postnatal cardiac development.

Methods

Hearts were harvested from rats at birth (D0), before (D12) and after suckling to weaning transition with normal (D28) or delayed weaning diet from D12 to D28 (D28F). O-GlcNAcylation levels and proteins expression were evaluated by Western blot. Cardiac transcriptomes were evaluated via 3'SRP analysis.

Results

Cardiac O-GlcNAcylation levels and nucleocytoplasmic OGT (ncOGT) were decreased at D28 while full length OGA (OGA) was increased. O-GlcNAcylation levels did not changed with delayed weaning diet while ncOGT and OGA were respectively increased and decreased. Uapl1 was the only O-GlcNAcylation-related gene identified as differentially expressed throughout postnatal development.

Conclusion

Macronutrients switch promotes changes in the transcriptome landscape that are independent from O-GlcNAcylation levels. UAP1 and UAP1L1 are not the main regulator element of O-GlcNAcylation throughout postnatal development.

A role for ceruloplasmin in the control of human glioblastoma cell responses to radiation

Background

Glioblastoma (GB) is the most common and most aggressive malignant brain tumor. In understanding its resistance to conventional treatments, iron metabolism and related pathways may represent a novel avenue. As for many cancer cells, GB cell growth is dependent on iron, which is tightly involved in red-ox reactions related to radiotherapy effectiveness. From new observations indicating an impact of RX radiations on the expression of ceruloplasmin (CP), an important regulator of iron metabolism, the aim of the present work was to study the functional effects of constitutive expression of CP within GB lines in response to beam radiation depending on the oxygen status (21% O₂ versus 3% O₂).

Methods and results

After analysis of radiation responses (Hoechst staining, LDH release, Caspase 3 activation) in U251-MG and U87-MG human GB cell lines, described as radiosensitive and radioresistant respectively, the expression of 9 iron partners (TFR1, DMT1, FTH1, FTL, MFRN1, MFRN2, FXN, FPN1, CP) were tested by RTqPCR and western blots at 3 and 8 days following 4 Gy irradiation. Among those, only CP was significantly downregulated, both at transcript and protein levels in the two lines, with however, a weaker effect in the U87-MG, observable at 3% O₂. To investigate specific role of CP in GB radioresistance, U251-MG and U87-MG cells were modified genetically to obtain CP depleted and overexpressing cells, respectively. Manipulation of CP expression in GB lines demonstrated impact both on cell survival and on activation of DNA repair/damage machinery (γH2AX); specifically high levels of CP led to increased production of reactive oxygen species, as shown by elevated levels of superoxide anion, SOD1 synthesis and cellular Fe2 + .

Conclusions

Taken together, these in vitro results indicate for the first time that CP plays a positive role in the efficiency of radiotherapy on GB cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09808-6.

Targeted alpha particle therapy remodels the tumor microenvironment and improves efficacy of immunotherapy

PURPOSE

Tumor microenvironment (TME) can severely impair immunotherapy efficacy by repressing the immune system. In a Multiple Myeloma (MM) murine model, we investigated the impact of Targeted alpha-particle therapy (TAT) on the immune TME. TAT was combined with an adoptive cell transfer of CD8 T-cells (ACT), and the mechanisms of action of this combination were assessed at the tumor site.

METHODS

This combination treatment was conducted in a syngeneic MM murine model grafted subcutaneously. TAT was delivered by i.v. injection of a bismuth-213 radiolabelled anti-CD138 antibody. To strengthen anti-tumor immune response, TAT was combined with an ACT of tumor specific CD8+ OT-1 T-cells. The tumors were collected and the immune TME analyzed by flow cytometry, immunohistochemistry and ex vivo T-cell motility assay on tumor slices. The chemokine and cytokine productions were also assessed by RT-qPCR.

RESULTS

Tumor specific CD8+ OT-1 T-cells infiltrated the tumors after ACT. However only treatment with TAT resulted in regulatory CD4 T-cell drop and transient increased production of IL-2, CCL-5 and IFNγ within the tumor. Moreover, OT-1 T-cell recruitment and motility were increased on tumor slices from TAT-treated mice as observed by ex vivo time lapse, contributing to a more homogeneous distribution of OT-1 T-cells in the tumor. Subsequently, the tumor cells increased PD-L1 expression, anti-tumor cytokine production decreased and OT-1 T-cells overexpressed exhaustion markers, suggesting an exhaustion of the immune response.

CONCLUSION

Combining TAT and ACT seems to transiently remodel the cold TME, improving ACT efficiency. The immune response then leads to the establishment of other tumor cell resistance mechanisms.

Anti-tumor efficacy of a combination therapy with PD-L1 targeted alpha therapy and adoptive cell transfer of PD-1 deficient melanoma-specific human T-lymphocytes

The optimization of adoptive transfer approaches of anti-tumor T cells requires both the functional improvement of the injected T cells and the modulation of the tumor microenvironment, favoring the recruitment of these T cells and their activation. We have recently shown the therapeutic benefit of two approaches tested individually in a melanoma model wich were on one hand the adoptive transfer of specific T cells deficient for the expression of the inhibitory receptor PD-1, and on the other hand PD-L1 targeted alpha therapy (TAT). In this study, we sought to investigate the efficacy of these two therapies combined, compared to each monotherapy, in order to evaluate the synergy between these two approaches, in the same melanoma model. Here we used melanoma-specific T-cell clones, previously validated for the edition of PDCD1 gene and with previously demonstrated superior anti-tumor activity than their wild-type counterparts, after adoptive transfer in NSG mice engrafted with PD-L1 expressing human melanoma tumors. We also used a previously validated TAT approach, using a ²¹³Bi-anti-human-PD-L1 mAb, alone or in combination with adoptive cell transfer, in the same mouse model. We confirmed previous results obtained with each monotherapy and documented the safety and the superior ability of a combination between the adoptive transfer of PD-1 deficient T cells and TAT targeting PD-L1 to control the growth of melanoma tumors in NSG mice. This study provides the first proof-of-concept of the efficacy of a combination therapy using TAT, adoptive cell transfer and genomic editing of IC-coding genes.

Anti-Tumor Efficacy of PD-L1 Targeted Alpha-Particle Therapy in a Human Melanoma Xenograft Model

Simple Summary

In recent years, the development of immune checkpoint inhibitors, such as anti-PD‑1 and anti-PD-L1, proved to prolong melanoma patient survival and are now used in routine clinical practice. PD-L1 also represents a potent biomarker for in vivo molecular imaging using radiolabeled anti-PD-L1 mAbs and positron emission tomography and is currently in development to select patients and assess response to treatment. The aim of our study was to investigate in a preclinical model of human melanoma if PD-L1 could also be a good target for treatment using targeted alpha-particle therapy. Our results show that targeting PD-L1 with bismuth-213, an alpha particle emitter, was associated with efficient anti-tumor response, significant tumor growth delay, and improved survival. This demonstrates that anti-PD-L1 antibodies could be used as theranostics in molecular imaging but also in targeted alpha-particle therapy to treat the tumor and its stroma.

Abstract

PD-L1 (programmed death-ligand 1, B7-H1, CD274), the ligand for PD-1 inhibitory receptor, is expressed on various tumors, and its expression is correlated with a poor prognosis in melanoma. Anti-PD-L1 mAbs have been developed along with anti-CTLA-4 and anti-PD-1 antibodies for immune checkpoint inhibitor (ICI) therapy, and anti-PD-1 mAbs are now used as first line treatment in melanoma. However, many patients do not respond to ICI therapies, and therefore new treatment alternatives should be developed. Because of its expression on the tumor cells and on immunosuppressive cells within the tumor microenvironment, PD-L1 represents an interesting target for targeted alpha-particle therapy (TAT). We developed a TAT approach in a human melanoma xenograft model that stably expresses PD-L1 using a ²¹³Bi-anti-human-PD-L1 mAb. Unlike treatment with unlabeled anti-human-PD-L1 mAb, TAT targeting PD-L1 significantly delayed melanoma tumor growth and improved animal survival. A slight decrease in platelets was observed, but no toxicity on red blood cells, bone marrow, liver or kidney was induced. Anti-tumor efficacy was associated with specific tumor targeting since no therapeutic effect was observed in animals bearing PD-L1 negative melanoma tumors. This study demonstrates that anti-PD-L1 antibodies may be used efficiently for TAT treatment in melanoma.

Cell Tracking in Cancer Immunotherapy

The impressive development of cancer immunotherapy in the last few years originates from a more precise understanding of control mechanisms in the immune system leading to the discovery of new targets and new therapeutic tools. Since different stages of disease progression elicit different local and systemic inflammatory responses, the ability to longitudinally interrogate the migration and expansion of immune cells throughout the whole body will greatly facilitate disease characterization and guide selection of appropriate treatment regiments. While using radiolabeled white blood cells to detect inflammatory lesions has been a classical nuclear medicine technique for years, new non-invasive methods for monitoring the distribution and migration of biologically active cells in living organisms have emerged. They are designed to improve detection sensitivity and allow for a better preservation of cell activity and integrity. These methods include the monitoring of therapeutic cells but also of all cells related to a specific disease or therapeutic approach. Labeling of therapeutic cells for imaging may be performed in vitro, with some limitations on sensitivity and duration of observation. Alternatively, in vivo cell tracking may be performed by genetically engineering cells or mice so that may be revealed through imaging. In addition, SPECT or PET imaging based on monoclonal antibodies has been used to detect tumors in the human body for years. They may be used to detect and quantify the presence of specific cells within cancer lesions. These methods have been the object of several recent reviews that have concentrated on technical aspects, stressing the differences between direct and indirect labeling. They are briefly described here by distinguishing ex vivo (labeling cells with paramagnetic, radioactive, or fluorescent tracers) and in vivo (in vivo capture of injected radioactive, fluorescent or luminescent tracers, or by using labeled antibodies, ligands, or pre-targeted clickable substrates) imaging methods. This review focuses on cell tracking in specific therapeutic applications, namely cell therapy, and particularly CAR (Chimeric Antigen Receptor) T-cell therapy, which is a fast-growing research field with various therapeutic indications. The potential impact of imaging on the progress of these new therapeutic modalities is discussed.

[Alpha-Radioimmunotherapy: principle and relevance in anti-tumor immunity]

Alpha-radioimmunotherapy (α-RIT) is a targeted anti-tumor therapy using usually a monoclonal antibody specific for a tumor antigen that is coupled to an α-particle emitter. α-emitters represent an ideal tool to eradicate disseminated tumors or metastases. Recent data demonstrate that ionizing radiation in addition to its direct cytotoxic ability can also induce an efficient anti-tumor immunity. This suggests that biologic effects on irradiated tissues could be used to potentiate immunotherapy efficacy and opens the way for development of new therapies combining α-RIT and different types of immunotherapy.

Alpha Particles Induce Autophagy in Multiple Myeloma Cells

OBJECTIVES

Radiation emitted by the radionuclides in radioimmunotherapy (RIT) approaches induce direct killing of the targeted cells as well as indirect killing through the bystander effect. Our research group is dedicated to the development of α-RIT, i.e., RIT using α-particles especially for the treatment of multiple myeloma (MM). γ-irradiation and β-irradiation have been shown to trigger apoptosis in tumor cells. Cell death mode induced by (213)Bi α-irradiation appears more controversial. We therefore decided to investigate the effects of (213)Bi on MM cell radiobiology, notably cell death mechanisms as well as tumor cell immunogenicity after irradiation.

METHODS

Murine 5T33 and human LP-1 MM cell lines were used to study the effects of such α-particles. We first examined the effects of (213)Bi on proliferation rate, double-strand DNA breaks, cell cycle, and cell death. Then, we investigated autophagy after (213)Bi irradiation. Finally, a coculture of dendritic cells (DCs) with irradiated tumor cells or their culture media was performed to test whether it would induce DC activation.

RESULTS

We showed that (213)Bi induces DNA double-strand breaks, cell cycle arrest, and autophagy in both cell lines, but we detected only slight levels of early apoptosis within the 120 h following irradiation in 5T33 and LP-1. Inhibition of autophagy prevented (213)Bi-induced inhibition of proliferation in LP-1 suggesting that this mechanism is involved in cell death after irradiation. We then assessed the immunogenicity of irradiated cells and found that irradiated LP-1 can activate DC through the secretion of soluble factor(s); however, no increase in membrane or extracellular expression of danger-associated molecular patterns was observed after irradiation.

CONCLUSION

This study demonstrates that (213)Bi induces mainly necrosis in MM cells, low levels of apoptosis, and autophagy that might be involved in tumor cell death.

Combining α-Radioimmunotherapy and Adoptive T Cell Therapy to Potentiate Tumor Destruction

Ionizing radiation induces direct and indirect killing of cancer cells and for long has been considered as immunosuppressive. However, this concept has evolved over the past few years with the demonstration that irradiation can increase tumor immunogenicity and can actually favor the implementation of an immune response against tumor cells. Adoptive T-cell transfer (ACT) is also used to treat cancer and several studies have shown that the efficacy of this immunotherapy was enhanced when combined with radiation therapy. α-Radioimmunotherapy (α-RIT) is a type of internal radiotherapy which is currently under development to treat disseminated tumors. α-particles are indeed highly efficient to destroy small cluster of cancer cells with minimal impact on surrounding healthy tissues. We thus hypothesized that, in the setting of α-RIT, an immunotherapy like ACT, could benefit from the immune context induced by irradiation. Hence, we decided to further investigate the possibilities to promote an efficient and long-lasting anti-tumor response by combining α-RIT and ACT. To perform such study we set up a multiple myeloma murine model which express the tumor antigen CD138 and ovalbumine (OVA). Then we evaluated the therapeutic efficacy in the mice treated with α-RIT, using an anti-CD138 antibody coupled to bismuth-213, followed by an adoptive transfer of OVA-specific CD8+ T cells (OT-I CD8+ T cells). We observed a significant tumor growth control and an improved survival in the animals treated with the combined treatment. These results demonstrate the efficacy of combining α-RIT and ACT in the MM model we established.

Antitumor immunity induced after α irradiation

Radioimmunotherapy (RIT) is a therapeutic modality that allows delivering of ionizing radiation directly to targeted cancer cells. Conventional RIT uses β-emitting radioisotopes, but recently, a growing interest has emerged for the clinical development of α particles. α emitters are ideal for killing isolated or small clusters of tumor cells, thanks to their specific characteristics (high linear energy transfer and short path in the tissue), and their effect is less dependent on dose rate, tissue oxygenation, or cell cycle status than γ and X rays. Several studies have been performed to describe α emitter radiobiology and cell death mechanisms induced after α irradiation. But so far, no investigation has been undertaken to analyze the impact of α particles on the immune system, when several studies have shown that external irradiation, using γ and X rays, can foster an antitumor immune response. Therefore, we decided to evaluate the immunogenicity of murine adenocarcinoma MC-38 after bismuth-213 ((213)Bi) irradiation using a vaccination approach. In vivo studies performed in immunocompetent C57Bl/6 mice induced a protective antitumor response that is mediated by tumor-specific T cells. The molecular mechanisms potentially involved in the activation of adaptative immunity were also investigated by in vitro studies. We observed that (213)Bi-treated MC-38 cells release "danger signals" and activate dendritic cells. Our results demonstrate that α irradiation can stimulate adaptive immunity, elicits an efficient antitumor protection, and therefore is an immunogenic cell death inducer, which provides an attractive complement to its direct cytolytic effect on tumor cells.

Using α radiation to boost cancer immunity?

Radioimmunotherapy aims to deliver radiation directly to cancer cells by means of a tumor specific vector coupled to a radionuclide. Alpha radionuclides are very potent agents to treat disseminated cancer and metastasis. We have demonstrated that α radiation can also induce immunogenic cell death, reinforcing interest in their clinical development.

Cross-presentation of synthetic long peptides by human dendritic cells: a process dependent on ERAD component p97/VCP but Not sec61 and/or Derlin-1

Antitumor vaccination using synthetic long peptides (SLP) is an additional therapeutic strategy currently under development. It aims to activate tumor-specific CD8⁺ CTL by professional APCs such as DCs. DCs can activate T lymphocytes by MHC class I presentation of exogenous antigens - a process referred to as “cross-presentation”. Until recently, the intracellular mechanisms involved in cross-presentation of soluble antigens have been unclear. Here, we characterize the cross-presentation pathway of SLP Melan-A_16–40 containing the HLA-A2-restricted epitope_26–35 (A27L) in human DCs. Using confocal microscopy and specific inhibitors, we show that SLP_16–40 is rapidly taken up by DC and follows a classical TAP- and proteasome-dependent cross-presentation pathway. Our data support a role for the ER-associated degradation machinery (ERAD)-related protein p97/VCP in the transport of SLP_16–40 from early endosomes to the cytoplasm but formally exclude both sec61 and Derlin-1 as possible retro-translocation channels for cross-presentation. In addition, we show that generation of the Melan-A_26–35 peptide from the SLP_16–40 was absolutely not influenced by the proteasome subunit composition in DC. Altogether, our findings propose a model for cross-presentation of SLP which tends to enlarge the repertoire of potential candidates for retro-translocation of exogenous antigens to the cytosol.

HLA-E-restricted cross-recognition of allogeneic endothelial cells by CMV-associated CD8 T cells: a potential risk factor following transplantation

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.

Matrix metalloproteinase-2 conditions human dendritic cells to prime inflammatory T(H)2 cells via an IL-12- and OX40L-dependent pathway

Matrix metalloproteinase-2 (MMP-2) is a proteolytic enzyme degrading the extracellular matrix and overexpressed by many tumors. Here, we documented the presence of MMP-2-specific CD4(+) T cells in tumor-infiltrating lymphocytes (TILs) from melanoma patients. Strikingly, MMP-2-specific CD4(+) T cells displayed an inflammatory T(H)2 profile, i.e., mainly secreting TNF-α, IL-4, and IL-13 and expressing GATA-3. Furthermore, MMP-2-conditioned dendritic cells (DCs) primed naïve CD4(+) T cells to differentiate into an inflammatory T(H)2 phenotype through OX40L expression and inhibition of IL-12p70 production. MMP-2 degrades the type I IFN receptor, thereby preventing STAT1 phosphorylation, which is necessary for IL-12p35 production. Active MMP-2, therefore, acts as an endogenous type 2 "conditioner" and may play a role in the observed prevalence of detrimental type 2 responses in melanoma.

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.

MMP-2: A novel target for antitumor immune therapy

3053

Background: Over the last two decades, a large array of antigens expressed by melanoma cells (MAA) has been identified and used in various immunization strategies to treat cancer patients. However, the therapeutic efficacy of these approaches remains limited. Because MMP-2 (matrix metalloproteinase-2) activity is critical for melanoma progression, this protein represents a unique antigen for vaccine therapy. Methods: Antigen-specific T cell clones were obtained from healthy donors. CD4+ cells were stimulated with overlapping MMP-2 peptides pulsed with irradiated autologous CD4- fraction. After 12 days, MMP-2-specific responses were determined by intracellular staining for cytokines. Specific T cells from positive samples were enriched, using the IFNγ-capture assay (Miltenyi), followed by cloning using limiting dilution. Cytokine production was assessed by ELISA, intracellular staining, or cytometric bead array method. Results: We identified 11 novel CD4 MMP-2-derived epitopes, and showed that the corresponding T cells displayed an inflammatory TH2 profile, i.e., mainly secreting TNF, IL-4 and IL-13 and expressing the TH2-specific transcription factor GATA-3. In contrast, CD4+ T cells that recognize other associated MAAs were typically TH1. MMP-2-specific responses were detected in the CD45RO+/CD62L- T cell memory fraction. Interestingly, naïve T cells primed with active MMP-2 gave rise to TH2 specific cells, while naïve T cells primed with peptides generated IFNγ-secreting specific cells, consistent with a TH1 profile. Accordingly, we showed that the enzymatic activity of MMP-2 inhibited IL-12 secretion by mature DCs, possibly explaining the TH2 skewing of MMP-2-specific T cells. Furthermore, MMP-2 specific TH2 cells were found in at least 18 tumor-infiltrating lymphocyte populations out of the 31 melanoma patients tested. Conclusions: The protease activity of MMP-2 blocks DC maturation, more precisely IL-12 production, which could be responsible for the observed TH2 lineage commitment of MMP-2-specific T cells. These findings open the way to therapeutic strategies skewing these already frequent and diverse MMP-2-specific responses towards a more efficient antitumor TH1 phenotype to treat melanoma patients.

No significant financial relationships to disclose.

A HLA-DQ5 restricted Melan-A/MART-1 epitope presented by melanoma tumor cells to CD4+ T lymphocytes

Melan-A/MART1 is a melanocytic differentiation antigen expressed by tumor cells of the majority of melanoma patients and, as such, is considered as a good target for melanoma immunotherapy. Nonetheless, the number of class I and II restricted Melan-A epitopes identified so far remains limited. Here we describe a new Melan-A/MART-1 epitope recognized in the context of HLA-DQa1*0101 and HLA-DQb1*0501, -DQb1*0502 or -DQb1*0504 molecules by a CD4+ T cell clone. This clone was obtained by in vitro stimulation of PBMC from a healthy donor by the Melan-A51-73 peptide previously reported to contain a HLA-DR4 epitope. The Melan-A51-73 peptide, therefore contains both HLA-DR4 and HLA-DQ5 restricted epitope. We further show that Melan-A51-63 is the minimal peptide optimally recognized by the HLA-DQ5 restricted CD4+ clone. Importantly, this clone specifically recognizes and kills tumor cell lines expressing Melan-A and either HLA-DQb1*0501, -DQb1*0504 or -DQb1*0502 molecules. Moreover, we could detect CD4+ T cells secreting IFN-gamma in response to Melan-A51-63 and Melan-A51-73 peptides among tumor infiltrating and blood lymphocytes from HLA-DQ5+ patients. This suggests that spontaneous CD4+ T cell responses against this HLA-DQ5 epitope occur in vivo. Together these data significantly increase the fraction of melanoma patients susceptible to benefit from a Melan-A class II restricted vaccine approach.

Pathogenetic mechanisms of vitiligo in a patient with Sézary syndrome

Patients exhibiting association between vitiligo and cutaneous T-cell lymphoma (CTCL) remain rare and it is not known whether some T-cell subpopulations of CTCL in the skin are able to recognize specific melanocytic epitopes and thus induce vitiligo. The aim of our study was to determine whether T cells specific to melanocyte differentiation antigens were detectable among tumour-infiltrating lymphocytes (TIL) in the hypopigmented skin of a patient with Sézary syndrome (SS). A 71-year-old patient presented with SS and developed vitiligo during the course of her disease. Immunohistochemical studies showed staining with HMB45 and MelanA antibodies in the pigmented skin biopsy, whereas no staining was observed in the hypopigmented skin biopsy. To analyse responses to melanocyte differentiation antigens, we used a transient COS transfection assay that permits an estimation of CD8 T-cell responses against a large number of HLA/antigen combinations. This technique allowed the detection of melanocyte differentiation antigen-specific T lymphocytes, directed mainly against Melan-A/MART1 antigen in the HLA-A*23 context. Our study supports the concept that vitiligo that has developed during the evolution of a CTCL is related to the presence of a T-lymphocyte subpopulation reactive against melanocyte differentiation antigens (mainly Melan-A/MART1) present in skin lesions. The role of interferon in the induction of this T-lymphocyte subpopulation is discussed.

Adoptive transfer of tumor-reactive Melan-A-specific CTL clones in melanoma patients is followed by increased frequencies of additional Melan-A-specific T cells

In this study, we report the adoptive transfer of highly tumor-reactive Melan-A-specific T cell clones to patients with metastatic melanoma, and the follow-up of these injected cells. These clones were generated from HLA-A*0201 patients by in vitro stimulations of total PBMC with the HLA-A*0201-binding Melan-A peptide analog ELAGIGILTV. Ten stage IV melanoma patients were treated by infusion of these CTL clones with IL-2 and IFN-alpha. The generated T cell clones, of effector/memory phenotype were selected on the basis of their ability to produce IL-2 in response to HLA-A*0201 Melan-A-positive melanoma lines. Infused clones were detected, by quantitative PCR, in the blood of three patients for periods ranging from 7 to 60 days. Six patients showed regression of individual metastases or disease stabilization, and one patient experienced a complete response, but no correlation was found between the detection of the infused clones in PBMC or tumor samples and clinical responses. Nonetheless, frequencies of Melan-A/A2-specific lymphocytes, measured by tetramer labeling, increased after treatment in most patients. In one of these patients, who showed a complete response, this increase corresponded to the expansion of new clonotypes of higher avidity than those detected before treatment. Together, our results suggest that infused CTL clones may have initiated an antitumor response that may have resulted in the expansion of a Melan-A-specific CTL repertoire.

CD8+ T lymphocytes reactive against Epstein-Barr virus antigens in skin lesions of a patient with Sézary syndrome

Several studies have investigated the possible involvement of viral agents, and among them herpes viruses, in the development of cutaneous T-cell lymphoma. The aim of our study was to determine whether T cells specific to Epstein-Barr virus (EBV) antigens were detectable among tumor-infiltrating lymphocytes infiltrating cutaneous lesions of a patient with Sézary syndrome. To analyze responses to EBV, we used a transient SV-40 origin-defective transformed simian cells transfection assay that permits an estimation of CD8 T-cell responses against a large number of HLA/viral protein combinations. This technique allowed the detection of EBV-specific T lymphocytes mainly directed against epitopes generated during the lytic cycle in the cutaneous lesions. This is, to our knowledge, the first description of the presence of EBV-specific T lymphocytes among tumor-infiltrating lymphocytes infiltrating the lesional skin of a patient with Sézary syndrome.

alpha v beta3-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.

A ras-mutated peptide targeted by CTL infiltrating a human melanoma lesion

Ags derived from commonly mutated oncogenic proteins seem ideally suited as targets for tumor immunotherapy. Nonetheless, only a few mutated epitopes efficiently presented by human tumors have thus far been identified. We describe here an approach to identify such epitopes. This approach involves: 1) identifying tumors expressing a ras mutation and isolating the tumor-infiltrating lymphocytes (TIL); 2) transfecting COS cells to induce expression of unknown mutated peptides in the context of a patient's HLA class I molecules; and 3) screening epitope recognition by using TIL from the tumors expressing a ras mutation. By using this approach, there appeared to be a N-ras mutation (a glutamine-to-arginine exchange at residue 61 (Q61R)), detected in a melanoma lesion, which was recognized specifically by the autologous TIL in the HLA-A*0101 context. The ras peptide 55-64(Q61R) was the epitope of these TIL and was regularly presented by Q61R-mutated HLA-A*0101(+) melanoma cell lines. This peptide and its wild-type homolog (55-64(wt)) bound to HLA-A*0101 with similar affinities. However, only the mutated peptide could induce specific CTL expansion from PBL. All the CTL clones specific to the mutated peptide, failed to recognize the wild-type sequence on both COS and melanoma cells. These data thus show that oncogenic protein mutations can create shared tumor-specific CTL epitopes, efficiently presented by tumor cells, and that screening for oncogene-transfected COS cell recognition by TIL (from tumors containing mutations) is a powerful approach for the identification of these epitopes.

Optimal induction of effector but not memory antitumor cytotoxic T lymphocytes involves direct antigen presentation by the tumor cells

MHC class I-restricted tumor antigen can be presented to CD8+ T cells by two distinct mechanisms. Direct presentation involves degradation of cytosolic proteins by the proteosome into peptides, transport of the peptides across the endoplasmic reticulum membrane, and expression of the MHC-peptide complex on the tumor cell surface. Cross-presentation, on the other hand, involves uptake and intracellular processing of the tumor antigen by host antigen-presenting cells. Whereas it is clear that cross-presentation is necessary and sufficient for the induction of memory CTLs, it has not been tested whether such presentation is sufficient to induce effector CTLs. Here we analyzed the requirements of direct antigen presentation for the induction of effector and memory antitumor CTLs using a MHC class I- mutant incapable of direct antigen presentation and its parent, the MHC class I+ J558 cell line. We report that in comparison with the MHC class I+ tumor cell, the MHC class I- mutant induces equal priming for recall CTL response but poor effector CTLs. Our results demonstrate that optimal induction of effector CTLs, but not memory CTLs, requires direct antigen presentation by the tumor cells.

High avidity melanoma-reactive cytotoxic T lymphocytes are efficiently induced from peripheral blood lymphocytes on stimulation by peptide-pulsed melanoma cells

To design an efficient procedure to expand high avidity melanoma reactive T cells and to perform immunotherapies, we compared conditions of peripheral blood lymphocyte (PBL) stimulation by Melan-A/MART-1 peptides. Avidity of induced CTLs was evaluated by measuring their lysis and cytokine secretion to peptide-pulsed transporter-associated protein-deficient cells and to melanoma cells. In side-by-side experiments, we show that melanoma cells, either allogeneic or autologous, induced the growth of high avidity Melan-A-reactive CTLs from all donors, whereas essentially low avidity T cells were induced by peptide-pulsed PBLs. We also show that at least two cytokines, interleukin-6 and interleukin-2, were required to promote the growth of high avidity CTLs. Once sorted by tetramer labeling or cloning, the specificity and reactivity to tumor cells of peptide-specific T cells induced by allogeneic melanoma cells were confirmed. We then describe a relatively simple and efficient procedure that allowed us to obtain systematically high amounts (in the range of billion) of high avidity Melan-A/ MART-1-specific T cells from the PBLs of HLA-A2 melanoma patients and healthy donors in 3 months. Because this antigen is expressed by most melanoma tumors, this procedure should be useful for checking the efficiency of adoptive immunotherapy of melanoma tumors and using functionally well-defined Melan-A/MART-1-specific CTLs in a large group of patients.

Cytotoxic T lymphocytes to an unmutated tumor rejection antigen P1A: normal development but restrained effector function in vivo

Unmutated tumor antigens are chosen as primary candidates for tumor vaccine because of their expression on multiple lineages of tumors. A critical issue is whether unmutated tumor antigens are expressed in normal cells, and if so, whether such expression imposes special restrictions on cytotoxic T lymphocyte (CTL) responses. In this study, we use a transgenic approach to study the development and effector function of T cells specific for P1A, a prototypical unmutated tumor antigen. We report here that although P1A is expressed at low levels in normal tissues, including lymphoid tissues, the P1A-specific transgenic T cells develop normally and remain highly responsive to the P1A antigen. The fact that transgenic expression of P1A antigen in the thymus induces T cell clonal deletion demonstrates that normal hematopoietic cells can process and present the P1A antigen and that P1A-specific T cells are susceptible to clonal deletion. By inference, P1A-specific T cells must have escaped clonal deletion due to low expression of P1A in the thymus. Interestingly, despite the fact that an overwhelming majority of T cells in the T cell receptor for antigen (TCR)-transgenic mice are specific for P1A, these mice are no more resistant to a P1A-expressing plasmocytoma than nontransgenic littermates. Moreover, when the same TCR-transgenic mice were challenged simultaneously with B7-1(+) and B7-1(-) tumors, only B7-1(+) tumors were rejected. Therefore, even though P1A can be a tumor rejection antigen, the effector function of P1A-specific CTL is restrained in vivo. These results have important implications for the strategy of tumor immunotherapy.

In vitro induction of specific cytotoxic T lymphocytes using recombinant single-chain MHC class I/peptide complexes

We have previously described the production and purification of a murine single-chain, soluble recombinant major histocompatibility complex (MHC) class I molecule (SC-Kd). A similar strategy was devised to produce a recombinant HLA-A2.1 (SC-A2) molecule. The latter was composed of the first three domains of the HLA-A2.1 heavy chain connected to human beta 2-microglobulin through a spacer of 15 amino acids. Immunoaffinity-purified SC-A2 molecules-were correctly folded and biologically functional. They specifically bound HLA-A2-restricted peptides and induced a peptide-specific cytotoxic T lymphocyte (CTL) clone to proliferate and secrete interleukin-2. The ability of murine and human SC-MHC molecules to elicit primary CTLs in vitro was next investigated. When coated in high density onto beads, complexes of antigenic peptide and SC-Kd or SC-A2 molecules efficiently induced a specific primary CTL response in vitro. Furthermore, the structural features of these CTLs were characterized by T cell receptor-beta chain analysis, which revealed rearrangements very similar, if not identical, to those found in CTLs generated by in vivo immunization. Such single-chain, soluble recombinant MHC class I molecules should provide a useful tool in particular for peptide binding assays and for in vitro primary CTL induction to identify immunogenic peptides such as those derived from known tumor-associated antigens.

Optimal T cell activation by melanoma cells depends on a minimal level of antigen transcription

We reported previously that a large fraction of melanoma cell lines induced a suboptimal activation of specific CTL clones, characterized by good tumor cell lysis but no detectable IL-2 production. Using synthetic peptides, we demonstrated recently that this was due to expression of subthreshold levels of appropriate MHC-peptide complexes. We measure here by semiquantitative reverse transcription-PCR the expression of two melanoma Ag (NA17-A and Melan-A/MART-1) mRNAs in 13 melanoma cell lines and analyze the responses to these cell lines of specific HLA-A2-restricted CTL clones. In line with the idea that the density of MHC-antigenic peptide complexes on melanoma cells is a direct function of the Ag's mRNA level, we found that CTL lysis was grossly proportional to this level. We also established that a minimal level of transcription is required for melanoma cells to induce IL-2 secretion. Interestingly, all cell lines that expressed the Ag above this minimal level, either spontaneously or after gene transfection, stimulated the secretion by tumor-infiltrating lymphocyte of IL-2 amounts proportional to Ag expression unless they exhibited a defective expression of intracellular adhesion molecule-1 or LFA-3 molecules or a low expression of the restricting HLA element. These results indicate that optimal activation and therefore, doubtless, full functionality of melanoma-specific CTL clones critically depend on the mRNA level of the Ag in tumor cells and also on a minimal expression of the HLA restriction element, intracellular adhesion molecule-1, and LFA-3. These data provide a rationale for a better selection of patients to be included in Ag-specific immunization protocols.

Optimal T cell activation by melanoma cells depends on a minimal level of antigen transcription

We reported previously that a large fraction of melanoma cell lines induced a suboptimal activation of specific CTL clones, characterized by good tumor cell lysis but no detectable IL-2 production. Using synthetic peptides, we demonstrated recently that this was due to expression of subthreshold levels of appropriate MHC-peptide complexes. We measure here by semiquantitative reverse transcription-PCR the expression of two melanoma Ag (NA17-A and Melan-A/MART-1) mRNAs in 13 melanoma cell lines and analyze the responses to these cell lines of specific HLA-A2-restricted CTL clones. In line with the idea that the density of MHC-antigenic peptide complexes on melanoma cells is a direct function of the Ag's mRNA level, we found that CTL lysis was grossly proportional to this level. We also established that a minimal level of transcription is required for melanoma cells to induce IL-2 secretion. Interestingly, all cell lines that expressed the Ag above this minimal level, either spontaneously or after gene transfection, stimulated the secretion by tumor-infiltrating lymphocyte of IL-2 amounts proportional to Ag expression unless they exhibited a defective expression of intracellular adhesion molecule-1 or LFA-3 molecules or a low expression of the restricting HLA element. These results indicate that optimal activation and therefore, doubtless, full functionality of melanoma-specific CTL clones critically depend on the mRNA level of the Ag in tumor cells and also on a minimal expression of the HLA restriction element, intracellular adhesion molecule-1, and LFA-3. These data provide a rationale for a better selection of patients to be included in Ag-specific immunization protocols.

Suboptimal activation of melanoma infiltrating lymphocytes (TIL) due to low avidity of TCR/MHC-tumor peptide interactions

Coculture of melanoma cells and T cell clones derived from tumor-infiltrating lymphocytes (TIL) generally results in lysis of the antigen-bearing tumor cells but to inefficient proliferation and IL-2 secretion by responder T cells. This suboptimal activation is classically explained by an inability of tumor cells to provide costimulatory signals. Here we analyzed the responses to synthetic peptides of HLA-A2.1-restricted CTL clones specific for melanoma antigens MART-1 and NA17-A. We showed that peptide concentrations ranging from 1 pM to 10 nM efficiently sensitized the peptide transporter-deficient T2 cells to lysis. T2 cells pulsed with melanoma peptides also induced TIL proliferation and detectable secretion of IL-2, IFN-gamma and GM-CSF, but only for peptide concentrations 10- to 10,000-fold higher than those required for lysis. Hence this suggests that partial triggering of TIL clones by melanoma cells could be due to expression of appropriate MHC-peptide complexes at subthreshold levels. In support of this, we showed that melanoma cells, unable to trigger IL-2 secretion, developed this ability when incubated with the appropriate peptide. These results indicate that the level of antigens expressed on melanoma tumors critically affects TIL activation status and thus, the efficiency of specific immune reactions mediated by these cells.

A peptide recognized by human cytolytic T lymphocytes on HLA-A2 melanomas is encoded by an intron sequence of the N-acetylglucosaminyltransferase V gene

A cytolytic T lymphocyte (CTL) clone that lyses many HLA-A2 melanomas was derived from a population of tumor-infiltrating lymphocytes of an HLA-A2 melanoma patient. The gene coding for the antigen recognized by this CTL was identified by transfection of a cDNA library. It is the gene which has been reported to code for N-acetylglucosaminyltransferase V (GnT-V). Remarkably, the antigenic peptide recognized by the CTL is encoded by a sequence located in an intron. In contrast to the fully spliced GnT-V mRNA, which was found in a wide range of normal and tumoral tissues, the mRNA containing the intron region coding for the antigen was not found at a significant level in normal tissues. This mRNA was observed to be present in about 50% of melanomas. Our results suggest that a promoter located near the end of the relevant intron is activated in melanoma cells, resulting in the production of an mRNA coding for the antigen.

T cell activation by antigens on human melanoma cells--co-stimulation by B7-1 is neither sufficient nor necessary to stimulate IL-2 secretion by melanoma-specific T cell clones in vitro

B7-1 expression, induced by transfection in poorly immunogenic murine tumours, was shown to elicit a T cell-mediated rejection of these tumours and further active immunity against the non-transfected tumour. We therefore asked to what level similarly induced expression of B7 on human melanoma cells would affect the antigen-dependent responses of tumour-specific T cell clones in vitro. Data presented show that B7-1 expression by melanoma lines: (i) significantly induced, or improved, an IL-2-dependent proliferative response of such clones to the antigen; (ii) increased the amount of IL-2 produced by two clones in response to the parental non-transfected tumour cells; and (iii) increased the TNF responses of all the CD4+ clones. However, despite these clear co-stimulatory effects on antigen-induced responses of all T cell clones, which demonstrated an effective interaction of the B7-1 transfected molecule with one or the other of its counter-receptors expressed on T cell clones, B7 co-stimulation did not correct the defect of IL-2 secretion exhibited by many of these clones in response to in vitro antigen presentation by melanoma cells. We further show that defective IL-2 secretion in response to melanoma antigens was not due to a T cell clone refractoriness induced by the culture, since one of these clones could be induced to secrete IL-2 by an antigen-expressing melanoma line, upon increased lymphocyte function associated antigen-3 expression induced by gene transfection. Together these data suggest that defective IL-2 secretion by many tumour-infiltrating lymphocytes clones in response to antigen presentation by melanoma cells in vitro is not exclusively due to the inability of these cells to provide an appropriate co-stimulation through the B7-1 molecule.

Defective lymphokine production by most CD8+ and CD4+ tumor-specific T cell clones derived from human melanoma-infiltrating lymphocytes in response to autologous tumor cells in vitro

Human melanomas are infiltrated by tumor-reactive T lymphocytes. However, the ability of these cells to elicit a specific anti-tumor response in vivo remains to be established. Because lymphokine production is critical for T cell functions, we have analyzed the capacity of melanoma-specific tumor-infiltrating lymphocyte (TIL) clones to produce major lymphokines: interleukin-2 (IL-2), interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), as well as tumor necrosis factor (TNF), in response to direct antigen presentation by autologous and allogeneic tumor cells. We report here that, upon stimulation by autologous melanoma cells, all TIL clones secreted TNF but only a few of them produced significant amounts of IL-2, IL-4 or IFN-gamma. Nonetheless, all these clones consistently produced two or three of these last lymphokines upon stimulation with phorbol myristate acetate and calcium ionophore, as well as IL-2 upon CD3 stimulation, showing the existence of three lymphokine profiles among them: Th1, Th0 and a profile characterized by IL-2 and IL-4, but not IFN-gamma secretion. Stimulation of TIL clones by allogeneic melanoma lines sharing the appropriate HLA-peptide complexes revealed that defective IL-2 production seemed to be a constant feature for some clones, while it was, for other clones, dependent on the antigen-presenting tumor cells. For this last type of clone, we further showed that defective IL-2 induction resulted from an LFA-3 defect of some melanoma cells or from distinct yet undefined defects of other melanoma lines. Our data suggest that defective lymphokine secretion may be an essential component of the in vivo failure of melanoma-reactive TIL to control tumor development. Interestingly both CD4+ and CD8+ TIL clones from one patient were fully activated by the autologous melanoma cells in vitro, supporting a potential role of such TIL in spontaneous or induced tumor rejection.

Recognition of shared melanoma antigen by HLA-A2-restricted cytolytic T cell clones derived from human tumor-infiltrating lymphocytes

Three melanoma-specific cytotoxic T lymphocytes (CTL) clones were derived from the tumor-infiltrating lymphocyte (TIL) of human melanoma M17, and were used to study the expression of immunogenic melanoma peptides on allogeneic tumors. Antibody inhibition studies showed that two of these TIL clones were restricted by an HLA-A2 molecule which was identified as A2.1 by gene sequencing. The third CTL clone was not restricted by HLA-A2, but by a B or C HLA antigen. HLA-A2-restricted CTL clones M17-1 and M17-2 lysed 5 and 12 out of 15 HLA-A2+ allogeneic melanomas, respectively. Since they did not lyse autologous Epstein-Barr virus B cells, HLA-A2.1-transfected P815 cells, 13 HLA-A2+ non-melanoma tumor cell lines and 10 HLA-A2- melanomas, these clones appeared specific for melanoma-restricted epitopes presented by the HLA-A2.1 molecule. We then tried to determine why a few HLA-A2+ melanomas were refractory to TIL lysis. By using a combination of flow cytometry analysis, partial cloning and sequencing of their HLA-A2 genes, we show that failure to lyse did not result from low expression or polymorphism of the HLA-A2 molecule, or from deficient expression of the adhesion molecules ICAM-1 and LFA-3 by these melanomas. Taken together, our data confirm at the clonal level the existence of shared melanoma antigens recognized by TIL in the HLA-A2.1 context. They further show that individual peptides derived from these antigens are expressed by a large majority of HLA-A2+ melanomas. Identification of such peptides appears crucial for the future of vaccination therapies.

Specificity, T cell receptor diversity and activation requirements of CD4+ and CD8+ clones derived from human melanoma-infiltrating lymphocytes

To try to understand the functional significance of human melanoma-infiltrating lymphocytes (TIL), a clonal analysis of the specificity, T cell receptor (TcR) diversity and activation requirements of these lymphocytes isolated from four different tumors was carried out. Supporting the presence of in vivo primed tumor-specific T lymphocytes in these four tumors, a high frequency of the Cd8+ and CD4+ clones, obtained from the TIL cultured for a few days with recombinant interleukin (rIL)-2 and autologous tumor cells, exhibited a restricted lysis or proliferation in response to the autologous tumor cell line. In contrast, no tumor-specific clone was obtained from freshly extracted TIL, suggesting that the frequency of tumor-specific effectors remained low in these tumors. Only the CD8+ clones lysed the autologous tumor cells and their activity was major histocompatibility complex MHC class I restricted. Significant expansion of CD4+ and CD8+ tumor-specific clones required regular restimulation by autologous melanoma cells but also the addition of exogenous IL-2 and of Epstein-Barr virus-transformed B feeder cells. Five different tumor-specific clones, three CD8+ and two CD4+ clones were identified in a single tumor on the basis of their TcR gene configuration. Together, these data suggest that a spontaneous and diverse immune response, mediated by tumor-specific CD4+ as well as CD8+ T lymphocytes, arises in most MHC-bearing human melanomas but that antigen-MHC complex presentation by tumor cells does not, at least in vitro, allow a significant proliferation of these lymphocytes.