Breast cancer is the most common cancer type in women and the leading cause of cancer-related death. The human epidermal growth factor receptor 2 (HER2) is a key marker of this disease, as it is overexpressed in 25% of the most aggressive breast cancers. Immunotherapy has significantly improved long-term remission rates and survival for many patients. However, resistance to immunotherapy is still a significant issue due to the ability of tumor cells to evade the immune system. One immunotherapeutic strategy that exploits the immune system’s ability to recognize antigens from genetically distinct individuals of the same species (allo-reactivity) is allogeneic transplantation, which has been historically exploited for leukemia treatment and, more recently, for the treatment of solid tumors. The main limitation of this approach is represented by Graft Versus Host Disease (GVHD), a systemic complication with potentially fatal outcomes. This study, conducted at the European Institute of Oncology, focused on the application of allo-reactivity against HER2+ breast cancer, using a unique murine model generated in the laboratory, named “AlloMHC,” which harbours an allogeneic H-2 locus (H-2b, derived from the C57Bl/6 strain) in a FVB genetic background. Preliminary results showed that ErbB2-induced FVB WT tumors, the orthologue of human HER2, are not transplantable in AlloMHC mice (and vice versa), and that MHC II+ cells in the AlloMHC tumor microenvironment are responsible for the lack of tumor growth. In fact, FVB WT CD4+ T cells, when activated by MHC II+ antigen-presenting cells (APCs) from AlloMHC, trigger an anti-tumor response without GVHD. The aim of my thesis project was to investigate, at an immunophenotypic and molecular level, the CD4+ T cells stimulated by AlloMHC APCs. The first goal of my study was to characterize the genetic polymorphisms (SNPs) of the MHC II of AlloMHC compared to FVB WT. I then studied the proliferation and differentiation of T cells stimulated by partially (AlloMHC) or fully (C57Bl/6) allogeneic APCs, highlighting, in vitro, a shift toward effector memory in C57Bl/6 stimulation and toward central memory in AlloMHC stimulation. Molecular analyses of the T cell receptor (TCR) showed greater diversity in the CD4+ T cell repertoire in the AlloMHC stimulation as compared to the C57Bl/6 stimulation. Finally, in vivo experiments confirmed the expansion and activation of CD4+ memory compartment T cells in FVB mice inoculated with ErbB2 AlloMHC tumor cells. In conclusion, I investigated the cellular mechanisms of the response of CD4+ T cells stimulated by APCs expressing an allogenic MHC II in an otherwise syngeneic context, suggesting that the AlloMHC model represents a promising approach for new immunotherapeutic strategies against breast cancer.
Il cancro al seno è la forma più comune di cancro nelle donne e la principale causa di morte per tumore. Il recettore del fattore di crescita epidermico umano, HER2, è un marcatore fondamentale in quanto è sovraespresso nel 25% dei tumori al seno maggiormente aggressivi. L’immunoterapia ha migliorato notevolmente i tassi di remissione a lungo termine e la sopravvivenza di molte pazienti. Tuttavia, la resistenza all’immunoterapia è ancora un limite, a causa della capacità delle cellule tumorali di eludere il sistema immunitario. Una strategia immunoterapica che sfrutta la capacità del sistema immunitario di riconoscere antigeni provenienti da individui geneticamente distinti della stessa specie (alloreattività) è il trapianto allogenico, storicamente usato per il trattamento delle leucemie e recentemente impiegato anche per il trattamento di tumori solidi. Il limite principale di questo approccio è la Graft Versus Host Disease (GVHD), una complicanza sistemica con esiti anche fatali. Il presente studio, condotto presso l’Istituto Europeo di Oncologia, si è concentrato sull’applicazione dell’alloreattività contro il tumore al seno HER2+, sfruttando un modello murino unico generato dal laboratorio stesso, detto “AlloMHC”, che presenta un locus H-2 allogenico (H-2b, derivato dal ceppo C57Bl/6) in un background genetico FVB. Risultati preliminari hanno mostrato che i tumori FVB WT indotti da ErbB2, ortologo di HER2 umano, non sono trapiantabili nei topi AlloMHC (e viceversa) e che le cellule MHC II+ del microambiente tumorale AlloMHC sono responsabili della mancata crescita tumorale. Le cellule T CD4+ FVB WT, infatti, se attivate dalle cellule presentanti l’antigene (APC) MHC II+ AlloMHC, innescano una risposta antitumorale senza causare GVHD. Lo scopo del mio progetto di tesi è stato indagare a livello immunofenotipico e molecolare le cellule T CD4+ stimolate dalle APC AlloMHC. Il primo obiettivo del mio studio è stato caratterizzare i polimorfismi genetici (SNP) dell’MHC II AlloMHC rispetto all’FVB WT. Successivamente, ho studiato la proliferazione e il differenziamento delle cellule T stimolate dalle APC parzialmente (AlloMHC) o completamente (C57Bl/6) allogeniche, evidenziando, in vitro, uno spostamento verso la memoria effettrice nella stimolazione con le C57Bl/6 e verso la memoria centrale con le AlloMHC. Le analisi molecolari condotte sul recettore delle cellule T (TCR), inoltre, hanno mostrato una maggiore diversità del repertorio delle cellule T CD4+ nella stimolazione AlloMHC rispetto alla stimolazione C57Bl/6. Con esperimenti in vivo, infine, ho confermato l’espansione e l’attivazione delle cellule T CD4+ del comparto della memoria nei topi FVB inoculati con cellule tumorali ErbB2 AlloMHC. In conclusione, con il mio lavoro ho indagato i meccanismi cellulari della risposta delle cellule T CD4+ stimolate da APC esprimenti un MHC II allogenico in un contesto altrimenti singenico, suggerendo come il modello AlloMHC rappresenti un promettente approccio per nuove strategie immunoterapiche contro il cancro al seno.
Studio di un nuovo approccio immunoterapico per il cancro alla mammella basato su cellule T stimolate con MHC allogenici
POLIMENO, ALICE
2023/2024
Abstract
Breast cancer is the most common cancer type in women and the leading cause of cancer-related death. The human epidermal growth factor receptor 2 (HER2) is a key marker of this disease, as it is overexpressed in 25% of the most aggressive breast cancers. Immunotherapy has significantly improved long-term remission rates and survival for many patients. However, resistance to immunotherapy is still a significant issue due to the ability of tumor cells to evade the immune system. One immunotherapeutic strategy that exploits the immune system’s ability to recognize antigens from genetically distinct individuals of the same species (allo-reactivity) is allogeneic transplantation, which has been historically exploited for leukemia treatment and, more recently, for the treatment of solid tumors. The main limitation of this approach is represented by Graft Versus Host Disease (GVHD), a systemic complication with potentially fatal outcomes. This study, conducted at the European Institute of Oncology, focused on the application of allo-reactivity against HER2+ breast cancer, using a unique murine model generated in the laboratory, named “AlloMHC,” which harbours an allogeneic H-2 locus (H-2b, derived from the C57Bl/6 strain) in a FVB genetic background. Preliminary results showed that ErbB2-induced FVB WT tumors, the orthologue of human HER2, are not transplantable in AlloMHC mice (and vice versa), and that MHC II+ cells in the AlloMHC tumor microenvironment are responsible for the lack of tumor growth. In fact, FVB WT CD4+ T cells, when activated by MHC II+ antigen-presenting cells (APCs) from AlloMHC, trigger an anti-tumor response without GVHD. The aim of my thesis project was to investigate, at an immunophenotypic and molecular level, the CD4+ T cells stimulated by AlloMHC APCs. The first goal of my study was to characterize the genetic polymorphisms (SNPs) of the MHC II of AlloMHC compared to FVB WT. I then studied the proliferation and differentiation of T cells stimulated by partially (AlloMHC) or fully (C57Bl/6) allogeneic APCs, highlighting, in vitro, a shift toward effector memory in C57Bl/6 stimulation and toward central memory in AlloMHC stimulation. Molecular analyses of the T cell receptor (TCR) showed greater diversity in the CD4+ T cell repertoire in the AlloMHC stimulation as compared to the C57Bl/6 stimulation. Finally, in vivo experiments confirmed the expansion and activation of CD4+ memory compartment T cells in FVB mice inoculated with ErbB2 AlloMHC tumor cells. In conclusion, I investigated the cellular mechanisms of the response of CD4+ T cells stimulated by APCs expressing an allogenic MHC II in an otherwise syngeneic context, suggesting that the AlloMHC model represents a promising approach for new immunotherapeutic strategies against breast cancer.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14239/28739