The Role of γδ T Cells as a Line of Defense in Viral Infections after Allogeneic Stem Cell Transplantation: Opportunities and Challenges

In the complex interplay between inflammation and graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-HSCT), viral reactivations are often observed and cause substantial morbidity and mortality. As toxicity after allo-HSCT within the context of viral reactivations is mainly driven by αβ T cells, we describe that by delaying αβ T cell reconstitution through defined transplantation techniques, we can harvest the full potential of early reconstituting γδ T cells to control viral reactivations. We summarize evidence of how the γδ T cell repertoire is shaped by CMV and EBV reactivations after allo-HSCT, and their potential role in controlling the most important, but not all, viral reactivations. As most γδ T cells recognize their targets in an MHC-independent manner, γδ T cells not only have the potential to control viral reactivations but also to impact the underlying hematological malignancies. We also highlight the recently re-discovered ability to recognize classical HLA-molecules through a γδ T cell receptor, which also surprisingly do not associate with GVHD. Finally, we discuss the therapeutic potential of γδ T cells and their receptors within and outside the context of allo-HSCT, as well as the opportunities and challenges for developers and for payers

Cellular immunotherapy on primary multiple myeloma expanded in a 3D bone marrow niche model

Bone marrow niches support multiple myeloma, providing signals and cell-cell interactions essential for disease progression. A 3D bone marrow niche model was developed, in which supportive multipotent mesenchymal stromal cells and their osteogenic derivatives were co-cultured with endothelial progenitor cells. These co-cultured cells formed networks within the 3D culture, facilitating the survival and proliferation of primary CD138+ myeloma cells for up to 28 days. During this culture, no genetic drift was observed within the genomic profile of the primary myeloma cells, indicating a stable outgrowth of the cultured CD138+ population. The 3D bone marrow niche model enabled testing of a novel class of engineered immune cells, so called TEGs (αβT cells engineered to express a defined γδTCR) on primary myeloma cells. TEGs were engineered and tested from both healthy donors and myeloma patients. The added TEGs were capable of migrating through the 3D culture, exerting a killing response towards the primary myeloma cells in 6 out of 8 donor samples after both 24 and 48 hours. Such a killing response was not observed when adding mock transduced T cells. No differences were observed comparing allogeneic and autologous therapy. The supporting stromal microenvironment was unaffected in all conditions after 48 hours. When adding TEG therapy, the 3D model surpassed 2D models in many aspects by enabling analyses of specific homing, and both on- and off-target effects, preparing the ground for the clinical testing of TEGs. The model allows studying novel immunotherapies, therapy resistance mechanisms and possible side-effects for this incurable disease

Cellular immunotherapy on primary multiple myeloma expanded in a 3D bone marrow niche model

Bone marrow niches support multiple myeloma, providing signals and cell-cell interactions essential for disease progression. A 3D bone marrow niche model was developed, in which supportive multipotent mesenchymal stromal cells and their osteogenic derivatives were co-cultured with endothelial progenitor cells. These co-cultured cells formed networks within the 3D culture, facilitating the survival and proliferation of primary CD138+ myeloma cells for up to 28 days. During this culture, no genetic drift was observed within the genomic profile of the primary myeloma cells, indicating a stable outgrowth of the cultured CD138+ population. The 3D bone marrow niche model enabled testing of a novel class of engineered immune cells, so called TEGs (αβT cells engineered to express a defined γδTCR) on primary myeloma cells. TEGs were engineered and tested from both healthy donors and myeloma patients. The added TEGs were capable of migrating through the 3D culture, exerting a killing response towards the primary myeloma cells in 6 out of 8 donor samples after both 24 and 48 hours. Such a killing response was not observed when adding mock transduced T cells. No differences were observed comparing allogeneic and autologous therapy. The supporting stromal microenvironment was unaffected in all conditions after 48 hours. When adding TEG therapy, the 3D model surpassed 2D models in many aspects by enabling analyses of specific homing, and both on- and off-target effects, preparing the ground for the clinical testing of TEGs. The model allows studying novel immunotherapies, therapy resistance mechanisms and possible side-effects for this incurable disease

RhoB Mediates Phosphoantigen Recognition by Vg9Vd2 T Cell Receptor

International audienceHighlights d Identification of SNPs near RhoB is associated with poor Vg9Vd2 T cell activation d RhoB activity and distribution in tumor cells modulate Vg9Vd2 T cell activation d Relocalization of RhoB induces membrane immobility of BTN3A1 d Tumor recognition by a Vg9Vd2 TCR depends on BTN3A1 conformation In Brief Sebestyen et al. show that Vg9Vd2TCR activation is modulated by the GTPase activity of RhoB in tumor cells, and by the relocalization of RhoB to BTN3A1. Subsequently, a phosphoantigen-induced conformational change in BTN3A1 leads to its recognition by Vg9Vd2TCRs

γ9δ2T cell diversity and the receptor interface with tumor cells

γ9δ2T cells play a major role in cancer immune surveillance, yet the clinical translation of their in vitro promise remains challenging. To address limitations of previous clinical attempts utilizing expanded γ9δ2T cells, we explored the clonal diversity of γ9δ2T cell repertoires and characterized their target. We demonstrated that only a fraction of expanded γ9δ2T cells is active against cancer cells, and that activity of the parental clone, or functional avidity of selected γ9δ2TCRs does not associate with clonal frequency. We also analyzed the target-receptor-interface and provided a two-receptor, three-ligand model. Activation is initiated by binding of the γ9δ2TCR to BTN2A1 through the regions between CDR2 and CDR3 of the TCR γ chain, and modulated by the affinity of the CDR3 region of the TCR δ chain, which is phosphoantigen (pAg)-independent and does not depend on CD277. CD277 is secondary, serving as mandatory co-activating ligand. Binding of CD277 to its putative ligand does not depend on the presence of γ9δ2TCR, does depend on usage of the intracellular CD277, creates pAg-dependent proximity to BTN2A1, enhances cell-cell conjugate formation and stabilizes the immunological synapse. This process critically depends on the affinity of the γ9δ2TCR and requires membrane flexibility of the γ9δ2TCR and CD277, facilitating their polarization and high-density recruitment during immunological synapse formation

γ9δ2T cell diversity and the receptor interface with tumor cells

International audienc

γ9δ2T cell diversity and the receptor interface with tumor cells

International audienc