Authors: Florent Creusat, Siham Hedir, Alexis Gonon, Amélie Marguier, Yacine Cherifi, Fabiane Sonego, Gaëlle Martin, Kader Thiam
Published: 2025-04-21
DOI: 10.1158/1538-7445.am2025-5244
Source: Full article
Development of immunotherapies has been a major landmark in the field of oncology, leading to numerous effective treatments. From the first use of an immunomodulatory agent in clinical studies to modern immunotherapies, these were mainly focused on modulating adaptive immune response. However, only a fraction of patients can respond to these treatments, and the complexity of the tumor microenvironment requires other players to be targeted. γδ T cells are unconventional T cells, as they recognize antigens mostly in a MHC-unrestricted fashion. They show a high diversity of effector functions, from cytotoxicity to mediators’ production and wound healing. Their preactivated state allows a quick immune response, and their role in tumor development, both in beneficious or deleterious manner, was demonstrated in numerous types of cancer. Current therapeutic approaches involving γδ T cell include adoptive cell transfer, in vivo stimulation and combined therapies. While preliminary results are promising, investigation of such therapies in preclinical models is challenging, because γδ T cells are not developed at satisfactory levels in most of the humanized mouse models. Here we describe the presence and functionality of γδ T cell in BRGSF (Balb/C Rag2-/-, IL2Rγ-/-, SIRPαNOD and Flt3-/-), a highly immunodeficient mouse featuring reduced murine myeloid cells. BRGSF mice reconstituted with human cord blood CD34+ cells (BRGSF-HIS) develop functional lymphoid and myeloid compartments. This engraftment is stable for over a year (Labarthe et al., 2019) and mice do not develop GvHD. At steady-state, BRGSF-HIS mice show a diverse population of γδ T cells in their blood and peripheral organs, expressing Vδ1, Vδ2 or Vδ3 chains, although their ratio is different in blood from BRGSF-HIS mice and human PBMC. These cells can be expanded using zoledronate with human IL-2, allowing ex vivo or in vivo assays for γδ T cells targeting compounds. This specific activation, as well as the activation with a Vδ1-targeting agent, leads to an increase in γδ T cells activation state (expression of CD25, CD69, CD137) and their effector function (cytokine production or CD107a-associated degranulation). Similarly, an “Expander” targeting Vγ9 significantly increased Vγ9 expressing cells frequencies, and serum levels of perforin and INF-γ in treated mice. Interestingly, γδ T cells were recruited into the tumor microenvironment of the triple negative breast cancer line MDA-MB-231 and the colorectal adenocarcinoma cell lines HT29 and SW480, suggesting that therapies designed to expand and activate γδ T cells could be assessed in BRGSF-HIS tumor bearing mice. Therefore, the development of functional γδ T cells in BRGSF-HIS mice brings a new perspective on the assessment of therapies targeting this cell population in humanized mouse models.