{
  "abstract": "Background Natural killer (NK) cells are key components of the innate immune system, and their high cytotoxicity has been associated to a more favorable prognosis in cancer. Therefore, strategies focusing on enhancing the effector function of NK cells are being investigated. Assessment of NK-targeting therapies in humanized mice is often challenging, as human NK cell levels are low, requiring supplementation with human IL-15 to enhance their development. Here we describe the recruitment of NK cells in the tumor microenvironment (TME) of A549 lung tumor model in genO-BRGSF-HIS mice (Balb/C Rag2 -/-, IL2Rγ-/-, SIRPαNOD and Flt3-/- immunodeficient mice reconstituted with human cord blood CD34+ cells), without the need of supplementation with human IL-15.Methods genO-BRGSF-HIS mice were engrafted with A549 cells and the immune cell infiltration into the TME was investigated by flow cytometry at three timepoints based on average tumor size: 200 mm 3, 400 mm3, and 800 mm3.Results Immune cells (human and mouse CD45 +) were 7-9% of the cells in the TME, with the frequency of human CD45+ cells ranging between 8% to 41% of the immune cells infiltrate overtime. Among human CD45+ cells, NK cells ranged from 30% to 37% overtime. NK cells recruited into the TME were identified as NK1, NK2 or NK3. While cytotoxic NK1 and chemokine-secreting NK2 populations decreased upon tumor growth, adaptive NK3 cells increased, suggesting that despite the low levels of circulating NK cells in naïve genO-BRGSF-HIS, NK cells developed and polarized in vivo without supplementation with human IL-15. Along with NK cells, T cells were also a major cell type recruited into the TME of A549 in genO-BRGSF-HIS mice, ranging from 21% to 36% among human CD45+ cells overtime. Interestingly, regulatory T cells (Treg) (CD4+FoxP3+CD127-) were approximately 10% of the T cells in the TME at termination (800 mm3). Based on the expression of GARP, Ki-67 and TIM-3 markers, approximately half of the Treg were identified as non-activated natural Treg (nTreg), while 25% as activated nTreg. A second subset was identified, 25% of CD4+CD25+FoxP3+cells, expressing CD127, CD30, CD39 and high levels of all activation markers, which could correspond to induced Tregs. Monocytes, neutrophils and dendritic cells also infiltrated the tumor.Conclusions These data show that NK cells respond to environmental stimulus and are recruited into the TME of A549 tumors in genO-BRGSF-HIS mice. The functionality of the different NK subpopulations remains to be investigated, however, if confirmed, genO-BRGSF-HIS could be a novel tool to assess NK-targeting immunotherapies.",
  "authors": [
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Siham Hedir"
    },
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Florent Creusat"
    },
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Amelie Marguier"
    },
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Yacine Cherifi"
    },
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Fabiane Sonego"
    },
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Gaelle Martin"
    },
    {
      "affiliations": [
        "GeOway, Lyon, France"
      ],
      "name": "Kader Thiam"
    }
  ],
  "title": "812 NK cell recruitment into A549 TME in genO-BRGSF-HIS mice",
  "uid": "4174e2bb-2dc6-5a30-ac12-b4c819b05fde"
}