Host derived macrophage migration inhibitory factor expression attenuates anti-tumoral immune cell accumulation and promotes immunosuppression in the tumor microenvironment of head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is a significant public health concern worldwide. Immunomodulatory targets in the HNSCC tumor microenvironment are crucial to enhance the efficacy of HNSCC immunotherapy. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that has been linked to poor prognosis in many cancers, but the mechanistic role of MIF in HNSCC remains unclear. Using a murine orthotopic oral cancer model in Mif+/+ or Mif-/- mice, we determined the function of host derived MIF in HNSCC tumor development, metastasis as well as localized and systemic tumor immune responses. We observed that Mif-/- mice have decreased tumor growth and tumor burden compared to their wild-type counterparts. Flow cytometric analysis of immune populations within the primary tumor site revealed increased Th1 and cytotoxic T cell recruitment to the HNSCC tumor microenvironment. Within the tumors of Mif-/- mice, MIF deletion also enhanced the effector function of anti-tumoral effector CD8+ T cells as well as Th1 cells and decreased the accumulation of granulocytic myeloid derived suppressor cells (g-MDSCs) in the tumor microenvironment. Furthermore, MDSCs isolated from tumor bearing mice chemotactically respond to MIF in a dose dependent manner. Taken together, our results demonstrate a chemotactic and immunomodulatory role for host derived MIF in promoting HNSCC and suggest that MIF targeted immunomodulation is a promising approach for HNSCC treatment.

CRISPR/Cas9 deletion of MIR155HG in human T cells reduces incidence and severity of acute GVHD in a xenogeneic model.

ABSTRACT: Acute graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplantation (allo-HCT). Using preclinical mouse models of disease, previous work in our laboratory has linked microRNA-155 (miR-155) to the development of acute GVHD. Transplantation of donor T cells from miR-155 host gene (MIR155HG) knockout mice prevented acute GVHD in multiple murine models of disease while maintaining critical graft-versus-leukemia (GVL) response, necessary for relapse prevention. In this study, we used clustered, regularly interspaced, short palindromic repeats (CRISPR)/Cas9 genome editing to delete miR-155 in primary T cells (MIR155HGΔexon3) from human donors, resulting in stable and sustained reduction in expression of miR-155. Using the xenogeneic model of acute GVHD, we show that NOD/SCID/IL2rγnull (NSG) mice receiving MIR155HGΔexon3 human T cells provide protection from lethal acute GVHD compared with mice that received human T cells with intact miR-155. MIR155HGΔexon3 human T cells persist in the recipients displaying decreased proliferation potential, reduced pathogenic T helper-1 cell population, and infiltration into GVHD target organs, such as the liver and skin. Importantly, MIR155HGΔexon3 human T cells retain GVL response significantly improving survival in an in vivo model of xeno-GVL. Altogether, we show that CRISPR/Cas9-mediated deletion of MIR155HG in primary human donor T cells is an innovative approach to generate allogeneic donor T cells that provide protection from lethal GVHD while maintaining robust antileukemic response.