Galectin-3 expression in donor T cells reduces GvHD severity and lethality after allogeneic hematopoietic cell transplantation

Abundant donor cytotoxic T cells that attack normal host organs remain a major problem for patients receiving allogeneic hematopoietic cell transplantation (Allo-HCT). Despite an increase in our knowledge of the pathobiology of acute graft versus host disease (aGvHD), the mechanisms regulating the proliferation and function of donor T cells remain unclear. Here, we show that activated donor T cells express galectin-3 (Gal-3) after allo-HCT. In both major and minor histocompatibility–mismatched models of murine aGvHD, expression of Gal-3 is associated with decreased T cell activation and suppression of the secretion of effector cytokines including IFN-γ and GM-CSF. Mechanistically, Gal-3 results in activation of NFAT signaling which can induce T cell exhaustion. Gal-3 overexpression in human T cells prevents severe disease by suppressing cytotoxic T cells in xenogeneic aGvHD models. Together these data identify the Gal-3-dependent regulatory pathway in donor T cells as a critical component of inflammation in aGvHD. At day 7 after allo-HCT, CD4+ or CD8+ T cells (live, H-2Kb+CD45+CD3+) were sorted from single-cell suspensions of spleens from BALB/c recipient mice for gene expression (Immunology Panel, Nanostring) using BD FACSAria (BD Bioscience) in the Roswell Park Flow and Image Cytometry Shared Resource. After sorting, the total T cells ranged from 0.5×106 to 1×106 cells. Cells were immediately frozen in liquid nitrogen and then stored at -80°C or on dry ice. Samples were sent to the Roswell Park Genomic Shared Resource for gene expression profiling. Nanostring analysis was performed with the nCounter® Analysis System from NanoString Technologies utilizing the nCounter Mouse Immunology Kit, which includes 561 immunology-related mouse genes according to manufacturer’s protocols.