Nanographene Oxide Attenuates Acute GVHD by Modulating Macrophage Polarization in a Xenogeneic Mouse Model

Nanographene oxide (NGO) exhibits immunomodulatory activity and holds promise as a therapeutic agent for graft-versus-host disease (GVHD). In a xenogeneic GVHD mouse model, NGO administration improves survival and attenuates pathology with reduced weight loss and leukocyte engraftment, without sustained systemic toxicity. In GVHD patient-derived peripheral blood mononuclear cells (PBMCs), NGO treatment shifts T cell subsets toward immune homeostasis by increasing naïve T cells and decreasing effector memory T cells. Integrated transcriptomic analyses of PBMCs from GVHD patients and healthy donors reveal downregulation of pro-inflammatory and interferon-gamma-signal transducer and activator of transcription 1 (IFN-γ-STAT1)-associated genes, coinciding with the suppression of M1 macrophage signatures and induction of anti-inflammatory profiles. Mechanistically, NGO inhibits STAT1 activation and biases macrophages toward an anti-inflammatory state, independent of reactive oxygen species scavenging and lipopolysaccharide-myeloid differentiation primary response 88 (LPS-MyD88) signaling. To improve translational feasibility, NGO-primed macrophages (NGO-Mac) are generated, which produce higher levels of interleukin-10 (IL-10), inhibit helper T cell 1 (Th1) differentiation, and promote regulatory T cell (Treg) induction in an IL-10-dependent manner. In vivo, NGO-Mac therapy reduces M1 macrophage infiltration, increases Treg frequencies, and attenuates GVHD pathology. These findings highlight NGO and NGO-Mac as complementary immunotherapies, while further studies on safety, biodistribution, and feasibility are necessary for translation.