ABSTRACT
We evaluated the role of the thymus in development of multi-organ autoimmunity in human immune system (HIS) mice. T cells were essential for disease development and the same T cell clones with varying phenotypes infiltrated multiple tissues. De novo-generated hematopoietic stem cell (HSC)-derived T cells were the major disease drivers, though thymocytes pre-existing in grafted human thymi contributed if not first depleted. HIS mice with a native mouse thymus developed disease earlier than thymectomized mice with a thymocyte-depleted human thymus graft. Defective structure in the native mouse thymus was associated with impaired negative selection of thymocytes expressing a transgenic TCR recognizing a self-antigen. Disease developed without direct recognition of antigens on recipient mouse MHC. While human thymus grafts had normal structure and negative selection, failure to tolerize human T cells recognizing mouse antigens presented on HLA molecules may explain eventual disease development. These new insights have implications for human autoimmunity and suggest methods of avoiding autoimmunity in next-generation HIS mice.
Subject(s)
Autoimmune Diseases/etiology , Autoimmune Diseases/metabolism , Autoimmunity , Disease Susceptibility/immunology , Thymus Gland/immunology , Thymus Gland/metabolism , Animals , Antigens , Autoimmune Diseases/pathology , Biomarkers , Clonal Selection, Antigen-Mediated/immunology , Disease Models, Animal , High-Throughput Nucleotide Sequencing , Humans , Immunohistochemistry , Immunophenotyping , Lymphopoiesis/genetics , Lymphopoiesis/immunology , Mice , Mice, Knockout , Mice, Transgenic , Organ Specificity/immunology , Receptors, Antigen, T-Cell/genetics , Receptors, Antigen, T-Cell/metabolism , Receptors, Antigen, T-Cell, alpha-beta/genetics , Receptors, Antigen, T-Cell, alpha-beta/metabolism , T-Lymphocytes/immunology , T-Lymphocytes/metabolismABSTRACT
We developed a rapid method to remove the native mouse thymus from NSG mice, which allowed us to compare the behavior of human immune cells in the presence or absence of human T cells in human immune system mice. Removing the native mouse thymus is critical for studies of human thymopiesis in grafted thymic tissue in humanized mice.
Subject(s)
Thymectomy/methods , Thymus Gland/immunology , Thymus Gland/transplantation , Transplantation, Heterologous/methods , Animals , Humans , Mice , Mice, Inbred NOD , Mice, SCIDABSTRACT
Gangliosides shed by tumors into their microenvironment (TME) are immunoinhibitory. Interferon-γ (IFN-γ) may boost antitumor immune responses. Thus we wondered whether IFN-γ would counteract tumor ganglioside-mediated immune suppression. To test this hypothesis, we exposed human monocyte-derived LPS-activated dendritic cells (DC) to IFN-γ and to a highly purified ganglioside, GD1a. DC ganglioside exposure decreased TLR-dependent p38 signaling, explaining the previously observed ganglioside-induced down-modulation of pro-inflammatory surface markers and cytokines. Strikingly, while increasing LPS-dependent DC responses, IFN-γ unexpectedly did not counteract the inhibitory effects of GD1a. Rather, induction of indoleamine 2,3-dioxygenase (IDO1), and expression of STAT1/IRF-1 and programmed cell death ligand (PD-L1), indicated that the immunoinhibitory, not an immune stimulatory, IFN-γ-signaling axis, was active. The combination, IFN-γ and DC ganglioside enrichment, markedly impaired DC stimulatory potential of CD8+ T-cells. We suggest that gangliosides and IFN-γ may act in concert as immunosuppressive mediators in the TME, possibly promoting tumor progression.