ABSTRACT
IL-17-producing CD4+ T cells (Th17) play important functions in autoimmune diseases and allograft rejection of solid organs. We examined the effects of IL 17 and its mechanism of action on arthritis in a murine collagen-induced arthritis (CIA) model using bone marrow transplantation (BMT) system. DBA/1J mice were administered a lethal radiation dose and then rescued with bone marrow derived from either wild-type (WT) or IL-17-/- mice on C57BL/6 background mice. CIA was induced after the bone marrow transplant, and disease progression was characterized. DBA/1J mice with CIA that received IL-17-/- donor bone marrow showed potently inhibited development and severity of clinical arthritis as compared with CIA mice that received WT bone marrow. Reduced secretion of the pro-inflammatory cytokines tumor necrosis factor-alpha, IL-1beta, and IL-6, and collagen-specific T cell responses were observed in mice that received IL-17-/- bone marrow. IL-17 blockade also inhibited effector T cell proliferation by reciprocally regulating the Treg/Th17 ratio. IL-17 blockade prevented joint destruction in mice with CIA. These findings suggest that CIA with BMT is a viable method of immunological manipulation and that IL-17 deficiency suppresses severe joint destruction and inflammation in CIA mice. There may be clinical benefits in blocking IL-17 and BMT in the treatment of rheumatoid arthritis.
Subject(s)
Animals , Humans , Male , Mice , Antigens, Differentiation/metabolism , Arthritis, Experimental/pathology , Bone Marrow Transplantation , Cell Differentiation , Cell Proliferation , Cells, Cultured , Collagen Type II , Cytokines/metabolism , Interleukin-17/deficiency , Joints/pathology , Mice, Inbred C57BL , Mice, Inbred DBA , Mice, Knockout , Osteoclasts/metabolism , Signal Transduction , T-Lymphocytes/metabolism , Transplantation, HomologousABSTRACT
BACKGROUND/AIMS: The bone marrow functions not only as the primary B-lymphocyte-producing organ but also as a secondary lymphoid organ for CD4 and CD8 cell responses and a site of preferential homing and persistence for memory T cells. Bone marrow T (BM-T) cells are distinguished from peripheral blood T cells by surface phenotype, cytokine secretion profile, and immune functions. In this study, we evaluated the alloreactive potential of donor lymphocyte infusion (DLI) using BM-T cells in mixed chimerism compared to that using spleen T (SP-T) cells. METHODS: Cells were prepared using established procedures. BM-T cells were obtained as a by-product of T-cell depletion in BM grafting and then cryopreserved for subsequent DLI. We performed DLI using BM-T cells in allogeneic mixed chimera mice on post-BMT day 21. RESULTS: When the same dose of T cells, 5-10x10(5) (Thy1.2+), fractionated from BM and spleen were administered into mixed chimeras, the BM-T group showed complete chimeric conversion, with self-limited graft-versus-host disease (GVHD) and no pathological changes. However, the SP-T group showed persistent mixed chimerism, with pathological signs of GVHD in the liver and intestine. CONCLUSIONS: Our results suggest that DLI using BM-T cells, even in small numbers, is more potent at inducing chimeric conversion in mixed chimerism than DLI using SP-T cells. Further study is needed to determine whether cryopreserved BM-T cells are an effective cell source for DLI to consolidate donor-dominant chimerism in clinical practice without concerns about GVHD.
Subject(s)
Animals , Female , Mice , Bone Marrow Cells/physiology , Bone Marrow Transplantation , Graft vs Host Disease/prevention & control , Lymphocyte Transfusion , Mice, Inbred BALB C , Mice, Inbred C57BL , Spleen/cytology , T-Lymphocytes/physiology , Tissue Donors , Transplantation Chimera , Transplantation, HomologousABSTRACT
OBJECTIVE: Indoleamine 2, 3-dioxygenase (IDO), an immuno suppression enzyme, is one of the initial and rate-limiting enzymes involved in the catabolism of the essential amino acid tryptophan. IDO inhibits T cell proliferation, induces T cell apoptosis, and plays a fundamental role in autoimmunity and allergy. We investigated which subtype of dendritic cells (DCs) is involved in IDO expression and the generation of regulatory T cells during the induction of oral tolerance in type II collagen-induced arthritis (CIA). METHODS: Type II Collagen was fed to DBA/1J mice before immunization. Changes in DC subtypes and induction of regulatory T cell in orally tolerized CIA mice were analyzed. Whether the effect of DC subtype was modulated by the IDO expression, was determined by flow cytometry (FACs) and confocal microscopy. RESULTS: IDO expression of CD11c+ DCs was higher in orally tolerized CIA mice than in non-tolerized CIA mice. CD11b+ DCs of the CD11c +DCs, subtype was higher in the induction of in IDO expression. Our data suggest that these IDO expressing DCs of oral tolerized mice suppressed type II collagen-specific T cell proliferation and favored the differentiation of naive CD4+ T cells into regulatory T cells. Especially, CD11c+CD11b+ DCs expressed IDO, which is known to be associated with regulatory T cell induction. CONCLUSION: We observed that oral tolerance induced the increase in IDO-expressing CD11c+CD11b+ DCs, which appeared to induce regulatory T cells. IDO-expressing CD11c+CD11b+ DCs are involved in oral tolerance, which may provide a new therapeutic approach for the treatment of rheumatoid arthritis.