krn-7000 and Hepatitis--Autoimmune

Signal-transducing adaptor protein (STAP) family members function as adaptor molecules and are involved in several events during immune responses. Notably however, the biological functions of STAP-1 in other cells are not known. We aimed to investigate the functions of STAP-1 in invariant natural killer T (iNKT) cells and iNKT cell-dependent hepatitis.. We employed concanavalin A (Con A)-induced hepatitis and α-galactosylceramide (α-GalCer)-induced hepatitis mouse models, both are models of iNKT cell-dependent autoimmune hepatitis, and STAP-1 overexpressing 2E10 cells to investigate the role of STAP-1 in iNKT cell activation in vivo an in vitro, respectively.. After Con A- or α-GalCer-injection, hepatocyte necrotic areas and plasma alanine aminotransferase elevation were more severe in STAP-1 knockout (S1KO) mice and milder in lymphocyte-specific STAP-1 transgenic (S1Tg) mice, as compared to wild-type (WT) mice. Two events that may be related to Con A-induced and/or α-GalCer-induced hepatitis were influenced by STAP-1 manipulation. One is that iNKT cell populations in the livers and spleens were increased in S1KO mice and were decreased in S1Tg mice. The other is that Con A-induced interleukin-4 and interferon-γ production was attenuated by STAP-1 overexpression. These effects of STAP-1 were confirmed using 2E10 cells overexpressing STAP-1 that showed impairment of interleukin-4 and interferon-γ production as well as phosphorylation of Akt and mitogen-activated protein kinases in response to Con A stimulation.. These results conclude that STAP-1 regulates iNKT cell maintenance/activation, and is involved in the pathogenesis of autoimmune hepatitis.

Topics: Adaptor Proteins, Signal Transducing; Animals; Concanavalin A; Cytokines; Down-Regulation; Galactosylceramides; Hepatitis, Autoimmune; Homeostasis; Mice, Inbred C57BL; Mice, Knockout; Natural Killer T-Cells

The immunobiology of FXR has attracted significant attention in immune regulation and innate immunity. We have studied the mechanism of action of FXR activation on two models of acute hepatitis, inflammation mediated by Con A and α-GalCer and focused on the interactions of FXR activation and expression of PIR-B, both in vivo and in vitro using luciferase reporter and CHIP assays. In addition, based upon our data, we studied the role of FXR activation on the immunobiology of myeloid-derived suppressor cells (MDSCs). Importantly, we report herein that FXR activation reduces the inflammatory insult induced by either α-GalCer or Con A; such treatment expands CD11b(+)Ly6C(+) MDSCs. The protective effect of FXR activation is dependent on expansion of MDSCs, particularly liver CD11b(+)Ly6C(high) cells. Indeed, FXR activation enhances the suppressor function of MDSCs through upregulation of PIR-B by binding the PIR-B promoter. FXR activation drives the accumulation of MDSCs to liver through upregulation of S100A8. FXR activation facilitates homing and function of MDSCs, which function as a critical negative feedback loop in immune-mediated liver injury. The novel mechanisms defined herein emphasize not only the importance of liver lymphoid subpopulations, but also the potential roles of modulating FXR in autoimmune liver disease.

Topics: Animals; Antigens, Ly; Calgranulin A; CD11b Antigen; Concanavalin A; Galactosylceramides; Hepatitis, Autoimmune; Liver; Mice; Mice, Transgenic; Mitogens; Myeloid Cells; Promoter Regions, Genetic; Receptors, Cytoplasmic and Nuclear; Receptors, Immunologic

Regulation and induction of anergy in NKT cells of the liver can inhibit autoimmune and antitumor responses by mechanisms that are poorly understood. We investigated the effects of PGE2, delivered by intestinal, mucus-derived, exosome-like nanoparticles (IDENs), on NKT cells in mice. In this study, we demonstrate that IDENs migrate to the liver where they induce NKT cell anergy. These effects were mediated by an IDENs' PGE2. Blocking PGE2 synthesis attenuated IDENs inhibition of induction of IFN-γ and IL-4 by α-galactosylceramide (α-GalCer)-stimulated liver NKT cells in a PGE2 E-type prostanoid 2/E-type prostanoid 4 receptor-mediated manner. Proinflammatory conditions enhanced the migration of IDENs to the liver where α-GalCer and PGE2 induced NKT anergy in response to subsequent α-GalCer stimulation. These findings demonstrate that IDENs carrying PGE2 can be transferred from the intestine to the liver, where they act as immune modulators, inducing an anergic-like state of NKT cells. These reagents might be developed as therapeutics for autoimmune liver diseases.

Topics: Animals; Cell-Derived Microparticles; Clonal Anergy; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Dinoprostone; Disease Models, Animal; Exosomes; Galactosylceramides; Hepatitis, Autoimmune; Humans; Intestinal Mucosa; Liver; Lymphocyte Activation; Male; Mice; Natural Killer T-Cells; Signal Transduction

As natural killer (NK) T cells play an important role in the development of autoimmune diseases, they should have significant roles for the pathogenesis of autoimmune liver disease. Implication of the NK T cells in the generation of autoimmune-related hepatic inflammation was investigated using a novel mouse model. Immunization of mice with dendritic cells (DCs) loaded with hepatocyte-mimicking hepatocellular carcinoma cells (DC/Hepa1-6) induces cytotoxic T lymphocytes (CTL) capable of killing hepatocytes. Subsequent administration of interleukin (IL)-12, a potent interferon-gamma (IFN-γ) inducer, to the immunized mice generates autoimmune hepatic inflammation (AHI), as reported previously. Upon onset of the AHI response, the number of intrahepatic CD3(+) NK1 · 1(+) NK T cells increased markedly, along with a decrease in the number of splenic NK T cells, augmented expression of CXCR6 on intrahepatic NK T cells and CXCL16 in hepatic tissue, suggesting that NK T cells were recruited into the inflamed liver. The NK T cells were strongly positive for CD69 and produced IFN-γ, but not IL-4. AHI activity was attenuated markedly in CD1d(-/-) NK T cell-deficient mice, indicating that NK T cells play a pivotal role in the development of AHI. Mice treated with DC/Hepa1-6 and alpha-galactosylceramide, a potent NK T cell activator, also exhibited similar hepatic inflammation, in which activated NK T cells producing IFN-γ and CD8(+) T cells cytotoxic to hepatocytes were induced in liver-infiltrating mononuclear cells. Activated NK T cells producing IFN-γ potentiate DC-based AHI in the mouse model.

Topics: Animals; Antigens, CD1d; Cell Line; Cytotoxicity, Immunologic; Dendritic Cells; Female; Galactosylceramides; Hepatitis, Autoimmune; Interferon-gamma; Liver; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Knockout; Natural Killer T-Cells; T-Lymphocytes, Cytotoxic

V alpha14 invariant natural killer T cells (iNKT) are localized in peripheral tissues such as the liver rather than lymphoid tissues. Therefore, their role in modulating the stimulation of conventional, major histocompatibility complex (MHC)-restricted T-cell responses has remained ambiguous. We here describe a role for V alpha14 iNKT cells in modulating conventional T-cell responses to antigen expressed in liver, using transferrin-mOVA (Tf-mOVA) mice.. Naïve ovalbumin-specific class I MHC-restricted T cells (OTI) were adoptively transferred into Tf-mOVA mice in the presence or absence of iNKT-cell agonist alpha-galactosylceramide, after which OTI T-cell priming, antigen-specific cytokine production, cytotoxic killing ability, and liver damage were analyzed.. Transfer of OTI cells resulted in robust intrahepatic, antigen-specific proliferation of T cells. OTI T cells were activated in liver, and antigen-specific effector function was stimulated by coactivation of Valpha14 iNKT cells using alpha-galactosylceramide. This stimulation was absent in CD1d(-/-)Tf-mOVA mice, which lack V alpha14 iNKT cells, and was prevented when interferon-gamma and tumor necrosis factor-alpha production by V alpha14 iNKT cells was blocked.. CD1d-restricted V alpha14 iNKT cells stimulate intrahepatic CD8 T-cell effector responses to antigen expressed in liver. Our findings elucidate a previously unknown intervention point for targeted immunotherapy to autoimmune and possibly infectious liver diseases.

Topics: Adoptive Transfer; Animals; Antibodies; Antigens, CD1; Antigens, CD1d; CD8-Positive T-Lymphocytes; Cell Proliferation; Cells, Cultured; Cytotoxicity, Immunologic; Galactosylceramides; Hepatitis, Autoimmune; Homeodomain Proteins; Interferon-gamma; Killer Cells, Natural; Liver; Lymph Nodes; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Receptors, Antigen, T-Cell; Serpins; Transferrin; Tumor Necrosis Factor-alpha