10 mice with VSIG4 WT or KO KCs in the presence of OVA323-339 for 2 days. DO11.10 T-cells produced more TNF-α and IFN-γ, and to a lesser extent, IL-4, when cocultured with VSIG4 KO KCs rather than with WT KCs (Fig. 4C,D). We investigated the potential role of VSIG4 in the induction of liver NKT-cell tolerance in vivo by using an α-GalCer-induced NKT-cell tolerance model in which NKT-cells acquire an anergic phenotype following in vivo stimulation with α-GalCer.17 Liver NKT-cells isolated from α-GalCer-tolerized WT mice did not produce IFN-γ and IL-4 in response to in vitro restimulation with

a low dose of α-GalCer this website (10 ng/mL), whereas liver NKT-cells from α-GalCer-tolerized VSIG4 KO mice produced higher levels of IFN-γ and IL-4 (P < 0.001; Fig. 5A). However, the cytokine levels of NKT-cells from α-GalCer-tolerized VSIG4 KO mice in response to in vitro α-GalCer restimulation were still lower than those from WT liver NKT-cells tolerized with vehicle alone (Fig. 5A, inset). Next, to examine the role of endogenous VSIG4 in the induction of liver T-cell tolerance, we used Y-27632 order orally tolerized mice with multiple low doses of soluble OVA protein (0.5 mg/mouse). Liver T-cells from orally tolerized WT mice did not produce detectable levels of IFN-γ and IL-2 in response to in vitro restimulation with OVA protein, whereas liver T-cells from orally tolerized VSIG4 KO mice

produced significant levels of IFN-γ and IL-2 even at a high concentration of OVA protein (IFN-γ, P < 0.001; IL-2, P < 0.001; Fig. 5B). To examine the in vivo tolerant state of liver NKT-cells, we stimulated liver MNCs containing NKT-cells and APCs with α-GalCer. VSIG4 KO liver MNCs produced more IFN-γ than WT counterparts (P < 0.001; Fig. 5C). The observation was not due to a difference between VSIG4 WT and KO mice in the frequencies of responding cells in liver MNCs, including NKT-cells, KCs, DCs, and Treg cells (Supporting Fig. 6A-C). Next, we purified Thy1.2+ liver T-cells using anti-CD90.2

microbeads and stimulated the cells with various concentrations of anti-CD3. The liver T-cells from VSIG4 KO mice produced more IFN-γ Lumacaftor mw and IL-2 than WT counterparts (at 1 μg/mL anti-CD3; IFN-γ, P < 0.001; IL-2, P < 0.01; Fig. 5D). Despite enhanced responsiveness of liver T- and NKT-cells from VSIG4 KO mice against cognate antigens, there was no significant difference between VSIG4 WT and KO mice in the frequencies of liver T- and NKT-cells with activated phenotypes, including CD44hi and CD62Llo (Supporting Fig. 6D). To examine the ability of VSIG4-expressing KCs to regulate T-cell proliferation, we cocultured DO11.10 T-cells with KCs from VSIG4 WT and KO mice in the presence of OVA peptide. A thymidine incorporation assay showed that VSIG4 WT KCs significantly inhibit DO11.10 T-cell proliferation compared to KO KCs (P < 0.01; Fig. 6A). VSIG4.