T-cell tolerance is the central program that prevents harmful immune responses against self-antigens, in which inhibitory PD-1 signal given by B7-H1 interaction plays an important role. Recent studies demonstrated that B7-H1 binds CD80 besides PD-1, and B7-H1/CD80 interaction also delivers inhibitory signals in T cells. However, a role of B7-H1/CD80 signals in regulation of T-cell tolerance has yet to be explored. We report here that attenuation of B7-H1/CD80 signals by treatment with anti-B7-H1 monoclonal antibody, which specifically blocks B7-H1/CD80 but not B7-H1/PD-1, enhanced T-cell expansion and prevented T-cell anergy induction. In addition, B7-H1/CD80 blockade restored Ag responsiveness in the previously anergized T cells. Experiments using B7-H1 or CD80-deficient T cells indicated that an inhibitory signal through CD80, but not B7-H1, on T cells is responsible in part for these effects. Consistently, CD80 expression was detected on anergic T cells and further up-regulated when they were reexposed to the antigen (Ag). Finally, blockade of B7-H1/CD80 interaction prevented oral tolerance induction and restored T-cell responsiveness to Ag previously tolerized by oral administration. Taken together, our findings demonstrate that the B7-H1/CD80 pathway is a crucial regulator in the induction and maintenance of T-cell tolerance. (Blood. 2010;116(8): 1291-1298) Introduction B7-H1 (CD274, PD-L1), a transmembrane glycoprotein belonging to immunoglobulin (Ig) superfamily molecule, plays an integral role in the regulation of immune tolerance and homeostasis. 1 Mice deficient of B7-H1 gene or wild-type mice treated with anti-B7-H1 blocking monoclonal antibody (mAb) exhibit exacerbated autoimmune phenotypes associated with an activation of self-reactive CD4 ϩ and CD8 ϩ T cells. [2][3][4][5] Tolerogenic functions of B7-H1 are dependent on its expression on hematopoietic or parenchymal cells, and mediated by its interaction with PD-1 receptor. 6-8 PD-1 is inducibly expressed on T cells after activation and delivers coinhibitory signals via immunoreceptor tyrosine-based switch motif in the cytoplasmic domain. 9,10 PD-1 signal interferes with phosphatidylinositol-3-kinase (PI3K) activity and subsequently inhibits interleukin-2 (IL-2) production, which eventually renders T cells anergic. 11 The mice deficient of PD-1 gene spontaneously develop autoimmune phenotypes, and single nucleotide polymorphisms of human PD-1 gene are associated with an increased risk of autoimmune diseases. [12][13][14][15][16] Recent studies by Butte et al discovered that B7-H1 interacts with CD80 (B7-1) in addition to PD-1. 17,18 In vitro studies using CD4ϩ T cells deficient of PD-1, CD28, and/or CTLA-4 indicated that B7-H1/CD80 interaction delivers bidirectional inhibitory signals to T cells. 17 These findings are consistent with previous observations implicating the presence of non-PD-1 receptor(s) of B7-H1. For instance, when the B7-H1/PD-1 interaction is blocked in models of T-cell tolerance, the effects of anti-B7-H1 antagonistic mAb in rest...

Manganese cobalt oxides are promising coating materials for reducing chromium volatilization, and thus the associated cathode poisoning, from interconnect alloys in solid oxide fuel cells (SOFCs). Interaction between this coating and the oxide scale formed on the alloy during fuel cell operation can lead to changes in the coating composition and thus its performance. In this study, the properties of manganese cobalt spinel oxides and the reaction between manganese cobalt spinel oxides and chromia were investigated. The reaction product consists of two layers: a layer in contact with chromia that grows by the diffusion of cobalt and manganese from (Mn,Co) 3 O 4 toward the chromia and an intermediate layer that grows by the diffusion of chromium through the reaction layer. The effect of dopants on the coating performance was also investigated. With the addition of iron or titanium, the rate of reaction between the spinel coating and the chromia scale can be decreased significantly, which would reduce the risk of scale spallation and provide an increase in the lifetime of the interconnect and thus the fuel cell. II. Experimental ProcedureSpinel oxides were synthesized by solid state reaction of Co 3 O 4 (99.83%, Fisher, Pittsburgh, PA), MnO (99%, Alfa Aesar, Ward Hill, MA), Fe 3 O 4 (99.999%, Aesar), TiO 2 (99.17%, Fisher), and Cr 2 O 3 (99%, Acros, Geel, Belgium). The relevant oxide powders were carefully weighed to produce the appropriate stoichiometric mixtures for the spinels of interest. Weighed powders were pre-mixed by ball milling J. Stevenson-contributing editor Manuscript No. 29472.

B and T lymphocyte attenuator (BTLA) is a coinhibitory receptor that interacts with herpesvirus entry mediator (HVEM), and this interaction regulates pathogenesis in various immunologic diseases. In graftversus-host disease (GVHD), IntroductionActivation of T lymphocytes is regulated by 2 distinct signals: one is a primary signal delivered by T-cell receptor interaction with antigenic peptide/major histocompatibility complex (MHC), and the other is a cosignal delivered by interactions between cosignal receptors on T cells and their ligands on antigen-presenting cells. 1,2 Cosignaling receptors transmit stimulatory or inhibitory signals according to characteristics of their intracellular signaling motifs, and a balance of cosignals defines the fate of T-cell responses (ie, optimal activation or deactivation/tolerance induction). 3,4 Approaches to regulate cosignaling functions have been applied as novel and promising immunotherapies in various disorders, including cancer, infectious diseases, autoimmunity, organ transplantation, and graft-versus-host disease (GVHD).B and T lymphocyte attenuator (BTLA) is a cosignaling molecule that structurally belongs to the immunoglobulin (Ig) superfamily, expressed on broad ranges of immune cells, including T cells, B cells, and dendritic cells (DCs). [5][6][7] Intracellular domain of BTLA has 2 immunoreceptor tyrosine-based inhibition motifs, to which SH2 domain-containing protein tyrosine phosphatase-1 and tyrosine phosphatase-2 are recruited. 5,8,9 This signaling characteristic is consistent with its immune inhibitory functions, as BTLA gene-deficient mice exhibit an enhanced susceptibility to autoimmune diseases and increased inflammatory responses. 5,10-14 BTLA coinhibitory signal is induced by interaction with its endogenous ligand herpesvirus entry mediator (HVEM), a member of tumor necrosis factor-receptor superfamily. 8,15 In addition to BTLA, HVEM has 3 other binding partners, LIGHT (lymphotoxin-like, inducible expression, competes with herpes simplex virus glycoprotein D for HVEM, a receptor expressed by T lymphocytes), CD160 and lymphotoxin-␣. 16 LIGHT-HVEM interaction transmits HVEM-positive cosignal into T cells via activation of nuclear factor-B (NF-B) signaling pathway. [16][17][18] HVEM interactions with BTLA and LIGHT are dependent on distinct extracellular regions of HVEM (ie, cysteine-rich domain-1 for BTLA while opposing cysteine-rich domain-2 and -3 sites for LIGHT binding), and it has been suggested that ternary LIGHT-HVEM-BTLA complex either augments or disrupts HVEM-BTLA interactions according to soluble or membrane form of LIGHT. 19 In contrast to negative cosignaling functions of BTLA, recent studies also suggested prosurvival effects of BTLA. For instance, in nonirradiated parent-into-F1 GVHD model, transfer of BTLAknockout (KO) donor T cells resulted in significantly diminished donor-antihost responses because of an impaired donor T-cell survival. 20 In addition, intestinal inflammation induced by a transfer of BTLA-KO T cells into Rag-KO mice was ...

Toll-like receptors (TLR) are expressed by a variety of cancers, including melanoma, but their functional contributions in cancer cells are uncertain. To approach this question, we evaluated the effects of stimulating or inhibiting the TLR/IL-1 receptor-associated kinases IRAK-1 and IRAK-4 in melanoma cells where their functions are largely unexplored. TLRs and TLR-related proteins were variably expressed in melanoma cell lines, with 42% expressing activated phospho-IRAK-1 constitutively and 85% expressing high levels of phospho-IRAK-4 in the absence of TLR stimulation. Immunohistochemical evaluation of melanoma tumor biopsies (n=242) revealed two distinct patient populations, one which expressed p-IRAK-4 levels similar to normal skin (55%) and one with significantly higher levels than normal skin (45%). Levels of p-IRAK-4 levels did not correlate with clinical stage, gender or age, but attenuating IRAK-1,-4 signaling with pharmacological inhibitors or siRNA enhanced cell death in vitro in combination with vinblastine. Moreover, in a xenograft mouse model of melanoma, the combined pharmacological treatment delayed tumor growth and prolonged survival compared to subjects receiving single agent therapy. We propose p-IRAK-4 as a novel inflammation and pro-survival marker in melanoma with the potential to serve as a therapeutic target to enhance chemotherapeutic responses.