A CD300c-Fc Fusion Protein Inhibits T Cell Immunity

T cell responses are fine-tuned by co-stimulatory and co-inhibitory molecules. Among the T cell regulators, the B7 family members are of central importance. The recent success in targeting the B7 family molecules for the treatment of immune-related diseases has attracted intense interest in identifying additional B7-related molecules. In this study, we describe CD300c as a novel T cell co-inhibitory molecule that shares significant sequence homology with existing B7 family members. CD300c protein is expressed on professional antigen-presenting cells (APC), including B cells, monocytes, macrophages, and dendritic cells (DCs). The putative CD300c counter-receptor is expressed on CD4 and CD8 T cells, and the expression levels are upregulated upon activation. Soluble human and mouse CD300c-Fc fusion proteins significantly inhibit the proliferation, activation, and cytokine production by CD4 and CD8 T cells in vitro. Administration of CD300c-Fc protein attenuates graft-vs.-host disease (GVHD) in mice. Our results suggest that therapeutic interaction with the CD300c inhibitory pathway may represent a new strategy to modulate T cell-mediated immunity for the treatment of GVHD and autoimmune disease

Administration of Recombinant TAPBPL Protein Ameliorates Collagen-Induced Arthritis in Mice

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease distinguished by synovial hyperplasia and a progressive destruction of joints. T cells are critical players in the pathogenesis of RA. We have previously identified a novel immune checkpoint molecule, TAPBPL, that inhibits T cell functions in vitro. As a model for human RA, we investigated the ability of the TAPBPL protein to ameliorate collagen type II (CII)-induced arthritis (CIA) in mice that were injected with recombinant TAPBPL or a control protein. The mice were analyzed for CIA development, immune cells, and their responses. We found that TAPBPL protein significantly decreased CIA incidence and reduced clinical and pathological arthritis scores, which were related to a lower number of activated CD4 T cells but a greater number of regulatory T cells (Tregs) in the spleen, and a reduction of Th1/Th17 inflammatory cytokines in the joints and serum. Importantly, TAPBPL protein inhibited CII-specific T cell growth and Th1 and Th17 cytokine expression and reduced the production of CII autoantibodies in the serum. Our results suggest that TAPBPL protein can ameliorate CIA in mice and has the potential to be used in the treatment of patients with RA

Expression of canonical WNT/β-CATENIN signaling components in the developing human lung

<p>Abstract</p> <p>Background</p> <p>The WNT/β-CATENIN signaling cascade is crucial for the patterning of the early lung morphogenesis in mice, but its role in the developing human lung remains to be determined. In this study, expression patterns of canonical WNT/β-CATENIN signaling components, including WNT ligands (<it>WNT2</it>, <it>WNT7B</it>), receptors ( <it>FZD4</it>, <it>FZD7</it>, <it>LRP5</it>, <it>LRP6</it>), transducers ( <it>DVL2</it>, <it>DVL3</it>, <it>GSK-3β</it>, <it>β-CATENIN</it>, <it>APC</it>, <it>AXIN2</it>), transcription factors ( <it>TCF4</it>, <it>LEF1</it>) and antagonists ( <it>SOSTDC1</it>) were examined in human embryonic lung at 7, 12, 17 and 21 weeks of gestation (W) by real-time qRT-PCR and in situ hybridization.</p> <p>Results</p> <p>qRT-PCR analysis showed that some of these components were gradually upregulated, while some were significantly downregulated from the 7 W to the 12 W. However, most components reached a high level at 17 W, with a subsequent decrease at 21 W. In situ hybridization showed that the canonical WNT ligands and receptors were predominantly located in the peripheral epithelium, whereas the canonical WNT signal transducers and transcription factors were not only detected in the respiratory epithelium, but some were also scattered at low levels in the surrounding mesenchyme in the developing human lung. Furthermore, Western blot, qRT-PCR and histological analysis demonstrated that the β-CATENIN-dependent WNT signaling in embryonic human lung was activated in vitro by CHIR 99021 stimulation.</p> <p>Conclusions</p> <p>This study of the expression patterns and in vitro activity of the canonical WNT/β-CATENIN pathways suggests that these components play an essential role in regulation of human lung development.</p

Recombinant IL-7/HGFβ Hybrid Cytokine Enhances T Cell Recovery in Mice Following Allogeneic Bone Marrow Transplantation

<div><p>T cell immunodeficiency is a major complication of bone marrow (BM) transplantation (BMT). Therefore, approaches to enhance T cell reconstitution after BMT are required. We have purified a hybrid cytokine, consisting of IL-7 and the β-chain of hepatocyte growth factor (HGFβ) (IL-7/HGFβ), from a unique long-term BM culture system. We have cloned and expressed the IL-7/HGFβ gene in which the IL-7 and HGFβ genes are connected by a flexible linker to generate rIL-7/HGFβ protein. Here, we show that rIL-7/HGFβ treatment enhances thymopoiesis after allogeneic BMT. Although rIL-7 treatment also enhances the number of thymocytes, rIL-7/HGFβ hybrid cytokine was more effective than was rIL-7 and the mechanisms by which rIL-7 and rIL-7/HGFβ increase the numbers of thymocytes are different. rIL-7 enhances the survival of double negative (DN), CD4 and CD8 single positive (SP) thymocytes. In contrast, rIL-7/HGFβ enhances the proliferation of the DN, SP thymocytes, as well as the survival of CD4 and CD8 double positive (DP) thymocytes. rIL-7/HGFβ treatment also increases the numbers of early thymocyte progenitors (ETPs) and thymic epithelial cells (TECs). The enhanced thymic reconstitution in the rIL-7/HGFβ-treated allogeneic BMT recipients results in increased number and functional activities of peripheral T cells. Graft-versus-host-disease (GVHD) is not induced in the rIL-7/HGFβ-treated BMT mice. Therefore, rIL-7/HGFβ may offer a new tool for the prevention and/or treatment of T cell immunodeficiency following BMT.</p> </div

rIL-7/HGFβ-treated allo-BMT recipients do not develop GVHD.

<p>Lethally irradiated BALB/c mice were injected with TCD-BM from B6 mice. Syngeneic BMT (both BM and recipients from B6 mice) were used as controls. Both syngeneic and allo-BMT recipients were treated with rIL-7/HGFβ (15 μg) or PBS at 2-day intervals from days 1 to 26 after BMT. (A) weights and (B) histopathological analysis of signs of GVHD in liver, small bowel (SB) and large bowel (LB) were conducted on day 75 after BMT. (C) Splenocytes harvested from the allo-BMT recipients were used as effector cells for MLRs. Splenocytes from normal non-BMT B6 mice were used as controls. The effector cells were cultured with irradiated splenocytes (as stimulators) from normal non-BMT BALB/c, B6, and CBA mice, respectively. Cell proliferation was determined by BrdU incorporation. Mean OD in MLRs/OD in spontaneous proliferation with splenocytes from all-BMT recipients or normal B6 mice as effectors and splenocytes from BALB/c, B6, and CBA mice as stimulators were 0.21/0.20, 0.20/0.20, 2.97/0.21, as well as 2.95/0.21, 0.21/0.20, and 3.15/0.22, respectively. Data are shown as stimulation index. (A-C) The data are representative of 2 independent experiments of 5 mice each group. </p