Cloning of a Carcinoembryonic Antigen Gene Family Member Expressed in Leukocytes of Chronic Myeloid Leukemia Patients and Bone Marrow

The carcinoembryonic antigen (CEA) gene family belongs to the immunoglobulin superfamily and can be subdivided into the CEA and pregnancy-specific glycoprotein subgroups. The basic structure of the encoded proteins consists of, in addition to a leader, one IgV-like and 2, 3, or 6 IgC-like domains. These domains are followed by varying COOH-terminal regions responsible for secretion, transmembrane anchoring, or insertion into the membrane by a glycosyl phosphatidylinositol tail. Here we report on the characterization of CGM6, a new member of the CEA gene subgroup, by complementary DNA cloning. The deduced coding region comprises 349 amino acids and consists of a leader, one IgV-like, two IgC-like domains, and a hydrophobic region, which is replaced by a glycosyl phosphatidylinositol moiety in the mature protein. CGM6 transcripts were only found thus far in leukocytes of chronic myeloid leukemia patients, in normal bone marrow, and in marginal amounts in normal granulocytes. The CGM6 gene product might, therefore, represent a myeloid marker. Analyses of CGM6 protein-expressing HeLa transfectants with monoclonal antibodies strongly indicate that the CGM6 gene codes for the CEA family member NCA-95

An anti-CD45RO/RB monoclonal antibody modulates T cell responses via induction of apoptosis and generation of regulatory T cells

The effects of a chimeric monoclonal antibody (chA6 mAb) that recognizes both the RO and RB isoforms of the transmembrane protein tyrosine phosphatase CD45 on human T cells were investigated. Chimeric A6 (chA6) mAb potently inhibited antigen-specific and polyclonal T cell responses. ChA6 mAb induced activation-independent apoptosis in CD4+CD45RO/RBhigh T cells but not in CD8+ T cells. In addition, CD4+ T cell lines specific for tetanus toxoid (TT) generated in the presence of chA6 mAb were anergic and suppressed the proliferation and interferon (IFN)-γ production by TT-specific effector T cells by an interleukin-10–dependent mechanism, indicating that these cells were equivalent to type 1 regulatory T cells. Similarly, CD8+ T cell lines specific for the influenza A matrix protein-derived peptide (MP.58-66) generated in the presence of chA6 mAb were anergic and suppressed IFN-γ production by MP.58-66–specific effector CD8+ T cells. Furthermore, chA6 mAb significantly prolonged human pancreatic islet allograft survival in nonobese diabetic/severe combined immunodeficiency mice injected with human peripheral blood lymphocytes (hu-PBL-NOD/SCID). Together, these results demonstrate that the chA6 mAb is a new immunomodulatory agent with multiple modes of action, including deletion of preexisting memory and recently activated T cells and induction of anergic CD4+ and CD8+ regulatory T cells

Interleukin-17A blockade with secukinumab results in decreased neutrophil infiltration in psoriasis: minimally-invasive measurement by tape stripping

Psoriasis is a well characterized interleukin (IL)-17A-driven skin disease with neutrophil infiltration and epidermal hyperkeratosis. Several biomarkers, most prominently β-defensin-2 (BD-2), have been identified using local and systemic invasive measurements as responsive markers of IL-17A-driven skin pathology. We sought to determine whether measurements of epidermal proteins by tape stripping could offer a minimally-invasive method to assess treatment responses. We compared the expression of 170 proteins in the epidermis (tape stripping) and dermis (open flow microperfusion) of 8 psoriatic subjects before and after administration of a single dose of subcutaneous (s.c.) antiIL-17A mAb secukinumab. Proteomic analyses of tape strips revealed a >3-fold decrease in 32 epidermal and inflammatory cell proteins in response to secukinumab. The epidermal proteins with the largest (>10-fold) decreases were: matrix metalloproteinase-8 (MMP-8, 15.68-fold, p<0.05); myeloperoxidase (MPO, 14.72-fold, p<0.005); IL-8 (11.93-fold, p<0.05); MMP-9 (10.81-fold, p<0.005); and IL-1β (10.35-fold, p<0.05). For these proteins, greater-fold protein changes were detected in the epidermis compared to dermis. Immunohistochemical analysis confirmed that neutrophils are the predominant cell type in psoriatic skin lesions that express MPO, MMP-8 and MMP-9, and that secukinumab treatment dramatically decreases neutrophil accumulation. Thus, tape stripping may be used to assess epidermal neutrophils, and protein biomarker responses to anti-IL-17A therapy in psoriasis

CD47 fusion protein targets CD172a+ cells in Crohn’s disease and dampens the production of IL-1β and TNF

In mice, the transfer of CD172a(+) (SIRP-α) dendritic cells (DCs) elicits T cell–driven colitis, whereas treatment with CD47-Fc protein, a CD172a-binding agent, confers protection. The aim of this study was to elucidate the nature and functional properties of human CD172a(+) DCs in chronic intestinal inflammation. Here, we show that CD172a(+)CD11c(+) cells accumulate in the mesenteric lymph nodes (mLNs) and inflamed intestinal mucosa in patients with Crohn’s disease (CD). These cells are distinct from resident DCs and may coexpress markers typically associated with monocyte-derived inflammatory DCs such as CD14 and/or DC-SIGN, E-Cadherin, and/or CX(3)CR1. Spontaneous IL-1β and TNF production by HLA-DR(+) cells in CD tissues is restricted to those expressing CD172a. An avidity-improved CD47 fusion protein (CD47-Var1) suppresses the release of a wide array of inflammatory cytokines by CD172a(+) cells, which may include HLA-DR(−)CD172a(+) neutrophils, in inflamed colonic explant cultures and impairs the ability of HLA-DR(+)CD172a(+) cells to activate memory Th17 but not Th1 responses in mLNs. In conclusion, targeting CD172a(+) cells may represent novel therapeutic perspectives for patients with CD

Effect of IL-17A blockade with secukinumab in autoimmune diseases

The importance of Th17 cells in the pathophysiology of autoimmune disorders has become increasingly appreciated in the past several years. Genetic studies and correlative expression data in diseased tissues have pointed to the role of Th17 cells in the pathogenesis of psoriasis, inflammatory bowel disease, and seronegative spondyloarthropathies. While it is known that Th17 cells produce the pro-inflammatory cytokine interleukin (IL)-17A, recent research has demonstrated that IL-17A is also expressed by multiple lineages of the innate immune system, including mast cells, neutrophils, dendritic cells, gammadelta-T cells, macrophages, and natural killer cells. Th17 cells also express other effector cytokines, such as IL-17F and IL-22. It can thus be expected that inhibiting IL-17A as a therapeutic target in autoimmune disease would exert different physiologic effects than suppressing Th17 activity. Early clinical data are now available on secukinumab (AIN 457), a recombinant, highly selective, fully human monoclonal anti-IL17A antibody of the IgG1/kappa isotype, enabling a preliminary assessment of the effects of IL-17A inhibition in multiple autoimmune diseases. Rapid and sustained symptom reductions in psoriasis, rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis have been observed in secukinumab-treated patients, with no important safety signals. In conjunction with data on the humanized anti-IL-17A monoclonal antibody ixekizumab (LY2439821) and the fully human anti-IL-17RA monoclonal antibody brodalumab (AMG 827), these findings provide evidence for the role of IL-17A to the pathophysiology of autoimmune disease and suggest the potential value of targeting this cytokine

Force-mediated kinetics of single P-selectin/ligand complexes observed by atomic force microscopy

Leukocytes roll along the endothelium of postcapillary venules in response to inflammatory signals. Rolling under the hydrodynamic drag forces of blood flow is mediated by the interaction between selectins and their ligands across the leukocyte and endothelial cell surfaces. Here we present force-spectroscopy experiments on single complexes of P-selectin and P-selectin glycoprotein ligand-1 by atomic force microscopy to determine the intrinsic molecular properties of this dynamic adhesion process. By modeling intermolecular and intramolecular forces as well as the adhesion probability in atomic force microscopy experiments we gain information on rupture forces, elasticity, and kinetics of the P-selectin/P-selectin glycoprotein ligand-1 interaction. The complexes are able to withstand forces up to 165 pN and show a chain-like elasticity with a molecular spring constant of 5.3 pN nm(−1) and a persistence length of 0.35 nm. The dissociation constant (off-rate) varies over three orders of magnitude from 0.02 s(−1) under zero force up to 15 s(−1) under external applied forces. Rupture force and lifetime of the complexes are not constant, but directly depend on the applied force per unit time, which is a product of the intrinsic molecular elasticity and the external pulling velocity. The high strength of binding combined with force-dependent rate constants and high molecular elasticity are tailored to support physiological leukocyte rolling

Structural Analysis Reveals that the Cytokine IL-17F Forms a Homodimeric Complex with Receptor IL-17RC to Drive IL-17RA-Independent Signaling

IL-17, a crucial cytokine for chronic inflammatory diseases, forms a heteromeric complex with IL-17RA and IL-17RC receptors for signaling. Goepfert et al. determine the structure of human IL-17F bound to IL-17RC and reveal a homodimeric assembly that contrasts with the prevailing signaling paradigm and suggests IL-17RA-independent roles for IL-17RC. Interleukin-17A (IL-17A), IL-17F, and IL-17A/F heterodimers are key cytokines of the innate and adaptive immune response. Dysregulation of the IL-17 pathway contributes to immune pathology, and it is therefore important to elucidate the molecular mechanisms that govern IL-17 recognition and signaling. The receptor IL-17RC is thought to act in concert with IL-17RA to transduce IL-17A-, IL-17F-, and IL-17A/F-mediated signals. We report the crystal structure of the extracellular domain of human IL-17RC in complex with IL-17F. In contrast to the expected model, we found that IL-17RC formed a symmetrical 2:1 complex with IL-17F, thus competing with IL-17RA for cytokine binding. Using biophysical techniques, we showed that IL-17A and IL-17A/F also form 2:1 complexes with IL-17RC, suggesting the possibility of IL-17RA-independent IL-17 signaling pathways. The crystal structure of the IL-17RC:IL-17F complex provides a structural basis for IL-17F signaling through IL-17RC, with potential therapeutic applications for respiratory allergy and inflammatory bowel diseases