Glycan-specific IgG anti-IgE autoantibodies are protective against allergic anaphylaxis in a murine model.

BACKGROUND IgE causes anaphylaxis in type-1 hypersensitivity diseases by activating degranulation of effector cells such as mast cells and basophils. The mechanisms that control IgE activity and prevent anaphylaxis under normal conditions are still enigmatic. OBJECTIVE We aimed to unravel how anti-IgE autoantibodies are induced and understand their role in regulating serum IgE level and allergic anaphylaxis. METHODS We immunized mice with different forms of IgE and tested anti-IgE autoantibody responses and their specificities. We then analysed the effect of those antibodies on serum kinetics and their in vitro and in vivo impact on anaphylaxis. Finally, we investigated anti-IgE autoantibodies in human sera. RESULTS Immunization of mice with IgE-immune complexes induced glycan-specific anti-IgE autoantibodies. The anti-IgE autoantibodies prevented effector cell sensitization, reduced total IgE serum levels, protected mice from passive and active IgE sensitization, and resulted in cross-protection against different allergens. Furthermore, glycan-specific anti-IgE autoantibodies were present in sera from allergic and non-allergic subjects. CONCLUSION In conclusion, we provide first evidence that in the murine model the serum level and anaphylactic activity of IgE may be down-regulated by glycan-specific IgG anti-IgE autoantibodies

Xenogeneic Neu5Gc and self-glycan Neu5Ac epitopes are potential immune targets in MS.

OBJECTIVE To explore the repertoire of glycan-specific immunoglobulin G (IgG) antibodies in treatment-naive patients with relapsing-remitting multiple sclerosis (RRMS). METHODS A systems-level approach combined with glycan array technologies was used to determine specificities and binding reactivities of glycan-specific IgGs in treatment-naive patients with RRMS compared with patients with noninflammatory and other inflammatory neurologic diseases. RESULTS We identified a unique signature of glycan-binding IgG in MS with high reactivities to the dietary xenoglycan N-glycolylneuraminic acid (Neu5Gc) and the self-glycan N-acetylneuraminic acid (Neu5Ac). Increased reactivities of serum IgG toward Neu5Gc and Neu5Ac were additionally observed in an independent, treatment-naive cohort of patients with RRMS. CONCLUSION Patients with MS show increased IgG reactivities to structurally related xenogeneic and human neuraminic acids. The discovery of these glycan-specific epitopes as immune targets and potential biomarkers in MS merits further investigation

Quark stars and quantum-magnetically induced collapse

Quark matter is expected to exist in the interior of compact stellar objects as neutron stars or even the more exotic strange stars, based on the Bodmer-Witten conjecture. Bare strange quark stars and (normal) strange quark-matter stars, those possessing a baryon (electron-supported) crust, are hypothesized as good candidates to explain the properties of a set of peculiar stellar sources as the enigmatic X-ray source RX J1856.5-3754, some pulsars as PSR B1828-11 and PSR B1642-03, and the anomalous X-ray pulsars and soft gamma-ray repeaters. In the MIT bag model, quarks are treated as a degenerate Fermi gas confined to a region of space having a vacuum energy density $B_{bag}$ (the Bag constant). In this note, we modif{}y the MIT Bag Model by including the electromagnetic interaction. We also show that this version of the MIT model implies the anisotropy of the Bag pressure due to the presence of the magnetic field. The equations of state of degenerate quarks gases are studied in the presence of ultra strong magnetic fields. The behavior of a system made-up of quarks having (or not) anomalous magnetic moment is reviewed. A structural instability is found, which is related to the anisotropic nature of the pressures in this highly magnetized matter. The conditions for the collapse of this system are obtained and compared to a previous model of neutron stars build-up on a neutron gas having anomalous magnetic moment.Comment: 11 pages, 2 figure

Modulation of Neutrophil Function by Recombinant Human IgG1 Fc Hexamer in the Endogenous K/BxN Mouse Model of Rheumatoid Arthritis.

INTRODUCTION Neutrophils are a pivotal cell type in the K/BxN mouse model of rheumatoid arthritis and play an essential role in the progression of the arthritis. They are readily activated by immune complexes (ICs) via their FcγRs to release IL-1β in addition to other cytokines, which are inducing cartilage destruction. Neutrophils also release neutrophil-active chemokines to recruit themselves in an autocrine manner to perpetuate tissue destruction. FcγR-expression on neutrophils is of crucial importance for the recognition of ICs. METHODS In this study, due to its high avidity for binding to FcγRs, we investigated the potential anti-inflammatory effect of a recombinant IgG1 Fc hexamer (rFc-µTP-L309C) on neutrophils in the K/BxN mouse model of endogenously generated chronic arthritis. 200 mg/kg rFc-µTP-L309C and human serum albumin (HSA), used as controls, were administered subcutaneously every other day. Mouse ankle joints were monitored daily to generate a clinical score. Immunohistology was used to evaluate neutrophil infiltration and TUNEL to assess apoptosis. ELISA was used to measure IL-1β. RESULTS Treatment with rFc-µTP-L309C, but not HSA, was able to significantly ameliorate the arthritis in the K/BxN mice. Significant neutrophil infiltration into the ankle joint was found, but treatment with rFc-µTP-L309C resulted in significantly less neutrophil infiltration. There was no significant influence of rFc-µTP-L309C on neutrophil death or apoptosis. Less neutrophil infiltration could not be correlated to chemokine-mediated migration. Significantly less IL-1β was measured in mice treated with rFc-µTP-L309C. CONCLUSION In the endogenous K/BxN mouse model of rheumatoid arthritis, amelioration can be explained in part by inhibition of neutrophil infiltration into the joints as well as inhibition of IL-1β production. Given the observed inhibitory properties on neutrophils, rFc-µTP-L309C may be a potential therapeutic candidate to treat autoimmune and inflammatory conditions in which neutrophils are the predominant cell type involved in pathogenesis

Supplemental information Modular adjuvant-free pan-HLA-DR-immunotargeting subunit vaccine against SARS-CoV-2 elicits broad sarbecovirus-neutralizing antibody responses

10 pages. -- Figure S1. Negative stain electron microscopy of purified ITV. -- Figure S2. c44H10 Fab targets an epitope largely conserved across major MHC Class II allele groups. -- Figure S3. Intramuscular ITV-TpD immunization elicits neutralizing antibody responses superior relative to subcutaneous administration. -- Figure S4. ITV-TpD is thermostable when stored at -20°C, 4°C or 40°C for up to 3 weeks. -- Figure S5. Bi-antigenic ITV-TpD elicits broad sarbecovirus-neutralizing antibody responses. -- Supplementary Table 1: Data collection and refinement statistics for the c44H10 Fab-MHC Class II (HLA-DRA*01:01, HLA-DRB1*04:01) complex (related to Figure 2). -- Supplementary Table 2: Table of contacts between the HLA-DR α chain and c44H10 Fab (Related to Figure 2). -- Supplementary Table 3: Table of contacts between the HLA-DR β chain and c44H10 FabPeer reviewe

Self-associated molecular patterns mediate cancer immune evasion by engaging Siglecs on T cells

© 2018, American Society for Clinical Investigation. This article has been published in final form at https://doi.org/10.1172/JCI120612First-generation immune checkpoint inhibitors, including anti-CTLA-4 and anti-programmed death 1 (anti-PD-1) antibodies, have led to major clinical progress, yet resistance frequently leads to treatment failure. Thus, new targets acting on T cells are needed. CD33-related sialic acid-binding immunoglobulin-like lectins (Siglecs) are pattern-recognition immune receptors binding to a range of sialoglycan ligands, which appear to function as self-associated molecular patterns (SAMPs) that suppress autoimmune responses. Siglecs are expressed at very low levels on normal T cells, and these receptors were not until recently considered as interesting targets on T cells for cancer immunotherapy. Here, we show an upregulation of Siglecs, including Siglec-9, on tumor-infiltrating T cells from non-small cell lung cancer (NSCLC), colorectal, and ovarian cancer patients. Siglec-9-expressing T cells coexpressed several inhibitory receptors, including PD-1. Targeting of the sialoglycan-SAMP/Siglec pathway in vitro and in vivo resulted in increased anticancer immunity. T cell expression of Siglec-9 in NSCLC patients correlated with reduced survival, and Siglec-9 polymorphisms showed association with the risk of developing lung and colorectal cancer. Our data identify the sialoglycan-SAMP/Siglec pathway as a potential target for improving T cell activation for immunotherapy.Peer reviewe

Antitumor effects of the GM3(Neu5Gc) ganglioside-specific humanized antibody 14F7hT against Cmah-transfected cancer cells.

The GM3(Neu5Gc) ganglioside represents a tumor-specific antigen that is considered a promising target for cancer immunotherapy. We previously demonstrated that the humanized antibody 14F7hT, specific for this ganglioside, exhibited significant antitumor effects in preclinical hematological tumor models. As this antibody recognizes human tumor tissues from several origins, we addressed its potential effect on different tumor types. The use of cell lines for testing GM3(Neu5Gc)-targeting strategies, in particular for human malignancies, is complicated by the absence in humans of functional cytidine monophospho-N-acetyl-neuraminic acid hydroxylase (CMAH), the enzyme required for Neu5Gc sialic acid biosynthesis. Quantitative flow cytometry revealed the absence of surface GM3(Neu5Gc) in several human but also mouse cell lines, in the last case due to low expression of the enzyme. Hypoxia-induced expression of this ganglioside on human SKOV3 cells was observed upon culture in Neu5Gc-containing medium without evidence for CMAH-independent biosynthesis. However, only transfection of the mouse Cmah gene into human SKOV3 and mouse 3LL cells induced a stable expression of GM3(Neu5Gc) on the cancer cell surface, resulting in effective models to evaluate the antitumor responses by 14F7hT in vitro and in vivo. This antibody exerted antibody-dependent cell-mediated cytotoxicity (ADCC) and in vivo antitumor effects on these Cmah-transfected non-hematological tumors from both mouse and human origin. These results contribute to validate GM3(Neu5Gc) as a relevant target for cancer immunotherapy and reinforces the value of 14F7hT as a novel anti-cancer drug

Modular adjuvant-free pan-HLA-DR-immunotargeting subunit vaccine against SARS-CoV-2 elicits broad sarbecovirus-neutralizing antibody responses

Subunit vaccines typically require co-administration with an adjuvant to elicit protective immunity, adding development hurdles that can impede rapid pandemic responses. To circumvent the need for adjuvant in a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subunit vaccine, we engineer a thermostable immunotargeting vaccine (ITV) that leverages the pan-HLA-DR monoclonal antibody 44H10 to deliver the viral spike protein receptor-binding domain (RBD) to antigen-presenting cells. X-ray crystallography shows that 44H10 binds to a conserved epitope on HLA-DR, providing the basis for its broad HLA-DR reactivity. Adjuvant-free ITV immunization in rabbits and ferrets induces robust anti-RBD antibody responses that neutralize SARS-CoV-2 variants of concern and protect recipients from SARS-CoV-2 challenge. We demonstrate that the modular nature of the ITV scaffold with respect to helper T cell epitopes and diverse RBD antigens facilitates broad sarbecovirus neutralization. Our findings support anti-HLA-DR immunotargeting as an effective means to induce strong antibody responses to subunit antigens without requiring an adjuvant.This work was supported by the Hospital for Sick Children Foundation, operating grant PJT-148811 from the Canadian Institutes of Health Research (J.-P.J.), the CIFAR Azrieli Global Scholar program (J.-P.J.), the Ontario Early Researcher Awards program (J.-P.J.), and the Canada Research Chairs program (J.-P.J.). A.K. and K.M. are supported by Ontario Graduate Scholarships (OGS), and E.S. is supported by a Master’s Canada Graduate Scholarship (CGS-M). I.K. is supported by a Hospital for Sick Children Restracomp Postdoctoral Fellowship, and E.R. is supported by the European Union’s Horizon 2020 research and innovation program under Marie Sklodowska-Curie grant 790012.Peer reviewe

Dysregulated Expression of Glycolipids in Tumor Cells: From Negative Modulator of Anti-tumor Immunity to Promising Targets for Developing Therapeutic Agents

Glycolipids are complex molecules consisting of a ceramide lipid moiety linked to a glycan chain of variable length and structure. Among these are found the gangliosides, which are sialylated glycolipids ubiquitously distributed on the outer layer of vertebrate plasma membranes. Changes in the expression of certain species of gangliosides have been described to occur during cell proliferation, differentiation and ontogenesis. However, the aberrant and elevated expression of gangliosides has been also observed in different types of cancer cells, thereby promoting tumor survival. Moreover, gangliosides are actively released from the membrane of tumor cells, having a strong impact on impairing anti-tumor immunity. Beyond the undesirable effects of gangliosides in cancer cells, a substantial number of cancer immunotherapies have been developed in recent years that have used gangliosides as the main target. This has resulted in successful immune cell- or antibody-responses against glycolipids, with promising results having been obtained in clinical trials. In this review, we provide a general overview on the metabolism of glycolipids, both in normal and tumor cells, as well as examining glycolipid-mediated immune modulation and the main successes achieved in immunotherapies using gangliosides as molecular targets