Differences in IgG autoantibody Fab glycosylation across autoimmune diseases.

BACKGROUND: Increased prevalence of autoantibody Fab glycosylation has been demonstrated for several autoimmune diseases. OBJECTIVES: To study whether elevated Fab glycosylation is a common feature of autoimmunity, this study investigated Fab glycosylation levels on serum IgG and its subclasses for autoantibodies associated with a range of different B cell-mediated autoimmune diseases, including rheumatoid arthritis, myasthenia gravis subtypes, pemphigus vulgaris, antineutrophil cytoplasmic antibody-associated vasculitis, systemic lupus erythematosus, anti-glomerular basement membrane glomerulonephritis, thrombotic thrombocytopenic purpura, and Guillain-Barré syndrome. METHODS: The level of Fab glycosylated IgG antibodies was assessed by lectin affinity chromatography and autoantigen-specific immunoassays. RESULTS: In 6 of 10 autoantibody responses, in 5 of 8 diseases, the investigators found increased levels of Fab glycosylation on IgG autoantibodies that varied from 86% in rheumatoid arthritis to 26% in systemic lupus erythematosus. Elevated autoantibody Fab glycosylation was not restricted to IgG4, which is known to be prone to Fab glycosylation, but was also present in IgG1. When autoimmune diseases with a chronic disease course were compared with more acute autoimmune illnesses, increased Fab glycosylation was restricted to the chronic diseases. As a proxy for chronic autoantigen exposure, the investigators determined Fab glycosylation levels on antibodies to common latent herpes viruses, as well as to glycoprotein 120 in individuals who are chronically HIV-1-infected. Immunity to these viral antigens was not associated with increased Fab glycosylation levels, indicating that chronic antigen-stimulation as such does not lead to increased Fab glycosylation levels. CONCLUSIONS: These data indicate that in chronic but not acute B cell-mediated autoimmune diseases, disease-specific autoantibodies are enriched for Fab glycans.

Templated insertions at VD and DJ junctions create unique B-cell receptors in the healthy B-cell repertoire.

RAG complexes recognise (cryptic) RSS sites both in and outside immunoglobulin sites. Excision circles may be reinserted into V(D)J rearrangements as long templated insertions to diversify the adaptive immune repertoire. We show that such VDJ with templated insertions are incidentally found in the repertoire of healthy donors.

A Comparison of Immunoglobulin Variable Region N-Linked Glycosylation in Healthy Donors, Autoimmune Disease and Lymphoma.

N-linked glycans play an important role in immunity. Although the role of N-linked glycans in the Fragment crystallizable (Fc) region of immunoglobulins has been thoroughly described, the function of N-linked glycans present in Ig-variable domains is only just being appreciated. Most of the N-linked glycans harbored by immunoglobulin variable domain are of the complex biantennary type and are found as a result of the presence of N-linked glycosylation that most often have been introduced by somatic hypermutation. Furthermore, these glycans are ubiquitously present on autoantibodies observed in some autoimmune diseases as well as certain B-cell lymphomas. For example, variable domain glycans are abundantly found by anti-citrullinated protein antibodies (ACPA) in rheumatoid arthritis (RA) as well as by the B-cell receptors of follicular lymphoma (FL). In FL, variable domain glycans are postulated to convey a selective advantage through interaction with lectins and/or microbiota, whereas the contribution of variable domain glycans on autoantibodies is not known. To aid the understanding how these seemingly comparable phenomena contribute to a variety of deranged B-responses in such different diseases this study summarizes the characteristics of ACPA and other auto-antibodies with FL and healthy donor immunoglobulins, to identify the commonalities and differences between variable domain glycans in autoimmune and malignant settings. Our finding indicate intriguing differences in variable domain glycan distribution, frequency and glycan composition in different conditions. These findings underline that variable domain glycosylation is a heterogeneous process that may lead to a number of pathogenic outcomes. Based on the current body of knowledge, we postulate three disease groups with distinct variable domain glycosylation patterns, which might correspond with distinct underlying pathogenic processes.

The direct oral anticoagulants rivaroxaban and dabigatran do not inhibit orthotopic growth and metastasis of human breast cancer in mice.

Essentials Factor Xa (FXa)-targeting direct oral anticoagulants (DOACs) reduce venous thromboembolism (VTE) The effects of FXa-targeting DOACs on cancer progression remain to be studied In xenograft models, a FXa-targeting DOAC did not inhibit breast cancer growth and metastasis A thrombin-targeting DOAC, dabigatran, also did not inhibit breast cancer growth and metastasis ABSTRACT: Background Factor Xa-targeting DOACs were recently found to reduce recurrent VTE efficiently in cancer patients when compared to the standard treatment with low-molecular-weight heparins (LMWHs). While the anticancer effects of LMWHs have been extensively studied in preclinical cancer models, the effects of FXa-targeting DOACs on cancer progression remain to be studied. Objective We investigated whether the FXa-targeting DOAC rivaroxaban and the thrombin-targeting DOAC dabigatran etexilate (DE) affected human breast cancer growth and metastasis in orthotopic xenograft models. Methods/results Mice that were put on a custom-made chow diet supplemented with rivaroxaban (0.4 or 1.0 mg/g diet) or dabigatran etexilate (DE) (10 mg/g diet) showed prolonged ex vivo coagulation times (prothrombin time [PT] and activated partial thromboplastin time [aPTT] assay, respectively). However, rivaroxaban and DE did not inhibit MDA-MB-231 tumor growth and metastasis formation in lungs or livers of 7-week-old fully immunodeficient NOD/SCID/Æ´C-/- (NSG) mice. Comparable data were obtained for rivaroxaban-treated mice when using NOD-SCID mice. Rivaroxaban and DE treatment also did not significantly inhibit tumor growth and metastasis formation when using another human triple negative breast cancer (TNBC) cell line (HCC1806) in NOD-SCID mice. The FXa and thrombin-induced gene expression of the downstream target CXCL8 in both cell lines, but FXa and thrombin, did not significantly stimulate migration, proliferation, or stemness in vitro. Conclusion Although effectively inhibiting coagulation, the DOACs rivaroxaban and DE did not inhibit orthotopic growth and metastasis of human TNBC. It remains to be investigated whether DOACs exert antitumorigenic effects in other types of cancer.