In Vitro Bone Marrow Niches for Hematopoietic Cells : to have and to hold, in sickness and in health

The bone marrow is a complex tissue within the bones, responsible for the production of blood cells. Within the bone marrow, different types of blood cells arise from so-called stem cells. The bone marrow plays an important role in the support and regulation of these hematopoietic stem and progenitor cells. Several malignancies can also develop in the bone marrow, including multiple myeloma, a cancer of plasma cells. Both cell types cannot survive outside the bone marrow and are therefore dependent on their surrounding, supportive environment: the bone marrow niche. By mimicking the bone marrow niche in vitro (outside the body), both hematopoietic stem and progenitor cells and multiple myeloma cells can be cultured and thus be used for further research. The studies described in this thesis investigate the possibilities to develop an artificial bone marrow niche model in vitro that can be used as a platform to culture hematopoietic stem and progenitor cells as well as myeloma cells. For both cell types, the components of a supportive bone marrow niche model were optimized. Various combinations of primary stromal cell types, hydrogels and biofabricated architectures were investigated, in search of the most essential components of these complex environments. The developed myeloma bone marrow niche model was further validated, analyzing the genetic stability of the cultured myeloma cells. Also the feasibility of using the model to assess therapeutic responses was analyzed. T cell therapy, liposomal drug therapy, as well as conventional chemotherapy were tested in the model, analyzing their effect on both myeloma cells and the supporting stromal cells. Lastly, the capability of the developed myeloma bone marrow niche model to predict clinical treatment outcomes was evaluated. The developed model will be used in further research to look at the effects of multiple myeloma cells and given anticancer therapies on the surrounding bone and bone marrow, as well as further research into the metastatic bone marrow niche environment, investigating cancer-niche interactions

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-Barre ⠁ 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. (J Allergy Clin Immunol 2023;151:16 46-54.)Pathophysiology and treatment of rheumatic disease