Biology subjects

von Bergwelt-Baildon, M.

Publications and source records attributed to von Bergwelt-Baildon, M..

4 recordsLinked to original sources

bioRxiv2024

L-Asparaginase treatment induces reversible immunoregulatory and immunosuppressive effects in non-malignant B cells in a model of T-cell dependent B cell activation

Metabolic reprogramming is critical for immune cell adaptation upon activation to exert full functionality with amino acids being a key metabolic factor. While L-asparagine is a non- essential amino acid it turns out to be conditionally essential in malignant B cells due to defective asparagine synthetase making L-asparaginase a commonly used chemotherapeutic agent. Off-target enzymatic activity including glutaminolysis impacting crucial immune function. However, its effects on healthy B cells remain unclear, therefore in this study, we explored how L-asparaginase modulates the biology and function of CD40-activated B cells, using an in-vitro model. B cells from healthy donors were treated with increasing L- asparaginase concentrations and analyzed for proliferation, immune phenotype, and metabolic changes. Results showed L-asparaginase reduced B cell proliferation and homotypic clustering without inducing apoptosis, instead impairing metabolic pathways, lowering glycolysis and oxidative phosphorylation, and reducing surface markers associated with antigen-presenting cell (APC) function. Functional assays confirmed that L-asparaginase- treated B cells had diminished ability to activate T cells. Supplementing with asparagine or glutamine restored B cell proliferation and function, with glutamine slightly more effective than asparagine. Interestingly, L-asparaginase induced a regulatory B cell phenotype, marked by CD24+CD38+CD27+ expression and increased interleukin-10 and TGF-beta, suggesting a potential immunosuppressive mechanism. These findings indicate that L-asparaginase not only affects malignant cells but also impacts the function of non-malignant B cells, proposing potential therapeutic applications in B cell-driven autoimmune disorders. Further studies are needed to explore its effects at lower, clinically relevant concentrations. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/625617v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@1ae8d10org.highwire.dtl.DTLVardef@af405borg.highwire.dtl.DTLVardef@1aa4c0eorg.highwire.dtl.DTLVardef@16750ea_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

ARID1A Mutations Protect Follicular Lymphoma from FAS-dependent Immune Surveillance by Reducing RUNX3/ETS1-Driven FAS-Expression

The cell death receptor FAS and its ligand (FASLG) play crucial roles in the selection of B cells during the germinal center (GC) reaction. Failure to eliminate potentially harmful B cells via FAS can lead to lymphoproliferation and the development B cell malignancies. The classic form of follicular lymphoma (FL) is a prototypic GC-derived B cell malignancy, characterized by the t(14;18) (q32;q21)IGH::BCL2 translocation and overexpression of antiapoptotic BCL2. Additional alterations were shown to be clinically relevant, including mutations in ARID1A. ARID1A is part of the SWI/SNF nucleosome remodeling complex that regulates DNA accessibility ("openness"). However, the mechanism how ARID1A mutations contribute to FL pathogenesis remains unclear. We analyzed 151 FL biopsies of patients with advanced stage disease at initial diagnosis and found that ARID1A mutations were recurrent and mainly disruptive, with an overall frequency of 18%. Additionally, we observed that ARID1A mutant FL showed significantly lower FAS protein expression in the FL tumor cell population. Functional experiments in BCL2-translocated lymphoma cells demonstrated that ARID1A is directly involved in the regulation of FAS, and ARID1A loss leads to decreased FAS protein and gene expression. However, ARID1A loss did not affect FAS promotor openness. Instead, we identified and experimentally validated a previously unknown co-transcriptional complex consisting of RUNX3 and ETS1 that regulates FAS expression, and ARID1A loss leads to reduced RUNX3 promotor openness and gene expression. The reduced FAS levels induced by ARID1A loss rendered lymphoma cells resistant to both soluble and T cell membrane-anchored FASLG-induced apoptosis. In summary, we have identified a functionally and clinically relevant mechanism how FL cells can escape FAS-dependent immune surveillance, which may also impact the efficacy of T cell-based therapies, including bispecific antibodies and CAR T cells.

cancer biology↗

bioRxiv2021

Impaired function and delayed regeneration of dendritic cells in COVID-19

Disease manifestations in COVID-19 range from mild to severe illness associated with a dysregulated innate immune response. Alterations in function and regeneration of dendritic cells (DC) and monocytes may contribute to immunopathology and influence adaptive immune responses in COVID-19 patients. We analyzed circulating DC and monocyte subsets in 65 hospitalized COVID-19 patients with mild/moderate or severe disease from acute disease to recovery and in healthy controls. Persisting reduction of all DC subpopulations was accompanied by an expansion of proliferating Lineage- HLADR+ cells lacking DC markers. Increased frequency of the recently discovered CD163+ CD14+ DC3 subpopulation in patients with more severe disease was associated with systemic inflammation, activated T follicular helper cells, and antibody-secreting cells. Persistent downregulation of CD86 and upregulation of PD-L1 in conventional DC (cDC2 and DC3) and classical monocytes associated with a reduced capacity to stimulate naive CD4+ T cells correlated with disease severity. Long-lasting depletion and functional impairment of DCs and monocytes may have consequences for susceptibility to secondary infections and therapy of COVID-19 patients.

immunology↗

bioRxiv2021

Protective immune trajectories in early viral containment of non-pneumonic SARS-CoV-2 infection

The immune system of most SARS-CoV-2 infected individuals limits viral spread to the upper airways without pulmonary involvement. This prevents the development of pneumonic COVID-19. However, the protective immunological responses causative of successful viral containment in the upper airways remain unclear. Here, we combine longitudinal single-cell RNA sequencing, proteomic profiling, multidimensional flow cytometry, RNA-Seq of FACS-sorted leukocyte subsets and multiplex plasma interferon profiling to uncover temporally resolved protective immune signatures in non-pneumonic and ambulatory SARS-CoV-2 infected patients. We compare host responses in a high-risk patient population infected with SARS-CoV-2 but without pulmonary involvement to patients with COVID-19 pneumonia. Our data reveal a distinct immunological signature of successful viral containment, characterized by an early prominent interferon stimulated gene (ISG) upregulation across immune cell subsets. In addition, reduced cytotoxic potential of Natural Killer (NK) and T cells, as well as a monocyte phenotype with immune-modulatory potential are hallmarks of protective immunity. Temporal resolution across disease trajectories highlights ISG upregulation as particularly prominent early in the disease and confirms increased expression also in comparison to healthy controls. We validate this distinct temporal ISG signature by in-depth RNA-seq of FACS-sorted leukocyte subsets in a large prospective ambulatory SARS-CoV-2 infected cohort confirming early and robust ISG upregulation particularly in monocytes and T cells. In conclusion, our data demonstrate a protective ISG phenotype in patients with successful containment of SARS-CoV-2 infection without progression to COVID-19. This early protective interferon response might be exploited as a therapeutic approach and for disease course prediction.

immunology↗