Biology subjects

Castrillon, C.

Publications and source records attributed to Castrillon, C..

4 recordsLinked to original sources

bioRxiv2024

Lupus-associated innate receptors drive extrafollicular evolution of autoreactive B cells

In systemic lupus erythematosus, recent findings highlight the extrafollicular (EF) pathway as prominent origin of autoantibody-secreting cells (ASCs). CD21loCD11c+ B cells, associated with aging, infection, and autoimmunity, are contributors to autoreactive EF ASCs but have an obscure developmental trajectory. To study EF kinetics of autoreactive B cell in tissue, we adoptively transferred WT and gene knockout B cell populations into the 564Igi mice - an autoreactive host enriched with autoantigens and T cell help. Time-stamped analyses revealed TLR7 dependence in early escape of peripheral B cell tolerance and establishment of a pre-ASC division program. We propose CD21lo cells as precursors to EF ASCs due to their elevated TLR7 sensitivity and proliferative nature. Blocking receptor function reversed CD21 loss and reduced effector cell generation, portraying CD21 as a differentiation initiator and a possible target for autoreactive B cell suppression. Repertoire analysis further delineated proto-autoreactive B cell selection and receptor evolution toward self-reactivity. This work elucidates receptor and clonal dynamics in EF development of autoreactive B cells, and establishes modular, native systems to probe mechanisms of autoreactivity.

immunology↗

bioRxiv2023

Invasion of spontaneous germinal centers by naive B cells is rapid and persistent

In autoreactive germinal centers (GC) initiated by a single rogue B cell clone, wild-type B cells expand and give rise to clones that target other autoantigens, known as epitope spreading. The chronic, progressive nature of epitope spreading calls for early interventions, but the kinetics and molecular requirements for wild-type B cell invasion and participation in GC remain largely unknown. With parabiosis and adoptive transfer approaches in a murine model of systemic lupus erythematosus, we demonstrate that wild-type B cells join existing GCs rapidly, clonally expand, persist, and contribute to autoantibody production and diversification. The invasion of autoreactive GCs required TLR7, B cell receptor specificity, antigen presentation, and type I interferon signaling. The adoptive transfer model provides a novel tool for identifying early events in the breaking of B cell tolerance in autoimmunity. One Sentence SummaryThe autoreactive germinal center is an open structure that is susceptible to rapid and persistent naive B cell invasion, with clonal expansion and auto-antibody induction and diversification.

immunology↗

bioRxiv2022

Complex subsets but redundant clonality after B cells egress from spontaneous germinal centers

Affinity matured self-reactive antibodies are found in autoimmune diseases like systemic lupus erythematous. Here we used fate-mapping reporter mice and single cell transcriptomics coupled to antibody repertoire analysis to characterize the post-germinal center (GC) B cell compartment in a new mouse model of autoimmunity. Antibody secreting cells (ASCs) and memory B cells (MemBs) from spontaneous GCs grouped into multiple subclusters. ASCs matured into two terminal clusters, with distinct secretion, antibody repertoire and metabolic profiles. MemBs contained FCRL5+ and CD23+ subsets, with different in vivo localization in the spleen. GC-derived FCRL5+ MemBs share transcriptomic and repertoire properties with atypical B cells found in aging and infection and localize to the marginal zone, suggesting a similar contribution to recall responses. While transcriptomically diverse, ASC and MemB subsets maintained an underlying clonal redundancy. Therefore, self-reactive clones could escape subset-targeting therapy by perpetuation of self-reactivity in distinct subsets.

immunology↗

bioRxiv2021

Single-cell analyses of immune thrombocytopenic patients reveal multiorgan dissemination of high-affinity autoreactive plasma cells

The major therapeutic goal for immune thrombocytopenia (ITP) is to restore normal platelet counts using drugs to promote platelet production or by interfering with mechanisms responsible for platelet destruction. 80% of patients possess anti-integrin IIb{beta}3 (GPIIbIIIa) IgG autoantibodies causing platelet opsonization and phagocytosis. The spleen is considered the primary site of autoantibody production by autoreactive B cells and platelet destruction. The immediate failure in ~50% of patients to recover a normal platelet count after anti-CD20 Rituximab-mediated B cell depletion and splenectomy suggest that autoreactive, rituximab-resistant, IgG-secreting B cells (IgG-SC) reside in other anatomical compartments. We analyzed >3,300 single IgG-SC from spleen, bone marrow and/or blood of 27 patients with ITP revealing high inter-individual variability in affinity for GPIIbIIIa with variations over 3 logs. IgG-SC dissemination and range of affinities were however similar per patient. Longitudinal analysis of autoreactive IgG-SC upon treatment with anti-CD38 mAb daratumumab demonstrated variable outcomes, from complete remission to failure with persistence of high-affinity anti-GPIIbIIIa IgG-SC in the bone marrow. This study demonstrates the existence and dissemination of high-affinity autoreactive plasma cells in multiple anatomical compartments of patients with ITP that may cause the failure of current therapies.

immunology↗