Project description:Although severe COVID-19 is often associated with elevated autoantibody titers, the underlying mechanism has been unclear. Here, we investigated repertoires and reactivities of immunoglobulins derived from blood plasmablasts (PBs) in COVID-19 patients. This uncovered robust clonal expansion of PBs secreting cardiolipin (CL)-reactive autoantibodies in humoral response to SARS-CoV-2. About half of the expanded CL-reactive clones were also reactive to SARS-CoV-2 antigens and derived from SARS-CoV-2-specific primary responses as well as seasonal coronavirus-reactive memory responses. One such clone, CoV1804, was reactive to both CL and viral nucleocapsid (N), and exhibited anti-nucleolar activity in human cells. Repertoire analysis identified antibodies sharing genetic features with CoV1804 in COVID-19 patient-derived immunoglobulins from our and other cohorts, thereby constituting a novel public antibody. These public autoantibodies had numerous mutations that enhanced anti-N reactivity. On the other hand, anti-CL reactivity fluctuated through somatic hypermutation, which instead resulted in the acquisition of additional self-reactivities, including anti-nucleolar activity in the progeny. Thus, potentially CL-reactive precursors may have developed multiple reactivities to different self-antigens through clonal expansion driven by viral antigens. Our results unraveled a unique process of autoantibody production during COVID-19 and provide novel insights into the origin of virus-induced autoantibodies.
Project description:To study longitudinal dynamics of IGH BCR repertoires and clonal lineages evolution of memory B-cells, plasmablasts and plasma cells from peripheral blood of healthy donors, which were sampled three times within a year
Project description:T cell–B cell interaction is the key immune response to protect host from severe viral infection. We used COVID-19 as a model of acute viral infections and analyzed CD4+ T cell subsets associated with plasmablasts expansion and clinical outcome. Peripheral helper T cells (Tph, denoted as PD-1highCXCR5–CD4+ T cells) were significantly increased, as were plasmablasts. Tph cells exhibited “B-cell help” signatures and induced plasmablasts differentiation in vitro. Expanded plasmablasts showed increased CXCR3 expression, which is positively correlated with higher frequency of activated Tph cells and better clinical outcome. These results elucidate a critical role for Tph cells in regulating protective B cell response during acute viral infection.
Project description:Coronavirus disease 2019 (COVID-19) is associated with significant morbidity and mortality, albeit with considerable heterogeneity among affected individuals. Emerging evidence points towards an important role of preexisting host factors, such as a deregulated inflammatory response at the time of infection. Here, we demonstrate the negative impact of clonal hematopoiesis, a prevalent clonal disorder of ageing individuals, on COVID-19-related cytokine release severity and mortality. In this study we perform use the Illumina MethylationEPIC array to quantify methylation levels in PBMCs from COVID19 patients and patients with clonal hematopoiesis.
Project description:Autoantibodies contribute to many autoimmune diseases, yet there is no therapy to neutralize them selectively. A popular mouse model, experimental autoimmune encephalomyelitis (EAE), could serve to develop such a therapy, provided we can better understand the nature and importance of the autoantibodies involved. In this study, we analyzed autoantibody-secreting extrafollicular plasmablasts in mice with EAE induced by immunization with a mutated myelin oligodendrocyte glycoprotein (MOG) antigen called bMOG. These CD138+ cells were enriched from lymph nodes at day 8 post-immunization and analyzed by single-cell RNA sequencing using 10× Genomics technologies. Here we provide the raw and processed data obtained from the gene expression (GEX) and VDJ cDNA libraries.
Project description:We investigated the kinetics, breadth, magnitude, and level of cross-reactivity of IgG antibodies against SARS-CoV-2 and heterologous seasonal (HCoV-NL63, -229E, -OC43 and -HKU1) and epidemic coronaviruses (SARS-CoV, hCoV-MERS) at the clonal level in patients with mild or severe COVID-19 as well as in disease control patients. We assessed IgG antibody reactivity to nucleocapsid and spike antigens using protein microarray. A cutoff was set at the average plus 3 times the SD of 20 nonreactive cultures with a minimum MFI of 1000.
Project description:Myasthenia gravis (MG) is an autoantibody-mediated autoimmune disorder of the neuromuscular junction. Some patients with MG have pathogenic mAbs that recognize muscle-specific tyrosine kinase (MuSK). Patients respond well to CD20-mediated B-cell depletion therapy (BCDT); most achieve complete stable remission. However, relapse often occurs. To further understand the immunomechanisms underlying relapse we sought to study autoantibody-producing B-cells over the course of BCDT. We developed a monomeric fluorescently labelled antigen to enrich for MuSK-specific B-cells, which was validated with a novel Nalm6 cell line engineered to express a human MuSK autoantibody as B-cell receptor. We found that MuSK-specific B-cells are rare within the circulation (<3 per 10 million cells). From two MuSK-specific B-cells isolated from two distinct patients, we generated human recombinant MuSK mAbs. The autoantibodies originated from plasmablasts, used the IgG4 subclass, recognized the Ig1-like domain of MuSK and showed pathogenic capacity using an in vitro AChR clustering assay. Persistent clones of the mAbs were identified through B-cell repertoire tracing. Clonal variants of 2E6 were detected at several timepoints spanning more than five years months and reemerged after BCDT-mediated remission, appearing several months prior to relapse. These results indicate that a reservoir of rare pathogenic MuSK autoantibody-expressing B cell clones survive BCDT, then reemerge prior to manifestation of clinical relapse. This study provides both a mechanistic understanding of MuSK MG relapse and a valuable candidate biomarker for relapse prediction.
Project description:Coronavirus disease 2019 (COVID-19) is associated with significant morbidity and mortality, albeit with considerable heterogeneity among affected individuals. Emerging evidence points towards an important role of preexisting host factors, such as a deregulated inflammatory response at the time of infection. Here, we demonstrate the negative impact of clonal hematopoiesis, a prevalent clonal disorder of ageing individuals, on COVID-19-related cytokine release severity and mortality. In this study we perform Multiome single cell sequencing of PBMCs from COVID19 patients and patients with clonal hematopoiesis.
Project description:Many clinical risk factors for severe COVID-19, such as diabetes, hypertension, and high body mass index have been reported. However, searching for additional risk factors should be continued to predict the progression of severe COVID-19 more accurately. We suppose that clonal hematopoiesis of indeterminate potential (CHIP) can also be regarded as one of risk factors. To identify the influence of CHIP in COVID-19 pathogenesis, we performed single-cell RNA-seq using peripheral blood mononuclear cells (PBMCs) obtained from severe COVID-19 patient with CHIP and integrate the data with other published COVID-19 scRNA seq data (GSE149689). After clustering and annotating cell types, we compare the expression profiles between CHIP vs non-CHIP COVID-19 severe patient.