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Principal Investigator: Emmanuel Zorn
Organization: COLUMBIA UNIVERSITY HEALTH SCIENCES
Fiscal Year: 2024
Award: $205,625
Funding agency: National Institute of Allergy and Infectious Diseases
Project Summary
Serum IgM have crucial “housekeeping” functions such as the clearance of apoptotic cells and cellular debris,
preventing their accumulation in tissue. However, despite their important role, IgM have been largely
understudied in comparison to other immunoglobulin isotypes, especially IgG. A central characteristic of serum
IgM linked to their biological function is their reactivity to simple chemical moieties exposed on cell membranes
and macromolecules. For instance, IgM bind to phosphorylcholine on apoptotic cells to promote their elimination.
These moieties form adducts when attached to proteins or other macromolecules. Remarkably, only a few
chemical adducts recognized by serum IgM have been identified thus far. Whether these are examples of a
much larger group of chemical radicals targeted by serum IgM is unknown. To address this knowledge gap, we
developed a high-dimensional platform to assess monoclonal IgM and serum IgM reactivity to 87 ubiquitous
adducts. Results showed that: 1) monoclonal “polyreactive” IgM cloned from memory blood B cells and binding
to apoptotic cells, hence displaying a typical “natural antibody” profile, react in fact to specific adducts; 2) the
anti-adduct IgM repertoire is highly restricted in newborns and only includes reactivity to a limited number of
adducts; 3) IgM reactivity diversifies abruptly around 6 months of age, marking a transition from a restricted
neonatal repertoire to a broad adult repertoire and 4) this transition appears to coincide with exposure to
environmental antigens. Overall, these studies uncovered a much more complex anti-adduct IgM immunity than
was initially anticipated. Yet, several important questions remain unanswered: What are the functional niches of
anti-adduct B cells/PC? Do anti-adduct B cells constitute a distinct subset with specific phenotypic
characteristics? What is the role of anti-adduct IgM in efferocytosis and regulation of inflammation? Are these
functions dependent on the IgM specificity to individual adducts? Our proposed studies will address these salient
questions through the characterization of anti-adduct B cell and PC at the single-cell level.
Specific aim-1. To characterize anti-adduct memory B cells and plasma cells and map their niches
We will first detect anti-adduct memory IgM+ B cells and IgM-secreting cells in the bone marrow, spleen, thymus
and gut-associated lymphoid tissue in order to identify their main niches. We will then characterize the phenotype
of anti-adduct memory IgM+ B cells using flow cytometry and single-cell-RNA-seq combined with BCR-seq to
profile their transcriptome and evaluate their clonal composition in vivo.
Specific aim-2. To determine the role of anti-adduct IgM in regulation of efferocytosis and inflammation
In specific aim 2 we will examine the capacity of IgM mab specific to individual adducts to opsonize apoptotic
cells and enhance their clearance by different types of phagocytes. We will also investigate the role of
complement in this function. In a second part, we will examine whether apoptotic cells opsonized by IgM reactive
to different adducts trigger distinct cytokine secretion upon their uptake by phagocytes.
Terms: <0-4 weeks old><19S Gamma Globulin><21+ years old><7S Gamma Globulin><Address><Adult><Adult Human><Age Months><Allergy><Antigenic Determinants><Antigens><Apoptotic><Area><Assay><Autoimmune Diseases><Autoimmune Thrombocytopenias><Autoimmune Thrombocytopenic Purpura><B blood cells><B cell><B cells><B-Cells><B-Lymphocytes><B-cell><B-cell receptor repertoire sequencing><B-cell receptor sequencing><BCR repertoire sequencing><BCR seq><BCR sequencing><BCRseq><Binding><Binding Determinants><Bioassay><Biological Assay><Biological Function><Biological Process><Blood Plasma Cell><Blood Serum><Body Tissues><Bone Marrow><Bone Marrow Reticuloendothelial System><Cell Body><Cell membrane><Cell secretion><Cell surface><Cells><Cellular Secretion><Characteristics><Chemicals><Choline Chloride Dihydrogen Phosphate><Choline Phosphate><Choline Phosphate Chloride><Clone Cells><Collection><Complement><Complement Proteins><Complex><Cytoplasmic Membrane><ELISPOT><Epitopes><Exposure to><Flow Cytofluorometries><Flow Cytofluorometry><Flow Cytometry><Flow Microfluorimetry><Flow Microfluorometry><Gut associated lymphoid tissue><Housekeeping><Housework><Human><Humoral Immunities><Hypersensitivity><Idiopathic Thrombocytopenic Purpura><IgG><IgM><Immune thrombocytopenia><Immunity><Immunoglobulin G><Immunoglobulin Isotypes><Immunoglobulin M><Incidence><Individual><Inflammation><Knowledge><Link><Lupus Erythematosus Disseminatus><Malonaldehyde><Malondialdehyde><Malonylaldehyde><Malonyldialdehyde><Maps><Memory><Memory B Cell><Memory B-Lymphocyte><Modern Man><Molecular Interaction><Neonatal><Newborn Infant><Newborns><OxLDL><Patients><Phagocytes><Phagocytic Cell><Phenotype><Phosphocholine><Phosphorylcholine><Phosphorylcholine Chloride><Plasma Cells><Plasma Membrane><Plasmacytes><Play><Process><Propanedial><Property><Proteins><Reaction><Regulation><Research><Role><SLE><Serum><Source><Specificity><Spleen><Spleen Reticuloendothelial System><Systemic Lupus Erythematosus><Systemic Lupus Erythematous><Systemic Lupus Erythmatosus><Thymus><Thymus Gland><Thymus Proper><Thymus Reticuloendothelial System><Tissues><Werlhof's Disease><adduct><adulthood><amebocyte><antibody-based immunity><autoimmune condition><autoimmune disorder><autoimmunity disease><bacteria pathogen><bacterial pathogen><chemical group><complementation><cytokine><disseminated lupus erythematosus><early childhood><enzyme linked immunospot assay><experiment><experimental research><experimental study><experiments><flow cytophotometry><global gene expression><global transcription profile><high dimensionality><immune thrombocytopenic purpura><immunogen><in vivo><macromolecule><natural antibodies><neonate><newborn child><newborn children><ox-LDL><oxidation><oxidized LDL><oxidized low density lipoprotein><pathogen><pathogenic bacteria><pathogenic virus><plasmalemma><plasmocyte><prevent><preventing><scRNA-seq><single cell RNA-seq><single cell RNAseq><single cell expression profiling><single cell transcriptomic profiling><single-cell RNA sequencing><social role><systemic lupus erythematosis><transcriptome><uptake><viral pathogen><virus pathogen>