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- Budeus, B., et al.
(författare)
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Human cord blood b cells differ from the adult counterpart by conserved ig repertoires and accelerated response dynamics
- 2021
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 206:12, s. 2839-2851
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Tidskriftsartikel (refereegranskat)abstract
- Neonatal and infant immune responses are characterized by a limited capability to generate protective Ab titers and memory B cells as seen in adults. Multiple studies support an immature or even impaired character of umbilical cord blood (UCB) B cells themselves. In this study, we provide a comprehensive molecular and functional comparison of B cell subsets from UCB and adult peripheral blood. Most UCB B cells have a mature, naive B cell phenotype as seen in adults. The UCB Ig repertoire is highly variable but interindividually conserved, as BCR clonotypes are frequently shared between neonates. Furthermore, UCB B cells show a distinct transcriptional program that confers accelerated responsiveness to stimulation and facilitated IgA class switching. Stimulation drives extensive differentiation into Ab-secreting cells, presumably limiting memory B cell formation. Humanized mice suggest that the distinctness of UCB versus adult B cells is already reflected by the developmental program of hematopoietic precursors, arguing for a layered B-1/B-2 lineage system as in mice, albeit our findings suggest only partial comparability to murine B-1 cells. Our study shows that UCB B cells are not immature or impaired but differ from their adult mature counterpart in a conserved BCR repertoire, efficient IgA class switching, and accelerated, likely transient response dynamics. © 2021 by TheAmericanAssociation of Immunologists, Inc.
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- Podlesny-Drabiniok, A, et al.
(författare)
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BHLHE40/41 regulate macrophage/microglia responses associated with Alzheimer's disease and other disorders of lipid-rich tissues
- 2023
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Ingår i: bioRxiv : the preprint server for biology. - : Cold Spring Harbor Laboratory.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundGenetic and experimental evidence strongly implicates myeloid cells in the etiology of AD and suggests that AD-associated alleles and genes may modulate disease risk by altering the transcriptional and cellular responses of macrophages (like microglia) to damage of lipid-rich tissues (like the brain). Specifically, recent single-cell/nucleus RNA sequencing (sc/nRNA-seq) studies identified a transcriptionally distinct state of subsets of macrophages in aging or degenerating brains (usually referred to as disease- associated microglia or DAM) and in other diseased lipid-rich tissues (e.g., obese adipose tissue, fatty liver, and atherosclerotic plaques). We collectively refer to these subpopulations as lipid-associated macrophages or LAMs. Importantly, this particular activation state is characterized by increased expression of genes involved in the phagocytic clearance of lipid-rich cellular debris (efferocytosis), including several AD risk genes.MethodsWe used sc/nRNA-seq data from human and mouse microglia from healthy and diseased brains and macrophages from other lipid-rich tissues to reconstruct gene regulatory networks and identify transcriptional regulators whose regulons are enriched for LAM response genes (LAM TFs) across species. We then used gene knock- down/knock-out strategies to validate some of these LAM TFs in human THP-1 macrophages and iPSC-derived microgliain vitro, as well as mouse microgliain vivo.ResultsWe nominate 11 strong candidate LAM TFs shared across human and mouse networks (BHLHE41,HIF1A,ID2,JUNB,MAF,MAFB,MEF2A,MEF2C,NACA, POU2F2andSPI1). We also demonstrate a strong enrichment of AD risk alleles in the cistrome ofBHLHE41(and its close homologBHLHE40), thus implicating its regulon in the modulation of disease susceptibility. Loss or reduction ofBHLHE40/41expression in human THP-1 macrophages and iPSC-derived microglia, as well as loss ofBhlhe40/41in mouse microglia led to increased expression of LAM response genes, specifically those involved in cholesterol clearance and lysosomal processing, with a concomitant increase in cholesterol efflux and storage, as well as lysosomal mass and degradative capacity.ConclusionsTaken together, this study nominates transcriptional regulators of the LAM response, experimentally validates BHLHE40/41 in human and mouse macrophages/microglia, and provides novel targets for therapeutic modulation of macrophage/microglia function in AD and other disorders of lipid-rich tissues.Graphical abstract
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- Rauschmeier, R, et al.
(författare)
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Bhlhe40 function in activated B and TFH cells restrains the GC reaction and prevents lymphomagenesis
- 2021
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Ingår i: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 219:2
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Tidskriftsartikel (refereegranskat)abstract
- The generation of high-affinity antibodies against pathogens and vaccines requires the germinal center (GC) reaction, which relies on a complex interplay between specialized effector B and CD4 T lymphocytes, the GC B cells and T follicular helper (TFH) cells. Intriguingly, several positive key regulators of the GC reaction are common for both cell types. Here, we report that the transcription factor Bhlhe40 is a crucial cell-intrinsic negative regulator affecting both the B and T cell sides of the GC reaction. In activated CD4 T cells, Bhlhe40 was required to restrain proliferation, thus limiting the number of TFH cells. In B cells, Bhlhe40 executed its function in the first days after immunization by selectively restricting the generation of the earliest GC B cells but not of early memory B cells or plasmablasts. Bhlhe40-deficient mice with progressing age succumbed to a B cell lymphoma characterized by the accumulation of monoclonal GC B-like cells and polyclonal TFH cells in various tissues.
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