| 1. |
- Aranburu, Alaitz, et al.
(författare)
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Age-associatedBcells expanded in autoimmune mice are memory cells sharing H-CDR3-selected repertoires
- 2018
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 48:3, s. 509-521
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Tidskriftsartikel (refereegranskat)abstract
- Age-associated Bcells (ABCs) represent a distinct cell population expressing low levels of CD21 (CD21 −/low ). The Ig repertoire expressed by ABCs in aged mice is diverse and exhib its signs of somatic hypermutation (SHM). A CD21 −/low B-cell population is expanded in autoimmune diseases, e.g. systemic lupus erythematosus, as well as in lupus-prone NZB/W mice and in mice lacking a pre-Bcell receptor (SLC −/− ). However, the nature of the CD21 −/low Bcells (hereafter ABCs) in autoimmunity is not well understood. Here we show that in young SLC −/− mice, the vast majority of the ABCs express memory B-cell (MBC) markers in contrast to wild-type controls. A similar population is present in lupus-prone MRL mice before and at disease onset. In SLC −/− mice, a majority of the ABCs are IgM + , their V H genes have undergone SHM, show clonal diversification and clonal restriction at the H-CDR3 level. ABC hybridomas, established from SLC −/− mice, secrete typical lupus autoantibodies, e.g. anti-Smith antigen, and some of those that bind to DNA comprise a H-CDR3 that is identical to previously described IgM anti-DNA antibodies from lupus-prone mice. Together, these results reveal that ABCs in autoimmune mice are comprised of autoreactive MBCs expressing highly restricted H-CDR3 repertoires.
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| 2. |
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| 3. |
- Aranburu, Alaitz, et al.
(författare)
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Clonal relationships of memory B cell subsets in autoimmune mice
- 2023
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Immunological memory protects our body from re-infection and it is composed of a cellular and a humoral arm. The B-cell branch with its memory B cells (MBCs), plasma cells and antibodies, formed either in a germinal centre (GC) -dependent or -independent manner, ensure that we can rapidly mount a recall immune response. Previous work in immunised wildtype (WT) mice have identified several subsets of MBCs whereas less is known under autoimmune conditions. Here, we have investigated the heterogeneity of the MBC compartment in autoimmune mouse models and examined the clonal relationships between MBC subsets and GC B cells in one of the models. We demonstrate the presence of at least four different MBC subsets based on their differential expression pattern of CD73, CD80 and PD-L2 in surrogate light chain-deficient (SLC-/-), MRL+/+ and MRLlpr/lpr mice, where most of the MBCs express IgM. Likewise, four MBC subsets could be identified in WT immunised mice. In SLC-/- mice, high-throughput sequencing of Ig heavy chains demonstrates that the two CD73-positive subsets are generally more mutated. Lineage tree analyses on expanded clones show overlaps between all MBC subsets and GC B cells primarily in the IgM sequences. Moreover, each of the three IgM MBC subsets could be found both as ancestor and progeny to GC B cells. This was also observed in the IgG sequences except for the CD73-negative subset. Thus, our findings demonstrate that several MBC subsets are present in autoimmune and WT mice. In SLC-/- mice, these MBC subsets are clonally related to each other and to GC B cells. Our results also indicate that different MBC subsets can seed the GC reaction.
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| 4. |
- Aranburu, Alaitz
(författare)
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Studies of penta-decameric binding proteins: AP-4 and CBF-A
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Each immunoglobulin (Ig) V gene segment contains an upstream promoter region. The octamer element and the TATA box are the only elements that are conserved in all Ig promoters. The presence of the octamer element is necessary, but not sufficient to support high levels of transcription. Therefore, the activity of other co-stimulatory elements is required. This investigation has focused on the study of one such regulatory region: the penta-decameric (pd) element. The pd element is an integral part of the SP6 V-kappa promoter and shows functional synergism with the octamer element at the late stages in B cell differentiation. The pd element is comprised of an E2A type of E-box (5’-CAGCTG-3-) and an AT-rich region. Previous work had identified CArG box-binding factor-A (CBF-A) as the protein interacting with the AT-rich moiety. However, the ligand for the E-box was an unknown. Our work has now identified the bHLH-Zip protein AP-4 as the E-box binding factor. In addition, AP-4 has been found to bind to the second E-box (5’-CAGCTG-3’) found 3’ from the octamer site. E-boxes are conserved within human V-kappa promoter subgroups I, III, IV, V and VII, and related families, hence reinforcing the idea that the natural ligand for Ig-kappa promoter E-boxes is AP-4. Lastly, we pursued the study of CBF-A by searching for interacting partners by using a yeast Two-Hybrid screen. We have now characterised two important proteins interacting with CBF-A, the nucleolar phosphoprotein nucleophosmin(NPM/B23) and hnRNP H. Furthermore, CBF-A shows selectivity in its interactions, since CBF-A/NPM complexes are detected in the nucleus only, as opposed to the cytoplasmic only CBF-A/hnRNP H heterotypic complexes. Interestingly, we have shown that CBF-A undergoes self-oligomerisation in both the nuclear and cytoplasmic compartments. In addition, we have evidence to suggest that CBF-A might be shuttling between the nucleus and the cytoplasm. Specifically, we show that mitogenic stimulation of resting B cells promotes CBF-A accumulation in the nucleus. We have mapped the region responsible for the import/export activity of CBF-A to the most carboxyl-terminal 13 amino acid residues.
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| 5. |
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| 6. |
- Camponeschi, Alessandro, et al.
(författare)
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Dissecting Integrin Expression and Function on Memory B Cells in Mice and Humans in Autoimmunity.
- 2019
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Ingår i: Frontiers in immunology. - : Frontiers Media SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Immunological memory ensures life-long protection against previously encountered pathogens, and in mice and humans the spleen is an important reservoir for long-lived memory B cells (MBCs). It is well-established that integrins play several crucial roles in lymphocyte survival and trafficking, but their involvement in the retention of MBCs in secondary lymphoid organs, and differences between B cell subsets in their adhesion capacity to ICAM-1 and/or VCAM-1 have not yet been confirmed. Here, we use an autoimmune mouse model, where MBCs are abundant, to show that the highest levels of LFA-1 and VLA-4 amongst B cells are found on MBCs. In vivo blockade of VLA-4 alone or in combination with LFA-1, but not LFA-1 alone, causes a release of MBCs from the spleen into the blood stream. In humans, we find that in peripheral blood, spleens, and tonsils from healthy donors the highest expression levels of the integrins LFA-1 and VLA-4 are also found on MBCs. Consistent with this, we found MBCs to have a higher capacity to adhere to ICAM-1 and VCAM-1 than naïve B cells. In patients with the autoimmune disease rheumatoid arthritis, it is the MBCs that have the highest levels of LFA-1 and VLA-4; moreover, compared with healthy donors, naïve B and MBCs of patients receiving anti-TNF medication have enhanced levels of the active form of LFA-1. Commensurate levels of the active αL subunit can be induced on B cells from healthy donors by exposure to the integrin ligands. Thus, our findings establish the selective use of the integrins LFA-1 and VLA-4 in the localization and adhesion of MBCs in both mice and humans.
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| 7. |
- Camponeschi, Alessandro, et al.
(författare)
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Human CD38 regulates B cell antigen receptor dynamic organization in normal and malignant B cells.
- 2022
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Ingår i: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 219:9
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Tidskriftsartikel (refereegranskat)abstract
- CD38 is a multifunctional protein expressed on the surface of B cells in healthy individuals but also in B cell malignancies. Previous studies have suggested a connection between CD38 and components of the IgM class B cell antigen receptor (IgM-BCR) and its coreceptor complex. Here, we provide evidence that CD38 is closely associated with CD19 in resting B cells and with the IgM-BCR upon engagement. We show that targeting CD38 with an antibody, or removing this molecule with CRISPR/Cas9, inhibits the association of CD19 with the IgM-BCR, impairing BCR signaling in normal and malignant B cells. Together, our data suggest that CD38 is a new member of the BCR coreceptor complex, where it exerts a modulatory effect on B cell activation upon antigen recognition by regulating CD19. Our study also reveals a new mechanism where α-CD38 antibodies could be a valuable option in therapeutic approaches to B cell malignancies driven by aberrant BCR signaling.
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| 8. |
- Grimsholm, O., et al.
(författare)
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The Interplay between CD27(dull) and CD27(brig)(ht) B Cells Ensures the Flexibility, Stability, and Resilience of Human B Cell Memory
- 2020
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 30:9
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Tidskriftsartikel (refereegranskat)abstract
- Memory B cells (MBCs) epitomize the adaptation of the immune system to the environment. We identify two MBC subsets in peripheral blood, CD27(dull) and CD27(bright) MBCs, whose frequency changes with age. Heavy chain variable region (VH) usage, somatic mutation frequency replacement-to-silent ratio, and CDR3 property changes, reflecting consecutive selection of highly antigen-specific, low cross-reactive antibody variants, all demonstrate that CD27(du)(ll) and CD27(bright) MBCs represent sequential MBC developmental stages, and stringent antigen-driven pressure selects CD27(du)(ll) into the CD27(bright) MBC pool. Dynamics of human MBCs are exploited in pregnancy, when 50% of maternal MBCs are lost and CD27(du)(ll) MBCs transit to the more differentiated CD27 bright stage. In the postpartum period, the maternal MBC pool is replenished by the expansion of persistent CD27(du)(ll) clones. Thus, the stability and flexibility of human B cell memory is ensured by CD27(du)(ll) MBCs that expand and differentiate in response to change.
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| 9. |
- McGrath, Sarah, et al.
(författare)
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Correlation of Professional Antigen-Presenting Tbet+CD11c+ B Cells With Bone Destruction in Untreated Rheumatoid Arthritis
- 2024
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Ingår i: Arthritis & Rheumatology. - : John Wiley & Sons. - 2326-5191 .- 2326-5205.
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Subsets of CD21−/low memory B cells (MBCs), including double-negative (DN, CD27−IgD−) and Tbet+CD11c+ cells, are expanded in chronic inflammatory diseases. In rheumatoid arthritis (RA), CD21−/low MBCs correlate with joint destruction. However, whether this is due to the Tbet+CD11c+ subset, its function and pathogenic contribution to RA are unknown. This study aims to investigate the association between CD21−/lowTbet+CD11c+ MBCs and joint destruction as well as other clinical parameters and to elucidate their functional properties in patients with untreated RA (uRA). Methods: Clinical observations were combined with flow cytometry (n = 36) and single-cell RNA sequencing (scRNA-seq) and V(D)J sequencing (n = 4) of peripheral blood (PB) MBCs from patients with uRA. The transcriptome of circulating Tbet+CD11c+ MBCs was compared with scRNA-seq data of synovial B cells. In vitro coculture of Tbet+CD11c+ B cells with T cells was used to assess costimulatory capacity. Results: CD21−/lowTbet+CD11c+ MBCs in PB correlated with bone destruction but no other clinical parameters analyzed. The Tbet+CD11c+ MBCs have undergone clonal expansion and express somatically mutated V genes. Gene expression analysis of these cells identified a unique signature of more than 150 up-regulated genes associated with antigen presentation functions, including B cell receptor activation and clathrin-mediated antigen internalization; regulation of actin filaments, endosomes, and lysosomes; antigen processing, loading, presentation, and costimulation; a transcriptome mirrored in their synovial tissue counterparts. In vitro, Tbet+CD11c+ B cells induced retinoic acid receptor–related orphan nuclear receptor γT expression in CD4+ T cells, thereby polarizing to Th17 cells, a T cell subset critical for osteoclastogenesis and associated with bone destruction. Conclusion: This study suggests that Tbet+CD11c+ MBCs contribute to the pathogenesis of RA by promoting bone destruction through antigen presentation, T cell activation, and Th17 polarization. (Figure presented.).
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| 10. |
- Minafo, Y. A., et al.
(författare)
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A stereotyped light chain may shape virus-specific B-cell receptors in HCV-dependent lymphoproliferative disorders
- 2020
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Ingår i: Genes and Immunity. - : Springer Science and Business Media LLC. - 1466-4879 .- 1476-5470. ; 21:131-135
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Tidskriftsartikel (refereegranskat)abstract
- Hepatitis C virus (HCV) causes B-cell lymphoproliferative disorders (LPDs) expressing stereotyped B-cell receptors (BCRs) endowed with rheumatoid factor (RF) activity and putatively recognizing the HCV E2 protein. To further untangle the shaping and function of these BCRs, we analyzed immunoglobulin gene rearrangements of monoclonal B cells from 13 patients with HCV-associated LPDs and correlated their features with the clinical outcomes of antiviral therapy. While only two patients shared a stereotyped heavy-chain complementarity determining region 3 (CDR3) sequence, two kappa chain CDR3 stereotyped sequences accounted for 77% of BCRs. Light chains were enriched in sequences homologous to anti-HCV E2 antibodies compared with heavy chains (7/13 vs. 0/13; p = 0.005). Anti-HCV E2 homology was uniquely associated (7/7 vs. 0/6; p = 0.0006) with a stereotyped CDR3 sequence encoded by IGKV3-20/3D-20 gene(s) accounting for 54% of BCRs. An IGKV3-15/IGKJ1-encoded stereotyped sequence homologous to WA RF accounted for 23% of BCRs. LPDs expressing KCDR3s homologous to anti-HCV E2 antibodies responded more frequently to the eradication of HCV by antiviral therapy (6/6 vs. 1/6; p = 0.015). These findings, although limited by the small sample size, suggest that a stereotyped KCDR3 may predominantly shape anti-HCV specificity of BCRs, possibly providing a signature that may help identifying bona fide HCV-dependent LPDs.
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