Regulated somatic hypermutation enhances antibody affinity maturation
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ABSTRACT:
PROVIDER: PRJNA1211152 | ENA |
REPOSITORIES: ENA
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Project description:Germinal centers (GCs) are microenvironments where B cells undergo affinity maturation through somatic hypermutation (SHM) and selection by T follicular helper (TFH) cells. While SHM introduces mutations at a fixed rate (~1x10⁻³ per base pair per division), most mutations are deleterious, particularly in high-affinity B cells undergoing many divisions. This study tests a theoretical model suggesting that high-affinity B cells optimize maturation by dividing more but mutating less per division. Data from mice immunized with SARS-CoV-2 or a model antigen support the model, showing that high-affinity B cells shorten their G0/G1 phases and reduce mutation rates, safeguarding their lineages and improving affinity maturation outcomes.
2025-01-27 | GSE287123 | GEO
Project description:B cell somatic hypermutation (SHM) and selection in germinal center (GC)s enhance antibody affinity to antigen. Conventional understanding holds that SHM enhances pre-existing antibody specificities, limiting the scope of SHM-based antibody evolution to those established in the primary repertoire through V(D)J recombination. By tracking pre-defined non-specific B cells, we observed consistent SHM in non-cognate antibody genes after immunization in settings of diverse, polyclonal B and T cells. Removing B cell competition enabled these non-specific yet somatically mutating antibodies to develop entirely new specificities to diverse antigens. Our findings introduce an updated model, where SHM drives antibody diversification without requiring initial antigen specificity. This reveals that B cell competition, rather than a necessity for specific affinity, limits the emergence of new affinities (termed here as affinity birth) by SHM and highlights the mammalian adaptive immune system’s capacity to explore antibody-antigen interactions beyond the epitopes targeted by the V(D)J-dependent primary antibody repertoire.
2024-12-04 | GSE283094 | GEO
Project description:Anitbody affinity birth through somatic hypermutation
| PRJNA1191854 | ENA
Project description:Somatic hypermutation and clonal selection lead to B cells expressing high-affinity antibodies. Here we show that somatic mutations not only play a critical role in antigen binding, they also affect the thermodynamic stability of the antibody molecule. Somatic mutations directly involved in antigen recognition by antibody 93F3, which binds a relatively small hapten, reduce the melting temperature compared with its germ-line precursor by up to 9 °C. The destabilizing effects of these mutations are compensated by additional somatic mutations located on surface loops distal to the antigen binding site. Similarly, somatic mutations enhance both the affinity and thermodynamic stability of antibody OKT3, which binds the large protein antigen CD3. Analysis of the crystal structures of 93F3 and OKT3 indicates that these somatic mutations modulate antibody stability primarily through the interface of the heavy and light chain variable domains. The historical view of antibody maturation has been that somatic hypermutation and subsequent clonal selection increase antigen-antibody specificity and binding energy. Our results suggest that this process also optimizes protein stability, and that many peripheral mutations that were considered to be neutral are required to offset deleterious effects of mutations that increase affinity. Thus, the immunological evolution of antibodies recapitulates on a much shorter timescale the natural evolution of enzymes in which function and thermodynamic stability are simultaneously enhanced through mutation and selection.
| S-EPMC3600448 | biostudies-literature
Project description:Affinity maturation of antibody against membrane-bound GPCR molecules
| PRJEB32492 | ENA
Project description:Germinal center (GC) B cells undergo cycles of somatic hypermutation and selection, thus increasing their antibody affinity before differentiating into plasma or memory cells. The mechanisms dictating the dynamics of GC B cells are incompletely understood. We show that ablating the Protein arginine methyltransferase 1 (PRMT1) in GC B cells reduces antibody affinity maturation by impairing GC dynamics, as shown by compromised GC expansion, accumulation of CXCR4- B cells, and increased memory B cell differentiation, partly, at the expense of plasma cell production. Furthermore, PRMT1 distinguishes the subset of GC B cells that reenter the GC dark zone after positive selection, in which it is upregulated by Myc in conjunction with mTORC signaling. PRMT1 opposes mature B cell differentiation, as shown by higher plasma cell differentiation of PRMT1-deficient B cells activated ex vivo, a function co-opted by B cell lymphoma cells, in which PRMT1 expression also correlates with Myc expression and outcome.
2023-04-27 | GSE189276 | GEO
Project description:Increased antibody affinity over time after vaccination is a prototypical feature of immune responses. Recent studies have shown that a diverse collection of B cells, producing antibodies with a wide spectrum of different affinities, are selected into the plasma cell (PC) pathway. How affinity-permissive selection enables PC affinity maturation remains unknown. Here we report that PC precursors (prePC) expressing high affinity antibodies received higher levels of T follicular helper (Tfh) and divided at higher rates than their lower affinity counterparts once they left the GC. Thus, differential cell division by selected prePCs accounted for how diverse precursors developed into a PC compartment that mediated serological affinity maturation.
2024-12-19 | GSE282284 | GEO
Project description:Influenza virus vaccination remains the best strategy for combating virus infection, but vaccine efficacy is highly variable. An ideal influenza vaccine must have two attributes: one, it should be capable of inducing broadly cross-reactive antibodies that can neutralize diverse influenza virus strains; and two, it must induce long-lived antibody responses to maintain protective immunity for extended periods. Germinal center (GC) reactions are the major sites where diversification and affinity maturation of B cells occur. Whether a persistent GC response could expand the breadth of responding B cell clones following influenza vaccination in humans remains unknown. Here, we show that influenza virus vaccine-specific GC B cells persist for over nine weeks post vaccination in two out of seven individuals. These late vaccine-specific GC B cells exhibited increased somatic hypermutation (SHM) of their B cell receptors compared to early vaccine-specific GC B cells. After re-immunization with seasonal influenza virus vaccine, individuals with a persistent GC engaged vaccine-specific plasmablasts (PBs) with higher SHM frequency. Tracking the maturation of three clonally related GC B cell lineages over time revealed that late GC B cells had receptors that recognized and neutralized heterologous influenza virus strains. Thus, SHM induced by persistent GCs can broaden the antibody response to influenza virus vaccination. This indicates that seasonal influenza virus vaccination in humans can induce broadly cross-reactive antibodies that target diverse influenza virus strains.
2024-06-13 | GSE211869 | GEO
Project description:Influenza virus vaccination remains the best strategy for combating virus infection, but vaccine efficacy is highly variable. An ideal influenza vaccine must have two attributes: one, it should be capable of inducing broadly cross-reactive antibodies that can neutralize diverse influenza virus strains; and two, it must induce long-lived antibody responses to maintain protective immunity for extended periods. Germinal center (GC) reactions are the major sites where diversification and affinity maturation of B cells occur. Whether a persistent GC response could expand the breadth of responding B cell clones following influenza vaccination in humans remains unknown. Here, we show that influenza virus vaccine-specific GC B cells persist for over nine weeks post vaccination in two out of seven individuals. These late vaccine-specific GC B cells exhibited increased somatic hypermutation (SHM) of their B cell receptors compared to early vaccine-specific GC B cells. After re-immunization with seasonal influenza virus vaccine, individuals with a persistent GC engaged vaccine-specific plasmablasts (PBs) with higher SHM frequency. Tracking the maturation of three clonally related GC B cell lineages over time revealed that late GC B cells had receptors that recognized and neutralized heterologous influenza virus strains. Thus, SHM induced by persistent GCs can broaden the antibody response to influenza virus vaccination. This indicates that seasonal influenza virus vaccination in humans can induce broadly cross-reactive antibodies that target diverse influenza virus strains.
2024-06-13 | GSE211865 | GEO
Project description:Affinity maturation of antibody responses is mediated by differential plasma cell proliferation
| PRJNA1188058 | ENA