Clonal selection in the germinal centre by regulated proliferation and hypermutation

Gitlin, Alexander D.; Shulman, Ziv; Nussenzweig, Michel C.

doi:10.1038/nature13300

Cited by 497 publications

(622 citation statements)

References 31 publications

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“…For example, a memory B cell might have come from a clone that expressed lower levels of AID or some of its associated proteins at the time when mutations were occurring, and then it would have fewer mutated V regions. Distinguishing between these two different models is especially difficult because it has not been possible to establish how many mutations occur during each cell division (25,(53)(54)(55) or to find convincing experimental evidence that AID is processive in vivo (53). It is even possible that AID does not always behave the same way on each V region at each cell division.…”

Section: Discussionmentioning

confidence: 99%

“…For example, AID might occasionally increase its efficiency, pause for a longer period, or remain associated with the transcriptional apparatus to generate multiple mutations during a single cell cycle to mutate more distant sites. This could occur, for example, in B cells that go through multiple sequential divisions in the dark zone germinal center and that undergo more mutations than the majority of the B cells that shuttle back forth at every cell division between the dark and the light zone (25).…”

Section: Discussionmentioning

confidence: 99%

“…Transcription-associated proteins and RNA processing factors also participate in the AID mutational process and, in some cases, physically interact with AID (14)(15)(16)(17). In addition, other transacting proteins (18,19), including chaperones (20), chromatin modifiers and remodelers (21)(22)(23), cell cycle regulators (24), developmental factors (25), and cisacting sequences (26,27), appear to affect mutations. However, all of these factors also have pleiotropic effects on non-Ig genes in B cells, so they do not appear to be solely responsible for the targeting of AID-induced mutations to the Ig V. Because many nonIg genes are also highly transcribed in activated B cells and AID appears to occupy many sites in such cells (28,29) and can also cause mutations in non-B cells, it is important to understand why the very high rate of mutation in the SHM is not seen in other highly expressed genes in B cells.…”

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confidence: 99%

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Overlapping hotspots in CDRs are critical sites for V region diversification

Wei

Chahwan

Wang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Activation-induced deaminase (AID) mediates the somatic hypermutation (SHM) of Ig variable (V) regions that is required for the affinity maturation of the antibody response. An intensive analysis of a published database of somatic hypermutations that arose in the IGHV3-23*01 human V region expressed in vivo by human memory B cells revealed that the focus of mutations in complementary determining region (CDR)1 and CDR2 coincided with a combination of overlapping AGCT hotspots, the absence of AID cold spots, and an abundance of polymerase eta hotspots. If the overlapping hotspots in the CDR1 or CDR2 did not undergo mutation, the frequency of mutations throughout the V region was reduced. To model this result, we examined the mutation of the human IGHV3-23*01 biochemically and in the endogenous heavy chain locus of Ramos B cells. Deep sequencing revealed that IGHV3-23*01 in Ramos cells accumulates AID-induced mutations primarily in the AGCT in CDR2, which was also the most frequent site of mutation in vivo. Replacing the overlapping hotspots in CDR1 and CDR2 with neutral or cold motifs resulted in a reduction in mutations within the modified motifs and, to some degree, throughout the V region. In addition, some of the overlapping hotspots in the CDRs were at sites in which replacement mutations could change the structure of the CDR loops. Our analysis suggests that the local sequence environment of the V region, and especially of the CDR1 and CDR2, is highly evolved to recruit mutations to key residues in the CDRs of the IgV region.A fter an encounter with antigen and subsequent migration into the germinal centers of the secondary lymphoid organs, B cells undergo a regulated cascade of mutational events that occur at a very high frequency and are largely restricted to the variable (V) and switch (S) regions of the Ig heavy chain locus and the V region of the light chain locus. These mutagenic events are responsible for the somatic hypermutation (SHM) of the V regions and the class switch recombination of the constant (C) regions that are required for protective antibodies (1, 2). Both SHM and class switch recombination are initiated by activationinduced deaminase (AID) that preferentially deaminates the dC residues in WRC (W = A/T, R = A/G) hotspot motifs at frequencies 2-10-fold higher than SYC (S = G/C; Y = C/T) cold spots (3-7). During V region SHM, the resulting dU:G mismatch can then be replicated during S-phase to produce transition mutations, be processed by uracil-DNA glycosylase 2 and apurinic/ apyrimidinic endonucleases through the base excision repair pathway to produce both transitions and transversions (8-10), or be recognized by MutS homolog (MSH)2/MSH6 of the mismatch repair (MMR) complex that recruits the low-fidelity polymerase eta (Polη) to generate additional mutations at neighboring A:T residues (11).The specificity of AID targeting to the Ig gene has been under intense investigation. Studies have shown that AID deamination and mutagenesis targets single-stranded DNA substrates generated during ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Overlapping hotspots in CDRs are critical sites for V region diversification

Wei

Chahwan

Wang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…B cells then migrate into the dark zones where they proliferate and undergo somatic hypermutation, resulting in antibody diversification (reviewed in 106). The number of divisions B cells undergo in the dark zone and the speed of cycling are determined by the help provided by Tfh cells 107, 108. B cells then exit into the light zones, where those cells expressing surface Ig of sufficiently high affinity to enable them to efficiently acquire antigen from FDCs undergo further interactions with Tfh cells and receive signals, in particular via CD40, that enable continued survival.…”

Section: T Follicular Helper Cells and Their Role In Bnab Inductionmentioning

confidence: 99%

Immunologic characteristics of HIV‐infected individuals who make broadly neutralizing antibodies

Borrow

Moody

2017

Immunological Reviews

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SummaryInduction of broadly neutralizing antibodies (bnAbs) capable of inhibiting infection with diverse variants of human immunodeficiency virus type 1 (HIV‐1) is a key, as‐yet‐unachieved goal of prophylactic HIV‐1 vaccine strategies. However, some HIV‐infected individuals develop bnAbs after approximately 2‐4 years of infection, enabling analysis of features of these antibodies and the immunological environment that enables their induction. Distinct subsets of CD4+ T cells play opposing roles in the regulation of humoral responses: T follicular helper (Tfh) cells support germinal center formation and provide help for affinity maturation and the development of memory B cells and plasma cells, while regulatory CD4+ (Treg) cells including T follicular regulatory (Tfr) cells inhibit the germinal center reaction to limit autoantibody production. BnAbs exhibit high somatic mutation frequencies, long third heavy‐chain complementarity determining regions, and/or autoreactivity, suggesting that bnAb generation is likely to be highly dependent on the activity of CD4+ Tfh cells, and may be constrained by host tolerance controls. This review discusses what is known about the immunological environment during HIV‐1 infection, in particular alterations in CD4+ Tfh, Treg, and Tfr populations and autoantibody generation, and how this is related to bnAb development, and considers the implications for HIV‐1 vaccine design.

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“…GC Tfh cells are both required and limiting for the GC reaction (9,10). GC Tfh cells control the number of GC B-cell divisions and therefore, the amount of SHM by individual GC B-cell clones (11). Currently, the preferred means of quantifying the GC response is the cellular enumeration and analysis of GC Tfh and GC B cells (8).…”

mentioning

confidence: 99%

CXCL13 is a plasma biomarker of germinal center activity

Havenar-Daughton

Lindqvist

Heit

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

291

311

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Significantly higher levels of plasma CXCL13 [chemokine (C-X-C motif) ligand 13] were associated with the generation of broadly neutralizing antibodies (bnAbs) against HIV in a large longitudinal cohort of HIV-infected individuals. Germinal centers (GCs) perform the remarkable task of optimizing B-cell Ab responses. GCs are required for almost all B-cell receptor affinity maturation and will be a critical parameter to monitor if HIV bnAbs are to be induced by vaccination. However, lymphoid tissue is rarely available from immunized humans, making the monitoring of GC activity by direct assessment of GC B cells and germinal center CD4 + T follicular helper (GC Tfh) cells problematic. The CXCL13-CXCR5 [chemokine (C-X-C motif) receptor 5] chemokine axis plays a central role in organizing both B-cell follicles and GCs. Because GC Tfh cells can produce CXCL13, we explored the potential use of CXCL13 as a blood biomarker to indicate GC activity. In a series of studies, we found that plasma CXCL13 levels correlated with GC activity in draining lymph nodes of immunized mice, immunized macaques, and HIV-infected humans. Furthermore, plasma CXCL13 levels in immunized humans correlated with the magnitude of Ab responses and the frequency of ICOS + (inducible T-cell costimulator) Tfh-like cells in blood. Together, these findings support the potential use of CXCL13 as a plasma biomarker of GC activity in human vaccine trials and other clinical settings.T he germinal center (GC) reaction is a critical immunological process that occurs in draining lymph nodes after immunization (1). The GC response consists of antigen-specific B cells undergoing affinity maturation through a process of somatic hypermutation (SHM) of the B-cell receptor. SHM is necessary for producing high-affinity Ab responses after immunizations and infections. Influenza neutralizing Abs have substantial SHM. Particularly high levels of SHM, 15-30% amino acid mutation (2, 3), are present and necessary for broad Ab neutralization of diverse HIV strains (4, 5). Therefore, as candidate influenza and HIV vaccines are evaluated for the ability to induce broadly neutralizing antibodies (bnAbs), the quantitation and functional characterization of GC responses will be a key parameter for study. Serological analysis of vaccine-specific Ab titers provides important information, but those data are limited. Serological outcomes are measured at time points long after initial immunizations. Neutralizing Ab responses are commonly only measurable after multiple boosts. Those outcomes likely depend on GC activity and affinity maturation at much earlier time points. Several state of the art HIV vaccine strategies rely on long, multistage immunization protocols (6, 7). With bnAb responses as the goal, means of early analysis of the immune response will be essential to understand and improve on vaccination schemes that may end in failure or only partial success. One critical parameter to assess will be the ability of each immunization to generate GC responses.Central to the GC re...

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Clonal selection in the germinal centre by regulated proliferation and hypermutation

Cited by 497 publications

References 31 publications

Overlapping hotspots in CDRs are critical sites for V region diversification

Overlapping hotspots in CDRs are critical sites for V region diversification

Immunologic characteristics of HIV‐infected individuals who make broadly neutralizing antibodies

CXCL13 is a plasma biomarker of germinal center activity

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