CXCL13 is a plasma biomarker of germinal center activity Havenar-Daughton, Colin; Lindqvist, Madelene; Heit, Antje ...
Proceedings of the National Academy of Sciences - PNAS,
03/2016, Letnik:
113, Številka:
10
Journal Article
Recenzirano
Odprti dostop
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.
Passive administration of HIV neutralizing antibodies (nAbs) can protect macaques from hard-to-neutralize (tier 2) chimeric simian-human immunodeficiency virus (SHIV) challenge. However, conditions ...for nAb-mediated protection after vaccination have not been established. Here, we selected groups of 6 rhesus macaques with either high or low serum nAb titers from a total of 78 animals immunized with recombinant native-like (SOSIP) Env trimers. Repeat intrarectal challenge with homologous tier 2 SHIVBG505 led to rapid infection in unimmunized and low-titer animals. High-titer animals, however, demonstrated protection that was gradually lost as nAb titers waned over time. An autologous serum ID50 nAb titer of ∼1:500 afforded more than 90% protection from medium-dose SHIV infection. In contrast, antibody-dependent cellular cytotoxicity and T cell activity did not correlate with protection. Therefore, Env protein-based vaccination strategies can protect against hard-to-neutralize SHIV challenge in rhesus macaques by inducing tier 2 nAbs, provided appropriate neutralizing titers can be reached and maintained.
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•HIV Env trimer immunization protects from autologous tier 2 challenge in macaques•Neutralizing antibody (nAb) titers correlate with protection and peak viremia•T cell and ADCC functions do not correlate with protection•nAb titers of ∼1:500 (pseudovirus)/∼1:30 (live virus) required for ∼90% protection
Vaccine-induced immunity to HIV is a major research focus, but relevant correlates of protection remain controversial. Here, Pauthner et al. study protection from hard-to-neutralize SHIVBG505 challenge after immunization with native-like BG505 Envelope trimers in nonhuman primates and identify neutralizing antibodies, but not T cell or ADCC activity, as correlates of protection.
Elicitation of broadly neutralizing antibodies (bnAbs) is a primary HIV vaccine goal. Native-like trimers mimicking virion-associated spikes present nearly all bnAb epitopes and are therefore ...promising vaccine antigens. However, first generation native-like trimers expose epitopes for non-neutralizing antibodies (non-nAbs), which may hinder bnAb induction. We here employ computational and structure-guided design to develop improved native-like trimers that reduce exposure of non-nAb epitopes in the V3-loop and trimer base, minimize both CD4 reactivity and CD4-induced non-nAb epitope exposure, and increase thermal stability while maintaining bnAb antigenicity. In rabbit immunizations with native-like trimers of the 327c isolate, improved trimers suppress elicitation of V3-directed and tier-1 neutralizing antibodies and induce robust autologous tier-2 neutralization, unlike a first-generation trimer. The improved native-like trimers from diverse HIV isolates, and the design methods, have promise to assist in the development of a HIV vaccine.
Traditional vaccine development to prevent some of the worst current pandemic diseases has been unsuccessful so far. Germline-targeting immunogens have potential to prime protective antibodies (Abs) ...via more targeted immune responses. Success of germline-targeting vaccines in humans will depend on the composition of the human naive B cell repertoire, including the frequencies and affinities of epitope-specific B cells. However, the human naive B cell repertoire remains largely undefined. Assessment of antigen-specific human naive B cells among hundreds of millions of B cells from multiple donors may be used as pre-phase 1 ex vivo human testing to potentially forecast B cell and Ab responses to new vaccine designs. VRC01 is an HIV broadly neutralizing Ab (bnAb) against the envelope CD4-binding site (CD4bs). We characterized naive human B cells recognizing eOD-GT8, a germline-targeting HIV-1 vaccine candidate immunogen designed to prime VRC01-class Abs. Several distinct subclasses of VRC01-class naive B cells were identified, sharing sequence characteristics with inferred precursors of known bnAbs VRC01, VRC23, PCIN63, and N6. Multiple naive B cell clones exactly matched mature VRC01-class bnAb L-CDR3 sequences. Non-VRC01-class B cells were also characterized, revealing recurrent public light chain sequences. Unexpectedly, we also identified naive B cells related to the IOMA-class CD4bs bnAb. These different subclasses within the human repertoire had strong initial affinities (
) to the immunogen, up to 13 nM, and represent encouraging indications that multiple independent pathways may exist for vaccine-elicited VRC01-class bnAb development in most individuals. The frequencies of these distinct eOD-GT8 B cell specificities give insights into antigen-specific compositional features of the human naive B cell repertoire and provide actionable information for vaccine design and advancement.
Detection of Ag-specific CD4(+) T cells is central to the study of many human infectious diseases, vaccines, and autoimmune diseases. However, such cells are generally rare and heterogeneous in their ...cytokine profiles. Identification of Ag-specific germinal center (GC) T follicular helper (Tfh) cells by cytokine production has been particularly problematic. The function of a GC Tfh cell is to selectively help adjacent GC B cells via cognate interaction; thus, GC Tfh cells may be stingy cytokine producers, fundamentally different from Th1 or Th17 cells in the quantities of cytokines produced. Conventional identification of Ag-specific cells by intracellular cytokine staining relies on the ability of the CD4(+) T cell to generate substantial amounts of cytokine. To address this problem, we have developed a cytokine-independent activation-induced marker (AIM) methodology to identify Ag-specific GC Tfh cells in human lymphoid tissue. Whereas Group A Streptococcus-specific GC Tfh cells produced minimal detectable cytokines by intracellular cytokine staining, the AIM method identified 85-fold more Ag-specific GC Tfh cells. Intriguingly, these GC Tfh cells consistently expressed programmed death ligand 1 upon activation. AIM also detected non-Tfh cells in lymphoid tissue. As such, we applied AIM for identification of rare Ag-specific CD4(+) T cells in human peripheral blood. Dengue, tuberculosis, and pertussis vaccine-specific CD4(+) T cells were readily detectable by AIM. In summary, cytokine assays missed 98% of Ag-specific human GC Tfh cells, reflecting the biology of these cells, which could instead be sensitively identified by coexpression of TCR-dependent activation markers.
Generating tier 2 HIV-neutralizing antibody (nAb) responses by immunization remains a challenging problem, and the immunological barriers to induction of such responses with Env immunogens remain ...unclear. Here, some rhesus monkeys developed autologous tier 2 nAbs upon HIV Env trimer immunization (SOSIP.v5.2) whereas others did not. This was not because HIV Env trimers were immunologically silent because all monkeys made similar ELISA-binding antibody responses; the key difference was nAb versus non-nAb responses. We explored the immunological barriers to HIV nAb responses by combining a suite of techniques, including longitudinal lymph node fine needle aspirates. Unexpectedly, nAb development best correlated with booster immunization GC B cell magnitude and Tfh characteristics of the Env-specific CD4 T cells. Notably, these factors distinguished between successful and unsuccessful antibody responses because GC B cell frequencies and stoichiometry to GC Tfh cells correlated with nAb development, but did not correlate with total Env Ab binding titers.
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•Fine needle aspirates quantitatively monitor germinal center activity in lymph nodes•Neutralizing antibodies correlate with GC B cell magnitude, not ELISA Ab titers•Tfh cell quality is associated with vaccine-elicited HIV-neutralizing antibodies•LN FNA probing of GCs should be an immune correlate in HIV vaccine trials
This study explores the immunological process by which a protein vaccine elicits HIV-neutralizing antibodies. Using direct probing of lymph nodes, Havenar-Daughton et al. show that neutralizing antibody development correlates with germinal center B cell frequencies and Tfh cells and that those responses can be tracked by LN FNAs over time.
A range of current candidate AIDS vaccine regimens are focused on generating protective HIV-neutralizing Ab responses. Many of these efforts rely on the rhesus macaque animal model. Understanding how ...protective Ab responses develop and how to increase their efficacy are both major knowledge gaps. Germinal centers (GCs) are the engines of Ab affinity maturation. GC T follicular helper (Tfh) CD4 T cells are required for GCs. Studying vaccine-specific GC Tfh cells after protein immunizations has been challenging, as Ag-specific GC Tfh cells are difficult to identify by conventional intracellular cytokine staining. Cytokine production by GC Tfh cells may be intrinsically limited in comparison with other Th effector cells, as the biological role of a GC Tfh cell is to provide help to individual B cells within the GC, rather than secreting large amounts of cytokines bathing a tissue. To test this idea, we developed a cytokine-independent method to identify Ag-specific GC Tfh cells. RNA sequencing was performed using TCR-stimulated GC Tfh cells to identify candidate markers. Validation experiments determined CD25 (IL-2Rα) and OX40 to be highly upregulated activation-induced markers (AIM) on the surface of GC Tfh cells after stimulation. In comparison with intracellular cytokine staining, the AIM assay identified >10-fold more Ag-specific GC Tfh cells in HIV Env protein-immunized macaques (BG505 SOSIP). CD4 T cells in blood were also studied. In summary, AIM demonstrates that Ag-specific GC Tfh cells are intrinsically stingy producers of cytokines, which is likely an essential part of their biological function.
The first immunization in a protein prime-boost vaccination is likely to be critical for how the immune response unfolds. Using fine needle aspirates (FNAs) of draining lymph nodes (LNs), we tracked ...the kinetics of the primary immune response in rhesus monkeys immunized intramuscularly (IM) or subcutaneously (s.c.) with an eOD-GT8 60-mer nanoparticle immunogen to facilitate clinical trial design. Significant numbers of germinal center B (BGC) cells and antigen-specific CD4 T cells were detectable in the draining LN as early as 7 days post-immunization and peaked near day 21. Strikingly, s.c. immunization results in 10-fold larger antigen-specific BGC cell responses compared to IM immunization. Lymphatic drainage studies revealed that s.c. immunization resulted in faster and more consistent axillary LN drainage than IM immunization. These data indicate robust antigen-specific germinal center responses can occur rapidly to a single immunization with a nanoparticle immunogen and vaccine drainage substantially impacts immune responses in local LNs.
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•Rapid immunogen-specific lymph node responses detected at day 7 post-immunization•Lymph node immune response kinetics can be longitudinally tracked•Greater germinal center responses after subcutaneous versus intramuscular immunization•Immunization injection method substantially impacts immune responses in local LNs
The first immunization of protein prime-boost vaccination is likely critical but has been understudied in large animals and humans. Havenar-Daughton et al. use lymph node fine needle aspirates to determine primary germinal center response kinetics in rhesus monkeys immunized intramuscularly or subcutaneously with a clinical trial candidate nanoparticle immunogen.
Experiencing poverty increases vulnerability for dysregulated hypothalamic-pituitary-adrenal (HPA) axis functioning and compromises long-term health. Positive parenting buffers children from HPA axis ...reactivity, yet this has primarily been documented among families not experiencing poverty. We tested the theorized power of positive parenting in 124 parent-child dyads recruited from Early Head Start (Mage = 25.21 months) by examining child cortisol trajectories using five samples collected across a standardized stress paradigm. Piecewise latent growth models revealed that positive parenting buffered children's stress responses when controlling for time of day, last stress task completed, and demographics. Positive parenting also interacted with income such that positive parenting was especially protective for cortisol reactivity in families experiencing greater poverty. Findings suggest that positive parenting behaviors are important for protecting children in families experiencing low income from heightened or prolonged physiologic stress reactivity to an acute stressor.
Germinal centers (GC) are critically important for maturation of the antibody response and generation of memory B cells, processes that form the basis for long-term protection from pathogens. GCs ...only occur in lymphoid tissue, such as lymph nodes, and are not present in blood. Therefore, GC B cells and GC T follicular helper (TFH) cells are not well-studied in humans under normal healthy conditions, due to the limited availability of healthy lymph node samples. We used a minimally invasive, routine clinical procedure, lymph node fine needle aspirations (LN FNAs), to obtain LN cells from healthy human subjects. This study of 73 LNs demonstrates that human LN FNAs are a safe and feasible technique for immunological research, and suggests benchmarks for human GC biology under noninflammatory conditions. The findings indicate that assessment of the GC response via LN FNAs will have application to the study of human vaccination, allergy, and autoimmune disease.
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