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1.
Nat Immunol ; 25(6): 1083-1096, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38816616

RESUMO

Current prophylactic human immunodeficiency virus 1 (HIV-1) vaccine research aims to elicit broadly neutralizing antibodies (bnAbs). Membrane-proximal external region (MPER)-targeting bnAbs, such as 10E8, provide exceptionally broad neutralization, but some are autoreactive. Here, we generated humanized B cell antigen receptor knock-in mouse models to test whether a series of germline-targeting immunogens could drive MPER-specific precursors toward bnAbs. We found that recruitment of 10E8 precursors to germinal centers (GCs) required a minimum affinity for germline-targeting immunogens, but the GC residency of MPER precursors was brief due to displacement by higher-affinity endogenous B cell competitors. Higher-affinity germline-targeting immunogens extended the GC residency of MPER precursors, but robust long-term GC residency and maturation were only observed for MPER-HuGL18, an MPER precursor clonotype able to close the affinity gap with endogenous B cell competitors in the GC. Thus, germline-targeting immunogens could induce MPER-targeting antibodies, and B cell residency in the GC may be regulated by a precursor-competitor affinity gap.


Assuntos
Afinidade de Anticorpos , Linfócitos B , Centro Germinativo , Anticorpos Anti-HIV , HIV-1 , Centro Germinativo/imunologia , Animais , Camundongos , Humanos , Linfócitos B/imunologia , HIV-1/imunologia , Anticorpos Anti-HIV/imunologia , Afinidade de Anticorpos/imunologia , Anticorpos Neutralizantes/imunologia , Infecções por HIV/imunologia , Vacinas contra a AIDS/imunologia , Receptores de Antígenos de Linfócitos B/metabolismo , Receptores de Antígenos de Linfócitos B/imunologia , Técnicas de Introdução de Genes , Camundongos Transgênicos , Anticorpos Amplamente Neutralizantes/imunologia , Camundongos Endogâmicos C57BL
2.
Nat Immunol ; 25(6): 1073-1082, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38816615

RESUMO

A key barrier to the development of vaccines that induce broadly neutralizing antibodies (bnAbs) against human immunodeficiency virus (HIV) and other viruses of high antigenic diversity is the design of priming immunogens that induce rare bnAb-precursor B cells. The high neutralization breadth of the HIV bnAb 10E8 makes elicitation of 10E8-class bnAbs desirable; however, the recessed epitope within gp41 makes envelope trimers poor priming immunogens and requires that 10E8-class bnAbs possess a long heavy chain complementarity determining region 3 (HCDR3) with a specific binding motif. We developed germline-targeting epitope scaffolds with affinity for 10E8-class precursors and engineered nanoparticles for multivalent display. Scaffolds exhibited epitope structural mimicry and bound bnAb-precursor human naive B cells in ex vivo screens, protein nanoparticles induced bnAb-precursor responses in stringent mouse models and rhesus macaques, and mRNA-encoded nanoparticles triggered similar responses in mice. Thus, germline-targeting epitope scaffold nanoparticles can elicit rare bnAb-precursor B cells with predefined binding specificities and HCDR3 features.


Assuntos
Vacinas contra a AIDS , Anticorpos Neutralizantes , Anticorpos Anti-HIV , Proteína gp41 do Envelope de HIV , Infecções por HIV , HIV-1 , Macaca mulatta , Animais , Humanos , Proteína gp41 do Envelope de HIV/imunologia , Anticorpos Anti-HIV/imunologia , Camundongos , Vacinas contra a AIDS/imunologia , Anticorpos Neutralizantes/imunologia , HIV-1/imunologia , Infecções por HIV/imunologia , Infecções por HIV/prevenção & controle , Infecções por HIV/virologia , Vacinação , Anticorpos Amplamente Neutralizantes/imunologia , Linfócitos B/imunologia , Nanopartículas/química , Feminino , Regiões Determinantes de Complementaridade/imunologia , Epitopos/imunologia
4.
Nature ; 609(7929): 998-1004, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36131022

RESUMO

Germinal centres are the engines of antibody evolution. Here, using human immunodeficiency virus (HIV) Env protein immunogen priming in rhesus monkeys followed by a long period without further immunization, we demonstrate germinal centre B (BGC) cells that last for at least 6 months. A 186-fold increase in BGC cells was present by week 10 compared with conventional immunization. Single-cell transcriptional profiling showed that both light- and dark-zone germinal centre states were sustained. Antibody somatic hypermutation of BGC cells continued to accumulate throughout the 29-week priming period, with evidence of selective pressure. Env-binding BGC cells were still 49-fold above baseline at 29 weeks, which suggests that they could remain active for even longer periods of time. High titres of HIV-neutralizing antibodies were generated after a single booster immunization. Fully glycosylated HIV trimer protein is a complex antigen, posing considerable immunodominance challenges for B cells1,2. Memory B cells generated under these long priming conditions had higher levels of antibody somatic hypermutation, and both memory B cells and antibodies were more likely to recognize non-immunodominant epitopes. Numerous BGC cell lineage phylogenies spanning more than the 6-month germinal centre period were identified, demonstrating continuous germinal centre activity and selection for at least 191 days with no further antigen exposure. A long-prime, slow-delivery (12 days) immunization approach holds promise for difficult vaccine targets and suggests that patience can have great value for tuning of germinal centres to maximize antibody responses.


Assuntos
Afinidade de Anticorpos , Linfócitos B , Movimento Celular , Células Clonais , Centro Germinativo , Anticorpos Anti-HIV , Imunização , Animais , Anticorpos Neutralizantes/genética , Anticorpos Neutralizantes/imunologia , Afinidade de Anticorpos/genética , Afinidade de Anticorpos/imunologia , Linfócitos B/citologia , Linfócitos B/imunologia , Células Clonais/citologia , Células Clonais/imunologia , Epitopos de Linfócito B/imunologia , Perfilação da Expressão Gênica , Centro Germinativo/citologia , Centro Germinativo/imunologia , Anticorpos Anti-HIV/genética , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Humanos , Imunização Secundária , Macaca mulatta/imunologia , Macaca mulatta/virologia , Células B de Memória/citologia , Células B de Memória/imunologia , Análise de Célula Única , Hipermutação Somática de Imunoglobulina/genética , Hipermutação Somática de Imunoglobulina/imunologia , Fatores de Tempo , Produtos do Gene env do Vírus da Imunodeficiência Humana/administração & dosagem , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia
6.
BMC Cancer ; 18(1): 69, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29320991

RESUMO

BACKGROUND: RHEB is a unique member of the RAS superfamily of small GTPases expressed in all tissues and conserved from yeast to humans. Early studies on RHEB indicated a possible RHEB-RAF interaction, but this has not been fully explored. Recent work on cancer genome databases has revealed a reoccurring mutation in RHEB at the Tyr35 position, and a recent study points to the oncogenic potential of this mutant that involves activation of RAF/MEK/ERK signaling. These developments prompted us to reassess the significance of RHEB effect on RAF, and to compare mutant and wild type RHEB. METHODS: To study RHEB-RAF interaction, and the effect of the Y35N mutation on this interaction, we used transfection, immunoprecipitation, and Western blotting techniques. We generated cell lines stably expressing RHEB WT, RHEB Y35N, and KRAS G12V, and monitored cellular transforming properties through cell proliferation, anchorage independent growth, cell cycle analysis, and foci formation assays. RESULTS: We observe a strong interaction between RHEB and BRAF, but not with CRAF. This interaction is dependent on an intact RHEB effector domain and RHEB-GTP loading status. RHEB overexpression decreases RAF activation of the RAF/MEK/ERK pathway and RHEB knockdown results in an increase in RAF/MEK/ERK activation. RHEB Y35N mutation has decreased interaction with BRAF, and RHEB Y35N cells exhibit greater BRAF/CRAF heterodimerization resulting in increased RAF/MEK/ERK signaling. This leads to cancer transformation of RHEB Y35N stably expressing cell lines, similar to KRAS G12 V expressing cell lines. CONCLUSIONS: RHEB interaction with BRAF is crucial for inhibiting RAF/MEK/ERK signaling. The RHEB Y35N mutant sustains RAF/MEK/ERK signaling due to a decreased interaction with BRAF, leading to increased BRAF/CRAF heterodimerization. RHEB Y35N expressing cells undergo cancer transformation due to decreased interaction between RHEB and BRAF resulting in overactive RAF/MEK/ERK signaling. Taken together with the previously established function of RHEB to activate mTORC1 signaling, it appears that RHEB performs a dual function; one is to suppress the RAF/MEK/ERK signaling and the other is to activate mTORC1 signaling.


Assuntos
Carcinogênese/genética , Neoplasias/genética , Proteínas Proto-Oncogênicas B-raf/genética , Proteína Enriquecida em Homólogo de Ras do Encéfalo/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Sistema de Sinalização das MAP Quinases/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Mutação , Neoplasias/patologia , Fosforilação , Inibidores de Proteínas Quinases/uso terapêutico
7.
Science ; 384(6697): eadj8321, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38753769

RESUMO

Germline-targeting immunogens hold promise for initiating the induction of broadly neutralizing antibodies (bnAbs) to HIV and other pathogens. However, antibody-antigen recognition is typically dominated by heavy chain complementarity determining region 3 (HCDR3) interactions, and vaccine priming of HCDR3-dominant bnAbs by germline-targeting immunogens has not been demonstrated in humans or outbred animals. In this work, immunization with N332-GT5, an HIV envelope trimer designed to target precursors of the HCDR3-dominant bnAb BG18, primed bnAb-precursor B cells in eight of eight rhesus macaques to substantial frequencies and with diverse lineages in germinal center and memory B cells. We confirmed bnAb-mimicking, HCDR3-dominant, trimer-binding interactions with cryo-electron microscopy. Our results demonstrate proof of principle for HCDR3-dominant bnAb-precursor priming in outbred animals and suggest that N332-GT5 holds promise for the induction of similar responses in humans.


Assuntos
Vacinas contra a AIDS , Anticorpos Amplamente Neutralizantes , Regiões Determinantes de Complementaridade , Centro Germinativo , Anticorpos Anti-HIV , Animais , Humanos , Vacinas contra a AIDS/imunologia , Linfócitos B/imunologia , Anticorpos Amplamente Neutralizantes/imunologia , Regiões Determinantes de Complementaridade/imunologia , Microscopia Crioeletrônica , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Centro Germinativo/imunologia , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , Infecções por HIV/prevenção & controle , HIV-1/imunologia , Cadeias Pesadas de Imunoglobulinas/imunologia , Cadeias Pesadas de Imunoglobulinas/genética , Macaca mulatta , Células B de Memória/imunologia
8.
Nat Commun ; 14(1): 7107, 2023 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-37925510

RESUMO

Adjuvants and antigen delivery kinetics can profoundly influence B cell responses and should be critically considered in rational vaccine design, particularly for difficult neutralizing antibody targets such as human immunodeficiency virus (HIV). Antigen kinetics can change depending on the delivery method. To promote extended immunogen bioavailability and to present antigen in a multivalent form, native-HIV Env trimers are modified with short phosphoserine peptide linkers that promote tight binding to aluminum hydroxide (pSer:alum). Here we explore the use of a combined adjuvant approach that incorporates pSer:alum-mediated antigen delivery with potent adjuvants (SMNP, 3M-052) in an extensive head-to-head comparison study with conventional alum to assess germinal center (GC) and humoral immune responses. Priming with pSer:alum plus SMNP induces additive effects that enhance the magnitude and persistence of GCs, which correlate with better GC-TFH cell help. Autologous HIV-neutralizing antibody titers are improved in SMNP-immunized animals after two immunizations. Over 9 months after priming immunization of pSer:alum with either SMNP or 3M-052, robust Env-specific bone marrow plasma cells (BM BPC) are observed. Furthermore, pSer-modification of Env trimer reduce targeting towards immunodominant non-neutralizing epitopes. The study shows that a combined adjuvant approach can augment humoral immunity by modulating immunodominance and shows promise for clinical translation.


Assuntos
Infecções por HIV , Imunidade Humoral , Animais , Centro Germinativo , Adjuvantes Imunológicos/farmacologia , Antígenos , Primatas , Anticorpos Neutralizantes , Anticorpos Anti-HIV , Produtos do Gene env do Vírus da Imunodeficiência Humana
9.
Sci Immunol ; 6(66): eabf1152, 2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-34860581

RESUMO

Saponins are potent and safe vaccine adjuvants, but their mechanisms of action remain incompletely understood. Here, we explored the properties of several saponin formulations, including immune-stimulatory complexes (ISCOMs) formed by the self-assembly of saponin and phospholipids in the absence or presence of the Toll-like receptor 4 agonist monophosphoryl lipid A (MPLA). We found that MPLA self-assembles with saponins to form particles physically resembling ISCOMs, which we termed saponin/MPLA nanoparticles (SMNP). Saponin-containing adjuvants exhibited distinctive mechanisms of action, altering lymph flow in a mast cell­dependent manner and promoting antigen entry into draining lymph nodes. SMNP was particularly effective, exhibiting even greater potency than the compositionally related adjuvant AS01B in mice, and primed robust germinal center B cell, TFH, and HIV tier 2 neutralizing antibodies in nonhuman primates. Together, these findings shed new light on mechanisms by which saponin adjuvants act to promote the immune response and suggest that SMNP may be a promising adjuvant in the setting of HIV, SARS-CoV-2, and other pathogens.


Assuntos
Imunidade Adaptativa/efeitos dos fármacos , Adjuvantes Imunológicos/farmacologia , Linfa/efeitos dos fármacos , Saponinas/farmacologia , Receptores Toll-Like/agonistas , Animais , Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Feminino , Linfa/fisiologia , Macaca mulatta , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Nanopartículas , Ratos , Ratos Wistar
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