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2.
Front Immunol ; 12: 705848, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34539636

RESUMO

Activation and differentiation of B cells depend on extensive rewiring of gene expression networks through changes in chromatin structure and accessibility. The chromatin remodeling complex BAF with its catalytic subunit Brg1 was previously identified as an essential regulator of early B cell development, however, how Brg1 orchestrates gene expression during mature B cell activation is less clear. Here, we find that Brg1 is required for B cell proliferation and germinal center formation through selective interactions with enhancers. Brg1 recruitment to enhancers following B cell activation was associated with increased chromatin accessibility and transcriptional activation of their coupled promoters, thereby regulating the expression of cell cycle-associated genes. Accordingly, Brg1-deficient B cells were unable to mount germinal center reactions and support the formation of class-switched plasma cells. Our findings show that changes in B cell transcriptomes that support B cell proliferation and GC formation depend on enhancer activation by Brg1. Thus, the BAF complex plays a critical role during the onset of the humoral immune response.

3.
J Exp Med ; 218(10)2021 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-34402854

RESUMO

Long-lasting immunity depends on the generation of protective antibodies through the germinal center (GC) reaction. N6-methyladenosine (m6A) modification of mRNAs by METTL3 activity modulates transcript lifetime primarily through the function of m6A readers; however, the physiological role of this molecular machinery in the GC remains unknown. Here, we show that m6A modifications by METTL3 are required for GC maintenance through the differential functions of m6A readers. Mettl3-deficient GC B cells exhibited reduced cell-cycle progression and decreased expression of proliferation- and oxidative phosphorylation-related genes. The m6A binder, IGF2BP3, was required for stabilization of Myc mRNA and expression of its target genes, whereas the m6A reader, YTHDF2, indirectly regulated the expression of the oxidative phosphorylation gene program. Our findings demonstrate how two independent gene networks that support critical GC functions are modulated by m6A through distinct mRNA binders.

4.
Sci Immunol ; 6(61)2021 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-34326184

RESUMO

The spillover of animal coronaviruses (aCoVs) to humans has caused SARS, MERS, and COVID-19. While antibody responses displaying cross-reactivity between SARS-CoV-2 and seasonal/common cold human coronaviruses (hCoVs) have been reported, potential cross-reactivity with aCoVs and the diagnostic implications are incompletely understood. Here, we probed for antibody binding against all seven hCoVs and 49 aCoVs represented as 12,924 peptides within a phage-displayed antigen library. Antibody repertoires of 269 recovered COVID-19 patients showed distinct changes compared to 260 unexposed pre-pandemic controls, not limited to binding of SARS-CoV-2 antigens but including binding to antigens from hCoVs and aCoVs with shared motifs to SARS-CoV-2. We isolated broadly reactive monoclonal antibodies from recovered COVID-19 patients that bind a shared motif of SARS-CoV-2, hCoV-OC43, hCoV-HKU1, and several aCoVs, demonstrating that interspecies cross-reactivity can be mediated by a single immunoglobulin. Employing antibody binding data against the entire CoV antigen library allowed accurate discrimination of recovered COVID-19 patients from unexposed individuals by machine learning. Leaving out SARS-CoV-2 antigens and relying solely on antibody binding to other hCoVs and aCoVs achieved equally accurate detection of SARS-CoV-2 infection. The ability to detect SARS-CoV-2 infection without knowledge of its unique antigens solely from cross-reactive antibody responses against other hCoVs and aCoVs suggests a potential diagnostic strategy for the early stage of future pandemics. Creating regularly updated antigen libraries representing the animal coronavirome can provide the basis for a serological assay already poised to identify infected individuals following a future zoonotic transmission event.


Assuntos
Anticorpos Antivirais/imunologia , Antígenos Virais/imunologia , Infecções por Coronavirus/imunologia , Coronavirus/imunologia , Biblioteca de Peptídeos , Adolescente , Adulto , Idoso , Animais , Infecções por Coronavirus/diagnóstico , Reações Cruzadas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Zoonoses
5.
Sci Immunol ; 6(60)2021 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-34088746

RESUMO

In this issue of Science Immunology, Gallman et al. reveal how S-geranylgeranyl-l-glutathione cleavage and transport support P2RY8-driven B cell confinement to the germinal centers and its role in lymphocyte homing to the bone marrow.

6.
J Clin Invest ; 131(13)2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34014840

RESUMO

BACKGROUNDThe significant risks posed to mothers and fetuses by COVID-19 in pregnancy have sparked a worldwide debate surrounding the pros and cons of antenatal SARS-CoV-2 inoculation, as we lack sufficient evidence regarding vaccine effectiveness in pregnant women and their offspring. We aimed to provide substantial evidence for the effect of the BNT162b2 mRNA vaccine versus native infection on maternal humoral, as well as transplacentally acquired fetal immune response, potentially providing newborn protection.METHODSA multicenter study where parturients presenting for delivery were recruited at 8 medical centers across Israel and assigned to 3 study groups: vaccinated (n = 86); PCR-confirmed SARS-CoV-2 infected during pregnancy (n = 65), and unvaccinated noninfected controls (n = 62). Maternal and fetal blood samples were collected from parturients prior to delivery and from the umbilical cord following delivery, respectively. Sera IgG and IgM titers were measured using the Milliplex MAP SARS-CoV-2 Antigen Panel (for S1, S2, RBD, and N).RESULTSThe BNT162b2 mRNA vaccine elicits strong maternal humoral IgG response (anti-S and RBD) that crosses the placenta barrier and approaches maternal titers in the fetus within 15 days following the first dose. Maternal to neonatal anti-COVID-19 antibodies ratio did not differ when comparing sensitization (vaccine vs. infection). IgG transfer ratio at birth was significantly lower for third-trimester as compared with second trimester infection. Lastly, fetal IgM response was detected in 5 neonates, all in the infected group.CONCLUSIONAntenatal BNT162b2 mRNA vaccination induces a robust maternal humoral response that effectively transfers to the fetus, supporting the role of vaccination during pregnancy.FUNDINGIsrael Science Foundation and the Weizmann Institute Fondazione Henry Krenter.


Assuntos
Anticorpos Antivirais/sangue , Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/farmacologia , COVID-19/imunologia , COVID-19/prevenção & controle , Troca Materno-Fetal/imunologia , SARS-CoV-2/imunologia , Adulto , Estudos de Coortes , Feminino , Sangue Fetal/imunologia , Humanos , Imunização Passiva , Imunoglobulina G/sangue , Recém-Nascido , Masculino , Gravidez , Adulto Jovem
7.
Nat Chem Biol ; 17(9): 954-963, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33972797

RESUMO

The peptidyl-prolyl isomerase, Pin1, is exploited in cancer to activate oncogenes and inactivate tumor suppressors. However, despite considerable efforts, Pin1 has remained an elusive drug target. Here, we screened an electrophilic fragment library to identify covalent inhibitors targeting Pin1's active site Cys113, leading to the development of Sulfopin, a nanomolar Pin1 inhibitor. Sulfopin is highly selective, as validated by two independent chemoproteomics methods, achieves potent cellular and in vivo target engagement and phenocopies Pin1 genetic knockout. Pin1 inhibition had only a modest effect on cancer cell line viability. Nevertheless, Sulfopin induced downregulation of c-Myc target genes, reduced tumor progression and conferred survival benefit in murine and zebrafish models of MYCN-driven neuroblastoma, and in a murine model of pancreatic cancer. Our results demonstrate that Sulfopin is a chemical probe suitable for assessment of Pin1-dependent pharmacology in cells and in vivo, and that Pin1 warrants further investigation as a potential cancer drug target.


Assuntos
Antineoplásicos/farmacologia , Inibidores Enzimáticos/farmacologia , Peptidilprolil Isomerase de Interação com NIMA/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-myc/antagonistas & inibidores , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Estrutura Molecular , Peptidilprolil Isomerase de Interação com NIMA/metabolismo , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Proteínas Proto-Oncogênicas c-myc/metabolismo , Relação Estrutura-Atividade , Células Tumorais Cultivadas
8.
J Am Chem Soc ; 143(13): 4979-4992, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33761747

RESUMO

Targeted covalent inhibitors are an important class of drugs and chemical probes. However, relatively few electrophiles meet the criteria for successful covalent inhibitor design. Here we describe α-substituted methacrylamides as a new class of electrophiles suitable for targeted covalent inhibitors. While typically α-substitutions inactivate acrylamides, we show that hetero α-substituted methacrylamides have higher thiol reactivity and undergo a conjugated addition-elimination reaction ultimately releasing the substituent. Their reactivity toward thiols is tunable and correlates with the pKa/pKb of the leaving group. In the context of the BTK inhibitor ibrutinib, these electrophiles showed lower intrinsic thiol reactivity than the unsubstituted ibrutinib acrylamide. This translated to comparable potency in protein labeling, in vitro kinase assays, and functional cellular assays, with improved selectivity. The conjugate addition-elimination reaction upon covalent binding to their target cysteine allows functionalizing α-substituted methacrylamides as turn-on probes. To demonstrate this, we prepared covalent ligand directed release (CoLDR) turn-on fluorescent probes for BTK, EGFR, and K-RasG12C. We further demonstrate a BTK CoLDR chemiluminescent probe that enabled a high-throughput screen for BTK inhibitors. Altogether we show that α-substituted methacrylamides represent a new and versatile addition to the toolbox of targeted covalent inhibitor design.

11.
Nat Commun ; 11(1): 3547, 2020 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-32669546

RESUMO

Neutrophils provide first line of host defense against bacterial infections utilizing glycolysis for their effector functions. How glycolysis and its major byproduct lactate are triggered in bone marrow (BM) neutrophils and their contribution to neutrophil mobilization in acute inflammation is not clear. Here we report that bacterial lipopolysaccharides (LPS) or Salmonella Typhimurium triggers lactate release by increasing glycolysis, NADPH-oxidase-mediated reactive oxygen species and HIF-1α levels in BM neutrophils. Increased release of BM lactate preferentially promotes neutrophil mobilization by reducing endothelial VE-Cadherin expression, increasing BM vascular permeability via endothelial lactate-receptor GPR81 signaling. GPR81-/- mice mobilize reduced levels of neutrophils in response to LPS, unless rescued by VE-Cadherin disrupting antibodies. Lactate administration also induces release of the BM neutrophil mobilizers G-CSF, CXCL1 and CXCL2, indicating that this metabolite drives neutrophil mobilization via multiple pathways. Our study reveals a metabolic crosstalk between lactate-producing neutrophils and BM endothelium, which controls neutrophil mobilization under bacterial infection.


Assuntos
Células da Medula Óssea/imunologia , Ácido Láctico/metabolismo , Neutrófilos/imunologia , Receptores Acoplados a Proteínas G/metabolismo , Infecções por Salmonella/imunologia , Animais , Medula Óssea/irrigação sanguínea , Células da Medula Óssea/metabolismo , Modelos Animais de Doenças , Endotélio Vascular/metabolismo , Feminino , Humanos , Lipopolissacarídeos/imunologia , Masculino , Camundongos , Camundongos Knockout , Neutrófilos/metabolismo , Receptores Acoplados a Proteínas G/genética , Infecções por Salmonella/microbiologia , Salmonella typhimurium/imunologia , Transdução de Sinais/imunologia
13.
Immunol Rev ; 296(1): 36-47, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32557712

RESUMO

Enduring immunity against harmful pathogens depends on the generation of immunological memory. Serum immunoglobulins are constantly secreted by long-lived antibody-producing cells, which provide extended protection from recurrent exposures. These cells originate mainly from germinal center structures, wherein B cells introduce mutations to their immunoglobulin genes followed by affinity-based selection. Generation of high-affinity antibodies relies on physical contacts between T and B cells, a process that facilitates the delivery of fate decision signals. T-B cellular engagements are mediated through interactions between the T cell receptor and its cognate peptide presented on B cell major histocompatibility class II molecules. Here, we describe the cellular and molecular aspects of these cognate T-B interactions, and highlight exceptional cases, especially those arising at intestinal lymphoid organs, at which T cells provide help to B cells in an atypical manner, independent of T cell specificity.

14.
J Am Chem Soc ; 142(27): 11734-11742, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32369353

RESUMO

Proteolysis targeting chimeras (PROTACs) represent an exciting inhibitory modality with many advantages, including substoichiometric degradation of targets. Their scope, though, is still limited to date by the requirement for a sufficiently potent target binder. A solution that proved useful in tackling challenging targets is the use of electrophiles to allow irreversible binding to the target. However, such binding will negate the catalytic nature of PROTACs. Reversible covalent PROTACs potentially offer the best of both worlds. They possess the potency and selectivity associated with the formation of the covalent bond, while being able to dissociate and regenerate once the protein target is degraded. Using Bruton's tyrosine kinase (BTK) as a clinically relevant model system, we show efficient degradation by noncovalent, irreversible covalent, and reversible covalent PROTACs, with <10 nM DC50's and >85% degradation. Our data suggest that part of the degradation by our irreversible covalent PROTACs is driven by reversible binding prior to covalent bond formation, while the reversible covalent PROTACs drive degradation primarily by covalent engagement. The PROTACs showed enhanced inhibition of B cell activation compared to ibrutinib and exhibit potent degradation of BTK in patient-derived primary chronic lymphocytic leukemia cells. The most potent reversible covalent PROTAC, RC-3, exhibited enhanced selectivity toward BTK compared to noncovalent and irreversible covalent PROTACs. These compounds may pave the way for the design of covalent PROTACs for a wide variety of challenging targets.

15.
Nat Immunol ; 21(5): 501-512, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32284591

RESUMO

Protection from harmful pathogens depends on activation of the immune system, which relies on tight regulation of gene expression. Recently, the RNA modification N6-methyladenosine (m6A) has been found to play an essential role in such regulation. Here, we summarize newly discovered functions of m6A in controlling various aspects of immunity, including immune recognition, activation of innate and adaptive immune responses, and cell fate decisions. We then discuss some of the current challenges in the field and describe future directions for uncovering the immunological functions of m6A and its mechanisms of action.


Assuntos
Processamento Pós-Transcricional do RNA/imunologia , RNA/genética , Imunidade Adaptativa/genética , Adenosina/análogos & derivados , Adenosina/genética , Animais , Diferenciação Celular , Humanos , Sistema Imunitário , Imunidade Inata/genética , Imunomodulação
16.
Cell Rep ; 30(6): 1910-1922.e5, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-32049020

RESUMO

Antibodies secreted within the intestinal tract provide protection from the invasion of microbes into the host tissues. Germinal center (GC) formation in lymph nodes and spleen strictly requires SLAM-associated protein (SAP)-mediated T cell functions; however, it is not known whether this mechanism plays a similar role in mucosal-associated lymphoid tissues. Here, we find that in Peyer's patches (PPs), SAP-mediated T cell help is required for promoting B cell selection in GCs, but not for clonal diversification. PPs of SAP-deficient mice host chronic GCs that are absent in T cell-deficient mice. GC B cells in SAP-deficient mice express AID and Bcl6 and generate plasma cells in proportion to the GC size. Single-cell IgA sequencing analysis reveals that these mice host few diversified clones that were subjected to mild selection forces. These findings demonstrate that T cell-derived help to B cells in PPs includes SAP-dependent and SAP-independent functions.


Assuntos
Linfócitos B/imunologia , Centro Germinativo/imunologia , Nódulos Linfáticos Agregados/imunologia , Proteína Associada à Molécula de Sinalização da Ativação Linfocitária/metabolismo , Animais , Camundongos
17.
J Exp Med ; 217(3)2020 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-31873727

RESUMO

Germinal centers (GCs) are sites at which B cells proliferate and mutate their antibody-encoding genes in the dark zone (DZ), followed by affinity-based selection in the light zone (LZ). B cell antigen receptor (BCR) signals induce Syk activation followed by rapid phosphatase-mediated desensitization; however, how degradation events regulate BCR functions in GCs is unclear. Here, we found that Syk degradation restrains plasma cell (PC) formation in GCs and promotes B cell LZ to DZ transition. Using a mouse model defective in Cbl-mediated Syk degradation, we demonstrate that this machinery attenuates BCR signaling intensity by mitigating the Kras/Erk and PI3K/Foxo1 pathways, and restricting the expression of PC transcription factors in GC B cells. Inhibition of Syk degradation perturbed gene expression, specifically in the LZ, and enhanced the generation of PCs without affecting B cell proliferation. These findings reveal how long-lasting attenuation of signal transduction by degradation events regulates cell fate within specialized microanatomical sites.


Assuntos
Centro Germinativo/metabolismo , Plasmócitos/metabolismo , Quinase Syk/metabolismo , Animais , Linfócitos B/metabolismo , Linfócitos B/fisiologia , Proliferação de Células/fisiologia , Expressão Gênica/fisiologia , Centro Germinativo/fisiologia , Ativação Linfocitária/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Plasmócitos/fisiologia , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais/fisiologia
18.
J Exp Med ; 216(11): 2515-2530, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31492809

RESUMO

Germinal centers (GCs) are sites wherein B cells proliferate and mutate their immunoglobulins in the dark zone (DZ), followed by affinity-based selection in the light zone (LZ). Here, we mapped the location of single B cells in the context of intact lymph nodes (LNs) throughout the GC response, and examined the role of BCR affinity in dictating their position. Imaging of entire GC structures and proximal single cells by light-sheet fluorescence microscopy revealed that individual B cells that previously expressed AID are located within the LN cortex, in an area close to the GC LZ. Using in situ photoactivation, we demonstrated that B cells migrate from the LZ toward the GC outskirts, while DZ B cells are confined to the GC. B cells expressing very-low-affinity BCRs formed GCs but were unable to efficiently disperse within the follicles. Our findings reveal that BCR affinity regulates B cell positioning during the GC response.


Assuntos
Linfócitos B/metabolismo , Proliferação de Células , Centro Germinativo/metabolismo , Linfonodos/metabolismo , Receptores de Antígenos de Linfócitos B/metabolismo , Animais , Linfócitos B/citologia , Movimento Celular , Centro Germinativo/citologia , Linfonodos/citologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Microscopia Confocal , Microscopia de Fluorescência
19.
Cell Adh Migr ; 13(1): 315-321, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31328672

RESUMO

It is unclear if naïve T cells require dendritic cell ICAMs to proliferate inside lymph nodes. To check if and when CD4 lymphocytes use ICAMs on migratory DCs, wild-type and ICAM-1 and 2 double knock out bone marrow-derived DCs pulsed with saturating levels of an OT-II transgene-specific ovalbumin-derived peptide were co-transferred into skin-draining lymph nodes. Intravital imaging of OT-II lymphocytes entering these lymph nodes revealed that ICAM-1 and -2 deficient migratory DCs formed fewer stable conjugates with OT-II lymphocytes but promoted normal T cell proliferation. DC ICAMs were also not required for unstable TCR-dependent lymphocyte arrests on antigen presenting migratory DCs. Thus, rare antigen-stimulated ICAM-stabilized T-DC conjugates are dispensable for CD4 lymphocyte proliferation inside lymph nodes.


Assuntos
Antígenos CD/metabolismo , Linfócitos T CD4-Positivos/imunologia , Moléculas de Adesão Celular/metabolismo , Células Dendríticas/imunologia , Molécula 1 de Adesão Intercelular/metabolismo , Linfonodos/metabolismo , Animais , Antígenos CD/genética , Linfócitos T CD4-Positivos/citologia , Moléculas de Adesão Celular/genética , Movimento Celular/fisiologia , Proliferação de Células/fisiologia , Células Dendríticas/citologia , Molécula 1 de Adesão Intercelular/genética , Lipopolissacarídeos/imunologia , Linfonodos/citologia , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout
20.
Nat Commun ; 10(1): 2423, 2019 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-31160559

RESUMO

The germinal center (GC) reaction in Peyer's patches (PP) requires continuous access to antigens, but how this is achieved is not known. Here we show that activated antigen-specific CCR6+CCR1+GL7- B cells make close contact with M cells in the subepithelial dome (SED). Using in situ photoactivation analysis of antigen-specific SED B cells, we find migration of cells towards the GC. Following antigen injection into ligated intestinal loops containing PPs, 40% of antigen-specific SED B cells bind antigen within 2 h, whereas unspecifc cells do not, indicating B cell-receptor involvment. Antigen-loading is not observed in M cell-deficient mice, but is unperturbed in mice depleted of classical dendritic cells (DC). Thus, we report a M cell-B cell antigen-specific transporting pathway in PP that is independent of DC. We propose that this antigen transporting pathway has a critical role in gut IgA responses, and should be taken into account when developing mucosal vaccines.


Assuntos
Células Apresentadoras de Antígenos/imunologia , Antígenos/imunologia , Linfócitos B/imunologia , Células Epiteliais/imunologia , Nódulos Linfáticos Agregados/imunologia , Receptores de Antígenos de Linfócitos B/imunologia , Animais , Células Dendríticas/imunologia , Centro Germinativo/imunologia , Imunoglobulina A/imunologia , Ativação Linfocitária , Camundongos
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