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1.
Cell ; 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-32059783

RESUMO

Pathogenic autoantibodies arise in many autoimmune diseases, but it is not understood how the cells making them evade immune checkpoints. Here, single-cell multi-omics analysis demonstrates a shared mechanism with lymphoid malignancy in the formation of public rheumatoid factor autoantibodies responsible for mixed cryoglobulinemic vasculitis. By combining single-cell DNA and RNA sequencing with serum antibody peptide sequencing and antibody synthesis, rare circulating B lymphocytes making pathogenic autoantibodies were found to comprise clonal trees accumulating mutations. Lymphoma driver mutations in genes regulating B cell proliferation and V(D)J mutation (CARD11, TNFAIP3, CCND3, ID3, BTG2, and KLHL6) were present in rogue B cells producing the pathogenic autoantibody. Antibody V(D)J mutations conferred pathogenicity by causing the antigen-bound autoantibodies to undergo phase transition to insoluble aggregates at lower temperatures. These results reveal a pre-neoplastic stage in human lymphomagenesis and a cascade of somatic mutations leading to an iconic pathogenic autoantibody.

2.
J Exp Med ; 217(2)2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31841125

RESUMO

Antibody-mediated autoimmune diseases are a major health burden. However, our understanding of how self-reactive B cells escape self-tolerance checkpoints to secrete pathogenic autoantibodies remains incomplete. Here, we demonstrate that patients with monogenic immune dysregulation caused by gain-of-function mutations in PIK3CD, encoding the p110δ catalytic subunit of phosphoinositide 3-kinase (PI3K), have highly penetrant secretion of autoreactive IgM antibodies. In mice with the corresponding heterozygous Pik3cd activating mutation, self-reactive B cells exhibit a cell-autonomous subversion of their response to self-antigen: instead of becoming tolerized and repressed from secreting autoantibody, Pik3cd gain-of-function B cells are activated by self-antigen to form plasmablasts that secrete high titers of germline-encoded IgM autoantibody and hypermutating germinal center B cells. However, within the germinal center, peripheral tolerance was still enforced, and there was selection against B cells with high affinity for self-antigen. These data show that the strength of PI3K signaling is a key regulator of pregerminal center B cell self-tolerance and thus represents a druggable pathway to treat antibody-mediated autoimmunity.

3.
Curr Opin Immunol ; 63: 29-34, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31835060

RESUMO

Germinal centers (GCs) are well known for their important role in shaping the secondary B cell repertoire to generate antibodies capable of binding with high-affinity and specificity to foreign antigens. Somatic hypermutation of the Ig variable region genes in GC B cells represents a highly efficient mechanism for generating new antibody variants with increased antigen affinity. To be effective, however, this process needs to be intimately linked with equally efficient processes that positively select high-affinity clones for perpetuation in the GC and, ultimately, for differentiation into plasma cell and memory B cell effector populations. Just as important is the need for mechanisms of negative selection that remove GC B cell clones with unwanted specificities, particularly those that have gained reactivity with self-components. Here, we discuss recent advances in our understanding of the various selective processes that occur within the GC and identify the major questions in this field that remain to be answered.

4.
Nat Immunol ; 20(10): 1299-1310, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31534238

RESUMO

Resisting and tolerating microbes are alternative strategies to survive infection, but little is known about the evolutionary mechanisms controlling this balance. Here genomic analyses of anatomically modern humans, extinct Denisovan hominins and mice revealed a TNFAIP3 allelic series with alterations in the encoded immune response inhibitor A20. Each TNFAIP3 allele encoded substitutions at non-catalytic residues of the ubiquitin protease OTU domain that diminished IκB kinase-dependent phosphorylation and activation of A20. Two TNFAIP3 alleles encoding A20 proteins with partial phosphorylation deficits seemed to be beneficial by increasing immunity without causing spontaneous inflammatory disease: A20 T108A;I207L, originating in Denisovans and introgressed in modern humans throughout Oceania, and A20 I325N, from an N-ethyl-N-nitrosourea (ENU)-mutagenized mouse strain. By contrast, a rare human TNFAIP3 allele encoding an A20 protein with 95% loss of phosphorylation, C243Y, caused spontaneous inflammatory disease in humans and mice. Analysis of the partial-phosphorylation A20 I325N allele in mice revealed diminished tolerance of bacterial lipopolysaccharide and poxvirus inoculation as tradeoffs for enhanced immunity.

5.
J Allergy Clin Immunol ; 144(1): 236-253, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30738173

RESUMO

BACKGROUND: Gain-of-function (GOF) mutations in PIK3CD cause a primary immunodeficiency characterized by recurrent respiratory tract infections, susceptibility to herpesvirus infections, and impaired antibody responses. Previous work revealed defects in CD8+ T and B cells that contribute to this clinical phenotype, but less is understood about the role of CD4+ T cells in disease pathogenesis. OBJECTIVE: We sought to dissect the effects of increased phosphoinositide 3-kinase (PI3K) signaling on CD4+ T-cell function. METHODS: We performed detailed ex vivo, in vivo, and in vitro phenotypic and functional analyses of patients' CD4+ T cells and a novel murine disease model caused by overactive PI3K signaling. RESULTS: PI3K overactivation caused substantial increases in numbers of memory and follicular helper T (TFH) cells and dramatic changes in cytokine production in both patients and mice. Furthermore, PIK3CD GOF human TFH cells had dysregulated phenotype and function characterized by increased programmed cell death protein 1, CXCR3, and IFN-γ expression, the phenotype of a TFH cell subset with impaired B-helper function. This was confirmed in vivo in which Pik3cd GOF CD4+ T cells also acquired an aberrant TFH phenotype and provided poor help to support germinal center reactions and humoral immune responses by antigen-specific wild-type B cells. The increase in numbers of both memory and TFH cells was largely CD4+ T-cell extrinsic, whereas changes in cytokine production and TFH cell function were cell intrinsic. CONCLUSION: Our studies reveal that CD4+ T cells with overactive PI3K have aberrant activation and differentiation, thereby providing mechanistic insight into dysfunctional antibody responses in patients with PIK3CD GOF mutations.

7.
Nat Commun ; 9(1): 3372, 2018 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-30135429

RESUMO

Vaccine-induced immunity depends on the generation of memory B cells (MBC). However, where and how MBCs are reactivated to make neutralising antibodies remain unknown. Here we show that MBCs are prepositioned in a subcapsular niche in lymph nodes where, upon reactivation by antigen, they rapidly proliferate and differentiate into antibody-secreting plasma cells in the subcapsular proliferative foci (SPF). This novel structure is enriched for signals provided by T follicular helper cells and antigen-presenting subcapsular sinus macrophages. Compared with contemporaneous secondary germinal centres, SPF have distinct single-cell molecular signature, cell migration pattern and plasma cell output. Moreover, SPF are found both in human and mouse lymph nodes, suggesting that they are conserved throughout mammalian evolution. Our data thus reveal that SPF is a seat of immunological memory that may be exploited to rapidly mobilise secondary antibody responses and improve vaccine efficacy.


Assuntos
Linfócitos B/metabolismo , Linfonodos/metabolismo , Animais , Linfócitos B/imunologia , Linfócitos T CD4-Positivos/metabolismo , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Citometria de Fluxo , Humanos , Linfonodos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Modelos Teóricos , Pirazóis/farmacologia , Pirimidinas/farmacologia , Tamoxifeno/farmacologia
8.
J Exp Med ; 215(8): 2073-2095, 2018 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-30018075

RESUMO

Gain-of-function (GOF) mutations in PIK3CD, encoding the p110δ subunit of phosphatidylinositide 3-kinase (PI3K), cause a primary immunodeficiency. Affected individuals display impaired humoral immune responses following infection or immunization. To establish mechanisms underlying these immune defects, we studied a large cohort of patients with PIK3CD GOF mutations and established a novel mouse model using CRISPR/Cas9-mediated gene editing to introduce a common pathogenic mutation in Pik3cd In both species, hyperactive PI3K severely affected B cell development and differentiation in the bone marrow and the periphery. Furthermore, PI3K GOF B cells exhibited intrinsic defects in class-switch recombination (CSR) due to impaired induction of activation-induced cytidine deaminase (AID) and failure to acquire a plasmablast gene signature and phenotype. Importantly, defects in CSR, AID expression, and Ig secretion were restored by leniolisib, a specific p110δ inhibitor. Our findings reveal key roles for balanced PI3K signaling in B cell development and long-lived humoral immunity and memory and establish the validity of treating affected individuals with p110δ inhibitors.


Assuntos
Linfócitos B/citologia , Linfócitos B/imunologia , Classe I de Fosfatidilinositol 3-Quinases/genética , Mutação em Linhagem Germinativa/genética , Fosfatidilinositol 3-Quinases/genética , Animais , Afinidade de Anticorpos/imunologia , Células da Medula Óssea/citologia , Diferenciação Celular , Proliferação de Células , Criança , Mutação com Ganho de Função/genética , Humanos , Switching de Imunoglobulina , Imunoglobulinas/metabolismo , Interleucinas/farmacologia , Camundongos , Modelos Animais , Fenótipo , Fosfatidilinositol 3-Quinases/metabolismo , Plasmócitos/metabolismo , Transdução de Sinais
9.
Science ; 360(6385): 223-226, 2018 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-29650674

RESUMO

Antibodies have the specificity to differentiate foreign antigens that mimic self antigens, but it remains unclear how such specificity is acquired. In a mouse model, we generated B cells displaying an antibody that cross-reacts with two related protein antigens expressed on self versus foreign cells. B cell anergy was imposed by self antigen but reversed upon challenge with high-density foreign antigen, leading to germinal center recruitment and antibody gene hypermutation. Single-cell analysis detected rapid selection for mutations that decrease self affinity and slower selection for epistatic mutations that specifically increase foreign affinity. Crystal structures revealed that these mutations exploited subtle topological differences to achieve 5000-fold preferential binding to foreign over self epitopes. Resolution of antigenic mimicry drove the optimal affinity maturation trajectory, highlighting the value of retaining self-reactive clones as substrates for protective antibody responses.


Assuntos
Anticorpos/genética , Formação de Anticorpos/genética , Autoantígenos/imunologia , Centro Germinativo/imunologia , Mimetismo Molecular/genética , Tolerância a Antígenos Próprios , Animais , Anticorpos/química , Anticorpos/imunologia , Afinidade de Anticorpos/genética , Linfócitos B/imunologia , Anergia Clonal , Reações Cruzadas , Cristalografia por Raios X , Camundongos , Camundongos Mutantes , Mutação , Nucleoproteínas/genética , Nucleoproteínas/imunologia , Seleção Genética , Análise de Célula Única
10.
Am J Physiol Endocrinol Metab ; 315(2): E286-E293, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29664675

RESUMO

Glucose transporter 6 (GLUT6) is a member of the facilitative glucose transporter family. GLUT6 is upregulated in several cancers but is not widely expressed in normal tissues. Previous studies have shown that GLUT6 knockdown kills endometrial cancer cells that express elevated levels of the protein. However, whether GLUT6 represents a viable anticancer drug target is unclear because the role of GLUT6 in normal metabolic physiology is unknown. Herein we generated GLUT6 knockout mice to determine how loss of GLUT6 affected whole body glucose homeostasis and metabolic physiology. We found that the mouse GLUT6 ( Slc2a6) gene expression pattern was similar to humans with mRNA found primarily in brain and spleen. CRISPR-Cas9-mediated deletion of Slc2a6 did not alter mouse development, growth, or whole body glucose metabolism in male or female mice fed either a chow diet or Western diet. GLUT6 deletion did not impact glucose tolerance or blood glucose and insulin levels in male or female mice fed either diet. However, compared with wild-type littermate controls, GLUT6 null female mice had a relatively minor decrease in fat accumulation when fed Western diet and had a lower respiratory exchange ratio when fed chow diet. Collectively, these data show that GLUT6 is not a major regulator of whole body metabolic physiology; therefore, GLUT6 inhibition may have minimal adverse effects if targeted for cancer therapy.


Assuntos
Proteínas Facilitadoras de Transporte de Glucose/genética , Metabolismo/genética , Metabolismo/fisiologia , Adiposidade/genética , Animais , Glicemia/metabolismo , Peso Corporal/genética , Sistemas CRISPR-Cas , Dieta , Metabolismo Energético/genética , Feminino , Genótipo , Glucose/metabolismo , Teste de Tolerância a Glucose , Homeostase/genética , Insulina/sangue , Masculino , Camundongos , Camundongos Knockout
11.
Proc Natl Acad Sci U S A ; 115(19): 4921-4926, 2018 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-29669924

RESUMO

Activation-induced deaminase (AID) initiates hypermutation of Ig genes in activated B cells by converting C:G into U:G base pairs. G1-phase variants of uracil base excision repair (BER) and mismatch repair (MMR) then deploy translesion polymerases including REV1 and Pol η, which exacerbates mutation. dNTP paucity may contribute to hypermutation, because dNTP levels are reduced in G1 phase to inhibit viral replication. To derestrict G1-phase dNTP supply, we CRISPR-inactivated SAMHD1 (which degrades dNTPs) in germinal center B cells. Samhd1 inactivation increased B cell virus susceptibility, increased transition mutations at C:G base pairs, and substantially decreased transversion mutations at A:T and C:G base pairs in both strands. We conclude that SAMHD1's restriction of dNTP supply enhances AID's mutagenicity and that the evolution of Ig hypermutation included the repurposing of antiviral mechanisms based on dNTP starvation.


Assuntos
Linfócitos B/imunologia , Fase G1/imunologia , Ativação Linfocitária , Mutação , Proteína 1 com Domínio SAM e Domínio HD , Hipermutação Somática de Imunoglobulina/imunologia , Animais , Linfócitos B/citologia , Citidina Desaminase/imunologia , Fase G1/genética , Masculino , Camundongos , Camundongos Transgênicos , Nucleotidiltransferases/genética , Nucleotidiltransferases/imunologia , Proteína 1 com Domínio SAM e Domínio HD/genética , Proteína 1 com Domínio SAM e Domínio HD/imunologia
12.
J Exp Med ; 215(3): 801-813, 2018 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-29386231

RESUMO

Activated B cells can initially differentiate into three functionally distinct fates-early plasmablasts (PBs), germinal center (GC) B cells, or early memory B cells-by mechanisms that remain poorly understood. Here, we identify atypical chemokine receptor 4 (ACKR4), a decoy receptor that binds and degrades CCR7 ligands CCL19/CCL21, as a regulator of early activated B cell differentiation. By restricting initial access to splenic interfollicular zones (IFZs), ACKR4 limits the early proliferation of activated B cells, reducing the numbers available for subsequent differentiation. Consequently, ACKR4 deficiency enhanced early PB and GC B cell responses in a CCL19/CCL21-dependent and B cell-intrinsic manner. Conversely, aberrant localization of ACKR4-deficient activated B cells to the IFZ was associated with their preferential commitment to the early PB linage. Our results reveal a regulatory mechanism of B cell trafficking via an atypical chemokine receptor that shapes activated B cell fate.


Assuntos
Linfócitos B/citologia , Linfócitos B/metabolismo , Linhagem da Célula , Receptores CCR/metabolismo , Animais , Antígenos/metabolismo , Proliferação de Células , Centro Germinativo/metabolismo , Camundongos Endogâmicos C57BL , Baço/citologia
13.
Immunol Cell Biol ; 96(2): 128-136, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29363187

RESUMO

The G protein-coupled receptor 65 (GPR65) gene has been genetically associated with several autoimmune diseases, including multiple sclerosis (MS). GPR65 is predominantly expressed in lymphoid organs and is activated by extracellular protons. In this study, we tested whether GPR65 plays a functional role in demyelinating autoimmune disease. Using a murine model of MS, experimental autoimmune encephalomyelitis (EAE), we found that Gpr65-deficient mice develop exacerbated disease. CD4+ helper T cells are key drivers of EAE pathogenesis, however, Gpr65 deficiency in these cells did not contribute to the observed exacerbated disease. Instead, Gpr65 expression levels were found to be highest on invariant natural killer T (iNKT) cells. EAE severity in Gpr65-deficient mice was normalized in the absence of iNKT cells (CD1d-deficient mice), suggesting that GPR65 signals in iNKT cells are important for suppressing autoimmune disease. These findings provide functional support for the genetic association of GPR65 with MS and demonstrate GPR65 signals suppress autoimmune activity in EAE.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Encefalomielite Autoimune Experimental/imunologia , Células T Matadoras Naturais/imunologia , Transferência Adotiva , Animais , Modelos Animais de Doenças , Progressão da Doença , Encefalomielite Autoimune Experimental/patologia , Camundongos Endogâmicos C57BL , Glicoproteína Mielina-Oligodendrócito/imunologia , Fragmentos de Peptídeos/imunologia , Receptores Acoplados a Proteínas-G/deficiência , Receptores Acoplados a Proteínas-G/metabolismo
14.
Annu Rev Immunol ; 36: 339-357, 2018 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-29356584

RESUMO

Maintenance of immunological self-tolerance requires lymphocytes carrying self-reactive antigen receptors to be selectively prevented from mounting destructive or inflammatory effector responses. Classically, self-tolerance is viewed in terms of the removal, editing, or silencing of B and T cells that have formed self-reactive antigen receptors during their early development. However, B cells activated by foreign antigen can enter germinal centers (GCs), where they further modify their antigen receptor by somatic hypermutation (SHM) of their immunoglobulin genes. The inevitable emergence of activated, self-reactive GC B cells presents a unique challenge to the maintenance of self-tolerance that must be rapidly countered to avoid autoantibody production. Here we discuss current knowledge of the mechanisms that enforce B cell self-tolerance, with particular focus on the control of self-reactive GC B cells. We also consider how self-reactive GC B cells can escape self-tolerance to initiate autoantibody production or instead be redeemed via SHM and used in productive antibody responses.


Assuntos
Autoimunidade , Linfócitos B/imunologia , Centro Germinativo/imunologia , Animais , Autoanticorpos/imunologia , Autoantígenos/imunologia , Linfócitos B/metabolismo , Centro Germinativo/metabolismo , Humanos , Tolerância Imunológica , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Plasmócitos/imunologia , Plasmócitos/metabolismo , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo
15.
Immunity ; 47(6): 1142-1153.e4, 2017 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-29262350

RESUMO

Memory B cells (MBCs) and plasma cells (PCs) constitute the two cellular outputs of germinal center (GC) responses that together facilitate long-term humoral immunity. Although expression of the transcription factor BLIMP-1 identifies cells undergoing PC differentiation, no such marker exists for cells committed to the MBC lineage. Here, we report that the chemokine receptor CCR6 uniquely marks MBC precursors in both mouse and human GCs. CCR6+ GC B cells were highly enriched within the GC light zone (LZ), were the most quiescent of all GC B cells, exhibited a cell-surface phenotype and gene expression signature indicative of an MBC transition, and possessed the augmented response characteristics of MBCs. MBC precursors within the GC LZ predominantly possessed a low affinity for antigen but also included cells from within the high-affinity pool. These data indicate a fundamental dichotomy between the processes that drive MBC and PC differentiation during GC responses.


Assuntos
Centro Germinativo/imunologia , Imunidade Humoral , Plasmócitos/imunologia , Células Precursoras de Linfócitos B/imunologia , Receptores CCR6/imunologia , Animais , Antígeno B7-2/genética , Antígeno B7-2/imunologia , Diferenciação Celular , Linhagem da Célula/imunologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Centro Germinativo/citologia , Humanos , Memória Imunológica , Imunofenotipagem , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fenótipo , Plasmócitos/citologia , Fator 1 de Ligação ao Domínio I Regulador Positivo/genética , Fator 1 de Ligação ao Domínio I Regulador Positivo/imunologia , Células Precursoras de Linfócitos B/citologia , Receptores CCR6/genética , Receptores CXCR4/genética , Receptores CXCR4/imunologia , Transdução de Sinais
16.
Acta Crystallogr D Struct Biol ; 73(Pt 11): 910-920, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29095163

RESUMO

Duck egg lysozyme (DEL) is a widely used model antigen owing to its capacity to bind with differential affinity to anti-chicken egg lysozyme antibodies. However, no structures of DEL have so far been reported, and the situation had been complicated by the presence of multiple isoforms and conflicting reports of primary sequence. Here, the structures of two DEL isoforms from the eggs of the commonly used Pekin duck (Anas platyrhynchos) are reported. Using structural analyses in combination with mass spectrometry, non-ambiguous DEL primary sequences are reported. Furthermore, the structures and sequences determined here enable rationalization of the binding affinity of DEL for well documented landmark anti-lysozyme antibodies.


Assuntos
Apresentação do Antígeno , Proteínas Aviárias/química , Patos , Proteínas do Ovo/química , Muramidase/química , Sequência de Aminoácidos , Animais , Cristalização , Cristalografia por Raios X , Clara de Ovo/química , Modelos Moleculares , Conformação Proteica , Homologia de Sequência
17.
J Immunol ; 199(7): 2366-2376, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28835458

RESUMO

IL-17-producing γδ T (γδT-17) cells have proved to be an important early source of IL-17 in many inflammatory settings and are emerging as an important participant in protumor immune responses. Considering that their peripheral activation depends largely on innate signals rather than TCR ligation, it is important to understand what mechanisms exist to curb unwanted activation. Expression of the high-affinity IL-2R on γδT-17 cells prompted us to investigate a role for this cytokine. We found γδT-17 cells to be enriched, not depleted, in IL-2-deficient mice. The absence of IL-2 also resulted in higher IL-17 production and the emergence of IL-17+IFN-γ+ double producers. Furthermore, the addition of IL-2 to in vitro cultures of sorted γδT-17 cells was able to moderate IL-17 and affect differentiation into polyfunctional cytokine-producing cells. Interestingly, the Vγ6+ subset was more susceptible to the effects of IL-2 than Vγ4+ γδT-17 cells. We also found that unlike other γδ T cells, γδT-17 cells do not produce IL-2, but express Blimp-1, a known transcriptional repressor of IL-2. Although IL-2 was able to induce robust proliferation of γδT-17 cells, it did not sustain viability, negatively impacting their survival via downregulation of the IL-7R. Taken together, these data indicate that IL-2 can augment the γδT-17 response in favor of short-lived effectors with limited plasticity, particularly in the presence of IL-1ß and IL-23. In this way, IL-2 may act to curtail the innate-like response of γδT-17 cells upon arrival of IL-2-producing adaptive immune cells at the site of inflammation.


Assuntos
Interleucina-17/biossíntese , Interleucina-2/imunologia , Interleucina-2/metabolismo , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Linfócitos T/imunologia , Animais , Diferenciação Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Citocinas/biossíntese , Citometria de Fluxo , Inflamação , Interferon gama/biossíntese , Interferon gama/imunologia , Interleucina-17/imunologia , Interleucina-2/deficiência , Interleucina-2/genética , Interleucina-23/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Fator 1 de Ligação ao Domínio I Regulador Positivo , Receptores de Interleucina-7/genética , Transdução de Sinais , Linfócitos T/efeitos dos fármacos , Linfócitos T/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
18.
Immunol Cell Biol ; 95(9): 775-788, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28611475

RESUMO

Inherited mutations in lipopolysaccharide-responsive beige-like anchor (LRBA) cause a recessive human immune dysregulation syndrome with memory B-cell and antibody deficiency (common variable immunodeficiency), inflammatory bowel disease, enlarged spleen and lymph nodes, accumulation of activated T cells and multiple autoimmune diseases. To understand the pathogenesis of the syndrome, C57BL/6 mice carrying a homozygous truncating mutation in Lrba were produced using CRISPR/Cas9-mediated gene targeting. These mice revealed that LRBA has a critical, cell-autonomous role in promoting cytotoxic T-lymphocyte antigen-4 (CTLA-4) accumulation within CD4 effector T cells and FOXP3+ T-regulatory cells (Tregs). In young mice, or in chimeric mice where only half of the T cells are LRBA deficient, low CTLA-4 was the only detectable abnormality in Tregs, whereas in old mice FOXP3 was also decreased. Low CTLA-4 did not translate into increased CD86 on B cells unless the LRBA-deficient mice were immunised, and neither immunisation nor chronic lymphocytic choriomeningitis virus infection precipitated immune dysregulation. LRBA deficiency did not alter antigen-specific B-cell activation, germinal centre (GC) formation, isotype switching or affinity maturation. Paradoxically, CD86 was decreased on GC B cells in LRBA-deficient mice, pointing to compensatory mechanisms for controlling CD86 in the face of low CTLA-4. These results add to the experimental rationale for treating LRBA deficiency with the CTLA4-Ig fusion protein, Abatacept, and pose questions about the limitations of laboratory experiments in mice to reproduce human disease in natura.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Antígeno CTLA-4/metabolismo , Imunodeficiência de Variável Comum/imunologia , Coriomeningite Linfocítica/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Reguladores/imunologia , Abatacepte/uso terapêutico , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Antígeno B7-2/metabolismo , Antígeno CTLA-4/genética , Células Cultivadas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Imunodeficiência de Variável Comum/tratamento farmacológico , Imunodeficiência de Variável Comum/genética , Fatores de Transcrição Forkhead/metabolismo , Humanos , Imunossupressores/uso terapêutico , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout
19.
Proc Natl Acad Sci U S A ; 114(22): 5677-5682, 2017 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-28507145

RESUMO

Immune therapy is rapidly gaining prominence in the clinic as a major weapon against cancer. Whereas much attention has been focused on the infiltration of tumors by immune cells, the subsequent fate of these infiltrates remains largely unexplored. We therefore established a photoconversion-based model that allowed us to label tumor-infiltrating immune cells and follow their migration. Using this system, we identified a population of tumor-experienced cells that emigrate from primary tumors to draining lymph nodes via afferent lymphatic vessels. Although the majority of tumor-infiltrating cells were myeloid, T cells made up the largest population of tumor-egressing leukocytes. Strikingly, the subset composition of tumor-egressing T cells was greatly skewed compared with those that had infiltrated the tumor and those resident in the draining lymph node. Some T-cell subsets such as CD8+ T cells emigrated more readily; others including CD4-CD8- T cells were preferentially retained, suggesting that specific mechanisms guide immune cell egress from tumors. Furthermore, tumor-egressing T cells were more activated and displayed enhanced effector function in comparison with their lymph node counterparts. Finally, we demonstrated that tumor-infiltrating T cells migrate to distant secondary tumors and draining lymph nodes, highlighting a mechanism whereby tumor-experienced effector T cells may mediate antitumor immunity at metastatic sites. Thus, our results provide insights into migration and function of tumor-infiltrating immune cells and the role of these cells in tumor immunity outside of primary tumor deposits.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Carcinoma Pulmonar de Lewis/imunologia , Movimento Celular/imunologia , Ativação Linfocitária/imunologia , Linfócitos do Interstício Tumoral/imunologia , Linfócitos T Reguladores/imunologia , Animais , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Imunoterapia Adotiva/métodos , Linfonodos/citologia , Linfonodos/imunologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/imunologia
20.
J Exp Med ; 214(5): 1259-1267, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28363897

RESUMO

Plasma cells (PCs) derived from germinal centers (GCs) secrete the high-affinity antibodies required for long-term serological immunity. Nevertheless, the process whereby GC B cells differentiate into PCs is uncharacterized, and the mechanism underlying the selective PC differentiation of only high-affinity GC B cells remains unknown. In this study, we show that differentiation into PCs is induced among a discrete subset of high-affinity B cells residing within the light zone of the GC. Initiation of differentiation required signals delivered upon engagement with intact antigen. Signals delivered by T follicular helper cells were not required to initiate differentiation but were essential to complete the differentiation process and drive migration of maturing PCs through the dark zone and out of the GC. This bipartite or two-signal mechanism has likely evolved to both sustain protective immunity and avoid autoantibody production.


Assuntos
Antígenos de Diferenciação de Linfócitos B/fisiologia , Linfócitos B/fisiologia , Diferenciação Celular/fisiologia , Centro Germinativo/fisiologia , Plasmócitos/fisiologia , Linfócitos T Auxiliares-Indutores/fisiologia , Animais , Camundongos , Camundongos Endogâmicos C57BL
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