RESUMEN
Developing new influenza vaccines with improved performance and easier administration routes hinges on defining correlates of protection. Vaccine-elicited cellular correlates of protection for influenza in humans have not yet been demonstrated. A phase-2 double-blind randomized placebo and active (inactivated influenza vaccine) controlled study provides evidence that a human-adenovirus-5-based oral influenza vaccine tablet (VXA-A1.1) can protect from H1N1 virus challenge in humans. Mass cytometry characterization of vaccine-elicited cellular immune responses identified shared and vaccine-type-specific responses across B and T cells. For VXA-A1.1, the abundance of hemagglutinin-specific plasmablasts and plasmablasts positive for integrin α4ß7, phosphorylated STAT5, or lacking expression of CD62L at day 8 were significantly correlated with protection from developing viral shedding following virus challenge at day 90 and contributed to an effective machine learning model of protection. These findings reveal the characteristics of vaccine-elicited cellular correlates of protection for an oral influenza vaccine.
Asunto(s)
Inmunidad , Vacunas contra la Influenza/inmunología , Gripe Humana/inmunología , Vacunación , Método Doble Ciego , Humanos , Inmunidad Celular , Inmunización , Subtipo H1N1 del Virus de la Influenza A , Virus de la Influenza A , Gripe Humana/prevención & control , Selectina L/metabolismo , Factor de Transcripción STAT5/metabolismo , Linfocitos T , Vacunas de Productos Inactivados/inmunología , Esparcimiento de VirusRESUMEN
BACKGROUND: Influenza is an important public health problem and existing vaccines are not completely protective. New vaccines that protect by alternative mechanisms are needed to improve efficacy of influenza vaccines. In 2015, we did a phase 1 trial of an oral influenza vaccine, VXA-A1.1. A favourable safety profile and robust immunogenicity results in that trial supported progression of the vaccine to the current phase 2 trial. The aim of this study was to evaluate efficacy of the vaccine in a human influenza challenge model. METHODS: We did a single-site, placebo-controlled and active-controlled, phase 2 study at WCCT Global, Costa Mesa, CA, USA. Eligible individuals had an initial A/California/H1N1 haemagglutination inhibition titre of less than 20 and were aged 18-49 years and in good health. Individuals were randomly assigned (2:2:1) to receive a single immunisation of either 1011 infectious units of VXA-A1.1 (a monovalent tablet vaccine) orally, a full human dose of quadrivalent inactivated influenza vaccine (IIV) via intramuscular injection, or matched placebo. Randomisation was done by computer-generated assignments with block size of five. An unmasked pharmacist provided the appropriate vaccines and placebos to the administrating nurse. Individuals receiving the treatments, investigators, and staff were all masked to group assignments. 90 days after immunisation, individuals without clinically significant symptoms or signs of influenza, an oral temperature of higher than 37·9°C, a positive result for respiratory viral shedding on a Biofire test, and any investigator-assessed contraindications were challenged intranasally with 0·5 mL wild-type A/CA/like(H1N1)pdm09 influenza virus. The primary outcomes were safety, which was assessed in all immunised participants through 365 days, and influenza-positive illness after viral challenge, which was assessed in individuals that received the viral challenge and the required number of assessments post viral challenge. This trial is registered with ClinicalTrials.gov, number NCT02918006. RESULTS: Between Aug 31, 2016, and Jan 23, 2017, 374 individuals were assessed for eligibility, of whom 179 were randomly assigned to receive either VXA-A1.1 (n=71 [one individual did not provide a diary card, thus the solicited events were assessed in 70 individuals]), IIV (n=72), or placebo (n=36). Between Dec 2, 2016, and April 26, 2017, 143 eligible individuals (58 in the VXA-A1.1 group, 54 in the IIV group, and 31 in the placebo group) were challenged with influenza virus. VXA-A1.1 was well tolerated with no serious or medically significant adverse events. The most prevalent solicited adverse events for each of the treatment groups after immunisation were headache in the VXA-A1.1 (in five [7%] of 70 participants) and placebo (in seven [19%] of 36 participants) groups and tenderness at injection site in the IIV group (in 19 [26%] of 72 participants) Influenza-positive illness after challenge was detected in 17 (29%) of 58 individuals in the VXA-A1.1 group, 19 (35%) of 54 in the IIV group, and 15 (48%) of 31 in the placebo group. INTERPRETATION: Orally administered VXA-A1.1 was well tolerated and generated protective immunity against virus shedding, similar to a licensed intramuscular IIV. These results represent a major step forward in developing a safe and effective oral influenza vaccine. FUNDING: Department of Health and Human Services, Office of the Assistant Secretary for Preparedness and Response, and Biomedical Advanced Research and Development Authority.
Asunto(s)
Administración Oral , Inmunogenicidad Vacunal , Subtipo H1N1 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza , Seguridad , Adulto , Método Doble Ciego , Femenino , Cefalea/etiología , Voluntarios Sanos , Humanos , Vacunas contra la Influenza/inmunología , Vacunas contra la Influenza/uso terapéutico , Gripe Humana/inmunología , Gripe Humana/prevención & control , Masculino , Persona de Mediana Edad , Placebos , VacunaciónRESUMEN
Dysregulated germinal center (GC) responses are implicated in the pathogenesis of human autoimmune diseases, including systemic lupus erythematosus (SLE). Although both type 1 and type 2 interferons (IFNs) are involved in lupus pathogenesis, their respective impacts on the establishment of autoimmune GCs has not been addressed. In this study, using a chimeric model of B cell-driven autoimmunity, we demonstrate that B cell type 1 IFN receptor signals accelerate, but are not required for, lupus development. In contrast, B cells functioning as antigen-presenting cells initiate CD4(+) T cell activation and IFN-γ production, and strikingly, B cell-intrinsic deletion of the IFN-γ receptor (IFN-γR) abrogates autoimmune GCs, class-switched autoantibodies (auto-Abs), and systemic autoimmunity. Mechanistically, although IFN-γR signals increase B cell T-bet expression, B cell-intrinsic deletion of T-bet exerts an isolated impact on class-switch recombination to pathogenic auto-Ab subclasses without impacting GC development. Rather, in both mouse and human B cells, IFN-γ synergized with B cell receptor, toll-like receptor, and/or CD40 activation signals to promote cell-intrinsic expression of the GC master transcription factor, B cell lymphoma 6 protein. Our combined findings identify a novel B cell-intrinsic mechanism whereby IFN signals promote lupus pathogenesis, implicating this pathway as a potential therapeutic target in SLE.
Asunto(s)
Linfocitos B/inmunología , Centro Germinal/inmunología , Lupus Eritematoso Sistémico/inmunología , Proteínas Proto-Oncogénicas c-bcl-6/inmunología , Receptores de Interferón/inmunología , Transducción de Señal/inmunología , Animales , Autoanticuerpos/inmunología , Linfocitos B/patología , Centro Germinal/patología , Interferón gamma/genética , Interferón gamma/inmunología , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/patología , Masculino , Ratones , Ratones Noqueados , Proteínas Proto-Oncogénicas c-bcl-6/genética , Receptores de Interferón/genética , Transducción de Señal/genética , Receptores Toll-Like/genética , Receptores Toll-Like/inmunología , Receptor de Interferón gammaRESUMEN
Mice overexpressing B cell activating factor of the TNF family (BAFF) develop systemic autoimmunity characterized by class-switched anti-nuclear Abs. Transmembrane activator and CAML interactor (TACI) signals are critical for BAFF-mediated autoimmunity, but the B cell developmental subsets undergoing TACI-dependent activation in settings of excess BAFF remain unclear. We report that, although surface TACI expression is usually limited to mature B cells, excess BAFF promotes the expansion of TACI-expressing transitional B cells. TACI(+) transitional cells from BAFF-transgenic mice are characterized by an activated, cycling phenotype, and the TACI(+) cell subset is specifically enriched for autoreactivity, expresses activation-induced cytidine deaminase and T-bet, and exhibits evidence of somatic hypermutation. Consistent with a potential contribution to BAFF-mediated humoral autoimmunity, TACI(+) transitional B cells from BAFF-transgenic mice spontaneously produce class-switched autoantibodies ex vivo. These combined findings highlight a novel mechanism through which BAFF promotes humoral autoimmunity via direct, TACI-dependent activation of transitional B cells.
Asunto(s)
Autoanticuerpos/biosíntesis , Factor Activador de Células B/metabolismo , Células Precursoras de Linfocitos B/inmunología , Proteína Activadora Transmembrana y Interactiva del CAML/metabolismo , Animales , Autoanticuerpos/inmunología , Autoinmunidad , Factor Activador de Células B/genética , Subgrupos de Linfocitos B/inmunología , Activación de Linfocitos , Ratones , Ratones Transgénicos , Células Precursoras de Linfocitos B/fisiología , Proteína Activadora Transmembrana y Interactiva del CAML/genéticaRESUMEN
The establishment of a diverse B cell repertoire requires fine-tuning of antigen receptor selection during development in order to permit sufficient diversity while reducing the potential for autoimmunity. In this review, we highlight recent studies demonstrating the central role of the B cell antigen receptor (BCR), in coordination with other key pro-survival signals mediated by CD40, BAFF-R, TACI and/or TLRs, in regulating both negative and positive selection of autoreactive B cells. In particular, we show how altered antigen or co-stimulatory signaling can facilitate positive selection of transitional B cells with self-reactive BCRs, ultimately leading to their entry into the mature, naive B cell compartment. We propose a model wherein altered receptor signals (due to inherited genetic changes) leads: first, to enhanced positive selection of autoreactive cells into the naïve B cell repertoire; subsequently, to an increased probability of pathogenic germinal center responses in individuals with a broad range of autoimmune disorders.
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Linfocitos B/inmunología , Centro Germinal/fisiología , Receptor Cross-Talk , Receptores de Antígenos de Linfocitos B/metabolismo , Animales , Autoantígenos/inmunología , Autoinmunidad/genética , Diferenciación Celular/genética , Selección Clonal Mediada por Antígenos , Humanos , Mutación/genética , Transducción de Señal/genéticaRESUMEN
Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency disorder frequently associated with systemic autoimmunity, including autoantibody-mediated cytopenias. WAS protein (WASp)-deficient B cells have increased B cell receptor (BCR) and Toll-like receptor (TLR) signaling, suggesting that these pathways might impact establishment of the mature, naive BCR repertoire. To directly investigate this possibility, we evaluated naive B cell specificity and composition in WASp-deficient mice and WAS subjects (n = 12). High-throughput sequencing and single-cell cloning analysis of the BCR repertoire revealed altered heavy chain usage and enrichment for low-affinity self-reactive specificities in murine marginal zone and human naive B cells. Although negative selection mechanisms including deletion, anergy, and receptor editing were relatively unperturbed, WASp-deficient transitional B cells showed enhanced proliferation in vivo mediated by antigen- and Myd88-dependent signals. Finally, using both BCR sequencing and cell surface analysis with a monoclonal antibody recognizing an intrinsically autoreactive heavy chain, we show enrichment in self-reactive cells specifically at the transitional to naive mature B cell stage in WAS subjects. Our combined data support a model wherein modest alterations in B cell-intrinsic, BCR, and TLR signals in WAS, and likely other autoimmune disorders, are sufficient to alter B cell tolerance via positive selection of self-reactive transitional B cells.
Asunto(s)
Linfocitos B/metabolismo , Linfocitos B/patología , Receptores de Antígenos de Linfocitos B/metabolismo , Receptores Toll-Like/metabolismo , Síndrome de Wiskott-Aldrich/metabolismo , Adolescente , Adulto , Animales , Factor Activador de Células B/sangre , Linfocitos B/inmunología , Estudios de Casos y Controles , Niño , Preescolar , Citoprotección , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Lactante , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Factor 88 de Diferenciación Mieloide/metabolismo , Síndrome de Wiskott-Aldrich/inmunología , Síndrome de Wiskott-Aldrich/patología , Proteína del Síndrome de Wiskott-Aldrich/genética , Proteína del Síndrome de Wiskott-Aldrich/metabolismo , Adulto JovenRESUMEN
Patients with Wiskott-Aldrich syndrome (WAS) exhibit prominent defects in splenic marginal zone (MZ), resulting in abnormal T-cell-independent antibody responses and increased bacterial infections. B-cell-intrinsic deletion of the affected gene WAS protein (WASp) markedly reduces splenic MZ B cells, without impacting the rate of MZ B-cell development, suggesting that abnormal B-cell retention within the MZ accounts for MZ defects in WAS. Since WASp regulates integrin-dependent actin cytoskeletal rearrangement, we previously hypothesized that defective B-cell integrin function promotes MZ depletion. In contrast, we now report that B-cell-intrinsic deletion of the TLR signaling adaptor MyD88 is sufficient to restore the MZ in WAS. We further identify TLR7, an endosomal single-stranded RNA (ssRNA) receptor, as the MyD88-dependent receptor responsible for WAS MZ depletion. These findings implicate spontaneous activation of MZ B cells by ssRNA-containing self-ligands (likely derived from circulating apoptotic material) as the mechanism underlying MZ depletion in WAS. Together, these data suggest a previously unappreciated role for B-cell intrinsic TLR signals in MZ homeostasis, of relevance to both pathogen responses and to the development of systemic autoimmunity.
Asunto(s)
Linfocitos B/inmunología , Glicoproteínas de Membrana/inmunología , Transducción de Señal/inmunología , Bazo/inmunología , Receptor Toll-Like 7/inmunología , Síndrome de Wiskott-Aldrich/inmunología , Animales , Linfocitos B/patología , Citoesqueleto/genética , Citoesqueleto/inmunología , Modelos Animales de Enfermedad , Integrinas/genética , Integrinas/inmunología , Depleción Linfocítica , Glicoproteínas de Membrana/genética , Ratones , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/inmunología , Transducción de Señal/genética , Bazo/patología , Receptor Toll-Like 7/genética , Síndrome de Wiskott-Aldrich/genética , Síndrome de Wiskott-Aldrich/patologíaRESUMEN
A significant proportion of autoimmune-associated genetic variants are expressed in B cells, suggesting that B cells may play multiple roles in autoimmune pathogenesis. In this review, we highlight recent studies demonstrating that even modest alterations in B cell signaling are sufficient to promote autoimmunity. First, we describe several examples of genetic variations promoting B cell-intrinsic initiation of autoimmune germinal centers and autoantibody production. We highlight how dual antigen receptor/toll-like receptor signals greatly facilitate this process and how activated, self-reactive B cells may function as antigen presenting cells, leading to loss of T cell tolerance. Further, we propose that B cell-derived cytokines may initiate and/or sustain autoimmune germinal centers, likely also contributing, in parallel, to programing of self-reactive T cells.
Asunto(s)
Linfocitos B/inmunología , Linfocitos B/metabolismo , Animales , Presentación de Antígeno/inmunología , Autoanticuerpos/inmunología , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/metabolismo , Autoinmunidad/inmunología , Linfocitos B/citología , Citocinas/metabolismo , Centro Germinal/inmunología , Centro Germinal/metabolismo , Humanos , Tolerancia Inmunológica , Transducción de SeñalRESUMEN
Control of peripheral B cell development and homeostasis depends critically on coordinate signals received through the BAFFRs and BCRs. The extent to which other signals contribute to this process, however, remains undefined. We present data indicating that CD4(+) T cells directly influence naive B cell development via CD40 signaling. Loss of CD4(+) T cells or CD40-CD40L interaction leads to reduced B cell homeostatic proliferation and hindered B cell reconstitution posttransplantation. Furthermore, we demonstrate that in the absence of CD40 signals, these events are modulated by BCR self-reactivity. Strikingly, murine models lacking CD40 reveal a broadly altered BCR specificity and limited diversity by both single-cell cloning and high-throughput sequencing techniques. Collectively, our results imply that any setting of T cell lymphopenia or reduced CD40 function, including B cell recovery following transplantation, will impact the naive B cell repertoire.
Asunto(s)
Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Antígenos CD40/inmunología , Homeostasis/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Transducción de Señal/inmunología , Animales , Linfocitos B/patología , Linfocitos T CD4-Positivos/patología , Antígenos CD40/genética , Homeostasis/genética , Linfopenia/genética , Linfopenia/inmunología , Linfopenia/patología , Ratones , Ratones Noqueados , Receptores de Antígenos de Linfocitos B/genética , Transducción de Señal/genéticaRESUMEN
Systemic lupus erythematosus is a multisystem autoimmune disease characterized by autoantibodies targeting nucleic acid-associated Ags. The endosomal TLRs TLR7 and TLR9 are critical for generation of Abs targeting RNA- or DNA-associated Ags, respectively. In murine lupus models, deletion of TLR7 limits autoimmune inflammation, whereas deletion of TLR9 exacerbates disease. Whether B cell or myeloid TLR7/TLR9 signaling is responsible for these effects has not been fully addressed. In this study, we use a chimeric strategy to evaluate the effect of B cell-intrinsic deletion of TLR7 versus TLR9 in parallel lupus models. We demonstrate that B cell-intrinsic TLR7 deletion prevents RNA-associated Ab formation, decreases production of class-switched Abs targeting nonnuclear Ags, and limits systemic autoimmunity. In contrast, B cell-intrinsic TLR9 deletion results in decreased DNA-reactive Ab, but increased Abs targeting a broad range of systemic autoantigens. Further, we demonstrate that B cell-intrinsic TLR9 deletion results in increased systemic inflammation and immune complex glomerulonephritis, despite intact TLR signaling within the myeloid compartment. These data stress the critical importance of dysregulated B cell-intrinsic TLR signaling in the pathogenesis of systemic lupus erythematosus.