RESUMEN
INTRODUCTION: The development of biomarkers to guide management of anti-tumor necrosis factor (TNF) agents in patients with inflammatory bowel disease (IBD) is an unmet need. We developed an in vitro blood assay to predict patient long-term outcome with the anti-TNFα agent infliximab (IFX). METHODS: Patients with IBD were classified according to the shedding of an L-selectin (CD62L) from the surface of their granulocytes in whole blood. CD62L shedding was quantified by flow cytometry before and after drug administration. A clinical data collection from June 2012 to August 2017 with blinded IFX management was aimed at validating the long-term predictive value of this test. RESULTS: Among 33 patients with IBD (17 Crohn's disease and 5 ulcerative colitis), 22 were predicted functional responders (PFR) and 11 were predicted as nonresponders (NR) according to the in vitro test. Five years after study initiation, 72% of PFR were still treated with IFX (vs 27% in the NR group; P < 0.05), with a median time spent under IFX of 45 vs 12 months (P = 0.019), respectively. Thirty-five medicosurgical events occurred with a median time to first event of 3 vs 30 months (P = 0.023), respectively. Our assay was the best independent predictor of staying long term on IFX (P = 0.056). DISCUSSION: An assay-based in vitro test for functional blockade of TNFα (CD62L shedding) provides an excellent long-term (at 3-5 years) independent predictor of durable use of IFX in patients with IBD. Testing patients could personalize decision making to significantly reduce costs and risk of adverse events and complications.
Asunto(s)
Colitis Ulcerosa/tratamiento farmacológico , Enfermedad de Crohn/tratamiento farmacológico , Fármacos Gastrointestinales/uso terapéutico , Inmunoensayo/métodos , Infliximab/uso terapéutico , Selectina L/sangre , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Adulto , Anticuerpos/sangre , Biomarcadores/sangre , Colitis Ulcerosa/sangre , Femenino , Citometría de Flujo , Estudios de Seguimiento , Fármacos Gastrointestinales/inmunología , Humanos , Infliximab/inmunología , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Análisis de SupervivenciaRESUMEN
Microbial exposure following birth profoundly impacts mammalian immune system development. Microbiota alterations are associated with increased incidence of allergic and autoimmune disorders with elevated serum IgE as a hallmark. The previously reported abnormally high serum IgE levels in germ-free mice suggests that immunoregulatory signals from microbiota are required to control basal IgE levels. We report that germ-free mice and those with low-diversity microbiota develop elevated serum IgE levels in early life. B cells in neonatal germ-free mice undergo isotype switching to IgE at mucosal sites in a CD4 T-cell- and IL-4-dependent manner. A critical level of microbial diversity following birth is required in order to inhibit IgE induction. Elevated IgE levels in germ-free mice lead to increased mast-cell-surface-bound IgE and exaggerated oral-induced systemic anaphylaxis. Thus, appropriate intestinal microbial stimuli during early life are critical for inducing an immunoregulatory network that protects from induction of IgE at mucosal sites.
Asunto(s)
Biodiversidad , Tracto Gastrointestinal/microbiología , Inmunoglobulina E/sangre , Animales , Animales Recién Nacidos , Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Vida Libre de Gérmenes , Interleucina-4/inmunología , RatonesRESUMEN
We are all born germ-free. Following birth we enter into a lifelong relationship with microbes residing on our body's surfaces. The lower intestine is home to the highest microbial density in our body, which is also the highest microbial density known on Earth (up to 10(12) /g of luminal contents). With our indigenous microbial cells outnumbering our human cells by an order of magnitude our body is more microbial than human. Numerous immune adaptations confine these microbes within the mucosa, enabling most of us to live in peaceful homeostasis with our intestinal symbionts. Intestinal epithelial cells not only form a physical barrier between the bacteria-laden lumen and the rest of the body but also function as multi-tasking immune cells that sense the prevailing microbial (apical) and immune (basolateral) milieus, instruct the underlying immune cells, and adapt functionally. In the constant effort to ensure intestinal homeostasis, the immune system becomes educated to respond appropriately and in turn immune status can shape the microbial consortia. Here we review how the dynamic immune-microbial dialogue underlies maturation and regulation of the immune system and discuss recent findings on the impact of diet on both microbial ecology and immune function.
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Sistema Inmunológico/inmunología , Sistema Inmunológico/microbiología , Animales , Células Epiteliales/inmunología , Células Epiteliales/microbiología , Humanos , Intestinos/citología , Intestinos/inmunología , Intestinos/microbiologíaRESUMEN
Mammals harbor a dense commensal microbiota in the colon. Regulatory T (Treg) cells are known to limit microbe-triggered intestinal inflammation and the CD4+ T cell compartment is shaped by the presence of particular microbes or bacterial compounds. It is, however, difficult to distinguish whether these effects reflect true mutualistic immune adaptation to intestinal colonization or rather idiosyncratic immune responses. To investigate truly mutualistic CD4+ T cell adaptation, we used the altered Schaedler flora (ASF). Intestinal colonization resulted in activation and de novo generation of colonic Treg cells. Failure to activate Treg cells resulted in the induction of T helper 17 (Th17) and Th1 cell responses, which was reversed by wild-type Treg cells. Efficient Treg cell induction was also required to maintain intestinal homeostasis upon dextran sulfate sodium-mediated damage in the colon. Thus, microbiota colonization-induced Treg cell responses are a fundamental intrinsic mechanism to induce and maintain host-intestinal microbial T cell mutualism.
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Inmunidad Adaptativa , Colon/inmunología , Colon/microbiología , Linfocitos T Reguladores/inmunología , Animales , Proliferación Celular , Colon/citología , Homeostasis , Inmunidad Mucosa , Interleucina-10/inmunología , Activación de Linfocitos , Ratones , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Linfocitos T Reguladores/citologíaRESUMEN
RATIONALE: The incidence of allergic disorders is increasing in developed countries and has been associated with reduced exposure to microbes and alterations in the commensal bacterial flora. OBJECTIVES: To ascertain the relevance of commensal bacteria on the development of an allergic response, we used a model of allergic airway inflammation in germ-free (GF) mice that lack any exposure to pathogenic or nonpathogenic microorganisms. METHODS: Allergic airway inflammation was induced in GF, specific pathogen-free (SPF), or recolonized mice by sensitization and challenge with ovalbumin. The resulting cellular infiltrate and cytokine production were measured. MEASUREMENTS AND MAIN RESULTS: Our results show that the total number of infiltrating lymphocytes and eosinophils were elevated in the airways of allergic GF mice compared with control SPF mice, and that this increase could be reversed by recolonization of GF mice with the complex commensal flora of SPF mice. Exaggerated airway eosinophilia correlated with increased local production of Th2-associated cytokines, elevated IgE production, and an altered number and phenotype of conventional dendritic cells. Regulatory T-cell populations and regulatory cytokine levels were unaltered, but GF mice exhibited an increased number of basophils and decreased numbers of alveolar macrophages and plasmacytoid dendritic cells. CONCLUSIONS: These data demonstrate that the presence of commensal bacteria is critical for ensuring normal cellular maturation, recruitment, and control of allergic airway inflammation.
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Asma/inmunología , Inflamación/inmunología , Pulmón/inmunología , Metagenoma/inmunología , Animales , Asma/complicaciones , Basófilos/inmunología , Células Dendríticas/inmunología , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Eosinófilos/inmunología , Citometría de Flujo , Inmunoglobulina E/inmunología , Inflamación/complicaciones , Macrófagos Alveolares/inmunología , Ratones , Ratones Endogámicos C57BL , Ovalbúmina , Organismos Libres de Patógenos Específicos , Linfocitos T Reguladores/inmunología , Células Th2/inmunologíaRESUMEN
The lower intestine of adult mammals is densely colonized with nonpathogenic (commensal) microbes. Gut bacteria induce protective immune responses, which ensure host-microbial mutualism. The continuous presence of commensal intestinal bacteria has made it difficult to study mucosal immune dynamics. Here, we report a reversible germ-free colonization system in mice that is independent of diet or antibiotic manipulation. A slow (more than 14 days) onset of a long-lived (half-life over 16 weeks), highly specific anticommensal immunoglobulin A (IgA) response in germ-free mice was observed. Ongoing commensal exposure in colonized mice rapidly abrogated this response. Sequential doses lacked a classical prime-boost effect seen in systemic vaccination, but specific IgA induction occurred as a stepwise response to current bacterial exposure, such that the antibody repertoire matched the existing commensal content.
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Anticuerpos Antibacterianos/inmunología , Escherichia coli/crecimiento & desarrollo , Escherichia coli/inmunología , Inmunoglobulina A/inmunología , Mucosa Intestinal/inmunología , Mucosa Intestinal/microbiología , Animales , Anticuerpos Antibacterianos/biosíntesis , Especificidad de Anticuerpos , Recuento de Colonia Microbiana , Relación Dosis-Respuesta Inmunológica , Vida Libre de Gérmenes , Semivida , Inmunoglobulina A/biosíntesis , Memoria Inmunológica , Intestinos/inmunología , Intestinos/microbiología , Ratones , Ratones Endogámicos C57BL , Membrana Mucosa/inmunología , Células Plasmáticas/inmunología , Factores de TiempoRESUMEN
Progressive human immunodeficiency virus type 1 (HIV-1) infection is often associated with high plasma virus load (pVL) and impaired CD8(+) T-cell function; in contrast, CD8(+) T cells remain polyfunctional in long-term nonprogressors. However, it is still unclear whether CD8(+) T-cell dysfunction is the cause or the consequence of high pVLs. Here, we conducted a longitudinal functional and phenotypic analysis of virus-specific CD8(+) T cells in a cohort of patients with chronic HIV-1 infection. During the initiation and maintenance of successful antiretroviral therapy (ART), we assessed whether the level of pVL was associated with the degree of CD8(+) T-cell dysfunction. Under viremic conditions, HIV-specific CD8(+) T cells were dysfunctional with respect to cytokine secretion (gamma interferon, interleukin-2 [IL-2], and tumor necrosis factor alpha), and their phenotype suggested limited potential for proliferation. During ART, cytokine secretion by HIV-specific CD8(+) T cells was gradually restored, IL-7Ralpha and CD28 expression increased dramatically, and PD-1 levels declined. Thus, prolonged ART-induced reduction of viral replication and, hence, presumably antigen exposure in vivo, allows a significant functional restoration of CD8(+) T cells with the appearance of polyfunctional cells. These findings indicate that the level of pVL as a surrogate for antigen load has a dominant influence on the phenotypic and functional profile of virus-specific CD8(+) T cells.
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Fármacos Anti-VIH/uso terapéutico , Linfocitos T CD8-positivos/inmunología , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/inmunología , VIH-1/inmunología , Carga Viral , Adulto , Antígenos CD , Proteínas Reguladoras de la Apoptosis , Antígenos CD28/biosíntesis , Estudios de Cohortes , Femenino , VIH-1/efectos de los fármacos , Humanos , Interferón gamma/biosíntesis , Interleucina-2/biosíntesis , Masculino , Persona de Mediana Edad , Receptor de Muerte Celular Programada 1 , Receptores de Interleucina-7/biosíntesis , Factor de Necrosis Tumoral alfa/biosíntesisRESUMEN
In persistent viral infections, the host's immune system is challenged by the constant exposure to antigen, potentially causing continuous activation of CD8(+) T cells with subsequent immunopathology. Here we demonstrate, for experimental chronic lymphocytic choriomeningitis virus and human HIV infection, that upon prolonged in vivo exposure to antigen, TCR-triggered Ca(2+) flux, degranulation, and cytotoxicity are maintained on a cellular level, whereas cytokine production is severely impaired because of a selective defect in activation-induced NFAT nuclear translocation. During chronic infection, this differential regulation of pathways leading to diverse effector functions may allow CD8(+) T cells to sustain some degree of local viral control by direct cytotoxicity while limiting systemic immune pathology by silencing cytokine production.