RESUMEN
Context: Although calorie restriction has proven beneficial for weight loss, long-term weight control is variable between individuals. Objective: To identify biomarkers of successful weight control during a dietary intervention (DI). Design, Setting, and Participants: Adipose tissue (AT) transcriptomes were compared between 21 obese individuals who either maintained weight loss or regained weight during the DI. Results were validated on 310 individuals from the same study using quantitative reverse transcription polymerase chain reaction and protein levels of potential circulating biomarkers measured by enzyme-linked immunosorbent assay. Intervention: Individuals underwent 8 weeks of low-calorie diet, then 6 months of ad libitum diet. Outcome Measure: Weight changes at the end of the DI. Results: We evaluated six genes that had altered expression during DI, encode secreted proteins, and have not previously been implicated in weight control (EGFL6, FSTL3, CRYAB, TNMD, SPARC, IGFBP3), as well as genes for which baseline expression differed between those with good and poor weight control (ASPN, USP53). Changes in plasma concentrations of EGFL6, FSTL3, and CRYAB mirrored AT messenger RNA expression; all decreased during DI in individuals with good weight control. ASPN and USP53 had higher baseline expression in individuals who went on to have good weight control. Expression quantitative trait loci analysis found polymorphisms associated with expression levels of USP53 in AT. A regulatory network was identified in which transforming growth factor ß1 (TGF-ß1) was responsible for downregulation of certain genes during DI in good controllers. Interestingly, ASPN is a TGF-ß1 inhibitor. Conclusions: We found circulating biomarkers associated with weight control that could influence weight management strategies and genes that may be prognostic for successful weight control.
Asunto(s)
Restricción Calórica , Obesidad/dietoterapia , ARN Mensajero/metabolismo , Grasa Subcutánea/metabolismo , Adulto , Biomarcadores/metabolismo , Proteínas de Unión al Calcio , Moléculas de Adhesión Celular , Regulación hacia Abajo , Ensayo de Inmunoadsorción Enzimática , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Proteínas Relacionadas con la Folistatina/genética , Proteínas Relacionadas con la Folistatina/metabolismo , Perfilación de la Expresión Génica , Redes Reguladoras de Genes , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Masculino , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Análisis por Micromatrices , Persona de Mediana Edad , Obesidad/genética , Obesidad/metabolismo , Osteonectina/genética , Osteonectina/metabolismo , Polimorfismo Genético , Sitios de Carácter Cuantitativo , Reacción en Cadena en Tiempo Real de la Polimerasa , Factor de Crecimiento Transformador beta1/metabolismo , Proteasas Ubiquitina-Específicas/genética , Proteasas Ubiquitina-Específicas/metabolismo , Cadena B de alfa-Cristalina/genética , Cadena B de alfa-Cristalina/metabolismoRESUMEN
AIMS/HYPOTHESIS: Activation of macrophages by fatty acids (FAs) is a potential mechanism linking obesity to adipose tissue (AT) inflammation and insulin resistance. Here, we investigated the effects of FAs released during adipocyte lipolysis on AT macrophages (ATMs). METHODS: Human THP-1 macrophages were treated with media from human multipotent adipose-derived stem (hMADS) adipocytes stimulated with lipolytic drugs. Macrophages were also treated with mixtures of FAs and an inhibitor of Toll-like receptor 4, since this receptor is activated by saturated FAs. Levels of mRNA and the secretion of inflammation-related molecules were measured in macrophages. FA composition was determined in adipocytes, conditioned media and macrophages. The effect of chronic inhibition or acute activation of fat cell lipolysis on ATM response was investigated in vivo in mice. RESULTS: Whereas palmitic acid alone activates THP-1, conditioned media from hMADS adipocyte lipolysis had no effect on IL, chemokine and cytokine gene expression, and secretion by macrophages. Mixtures of FAs representing de novo lipogenesis or habitual dietary conditions also had no effect. FAs derived from adipocyte lipolysis were taken up by macrophages and stored as triacylglycerol droplets. In vivo, chronic treatment with an antilipolytic drug did not modify gene expression and number of ATMs in mice with intact or defective Tlr4. Stimulation of adipocyte lipolysis increased storage of neutral lipids by macrophages without change in number and phenotype. CONCLUSIONS/INTERPRETATION: Our data suggest that adipocyte lipolysis does not activate inflammatory pathways in ATMs, which instead may act as scavengers of FAs.
Asunto(s)
Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Ácidos Grasos/metabolismo , Lipólisis/fisiología , Macrófagos/metabolismo , Triglicéridos/metabolismo , Adipocitos/citología , Tejido Adiposo/citología , Agonistas de Receptores Adrenérgicos beta 3/farmacología , Animales , Línea Celular , Dioxoles/farmacología , Ácidos Grasos/farmacología , Humanos , Inflamación/metabolismo , Macrófagos/citología , Macrófagos/efectos de los fármacos , Masculino , Ratones , Ratones Noqueados , Ácido Palmítico/farmacología , Células Madre/citología , Células Madre/metabolismo , Receptor Toll-Like 4/antagonistas & inhibidores , Receptor Toll-Like 4/genética , Receptor Toll-Like 4/metabolismoRESUMEN
An uncontrolled exaggerated Th17 response can drive the onset of autoimmune and inflammatory diseases. In this study, we show that, in T cells, Foxo1 is a negative regulator of the Th17 program. Using mixed bone marrow chimeras and Foxo1-deficient mice, we demonstrate that this control is effective in vivo, as well as in vitro during differentiation assays of naive T cells with specific inhibitor of Foxo1 or inhibitors of the PI3K/Akt pathway acting upstream of Foxo1. Consistently, expressing this transcription factor in T cells strongly decreases Th17 generation in vitro as well as transcription of both IL-17A and IL-23R RORγt-target genes. Finally, at the molecular level, we demonstrate that Foxo1 forms a complex with RORγt via its DNA binding domain to inhibit RORγt activity. We conclude that Foxo1 is a direct antagonist of the RORγt-Th17 program acting in a T cell-intrinsic manner.
Asunto(s)
Factores de Transcripción Forkhead/metabolismo , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Subgrupos de Linfocitos T/metabolismo , Células Th17/metabolismo , Animales , Diferenciación Celular/genética , Línea Celular , Proteína Forkhead Box O1 , Factores de Transcripción Forkhead/deficiencia , Factores de Transcripción Forkhead/genética , Humanos , Inmunofenotipificación , Interleucina-17/genética , Interleucina-17/metabolismo , Recuento de Linfocitos , Ratones , Ratones Noqueados , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/antagonistas & inhibidores , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/química , Fenotipo , Fosfatidilinositol 3-Quinasas/metabolismo , Regiones Promotoras Genéticas , Dominios y Motivos de Interacción de Proteínas , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Células Th17/citología , Células Th17/inmunología , Transcripción GenéticaRESUMEN
Adipose tissue fibrosis development blocks adipocyte hypertrophy and favors ectopic lipid accumulation. Here, we show that adipose tissue fibrosis is associated with obesity and insulin resistance in humans and mice. Kinetic studies in C3H mice fed a high-fat diet show activation of macrophages and progression of fibrosis along with adipocyte metabolic dysfunction and death. Adipose tissue fibrosis is attenuated by macrophage depletion. Impairment of Toll-like receptor 4 signaling protects mice from obesity-induced fibrosis. The presence of a functional Toll-like receptor 4 on adipose tissue hematopoietic cells is necessary for the initiation of adipose tissue fibrosis. Continuous low-dose infusion of the Toll-like receptor 4 ligand, lipopolysaccharide, promotes adipose tissue fibrosis. Ex vivo, lipopolysaccharide-mediated induction of fibrosis is prevented by antibodies against the profibrotic factor TGFß1. Together, these results indicate that obesity and endotoxemia favor the development of adipose tissue fibrosis, a condition associated with insulin resistance, through immune cell Toll-like receptor 4.