RESUMEN
OBJECTIVE: To determine whether synovial fluid (SF) levels and cell-surface expression of B lymphocyte stimulator (BLyS) protein and SF levels of APRIL are elevated in patients with inflammatory arthritis (IA). METHODS: Same-day blood and SF samples from 89 patients with 103 knee effusions (81 knees with IA and 22 with noninflammatory arthritis [NIA]) were evaluated for BLyS protein and APRIL levels by enzyme-linked immunosorbent assay. Blood and SF mononuclear cells were double-stained for surface BLyS protein and surface CD14 (monocyte marker) and were analyzed by flow cytometry. Complete blood cell counts and SF nucleated cell counts were performed by the clinical hematology laboratory. RESULTS: BLyS protein levels were higher in SF than in corresponding serum samples from both IA and NIA patients. SF BLyS protein levels, but not surface expression of BLyS protein, were disproportionately elevated in IA patients. APRIL levels were higher in SF than in corresponding serum samples from most IA patients but not NIA patients. SF BLyS protein and APRIL levels correlated with each other, and each correlated with SF monocyte, lymphocyte, neutrophil, and total nucleated cell counts. Although SF and serum BLyS protein levels correlated with each other, SF and serum APRIL levels did not, suggesting that SF BLyS protein levels are more dependent upon systemic factors than are SF APRIL levels. Moreover, in 8 patients who underwent sequential arthrocenteses, changes in SF BLyS protein levels did not immutably parallel changes in SF APRIL levels, indicating their differential regulation. CONCLUSION: BLyS protein and APRIL are locally produced in inflamed joints. Their respective SF levels are differentially regulated, suggesting that they serve different functions. Together, their local production may foster survival and/or expansion of B cells that produce pathogenic autoantibodies and/or promote local T cell activation and consequent joint destruction.
Asunto(s)
Artritis Reumatoide/metabolismo , Articulación de la Rodilla/metabolismo , Proteínas de la Membrana/metabolismo , Neuropéptidos/metabolismo , Proteínas Nucleares/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Factor Activador de Células B , Recuento de Células , Ensayo de Inmunoadsorción Enzimática , Femenino , Citometría de Flujo , Humanos , Receptores de Lipopolisacáridos/metabolismo , Masculino , Persona de Mediana Edad , Monocitos/citología , Monocitos/metabolismo , Líquido Sinovial/citología , Líquido Sinovial/metabolismoRESUMEN
A coordinated effort combining bioinformatic tools with high-throughput cell-based screening assays was implemented to identify novel factors involved in T-cell biology. We generated a unique library of cDNAs encoding predicted secreted and transmembrane domain-containing proteins generated by analyzing the Human Genome Sciences cDNA database with a combination of two algorithms that predict signal peptides. Supernatants from mammalian cells transiently transfected with this library were incubated with primary T cells and T-cell lines in several high-throughput assays. Here we describe the discovery of a T cell factor, TIP (T cell immunomodulatory protein), which does not show any homology to proteins with known function. Treatment of primary human and murine T cells with TIP in vitro resulted in the secretion of IFN-gamma, TNF-alpha, and IL-10, whereas in vivo TIP had a protective effect in a mouse acute graft-versus-host disease (GVHD) model. Therefore, combining functional genomics with high-throughput cell-based screening is a valuable and efficient approach to identifying immunomodulatory activities for novel proteins.
Asunto(s)
Enfermedad Injerto contra Huésped/tratamiento farmacológico , Análisis de Secuencia de Proteína/métodos , Factores Supresores Inmunológicos/administración & dosificación , Factores Supresores Inmunológicos/química , Linfocitos T/metabolismo , Adyuvantes Inmunológicos/química , Adyuvantes Inmunológicos/genética , Adyuvantes Inmunológicos/metabolismo , Animales , Línea Celular , Perfilación de la Expresión Génica/métodos , Enfermedad Injerto contra Huésped/inmunología , Enfermedad Injerto contra Huésped/metabolismo , Humanos , Riñón/química , Riñón/embriología , Riñón/inmunología , Ratones/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Proteínas Recombinantes de Fusión/metabolismo , Factores Supresores Inmunológicos/genética , Factores Supresores Inmunológicos/inmunología , Especificidad del Receptor de Antígeno de Linfocitos T/genética , Linfocitos T/química , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunología , Transfección/métodosRESUMEN
DR3 is a death domain-containing receptor that is upregulated during T cell activation and whose overexpression induces apoptosis and NF-kappaB activation in cell lines. Here we show that an endothelial cell-derived TNF-like factor, TL1A, is a ligand for DR3 and decoy receptor TR6/DcR3 and that its expression is inducible by TNF and IL-1alpha. TL1A induces NF-kappaB activation and apoptosis in DR3-expressing cell lines, while TR6-Fc protein antagonizes these signaling events. Interestingly, in T cells, TL1A acts as a costimulator that increases IL-2 responsiveness and secretion of proinflammatory cytokines both in vitro and in vivo. Our data suggest that interaction of TL1A with DR3 promotes T cell expansion during an immune response, whereas TR6 has an opposing effect.