Enterotoxigenic Escherichia coli Enterotoxins Regulate Epithelial to Immune Relay of IL-33 and IL-1Ra Cytokines.

Enterotoxigenic Escherichia coli (ETEC) remain a major cause of diarrheal mortality and morbidity in children in low-resource settings. Few studies have explored the consequences of simultaneous intoxication with heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT) despite the increased prevalence of wild ETEC isolates expressing both toxins. We therefore used a combination of tissue culture and murine models to explore the impact of simultaneous ST + LT intoxication on epithelial and myeloid cells. We report that LT induces sustained production of interleukin 33 (IL-33) and interleukin 1 receptor antagonist (IL-1Ra) in T84 intestinal epithelial cells via cAMP production and protein kinase A activation. We demonstrate that combined ST + LT intoxication hastens epithelial transcriptional responses induced more slowly by LT alone. ST- and LT-mediated luminal fluid accumulation in vivo correlates with significant increases in IL-33 and IL-1Ra in small intestinal mucosal scrapings. Additionally, IL-33 receptor (IL-33R)-deficient mice are significantly less susceptible to ST-mediated secretion than wildtype mice. In the immune compartment, IL-33 is sensed by myeloid cells, and LT suppresses IL-33-induced tumor necrosis factor α (TNF-α) secretion from macrophages and bone marrow-derived dendritic cells (BMDCs) but amplifies IL-33-mediated induction of IL-6 from BMDCs. In conclusion, our studies suggest that enterotoxin-induced IL-33 and IL-1Ra modulate intestinal inflammation and IL-1 receptor signaling in the intestinal mucosa in response to ETEC enterotoxins.

Role of Inflammasome Activation in Systemic Lupus Erythematosus: Are Innate Immune Cells Activated? / Rol de la activación del inflammasome en lupus eritematoso sistémico: están las células del sistema inmune innato activados?

Background: Systemic lupus erythematosus (SLE) is characterized by a wide spectrum of clinical and immunological abnormalities. New data have emerged about the role of inflammasomes in autoimmune diseases. We aimed to investigate whether basal inflammasome activation occurs in SLE patients, and whether a relationship between inflammasome-related-cytokines and disease activity exists. Methods: Fourteen (14) consecutive SLE patients and 13 healthy individuals, matched by sex, age and ethnicity, were included. Demographics, laboratory and clinical data were recorded. Peripheral blood mononuclear cells (PBMCs) from patients and controls were obtained and monocytes were isolated by negative selection. Purified monocytes were stimulated with LPS in the presence or absence of Caspase-1 inhibitor. CD14 and Caspase-1 expression were analyzed by flow cytometry. Cytokine levels were determined in plasma and culture supernatants by ELISA. Student's t test and Mann–Whitney tests were used for statistical analysis. Results: The percentage of CD14+/Caspase-1+ was significantly higher in monocytes from SLE patients compared to normal controls (p<0.01). These findings paralleled with higher plasma levels of IL-1β (p<0.05) and IL-18 (p<0.01) in those patients. Purified monocytes from SLE patients displayed a robust inflammatory response after LPS stimulation where Caspase-1, IL-1β and IL-18 were highly expressed. Plasma levels of IL-18 were also significantly higher in SLE patients with active disease (p<0.05). In addition, the production of IL-18 was reduced by 3 fold when Caspase-1 inhibitor was added to the cultures. Conclusions: Monocytes from SLE patients exhibited increased inflammasome activation, characterized by high expression of Caspase-1, IL-1β and IL-18. Caspase-1 specific inhibitor decreased inflammasome activation (in vitro) by suppressing the production of IL-18.(AU)

Introducción: El lupus eritematoso sistémico (LES) se caracteriza por presentar diversas anormalidades clínicas e inmunológicas. El ensamblaje de los componentes del inflamasoma da lugar a la activación de caspasa-1, generando la liberación de citoquinas pro-inflamatorias IL-1β e IL-18. Objetivos: Evaluar si existe una activación basal del inflamasoma en pacientes con LES y determinar la asociación de las citoquinas IL-1β e IL-18 con la actividad de la enfermedad. Materiales y métodos: Se incluyeron 14 (n=14) pacientes consecutivos con LES y 13 (n=13) controles, pareados por edad, sexo y raza. Se recogieron datos clínicos, demográficos y de laboratorio. Los monocitos fueron aislados a partir de células mononucleares de sangre periférica obtenidas de pacientes y controles. Los monocitos purificados fueron estimulados con LPS, en presencia y ausencia de inhibidor de caspasa-1. La expresión de CD14 y caspasa-1 fueron determinados por citometría de flujo. Niveles de citoquinas fueron determinadas en plasma y en sobrenadantes de cultivos mediante técnica de ELISA. Test de Student y Mann-Whitney fueron usados para el análisis estadístico. Resultados: El porcentaje de CD14+/caspasa-1+ fue significativamente superior en monocitos de pacientes con LES vs. controles (p<0,01). En forma paralela, se encontraron niveles plasmáticos significativamente superiores de IL-1β (p<0,05) y de IL-18 (p<0,01) en pacientes con LES. Monocitos purificados de pacientes lúpicos presentaron una robusta respuesta inflamatoria luego de ser estimulados con LPS, donde caspasa-1, IL-1β e IL-18 fueron altamente expresados. Niveles plasmáticos de IL-18 fueron significativamente mayores en pacientes con LES y enfermedad activa (p<0,05). Por otro lado, la producción de IL-18 se redujo casi 3 veces cuando se agregó inhibidor de caspasa-1 en cultivos.(AU)

Role of Inflammasome Activation in Systemic Lupus Erythematosus: Are Innate Immune Cells Activated?

BACKGROUND: Systemic lupus erythematosus (SLE) is characterized by a wide spectrum of clinical and immunological abnormalities. New data have emerged about the role of inflammasomes in autoimmune diseases. We aimed to investigate whether basal inflammasome activation occurs in SLE patients, and whether a relationship between inflammasome-related-cytokines and disease activity exists. METHODS: Fourteen (14) consecutive SLE patients and 13 healthy individuals, matched by sex, age and ethnicity, were included. Demographics, laboratory and clinical data were recorded. Peripheral blood mononuclear cells (PBMCs) from patients and controls were obtained and monocytes were isolated by negative selection. Purified monocytes were stimulated with LPS in the presence or absence of Caspase-1 inhibitor. CD14 and Caspase-1 expression were analyzed by flow cytometry. Cytokine levels were determined in plasma and culture supernatants by ELISA. Student's t test and Mann-Whitney tests were used for statistical analysis. RESULTS: The percentage of CD14+/Caspase-1+ was significantly higher in monocytes from SLE patients compared to normal controls (p<0.01). These findings paralleled with higher plasma levels of IL-1ß (p<0.05) and IL-18 (p<0.01) in those patients. Purified monocytes from SLE patients displayed a robust inflammatory response after LPS stimulation where Caspase-1, IL-1ß and IL-18 were highly expressed. Plasma levels of IL-18 were also significantly higher in SLE patients with active disease (p<0.05). In addition, the production of IL-18 was reduced by 3 fold when Caspase-1 inhibitor was added to the cultures. CONCLUSIONS: Monocytes from SLE patients exhibited increased inflammasome activation, characterized by high expression of Caspase-1, IL-1ß and IL-18. Caspase-1 specific inhibitor decreased inflammasome activation (in vitro) by suppressing the production of IL-18.