Metalloproteinase-dependent TLR2 ectodomain shedding is involved in soluble toll-like receptor 2 (sTLR2) production

Toll-like receptor (TLR) 2, a type I membrane receptor that plays a key role in innate immunity, recognizes conserved molecules in pathogens, and triggering an inflammatory response. It has been associated with inflammatory and autoimmune diseases. Soluble TLR2 (sTLR2) variants have been identified in human body fluids, and the TLR2 ectodomain can negatively regulate TLR2 activation by behaving as a decoy receptor. sTLR2 generation does not involve alternative splicing mechanisms, indicating that this process might involve a post-translational modification of the full-length receptor; however, the specific mechanism has not been studied. Using CD14+ peripheral human monocytes and the THP-1 monocytic leukemia-derived cell line, we confirm that sTLR2 generation increases upon treatment with pro-inflammatory agents and requires a post-translational mechanism. We also find that the constitutive and ligand-induced release of sTLR2 is sensitive to pharmacological metalloproteinase activator and inhibitors leading us to conclude that metalloproteinase TLR2 shedding contributes to soluble receptor production. By expressing human TLR2 in ADAM10- or ADAM17-deficient MEF cells, we find both enzymes to be implicated in TLR2 ectodomain shedding. Moreover, using a deletion mutant of the TLR2 juxtamembrane region, we demonstrate that this domain is required for sTLR2 generation. Functional analysis suggests that sTLR2 generated by metalloproteinase activation inhibitsTLR2-induced cytokine production by this monocytic leukemia-derived cell line. The identification of the mechanisms involved in regulating the availability of soluble TLR2 ectodomain and cell surface receptors may contribute further research on TLR2-mediated processes in innate immunity and inflammatory disorders

Landscapes and bacterial signatures of mucosa-associated intestinal microbiota in Chilean and Spanish patients with inflammatory bowel disease

Inflammatory bowel diseases (IBDs), which include ulcerative colitis (UC) and Crohn’s disease (CD), cause chronic inflammation of the gut, affecting millions of people worldwide. IBDs have been frequently associated with an alteration of the gut microbiota, termed dysbiosis, which is generally characterized by an increase in abundance of Proteobacteria such as Escherichia coli, and a decrease in abundance of Firmicutes such as Faecalibacterium prausnitzii (an indicator of a healthy colonic microbiota). The mechanisms behind the development of IBDs and dysbiosis are incompletely understood. Using samples from colonic biopsies, we studied the mucosa-associated intestinal microbiota in Chilean and Spanish patients with IBD. In agreement with previous studies, microbiome comparison between IBD patients and non-IBD controls indicated that dysbiosis in these patients is characterized by an increase of pro-inflammatory bacteria (mostly Proteobacteria) and a decrease of commensal beneficial bacteria (mostly Firmicutes). Notably, bacteria typically residing on the mucosa of healthy individuals were mostly obligate anaerobes, whereas in the inflamed mucosa an increase of facultative anaerobe and aerobic bacteria was observed. We also identify potential co-occurring and mutually exclusive interactions between bacteria associated with the healthy and inflamed mucosa, which appear to be determined by the oxygen availability and the type of respiration. Finally, we identified a panel of bacterial biomarkers that allow the discrimination between eubiosis from dysbiosis with a high diagnostic performance (96% accurately), which could be used for the development of non-invasive diagnostic methods. Thus, this study is a step forward towards understanding the landscapes and alterations of mucosa-associated intestinal microbiota in patients with IBDs.This study was supported by Fondo Nacional De Desarrollo Científico y Tecnológico FONDECYT grant 1161161 to R. Vidal, CONICYT-PCHA/2014-21140975 fellowship to N. Chamorro, FONDECYT 1120577 and 1170648 to Hermoso MA and the Spanish Ministry of Economy projects CLG2015 66686-C3-1-P to Rosselló-Mora R., as well as funds from the European Regional Development Fund (FEDER) and NSF Dimensions in Biodiversity grant OCE-1342694. Support was also provided by a Millennium Science Initiative grant from the Ministry of Economy, Development and Tourism to Paredes-Sabja D

Regulation of the Intestinal Extra-Adrenal Steroidogenic Pathway Component LRH-1 by Glucocorticoids in Ulcerative Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) and can be treated with glucocorticoids (GC), although some patients are unresponsive to this therapy. The transcription factor LRH-1/NR5A2 is critical to intestinal cortisol production (intestinal steroidogenesis), being reduced in UC patients. However, the relationship between LRH-1 expression and distribution with altered corticosteroid responses is unknown. To address this, we categorized UC patients by their steroid response. Here, we found that steroid-dependent and refractory patients presented reduced glucocorticoid receptor (GR)-mediated intestinal steroidogenesis compared to healthy individuals and responder patients, possibly related to increased colonic mucosa GR isoform beta (GR beta) content and cytoplasmic LRH-1 levels in epithelial and lamina propria cells. Interestingly, an intestinal epithelium-specific GR-induced knockout (GR(iKO)) dextran sodium sulfate (DSS)-colitis mice model presented decreased epithelial LRH-1 expression, whilst it increased in the lamina propria compared to DSS-treated control mice. Mechanistically, GR directly induced NR5A2 gene expression in CCD841CoN cells and human colonic organoids. Furthermore, GR bound to two glucocorticoid-response elements within the NR5A2 promoter in dexamethasone-stimulated CCD841CoN cells. We conclude that GR contributes to intestinal steroidogenesis by inducing LRH-1 in epithelial cells, suggesting LRH-1 as a potential marker for glucocorticoid-impaired response in UC. However, further studies with a larger patient cohort will be necessary to confirm role of LRH-1 as a therapeutic biomarker

Update on celiac disease Enfermedad celíaca. revisión

© 2016, Sociedad Medica de Santiago. All rights reserved.The prevalence of Celiac disease in the general population is approximately 1% and remains undiagnosed in a significant proportion of individuals. Its clinical presentation includes the classical malabsorption syndrome, unspecific and extra-intestinal manifestations, and silent celiac disease. The serologic diagnosis has an elevated sensitivity and specificity and, at least in adult population, it must be confirmed by biopsy in every case. Diagnosis in subjects already on gluten free diet includes HLA typing and gluten challenge with posterior serologic and histologic evaluation. The core of the treatment is the gluten free diet, which must be supervised by an expert nutritionist. Monitoring must be performed with serology beginning at 3-6 months, and with histology two years after the diagnosis, unless the clinical response is poor. Poor disease control is associated with complications such as lymphoma and small bowel adenocarc

Síndrome hepatorenal: patogénesis y tratamiento

El Síndrome Hepatorenal (SHR) es una insuficiencia renal aguda funcional y reversible, que se desarrolla en pacientes con cirrosis hepática descompensada o en insuficiencia hepática aguda severa. La característica principal del SHR es la intensa vasoconstricción renal causada por la interacción entre alteraciones hemodinámicas a nivel sistémico y portal. El aumento del volumen intravascular y un prolongado tratamiento con fármacos vasoconstrictores pueden revertir la falla renal en un porcentaje significativo de pacientes. El SHR Tipo 2, el más frecuente, generalmente presenta una evolución lenta y un mejor pronóstico que el SHR Tipo 1. La terapia vasoconstrictora con terlipresina asociado a albúmina es el tratamiento de elección en pacientes con SHR. A pesar del avance en las diferentes estrategias terapéuticas, el pronóstico a largo plazo es aún pobre y depende generalmente del grado de reversibilidad de la enfermedad hepática asociada o del acceso al trasplante hepático. En la presente revisión se discutirán los avances más recientes en el diagnóstico, patogénesis y tratamiento del SHR

Proctitis: ¿En qué etiologías debemos pensar? y ¿qué estrategia terapéutica debemos considerar?

La proctitis se refiere a la inflamación recurrente o persistente de la mucosa rectal (últimos 15 cm), la cual resulta de un amplio rango de etiologías con diferentes mecanismos patogénicos. Aunque la proctitis ulcerosa es la causa más frecuente de proctitis infecciosa, causas infecciosas y no- infecciosas (tales como radiación, isquemia, derivación y traumatismos) deben ser también consideradas. Ya que los síntomas, signos y los hallazgos endoscópicos e histológicos son frecuentemente independientes de la etiología, el diagnóstico definitivo puede ser complicado en algunas ocasiones. Esta revisión ilustra y analiza las presentaciones clínicas, las claves en el diagnóstico y los tratamientos para las diferentes causas de proctitis