The bile acid sensor FXR is required for immune-regulatory activities of TLR-9 in intestinal inflammation.

<h4>Background</h4>Toll like receptors (TLRs) sense the intestinal microbiota and regulate the innate immune response. A dysregulation of TLRs function participates into intestinal inflammation. Farnesoid X Receptor (FXR) is a nuclear receptor and bile acid sensor highly expressed in ent...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Barbara Renga, Andrea Mencarelli, Sabrina Cipriani, Claudio D'Amore, Adriana Carino, Angela Bruno, Daniela Francisci, Angela Zampella, Eleonora Distrutti, Stefano Fiorucci
Formato: article
Lenguaje:EN
Publicado: Public Library of Science (PLoS) 2013
Materias:
R
Q
Acceso en línea:https://doaj.org/article/95ac7d0acba945eca1cf9d528946926d
Etiquetas: Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
Descripción
Sumario:<h4>Background</h4>Toll like receptors (TLRs) sense the intestinal microbiota and regulate the innate immune response. A dysregulation of TLRs function participates into intestinal inflammation. Farnesoid X Receptor (FXR) is a nuclear receptor and bile acid sensor highly expressed in entero-hepatic tissues. FXR regulates lipid metabolism and innate immunity.<h4>Methodology/principal findings</h4>In this study we have investigated whether FXR gene expression/function in the intestine is modulated by TLRs. We found that in human monocytes activation of membrane TLRs (i.e. TLR2, 4, 5 and 6) downregulates, while activation of intracellular TLRs (i.e. TLR3, 7, 8 and 9) upregulates the expression of FXR and its target gene SHP, small heterodimer partner. This effect was TLR9-dependent and TNFα independent. Intestinal inflammation induced in mice by TNBS downregulates the intestinal expression of FXR in a TLR9-dependent manner. Protection against TNBS colitis by CpG, a TLR-9 ligand, was lost in FXR(-/-) mice. In contrast, activation of FXR rescued TLR9(-/-) and MyD88(-/-) mice from colitis. A putative IRF7 response element was detected in the FXR promoter and its functional characterization revealed that IRF7 is recruited on the FXR promoter under TLR9 stimulation.<h4>Conclusions/significance</h4>Intestinal expression of FXR is selectively modulated by TLR9. In addition to its role in regulating type-I interferons and innate antiviral immunity, IRF-7 a TLR9-dependent factor, regulates the expression of FXR, linking microbiota-sensing receptors to host's immune and metabolic signaling.