Publications by authors named "Isabelle Christen"

In a group of pedigree cats (n = 17) in poor health condition housed in an animal shelter in Vienna, Austria, with a history of persistent diarrhea, Tritrichomonas foetus infection was detected by PCR. Despite pre-existing clinical conditions all cats were treated with ronidazole (30 mg/kg PO q24h for 14 days) under close observation. After treatment, 11 of 14 initially positive animals remained negative for T.

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The behaviors of lymphocytes, including CD4 T helper cells, are controlled on many levels by internal metabolic properties. Lipid metabolites have recently been ascribed a novel function as immune response modulators and perturbation of steroids pathways modulates inflammation and potentially promotes a variety of diseases. However, the impact of lipid metabolism on autoimmune disease development and lymphocyte biology is still largely unraveled.

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Arrival of encephalitogenic T cells at inflammatory foci represents a critical step in development of experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. EBI2 and its ligand, 7α,25-OHC, direct immune cell localization in secondary lymphoid organs. CH25H and CYP7B1 hydroxylate cholesterol to 7α,25-OHC.

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EBI2 is a G protein-coupled receptor activated by oxysterol 7α, 25-dihydroxycholesterol (7α25HC) and regulates T cell-dependant antibody response and B cell migration. We recently found EBI2 is expressed in human astrocytes, regulates intracellular signalling and modulates astrocyte migration. Here, we report that LPS treatment of mouse astrocytes alters mRNA levels of EBI2 and oxysterols suggesting that the EBI2 signalling pathway is sensitive to LPS-mediated immune challenge.

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We report a straightforward sample preparation procedure and a direct liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method for the analysis of 7alpha,25-dihydroxycholesterol (7α25-OHC) and 7alpha,27-dihydroxycholesterol (7α27-OHC). By applying a slow protein precipitation approach using cold ethanol, we were able to detect and quantify 7α25-OHC and 7α27-OHC in a fast and reliable manner. The average concentrations from 20 healthy individuals were determined to be 0.

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Epstein-Barr virus-induced gene 2 (EBI2, also known as GPR183) is a G-protein-coupled receptor that is required for humoral immune responses; polymorphisms in the receptor have been associated with inflammatory autoimmune diseases. The natural ligand for EBI2 has been unknown. Here we describe the identification of 7α,25-dihydroxycholesterol (also called 7α,25-OHC or 5-cholesten-3β,7α,25-triol) as a potent and selective agonist of EBI2.

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