Transcriptional regulation and functional characterization of the oxysterol/EBI2 system in primary human macrophages.
Oxysterols such as 7 alpha, 25-dihydroxycholesterol (7α,25-OHC) are natural ligands for the Epstein-Barr virus (EBV)-induced gene 2 (EBI2, aka GPR183), a G protein-coupled receptor (GPCR) highly expressed in immune cells and required for adaptive immune responses. Activation of EBI2 by specific oxysterols leads to chemotaxis of B cells in lymphoid tissues. While the ligand gradient necessary for this critical process of the adaptive immune response is established by a stromal cells subset here we investigate the involvement of the oxysterol/EBI2 system in the innate immune response. First, we show that primary human macrophages express EBI2 and the enzymes needed for ligand production such as cholesterol 25-hydroxylase (CH25H), sterol 27-hydroxylase (CYP27A1), and oxysterol 7α-hydroxylase (CYP7B1). Furthermore, challenge of monocyte-derived macrophages with lipopolysaccharides (LPS) triggers a strong up-regulation of CH25H and CYP7B1 in comparison to a transient increase in EBI2 expression. Stimulation of EBI2 expressed on macrophages leads to calcium mobilization and to directed cell migration. Supernatants of LPS-stimulated macrophages are able to stimulate EBI2 signaling indicating that an induction of CH25H, CYP27A1, and CYP7B1 results in an enhanced production and release of oxysterols into the cellular environment. This is a study characterizing the oxysterol/EBI2 pathway in primary monocyte-derived macrophages. Given the crucial functional role of macrophages in the innate immune response these results encourage further exploration of a possible link to systemic autoimmunity.
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Inga
I
Preuss
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Marie-Gabrielle
MG
Ludwig
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Birgit
B
Baumgarten
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Frederic
F
Bassilana
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Francois
F
Gessier
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Klaus
K
Seuwen
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland. Electronic address: andreas.sailer@novartis.com.
Andreas W
AW
Sailer
D002118:Calcium / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D053493:Cholestanetriol 26-Monooxygenase / Q000235:genetics / Q000378:metabolism; D000072474:Cytochrome P450 Family 7; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006888:Hydroxycholesterols / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism
C080105:GPR183 protein, human; D006888:Hydroxycholesterols; D008070:Lipopolysaccharides; D043562:Receptors, G-Protein-Coupled; D013250:Steroid Hydroxylases; D000072474:Cytochrome P450 Family 7; C499571:CYP7B1 protein, human; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; C507384:cholesterol 25-hydroxylase; D002118:Calcium
CH25H; EBI2; GPCR; GPR183; Macrophages; Oxysterols