title: 25-Hydroxycholesterol secreted by macrophages in response to Toll-like receptor activation suppresses immunoglobulin A production.
abstract: 25-Hydroxycholesterol is produced in mammalian tissues. The function of this oxysterol is unknown. Here we describe a central role for 25-hydroxycholesterol in regulating the immune system. In initial experiments, we found that stimulation of macrophage Toll-like receptors (TLR) induced expression of cholesterol 25-hydroxylase and the synthesis of 25-hydroxycholesterol. Treatment of naïve B cells with nanomolar concentrations of 25-hydroxycholesterol suppressed IL-2-mediated stimulation of B cell proliferation, repressed activation-induced cytidine deaminase (AID) expression, and blocked class switch recombination, leading to markedly decreased IgA production. Consistent with these findings, deletion of the mouse cholesterol 25-hydroxylase gene caused an increase in serum IgA. Conversely, inactivation of the CYP7B1 oxysterol 7alpha-hydroxylase, which degrades 25-hydroxycholesterol, decreased serum IgA. The suppression of IgA class switching in B cells by a macrophage-derived sterol in response to TLR activation provides a mechanism for local and systemic negative regulation of the adaptive immune response by the innate immune system.
authors.affiliation: Department of Molecular Genetics and The Cancer Immunobiology Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Bauman
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bitmansour
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: McDonald
authors.forename: Bonne M
authors.initials: BM
authors.lastname: Thompson
authors.forename: Guosheng
authors.initials: G
authors.lastname: Liang
authors.forename: David W
authors.initials: DW
authors.lastname: Russell
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D006888:Hydroxycholesterols / Q000378:metabolism*; D007070:Immunoglobulin A / Q000096:biosynthesis*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*
chemical_list: D016207:Cytokines; D006888:Hydroxycholesterols; D007070:Immunoglobulin A; D051193:Toll-Like Receptors; C007997:25-hydroxycholesterol; D013250:Steroid Hydroxylases; C507384:cholesterol 25-hydroxylase