title: Suppression of LPS-induced Interferon-gamma and nitric oxide in splenic lymphocytes by select estrogen-regulated microRNAs: a novel mechanism of immune modulation.
abstract: MicroRNAs (miRNAs), recently identified noncoding small RNAs, are emerging as key regulators in homeostasis of the immune system. Therefore, aberrant expression of miRNAs may be linked to immune dysfunction, such as in chronic inflammation and autoimmunity. In this study, we investigated the potential role of miRNAs in estrogen-mediated regulation of innate immune responses, as indicated by up-regulation of lipopolysaccharide (LPS)-induced interferon-gamma (IFNgamma), inducible nitric oxide synthase (iNOS), and nitric oxide in splenic lymphocytes from estrogen-treated mice. We found that miR-146a, a negative regulator of Toll-like receptor (TLR) signaling, was decreased in freshly isolated splenic lymphocytes from estrogen-treated mice compared with placebo controls. Increasing the activity of miR-146a significantly inhibited LPS-induced IFNgamma and iNOS expression in mouse splenic lymphocytes. Further, miRNA microarray and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed that estrogen selectively up-regulates/down-regulates the expression of miRNAs in mouse splenic lymphocytes. miR-223, which is markedly enhanced by estrogen, regulates LPS-induced IFNgamma, but not iNOS or nitric oxide in splenic lymphocytes. Inhibition of miR-223 activity decreased LPS-induced IFNgamma in splenic lymphocytes from estrogen-treated mice. Our data are the first to demonstrate the selective regulation of miRNA expression in immune cells by estrogen and are indicative of an important role of miRNAs in estrogen-mediated immune regulation.
authors.affiliation: Department of Biomedical Sciences and Pathology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA24061-0342, USA.
authors.forename: Rujuan
authors.initials: R
authors.lastname: Dai
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Phillips
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Deena
authors.initials: D
authors.lastname: Khan
authors.forename: Oswald
authors.initials: O
authors.lastname: Crasta
authors.forename: S Ansar
authors.initials: SA
authors.lastname: Ahmed
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D004967:Estrogens / Q000494:pharmacology*; D020869:Gene Expression Profiling; D007111:Immunity, Cellular / Q000235:genetics*; D007371:Interferon-gamma / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics*; D009569:Nitric Oxide / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D014162:Transfection
chemical_list: D004967:Estrogens; D008070:Lipopolysaccharides; C542542:MIRN146 microRNA, human; D035683:MicroRNAs; C534190:Mirn146 microRNA, mouse; D009569:Nitric Oxide; D007371:Interferon-gamma
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