title: 17Beta-estradiol promotes TLR4-triggered proinflammatory mediator production through direct estrogen receptor alpha signaling in macrophages in vivo.
abstract: 17Beta-estradiol (E2) has been shown to promote the expression of inflammatory mediators by LPS-activated tissue resident macrophages through estrogen receptor alpha (ERalpha) signaling. However, it remained to be determined whether E2 similarly influences macrophages effector functions under inflammatory conditions in vivo, and whether this action of E2 resulted from a direct effect on macrophages. We show in this study that chronic E2 administration to ovariectomized mice significantly increased both cytokine (IL-1beta, IL-6, and TNF-alpha) and inducible NO synthase mRNA abundance in thioglycolate (TGC)-elicited macrophages. The proinflammatory action of E2 was also evidenced at the level of released IL-1beta and IL-6 by ex vivo LPS-activated macrophages. E2 concomitantly inhibited PI3K activity as well as Akt phosphorylation in TGC-elicited macrophages, suggesting that E2 promoted TLR-dependent macrophage activation by alleviating this suppressive signaling pathway. Indeed, this effect was abolished in the presence of the inhibitor wortmannin, demonstrating a key functional link between inhibition of PI3K activity and the E2 action on macrophage functions. Endogenous estrogens levels circulating in ovary-intact mice were sufficient to promote the above described actions. Finally, thanks to a CreLox strategy, targeted disruption of ERalpha gene in macrophages totally abolished the effect of E2 on the expression of inflammatory mediators by both resident and TGC-elicited peritoneal macrophages. In conclusion, we demonstrate that estrogens, through the activation of ERalpha in macrophages in vivo, enhance their ability to produce inflammatory mediators and cytokines upon subsequent TLR activation.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale Unité 858, Institut de Médecine Moléculaire de Rangueil, Université de Toulouse, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Calippe
authors.forename: Victorine
authors.initials: V
authors.lastname: Douin-Echinard
authors.forename: Laurent
authors.initials: L
authors.lastname: Delpy
authors.forename: Muriel
authors.initials: M
authors.lastname: Laffargue
authors.forename: Karine
authors.initials: K
authors.lastname: Lélu
authors.forename: Andrée
authors.initials: A
authors.lastname: Krust
authors.forename: Bernard
authors.initials: B
authors.lastname: Pipy
authors.forename: Francis
authors.initials: F
authors.lastname: Bayard
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Arnal
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Guéry
authors.forename: Pierre
authors.initials: P
authors.lastname: Gourdy
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D018836:Inflammation Mediators / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013864:Thioglycolates / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
chemical_list: D016207:Cytokines; D047628:Estrogen Receptor alpha; D018836:Inflammation Mediators; D013864:Thioglycolates; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D004958:Estradiol; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt