title: Effect of dexamethasone on Na+/Ca2+ exchanger in dendritic cells.
abstract: Ca(+)-dependent signaling regulates the function of dendritic cells (DCs), antigen-presenting cells linking innate and adaptive immunity. The activity of DCs is suppressed by glucocorticoids, potent immunosuppressive hormones. The present study explored whether the glucocorticoid dexamethasone influences the cytosolic Ca(2+) concentration ([Ca(2+)](i)) in DCs. To this end, DCs were isolated from mouse bone marrow. According to fura-2 fluorescence, exposure of DCs to lipopolysaccharide (LPS, 100 ng/ml) increased [Ca(2+)](i), an effect significantly blunted by overnight incubation with 10 nM dexamethasone before LPS treatment. Dexamethasone did not affect the Ca(2+) content of intracellular stores, sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA)2 and SERCA3 expression, ryanodine receptor (RyR)1 expression, or Ca(2+) entry through store-operated Ca(2+) channels. In contrast, dexamethasone increased the transcript level and the membrane protein abundance of the Na(+)/Ca(2+) exchanger NCX3. The activity of Na(+)/Ca(2+) exchangers was assessed by removal of extracellular Na(+) in the presence of external Ca(2+), a maneuver triggering the Ca(2+) influx mode. Indeed, Na(+) removal resulted in a rapid transient increase of [Ca(2+)](i) and induced an outwardly directed current as measured in whole cell patch-clamp experiments. Dexamethasone significantly augmented the increase of [Ca(2+)](i) and the outward current following removal of extracellular Na(+). The NCX blocker KB-R7943 reversed the inhibitory effect of dexamethasone on LPS-induced increase in [Ca(2+)](i). Dexamethasone blunted LPS-induced stimulation of CD86 expression and TNF-α production, an effect significantly less pronounced in the presence of NCX blocker KB-R7943. In conclusion, our results show that glucocorticoid treatment blunts LPS-induced increase in [Ca(2+)](i) in DCs by increasing expression and activity of Na(+)/Ca(2+) exchanger NCX3. The effect contributes to the inhibitory effect of the glucocorticoid on DC maturation.
authors.affiliation: Dept. of Physiology, University of Tübingen, Gmelinstrasse 5, Tübingen, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Heise
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.forename: Meerim K
authors.initials: MK
authors.lastname: Nurbaeva
authors.forename: Evi
authors.initials: E
authors.lastname: Schmid
authors.forename: Kalina
authors.initials: K
authors.lastname: Szteyn
authors.forename: Wenting
authors.initials: W
authors.lastname: Yang
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Xuan
authors.forename: Kan
authors.initials: K
authors.lastname: Wang
authors.forename: Irina M
authors.initials: IM
authors.lastname: Zemtsova
authors.forename: Michael
authors.initials: M
authors.lastname: Duszenko
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D051940:B7-2 Antigen / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D018408:Patch-Clamp Techniques; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013890:Thiourea / Q000031:analogs & derivatives / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; D051940:B7-2 Antigen; D005938:Glucocorticoids; D008070:Lipopolysaccharides; C491101:Slc8a3 protein, mouse; D019831:Sodium-Calcium Exchanger; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D013890:Thiourea; D002118:Calcium