Regulation of calcium signaling in dendritic cells by 1,25-dihydroxyvitamin D3

FASEB J. 2010 Jun;24(6):1989-96. doi: 10.1096/fj.09-142265. Epub 2010 Feb 2.

Abstract

Dendritic cells (DCs) are antigen-presenting cells that provide a link between innate and adaptive immunity. Ca(2+)-dependent signaling plays a central regulatory role in DC responses to diverse antigens. DCs are a primary target of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], a secosteroid hormone, that, in addition to its well-established action on Ca(2+) homeostasis, possesses immunomodulatory properties. Surprisingly, nothing is known about its effects on DC cytosolic Ca(2+) activity. The present study explored whether 1,25(OH)(2)D(3) modifies the intracellular Ca(2+) concentration ([Ca(2+)](i)) in DCs. Here we show that mouse DCs expressed K(+)-independent (NCX1-3) and K(+)-dependent (NCKX1, 3, 4, and 5) Na(+)/Ca(2+) exchangers. Acute application of LPS (100 ng/ml) to DCs increased [Ca(2+)](i), an effect significantly blunted by prior incubation with 1,25(OH)(2)D(3). 1,25(OH)(2)D(3) increased the membrane abundance of the NCKX1 protein, up-regulated the K(+)- and Na(+)-dependent Ca(2+) entry and enhanced the K(+)-dependent Na(+)/Ca(2+) exchanger currents. The NCKX blocker 3',4'-dichlorobenzamyl (DBZ) reversed the inhibitory effect of 1,25(OH)(2)D(3) on the LPS-induced increase of [Ca(2+)](i). Expression of the costimulatory molecule CD86 was down-regulated by 1,25(OH)(2)D(3), an effect reversed by DBZ. In summary, 1,25(OH)(2)D(3) blunts the LPS-induced increase in [Ca(2+)](i) by stimulation of Na(+)/Ca(2+) exchanger-dependent Ca(2+) extrusion, an effect that contributes to 1,25(OH)(2)D(3)-mediated immunosuppression. The results disclose completely novel mechanisms in the regulation of DC maturation and function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Signaling / drug effects*
  • Cells, Cultured
  • Dendritic Cells / drug effects*
  • Dendritic Cells / metabolism
  • Female
  • Flow Cytometry
  • Immunoblotting
  • Lipopolysaccharides / pharmacology
  • Mice
  • Patch-Clamp Techniques
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sodium-Calcium Exchanger / genetics
  • Sodium-Calcium Exchanger / metabolism
  • Vitamin D / analogs & derivatives*
  • Vitamin D / pharmacology

Substances

  • Lipopolysaccharides
  • NCX1 protein, mouse
  • RNA, Messenger
  • Slc24a3 protein, mouse
  • Slc8a2 protein, mouse
  • Slc8a3 protein, mouse
  • Sodium-Calcium Exchanger
  • Vitamin D
  • 1,25-dihydroxyvitamin D
  • Calcium