Dexamethasone Enhances ATP-Induced Inflammatory Responses in Endothelial Cells

Abstract

The purinergic nucleotide ATP is released from stressed cells and is implicated in vascular inflammation. Glucocorticoids are essential to stress responses and are used therapeutically, yet little information is available that describes the effects of glucocorticoids on ATP-induced inflammation. In a human microvascular endothelial cell line, extracellular ATP-induced interleukin (IL)-6 secretion in a dose-and time-dependent manner. When cells were pretreated with dexamethasone, a prototypic glucocorticoid, ATP-induced IL-6 production was enhanced in a time-and dose-dependent manner. Mifepristone, a glucocorticoid receptor antagonist, blocked these effects. ATP-induced IL-6 release was significantly inhibited by a phospholipase C inhibitor (88 Ϯ 1%, p Ͻ 0.001). Cells treated with dexamethasone induced mRNA expression of the purinergic P2Y 2 receptor (P2Y 2 R) 1.8-Ϯ 0.1-fold and, when stimulated with ATP, enhanced Ca 2ϩ release and augmented IL-6 mRNA expression. Silencing of the P2Y 2 R by its small interfering RNA decreased ATP-induced IL-6 production by 81 Ϯ 1% (p Ͻ 0.001). Dexamethasone enhanced the transcription rate of P2Y 2 R mRNA and induced a dose-related increase in the activity of the P2Y 2 R promoter. Furthermore, dexamethasoneenhanced ATP induction of adhesion molecule transcription and augmented the release of IL-8. Dexamethasone leads to an unanticipated enhancement of endothelial inflammatory mediator production by extracellular ATP via a P2Y 2 R-dependent mechanism. These data define a novel positive feedback loop of glucocorticoids and ATP-induced endothelial inflammation.

Glucocorticoid-Potentiated Spinal Microglia Activation Contributes to Preoperative Anxiety-Induced Postoperative Hyperalgesia

“…Upon stimulation, the TLR2 signaling leads to the activation of proinflammatory transcription factors and results in the expression of inflammatory cytokines [65,66]. Second, GCs can upregulate the expression of pyrin domain-containing 3 [62,67] and purinergic 2Y2 nucleotide receptor [68], which can sensitize innate immune cells to extracellular adenosine triphosphate and ultimately induce the synthesis of proinflammatory cytokines [65,66]. Third, NMDA signaling may participate in the process of GC-priming microglia [69].…”

Glucocorticoids Sensitize the Innate Immune System through Regulation of the NLRP3 Inflammasome

“…4C) has considerable implications for processes that result in micromolar levels of extracellular ATP in vivo, such as inflammation (53), damaged and dying tissue (54), or chemotherapy (55). In addition to changes in NLRP3, induction of P2Y 2 by glucocorticoids could be contributing to this sensitization and providing another pathway for ATP and GR to crosstalk (47).…”

“…Acute stress has been shown to prime the immune system and enhance the release of TNF-␣, IL-1␤, and IL-6 (45,46). Additionally, it recently has been shown that glucocorticoids enhance the release of IL-6 from endothelial cells in response to ATP (47). Therefore, supernatants from LPS-primed THP-1 and THP-M⌽ were assayed for the secreted forms of the following pro-and anti-inflammatory cytokines by flow cytometry: IL-8, IL-1␤, IL-6, IL-10, TNF-␣, and IL-12 p70.…”

Interaction of purinergic receptors with GPCRs, ion channels, tyrosine kinase and steroid hormone receptors orchestrates cell function

“…In a human microvascular endothelial cell line, dexamethasone enhanced ATP-induced interleukin 6 (IL-6) secretion through PLC and p38 MAPK. In addition, dexamethasone induced P2Y 2 receptor mRNA expression, and when the P2Y 2 receptor was silenced by its small interfering RNA, ATPinduced IL-6 production decreased [126]. Dexamethasone also enhanced the ATP-induced [Ca 2+ ]i increase and nitric oxide (NO) production in type I spiral ganglion neurons of the guinea pig cochlea.…”