The P2 purinergic receptors of human dendritic cells: identification and coupling to cytokine release

Abstract

We investigated the expression of purinoceptors in human dendritic cells, providing functional, pharmacological, and biochemical evidence that immature and mature cells express P2Y and P2X subtypes, coupled to increase in the intracellular Ca(2+), membrane depolarization, and secretion of inflammatory cytokines. The ATP-activated Ca(2+) change was biphasic, with a fast release from intracellular stores and a delayed influx across the plasma membrane. A prolonged exposure to ATP was toxic to dendritic cells that swelled, lost typical dendrites, became phase lucent, detached from the substrate, and eventually died. These changes were highly suggestive of expression of the cytotoxic receptor P2X(7), as confirmed by ability of dendritic cells to become permeant to membrane impermeant dyes such as Lucifer yellow or ethidium bromide. The P2X(7) receptor ligand 2',3'-(4-benzoylbenzoyl)-ATP was a better agonist then ATP for Ca(2+) increase and plasma membrane depolarization. Oxidized ATP, a covalent blocker of P2X receptors, and the selective P2X(7) antagonist KN-62 inhibited both permeabilization and Ca(2+) changes induced by ATP. The following purinoceptors were expressed by immature and mature dendritic cells: P2Y(1), P2Y(2), P2Y(5), P2Y(11) and P2X(1), P2X(4), P2X(7). Finally, stimulation of LPS-matured cells with ATP triggered release of IL-1 beta and TNF-alpha. Purinoceptors may provide a new avenue to modulation of dendritic cells function.

Purinergic signaling in inflammatory cells: P2 receptor expression, functional effects, and modulation of inflammatory responses

“…Human dendritic cells were found to express mRNA for P2X1, P2X4, P2X5, and P2X7 as well as for P2Y 1 , P2Y 2 , P2Y 4 , P2Y 6 , P2Y 11 , and P2Y 14 receptors [123][124][125][126]. The expression of P2X7 on protein level in DCs during immune responses was suggested by Buell et al who observed immunopositive staining within human tonsils [127].…”

ATP-Induced Non-Neuronal Cell Permeabilization in the Rat Inner Retina

“…It is known that ATP activates P2X 7 receptors in microglial cells in which it mediates cytotoxic responses and cytokine release. This suggests that it may have an important role in immunomodulation Di Virgilio et al, 1998;Ferrari et al, 2000;Inoue, 2002). There is increasing evidence that microglial cells are related to a number of physio-pathological events in the retina when massive cell death occurs (Schnitzer and Scherer, 1990;Milligan et al, 1991;Thanos, 1991;Frade and Barde, 1998).…”

Augmentation of Cutaneous Immune Responses by ATPγS: Purinergic Agonists Define a Novel Class of Immunologic Adjuvants

“…There are several precedents for this possibility. Monocyte-derived dendritic cells have been shown to express a number of P2Rs of both the P2X and the P2Y series (11,12). Exposure of monocyte-derived dendritic cells to ATP results in up-regulation of CD54 and MHC class II molecules, induces secretion of IL-12, and augments stimulatory capacity for allogeneic T cells (11,13).…”

“…Exposure of monocyte-derived dendritic cells to ATP results in up-regulation of CD54 and MHC class II molecules, induces secretion of IL-12, and augments stimulatory capacity for allogeneic T cells (11,13). Exposure of LPS-matured dendritic cells to ATP induces the release of IL-1␤ and TNF-␣ (12). In combination with TNF-␣, ATP has been shown to increase the expression of CD80, CD83, and CD86 in monocyte-derived dendritic cells (11).…”