Thrombospondin-1 and indoleamine 2,3-dioxygenase are major targets of extracellular ATP in human dendritic cells

Abstract

Extracellular adenosine triphosphate affects the maturation of human monocytederived dendritic cells (DCs), mainly by inhibiting T-helper 1 (Th1) cytokines, promoting Th2 cytokines, and modulating the expression of costimulatory molecules. In this study, we report that adenosine triphosphate (ATP) can induce immunosuppression through its action on DCs, defining a new role for extracellular nucleotides. Microarray analysis of ATPstimulated human DCs revealed inter alia a drastic up-regulation of 2 genes encoding mediators involved in immunosuppression: thrombospondin-1 (TSP-1) and indoleamine 2,3-dioxygenase (IDO). The release of TSP-1 by DCs in response to ATP was confirmed at the protein level by enzyme-linked immunosorbent assay (ELISA), immunodetection, and mass spectrometry analysis, and has an antiproliferative effect on T CD4 ؉ lymphocytes through TSP-1/CD47 interaction. Our pharmacologic data support the involvement of purinergic receptor P2Y 11 in this ATP-mediated TSP-1 secretion. We demonstrate also that ATP significantly potentiates the up-regulation of IDO-a negative regulator of T lymphocyte proliferation-and kynurenine production initiated by interferon-␥ (IFN-␥) in human DCs.Thus, extracellular ATP released from damaged cells and previously considered as a danger signal is also a potent regulator of mediators playing key roles in immune tolerance. Consequently, nucleotides' derivatives may be considered as useful tools for DC-based immunotherapies. ( IntroductionDendritic cells (DCs) are antigen-presenting cells (APCs) playing a crucial role in the induction and regulation of immune responses. In response to danger signals like proinflammatory cytokines such as tumor necrosis factor-␣ (TNF-␣) and interleukin-1␤ (IL-1␤); pathogen-related molecules (lipopolysaccharide [LPS], doublestranded RNA, bacterial DNA); and T cell-derived signals such as CD40 ligand, immature dendritic cells undergo maturation. Maturation of DCs induces the loss of endocytosis, the surface expression of stable major histocompatibility complex (MHC)-peptide complexes and costimulatory molecules (CD80, CD86) and the production of cytokines such as IL-12. 1 Maturation is also accompanied by a shift in the expression of chemokines and their receptors, allowing DC migration to lymphoid organs. High secretion of IL-12 by mature DCs induces differentiation of CD4 ϩ T cells into T-helper 1 (Th1) cells secreting interferon-␥ (IFN-␥), whereas low IL-12 release combined with IL-10 production induces a Th2 response or a T regulatory response associated with induced tolerance. 1,2 In the past several years, our concepts about the role of DCs as the most potent initiators of the immune response against foreign antigens have evolved and the existence of an intermediate state between immaturity and maturation, called semimaturation, has been proposed. 3 An increasing number of reports provide strong evidence that APCs, and particularly DCs, are also involved in central and peripheral tolerance. 4,5 This tolerogenicity seems to be mediated b...

Modulation of murine dendritic cell function by adenine nucleotides and adenosine: Involvement of the A2B receptor

“…The molecular mechanisms involved in the generation of tolerogenic DC remain largely unknown. A microarray analysis of ATPcS-stimulated human monocytederived DC has revealed inter alia the striking up-regulation of two genes that could play a role in tolerance: TSP-1 and IDO [11]. TSP-1 can inhibit CD4 + Tcell proliferation, inhibit IL-12 production by DC [40] and activate TGF-b [41].…”

“…The incubation time (6 h) was chosen in view of previous experiments on human monocyte-derived DC [11]. In LPS-treated BMDC, 382 genes were up-or downregulated at least two times in response to NECA (data not shown).…”

“…Indeed, ATP up-regulates CD83 (a maturation maker) and co-stimulatory molecules such as CD80 and CD86 [7][8][9]. It also reduces the LPS-induced production of IL-12p70 [7,10] and favours the expression of IL-10, thrombospondin-1 (TSP-1) and indoleamine 2,3-dioxygenase (IDO) [11]. In addition, adenine nucleotides affect the production of chemokines (CCL22, CCL5), chemokine receptors (CCR7, CCR5) and the migration of DC [12,13].…”

“…Nucleotides and nucleosides released in the extracellular space by necrotic cells or activated immune cells at the site of inflammation are thought to control the immune response [4,5]. Adenosine exerts its actions by activating P1 (A 1 , A 2A , A 2B and A 3 ) receptors while nucleotides bind to P2Y (P2Y 1 , P2Y 2 , P2Y 4 , P2Y 6 , P2Y [11][12][13][14] or P2X (P2X 1-7 ) receptors (for review see [6]). We and others have shown that adenosine triphosphate (ATP) promotes a semi-maturation state of human monocyte-derived DC that could take part in tolerance.…”

The role of purinergic signaling in the liver and in transplantation: effects of extracellular nucleotides on hepatic graft vascular injury, rejection and metabolism

“…There are two main families of nucleotide receptors: P2X are "rapid" ligand-gated ion channels permeable for Na + , K + and also Ca 2+ (subtypes P2X1-7) (28) and P2Y are the "slow" metabotropic receptors (P2Y1, 2,4,6,[11][12][13][14]. P2Y receptors are 7-transmembrane G q -or G i -protein linked and initiate signal transduction coupled to activation of phospholipase C, or to inhibition of adenylate cyclase, respectively (29).…”