Induction of antiinflammatory purinergic signaling in activated human iNKT cells

Abstract

Invariant natural killer T (iNKT) cells are activated at sites of local tissue injury, or globally during vaso-occlusive episodes of sickle cell disease (SCD). Tissue damage stimulates production of CD1d-restricted lipid antigens that activate iNKT cells to produce Th1- and Th2-type cytokines. Here, we show that circulating iNKT cells in SCD patients express elevated levels of the ectonucleoside triphosphate diphosphosphohydrolase, CD39, as well the adenosine A2A receptor (A2AR). We also investigated the effects of stimulating cultured human iNKT cells on the expression of genes involved in the regulation of purinergic signaling. iNKT cell stimulation caused induction of ADORA2A, P2RX7, CD38, CD39, ENPP1, CD73, PANX1, and ENT1. Transcription of ADA, which degrades adenosine, was reduced. Induction of CD39 mRNA was associated with increased ecto-ATPase activity on iNKT cells that was blocked by POM1. Exposure of iNKT cells to A2AR agonists during stimulation reduced production of IFN-γ and enhanced production of IL-13 and CD39. Based on these findings, we define "purinergic Th2-type cytokine bias" as an antiinflammatory purinergic response to iNKT cell stimulation resulting from changes in the transcription of several genes involved in purine release, extracellular metabolism, and signaling.

Innate immune cells, major protagonists of sickle cell disease pathophysiology

“…72 Furthermore, iNKT cells from SCD patients showed concomitant high expression of A 2A R and CD39, the ecto-ATPase that converts ATP and ADP to AMP, thereby resulting in increased adenosine production, which limits iNKT-cell activation. 73 In a phase I trial of the A 2A R agonist regadenoson in 27 adult SCD patients, iNKT-cell activation, measured by phospho-NF-κB, IFN-g and A 2A R expression, was increased in patients as compared with controls and during VOC as compared with steady-state. 74 A 24-hour infusion of regadenoson during VOC decreased the activation of iNKT cells by 50%, to levels similar to those in steadystate patients and in controls, without any reported toxicity.…”

Adenosine A2A receptor agonist (regadenoson) in human lung transplantation

“…In a separate study, the effects of regadenoson on skeletal muscle microvascular flow produced a 9% improvement in blood flow during regadenoson infusion, which was encouraging, but not statistically significant (p = 0.13). 32 Because activated iNKT cells are known to synthesize and release proinflammatory cytokines such as interferon gamma and tumor necrosis factor-a (TNF-a) within 2 hours of their activation, 33 we suspect that the efficacy of regadenoson to reduce iNKT cell−mediated inflammation will be reduced as the time between the initiation of acute inflammatory insult and the infusion of regadenoson is increased. In the case of lung transplantation, regadenoson infusion is initiated before transplantation, so the drug is on board at the time that the recipient iNKT cells are activated, presumably resulting in a greater efficacy.…”

Inhibition of the Adenosinergic Pathway in Cancer Rejuvenates Innate and Adaptive Immunity

“…A 1 R and A 2 R have the potential to regulate NK cell activity [116]. Human naive NK cells do not express significant levels of CD73 [117], but stimulated NK cells increased the expressions of A 2A R, P2 X7 R, CD38, CD39, ENPP1, CD73, PANX1, and ENT1, and decreased ADA expression, suggesting that ADO is generated by canonical and non-canonical pathways after cellular activation [118]. The ADO effects on NK are presented in Figure 4.…”