Figure 7
From: The NLRP3 inflammasome is activated by nanoparticles through ATP, ADP and adenosine
Adenosine induces IL-1β secretion and ATP release in THP1 human macrophages. PMA-primed THP1 cells were stimulated during 6 h with 250 μg/ml nano-SiO2, 500 μg/ml nano-TiO2 and/or high concentrations of adenosine (Ado), and eATP and IL-1β releases were measured. Adenosine potentiated eATP release and IL-1β secretion upon nanoparticle stimulation without inducing change in cell viability (a). High doses of adenosine alone induced IL-1β secretion by PMA-primed THP1 in a dose-dependent manner (b). The caspase-1-specific inhibitor Z-YVAD-fmk (5 μM) remarkably reduced adenosine- and/or nanoparticle-induced IL-1β secretion; Z-YVAD-fmk alone had no effect (c). Adenosine-dependent induction of IL-1β secretion was reduced in THP1 sh NLRP3 or THP1 sh ASC but not in unmodified THP1 or THP1 sh CTL (d). PMA-primed THP1 cells were stimulated with increasing doses of adenosine, the non-metabolisable analogue of adenosine NECA or inosine (Ino), the product of adenosine hydrolysis by ADA, and cell supernatants were analyzed to measure eATP, IL-1β and cell death (e). PMA-primed THP1 cells were stimulated with mM doses of adenosine in the presence of 5-iodotubercidin (5-Iodo), an inhibitor of both adenosine kinase and ENTs, or in the presence of NBMPR, an inhibitor of ENT1 at nM doses and ENT2 at μM concentrations, and eATP and IL-1β releases were measured at 6 h (f,g). Quantitative PCR analysis of ENT1, ENT2 and NLRP3 expression in PMA-primed THP1 stimulated for 6 h with increasing concentrations of Ado was performed (h,i). Intracellular ATP contents were measured 6 h after stimulation with high concentrations of adenosine (j). Data are representative of 2–3 independent experiments (*P≤0.05, **P≤0.01, ***P≤0.001, ns: not statistically different)
