Mitochondria Regulate Neutrophil Activation by Generating ATP for Autocrine Purinergic Signaling

Polymorphonuclear neutrophils (PMNs) form the first line of defense against invading microorganisms. We have shown previously that ATP release and autocrine purinergic signaling via P2Y2 receptors are essential for PMN activation. Here we show that mitochondria provide the ATP that initiates PMN activation. Stimulation of formyl peptide receptors increases the mitochondrial membrane potential (Delta psi m) and triggers a rapid burst of ATP release from PMNs. This burst of ATP release can be blocked by inhibitors of mitochondrial ATP production and requires an initial formyl peptide receptor-induced Ca2+ signal that triggers mitochondrial activation. The burst of ATP release generated by the mitochondria fuels a first phase of purinergic signaling that boosts Ca2+ signaling, amplifies mitochondrial ATP production, and initiates functional PMN responses. Cells then switch to glycolytic ATP production, which fuels a second round of purinergic signaling that sustains Ca2+ signaling via P2X receptor-mediated Ca2+ influx and maintains functional PMN responses such as oxidative burst, degranulation, and phagocytosis.