EXTRACELLULAR ATP TRIGGERS IL-1-BETA RELEASE BY ACTIVATING THE PURINERGIC P2Z RECEPTOR OF HUMAN MACROPHAGES

Extracellular ATP (ATP(e)) is known to cause release of processed IL-1 beta from LPS-treated macrophages and microglial cells. IL-1 beta rel ease is fast and thought to be associated with cell death, We have rei nvestigated this process to identify 1) the purinegic receptor involve d; 2) the relationship to cell death; and 3) pharmacologic agonists or antagonists able to modulate IL-1 beta release, Our data confirm that ATP(e) is a powerful stimulus for IL-1 beta release from LPS-treated human macrophages; however, we also show that IL-1 beta release is not necessarily associated with cell death, as it occurs at lower ATP con centrations and much earlier than leakage of cytoplasmic markers. The selective purinergic P2Z receptor agonist benzoylbenzoyl ATP was at le ast one order of magnitude more powerful than ATP, but also had a stro ng cytotoxic effect. 2-Methylthio-ATP was equipotent as ATP(e) at the optimal concentration of 1 mM, but markedly inhibitory at higher conce ntrations. The irreversible P2Z blocker-oxidized ATP completely inhibi ted ATP(e)-induced IL-1 beta release. IL-1 beta release also was inhib ited by increasing the K+ concentration of the incubation medium. Thes e data suggest that ATP(e) triggers IL-1 beta via the purinergic P2Z r eceptor recently shown to be expressed by human macrophages and identi fied as a new member of the P2X family (P2X(7)), and provide pharmacol ogic tools for the modulation of IL-1 beta release in vitro and, possi bly, in vivo.