Related Experiment Videos
Purinergic modulation of interleukin-1 beta release from microglial cells stimulated with bacterial endotoxin
Abstract:
Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today, 16:524-528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R. A. North and G. Buell, 1996. Science (Wash. DC). 272:735-737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X7 receptor by exogenous ATP causes a large and rapid release of mature IL-1 beta. In the present report we investigated the role of microglial P2Z/P2X7 receptor in IL-1 beta release triggered by LPS. Our data suggest that LPS-dependent IL-1 beta release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X7 blocker oxidized ATP and modulated by ATP-hydrolyzing enzymes such as apyrase or hexokinase. Furthermore, microglial cells release ATP when stimulated with LPS. LPS-dependent release of ATP is also observed in monocyte-derived human macrophages. It is suggested that bacterial endotoxin activates an autocrine/paracrine loop that drives ATP-dependent IL-1 beta secretion.
Insights
Lipopolysaccharide (LPS) stimulates microglial cells to release ATP, activating the P2Z/P2X7 receptor. This purinergic receptor signaling drives the release of interleukin-1 beta (IL-1 beta), suggesting an autocrine loop in immune responses.
Area of Science:
- Immunology
- Neuroscience
- Cell Biology
Background:
- Microglial cells possess the P2Z/P2X7 purinergic receptor, which mediates ion fluxes and plasma membrane permeabilization.
- The precise physiological function of the P2Z/P2X7 receptor, particularly in microglial cells, remains largely unknown.
- Activation of the P2Z/P2X7 receptor by extracellular ATP can induce the release of mature interleukin-1 beta (IL-1 beta).
Purpose of the Study:
- To investigate the role of the microglial P2Z/P2X7 purinergic receptor in lipopolysaccharide (LPS)-induced IL-1 beta release.
- To determine if LPS stimulation of microglial cells leads to the release of ATP.
- To elucidate the involvement of an autocrine/paracrine loop in LPS-mediated IL-1 beta secretion.
Main Methods:
- Utilized selective P2Z/P2X7 receptor blockers, such as oxidized ATP, to inhibit receptor activation.
- Employed ATP-hydrolyzing enzymes, including apyrase and hexokinase, to modulate ATP levels.
- Measured IL-1 beta release and ATP release from microglial cells and human macrophages stimulated with LPS.
Main Results:
- LPS-induced IL-1 beta release from microglial cells was significantly inhibited by oxidized ATP, indicating P2Z/P2X7 receptor involvement.
- ATP-hydrolyzing enzymes modulated LPS-dependent IL-1 beta release, further supporting the role of the purinergic receptor.
- Microglial cells and monocyte-derived human macrophages were observed to release ATP upon stimulation with LPS.
Conclusions:
- The P2Z/P2X7 purinergic receptor plays a critical role in LPS-induced IL-1 beta secretion by microglial cells.
- LPS stimulation triggers an autocrine/paracrine loop involving ATP release and P2Z/P2X7 receptor activation to drive IL-1 beta secretion.
- Bacterial endotoxins may utilize this ATP-dependent pathway to modulate inflammatory responses mediated by microglial cells.