Caveolin-1 modulates P2X7 receptor-dependent ATP signaling in pro-inflammatory macrophages.

Abstract

[Background] Macrophage (Mφ) is one of the innate immune cells and related to several chronic inflammatory diseases. Ionotropic purinergic P2X7 receptor plays a key role in the regulation of Mφ functions. Caveolin-1 (Cav-1) is known to modulate the activities of ion channels. In this study, the functional coupling between Cav-1 and P2X7 receptor was examined using Cav-1 knockout (Cav-1 KO) mice.

[Methods] Murine bone marrow-derived Mφ (BMDM) was used in this study. Molecular interaction between Cav-1 and P2X7 receptor was analyzed by proximal ligation assay (PLA). Intracellular [Ca²⁺] and [K⁺] were measured by confocal microscopy with each specific fluorescent indicator. Lytic cell death was analyzed by LDH assay.

[Results] In BMDMs, Cav-1 expression was increased by lipopolysaccharide. PLA revealed the molecular interaction between Cav-1 and P2X7 receptor. The treatment with 1 mM ATP evoked sustained Ca²⁺ influx and K⁺ efflux in BMDMs from wild-type mice. The response was enhanced in BMDMs from Cav-1 KO mice. ATP stimulation induced lytic cell death through P2X7 receptor activation, and this cell death was facilitated in Cav-1 KO mice.

[Conclusion] Cav-1 negatively regulates the activation of P2X7 receptors and results in cell death in Mφ. This study may lead to the development of novel drugs of chronic inflammatory diseases.