P2X7R activation drives distinct IL-1 responses in dendritic cells compared to macrophages

Abstract

The P2X7R is a functionally distinct member of the P2X family of non-selective cation channels associated with rapid activation of the inflammasome complex and signalling interleukin (IL)-1β release in macrophages. The main focus of this investigation was to compare P2X7R-driven IL-1 production by primary murine bone marrow derived dendritic cells (BMDC) and macrophages (BMM). P2X7R expression in murine BMDC and BMM at both transcriptional (P2X7A variant) and protein levels was demonstrated. Priming with lipopolysaccharide (LPS) and receptor activation with adenosine triphosphate (ATP) resulted in markedly enhanced IL-1 (α and β) secretion in BMDC compared with BMM. In both cell types IL-1 production was profoundly inhibited with a P2X7R-specific inhibitor (A-740003) demonstrating that this release is predominantly a P2X7R-dependent process. These data also suggest that P2X7R and caspase-1 activation drive IL-1α release from BMDC. Both cell types expressed constitutively the gain-of-function P2X7K as well as the full P2X7A variant at equivalent levels. LPS priming reduced significantly levels of P2X7A but not P2X7K transcripts in both BMDC and BMM. P2X7R-induced pore formation, assessed by YO-PRO-1 dye uptake, was greater in BMDC, and these cells were protected from cell death. These data demonstrate that DC and macrophages display distinct patterns of cytokine regulation, particularly with respect to IL-1, as a consequence of cell-type specific differences in the physicochemical properties of the P2X7R. Understanding the cell-specific regulation of these cytokines is essential for manipulating such responses in health and disease.