E-Npp3 Controls Plasmacytoid Dendritic Cell Numbers In The Small Intestine

Extracellular adenosine 5'-triphosphate (ATP) performs multiple functions including activation and induction of apoptosis of many cell types. The ATP-hydrolyzing ectoenzyme ectonucleotide pyrophosphatase/phosphodiesterase 3 (E-NPP3) regulates ATP-dependent chronic allergic responses by mast cells and basophils. However, E-NPP3 is also highly expressed on epithelial cells of the small intestine. In this study, we showed that E-NPP3 controls plasmacytoid dendritic cell (pDC) numbers in the intestine through regulation of intestinal extracellular ATP. In Enpp3(-/-) mice, ATP concentrations were increased in the intestinal lumen. pDC numbers were remarkably decreased in the small intestinal lamina propria and Peyer's patches. Intestinal pDCs of Enpp3(-/-) mice showed enhanced cell death as characterized by increases in annexin V binding and expression of cleaved caspase-3. pDCs were highly sensitive to ATP-induced cell death compared with conventional DCs. ATP-induced cell death was abrogated in P2rx7(-/-) pDCs. Accordingly, the number of intestinal pDCs was restored in Enpp3(-/-) P2rx7(-/-) mice. These findings demonstrate that E-NPP3 regulates ATP concentration and thereby prevents the decrease of pDCs in the small intestine.