Toll-like receptors (TLRs) trigger innate immune responses through their recognition of conserved molecular
ligands of either endogenous or microbial origin. Although activation, function, and signaling pathways of TLRs were already well-studied, their precise function in specific cell types, especially innate immune cells, needs to be further clarified. In this study, we showed that when significantly decreased amounts of membrane CD39, an
adenosine triphosphate (
ATP)-degrading
enzyme, were detected in
lipopolysaccharide (LPS)-treated bone marrow-derived dendritic cells (BMDCs), Cd39
mRNA expression, and whole-cell CD39 expression were at the same levels as those in untreated BMDCs. Further experiments demonstrated that the downregulation of membrane CD39 expression in LPS-treated BMDCs was mediated by endocytosis, leading to membrane-exposed CD39 downregulation, which was positively associated with decreased enzymatic activity in
ATP metabolism and increased extracellular
ATP accumulation. The accumulated
ATP promoted intracellular
calcium accumulation and IL-1β production in BMDCs through P2X7 signaling activation. Further research revealed that not only LPS but also other TLR
ligands, excluding polyI:C, induced CD39 internalization in BMDCs and that the MyD88 pathway was critical in this process. The results suggested that the activation of CD39 internalization in DCs induced by a TLR
ligand caused increased
ATP accumulation, leading to
P2X7 receptor activation that mediated a proinflammatory effect. Considering the strong modulatory effect of extracellular
ATP accumulation on the immune response and
inflammation, the manipulation of membrane CD39 expression on DCs may have implications on the regulation and treatment of inflammatory responses.