CD73-dependent adenosine dampens interleukin-1β–induced CXCL8 production in gingival fibroblasts: Association with heme oxygenase-1 and adenosine monophosphate–activated protein kinase

Background: During inflammation, stressed or infected cells can release adenosine triphosphate (ATP) to the extracellular medium, which can be hydrolyzed to adenosine by ectonucleotidases such as ectonucleoside triphosphate diphosphohydrolase 1 (CD39) and 5^′-nucleotidase (CD73). The role of CD73 in the modulation of cytokine release by human gingival fibroblasts (HGFs) remains underexplored. Here, we investigated whether CD73-mediated hydrolysis of extracellular ATP (eATP) could affect interleukin (IL)-1B-induced CXCL8 secretion. Methods: The levels of mRNA expression of adenosine receptors, CD39 and CD73 of periodontitis samples were retrieved from a public database. Moreover, HGF mRNA levels were measured by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) after 3, 6, or 24 hours of IL-1B stimulation. IL-1B-induced CXCL8 protein levels were measured after pretreatment with 100-µM eATP in the presence or absence of CD73 inhibitor. The effect of eATP degradation to adenosine on CXCL8 levels was investigated using agonist and antagonist of adenosine receptors. Results: Levels of CD39, CD73, and adenosine receptor mRNA were differentially modulated by IL-1B. ATP pretreatment impaired IL-1B-induced CXCL8 secretion and required activation of heme oxygenase-1 (HO-1) and phosphorylated adenosine monophosphate–activated protein kinase (pAMPK). The inhibition of CD73 or the inhibition of adenosine receptors abrogated the ATP effect on CXCL8 secretion. Conclusions: CD73-generated adenosine dampens IL-1B-induced CXCL8 in HGFs and involves HO-1 and pAMPK signaling. These results imply that CD73 is a negative regulator of the inflammatory microenvironment, suggesting that this ectoenzyme could be involved in the generation of deficient CXCL8 gradient in chronic inflammation.