A2A adenosine receptor activation prevents neutrophil aging and promotes polarization from N1 towards N2 phenotype.

Extracellular adenosine is a biologically active signaling molecule that accumulates at sites of metabolic stress in sepsis. Extracellular adenosine has potent immunosuppressive effects by binding to and activating G protein-coupled A_2A adenosine receptors (A_2AARs) on the surface of neutrophils. A_2AAR signaling reproduces many of the phenotypic changes in neutrophils that are characteristic of sepsis, including decreased degranulation, impaired chemotaxis, and diminished ability to ingest and kill bacteria. We hypothesized that A_2AARs also suppress neutrophil aging, which precedes cell death, and N1 to N2 polarization. Using human neutrophils isolated from healthy subjects, we demonstrate that A_2AAR stimulation slows neutrophil aging, suppresses cell death, and promotes the polarization of neutrophils from an N1 to N2 phenotype. Using genetic knockout and pharmacological blockade, we confirmed that A_2AARs decrease neutrophil aging in murine sepsis induced by cecal ligation and puncture. A_2AARs expression is increased in neutrophils from septic patients compared to healthy subject but A_2AAR expression fails to correlate with aging or N1/N2 polarization. Our data reveals that A_2AARs regulate neutrophil aging in healthy but not septic neutrophils. [ABSTRACT FROM AUTHOR]