TY - JOUR T1 - Extracellular adenosine enhances the ability of PMNs to kill <em>Streptococcus pneumoniae</em> by inhibiting IL-10 production JF - bioRxiv DO - 10.1101/716456 SP - 716456 AU - Nalat Siwapornchai AU - James N. Lee AU - Essi Y. I. Tchalla AU - Manmeet Bhalla AU - Jun Hui Yeoh AU - John M. Leong AU - Elsa N. Bou Ghanem Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/07/26/716456.abstract N2 - PMNs are crucial for initial control of Streptococcus pneumoniae (pneumococcus) lung infection; however, as the infection progresses their persistence in the lungs is detrimental. We found that the progressive inability of PMNs to control infection correlated with phenotypic differences characterized by a decrease in CD73 expression, an enzyme required for production of extracellular adenosine (EAD). EAD production by CD73 was crucial for PMN function as PMNs from CD73-/- mice failed to kill pneumococci and supplementation with EAD reversed this defect. Further, adoptive transfer of PMNs from wild type mice prior to lung challenge was sufficient to boost the resistance of CD73-/- mice to infection. Importantly, CD73 activity was important for the antimicrobial function of PMNs from human donors. We found that CD73-mediated resistance is due to its inhibitory effects on IL-10. PMNs from CD73-/-, but not wild type mice, up-regulated IL-10 production upon pneumococcal infection in the lungs and in vitro. IL-10 inhibited PMN function, as addition of recombinant IL-10 impaired the ability of PMNs from wild type mice to kill pneumococci ex vivo, and treatment with anti-IL-10 boosted the bactericidal activity of CD73-/- PMNs. Blocking IL-10 also boosted the resistance of CD73-/- mice to pneumococcal pneumonia. CD73/IL-10 did not affect apoptosis, bacterial uptake and intracellular killing or production of anti-microbial Neutrophil Elastase and Myeloperoxidase. Rather, inhibition of IL-10 production by CD73 was important for production of extracellular ROS by PMNs upon S. pneumoniae infection. This study demonstrates that CD73 regulates PMN anti-microbial phenotype during pneumococcal pneumonia.Summary Sentence Extracellular adenosine produced by CD73 promotes the ability of PMNs to kill Streptococcus pneumoniae by blunting IL-10 productionCFUColony Forming UnitsCTCycle thresh-holdEADExtracellular adenosineI.PIntra peritonealI.TIntra trachealMFI(Mean Fluorescent Intensity)MOIMultiplicity of infectionMPOMyeloperoxidaseNENeutrophil ElastaseOPHOpsonophagocyticPLYPneumolysinPMAPhorbol 12-myristate 13-acetatePMNsPolymorphonuclear leukocytesPneumococcusStreptococcus pneumoniaeROSReactive oxygen speciesWTWild type ER -