The Effect of Equilibriative Nucleoside Transporter 1 on Pseudomonas Aeruginosa‐Induced Acute Lung Injury

Abstract

Acute lung injury (ALI) is hallmarked by lung edema, excessive inflammation, and respiratory failure resulting in 40% mortality. Multidrug resistant Pseudomonas aeruginosa (P. aeruginosa) infections often cause ALI in patients with compromised immunity. It is well established that Adenosine, a signaling nucleoside increased upon tissue injury, has been shown to protect against ALI through activation of adenosine receptors (ARs). Extracellular and intracellular adenosine concentrations are regulated by equilibriative nucleoside transporters (ENTs). Whether altering adenosine signaling and uptake can prevent or treat bacterial P. aeruginosa‐induced ALI is unknown. We hypothesize that ENT1 inhibition will increase extracellular adenosine and protect against P. aeruginosa‐induced ALI via activation of ARs. ENT1 pharmacological inhibitors and null mice were used to determine the effects of ENT1 inhibition on P. aeruginosa‐induced ALI. We found that P. aeruginosa infections induced ALI in C57BL/6 mice in a dose dependent manner. Pharmacological inhibition of ENT1 via NBTI significantly attenuated P. aeruginosa‐induced ALI, as assessed by wet‐to‐dry lung weight, bronchoalveolar lavage (BAL) protein levels, BAL inflammatory cells, and pulmonary function determined by static lung compliance, tissue damping, and tissue elastance. NBTI also increased bacterial clearance in mice infected with P. aeruginosa. Additionally, NBTI attenuated P. aeruginosa‐induced IL‐1β levels in the BAL of mice. Consistent with ENT1 pharmacological inhibitor data, ENT1 null mice attenuated P. aeruginosa‐induced ALI as assessed by BAL protein and BAL cell counts. Finally, agonists of A2AR and A2BR mimicked NBTI blunting of P. aeruginosa‐induced ALI, whereas, antagonists against A2AR or A2BR diminished the protective effect of NBTI inhibition on P. aeruginosa‐induced ALI. These results suggest that inhibition of ENT1 protects against P. aeruginosa‐induced ALI via adenosine‐mediated activation of A2AR and A2BR. Inhibition of ENT1 may be a novel approach to prevent and treat P. aeruginosa‐ induced ALI.Support or Funding InformationThis work was in part supported by NIGMS P20GM103652 to S. Rounds and Q. Lu, RO1 HL130230 to Q. Lu, PULM‐019‐14F to S. Rounds, and NIEHS T32 ES007272 to E. Chambers.