Loss of CD73-mediated extracellular adenosine production exacerbates inflammation and abnormal alveolar development in newborn mice exposed to prolonged hyperoxia.

BackgroundHyperoxic lung injury is characterized by cellular damage from high oxygen concentrations that lead to an inflammatory response and it disrupts normal alveolarization in the developing newborn lung. Adenosine is a signaling molecule that is generated extracellularly by ecto-5'-nucleotidase (CD73) in response to injury. Extracellular adenosine signals through cell surface receptors and has been found to have a protective role in acute injury situations; however, chronic elevations have been associated with detrimental changes in chronic lung diseases. We hypothesized that hyperoxia-induced lung injury leads to CD73-mediated increases in extracellular adenosine, which are detrimental to the newborn lung.MethodsC57Bl/6 and CD73-/- mice were exposed to 95% oxygen, 70% oxygen, or room air. Adenosine concentration and markers of pulmonary inflammation and lung development were measured.ResultsExposure to hyperoxia caused pulmonary inflammation and disrupted normal alveolar development in association with increased pulmonary adenosine levels. Loss of CD73-mediated extracellular adenosine production led to decreased survival with exposure to 95% oxygen, and exacerbated pulmonary inflammation and worsened lung development with 70% oxygen exposure.ConclusionExposure to hyperoxia causes lung injury associated with an increase in adenosine concentration, and loss of CD73-mediated adenosine production leads to worsening of hyperoxic lung injury.Pediatric Research advance online publication, 23 August 2017; doi:10.1038/pr.2017.176.