Published ahead of print on December 30, 2005, doi:10.1164/rccm.200508-1200OC
© 2006 American Thoracic Society doi: 10.1164/rccm.200508-1200OC
Leflunomide Prevents Alveolar Fluid Clearance Inhibition by Respiratory Syncytial VirusDepartments of Anesthesiology, Physiology and Biophysics, Pediatrics, Hematology/Oncology, and Microbiology, University of Alabama at Birmingham, Birmingham, Alabama; and Departments of Medicine and Pharmacology, University of North Carolina, Chapel Hill, North Carolina Correspondence and requests for reprints should be addressed to Sadis Matalon, Ph.D., Department of Anesthesiology, University of Alabama at Birmingham, 224 BMR II, 901 South 19th Street, Birmingham, AL 35205-3703. E-mail: sadis{at}uab.edu Rationale: Previously, we demonstrated that intranasal infection of BALB/c mice with respiratory syncytial virus (RSV) resulted in an early 40% reduction in alveolar fluid clearance (AFC), an effect mediated via P2Y purinergic receptors. Objectives: To confirm that RSV-induced inhibition of AFC is mediated by uridine triphosphate (UTP), and to demonstrate that inhibition of de novo pyrimidine synthesis with leflunomide prevents increased UTP release after RSV infection, and thereby also prevents inhibition of AFC by RSV. Methods: BALB/c mice were infected intranasally with RSV strain A2. AFC was measured in anesthetized, ventilated mice by instillation of 5% bovine serum albumin into the dependent lung. Some mice were pretreated with leflunomide or 6-mercaptopurine. Measurements and Main Results: RSV-mediated inhibition of AFC is associated temporally with a 20-nM increase in UTP and ATP content of bronchoalveolar lavage fluid, hypoxemia, and altered nasal potential difference. RSV-mediated nucleotide release, AFC inhibition, and physiologic sequelae thereof can be prevented by pretreatment of mice with the de novo pyrimidine synthesis inhibitor leflunomide, which is not toxic to the mice, and which does not affect RSV replication in the lungs. In contrast, pretreatment of mice with 6-mercaptopurine, an inhibitor of de novo purine synthesis, has no beneficial effect on AFC or other indicators of disease progression. Finally, RSV-mediated inhibition of AFC is prevented by volume-regulated anion channel inhibitors. Conclusion: Pyrimidine synthesis or release pathways may provide novel therapeutic targets to counter the pathophysiologic sequelae of impaired AFC in RSV disease.
Key Words: ion transport • paramyxovirus infections • pneumonia, viral • pulmonary edema This article has been cited by other articles:
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