title: Adenosine receptor A3 is a critical mediator in LPS-induced pulmonary inflammation.
abstract: Adenosine receptor A(3) (A(3)) regulates directed movement of polymorphonuclear cells (PMNs) to sites of inflammation and has been implicated as a relevant mediator in models of inflammatory diseases. Here, we sought to characterize the role of A(3) in a murine model of lung inflammation. Initial studies revealed that pulmonary A(3) transcript levels were elevated following LPS exposure in vivo. In addition, inhalation of LPS increased the accumulation of PMNs in wild-type and A(3)(-/-) mice in all lung compartments. Pretreatment with the specific A(3)-agonist Cl-IB-MECA significantly decreased migration of PMNs into lung interstitium and alveolar air space of wild-type mice but not of A(3)(-/-) mice. Lower PMN counts were associated with reduced levels of TNF-α and IL-6 in the alveolar space of wild-type mice that received Cl-IB-MECA. In addition, Cl-IB-MECA attenuated LPS-induced microvascular permeability in wild-type mice as assessed by the extravasation of Evans blue. In pulmonary microvascular endothelial cells, Cl-IB-MECA reduced LPS-induced cytoskeletal remodeling and cell retraction, consistent with a specific role of A(3) for maintaining endothelial integrity. Migratory activity of human PMNs across an endothelial or epithelial monolayer was reduced when A(3) was activated on PMNs. Studies in chimeric mice, however, revealed that Cl-IB-MECA required A(3) on both hematopoietic and nonhematopoietic cells to reduce transmigration in vivo. Together, our results shed new light on the role of A(3) in LPS-induced PMN trafficking in the lung and suggest pharmacological modulation of A(3)-dependent pathways as a promising approach in lung inflammation.
authors.affiliation: Dept. of Anesthesiology and Intensive Care Medicine, University Hospital of Tübingen, Germany.
authors.forename: Rosalyn
authors.initials: R
authors.lastname: Wagner
authors.forename: Kristian-Christos
authors.initials: KC
authors.lastname: Ngamsri
authors.forename: Stefanie
authors.initials: S
authors.lastname: Stark
authors.forename: Irene
authors.initials: I
authors.lastname: Vollmer
authors.forename: Jörg
authors.initials: J
authors.lastname: Reutershan
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D058909:Adenosine A3 Receptor Agonists; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002199:Capillary Permeability; D002465:Cell Movement; D005434:Flow Cytometry; D006801:Humans; D007124:Immunoenzyme Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000098:blood supply / Q000276:immunology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011014:Pneumonia / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics; D043684:Receptor, Adenosine A3 / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D058909:Adenosine A3 Receptor Agonists; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D043684:Receptor, Adenosine A3; D000241:Adenosine; C090034:2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide