Adenosine A 2A receptors are up-regulated and control the activation of human alveolar macrophages

• Published in: Pulmonary pharmacology & therapeutics Vol. 45; p. 90
• Main Authors: Alfaro, Tiago M, Rodrigues, Diana I, Tomé, Ângelo R, Cunha, Rodrigo A, Robalo Cordeiro, Carlos
• Format: Journal Article
• Language: English
• Published: England 01.08.2017
• Subjects: Adenosine - administration & dosage; Adenosine - analogs & derivatives; Adenosine - pharmacology; Adenosine A2 Receptor Agonists - administration & dosage; Adenosine A2 Receptor Agonists - pharmacology; Adult; Calcium - metabolism; Dose-Response Relationship, Drug; Female; Fluorescent Antibody Technique; Fluorescent Dyes; Fura-2; Humans; Lung Diseases, Interstitial - drug therapy; Lung Diseases, Interstitial - pathology; Macrophages, Alveolar - metabolism; Male; Middle Aged; N-Formylmethionine Leucyl-Phenylalanine - administration & dosage; Phenethylamines - administration & dosage; Phenethylamines - pharmacology; Prospective Studies; Receptor, Adenosine A2A - drug effects; Receptor, Adenosine A2A - genetics; Time Factors; Up-Regulation; Adenosine; Respiratory tract diseases; Inflammation; Anti-inflammatory agents
• ISSN: 1522-9629

Chronic inflammatory lung diseases remain a health concern and new anti-inflammatory treatments are needed. Targeting adenosine A receptors (A R) affords robust anti-inflammatory effects in animal models, but the translation of this promising strategy to humans has been challenging, possibly due to interspecies differences in receptor distribution and effects. Thus, we now assessed the efficiency of a selective A R agonist to control the activation of fresh human alveolar inflammatory cells. We collected bronchoalveolar lavage fluid from patients with interstitial lung disease and loaded alveolar cells with the intracellular free calcium probe FURA-2/AM. Calcium transients were then recorded in response to superfusion with a proinflammatory peptide (N-formylmethionyl-leucyl-phenylalanine - FMLP), in the absence or presence of the selective A R agonist CGS21680. In a second experiment, cells were continuously exposed to FMLP and A R density was assessed by immunocytochemistry. Sixteen patients were included, nine for analysis of calcium transients, and seven for immunocytochemistry. When alveolar macrophages were exposed to 100 nM FMLP for 120 s, a peak elevation of intracellular free calcium levels (97.0% over baseline) was recorded; CGS21680 (100 and 300 mM) significantly reduced this peak to 89.5% and 81.5%, respectively. The immunofluorescence analysis revealed a time-dependent increase of A R density in alveolar macrophage upon exposure to 1 μM FMLP, up to 148% of control at 6 h. These results show that pro-inflammatory stimuli up-regulate A R and their activation dampens the impact of pro-inflammatory stimuli. This supports that targeting A R is a promising therapy for human lung inflammatory diseases, especially for diseases with a strong inflammatory component.