Adenosine and adenosine receptors: their contribution to airway inflammation and therapeutic potential in asthma.

Growing evidence emphasizes that the purine nucleoside adenosine plays an active role as local regulator in airway inflammation and pulmonary diseases. The notion that increased adenosine concentrations are associated with lung inflammation indicates the importance of this signaling pathway, which involves the activation of a family of cell surface G-protein coupled receptor subtypes named as A(1), A(2A), A(2B) and A(3). Recently, important progress has been made to better clarify the role of these receptors in a variety of inflammatory airway disorders including asthma. As a consequence, new molecules with high affinity and high selectivity for the human adenosine receptors subtypes designed to control the airway inflammatory component of asthma have been launched and are currently tested in clinical trials as anti-asthma treatments. With the availability of these molecules for testing in humans, the role of adenosine receptors in asthma can now be validated.