Adenosine receptors as promising therapeutic targets for drug development in chronic airway inflammation.

A growing body of evidence has emerged in support of a pro-inflammatory role for adenosine in the pathogenic mechanisms of chronic inflammatory disorders of the airways such as asthma and COPD. The demonstration that adenosine enhances mast cell allergen-dependent activation, the notion that elevated levels of adenosine are present in chronically inflamed airways, and the results from exposure studies of nebulised adenosine showing dose-dependent bronchoconstriction in subjects with asthma and COPD, emphasise the importance of adenosine in the initiation, persistence and progression in these common inflammatory disorders of the airways. Adenosine exerts its manifold biological activities by interacting with at least four adenosine receptor subtypes.

Adenosine signalling in airways.

Current research endeavours indicate that adenosine elicits strong inflammatory responses in the lung and might be involved in the pathogenic mechanisms of chronic inflammatory disorders of the airways such as asthma and chronic obstructive pulmonary disease (COPD). The contribution of adenosine-associated effector mechanisms to the initiation, persistence and progression of the inflammatory response is highly heterogeneous and is dictated by the expression pattern of four different adenosine receptors. Selective activation or blockade of these sites can therefore be exploited in an attempt to generate novel therapies for asthma and COPD.