ATP in the pathogenesis of lung emphysema

Extracellular ATP is a signaling molecule that often serves as a danger signal to alert the immune system of tissue damage. This molecule activates P2 nucleotide receptors, that include the ionotropic P2X receptors and metabotropic P2Y receptors. Recently, it has been reported that ATP accumulates in the airways of both asthmatic patients and sensitized mice after allergen challenge. The role and function of ATP in the pathogenesis of chronic obstructive pulmonary diseases (COPD) are not well understood. In this study we investigated the effect of cigarette smoke on purinergic receptors and ATP release by neutrophils. Neutrophils and their mediators are key players in the pathogenesis of lung emphysema. Here we demonstrated that in an in vivo model of cigarette smoke-induced lung emphysema, the amount of ATP was increased in the bronchoalveolar lavage fluid. Moreover, activation of neutrophils with cigarette smoke extract induced ATP release. Treatment of neutrophils with apyrase (catalyses the hydrolysis of ATP to yield AMP) and suramin (P2-receptor antagonist) abrogated the release of CXCL8 and elastase induced by cigarette smoke extract and exogenous ATP. These observations indicate that activation of purinergic signaling by cigarette smoke may take part in the pathogenesis of lung emphysema.