Moraxella catarrhalis induces ERK- and NF-kappaB-dependent COX-2 and prostaglandin E2 in lung epithelium

Moraxella catarrhalis is a major cause of infectious exacerbations of chronic obstructive lung disease. Cyclooxygenase (COX)-derived prostaglandins, such as prostaglandin E(2) (PGE(2)), are considered to be important regulators of lung function. The present authors tested the hypothesis that M. catarrhalis induces COX-2-dependent PGE(2) production in pulmonary epithelial cells. In the present study, the authors demonstrate that M. catarrhalis specifically induces COX-2 expression and subsequent PGE(2) release in pulmonary epithelial cells. Furthermore, the prostanoid receptor subtypes EP2 and EP4 were also upregulated in these cells. The M. catarrhalis-specific ubiquitous cell surface protein A1 was important for the induction of COX-2 and PGE(2). Moreover, M. catarrhalis-induced COX-2 and PGE(2) expression was dependent on extracellular signal-regulated kinase 1/2-driven activation of nuclear factor-kappaB, but not on the activation of p38 mitogen-activated protein kinase. In conclusion, the present data suggest that ubiquitous cell surface protein A1 of Moraxella catarrhalis, extracellular signal-regulated kinase 1/2 and nuclear factor-kappaB control cyclooxygenase-2 expression and subsequent prostaglandin E(2) release by lung epithelial cells. Moraxella catarrhalis-induced prostaglandin E(2) expression might counteract lung inflammation promoting colonisation of the respiratory tract in chronic obstructive pulmonary disease patients.