Long-term CFTR inhibition modulates 15d-prostaglandin J2 in human pulmonary cells

Prostaglandins, the products of arachidonic acid release and oxidation by phospholipase A(2) and cyclooxygenases (COX) 1 and 2 respectively, are known as important inflammation mediators. However, their diversity in structure, properties and cell specificity make their physiological function difficult to define. In the lung, the prostaglandin D(2) (PGD(2)) metabolite 15d-PGJ(2) is known to modulate the properties of a large number of intracellular compounds, leading to both pro- and anti-inflammatory effects. In the lung, the serous sub-mucosal glands, that strongly express CFTR (cystic fibrosis transmembrane conductance regulator), play an important role in the defence against inflammation, and their derivatives Calu-3 cells are largely used in in vitro experiments. The present study was undertaken to determine whether the PGD synthase-PGD(2)-15d-PGJ(2) pathway is active in Calu-3 cells, and whether its activity requires a functional CFTR. Both cellular and released PGD(2) and 15d-PGJ(2) were measured in cells treated with CFTR inhibitors and stimulated or not with inflammatory IL-1β. Pretreatment with either CFTR(inh172) or GlyH101 inhibitors decreased the basal cell content of both prostaglandins, and so did acute stimulation with IL-1β, but the latter was dramatically reversed in CFTR(inh172)-treated cells. CFTR(inh172) also altered the release of inflammation mediators PGE(2) and IL-8, and this effect was blunted by exogenous 15d-PGJ(2). CFTR(inh172)-induced modulation of 15d-PGJ(2) cellular content was not detected in CFTR-silenced Calu-3 cells, but it was reproduced in pulmonary CFBE41o-cells, which express F508del-CFTR. These results show that cellular 15d-PGJ(2) production, which controls PGE(2) and IL-8 release, is disturbed by CFTR dysfunction. In Calu-3 cells, 15d-PGJ(2) production resulted from COX-2-regulated COX-1 activation, while CFTR(inh172)-induced alteration of 15d-PGJ(2) synthesis involved both decreased expression of PGD synthase and disturbed relationships between both COXs. CFTR-mediated regulation of PGD synthase-PGD(2)-15d-PGJ(2) pathway and cellular 15d-PGJ(2) effects may involve a large number of molecular reactive pathways. Their exploration should help understand the development of CF inflammation and might bring new perspectives in its treatment.