On the biosynthesis of 15-HETE and eoxin C4 by human airway epithelial cells

Several lines of evidence indicate that 15-lipoxygenase type 1 (15-LO-1) plays a pathophysiological role in asthma. The aim for this study was to investigate the 15-LO-1 expression and activity in primary human airway epithelial cells cultivated on micro-porous filters at air-liquid interface. Incubation of human airway epithelial cells with arachidonic acid led to the formation of 15(S)-hydroxy-eicosatetraenoic acid (15-HETE) and exposing the cells to bacteria or physical injury markedly increased their production of 15-HETE. The cells were also found to convert arachidonic acid to eoxin C4 (EXC4). Subcellular fractionation revealed that the conversion of EXA4 to EXC4 was catalyzed by a soluble glutathione transferase (GST). The GST P1-1 enzyme was found to possess the highest activity of the investigated soluble GSTs. Following IL-4 treatment of airway epithelial cells, microarray analysis confirmed high expression of 15-LO-1 and GST P1-1, and immunohistochemical staining of bronchial biopsies revealed co-localization of 15-LO-1 and GST P1-1 in airway epithelial cells. These results indicate that respiratory infection and cell injury may activate the 15-LO pathway in airway epithelial cells. Furthermore, we also demonstrate that airway epithelial cells have the capacity to produce EXC4.