NADPH Oxidase-dependent Acid Production in Airway Epithelial Cells

Christian Schwarzer, Terry E. Machen, Beate Illek, Horst Fischer
2004 Journal of Biological Chemistry  
The purpose of this study was to determine the role of NADPH oxidase in H ؉ secretion by airway epithelia. In whole cell patch clamp recordings primary human tracheal epithelial cells (hTE) and the human serous gland cell line Calu-3 expressed a functionally similar zincblockable plasma membrane H ؉ conductance. However, the rate of H ؉ secretion of confluent epithelial monolayers measured in Ussing chambers was 9-fold larger in hTE compared with Calu-3. In hTE H ؉ secretion was blocked by
more » ... was blocked by mucosal ZnCl 2 and the NADPH oxidase blockers acetovanillone and 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF), whereas these same blockers had no effect in Calu-3. We determined levels of transcripts for the NADPH oxidase transmembrane isoforms (Nox1 through -5, Duox1 and -2, and p22 phox ) and found Duox1, -2, and p22 phox to be highly expressed in hTE, as well as the intracellular subunits p40 phox , p47 phox , and p67 phox . In contrast, Calu-3 lacked transcripts for Duox1, p40 phox , and p47 phox . Anti-Duox antibody staining resulted in prominent apical staining in hTE but no significant staining in Calu-3. When treated with amiloride to block the Na ؉ /H ؉ exchanger, intracellular pH in hTE acidified at significantly higher rates than in Calu-3, and treatment with AEBSF blocked acidification. These data suggest a role for an apically located Duox-based NADPH oxidase during intracellular H ؉ production and H ؉ secretion, but not in H ؉ conduction.
doi:10.1074/jbc.m404983200 pmid:15210697 fatcat:4noylnd64bdklg4y6ym4kaexv4