Paradoxical Effects of Hydrogen Peroxide on Human Airway Anion Secretion

Abstract

The present study concerns intriguing effects of hydrogen peroxide (H 2 O 2 ) on cAMP-mediated anion secretion in polarized human airway epithelia. Although H 2 O 2 applied to the apical and basolateral membrane increases short-circuit currents (I SC ) with analogous properties, it has opposite effects on subsequent cAMP-activated I SC responses. Namely, forskolin (FK)-induced I SC responses were down-regulated by the apical presence of H 2 O 2 , whereas they were up-regulated by its basolateral presence. Despite this contrasting effect, oxidative stimuli from either aspect of the monolayer hindered FK-induced increments in cytosolic cAMP levels and apical membrane Cl Ϫ conductance. The site-dependent effects of H 2 O 2 were reproduced in the responses to 8-bromo-cAMP. Estimation of the anionic composition of the I SC revealed that the FK up-regulated both bumetanide [an Na Ϫ secretion by an increase in Cl Ϫ uptake via basolateral NKCC1, whose sensitivities to cAMP/protein kinase A are up-regulated, overcoming the H 2 O 2 -induced inhibition of cAMP-mediated apical anion conductance. The basolateral membrane-specific effects of H 2 O 2 may be relevant to the basolateral cytoskeleton, which is believed to interact with NKCC1.

H2O2 Stimulates Cystic Fibrosis Transmembrane Conductance Regulator through an Autocrine Prostaglandin Pathway, Using Multidrug-Resistant Protein–4

“…Thus, all further experiments were performed in the presence of 10 mM amiloride to block epithelial sodium channel. Both the amplitude and duration of the I SC increase were dependent on the [ Basolateral stimulation with H 2 O 2 , which was also sensitive to CFTR inhibitors, required higher concentrations to induce Together, these data differed from those in previous reports using cell lines, in that high H 2 O 2 concentrations in primary, fully differentiated human airway epithelial cells led to transient changes in H 2 O 2 -induced CFTR anion conductance (15,16), similar to the results of Dazy and colleagues (25) using hydroxyl radicals. To assess the role of the hydroxyl radical, cultures were pretreated with deferoxamine and stimulated with H 2 O 2 in the presence of deferoxamine.…”

“…CFTR channel activity is essential for the regulation of this process. Therefore, the concentration-dependent effects of H 2 O 2 on CFTR activity will (16,25), although the responses in human nasal epithelial cells were ascribed to the effects of hydroxyl radicals (25). NHBE cells, redifferentiated at the ALI, display both sustained and transient responses in an [H 2 O 2 ]-dependent fashion.…”

“…CFTR-mediated epithelial anion secretion has been shown to occur in response to exogenous H 2 O 2 in several cell lines used as models of airway epithelia (15,16,25). To clarify the effects of different amounts of [H 2 O 2 ] on anion secretion by cells most closely resembling the native human airway epithelium (26) and to study the mechanism of H 2 O 2 actions, NHBE cultures fully differentiated at the ALI were mounted in Ussing chambers and exposed to increasing concentrations of either apically or basolaterally added H 2 O 2 .…”

“…In the bronchial submucosal adenocarcinoma cell line Calu-3, CFTR activity is increased by exposure of the airway epithelium to exogenous H 2 O 2 (15,16). In cell lines, the effect of H 2 O 2 on CFTR is reported to occur through increases in transmembrane adenylyl cyclase activity and through the activation of two K 1 channels (15), most likely KCNQ1 and KCNN4, which are located in the basolateral membrane.…”

Dual Pathway Activated by tert-Butyl Hydroperoxide in Human Airway Anion Secretion

“…They were 48.5 Ϯ 6.1 A/cm 2 (n ϭ 4) and 46. (Ohashi et al, 2006). Furthermore, ⌬I SC-20MIN after the application of 10 mM H 2 O 2 was decreased to below the basal level: ⌬I SC-20MIN ϭ Ϫ7.6 Ϯ 2.0 A/cm 2 (n ϭ 4).…”