Soluble adenylyl cyclase mediates hydrogen peroxide-induced changes in epithelial barrier function

Pedro Ivonnet, Hoshang Unwalla, Matthias Salathe, Gregory E. Conner

Elevated H2O2 levels are associated with inflammatory diseases and H2O2 exposure is known to disrupt epithelial barrier function, leading to increased permeability and decreased electrical resistance. In normal human bronchial epithelial (NHBE) cells, fully differentiated at the air liquid interface (ALI), H2O2 activates an autocrine prostaglandin pathway that stimulates transmembrane adenylyl cyclase (tmAC) as well as soluble adenylyl cyclase (sAC), but the role of this autocrine pathway in H2O2-mediated barrier disruption is not entirely clear. To further characterize the mechanism of H2O2-induced barrier disruption, NHBE cultures were treated with H2O2 and evaluated for changes in transepithelial resistance and mannitol permeability using agonist and inhibitors to dissect the pathway. A short (<10 min) H2O2 treatment was sufficient to induce resistance and permeability changes that occurred 40 min to 1 h later and the changes were partially sensitive to EP1 but not EP4 receptor antagonists. EP1 receptors were localized to the apical compartment of NHBE. Resistance and permeability changes were sensitive to inhibition of sAC but not tmAC and were partially blocked by PKA inhibition. Pretreatment with a PLC inhibitor or an IP3 receptor antagonist reduced changes in resistance and permeability suggesting activation of sAC occurred through increased intracellular calcium. The data support an important role for prostaglandin activation of sAC and PKA in H2O2-induced barrier disruption.