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

Area of Science:

• Cell biology
• Epithelial physiology
• Inflammatory disease mechanisms

Background:

• Elevated hydrogen peroxide (H2O2) is linked to inflammatory diseases.
• H2O2 exposure impairs epithelial barrier function, increasing permeability and reducing electrical resistance.
• The role of H2O2-induced autocrine prostaglandin pathways in normal human bronchial epithelial (NHBE) cells is not fully understood.

Purpose of the Study:

• To investigate the mechanism of H2O2-induced epithelial barrier disruption.
• To elucidate the role of specific signaling pathways, including adenylyl cyclases and prostaglandin receptors, in H2O2-mediated effects.

Main Methods:

• NHBE cells differentiated at the air-liquid interface (ALI) were treated with H2O2.
• Transepithelial electrical resistance and mannitol permeability were measured.
• Agonists and inhibitors targeting prostaglandin receptors, adenylyl cyclases (tmAC, sAC), PKA, PLC, and IP3 receptors were used.

Main Results:

• Short H2O2 exposure (<10 min) caused barrier disruption (decreased resistance, increased permeability) within 40-60 min.
• These changes were partially sensitive to EP1 receptor antagonism and blocked by sAC inhibition, but not tmAC inhibition.
• Barrier disruption was partially inhibited by PKA inhibition and significantly reduced by PLC or IP3 receptor antagonists, suggesting sAC activation via increased intracellular calcium.

Conclusions:

• Prostaglandin activation of soluble adenylyl cyclase (sAC) plays a significant role in H2O2-induced epithelial barrier disruption.
• Protein kinase A (PKA) is involved in the downstream signaling of sAC activation.
• Intracellular calcium signaling contributes to the activation of sAC in response to H2O2.