Aquaporins in Allergic Response: A New Player.

Aquaporins (AQPs) are transmembrane proteins that facilitate the transport of water and small solutes across cell membranes. Their expression in organs such as the skin, lungs, gastrointestinal tract, and immune system has been implicated in the pathophysiology of various allergic diseases. Emerging evidence suggests that AQPs, particularly AQP1, AQP3, AQP4, AQP5, AQP7, and AQP9, are differentially regulated during allergic responses, contributing to symptoms such as mucosal hypersecretion, edema, and skin dryness. In atopic dermatitis, AQP3 overexpression correlates with increased transepidermal water loss, while in food allergy models, downregulation of AQP4 and AQP8 is associated with allergic diarrhea. In asthma, altered expression of AQP1, AQP3, and AQP5 has been linked to airway inflammation, eosinophil migration, and mucus production. The cAMP/CREB and NFκB signaling pathways have been identified as key regulators of AQP5 expression, providing potential therapeutic targets. Several experimental studies using herbal extracts have demonstrated anti-inflammatory effects mediated through upregulation of AQP1 and AQP5 and suppression of proinflammatory cytokines. A proposed integrative model suggests that AQPs participate in both the sensitization and effector phases of the allergic response, influencing antigen presentation, immune cell migration, and mediator release. Despite promising preclinical findings, human studies remain limited. Further clinical research is warranted to validate AQPs as biomarkers and therapeutic targets in allergic diseases, especially considering the increasing global prevalence of these conditions.