Transient receptor vanilloid 4 (TRPV4) channels are essential for alveolar epithelial cell function

Ischemia-reperfusion(IR)-induced edema formation can be mimicked ex-vivo in isolated perfused mouse lungs (IPL). Here we show enhanced edema formation in transient receptor potential vanilloid 4 (TRPV4)-deficient (TRPV4-/-) IPL compared to wild-type (WT) controls in response to IR, indicating a protective role of TRPV4 to maintain the alveolar epithelial barrier. By immunohistochemistry, mRNA profiling or electrophysiological analysis we detected TRPV4 in bronchial epithelium, alveolar type I (ATI) and alveolar type II (ATII) cells. Genetic ablation of TRPV4 resulted in reduced expression of aquaporin-5 (AQP-5) channels in ATI as well as decreased production of pro surfactant protein C (pSP-C) in ATII cells. Migration of TRPV4-deficient ATI cells was reduced and cell barrier function was impaired. Moreover, adult TRPV4−/− lungs developed emphysema-like changes and altered lung parameters compared to WT lungs. Therefore, our data highlight novel essential functions of TRPV4 channels in alveolar epithelial cells and in the protection from edema formation.