Unfolded protein response modulates the effects of GHRH antagonists in experimental models of in vivo and in vitro lung injury.

The development of efficient targeted therapies to ameliorate endothelial disorders is of the utmost need, as evident by the devastating outcomes of the recent pandemic. Recent findings suggest that unfolded protein response (UPR) modulates barrier function. In the current study, we reveal that the aforementioned highly conservative mechanism is involved in the protective effects of growth hormone-releasing hormone antagonists (GHRHAnt) in lung injury, both in vivo and in vitro. In bovine pulmonary artery endothelial cells, UPR suppression counteracted the protective effects of GHRHAnt in lipopolysaccharide (LPS)-induced endothelial hyperpermeability. In mouse lungs, UPR activation enhanced the beneficial effects of GHRHAnt against LPS-induced acute lung injury. Our observations - which are focused on lung endothelial cells and tissues - enhance our knowledge on the mechanisms mediating the barrier function and contribute to the development of novel therapies toward sepsis, direct and indirect lung injury. The effects of UPR modulation on the effects of GHRHAnt in other tissues are unknown, and they are the subject of future investigations.