MPO and acute respiratory distress syndrome: Preconditioning with pyrogallol was also able to enhance UC-MSC therapeutic properties via activation of the Nrf2/HO-1 signaling pathway, leading to a reduction of lung injury, epithelial cell apoptosis, MPO activity, and levels of inflammation-associated mediators (IL-6, IL-8, MCP-1, and TNF-α) in experimental LPS-induced ARDS (Zhang et al., 2022).