In vivo and in vitro effects of salbutamol on alveolar epithelial repair in acute lung injury

Background: Acute lung injury is an important cause of respiratory failure in the critically ill patient. It is caused by damage to the alveolar barrier with subsequent alveolar flooding leading to the development of refractory hypoxaemia. beta Agonists stimulate alveolar fluid clearance in animal models of lung injury. In a clinical trial (BALTI-1), intravenous beta agonists reduced extravascular lung water, an effect that took 72 h in contrast with what animal studies suggest. One possible explanation for the delay in change in extravascular lung water is the time required for salbutamol to stimulate alveolar epithelial repair. Objective: To investigate whether salbutamol can stimulate alveolar epithelial repair in vivo and in vitro. Results: Intravenous salbutamol reduced measures of alveolar-capillary permeability in patients with acute respiratory distress syndrome (ARDS). In vitro, salbutamol stimulated both wound repair, and spreading and proliferation of A549 cells and distal lung epithelial cells. Lung lavage fluid from patients treated with salbutamol enhanced wound repair responses compared with placebo treated patients in vitro by an interleukin 1 beta dependent mechanism. Conclusions: Our in vivo and in vitro work suggests that salbutamol may stimulate epithelial repair-potentially a pharmacological first in ARDS. Clearly establishing the mechanisms and pathways responsible for this is important for the future, and may allow identification of novel therapeutic targets to promote alveolar epithelial repair in humans with ARDS