Downregulation Of R-spondin1 Contributes To Mechanical Stretch-induced Pulmonary Endothelial Cell Injury

Objectives: Ventilator induced lung injury(VILI)is a severe side effect happening during mechanical ventilation,mainly caused by the injurious effect of overloaded transmembrane pressure to pulmonary vascular endothelial cells.Recent studies reported that R-spondin(RSPO)proteins were able to tighten endothelium and prevent vascular leakage.Therefore,this study aims to investigate whether RSPOs can protect against VILI via dampening pulmonary endothelial impairment.Research contents: Patient plasma RSPOs concentration was analysed to confirm whether mechanical ventilation could regulate RSPO proteins.Also,VILI murine models and in vitro cyclic stretch induced mouse lung vascular endothelial cells(MLVECs)were established to study what role RSPOs play in mechanical stretch induced pulmonary endothelial cell damage.Further relative experiments were performed to underlie the potential molecular mechanism through which RSPOs attenuate mechanical stretch induced pulmonary endothelial cell injury.Measurements and Main Results: Patients undergoing surgery were supported with mechanical ventilation for a minimum of 3 hours.Murine VILI models were established via subjecting Institute of Cancer Research(ICR)to mechanical ventilation.RSPO1 of both blood and lung samples collected before and after mechanical ventilation was reduced after mechanical ventilation in clinic patients and/or murine VILI models.Furthermore,exogenous supplement of RSPO1 attenuated,whereas RSPO1 siRNA exacerbated VILI and mechanical stretch-induced lung vascular endothelial cell apoptosis.In vitro cyclic stretched MLVECs showed the anti-apoptotic effect of RSPO1 worked through enhancing the interaction between the leucine-rich repeat containing G-protein coupled receptor 5(LGR5) and apoptosis stimulating protein of p53 2(ASPP2),which inhibited the binding of ASPP2 to p53 and thus reduced p53 mediated pro-apoptotic pathway during mechanical stretch induced MLVEC apoptosis.Conclusions: In our study,we found RSPO1 was involved in the process of VILI which was capable of attenuating lung vascular endothelial cell apoptosis caused by mechanical stretch.And this protective function against VILI of RSPO1 worked through enhancing the binding ability of Wnt signal receptor LGR5 to ASPP2,thus inactivating p53-mediated pro-apoptotic pathway in cyclic-stretched MLVECs.Therefore,RSPO1 may have clinical benefit in alleviating mechanical VILI.