Downregulation of R-Spondin1 Contributes to Mechanical Stretch-Induced Lung Injury

Abstract

Objectives: The R-spondin family attenuates tissue damage via tightening endothelium and preventing vascular leakage. This study aims to investigate whether R-spondins protect against mechanical stretch-induced endothelial dysfunction and lung injury and to reveal the underlying mechanisms. Design: Randomized controlled study. Setting: University research laboratory. Subjects: Patients scheduled to undergo surgery with mechanical ventilation support. Adult male Institute of Cancer Research mice. Primary cultured mouse lung vascular endothelial cells. Interventions: Patients underwent a surgical procedure with mechanical ventilation support of 3 hours or more. Mice were subjected to mechanical ventilation (6 or 30 mL/kg) for 0.5–4 hours. Another group of mice were intraperitoneally injected with 1 mg/kg lipopolysaccharide, and 12 hours later subjected to mechanical ventilation (10 mL/kg) for 4 hours. Mouse lung vascular endothelial cells were subjected to cyclic stretch for 4 hours. Measurements and Main Results: R-spondin1 were downregulated in both surgical patients and experimental animals exposed to mechanical ventilation. Intratracheal instillation of R-spondin1 attenuated, whereas knockdown of pulmonary R-spondin1 exacerbated ventilator-induced lung injury and mechanical stretch-induced lung vascular endothelial cell apoptosis. The antiapoptotic effect of R-spondin1 was mediated through the leucine-rich repeat containing G-protein coupled receptor 5 in cyclic stretched mouse lung vascular endothelial cells. We identified apoptosis-stimulating protein of p53 2 as the intracellular signaling protein interacted with leucine-rich repeat containing G-protein coupled receptor 5. R-spondin1 treatment decreased the interaction of apoptosis-stimulating protein of p53 2 with p53 while increased the binding of apoptosis-stimulating protein of p53 2 to leucine-rich repeat containing G-protein coupled receptor 5, therefore resulting in inactivation of p53-mediated proapoptotic pathway in cyclic stretched mouse lung vascular endothelial cells. Conclusions: Mechanical ventilation leads to down-regulation of R-spondin1. R-spondin1 may enhance the interaction of leucine-rich repeat containing G-protein coupled receptor 5 and apoptosis-stimulating protein of p53 2, thus inactivating p53-mediated proapoptotic pathway in cyclic stretched mouse lung vascular endothelial cells. R-spondin1 may have clinical benefit in alleviating mechanical ventilator-induced lung injury.

Upregulation of sphingosine kinase�1 contributes to�ventilator-associated lung injury in a two-hit model

“…When establishing the two-hit model, the present study intraperitoneally administrated 1 mg/kg LPS, according to the study of O'Mahony et al (2); and no notable lung injury was observed at this dose. Similarly, the present study reported that ventilation or LPS alone could result in mild changes, not meeting the criteria for ALI or ARDS (5,29). By contrast, in the present study, the combined treatment of LPS and ventilation resulted in molecular and histological alterations associated with lung injury.…”

“…As lung endothelial cell hyperpermeability is caused by endothelial overdistension during ventilation (1,29), the effects of cyclic stretch and LPS were examined, and the effect of SPHK1 inhibition on the activation of the RhoA/ROCK pathway was investigated in primary cultured MLVECs. In the present study, MLVECs were subjected to LPS treatment for 12 h and then exposed to cyclic stretch (8% elongation) for 4 h. Consistent with the findings in vivo , LPS or stretch alone led to minor changes in the activation of RhoA and ROCK1, and the phosphorylation of MYPT1.…”

Exercise training ameliorates early diabetic kidney injury by regulating the H2S/SIRT1/p53 pathway

“…Caspase‐3 activity in the kidney tissues and MPC5 podocytes was measured by using the caspase‐3 activity assay kit (Beyotime, Jiangsu, China) as previously described 26 . Renal tissues and podocytes were homogenized in lysis buffer and centrifuged at 20 000 rpm for 15 minutes at 4℃ Then supernatant was used for measurement of caspase‐3 activity.…”

“…Caspase-3 activity in the kidney tissues and MPC5 podocytes was measured by using the caspase-3 activity assay kit (Beyotime, Jiangsu, China) as previously described. 26 Renal tissues and podocytes were homogenized in lysis buffer and centrifuged at 20 000 rpm for 15 minutes at 4℃ Then supernatant was used for measurement of caspase-3 activity. 50 μL of supernatants were added to 50 μL of assay buffer and 10 μL of the 2mM Ac-DEVD-pNA chromogenic substrate into 96-well plates with 50 μL of lysis buffer served as control.…”

Upregulation of FOXO1 contributes to lipopolysaccharide-induced pulmonary endothelial injury by induction of autophagy

“…MLVECs were isolated from A total of 48 male Institute of Cancer Research (ICR) mice (3-4 weeks,) as previously described (18,19). Briefly, after anesthesia, the right ventricle of mice was injected with PBS to clear blood from lungs.…”