Lung ischemia-reperfusion injury (LIRI) is associated with many diseases, including primary graft dysfunction after lung transplantation, and has no specific and effective therapies. Necroptosis contributes to the pathogenesis of ischemia-reperfusion injury. Necrostatin-1 (Nec-1), the necroptosis inhibitor targeting RIPK1, has been reported to alleviate ischemia-reperfusion injury in various organs. However, the underlying mechanism of Nec-1 in LIRI remains unclear. In this paper, an in vivo LIRI model was built up by left lung hilar clamping in mice, and an in vitro cold ischemia-reperfusion (CI/R) model using BEAS-2B cells was applied to mimic the lung transplantation setting. We found Nec-1 significantly alleviated ischemia-reperfusion-induced lung injury, cytokine releasing, and necroptosis of epithelial cells in mouse lungs. In vitro, Nec-1 also mitigated CI/R-induced cell death and inflammatory responses in BEAS-2B cells, and these protective effects were achieved by simultaneously inhibiting the formation of necrosome and RIPK1-dependent apoptosis. However, Nec-1 decreased the necrosome number but increased the apoptosis level in lung tissues after ischemia reperfusion. We further clarified that Nec-1 could also attenuate lung injury by promoting neutrophil apoptosis from flow cytometry. In conclusion, Nec-1 alleviated lung ischemia-reperfusion injury by inhibiting necroptosis and apoptosis of epithelial cells and promoting the apoptosis of neutrophils. Thus, Nec-1 could be a promising medication against primary graft dysfunction after lung transplantation.

A random‐pattern skin flap plays an important role in the field of wound repair; the mechanisms that influence the survival of random‐pattern skin flaps have been extensively studied but little attention has been paid to endogenous counterinjury substances and mechanism. Previous reports reveal that the apelin‐APJ axis is an endogenous counterinjury mechanism that has considerable function in protecting against infection, inflammation, oxidative stress, necrosis, and apoptosis in various organs. As an in vivo study, our study proved that the apelin/APJ axis protected the skin flap by alleviating vascular oxidative stress and the apelin/APJ axis works as an antioxidant stress factor dependent on CaMKK/AMPK/GSK3β signaling. In addition, the apelin/APJ‐manipulated CaMKK/AMPK/GSK3β‐dependent mechanism improves HUVECs’ resistance to oxygen and glucose deprivation/reperfusion (OGD/R), reduces ROS production and accumulation, maintained the normal mitochondrial membrane potential, and suppresses oxidative stress in vitro. Besides, activation of the apelin/APJ axis promotes vascular migration and angiogenesis under relative hypoxia condition through CaMKK/AMPK/GSK3β signaling. In a word, we provide new evidence that the apelin/APJ axis is an effective antioxidant and can significantly improve the vitality of random flaps, so it has potential be a promising clinical treatment.

Ischemia-reperfusion injury (IRI) greatly impairs lung transplantation (LTx) outcomes, with no effective treatments. Although existing studies have confirmed that cell death and inflammation responses are critical in LTx-IRI, the specific cell death profiles of various parenchymal and inflammatory cells remain to be elucidated. Using human single-cell RNA sequencing data from LTx-IRI, we identified activation of genes related to cell death and inflammation pathways. We examined the effects and mechanisms of a RIPK3 inhibitor, GSK'872, on IRI with a rat LTx model. GSK'872, added to lung preservation solution, injected to recipients, or in combination, reduced alveolar hemorrhage, perivascular edema, neutrophil infiltration and suppressed necroptosis, pyroptosis, and inflammation in lung tissues. GSK'872 decreased MLKL phosphorylation in type 2 alveolar epithelial cells and macrophages, and RIPK3 phosphorylation in neutrophils. GSK'872 induced apoptosis in RAW264.7 macrophages via RIPK1 and caspase 3 cleavage in a cold ischemia/warm reperfusion (CI/R) cell culture model. GSK'872 inhibited lipopolysaccharide (LPS)-stimulated neutrophil extracellular traps (NETs) formation with suppressed necroptosis and pyroptosis. GSK'872 did not rescue BEAS-2B lung epithelial cells from CI/R-induced cell death. However, conditioned medium from GSK'872-treated macrophages (after CI/R) or neutrophils (challenged by LPS) reduced CI/R-induced decrease in BEAS-2B cell viability. GSK'872 alleviates LTx-IRI by inhibiting necroptosis and pyroptosis in macrophages and neutrophils directly, and protects lung epithelial cells via blocking soluble mediators indirectly. Administration of GSK'872 to lung preservation solution and/or injection to recipients may be new treatment options for IRI in LTx.