Inhibition of mitochondrial autophagy protects donor lungs for lung transplantation against ischaemia‐reperfusion injury in rats via the mTOR pathway

Abstract

Impaired mitochondrial function is a key factor attributing to lung ischaemia‐reperfusion (IR) injury, which contributes to major post‐transplant complications. Thus, the current study was performed to investigate the role of mitochondrial autophagy in lung I/R injury and the involvement of the mTOR pathway. We established rat models of orthotopic left lung transplantation to investigate the role of mitochondrial autophagy in I/R injury following lung transplantation. Next, we treated the donor lungs with 3‐MA and Rapamycin to evaluate mitochondrial autophagy, lung function and cell apoptosis with different time intervals of cold ischaemia preservation and reperfusion. In addition, mitochondrial autophagy, and cell proliferation and apoptosis of pulmonary microvascular endothelial cells (PMVECs) exposed to hypoxia‐reoxygenation (H/R) were monitored after 3‐MA administration or Rapamycin treatment. The cell apoptosis could be inhibited by mitochondrial autophagy at the beginning of lung ischaemia, but was rendered out of control when mitochondrial autophagy reached normal levels. After I/R of donor lung, the mitochondrial autophagy was increased until 6 hours after reperfusion and then gradually decreased. The elevation of mitochondrial autophagy was accompanied by promoted apoptosis, aggravated lung injury and deteriorated lung function. Moreover, the suppression of mitochondrial autophagy by 3‐MA inhibited cell apoptosis of donor lung to alleviate I/R‐induced lung injury as well as inhibited H/R‐induced PMVEC apoptosis, and enhanced its proliferation. Finally, mTOR pathway participated in I/R‐ and H/R‐mediated mitochondrial autophagy in regulation of cell apoptosis. Inhibition of I/R‐induced mitochondrial autophagy alleviated lung injury via the mTOR pathway, suggesting a potential therapeutic strategy for lung I/R injury.

Interferon regulatory factor 8 induces alveolar macrophage hypoxia/reoxygenation injury via the PINK1/Parkin mitophagy pathway

“…Consistently, the effects of PINK1-mediated mitophagy on LIRI also varied. The upregulation of PINK1 and the scathing role of mitophagy in LIRI were corroborated in previous research [9]. However, some research also illustrated that improved in ammatory response and apoptosis in cardiomyocyte HR injury was achieved through activation of the PINK1/Parkin mediated mitophagy [13].…”

“…Lung ischemia-reperfusion injury affects the expressions of autophagy-related proteins and promotes autophagy [9,12]. Thus, we examined whether IRF8 directly regulates autophagy and facilitates its damaging effects on HR injury.…”

“…PINK1/Parkin-mediated mitochondrial autophagy is a classical mitochondrial autophagy pathway and has also been proven to be involved in ischemia-reperfusion injury and HR injury [9,[13][14][15]. Therefore, to evidence the involvement of PINK1-mediated mitophagy, immuno uorescence PINK1/MitoTracker double labeling was employed to assess mitophagy in macrophages.…”

“…It is known that mitochondrial autophagy (mitophagy) is often caused by exposure to hypoxia and participates in multiple aspects of tissue homeostasis, exerting an essentially physiological effects on eukaryotic cells [8]. More recently, mitophagy has been proved to participate in the process of LIRI by regulating the mTOR pathway [9]. However, regulation of hypoxia/reoxygenation (HR) injury by phosphatase and tensin homologue (PTEN)-induced putative kinase 1 (PINK1), one of the most studied pathway molecule in mitophagy with Parkin functioning downstream of it, has not been substantiated yet.…”

Necrostatin-1 Synergizes the Pan Caspase Inhibitor to Attenuate Lung Injury Induced by Ischemia Reperfusion in Rats

“…Excessive production of reactive oxygen species (ROS) following IR could damage the mitochondrial membrane and stimulate the release of cytochrome c, leading to the initiation of the intrinsic apoptosis pathway [ 3 , 4 ]. Inhibition of apoptosis could reduce lung injury following IR [ 5 , 6 ]. Furthermore, necrosis is suggested to be involved in IR-induced lung injury as well [ 7 ], but it is not considered as an effective therapeutic target previously, since necrosis is traditionally defined as a nonregulated and accidental type of cell death.…”