Pulmonary Ischemia-reperfusion Injury Research Articles

(225) - Novel Anti-CD94 Treatment Reduces Mouse and Human Experimental Pulmonary Ischemia-Reperfusion Injury

(225) - Novel Anti-CD94 Treatment Reduces Mouse and Human Experimental Pulmonary Ischemia-Reperfusion Injury

Nanoparticle targeting of neutrophil glycolysis prevents lung ischemia-reperfusion injury

Neutrophils exacerbate pulmonary ischemia-reperfusion injury (IRI) resulting in poor short and long-term outcomes for lung transplant recipients. Glycolysis powers neutrophil activation, but it remains unclear if neutrophil-specific targeting of this pathway will inhibit IRI. Lipid nanoparticles containing the glycolysis flux inhibitor 2-deoxyglucose (2-DG) were conjugated to neutrophil-specific Ly6G antibodies (NP-Ly6G[2-DG]). Intravenously administered NP-Ly6G(2-DG) to mice exhibited high specificity for circulating neutrophils. NP-Ly6G(2-DG)–treated neutrophils were unable to adapt to hypoglycemic conditions of the lung airspace environment as evident by the loss of demand-induced glycolysis, reductions in glycogen and ATP content, and an increased vulnerability to apoptosis. NP-Ly6G(2-DG) treatment inhibited pulmonary IRI following hilar occlusion and orthotopic lung transplantation. IRI protection was associated with less airspace neutrophil extracellular trap generation, reduced intragraft neutrophilia, and enhanced alveolar macrophage efferocytotic clearance of neutrophils. Collectively, our data show that pharmacologically targeting glycolysis in neutrophils inhibits their activation and survival leading to reduced pulmonary IRI.

CCR5 drives NK cell-associated airway damage in pulmonary ischemia-reperfusion injury.

Primary graft dysfunction (PGD) limits clinical benefit after lung transplantation, a life-prolonging therapy for patients with end-stage disease. PGD is the clinical syndrome resulting from pulmonary ischemia-reperfusion injury (IRI), driven by innate immune inflammation. We recently demonstrated a key role for NK cells in the airways of mouse models and human tissue samples of IRI. Here, we used 2 mouse models paired with human lung transplant samples to investigate the mechanisms whereby NK cells migrate to the airways to mediate lung injury. We demonstrate that chemokine receptor ligand transcripts and proteins are increased in mouse and human disease. CCR5 ligand transcripts were correlated with NK cell gene signatures independently of NK cell CCR5 ligand secretion. NK cells expressing CCR5 were increased in the lung and airways during IRI and had increased markers of tissue residency and maturation. Allosteric CCR5 drug blockade reduced the migration of NK cells to the site of injury. CCR5 blockade also blunted quantitative measures of experimental IRI. Additionally, in human lung transplant bronchoalveolar lavage samples, we found that CCR5 ligand was associated with increased patient morbidity and that the CCR5 receptor was increased in expression on human NK cells following PGD. These data support a potential mechanism for NK cell migration during lung injury and identify a plausible preventative treatment for PGD.

Abstract 181: Adiponectin Alleviates Acute Murine Pulmonary Injury Post Cardiopulmonary Resuscitation

Objective: Patients with cardiac arrest (CA) are often suffering from pulmonary ischemia-reperfusion injury after active cardiopulmonary resuscitation (CPR) and return of spontaneous circulation (ROSC). In recent years, previous studies have found that acute lung injury (ALI) after ROSC could be an independent risk factor for the prognosis of out of hospital cardiac arrest (OHCA). However, there is still a lack of effective therapy for pulmonary injury caused by CA-CPR-ROSC with no side effects. Methods: C57BL/6 male mice, aged from 8 to 10 weeks were purchased from Dossy Experimental Animals Co. Ltd (Chengdu, China). All the mice were feeding and drinking freely in the animal room of Sichuan University West China Science and Technology Park for one week. The experiments involving mice were approved by the Ethics Committee from West China Hospital of Sichuan University (approval No.2017071A). At the day before experiment, mice were given fasting treatment but allowed to drink water freely. CA-CPR-ROSC could cause global cerebral ischemia injury in vivo. APN (10μg/0.05ml per mice) was intravenously injected to mice at 10 min after restoration of spontaneous circulation (ROSC). Computed tomography (CT) scan of the lungs was performed before executing the animals. We used the Opal Color Manual IHC staining Kit for multiplex immunofluorescence staining measurement. Western blot detected the expression of Nrf2, OCLN, and CLDN5 in murine pulmonary tissues. Results: The results of CT scanning and routine histological measurements showed that APN could protect mice against murine pulmonary injury caused by CA-CPR-ROSC, compared to that of mice in CA-CPR-ROSC group. The results of western blot suggested that the expression of Nrf2 significantly increased in mice pulmonary tissues in CA-CPR-ROSC, whereas the expression of OCLN and CLDN5 obviously decreased in murine pulmonary tissues in CA-CPR-ROSC. Conclusion: Current study indicated the protect role of Adiponectin against acute murine pulmonary injury caused by CA-CPR-ROSC. The protective role of Adiponectin against acute murine pulmonary injury caused by CA-CPR-ROSC might be associated to the Nrf2 signaling pathway.

Post-ischemic treatment of nalmefene hydrochloride attenuated lung ischemia-reperfusion injury in rats via the Sirt1/Nrf2/HO-1 pathway with inhibition of ferroptosis

Objective: To study the effect and mechanism of post-ischemic treatment of nalmefene in alleviating the lung ischemia-reperfusion injury by inhibiting ferroptosis through activation of the Sirt 1/Nrf 2/HO-1 axis. Methods: A total of 60 rats were randomly divided into six groups equally (n=10): the sham group, the model group(I/R), the nalmefene group, the nalmefene+EX527 group, the nalmefene+ML385 group, the nalmefene+Fe-citrate group (nalmefene+Fe group). The sham group without drug treatment was not treated with ischemia-reperfusion. The pulmonary ischemia-reperfusion model was established by occlusion of the left pulmonary hilum in the model group without drug treatment. After ischemic treatment, the nalmefene group was injected with nalmefene (15 μg/kg) via the tail vein at 5 minutes before reperfusion. The nalmefene+EX527 group, the nalmefene+ML385 group, and the nalmefene+Fe group were injected intraperitoneally with EX527 (5 mg/kg), ML385 (30 mg/kg), Fe-citrate(15 mg/kg), respectively, 2 h before moulding and then injected with nalmefene (15 μg/kg) via the tail vein at 5 minutes before reperfusion. All rats were sacrificed three hours after reperfusion, and the specimens from the upper lobe of the left lung tissue were preserved. The degree of lung tissue injury and the wet/dry weight ratio were assessed in each group of rats. Fe 2+, MDA, TNF-α, and IL-6 content, GSH activity and the expression levels of Sirt1, Nrf2, HO-1, ACSL4 and GPX4 were determined. Results: Compared with the sham group, the wet/dry weight ratio, lung tissue injury score, ACSL 4 expression level, Fe 2+, TNF-α, IL-6 and MDA content, Sirt 1, Nrf 2, HO-1 messenger RNA and protein expression levels were significantly increased (P<0.01), while GPX 4 expression level and GSH activity were significantly decreased in the model group (P<0.01). Compared with the model group, wet/dry weight ratio, lung tissue injury score, ACSL 4 expression level, Fe 2+, TNF-α, IL-6, and MDA content decreased significantly (P<0.01), Nrf 2, HO-1 messenger RNA and protein, GPX 4 expression, and GSH activity were significantly increased in the nalmefene group and the nalmefene+EX527 group (P<0.01). Sirt 1 messenger RNA and protein expression increased significantly in the nalmefene (P<0.01) and the nalmefene+EX527 groups (P>0.05). In the nalmefene+ML385 group, the wet/dry weight ratio, lung tissue injury score, TNF-α and IL-6 content were decreased significantly (P<0.01), while Sirt 1 messenger RNA and protein expression levels were significantly increased (P<0.01), but there were no significant changes in Nrf 2, HO-1 messenger RNA and protein expression levels, ACSL 4 and GPX 4 expression levels, Fe 2+, MDA content, and GSH activity (P>0.05). In the nalmefene+Fe group, wet/dry weight ratio, lung-injury score, TNF-α, IL-6, MDA content were decreased significantly (P<0.01), messenger RNA and protein expression levels of Sirt 1, Nrf 2, HO-1, and GSH activity were increased significantly (P<0.01), but there were no significant changes in Fe 2+content, ACSL 4 and GPX 4 expression levels (P>0.05). Compared with the nalmefene group, in the nalmefene+EX527 group, the nalmefene+ML385 group and the nalmefene+Fe group, wet/dry weight ratio, lung tissue damage score, ACSL 4 expression level, TNF-α, IL-6 and MDA content were significantly increased (P<0.01), the expression level of GPX 4 and GSH activity were significantly decreased (P<0.01). The expression levels of Sirt 1, Nrf 2, HO-1 messenger RNA and protein were significantly decreased in the nalmefene+EX527 group (P<0.01). The expression levels of Nrf 2, HO-1 messenger RNA and protein decreased significantly in the namemefene+ML385 group (P<0.01), but there was no significant change in Sirt 1 messenger RNA and protein expression level (P>0.05). Sirt 1, Nrf 2, HO-1 messenger RNA-protein expression levels did not change significantly in the nalmefene+Fe group (P>0.05). Conclusion: Post-ischemic treatment with nalmefene hydrochloride may alleviate pulmonary ischemia-reperfusion injury by inhibiting ferroptosis through activation of the Sirt 1/Nrf 2/HO-1 axis.

118.7: The role of tertiary lymphoid structures in aged swine on the progression of pulmonary ischemia-reperfusion injury

118.7: The role of tertiary lymphoid structures in aged swine on the progression of pulmonary ischemia-reperfusion injury

The hemodynamic interplay between pulmonary ischemia-reperfusion injury and right ventricular function in lung transplantation: A translational porcine model.

Lung transplantation is a challenging procedure. Following the process of ischemia-reperfusion injury, the transplanted pulmonary graft might become severely damaged, resulting in primary graft dysfunction. Additionally, during the intra-operative window, the right ventricle is at risk of acute failure. The interaction of right ventricular function with lung injury, is however, poorly understood. We aimed to address this interaction in a translational porcine model of pulmonary ischemia-reperfusion injury. Advanced pulmonary and hemodynamic assessment was used, including right ventricular pressure-volume loop analysis. The acute model was based on clamping and unclamping of the left lung hilus, respecting the different hemodynamic phases of a clinical lung transplantation. We found that forcing entire right ventricular cardiac output through a lung suffering from ischemia-reperfusion injury increased afterload (pulmonary vascular resistance from baseline to end experiment p <0.0001) and induced right ventricular failure in 5/9 animals. Notably, we identified different compensation patterns in failing versus non-failing ventricles (arterial elastance p=0.0008; stroke volume p <0.0001). Furthermore, increased vascular pressure and flow produced by the right ventricle resulted in higher pulmonary injury, as measured by ex-vivo CT density (correlation: pressure r=0.8; flow r= 0.85). Finally, RV ischemia as measured by troponin-T was negatively correlated with pulmonary injury (r=-0.76), however, troponin-T values did not determine RVF in all animals. In conclusion, we demonstrate a delicate balance between development of pulmonary ischemia-reperfusion injury and right ventricular function during lung transplantation. Furthermore, we provide a physiological basis for potential benefit of extracorporeal life support technology.

(1272) Effect of Aging on the Progression of Pulmonary Ischemia-Reperfusion Injury in Clawn Miniature Swine

(1272) Effect of Aging on the Progression of Pulmonary Ischemia-Reperfusion Injury in Clawn Miniature Swine

(207) Pumpless Intra-Operative Circulatory Support During Lung Transplantation: Pulmonary Artery to Left Atrium Oxygenator in a Porcine Model of Pulmonary Ischemia-Reperfusion Injury

(207) Pumpless Intra-Operative Circulatory Support During Lung Transplantation: Pulmonary Artery to Left Atrium Oxygenator in a Porcine Model of Pulmonary Ischemia-Reperfusion Injury

422.6: Effects of Argon Inhalation on Reducing Pulmonary Warm Ischemia-Reperfusion Injury in CLAWN Miniature Swine

Background: Ischemia-reperfusion injury (IRI) remains a major cause of early death in lung transplantation. In addition, warm ischemia of the donor organ is inevitable when transplanting from DCD donor, and it is important to develop new strategies for reducing warm IRI. The cytoprotective effects of chemically inert noble gases such as argon (Ar) have been demonstrated. Ar is particularly safe and cost-effective because it is non-anesthetic and the third most abundant gas in the atmosphere, suggesting higher safety levels and lower cost advantages. The inhibitory effect of IRI has been reported in small animal models of various organs, but there are conflicting reports on the effect in large animal models. In this study, we evaluated the cytoprotective effect and safety of Ar inhalation using large animal model of pulmonary warm IRI model. Methods: Ten CLAWN miniature swine were evenly divided into two groups (Ar-treated and control group). In both groups, warm ischemia was induced for 90 minutes by clamping the left bronchus, pulmonary artery and veins. Animals were inhaled with either 70% Ar (Ar-treated) or 70% nitrogen (control) in 30% oxygen for 360 minutes throughout the procedure. Lung function and structure were serially assessed via the ratio of partial pressure of oxygen to fractional inspired oxygen (pO2/FiO2) measured by both arterial blood and pulmonary vein (PV), chest X-ray (CXR) and lung biopsy, as well as the presence of side effects. Results: Ar inhalation dramatically decreased lung injury associated with ischemia and reperfusion without apparent adverse effects. In the control group, 90 minutes of warm ischemia resulted in a significant decrease in pO2/FiO2 by arterial blood, from 568 +/-12 mmHg before ischemia to 272 +/-39 mmHg 2 hours after reperfusion (p<0.05). In sharp contrast, animals in the Ar-treated group had no significant change in pO2/FiO2 by arterial blood despite 90-min ischemia (563 +/-18 mmHg before ischemia to 431 +/-49 mmHg 2 hours after reperfusion). Moreover, pO2/FiO2 by PV showed well-maintained lung function in the Ar-treated group (331 +/-40 vs. 186 +/-17 mmHg at 2 hours, p<0.05; 519 +/-19 vs. 292 +/-33 mmHg at 2 days after reperfusion, p<0.05). In addition, histological scores of lung biopsies (calculated based on four items: cellular infiltration, intralobular edema, fibrin exudation, and hemorrhage) were significantly better in the Ar-inhalation group for both 2-hour and 2-day biopsies after reperfusion. The evaluation of serum and biopsy samples suggested that anti-oxidant and anti-apoptosis were the main mechanisms of Ar inhalation. Conclusion: In this study, we demonstrated for the first time the inhibitory effect of perioperative Ar inhalation on pulmonary warm IRI in large animals. In order to apply this new therapy to clinical practice, further detailed analysis of the mechanism and evaluation using ischemic models including cold storage are required in the future.

Effect of sevoflurane post-conditioning on apoptosis and the expressions of Bcl-2 and Bax in lung tissue of cardiopulmonary bypass dogs

Purpose: To investigate the effects of sevoflurane post-conditioning on the expressions of Bcl-2 and Bax in lung tissues of cardiopulmonary bypass (CPB) dogs.&#x0D; Methods: Twelve healthy hybrid mongrels were divided into control (C) and sevoflurane postconditioning (S) groups. All dogs were subjected to thoracotomy in order to establish CPB. Ischemiareperfusion was conducted in the left lung of both groups. Thereafter, sevoflurane post-conditioning was given to group S. Femoral artery blood specimens were obtained prior to CPB (T1), as the left pulmonary artery was opened (T2), and 2 h after CPB (T3), for blood gas analysis. Respiration index (RI), oxygenation index (OI), and dynamic lung compliance (Cd) were calculated.&#x0D; Results: When T1 was compared with T2 and T3, their OI and Cd were significantly decreased in both groups, while RI showed the opposite trend (p &lt; 0.05). Values of OI and Cd at T3 in group S were increased significantly, relative to group C, while RI decreased (p &lt; 0.05). There were less lung tissue inflammation and structural disorder at T3 in Group S than in group C. Protein expressions and positive integral of Bcl-2 and Bax, and apoptosis at T2 and T3 in dog lung tissues of both groups were higher than those at T1 (p &lt; 0.05).&#x0D; Conclusion: Post-conditioning with sevoflurane is lung-protective in CPB dogs. The underlying mechanism may be based on the promotion of Bcl-2 expression and inhibition of Bax expression, thereby reducing apoptosis in dog lung tissue. Further investigations to determine its suitability for clinical applications in humans are, however, required.&#x0D; Keywords: Sevoflurane; Cardiopulmonary bypass; Bcl-2, Bax; Apoptosis; Pulmonary ischemiareperfusion injury

Rosmarinic Acid Ameliorates Pulmonary Ischemia/Reperfusion Injury by Activating the PI3K/Akt Signaling Pathway.

Pulmonary ischemia/reperfusion (IR) injury is the leading cause of acute lung injury, which is mainly attributed to reactive oxygen species (ROS) induced cell injuries and apoptosis. Since rosmarinic acid (RA) has been identified as an antioxidant natural ester, this natural compound might protect against pulmonary IR injury. In this study, the mice were given RA daily (50, 75, or 100 mg/kg) by gavage for 7 days before the pulmonary IR injury. We found that hypoxemia, pulmonary edema, and serum inflammation cytokines were aggravated in pulmonary IR injury. RA pretreatment (75 and 100 mg/kg) effectively reversed these parameters, while 50 mg/kg RA pretreatment was less pronounced. Our data also indicated RA pretreatment mitigated the upregulation of pro-oxidant NADPH oxidases (NOX2 and NOX4) and the downregulation of anti-oxidant superoxide dismutases (SOD1 and SOD2) upon IR injury. In vitro studies showed RA preserved the viability of anoxia/reoxygenation (AR)-treated A549 cells (a human lung epithelial cell line), and the results showed the protective effect of RA started at 5 μM concentration, reached its maximum at 15 μM, and gradually decreased at 20–25 μM. Besides, RA pretreatment (15 μM) greatly reduced the lactate dehydrogenase release levels subjected to AR treatment. Moreover, the results of our research revealed that RA eliminated ROS production and reduced alveolar epithelial cell apoptosis through activating the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) signaling pathway, which was supported by using wortmannin, because in the presence of wortmannin, the RA-mediated protection was blocked. Meanwhile, wortmannin also reversed the protective effects of RA in mice. Together, our results demonstrate the beneficial role of RA in pulmonary IR injury via PI3K/Akt-mediated anti-oxidation and anti-apoptosis, which could be a promising therapeutic intervention for pulmonary IR injury.

Argon Inhalation Reduces Pulmonary Ischemia-Reperfusion Injury in MHC-inbred CLAWN Miniature Swine

<h3>Purpose</h3> Ischemia-reperfusion injury (IRI) remains a major cause of early death in lung transplantation. The cytoprotective effects of chemically inert noble gases such as argon (Ar) have been demonstrated, especially Ar, which is non-anesthetic and the third most abundant gas in the atmosphere, suggesting higher safety levels and lower cost advantages. The inhibitory effect of IRI has been reported in small animal models of various organs, but there are conflicting reports on the effect in large animal models. In this study, we evaluated the beneficial effect and safety of Ar inhalation using a large animal lung IRI model to assess the applicability of Ar's cytoprotective effect to transplantation. <h3>Methods</h3> The Ar inhalation group (n=5) inhaled 30% oxygen plus 70% Ar, and the control group (n=5) inhaled 30% oxygen plus 70% nitrogen for a total of 360 minutes. In each group, the degree of lung damage was evaluated up to 28 days postoperatively using arterial and pulmonary venous (PV) gas analysis, chest X-ray (CXR), and lung biopsy as the main indices, as well as the presence of side effects. <h3>Results</h3> Although the arterial blood P/F ratio significantly decreased from pre-ischemia to 2 hours after reperfusion in the control group (from 568 ± 12 to 272 ± 39 mmHg) after 90 minutes of warm ischemia, it was well maintained in the Ar inhalation group (from 563 ± 18 to 431 ± 49 mmHg). In addition, direct assessment of impaired lung using left PV blood showed a significantly better P/F ratio in the Ar inhalation group (331 ± 40 vs. 186 ± 17 mmHg at 2 hours; 519 ± 19 vs. 292 ± 33 mmHg at 2 days). Early postoperative CXR showed that the infiltrations of the left lung in the control group were reduced by Ar inhalation. In addition, histological scores of lung biopsies (calculated based on four items: cellular infiltration, intralobular edema, fibrin exudation, and hemorrhage) were significantly better in the Ar-inhalation group for both 2-hour and 2-day biopsies after reperfusion. The serum evaluation suggested that anti-oxidant and anti-apoptosis were the main mechanisms of action. <h3>Conclusion</h3> In this study, we demonstrated for the first time the inhibitory effect of perioperative Ar inhalation on pulmonary IRI in large animals. In order to apply this new therapy to clinical practice, further detailed analysis of the mechanism and evaluation using ischemic models including cold storage are required in the future.

Differential Response of Right Ventricular Contractility to Lung Ischemia-Reperfusion Injury: Large Animal Model to Study Sequential Single Lung Transplantation

<h3>Purpose</h3> Early outcome after lung transplantation (LTx) is often characterized by the presence of primary graft dysfunction (PGD). The exact role of the right ventricle (RV) in development of PGD and perioperative outcome is unknown. Firstly, increased afterload due to PGD might compromise RV function. Secondly, increased contractility and cardiac output (CO) of RV might contribute to pulmonary edema accumulation after reperfusion. We developed a unique large animal model to study RV behavior in a setting of pulmonary ischemia-reperfusion injury (IRI). <h3>Methods</h3> The left lung (LL) of a domestic pig in clamping group [CLA] was clamped (3h warm ischemia) and reperfused (3h) in situ (n=6). During the final hour of reperfusion, contralateral right lung (RL) was clamped to force RV CO to the injured LL. Control animals [CON] were fully instrumented (n=5) and followed for 6 hours. The RV function was monitored using a conductance catheter measuring pressure-volume (PV) loops. Lung injury was assessed by wet to dry (W/D) ratio and ex-vivo computed tomography (CT). Data was analyzed in time using 2-way ANOVA test or student T-test. <h3>Results</h3> Pulmonary vascular resistance (PVR) rose significantly at hour 6 in [CLA], reflecting an increase of afterload due to IRI and RL camping (<i>fig. A</i>). RV Contractility was stable in [CON]. In [CLA], it increased in 2 animals (<i>fig. D</i>) and 4 animals developed RV failure (<i>fig. B</i>). Lungs were injured as reflected by higher W/D ratio (<i>p=0.0019</i>) and parenchymal density on CT (<i>p=0.0089</i>) of [CLA] LL compared to [CON]. <h3>Conclusion</h3> RV response to increased afterload resulting from IRI occurs in a dichotomized way: with increased contractility or with failure. This occurs when the contralateral lung is clamped and mimics a specific intra-operative situation of sequential single LTx. Our model should be considered as an innovative platform to study the possible benefit of ECLS devices on RV function and PGD development after LTx.

Physiological, Radiological and Morphological Characterization of Large Animal Pulmonary Ischemia-Reperfusion Injury

<h3>Purpose</h3> Large animal models are essential to study ischemia-reperfusion injury (IRI) in lung transplantation (LTx). Despite a long history of animal models, clinically relevant injury markers are not well described. Also, the manifestation of lung IRI with different sets of parameters has not been investigated thoroughly. Therefore, we aimed to develop and describe a porcine pulmonary IRI model at a physiological, radiological and morphological level. <h3>Methods</h3> In a clamping group [CLA] the left lung (LL) of a domestic pig was clamped (3h) and reperfused (3h) in situ (n=9). During the last hour of reperfusion, contralateral right lung (RL) was clamped to force the entire pulmonary flow to the injured LL. This reflects an intra-operative step in sequential single LTx after reperfusion of the first lung. In a control group [CON] the animals were fully instrumented (n=6). Lung injury was assessed by continuous monitoring of lung compliance and intermittent calculation of Pa/FiO₂ ratio. After the experiments, wet to dry (W/D) ratio was calculated and an ex vivo lung computed tomography (CT) scan as well as histological assessment were performed. Data was analyzed in time using 2-way ANOVA test or student T-test. <h3>Results</h3> A reproducible injury pattern in [CLA] compared to [CON] was noticed. Physiological assessment showed decline in lung function (<i>Fig 1; A,B</i>). Severe LL injury in [CLA] was reflected by increase in W/D ratio, CT measured density (<i>Fig 1; C,D,G,H)</i> and translated into morphological assessment (<i>Fig 1; E,F).</i> <h3>Conclusion</h3> We report a unique model of porcine lung IRI with meticulous description of physiological, radiological and morphological parameters. We demonstrated that injury is consistent at all the levels of assessment, reflecting the clinical syndrome and definition of primary graft dysfunction (PGD) after LTx. This model allows to investigate PGD at a true pre-clinical level with the potential to translate treatment strategies rapidly into clinical practice.

Recent Progress of Ferroptosis in Lung Diseases.

Ferroptosis is a new form of programmed cell death due to iron-dependent excess accumulation of lipid peroxides and differs from other programmed cell deaths in morphological and biochemical characteristics. The process of ferroptosis is precisely regulated by iron metabolism, lipid metabolism, amino acid metabolism, and numerous signaling pathways, and plays a complex role in many pathophysiological processes. Recent studies have found that ferroptosis is closely associated with the development and progression of many lung diseases, including acute lung injury, pulmonary ischemia-reperfusion injury, lung cancer, chronic obstructive pulmonary disease, and pulmonary fibrosis. Here, we present a review of the main regulatory mechanisms of ferroptosis and its research progress in the pathogenesis and treatment of lung diseases, with the aim of providing new ideas for basic and clinical research of lung-related diseases.

Ischemia-Reperfusion Injury in Lung Transplantation.

Lung transplantation has been established worldwide as the last treatment for end-stage respiratory failure. However, ischemia–reperfusion injury (IRI) inevitably occurs after lung transplantation. The most severe form of IRI leads to primary graft failure, which is an important cause of morbidity and mortality after lung transplantation. IRI may also induce rejection, which is the main cause of mortality in recipients. Despite advances in donor management and graft preservation, most donor grafts are still unsuitable for transplantation. Although the pulmonary endothelium is the primary target site of IRI, the pathophysiology of lung IRI remains incompletely understood. It is essential to understand the mechanism of pulmonary IRI to improve the outcomes of lung transplantation. Therefore, we reviewed the state-of-the-art in the management of pulmonary IRI after lung transplantation. Recently, the ex vivo lung perfusion (EVLP) system has been clinically introduced worldwide. Various promising therapeutic strategies for the protection of the endothelium against IRI, including EVLP, inhalation therapy with therapeutic gases and substances, fibrinolytic treatment, and mesenchymal stromal cell therapy, are awaiting clinical application. We herein review the latest advances in the field of pulmonary IRI in lung transplantation.

Natural killer cells activated through NKG2D mediate lung ischemia-reperfusion injury.

Pulmonary ischemia-reperfusion injury (IRI) is a clinical syndrome of acute lung injury that occurs after lung transplantation or remote organ ischemia. IRI causes early mortality and has no effective therapies. While NK cells are innate lymphocytes capable of recognizing injured cells, their roles in acute lung injury are incompletely understood. Here, we demonstrated that NK cells were increased in frequency and cytotoxicity in 2 different IRI mouse models. We showed that NK cells trafficked to the lung tissue from peripheral reservoirs and were more mature within lung tissue. Acute lung ischemia-reperfusion injury was blunted in a NK cell-deficient mouse strain but restored with adoptive transfer of NK cells. Mechanistically, NK cell NKG2D receptor ligands were induced on lung endothelial and epithelial cells following IRI, and antibody-mediated NK cell depletion or NKG2D stress receptor blockade abrogated acute lung injury. In human lung tissue, NK cells were increased at sites of ischemia-reperfusion injury and activated NK cells were increased in prospectively collected human bronchoalveolar lavage in subjects with severe IRI. These data support a causal role for recipient peripheral NK cells in pulmonary IRI via NK cell NKG2D receptor ligation. Therapies targeting NK cells may hold promise in acute lung injury.

Protective effect of necrosulfonamide on rat pulmonary ischemia-reperfusion injury via inhibition of necroptosis

BackgroundNecroptosis plays an important role in cell death during pulmonary ischemia-reperfusion injury (IRI). We hypothesized that therapy with necrosulfonamide (NSA), a mixed-lineage kinase domain-like protein inhibitor, would attenuate lung IRI. MethodsRats were assigned at random into the sham operation group (n = 6), vehicle group (n = 8), or NSA group (n = 8). In the NSA and vehicle groups, the animals were heparinized and underwent left thoracotomy, and the left hilum was clamped for 90 minutes, followed by reperfusion for 120 minutes. NSA (0.5 mg/body) and a solvent were administered i.p. in the NSA group and the vehicle group, respectively. The sham group underwent 210 minutes of perfusion without ischemia. After reperfusion, arterial blood gas analysis, physiologic data, lung wet-to-dry weight ratio, histologic changes, and cytokine levels were assessed. Fluorescence double immunostaining was performed to evaluate necroptosis and apoptosis. ResultsArterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) was better, dynamic compliance was higher, and mean airway pressure and lung edema were lower in the NSA group compared with the vehicle group. Moreover, in the NSA group, lung injury was significantly alleviated, and the mean number of necroptotic cells (55.3 ± 4.06 vs 78.2 ± 6.87; P = .024), but not of apoptotic cells (P = .084), was significantly reduced compared with the vehicle group. Interleukin (IL)-1β and IL-6 levels were significantly lower with NSA administration. ConclusionsIn a rat model, our results suggest that NSA may have a potential protective role in lung IRI through the inhibition of necroptosis.

Dexmedetomidine alleviates pulmonary ischemia-reperfusion injury through modulating the miR-21-5p/Nr4a1 signaling pathway.

This study aims to investigate the protection of dexmedetomidine (Dex) against pulmonary ischemia-reperfusion injury (PIRI) in the mouse model and reveal the mechanism in hypoxia reoxygenation (H/R)-induced mouse pulmonary vascular endothelial cells (MPVECs). The lung wet-to-dry weight ratio, histopathological features, and malondialdehyde (MDA) concentrations were measured. The H/R-induced MPVECs were exposed to Dex, and the cell viability, cell apoptosis and protein expressions were assessed by the Cell Counting Kit-8 (CCK8) assay, flow cytometry and western blot, respectively. In addition, the regulatory relationship between miR-21-5p and orphan nuclear receptor 4A1 (Nr4a1) was revealed by several assays, including the dual-luciferase reporter assay, real-time quantitative polymerase chain reaction (RT-qPCR) and western blot. We found that the Dex treatment significantly alleviated pulmonary injury and decreased the level of MDA and wet/dry weight ratio in PIRI mice. Dex treatment also increased cell viability, reduced apoptotic ratio and downregulated expression levels of Cleaved Caspase-3 and Cleaved Caspase-9 in H/R induced MPVECs. Furthermore, the expression of miR-21-5p was upregulated, while Nr4a1 was downregulated by Dex in a concentration-dependent manner in H/R induced MPVECs. Moreover, Nr4a1 was verified as a target of miR-497-5p. Overexpression of Nr4a1 could reverse the protective effects of Dex on alleviating H/R-induced injury in MPVECs. Taken together, Dex treatment attenuated ischemia-reperfusion induced pulmonary injury through modulating the miR-21-5p/Nr4a1 signaling pathway.