Model Of Lung Ischemia-reperfusion Injury Research Articles

Sevoflurane enhances autophagy via Rac1 to attenuate lung ischaemia‒reperfusion injury

Sevoflurane can attenuate lung ischaemia‒reperfusion injury (LIRI). However, the protective mechanism is unclear. In this study, we developed a LIRI model in vivo that animals (SD, n = 15) were subjected to the administration of 2.2 % sevoflurane 30 min before the onset of left pulmonary artery clamping for 45 min, which was then followed by 60 min of reperfusion treatment. Then, transcriptome sequencing was used to analyse lung tissues. Autophagy inhibition (3-MA) and Rac1-overexpression transfection plasmids were used in BEAS-2B cells, and BEAS-2B cells were subjected to hypoxia reoxygenation (H/R) and sevoflurane treatment. In both animal tissue and cells, inflammatory cytokines and apoptotic and autophagy molecules were measured by quantitative real-time PCR, western blotting and immunostaining. As a result, decreased arterial partial oxygen and damage to the histological structure of lung tissues were observed in LIRI model rats, and these effects were reversed by sevoflurane treatment. Activation of inflammation (elevated IL-1β, IL-6, and TNF-α) and apoptosis (elevated cleaved caspase3/caspase3 and Bax, degraded expression of Bcl2) and inhibition of autophagy (elevated P62, degraded expression of Beclin1 and LC3-II/LC3I) in the model group were ameliorated by sevoflurane. Transcriptome sequencing indicated that the PI3K/Akt pathway regulated by Rac1 plays an important role in LIRI. Furthermore, overexpression of Rac1 in a cell line inhibited the protective effect of sevoflurane in LIRI. Autophagy inhibition (3-MA) also prevented the protective effect of sevoflurane on inflammation and apoptosis.As shown in the present study, sevoflurane enhances autophagy via Rac1/PI3K/AKT signalling to attenuate lung ischaemia‒reperfusion injury.

Erythropoietin alleviates lung ischemia-reperfusion injury by activating the FGF23/FGFR4/ERK signaling pathway.

The purpose of the present study was to investigate the effect of erythropoietin (EPO) on lung ischemia-reperfusion injury (LIRI). Sprague Dawley rats and BEAS-2B cells were employed to construct an ischemia-reperfusion (I/R)-induced model in vivo and in vitro, respectively. Afterward, I/R rats and tert-butyl hydroperoxide (TBHP)-induced cells were treated with different concentrations of EPO. Furthermore, 40 patients with LIRI and healthy controls were enrolled in the study. It was observed that lung tissue damage, cell apoptosis and the expression of BAX and caspase-3 were higher in the LIRI model in vivo and in vitro than in the control group, nevertheless, the Bcl-2, FGF23 and FGFR4 expression level was lower than in the control group. EPO administration significantly reduced lung tissue damage and cell apoptosis while also up-regulating the expression of FGF23 and FGFR4. Rescue experiments indicated that EPO exerted a protective role associated with the FGF23/FGFR4/p-ERK1/2 signal pathway. Notably, the expression of serum EPO, FGF23, FGFR4 and Bcl-2 was decreased in patients with LIRI, while the expression of caspase-3 and BAX was higher. EPO could effectively improve LIRI, which might be related to the activation of the FGF23/FGFR4/p-ERK1/2 signaling pathway.

High Dose ofEstrogen Protects the Lungs from Ischemia-Reperfusion Injury by Downregulating the Angiotensin II Signaling Pathway.

We explored the sex difference in lung ischemia-reperfusion injury (LIRI) and the role and mechanism of estrogen (E2) and angiotensin II (Ang II) in LIRI. We established a model of LIRI in mice. E2, Ang II, E2 inhibitor (fulvestrant), and angiotensin II receptor blocker (losartan) were grouped for treatment. The lung wet/dry weight ratio, natural killer (NK) cells (by flow cytometry), neutrophils (by flow cytometry), expression of key proteins (by Western blot, immunohistochemistry, ELISA, and immunofluorescence), and expression of related protein mRNA (by qPCR) were detected. The ultrastructure of the alveolar epithelial cells was observed by transmission electron microscopy. We found that E2 and Ang II played an important role in the progression of LIRI. The two signaling pathways showed obvious antagonism, and E2 regulates LIRI in the different sexes by downregulating Ang II, leading to a better prognosis. E2 and losartan reduced the inflammatory cell infiltration in lung tissue and key inflammatory factors in serum while fulvestrant and Ang II had the opposite effect. The protective effect of E2 was related with AKT, p38, COX2, and HIF-1α.

Monitorization of autophagic flux in a rat model of lung ischemia-reperfusion injury — Insights on organ transplantation surgery

Ischemia is characterized by cataclysmic oxygen deficiency, but the reperfusion of an ischemic tissue paradoxically causes more serious damage than the ischemia itself. Ischemia/reperfusion (I/R) triggers organ damage, which is frequently observed in organ transplantation surgery, specifically in heavily blooded organs, such as the lung and kidney. To understand the molecular underpinnings of organ damage in transplant surgery, we aimed to monitor autophagic flux, a cellular death pathway, in an organ transplantation scenario created by prolonged ischemia and reperfusion of the lung. We included a total of 48 adult Wistar-Albino rats weighing 250–300 g in this study. We implemented three different ischemia/reperfusion protocols in three different groups (n = 10) based on different reperfusion times, and we observed one randomly created control group for comparison (n = 10). We then probed the gene expression levels of autophagy mediators in normal and pathologic tissues. Autophagy, a cellular death pathway, is sensitive to intracellular oxidative stress, which is one of the most dramatic markers of reperfused-ischemic tissue. In keeping with this ground, we determined that as the duration of reperfusion increases, autophagy driving proteins, Atg5, Atg7, Atg10, Beclin1, and Ulk1, specifically surge. Reperfusion of an ischemic tissue triggers catastrophic cellular death pathway, autophagy, and thus gives rise to a ruinous result. Considering autophagy inhibitor usage might be prophylactic. We indicated that Atg7 and Atg10 are the most dramatically increased mediators of autophagy. Hence, targeting these mediators with specific agents could increase patient survival and shorten the post-surgical recovery period after transplant surgery.

Ginsenoside Rd Attenuates Lung Ischemia/Reperfusion Injury in Mice via Regulating Mitochondrial Function

In emergency and critical care medicine, lung ischemia-reperfusion injury is a prevalent disorder, which has significant morbidity and mortality. However, there is still a lack of effective means to block the lung ischemia-reperfusion injury. Established the lung ischemia-reperfusion injury model of mice; lung injury and histological analysis scoring were helpful to assess pathological injury in lung tissue; using an enzymelinked immunosorbent assay kit, expressed interleukin-6 and interleukin-1 in bronchoalveolar lavage fluids was determined. Seahorse analysis was used to examine the oxygen consumption rate and production of adenosine triphosphate. The expression of mitochondrial function-related genes was detected by realtime polymerase chain reaction; commercially available assay kits used for find the malondialdehyde production and catalase activity; apoptotic cells were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling and protein expression was discovered using Western blotting. Ginsenoside alleviated the pathological changes caused by lung ischemia-reperfusion injury and reduced the lung injury score; ginsenoside Rd therapy reduced inflammatory cell infiltration significantly decreased lung bronchoalveolar lavage fluids interleukin-1 and interleukin-6 levels; ginsenoside Rd also increased the respiratory rate and the adenosine triphosphate production and regulated mitochondrial-related gene expression. Moreover, ginsenoside Rd ameliorated the lung ischemia-reperfusion injury-associated decrease in superoxide dismutase 2 expression, increase in malondialdehyde content and reduction in catalase activity. Additionally, ginsenoside Rd decreased lung ischemia-reperfusion injury-induced apoptosis. Ginsenoside Rd regulates the mitochondrial activity and thus protects against lung ischemiareperfusion injury.

Necrostatin-1 Alleviates Lung Ischemia-Reperfusion Injury via Inhibiting Necroptosis and Apoptosis of Lung Epithelial Cells.

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.

Dexmedetomidine Alleviates Lung Oxidative Stress Injury Induced by Ischemia-Reperfusion in Diabetic Rats via the Nrf2-Sulfiredoxin1 Pathway.

Oxidative stress injury (OSI) is an important pathological process in lung ischemia-reperfusion injury (LIRI), and diabetes mellitus (DM) can exacerbate this injury. Dexmedetomidine protects against LIRI by reducing OSI. However, the effect of dexmedetomidine on LIRI under diabetic conditions remains unclear. Therefore, this study is aimed at exploring the effects and mechanisms of dexmedetomidine on OSI induced by LIRI in diabetic rats. Rats were randomly divided into control+sham (CS), DM+sham (DS), control+ischemia-reperfusion (CIR), DM+ischemia-reperfusion (DIR), and DM+ischemia-reperfusion+dexmedetomidine (DIRD) groups (n = 6). In the CS and DS groups, the nondiabetic and diabetic rats underwent thoracotomy only without LIRI. In the CIR, DIR, and DIRD groups, LIRI was induced through left hilum occlusion for 60 min, followed by reperfusion for 120 min in nondiabetic and diabetic rats, and rats in the DIRD group were administered dexmedetomidine (3, 5, and 10 μg/kg). Compared with those in the CS group, the OSI, lung compliance, apoptosis, and oxygenation indices deteriorated in the DS group (P < 0.05), and these indices were further aggravated in the CIR and DIR groups (P < 0.05), being the worst in the DIR group (P < 0.05). Compared to those of the DIR group, the OSI, lung compliance (15.8 ± 2.4 vs. 11.6 ± 1.7 ml/kg), apoptosis (22.5 ± 2.6 vs. 51.8 ± 5.7), oxygenation (381 ± 58 vs. 308 ± 78 mmHg), and caspase-3 and caspase-9 protein expression indices were attenuated, and Nrf2 and sulfiredoxin1 protein expression was increased in the DIRD group (P < 0.05). And the lung injury, oxygenation, OSI, and Nrf2 and sulfiredoxin1 protein expression changed in a concentration-dependent manner. In conclusion, dexmedetomidine alleviated lung OSI and improved lung function in a diabetic rat LIRI model through the Nrf2-sulfiredoxin1 pathway.

Bag-1L Protects against Cell Apoptosis in an In Vitro Model of Lung Ischemia-Reperfusion Injury through the C-Terminal "Bag" Domain.

Bcl-2-associated athanogene 1 (Bag-1) is a multifunctional and antiapoptotic protein that binds to the antiapoptosis regulator Bcl-2 and promotes cell survival. To investigate the protective function of Bag-1, we examined the effects of Bag-1L, one isoform of Bag-1, in an in vitro cell culture model of lung ischemia-reperfusion injury (LIRI) generated by treatment of A549 cells with hypoxia/reoxygenation. Overexpression of full-length Bag-1L increased the viability of A549 cells and reduced cell apoptosis in response to 6 h of hypoxia/reoxygenation treatment. Furthermore, Bag-1L overexpression enhanced the heat shock protein 70 (HSP70) and Bcl-2 protein levels, increased the phosphorylation of AKT, decreased Bax and cleaved caspase-3 levels, and was able to overcome cell cycle arrest. These effects were not observed in A549 cells overexpressing a truncated form of Bag-1L lacking the “Bag domain,” denoted Bag-1L△C. The “Bag domain” is the C-terminal 47 amino acids. Taken together, the results of this study suggest that Bag-1L overexpression can protect against oxidative stress and apoptosis in an in vitro LIRI model, with a dependence on the Bag domain.

Kaempferol Alleviates Oxidative Stress and Apoptosis Through Mitochondria-dependent Pathway During Lung Ischemia-Reperfusion Injury.

In previous study, we reported that kaempferol ameliorates significantly lung ischemia-reperfusion injury (LIRI), and may be achieved by targeting the SIRT 1 pathway. This study further explored the anti-LIRI mechanism of kaempferol. In vitro, the rat alveolar epithelial cells L2 was cultured and subjected to anoxia/reoxygenation (A/R) insult. In vivo, SD rats were operated to establish LIRI model. The related indicators of oxidative stress and apoptosis in L2 cells and rats lung tissues were detected. Results showed that kaempferol pre-treatment significantly increased the cell viability, improved mitochondrial membrane potential, inhibited the opening of mitochondrial permeability transition pores, reduced the levels of oxidative stress and apoptosis, increased the expressions of Bcl-2 and mitochondrial cytochrome c, and decreased the expressions of Bax and cytoplasmic cytochrome c in L2 cells after A/R insult. In vivo, kaempferol improved the pathological injury, inhibited the levels of oxidative stress and apoptosis, increased the expressions of Bcl-2 and mitochondrial cytochrome c, and decreased the expressions of Bax and cytoplasmic cytochrome c in rats lung tissues after I/R. However, the aforementioned effects of kaempferol were significantly attenuated by the SIRT 1 inhibitor EX527 or the PGC-1α inhibitor SR-18292. What’s more, SR-18292 has not reversed the effect of kaempferol on increasing the protein activity of SIRT 1. Above results suggest that kaempferol ameliorates LIRI by improving mitochondrial function, reducing oxidative stress and inhibiting cell apoptosis. Its molecular mechanism of action includes the SIRT 1/PGC-1α/mitochondria signaling pathway.

Parecoxib mitigates lung ischemia-reperfusion injury in rats by reducing oxidative stress and inflammation and up-regulating HO-1 expression.

ABSTRACTPurpose:To investigate the protective effect of parecoxib against lung ischemia-reperfusion injury (LIRI) in rats and the mechanism.Methods:Thirty rats were divided into sham-operated, LIRI and LIRI+parecoxib groups. LIRI model (ischemia for 60 min, followed by reperfusion for 120 min) was constructed in LIRI and LIRI+parecoxib groups. In LIRI+parecoxib group, 10 mg/kg parecoxib was given via femoral vein 15 min before ischemia beginning. At the end of the reperfusion, blood gas analysis, lung wet to dry mass ratio measurement, lung tissue biochemical determination and heme oxygenase-1 (HO-1) protein expression determination were performed.Results:Compared with LIRI group, in LIRI+parecoxib group the oxygenation index was significantly increased, the alveolar-arterial oxygen partial pressure difference was significantly decreased, the lung wet to dry mass ratio was significantly decreased, the lung tissue malondialdehyde content was significantly decreased, the lung tissue superoxide dismutase and myeloperoxidase activities were significantly increased, the lung tissue tumor necrosis factor α and interleukin 1β levels were significantly decreased, and the lung tissue HO-1 protein expression level was significantly increased (all P < 0.05).Conclusions:Parecoxib pretreatment can mitigate the LIRI in rats by reducing oxidative stress, inhibiting inflammatory response and up-regulating HO-1 expression in lung tissue.

Sodium butyrate relieves lung ischemia-reperfusion injury by inhibiting NF-κB and JAK2/STAT3 signaling pathways.

Ischemia-reperfusion (IR) is the main cause of acute lung injury (ALI) in clinical lung transplantation, extracorporeal circulation, lung sleeve resection, trauma and cardiopulmonary resuscitation. The inflammatory response and oxidative stress following IR are factors that cause and aggravate its secondary damage. The purpose of this study was to investigate the efficacy and mechanism of sodium butyrate (NaB) on lung ischemia-reperfusion injury (LIRI). We used male C57BL/6 mice to construct the LIRI model and administered the mice with NaB. By examining the expression of inflammatory factors and oxidative stress-related molecules in mouse lung tissue, we investigated the effects of NaB on inflammation and oxidative stress in lung tissue after IR. In addition, the changes in the activity of the NF-κB and JAK2/STAT3 signaling pathways were also examined to determine the mechanism of NaB. The expression levels of the inflammatory factors (IL-1β, IL-6 and TNF-α) in lung tissue of mice after IR were significantly increased, while NaB reduced the expression of inflammatory factors. In addition, the oxidative stress level of mouse lung tissue after IR increased significantly, showing the decrease of antioxidant molecules SOD1/2, catalase (CAT), and Peroxiredoxin 1 (Prdx1), while the intake of NaB increased the antioxidant level of mouse lung tissue. The activities of NF-κB and JAK2/STAT3 signaling pathways were significantly increased in lung tissue after IR, whereas NaB inhibited the activity of NF-κB and JAK2/STAT3 signaling pathways. NaB relieves LIRI by inhibiting NF-κB and JAK2/STAT3 signaling pathways to reduce inflammation and oxidative stress levels in lung tissue of mice after IR.

Netrin-1 reduces lung ischemia-reperfusion injury by increasing the proportion of regulatory T cells.

ObjectiveInflammation is the primary mechanism of lung ischemia-reperfusion injury (LIRI) and neurologic factors can regulate inflammatory immune responses. Netrin-1 is an axonal guidance molecule, but whether Netrin-1 plays a role in LIRI remains unclear.MethodsA mouse model of LIRI was established. Immunohistochemistry was used to detect expression of Netrin-1 and to enumerate macrophages and T cells in lung tissue. The proportion of regulatory T cells (Tregs) was assessed by flow cytometry. Levels of apoptosis were assessed by terminal deoxynucleotidyl transferase dUTP nick end staining.ResultsNumbers of macrophages and T cells in the lung tissues of mice with LIRI were elevated, while expression of netrin-1 was significantly decreased. Flow cytometry showed that the proportion of Tregs in mice with LIRI was significantly decreased. The proportion of Tregs among lymphocytes was positively correlated with netrin-1 expression. In vitro experiments showed that netrin-1 promoted an increase in Treg proportion through the A2b receptor. Animal experiments showed that netrin-1 could inhibit apoptosis and reduce T cell and macrophage infiltration by increasing the proportion of Tregs, ultimately reducing LIRI. Treg depletion using an anti-CD25 monoclonal antibody blocked the effects of netrin-1.ConclusionNetrin-1 reduced LIRI by increasing the proportion of Tregs.

Improvement of lung ischemia-reperfusion injury by inhibition of microRNA-155 via reductions in neuroinflammation and oxidative stress of vagal afferent nerve.

Lung ischemia–reperfusion injury (LIRI) is a common clinical concern. As the injury occurs, the pulmonary afferent nerves play a key role in regulating respiratory functions under pathophysiological conditions. The present study was to examine the effects of inhibiting microRNA-155 on the levels of proinflammatory cytokines and products of oxidative stress in the pulmonary vagal afferent nerves and the commissural nucleus of the solitary tract (cNTS) after LIRI. A rat model of LIRI was used. ELISA method was employed to examine proinflammatory cytokines, namely, IL-1β, IL-6 and TNF-α; and key biomarkers of oxidative stress, 8-isoprostaglandin F2α (8-iso PGF2α) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). In results, in the process of LIRI, the levels of microRNA-155 were amplified in the vagal afferent nerves and cNTS, and this was accompanied with increases of IL-1β, IL-6 and TNF-α; and 8-iso PGF2α and 8-OHdG. Application of microRNA-155 inhibitor, but not its scramble, attenuated the elevation of proinflammatory cytokines and amplification of 8-iso PGF2α and 8-OHdG in those nerve tissues. In conclusion, we observed the abnormalities in the pulmonary afferent pathways at the levels of the peripheral nerves and brainstem, which is likely to affect respiratory functions as LIRI occurs. Our data suggest that blocking microRNA-155 signal pathways plays a beneficial role in regulating LIRI via inhibiting responses of neuroinflammation and oxidative stress signal pathways to LIRI.

Dexamethasone on alleviating lung ischemia/reperfusion injury in rats by regulating PI3K/AKT pathway

To investigate the protective effect and mechanism of dexamethasone in lung ischemia/reperfusion injury (LIRI) rats. (1) Part one experiment: 24 Sprague-Dawley (SD) rats were divided into four groups according to the random number method (n = 6): standard ventilation group (N group), normal saline group (NS group), LIRI group, and dexamethasone+LIRI group (DEX group). The rat model of LIRI was established by clamping the left pulmonary hilum for 1 hour and reperfusing it for 2 hours. The DEX group was given dexamethasone 3 mg/kg 5 minutes before reperfusion, and NS group was injected with normal saline. Group N did not receive any treatment. The left lung tissue of the rats in each group were taken alive 2 hours after reperfusion. The lung tissue was harvested for lung wet/dry mass ratio (W/D) measurement. Hematoxylin-eosin (HE) staining and electron microscopy was used to observe the pathological changes of lung tissue and to assess the degree of injury. Ultrastructural changes of lung tissue were observed under electron microscope. The levels of tumor necrosis factor-α (TNF-α), interleukin (IL-1β, IL-6) in lung tissue were detected by enzyme linked immunosorbent assay (ELISA). The expressions of phosphorylated protein kinase B (p-AKT) was detected by Western Blot. (2) Part two experiment: intervention with phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway inhibitor LY294002 to further explore the mechanism of dexamethasone in reducing lung injury induced by LIRI. Twenty-four SD rats were divided into four groups according to the random number method (n = 6): N group, LIRI group, DEX group, and dexamethasone+LY294002+LIRI group (LY group). All the groups except the LY group were treated with membrane and intervention according to part one experiment. The LY group was injected with LY294002 0.3 mg/kg after injection of dexamethasone. The expressions of M1 macrophage polarization markers CD11c, CD16, and M2 macrophage polarization markers CD206, Arg1 were detected by immunohistochemistry. (1) Part one experiment: compared with N group, the morphological and ultrastructural changes of lung tissue in the LIRI group were significantly changed, lung injury score, lung W/D ratio and TNF-α, IL-1β, IL-6 levels were significantly increased, and p-AKT expression was significantly decreased. Compared with the LIRI group, the morphological and ultrastructural changes of the lung tissue in the DEX group were significantly improved, and the lung injury score was reduced (5.00±0.89 vs. 8.83±0.75), lung W/D ratio and TNF-α, IL-1β, IL-6 levels were significantly decreased [lung W/D ratio: 6.25±0.56 vs. 8.27±0.72, TNF-α (ng/L): 93.28±16.42 vs. 205.90±25.30, IL-1β (ng/L): 130.10±10.81 vs. 209.10±19.20, IL-6 (ng/L): 195.80±21.17 vs. 310.50±20.77], p-AKT expression was significantly increased [p-AKT/AKT: (57.58±8.80)% vs. (36.62±9.25)%], and the differences were statistically significant (all P < 0.05). There was no significant difference in each index between NS group and N group. (2) Part two experiment: compared with the N group, the expression of macrophage polarization markers CD11c, CD16, CD206 and Arg1 in the LIRI group were significantly increased. Compared with the LIRI group, the expressions of CD11c and CD16 in the lung tissue of the DEX group were significantly decreased, and the expressions of CD206 and Arg1 were significantly increased. The intervention of PI3K/AKT signaling pathway inhibitor LY294002 significantly blocked the effect of dexamethasone on LIRI-mediated macrophage polarization (CD11c immunohistochemical score: 7.20±0.36 vs. 5.00±0.34, CD16 immunohistochemical score: 8.20±0.48 vs. 7.40±0.64, CD206 immunohistochemical score: 5.80±0.59 vs. 7.40±0.28, Arg1 immunohistochemical score: 7.20±0.72 vs. 8.80±0.48, all P < 0.05). Dexamethasone pretreatment can alleviate the intrapulmonary inflammatory response and lung injury caused by LIRI in rats. The mechanism of action is related to the polarization direction of pulmonary macrophagesvia activation of the PI3K/AKT pathway by dexamethasone.

Role and related mechanism of resolvin D1 in lung ischemia reperfusion injury in rats

Objective: To investigate the role and related mechanism of resolvin D1 (RvD1) in lung ischemia-reperfusion injury (LIRI) in rats. Methods: Forty male Sprague-Dawley rats, 7-8 weeks, weighing 220-280 g, were divided into 4 groups using a random number table method: sham operation group, lung ischemia reperfusion control group, normal saline group, and RvD1 group. The rat model of LIRI was produced by 45 min of occlusion of the left hilum of lungs followed by 150 min reperfusion. In sham group, no blocking of the left hilum of lung after thoracotomy; Normal saline 2 ml/kg and RvD1 100 μg/kg were injected respectively at 10 min of reperfusion in normal saline group and RvD1 group. Blood samples were collected from the femoral vein for determination of interleukin (IL)-6, tumor necrosis factor (TNF)-α, soluble inter-cell adhesion molecules (sICAM-1) concentrations at 150 min of reperfusion. The rats were sacrificed after collection of blood samples and then lung tissues were taken for observation of the pathological changes and for measurement of lung wet/dry weight ratio (W/D). The the contents of malondialdehyde (MDA), monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-2 and the activity of myeloperoxidase (MPO) in lung tissues were determined. The protein relative expression of nuclear factor (NF)-κB in lung tissues was detected by Western blot. Lung tissue cell apoptosis was detected with TUNEL method. Results: The plasma level of IL-6, TNF-α, sICAM-1 in normal saline group and RvD1 group were significantly higher than those in the Sham group [(110±7), (100±4) vs (72±3) ng/L, (151±8), (153±6) vs (104±5) ng/L, (2 690±133), (2 760±167) vs (1 953±125) ng/L]. Besides, NF-κB protein relative expression level of lung tissues up-regulated [(0.681±0.033), (0.664±0.024) vs (0.292±0.011)] (all P<0.05). The W/D, apoptosis index, MDA, MCP-1, MIP-2 contents and MPO activity in lung ischemia reperfusion control group, normal saline group and RvD1 group were significantly higher than those in the Sham group [(5.92±0.31), (5.85±0.24), (5.06±0.08) vs (4.14±0.10), (32.9±1.5)%, (31.9±1.3)%, (17.7±1.8)% vs (8.1±0.6)%, (72.1±2.3), (66.7±3.7), (34.0±1.4) vs (22.0±0.8) nmol/mg, (3.99±0.28), (3.86±0.25), (2.66±0.16) vs (1.47±0.17) pg/mg, (9.45±0.53), (9.68±0.62), (7.62±0.22) vs (4.70±0.41) pg/mg, (3.01±0.18), (2.92±0.19), (1.58±0.11) vs (0.98±0.07) U/g] (all P<0.05). The plasma levels of the cytokines mentioned above, the W/D, the apoptosis index, MDA, MCP-1, MIP-2 contents and MPO activity in RvD1 group were significantly lower than those in the lung ischemia reperfusion control group [(63±4) vs (110±7) ng/L, (90±8) vs (151±8) ng/L, (1 835±182) vs (2 690±133) ng/L, (5.06±0.08) vs (5.92±0.31), (17.7±1.8)% vs (32.9±1.5)%, (34.0±1.4) vs (72.1±2.3) nmol/mg, (2.66±0.16) vs (3.99±0.28) pg/mg, (7.62±0.22) vs (9.45±0.53) pg/mg, (1.58±0.11) vs (3.01±0.18) U/g]. Besides, NF-κB protein relative expression level of lung tissues down-regulated [(0.313±0.012) vs (0.681±0.033)] (all P<0.05). Inflammatory cell infiltration in LIRI groups increased significantly, while it was significantly reduced in RvD1 group. Conclusion: RvD1 can effectively alleviate the tissue damage caused by lung ischemia-reperfusion through down-regulating NF-κB expression, relieving inflammatory reaction and oxidative stress, reducing apoptosis in rats.

Dexmedetomidine Ameliorates Post-CPB Lung Injury in Rats by Activating the PI3K/Akt Pathway

Purpose: To investigate the protective effects of dexmedetomidine (Dex) on post cardiopulmonary bypass (CPB) lung injury in rats and to explore the possibility of underlying mechanisms involving phosphatidylinositol 3-kinase (PI3K)/Akt. Materials and Methods: Forty healthy male Sprague–Dawley rats were randomly divided into five groups (n = 8 for each). A left lung ischemia-reperfusion injury model of CPB was established in all five groups. Rats were given saline, dexmedetomidine (Dex), dimethyl sulfoxide (DMSO), wortmannin (Wtm), and Dex plus Wtm during the CPB process, in Group Saline, Dex, DMSO, Wtm, and Dex + Wtm, respectively. Mean arterial pressure, oxygenation index (OI), and respiratory index (RI) were measured at the following three timepoints: before CPB (T1), at the onset of opening of the left hilus pulmonis (T2), and at the end of the CPB process (T3). At T3, hematoxylin and eosin (H&E) staining was conducted to evaluate pathology of lung injury. The rate of lung tissue apoptosis was determined by flow-cytometry. The expression of Akt, p-Akt, caspase-3, and caspase-9 was assessed by Western blot. Results: Dex treatment during CPB protected rat lungs from post-CPB lung injury, manifested by improved lung function, mitigated pathological damage, and reduced lung tissue apoptosis. The expression and phosphorylation of Akt was significantly enhanced by Dex treatment compared to the saline/DMSO-treated group. Wtm, a recognized PI3K inhibitor, abolished the protective effect of Dex. The levels of caspase-3 and caspase-9 were also significantly elevated in the Wtm-treated group. Conclusions: Dex reduces post-CPB lung injury in rats, at least partially, by activating the PI3K/Akt pathway and inhibiting lung tissue apoptosis.

The protective effects of heat shock protein 22 in lung ischemia-reperfusion injury mice

Lung ischemia-reperfusion injury (LIRI) often results in respiratory insufficiency after pulmonary embolism, lung transplantation, etc. To investigate the role of HSP22 in LIRI mice, ischemia-reperfusion injury was established in the left lung of an HSP22 overexpression transgenic mouse. Twelve HSP22 transgenic (TG) mice and twelve wild-type (WT) mice were randomly divided into 2 groups: the sham-operated group (SO: TG-SO, WT-SO) and the ischemia-reperfusion group (I/R: TG-I/R, WT-I/R), respectively. We tested the PaO2, W/D ratio, and MDA level; observed morphology changes; and calculated the index of alveolar damage. HSP22 expression was examined in lung tissues of TG and WT C57BL mice by immunohistochemistry. TUNEL assay was performed to measure apoptosis. We found that HSP22 was significantly overexpressed in TG mice. There was no difference in PaO2 among the four groups. In the I/R group, the W/D ratio, MDA and index of alveolar damage were higher than those in the SO group. Moreover, compared with WT-I/R group, the W/D ratio, MDA and index of alveolar damage in the TG-I/R group were significantly decreased. Apoptosis in the I/R groups was increased compared to that in the SO groups, while apoptosis in the TG-I/R groups was decreased compared to that in the WT-I/R groups. Our results showed that HSP22 TG mice and the LIRI model were successfully established. In addition, HSP22 overexpression has protective effects on LIRI by inhibiting lipid peroxidation and apoptosis.

Effects of Sildenafil and Tadalafil on Edema and Reactive Oxygen Species Production in an Experimental Model of Lung Ischemia-Reperfusion Injury

BackgroundLung ischemia-reperfusion injury is characterized by formation of reactive oxygen species and cellular swelling leading to pulmonary edema and primary graft dysfunction. Phosphodiesterase 5 inhibitors could ameliorate lung ischemia-reperfusion injury by interfering in many molecular pathways. The aim of this work was to evaluate and compare the effects of sildenafil and tadalafil on edema and reactive oxygen species formation in an ex vivo nonhuman animal model of lung ischemia-reperfusion injury. MethodsThirty-two Wistar rats were distributed, treated, perfused and the cardiopulmonary blocks were managed as follows: control group: immediate excision and reperfusion without pretreatment; ischemia reperfusion group: treatment with dimethylsulfoxide 0.9% and excision 1 hour later; sildenafil group: treatment with sildenafil (0.7 mg/kg) and excision 1 hour later; and tadalafil group: treatment with tadalafil (0.15 mg/kg) and excision 2 hours later. All cardiopulmonary blocks except control group were preserved for 8 hours and then reperfused. Pulmonary arterial pressure, pulmonary venous pressure, and capillary filtration coefficient were measured. Reactive oxygen species were measured. ResultsEdema was similar between control and sildenafil groups, but significantly greater in the ischemia-reperfusion (P ≤ .04) and tadalafil (P ≤ .003) groups compared with the sildenafil group. The malondialdehyde levels were significantly lower in the sildenafil (P ≤ .001) and tadalafil (P ≤ .001) groups than the ischemia-reperfusion group. ConclusionsAdministration of sildenafil, but not tadalafil, decreased edema in lung ischemia-reperfusion injury. Both drugs decreased reactive oxygen species formation in a lung ischemia-reperfusion injury model.

Biliverdin Protects the Isolated Rat Lungs from Ischemia-reperfusion Injury via Antioxidative, Anti-inflammatory and Anti-apoptotic Effects.

Background:Biliverdin (BV) has a protective role against ischemia-reperfusion injury (IRI). However, the protective role and potential mechanisms of BV on lung IRI (LIRI) remain to be elucidated. Thus, we aimed to investigate the protective role and potential mechanisms of BV on LIRI.Methods:Lungs were isolated from Sprague-Dawley rats to establish an ex vivo LIRI model. After an initial 15 min stabilization period, the isolated lungs were subjected to ischemia for 60 min, followed by 90 min of reperfusion with or without BV treatment.Results:Lungs in the I/R group exhibited significant decrease in tidal volume (1.44 ± 0.23 ml/min in I/R group vs. 2.41 ± 0.31 ml/min in sham group; P < 0.001), lung compliance (0.27 ± 0.06 ml/cmH2O in I/R group vs. 0.44 ± 0.09 ml/cmH2O in sham group; P < 0.001; 1 cmH2O=0.098 kPa), and oxygen partial pressure (PaO2) levels (64.12 ± 12 mmHg in I/R group vs. 114 ± 8.0 mmHg in sham group; P < 0.001; 1 mmHg = 0.133 kPa). In contrast, these parameters in the BV group (2.27 ± 0.37 ml/min of tidal volume, 0.41 ± 0.10 ml/cmH2O of compliance, and 98.7 ± 9.7 mmHg of PaO2) were significantly higher compared with the I/R group (P = 0.004, P < 0.001, and P < 0.001, respectively). Compared to the I/R group, the contents of superoxide dismutase were significantly higher (47.07 ± 7.91 U/mg protein vs. 33.84 ± 10.15 U/mg protein; P = 0.005) while the wet/dry weight ratio (P < 0.01), methane dicarboxylic aldehyde (1.92 ± 0.25 nmol/mg protein vs. 2.67 ± 0.46 nmol/mg protein; P < 0.001), and adenosine triphosphate contents (297.05 ± 47.45 nmol/mg protein vs. 208.09 ± 29.11 nmol/mg protein; P = 0.005) were markedly lower in BV-treated lungs. Histological analysis revealed that BV alleviated LIRI. Furthermore, the expression of inflammatory cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-β) was downregulated and the expression of cyclooxygenase-2, inducible nitric oxide synthase, and Jun N-terminal kinase was significantly reduced in BV group (all P < 0.01 compared to I/R group). Finally, the apoptosis index in the BV group was significantly decreased (P < 0.01 compared to I/R group).Conclusion:BV protects lung IRI through its antioxidative, anti-inflammatory, and anti-apoptotic effects.

Apigenin Reduces NF-κB and Subsequent Cytokine Production as Protective Effect in a Rodent Animal Model of Lung Ischemia-Reperfusion Injury

ABSTRACTPurpose: Lung ischemia–reperfusion injury (LIRI) can complicate lung transplantation or cardiac surgery with cardiopulmonary bypass, increasing morbidity and mortality. In LIRI, pro-inflammatory cytokines are activated, reactive oxygen species are generated and nuclear factor-κB (NF-κB) is up-regulated, altering lung mechanics. We tested the effect of the flavonoid apigenin on a rodent model of LIRI. Methods: Thirty-seven Wistar rats were subjected to LIRI with or without a single or double dose of apigenin. Induction of LIRI involved sternotomy and clamping of either the left lung hilum or the pulmonary artery alone for 30 min, followed by 60 min of reperfusion. Control groups consisted of LIRI plus NaCl, a sham group and a baseline group. At the end of the experiments, both lungs were analyzed by RT-PCR, Western blot, and light microscopy. Results: In placebos, the expression levels of pro-inflammatory markers were increased in both lungs significantly, whereas NF-κB was markedly up-regulated. Administration of apigenin reduced the activation of NF-κB and the expression of TNFα, iNOS, and IL-6. These effects were observed in total lung ischemia. Histology showed greater hemorrhage and exudation in the pulmonary periphery of all groups, whereby damage was practically absent in the central lung regions of the apigenin animals. A second dose of apigenin did not outclass a single one. Conclusions: We conclude that apigenin given intraperitoneally can reduce activation of NF-κB and also attenuate the expression of TNFα, IL-6, and iNOS in a surgical model of LIRI. The surgical procedure itself can induce significant damage to the lungs.