Glutamine protects ischemia-reperfusion induced acute lung injury in isolated rat lungs

Evaluation of the effect of enriched hydrogen saline solution on distant organ (lung) damage in skeletal muscle ischemia reperfusion in rats

INTRODUCTION

Ischemia-reperfusion (IR) injury is a major concern that frequently occurs during vascular surgeries. Hydrogen-rich saline (HRS) solution exhibits antioxidant and anti-inflammatory properties. This study aimed to examine the effects of HRS applied before ischemia in the lungs of rats using a lower extremity IR model.

MATERIAL AND METHODS

After approval was obtained from the ethics committee, 18 male Wistar albino rats weighing 250-280 g were randomly divided into three groups: control (C), IR and IR-HRS. In the IR and IR-HRS groups, an atraumatic microvascular clamp was used to clamp the infrarenal abdominal aorta, and skeletal muscle ischemia was induced. After 120 min, the clamp was removed, and reperfusion was achieved for 120 min. In the IR-HRS group, HRS was administered intraperitoneally 30 min before the procedure. Lung tissue samples were examined under a light microscope and stained with hematoxylin-eosin (H&E). Malondialdehyde (MDA) levels, total sulfhydryl (SH) levels, and histopathological parameters were evaluated in the tissue samples.

RESULTS

MDA and total SH levels were significantly higher in the IR group than in the control group (p < 0.0001 and p = 0.001, respectively). MDA and total SH levels were significantly lower in the IR-HRS group than in the IR group (p < 0.0001 and p = 0.013, respectively). A histopathological examination revealed that neutrophil infiltration/aggregation, alveolar wall thickness, and total lung injury score were significantly higher in the IR group than in the control group (p < 0.0001, p = 0.001, and p < 0.0001, respectively). Similarly, alveolar wall thickness and total lung injury scores were significantly higher in the IR-HRS group than in the control group (p = 0.009 and p = 0.004, respectively). A statistically significant decrease was observed in neutrophil infiltration/aggregation and total lung injury scores in the IR-HRS group compared to those in the IR group (p = 0.023 and p = 0.022, respectively).

CONCLUSION

HRS at a dose of 20 mg/kg, administered intraperitoneally 30 min before ischemia in rats, reduced lipid peroxidation and oxidative stress, while also reducing IR damage in lung histopathology. We believe that HRS administered to rats prior to IR exerts a lung-protective effect.

L-alanyl-L-glutamine modified perfusate improves human lung cell functions and extend porcine ex vivo lung perfusion

BACKGROUND

The clinical application of normothermic ex vivo lung perfusion (EVLP) has increased donor lung utilization for transplantation through functional assessment. To develop it as a platform for donor lung repair, reconditioning and regeneration, the perfusate should be modified to support the lung during extended EVLP.

METHODS

Human lung epithelial cells and pulmonary microvascular endothelial cells were cultured, and the effects of Steen solution (commonly used EVLP perfusate) on basic cellular function were tested. Steen solution was modified based on screening tests in cell culture, and further tested with an EVLP cell culture model, on apoptosis, GSH, HSP70, and IL-8 expression. Finally, a modified formula was tested on porcine EVLP. Physiological parameters of lung function, histology of lung tissue, and amino acid concentrations in EVLP perfusate were measured.

RESULTS

Steen solution reduced cell confluence, induced apoptosis, and inhibited cell migration, compared to regular cell culture media. Adding L-alanyl-L-glutamine to Steen solution improved cell migration and decreased apoptosis. It also reduced cold preservation and warm perfusion-induced apoptosis, enhanced GSH and HSP70 production, and inhibited IL-8 expression on an EVLP cell culture model. L-alanyl-L-glutamine modified Steen solution supported porcine lungs on EVLP with significantly improved lung function, well-preserved histological structure, and significantly higher levels of multiple amino acids in EVLP perfusate.

CONCLUSIONS

Adding L-alanyl-L-glutamine to perfusate may provide additional energy support, antioxidant, and cytoprotective effects to lung tissue. The pipeline developed herein, with cell culture, cell EVLP, and porcine EVLP models, can be used to further optimize perfusates to improve EVLP outcomes.

Dietary Glutamine Inclusion Regulates Immune and Antioxidant System, as Well as Programmed Cell Death in Fish to Protect against Flavobacterium columnare Infection

The susceptibility of animals to pathogenic infection is significantly affected by nutritional status. The present study took yellow catfish (Pelteobagrus fulvidraco) as a model to test the hypothesis that the protective roles of glutamine during bacterial infection are largely related to its regulation on the immune and antioxidant system, apoptosis and autophagy. Dietary glutamine supplementation significantly improved fish growth performance and feed utilization. After a challenge with Flavobacterium columnare, glutamine supplementation promoted il-8 and il-1β expression via NF-κB signaling in the head kidney and spleen, but inhibited the over-inflammation in the gut and gills. Additionally, dietary glutamine inclusion also enhanced the systematic antioxidant capacity. Histological analysis showed the protective role of glutamine in gill structures. Further study indicated that glutamine alleviated apoptosis during bacterial infection, along with the reduced protein levels of caspase-3 and the reduced expression of apoptosis-related genes. Moreover, glutamine also showed an inhibitory role in autophagy which was due to the increased activation of the mTOR signaling pathway. Thus, our study for the first time illustrated the regulatory roles of glutamine in the fish immune and antioxidant system, and reported its inhibitory effects on fish apoptosis and autophagy during bacterial infection.

The Effect of Cerium Oxide on Lung Tissue in Lower Extremity Ischemia Reperfusion Injury in Sevoflurane Administered Rats

Introduction

We aimed to investigate the effects of cerium oxide, applied before the sevoflurane anesthesia, on lung tissue in rats with lower extremity ischemia-reperfusion (IR).

Materials and Methods

A total of 30 rats were randomly divided into five groups as; control (C), IR, cerium oxide-IR (CO-IR), IR-sevoflurane (IRS), and cerium oxide-IR-sevoflurane (CO-IRS). In the CO-IR group, 30 minutes after the injection of cerium oxide (0.5 mg/kg, intraperitoneal (i.p)), an atraumatic microvascular clamp was placed on the infrarenal abdominal aorta for 120 minutes. Then, the clamp was removed and reperfused for 120 minutes. Sevoflurane was applied in 100% oxygen at a rate of 2.3% at 4 L/min during IR. The blood samples were taken for biochemical analysis and the lung tissue samples were taken for histological analysis.

Results

Neutrophil infiltration/aggregation was significantly higher in the IR group than in the C and CO-IRS groups. The alveolar wall thickness and total lung injury scores were significantly higher in the IR group than in the C, IRS, CO-IR and CO-IRS groups.

Discussion

We determined that the administration of 0.5 mg/kg dose of cerium oxide with sevoflurane reduces the oxidative stress and corrects IR-related damage in lung tissue. Our results show that the administration of cerium oxide before IR and the administration of sevoflurane during IR have a protective effect in rats.

Acupoint Catgut Embedding Improves the Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome in Rats

Background

This study investigated the potential therapeutic effects of acupoint catgut embedding (ACE) at ST36 and BL13 on lipopolysaccharide- (LPS-) induced acute respiratory distress syndrome (ARDS) in rats.

Materials and Methods

Male Sprague-Dawley rats were randomized into the normal saline (NS group with a sham procedure), lipopolysaccharide (LPS group with a sham procedure), and LPS plus ACE (LPS+ACE with ACE at bilateral BL13 and ST36 acupoints one day before LPS injection) groups. After intratracheal instillation of normal saline or LPS (0.5 mg/kg), all rats were subjected to mechanical ventilation for 4 h. Their blood gas was analyzed before and after lung injury, and their lung pressure-volumes were measured longitudinally. The levels of TNF-α, IL-6, IL-10, and phosphatidylcholine (PC) and total proteins (TP) in bronchial alveolar lavage fluid (BALF) were assessed. Their wet to dry lung weight ratios, histology, myeloperoxidase (MPO), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) levels were measured. Their lung aquaporin 1 (AQP1) and Occludin protein levels were analyzed.

Results

LPS administration significantly decreased the ratios of PaO₂/FiO₂ and pressure-volumes and induced lung inflammation and injury by increased concentrations of TNF-α, IL-6, IL-10, and TP in BALF and MPO and MDA in the lung but decreased PC in BALF and SOD activity in the lungs. LPS also reduced AQP1 and Occludin protein levels in the lung of rats. In contrast, ACE significantly mitigated the LPS-induced lung injury, inflammation, and oxidative stress and preserved the AQP1 and Occludin contents in the lung of rats.

Conclusions

ACE significantly improved respiratory function by mitigating inflammation and oxidative stress and preserving AQP1 and Occludin expression in the lung in a rat model of LPS-induced ARDS.

Cytochrome P450 Epoxygenase 2J2 Protects Against Lung Ischemia/Reperfusion Injury by Activating the P13K/Akt/GSK-3-β/NF-kB Signaling Pathway During Deep Hypothermic Low Flow in Mice

BACKGROUND

Cytochrome P450 epoxygenase 2J2 (CYP2J2) metabolizes arachidonic acid to epoxyeicosatrienoic acids, which exert anti-inflammatory effects and alleviate oxidative stress in the cardiovascular system. Our previous work revealed that CYP2J2 is expressed in pulmonary artery endothelial cells. It was therefore hypothesized that CYP2J2 overexpression may prevent lung ischemia/reperfusion injury (LIRI) in 3-week-old C57BL/6 mice during deep hypothermic low flow (DHLF). This study aimed to establish whether CYP2J2 protects against LIRI and the mechanisms of CYP2J2 overexpression during DHLF in mice. The aim of this study was to explore the effects of DHLF on lung tissue in mice and to find out the regularity of this process, so as to provide theoretical data for lung tissue protection in children undergoing this process in clinic.

METHODS

A 3-week-old C57BL/6 mouse model was used to mimic LIRI conditions during DHLF by clamping the left pulmonary artery and left main bronchus for 120 min, followed by reperfusion for 2 h. The body temperature of the mice was maintained between 18°C and 19°C to induce DHLF.

RESULTS

During DHLF, lung ischemia/reperfusion increased the left lung wet/dry weight, the left lung weight/body weight ratio, the protein concentration in bronchoalveolar lavage fluid, and the concentration of proinflammatory mediators in the lungs, including interleukin (IL)-1, IL-8, and necrosis factor (NF)-α, and decreased the concentration of the anti-inflammatory mediator IL-10. Furthermore, activation of NF-κB p65 and degradation of IKBα were remarkably increased in lung tissues after ischemia/reperfusion. The CYP2J2 overexpression group showed the opposite results (P < 0.05), and p-Akt1 and p-GSK-3β expression were significantly higher in the CYP2J2 overexpression group (P < 0.05). Moreover, the changes in IL-1, IL-8, tumor necrosis factor-α, IL-10, p-Akt1, p-GSK-3β, NF-κB p65, and IKBα were reversed in the Akt1 gene heterozygous knockout group, and lung damage was significantly higher in the Akt1 gene heterozygous knockout group than in the CYP2J2 overexpression group. CYP2J2 overexpression can protect against LIRI, whereas Akt1 gene heterozygous knockout in mice can abolish this protective effect.

CONCLUSIONS

CYP2J2 overexpression can protect against LIRI by activating the P13K/Akt/GSK-3β/NF-kB signaling pathway during DHLF. Thus, changing CYP2J2 expression can be a novel strategy for the prevention and treatment of LIRI during DHLF.

Early Protection by Resveratrol in Rat Lung Transplantation

BACKGROUND Resveratrol is a multifunctional bioactive substance that has effects in anti-inflammation and prevention of ischemia-reperfusion injury. This study compared the inflammation and expression of related proteins during the early stages after transplantation to explore the effects and mechanisms of resveratrol on transplanted lung. MATERIAL AND METHODS Sprague-Dawley rats were randomized to receive pretreatment of resveratrol suspension (60 mg/kg; RES group), dexamethasone (1 mg/kg; DEM group), or normal saline solution (2 mL/kg; control group) 1 h before lung transplantation. The cytokine concentration in the serum and bronchoalveolar lavage fluid (BALF) of the recipients was determined 24 h after transplantation. Histopathologic evaluation, including lung injury score, and the expression of necroptosis-associated proteins was assessed. RESULTS Histopathologic evaluation showed pneumocyte damage and endothelialitis associated with hemorrhage in the alveoli in the control group, the severity of which was greater than that in the other 2 groups. The levels of interleukin-6 and tumor necrosis factor-a in the serum and BALF of the RES and DEM groups were lower than those in the control group. The expression of necroptosis-associated proteins in the RES group was lower than that in the control group, and was inversely proportional to lung injury. CONCLUSIONS Pretreatment with resveratrol protected rat lung in the early stages after transplantation. We determined a relationship between necroptosis-associated proteins and transplanted lung injury, which suggests that the mechanism of lung transplantation-associated ischemia-reperfusion injury may be related to necroptosis.

Protective Effects of Neural Crest-Derived Stem Cell-Conditioned Media against Ischemia-Reperfusion-Induced Lung Injury in Rats

Current treatments for ischemia-reperfusion (IR)-induced acute lung injury are limited. Mesenchymal stem cell-conditioned medium (CM) has been reported to attenuate lung injury. Neural crest stem cells (NCSCs), a type of multipotent stem cells, are more easily obtained than mesenchymal stem cells. We hypothesize that NCSC-CM has anti-inflammatory properties that could protect against IR-induced lung injury in rats. In this study, NCSC-CM was derived from rat NCSCs. Typical acute lung injury was induced by 30-min ischemia followed by 90-min reperfusion in adult male Sprague–Dawley rats. Bronchoalveolar lavage fluid (BALF) and lung tissues were collected to analyze the degree of lung injury after the experiment. NCSC-CM was administered before ischemia and after reperfusion. NCSC-CM treatment significantly attenuated IR-induced lung edema, as indicated by decreases in pulmonary vascular permeability, lung weight gain, wet to dry weight ratio, lung weight to body weight ratio, pulmonary arterial pressure, and protein level in BALF. The levels of tumor necrosis factor-α and interleukin-6 in the BALF were also significantly decreased. Additionally, NCSC-CM improved lung pathology and neutrophil infiltration in the lung tissue, and significantly suppressed nuclear factor (NF)-κB activity and IκB-α degradation in the lung. However, heating NCSC-CM eliminated these protective effects. Our experiment demonstrates that NCSC-CM treatment decreases IR-induced acute lung injury and that the protective mechanism may be attributable to the inhibition of NF-κB activation and the inflammatory response. Therefore, NCSC-CM may be a novel approach for treating IR-induced lung injury.

Attenuation of acute lung injury in a rat model by Semen Cassiae

Background

Acute lung injury (ALI) is an inflammatory disorder. Semen Cassiae has potent anti-inflammatory activities. The aim of our study was to investigate whether Semen Cassiae plays a protective effect on lipopolysaccharide (LPS)-induced ALI and, if so, to elucidate its potential mechanism.

Methods

Male Sprague–Dawley rat lungs were injured by intratracheal instillation of LPS. Rats were treated with Semen Cassiae or vehicle 3 h after LPS challenge. Samples were harvested 24 h post-LPS administration. We also investigated the effects of Semen Cassiae on LPS stimulation in RAW 264.7 cells.

Results

LPS administration markedly induced pulmonary edema and polymorphonuclear neutrophil influxes. These changes were significantly attenuated in Semen Cassiae treated group. Moreover, Semen Cassiae markedly reduced pulmonary interleukin (IL)-6, tumor necrosis factor (TNF)-α, and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels. The pulmonary soluble epoxide hydrolase (sEH) activity and the DNA binding activity of Nuclear factor (NF)-κB were significantly inhibited in Semen Cassiae treated group. Furthermore, Semen Cassiae treatment significantly increased epoxyeicosatrienoic acids (EETs), and heme oxygenase-1 (HO-1) activity. Our in vitro study demonstrates that Semen Cassiae treatment may inhibit LPS induced IκBα phosphorylation and NF-κB p65 nucleus translocation.

Conclusion

Semen Cassiae protects LPS-induced ALI in rats. Semen Cassiae can be developed as a novel treatment for ALI.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1747-7) contains supplementary material, which is available to authorized users.

Targeting of nicotinamide phosphoribosyltransferase enzymatic activity ameliorates lung damage induced by ischemia/reperfusion in rats

Background

Emerging evidence reveals that nicotinamide phosphoribosyltransferase (NAMPT) has a significant role in the pathophysiology of the inflammatory process. NAMPT inhibition has a beneficial effect in the treatment of a variety of inflammatory diseases. However, it remains unclear whether NAMPT inhibition has an impact on ischemia-reperfusion (I/R)-induced acute lung injury. In this study, we examined whether NAMPT inhibition provided protection against I/R lung injury in rats.

Methods

Isolated perfused rat lungs were subjected to 40 min of ischemia followed by 60 min of reperfusion. The rats were randomly allotted to the control, control + FK866 (NAMPT inhibitor, 10 mg/kg), I/R, or I/R + FK866 groups (n = 6 per group). The effects of FK866 on human alveolar epithelial cells exposed to hypoxia-reoxygenation (H/R) were also investigated.

Results

Treatment with FK866 significantly attenuated the increases in lung edema, pulmonary arterial pressure, lung injury scores, and TNF-α, CINC-1, and IL-6 concentrations in bronchoalveolar lavage fluid in the I/R group. Malondialdehyde levels, carbonyl contents and MPO-positive cells in lung tissue were also significantly reduced by FK866. Additionally, FK866 mitigated I/R-stimulated degradation of IκB-α, nuclear translocation of NF-κB, Akt phosphorylation, activation of mitogen-activated protein kinase, and downregulated MKP-1 activity in the injured lung tissue. Furthermore, FK866 increased Bcl-2 and decreased caspase-3 activity in the I/R rat lungs. Comparably, the in vitro experiments showed that FK866 also inhibited IL-8 production and NF-κB activation in human alveolar epithelial cells exposed to H/R.

Conclusions

Our findings suggest that NAMPT inhibition may be a novel therapeutic approach for I/R-induced lung injury. The protective effects involve the suppression of multiple signal pathways.

Experimental chronic kidney disease attenuates ischemia-reperfusion injury in an ex vivo rat lung model

Lung ischemia reperfusion injury (LIRI) is one of important complications following lung transplant and cardiopulmonary bypass. Although patients on hemodialysis are still excluded as lung transplant donors because of the possible effects of renal failure on the lungs, increased organ demand has led us to evaluate the influence of chronic kidney disease (CKD) on LIRI. A CKD model was induced by feeding Sprague-Dawley rats an adenine-rich (0.75%) diet for 2, 4 and 6 weeks, and an isolated rat lung in situ model was used to evaluate ischemia reperfusion (IR)-induced acute lung injury. The clinicopathological parameters of LIRI, including pulmonary edema, lipid peroxidation, histopathological changes, immunohistochemistry changes, chemokine CXCL1, inducible nitric oxide synthase (iNOS), proinflammatory and anti-inflammatory cytokines, heat shock protein expression, and nuclear factor-κB (NF-κB) activation were determined. Our results indicated that adenine-fed rats developed CKD as characterized by increased blood urea nitrogen and creatinine levels and the deposition of crystals in the renal tubules and interstitium. IR induced a significant increase in the pulmonary arterial pressure, lung edema, lung injury scores, the expression of CXCL1 mRNA, iNOS level, and protein concentration of the bronchial alveolar lavage fluid (BALF). The tumor necrosis factor-α levels in the BALF and perfusate; the interleukin-10 level in the perfusate; and the malondialdehyde levels in the lung tissue and perfusate were also significantly increased by LIRI. Counterintuitively, adenine-induced CKD significantly attenuated the severity of lung injury induced by IR. CKD rats exhibited increased heat shock protein 70 expression and decreased activation of NF-κB signaling. In conclusion, adenine-induced CKD attenuated LIRI by inhibiting the NF-κB pathway.

Neuroprotective effects of Aceglutamide on motor function in a rat model of cerebral ischemia and reperfusion

PURPOSE

To investigate the effect and underlying mechanism of Aceglutamide on motor dysfunction in rats after cerebral ischemia-reperfusion.

METHODS

Adult male Sprague-Dawley rats were subjected to 2 h transient middle cerebral artery occlusion (MCAO). Aceglutamide or vehicle was intraperitoneally given to rats at 24 h after reperfusion and lasted for 14 days. Subsequently functional recovery was assessed and number of tyrosine hydroxylase (TH)-positive neurons in substantia nigra (SN) was analyzed. Tumor necrosis factor receptor-associated factor 1(TRAF1), P-Akt and Bcl-2/Bax were determined in mesencephalic tissue by Western blot method. PC12 cells and primary cultured mesencephalic neurons were employed to further investigate the mechanism of Aceglutamide.

RESULTS

Aceglutamide treatment improved behavioral functions, reduced the infarction volume, and elevated the number of TH-positive neurons in the SN. Moreover, Aceglutamide significantly attenuated neuronal apoptosis in the SN. Meanwhile Aceglutamide treatment significantly inhibited the expression of TRAF1 and up-regulated the expression of P-Akt and Bcl-2/Bax ratio both in vitro and in vivo.

CONCLUSIONS

Aceglutamide ameliorated motor dysfunction and delayed neuronal death in the SN after ischemia, which involved the inhibition of pro-apoptotic factor TRAF1 and activation of Akt/Bcl-2 signaling pathway. These data provided experimental information for applying Aceglutamide to ischemic stroke treatment.

Dexmedetomidine protects from post-myocardial ischaemia reperfusion lung damage in diabetic rats

OBJECTIVE

Diabetic complications and lipid peroxidation are known to have a close association. Lipid peroxidation commonly occurs at sites exposed to ischaemia, but distant organs and tissues also get damaged during ischaemia/reperfusion (I/R). Some of these targets are vital organs, such as the lung, liver, and kidney; the lung is the most frequently affected. The aim of our study was to investigate the effects of dexmedetomidine on I/R damage in lung tissue and on the oxidant/anti-oxidant system in diabetic rats.

MATERIAL AND METHODS

Diabetes was induced with streptozotocin (55 mg/kg) in 18 Wistar Albino rats, which were then randomly divided into three groups (diabetes control (DC), diabetes plus ischaemia-reperfusion (DIR), and diabetes plus dexmedetomidine-ischaemia/reperfusion (DIRD)) after the effects of diabetes were clearly evident. The rats underwent a left thoracotomy and then ischaemia was produced in the myocardium muscle by a left anterior descending artery ligation for 30 min in the DIR and DIRD groups. I/R was performed for 120 min. The DIRD group received a single intraperitoneal dose of dexmedetomidine (100 µg/kg); the DIR group received no dexmedetomidine. Group DC was evaluated as the diabetic control group and also included six rats (C group) in which diabetes was not induced. These mice underwent only left thoracotomy and were closed without undergoing myocardial ischaemia. Histopathological changes, activities of catalase (CAT) and glutathione-S-transferase anti-oxidant enzymes, and malondialdehyde (MDA) levels were evaluated in the lung tissues of all rats.

RESULTS

Neutrophil infiltration/aggregation was higher in the DIR group than in the C, DC, and DIRD groups (p=0.001, p=0.013, and p=0.042, respectively). The lung injury score was significantly higher in the DIR group than in the C and DC groups (p<0.0001 and p=0.024, respectively). The levels of MDA were significantly higher in the DIR group than in the C and DIRD groups. CAT activity was significantly higher in the DIR group than in the DIRD and C groups.

CONCLUSION

Our results confirm that dexmedetomidine has protective effects against the lung damage resulting from I/R in diabetic rats. Future studies conducted to evaluate the effects of the use of dexmedetomidine on damage to various organs following different I/R durations may help understanding possible protective effects of dexmedetomidine and underlying mechanisms in tissue damage related to I/R injury.

Valproic acid attenuates acute lung injury induced by ischemia-reperfusion in rats

BACKGROUND

Evidence reveals that histone deacetylase (HDAC) inhibition has potential for the treatment of inflammatory diseases. The protective effect of HDAC inhibition involves multiple mechanisms. Heme oxygenase-1 (HO-1) is protective in lung injury as a key regulator of antioxidant response. The authors examined whether HDAC inhibition provided protection against ischemia-reperfusion (I/R) lung injury in rats by up-regulating HO-1 activity.

METHODS

Acute lung injury was induced by producing 40 min of ischemia followed by 60 min of reperfusion in isolated perfused rat lungs. The rats were randomly allotted to control group, I/R group, or I/R + valproic acid (VPA) group with or without an HO-1 activity inhibitor (zinc protoporphyrin IX) (n = 6 per group).

RESULTS

I/R caused significant increases in the lung edema, pulmonary arterial pressure, lung injury scores, tumor necrosis factor-α, and cytokine-induced neutrophil chemoattractant-1 concentrations in bronchoalveolar lavage fluid. Malondialdehyde levels, carbonyl contents, and myeloperoxidase-positive cells in lung tissue were also significantly increased. I/R stimulated the degradation of inhibitor of nuclear factor-κB-α, nuclear translocation of nuclear factor-κB, and up-regulation of HO-1 activity. Furthermore, I/R decreased B-cell lymphoma-2, heat shock protein 70, acetylated histone H3 protein expression, and increased the caspase-3 activity in the rat lungs. In contrast, VPA treatment significantly attenuated all the parameters of lung injury, oxidative stress, apoptosis, and inflammation. In addition, VPA treatment also enhanced HO-1 activity. Treatment with zinc protoporphyrin IX blocked the protective effect of VPA.

CONCLUSIONS

VPA protected against I/R-induced lung injury. The protective mechanism may be partly due to enhanced HO-1 activity following HDAC inhibition.

Brief Glutamine Pretreatment Increases Alveolar Macrophage CD163/Heme Oxygenase-1/p38-MAPK Dephosphorylation Pathway and Decreases Capillary Damage but Not Neutrophil Recruitment in IL-1/LPS-Insufflated Rats

Background

Glutamine (GLN) attenuates acute lung injury (ALI) but its effect on alveolar macrophages is unknown. We hypothesized that GLN pretreatment would induce the anti-inflammatory CD163/heme oxygenase (HO)-1/p38-MAPK dephosphorylation pathway in alveolar macrophages and reduce ALI in rats insufflated with interleukin-1 (IL-1) and lipopolysaccharide (LPS).

Methods

Male Sprague-Dawley rats were randomized to the following groups: GLN-IL-1/LPS-, GLN+IL-1/LPS-, GLN-IL-1/LPS+, and GLN+IL-1/LPS+. GLN pretreatment was given via gavage (1g/kg L-alanyl-L-glutamine) daily for 2 days. ALI was subsequently induced by insufflating 50ng IL-1 followed by 5mg/kg E.coli LPS. After 24h, bronchoalveolar lavage (BAL) protein, lactate dehydrogenase (LDH) and neutrophil concentrations were analyzed. BAL alveolar macrophage CD163+ expression, HO-1 and p38-MAPK concentrations were measured, as well as alveolar macrophage tumor necrosis factor (TNF)-α and interleukin (IL)-10 concentrations. Histology and immunofluorescence studies were also performed.

Results

Following IL-1/LPS insufflation, GLN pretreated rats had significantly decreased BAL protein and LDH concentrations, but not BAL neutrophil counts, compared to non-GLN pretreated rats. The number of alveolar macrophages and the number of CD163+ macrophages were significantly increased in GLN pretreated IL-1/LPS-insufflated rats compared to non-GLN pretreated, IL-1/LPS-insufflated rats. GLN pretreatment before IL-1/LPS also significantly increased HO-1 concentrations and dephosphorylated p38-MAPK levels but not cytokine levels in alveolar macrophages. Immunofluorescence localized CD163 and HO-1 in alveolar macrophages.

Conclusion

Short-term GLN pretreatment activates the anti-inflammatory CD163/HO-1/p38-MAPK dephosphorylation pathway of alveolar macrophages and decreases capillary damage but not neutrophil recruitment in IL-1/LPS-insufflated rats.

Protection against reperfusion lung injury via aborgating multiple signaling cascades by trichostatin A

Trichostatin A (TSA) is a histone deacetylase inhibitor with anti-inflammatory effects. Nonetheless, little information is available about the effect of TSA in ischemia-reperfusion (IR)-induced lung injury. In a perfused rat lung model, IR was induced by 40min of ischemia followed by 60min of reperfusion. The rat lungs were randomly divided into several groups including control, control+TSA (0.1mg/kg), IR, and IR+various dosages of TSA (0.05, 0.075, 0.1mg/kg). Bronchoalveolar lavage fluids and lung tissues were obtained and examined at the end of the experiment. TSA dose-dependently diminished IR-induced increased vascular permeability and edema, pulmonary artery pressure, and histological changes in the lungs. Additionally, TSA suppressed lavage tumor necrosis factor-α and cytokine-induced neutrophil chemoattractant concentrations, cell infiltration, and myeloperoxidase-positive cells in the lung tissue. Furthermore, TSA attenuated the phosphorylation of extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase, degradation of the inhibitor of nuclear factor (NF)-κB, and nuclear NF-κB levels. TSA also decreased poly (ADP-ribose) polymerase but enhanced acetylated histone H3 acetylation, Bcl-2, and mitogen-activated protein kinase phosphatase-1 (MKP-1) expression in IR lung tissue. Therefore, TSA exerted a protective effect on IR-induced lung injury via increasing histone acetylation and MKP-1 protein expression, repressing NF-κB, mitogen-activated protein kinase, and apoptosis signaling pathways.

The protective effects of glutamine in a rat model of ventilator-induced lung injury

BACKGROUND

The mortality rate of patients with acute respiratory distress syndrome (ARDS) is still high despite the use of protective ventilatory strategies. We sought to examine the pharmacological effects of glutamine (GLN) in a two-hit model of endotoxin-induced inflammation followed by ventilator-induced lung injury (VILI). We hypothesized that the administration of GLN ameliorates the VILI.

METHODS

Sprague-Dawley rats were anesthetized and given lipopolysaccharide (LPS) intratracheally as a first hit to induce lung inflammation, followed 24 h later by a second hit of mechanical ventilation (MV) with either low tidal volume (6 mL/kg) with 5 cmH2O of positive end-expiratory pressure (PEEP) or high tidal volume (22 mL/kg) with zero PEEP for 4 h. GLN or lactated Ringer's solution as the placebo was administered intravenously 15 min prior to MV.

RESULTS

In the LPS-challenged rats ventilated with high tidal volume, the treatment with GLN improved lung injury indices, lung mechanics and cytokine responses compared with the placebo group.

CONCLUSIONS

The administration of GLN given immediately prior to MV may be beneficial in the context of reducing VILI.

The effect of levosimendan on lung damage after myocardial ischemia reperfusion in rats in which experimental diabetes was induced

BACKGROUND

It is known that diabetic complications and lipid peroxidation are closely associated. During ischemia and reperfusion (IR), injury may occur in distant organs, as well as in tissues next to the region exposed to the ischemia, and the lungs can be one of the most affected of these organs. Therefore, this study investigated the effects of levosimendan on lung tissue and the oxidant-antioxidant system in diabetic rats.

MATERIALS AND METHODS

The study was conducted in 24 Wistar albino rats that were separated into four groups (C, control; DC, diabetic control; DIR, diabetic IR; and DIRL, diabetic IR levosimendan). Diabetes was induced in 18 rats using streptozotocin (55 mg/kg), and the animals were randomly separated into three groups after the effects of the diabetes became apparent. After a left thoracotomy, ischemia was performed on the myocardial muscle with the left main coronary artery (LAD) for 30 min in the DIR and DIRL groups. After ischemia, the LAD ligation was removed, and reperfusion was applied for 120 min. Single-dose intraperitoneal 12 μg/kg levosimendan was administered to group DIRL before the ischemia. Group DC was evaluated as the diabetic control group, and six rats were considered to be the control group (group C), in which thoracotomy was performed and then closed with no induction of myocardial ischemia. We measured the levels of malondialdehyde, as a lipid peroxidation end product, as well as catalase and glutathione S-transferase activities, as antioxidant enzymes in the lung tissue. Tissue samples were also examined histopathologically.

RESULTS

Neutrophil infiltration or aggregation in lung tissue was significantly higher in the DIR group compared with the C, DC, and DIRL groups (P = 0.003, P = 0.026, and P = 0.026, respectively). Alveolar wall thickening in lung tissue was significantly higher in the DIR group compared with the C, DC, and DIRL groups (P = 0.002, P = 0.002, and P = 0.006, respectively). In addition, the lung tissue damage score was significantly higher in the DIR group compared with the C, DC, and DIRL groups (P = 0.001, P = 0.004, and P = 0.007, respectively). Finally, catalase and glutathione S-transferase activity levels were significantly higher in the DIR group compared with those observed in the C, DC, and DIRL groups.

CONCLUSIONS

Although diabetes increases lipid peroxidation, it suppresses antioxidant activity. Our results showed that levosimendan had a protective effect against lung damage secondary to IR in the rats with induced diabetes. We recommend that experimental and clinical studies be conducted to examine the effects of levosimendan at different doses and different IR durations on various organs for clinical use.

Glutamine attenuates acute lung injury caused by acid aspiration

Inadequate ventilator settings may cause overwhelming inflammatory responses associated with ventilator-induced lung injury (VILI) in patients with acute respiratory distress syndrome (ARDS). Here, we examined potential benefits of glutamine (GLN) on a two-hit model for VILI after acid aspiration-induced lung injury in rats. Rats were intratracheally challenged with hydrochloric acid as a first hit to induce lung inflammation, then randomly received intravenous GLN or lactated Ringer's solution (vehicle control) thirty min before different ventilator strategies. Rats were then randomized to receive mechanical ventilation as a second hit with a high tidal volume (TV) of 15 mL/kg and zero positive end-expiratory pressure (PEEP) or a low TV of 6 mL/kg with PEEP of 5 cm H2O. We evaluated lung oxygenation, inflammation, mechanics, and histology. After ventilator use for 4 h, high TV resulted in greater lung injury physiologic and biologic indices. Compared with vehicle treated rats, GLN administration attenuated lung injury, with improved oxygenation and static compliance, and decreased respiratory elastance, lung edema, extended lung destruction (lung injury scores and lung histology), neutrophil recruitment in the lung, and cytokine production. Thus, GLN administration improved the physiologic and biologic profiles of this experimental model of VILI based on the two-hit theory.

How wasting is saving: weight loss at altitude might result from an evolutionary adaptation

At extreme altitude (>5,000 – 5,500 m), sustained hypoxia threatens human function and survival, and is associated with marked involuntary weight loss (cachexia). This seems to be a coordinated response: appetite and protein synthesis are suppressed, and muscle catabolism promoted. We hypothesise that, rather than simply being pathophysiological dysregulation, this cachexia is protective. Ketone bodies, synthesised during relative starvation, protect tissues such as the brain from reduced oxygen availability by mechanisms including the reduced generation of reactive oxygen species, improved mitochondrial efficiency and activation of the ATP-sensitive potassium (K_ATP) channel. Amino acids released from skeletal muscle also protect cells from hypoxia, and may interact synergistically with ketones to offer added protection. We thus propose that weight loss in hypoxia is an adaptive response: the amino acids and ketone bodies made available act not only as metabolic substrates, but as metabolic modulators, protecting cells from the hypoxic challenge.

Protective effect of hypercapnic acidosis in ischemia-reperfusion lung injury is attributable to upregulation of heme oxygenase-1

Hypercapnic acidosis (HCA) has protective effects in animal models of acute lung injury, but the mechanism underlying the effect of HCA is unclear. Heme oxygenase-1 (HO-1) is an antioxidant enzyme that protects tissue from inflammation injury. We investigated whether HO-1 contributes to the protective effects of HCA in ischemia-reperfusion (IR)-induced lung injury. Typical acute lung injury in rats was successfully induced by 40 min of ischemia and 90 min of reperfusion in an isolated perfused lung model. The rat lungs were randomly assigned to the control group, IR group or IR + HCA group with or without zinc protoporphyrin IX (ZnPP), an HO-1 activity inhibitor. At the end of the experiment, bronchoalveolar lavage fluid (BALF) and lung tissues were collected to evaluate the degree of lung injury. In in vitro experiments, HO-1 siRNA transfected A549 cells were exposed to a normoxic or hypoxia-reoxygenation (H/R) environment in the presence or absence of HCA. IR caused significant increases in the pulmonary arterial pressure, lung weight to body weight and wet/dry ratios, lung weight gain, capillary filtration coefficient, lung injury scores, neutrophil infiltration, and concentrations of protein and TNF-α in the BALF. IR also induced degradation of inhibitor of nuclear factor (NF)-κB-α, increased IκB kinase (IKK)-β phosphorylation and nuclear translocation of NF-κB, and up-regulated HO-1 expression and activity. Furthermore, IR decreased Bcl-2 protein expression and increased the number of active caspase-3 stained cells. HCA treatment enhanced HO-1 expression and activity, and accordingly reduced IKK-NF-κB signaling, inhibited apoptosis, and significantly attenuated IR-induced changes. Treatment with ZnPP partially blocked the protective effect of HCA. In addition, HO-1 siRNA significantly reversed HCA-mediated inhibition of NF-κB signaling in A549 cells subjected to H/R. In conclusion, the protective effect of HCA in IR lung injury in rats was mediated in part by the anti-inflammatory and anti-apoptotic action of HO-1.

The therapeutic efficacy of glutamine for rats with smoking inhalation injury

Smoke inhalation injury represents a major cause of mortality in burn patients and is associated with a high incidence of pulmonary complications. Glutamine (GLN) is considered a conditionally essential amino acid during critical illness and injury. However, whether GLN could attenuate lung injury caused by smoke inhalation is still unknown. The purpose of this study is to investigate whether GLN has a beneficial effect on smoke inhalation induced lung injury. In our present work, rats were equally randomized into three groups: Sham group (ambient air inhalation plus GLN treatment), Control group (smoke inhalation plus physiological saline) and GLN treatment group (smoke inhalation injury plus GLN treatment). At sampling, bronchoalveolar lavage fluid was performed to determine total protein concentration and pro-inflammatory cytokine levels. Lung tissues were collected for wet/dry ratio, histopathology, hydroxyproline and Western blotting measurement. Our results exhibited that GLN attenuated the lung histopathological alterations, improved pulmonary oxygenation, and mitigated pulmonary edema. At 28days post-injury, GLN mitigated smoke inhalation-induced excessive collagen deposition as evidence by Masson-Goldner trichrome staining and hydroxyproline content. GLN mitigated smoke inhalation-induced lung inflammatory response, and further prevented the activity of NF-kappa-B. More importantly, results from Western blotting and Immunohistochemistry exhibited that GLN enhanced the expression of HSF-1, HSP-70 and HO-1 in lung tissues. Our data demonstrated that GLN protected rats against smoke inhalation-induced lung injury and its protective mechanism seems to involve in inhibition inflammatory response and enhancing HSP expression.

When is injury potentially reversible in a lung ischemia-reperfusion model?

OBJECTIVE

To verify the impact of ischemic time on lung cell viability in an experimental model of lung ischemia-reperfusion (IR) injury and its repercussion on lung performance after reperfusion.

METHODS

Twenty-four animals were subjected to selective clamping of the left pulmonary artery and divided into four groups (n = 6) according to ischemic time: 15 (IR15), 30 (IR30), 45 (IR45), and 60 min (IR60). All animals were observed for 120 min after reperfusion. The hemodynamics, arterial blood gases measurements, and histologic changes were analyzed. Immunofluorescence assays for caspase 3 and annexin V were performed. Lipid peroxidation was assessed by thiobarbituric acid-reactive substances, and caspase 3 activity was assessed by colorimetric extract.

RESULTS

The partial pressure of arterial oxygen significantly decreased at the end of the observation period in the IR30, IR45, and IR60 groups (P < 0.05). The final mean arterial pressure significantly decreased in the IR60 group (P < 0.05). We observed a significant increase in caspase 3 activity and caspase 3-positive cells by immunofluorescence in the IR45 group compared with the other groups (P < 0.05). Additionally, there was an increase in necrotic cells assessed by annexin V in the IR60 group. The histologic score did not show differences among the different groups.

CONCLUSIONS

The degree of cell damage had a negative impact on lung performance. Sixty minutes of lung ischemia and posterior reperfusion resulted in an increased number of necrotic cells, suggesting that these cells may not be able to reverse the effects of the IR injury because of the lack of viable cells.

Inducible cyclooxygenase expression mediating hypoxia/reoxygenation-induced pulmonary vasoconstriction is attenuated by a cyclooxygenase inhibitor in rats

OBJECTIVE

Hypoxic pulmonary vasoconstriction (HPV) is a well known phenomenon to temporarily offset a ventilation-perfusion mismatch. Sustained HPV may lead to pulmonary hypertension. In this protocol, we studied the relationships between the HPV response and inducible cyclooxygenase II (COX II) activation after hypoxia-reoxygenation (H-R) challenge in an isolated perfused lung model.

METHODS

An in situ isolated perfused rat lung model underwent inaction of hypoxia by ventilation with 5% CO(2)-95% N(2) for 10 minutes instead of 5% CO(2)-95% air; they were then reoxygenated with 5% CO(2)-95% air. We measured pulmonary arterial pressure (PAP) changes before, during, and after H-R challenge. We also estimated changes in blood concentrations of hydroxyl radicals, nitric oxide (NO) and thromboxane B(2) (TxB(2)) before and after H-R as well as mRNA expressions of COX II in lung tissue thereafter. A COX II inhibitor, celecoxib (10 mg/kg), was administered between 2 consecutive challenges.

RESULTS

Hypoxia induced pulmonary vasoconstriction by increasing PAP (4.1 ± 0.8 mm Hg). Consecutive hypoxic challenges did not show tachyphylaxis (P > .05). H-R of lung tissues induced significant increases in blood concentrations of hydroxyl radicals (48.5 ± 7.6 vs 75.8 ± 11.5 mmol/L; P < .01), NO (54.3 ± 12.3 vs 77.7 ± 15.7 pmol; P < .05), and TxB(2) (42.3 ± 6.9 vs 58.7 ± 8.6 pg/mL; P < .05). Lung tissue H-R also significantly increased COX II mRNA expression compared with sham tissues (1 ± 0 vs 4.0 ± 2.8; P < .001). The COX II inhibitor celecoxib significantly attenuated HPV responses (P < .05) and attenuated the elevated blood concentrations of TxB(2) (P < .05), hydroxyl radicals (P < .01), nitric oxide (P < .05), and COX II mRNA expression (P < .05) after H-R challenge.

CONCLUSIONS

Lung tissue H-R induced significant increases blood concentrations of inflammatory mediators and tissue mRNA expression of COX related to elevation of HPV responses. COX II inhibitor celecoxib attenuated the HPV responses by reducing TxB(2) release.