Inhibition of Na-K-Cl cotransporter isoform 1 reduces lung injury induced by ischemia–reperfusion

Objectives

Ischemia–reperfusion acute lung injury is characterized by increased vascular permeability, lung edema, and neutrophil sequestration. Ischemia–reperfusion acute lung injury occurs in lung transplantation and other major surgical procedures. Effective regulation of alveolar fluid balance is critical for pulmonary edema. Sodium-potassium-chloride co-transporter regulates alveolar fluid and is associated with inflammation. We hypothesized that sodium-potassium-chloride co-transporter is important in ischemia–reperfusion acute lung injury. Bumetanide, a sodium-potassium-chloride co-transporter inhibitor, is used to treat pulmonary edema clinically. We studied the effect of bumetanide in ischemia–reperfusion acute lung injury.

Protective effects of pretreatment with Radix Paeoniae Rubra on acute lung injury induced by intestinal ischemia/reperfusion in rats

Objective： To investigate the effect of pretreatment with Radix Paeoniae Rubra （RPR） on acute lung injury induced by intestinal ischemia/reperfusion in rats and its protective mechanism.
Methods： Thirty-two Wistar rats were randomly divided into four groups： Sham-operation group, ischemla/ reperfusion group （I/R group ）, RPR-pretreatment group and hemin group. The model of intestinal ischemia/ reperfusion was established by clamping the superior mesenteric artery for 1 hour followed by 2-hour reperfusion. The effect of RPR on the expression of heme oxygenase-1 （HO-1） in lung tissues was detected by immunohistochemistry and morphometry computer image analysis. Arterial blood gas analysis, lung permeability index, malondialdehyde （MDA） and superoxide dismutase （SOD） contents in lungs were measured. The histological changes of lung tissue were observed under light microscope.
Resalts： The expression of HO-1 in RPR-pretreatment group and hemin group was obviously higher than that in sham-operation group and I/R group （ P 〈 0.01 ）. The level of MDA and lung permeability index in RPR-pretreatment and hemin group were significantly lower than those in I/R group （P〈0.01 or P〈0.05）, while the activity of SOD in RPR-pretreatment and hemin group was obviously higher than that in I/R group （P〈0.01）. Under light microscope, the pathologic changes induced by I/R were significantly attenuated by RPR.
Conclusion： Intestinal ischemia/reperfusion may result in acute lung injury and pretreatment with RPR injection can attenuate the injury. The protective effect of RPR on the acute lung injury is related to its property of inducing HO-1 expression and inhibiting lipid peroxidation.     

The interaction between oxidative stress and mast cell activation plays a role in acute lung injuries induced by intestinal ischemia–reperfusion

Background

Both oxidative stress and mast cells are involved in acute lung injuries (ALIs) that are induced by intestinal ischemia–reperfusion (IIR). The aim of this study was to further investigate the interaction between oxidative stress and mast cells during the process of IIR-induced ALI.

Materials and methods

Thirty adult Sprague–Dawley rats were randomly divided into five groups: sham, IIR, IIR + compound 48/80 (CP), N-acetylcysteine (NAC) + IIR, and NAC + IIR + CP. All rats except those in the sham group were subjected to 75 min of superior mesenteric artery occlusion, followed by 2 h of reperfusion. The rats in the NAC + IIR and NAC + IIR + CP groups were injected intraperitoneally with NAC (0.5 g/kg) for three successive days before undergoing IIR. The rats in the IIR + CP and NAC + IIR + CP groups were treated with CP (0.75 mg/kg), which was administered intravenously 5 min before the reperfusion. At the end of the experiment, lung tissue was obtained for pathologic and biochemical assays.

Results

IIR resulted in ALI, which was detected by elevated pathology scores, a higher lung wet-to-dry ratio, and decreased expression of prosurfactant protein C (P < 0.05). Concomitant elevations were observed in the expression levels of the nicotinamide adenine dinucleotide phosphate oxidase subunits p47^phox and gp91^phox and the levels of hydrogen peroxide and malondialdehyde. However, superoxide dismutase activity in the lung was reduced (P < 0.05). The level of interleukin 6, the activity of myeloperoxidase, and the expression of intercellular adhesion molecule 1 were also increased in the lung. IIR led to pulmonary mast cell degranulation and increases in the plasma and pulmonary β-hexosaminidase levels, mast cell counts, and tryptase expression in lung tissue. CP aggravated these conditions, altering the measurements further, whereas NAC attenuated the IIR-induced ALI and all biochemical changes (P < 0.05). However, CP abolished some of the protective effects of NAC.

Conclusions

Oxidative stress and mast cells interact with each other and promote IIR-induced ALI.     

Hydrogen sulfide attenuates lung ischemia–reperfusion injury through SIRT3-dependent regulation of mitochondrial function in type 2 diabetic rats

BackgroundLung ischemia–reperfusion injury is a complex pathophysiologic process associated with high morbidity and mortality. We have demonstrated elsewhere that diabetes mellitus aggravated ischemia-induced lung injury. Oxidative stress and mitochondrial dysfunction are drivers of diabetic lung ischemia-reperfusion injury; however, the pathways that mediate these events are unexplored. In this study using a high-fat diet–fed model of streptozotocin-induced type 2 diabetes in rats, we determined the effect of hydrogen sulfide on lung ischemia-reperfusion injury with a focus on Sirtuin3 signaling.MethodsRats with type 2 diabetes were exposed to GYY4137, a slow release donor of hydrogen sulfide with or without administration of the Sirtuin3 short hairpin ribonucleic acid plasmid, and then subjected to a surgical model of ischemia–reperfusion injury of the lung (n = 8). Lung function, oxidative stress, inflammation, cell apoptosis, and mitochondrial function were measured.ResultsCompared with nondiabetic rats, animals with type 2 diabetes at baseline exhibited significantly decreased Sirtuin3 signaling in lung tissue and increased oxidative stress, apoptosis, inflammation, and mitochondrial dysfunction (P < .05 each). In addition, further impairment in Sirtuin3 signaling was found in diabetic rats subjected to this model of lung ischemia–reperfusion. Simultaneously, the indexes showed further aggravation. Treatment with hydrogen sulfide restored Sirtuin3 expression and decreased lung ischemia–reperfusion injury in animals with type 2 diabetes mellitus by improving lung functional recovery, decreasing oxidative damage, suppressing inflammation, ameliorating cell apoptosis, and preserving mitochondrial function (P < .05). Conversely, these protective effects were largely reversed in Sirtuin3 knockdown rats.ConclusionImpaired lung Sirtuin3 signaling associated with type 2 diabetic conditions was further attenuated by an ischemia-reperfusion insult. Hydrogen sulfide ameliorated reperfusion-induced oxidative stress and mitochondrial dysfunction via activation of Sirtuin3 signaling, thereby decreasing lung ischemia-reperfusion damage in rats with a model of type II diabetes.     

Dexmedetomidine protects against lung ischemia–reperfusion injury by the PI3K/Akt/HIF-1α signaling pathway

Purpose

To evaluate the role of the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway in the protection by dexmedetomidine against lung ischemia–reperfusion injury (IRI) in rats.

Methods

Forty-eight male Sprague–Dawley rats weighing 250–350 g were randomly divided into six groups (n = 8 each group): sham group, IRI group, low-dose dexmedetomidine group (LD group), high-dose dexmedetomidine group (HD group), combined low-dose dexmedetomidine and LY294002 group (LDL group), and combined high-dose dexmedetomidine and LY294002 group (HDL group). A 30-min ischemia was induced by occluding the hilum of the left lung, followed by a 120-min reperfusion by removing occlusion of the hilum. After the left lung was removed, the wet/dry weight ratio (W/D) of the lung tissues was determined. Pathological changes of lung tissues were evaluated by light and electron microscopes and the expression of p-Akt and HIF-1α in the lung tissues was determined by western blotting.

Results

Compared with the sham group, both the W/D ratio and lung injury were significantly increased, the p-Akt expression was down-regulated and HIF-1α expression was up-regulated in the five experimental groups. Compared with the LD and LDL groups, both the W/D ratio and lung injury were decreased, but the expression of p-Akt and HIF-1α was increased in the HD and HDL groups.

Conclusions

Administration of dexmedetomidine before ischemia can provide a protection against lung IRI by re-installing the PI3K/Akt/HIF-1α signaling pathway.

     

The interaction between Toll-like receptor 4 signaling pathway and hypoxia-inducible factor 1α in lung ischemia–reperfusion injury

Background

Lung ischemia–reperfusion injury (LIRI) is the life-threatening complication occurring after lung transplantation. Toll-like receptor 4 (TLR4) signaling pathway and hypoxia-inducible factor-1α (HIF-1α) are intimately involved in the development and progression of various inflammatory and hypoxia diseases; however, the relationship of them in LIRI in vivo is still far from clear.

Materials and methods

Forty-five Sprague–Dawley rats were randomly distributed in nine groups: (1) Sham group, (2) LIRI group, (3) LIRI + saline control group, (4) LIRI + dimethyl Sulfoxide control group, (5) LIRI + lipopolysaccharide group, (6) LIRI + TAK-242 group (TAK-242 is a TLR4 inhibitor, ethyl (6R)-6- [N-(2-chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate), (7) LIRI + thioredoxin group (thioredoxin is an apoptosis signal–regulating kinase 1 (ASK1) inhibitor), (8) LIRI + SB203580 group (SB203580 is a p38 inhibitor), and (9) LIRI + chetomin group (chetomin is a HIF-1α inhibitor). The interaction between TLR4 signaling pathway (including TLR4, myeloid differentiation primary response gene 88 (MyD88), TIR-domain-containing adapter-inducing interferon-β (TRIF), ASK1, and p38) and HIF-1α and the role of TLR4-dependent HIF-1α were analyzed.

Results

In LIRI, HIF-1α accumulation was induced in a TLR4-dependent fashion, and MyD88, but not TRIF, and activation of ASK1 and p38 were found to be critical for TLR4-mediated HIF-1α accumulation. HIF-1α protein played a critical role in TLR4-mediated lung injury of LIRI (including inflammation, cell apoptosis, and lung damage). HIF-1α protein upregulated TLR4 expression of LIRI in a positive feedback manner.

Conclusions

We identify that the TLR4-HIF-1 loop may be existed in LIRI. Therefore, we suggest that the interaction between them may represent a novel therapeutic target for the development of novel target-based therapies of LIRI.     

Salvianolic acid B attenuates spinal cord ischemia-reperfusion–induced neuronal injury and oxidative stress by activating the extracellular signal–regulated kinase pathway in rats

Background

Salvianolic acid B (SalB), the main bioactive compound isolated from the traditional Chinese medicinal herb broad Radix Salviae Miltiorrhizae exerts a spectrum of pharmacologic activities. We investigated the effects of SalB treatment in a rat model of spinal cord ischemia and reperfusion (I/R) injury and the underlying mechanism.

Materials and methods

SalB was administered at 1, 10, or 50 mg/kg after spinal cord ischemia. The potential protective effects on spinal cord injury were determined by spinal cord edema, infarct volume, and motor function assessment of the hind limbs.

Results

SalB treatment significantly decreased spinal cord edema and infarct volume and preserved motor function of the hind limbs in a dose-dependent manner. SalB administration ameliorated the generation of oxidative products and preserved antioxidant defense activities in the injured spinal cord at both 4 and 24 h after I/R injury. Moreover, SalB prolonged the I/R injury–induced activation of extracellular signal–regulated kinase (ERK), and blocking ERK activation with PD98059 partially prevented the neuroprotective effects of SalB.

Conclusions

These findings demonstrate the neuroprotective effects of SalB in a spinal cord I/R injury model and suggest that SalB-induced neuroprotection was mediated by ERK activation.