Protective Effects of Levosimendan and Iloprost on Lung Injury Induced by Limb Ischemia-Reperfusion: A Rabbit Model

Therapeutic iloprost for the treatment of acute respiratory distress syndrome (ARDS) (the ThIlo trial): a prospective, randomized, multicenter phase II study

Background

Acute respiratory distress syndrome (ARDS) is caused by rapid-onset (within hours) acute inflammatory processes in lung tissue, and it is a life-threatening condition with high mortality. The treatment of ARDS to date is focused on the prevention of further iatrogenic damage of the lung rather than the treatment of the initial inflammatory process. Several preclinical studies have revealed a beneficial effect of iloprost on the control of pulmonary inflammation, and in a small number of patients with ARDS, iloprost treatment resulted in improved oxygenation. Therefore, we plan to conduct a large multicenter trial to evaluate the effect of iloprost on ARDS.

Methods

The Therapeutic Iloprost during ARDS trial (ThIlo trial) is a multicenter, randomized, single blinded, clinical phase II trial assessing the efficacy of inhaled iloprost for the prevention of the development and progression of ARDS in critically ill patients. One hundred fifty critically ill patients suffering from acute ARDS will be treated either by nebulized iloprost or NaCl 0.9% for 5 days. Blood samples will be drawn at defined time points to elucidate the serum levels of iloprost and inflammatory markers during treatment. Mechanical ventilation will be standardized. In follow-up visits at days 28 and 90 as well as 6 months after enrollment, functional status according to the Barthel Index and a health care-related questionnaire, and frailty (Vulnerable Elders Survey) will be evaluated. The primary endpoint is the improvement of oxygenation, defined as the ratio of PaO₂/FiO₂. Secondary endpoints include 90-day all-cause mortality, Sequential Organ Failure Assessment scores during the study period up to day 90, the duration of mechanical ventilation, the length of intensive care unit (ICU) stay, ventilator-associated pneumonia, delirium, ICU-acquired weakness, and discharge localization. The study will be conducted in three university ARDS centers in Germany.

Discussion

The results of the ThIlo trial will highlight the anti-inflammatory effect of iloprost on early inflammatory processes during ARDS, resulting in the improvement of outcome parameters in patients with ARDS.

Trial registration

EUDRA-CT: 2016-003168-37. Registered on 12 April 2017. ClinicalTrials.gov: NCT03111212. Registered on 4 June 2017.

Which Distant Organ is Most Affected by Lower Extremity Ischemia-Reperfusion?

BACKGROUND

It has been experimentally shown that reperfusion injury occurs in many remote organs after ischemia-reperfusion (I/R) of the lower extremity. However, which distant organ is affected more after I/R of the lower extremity has not been investigated. In this study, we investigate which remote organ is predominantly affected after lower extremity I/R.

METHODS

Twenty male Sprague-Dawley rats were randomly divided into 2 groups: sham (group 1) and lower extremity I/R (group 2). In group 2, 1 hr of ischemia of the left lower extremity was followed by 24 hr of reperfusion of the limb. After reperfusion, the lung, liver, kidney, heart, and small intestine tissues were harvested in both groups.

RESULTS

In the I/R group, the malondialdehyde levels were significantly higher in the heart and small intestine tissues than those in other tissues (P < 0.05). In addition, in the I/R group, the glutathione and glutathione peroxidase activities were also higher in the heart tissues than those in other tissues (P < 0.05). However, these results were not significant because the malondialdehyde, glutathione, and glutathione peroxidase levels of the heart tissues in the control group were higher than those of the other tissues. Therefore, no statistically significant difference was found between the tissues in terms of the histological damage score we created and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cell numbers.

CONCLUSIONS

There was no difference in the severity of reperfusion injury between the tissues we examined after lower extremity I/R. This suggests that every distal organ should be carefully monitored after lower extremity I/R.

Assessment of the effects of levosimendan and thymoquinone on lung injury after myocardial ischemia reperfusion in rats

AIM

The aim of this study was to investigate the effects of levosimendan and thymoquinone (TQ) on lung injury after myocardial ischemia/reperfusion (I/R).

MATERIALS AND METHODS

Twenty-four Wistar albino rats were included in the study. The animals were randomly assigned to 1 of 4 experimental groups. In Group C (control group), left anterior descending artery was not occluded or reperfused. Myocardial I/R was induced by ligation of the left anterior descending artery for 30 min, followed by 2 h of reperfusion in the I/R, I/R-levosimendan (24 µg/kg) (IRL) group, and I/R-thymoquinone (0.2 mL/kg) (IRTQ) group. Tissue samples taken from the lungs of rats were histochemically stained with H&E and immunohistochemically stained with p53, Bcl 2, Bax, and caspase 3 primer antibodies.

RESULTS

Increased expression of p53 and Bax was observed (4+), especially in the I/R group. In IRTQ and IRL groups, expression was also observed at various locations (2+, 3+). H&E staining revealed that that the lungs were severely damaged and the walls of the alveoli were too thick, the number of areas examined was increased during the evaluation. Caspase 3 expression was observed to be at an (1+, 2+) intensity that was usually weak and diffuse in multiple areas. Bcl 2 was not found to be expressed in any of the tissues. H&E staining revealed that that the lungs were severely damaged in the I/R group, with the walls of the channels and alveoli thickened and edematous, and also an intense inflammatory cell migration was observed. Immunohistochemical staining was more prominent in inflammatory areas and structures around the terminal bronchioles.

CONCLUSION

The findings in our study have shown that administration of levosimendan and TQ during I/R increases expression of caspase 3, p53, and Bax in lung tissue and has a protective effect on lung as distant organ. We suggest that findings of this study be elucidated with further large-scale clinical studies.

Levosimendan prevents bronchoconstriction and adverse respiratory tissue mechanical changes in rabbits

Levosimendan has a calcium-sensitizing effect in the myocardium and opens ATP-sensitive potassium channels (KATP) in vascular smooth muscle. Because airway smooth muscle also expresses KATP, we characterized the protective potential of levosimendan against increased airway and respiratory tissue resistances. Animals were administered levosimendan alone ( group L), levosimendan after pretreatment with a KATP channel blocker (glibenclamide, group LG), glibenclamide only ( group G), or solvent alone (dextrose, group C). Airway resistance (Raw), tissue damping, and elastance were determined by forced oscillations under baseline conditions and following provocation tests with intravenous methacholine (MCh). Cardiac output (CO) was assessed by transpulmonary thermodilution. The same sequence of measurements was then repeated during intravenous infusion of levosimendan in groups L and LG or glucose in groups G and C. Sham treatments in groups C and G had no effect on lung responsiveness. However, levosimendan treatment in group L elevated CO and inhibited the MCh-induced airway responses [Raw changes of 87.8 ± 83% (SD) vs. 24.4 ± 16% at 4 μg·kg−1·min−1 MCh, P < 0.001], and in G (35.2 ± 12.7 vs. 25.2 ± 12.9%, P < 0.05). The preventive affect of levosimendan against lung constriction vanished in the LG group. Levosimendan exerts a KATP-mediated potential to prevent bronchoconstriction and may prohibit adverse lung peripheral changes both in the small bronchi and the pulmonary parenchyma. The identification of a further pleiotropic property of levosimendan that is related to the pulmonary system is of particular importance for patients with decreased cardiorespiratory reserves for which simultaneous circulatory support is complemented with prevention of adverse respiratory events.

Levosimendan beyond inotropy and acute heart failure: Evidence of pleiotropic effects on the heart and other organs: An expert panel position paper

Levosimendan is a positive inotrope with vasodilating properties (inodilator) indicated for decompensated heart failure (HF) patients with low cardiac output. Accumulated evidence supports several pleiotropic effects of levosimendan beyond inotropy, the heart and decompensated HF. Those effects are not readily explained by cardiac function enhancement and seem to be related to additional properties of the drug such as anti-inflammatory, anti-oxidative and anti-apoptotic ones. Mechanistic and proof-of-concept studies are still required to clarify the underlying mechanisms involved, while properly designed clinical trials are warranted to translate preclinical or early-phase clinical data into more robust clinical evidence. The present position paper, derived by a panel of 35 experts in the field of cardiology, cardiac anesthesiology, intensive care medicine, cardiac physiology, and cardiovascular pharmacology from 22 European countries, compiles the existing evidence on the pleiotropic effects of levosimendan, identifies potential novel areas of clinical application and defines the corresponding gaps in evidence and the required research efforts to address those gaps.

Inhibition of reactive oxygen species downregulates the MAPK pathway in rat spinal cord after limb ischemia reperfusion injury

INTRODUCTION

We examined the activity of mitogen-activated protein kinase (MAPK) family members, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, in rats pinal cord after hind limb ischemia reperfusion (IR) and analyzed the role of reactive oxygen species (ROS) as mediators of MAPK signaling under these conditions.

METHODS

In experiment 1, hind limb IR rats were treated intraperitoneally with one of following agents at 30 min before reperfusion: allopurinol (4, 40 mg/kg), superoxide dismutase (SOD, 4000 U/kg), N-nitro-l-arginine methyl ester (l-NAME, 10 mg/kg), or SOD (4000 U/kg) + l-NAME (10 mg/kg). In experiment 2, 5,10,15,20-tetrakis (N-methyl-4'-pyridyl) porphyrinato iron (III) (FeTMPyP) was administered intraperitoneally (1, 3, or 10 mg/kg) 30 min before reperfusion. After 3 d reperfusion period, the spinal cord (L4-6) was harvested to investigate MAPK signaling activity.

RESULTS

In experiment 1, p-ERK and p-JNK levels were significantly higher in the IR group than sham group. Administration of allopurinol, SOD, l-NAME, or SOD + l-NAME significantly reduced the IR-induced increase in p-ERK and p-JNK levels. There were no significant differences in p-p38 levels. In experiment 2, FeTMPyP significantly reduced the IR-induced increase in p-ERK and p-JNK levels in a dose-dependent manner.

CONCLUSIONS

Activation of ERK and JNK in the spinal cord was induced by hind limb IR and was not accompanied by p38 activation. IR-induced MAPK phosphorylation was reduced by inhibition of superoxide, nitric oxide, and peroxynitrite, indicating that ROS produced by hind limb IR mediate the activation of these signaling pathways in the spinal cord, potentially affecting distant organs.

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.

The effect of sildenafil and udenafil on testicular damage following ischemia-reperfusion injury in rats

PURPOSE

Ischemia-reperfusion injury can cause testicular damage and phosphodiesterase inhibitors are reported to regulate antioxidant activity. We investigated the prevention of ipsilateral and contralateral testicular damage using 2 phosphodiesterase inhibitors after testicular detorsion in rats.

MATERIALS AND METHODS

A total of 28 adult male rats were randomly divided into 4 groups of 7 each, including group 1-sham operation, group 2-testicular torsion and detorsion, group 3- testicular torsion and detorsion with sildenafil administration before detorsion and group 4- testicular torsion and detorsion with udenafil administration before detorsion. Tissue levels of malondialdehyde, total sulfhydryl and nitrite were evaluated, and histopathological changes in the groups were examined.

RESULTS

Compared to group 1 significantly increased tissue malondialdehyde (p = 0.001), significantly decreased total sulfhydryl (p = 0.038) and insignificantly increased nitrite were found in group 2. Compared to group 2 malondialdehyde decreased significantly and total sulfhydryl increased significantly in groups 3 and 4. The decrease in nitrite was insignificant in the latter 2 groups. Histopathology revealed increased hemorrhage, congestion and edema in group 2 rats. The testicular injury score was lower in groups 3 and 4. In group 2 grades II to IV injury was detected while most specimens in treated groups showed grade II injury.

CONCLUSIONS

This study indicates that intraperitoneal administration of sildenafil and udenafil efficiently suppresses radical production while decreasing histological changes after testicular ischemia-reperfusion injury.

Piperphentonamine (PPTA) attenuated cerebral ischemia-induced memory deficits via neuroprotection associated with anti-apoptotic activity

The calcium sensitizers levosimendan and piperphentonamine hydrochloride (PPTA) are used as cardiovascular drugs for treatment of heart failure. Given that levosimendan has been reported to exhibit a neuroprotective profile in a model of traumatic brain injury, it was interesting to know whether PPTA, a new calcium sensitizer recently developed in China, exerts a similar effect. The objective of this study was to determine whether PPTA exhibited neuroprotective effects and whether these properties were associated with memory. Four-vessel occlusion (4-VO) was used to induce global cerebral ischemia/reperfusion injury in rats treated with or without PPTA (5, 10 mg/kg, i.p., 2 h after the onset of reperfusion and then once a day for 15 consecutive days). Memory was measured using the step-through passive avoidance test. Neurochemical changes were examined in rat PC12 cells treated with oxygen-glucose deprivation (OGD) for 4 h followed by reoxygenation (OGD-R) for 24 h, in the absence or presence of PPTA. In vehicle-treated animals, 4-VO for 10 min produced memory deficits, as demonstrated by decreased retention in step-through passive avoidance, and massive neuron loss in the hippocampal CA1 subregion. These effects were attenuated by PPTA. The results were consistent with those observed in PC12 cells. PPTA treatment increased cell viability, as indicated by MTT assay, inhibited apoptosis, and decreased extracellular lactate dehydrogenase levels in Na(2)S(2)O(4)-treated PC12 cells. These results provide novel demonstration for the ability of PPTA to attenuate cerebral ischemia-induced memory deficits via neuroprotection in the hippocampus. The neuroprotective effect of PPTA appears to be associated with its anti-apoptotic activity. PPTA has the therapeutic potential for ischemic stroke.

Protective effects of hyperbaric oxygen and iloprost on ischemia/reperfusion-induced lung injury in a rabbit model

Background

The role of multiorgan damage in the mortality caused by ischemic limb injury is still not clarified. The objective of this study was to examine the potential protective effects of hyperbaric oxygen (HBO) and iloprost (IL) therapy on lung damage induced by limb ischemia/reperfusion injury in a rabbit model, using both biochemical and histopathological aspects.

Methods

Forty New Zealand white rabbits were randomly allocated into one of five study groups: HBO group (single session of HBO treatment); IL group (25 ng/kg/min infusion of IL); HBO + IL group (both HBO and IL); Control group (0.9% saline only); and a sham group. Acute hind limb ischemia-reperfusion was established by clamping the abdominal aorta for 1 h. HBO treatment and IL infusion were administrated during 60 min of ischemia and 60 min of reperfusion period. Blood pH, partial pressure of oxygen, partial pressure of carbon dioxide and levels of bicarbonate, sodium, potassium, creatine kinase, lactate dehydrogenase, and tumor necrosis factor alpha were determined at the end of the reperfusion period. Malondialdehyde was measured in the plasma and lung as an indicator of free radicals. After sacrifice, left lungs were removed and histopathological examination determined the degree of lung injury.

Results

In the control group, blood partial pressure of oxygen and bicarbonate levels were significantly lower and creatine kinase, lactate dehydrogenase, malondialdehyde and tumor necrosis factor-α levels were significantly higher than those of the HBO group, IL group, HBO + IL group and sham group. Similarly, the malondialdehyde levels in the lung tissue and plasma levels were significantly lower in the treatment groups compared with the control group. The extent of lung injury according to the histological findings was significantly higher in the control group.

Conclusions

These results suggest that both HBO and IL therapies and their combination might be effectively used in the prevention of lung injury after ischemia/reperfusion injury of the lower extremities.

Affirmative effects of iloprost on apoptosis during ischemia-reperfusion injury in kidney as a distant organ

OBJECTIVE

Apoptosis and its regulatory mechanisms take part in renal ischemia-reperfusion (I/R) injury which can result in acute renal failure and the inhibition of the caspase is considered as a new therapeutic strategy. In this context, we investigated the antiapoptotic and cytoprotective effects of iloprost, a prostacyclin analog, in kidney as a distant organ.

METHODS

Wistar albino rats were randomized into five groups (n = 12 in each) as sham, ischemia, I/R, iloprost (10 μg kg(-1)), and I/R + iloprost (10 μg kg(-1)). A 4 h reperfusion procedure was carried out after 4 h of ischemia. Caspase-8 was evaluated for death receptor-induced pathways, whereas caspase-9 was evaluated for mitochondria-dependent pathways and caspase-3 was investigated for overall apoptosis. Superoxide dismutase (SOD) enzyme activity and nitrite content as an indicator of nitric oxide (NO) production were also analyzed in kidney tissues.

RESULTS

Caspases-3, -8, and -9 were all significantly elevated in both ischemia and I/R groups compared to the sham group; however, treatment with iloprost reduced caspases-3, -8, and -9. SOD enzyme activity was attenuated by iloprost when compared to ischemic rats. The different effects of NO were found which change according to the present situation in ischemia, I/R, and treatment with iloprost.

CONCLUSIONS

These findings suggested that iloprost prevents apoptosis in both receptor-induced and mitochondria-dependent pathways in renal I/R injury and it may be considered as a cytoprotective agent for apoptosis. Understanding the efficiency of iloprost on the pathways for cell death may lead to an opportunity in the therapeutic approach for renal I/R injury.