Effects of simvastatin on lung injury induced by ischaemia-reperfusion of the hind limbs in rats

Effect of Selenium on Lung Injury Induced by Limb Ischemic Reperfusion Injury in Sprague-Dawley Rats

Purpose

: Ischemia-reperfusion injury (IRI) plays an important role in the pathophysiology of acute limb ischemia, leading to damage to distant organs, including the lungs. A complex mechanism is involved in the formation of reactive oxygen species (ROS), release of inflammatory mediators, and neutrophil activation. One strategy to reduce the damage is administering selenium, an antioxidant enzyme component that can bind ROS and protect cells. This study aimed to compare the degree of lung injury due to limb IRI in Sprague-Dawley (SD) rats with selenium administration versus those without selenium treatment.

Materials and Methods

: Fifteen male SD rats were divided into three groups: the control group (Group A), the ischemia-reperfusion with pre-reperfusion selenium (Group B), and the ischemia-reperfusion with post-reperfusion selenium (Group C). All animals underwent two hours of limb ischemia and three hours of reperfusion. Selenium was given intravenously at a dose of 0.2 mg/kg body weight. After reperfusion, lung specimens were histopathologically examined.

Results

: The median degree of lung injury was severe in Group A, mild in Group B, and moderate in Group C (P=0.01). Post hoc analysis revealed a significant difference in the degree of lung injury between Groups A and B (P=0.01), while a comparison between Groups A and C (P=0.06) and Groups B and C (P=0.31) revealed no significant difference.

Conclusion

: The administration of pre-reperfusion selenium significantly decreases lung injury induced by limb ischemia-reperfusion in SD rats.

Simvastatin Inhibits NLRP3 Inflammasome Activation and Ameliorates Lung Injury in Hyperoxia-Induced Bronchopulmonary Dysplasia via the KLF2-Mediated Mechanism

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly found in premature infants. Excessive inflammation and oxidative stress contribute to BPD occurrence and development. Simvastatin, as an inhibitor of HMG-CoA reductase, has been reported to have antioxidative and anti-inflammatory effects. However, its effect and possible mechanisms in hyperoxia-induced lung injury are rarely reported. In this study, in vivo and in vitro experiments were conducted to investigate whether simvastatin could ameliorate hyperoxia-induced lung injury and explore its potential mechanism. For the in vivo study, simvastatin could improve alveolar development after hyperoxic lung injury and reduce hyperoxic stress and inflammation. The in vitro study revealed that simvastatin can reduce inflammation in A549 cells after high-oxygen exposure. Simvastatin suppressed NLRP3 inflammasome activation and played anti-inflammatory and antioxidant roles by increasing KLF2 (Krüppel-like factor 2) expression. In vitro experiments also revealed that these effects of simvastatin were partially reversed by KLF2 shRNA, indicating that KLF2 was involved in simvastatin effects. In summary, our findings indicate that simvastatin could downregulate NLRP3 inflammasome activation and attenuate lung injury in hyperoxia-induced bronchopulmonary dysplasia via KLF2-mediated mechanism.

Effect of Atorvastatin on PM10-induced Cytokine Production by Human Alveolar Macrophages and Bronchial Epithelial Cells

Exposure to ambient air pollution particles (PM10) has been associated with increased cardiovascular morbidity and mortality. Inhaled pollutants induce a pulmonary and systemic inflammatory response that is thought to exacerbate cardiovascular disease. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have been shown to have anti-inflammatory effects that could contribute to their beneficial effect in cardiovascular disease. The aim of this study is to determine the effects of statins on PM10-induced cytokine production in human bronchial epithelial cells (HBECs) and alveolar macrophages (AMs). Primary HBECs and AMs are obtained from resected human lung. Cells are pretreated with different concentrations of atorvastatin for 24 hours and then exposed to 100 μg/mL urban air pollution particles (EHC-93). Cytokine levels (interleukin-1β, interleukin-8, granulocyte-macrophage colonystimulating factor, interleukin-6, and tumor necrosis factor-α) are measured at messenger RNA and protein levels using real-time polymerase chain reaction and bead-based multiplex immunoassay, respectively. PM10 exposure increases production of these cytokines by both cell types. Atorvastatin attenuates PM10-induced messenger RNA expression and cytokine production by AMs but not by HBECs. It is concluded that statins can modulate the PM10-induced inflammatory response in the lung by reducing mediator production by AMs.

Evaluation of the Effects of Atorvastatin and Ischemic Postconditioning Preventing on the Ischemia and Reperfusion Injury: Experimental Study in Rats

INTRODUCTION

Reperfusion injury leads to systemic morphological and functional pathological alterations. Some techniques are already estabilished to attenuate the damage induced by reperfusion. Ischemic preconditioning is one of the standard procedures. In the last 20 years, several experimental trials demonstrated that the ischemic postconditioning presents similar effectiveness. Recently experimental trials demonstrated that statins could be used as pharmacological preconditioning.

METHODS

41 Wistar rats (Rattus norvegicus albinus) were distributed in 5 groups: Ischemia and Reperfusion (A), Ischemic Postconditioning (B), Statin (C), Ischemic Postconditioning + Statins (D) and SHAM (E). After euthanasia, lungs, liver, kidneys and ileum were resected and submitted to histopathological analysis.

RESULTS

The average of lung parenchymal injury was A=3.6, B=1.6, C=1.2, D=1.2, E=1 (P=0.0029). The average of liver parenchymal injury was A=3, B=1.5, C=1.2, D=1.2, E = 0 (P<0.0001). The average of renal parenchymal injury was A=4, B=2.44, C=1.22, D=1.11, E=1 (P<0.0001). The average of intestinal parenchymal injury was A=2, B=0.66, C=0, D=0, E=0 (P=0.0006). The results were submitted to statistics applying Kruskal-Wallis test, estabilishing level of significance P<0.05.

CONCLUSION

Groups submitted to ischemic postconditioning, to pre-treatment with statins and both methods associated demonstrated less remote reperfusion injuries, compared to the group submitted to ischemia and reperfusion without protection.

Could simvastatin be considered as a potential therapy for chronic lung diseases? A debate on the pros and cons

INTRODUCTION

Simvastatin (SV) is a drug from the statin class, currently used orally as an anti-cholesterolemic drug. It inhibits the 3-hydroxy-3-methyl-glutaryl-Coenzyme A (HMG-CoA) reductase to reduce cholesterol synthesis. Recently, it has been found that SV also has several other protective pharmacological actions unrelated to its anti-cholesterol effects that might be beneficial in the treatment of chronic airway diseases.

AREAS COVERED

This review summarizes the evidence relating to SV as a potential anti-inflammatory, anti-oxidant and muco-inhibitory agent, administered both orally and via pulmonary inhalation, and discusses its pro and cons. Evidence could potentially be used to support the delivery of SV as inhaled formulation for the treatment of chronic respiratory diseases.

EXPERT OPINION

The use of SV as anti-inflammatory, anti-oxidant and muco-inhibitory agent for drug delivery to the lung is promising. Inhaled SV formulations could allow the delivery profile to be customized and optimized to take advantage of the rapid onset of action, low systemic side effect and improved physico-chemical stability. This treatment could potentially to be used clinically for the localized treatment of lung diseases where inflammation and oxidative stress production is present.

Simvastatin inhibits smoke-induced airway epithelial injury: implications for COPD therapy

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death. The statin drugs may have therapeutic potential in respiratory diseases such as COPD, but whether they prevent bronchial epithelial injury is unknown. We hypothesised that simvastatin attenuates acute tobacco smoke-induced neutrophilic lung inflammation and airway epithelial injury. Spontaneously hypertensive rats were given simvastatin (20 mg·kg(-1) i.p.) daily for either 7 days prior to tobacco smoke exposure and during 3 days of smoke exposure, or only during tobacco smoke exposure. Pretreatment with simvastatin prior to and continued throughout smoke exposure reduced the total influx of leukocytes, neutrophils and macrophages into the lung and airways. Simvastatin attenuated tobacco smoke-induced cellular infiltration into lung parenchymal and airway subepithelial and interstitial spaces. 1 week of simvastatin pretreatment almost completely prevented smoke-induced denudation of the airway epithelial layer, while simvastatin given only concurrently with the smoke exposure had no effect. Simvastatin may be a novel adjunctive therapy for smoke-induced lung diseases, such as COPD. Given the need for statin pretreatment there may be a critical process of conditioning that is necessary for statins' anti-inflammatory effects. Future work is needed to elucidate the mechanisms of this statin protective effect.

[Postconditioning can reduce long-term lung injury after lower limb ischemia-reperfusion]

INTRODUCTION

Operation on the infrarenal aorta could cause ischemic-reperfusion (IR) injury in local tissues and remote organs (e.g. the lung).

OBJECTIVES

Our aim was to reduce long-term lung damage, after lower limb IR with postconditioning.

MATERIALS AND METHODS

Male Wistar rats underwent 180 minutes of bilateral lower limb ischemia. Animals were divided into three groups: Sham-operated, IR, Postconditioned (PostC) and further to two subgroups according to reperfusion time: 24 h and 72 h. Serum free radical and IL-6 levels, histological changes, Wet/Dry (W/D) ratio, tissue myeloperoxidase (MPO) activity and Hsp72 levels were investigated.

RESULTS

Postconditioning can reduce histological changes in the lung. Free radical levels are significantly lower in PostC groups than in IR groups (42.9 ± 8.0 vs. 6.4 ± 3.4; 27.3 ± 4.4 vs. 8.3 ± 4.0 RLU%; p < 0.05). IL-6 level (238.4 ± 31.1 vs. 209.1 ± 18.8; 190.0 ± 8.8 vs. 187.0 ± 14.9 pg/ml) and Hsp72 expression did not show any significant difference. Compared to the IR group, lung MPO activity did not change in the PostC groups. W/D ratio in PostC groups is significantly lower at all measured time-points (68% vs. 65%; 72% vs. 68%; p < 0.05).

CONCLUSION

Postconditioning may reduce long-term damages of the lung after lower limb ischemic-reperfusion injury.

Pretreatment with atorvastatin attenuates lung injury caused by high-stretch mechanical ventilation in an isolated rabbit lung model

OBJECTIVE

We hypothesized that pretreatment with atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, confers protection against lung injury caused by high-stretch mechanical ventilation.

METHODS

Twenty-four isolated sets of normal rabbit lungs were utilized. Treated animals received atorvastatin (20 mg/kg body weight/day by mouth) for 3 days before surgery. Lungs were perfused constantly (300 mL/min) and ventilated for 1 hr with pressure-control ventilation at either 23 (high pressure; resulting in tidal volume approximately 22 mL/kg) or 11 (low pressure; tidal volume approximately 10 mL/kg) cm H2O peak inspiratory pressure and positive end-expiratory pressure of 3 cm H2O. Four groups were examined: high pressure-no statin, high pressure-statin pretreatment, low pressure-no statin, and low pressure-statin pretreatment.

RESULTS

The high-pressure-no statin group sustained more damage than the low-pressure groups. In high-pressure groups, lungs of statin-pretreated vs. no statin-pretreated animals sustained a significantly lower increase in ultrafiltration coefficient (an accurate marker of alveolar capillary permeability; high-pressure-statin pretreatment vs. high-pressure-no statin, -0.013 +/- 0.017 g/min/mm Hg/100g vs. 1.723 +/- 0.495 g/min/mm Hg/100g; p < .001), lower weight gain (i.e., less edema formation; 4.62 +/- 1.50 grams vs. 17.75 +/- 4.71 grams; p = .005), improved hemodynamics (i.e., lower increase in mean pulmonary artery pressure; 0.56 +/- 0.51 mm Hg vs. 5.62 +/- 1.52 mm Hg; p = .04), lower protein concentration in bronchoalveolar lavage fluid (p < .001), and fewer histologic lesions (p = .013). Apoptosis of lung parenchyma cells was not different (p = .97). There was no difference between low-pressure-statin pretreatment and low-pressure-no statin groups regarding these outcomes.

CONCLUSION

In this model, atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, attenuates lung injury caused by high-stretch mechanical ventilation.

Simvastatin improves wound strength after intestinal anastomosis in the rat

BACKGROUND

Simvastatin is a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor commonly known as a cholesterol-lowering drug with additional pleiotropic effects. Also, it is demonstrated that it prevents postoperative peritoneal adhesions in rat. This study was designed to assess its effects on the healing process of colonic anastomosis.

METHODS

Thirty-two male Wistar albino rats were randomized into two groups and subjected to colonic anastomosis. The study group was treated with simvastatin and the control group received only tap water instead. The rats were killed 3 and 7 days postoperatively. Wound complications, intra-abdominal abscesses, and anastomotic leaks and stenosis were recorded. Four types of assessment were performed: bursting pressure, hydroxyproline content, histopathology, and biochemical analysis.

RESULTS

Compared to the control group, simvastatin-treated rats displayed a higher bursting pressure (p < 0.001) and anastomotic hydroxyproline content (p < 0.05). Simvastatin treatment leads to a significant decrease in malondealdehyde levels (p < 0.05) and increase in paraoxonase activity (p < 0.001) at both time points. Histopathological analysis revealed that simvastatin administration leads to a better anastomotic healing in terms of reepithelialization, decreased granuloma formation, reduced ischemic necrosis, and inflammatory infiltration to muscle layer.

CONCLUSION

Clinically relevant doses of simvastatin do not have a negative impact on colonic anastomosis but improve intestinal wound healing in rats.