Protective Effect of Pentoxifylline on Volume-Induced Lung Injury in Newborn Piglets

Cyclic mechanical stretch-induced oxidative stress occurs via a NOX-dependent mechanism in type II alveolar epithelial cells

Cyclic mechanical stretching (CMS) of the alveolar epithelium is thought to contribute to alveolar epithelial injury through an increase in oxidative stress. The aim of this study was to investigate the mechanisms of CMS-induced oxidative stress in alveolar epithelial cells (AECs). A549 cells were subjected to CMS, and the levels of 8-isoprostane and 3-nytrotyrosine were measured. Twenty-four hours of CMS induced a significant increase in the levels of 8-isoprostane and 3-nytrotyrosine. Although CMS did not increase the xanthine oxidase activity or the mitochondrial production of reactive oxygen species, it upregulated the expression of nicotine adenine dinucleotide phosphate oxidase (NOX) 2, 4, 5 and DUOX2. The NOX inhibitors DPI and GKT137831 significantly attenuated CMS-induced oxidative stress. Furthermore, the measurement of annexin V/propidium iodide by flow cytometry showed that CMS induced late-phase apoptosis/necrosis, which was also attenuated by both DPI and GKT137831. These data suggest that CMS mainly induces oxidative stress, which may lead to cell injury by activating NOX in AECs.

Pentoxifylline for the prevention of bronchopulmonary dysplasia in preterm infants

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common complication in preterm infants. BPD is associated with poor long-term respiratory and neurodevelopmental outcome and increased mortality. The prophylactic use of agents that modulate inflammation such as pentoxifylline, a synthetic methylxanthine and phosphodiesterase inhibitor, may reduce the incidence of BPD.

OBJECTIVES

The primary objective of this review was to determine the effect of pentoxifylline on the incidence of BPD, death prior to 36 weeks postmenstrual age (PMA), and BPD or death prior to 36 weeks PMA in preterm neonates.

SEARCH METHODS

We searched the Cochrane Neonatal Review Group Specialized Register, CENTRAL (The Cochrane Library Issue 9, 2012), EMBASE (January 1974 to September 2012), PubMed (January 1966 to September 2012), and CINAHL (January 1982 to September 2012) in September 2012. We checked references and cross-references from identified studies. We handsearched abstracts from the proceedings of the Pediatric Academic Societies Meetings (from January 1990 to September 2012). We placed no restrictions on language.

SELECTION CRITERIA

Randomised or quasi-randomised clinical trials of systemic or nebulised pentoxifylline in preterm neonates less than 32 weeks gestational age or less than 1500 g birth weight, reporting on at least one outcome of interest, were eligible for inclusion in the review.

DATA COLLECTION AND ANALYSIS

We used the standard methods of the Cochrane Neonatal Review Group and The Cochrane Collaboration. Two review authors (SMS and SK) independently searched the literature as described above and selected studies. Any disagreements were resolved by discussion involving all review authors.

MAIN RESULTS

We identified one randomised clinical trial eligible for inclusion in this review. This study compared the use of nebulised pentoxifylline versus placebo for prevention of BPD in 100 preterm infants and was at high risk of bias due to lack of blinding of intervention and outcome assessors, and incomplete outcome data. There was no statistically significant effect of nebulised pentoxifylline versus placebo on individual outcomes of BPD at 36 weeks PMA or on death prior to 36 weeks PMA. There was no significant effect of nebulised pentoxifylline on intraventricular haemorrhage, periventricular leukomalacia, sepsis, or patent ductus arteriosus (PDA) requiring ligation. The study did not report any of the other secondary outcomes considered for this review. Reporting of adverse events was very limited and did not allow for reliable judgement on the incidence of such events. No long-term outcomes were reported.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine the safety and efficacy of pentoxifylline for prevention of BPD in preterm neonates. We encourage researchers to conduct clinical trials to confirm or refute the role of pentoxifylline for prevention of BPD in preterm neonates. These trials should report on clinically important outcomes and, ideally, on long-term neurodevelopmental outcome.

The role of genetic polymorphisms in antioxidant enzymes and potential antioxidant therapies in neonatal lung disease

SIGNIFICANCE

Oxidative stress is involved in the development of newborn lung diseases, such as bronchopulmonary dysplasia and persistent pulmonary hypertension of the newborn. The activity of antioxidant enzymes (AOEs), which is impaired as a result of prematurity and oxidative injury, may be further affected by specific genetic polymorphisms or an unfavorable combination of more of them.

RECENT ADVANCES

Genetic polymorphisms of superoxide dismutase and catalase were recently demonstrated to be protective or risk factors for the main complications of prematurity. A lot of research focused on the potential of different antioxidant strategies in the prevention and treatment of lung diseases of the newborn, providing promising results in experimental models.

CRITICAL ISSUES

The effect of different genetic polymorphisms on protein synthesis and activity has been poorly detailed in the newborn, hindering to derive conclusive results from the observed associations with adverse outcomes. Therapeutic strategies that aimed at enhancing the activity of AOEs were poorly studied in clinical settings and partially failed to produce clinical benefits.

FUTURE DIRECTIONS

The clarification of the effects of genetic polymorphisms on the proteomics of the newborn is mandatory, as well as the assessment of a larger number of polymorphisms with a possible correlation with adverse outcome. Moreover, antioxidant treatments should be carefully translated to clinical settings, after further details on optimal doses, administration techniques, and adverse effects are provided. Finally, the study of genetic polymorphisms could help select a specific high-risk population, who may particularly benefit from targeted antioxidant strategies.

Pentoxifylline and prevention of hyperoxia-induced lung -injury in neonatal rats

INTRODUCTION

Oxygen exposure plays an important role in the pathogenesis of bronchopulmonary dysplasia (BPD). The phosphodiesterase inhibitor pentoxifylline (PTX) has anti-inflammatory and antifibrotic effects in multiple organs. It was hypothesized that PTX would have a protective effect on hyperoxia-induced lung injury (HILI).

METHODS

Newborn Sprague-Dawley rats were exposed to >95% oxygen (O(2)) and injected subcutaneously with normal saline (NS) or PTX (75 mg/kg) twice a day for 9 d. NS-injected, room air-exposed pups were controls. At days 4 and 9, lung tissue was collected to assess edema, antioxidant enzyme (AOE) activities, and vascular endothelial growth factor (VEGF) expression. At day 9, pulmonary macrophage infiltration, vascularization, and alveolarization were also examined.

RESULTS

At day 9, treatment with PTX significantly increased survival from 54% to 88% during hyperoxia. Treatment with PTX significantly decreased lung edema and macrophage infiltration. PTX treatment increased lung AOE activities including those of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). Furthermore, PTX treatment also increased the gene expression of VEGF189 and VEGF165, increased VEGF protein expression, and improved pulmonary vascularization.

DISCUSSION

These data indicate that the reduced lung edema and inflammation, increased AOE activities, and improved vascularization may be responsible for the improved survival with PTX during hyperoxia. PTX may be a potential therapy in reducing some of the features of BPD in preterm newborns.

The effect of pentoxifylline on the pulmonary response to high tidal volume ventilation in rats

BACKGROUND

Volume-induced lung injury is associated with lung inflammation. Pentoxifylline inhibits cytokine release and modulates neutrophil function.

OBJECTIVE

To evaluate the efficacy of pentoxifylline in the attenuation of lung inflammation induced by high tidal volume ventilation.

DESIGN

Adult rats were randomly assigned to receive saline as placebo or pentoxifylline (100mg/kg over 30 min, followed by 50mg/kg/h) before and during 4h of high tidal volume ventilation (20 ml/kg). Bronchoalveolar fluid inflammatory mediators were measured at baseline and after 4h of ventilation. Lung tissue myeloperoxidase activity and wet/dry lung weight were assessed upon completion of the study.

RESULTS

Bronchoalveolar tumor necrosis factor-alpha (pentoxifylline vs. placebo; 192+/-61 vs. 543+/-99 pg/ml; p<0.007) and thromboxane B(2) (262+/-26 vs. 418+/-49 pg/ml; p<0.02) concentrations, lung myeloperoxidase activity (0.5+/-0.1 vs. 1.2+/-0.2U/mg; p<0.003) and wet/dry weight (6.1+/-0.2 vs. 7.1+/-0.3; p<0.01) were all significantly lower in the pentoxifylline-treated group.

CONCLUSION

Pentoxifylline was effective in reducing inflammatory lung injury associated with high tidal volume ventilation.