Protein containing synthetic surfactant versus animal derived surfactant extract for the prevention and treatment of respiratory distress syndrome

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

The present review considers some controversial management practices during extremely premature perinatal transition. We focus on perinatal prevention and treatment of respiratory distress syndrome (RDS) in immature infants. New concerns regarding antenatal corticosteroid management have been raised. Many fetuses are only exposed to potential adverse effects of the drug. Hence, the formulation and the dosage may need to be modified. Another challenge is to increase the fraction of the high-risk fetuses that benefit from the drug and to minimize the harmful effects of the drug. On the other hand, boosting anti-inflammatory and anti-microbial properties of surfactant requires further attention. Techniques of prophylactic surfactant administration to extremely immature infants at birth may be further refined. Also, new findings suggest that prophylactic treatment of patent ductus arteriosus (PDA) of a high-risk population rather than later selective closure of PDA may be preferred. The TREOCAPA trial (Prophylactic treatment of the ductus arteriosus in preterm infants by acetaminophen) evaluates, whether early intravenous paracetamol decreases the serious cardiorespiratory consequences following extremely premature birth. Lastly, is inhaled nitric oxide (iNO) used in excess? According to current evidence, iNO treatment of uncomplicated RDS is not indicated. Considerably less than 10% of all very premature infants are affected by early persistence of pulmonary hypertension (PPHN). According to observational studies, effective ventilation combined with early iNO treatment are effective in management of this previously fatal disease. PPHN is associated with prolonged rupture of fetal membranes and birth asphyxia. The lipopolysaccharide (LPS)-induced immunotolerance and hypoxia-reperfusion-induced oxidant stress may inactivate NO-synthetases in pulmonary arterioles and terminal airways. Prospective trials on iNO in the management of PPHN are indicated. Other pulmonary vasodilators may be considered as comparison drugs or adjunctive drugs. The multidisciplinary challenge is to understand the regulation of pregnancy duration and the factors participating the onset of extremely premature preterm deliveries and respiratory adaptation. Basic research aims to identify deficiencies in maternal and fetal tissues that predispose to very preterm births and deteriorate the respiratory adaptation of immature infants. Better understanding on causes and prevention of extremely preterm births would eventually provide effective antenatal and neonatal management practices required for the intact survival.

Prevention and Treatment of Respiratory Distress Syndrome in Preterm Neonates

Respiratory distress syndrome (RDS) impacts a high proportion of preterm neonates, resulting in significant morbidity and mortality. Advances in pharmacotherapy, specifically antenatal corticosteroids and postnatal surfactant therapy, have significantly reduced the incidence and impact of neonatal RDS. Antenatal corticosteroids accelerate fetal lung maturation by increasing the activity of enzymes responsible for surfactant biosynthesis, resulting in improved lung compliance. Maternal antenatal corticosteroid treatment has improved survival of preterm neonates and lowered the incidence of brain injury. After birth, exogenous surfactant administration improves lung compliance and oxygenation, resulting in reductions in the incidence of pneumothorax and of death. Future research will identify the optimal surfactant product, timing of the initial dose, and mode of delivery.

The evolution of modern respiratory care for preterm infants

Preterm birth rates are rising, and many preterm infants have breathing difficulty after birth. Treatments for infants with prolonged breathing difficulty include oxygen therapy, exogenous surfactant, various modes of respiratory support, and postnatal corticosteroids. In this Series paper, we review the history of neonatal respiratory care and its effect on long-term outcomes, and we outline the future direction of the research field. The delivery and monitoring of oxygen therapy remains controversial, despite being in use for more than 50 years. Exogenous surfactant replacement has been used for 25 years and has dramatically reduced mortality and morbidity, but more research on when and how it is administered is needed. Methods and techniques of neonatal respiratory support are evolving. Clinicians are moving away from routine intubation and ventilation, and new modes of non-invasive support are being investigated. Postnatal corticosteroids have a limited role in infants with evolving bronchopulmonary dysplasia, but more research is needed to identify the best timing, type, dose, and method of administration. Despite advances in neonatal care in the past 50 years, bronchopulmonary dysplasia, with all its adverse short-term and long-term consequences, is still a serious problem in neonatal care. The challenge remains to support breathing in preterm infants, with special attention to risk factors in the subpopulation of infants that are at highest risk of bronchopulmonary dysplasia, without damaging their lungs or adversely affecting their long-term health.

Effects of the New Generation Synthetic Reconstituted Surfactant CHF5633 on Pro- and Anti-Inflammatory Cytokine Expression in Native and LPS-Stimulated Adult CD14+ Monocytes

Background

Surfactant replacement therapy is the standard of care for the prevention and treatment of neonatal respiratory distress syndrome. New generation synthetic surfactants represent a promising alternative to animal-derived surfactants. CHF5633, a new generation reconstituted synthetic surfactant containing SP-B and SP-C analogs and two synthetic phospholipids has demonstrated biophysical effectiveness in vitro and in vivo. While several surfactant preparations have previously been ascribed immunomodulatory capacities, in vitro data on immunomodulation by CHF5633 are limited, so far. Our study aimed to investigate pro- and anti-inflammatory effects of CHF5633 on native and LPS-stimulated human adult monocytes.

Methods

Highly purified adult CD14⁺ cells, either native or simultaneously stimulated with LPS, were exposed to CHF5633, its components, or poractant alfa (Curosurf^®). Subsequent expression of TNF-α, IL-1β, IL-8 and IL-10 mRNA was quantified by real-time quantitative PCR, corresponding intracellular cytokine synthesis was analyzed by flow cytometry. Potential effects on TLR2 and TLR4 mRNA and protein expression were monitored by qPCR and flow cytometry.

Results

Neither CHF5633 nor any of its components induced inflammation or apoptosis in native adult CD14⁺ monocytes. Moreover, LPS-induced pro-inflammatory responses were not aggravated by simultaneous exposure of monocytes to CHF5633 or its components. In LPS-stimulated monocytes, exposure to CHF5633 led to a significant decrease in TNF-α mRNA (0.57 ± 0.23-fold, p = 0.043 at 4h; 0.56 ± 0.27-fold, p = 0.042 at 14h). Reduction of LPS-induced IL-1β mRNA expression was not significant (0.73 ± 0.16, p = 0.17 at 4h). LPS-induced IL-8 and IL-10 mRNA and protein expression were unaffected by CHF5633. For all cytokines, the observed CHF5633 effects paralleled a Curosurf®-induced modulation of cytokine response. TLR2 and TLR4 mRNA and protein expression were not affected by CHF5633 and Curosurf®, neither in native nor in LPS-stimulated adult monocytes.

Conclusion

The new generation reconstituted synthetic surfactant CHF5633 was tested for potential immunomodulation on native and LPS-activated adult human monocytes. Our data confirm that CHF5633 does not exert unintended pro-inflammatory effects in both settings. On the contrary, CHF5633 significantly suppressed TNF-α mRNA expression in LPS-stimulated adult monocytes, indicating potential anti-inflammatory effects.

Animal derived surfactant extract versus protein free synthetic surfactant for the prevention and treatment of respiratory distress syndrome

BACKGROUND

A wide variety of surfactant preparations have been developed and tested including synthetic surfactants and surfactants derived from animal sources. Although clinical trials have demonstrated that both synthetic surfactant and animal derived surfactant preparations are effective, comparison in animal models has suggested that there may be greater efficacy of animal derived surfactant products, perhaps due to the protein content of animal derived surfactant.

OBJECTIVES

To compare the effect of animal derived surfactant to protein free synthetic surfactant preparations in preterm infants at risk for or having respiratory distress syndrome (RDS).

SEARCH METHODS

Searches were updated of the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2014), PubMed, CINAHL and EMBASE (1975 through November 2014). All languages were included.

SELECTION CRITERIA

Randomized controlled trials comparing administration of protein free synthetic surfactants to administration of animal derived surfactant extracts in preterm infants at risk for or having respiratory distress syndrome were considered for this review.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Fifteen trials met the inclusion criteria. The meta-analysis showed that the use of animal derived surfactant rather than protein free synthetic surfactant resulted in a significant reduction in the risk of pneumothorax [typical relative risk (RR) 0.65, 95% CI 0.55 to 0.77; typical risk difference (RD) -0.04, 95% CI -0.06 to -0.02; number needed to treat to benefit (NNTB) 25; 11 studies, 5356 infants] and a marginal reduction in the risk of mortality (typical RR 0.89, 95% CI 0.79 to 0.99; typical RD -0.02, 95% CI -0.04 to -0.00; NNTB 50; 13 studies, 5413 infants).Animal derived surfactant was associated with an increase in the risk of necrotizing enterocolitis [typical RR 1.38, 95% CI 1.08 to 1.76; typical RD 0.02, 95% CI 0.01 to 0.04; number needed to treat to harm (NNTH) 50; 8 studies, 3462 infants] and a marginal increase in the risk of any intraventricular hemorrhage (typical RR 1.07, 95% CI 0.99 to 1.15; typical RD 0.02, 95% CI 0.00 to 0.05; 10 studies, 5045 infants) but no increase in Grade 3 to 4 intraventricular hemorrhage (typical RR 1.08, 95% CI 0.91 to 1.27; typical RD 0.01, 95% CI -0.01 to 0.03; 9 studies, 4241 infants).The meta-analyses supported a marginal decrease in the risk of bronchopulmonary dysplasia or mortality associated with the use of animal derived surfactant preparations (typical RR 0.95, 95% CI 0.91 to 1.00; typical RD -0.03, 95% CI -0.06 to 0.00; 6 studies, 3811 infants). No other relevant differences in outcomes were noted.

AUTHORS' CONCLUSIONS

Both animal derived surfactant extracts and protein free synthetic surfactant extracts are effective in the treatment and prevention of respiratory distress syndrome. Comparative trials demonstrate greater early improvement in the requirement for ventilator support, fewer pneumothoraces, and fewer deaths associated with animal derived surfactant extract treatment. Animal derived surfactant may be associated with an increase in necrotizing enterocolitis and intraventricular hemorrhage, though the more serious hemorrhages (Grade 3 and 4) are not increased. Despite these concerns, animal derived surfactant extracts would seem to be the more desirable choice when compared to currently available protein free synthetic surfactants.

An update on pharmacologic approaches to bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most prevalent long-term morbidity in surviving extremely preterm infants and is linked to increased risk of reactive airways disease, pulmonary hypertension, post-neonatal mortality, and adverse neurodevelopmental outcomes. BPD affects approximately 20% of premature newborns, and up to 60% of premature infants born before completing 26 weeks of gestation. It is characterized by the need for assisted ventilation and/or supplemental oxygen at 36 weeks postmenstrual age. Approaches to prevention and treatment of BPD have evolved with improved understanding of its pathogenesis. This review will focus on recent advancements and detail current research in pharmacotherapy for BPD. The evidence for both current and potential future experimental therapies will be reviewed in detail. As our understanding of the complex and multifactorial pathophysiology of BPD changes, research into these current and future approaches must continue to evolve.

Comparative study of clinical pulmonary surfactants using atomic force microscopy

Clinical pulmonary surfactant is routinely used to treat premature newborns with respiratory distress syndrome, and has shown great potential in alleviating a number of neonatal and adult respiratory diseases. Despite extensive study of chemical composition, surface activity, and clinical performance of various surfactant preparations, a direct comparison of surfactant films is still lacking. In this study, we use atomic force microscopy to characterize and compare four animal-derived clinical surfactants currently used throughout the world, i.e., Survanta, Curosurf, Infasurf and BLES. These modified-natural surfactants are further compared to dipalmitoyl phosphatidylcholine (DPPC), a synthetic model surfactant of DPPC:palmitoyl-oleoyl phosphatidylglycerol (POPG) (7:3), and endogenous bovine natural surfactant. Atomic force microscopy reveals significant differences in the lateral structure and molecular organization of these surfactant preparations. These differences are discussed in terms of DPPC and cholesterol contents. We conclude that all animal-derived clinical surfactants assume a similar structure of multilayers of fluid phospholipids closely attached to an interfacial monolayer enriched in DPPC, at physiologically relevant surface pressures. This study provides the first comprehensive survey of the lateral structure of clinical surfactants at various surface pressures. It may have clinical implications on future application and development of surfactant preparations.

Global report on preterm birth and stillbirth (3 of 7): evidence for effectiveness of interventions

INTRODUCTION

Interventions directed toward mothers before and during pregnancy and childbirth may help reduce preterm births and stillbirths. Survival of preterm newborns may also be improved with interventions given during these times or soon after birth. This comprehensive review assesses existing interventions for low- and middle-income countries (LMICs).

METHODS

Approximately 2,000 intervention studies were systematically evaluated through December 31, 2008. They addressed preterm birth or low birth weight; stillbirth or perinatal mortality; and management of preterm newborns. Out of 82 identified interventions, 49 were relevant to LMICs and had reasonable amounts of evidence, and therefore selected for in-depth reviews. Each was classified and assessed by the quality of available evidence and its potential to treat or prevent preterm birth and stillbirth. Impacts on other maternal, fetal, newborn or child health outcomes were also considered. Assessments were based on an adaptation of the Grades of Recommendation Assessment, Development and Evaluation criteria.

RESULTS

Most interventions require additional research to improve the quality of evidence. Others had little evidence of benefit and should be discontinued. The following are supported by moderate- to high-quality evidence and strongly recommended for LMICs: Two interventions prevent preterm births--smoking cessation and progesterone. Eight interventions prevent stillbirths--balanced protein energy supplementation, screening and treatment of syphilis, intermittant presumptive treatment for malaria during pregnancy, insecticide-treated mosquito nets, birth preparedness, emergency obstetric care, cesarean section for breech presentation, and elective induction for post-term delivery. Eleven interventions improve survival of preterm newborns--prophylactic steroids in preterm labor, antibiotics for PROM, vitamin K supplementation at delivery, case management of neonatal sepsis and pneumonia, delayed cord clamping, room air (vs. 100% oxygen) for resuscitation, hospital-based kangaroo mother care, early breastfeeding, thermal care, and surfactant therapy and application of continued distending pressure to the lungs for respiratory distress syndrome

CONCLUSION

The research paradigm for discovery science and intervention development must be balanced to address prevention as well as improve morbidity and mortality in all settings. This review also reveals significant gaps in current knowledge of interventions spanning the continuum of maternal and fetal outcomes, and the critical need to generate further high-quality evidence for promising interventions.

Drug therapies in bronchopulmonary dysplasia: debunking the myths

Bronchopulmonary dysplasia (BPD), also known as chronic lung disease (CLD), is one of the most challenging complications in premature infants. The incidence of BPD has been increasing over the past two decades in parallel with an improvement in the survival of this population. Furthermore, the clinical characteristics and the natural history of infants affected by BPD have changed considerably, and newer definitions to clarify the term 'BPD' have also evolved since its first description more than four decades ago. Several drug therapies have also evolved, either to manage these infants' respiratory distress syndrome with an aim to prevent BPD or to manage the established condition. Although there is good evidence to support the 'routine' use of some therapies, many other therapies currently used in relation to BPD remain individual- or institution-specific, depending on beliefs and myths that we have adopted. In this article, we discuss the importance of defining BPD more objectively and the support--or lack thereof--for the drug therapies used in relation to BPD.

Pitfalls, problems, and progress in bronchopulmonary dysplasia

Bronchopulmonary dysplasia is a chronic lung disease associated with premature birth and characterized by early lung injury. In this review we discuss some pitfalls, problems, and progress in this condition over the last decade, focusing mainly on the last 5 years, limited to studies in human neonates. Changes in the definition, pathogenesis, genetic susceptibility, and recent biomarkers associated with bronchopulmonary dysplasia will be discussed. Progress in current management strategies, along with novel approaches/therapies, will be critically appraised. Finally, recent data on long-term pulmonary and neurodevelopmental outcomes of infants with bronchopulmonary dysplasia will be summarized.

Pathogenesis and prevention of chronic lung disease in the neonate

Often used interchangeably, chronic lung disease (CLD) or bronchopulmonary dysplasia (BPD) develops primarily in extremely low birth weight infants weighing <1000 g who receive prolonged oxygen therapy and or positive pressure ventilation. CLD, which occurs in as many as 30 percent of infants born weighing <1000 g, contributes significantly to the morbidity and mortality seen in very low birth weight infants. Despite extensive research aimed at identifying risk factors and devising preventative therapies, many questions about the etiology and pathogenesis of BPD remain. This article reviews the embryologic development of the lung and the pathogenesis of CLD or BPD. The authors discuss some of the measures that have been used in an attempt to both prevent and treat BPD.

Review: Surfactant respiratory therapy using Surfaxin/sinapultide

Respiratory distress syndrome (RDS) is a leading cause of mortality and morbidity in preterm infants. Surfactant replacement therapy has been widely used to prevent and treat RDS in these newborns and has now become a standard of care. First-generation synthetic surfactants such as Exosurf did not contain any surfactant protein. This disadvantage was overcome with animal-derived surfactant preparations which contain specific proteins but has the limitation of being derived from animal sources. This has led to development of newer synthetic surfactants such as lucinactant (Surfaxin, Discovery Laboratories, Philadelphia) which contains the protein B mimic synthetic peptide, sinapultide. Recent phase 3 clinical trials with Surfaxin show promising results with similar efficacy as animal derived surfactants and yet avoiding the disadvantage associated with animal products. The purpose of this paper is to summarise results of recent clinical trials of Surfaxin use in newborns with RDS.

RESPIRATORY DISTRESS SYNDROME

Respiratory Distress Syndrome (RDS) is due to immaturity of the lungs, primarily the surfactant synthesising system; hence, the risk of RDS is inversely proportional to gestational age. The incidence of RDS has been reduced by the routine use of both antenatal corticosteroids and postnatal surfactant, but still approximately one per cent of babies develop RDS. Hyaline membranes, formed from plasma proteins which have leaked onto the lung surface through damaged capillaries and endothelial cells, line the terminal airways. Hence, RDS has also been called hyaline membrane disease, but RDS is the preferred name as the presence of hyaline membranes can only be confirmed histologically. The aim of this review is to emphasize the pathophysiology of RDS and the clinical presentation and relevance of diagnostic techniques in the current population of very prematurely born infants, highlighting the differential diagnosis. In addition, the evidence base for prophylactic and management strategies including whether new therapies and techniques of respiratory support have positively impacted on outcomes are discussed. The mortality and long term morbidity associated with very premature birth are described. Our increasing understanding that the so-called new bronchopulmonary dysplasia (BPD) and associated chronic adverse respiratory outcomes in such infants can reflect antenatal events resulting in abnormal lung growth is highlighted.