In vitro and in vivo comparison between poractant alfa and the new generation synthetic surfactant CHF5633

The Synthetic Surfactant CHF5633 Restores Lung Function and Lung Architecture in Severe Acute Respiratory Distress Syndrome in Adult Rabbits

PURPOSE

Acute respiratory distress syndrome (ARDS) is a major cause of hypoxemic respiratory failure in adults. In ARDS extensive inflammation and leakage of fluid into the alveoli lead to dysregulation of pulmonary surfactant metabolism and function. Altered surfactant synthesis, secretion, and breakdown contribute to the clinical features of decreased lung compliance and alveolar collapse. Lung function in ARDS could potentially be restored with surfactant replacement therapy, and synthetic surfactants with modified peptide analogues may better withstand inactivation in ARDS alveoli than natural surfactants.

METHODS

This study aimed to investigate the activity in vitro and the bolus effect (200 mg phospholipids/kg) of synthetic surfactant CHF5633 with analogues of SP-B and SP-C, or natural surfactant Poractant alfa (Curosurf®, both preparations Chiesi Farmaceutici S.p.A.) in a severe ARDS model (the ratio of partial pressure arterial oxygen and fraction of inspired oxygen, P/F ratio ≤ 13.3 kPa) induced by hydrochloric acid instillation followed by injurious ventilation in adult New Zealand rabbits. The animals were ventilated for 4 h after surfactant treatment and the respiratory parameters, histological appearance of lung parenchyma and levels of inflammation, oxidative stress, surfactant dysfunction, and endothelial damage were evaluated.

RESULTS

Both surfactant preparations yielded comparable improvements in lung function parameters, reductions in lung injury score, pro-inflammatory cytokines levels, and lung edema formation compared to untreated controls.

CONCLUSIONS

This study indicates that surfactant replacement therapy with CHF5633 improves lung function and lung architecture, and attenuates inflammation in severe ARDS in adult rabbits similarly to Poractant alfa. Clinical trials have so far not yielded conclusive results, but exogenous surfactant may be a valid supportive treatment for patients with ARDS given its anti-inflammatory and lung-protective effects.

Postnatal budesonide improved lung function in preterm lambs exposed to antenatal steroids and chorioamnionitis

BACKGROUND

A combination of budesonide and surfactant decreases the rates of BPD in infants and lung injury in preterm sheep. Whether this combination will show benefit in the setting of chorioamnionitis and antenatal steroids is not known.

METHODS

Ewes at 123 ± 1 day gestational age received intra-amniotic (IA) injections of 10 mg LPS before being randomized to receive either 0.25 mg/kg maternal betamethasone phosphate and acetate or saline by intramuscular (IM) injection at 48 and 24 h prior to delivery at 125 ± 1 day. Lambs (N = 6-9/group) underwent intentionally injurious ventilation for 15 min, then lambs received surfactant mixed with either: (1) saline; or (2) Budesonide 0.25 mg/kg and were ventilated for 4 h.

RESULTS

Compared with LPS-exposed animals that received no IM steroid treatment, betamethasone exposed fetuses had improved hemodynamic stability, lung compliance, and ventilation efficiency. The addition of budesonide to surfactant further improved markers of injury and pro-inflammatory cytokine mRNA in both betamethasone IM or no IM lambs exposed to LPS IA. Antenatal betamethasone and IA LPS exposures decreased budesonide levels in the fetal lung and plasma.

CONCLUSION

Antenatal betamethasone stabilizes physiologic parameters in LPS treated lambs. Budesonide mixed with surfactant further decreases injury and improves respiratory physiology in betamethasone treated animals.

IMPACT

Antenatal betamethasone improved lung and systemic physiology in the setting of intra-amniotic LPS. The addition of budesonide to the surfactant further improved lung function. Budesonide levels in the plasma and lung were lower in lambs exposed to either LPS or LPS and Betamethasone animals, and these findings were not explained by increased esterification in the lungs. The combination of antenatal steroids and budesonide with surfactant had the lowest markers of pro-inflammatory cytokines in the lung of LPS exposed animals.

Synthetic surfactant with a combined SP-B and SP-C analogue is efficient in rabbit models of adult and neonatal respiratory distress syndrome

Respiratory distress syndrome (RDS) in premature infants is caused by insufficient amounts of endogenous lung surfactant and is efficiently treated with replacement therapy using animal-derived surfactant preparations. On the other hand, adult/acute RDS (ARDS) occurs secondary to for example, sepsis, aspiration of gastric contents, and multitrauma and is caused by alveolar endothelial damage, leakage of plasma components into the airspaces and inhibition of surfactant activity. Instillation of surfactant preparations in ARDS has so far resulted in very limited treatment effects, partly due to inactivation of the delivered surfactants in the airspace. Here, we develop a combined surfactant protein B (SP-B) and SP-C peptide analogue (Combo) that can be efficiently expressed and purified from Escherichia coli without any solubility or purification tag. NMR spectroscopy shows that Combo peptide forms α-helices both in organic solvents and in lipid micelles, which coincide with the helical regions described for the isolated SP-B and SP-C parts. Artificial Combo surfactant composed of synthetic dipalmitoylphosphatidylcholine:palmitoyloleoylphosphatidylglycerol, 1:1, mixed with 3 weights % relative to total phospholipids of Combo peptide efficiently improves tidal volumes and lung gas volumes at end-expiration in a premature rabbit fetus model of RDS. Combo surfactant also improves oxygenation and respiratory parameters and lowers cytokine release in an acid instillation-induced ARDS adult rabbit model. Combo surfactant is markedly more resistant to inhibition by albumin and fibrinogen than a natural-derived surfactant in clinical use for the treatment of RDS. These features of Combo surfactant make it attractive for the development of novel therapies against human ARDS.

Time-resolved transcriptomic profiling of the developing rabbit's lungs: impact of premature birth and implications for modelling bronchopulmonary dysplasia

BACKGROUND

Premature birth, perinatal inflammation, and life-saving therapies such as postnatal oxygen and mechanical ventilation are strongly associated with the development of bronchopulmonary dysplasia (BPD); these risk factors, alone or combined, cause lung inflammation and alter programmed molecular patterns of normal lung development. The current knowledge on the molecular regulation of lung development mainly derives from mechanistic studies conducted in newborn rodents exposed to postnatal hyperoxia, which have been proven useful but have some limitations.

METHODS

Here, we used the rabbit model of BPD as a cost-effective alternative model that mirrors human lung development and, in addition, enables investigating the impact of premature birth per se on the pathophysiology of BPD without further perinatal insults (e.g., hyperoxia, LPS-induced inflammation). First, we characterized the rabbit's normal lung development along the distinct stages (i.e., pseudoglandular, canalicular, saccular, and alveolar phases) using histological, transcriptomic and proteomic analyses. Then, the impact of premature birth was investigated, comparing the sequential transcriptomic profiles of preterm rabbits obtained at different time intervals during their first week of postnatal life with those from age-matched term pups.

RESULTS

Histological findings showed stage-specific morphological features of the developing rabbit's lung and validated the selected time intervals for the transcriptomic profiling. Cell cycle and embryo development, oxidative phosphorylation, and WNT signaling, among others, showed high gene expression in the pseudoglandular phase. Autophagy, epithelial morphogenesis, response to transforming growth factor β, angiogenesis, epithelium/endothelial cells development, and epithelium/endothelial cells migration pathways appeared upregulated from the 28th day of gestation (early saccular phase), which represents the starting point of the premature rabbit model. Premature birth caused a significant dysregulation of the inflammatory response. TNF-responsive, NF-κB regulated genes were significantly upregulated at premature delivery and triggered downstream inflammatory pathways such as leukocyte activation and cytokine signaling, which persisted upregulated during the first week of life. Preterm birth also dysregulated relevant pathways for normal lung development, such as blood vessel morphogenesis and epithelial-mesenchymal transition.

CONCLUSION

These findings establish the 28-day gestation premature rabbit as a suitable model for mechanistic and pharmacological studies in the context of BPD.

Efficacy of synthetic surfactant (CHF5633) bolus and/or lavage in meconium-induced lung injury in ventilated newborn rabbits

BACKGROUND

The pathogenesis of neonatal meconium aspiration syndrome (MAS) involves meconium-induced lung inflammation and surfactant inactivation. Bronchoalveolar lavage (BAL) with diluted surfactant facilitates the removal of meconium. CHF5633, one of the most promising synthetic surfactants, is effective in neonatal respiratory distress syndrome. Here we investigated its efficacy via BAL in an experimental MAS model.

METHODS

Experimental MAS was induced at birth in near-term newborn rabbits by intratracheal instillation of reconstituted human meconium. First, undiluted CHF5633 was compared with a porcine-derived surfactant (Poractant alfa) via intratracheal bolus (200 mg/kg). Second, the efficacy of BAL with diluted CHF5633 (5 mg/mL, 20 ml/kg) alone, or followed by undiluted boluses (100 or 300 mg/kg), was investigated.

RESULTS

Meconium instillation caused severe lung injury, reduced endogenous surfactant pool, and poor survival. CHF5633 had similar benefits in improving survival and alleviating lung injury as Poractant alfa. CHF5633 BAL plus higher boluses exerted better effects than BAL or bolus alone in lung injury alleviation by reversing phospholipid pools and mitigating proinflammatory cytokine mRNA expression, without fluid retention and function deterioration.

CONCLUSIONS

CHF5633 improved survival and alleviated meconium-induced lung injury, the same as Poractant alfa. CHF5633 BAL plus boluses was the optimal modality, which warrants further clinical investigation.

IMPACT

To explore the efficacy of a synthetic surfactant, CHF5633, in neonatal lung protection comparing with Poractant alfa in a near-term newborn rabbit model with meconium-induced lung injury. Similar effects on improving survival and alleviating lung injury were found between CHF5633 and Poractant alfa. Optimal therapeutic effects were identified from the diluted CHF5633 bronchoalveolar lavage followed by its undiluted bolus instillation compared to the lavage or bolus alone regimens. Animals with CHF5633 lavage plus bolus regimen exerted neither substantial lung fluid retention nor lung mechanics deterioration but a trend of higher pulmonary surfactant-associated phospholipid pools.

Aerosol Delivery of Lung Surfactant and Nasal CPAP in the Treatment of Neonatal Respiratory Distress Syndrome

After shifting away from invasive mechanical ventilation and intratracheal instillation of surfactant toward non-invasive ventilation with nasal CPAP and less invasive surfactant administration in order to prevent bronchopulmonary dysplasia in preterm infants with respiratory distress syndrome, fully non-invasive surfactant nebulization is the next Holy Grail in neonatology. Here we review the characteristics of animal-derived (clinical) and new advanced synthetic lung surfactants and improvements in nebulization technology required to secure optimal lung deposition and effectivity of non-invasive lung surfactant administration. Studies in surfactant-deficient animals and preterm infants have demonstrated the safety and potential of non-invasive surfactant administration, but also provide new directions for the development of synthetic lung surfactant destined for aerosol delivery, implementation of breath-actuated nebulization and optimization of nasal CPAP, nebulizer circuit and nasal interface. Surfactant nebulization may offer a truly non-invasive option for surfactant delivery to preterm infants in the near future.

Characterization of phospholipid-modified lung surfactant in vitro and in a neonatal ARDS model reveals anti-inflammatory potential and surfactant lipidome signatures

A strong inflammatory immune response drives the lung pathology in neonatal acute respiratory distress syndrome (nARDS). Anti-inflammatory therapy is therefore a promising strategy for improved treatment of nARDS. We demonstrate a new function of the anionic phospholipids POPG, DOPG, and PIP2 as inhibitors of IL-1β release by LPS and ATP-induced inflammasome activation in human monocyte-derived and lung macrophages. Curosurf® surfactant was enriched with POPG, DOPG, PIP2 and the head-group derivative IP3, biophysically characterized and applicability was evaluated in a piglet model of nARDS. The composition of pulmonary surfactant from piglets was determined by shotgun lipidomics screens. After 72 h of nARDS, levels of POPG, DOPG, and PIP2 were enhanced in the respective treatment groups. Otherwise, we did not observe changes of individual lipid species in any of the groups. Surfactant proteins were not affected, with the exception of the IP3 treated group. Our data show that POPG, DOPG, and PIP2 are potent inhibitors of inflammasome activation; their enrichment in a surfactant preparation did not induce any negative effects on lipid profile and reduced biophysical function in vitro was mainly observed for PIP2. These results encourage to rethink the current strategies of improving surfactant preparations by inclusion of anionic lipids as potent anti-inflammatory immune regulators.

Treatment of Respiratory Distress Syndrome with Single Recombinant Polypeptides that Combine Features of SP-B and SP-C

Treatment of respiratory distress syndrome (RDS) with surfactant replacement therapy in prematurely born infants was introduced more than 30 years ago; however, the surfactant preparations currently in clinical use are extracts from animal lungs. A synthetic surfactant that matches the currently used nature-derived surfactant preparations and can be produced in a cost-efficient manner would enable worldwide treatment of neonatal RDS and could also be tested against lung diseases in adults. The major challenge in developing fully functional synthetic surfactant preparations is to recapitulate the properties of the hydrophobic lung surfactant proteins B (SP-B) and SP-C. Here, we have designed single polypeptides that combine properties of SP-B and SP-C and produced them recombinantly using a novel solubility tag based on spider silk production. These Combo peptides mixed with phospholipids are as efficient as nature-derived surfactant preparations against neonatal RDS in premature rabbit fetuses.

Pulmonary surfactant: a unique biomaterial with life-saving therapeutic applications

Pulmonary surfactant is a complex lipoprotein mixture secreted into the alveolar lumen by type 2 pneumocytes, which is composed by tens of different lipids (approximately 90% of its entire mass) and surfactant proteins (approximately 10% of the mass). It is crucially involved in maintaining lung homeostasis by reducing the values of alveolar liquid surface tension close to zero at end-expiration, thereby avoiding the alveolar collapse, and assembling a chemical and physical barrier against inhaled pathogens. A deficient amount of surfactant or its functional inactivation is directly linked to a wide range of lung pathologies, including the neonatal respiratory distress syndrome. This paper reviews the main biophysical concepts of surfactant activity and its inactivation mechanisms, and describes the past, present and future roles of surfactant replacement therapy, focusing on the exogenous surfactant preparations marketed worldwide and new formulations under development. The closing section describes the pulmonary surfactant in the context of drug delivery. Thanks to its peculiar composition, biocompatibility, and alveolar spreading capability, the surfactant may work not only as a shuttle to the branched anatomy of the lung for other drugs but also as a modulator for their release, opening to innovative therapeutic avenues for the treatment of several respiratory diseases.

Budesonide with surfactant decreases systemic responses in mechanically ventilated preterm lambs exposed to fetal intra-amniotic lipopolysaccharide

BACKGROUND

Chorioamnionitis is associated with increased rates of bronchopulmonary dysplasia (BPD) in ventilated preterm infants. Budesonide when added to surfactant decreased lung and systemic inflammation from mechanical ventilation in preterm lambs and decreased the rates and severity of BPD in preterm infants. We hypothesized that the addition of budesonide to surfactant will decrease the injury from mechanical ventilation in preterm lambs exposed to intra-amniotic (IA) lipopolysaccharide (LPS).

METHODS

Lambs at 126 ± 1 day GA received LPS 10 mg IA 48 h prior to injurious mechanical ventilation. After 15 min, lambs received either surfactant mixed with: (1) saline or (2) Budesonide 0.25 mg/kg, then ventilated with normal tidal volumes for 4 h. Injury markers in the lung, liver, and brain were compared.

RESULTS

Compared with surfactant alone, the addition of budesonide improved blood pressures, dynamic compliance, and ventilation, while decreasing mRNA for pro-inflammatory cytokines in the lung, liver, and multiple areas of the brain. LPS caused neuronal activation and structural changes in the brain that were not altered by budesonide. Budesonide was not retained within the lung beyond 4 h.

CONCLUSIONS

In preterm lambs exposed to IA LPS, the addition of budesonide to surfactant improved physiology and markers of lung and systemic inflammation.

IMPACT

The addition of budesonide to surfactant decreases the lung and systemic responses to injurious mechanical ventilation preterm lambs exposed to fetal LPS. Budesonide was present in the plasma by 15 min and the majority of the budesonide is no longer in the lung at 4 h of ventilation. IA LPS and mechanical ventilation caused structural changes in the brain that were not altered by short-term exposure to budesonide. The budesonide dose of 0.25 mg/kg being used clinically seems likely to decrease lung inflammation in preterm infants with chorioamnionitis.

Impact of synthetic surfactant CHF5633 with SP-B and SP-C analogues on lung function and inflammation in rabbit model of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is associated with diffuse inflammation, alveolar epithelial damage, and leakage of plasma proteins into the alveolar space, which together contribute to inactivation of pulmonary surfactant and respiratory failure. Exogenous surfactant delivery is therefore considered to hold potential for ARDS treatment, but clinical trials with natural derived surfactant or synthetic surfactant containing a surfactant protein C (SP-C) analogue have been negative. Synthetic surfactant CHF5633, containing analogues of SP-B and SP-C, may be effective against ARDS. The aim here was to compare treatment effects of CHF5633 and animal-derived surfactant poractant alfa in animal model of ARDS. ARDS was induced in adult New Zealand rabbits by mild lung lavages followed by injurious ventilation until respiratory failure (P/F ratio <26.7 kPa). The animals were then treated with intratracheal bolus of 200 mg/kg CHF5633 or poractant alfa (Curosurf® ), or air as control. The animals were subsequently ventilated for an additional 4 hr and respiratory parameters were recorded regularly. Postmortem, histological analysis, degree of lung edema, and levels of the cytokines TNFα, IL-6, and IL-8 in lung homogenates were evaluated. Both surfactant preparations improved lung function, reduced the levels of pro-inflammatory cytokines, and degree of lung edema to very similar degrees versus the controls. No significant differences in any of the analyzed parameters were observed between the CHF5633- and poractant alfa-treated groups. This study indicates that single dose of CHF5633 improves lung function and attenuates inflammation as effectively as poractant alfa in experimental ARDS caused by injurious ventilation.

Dose of budesonide with surfactant affects lung and systemic inflammation after normal and injurious ventilation in preterm lambs

BACKGROUND

The addition of budesonide (Bud) 0.25 mg/kg to surfactant decreased the lung and systemic responses to mechanical ventilation in preterm sheep and the rates and severity of bronchopulmonary dysplasia (BPD) in preterm infants. We hypothesized that lower budesonide concentrations in surfactant will decrease injury while decreasing systemic corticosteroid exposure.

METHODS

Preterm lambs received either (1) protective tidal volume (V_T) ventilation with surfactant from birth or (2) injurious V_T ventilation for 15 min and then surfactant treatment. Lambs were further assigned to surfactant mixed with (i) Saline, (ii) Bud 0.25 mg/kg, (iii) Bud 0.1 mg/kg, or (iv) Bud 0.04 mg/kg. All lambs were then ventilated with protective V_T for 6 h.

RESULTS

Plasma Bud levels were proportional to the dose received and decreased throughout ventilation. In both protective and injurious V_T ventilation, <4% of Bud remained in the lung at 6 h. Some of the improvements in physiology and markers of injury with Bud 0.25 mg/kg were also found with 0.1 mg/kg, whereas 0.04 mg/kg had only minimal effects.

CONCLUSIONS

Lower doses of Bud were less effective at decreasing lung and systemic inflammation from mechanical ventilation. The plasma Bud levels were proportional to dose given and the majority left the lung.

Synthetic Surfactant CHF5633 Compared with Poractant Alfa in the Treatment of Neonatal Respiratory Distress Syndrome: A Multicenter, Double-Blind, Randomized, Controlled Clinical Trial

OBJECTIVE

To compare efficacy and safety of a new synthetic surfactant, CHF5633, enriched with surfactant proteins, SP-B and SP-C peptide analogues, with porcine surfactant, poractant alfa, for the treatment of respiratory distress syndrome in infants born preterm.

STUDY DESIGN

Neonates born preterm on respiratory support requiring fraction of inspired oxygen (FiO₂) ≥0.30 from 24^0/7 to 26^6/7 weeks and FiO₂ ≥0.35 from 27^0/7 to 29^6/7 weeks of gestation to maintain 88%-95% oxygen saturation were randomized to receive 200 mg/kg of CHF5633 or poractant alfa. If necessary, redosing was given at 100 mg/kg. Efficacy end points were oxygen requirement (FiO₂, respiratory severity score [FiO₂ × mean airway pressure]) in the first 24 hours, 7 and 28 days, discharge home, and/or 36 weeks of postmenstrual age; mortality and bronchopulmonary dysplasia at 28 days and 36 weeks of PMA. Adverse events and immunogenicity were monitored for safety.

RESULTS

Of the 123 randomized neonates, 113 were treated (56 and 57 in CHF5633 and poractant alfa groups, respectively). In both arms, FiO₂ and respiratory severity score decreased from baseline at all time points (P < .001) with no statistically significant differences between groups. Rescue surfactant use (19 [33.9%] vs 17 [29.8%]), bronchopulmonary dysplasia (31 [55.4%] and 32 [56.1%]), and mortality at day 28 (4 [7.1%] and 3 [5.3%]) were similar in the CHF5633 and poractant alfa groups, respectively. In 2 (3.4%) and 1 (1.7%) neonates, adverse drug reactions were reported in CHF5633 and poractant alfa groups, respectively. No immunogenicity was detected.

CONCLUSIONS

Treatment with CHF5633 showed similar efficacy and safety as poractant alfa in neonates born preterm with moderate-to-severe respiratory distress syndrome.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02452476.

In vitro characterization and in vivo comparison of the pulmonary outcomes of Poractant alfa and Calsurf in ventilated preterm rabbits

Poractant alfa and Calsurf are two natural surfactants widely used in China for the treatment of neonatal respiratory distress syndrome, which are extracted from porcine and calf lungs, respectively. The purpose of this experimental study was to compare their in vitro characteristics and in vivo effects in the improvement of pulmonary function and protection of lung injury. The biophysical properties, ultrastructure, and lipid composition of both surfactant preparations were respectively analysed in vitro by means of Langmuir-Blodgett trough (LBT), atomic force microscopy (AFM), and liquid-chromatography mass-spectrometry (LC-MS). Then, as core pharmacological activity, both head-to-head (100 and 200 mg/kg for both surfactants) and licensed dose comparisons (70 mg/kg Calsurf vs. 200 mg/kg Poractant alfa) between the two surfactants were conducted as prophylaxis in preterm rabbits with primary surfactant deficiency, assessing survival time and rate and dynamic compliance of the respiratory system (Cdyn). Intrapulmonary surfactant pools, morphometric volume density as alveolar expansion (Vv), and lung injury scores were determined post mortem. AFM and LC-MS analysis revealed qualitative differences in the ultrastructure as well as in the lipid composition of both preparations. Calsurf showed a longer plateau region of the LBT isotherm and lower film compressibility. In vivo, both surfactant preparations improved Cdyn at any dose, although maximum benefits in terms of Vv and intrapulmonary surfactant pools were seen with the 200 mg/kg dose in both surfactants. The group of animals treated with 200 mg/kg of Poractant alfa showed a prolonged survival time and rate compared to untreated but ventilated controls, and significantly ameliorated lung injury compared to Calsurf at any dose, including 200 mg/kg. The overall outcomes suggest the pulmonary effects to be dose dependent for both preparations. The group of animals treated with 200 mg/kg of Poractant alfa showed a significant reduction of mortality. Compared to Calsurf, Poractant alfa exerted better effects if licensed doses were compared, which requires further investigation.

In Vitro Functional and Structural Characterization of A Synthetic Clinical Pulmonary Surfactant with Enhanced Resistance to Inhibition

CHF5633 is a novel synthetic clinical pulmonary surfactant preparation composed by two phospholipid species, dipalmitoyl phosphatidylcholine (DPPC) and palmitoyloleoyl phosphatidylglycerol (POPG), and synthetic analogues of the hydrophobic surfactant proteins SP-B and SP-C. In this study, the interfacial properties of CHF5633 in the absence and in the presence of inhibitory serum proteins have been assessed in comparison with a native surfactant purified from porcine lungs and with poractant alpha, a widely used clinical surfactant preparation. The study of the spreading properties of CHF5633 in a Wilhelmy balance, its ability to adsorb and accumulate at air-liquid interfaces as revealed by a multiwell fluorescence assay, and its dynamic behavior under breathing-like compression-expansion cycling in a Captive Bubble Surfactometer (CBS), all revealed that CHF5633 exhibits a good behavior to reduce and sustain surface tensions to values below 5 mN/m. CHF5633 shows somehow slower initial interfacial adsorption than native surfactant or poractant alpha, but a better resistance to inhibition by serum proteins than the animal-derived clinical surfactant, comparable to that of the full native surfactant complex. Interfacial CHF5633 films formed in a Langmuir-Blodgett balance coupled with epifluorescence microscopy revealed similar propensity to segregate condensed lipid domains under compression than films made by native porcine surfactant or poractant alpha. This ability of CHF5633 to segregate condensed lipid phases can be related with a marked thermotropic transition from ordered to disordered membrane phases as exhibited by differential scanning calorimetry (DSC) of CHF5633 suspensions, occurring at similar temperatures but with higher associated enthalpy than that shown by poractant alpha. The good interfacial behavior of CHF5633 tested under physiologically meaningful conditions in vitro and its higher resistance to inactivation by serum proteins, together with its standardized and well-defined composition, makes it a particularly useful therapeutic preparation to be applied in situations associated with lung inflammation and edema, alone or in combined strategies to exploit surfactant-facilitated drug delivery.

Efficient delipidation of a recombinant lung surfactant lipopeptide analogue by liquid-gel chromatography

Pulmonary surfactant preparations extracted from natural sources have been used to treat millions of newborn babies with respiratory distress syndrome (RDS) and can possibly also be used to treat other lung diseases. Due to costly production and limited supply of animal-derived surfactants, synthetic alternatives are attractive. The water insolubility and aggregation-prone nature of the proteins present in animal-derived surfactant preparations have complicated development of artificial surfactant. A non-aggregating analog of lung surfactant protein C, SP-C33Leu is used in synthetic surfactant and we recently described an efficient method to produce rSP-C33Leu in bacteria. Here rSP-C33Leu obtained by salt precipitation of bacterial extracts was purified by two-step liquid gel chromatography and analyzed using mass spectrometry and RP-HPLC, showing that it is void of modifications and adducts. Premature New Zealand White rabbit fetuses instilled with 200mg/kg of 2% of rSP-C33Leu in phospholipids and ventilated with a positive end expiratory pressure showed increased tidal volumes and lung gas volumes compared to animals treated with phospholipids only. This shows that rSP-C33Leu can be purified from bacterial lipids and that rSP-C33Leu surfactant is active against experimental RDS.

Mass spectrometry imaging as a tool for evaluating the pulmonary distribution of exogenous surfactant in premature lambs

Background

The amount of surfactant deposited in the lungs and its overall pulmonary distribution determine the therapeutic outcome of surfactant replacement therapy. Most of the currently available methods to determine the intrapulmonary distribution of surfactant are time-consuming and require surfactant labelling. Our aim was to assess the potential of Mass Spectrometry Imaging (MSI) as a label-free technique to qualitatively and quantitatively evaluate the distribution of surfactant to the premature lamb.

Methods

Twelve preterm lambs (gestational age 126-127d, term ~150d) were allocated in two experimental groups. Seven lambs were treated with an intratracheal bolus of the synthetic surfactant CHF5633 (200 mg/kg) and 5 lambs were managed with mechanical ventilation for 120 min, as controls. The right lung lobes of all lambs were gradually frozen while inflated to 20 cmH₂O pressure for lung cryo-sections for MSI analysis. The intensity signals of SP-C analog and SP-B analog, the two synthetic peptides contained in the CHF5633 surfactant, were used to locate, map and quantify the intrapulmonary exogenous surfactant.

Results

Surfactant treatment was associated with a significant improvement of the mean arterial oxygenation and lung compliance (p < 0.05). Nevertheless, the physiological response to surfactant treatment was not uniform across all animals. SP-C analog and SP-B analog were successfully imaged and quantified by means of MSI in the peripheral lungs of all surfactant-treated animals. The intensity of the signal was remarkably low in untreated lambs, corresponding to background noise. The signal intensity of SP-B analog in each surfactant-treated animal, which represents the surfactant distributed to the peripheral right lung, correlated well with the physiologic response as assessed by the area under the curves of the individual arterial partial oxygen pressure and dynamic lung compliance curves of the lambs.

Conclusions

Applying MSI, we were able to detect, locate and quantify the amount of exogenous surfactant distributed to the lower right lung of surfactant-treated lambs. The distribution pattern of SP-B analog correlated well with the pulmonary physiological outcomes of the animals. MSI is a valuable label-free technique which is able to simultaneously evaluate qualitative and quantitative drug distribution in the lung.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1144-5) contains supplementary material, which is available to authorized users.

Tracing exogenous surfactant in vivo in rabbits by the natural variation of 13C

BACKGROUND

Respiratory Distress Syndrome (RDS) is a prematurity-related breathing disorder caused by a quantitative deficiency of pulmonary surfactant. Surfactant replacement therapy is effective for RDS newborns, although treatment failure has been reported. The aim of this study is to trace exogenous surfactant by ¹³C variation and estimate the amount reaching the lungs at different doses of the drug.

METHODS

Forty-four surfactant-depleted rabbits were obtained by serial bronchoalveolar lavages (BALs), that were merged into a pool (BAL pool) for each animal. Rabbits were in nasal continuous positive airway pressure and treated with 0, 25, 50, 100 or 200 mg/kg of poractant alfa by InSurE. After 90 min, rabbits were depleted again and a new pool (BAL end experiment) was collected. Disaturated-phosphatidylcholine (DSPC) was measured by gas chromatography. DSPC-Palmitic acid (PA) ¹³C/¹²C was analyzed by isotope ratio mass spectrometry. One-way non-parametric ANOVA and post-hoc Dunn's multiple comparison were used to assess differences among experimental groups.

RESULTS

Based on DSPC-PA ¹³C/¹²C in BAL pool and BAL end experiment, the estimated amount of exogenous surfactant ranged from 61 to 87% in dose-dependent way (p < 0.0001) in animals treated with 25 up to 200 mg/kg. Surfactant administration stimulated endogenous surfactant secretion. The percentage of drug recovered from lungs did not depend on the administered dose and accounted for 31% [24-40] of dose.

CONCLUSIONS

We reported a risk-free method to trace exogenous surfactant in vivo. It could be a valuable tool for assessing, alongside the physiological response, the delivery efficiency of surfactant administration techniques.

Synthetic surfactants with SP-B and SP-C analogues to enable worldwide treatment of neonatal respiratory distress syndrome and other lung diseases

Treatment of neonatal respiratory distress syndrome (RDS) using animal-derived lung surfactant preparations has reduced the mortality of handling premature infants with RDS to a 50th of that in the 1960s. The supply of animal-derived lung surfactants is limited and only a part of the preterm babies is treated. Thus, there is a need to develop well-defined synthetic replicas based on key components of natural surfactant. A synthetic product that equals natural-derived surfactants would enable cost-efficient production and could also facilitate the development of the treatments of other lung diseases than neonatal RDS. Recently the first synthetic surfactant that contains analogues of the two hydrophobic surfactant proteins B (SP-B) and SP-C entered clinical trials for the treatment of neonatal RDS. The development of functional synthetic analogues of SP-B and SP-C, however, is considerably more challenging than anticipated 30 years ago when the first structural information of the native proteins became available. For SP-B, a complex three-dimensional dimeric structure stabilized by several disulphides has necessitated the design of miniaturized analogues. The main challenge for SP-C has been the pronounced amyloid aggregation propensity of its transmembrane region. The development of a functional non-aggregating SP-C analogue that can be produced synthetically was achieved by designing the amyloidogenic native sequence so that it spontaneously forms a stable transmembrane α-helix.

Local pulmonary drug delivery in the preterm rabbit: feasibility and efficacy of daily intratracheal injections

Recent clinical trials in newborns have successfully used surfactant as a drug carrier for an active compound, to minimize systemic exposure. To investigate the translational potential of surfactant-compound mixtures and other local therapeutics, a relevant animal model is required in which intratracheal administration for maximal local deposition is technically possible and well tolerated. Preterm rabbit pups (born at 28 days of gestation) were exposed to either hyperoxia or normoxia and randomized to receive daily intratracheal surfactant, daily intratracheal saline, or no injections for 7 days. At day 7, the overall lung function and morphology were assessed. Efficacy in terms of distribution was assessed by micro-PET-CT on both day 0 and day 7. Lung function as well as parenchymal and vascular structure were altered by hyperoxia, thereby reproducing a phenotype reminiscent of bronchopulmonary dysplasia (BPD). Neither intratracheal surfactant nor saline affected the survival or the hyperoxia-induced BPD phenotype of the pups. Using PET-CT, we demonstrate that 82.5% of the injected radioactive tracer goes and remains in the lungs, with a decrease of only 4% after 150 min. Surfactant and saline can safely and effectively be administered in spontaneously breathing preterm rabbits. The described model and method enable researchers to evaluate intratracheal pharmacological interventions for the treatment of BPD.

Disulphide Bridges in Surfactant Protein B Analogues Affect Their Activity in Synthetic Surfactant Preparations

BACKGROUND

Limited supply and complicated manufacturing procedure of animal-derived surfactants make the development of synthetic surfactants warranted. The synthesis of surfactant protein (SP)-B and SP-C is complicated and several analogues have been developed. Mini-BLeu is an analogue that corresponds to the first and last helix of SP-B joined by a loop and linked by 2 disulphide bridges. SP-C33Leu is an SP-C analogue that can be cost-efficiently produced, but no such analogue has yet been described for SP-B.

OBJECTIVE

To design short SP-B analogues which lack disulphide bridges, are easy to produce and are efficacious in a preterm rabbit fetus model of neonatal RDS.

METHODS

Synthetic surfactants were prepared by adding 2 or 8% (w/w) of synthetic variants of Mini-B27, similar to Mini-BLeu but with a short loop, or different peptides covering helix 1 of SP-B to 2% (w/w) of SP-C33Leu in 80 mg/mL of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/egg yolk phosphatidylcholine/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol, 50: 40: 10 (by weight). Premature newborn rabbit fetuses were treated with 200 mg/kg of the surfactant preparations and ventilated with defined pressures for 30 min without positive end-expiratory pressure. Tidal volumes were registered during the experiments and lung gas volumes were measured at the end of the ventilation period.

RESULTS

Synthetic surfactant containing the Mini-B27 analogue with 2 disulphides gives similar lung gas volumes as treatment with an animal-derived surfactant preparation, but all other SP-B analogues gave lower lung gas volumes. All synthetic surfactants studied gave no significant differences in compliances except the surfactant containing the Mini-B27 analogue without cysteines that performed somewhat better at 30 min.

CONCLUSION

The helix-loop-helix SP-B analogues tested in this study require the presence of 2 disulphide bridges for optimal activity in a rabbit RDS model.

Turkish Neonatal Society guideline on the management of respiratory distress syndrome and surfactant treatment

Respiratory distress syndrome is the leading cause of respiratory failure in preterm infants. The incidence and severity of respiratory distress syndrome are inversely related to the gestational age of the newborn. The major underlying pathophysiologic mechanisms are surfactant deficiency and anatomic, structural immaturity of the lung. Recent improvements such as antenatal steroid treatment to enhance pulmonary maturity, appropriate resuscitation facilitated by placental transfusion and immediate use of continuous positive airway pressure for alveolar recruitment, early rescue administration of surfactant, ventilation with gentler modes to minimize damage to the immature lungs, and the other supportive therapies have significantly decreased respiratory distress syndrome-related morbidity and mortality. This guideline was addressed to overview the mentioned improvements in order to standardize respiratory distress syndrome management in neonatal intensive care units in Turkey.

Phospholipid components of the synthetic pulmonary surfactant CHF5633 probed by fluorescence spectroscopy

CHF5633 (Chiesi Farmaceutici, Italy) is a synthetic pulmonary surfactant currently under clinical development for the treatment of Respiratory Distress Syndrome in premature infants. The product is composed of phospholipids in liposomal organization, together with two peptide analogues of human surfactant proteins B and C. Phospholipids in liposomes can undergo oxidation of unsaturated lipids and hydrolysis, with formation of fatty acids and lysolipids, both affecting the physico-chemical properties of the formulation. We exploited two fluorescence probes, Prodan and ADIFAB, to evaluate the stability of the phospholipid components of CHF5633. While Prodan enters the phospholipid bilayer and probes the polarity of this environment, ADIFAB binds free fatty acids in the aqueous phase, allowing to determine their concentration. Changes of Prodan fluorescence emission indicated an increase in the polarity of the phospholipid bilayer as a function of time. This behavior is coupled with an increase in fatty acids concentration in the aqueous phase, as determined by ADIFAB, and an increase in lysolipids concentration, as determined by HPLC-MS. Prodan and ADIFAB resulted efficient probes to monitor phospholipids hydrolysis in liposomes, reporting an increased stability of CHF5633 at pH values higher than 6.5.

Surfactant, steroids and non-invasive ventilation in the prevention of BPD

Bronchopulmonary dysplasia (BPD) is a complex disorder with multiple factors implicated in its etiopathogenesis. Despite the scientific advances in the field of neonatology, the incidence of BPD has remained somewhat constant due to increased survival of extremely premature infants. Surfactant deficiency in the immature lung, exposure to invasive mechanical ventilation leading to volutrauma, barotrauma and lung inflammation are some of the critical contributing factors to the pathogenesis of BPD. Hence, strategies to prevent BPD in the postnatal period revolve around mitigation of this injury and inflammation. This article reviews the progress made in the last 5 years in the development of new preparations of surfactant, use of corticosteroids and non-invasive ventilation in the prevention of BPD. Emerging techniques of surfactant delivery through minimally invasive and non-invasive routes are also discussed.

Pulmonary surfactant and drug delivery: Focusing on the role of surfactant proteins

Pulmonary surfactant (PS) has been extensively studied because of its primary role in mammalian breathing. The deposition of this surface-active material at the alveolar air-water interface is essential to lower surface tension, thus avoiding alveolar collapse during expiration. In addition, PS is involved in host defense, facilitating the clearance of potentially harmful particulates. PS has a unique composition, including 92% of lipids and 8% of surfactant proteins (SPs) by mass. Although they constitute the minor fraction, SPs to a large extent orchestrate PS-related functions. PS contains four surfactant proteins (SPs) that can be structurally and functionally divided in two groups, i.e. the large hydrophilic SP-A and SP-D and the smaller hydrophobic SP-B and SP-C. The former belong to the family of collectins and are involved in opsonization processes, thus promoting uptake of pathogens and (nano)particles by phagocytic cell types. The latter SPs regulate interfacial surfactant adsorption dynamics, facilitating (phospho)lipid transfer and membrane fusion processes. In the context of pulmonary drug delivery, the exploitation of PS as a carrier to promote drug spreading along the alveolar interface is gaining interest. In addition, recent studies investigated the interaction of PS with drug-loaded nanoparticles (nanomedicines) following pulmonary administration, which strongly influences their biological fate, drug delivery efficiency and toxicological profile. Interestingly, the specific biophysical mode-of-action of the four SPs affect the drug delivery process of nanomedicines both on the extra-and intracellular level, modulating pulmonary distribution, cell targeting and intracellular delivery. This knowledge can be harnessed to exploit SPs for the design of unique and bio-inspired drug delivery strategies.

Metabolism of a synthetic compared with a natural therapeutic pulmonary surfactant in adult mice

Secreted pulmonary surfactant phosphatidylcholine (PC) has a complex intra-alveolar metabolism that involves uptake and recycling by alveolar type II epithelial cells, catabolism by alveolar macrophages, and loss up the bronchial tree. We compared the in vivo metabolism of animal-derived poractant alfa (Curosurf) and a synthetic surfactant (CHF5633) in adult male C57BL/6 mice. The mice were dosed intranasally with either surfactant (80 mg/kg body weight) containing universally ¹³C-labeled dipalmitoyl PC (DPPC) as a tracer. The loss of [U¹³C]DPPC from bronchoalveolar lavage and lung parenchyma, together with the incorporation of ¹³C-hydrolysis fragments into new PC molecular species, was monitored by electrospray ionization tandem mass spectrometry. The catabolism of CHF5633 was considerably delayed compared with poractant alfa, the hydrolysis products of which were cleared more rapidly. There was no selective resynthesis of DPPC and, strikingly, acyl remodeling resulted in preferential synthesis of polyunsaturated PC species. In conclusion, both surfactants were metabolized by similar pathways, but the slower catabolism of CHF5633 resulted in longer residence time in the airways and enhanced recycling of its hydrolysis products into new PC species.

Quenching of tryptophan fluorescence in a highly scattering solution: Insights on protein localization in a lung surfactant formulation

CHF5633 (Chiesi Farmaceutici, Italy) is a synthetic surfactant developed for respiratory distress syndrome replacement therapy in pre-term newborn infants. CHF5633 contains two phospholipids (dipalmitoylphosphatidylcholine and 1-palmitoyl-2oleoyl-sn-glycero-3-phosphoglycerol sodium salt), and peptide analogues of surfactant protein C (SP-C analogue) and surfactant protein B (SP-B analogue). Both proteins are fundamental for an optimal surfactant activity in vivo and SP-B genetic deficiency causes lethal respiratory failure after birth. Fluorescence emission of the only tryptophan residue present in SP-B analogue (SP-C analogue has none) could in principle be exploited to probe SP-B analogue conformation, localization and interaction with other components of the pharmaceutical formulation. However, the high light scattering activity of the multi-lamellar vesicles suspension characterizing the pharmaceutical surfactant formulation represents a challenge for such studies. We show here that quenching of tryptophan fluorescence and Singular Value Decomposition analysis can be used to accurately calculate and subtract background scattering. The results indicate, with respect to Trp microenvironment, a conformationally homogeneous population of SP-B. Trp is highly accessible to the water phase, suggesting a surficial localization on the membrane of phospholipid vesicles, similarly to what observed for full length SP-B in natural lung surfactant, and supporting an analogous role in protein anchoring to the lipid phase.

Effective in vivo treatment of acute lung injury with helical, amphipathic peptoid mimics of pulmonary surfactant proteins

Acute lung injury (ALI) leads to progressive loss of breathing capacity and hypoxemia, as well as pulmonary surfactant dysfunction. ALI's pathogenesis and management are complex, and it is a significant cause of morbidity and mortality worldwide. Exogenous surfactant therapy, even for research purposes, is impractical for adults because of the high cost of current surfactant preparations. Prior in vitro work has shown that poly-N-substituted glycines (peptoids), in a biomimetic lipid mixture, emulate key biophysical activities of lung surfactant proteins B and C at the air-water interface. Here we report good in vivo efficacy of a peptoid-based surfactant, compared with extracted animal surfactant and a synthetic lipid formulation, in a rat model of lavage-induced ALI. Adult rats were subjected to whole-lung lavage followed by administration of surfactant formulations and monitoring of outcomes. Treatment with a surfactant protein C mimic formulation improved blood oxygenation, blood pH, shunt fraction, and peak inspiratory pressure to a greater degree than surfactant protein B mimic or combined formulations. All peptoid-enhanced treatment groups showed improved outcomes compared to synthetic lipids alone, and some formulations improved outcomes to a similar extent as animal-derived surfactant. Robust biophysical mimics of natural surfactant proteins may enable new medical research in ALI treatment.

In vitro and in vivo characterization of poractant alfa supplemented with budesonide for safe and effective intratracheal administration

BackgroundThe intratracheal (IT) administration of budesonide using surfactant as a vehicle has been shown to reduce the incidence of bronchopulmonary dysplasia (BPD) in preterm infants. The objective of this study was to characterize the in vitro characteristics and in vivo safety and efficacy of the extemporaneous combination of budesonide and poractant alfa.MethodsThe stability, minimum surface tension, and viscosity of the preparation were evaluated by means of high-performance liquid chromatography (HPLC), Wilhelmy balance, and Rheometer, respectively. The safety and efficacy of the IT administration of the mixture were tested in two respiratory distress syndrome (RDS) animal models: twenty-seventh day gestational age premature rabbits and surfactant-depleted adult rabbits.ResultsA pre-formulation trial identified a suitable procedure to ensure the homogeneity and stability of the formulation. Wilhelmy Balance tests clarified that budesonide supplementation has no detrimental effect on poractant alfa surface tension activity. The addition of budesonide to poractant alfa did not affect the physiological response to surfactant treatment in both RDS animal models, and was associated to a significant reduction of lung inflammation in surfactant-depleted rabbits.ConclusionOur in vitro and in vivo analysis suggests that the IT administration of a characterized extemporaneous combination of poractant alfa and budesonide is a safe and efficacious procedure in the context of RDS.

A first-in-human clinical study of a new SP-B and SP-C enriched synthetic surfactant (CHF5633) in preterm babies with respiratory distress syndrome

OBJECTIVE

CHF5633 (Chiesi Farmaceutici S.p.A., Parma, Italy) is the first fully synthetic surfactant enriched by peptide analogues of two human surfactant proteins. We planned to assess safety and tolerability of CHF5633 and explore preliminary efficacy.

DESIGN

Multicentre cohort study.

PATIENTS

Forty infants from 27⁺⁰ to 33⁺⁶ weeks gestation with respiratory distress syndrome requiring fraction of inspired oxygen (FiO₂) ≥0.35 were treated with a single dose of CHF5633 within 48 hours after birth. The first 20 received 100 mg/kg and the second 20 received 200 mg/kg.

OUTCOME MEASURES

Adverse events (AEs) and adverse drug reactions (ADRs) were monitored with complications of prematurity considered AEs if occurring after dosing. Systemic absorption and immunogenicity were assessed. Efficacy was assessed by change in FiO₂ after dosing and need for poractant-alfa rescue.

RESULTS

Rapid and sustained improvements in FiO₂ were observed in 39 (98%) infants. One responded neither to CHF5633 nor two poractant-alfa doses. A total of 79 AEs were experienced by 19 infants in the 100 mg/kg cohort and 53 AEs by 20 infants in the 200 mg/kg cohort. Most AEs were expected complications of prematurity. Two unrelated serious AEs occurred in the second cohort. One infant died of necrotising enterocolitis and another developed viral bronchiolitis after discharge. The single ADR was an episode of transient endotracheal tube obstruction following a 200 mg/kg dose. Neither systemic absorption, nor antibody development to either peptide was detected.

CONCLUSIONS

Both CHF5633 doses were well tolerated and showed promising clinical efficacy profile. These encouraging data provide a basis for ongoing randomised controlled trials.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01651637.

Efficient Interfacially Driven Vehiculization of Corticosteroids by Pulmonary Surfactant

Pulmonary surfactant is a crucial system to stabilize the respiratory air-liquid interface. Furthermore, pulmonary surfactant has been proposed as an effective method for targeting drugs to the lungs. However, few studies have examined in detail the mechanisms of incorporation of drugs into surfactant, the impact of the presence of drugs on pulmonary surfactant performance at the interface under physiologically meaningful conditions, or the ability of pulmonary surfactant to use the air-liquid interface to vehiculise drugs to long distances. This study focuses on the ability of pulmonary surfactant to interfacially vehiculize corticosteroids such as beclomethasone dipropionate (BDP) or Budesonide (BUD) as model drugs. The main objectives have been to (a) characterize the incorporation of corticosteroids into natural and synthetic surfactants, (b) evaluate whether the presence of corticosteroids affects surfactant functionality, and (c) determine whether surfactant preparations enable the efficient spreading and distribution of BDP and BUD along the air-liquid interface. We have compared the performance of a purified surfactant from porcine lungs and two clinical surfactants: Poractant alfa, a natural surfactant of animal origin extensively used to treat premature babies, and CHF5633, a new synthetic surfactant preparation currently under clinical trials. Both, natural and clinical surfactants spontaneously incorporated corticosteroids up to at least 10% by mass with respect to phospholipid content. The presence of the drugs did not interfere with their ability to efficiently adsorb into air-liquid interfaces and form surface active films able to reach and sustain very low surface tensions (<2 mN/m) under compression-expansion cycling mimicking breathing dynamics. Furthermore, the combination of clinical surfactant with corticosteroids efficiently promoted the active diffusion of the drug to long distances along the air-liquid interface. This effect could not be mimicked by vehiculisation of corticosteroids in liposomes or in micellar emulsions similar to the formulations currently in use to deliver anti-inflammatory corticosteroids through inhalation.

Cerebral and lung effects of a new generation synthetic surfactant with SP-B and SP-C analogs in preterm lambs

BACKGROUND

Though natural surfactants (SF) are clinically superior to protein-free synthetic preparations, CHF-5633, a synthetic SF containing SP-B and SP-C analog peptides is a potential alternative to natural SF for treating neonatal respiratory distress syndrome (RDS). Nevertheless, information is lacking regarding the safety of this new treatment for the neonatal brain. We sought to compare the cerebral and pulmonary effects of this new synthetic surfactant (CHF5633) with those of natural porcine surfactant (Cursosurf) in premature lambs with RDS.

METHODS

Twenty-one preterm lambs were randomly assigned to receive CHF5633, Curosurf, or no treatment (control). Pulmonary (gas exchange, lung mechanics) and cerebral (carotid artery blood flow, cerebral oxygen metabolism) effects were measured every 30 min for 6 h. Pulmonary and cerebral histological analysis were also performed.

RESULTS

After delivery, lambs developed severe RDS (F_IO2 :1, pH < 7.15, P_aCO2  > 70 mmHg, P_aO2  < 40 mmHg, C_dyn  < 0.1 mL/cmH₂ O/kg). By 30 min after treatment, animals in both SF-treated groups had consistently better gas exchange and lung mechanics than controls. After CHF5633 administration, P_aCO2 , carotid artery blood flow, and cerebral oxygen delivery tended to slowly decrease compared to other groups. By 2 h, SF-treated groups had similar values of all parameters studied, these remaining steady for the rest of the experiment. Lambs administered CHF5633 obtained better lung and brain injury scores than controls.

CONCLUSION

Intratracheal administration of a bolus of CHF5633 improves pulmonary status in preterm lambs with severe RDS, obtaining better lung and brain injury scores than controls and favorable cerebral hemodynamics, comparable to those with gold standard Curosurf treatment.

Efficient protein production inspired by how spiders make silk

Membrane proteins are targets of most available pharmaceuticals, but they are difficult to produce recombinantly, like many other aggregation-prone proteins. Spiders can produce silk proteins at huge concentrations by sequestering their aggregation-prone regions in micellar structures, where the very soluble N-terminal domain (NT) forms the shell. We hypothesize that fusion to NT could similarly solubilize non-spidroin proteins, and design a charge-reversed mutant (NT*) that is pH insensitive, stabilized and hypersoluble compared to wild-type NT. NT*-transmembrane protein fusions yield up to eight times more of soluble protein in Escherichia coli than fusions with several conventional tags. NT* enables transmembrane peptide purification to homogeneity without chromatography and manufacture of low-cost synthetic lung surfactant that works in an animal model of respiratory disease. NT* also allows efficient expression and purification of non-transmembrane proteins, which are otherwise refractory to recombinant production, and offers a new tool for reluctant proteins in general.

In Vivo Evaluation of the Acute Pulmonary Response to Poractant Alfa and Bovactant Treatments in Lung-Lavaged Adult Rabbits and in Preterm Lambs with Respiratory Distress Syndrome

BACKGROUND

Poractant alfa (Curosurf^®) and Bovactant (Alveofact^®) are two animal-derived pulmonary surfactants preparations approved for the treatment of neonatal respiratory distress syndrome (nRDS). They differ in their source, composition, pharmaceutical form, and clinical dose. How much these differences affect the acute pulmonary response to treatment is unknown.

OBJECTIVES

Comparing these two surfactant preparations in two different animal models of respiratory distress focusing on the short-term response to treatment.

METHODS

Poractant alfa and Bovactant were administered in a 50-200 mg/kg dose range to surfactant-depleted adult rabbits with acute respiratory distress syndrome induced by lavage and to preterm lambs (127-129 days gestational age) with nRDS induced by developmental immaturity. The acute impact of surfactant therapy on gas exchange and pulmonary mechanics was assessed for 1 h in surfactant-depleted rabbits and for 3 h in preterm lambs.

RESULTS

Overall, treatment with Bovactant 50 mg/kg or Poractant alfa 50 mg/kg did not achieve full recovery of the rabbits' respiratory conditions, as indicated by significantly lower arterial oxygenation and carbon dioxide values. By contrast, the two approved doses for clinical use of Poractant alfa (100 and 200 mg/kg) achieved a rapid and sustained recovery in both animal models. The comparison of the ventilation indices of the licensed doses of Bovactant (50 mg/kg) and Poractant alfa (100 mg/kg) showed a superior performance of the latter preparation in both animal models. At equal phospholipid doses, Poractant alfa was superior to Bovactant in terms of arterial oxygenation in both animal models. In preterm lambs, surfactant replacement therapy with Poractant alfa at either 100 or 200 mg/kg was associated with significantly higher lung gas volumes compared to Bovactant treatment with 100 mg/kg.

CONCLUSION

At the licensed doses, the acute pulmonary response to Poractant alfa was significantly better than the one observed after Bovactant treatment, either at 50 or at 100 mg/kg dose, in two animal models of pulmonary failure.