In vivo effect of pneumonia on surfactant disaturated-phosphatidylcholine kinetics in newborn infants

Pulmonary Surfactant in Adult ARDS: Current Perspectives and Future Directions

Acute respiratory distress syndrome (ARDS) is a major cause of hypoxemic respiratory failure in adults, leading to the requirement for mechanical ventilation and poorer outcomes. Dysregulated surfactant metabolism and function are characteristic of ARDS. A combination of alveolar epithelial damage leading to altered surfactant synthesis, secretion, and breakdown with increased functional inhibition from overt alveolar inflammation contributes to the clinical features of poor alveolar compliance and alveolar collapse. Quantitative and qualitative alterations in the bronchoalveolar lavage and tracheal aspirate surfactant composition contribute to ARDS pathogenesis. Compared to neonatal respiratory distress syndrome (nRDS), replacement studies of exogenous surfactants in adult ARDS suggest no survival benefit. However, these studies are limited by disease heterogeneity, variations in surfactant preparations, doses, and delivery methods. More importantly, the lack of mechanistic understanding of the exact reasons for dysregulated surfactant remains a significant issue. Moreover, studies suggest an extremely short half-life of replaced surfactant, implying increased catabolism. Refining surfactant preparations and delivery methods with additional co-interventions to counteract surfactant inhibition and degradation has the potential to enhance the biophysical characteristics of surfactant in vivo.

The value of Pediatric Early Warning Score combined with SBAR in neonatal pneumonia nursing: A retrospective cohort study

To observe the effect of the Pediatric Early Warning System (PEWS) score combined with the situation-background-assessment-recommendation (SBAR) shift communication system in neonates with severe pneumonia in the pediatric intensive care unit. A total of 230 neonates admitted to the pediatric intensive care unit of our hospital from January 2018 to January 2021 were enrolled in this study. Participants were divided into an experimental group (110 patients, PEWS score combined with SBAR shift communication system) and a control group (120 patients, routine diagnosis and treatment and shift change). The early recognition rate, incidence of handover problems, and prognosis of critically ill children in the 2 groups were analyzed. Compared to the control group, the correct recognition rate of disease observation and early recognition rate of critically ill children in the experimental group were significantly higher, and the incidence of handover problems was significantly lower (P < .05). There was no significant difference in the incidence of asphyxia, heart failure, and toxic encephalopathy between both groups. The application of the PEWS score combined with the SBAR shift communication system can facilitate timely identification of deterioration of the condition of children with severe pneumonia, reduce handover problems, and help to implement interventions or rescue according to the changes in a patient's condition, which may be beneficial in improving the patient's prognosis.

A novel deuterium-based model for measurement of exogenous surfactant using deuterium-depleted water

Stable isotope tracers, like ¹³ C, can be used for the measurement of the partition between the endogenous and exogenous pulmonary disaturated-phosphatidylcholine (DSPC). Deuterium labeling methods are still not fully explored. Our aim was to investigate the feasibility of using deuterium-depleted water (DDW) and deuterium-enriched water (DEW) to measure endogenous and exogenous pulmonary DSPC in a rabbit model of surfactant depletion. Data obtained from the ¹³ C dilution method were used as a reference. We studied 9 adult rabbits: 4 drank DDW and 5 DEW for 5 days. Lung surfactant depletion was induced at Day 5 by repeated saline bronchoalveolar lavages (BAL), which were stored as a pool (BAL pool). After endogenous surfactant depletion, rabbits received exogenous surfactant followed by a second BAL depletion procedure (End-Experiment Pool). DSPC quantity, and palmitic acid (PA)-DSPC ² H/¹ H (δ² H) and ¹³ C/¹² C ratios (δ¹³ C) of exogenous surfactant batches and of BAL pools were measured by High-Resolution Mass Spectrometry. The amount of exogenous surfactant recovered from the lungs ranged from 45% to 81% and, it was highly correlated with those obtained with the use of the ¹³ C (r = 0.9844, p < 0.0001). We demonstrated that commercially available purified DDW and even low doses of DEW can be used to modify the deuterium background of endogenous surfactants with the purpose of measuring the contribution of exogenous surfactants to the endogenous alveolar surfactant pool.

Deuterium-depleted water: A new tracer to label pulmonary surfactant lipids in adult rabbits

Stable isotope tracing can be safely used for metabolic studies in animals and humans. The endogenous biosynthesis of lipids (lipogenesis) is a key process throughout the entire life but especially during brain and lung growth. Adequate synthesis of pulmonary surfactant lipids is indispensable for life. With this study, we report the use of deuterium-depleted water (DDW), suitable for human consumption, as metabolic precursor for lipogenesis. We studied 13 adult rabbits for 5 days. Four rabbits drank tap water (TW) and served as controls; in four animals, DDW was substituted to drinking water, whereas five drank deuterium-enriched water (DEW). After 5 days, a blood sample and a bronchoalveolar lavage (BAL) sample were collected. The ² H/¹ H (δ² H) of BAL palmitic acid (PA) desaturated phosphatidylcholine (DSPC), the major phospholipid of pulmonary surfactant, and of plasma water was determined by high-resolution mass spectrometry. We found that the δ² H values of DDW, DEW and TW were -984 ± 2‰, +757 ± 2‰ and -58 ± 1‰, respectively. After 5 days, plasma water values were -467 ± 87‰, +377 ± 56‰ and -53 ± 6‰, and BAL DSPC-PA was -401 ± 27‰, -96 ± 38‰ and -249 ± 9‰ in the DDW, DEW and TW, respectively. With this preliminary study, we demonstrated the feasibility of using DDW to label pulmonary surfactant lipids. This novel approach can be used in animals and in humans, and we speculate that it could be associated with more favourable study compliance than DEW in human studies.

Surfactant lung delivery with LISA and InSurE in adult rabbits with respiratory distress

BACKGROUND

In preterm infants, InSurE (Intubation-Surfactant-Extubation) and LISA (less invasive surfactant administration) techniques allow for exogenous surfactant administration while reducing lung injury associated with mechanical ventilation. We compared the acute pulmonary response and lung deposition of surfactant by LISA and InSurE in surfactant-depleted adult rabbits.

METHODS

Twenty-six spontaneously breathing surfactant-depleted adult rabbits (6-7 weeks old) with moderate RDS and managed with nasal continuous positive airway pressure were randomized to 3 groups: (1) 200 mg/kg of surfactant by InSurE; (2) 200 mg/kg of surfactant by LISA; (3) no surfactant treatment (Control). Gas exchange and lung mechanics were monitored for 180 min. After that, surfactant lung deposition and distribution were evaluated monitoring disaturated-phosphatidylcholine (DSPC) and surfactant protein C (SP-C), respectively.

RESULTS

No signs of recovery were found in the untreated animals. After InSurE, oxygenation improved more rapidly compared to LISA. However, at 180' LISA and InSurE showed comparable outcomes in terms of gas exchange, ventilation parameters, and lung mechanics. Neither DSPC in the alveolar pool nor SP-C signal distributions in a frontal lung section were significantly different between InSurE and LISA groups.

CONCLUSIONS

In an acute setting, LISA demonstrated efficacy and surfactant lung delivery similar to that of InSurE in surfactant-depleted adult rabbits.

IMPACT

Although LISA technique is gaining popularity, there are still several questions to address. This is the first study comparing LISA and InSurE in terms of gas exchange, ventilation parameters, and lung mechanics as well as surfactant deposition and distribution. In our animal study, three hours post-treatment, LISA method seems to be as effective as InSurE and showed similar surfactant lung delivery. Our findings provide some clarifications on a fair comparison between LISA and InSurE techniques, particularly in terms of surfactant delivery. They should reassure some of the concerns raised by the clinical community on LISA adoption in neonatal units.

Streptococcus pneumoniae inhibits purinergic signaling and promotes purinergic receptor P2Y2 internalization in alveolar epithelial cells

Bacterial pneumonia is a global health challenge that causes up to 2 million deaths each year. Purinergic signaling plays a pivotal role in healthy alveolar epithelium. Here, we used fluorophore-based analysis and live-cell calcium imaging to address the question of whether the bacterial pathogen Streptococcus pneumoniae directly interferes with purinergic signaling in alveolar epithelial cells. Disturbed purinergic signaling might result in pathophysiologic changes like edema formation and atelectasis, which are commonly seen in bacterial pneumonia. Purine receptors are mainly activated by ATP, mediating a cytosolic calcium response. We found that this purinergic receptor P2Y₂-mediated response is suppressed in the presence of S. pneumoniae in A549 and isolated primary alveolar cells in a temperature-dependent manner. Downstream inositol 3-phosphate (IP₃) signaling appeared to be unaffected, as calcium signaling via protease-activated receptor 2 remained unaltered. S. pneumoniae-induced suppression of the P2Y₂-mediated calcium response depended on the P2Y₂ phosphorylation sites Ser-243, Thr-344, and Ser-356, which are involved in receptor desensitization and internalization. Spinning-disk live-cell imaging revealed that S. pneumoniae induces P2Y₂ translocation into the cytosol. In conclusion, our results show that S. pneumoniae directly inhibits purinergic signaling by inducing P2Y₂ phosphorylation and internalization, resulting in the suppression of the calcium response of alveolar epithelial cells to ATP, thereby affecting cellular integrity and function.

[Clinical effect of exogenous pulmonary surfactant in the treatment of severe neonatal infectious pneumonia: a multicenter prospective clinical trial]

OBJECTIVE

To study the clinical effect of calsurf, a domestic exogenous pulmonary surfactant, in the treatment of severe neonatal infectious pneumonia.

METHODS

A total of 208 neonates with severe infectious pneumonia who hospitalized in 5 hospitals of China were enrolled. According to their parents' wishes on admission, these neonates were administered with conventional treatment (control group; n=81) and calsurf  treatment + conventional treatment (calsurf treatment group, n=127). The two groups were compared in terms of the degree of oxygen dependence on admission, blood gas parameters before and after treatment, lung ultrasound results, duration of mechanical ventilation, length of hospital stay, hospital costs, complications and prognosis.

RESULTS

Compared with the control group on admission, the calsurf treatment group had significantly higher inhaled oxygen concentration and partial pressure of carbon dioxide and significantly lower arterial partial pressure of oxygen and oxygenation index (P<0.01). After 1 hour of treatment, both groups had significant improvements in the above indices (P<0.05), and the improvements were more significant in the calsurf treatment group (P<0.05). After 4-6 hours of calsurf administration, there was a significant reduction in the degree of pulmonary consolidation. The calsurf treatment group had significantly shorter duration of mechanical ventilation and length of hospital stay than the control group, while there was no significant difference in the incidence rate of complications between the two groups. The neonates of both groups had a good prognosis.

CONCLUSIONS

In neonates with severe infectious pneumonia, calsurf treatment can significantly improve oxygenation, reduce the degree of pulmonary consolidation, and shorten the duration of mechanical ventilation and length of hospital stay. Therefore, it should be considered in neonates with severe infectious pneumonia.

Surfactant status and respiratory outcome in premature infants receiving late surfactant treatment

BACKGROUND

Many premature infants with respiratory failure are deficient in surfactant, but the relationship to occurrence of bronchopulmonary dysplasia (BPD) is uncertain.

METHODS

Tracheal aspirates were collected from 209 treated and control infants enrolled at 7-14 days in the Trial of Late Surfactant. The content of phospholipid, surfactant protein B, and total protein were determined in large aggregate (active) surfactant.

RESULTS

At 24 h, surfactant treatment transiently increased surfactant protein B content (70%, p < 0.01), but did not affect recovered airway surfactant or total protein/phospholipid. The level of recovered surfactant during dosing was directly associated with content of surfactant protein B (r = 0.50, p < 0.00001) and inversely related to total protein (r = 0.39, p < 0.0001). For all infants, occurrence of BPD was associated with lower levels of recovered large aggregate surfactant, higher protein content, and lower SP-B levels. Tracheal aspirates with lower amounts of recovered surfactant had an increased proportion of small vesicle (inactive) surfactant.

CONCLUSIONS

We conclude that many intubated premature infants are deficient in active surfactant, in part due to increased intra-alveolar metabolism, low SP-B content, and protein inhibition, and that the severity of this deficit is predictive of BPD. Late surfactant treatment at the frequency used did not provide a sustained increase in airway surfactant.

Surfactant Components and Tracheal Aspirate Inflammatory Markers in Preterm Infants with Respiratory Distress Syndrome

In 93 preterm infants ≤32 weeks of gestational age and 12 control infants, epithelial lining fluid disaturated-phosphatidylcholine, surfactant protein A and B, albumin, and myeloperoxidase activity were assessed after intubation and before exogenous surfactant administration. We found that disaturated-phosphatidylcholine, surfactant protein B, and myeloperoxidase were significantly higher in preterms with chorioamnionitis.

Surfactant Therapy for Early Onset Pneumonia in Late Preterm and Term Neonates Needing Mechanical Ventilation

INTRODUCTION

Pathophysiology of pneumonia involves leakage of plasma proteins into the airways and accumulation of cytokines within the lung. Several in vitro and in vivo studies have demonstrated that this proteinaceous material and lung inflammation inhibit surfactant function.

AIM

To evaluate whether exogenous surfactant therapy improves oxygenation and gas exchange in late preterm and term neonates with early onset pneumonia and respiratory failure.

MATERIALS AND METHODS

This prospective interventional cohort study was conducted at a tertiary care neonatal unit. Twenty four late preterm and term neonates with early onset pneumonia requiring mechanical ventilation for respiratory failure were included and received surfactant therapy. Oxygenation index, arterial/alveolar PO₂ (a/A ratio), mean airway pressure and fraction of inspired oxygen were calculated from arterial blood gases obtained before and after surfactant therapy. Wilcoxon signed rank sum test was used for assessment of change in oxygenation variables 12 hours after surfactant therapy. Data regarding clinical outcomes and complications were collected and analysed.

RESULTS

Just over half (54.2%) of the study neonates were of term gestation. After surfactant therapy, the median Oxygenation Index (OI) decreased from 11.15 to 3.7 at one hour and the change was sustained and significant at 12 hours (p<0.05). The median a/A PO₂ ratio improved from 0.09 to 0.3 within one hour of surfactant replacement and the improvement was significant at 12 hours (p<0.01). Twenty two neonates (92%) survived to discharge. Median duration of hospital stay was 15 days.

CONCLUSION

Significant and rapid improvement in oxygenation in late preterm and term neonates with early onset pneumonia was seen after surfactant therapy, which is sustained for a longer period. There could be a substantial role for the use of surfactant in early onset pneumonia, although larger controlled trials are needed before definite recommendations can be made.

Surfactant Replacement Therapy Beyond Respiratory Distress Syndrome in Neonates

BACKGROUND

Surfactant replacement therapy is an established modality of treatment in preterm neonates with respiratory distress syndrome. In addition, there are various neonatal respiratory disorders which are characterized by surfactant deficiency in which surfactant therapy can be a feasible and safe option.

OBJECTIVE

To collate the literature on the use of surfactant replacement therapy in neonates beyond respiratory distress syndrome and examine the evidence and newer developments.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, and EMBASE up to June 2015; and previous reviews, including cross-references, abstracts, and conference proceedings.

RESULTS

Evidence supports surfactant administration via bolus route in neonates with meconium aspiration syndrome, but additional robust evidence is required before its adoption in clinical practice. There is limited evidence to support surfactant therapy in neonates with pneumonia, pulmonary hemorrhage and bronchopulmonary dysplasia. Large multicenter randomized trials are needed to cement or refute the role of surfactant therapy in these disorders.

Investigation of urine proteome of preterm newborns with respiratory pathologies

A serious problem during intensive care and nursing of premature infants is the invasiveness of many examination methods. Urine is an excellent source of potential biomarkers due to the safety of the collection procedure. The purpose of this study was to determine the features specific for the urine proteome of preterm newborns and their changes under respiratory pathologies of infectious and non-infectious origin. The urine proteome of 37 preterm neonates with respiratory diseases and 10 full-term newborns as a control group were investigated using the LC-MS/MS method. The total number of identified proteins and unique peptides was 813 and 3672 respectively. In order to further specify the defined infant-specific dataset these proteins were compared with urine proteome of healthy adults (11 men and 11 pregnant women) resulting in 94 proteins found only in infants. Pairwise analysis performed for label-free proteomic data revealed 36 proteins which reliably distinguished newborns with respiratory disorders of infectious genesis from those with non-infectious pathologies, including: proteins involved in cell adhesion (CDH-2,-5,-11, NCAM1, TRY1, DSG2), metabolism (LAMP1, AGRN, TPP1, GPX3, APOD, CUBN, IDH1), regulation of enzymatic activity (SERPINA4, VASN, GAPDH), inflammatory and stress response (CD55, CD 93, NGAL, HP, TNFR, LCN2, AGT, S100P, SERPINA1/C1/B1/F1).

Proteomic Analysis of the Urine for Diagnostics in Newborns

Proteomic analysis of the urine was used for noninvasive diagnostics of abnormalities in newborns treated in the neonatal intensive care unit. This approach can be used to differentiate between infectious and noninfectious respiratory disorders.

Surfactant protein B and A concentrations are increased in neonatal pneumonia

BACKGROUND

Term newborns with pneumonia show a reduced pulmonary compliance due to multiple and ill-defined factors. Surfactant proteins' (SPs) changes could have a role in the reduced compliance but the matter is still unsettled. The aim of this study was to clarify the meaning of SPs changes during pneumonia in term newborns.

METHODS

In 28 term ventilated newborns, 13 with pneumonia and 15 with no lung disease, we measured SP-B, SP-A, disaturated-phosphatidylcholine (DSPC), and total phospholipids (PL) concentrations in tracheal aspirates at intubation and close to extubation. We also measured DSPC kinetics using (U-(13)C-PA)dipalmitoyl-phosphatidylcholine.

RESULTS

At baseline, SP-B, expressed as % of PL, was significantly different between the groups, being 3.5-fold higher in pneumonia than controls. Conversely, SP-A did not vary between the groups. At extubation, SP-B and SP-A concentrations had decreased significantly in newborns with pneumonia, while there was no significant change in controls. DSPC t1/2 was significantly shorter in the pneumonia group (11.8 (5.5-19.8) h vs. 26.6 (19.3-63.6) h, P = 0.011).

CONCLUSION

In term newborns with pneumonia, SP-B increases with respect to PL, and DSPC is turned over at a faster rate. Disease's resolution is associated with the restoration of the normal ratio between SP-B and PL.