SFTPB in serum extracellular vesicles as a biomarker of progressive pulmonary fibrosis.

Progressive pulmonary fibrosis (PPF), defined as the worsening of various interstitial lung diseases (ILDs), currently lacks useful biomarkers. To identify novel biomarkers for early detection of patients at risk of PPF, we performed a proteomic analysis of serum extracellular vesicles (EVs). Notably, the identified candidate biomarkers were enriched for lung-derived proteins participating in fibrosis-related pathways. Among them, pulmonary surfactant-associated protein B (SFTPB) in serum EVs could predict ILD progression better than the known biomarkers, serum KL-6 and SP-D, and it was identified as an independent prognostic factor from ILD-gender-age-physiology index. Subsequently, the utility of SFTPB for predicting ILD progression was evaluated further in 2 cohorts using serum EVs and serum, respectively, suggesting that SFTPB in serum EVs but not in serum was helpful. Among SFTPB forms, pro-SFTPB levels were increased in both serum EVs and lungs of patients with PPF compared with those of the control. Consistently, in a mouse model, the levels of pro-SFTPB, primarily originating from alveolar epithelial type 2 cells, were increased similarly in serum EVs and lungs, reflecting pro-fibrotic changes in the lungs, as supported by single-cell RNA sequencing. SFTPB, especially its pro-form, in serum EVs could serve as a biomarker for predicting ILD progression.

Disfunciones del metabolismo del surfactante pulmonar: caso clínico pediátrico / Pulmonary surfactant metabolism dysfunction: A pediatric clinical case report

Las enfermedades pulmonares intersticiales son patologías poco frecuentes en pediatría. Dentro de ellas, se incluyen las disfunciones del metabolismo del surfactante pulmonar, molécula anfipática cuya función es disminuir la tensión superficial y evitar el colapso alveolar. Se presenta el caso de un lactante de 6 meses, en seguimiento por bajo peso, que presentó dificultad respiratoria aguda y cianosis; la radiografía de tórax evidenció infiltrado intersticial, neumomediastino y neumotórax bilateral. Al interrogatorio, surgió antecedente materno de internación al año de vida, con requerimiento de oxigenoterapia prolongada y diagnóstico desconocido; presenta signos de hipoxia crónica. El paciente cursó internación con requerimiento de oxigenoterapia. Se realizaron estudios complementarios en búsqueda de etiología, sin resultados positivos. La tomografía de tórax evidenció opacidades en vidrio esmerilado, engrosamiento del intersticio septal y áreas de atrapamiento aéreo; con resultado de biopsia pulmonar y estudio genético se llegó al diagnóstico de disfunción del metabolismo del surfactante pulmonar.

Interstitial lung diseases are rare in pediatrics. They include dysfunctions in the metabolism of pulmonary surfactant, an amphipathic molecule that reduces surface tension and prevents alveolar collapse. Here we describe the case of a 6-month-old infant controlled for low weight, who presented with acute respiratory distress and cyanosis; his chest X-ray showed interstitial infiltrate, pneumomediastinum, and bilateral pneumothorax. During history-taking, it was noted that his mother had a history of hospitalization at 1 year old with unknown diagnosis, requiring prolonged oxygen therapy; she now shows signs of chronic hypoxia. The patient was hospitalized and required oxygen therapy. Ancillary tests were done to look for the etiology of the condition, with no positive results. A chest computed tomography showed groundglass opacities, thickening of the septal interstitium, and areas of air trapping; based on the results of a lung biopsy and a genetic study, pulmonary surfactant metabolism dysfunction was diagnosed.

Evaluating Novel SP-B and SP-C Synthetic Analogues for Pulmonary Surfactant Efficacy.

Pulmonary surfactants, a complex assembly of phospholipids and surfactant proteins such as SP-B and SP-C, are critical for maintaining respiratory system functionality by lowering surface tension (ST) and preventing alveolar collapse. Our study introduced five synthetic SP-B peptides and one SP-C peptide, leading to the synthesis of CHAsurf candidates (CHAsurf-1 to CHAsurf-5) for evaluation. We utilized a modified Wilhelmy balance test to assess the surface tension properties of the surfactants, measuring spreading rate, surface adsorption, and ST-area diagrams to comprehensively evaluate their performance. Animal experiments were performed on New Zealand white rabbits to test the efficacy of CHAsurf-4B, a variant chosen for its economic viability and promising ST reduction properties, comparable to Curosurf®. The study confirmed that higher doses of SP-B in CHAsurf-4 are associated with improved ST reduction. However, due to cost constraints, CHAsurf-4B was selected for in vivo assessment. The animal model revealed that CHAsurf-4B could restore alveolar structure and improve lung elasticity, akin to Curosurf®. Our research highlights the significance of cysteine residues and disulfide bonds in the structural integrity and function of synthetic SP-B analogues, offering a foundation for future surfactant therapy in respiratory disorders. This study's findings support the potential of CHAsurf-4B as a therapeutic agent, meriting further investigation to solidify its role in clinical applications.

Lung molecular and histological changes in type 2 diabetic rats and its improvement by high-intensity interval training.

BACKGROUND: Type 2 diabetes (T2D) leads to serious respiratory problems. This study investigated the effectiveness of high-intensity interval training (HIIT) on T2D-induced lung injuries at histopathological and molecular levels. METHODS: Forty-eight male Wistar rats were randomly allocated into control (CTL), Diabetes (Db), exercise (Ex), and Diabetes + exercise (Db + Ex) groups. T2D was induced by a high-fat diet plus (35 mg/kg) of streptozotocin (STZ) administration. Rats in Ex and Db + Ex performed HIIT for eight weeks. Tumor necrosis factor-alpha (TNFα), Interleukin 10 (IL-10), BAX, Bcl2, Lecithin, Sphingomyelin (SPM) and Surfactant protein D (SPD) levels were measured in the bronchoalveolar lavage fluid (BALF) and malondialdehyde (MDA) and total antioxidant capacity (TAC) levels were measured in lung tissue. Lung histopathological alterations were assessed by using H&E and trichrome mason staining. RESULTS: Diabetes was significantly associated with imbalance in pro/anti-inflammatory, pro/anti-apoptosis and redox systems, and reduced the SPD, lecithin sphingomyelin and alveolar number. Performing HIIT by diabetic animals increased Bcl2 (P < 0.05) and IL10 (P < 0.01) levels as well as surfactants components and TAC (P < 0.05) but decreased fasting blood glucose (P < 0.001), TNFα (P < 0.05), BAX (P < 0.05) and BAX/Bcl2 (P < 0.001) levels as well as MDA (P < 0.01) and MDA/TAC (P < 0.01) compared to the diabetic group. Furthermore, lung injury and fibrosis scores were increased by T2D and recovered in presence of HIIT. CONCLUSION: These findings suggested that the attenuating effect of HIIT on diabetic lung injury mediated by reducing blood sugar, inflammation, oxidative stress, and apoptosis as well as improving pulmonary surfactants components.

Pulmonary surfactant metabolism dysfunction: A pediatric clinical case report. / Disfunciones del metabolismo del surfactante pulmonar: caso clínico pediátrico.

Interstitial lung diseases are rare in pediatrics. They include dysfunctions in the metabolism of pulmonary surfactant, an amphipathic molecule that reduces surface tension and prevents alveolar collapse. Here we describe the case of a 6-month-old infant controlled for low weight, who presented with acute respiratory distress and cyanosis; his chest X-ray showed interstitial infiltrate, pneumomediastinum, and bilateral pneumothorax. During history-taking, it was noted that his mother had a history of hospitalization at 1 year old with unknown diagnosis, requiring prolonged oxygen therapy; she now shows signs of chronic hypoxia. The patient was hospitalized and required oxygen therapy. Ancillary tests were done to look for the etiology of the condition, with no positive results. A chest computed tomography showed groundglass opacities, thickening of the septal interstitium, and areas of air trapping; based on the results of a lung biopsy and a genetic study, pulmonary surfactant metabolism dysfunction was diagnosed.

Las enfermedades pulmonares intersticiales son patologías poco frecuentes en pediatría. Dentro de ellas, se incluyen las disfunciones del metabolismo del surfactante pulmonar, molécula anfipática cuya función es disminuir la tensión superficial y evitar el colapso alveolar. Se presenta el caso de un lactante de 6 meses, en seguimiento por bajo peso, que presentó dificultad respiratoria aguda y cianosis; la radiografía de tórax evidenció infiltrado intersticial, neumomediastino neumotórax bilateral. Al interrogatorio, surgió antecedente materno de internación al año de vida, con requerimiento de oxigenoterapia prolongada y diagnóstico desconocido; presenta signos de hipoxia crónica. El paciente cursó internación con requerimiento de oxigenoterapia. Se realizaron estudios complementarios en búsqueda de etiología, sin resultados positivos. La tomografía de tórax evidenció opacidades en vidrio esmerilado, engrosamiento del intersticio septal y áreas de atrapamiento aéreo; con resultado de biopsia pulmonar y estudio genético se llegó al diagnóstico de disfunción del metabolismo del surfactante pulmonar.

Mechanosensitive channels TMEM63A and TMEM63B mediate lung inflation-induced surfactant secretion.

Pulmonary surfactant is a lipoprotein complex lining the alveolar surface to decrease the surface tension and facilitate inspiration. Surfactant deficiency is often seen in premature infants and in children and adults with respiratory distress syndrome. Mechanical stretch of alveolar type 2 epithelial (AT2) cells during lung expansion is the primary physiological factor that stimulates surfactant secretion; however, it is unclear whether there is a mechanosensor dedicated to this process. Here, we show that loss of the mechanosensitive channels TMEM63A and TMEM63B (TMEM63A/B) resulted in atelectasis and respiratory failure in mice due to a deficit of surfactant secretion. TMEM63A/B were predominantly localized at the limiting membrane of the lamellar body (LB), a lysosome-related organelle that stores pulmonary surfactant and ATP in AT2 cells. Activation of TMEM63A/B channels during cell stretch facilitated the release of surfactant and ATP from LBs fused with the plasma membrane. The released ATP evoked Ca2+ signaling in AT2 cells and potentiated exocytic fusion of more LBs. Our study uncovered a vital physiological function of TMEM63 mechanosensitive channels in preparing the lungs for the first breath at birth and maintaining respiration throughout life.

Neonatal surfactant therapy beyond respiratory distress syndrome.

Whilst exogenous surfactant therapy is central to the management of newborn infants with respiratory distress syndrome, its use in other neonatal lung diseases remains inconsistent and controversial. Here we discuss the evidence and experience in relation to surfactant therapy in newborns with other lung conditions in which surfactant may be deficient or dysfunctional, including meconium aspiration syndrome, pneumonia, congenital diaphragmatic hernia and pulmonary haemorrhage. We find that, for all of these diseases, administration of exogenous surfactant as bolus therapy is frequently associated with transient improvement in oxygenation, likely related to temporary mitigation of surfactant inhibition in the airspaces. However, for none of them is there a lasting clinical benefit of surfactant therapy. By virtue of interrupting disease pathogenesis, lavage therapy with dilute surfactant in MAS offers the greatest possibility of a more pronounced therapeutic effect, but this has yet to be definitively proven. Lavage therapy also involves a greater degree of procedural risk.

Comparison of the efficacy of two natural surfactants (BERAKSURF and BLES) in the treatment of respiratory distress syndrome among preterm neonates.

BACKGROUND: The benefit of surfactant replacement therapy for respiratory distress syndrome (RDS) has been demonstrated. However, some surfactants are expensive and usually inaccessible. Consequently, the Iranian Survanta was produced, but its effect on complications and mortality of RDS is unknown. This study aimed to compare the therapeutic outcomes of Iranian surfactant (beraksurf) and BLES (bovine lipid extract surfactant) on RDS treatment among preterm neonates. METHODS: This triple blinded randomized controlled trial study was performed on 128 eligible neonates diagnosed with RDS in Afzalipour hospital in Kerman, Iran. Diagnosis of RDS, gestational age of 28-34 weeks and weight ≥ 1 kg were considered as inclusion criteria. Congenital anomalies such as congenital cyanotic heart diseases, digestive system anomalies and chromosome abnormalities were the exclusion criteria Neonates were randomly assigned into two equal groups: (1) those treated with BLES (n = 64) and (2) those treated with beraksurf (n = 64). Complications including patent ductus arteriosus (PDA), sepsis, intraventricular hemorrhage (IVH), pneumothorax, pulmonary hemorrhage, mortality, and also, the number of days required for invasive mechanical ventilation (using ventilator) and non-invasive continuous positive airway pressure (CPAP) were evaluated for all neonates. The risk ratio (RR) was calculated at 95% of confidence intervals (CI). RESULTS: Compared with BLES group, the RR estimate among neonates in beraksurf group was 0.89 (0.66-1.20) for PDA, 0.71 (0.23-2.13) for IVH, 0.44 (0.14-1.36) for sepsis, 0.35 (0.13-0.93) for pneumothorax, 0.33 (0.12-0.86) for pulmonary hemorrhage, and 0.55 (0.28-1.05) for mortality. CONCLUSIONS: Despite advances in the use of exogenous surfactants for the treatment of neonatal respiratory distress syndrome; There are still some controversial topics in this field. The results obtained in the present study showed that the two types of surfactant (BERAKSURF and BLES) have similar efficacy for the treatment and short-term outcomes in preterm infants with respiratory distress syndrome. Therefore, due to the cost-effectiveness of BRAKSURF compared to BLES, We recommend choosing BERAKSURF in terms of treatment.

Alveolar type II epithelial cell FASN maintains lipid homeostasis in experimental COPD.

Alveolar epithelial type II (AEC2) cells strictly regulate lipid metabolism to maintain surfactant synthesis. Loss of AEC2 cell function and surfactant production are implicated in the pathogenesis of the smoking-related lung disease chronic obstructive pulmonary disease (COPD). Whether smoking alters lipid synthesis in AEC2 cells and whether altering lipid metabolism in AEC2 cells contributes to COPD development are unclear. In this study, high-throughput lipidomic analysis revealed increased lipid biosynthesis in AEC2 cells isolated from mice chronically exposed to cigarette smoke (CS). Mice with a targeted deletion of the de novo lipogenesis enzyme, fatty acid synthase (FASN), in AEC2 cells (FasniΔAEC2) exposed to CS exhibited higher bronchoalveolar lavage fluid (BALF) neutrophils, higher BALF protein, and more severe airspace enlargement. FasniΔAEC2 mice exposed to CS had lower levels of key surfactant phospholipids but higher levels of BALF ether phospholipids, sphingomyelins, and polyunsaturated fatty acid-containing phospholipids, as well as increased BALF surface tension. FasniΔAEC2 mice exposed to CS also had higher levels of protective ferroptosis markers in the lung. These data suggest that AEC2 cell FASN modulates the response of the lung to smoke by regulating the composition of the surfactant phospholipidome.

Use of budesonide associated with a pulmonary surfactant to prevent bronchopulmonary dysplasia in premature newborns - A systematic review

Abstract Objective: Among the mechanisms proposed for the development of bronchopulmonary dysplasia is the increase in the pulmonary inflammatory process and oxidative stress. Thus, the control of this process may result in improvements in bronchopulmonary dysplasia-related outcomes. This study aims to analyze the current scientific evidence regarding the use of budesonide, a potent anti-inflammatory drug, associated with a pulmonary surfactant to prevent bronchopulmonary dysplasia. Methods: A systematic review of the literature was performed on the Embase and MEDLINE platforms, and studies that compared budesonide with pulmonary surfactant versus pulmonary surfactant for treating respiratory distress syndrome were included. The primary outcome was a reduction in bronchopulmonary dysplasia or death. Results: Four randomized clinical trials and two observational studies were included in this systematic review. Three of the randomized clinical trials found a reduction in bronchopulmonary dysplasia or death in the use of budesonide with the surfactant, all the other studies (1 clinical trial and 2 observational studies) found no statistical differences between the groups for the primary outcomes. The three main studies showed a reduction in the primary outcome; however, all studies showed great heterogeneity regarding the type of surfactant (poractant or beractant) and the method of administration. Conclusion: Robust clinical studies, in a heterogeneous population, using porcine surfactant associated with budesonide, with administration by a minimally invasive technique are necessary for there to be a recommendation based on scientific evidence for its widespread use.

Use of budesonide associated with a pulmonary surfactant to prevent bronchopulmonary dysplasia in premature newborns - A systematic review.

OBJECTIVE: Among the mechanisms proposed for the development of bronchopulmonary dysplasia is the increase in the pulmonary inflammatory process and oxidative stress. Thus, the control of this process may result in improvements in bronchopulmonary dysplasia-related outcomes. This study aims to analyze the current scientific evidence regarding the use of budesonide, a potent anti-inflammatory drug, associated with a pulmonary surfactant to prevent bronchopulmonary dysplasia. METHODS: A systematic review of the literature was performed on the Embase and MEDLINE platforms, and studies that compared budesonide with pulmonary surfactant versus pulmonary surfactant for treating respiratory distress syndrome were included. The primary outcome was a reduction in bronchopulmonary dysplasia or death. RESULTS: Four randomized clinical trials and two observational studies were included in this systematic review. Three of the randomized clinical trials found a reduction in bronchopulmonary dysplasia or death in the use of budesonide with the surfactant, all the other studies (1 clinical trial and 2 observational studies) found no statistical differences between the groups for the primary outcomes. The three main studies showed a reduction in the primary outcome; however, all studies showed great heterogeneity regarding the type of surfactant (poractant or beractant) and the method of administration. CONCLUSION: Robust clinical studies, in a heterogeneous population, using porcine surfactant associated with budesonide, with administration by a minimally invasive technique are necessary for there to be a recommendation based on scientific evidence for its widespread use.

Effects of antenatal dexamethasone and postnatal pulmonary surfactant combined with respiratory support on lung fluid clearance in preterm rabbits / 中华围产医学杂志

Objective:To explore the effects of prenatal dexamethasone (DEX), postnatal pulmonary surfactant (PS) and respiratory support on the lung fluid clearance in premature rabbits at gestational age (GA) of 25-28 d (full term: 31 d) and their relationship with dynamic compliance of respiratory system (Cdyn), pulmonary morphology and other parameters.Methods:In our previous publications, premature rabbits were divided into four groups according to the intervention strategy: control group, PS-only group, DEX-only group and DEX+PS group in which data of several parameters including wet-to-dry lung weight ratio (W/D), Cdyn and volume density of alveoli (Vv) were retrieved and the lung tissue sections were scanned to recalculate the ratio of perivascular sheath to vascular sectional area (S/V) and lung injury scores-edema (LIS-E). W/D, LIS-E, S/V and Vv were adjusted for birth weight (BW) (divided by BW, represented as W/D/BW, LIS-E/BW, S/V/BW and Vv/BW) and mean Cdyn (Cdyn-m) was adopted. Based on the grouping of previous studies, the intervention groups in this study were divided as DEX group and non-DEX group, and PS group and non-PS group to analyze the influence of DEX and PS on the above parameters. Two independent samples t-test, one-way analysis of variance, LSD test, Kruskal-Wallis H test, Mann-Whitney U test and Pearson correlation analysis were used for statistical analysis. Results:A total of 196 newborn rabbits receiving mechanical ventilation after birth were included in this study. (1) Effects of DEX: compared with the non-DEX group, the DEX group showed increased W/D/BW (489±69 vs 421±113, t=－2.09), LIS-E/BW (188±57 vs 138±55, t=－2.61) and Vv/BW (20.1±4.9 vs 14.2±4.7, t=－3.60), but decreased S/V (0.33±0.23 vs 0.51±0.25, t=2.23) and S/V/W/D (0.05±0.03 vs 0.07±0.04, t=2.22) at 25 d of gestation; at 26 d of gestation, W/D/BW (472±76 vs 303±44, t=－8.75), LIS-E/BW (189±63 vs 106±36, t=－5.23), Cdyn-m [(0.16±0.07) vs (0.05±0.03) ml/(kg?cmH 2O), 1 cmH 2O=0.098 kPa; t=－7.29] and Vv/BW increased (22.4±5.0 vs 12.2±3.8, t=－7.46), while S/V (0.23±0.19 vs 0.62±0.38, t=4.10), S/V/BW (15.7±12.4 vs 25.7±17.3, t=2.20), S/V/W/D (0.03±0.03 vs 0.08±0.05, t=3.92) and propensity scores decreased [(12.5±1.2) vs (15.1±1.2) scores, t=7.00]; at 27 d of gestation, Cdyn-m increased [(0.23±0.12) vs (0.16±0.07) ml/(kg?cmH 2O), t=－2.43], but S/V (0.32±0.23 vs 0.57±0.39, t=2.57) and S/V/W/D decreased (0.05±0.04 vs 0.09±0.06, t=2.55); at 28 d of gestation, W/D/BW (270±64 vs 162±33, t=－8.09), LIS-E/BW (72±32 vs 35±20, t=－5.17), S/V (0.90±0.60 vs 0.59±0.48, t=－2.81), S/V/BW (34.0±23.6 vs 15.2±12.7, t=－3.77) and Vv/BW increased (16.9±4.3 vs 9.2±2.9, t=－8.04); the differences were all statistically significant (all P<0.05). (2) Effects of PS: compared with the non-PS group, the PS group had decreased LIS-E/BW at 25, 26 and 27 d of gestation, increased Cdyn-m and Vv/BW at 25 and 27 d of gestation and higher propensity scores at 25 d of gestation (all P<0.05). (3) The correlation between gestational age and each index: gestational age was positively correlated with S/V ( r=0.31, P<0.05), but negatively correlated with W/D/BW and LIS-E/BW ( r=－0.73 and－0.63, both P<0.05). Conclusions:The pharmacological action of prenatal DEX on lung fluid clearance is mainly confined to preterm rabbits at the GA of 28 d which is supported by mechanical ventilation. Prenatal treatment with DEX and/or postnatal PS can improve the early respiratory function in preterm rabbits between GA of 25-27 d, but had no substantial impact on lung fluid clearance. The GA-related lung maturation appears to play a crucial role, in comparison with medications, in lung fluid clearance.

Effect of Cuban Porcine Pulmonary Surfactant (Surfacen) and rCmPI-II Protease Inhibitor on Neutrophil Elastase Activity.

INTRODUCTION: In inflammatory respiratory diseases, the imbalance between proteases and endogenous protease inhibitors leads to an exacerbated activity of human neutrophil elastase (a protease that destroys the extracellular matrix and stimulates proinflammatory cytokine release). Elastase is considered a target in the search for therapeutic treatments for inflammatory respiratory diseases. Pulmonary surfactant is a promising product for this purpose, because in addition to its biophysical function, it has anti-inflammatory properties. OBJECTIVE: Evaluate effect of the Cuban porcine pulmonary surfactant (Surfacen), the rCmPI-II elastase inhibitor, and the Surfacen/rCmPI-II combination on activated neutrophil elastase activity in vitro, and determine if Surfacen's interface property changes in the presence of the inhibitor. METHODS: The anti-elastase effect of Surfacen, rCmPI-II and the Surfacen/rCmPI-II combination was evaluated in an in vitro model of activated neutrophils, previously purified from the blood of healthy subjects. The cells were stimulated with LPS/fMLP and were incubated with different concentrations of Surfacen, rCmPI-II and the Surfacen/rCmPI-II combination. Elastase activity was measured. The interface property was determined on a Langmuir surface balance. The new index, called the abdominal adipose deposit index, was obtained by multiplying the subcutaneous fat thickness by visceral fat thickness, both measured by ultrasound. A cutoff point was established that facilitated discernment of an unhealthy phenotype: normal weight but metabolically obese, a cardiometabolic risk factor. RESULTS: Surfacen at 10 mg/mL inhibited 71% of stimulated neutrophil elastase activity. rCmPI-II at 0.1 µM reduced 20% of elastase activity; at 200 µM-the maximum concentration evaluated-inhibition was 68%. Both products had a dose-dependent effect. The Surfacen/inhibitor combination (0.5 mg/mL/80 µM) did not affect the surfactant interface property or the inhibitory activity of rCmPI-II against human neutrophil elastase. CONCLUSIONS: Surfacen and the rCmPI-II inhibitor have an anti-elastase effect on an activated neutrophil model. rCmPI-II does not affect Surfacen's interface property and, therefore, both can be evaluated for combined use in treating inflammatory lung diseases.

The influence of a biomimetic pulmonary surfactant modification on the in vivo fate of nanoparticles in the lung.

Direct biomimetic modification of nanoparticles (NPs) with endogenous surfactants is helpful to improve the biocompatibility of NPs and avoid damage to the physiological function of the lung. Therefore, the objective of this study is to investigate the influence of biomimetic endogenous pulmonary surfactant phospholipid modification on the in vivo fate of NPs after lung delivery. Here, two neutral phospholipids (dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylamine (DPPE)) and two negatively charged phospholipids (dipalmitoylphosphatidylglycerol (DPPG), dipalmitoylphosphatidylserine (DPPS)) were selected to modify paclitaxel (PTX)-loaded PLGA NPs with different molar ratio. DPPC, DPPE, and DPPG improved mucoadhesion, in contrast, DPPS improved the mucus permeability of the NPs. Neutral DPPC and DPPE reduced, but negatively charged DPPS and DPPG increased the uptake by alveolar macrophages, all types of phospholipid increased the uptake by lung epithelial cells and increased PTX retention in the whole lung. Whereas, DPPC, DPPE, and DPPG promoted PTX retention in bronchoalveolar lavage fluid (BALF), while DPPS promoted PTX absorption in the lung tissue. Only DPPS-PLGA (1:1) NPs remarkably increased PTX systemic exposure. A good correlation between PTX percentage in the supernatant of BALF and PTX concentration in plasma was established, implying PTX entered the system circulation mainly in molecular form. Phospholipid modification had no effect on extrapulmonary organ distribution of PTX. Taken together, our study disclosed that different phospholipid modification can endow the NPs mucoadhesive or mucus penetration and cellular uptake properties, with tunable retention in BALF and absorption in the lung tissue, providing the scientific background for translational nanocarrier design for inhalation as required. STATEMENT OF SIGNIFICANCE: Inhaled nanomedicines will inevitably interact with pulmonary surfactant and form "surfactant corona". However, the contribution of individual pulmonary surfactant phospholipid on the in vivo fate of nanomedicines is still unclear. In this regard, the most abundant pulmonary surfactant phospholipid dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylamine, and dipalmitoylphosphatidylglycerol and dipalmitoylphosphatidylserine were selected to modify the paclitaxel loaded PLGA nanoparticles and the effect of these pulmonary surfactant phospholipids on their in vivo fate was investigated. It was demonstrated that different phospholipid modification can endow the nanoparticles mucoadhesive or mucus penetration properties, with tunable retention in bronchoalveolar lavage fluid, alveolar macrophages uptake and absorption in the lung tissue. The present study provided a comprehensive understanding for the role of pulmonary surfactant phospholipid on inhaled nanomedicines.

Immune and epithelial determinants of age-related risk and alveolar injury in fatal COVID-19.

Respiratory failure in COVID-19 is characterized by widespread disruption of the lung's alveolar gas exchange interface. To elucidate determinants of alveolar lung damage, we performed epithelial and immune cell profiling in lungs from 24 COVID-19 autopsies and 43 uninfected organ donors ages 18-92 years. We found marked loss of type 2 alveolar epithelial (T2AE) cells and increased perialveolar lymphocyte cytotoxicity in all fatal COVID-19 cases, even at early stages before typical patterns of acute lung injury are histologically apparent. In lungs from uninfected organ donors, there was also progressive loss of T2AE cells with increasing age, which may increase susceptibility to COVID-19-mediated lung damage in older individuals. In the fatal COVID-19 cases, macrophage infiltration differed according to the histopathological pattern of lung injury. In cases with acute lung injury, we found accumulation of CD4+ macrophages that expressed distinctly high levels of T cell activation and costimulation genes and strongly correlated with increased extent of alveolar epithelial cell depletion and CD8+ T cell cytotoxicity. Together, our results show that T2AE cell deficiency may underlie age-related COVID-19 risk and initiate alveolar dysfunction shortly after infection, and we define immune cell mediators that may contribute to alveolar injury in distinct pathological stages of fatal COVID-19.

Thin-catheter Surfactant Application for Respiratory Distress Syndrome in Spontaneously Breathing Preterm Infants: A Meta-analysis of Randomized Clinical Trials.

BACKGROUND: Surfactant application by a thin catheter represented by the term less invasive surfactant administration (LISA) for respiratory distress syndrome in spontaneously breathing preterm infants was developed as an alternative to endotracheal intubation. METHODS: We conducted a meta-analysis to assess the effects of LISA when compared to the socalled intubation-surfactant-extubation (INSURE) and the standard endotracheal intubation and mechanical ventilation (MV). The primary outcome was the composite incidence of death or bronchopulmonary dysplasia at a postmenstrual age of 36 weeks. The secondary outcome was the composite incidence of seven other severe adverse events. On 06 October 2021, we searched randomized clinical trials (RCTs) in PubMed, the Cochrane Library, ClinicalTrials.gov, and the ICTRP Registry. RESULTS: We included 18 RCTs. The pooled data on the primary outcome favored LISA when compared to either INSURE (risk ratio 0.67; 95% CI, 0.51 to 0.88) or MV (risk ratio 0.78; 95% CI, 0.61 to 0.99). The pooled data on the second outcome also favored LISA when compared to INSURE (risk ratio 0.75; 95% CI, 0.60 to 0.94) and MV (risk ratio 0.73; 95% CI, 0.55 to 0.96). CONCLUSION: The findings showed that surfactant application by non-intubation respiratory support and the use of a thin catheter may decrease the composite risk of death or bronchopulmonary dysplasia. The included data support the view that LISA should be considered the preferred treatment option in eligible infants.

Nano-in-Microparticles for Aerosol Delivery of Antibiotic-Loaded, Fucose-Derivatized, and Macrophage-Targeted Liposomes to Combat Mycobacterial Infections: In Vitro Deposition, Pulmonary Barrier Interactions, and Targeted Delivery.

Nontuberculous mycobacterial infections rapidly emerge and demand potent medications to cope with resistance. In this context, targeted loco-regional delivery of aerosol medicines to the lungs is an advantage. However, sufficient antibiotic delivery requires engineered aerosols for optimized deposition. Here, the effect of bedaquiline-encapsulating fucosylated versus nonfucosylated liposomes on cellular uptake and delivery is investigated. Notably, this comparison includes critical parameters for pulmonary delivery, i.e., aerosol deposition and the noncellular barriers of pulmonary surfactant (PS) and mucus. Targeting increases liposomal uptake into THP-1 cells as well as peripheral blood monocyte- and lung-tissue derived macrophages. Aerosol deposition in the presence of PS, however, masks the effect of active targeting. PS alters antibiotic release that depends on the drug's hydrophobicity, while mucus reduces the mobility of nontargeted more than fucosylated liposomes. Dry-powder microparticles of spray-dried bedaquiline-loaded liposomes display a high fine particle fraction of >70%, as well as preserved liposomal integrity and targeting function. The antibiotic effect is maintained when deposited as powder aerosol on cultured Mycobacterium abscessus. When treating M. abscessus infected THP-1 cells, the fucosylated variant enabled enhanced bacterial killing, thus opening up a clear perspective for the improved treatment of nontuberculous mycobacterial infections.

Drug Meets Monolayer: Understanding the Interactions of Sterol Drugs with Models of the Lung Surfactant Monolayer Using Molecular Dynamics Simulations.

The lung surfactant monolayer (LSM) is a thin layer of lipids and proteins that forms the air/water interface of the alveoli. The primary function of the LSM is to reduce the surface tension at the air/water interface during breathing. The LSM also forms the main biological barrier for any inhaled particles, including drugs, to treat lung diseases. Elucidating the mechanism by which these drugs bind to and absorb into the LSM requires a molecular-level understanding of any drug-induced changes to the morphology, structure, and phase changes of the LSM.Molecular dynamics simulations have been used extensively to study the structure and dynamics of the LSM. The monolayer is usually simulated in at least two states: the compressed state, mimicking exhalation, and the expanded state, mimicking inhalation. In this chapter, we provide detailed instructions on how to set up, run, and analyze coarse-grained MD simulations to study the concentration-dependent effect of a sterol drug on the LSM, both in the expanded and compressed state.

Impact of surfactant when utilized during pediatric cardiac surgery admissions: analysis of a nationwide database.

OBJECTIVE: Surfactant has been routinely used in the neonatal population, particularly in the setting of prematurity and neonatal respiratory distress syndrome. Current evidence, however, does not delineate the effect of surfactant use in neonates and older children during cardiac surgery admissions. This study aimed to characterize the impact of surfactant on pediatric cardiac surgery admissions. METHODS: Admissions of those under 18 years of age with cardiac surgery were identified from the Pediatric Health Information System (PHIS) database between 2004 and 2015, using ICD-9 procedure codes. Univariate analyses were conducted to compare admission characteristics between those that did and not utilize surfactant. Variables shown to be significant were then entered as independent variables into the regression analyses. Surfactant was entered into each model as an independent variable. RESULTS: A total of 81,313 admissions met the inclusion criteria. Of these, 109 (0.1%) had surfactant utilized. Univariate analyses identified several differences between admissions with and without surfactant use and demonstrated significantly increased mortality in the surfactant group (38.5% versus 4.6%, p < .01). Regression analyses demonstrated that surfactant was independently associated with increased mortality (odds ratio 6.0, 95% confidence interval 3.9-9.3, p < .01). Univariate analysis in only surfactant admissions demonstrated the following to be associated with inpatient mortality: younger age, prematurity, Ebstein anomaly, and hypoplastic left heart syndrome. CONCLUSIONS: Surfactant administration during pediatric cardiac surgery admissions is independently associated with a sixfold increase in inpatient mortality. It is likely that these findings are mediated by augmentation of the decrease in pulmonary vascular resistance and a subsequent decrease in systemic blood flow in the setting of parallel circulation. Surfactant should be administered with special consideration in neonates with cardiac disease and may be best avoided in those with parallel circulation.

Alveolar epithelial glycocalyx degradation mediates surfactant dysfunction and contributes to acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure yet has few pharmacologic therapies, reflecting the mechanistic heterogeneity of lung injury. We hypothesized that damage to the alveolar epithelial glycocalyx, a layer of glycosaminoglycans interposed between the epithelium and surfactant, contributes to lung injury in patients with ARDS. Using mass spectrometry of airspace fluid noninvasively collected from mechanically ventilated patients, we found that airspace glycosaminoglycan shedding (an index of glycocalyx degradation) occurred predominantly in patients with direct lung injury and was associated with duration of mechanical ventilation. Male patients had increased shedding, which correlated with airspace concentrations of matrix metalloproteinases. Selective epithelial glycocalyx degradation in mice was sufficient to induce surfactant dysfunction, a key characteristic of ARDS, leading to microatelectasis and decreased lung compliance. Rapid colorimetric quantification of airspace glycosaminoglycans was feasible and could provide point-of-care prognostic information to clinicians and/or be used for predictive enrichment in clinical trials.