Inflammation and surfactant

State-of-the-art surfactants as biomedical game changers: unlocking their potential in drug delivery, diagnostics, and tissue engineering

This review presents a comprehensive analysis of surfactant-based medicinal formulations, highlighting both their advantages and disadvantages. Surfactants enhance drug solubility, enhance targeted delivery, and facilitate controlled release of drugs. Their antimicrobial action is a result of their ability to disrupt microbial membranes, and their application in the delivery of genes and proteins involves stabilizing lipid nanoparticles for messenger ribonucleic acid (mRNA) vaccines and clustered regularly interspaced short palindromic repeats (CRISPR). Surfactants also assist in biomedical imaging and theranostics by enhancing magnetic resonance imaging (MRI) contrast, fluorescence bioimaging, and cancer diagnosis. In tissue engineering, they assist in the manufacturing of scaffolds and coatings of biomaterials. In spite of their broad application, cytotoxicity concerns, environmental impact, and regulatory constraints bar clinical use. Biodegradable biosurfactants, stimuli-responsive intelligent surfactants, and AI-driven formulation design are areas that future studies can focus on to enhance safety and effectiveness in current healthcare applications.

Ascending Vaginal Infection in Mice Induces Preterm Birth and Neonatal Morbidity

Preterm birth (PTB; delivery before 37 weeks), the main cause of neonatal death worldwide, can lead to adverse neurodevelopmental outcomes, as well as lung and gut pathology. PTB can be associated with ascending vaginal infection. Ascending Escherichia coli infection in pregnant mice induces PTB and reduces pup survival. The current study demonstrated that this model recapitulates the pathology observed in human preterm neonates (namely, neuroinflammation, lung injury, and gut inflammation). In neonatal brains, there is widespread cell death, microglial activation, astrogliosis, and reduced neuronal density. The utility of this model was validated by assessing the efficacy of maternal cervical gene therapy with an adeno-associated viral vector containing human β defensin 3. This improved pup survival and reduced tumor necrosis factor alpha mRNA expression in perinatal pup brains exposed to E. coli. This model provides a unique opportunity to evaluate the therapeutic benefit of preterm labor interventions on perinatal pathology.

Intervention of organophosphate esters in phospholipids hypochlorination at the air-water interface

Organophosphate esters (OPEs) are a serious and pervasive indoor environmental pollutant, and their extensive use and frequent detection in indoor environments have raised growing concerns globally about their impact on the respiratory system. Simultaneously, increasing attention has been directed toward interfacial hypochlorous acid (HOCl) chemistry, particularly in relation to indoor air quality and public health. However, the molecular mechanisms underlying HOCl-mediated oxidation of phospholipids in the presence of OPEs remain unclear. This study utilized an online air-water interface reaction monitoring technique to examine the effects of ten OPEs, including alkyl, chlorinated, and aryl OPEs, on the oxidation of a model lung phospholipid 1-Palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) exposed to HOCl at the air-water interface. The results indicated that OPEs inhibit the oxidation of phospholipids by HOCl at the air-water interface, and this inhibitory effect is correlated with the concentration of OPEs and their water-oil partition coefficient (LogP). Mechanistic studies demonstrated that the hydrophilicity of OPEs enables their incorporation into the phospholipid monolayer, resulting in a compact arrangement of POPG. This arrangement partially shields the C=C double bonds from exposure to HOCl, thereby inhibiting the oxidation of POPG at the air-water interface. These findings elucidate the molecular mechanisms by which OPEs modulate HOCl-induced phospholipid oxidation, providing a theoretical foundation for the development of specific drugs targeting related diseases.

Effect of aging on pulmonary cellular responses during mechanical ventilation

Acute respiratory distress syndrome (ARDS) results in substantial morbidity and mortality, especially in elderly people. Mechanical ventilation, a common supportive treatment for ARDS, is necessary for maintaining gas exchange but can also propagate injury. We hypothesized that aging leads to alterations in surfactant function, inflammatory signaling, and microvascular permeability within the lung during mechanical ventilation. Young and aged male mice were mechanically ventilated, and surfactant function, inflammation, and vascular permeability were assessed. Additionally, single-cell RNA-Seq was used to delineate cell-specific transcriptional changes. The results showed that, in aged mice, surfactant dysfunction and vascular permeability were significantly augmented, while inflammation was less pronounced. Differential gene expression and pathway analyses revealed that alveolar macrophages in aged mice showed a blunted inflammatory response, while aged endothelial cells exhibited altered cell-cell junction formation. In vitro functional analysis revealed that aged endothelial cells had an impaired ability to form a barrier. These results highlight the complex interplay between aging and mechanical ventilation, including an age-related predisposition to endothelial barrier dysfunction, due to altered cell-cell junction formation, and decreased inflammation, potentially due to immune exhaustion. It is concluded that age-related vascular changes may underlie the increased susceptibility to injury during mechanical ventilation in elderly patients.

Maternal prenatal systemic inflammation indexes predicts premature neonatal respiratory distress syndrome

Neonatal respiratory distress syndrome (NRDS) is one of the leading causes of neonatal mortality in low-income countries. It is caused by a lack of surface-active substances in the lungs, and the maternal inflammatory response plays an important role in the formation of surface-active substances in the fetal lungs. We aimed to investigate the correlation between maternal prenatal systemic inflammatory indices and respiratory distress syndrome in preterm neonates. This is a retrospective case-control study that collected data from all patients who delivered between 28 and 36 weeks of gestation at Longhua District People's Hospital in Shenzhen City and whose infants were admitted to the neonatal unit, newborns with respiratory distress syndrome were in the experimental group (NRDS group), and newborns without NRDS were in the control group (non-NRDS group). To minimize the effect of confounders on the results, propensity score matching was performed on baseline characteristics. Totally, 524 patients were included (93 in the NRDS group and 431 in the non-NRDS group), and 71 matched pairs (142 patients). The neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (dNLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), aggregate index of systemic inflammation (AISI) and neutrophil lymphocyte to platelet ratio (NLPR) were higher in the NRDS group than in the non-NRDS group (p < 0.05). The ROC curves of NLR, dNLR, SII, SIRI, AISI and NLPR for the diagnosis of NRDS were plotted, and it was found that the combined diagnostic efficacy of these six systemic inflammatory markers was better (AUC: 0.643, P = 0.003). Patients were divided into two groups based on the cut-off values determined from the ROC curves, and analysis using binary regression models revealed that SII ≥ 1199.94 (OR, 2.554; 95% CI 1.245-5.239, P = 0.011) and NLPR ≥ 0.0239 (OR, 2.175; 95% CI 1.061-4.459, P = 0.034) were independent risk factors predicting NRDS. Maternal prenatal SII ≥ 1199.94 and NLPR ≥ 0.0239 are independent risk factors for NRDS, and clinicians may be used to prevent neonatal respiratory distress in advance to reduce the incidence of NRDS.

Early Ventilator Management for Infants With Congenital Diaphragmatic Hernia: Impact of a Standardized Clinical Practice Guideline

BACKGROUND

Infants with congenital diaphragmatic hernia (CDH) experience high morbidity and mortality due to pulmonary arterial hypertension and hypoplasia. Mechanical ventilation is a central component of CDH management. Our objective was to evaluate the impact of a standardized clinical practice guideline (implemented in January 2012) on ventilator management for infants with CDH, and associate management changes with short-term outcomes, specifically extracorporeal membrane oxygenation (ECMO) utilization and survival to discharge.

METHODS

We conducted a retrospective pre-post study of 103 CDH infants admitted from January 2007-July 2021, divided pre- (n = 40) and post-guideline (n = 63). Clinical outcomes, ventilator settings, and blood gas values in the first 7 days of mechanical ventilation were compared between the pre- and post-guideline cohorts.

RESULTS

Post-guideline, ECMO utilization decreased (11% vs 38%, p = 0.001) and survival to discharge improved (92% vs 68%, p = 0.001). More post-guideline patients remained on conventional mechanical ventilation without need for escalation to high-frequency ventilation or ECMO, and had higher pressures and PaCO2 with lower FiO2 and PaO2 (p < 0.05).

CONCLUSIONS

Standardized ventilator management optimizing pressures for adequate lung expansion and minimizing oxygen toxicity improves outcomes for infants with CDH.

LEVEL OF EVIDENCE

III.

Construction and evaluation of neonatal respiratory failure risk prediction model for neonatal respiratory distress syndrome

BACKGROUND

Neonatal respiratory distress syndrome (NRDS) is a common respiratory disease in preterm infants, often accompanied by respiratory failure. The aim of this study was to establish and validate a nomogram model for predicting the probability of respiratory failure in NRDS patients.

METHODS

Patients diagnosed with NRDS were extracted from the MIMIC-iv database. The patients were randomly assigned to a training and a validation cohort. Univariate and stepwise Cox regression analyses were used to determine the prognostic factors of NRDS. A nomogram containing these factors was established to predict the incidence of respiratory failure in NRDS patients. The area under the receiver operating characteristic curve (AUC), receiver operating characteristic curve (ROC), calibration curves and decision curve analysis were used to determine the effectiveness of this model.

RESULTS

The study included 2,705 patients with NRDS. Univariate and multivariate stepwise Cox regression analysis showed that the independent risk factors for respiratory failure in NRDS patients were gestational age, pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), hemoglobin, blood culture, infection, neonatal intracranial hemorrhage, Pulmonary surfactant (PS), parenteral nutrition and respiratory support. Then, the nomogram was constructed and verified.

CONCLUSIONS

This study identified the independent risk factors of respiratory failure in NRDS patients and used them to construct and evaluate respiratory failure risk prediction model for NRDS. The present findings provide clinicians with the judgment of patients with respiratory failure in NRDS and help clinicians to identify and intervene in the early stage.

A win-win scenario for antibacterial activity and skin mildness of cationic surfactants based on the modulation of host-guest supramolecular conformation

The commercial cationic surfactants (CSAa) with quaternary ammonium (QA) groups have proved to be broad-spectrum bactericide against bacteria, fungi, and viruses. Nevertheless, they inevitably exhibit potent irritation on the skin. In this work, we systematically investigated the regulatory mechanism of the host-guest supramolecular conformation with β-cyclodextrin (β-CD) on the bactericidal performance and skin irritation of CSAa with different head groups and chain lengths. When the ratio of incorporated β-CD is not greater than 1:1, the bactericidal efficiency of CSAa@β-CD (n > 12) remained above 90 % due to the free QA groups and hydrophobic fraction that can act on negatively charged bacterial membranes. And once the ratio of β-CD exceeded 1:1, the β-CD attracted to the bacterial surface by hydrogen bonding might prevent CSAa@β-CD from acting on bacteria, resulting in a decrement in antibacterial performance. Even so, the antibacterial activity of CSAa with long alkyl chains (n = 16, 18) was independent from the complexation of β-CD. Accordingly, both the zein solubilization assay and the neutrophil migration assay on zebrafish skin evidenced that β-CD attenuated the interaction of surfactant with skin model proteins and the inflammatory effect on zebrafish, thereby enhancing skin mildness. In this way, we hope to create a simple but effective brainpower using the host-guest approach to guarantee both bactericidal efficiency and skin mildness without modifying the chemical structure of these commercial biocides.

A randomized clinical trial of antibiotic treatment duration in preterm premature rupture of membranes: 7 days vs until delivery

BACKGROUND

Antibiotic treatment in preterm premature rupture of membranes can prolong the interval from membrane rupture to delivery and improve neonatal outcomes. However, the duration of antibiotic treatment for preterm premature rupture of membranes has been rarely compared in prospective studies.

OBJECTIVE

This study aimed to investigate the optimal duration of antibiotic treatment for premature rupture of membranes. We performed a randomized controlled trial comparing neonatal morbidity and infantile neurologic outcomes between 2 groups of patients with preterm premature rupture of membranes who received antibiotic treatment for 7 days or until delivery, respectively.

STUDY DESIGN

This prospective randomized study included patients who were diagnosed with preterm premature rupture of membranes between 22+0 weeks and 33+6 weeks of gestation. The enrolled patients were randomly assigned to receive intravenous cefazolin (1 g dosage every 12 hours) and oral clarithromycin (500 mg dosage every 12 hours) either for 7 days or until delivery. The study protocol was registered at ClinicalTrials.gov under identifier NCT01503606. The primary outcome was a neonatal composite morbidity, and the secondary outcome was neurologic outcomes at 12 months of corrected age. We enrolled 151 patients and allocated 75 and 76 of them to the 7-day and until-delivery groups, respectively. Analysis was done by per protocol.

RESULTS

After excluding cases lost to follow-up and those with protocol violations, 63 (7-day regimen) and 61 (until-delivery regimen) patients with preterm premature rupture of membranes and their babies were compared. There was no significant difference in the pregnancy outcomes, including gestational age at delivery and the interval from rupture of membranes to delivery, between the 2 groups. Among the neonatal outcomes, bronchopulmonary dysplasia, intraventricular hemorrhage, retinopathy of prematurity, necrotizing enterocolitis, and proven neonatal sepsis did not differ between the groups. However, the rates of respiratory distress syndrome (32.8% vs 50.8%; P=.039) and composite neonatal morbidities (34.4% vs 53.9%; P=.026) were lower in the until-delivery group than in the 7-day group. This difference remained statistically significant after a multivariable analysis adjusting for maternal age, twin pregnancy, antenatal corticosteroids treatment, gestational age at delivery, interval from rupture of membranes to delivery, and clinical chorioamnionitis. Infantile neurologic outcomes were evaluated in 71.4% of the babies discharged alive and did not differ between the groups.

CONCLUSION

Overall, the until-delivery regimen of cefazolin and clarithromycin in preterm premature rupture of membranes led to a lower incidence of composite neonatal morbidity and respiratory distress syndrome than the 7-day regimen, and both regimens otherwise showed similar individual neonatal morbidities and infantile neurologic outcomes.

Lipid-laden lung mesenchymal cells foster breast cancer metastasis via metabolic reprogramming of tumor cells and natural killer cells

While the distant organ environment is known to support metastasis of primary tumors, its metabolic roles in this process remain underdetermined. Here, in breast cancer models, we found lung-resident mesenchymal cells (MCs) accumulating neutral lipids at the pre-metastatic stage. This was partially mediated by interleukin-1β (IL-1β)-induced hypoxia-inducible lipid droplet-associated (HILPDA) that subsequently represses adipose triglyceride lipase (ATGL) activity in lung MCs. MC-specific ablation of the ATGL or HILPDA genes in mice reinforced and reduced lung metastasis of breast cancer respectively, suggesting a metastasis-promoting effect of lipid-laden MCs. Mechanistically, lipid-laden MCs transported their lipids to tumor cells and natural killer (NK) cells via exosome-like vesicles, leading to heightened tumor cell survival and proliferation and NK cell dysfunction. Blockage of IL-1β, which was effective singly, improved the efficacy of adoptive NK cell immunotherapy in mitigating lung metastasis. Collectively, lung MCs metabolically regulate tumor cells and anti-tumor immunity to facilitate breast cancer lung metastasis.

Pannexin-1 channel opening is critical for COVID-19 pathogenesis

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly rampaged worldwide, causing a pandemic of coronavirus disease (COVID -19), but the biology of SARS-CoV-2 remains under investigation. We demonstrate that both SARS-CoV-2 spike protein and human coronavirus 229E (hCoV-229E) or its purified S protein, one of the main viruses responsible for the common cold, induce the transient opening of Pannexin-1 (Panx-1) channels in human lung epithelial cells. However, the Panx-1 channel opening induced by SARS-CoV-2 is greater and more prolonged than hCoV-229E/S protein, resulting in an enhanced ATP, PGE₂, and IL-1β release. Analysis of lung lavages and tissues indicate that Panx-1 mRNA expression is associated with increased ATP, PGE₂, and IL-1β levels. Panx-1 channel opening induced by SARS-CoV-2 spike protein is angiotensin-converting enzyme 2 (ACE-2), endocytosis, and furin dependent. Overall, we demonstrated that Panx-1 channel is a critical contributor to SARS-CoV-2 infection and should be considered as an alternative therapy.

Pulmonary Consequences of Prenatal Inflammatory Exposures: Clinical Perspective and Review of Basic Immunological Mechanisms

Chorioamnionitis, a potentially serious inflammatory complication of pregnancy, is associated with the development of an inflammatory milieu within the amniotic fluid surrounding the developing fetus. When chorioamnionitis occurs, the fetal lung finds itself in the unique position of being constantly exposed to the consequent inflammatory meditators and/or microbial products found in the amniotic fluid. This exposure results in significant changes to the fetal lung, such as increased leukocyte infiltration, altered cytokine, and surfactant production, and diminished alveolarization. These alterations can have potentially lasting impacts on lung development and function. However, studies to date have only begun to elucidate the association between such inflammatory exposures and lifelong consequences such as lung dysfunction. In this review, we discuss the pathogenesis of and fetal immune response to chorioamnionitis, detail the consequences of chorioamnionitis exposure on the developing fetal lung, highlighting the various animal models that have contributed to our current understanding and discuss the importance of fetal exposures in regard to the development of chronic respiratory disease. Finally, we focus on the clinical, basic, and therapeutic challenges in fetal inflammatory injury to the lung, and propose next steps and future directions to improve our therapeutic understanding of this important perinatal stress.

Minimally invasive surfactant therapy failure: risk factors and outcome

OBJECTIVE

To evaluate incidence of minimally invasive surfactant therapy (MIST) failure, identify risk factors and assess the impact of MIST failure on neonatal outcome.

DESIGN

Retrospective cohort study. MIST failure was defined as need for early mechanical ventilation (<72 hours of life). Multivariate logistic regression analysis was performed to identify risk factors for MIST failure and compare outcomes between groups.

SETTING

Two tertiary neonatal intensive care centres in the Netherlands.

PATIENTS

Infants born between 24 weeks' and 31 weeks' gestational age (GA) (n=185) with MIST for respiratory distress syndrome.

INTERVENTIONS

MIST procedure with poractant alfa (100-200 mg/kg).

MAIN OUTCOME MEASURES

Continuous positive airway pressure (CPAP) failure after MIST in the first 72 hours of life.

RESULTS

30% of the infants failed CPAP after MIST. In a multivariate logistic regression analysis, four risk factors were independently associated with failure: GA <28 weeks, C reactive protein ≥10 mg/L, absence of antenatal corticosteroids and lower surfactant dose. Infants receiving 200 mg/kg surfactant had a failure rate of 14% versus 35% with surfactant dose <200 mg/kg. Mean body temperature was 0.4°C lower at neonatal intensive care unit admission and before the procedure in infants with MIST failure.Furthermore, MIST failure was independently associated with an increased risk of severe intraventricular haemorrhage.

CONCLUSION

We observed moderate MIST failure rates in concordance with the results of earlier studies. Absence of corticosteroids and lower surfactant dose are risk factors for MIST failure that may be modifiable in order to improve MIST success and patient outcome.

Impact of histologic chorioamnionitis on pulmonary hypertension and respiratory outcomes in preterm infants

We aimed to evaluate the association between the presence of histologic chorioamnionitis (HC) and development of pulmonary hypertension (PH) during neonatal intensive care unit (NICU) stay. Data of preterm infants born at 32 weeks of gestation or less were reviewed. The development of PH and other respiratory outcomes were compared according to the presence of HC. Potential risk factors associated with the development of PH during NICU stay were used for multivariable logistic regression analysis. A total of 188 infants were enrolled: 72 in the HC group and 116 in the no HC group. The HC group infants were born at a significantly shorter gestational age and lower birthweight, with a greater proportion presenting preterm premature rupture of membrane (pPROM) > 18 h before delivery. More infants in the HC group developed pneumothorax (P = 0.008), and moderate and severe bronchopulmonary dysplasia (BPD; P = 0.001 and P = 0.006, respectively). PH in the HC group was significantly more frequent compared to the no HC group (25.0% versus 8.6%, P = 0.002). Based on a multivariable logistic regression analysis, birthweight (P = 0.009, odds ratio [OR] = 0.997, 95% confidence interval [CI] = 0.995–0.999), the presence of HC (P = 0.047, OR = 2.799, 95% CI = 1.014–7.731), and duration of invasive mechanical ventilation (MV) > 14 days (P = 0.015, OR = 8.036, 95% CI = 1.051–43.030) were significant factors. The presence of HC and prolonged invasive MV in infants with lower birthweight possibly synergistically act against preterm pulmonary outcomes and leads to the development of PH. Verification of this result and further investigation to establish effective strategies to prevent or ameliorate these adverse outcomes are needed.

Exploration of the Contribution of Biobehavioral Variables to the Energy Expenditure of Preterm Infants

Variation in energy expended by preterm infants may be due to infant maturity and history of resolved acute lung disease (respiratory distress syndrome [RDS]) as well as growth, caloric intake, and activity. Indirect calorimetry was used in this exploratory, short-term longitudinal study to estimate energy expenditure (EE) from measures of inspired and expired O2 and CO2 .The sample included 35 assessments for 10 preterm infants (5 with and 5 without RDS history). Lung disease history (resolved RDS, no RDS diagnosis), weight gain (g/d) from the day on which birth weight had been regained to the study day, mean activity level, the number of the assessment (1 6), and the interaction of lung disease history and time were included in a linear mixed model for repeated measures. Time was an index of postconceptional and postnatal age; all 3 were highly correlated. Because of high correlation with weight gain, caloric intake was not included in the analytic model. Lung disease history, mean activity level, and time were significant contributors to EE. A more precise measure of medical status than absence or presence of lung disease history, evenly spaced repetitions of EE assessment, and exploration of contexts in which the infants exhibit a higher activity level are needed in a replication study with a larger sample.

Effect of hypoxia on lung gene expression and proteomic profile: insights into the pulmonary surfactant response

Exposure of lung to hypoxia has been previously reported to be associated with significant alterations in the protein content of bronchoalveolar lavage (BAL) and lung tissue. In the present work we have used a proteomic approach to describe the changes in protein complement induced by moderate long-term hypoxia (rats exposed to 10% O2 for 72h) in BAL and lung tissue, with a special focus on the proteins associated with pulmonary surfactant, which could indicate adaptation of this system to limited oxygen availability. The analysis of the general proteomic profile indicates a hypoxia-induced increase in proteins associated with inflammation both in lavage and lung tissue. Analysis at mRNA and protein levels revealed no significant changes induced by hypoxia on the content in surfactant proteins or their apparent oligomeric state. In contrast, we detected a hypoxia-induced significant increase in the expression and accumulation of hemoglobin in lung tissue, at both mRNA and protein levels, as well as an accumulation of hemoglobin both in BAL and associated with surface-active membranes of the pulmonary surfactant complex. Evaluation of pulmonary surfactant surface activity from hypoxic rats showed no alterations in its spreading ability, ruling out inhibition by increased levels of serum or inflammatory proteins.

BIOLOGICAL SIGNIFICANCE

This work reveals that hypoxia induces extensive changes in the proteomic profile of lung bronchoalveolar lavage, including the presence of proteins related with inflammation both in lung tissue and lavage, and a significant increase in the synthesis and secretion by the lung tissue of different forms of hemoglobin. The level of specific pulmonary surfactant-associated proteins is not substantially altered due to hypoxia, but hypoxia-adapted surfactant exhibits an enhanced ability to form surface-active films at the air-liquid interface. The increased amount of β-globin integrated into the operative surfactant complexes obtained from hypoxic rats is a relevant feature that points to the existence of adaptive responses coupling surfactant function and oxygen availability.

Novel therapeutic strategies for lung disorders associated with airway remodelling and fibrosis

Inflammatory cell infiltration, cytokine release, epithelial damage, airway/lung remodelling and fibrosis are central features of inflammatory lung disorders, which include asthma, chronic obstructive pulmonary disease, acute respiratory distress syndrome and idiopathic pulmonary fibrosis. Although the lung has some ability to repair itself from acute injury, in the presence of ongoing pathological stimuli and/or insults that lead to chronic disease, it no longer retains the capacity to heal, resulting in fibrosis, the final common pathway that causes an irreversible loss of lung function. Despite inflammation, genetic predisposition/factors, epithelial-mesenchymal transition and mechanotransduction being able to independently contribute to airway remodelling and fibrosis, current therapies for inflammatory lung diseases are limited by their ability to only target the inflammatory component of the disease without having any marked effects on remodelling (epithelial damage and fibrosis) that can cause lung dysfunction independently of inflammation. Furthermore, as subsets of patients suffering from these diseases are resistant to currently available therapies (such as corticosteroids), novel therapeutic approaches are required to combat all aspects of disease pathology. This review discusses emerging therapeutic approaches, such as trefoil factors, relaxin, histone deacetylase inhibitors and stem cells, amongst others that have been able to target airway inflammation and airway remodelling while improving related lung dysfunction. A better understanding of the mode of action of these therapies and their possible combined effects may lead to the identification of their clinical potential in the setting of lung disease, either as adjunct or alternative therapies to currently available treatments.

Chorioamnionitis, respiratory distress syndrome and bronchopulmonary dysplasia in extremely low birth weight infants

OBJECTIVE

To determine if histologic chorioamnionitis (HC) in the presence of respiratory distress syndrome (RDS) augments adverse pulmonary outcomes in extremely low birth weight (ELBW) infants.

STUDY DESIGN

We retrospectively identified 184 ELBW infants who were born at and admitted to the neonatal intensive care units between June 2005 and June 2009.

RESULTS

The mean gestational age of the cases was 27 ± 2 weeks, and the mean birth weight was 791 ± 147 g. A total of 88% (161/184) of patients developed bronchopulmonary dysplasia (BPD). HC was observed in 71 of 238 infants (39%). When infants were divided on the basis of the presence or absence of HC and RDS, the incidence of moderate or severe BPD and duration of oxygen requirement were greater in the HC+RDS+ group than in the HC-RDS+ or HC+RDS- groups. The combination of prenatal (HC) and postnatal (RDS) injuries increased significantly the risk for BPD. In the multivariate analysis, the significant predictors of developing BPD were low gestational age (odds ratio (OR), 0.6; confidence interval (CI), 0.4 to 0.7) and exposure to both HC and RDS (OR, 4.7; CI, 1.1 to 20.2).

CONCLUSION

The HC and RDS work synergistically to induce lung injury in ELBW infants. Chorioamnionitis may interact with RDS to further increase the risk of BPD, despite either HC or RDS could not show independent significant association with BPD.

Reduced airway inflammation in CD26/DPP4-deficient F344 rats is associated with altered recruitment patterns of regulatory T cells and expression of pulmonary surfactant proteins

INTRODUCTION

CD26 is highly expressed on lung epithelial cells as well as on immune cells. Ovalbumin (OVA)-induced airway inflammation induces a further increase of CD26 expression. CD26-deficient rat strains exhibit blunted clinical courses in models of experimental asthma.

OBJECTIVE

(1) To investigate the involvement of regulatory T cells (Tregs) and the surfactant system in a rat model of genetic CD26 deficiency. (2) To investigate regulatory mechanisms dependent on the endogenous CD26 expression. (3) To investigate the impact of CD26 on surfactant protein (SP)-levels under inflammatory conditions.

METHODS

Wild-type and CD26-deficient F344 rats were sensitized to and challenged with OVA. Subsequently, airway inflammation, SP levels as well as surface tension of the bronchoalveolar lavage (BAL) fluid were evaluated.

RESULTS

CD26 deficiency led to decreased airway inflammation, e.g. reduced numbers of eosinophils and activated T cells in the BAL. Remarkably, the CD26-deficient rats exhibited a significantly increased influx of FoxP3(+) Tregs into the lungs and increased IL-10-secretion/production by draining lymph node cells in culture experiments. Furthermore, in OVA-challenged CD26-deficient rats, the increase of the expression of the collectins SP-A and SP-D as well as of the surface tension-active SP-B was significantly less pronounced than in the CD26-positive strain. Only in the wild-type rats, functional alterations of the surfactant system, e.g. the increased surface tension were obvious after OVA challenge.

CONCLUSION

Reduced airway inflammation in CD26-deficient F344 rats appear to be mediated by differences in the recruitment and activity of Tregs. This altered inflammation is associated with differences in the SP expression as well as function.

Sputum dipalmitoylphosphatidylcholine level as a novel airway inflammatory marker in asthmatic children

INTRODUCTION

Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins. Phosphatidylcholine comprises almost 80% of the total surfactant lipids, about half of which is dipalmitoylphosphatidylcholine (DPPC). Alteration of surfactant composition and function is documented with various airway or lung parenchyma disorders.

OBJECTIVE

To assess sputum concentration of DPPC as a major component of airways surfactant in asthmatic children compared to conventional airway inflammatory markers.

METHODS

This case control study included 68 well-known asthmatic children of different grades of severity and 20 age- and sex-matched normal children as controls. All children were subjected to thorough clinical examination, pulmonary function tests, sputum induction and processing for cytology, DPPC level and eosinophil cationic protein (ECP) level assessment.

RESULTS

Elevated DPPC levels were evident in all sputum samples of asthmatic children (mean value 626.6 +/- 189.7 mcg/mL) compared to controls (mean value 49.3 +/- 20.1 mcg/mL). Significant negative correlations (r = -0.83, -0.752 and -0.384) were found between asthmatics sputum DPPC levels and pulmonary function test parameters [% of forced expiratory volume in first second, % of forced vital capacity (FVC) and forced expiratory flow rate over 25%-75% part of FVC], respectively. Meanwhile, significant positive correlations were evident between asthmatics sputum DPPC levels and the sputum inflammatory cells and their sputum ECP levels.

CONCLUSION

Elevated DPPC levels are evident in induced sputum of all asthmatic children and they are significantly related to sputum ECP levels and pulmonary function test parameters. Nevertheless, the value of DPPC estimation in the clinical management of children with asthma remains to be determined.

Chorioamnionitis alters the response to surfactant in preterm infants

OBJECTIVE

To study the association between antenatal exposure to chorioamnionitis and the neonatal response to surfactant.

STUDY DESIGN

Prospective observational cohort of 301 preterm infants of gestational age < or = 32.0 weeks, 146 of whom received surfactant according to standardized criteria. Fraction of inspired oxygen (FiO(2)) requirement (using analysis of variance) and time to extubation (using Kaplan-Meier and Cox regression analyses) were compared between groups based on the presence of histological chorioamnionitis (HC) with or without fetal involvement (HC-, n = 88; HC + F-, n = 25; HC + F+, n = 33) and between infants who developed bronchopulmonary dysplasia (BPD) or died (n = 57) and BPD-free survivors (n = 89). Multiple logistic regression was performed to investigate the association between HC and BPD.

RESULTS

Compared with HC- infants, HC + F+ infants had significantly greater FiO(2) requirement and prolonged time to extubation postsurfactant, not accounted for by differences in gestational age and birth weight. Infants with BPD/death had a strikingly similar pattern of increased FiO(2) requirement postsurfactant. Moreover, in infants who received surfactant, HC + F+ status was associated with increased risk for BPD (odds ratio [OR] = 3.40; 95% confidence interval [CI] = 1.02-11.3; P = .047) and for BPD/death (OR = 2.72; 95% CI = 1.00-7.42; P = .049).

CONCLUSIONS

An impaired surfactant response was observed in preterm infants with severe chorioamnionitis and may be involved in the association between chorioamnionitis, mechanical ventilation, and the development of BPD.

Congenital diaphragmatic hernia: current status and review of the literature

Treatment of congenital diaphragmatic hernia (CDH) challenges obstetricians, pediatric surgeons, and neonatologists. Persistent pulmonary hypertension (PPHT) associated with lung hypoplasia in CDH leads to a high mortality rate at birth. PPHT is principally due to an increased muscularization of the arterioles. Management of CDH has been greatly improved by the introduction of prenatal surgical intervention with tracheal obstruction (TO) and by more appropriate postnatal care. TO appears to accelerate fetal lung growth and to increase the number of capillary vessels and alveoli. Improvement of postnatal care over the last years is mainly due to the avoidance of lung injury by applying low peak inflation pressure during ventilation. The benefits of other drugs or technical improvements such as the use of inhaled nitric oxide or extracorporeal membrane oxygenation (ECMO) are still being debated and no single strategy is accepted worldwide. Despite intensive clinical and experimental research, the treatment of newborn with CDH remains difficult.

Altered pulmonary interleukin-6 signaling in preterm infants developing bronchopulmonary dysplasia

Interleukin (IL)-6 signaling depends on the soluble IL-6 receptor (sIL-6R) and the soluble glycoprotein 130 (sgp130). To investigate the impact of IL-6 signaling on the pathogenesis of bronchopulmonary dysplasia of prematurity (BPD), IL-6, sIL-6R, and sgp130 were measured by enzyme-linked immunosorbent assay (ELISA) technique in tracheal aspirates of mechanically ventilated preterm infants. Infants developing BPD showed increased concentrations of IL-6, sIL-6R, and sgp-130 in their first week of life. These infants also had significantly higher molar ratios for IL-6/sIL-6R and IL-6/sgp130. The authors conclude that altered interleukin-6 signaling via the soluble receptors sIL-6R and sgp130 may play an important role in pulmonary inflammation of preterm infants.

Role of lung surfactant in respiratory disease: current knowledge in large animal medicine

Lung surfactant is produced by type II alveolar cells as a mixture of phospholipids, surfactant proteins, and neutral lipids. Surfactant lowers alveolar surface tension and is crucial for the prevention of alveolar collapse. In addition, surfactant contributes to smaller airway patency and improves mucociliary clearance. Surfactant-specific proteins are part of the innate immune defense mechanisms of the lung. Lung surfactant alterations have been described in a number of respiratory diseases. Surfactant deficiency (quantitative deficit of surfactant) in premature animals causes neonatal respiratory distress syndrome. Surfactant dysfunction (qualitative changes in surfactant) has been implicated in the pathophysiology of acute respiratory distress syndrome and asthma. Analysis of surfactant from amniotic fluid allows assessment of fetal lung maturity (FLM) in the human fetus and exogenous surfactant replacement therapy is part of the standard care in premature human infants. In contrast to human medicine, use and success of FLM testing or surfactant replacement therapy remain limited in veterinary medicine. Lung surfactant has been studied in large animal models of human disease. However, only a few reports exist on lung surfactant alterations in naturally occurring respiratory disease in large animals. This article gives a general review on the role of lung surfactant in respiratory disease followed by an overview of our current knowledge on surfactant in large animal veterinary medicine.

Age-related pulmonary emphysema in mice lacking alpha/beta hydrolase domain containing 2 gene

The alpha/beta hydrolase family genes have been identified as down-regulated genes in human emphysematous lungs. Although proteins in the alpha/beta hydrolase family generally act as enzymes, such as lipases, the specific functions of the Abhd2 protein are unknown. To examine the role of Abhd2 in the lung, we analyzed Abhd2 deficient mice obtained by gene trap mutagenesis. Abhd2 was expressed in the alveolar type II cells. Abhd2 deficiency resulted in a decreased level of phosphatidylcholine in the bronchoalveolar lavage. These mice developed spontaneous gradual progression of emphysema, due to increased macrophage infiltration, increased inflammatory cytokines, a protease/anti-protease imbalance and enhanced apoptosis. This phenotype is more akin to the pace of emphysema that develops in humans. Our findings suggest that derangement in alveolar phospholipid metabolism can induce emphysema, and that Abhd2 plays a critical role in maintaining lung structural integrity.

Innate immune activation and cystic fibrosis

Since inflammation and infection occur so early in infancy in cystic fibrosis, the function of innate immune defence in cystic fibrosis has been questioned by many investigators. This review aims to summarize the findings relating to the physical, humoral and cellular components of innate immune defence in cystic fibrosis, and highlights the roles of neutrophils, macrophages and epithelial cells in these activities. In addition, recently identified links between antioxidant defences and cystic fibrosis transmembrane conductance regulator (CFTR) function, and how these may impact on innate lung defence, are summarized.

KL4-surfactant (Lucinactant) protects human airway epithelium from hyperoxia

Exogenous surfactant is critical in the treatment of neonates with respiratory distress syndrome. Lucinactant (Surfaxin; Discovery Laboratories, Inc.) is a surfactant replacement therapy containing sinulpeptide, which may reduce lung inflammation. This study tested whether Lucinactant reduces markers of inflammation, damage and remodeling in human airway epithelial cells exposed to hyperoxia. Calu-3 monolayers cultured at an air-liquid interface were treated apically with 140 microL of normal saline, Lucinactant or Beractant (Survanta; Abbott Laboratories, Inc.). Treated monolayers were exposed to 60% O(2)/5% CO(2) for 24 or 72 h. Transepithelial resistance (TER; p < 0.001) and cell viability (p < 0.05) were greater in both surfactant groups compared with saline; by 72 h Lucinactant cells had greater TER than Beractant (p < 0.001). Surfactant treated groups secreted less IL-8 than saline (p < 0.001), whereas Lucinactant cells secreted less IL-6 than saline and Beractant (p < 0.001). Matrix metalloproteinase 7, expressed by saline and Beractant treated cells at 24 h, was attenuated by 72 h by Beractant (p < 0.001), but was never detected in Lucinactant cells. Histology indicated less injury with Lucinactant relative to Beractant and saline. These data suggest that Lucinactant was protective compared with Beractant and control.

Lung epithelium as a sentinel and effector system in pneumonia--molecular mechanisms of pathogen recognition and signal transduction

Pneumonia, a common disease caused by a great diversity of infectious agents is responsible for enormous morbidity and mortality worldwide. The bronchial and lung epithelium comprises a large surface between host and environment and is attacked as a primary target during lung infection. Besides acting as a mechanical barrier, recent evidence suggests that the lung epithelium functions as an important sentinel system against pathogens. Equipped with transmembranous and cytosolic pathogen-sensing pattern recognition receptors the epithelium detects invading pathogens. A complex signalling results in epithelial cell activation, which essentially participates in initiation and orchestration of the subsequent innate and adaptive immune response. In this review we summarize recent progress in research focussing on molecular mechanisms of pathogen detection, host cell signal transduction, and subsequent activation of lung epithelial cells by pathogens and their virulence factors and point to open questions. The analysis of lung epithelial function in the host response in pneumonia may pave the way to the development of innovative highly needed therapeutics in pneumonia in addition to antibiotics.

Bench-to-bedside review: Paediatric viral lower respiratory tract disease necessitating mechanical ventilation--should we use exogenous surfactant?

Treatment of infants with viral lower respiratory tract disease (LRTD) necessitating mechanical ventilation is mainly symptomatic. The therapeutic use of surfactant seems rational because significantly lower levels of surfactant phospholipids and proteins, and impaired capacity to reduce surface tension were observed among infants and young children with viral LRTD. This article reviews the role of pulmonary surfactant in the pathogenesis of paediatric viral LRTD. Three randomized trials demonstrated improved oxygenation and reduced duration of mechanical ventilation and paediatric intensive care unit stay in young children with viral LRTD after administration of exogenous surfactant. This suggest that exogenous surfactant is the first beneficial treatment for ventilated infants with viral LRTD. Additionally, in vitro and animal studies demonstrated that surfactant associated proteins SP-A and SP-D bind to respiratory viruses, play a role in eliminating these viruses and induce an inflammatory response. Although these immunomodulating effects are promising, the available data are inconclusive and the findings are unconfirmed in humans. In summary, exogenous surfactant in ventilated infants with viral LRTD could be a useful therapeutic approach. Its beneficial role in improving oxygenation has already been established in clinical trials, whereas the immunomodulating effects are promising but remain to be elucidated.

Distribution of surfactant proteins in type II pneumocytes of newborn, 14-day old, and adult rats: an immunoelectron microscopic and stereological study

Surfactant proteins (SP) have an important impact on the function of the pulmonary surfactant. In contrast to humans, rat lungs are immature at birth. Alveolarization starts on postnatal day 4. Little is known about the distribution of SP during postnatal alveolarization. By immunoelectron microscopy, we studied the distribution of SP-A, SP-D, SP-B, and precursors of SP-C in type II pneumocytes before, near the end and after alveolarization and in mature lungs. We determined the subcellular volume fractions and the relative labeling index to obtain information about preferential labeling of compartments and non-randomness of labeling. Independently of alveolarization, the overall cellular distribution of SP was non-random. A preferential labeling for SP-A and SP-D was found in small vesicles and multivesicular bodies (mvb). SP-B and precursors of SP-C were localized in mvb and lamellar bodies (lb). There are no postnatal changes in labeling for all three SP in these compartments. Labeling intensity for SP-B in lb increased in close correlation with a significant increase in the volume fractions of lb during alveolarization. Our results support the concept that postnatal alveolarization in rat lungs is associated with significant increases in the SP-B content in lb and volume fraction of lb in type II pneumocytes. The postnatal compartment-specific distribution of SP-A, precursors of SP-C and SP-D does not change.