Intratracheal administration of endotoxin attenuates hyperoxia-induced lung injury in neonatal rats

Antiviral activity of a novel mixture of natural antimicrobials, in vitro, and in a chicken infection model in vivo

The aim of this study was to test in vitro the ability of a mixture of citrus extract, maltodextrin, sodium chloride, lactic acid and citric acid (AuraShield L) to inhibit the virulence of infectious bronchitis, Newcastle disease, avian influenza, porcine reproductive and respiratory syndrome (PRRS) and bovine coronavirus viruses. Secondly, in vivo, we have investigated its efficacy against infectious bronchitis using a broiler infection model. In vitro, these antimicrobials had expressed antiviral activity against all five viruses through all phases of the infection process of the host cells. In vivo, the antimicrobial mixture reduced the virus load in the tracheal and lung tissue and significantly reduced the clinical signs of infection and the mortality rate in the experimental group E2 receiving AuraShield L. All these effects were accompanied by a significant reduction in the levels of pro-inflammatory cytokines and an increase in IgA levels and short chain fatty acids (SCFAs) in both trachea and lungs. Our study demonstrated that mixtures of natural antimicrobials, such AuraShield L, can prevent in vitro viral infection of cell cultures. Secondly, in vivo, the efficiency of vaccination was improved by preventing secondary viral infections through a mechanism involving significant increases in SCFA production and increased IgA levels. As a consequence the clinical signs of secondary infections were significantly reduced resulting in recovered production performance and lower mortality rates in the experimental group E2.

Mesenchymal stem cell treatment in hyperoxia-induced lung injury in newborn rats

BACKGROUND

The aim of this study was to evaluate the effectiveness of tracheally delivered mesenchymal stem cells (MSC) on lung pathology in a hyperoxia-induced lung injury (HILI) model in neonatal rats.

METHODS

For the HILI model, rat pups were exposed to 85-95% oxygen during the first 10 days of life. Rats were divided into six groups: room-air normoxia (n = 11); room air, sham (n = 11); hyperoxia exposed with normal saline as placebo (n = 9); hyperoxia exposed with culture medium of MSC (n = 10); hyperoxia exposed with medium remaining after harvesting of MSC (n = 8); and hyperoxia exposed with MSC (n = 17). Pathologic changes, number and diameter of alveoli, α-smooth muscle actin (α-SMA) expression and localization of MSC in the lungs were assessed.

RESULTS

Number of alveoli increased and alveolar diameter decreased in the mesenchymal stem cell group so that there were no differences when compared with the normoxia group (P = 0.126 and P = 0.715, respectively). Expression of α-SMA decreased significantly in the mesenchymal stem cell group compared with the placebo group (P < 0001). Green fluorescent protein-positive cells were found in lung tissue from all rats given MSC. Some green fluorescent protein-positive MSC also expressed surfactant protein-C.

CONCLUSION

Mesenchymal stem cells became localized in damaged lung tissue, and recovery approximated the room air control.

Cell type-dependent variation in paracrine potency determines therapeutic efficacy against neonatal hyperoxic lung injury

BACKGROUND AIMS

The aim of this study was to determine the optimal cell type for transplantation to protect against neonatal hyperoxic lung injury. To this end, the in vitro and in vivo therapeutic efficacies and paracrine potencies of human umbilical cord blood-derived mesenchymal stromal cells (HUMs), human adipose tissue-derived mesenchymal stromal cells (HAMs) and human umbilical cord blood mononuclear cells (HMNs) were compared.

METHODS

Hyperoxic injury was induced in vitro in A549 cells by challenge with H2O2. Alternatively, hyperoxic injury was induced in newborn Sprague-Dawley rats in vivo by exposure to hyperoxia (90% oxygen) for 14 days. HUMs, HAMs or HMNs (5 × 10(5) cells) were given intratracheally at postnatal day 5.

RESULTS

Hyperoxia-induced increases in in vitro cell death and in vivo impaired alveolarization were significantly attenuated in both the HUM and HAM groups but not in the HMN group. Hyperoxia impaired angiogenesis, increased the cell death and pulmonary macrophages and elevated inflammatory cytokine levels. These effects were significantly decreased in the HUM group but not in the HAM or HMN groups. The levels of human vascular endothelial growth factor and hepatocyte growth factor produced by donor cells were highest in HUM group, followed by HAM group and then HMN group.

CONCLUSIONS

HUMs exhibited the best therapeutic efficacy and paracrine potency than HAMs or HMNs in protecting against neonatal hyperoxic lung injury. These cell type-dependent variations in therapeutic efficacy might be associated or mediated with the paracrine potency of the transplanted donor cells.

Antenatal use of bosentan and/or sildenafil attenuates pulmonary features in rats with congenital diaphragmatic hernia

BACKGROUND

Lung hypoplasia, pulmonary persistent hypertension of the newborn and its morphological changes are the main features in congenital diaphragmatic hernia (CDH). This study was undertaken to investigate if antenatal use of sildenafil and/or bosentan attenuates vascular remodeling, promotes branching, and improves alveolarization in experimental nitrofeninduced CDH.

METHODS

Nitrofen (100 mg) was gavage-fed to pregnant rats at post conception day (PCD) 9 to induce CDH. The rats were randomized to 5 groups: 1) control; 2) nitrofen; 3) nitrofen+sildenafil 100 mg/kg per day at PCD 16-20; 4) nitrofen+bosentan 30 mg/kg per day, at PCD 16-20, and 5) nitrofen+bosentan+sildenafil, same doses and administration days. After cesarean delivery, the offsprings were sacrificed. The diaphragmatic defect and pulmonary hypoplasia were identified, and the lungs were dissected. Arterial wall thickness, bronchiolar density and alveolarization were assessed.

RESULTS

The offsprings with CDH were characterized by severe pulmonary hypoplasia (lung weight-to-body weight ratio: 0.0263 [95% confidence interval (CI) 0.0242-0.0278)] in the nitrofen group versus 0.0385 (95% CI 0.0355-0.0424) in the control group (P=0.0001). Pulmonary arterial wall thickness was decreased to 3.0 (95% CI 2.8-3.7) μm in the nitrofen+sildenafil group versus 5.0 (95% CI 4.1-4.9) μm in the nitrofen group (P=0.02). Terminal bronchioles increased to 13.7 (95% CI 10.7-15.2) μm in the nitrofen+bosentan group in contrast to 8.7 (95% CI 7.2-9.4) μm in the nitrofen group (P=0.002). More significant differences (P=0.0001) were seen in terminal bronchioles in the nitrofen+sildenafil+bosentan group than in the nitrofen group [14.0 (95% CI 12.5-15.4) μm versus 8.5 (95% CI 7.1-9.3) μm]. Pulmonary arterial wall thickness was also decreased in the former group.

CONCLUSIONS

In this rat model, antenatal treatment with sildenafil attenuates vascular remodeling. Bosentan promotes the development of terminal bronchioles in nitrofen-induced CDH.

The NF-κB inhibitory proteins IκBα and IκBβ mediate disparate responses to inflammation in fetal pulmonary endothelial cells

Exposure to intrauterine inflammation impairs lung growth but paradoxically protects the neonatal pulmonary vasculature from hyperoxic injury. The mechanisms mediating these contradictory effects are unknown. The objective is to identify the role of NF-κB in mediating cytoprotective and proinflammatory responses to inflammation in the fetal pulmonary endothelium. In newborn rats exposed to intra-amniotic LPS, we found increased expression of the NF-κB target gene manganese superoxide dismutase (MnSOD) in the pulmonary endothelium. Supporting these in vivo findings, LPS induced NF-κB activation and MnSOD expression in isolated fetal pulmonary arterial endothelial cells. In addition, LPS exposure caused apoptosis and suppressed cellular growth and induced P-selectin expression. LPS-induced NF-κB activation that proceeded through specific isoforms of the inhibitory protein IκB mediated these diverse responses; NF-κB signaling through IκBα degradation resulted in MnSOD upregulation and preserved cell growth, whereas NF-κB signaling through IκBβ degradation mediated apoptosis and P-selectin expression. These findings suggest that selective inhibition of NF-κB activation that results from IκBβ degradation preserves the enhanced antioxidant defense and protects the developing pulmonary vascular endothelium from ongoing inflammatory injury.

Endotoxin inhalation alters lung development in neonatal mice

BACKGROUND

Childhood asthma is a significant public health problem. Epidemiologic evidence suggests an association between childhood asthma exacerbations and early life exposure to environmental endotoxin. Although the pathogenesis of endotoxin-induced adult asthma is well studied, questions remain about the impact of environmental endotoxin on pulmonary responsiveness in early life.

METHODS

We developed a murine model of neonatal/juvenile endotoxin exposures approximating those in young children and evaluated the lungs inflammatory and remodeling responses.

RESULTS

Persistent lung inflammation induced by the inhalation of endotoxin in early life was demonstrated by the influx of inflammatory cells and pro-inflammatory mediators to the airways and resulted in abnormal alveolarization.

CONCLUSIONS

Results of this study advance the understanding of the impact early life endotoxin inhalation has on the lower airways, and demonstrates the importance of an experimental design that approximates environmental exposures as they occur in young children.