Bronchopulmonary Dysplasia Lung Injury Research Articles

CircABPD1 alleviates oxidative lung injury of bronchopulmonary dysplasia through regulating miR-330-3p/HIF1α axis

In the NICU, bronchopulmonary dysplasia (BPD) is a concerning common respiratory complication in preterm and low birth-weight infants. Clinical studies have confirmed that human milk has an important nutritional role for children with BPD, therefore, dentification of beneficial components in human milk that prevent BPD is urgently needed. Our previous work showed that human milk exosomes (HM-Exos) could inhibit apoptosis of alveolar type II epithelial cells (AT II), and the circular RNA (circRNA)-circABPD1 were highly expressed in preterm colostrum milk exosomes. Exosomes transport circRNAs that are stable and may exert anti-inflammatory and immune effects attracted the attention of researchers, but the role and mechanism of human milk exosome-derived circABPD1 in BPD remains unclear. Here, we constructed BPD in vivo and in vitro models through exposure to hyperoxia, verified the effect of circABPD1 and revealed its mechanism through rescue experiments. We found that circABPD1 had circRNA properties, and overexpression of circABPD1 could improve reduced alveolar number, enlarged the alveolar linear intercept in vivo models of BPD, promote cell proliferation, reduce oxidative stress levels and alleviate lung epithelial cell damage in vivo and in vitro models. Mechanistically, circABPD1 targets miR-330–3p and regulates the expression of HIF1α. These results suggest that circABPD1 can improve the pathologoical changes of bronchopulmonary dysplasia, promote cell proliferation, inhibit oxidative stress level, and alleviate lung injury by targeting the miR-330–3p/HIF1α axis, which provides a new idea for the prevention and treatment of bronchopulmonary dysplasia.

ILC2 regulates hyperoxia-induced lung injury via an enhanced Th17 cell response in the BPD mouse model

BackgroudRecent research has focused on the role of immune cells and immune responses in the pathogenesis of bronchopulmonary dysplasia (BPD), but the exact mechanisms have not yet been elucidated. Previously, the key roles of type 2 innate lymphoid cells (ILC2) in the lung immune network of BPD were explored. Here, we investigated the role Th17 cell response in hyperoxia-induced lung injury of BPD, as well as the relationship between ILC2 and Th17 cell response.MethodsA hyperoxia-induced BPD mouse model was constructed and the pathologic changes of lung tissues were evaluated by Hematoxylin-Eosin staining. Flow cytometry analysis was conducted to determine the levels of Th17 cell, ILC2 and IL-6+ILC2. The expression levels of IL-6, IL-17 A, IL-17 F, and IL-22 in the blood serum and lung tissues of BPD mice were measured by ELISA. To further confirm the relationship between ILC2 and Th17 cell differentiation, ILC2 depletion was performed in BPD mice. Furthermore, we used immunomagnetic beads to enrich ILC2 and then flow-sorted mouse lung CD45+Lin-CD90.2+Sca-1+ILC2. The sorted ILC2s were injected into BPD mice via tail vein. Following ILC2 adoptive transfusion, the changes of Th17 cell response and lung injury were detected in BPD mice.ResultsThe expression levels of Th17 cells and Th17 cell-related cytokines, including IL-17 A, IL-17 F, and IL-22, were significantly increased in BPD mice. Concurrently, there was a significant increase in the amount of ILC2 and IL-6+ILC2 during hyperoxia-induced lung injury, which was consistent with the trend for Th17 cell response. Compared to the control BPD group, ILC2 depletion was found to partially abolish the Th17 cell response and had protective effects against lung injury after hyperoxia. Furthermore, the adoptive transfer of ILC2 enhanced the Th17 cell response and aggravated lung injury in BPD mice.ConclusionsThis study found that ILC2 regulates hyperoxia-induced lung injury by targeting the Th17 cell response in BPD, which shows a novel strategy for BPD immunotherapy.

PAR2 Overexpression is Involved in the Occurrence of Hyperoxygen-Induced Bronchopulmonary Dysplasia in Rats

Background Bronchopulmonary dysplasia is a chronic lung disease commonly seen in preterm infants. It is characterized by delayed development of the alveoli and lung fibrosis. Protease-activated receptor 2 (PAR2) is an inflammatory driver that plays a proinflammatory role mainly through the P38 MAPK/NF-κB signaling pathway. Methods Newborn rat pups were kept under air or oxygen at >60% concentration. Lung tissues were collected at postnatal days (P) 1, 4, 7, and 10 to observe pathological changes and take measurements. Results In the hyperoxic group, P4 and P7 rats showed delayed alveolar development, septal thickening, and disturbances in alveolar structure.PAR2, P38 MAPK, NF-κB, and IL-18 expression at P4, P7, and P10 was significantly higher than in the air group. Conclusion PAR2 is involved in lung injury induced by persistent hyperoxia. Activated PAR2 promotes IL-18 overexpression through the P38 MAPK/NF-κB signaling pathway, which may be an important mechanism of PAR2-mediated lung injury in bronchopulmonary dysplasia.

Microvesicles Derived from Human Umbilical Cord Mesenchymal Stem Cells Enhance Alveolar Type II Cell Proliferation and Attenuate Lung Inflammation in a Rat Model of Bronchopulmonary Dysplasia.

Although it is known that exosomes derived from human umbilical cord mesenchymal stem cells (hUCMSCs) alleviate hyperoxic lung injury of bronchopulmonary dysplasia (BPD) in animal models, the role of microvesicles (MVs) derived from hUCMSCs in BPD is poorly defined. Furthermore, antenatal inflammation has been linked to high risk of BPD in preterm infants. The purpose of this study was to explore whether MVs derived from hUCMSCs can preserve lung structure and function in an antenatal lipopolysaccharide- (LPS-) induced BPD rat model and to clarify the underlying mechanism. We demonstrate that antenatal LPS induced alveolar simplification, altered lung function, and dysregulated pulmonary vasculature, which restored by hUCMSCs and MVs treatment. Furthermore, MVs were large vesicles with a diameter of 100-900 nanometers and mostly uptaken by alveolar epithelial type II cells (AT2) and macrophages. Compared with the LPS-exposed group, MVs restored the AT2 cell number and SP-C expression in vivo and promoted the proliferation of AT2 cells in vitro. MVs also restored the level of IL-6 and IL-10 in lung homogenate. Additionally, PTEN/AKT and MAPK pathways were associated with the protection of MVs. Taken together, this study suggests MVs derived from hUCMSCs improve lung architecture and function in an antenatal LPS-induced BPD rat model by promoting AT2 cell proliferation and attenuating lung inflammation; thus, MVs provide a promising therapeutic vehicle for BPD treatment.

Mesenchymal Stem Cell-Derived Extracellular Vesicles for the Treatment of Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is the most common chronic respiratory disease in premature infants. However, there is a lack of effective treatment. Mesenchymal stromal cells derived extracellular vesicles (MSC-EVs), as nano- and micron-sized heterogeneous vesicles secreted by MSCs, are the main medium for information exchange between MSCs and injured tissue and organ, playing an important role in repairing tissue and organ injury. EVs include exosomes, microvesicles and so on. They are rich with various proteins, nucleic acids, and lipids. Now, EVs are considered as a new way of cell-to-cell communication. EVs mainly induce regeneration and therapeutic effects in different tissues and organs through the biomolecules they carry. The surface membrane protein or loaded protein and nucleic acid molecules carried by EVs, can activate the signal transduction of target cells and regulate the biological behavior of target cells after binding and cell internalization. MSC-EVs can promote the development of pulmonary vessels and alveoli and reduce pulmonary hypertension (PH) and inflammation and play an important role in the repair of lung injury in BPD. The regeneration potential of MSC-EVs is mainly due to the regulation of cell proliferation, survival, migration, differentiation, angiogenesis, immunoregulation, anti-inflammatory, mitochondrial activity and oxidative stress. As a new type of cell-free therapy, MSC-EVs have non-immunogenic, and are small in size and go deep into most tissues. What’s more, it has good biological stability and can be modified and loaded with drugs of interest. Obviously, MSC-EVs have a good application prospect in the treatment of lung injury and BPD. However, there are still many challenges to make MSC-EVs really enter clinical application.

Acetate Downregulates the Activation of NLRP3 Inflammasomes and Attenuates Lung Injury in Neonatal Mice With Bronchopulmonary Dysplasia.

Background: Bronchopulmonary dysplasia (BPD) is a common pulmonary complication in preterm infants. Acetate is a metabolite produced by the gut microbiota, and its anti-inflammatory function is well known. The role of acetate in BPD has not been studied. Here, we investigate the effects of acetate on lung inflammation and damage in mice model of BPD.Objective: To investigate the role of acetate in the development of BPD.Methods: C57BL/6 mice were randomly divided into three groups on the 3rd day after birth: room air group, hyperoxia group, and hyperoxia + acetate (250 mM, 0.02 ml/g) group. The expression of inflammatory factors was determined by ELISA and RT-PCR, and NLRP3 and caspase-1 were detected by Western blot. High-throughput sequencing was used to detect bacterial communities in the mice intestines.Results: After acetate treatment, the expression levels of TNF-α, IL-1β, IL-18, NLRP3, and caspase-1 were significantly reduced, while the expression of GPR43 was increased. In the BPD mice treated with acetate, the proportion of Escherichia-Shigella was lower than in placebo-treated BPD mice, while the abundance of Ruminococcus was increased.Conclusions: These results indicate that acetate may regulate intestinal flora and reduce inflammatory reactions and lung injury in BPD. Therefore, acetate may be an effective drug to protect against neonatal BPD.

Human amnion cell-derived extracellular vesicles in the treatment of bronchopulmonary dysplasia and associated pulmonary hypertension

Background & Aim We previously showed that human amnion epithelial cells (hAECs) are a viable source of cell therapy for established bronchopulmonary dysplasia (BPD). This work has culminated in a first-in-human clinical trial in babies with established BPD. In this current study, we sought to assess the therapeutic potential of hAEC-derived EVs (hAEC-EVs) in an experimental model of BPD. Methods, Results & Conclusion Methods Lipopolysaccharide (LPS) was introduced to C57bl6 mouse fetuses intra-amniotically at E16 prior to exposure to 65% oxygen (hyperoxia) at birth. hAEC-EVs were injected intravenously on postnatal day (PND) 4. One cohort of mice were culled on either postnatal day PND7 or PND14, while another cohort were kept in hyperoxia until PND 28, following which they were recovered under normoxia conditions for a further 2 weeks or 6 weeks for cardiovascular assessment. Results The isolated hAEC-EVs had distinct cup shaped morphology with average size of 80-140nm. ALIX, Grp94 and HLA-G were expressed in EVs, and Pathway enrichment analysis showed that endothelin signaling pathway, Wnt signaling pathway, and inflammation mediated by chemokine and cytokine signaling pathway were enriched in hAEC-EVs. In the mouse model of experimental BPD, hAEC-EV administration improved tissue-to-airspace ratio and septal crest density in a dose-dependent manner. hAEC-EVs reduced the levels of inflammatory cytokines such as interleukin (IL)-1β and tumour necrosis factor-alpha (TNF-α) on PND7. The improvement of lung injury was associated with the increase of the percentage of type II alveolar cells (AT2s) at both PND7 and 14. Surprisingly, neonatal hAEC-EV delivery reduced airway hyper-responsiveness, mitigated pulmonary hypertension and prevented right ventricle hypertrophy that associated with BPD-like lung injury at week 6. These improvements persisted till week 10. All these observations showed that HAEC-EVs mitigate the BPD lung injury through decreasing inflammation, activating local AT2 niche and reversing pulmonary artery remodeling. Conclusions hAEC-derived EVs had similar therapeutic effects to hAECs in this mouse model of experimental BPD. hAEC-derived EVs improved lung structure and reduced lung inflammation in a manner similar to that achieved using hAECs. EVs repaired lung injury partly through the activation of local stem/progenitor cells. Furthermore, hAEC-EV administration had long term benefit in improving lung function, preventing pulmonary hypertension and right ventricle hypertrophy.

Loss of interleukin-6 enhances the inflammatory response associated with hyperoxia-induced lung injury in neonatal mice.

In bronchopulmonary dysplasia (BPD), decreased angiogenesis and alveolarization is associated with pulmonary cell death and inflammation. It is commonly observed in premature infants who required mechanical ventilation and oxygen therapy. Since enhanced interleukin-6 (IL-6) expression has been reported in infants with BPD, it was hypothesized that a decrease in IL-6 may enhance lung inflammation and decrease hyperoxia-induced neonatal lung injury in mice. In the current study, newborn wild-type (WT) and IL-6 null mice were treated with 85% O2 (hyperoxia) or 21% O2 (normoxia) for 96 h. Although the increased volume and decreased quantity of alveoli was triggered by hyperoxia in WT and IL-6 null mice, transcription and translation of proinflammatory cytokines (monocyte chemoattractant protein-1, IL-10, IL-12 and tumor necrosis factor-α) and pulmonary cell death (caspase stimulation and terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling staining) were significantly enhanced in IL-6 null mice compared with WT mice. These results suggest that the crosstalk between inflammation and cell death may be involved in hyperoxia-induced lung injury in BPD. Future treatment approaches for bronchopulmonary dysplasia should be based on the suppression of cytokine expression.

Protective effect of Rhubarb on newborn rats with bronchopulmonary dysplasia

Objective To investigate the effect of Rhubarb on bronchopulmonary dysplasia(BPD) and its potential mechanism. Methods Neonatal Sprague-Dawley rats (postnatal day 4) were exposed to 600 mL/L O2 to induce BPD.The experimental rats were randomly divided into 4 groups with 16 in each group: air+ saline group, air+ Rhubarb(600 mg/kg)group, and hyperoxia+ saline group, and hyperoxia+ Rhubarb group.The rats were sacrificed and lung tissues were obtained on day 14 and 21 after birth.Hematoxylin-easin staining was used to detect the pathomorphology of the lungs.Apoptosis of the lung tissue was detected by means of TdT-mediated dUTP nick-end labeling(TUNEL). The expression of Fas was detected by adopting Western blot.The activity of Caspase-8 and Caspase-3 was detected by using spectrophotometer. Results The lung structure of rats was markedly abnormal (decreased, enlarged and simplified alveoli) after being exposed to hyperoxia at any time point.The apoptosis indexes (39.91±1.91 vs.10.11±1.64, 48.80±4.51 vs.12.90±3.18), the expression levels of Fas (0.47±0.02 vs.0.21±0.01, 0.55±0.02 vs.0.22±0.01) and the activities of Caspase-8 (52.59±1.23 vs.40.74±1.08, 60.20±3.48 vs.40.39±2.47) and Caspsase 3 (57.17±1.88 vs.42.00±1.19, 64.57±2.79 vs.41.54±1.27) were all increased in the hyperoxia+ saline group compared with those in the air+ saline group on day 14 and 21, and the differences were statistically significant(all P<0.001). However, compared with the hyperoxia+ saline group, Rhubarb administration dramatically decreased pulmonary apoptosis index (26.49±2.65 vs.22.97±3.66), Fas protein level (0.27±0.03 vs.0.31±0.01) and the activity of Caspase-8 (32.70±2.69 vs.30.66±4.48) and Caspase-3 (44.94±1.60 vs.44.59±1.66), and the differences were statistically significant(all P<0.001). Meanwhile, lung damage after hyperoxia was significantly attenuated in the hyperoxia+ Rhubarb group. Conclusion Rhubarb can reduce the hyperoxic lung injury of BPD by reducing the apoptosis of newborn rat lung tissue cells, and the mechanism may involve the apoptosis pathway of Fas. Key words: Bronchopulmonary dysplasia; Rhubarb; Apoptosis

Role of Fatty Acid Oxidation in Hyperoxia-induced Apoptosis in Neonatal Lung Endothelial Cells: Implications for Lung Injury and Repair

In neonates, hyperoxia causes lung injury characterized by impaired vascularization and alveolarization. These are the hallmarks of bronchopulmonary dysplasia (BPD), a chronic lung disease in premature infants with long-term sequelae. The pulmonary vascular bed is essential for alveolar formation during late stages of lung development. Although endothelial cells (ECs) rely mainly on glycolysis for bioenergetics, they have metabolic flexibility to maintain cell function under stress. It is unknown whether hyperoxia alters EC metabolism and what are the consequences on lung injury and repair. We hypothesize that hyperoxia causes metabolic reprogramming leading to EC dysfunction and lung injury in neonatal mice. We exposed mouse fetal lung EC line and primary lung microvascular ECs from neonatal mice to air (21% O2/5% CO2) and hyperoxia (95% O2/5% CO2). Some cultures were placed in air for 24 h post exposure (air recovery). Hyperoxia reduced mitochondrial respiration in lung ECs as determined by the Seahorse XF24 Analyzer. Interestingly, hyperoxia specifically increased fatty acid oxidation (FAO), which was reduced when lung ECs were recovered in air after hyperoxia. This was associated with increased apoptosis in hyperoxia followed by air recovery. Enhancing FAO by L-carnitine (0.5 mM) reduced whereas inhibiting long-chain FA entry into mitochondria by a carnitine palmitoyltransferase 1 inhibitor (etomoxir, 100 μM) augmented hyperoxia-induced apoptosis. Furthermore, etomoxir (30 mg/kg) aggravated hyperoxia-induced simplification of the alveoli in neonatal mice, which was attenuated by L-carnitine (300 mg/kg). In conclusion, hyperoxia has long-term effects on FAO, which may affect lung EC survival and could lead to impaired vascularization and alveolarization in neonatal lungs. Targeting FAO could be a potential therapeutic approach to ameliorate lung injury in BPD.

Study of the variation in expression and the significance of markers for alveolar epithelial cells in bronchopulmonary dysplasia newborn rats

Objective To investigate the variation in expression and the significance of markers indicating typeⅠalveolar epithelial cells(AECⅠ) and type Ⅱ alveolar epithelial cells(AECⅡ) in hyperoxia induced bronchopulmonary dysplasia(BPD) model. Methods A total of 80 term normal Wistar rats were randomly devided into model group (85% oxygen) or control group (room air) within 12 h after birth, with 40 rats in each group.On day 7, day 14, day 21 after exposure, the pathological characteristics of lung tissues were observed using HE staining, the expression and location of AECⅠ marker aquaporin 5(AQP5) and AECⅡ marker surfactant protein-C (SP-C) were examined using immunofluorescence double staining.Western blot analysis was employed to examine the expressions levels of AQP5 and SP-C proteins, while real-time PCR was used to evaluate the mRNA expression of AQP5 and SP-C. Results Alveolar developmental disorder was observed in lung tissues of the model group, including fewer, larger, simplified alveoli, thicker alveolar walls, and fewer alveolar secondary septa.Immunofluorescence double staining showed increased and disorganized AQP5 and SP-C expression, with significantly higher ratio of double-stained cells/SP-C positive cells in the model group (P<0.001). Comparing to the control group, the expression of AQP5 and SP-C protein increased from 7 d after hyperoxia exposure, which continued to 21 d. The mRNA expression levels of these two markers both significantly increased in the model group compared with the control group, with AQP5 starting from 7 d while SP-C starting from 14 d after hyperoxia exposure (P<0.05), and the difference between two groups became more significant with the exposure time extending. Conclusion The expression of AECⅠ marker AQP5 and AECⅡ marker SP-C both increase in the lung tissues of hyperoxia induced BPD newborn rats, with more AECⅡ transdifferentiated into AECⅠ.These changes of the markers indicate that there is excessive transdifferentiation of AECⅡ in the recovery process after BPD lung injury. Key words: Transdifferentiation; Alveolar epithelial cell; Bronchopulmonary dysplasia; Hyperoxia; Rats

Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia.

Vitamin A (retinol) plays an important role in epithelial regeneration during recovery from lung injury in bronchopulmonary dysplasia (BPD). Dexamethasone is used in the postnatal treatment of very low birth weight (VLBW) neonates with BPD. To test the hypothesis that the vitamin A status is critical for the beneficial pulmonary response to dexamethasone, we performed a prospective cohort study in which we characterized the changes in plasma concentrations of vitamin A and retinol-binding protein (RBP) in response to dexamethasone, and correlated these changes with the pulmonary outcome. VLBW neonates (birth weight <1350 g, gestational age <31 weeks, postnatal age >10 days), who had presumptive diagnosis of severe BPD and need for high ventilatory support (fraction of inspired oxygen >/=.6, mean airway pressure >/=7 cm H(2)O), were treated with a seven-day course of dexamethasone (.5 mg/kg/d x 2 days,.25 mg/kg/d x 2 days,.1 mg/kg/d x 3 days). Plasma concentrations of vitamin A and RBP were determined sequentially at baseline, and during and after dexamethasone treatment. Pulmonary response to dexamethasone was graded daily using a composite ventilation score. The changes in plasma vitamin A and RBP concentrations were compared between infants with a positive (beneficial) pulmonary response to dexamethasone and those with a negative response. Among 23 infants studied, 13 showed a positive pulmonary response to dexamethasone, as indicated by successful weaning from supplemental oxygen and mechanical ventilation, whereas 10 showed a negative response. A significant, yet short-term, increase in plasma concentrations of both vitamin A and RBP was observed in most infants treated with dexamethasone. The plasma vitamin A and RBP responses to dexamethasone tended to be higher in infants with a positive pulmonary response than in those with a negative response. Accounting for gender, a vitamin A response with each 10.0 microg/dL increment in plasma vitamin A concentration was associated with a 60% increase in the odds favoring a positive pulmonary response to dexamethasone. Postnatal dexamethasone treatment in VLBW neonates with BPD induces a significant, yet short-term, increase in plasma concentrations of both vitamin A and RBP. This increase probably results from endogenous mobilization of vitamin A from the liver. Our data suggest that the beneficial pulmonary response to dexamethasone in infants with BPD is influenced, at least in part, by the vitamin A status, and that gender plays a role in this response.vitamin A, dexamethasone, bronchopulmonary dysplasia.