MicroRNA-214 promotes alveolarization in neonatal rat models of bronchopulmonary dysplasia via the PlGF-dependent STAT3 pathway

Targeting miR-146b-5p to Regulate KDM6B Expression Aggravates Bronchopulmonary Dysplasia

miR-146b-5p has been studied to be highly expressed in bronchopulmonary dysplasia (BPD), but whether it is involved in regulating the process of BPD in premature infants remains unclear. This study was to explore miR-146b-5p in premature BPD and reveal its molecular mechanism. BPD mouse model and high-oxygen MLE-12 cell model were established. HE staining, TUNEL staining, and IF staining were conducted to evaluate the pathological injury and protein expression in mouse lung tissue. LDH assay, MMT assay, and flow cytometry were achieved to evaluate cytotoxicity, cell viability, and apoptosis. ELISA and immunoblotting were performed to evaluate inflammatory cytokines and Wnt pathway proteins in lung tissues and cells. Dual-luciferase reporter assay and RIP assay were needed to examine the targeting relationship between miR-146b-5p and KDM6B. miR-146b-5p was abundantly expressed in BPD and KDM6B was lowly expressed. miR-146b-5p knockdown improved hyperoxia-induced lung epithelial cell inflammation and apoptosis in both models. miR-146b-6p upregulation or KDM6B downregulation aggravated hyperoxia-induced inflammation and apoptosis of lung epithelial cells. This effect of overexpressing miR-146b-5p was rescued by forcing KDM6B. MiR-146b-5p activated Wnt signaling by regulating KDM6B. miR-146b-5p activates the Wnt pathway through targeted regulation of KDM6B, thereby aggravating hyperoxia-induced inflammation and apoptosis of lung epithelial cells.

Strategies for the prevention of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a common morbidity affecting preterm infants and is associated with substantial long-term disabilities. The pathogenesis of BPD is multifactorial, and the clinical phenotype is variable. Extensive research has improved the current understanding of the factors contributing to BPD pathogenesis. However, effectively preventing and managing BPD remains a challenge. This review aims to provide an overview of the current evidence regarding the prevention of BPD in preterm infants, offering practical insights for clinicians.

Recent progress in neonatal hyperoxic lung injury

With the progress in neonatal intensive care, there has been an increase in the survival rates of premature infants. However, this has also led to an increased incidence of neonatal hyperoxia lung injury and bronchopulmonary dysplasia (BPD), whose pathogenesis is believed to be influenced by various prenatal and postnatal factors, although the exact mechanisms remain unclear. Recent studies suggest that multiple mechanisms might be involved in neonatal hyperoxic lung injury and BPD, with sex also possibly playing an important role, and numerous drugs have been proposed and shown promise for improving the treatment outcomes of hyperoxic lung injury. Therefore, this paper aims to analyze and summarize sex differences in neonatal hyperoxic lung injury, potential pathogenesis and treatment progress to provide new ideas for basic and clinical research in this field.

Lysine demethylase KDM3A alleviates hyperoxia-induced bronchopulmonary dysplasia in mice by promoting ETS1 expression

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease among neonates, with increasing morbidity and mortality. This study aims to investigate the effect and mechanism of lysine demethylase 3A (KDM3A) on hyperoxia-induced BPD. Hyperoxia-induced BPD mouse and alveolar epithelial cell models were constructed. The effects of hyperoxia on lung development were evaluated by histological and morphological analysis. The levels of KDM3A, E26 transformation specific-1 (ETS1), H3 lysine 9 dimethylation (H3K9me2), and endoplasmic reticulum (ER) stress-related indexes were quantified by RT-qPCR, Western blot, and IF staining. Cell apoptosis was assessed by flow cytometry and TUNEL staining. Transfection of oe-ETS1, oe-KDM3A, and sh-ETS1 was applied in hyperoxia-induced alveolar epithelial cells to explore the mechanism of the KDM3A/ETS1 axis in hyperoxia-induced apoptosis. KDM3A inhibitor IOX1 was applied to validate the in vivo effect of KDM3A in hyperoxia-induced BPD mice. The results displayed that hyperoxia-induced BPD mice showed reduced body weight, severe destruction of alveolar structure, decreased radial alveolar count (RAC), and increased mean linear intercept (MLI) and mean alveolar diameter (MAD). Further, hyperoxia induction down-regulated ETS1 expression, raised ER stress levels, and increased apoptosis rate in BPD mice and alveolar epithelial cells. However, transfection of oe-ETS1 improved the above changes in hyperoxia-induced alveolar epithelial cells. Moreover, transfection of oe-KDM3A up-regulated ETS1 expression, down-regulated H3K9me2 expression, inhibited ER stress, and reduced apoptosis rate in hyperoxia-induced alveolar epithelial cells. In addition, transfection of sh-ETS1 reversed the inhibitory effect of KDM3A on hyperoxia-induced apoptosis by regulating ER stress. In vivo experiments, KDM3A inhibitor IOX1 intervention further aggravated BPD in newborn mice. In a word, KDM3A alleviated hyperoxia-induced BPD in mice by promoting ETS1 expression.

ETS1 Ameliorates Hyperoxia-Induced Bronchopulmonary Dysplasia in Mice by Activating Nrf2/HO-1 Mediated Ferroptosis

PURPOSE

Bronchopulmonary dysplasia (BPD) is associated with hyperoxia-induced oxidative stress-associated ferroptosis. This study examined the effect of E26 oncogene homolog 1 (ETS1) on oxidative stress-associated ferroptosis in BPD.

METHODS

Hyperoxia-induced A549 cells and neonatal mice were used to establish BPD models. The effects of ETS1 on hyperoxia-induced ferroptosis-like changes in A549 cells were investigated by overexpression of ETS1 plasmid transfection and erastin treatment. Glucose consumption, lactate production, and NADPH levels were assessed by the glucose, lactate, and NADP+/NADPH assay kits, respectively. The potential regulatory relationship between ETS1 and Nrf2/HO-1 was examined by treating hyperoxia-induced A549 cells with the Nrf2 inhibitor ML385. ETS1 effect on the Nrf2 promoter was explored by dual-luciferase reporter and chromatin immunoprecipitation assay. The effect of ETS1 on the symptoms of BPD mice was examined by injecting an adenovirus overexpressing ETS1.

RESULTS

ETS1 overexpression increased hyperoxia-induced cell viability, glucose consumption, lactate production, and NADPH levels and reduced inflammation and apoptosis in A549 cells. In animal experiments, ETS1 overexpression prevented weight loss, airway enlargement, and reductions in radial alveolar counts in BPD mice, while reducing the mean linear intercept, mean alveolar diameter and inflammation. ETS1 overexpression suppressed PTGS2 and CHAC1 expression, reduced ROS, MDA and ferrous iron (Fe2+) production and increased GSH levels in hyperoxia-induced A549 cells and BPD mice. In addition, ETS1 can bind to the Nrf2 promoter region and thus promote Nrf2 transcription. ETS1 overexpression increased the mRNA and protein levels of Nrf2, HO-1, xCT, and GPX4 in hyperoxia-induced A549 cells and BPD mice. In hyperoxia-induced A549 cells, erastin and ML385 treatment abolished the effect of ETS1 overexpression.

CONCLUSION

ETS1 is important in oxidative stress-related ferroptosis in a hyperoxia-induced BPD model, and the effect is partially mediated by the Nrf2/HO-1 axis.

Molecular mechanisms of cell death in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) in neonates is the most common pulmonary disease that causes neonatal mortality, has complex pathogenesis, and lacks effective treatment. It is associated with chronic obstructive pulmonary disease, pulmonary hypertension, and right ventricular hypertrophy. The occurrence and development of BPD involve various factors, of which premature birth is the most crucial reason for BPD. Under the premise of abnormal lung structure and functional product, newborns are susceptible to damage to oxides, free radicals, hypoxia, infections and so on. The most influential is oxidative stress, which induces cell death in different ways when the oxidative stress balance in the body is disrupted. Increasing evidence has shown that programmed cell death (PCD), including apoptosis, necrosis, autophagy, and ferroptosis, plays a significant role in the molecular and biological mechanisms of BPD and the further development of the disease. Understanding the mode of PCD and its signaling pathways can provide new therapeutic approaches and targets for the clinical treatment of BPD. This review elucidates the mechanism of BPD, focusing on the multiple types of PCD in BPD and their molecular mechanisms, which are mainly based on experimental results obtained in rodents.

Oxygen toxicity: cellular mechanisms in normobaric hyperoxia

In clinical settings, oxygen therapy is administered to preterm neonates and to adults with acute and chronic conditions such as COVID-19, pulmonary fibrosis, sepsis, cardiac arrest, carbon monoxide poisoning, and acute heart failure. In non-clinical settings, divers and astronauts may also receive supplemental oxygen. In addition, under current standard cell culture practices, cells are maintained in atmospheric oxygen, which is several times higher than what most cells experience in vivo. In all the above scenarios, the elevated oxygen levels (hyperoxia) can lead to increased production of reactive oxygen species from mitochondria, NADPH oxidases, and other sources. This can cause cell dysfunction or death. Acute hyperoxia injury impairs various cellular functions, manifesting ultimately as physiological deficits. Chronic hyperoxia, particularly in the neonate, can disrupt development, leading to permanent deficiencies. In this review, we discuss the cellular activities and pathways affected by hyperoxia, as well as strategies that have been developed to ameliorate injury.

Pharmacotherapy in Bronchopulmonary Dysplasia: What Is the Evidence?

Bronchopulmonary Dysplasia (BPD) is a multifactorial disease affecting over 35% of extremely preterm infants born each year. Despite the advances made in understanding the pathogenesis of this disease over the last five decades, BPD remains one of the major causes of morbidity and mortality in this population, and the incidence of the disease increases with decreasing gestational age. As inflammation is one of the key drivers in the pathogenesis, it has been targeted by majority of pharmacological and non-pharmacological methods to prevent BPD. Most extremely premature infants receive a myriad of medications during their stay in the neonatal intensive care unit in an effort to prevent or manage BPD, with corticosteroids, caffeine, and diuretics being the most commonly used medications. However, there is no consensus regarding their use and benefits in this population. This review summarizes the available literature regarding these medications and aims to provide neonatologists and neonatal providers with evidence-based recommendations.