Influence of reactive oxygen species on secretory component in the intestinal epithelium during hyperoxia

Oxygen in the neonatal ICU: a complicated history and where are we now?

Despite major advances in neonatal care, oxygen remains the most commonly used medication in the neonatal intensive care unit (NICU). Supplemental oxygen can be life-saving for term and preterm neonates in the resuscitation period and beyond, however use of oxygen in the neonatal period must be judicious as there can be toxic effects. Newborns experience substantial hemodynamic changes at birth, rapid energy consumption, and decreased antioxidant capacity, which requires a delicate balance of sufficient oxygen while mitigating reactive oxygen species causing oxidative stress. In this review, we will discuss the physiology of neonates in relation to hypoxia and hyperoxic injury, the history of supplemental oxygen in the delivery room and beyond, supporting clinical research guiding trends for oxygen therapy in neonatal care, current practices, and future directions.

Lactobacillus plantarum L168 improves hyperoxia-induced pulmonary inflammation and hypoalveolarization in a rat model of bronchopulmonary dysplasia

Alteration of gut microbiota can affect chronic lung diseases, such as asthma and chronic obstructive pulmonary disease, through abnormal immune and inflammatory responses. Previous studies have shown a feasible connection between gut microbiota and bronchopulmonary dysplasia (BPD) in preterm infants. However, whether BPD can be ameliorated by restoring the gut microbiota remains unclear. In preterm infants with BPD, we found variance in the diversity and structure of gut microbiota. Similarly, BPD rats showed gut dysbiosis, characterized by a deficiency of Lactobacillus, which was abundant in normal rats. We therefore explored the effect and potential mechanism of action of a probiotic strain, Lactobacillus plantarum L168, in improving BPD. The BPD rats were treated with L. plantarum L168 by gavage for 2 weeks, and the effect was evaluated by lung histopathology, lung function, and serum inflammatory markers. Subsequently, we observed reduced lung injury and improved lung development in BPD rats exposed to L. plantarum L168. Further evaluation revealed that L. plantarum L168 improved intestinal permeability in BPD rats. Serum metabolomics showed altered inflammation-associated metabolites following L. plantarum L168 intervention, notably a marked increase in anti-inflammatory metabolites. In agreement with the metabolites analysis, RNA-seq analysis of the intestine and lung showed that inflammation and immune-related genes were down-regulated. Based on the information from RNA-seq, we validated that L. plantarum L168 might improve BPD relating to down-regulation of TLR4 /NF-κB /CCL4 pathway. Together, our findings suggest the potential of L. plantarum L168 to provide probiotic-based therapeutic strategies for BPD.

H2O2/DEM-Promoted Maft Promoter Demethylation Drives Nrf2/ARE Activation in Zebrafish

The Nrf2/ARE signaling pathway is a cell survival response pathway in response to environmental stresses. The Nrf2/ARE signaling pathway can be activated by stimulating cysteine residues at different positions in the Keap1. However, the epigenetic mechanisms of the Nrf2/ARE pathway under different stimuli are still poorly understood. In this study, we found that both hydrogen peroxide (H₂O₂) and Diethyl Maleate (DEM) activated the Nrf2/ARE signaling pathway at 120 hpf in zebrafish. H₂O₂ regulated the demethylation of the maft promoter by inhibiting the expression of methyltransferase. This promotes the mRNA expression of the Nrf2 binding factor maft, thereby promoting the downstream antioxidant genes. The methylation of the Nrf2/ARE signaling pathway was not significantly regulated by DEM. However, under oxidative stress, the methyltransferase inhibitors (decitabine and azacitidine) demethylated the promoter region of maft. It activated the expression of the maft, further improving the Nrf2/ARE signal pathway. At last, antioxidant target genes were activated. It was shown that H₂O₂ and DEM cooperated with methyltransferase inhibitors, providing an important reference for the treatment of oxidative stress-related diseases and breaking new ground for the study of the mechanism of methyltransferase inhibitors in the process of tumor chemotherapy.

Mechanism of Neonatal Intestinal Injury Induced by Hyperoxia Therapy

High concentration oxygen is widely used in the treatment of neonates, which has a significant effect on improving blood oxygen concentration in neonates with respiratory distress. The adverse effects of hyperoxia therapy on the lung, retina, and neurodevelopment of newborns have been extensively studied, but less attention has been paid to intestinal damage caused by hyperoxia therapy. In this review, we focus on the physical, immune, and microorganism barriers of the intestinal tract and discuss neonatal intestinal tract damage caused by hyperoxia therapy and analyze the molecular mechanism of intestinal damage caused by hyperoxia in combination with necrotizing enterocolitis.