Leflunomide induces NAD(P)H quinone dehydrogenase 1 enzyme via the aryl hydrocarbon receptor in neonatal mice

Ramelteon Ameliorates LPS-Induced Hyperpermeability of the Blood-Brain Barrier (BBB) by Activating Nrf2

The blood-brain barrier (BBB) is important for protecting the brain tissue by selectively exchanging substances between the blood and brain. The integrity of the BBB can be damaged by multiple factors, including oxidative stress and inflammation. Ramelteon is an oral hypnotic drug, and in the present study, we investigated its protective effect on BBB damage, as well as the underlying mechanism. LPS was used to induce BBB damage on mice and stimulate injury on endothelial cells. Evans blue staining assay was used to measure the brain permeability. The expressions of ZO-1 and Occludin were evaluated using immunostaining and Western blot in the brain tissue and endothelial cells, respectively. qRT-PCR and ELISA were used to detect the production of IL-1β and MCP-1 in the brain vessels. TBA assay was utilized to examine the concentration of MDA in the brain tissue and endothelial cells. The expression of Nrf2 in the nucleus and NQO1 were determined using Western blot assay. The endothelial permeability of the monolayer was examined using the FITC-dextran permeation assay. Firstly, the increased brain permeability and downregulated expression of tight junction proteins in the brain tissue induced by LPS were significantly reversed by treatment with Ramelteon, accompanied by the decrease in the production of IL-1β and MCP-1 in the vessels in mice. Also, the Nrf2 signaling was activated and oxidative stress in the brain vessels was alleviated by treatment with Ramelteon. Secondly, LPS-induced increase in endothelial monolayer permeability and decrease in tight junction protein expression in bEnd.3 brain endothelial cells were significantly reversed by Ramelteon, accompanied by activated Nrf2 signaling and alleviated oxidative stress. Lastly, the protective effects of Ramelteon against LPS-induced reduction of ZO-1 and Occludin, and the increase in endothelial monolayer permeability were dramatically abolished by silencing Nrf2. Ramelteon might ameliorate LPS-induced hyperpermeability of the BBB by activating the Nrf2 signaling pathway.

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.

Leflunomide attenuates oxidative stress in fetal human lung endothelial cells via superoxide dismutase 2 and catalase

Hyperoxia-induced oxidative stress contributes to the pathogenesis of bronchopulmonary dysplasia (BPD), the most common respiratory morbidity of preterm infants. Importantly, the disease lack specific therapies and is associated with long-term cardio-pulmonary and neurodevelopmental morbidities, signifying the need to discover novel therapies and decrease the disease burden. We and others have demonstrated that leflunomide, a food and drug administration approved drug to treat humans with rheumatoid arthritis, increases the expression of the anti-oxidant enzymes, NAD(P)H quinone dehydrogenase 1 (NQO1), catalase, and superoxide dismutase (SOD). However, whether this drug can decrease oxidative stress in fetal human pulmonary arterial endothelial cells (HPAECs) is unknown. Therefore, we tested the hypothesis that leflunomide will decrease hyperoxia-induced oxidative stress by upregulating these anti-oxidant enzymes in HPAECs. Leflunomide decreased hydrogen peroxide (H₂O₂) levels and increased the mRNA and protein levels of catalase, NQO1, and SOD2 in HPAECs at basal conditions. Further, leflunomide-treated cells continued to have decreased H₂O₂ and increased SOD2 levels upon hyperoxia exposure. Leflunomide did not affect the expression of other anti-oxidant enzymes, including hemoxygenase-1 and SOD1. AhR-knockdown experiments suggested that leflunomide regulated NQO1 levels via AhR-dependent mechanisms and H₂O₂, catalase, and SOD2 levels via AhR-independent mechanisms. Collectively, the results support the hypothesis that leflunomide decreases oxidative stress in HPAECs via SOD2-and catalase-dependent, but AhR- and NQO1-independent mechanisms. Our findings indicate that leflunomide is a potential drug for the management of BPD in preterm infants.