CDH Live Webinar Series Part 1: Research: Lung Compression in CDH Generates Cellular Chronic Hypoxia and Energy Failure

Hi everyone. This is M Thambash, a research fellow at Cincinnati Children's Hospital. In this series, we are summarizing presentations from Congenital Diaphragmatic Hernia live webinar series by Cincinnati Children's Hospital. At our fetal care center, experts in maternal fetal medicine, neonatology, and fetal surgery provide exceptional comprehensive care for mothers and babies experiencing high-risk pregnancies or complex fetal conditions. Cincinnati Children's Hospital and Stay Current share knowledge to improve child health around the globe. Today we are talking about lung compression during lung development in CDH with Dr. Marva Murra Lopez. She finished her neonatology fellowship at Cincinnati Children's in 2021. This project was conceptualized and developed at Cincinnati Children's Hospital. Congenital Diaphragmatic Hernia or CDH is a rare anomaly with a high associated mortality rate. According to the US Centers for Disease Control and Prevention, the incidence is 2.6 per 10,000 births. The pathophysiology of CDH is not well understood, and we don't know why these babies have lung hypoplasia and severe pulmonary hypertension. But we know the diaphragmatic defect caused that the abdominal viscera herniate to the chest and this create lung compression and also cause lung hypoperfusion. We have the fifth questions to answer. Does hypoperfusion decrease the nutrients and oxygen delivery, changing the lung metabolism? Are the changes in the metabolism responsible for the changes that we see in lung development? To test this hypothesis, I use the nitrofen model. At 9 and 1/2 days, rats were giving intragastrically 100 milligrams of nitrofen dissolved in 1 milliliter of olive oil, or only olive oil as vehicle control group. Rats were euthanized before the pops were born on day 21 and a half. All the pups' lungs were harvested in less than 50 minutes to minimize hypoxia. Fetal development occurs in an hypoxic environment. The hypoxia inducible factor or hif is upregulated in hypoxia and is a sensitive contributor for the fetal development. Hif MRNA and protein levels are elevated in the fetal lung with the entire hif system activated at eight weeks of gestation in the human. However, when Hif1 Alpha is exposed to oxygen in normoxia, it has a short half-life which is less than five minutes. We study the Hif1 Alpha gene expression analyzed at QPCR. It is significantly different between the nitrofen CDH and vehicle control. Under decreased concentrations of oxygen, the degradation of hif alpha is retarded. And this can explain why the protein expression of hif that you see in this fluorescence image here in red is increase in the periphery of CDH lungs. Glucose is the primary energy source of the lungs and is essential source for energy production and surfactant synthesis. Hypoxic conditions and energy failure acutely stimulate the glucose transport. Glucose Transporter One or Glut1 increases in the lung tissue under hypoxia. In fetal rats, Glut1 MRNA expression increases to maximum levels of gestation day 20 and it falls to very low levels by postnatal day 8. Here on the top left, we see that the Glut1 gene expression evaluated by QPCR is upregulated on the CDH. On the top right, we see the glucose is not decreased in the lungs with CDH when we evaluated it by NMR spectroscopy. In this image, we compare the hif1 and the glut1. Here, we can see both of them manifest in the airways. This is a higher augmentation. According to the central dogma of molecular biology, metabolomics can be considered to provide a functional readout of the physiological and pathological state of an organism. Our metabolomic investigation published last year of complete fetal lungs indicates the presence of a unique metabolic profile in the Nitrofen induced CDH fetal lungs. They found evident changes in energy production, redox control state and cell proliferation. These changes are associated with lung hypoplasia caused by the nitrofen and aggravated by lung compression. This changes impact normal lung development. ATP is critical to maintain levels of what we know as energy charge. Almost all energy requiring process in the cells are driving by the hydrolysis of ATP. One of the most fundamental parameters that any healthy cell must maintain is a high ratio of ATP to ADP. In order of 10 ATPs for each ADP. Same with the ADP to AMP of the order of a 100 ADPs for each AMP. Adaptation to decrease in oxygen and nutrients required on regulation of metabolic demands and an increase in substrate supply to prevent the bioenergetic collapse. We evaluated the concentrations of ATP, ADP, and AMP. ADP is decreased and AMP is increased. Let's look at the energy charge of the cells. The barriers between 0.7 and 0.95. Oxidations in this range are very frequent and are normal. It is very clear that the CDH lungs are in an energetic failure with a level of 0.15. As a conclusion, fetal CDH lungs are compressed and probably with chronic hypoxia, have a different metabolism with significant alteration in glycolytic energy, antioxidant, and nucleotide metabolites. The fetal CDH lungs are in energetic failure. The metabolic changes found in the fetal CDH are compatible with growth arrest and tissue remodeling. Thank you for watching. I'm Em Thambash, a research fellow from Cincinnati Children's Hospital. If you like this podcast, please don't forget to subscribe to our YouTube channel, follow us on social media, and download the Stay Current app where you can find hundreds of content including podcasts, videos, and infographics. See you in the next episode. Cincinnati Children's Hospital and Stay Current share knowledge to improve child health around the globe.