Idiopathic pulmonary arterial hypertension was associated with an approximately 3-fold greater endothelial glycolytic rate and significantly higher [18F]FDG PET lung uptake versus controls.
Observational
IPAH endothelial cells exhibit a metabolic shift toward glycolysis for energy production, which can be detected in vivo using FDG-PET imaging.
Idiopathic pulmonary arterial hypertension (IPAH) is pathogenetically related to low levels of the vasodilator nitric oxide (NO). Because NO regulates cellular respiration and mitochondrial biogenesis, we hypothesized that abnormalities of bioenergetics may be present in IPAH. Evaluation of pulmonary artery endothelial cells from IPAH and control lungs in vitro revealed that oxygen consumption of IPAH cells was decreased, especially in state 3 respiration with substrates glutamate-malate or succinate, and this decrease paralleled reduction in Complex IV activity and IPAH cellular NO synthesis. IPAH pulmonary artery endothelial cells had decreased mitochondrial dehydrogenase activity and lowered mitochondrial numbers per cell and mitochondrial DNA content, all of which increased after exposure to NO donors. Although IPAH/pulmonary artery endothelial cells' ATP content was similar to control under normoxia, cellular ATP did not change significantly in IPAH cells under hypoxia, whereas ATP decreased 35% in control cells, identifying a greater dependence on cellular respiration for energy in control cells. Evidence that glucose metabolism was subserving the primary role for energy requirements of IPAH cells was provided by the approximately 3-fold greater glycolytic rate of IPAH cells. Positron emission tomography scan with 18Ffluoro-deoxy-D-glucose performed on IPAH patients and healthy controls revealed significantly higher uptake in IPAH lungs as compared with controls, confirming that the glycolytic rate was increased in vivo. Thus, there are substantial changes in bioenergetics of IPAH endothelial cells, which may have consequences for pulmonary hypertensive responses and potentially in development of novel imaging modalities for diagnosis and evaluation of treatment.
Xu et al. (Tue,) conducted a observational in Idiopathic pulmonary arterial hypertension (IPAH). Idiopathic pulmonary arterial hypertension was associated with an approximately 3-fold greater endothelial glycolytic rate and significantly higher [18F]FDG PET lung uptake versus controls.