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Am. J. Respir. Crit. Care Med. · Mar 2012
Comparative StudyLung ¹⁸F-fluorodeoxyglucose positron emission tomography for diagnosis and monitoring of pulmonary arterial hypertension.
- Glenn Marsboom, Christian Wietholt, Chad R Haney, Peter T Toth, John J Ryan, Erik Morrow, Thenappan Thenappan, Peter Bache-Wiig, Lin Piao, Jonathan Paul, Chin-Tu Chen, and Stephen L Archer.
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
- Am. J. Respir. Crit. Care Med.. 2012 Mar 15;185(6):670-9.
RationalePulmonary arterial hypertension (PAH) is a proliferative arteriopathy associated with glucose transporter-1 (Glut1) up-regulation and a glycolytic shift in lung metabolism. Glycolytic metabolism can be detected with the positron emission tomography (PET) tracer (18)F-fluorodeoxyglucose (FDG).ObjectivesThe precise cell type in which glycolytic abnormalities occur in PAH is unknown. Moreover, whether FDG-PET is sufficiently sensitive to monitor PAH progression and detect therapeutic regression is untested. We hypothesized that increased lung FDG-PET reflects enhanced glycolysis in vascular cells and is reversible in response to effective therapies.MethodsPAH was induced in Sprague-Dawley rats by monocrotaline or chronic hypoxia (10% oxygen) in combination with Sugen 5416. Monocrotaline rats were treated with oral dichloroacetate or daily imatinib injections. FDG-PET scans and pulmonary artery acceleration times were obtained weekly. The origin of the PET signal was assessed by laser capture microdissection of airway versus vascular tissue. Metabolism was measured in pulmonary artery smooth muscle cell (PASMC) cultures, using a Seahorse extracellular flux analyzer.Measurements And Main ResultsLung FDG increases 1-2 weeks after monocrotaline (when PAH is mild) and is normalized by dichloroacetate and imatinib, which both also regress medial hypertrophy. Glut1 mRNA is up-regulated in both endothelium and PASMCs, but not airway cells or macrophages. PASMCs from monocrotaline rats are hyperproliferative and display normoxic activation of hypoxia-inducible factor-1α (HIF-1α), which underlies their glycolytic phenotype.ConclusionsHIF-1α-mediated Glut1 up-regulation in proliferating vascular cells in PAH accounts for increased lung FDG-PET uptake. FDG-PET is sensitive to mild PAH and can monitor therapeutic changes in the vasculature.
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