BDNF secretion by human pulmonary artery endothelial cells in response to hypoxia.
Within human pulmonary artery, neurotrophin growth factors [NTs; e.g. brain-derived neurotrophic factor (BDNF)] and their high-affinity receptors (tropomyosin-related kinase; Trk) and low-affinity receptors p75 neurotrophin receptor (p75NTR) have been reported, but their functional role is incompletely understood. We tested the hypothesis that BDNF is produced by human pulmonary artery endothelial cells (PAECs). In the context of hypoxia as a risk factor for pulmonary hypertension, we examined the effect of hypoxia on BDNF secretion and consequent autocrine effects on pulmonary endothelium. Initial ELISA analysis of circulating BDNF in 30 healthy human volunteers showed that 72 h exposure to high altitude (~11,000 ft, alveolar PO2 = 100 mmHg) results in higher BDNF compared to samples taken at sea level. Separately, in human PAECs exposed for 24h to normoxia vs. hypoxia (1-3% O2), ELISA of extracellular media showed increased BDNF levels. Furthermore, quantitative PCR of PAECs showed 3-fold enhancement of BDNF gene transcription with hypoxia. In PAECs, BDNF induced NO production (measured using an NO-sensitive fluorescent dye DAF2-DA) that was significantly higher under hypoxic conditions, an effect also noted with the TrkB agonist 7,8-DHF. Importantly, hypoxia-induced NO was blunted by neutralization of secreted BDNF using the chimeric TrkB-Fc. Both hypoxia and BDNF increased iNOS (but not eNOS) mRNA expression. In accordance, BDNF enhancement of NO in hypoxia was not blunted by 50 nM L-NAME (eNOS inhibition) but substantially lower with 100 μM L-NAME (eNOS and iNOS inhibition). Hypoxia and BDNF also induced expression of hypoxia inducible factor 1 alpha (HIF-1α), a subunit of the transcription factor HIF-1, and pharmacological inhibition of HIF-1 diminished hypoxia effects on BDNF expression and secretion, and NO production. These results indicate that human PAECs express and secrete BDNF in response to hypoxia via a HIF-1-regulated pathway.
Department of Anesthesiology, Mayo Clinic, Rochester.|ICRC, International Clinical Research Center, Brno, Czech Republic.|Department of Anesthesiology and Intensive Care, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Martin
M
Helan
Department of Anesthesiology, Mayo Clinic, Rochester.
Bharathi
B
Aravamudan
Department of Anesthesiology, Mayo Clinic, Rochester.|Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester.
William R
WR
Hartman
Department of Anesthesiology, Mayo Clinic, Rochester.
Michael A
MA
Thompson
Cardiovascular diseases, Mayo Clinic, Rochester.
Bruce D
BD
Johnson
Department of Anesthesiology, Mayo Clinic, Rochester.|Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester.
Christina M
CM
Pabelick
Department of Anesthesiology, Mayo Clinic, Rochester.|Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester.
Y S
YS
Prakash
D001119:Arginase / Q000378:metabolism; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000473:pathology; D015870:Gene Expression; D006801:Humans; D000860:Hypoxia / Q000097:blood; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D008562:Membrane Glycoproteins; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases; D011651:Pulmonary Artery / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020813:Receptor, trkB; D015398:Signal Transduction
D019208:Brain-Derived Neurotrophic Factor; D051793:Hypoxia-Inducible Factor 1; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D009569:Nitric Oxide; C579455:BDNF protein, human; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D020813:Receptor, trkB; C000591259:tropomyosin-related kinase-B, human; C574619:ARG1 protein, human; C477631:ARG2 protein, human; D001119:Arginase
Hypoxia inducible factor 1; Neurotrophin; Nitric oxide; Tropomyosin related kinase; eNOS; iNOS