Prostacyclin analogs stimulate VEGF production from human lung fibroblasts in culture.
Prostacyclin is a short-lived metabolite of arachidonic acid that is produced by several cells in the lung and prominently by endothelial cells. It increases intracellular cAMP levels activating downstream signaling thus regulating vascular mesenchymal cell functions. The alveolar wall contains a rich capillary network as well as a population of mesenchymal cells, i.e., fibroblasts. The current study evaluated the hypothesis that prostacyclin may mediate signaling between endothelial and mesenchymal cells in the alveolar wall by assessing the ability of prostacyclin analogs to modulate fibroblast release of VEGF. To accomplish this study, human lung fibroblasts were cultured in routine culture on plastic support and in three-dimensional collagen gels with or without three prostacyclin analogs, carbaprostacyclin, iloprost, and beraprost, and the production of VEGF was evaluated by ELISA and quantitative real-time PCR. Iloprost and beraprost significantly stimulated VEGF mRNA levels and protein release in a concentration-dependent manner. These effects were blocked by the adenylate cyclase inhibitor SQ-22536 and by the protein kinase A (PKA) inhibitor KT-5720 and were reproduced by a direct PKA activator but not by an activator of exchange protein directly activated by cAMP (Epac), indicating that cAMP-activated PKA signaling mediated the effect. Since VEGF serves to maintain the pulmonary microvasculature, the current study suggests that prostacyclin is part of a bidirectional signaling network between the mesenchymal and vascular cells of the alveolar wall. Prostacyclin analogs, therefore, have the potential to modulate the maintenance of the pulmonary microcirculation by driving the production of VEGF from lung fibroblasts.
Kamio
Koichiro
K
Division of Pulmonary Medicine, Nippon Medical School, Tokyo, Japan.
Sato
Tadashi
T
Liu
Xiangde
X
Sugiura
Hisatoshi
H
Togo
Shinsaku
S
Kobayashi
Tetsu
T
Kawasaki
Shin
S
Wang
Xingqi
X
Mao
Lijun
L
Ahn
Youngsoo
Y
Holz
Olaf
O
Magnussen
Helgo
H
Rennard
Stephen I
SI
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000502:physiology; D000328:Adult; D002227:Carbazoles / Q000494:pharmacology; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D011464:Epoprostenol / Q000031:analogs & derivatives / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D008168:Lung / Q000166:cytology; D044062:Prostaglandins I / Q000494:pharmacology*; D011758:Pyrroles / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013268:Stimulation, Chemical; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis*
D000067956:Adenylyl Cyclase Inhibitors; D002227:Carbazoles; D044062:Prostaglandins I; D011758:Pyrroles; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C017759:9-(tetrahydro-2-furyl)-adenine; C048081:beraprost; C057416:KT 5720; C026678:carboprostacyclin; D011464:Epoprostenol; D000262:Adenylyl Cyclases; D000225:Adenine; D016285:Iloprost