Prostaglandin E₂Stimulates the Production of Vascular Endothelial Growth Factor through the E-Prostanoid–2 Receptor in Cultured Human Lung Fibroblasts

Abstract

Fibroblasts are the major mesenchymal cells present within the interstitium of the lung and are a major source of vascular endothelial growth factor (VEGF), which modulates the maintenance of pulmonary microvasculature. Prostaglandin E 2 (PGE 2 ) acts on a set of E-prostanoid (EP) receptors that activate multiple signal transduction pathways leading to downstream responses. We investigated the modulation by PGE 2 of VEGF release by human lung fibroblasts. Human lung fibroblasts were cultured until reaching 90% confluence in tissue culture plates, after which the culture media were changed to serum-free Dulbecco's modified Eagle's medium, with or without PGE 2 , and with specific agonists or antagonists for each EP receptor. After 2 days, culture media were assayed for VEGF by ELISA. The results demonstrated that PGE 2 and the EP2 agonist ONO-AE1-259-01 significantly stimulated the release of VEGF in a concentration-dependent manner. Agonists for other EP receptors did not stimulate the release of VEGF. The stimulatory effect of PGE 2 was blocked by the EP2 antagonist AH6809, but was not blocked by antagonists for other EP receptors. The protein kinase-A (PKA) inhibitor KT-5720 also blocked the stimulatory effect of PGE 2 . The increased release of VEGF induced by PGE 2 was accompanied by a transient increase in the concentration of VEGF mRNA. These findings demonstrate that PGE 2 can modulate the release of VEGF by human lung fibroblasts through its actions in the EP2 receptor/ PKA pathway. This activity may contribute to the maintenance of pulmonary microvasculature in the alveolar wall.

Prostaglandin E2 possesses different potencies in inducing Vascular Endothelial Growth Factor and Interleukin-8 production in COPD human lung fibroblasts

“…Pulmonary fibroblasts confer structural support to the lung connective tissue and play a role in stimulating and amplifying inflammatory signals through the expression of COX-2 and of microsomal prostaglandin E2 synthase in response to cigarette smoke [1]. Cigarette smoke, the major risk factor of COPD, also promotes the induction of COX-2 and PGE 2 receptor expression in neutrophils and alveolar macrophages (AM), therefore contributing to the proinflammatory effects of PGE 2 in the airways of COPD subjects [24,26]; indeed a significant overlap with minor, but statistically significant, differences was observed between HS and COPD subjects in terms of COX-2 and PGE 2 , but clearcut increases, in agreement with previously published data [27], were observed in COPD subjects only for EP2 and EP4 expressions, both as mRNA and protein, suggesting that the increase in PGE 2 -dependent IL-8 formation may be the result of concomitant higher PGE2 concentration and enhanced receptor expression when compared to C., Fibroblasts are the major mesenchymal cells present within the interstitium of the lung and have been shown to be a major source of VEGF [4]. VEGF in the lung is required to maintain endothelial cell survival of pulmonary capillaries and therefore a normal alveolar wall [28], but VEGF is also an extremely potent pro-angiogenic factor, 13 and relatively small changes in its concentrations may promote pathological blood vessel expansion.…”

“…Previously published evidence showed the increased expression of EP2 and EP4 receptors in COPD [27], as well as the ability of cigarette smoke to induce VEGF release from fibroblasts [31] or the positive correlation between PGE 2 and VEGF [4], but with the present work we provide evidence that different levels of PGE 2 production, as a result of COX-2 expression, can differentiate between the homeostatic pro-angiogenic or the proinflammatory role of this prostanoid, underlining its critical role in normal physiology as well as in COPD pathophysiology.…”

“…PGE 2 has the potential to function as both an autocrine and a paracrine mediator in fibroblasts, affecting chemotactic recruitment [2][3], proliferation [4], matrix production [5,6], and matrix remodeling [7,8]. PGE 2 acts on four distinct G proteincoupled E-prostanoid (EP) receptors named EP1, EP2, EP3, and EP4, [9,10], and coupled to different transduction mechanisms such as the increase in intracellular cyclic adenosine monophosphate (cAMP, EP2 and EP4), the decrease in cAMP (EP3), and the increase in intracellular calcium (EP1) [11] [12].…”

“…Prostacyclin analogues stimulate the production of VEGF by human lung fibroblasts, an effect mediated by the I-prostanoid receptor acting through the cAMP/protein kinase-A (PKA) pathway [16]. Similarly, it has recently been observed that PGE 2 stimulates the production of VEGF through the activation of the Gs-coupled EP2 receptor in cultured human lung fibroblasts [4]. Furthermore, PGs are known to increase IL-8 release by fibroblasts [17], playing also a potentially important role in COPD airway chronic inflammation [18].…”

G-Protein–Coupled Receptor 91 and Succinate Are Key Contributors in Neonatal Postcerebral Hypoxia-Ischemia Recovery

“…In neurons and astrocytes, succinate also stimulated PGE 2 formation, which resulted in a dose-dependent induction of VEGF mRNA. 60 In addition, succinate-induced VEGF mRNA expression was markedly diminished by prostaglandin synthase inhibitor indomethacin and by the selective EP 4 antagonist L-161982 but not by the nonspecific EP 1,2,3 nonspecific antagonist AH6809. Our findings are consistent with a robust expression of EP 4 in neurons and in endothelial cells after cerebral ischemia, suggesting a protective sensory cellular mechanism.…”