Azithromycin Attenuates Fibroblast Growth Factors Induced Vascular Endothelial Growth Factor Via p38^MAPK Signaling in Human Airway Smooth Muscle Cells

Abstract

The airways in asthma and COPD are characterized by an increase in airway smooth muscle (ASM) mass and bronchial vascular changes associated with increased expression of pro-angiogenic growth factors, such as fibroblast growth factors (FGF-1 and FGF-2) and vascular endothelial growth factor (VEGF). We investigated the contribution of FGF-1/-2 in VEGF production in ASM cells and assessed the influence of azithromycin and dexamethasone and their underlying signaling mechanisms. Growth-synchronized human ASM cells were pre-treated with MAPK inhibitors, U0126 for ERK1/2(MAPK) and SB239063 for p38(MAPK) as well as with dexamethasone or azithromycin, 30 min before incubation with FGF-1 or FGF-2. Expression of VEGF (VEGF-A, VEGF(121), and VEGF(165)) was assessed by quantitative PCR, VEGF release by ELISA and MAPK phosphorylation by Western blotting. Both FGF-1 and FGF-2 significantly induced mRNA levels of VEGF-A, VEGF(121), and VEGF(165). The VEGF protein release was increased 1.8-fold (FGF-1) and 5.5-fold (FGF-2) as compared to controls. Rapid transient increase in ERK1/2(MAPK) and p38(MAPK) phosphorylation and subsequent release of VEGF from FGF-1 or FGF-2-treated ASM cells were inhibited by respective blockers. Furthermore, azithromycin and dexamethasone significantly reduced both the VEGF release and the activation of p38(MAPK) pathway in response to FGF-1 or FGF-2 treatment. Our Results demonstrate that FGF-1 and FGF-2 up-regulate VEGF production via ERK1/2(MAPK) and p38(MAPK) pathways. Both azithromycin and dexamethasone elicited their anti-angiogenic effects via p38(MAPK) pathway in vitro, thereby suggesting a possible therapeutic approach to tackle VEGF-mediated vascular remodeling.