Antifibrotic role of vascular endothelial growth factor in pulmonary fibrosis
Lynne A. Murray, … , Cory M. Hogaboam, Erica L. Herzog
Lynne A. Murray, … , Cory M. Hogaboam, Erica L. Herzog
Published August 17, 2017
Citation Information: JCI Insight. 2017;2(16):e92192. https://doi.org/10.1172/jci.insight.92192.
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Research Article Inflammation Pulmonology

Antifibrotic role of vascular endothelial growth factor in pulmonary fibrosis

Abstract

The chronic progressive decline in lung function observed in idiopathic pulmonary fibrosis (IPF) appears to result from persistent nonresolving injury to the epithelium, impaired restitution of the epithelial barrier in the lung, and enhanced fibroblast activation. Thus, understanding these key mechanisms and pathways modulating both is essential to greater understanding of IPF pathogenesis. We examined the association of VEGF with the IPF disease state and preclinical models in vivo and in vitro. Tissue and circulating levels of VEGF were significantly reduced in patients with IPF, particularly in those with a rapidly progressive phenotype, compared with healthy controls. Lung-specific overexpression of VEGF significantly protected mice following intratracheal bleomycin challenge, with a decrease in fibrosis and bleomycin-induced cell death observed in the VEGF transgenic mice. In vitro, apoptotic endothelial cell–derived mediators enhanced epithelial cell injury and reduced epithelial wound closure. This process was rescued by VEGF pretreatment of the endothelial cells via a mechanism involving thrombospondin-1 (TSP1). Taken together, these data indicate beneficial roles for VEGF during lung fibrosis via modulating epithelial homeostasis through a previously unrecognized mechanism involving the endothelium.

Authors

Lynne A. Murray, David M. Habiel, Miriam Hohmann, Ana Camelo, Huilan Shang, Yang Zhou, Ana Lucia Coelho, Xueyan Peng, Mridu Gulati, Bruno Crestani, Matthew A. Sleeman, Tomas Mustelin, Meagan W. Moore, Changwan Ryu, Awo D. Osafo-Addo, Jack A. Elias, Chun G. Lee, Buqu Hu, Jose D. Herazo-Maya, Darryl A. Knight, Cory M. Hogaboam, Erica L. Herzog

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Figure 5

Protective effect of VEGF on epithelial cells occurs indirectly through its effect on endothelial cells.

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Protective effect of VEGF on epithelial cells occurs indirectly through ...
(A) Primary lung epithelial cells were assessed by RNA sequencing analysis for VEGF receptor expression (n = 3). (B) Effect of VEGF (0–1,000 ng/ml) on lung epithelial cell (normal human bronchial epithelial cells [NHBE] or A549) caspase 3/7 release after 24 hours of in vitro stimulation. (C) Effect of H2O2 in the presence of absence of VEGF on epithelial wound closure. (D and E) Normal or idiopathic pulmonary fibrosis (IPF) lung fibroblast cultures were stained with fluorescent conjugated anti-SSEA4 (stage-specific embryonic antigen 4) antibodies. SSEA4-negative lung fibroblasts were sorted from SSEA4-positive progenitors; RNA was extracted from the sorted cells and subject to RNA sequencing analysis. The resulting RNA-Seq reads were aligned to the human genome build hg18 and normalized fragments per kilobase of transcript per million mapped reads (FPKM) values pertaining to VEGF and VEGF receptor transcripts were mined. (D) Depicted is the average FPKM values from 3 normal, 2 slow progressing, and 5 rapid progressing IPF lung SSEA4-negative fibroblasts. (E) Representative Western blot of VEGFR1 expression in primary stromal cultures from nonfibrotic lungs (NL) (n = 2) and IPF lungs with rapid and slow progressing disease (n = 3). (F) Schematic showing the generation of HUVEC conditioned media. (G) HUVEC were incubated with or without H202 and different concentrations of VEGF (0–100 ng/ml), to elicit HUVEC-conditioned media. This was then added to NHBE cells, and apoptosis was measured by caspase 3/7 activity after 48 hours of incubation. (H) Relative wound healing percentage on NHBE cells cultured in either their own media or HUVEC-conditioned media (without or with added VEGF). Data is representative of 3 separate experiments. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.005 as stated or HUVEC-conditioned media compared with 100ng/ml condition media; #P ≤ 0.05, ##P ≤ 0.01, ###P ≤ 0.005, ####P ≤ 0.001 HUVEC-condition media compared with control media. All analysis were performed via one-way ANOVA analyses with Bonferroni significance post-testing.