Leukemia inhibitory factor regulates microvessel density by modulating oxygen-dependent VEGF expression in mice
Yoshiaki Kubota, … , Colin L. Stewart, Toshio Suda
Yoshiaki Kubota, … , Colin L. Stewart, Toshio Suda
Published June 2, 2008
Citation Information: J Clin Invest. 2008;118(7):2393-2403. https://doi.org/10.1172/JCI34882.
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Research Article Vascular biology

Leukemia inhibitory factor regulates microvessel density by modulating oxygen-dependent VEGF expression in mice

Abstract

To meet tissue requirements for oxygen, capillaries must be properly distributed without excess or shortage. In this process, tissue oxygen concentration is well known to determine capillary density via the hypoxia-induced cascade, in which HIFs and VEGF play key roles. However, some additional mechanisms modulating this cascade are suggested to be involved in precise capillary network formation. Here, we showed that leukemia inhibitory factor (LIF) was predominantly expressed in developing endothelium, while its receptor was expressed in surrounding cells such as retinal astrocytes. The retinas of Lif–/– mice displayed increased microvessel density accompanied by sustained tip cell activity, due to increased VEGF expression by astrocytes in the vascularized area. Lif–/– mice resisted hyperoxygen insult in the oxygen-induced retinopathy model, whereas they paradoxically had increased numbers of neovascular tufts. In an in vitro study, LIF inhibited hypoxia-induced VEGF expression and proliferation in cultured astrocytes. Lif–/– mice also exhibited similarly increased microvessel density and upregulated VEGF in various tissues outside the retina. Together, these findings suggest that tissues and advancing vasculature communicate to ensure adequate vascularization using LIF as well as oxygen, which suggests a new strategy for antiangiogenic therapy in human diseases such as diabetic retinopathy and cancer.

Authors

Yoshiaki Kubota, Masanori Hirashima, Kazuo Kishi, Colin L. Stewart, Toshio Suda

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Figure 7

LIF deficiency causes resistance against hyperoxic insult and increased extraretinal neovascularization in the OIR model.

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LIF deficiency causes resistance against hyperoxic insult and increased ...
(A–F) Double IHC of PECAM-1 (green in A and C; white in E and F) and GFAP (red in B and D) in P12 retinas after 3 days of hyperoxygen insult. Note the obliterated vein typically observed in Lif+/+ mice (open arrowheads), which was preserved in Lif–/– mice. Also note the entirely decreased area of vaso-obliteration (yellow outlines in E and F) in Lif–/– mice. (G–J) ISH for VEGF combined with isolectin staining in P12 retinas in the OIR model. Note the increased VEGF-expressing cells in Lif–/– mice were detected in the area resistant against hyperoxygen insult (above dotted lines). (K) Quantification of the vaso-obliterated area. Data represent quantification of the entire retina (n = 6). (L) Quantitative RT-PCR of vegfa for RNA isolated from P12 retina in the OIR model (n = 5). (M–P) Double IHC of PECAM-1 and GFAP in P17 retinas in the OIR model. (Q and R) Higher-magnification images of the boxed regions in M and O, respectively. (S and T) Three-dimensional confocal images of IHC for PECAM-1 in the NVT area. (U and V) Bright-field images of P17 retinas of Lif+/+ and Lif–/– mice in the OIR model. Note the severe bleeding in the NVT area of Lif–/– retina. (W) Quantification of the NVT area. Data represent quantification of the entire retina (n = 7). (X) Quantitative RT-PCR of vegfa for RNA isolated from P17 retina in the OIR model (n = 5). (Y) Western blotting of VEGF proteins from P17 retina in the OIR model. Numbers indicate VEGF120, VEGF164, and VEGF188 isoforms, respectively. a, artery; v, vein. Scale bars: 50 μm. *P < 0.03, **P < 0.01 versus Lif+/+.