Background: In the setting of inflammatory bowel disease, inflammation is associated with a simultaneous increase in angiogenesis; moreover, elevated vascular endothelial growth factor (VEGF) levels implicate angiogenesis as a pathologic contributor to disease severity. We hypothesize that selectively inhibiting vascular endothelial growth factor receptor-2 (VEGFR2) in a model of murine colitis will reduce angiogenesis, resulting in decreased inflammation and disease severity, providing mechanistic insight into the role of pathologic angiogenesis in IBD.
Materials and methods: In a dextran sodium sulfate model of murine colitis, anti-VEGFR2 monoclonal antibody (DC101) or placebo was administered. Clinical assessments followed by histologic and molecular tissue analysis were performed to quantify inflammation, microvessel density (MVD), VEGF and VEGFR2 gene expression, and phosphorylated mitogen-activated protein kinase protein expression.
Results: Weight loss began after d 6 with the treatment group demonstrating a more favorable percent weight change. Inflammation and MVD were similar between cohorts, both increasing in parallel toward a plateau. VEGF and VEGFR2 messenger RNA expression were not significantly different, but phosphorylated mitogen-activated protein kinase was elevated in the DC101 cohort (P = 0.03).
Conclusions: Despite a more favorable weight change profile in the treated group, no difference was observed between cohorts regarding clinical disease severity. However, a parallel rise in inflammation and MVD was observed coinciding with weight loss, suggesting their relationship in IBD. VEGFR2 downstream signaling was significantly elevated in the treated cohort, possibly by VEGF-independent signal transduction. Early and effective inhibition of angiogenesis by limiting downstream VEGF signaling or targeting multiple angiogenic pathways may block angiogenesis, thereby reducing disease severity and provide evidence toward the mechanism and clinical benefit of antiangiogenics in the setting of IBD.
Keywords: Angiogenesis; Colitis; Inflammatory bowel disease; VEGFR2.
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