The Roles of Vascular Endothelial Growth Factor, Angiostatin, and Endostatin in Nasal Polyp Development

Background and Objectives: Microvascular remodeling and angiogenesis are elements of tissue remodeling characteristic of chronic inflammatory diseases, including nasal polyps (NPs). Angiogenesis reflects the balance between the actions of pro- and anti-angiogenic factors. Many pro-angiogenic factors are known, including vascular endothelial growth factor (VEGF). A number of anti-angiogenic factors (e.g., angiostatin and endostatin) also has been identified. Our objective was to assess the roles of VEGF, angiostatin, and endostatin in NP development.Methods: The expression levels of VEGF, angiostatin, and endostatin were measured in NPs harvested during endoscopic endonasal surgery and compared with those in inferior turbinate mucosa (control) samples acquired from patients with hypertrophic rhinitis without allergy. Western blotting and immunohistochemical staining were used to analyze all samples.Results: The levels of VEGF and angiostatin were significantly higher in the NP subjects than in the controls. Neither the VEGF/angiostatin ratio nor the endostatin level differed significantly between the two groups. However, the VEGF/endostatin ratio was significantly higher in the NP than in the control group. Both the NP and control tissues were diffusely immunoreactive for VEGF, angiostatin, and endostatin.Conclusion: NP-associated hypoxia can elevate angiostatin level; moreover, an imbalance in the VEGF/endostatin ratio can contribute to NP formation.