Expression of Tie-2, angiopoietin-1, angiopoietin-2, ephrinB2 and EphB4 inpyogenic granuloma of human gingiva implicates their roles in inflammatoryangiogenesis

Tie-2, angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), ephrin-B2 and Eph-B4 are all important vascular morphogenesis factors which exhibit their funct ions in angiogenesis and blood vessel remodeling in embryonic stage. Howeve r, their roles in post-natal inflammatory angiogenesis are still unclear. P yogenic granuloma is a benign inflammatory lesion that mostly occurs on the gingiva of females with high levels of steroid hormones. Prominent capilla ry growth in hyperplastic granulation tissue is characteristic histopatholo gically in pyogenic granuloma. The purpose of this study was to detect and compare the expressions of Tie-2, Ang-1, Ang-2, ephrin-B2 and Eph-B4 among pyogenic granuloma on human gingiva, gingiva diagnosed with periodontitis a nd healthy gingiva by immunohistochemistry. The immunostaining revealed tha t all of the endothelial cells and some mesenchymal cells expressed Tie-2. The cells which expressed Ang-1 and Ang-2 were mainly macrophage- or monocy te-like mesenchymal cells and smooth muscle cells surrounding blood vessels . The expression of ephrin-B2 and Eph-B4 was not exclusively limited to the endothelial cells of arteries and veins, respectively, as in mice embryo. Eph-BI was expressed in the endothelial cells of newly budding capillaries and venules while ephrin-B2 was expressed in macrophage-like mesenchymal ce lls. Some of the ephrin-B2 positive cells were in direct contact with endot helial cells. The statistical analysis demonstrated that all of the five fa ctors were upregulated in pyogenic granuloma compared to healthy gingiva. I n conclusion, the 5 polypeptides mentioned above may play important roles i n the process of adult inflammatory neovascularization, especially in pyoge nic granuloma. It is highly plausible that most of the new capillaries in i nflammatory angiogenesis originated from venules instead of arterioles.