Decorin is produced by capillary endothelial cells in inflammation-associated angiogenesis

Decorin is a small extracellular chondroitin/dermatan sulfate proteoglycan that has previously been shown to be involved in the angiogenesis-like beha vior of endothelial cells (ECs) in vitro. There is also evidence that decor in plays a role in angiogenesis in vivo. In this study we sought to further explore the involvement of decorin in angiogenesis in vivo, especially in that associated with inflammation. We found by CD31 immunostaining of ECs t hat in giant cell arteritis there are capillary blood vessels not only in t he adventitia as in uninvolved temporal artery wall, but also in the media and the external zone of the thickened intima. Localization of decorin by a ntiserum LF-30 in adjacent sections showed that in normal temporal artery w all decorin resides mainly in the media and the adventitia, whereas in infl amed temporal artery wall decorin is distributed throughout the vessel wall including the intima. Furthermore, the most intense reaction for decorin w as evident in ECs of capillary neovessels within the media and the thickene d intima of inflamed temporal artery wall. Decorin was also found in capill ary ECs in certain pathological and physiological conditions in which the p ivotal role of angiogenesis is more generally accepted. Pyogenic granulomas , granulation tissue of healing dermal wounds, acid ovaries at different ph ases of follicle and corpus luteum formation all contained widely distribut ed CD31-positive capillaries. Decorin, on the other hand, was found in capi llary ECs in pyogenic granulomas and granulation tissue, but not in those i n the ovaries, The assessment of the degree of inflammation in the specimen s with the presence of CD68-positive macrophages showed that the pyogenic g ranuloma, granulation tissue, and giant cell arteritis specimens were rich in macrophages around the decorin-positive capillaries. In contrast, the ov arian specimens were populated with fewer macrophages and even they were no t located in close vicinity of capillaries negative for decorin, Our result s confirm that decorin is involved in angiogenesis in vivo and, particularl y, in conditions in which the inflammatory component is dominant.