Impact of IL-33 on PGD2 Generation by Activated Human Cord Blood-Derived Mast Cell: Lack of Effect on Tryptase Release

Mast cells are important not only in allergic reactions, but also in inflammation and are involved in a variety of responses including the immediate release of potent inflammatory mediators after activation by cross-linking of FcεRI molecules. Prostaglandin D2 (PGD2) is a major cyclooxygenase metabolite of arachidonic acid produced by mast cells and it is released following allergen challenge in allergic diseases. IL-33 is an iflammatory cytokine which is critically involved in the regulation of in vitro and in vivo cyclooxygenase production, providing a potential therapeutic target for inflammatory disorders. In this study, using human derived umbelical cord blood mast cells, we show that IL-33 (50 ng/ml), and calcium ionophore A 23187 (0.5 μg/ml), compound 48/80 (10−5 M) or anti-IgE (10 μg/ml), enhaced the production of PGD2 and this effect was inhibited by indomethacin. However, IL-33 was unable to induce tryptase release in these cells. These effects confirm the inflammatory property of IL-33 by stimulating PGD2 but not tryptase in human mast cells. The inhibitory effect of this new cytokine may have a potential therapeutic response in allergic and inflammatory diseases.

Endothelial cells, cholesterol, cytokines, and aging

It has been reported that high levels of cholesterol and triglycerides are associated with increased risk of developing atherosclerosis and shorter life. In fact, vascular endothelial dysfunction occurs during the human aging process. Accumulation of lipids in vascular endothelium activates leukocytes to produce cytokines and chemokines which recruit macrophages. On the other hand, macrophages augment inflammatory response and secrete vascular endothelial growth factor, a key cytokine that mediates angiogenesis and inflammatory response. In addition, hyperlipidaemia is one of the main risk factors for aging, hypertension and diabetes. Here, we review the interrelationship between endothelial cells, high level of cholesterol, and aging.