Interleukin-33 induces angiogenesis and vascular permeability through ST2/TRAF6-mediated endothelial nitric oxide production

Abstract

IntroductionAngiogenesis is a critical process in physiologic and pathologic conditions, including embryo development, wound healing, tumor progression, and inflammatory diseases. 1 Inflammation and angiogenesis are closely associated, and pathologic angiogenesis has been implicated in the development of chronic inflammatory diseases. Interplay between inflammation and angiogenesis is mediated largely by cytokines, chemokines, and growth factors. Some of these molecules, including vascular endothelial growth factor (VEGF), induce endothelial permeability, allowing the infiltration of leukocytes to inflammatory sites, resulting in tissue damage. 2 Interleukin-33 (IL-33) is a newly identified cytokine of the IL-1 family, which also includes the inflammatory cytokines IL-1␣, It has been shown to signal via ST2 receptor. 4 IL-33 expression is broadly detected in various tissues, including stomach, lung, spinal cord, brain, and skin, as well as in cells, including smooth muscle cells and epithelial cells lining bronchus and small airways. 4 Notably, IL-33 expression is induced by IL-1␤ and tumor necrosis factor-␣ (TNF-␣) in lung and dermal fibroblast and, to a lesser extent, by macrophage activation. 4 IL-33 treatment has been shown to induce T-helper (Th) type 2 responses in mice as indicated by an increase in Th2 cytokine production and serum immunoglobulin. Systemic treatment of mice with IL-33 results in pathologic changes in the lung and the digestive tract. In the lung, vascular changes accompanied with eosinophilic and mononuclear infiltrates were observed in small muscular arteries. 4 Recently, functions of IL-33 in cardiovascular diseases have been reported. For example, IL-33 can reduce the development of atherosclerosis in apolipoprotein E Ϫ/Ϫ mice on a high-fat diet. 5 Furthermore, IL-33/ST2 complexes also have been shown to activate cardioprotective signaling pathways. 6 IL-33 is produced as a 30-kDa precursor protein that is cleaved in vitro by caspase-1, releasing the mature 18-kDa form. 4 Upon binding to the ST2 receptor, IL-33 promotes the activation of nuclear factor (NF)-B and mitogen-activated protein kinase (MAPK), leading to increased transcription of Th2 cytokines. 4 The ST2 receptor, a member of IL-1 receptor family, has long been known as an orphan receptor. Despite its structural and functional similarity to IL-1 receptor family, the ST2 receptor does not bind to IL-1␣ or IL-1␤ or other members of the IL-1 family. Two isoforms, a soluble (sST2) and a membrane bound form (ST2L), are produced through differential mRNA processing. 7,8 ST2L is expressed mainly in mast cells and Th2 cells. 7,8 Both ST2 forms also are expressed in freshly isolated human umbilical vein endothelial cells (HUVECs), and they are up-regulated by proinflammatory stimuli such as TNF, IL-1␣, and IL-1␤. 9 Nitric oxide (NO) production in endothelial cells (ECs) is transiently regulated by multiple inflammatory angiogenic factors such as VEGF and angiopoietin-1. 10,11 NO, in turn, modulates the angiogenic function of these ...

Dynamics of the IL-33/ST2 network in the progression of human colorectal adenoma to sporadic colorectal cancer

“…It has been revealed that IL-33 can stimulate angiogenesis and cell growth via its receptor ST2 expressed in the effecting cells (20,46). In this study we have observed that ST2 was expressed in both the adenomatous/cancerous epithelium and microvessels, whether IL- LGD: Lower grade dysplasia.…”

Myocardial pressure overload induces systemic inflammation through endothelial cell IL-33

“…In contrast, sST2 appears to act as a decoy receptor for IL-33, blocking myocardial and vascular benefits (10)(11)(12). IL-33 is also expressed in endothelial cells (ECs) (13)(14)(15)(16), in which it induces angiogenesis (17), expression of adhesion molecules, and inflammatory activation (18). Here we report the surprising finding that endothelial IL-33 from pressure overload induces a selective systemic response, potentially linking hypertension with circulating factors that can affect the vasculature and other organs.…”

“…IL-33 is expressed in quiescent ECs, and IL-33 protein can be secreted in living cells after mechanical stress (9,(13)(14)(15)(16)(17). We therefore hypothesized that endothelial-derived IL-33 could represent a mechanism by which pressure overload of the myocardium can promote systemic inflammation, and thus we developed mice with conditional deletion of IL33.…”

Serum IL-33 as a Diagnostic and Prognostic Marker in Non-small Cell Lung Cancer

“…Recent data suggest that IL-33 promotes angiogenesis and endothelial permeability involved in tumorigenesis (Choi et al, 2009). Expression of IL-33 has been observed in various organs including stomach and lung, as well as in cells including pancreatic cancer cells and activated macrophages (Carriere et al, 2007).…”