IL-27 inhibits lymphatic endothelial cell proliferation by STAT1-regulated gene expression.

Objective: IL-27 belongs to the IL-12 family of cytokines and is recognized for its role in Th cell differentiation and as an inhibitor of tumor angiogenesis. The purpose of this study was to investigate the effect of IL-27 on proliferation of lymphatic endothelial cells to gain insight into the interplay between the immune system and development of the lymphatic system.

Methods: IL-27-stimulated signal transduction in human dermal lymphatic endothelial cells was measured by western blotting and synthesis of CXCL10 and CXCL11 by use of RT-PCR and ELISA.

Inflammation induces lymphangiogenesis through up-regulation of VEGFR-3 mediated by NF-kappaB and Prox1.

The concept of inflammation-induced lymphangiogenesis (ie, formation of new lymphatic vessels) has long been recognized, but the molecular mechanisms remained largely unknown. The 2 primary mediators of lymphangiogenesis are vascular endothelial growth factor receptor-3 (VEGFR-3) and Prox1. The key factors that regulate inflammation-induced transcription are members of the nuclear factor-kappaB (NF-kappaB) family; however, the role of NF-kappaB in regulation of lymphatic-specific genes has not been defined.

Lymphatic endothelial cells: establishment of primaries and characterization of established lines.

This chapter describes detailed methods for the isolation of primary human lymphatic endothelial cells from neonatal foreskin. We also provide protocols and information for their characterization and propagation. Isolation of primary human lymphatic endothelial cells requires a two-step process: mechanical and enzymatic digestion of human foreskins and cell sorting by fluorescence-activated cell sorting of CD31+/podoplanin+/CD45- cells.

IL-20 activates human lymphatic endothelial cells causing cell signalling and tube formation.

IL-20 is an arteriogenic cytokine that remodels collateral networks in vivo, and plays a role in cellular organization. Here, we investigate its role in lymphangiogenesis using a lymphatic endothelial cell line, hTERT-HDLEC, which expresses the lymphatic markers LYVE-1 and podoplanin. Upon stimulation of hTERT-HDLEC with IL-20, we found an increase in the intracellular free calcium concentration, in Akt and eNOS phosphorylations as well as in perinuclear NO production.

Human lymphatic endothelial cells express multiple functional TLRs.

The lymphatic endothelium is the preferred route for the drainage of interstitial fluid from tissues and also serves as a conduit for peripheral dendritic cells (DCs) to reach draining lymph nodes. Lymphatic endothelial cells (LECs) are known to produce chemokines that recruit Ag-loaded DCs to lymphatic vessels and therefore are likely to regulate the migration of DCs to lymph nodes. TLRs are immune receptors that recognize pathogen associated molecular patterns and then signal and stimulate production of inflammatory chemokines and cytokines that contribute to innate and adaptive immune responses.

Dissecting the role of matrix metalloproteinases (MMP) and integrin alpha(v)beta3 in angiogenesis in vitro: absence of hemopexin C domain bioactivity, but membrane-Type 1-MMP and alpha(v)beta3 are critical.

Matrix metalloproteinase (MMP)-2 and its hemopexin C domain autolytic fragment (also called PEX) have been proposed to be crucial for angiogenesis. Here, we have investigated the dependency of in vitro angiogenesis on MMP-mediated extracellular proteolysis and integrin alpha(v)beta3-mediated cell adhesion in a three-dimensional collagen I model. The hydroxamate-based synthetic inhibitors BB94, CT1399, and CT1847 inhibited endothelial cell invasion, as did neutralizing anti-membrane-type 1-MMP (MT1-MMP) antibodies and tissue inhibitor of MMP (TIMP)-2 and TIMP-3 but not TIMP-1.

Generation and characterization of telomerase-transfected human lymphatic endothelial cells with an extended life span.

The study of lymphatic endothelial cells and lymphangiogenesis has, in the past, been hampered by the lack of lymphatic endothelial-specific markers. The recent discovery of several such markers has permitted the isolation of lymphatic endothelial cells (LECs) from human skin. However, cell numbers are limited and purity is variable with the different isolation procedures.

alphav beta 3 and alphav beta 5 integrin antagonists inhibit angiogenesis in vitro.

Although angiogenesis is believed to require cell-extracellular matrix interactions which are mediated in part via integrins alphav beta 3 and alphav beta 5, a formal demonstration that alphav beta 3 and alphav beta 5 are involved in endothelial-cell invasion and capillary-like tube formation is still required. This has arisen from the cellular complexities which occur in vivo and the difficulty in finding appropriate in vitro model systems. Here we have used a three-dimensional assay which employs bovine aortic and microvascular endothelial cells, to show that alphav beta 3 and alphav beta 5 regulate angiogenesis in vitro.

Lymphangiogenesis and tumor metastasis.

In several human cancers, increased expression in primary tumors of vascular endothelial growth factor-C (VEGF-C) is correlated with regional lymph node metastasis. Studies using transgenic mice overexpressing VEGF-C, or xenotransplantation of VEGF-C-expressing tumor cells into immunodeficient mice, have demonstrated a role for VEGF-C in tumor lymphangiogenesis and the subsequent formation of lymph node metastasis. However, at variance with data obtained in animal models, there is at present very little evidence for lymphangiogenesis in human tumors.