<b>The selective distribution of LYVE-1-expressing endothelial cells and reticular cells in the reticulo-endothelial system </b><b>(RES) </b>

Abstract

LYVE-1, a receptor molecule for hyaluronan, is expressed in the lymphatic endothelium, blood sinus endothelium, and certain macrophage lineages. The present immunohistochemical study revealed a broader distribution of LYVE-1 in vascular endothelial cells of the murine lung, adrenal gland, and heart as well as the liver and spleen. In addition, sinus reticular cells-including sinuslining cells-in the medulla of the lymph node also intensely expressed LYVE-1. Ultrastructurally, immuno-gold particles for LYVE-1 were localized on the entire length of plasma membrane in all cell types. Most of these LYVE-1-expressing cells had previously been classified as the reticuloendothelial system (RES) specialized for eliminating foreign particles. An LPS stimulation decreased the LYVE-1 expression in macrophages but elevated the expression at mRNA and protein levels in the liver and lung, major organs for the elimination of blood-born waste substances. LYVE-1-expressing endothelial cells in these organs participated in the endocytosis of exogenous particles, and the uptake ability was conspicuously enhanced by the LPS challenge. Although the expression of the degrading enzyme, hyaluronidase, was generally low in the LYVE-1-expressing cells, they were topographically associated with a dense distribution of macrophages possessing hyaluronidase activities in each tissue. These findings suggest that the LYVE-1-expressing cells might be involved in the uptake of hyaluronan and other waste products as well as foreign particles circulating in the blood and lymph while participating in the subsequent degradation in relay with adjacent macrophage populations. LYVE-1 (lymphatic vessel endothelial hyaluronan receptor-1) has been identified as a reliable marker that is expressed predominantly in the lymphatic endothelium (5, 29). Both the chemical structure and function of LYVE-1 resemble those of a well-established hyaluronan receptor, CD44, which has a 41% similarity to LYVE-1 and is characterized as an inflammatory leukocyte homing receptor. CD44 is widely expressed in the epithelium, mesothelium, mesenchymal cells, and cells of hematopoietic origin (22), while LYVE-1 has been shown in early studies to display a restricted distribution to the lymphatic endothelium and be completely absent from blood vessels, except for sinusoidal endothelial cells in the spleen (5). Subsequent studies have also detected the expression of LYVE-1 in sinusoidal endothelial cells using paraffin sections of the liver, spleen and lymph node of humans (1, 26). However, our preliminary immunohistochemical study using frozen sections from rodents found a broader distribution of LYVE-1 in the endothelium of other organs, including the lung, adrenal gland, heart, and adenohypophysis. In addition, the sinus reticular cells in the medulla of the lymph node intensely expressed LYVE-1. Interestingly, most of these belong

High-endothelial cell-derived S1P regulates dendritic cell localization and vascular integrity in the lymph node

“…Lyve1 -expression is not restricted to the lymphatic vasculature and data presented in this study and by other groups show that LYVE1 is expressed on uncommitted embryonic blood vessels (Gordon et al, 2008). Recent findings show that LYVE1 is expressed on a subset of sinusoidal endothelial cells in the spleen of humans and adult rodents (Banerji et al, 1999; Zheng et al, 2016). LYVE1 is also expressed by resident macrophage populations and a subset of infiltrating macrophages found in tumors and inflamed tissues (Jackson, 2004), and splenic stromal organizer cells during ontogeny (Tan and Watanabe, 2017).…”

Prominent Receptors of Liver Sinusoidal Endothelial Cells in Liver Homeostasis and Disease

“…With the use of better antibodies, LYVE-1 expression was also detected in the liver, spleen, and lymph node sinusoidal endothelial cells in humans (Mouta Carreira et al, 2001;Akishima et al, 2004). However, a recent study conducted in rodents has revealed their expression in the non-sinusoidal endothelium of many other organs, such as lungs, heart, and adrenal gland (Zheng et al, 2016). Once regarded as the main receptor responsible for the internalization and transport of HA in the lymph circulation, a study using LYVE-1 KO mice model revealed that it is not crucial for the metabolism of HA in the lymphatic endothelium (Gale et al, 2007).…”

Blood–Brain Barrier, Lymphatic Clearance, and Recovery: Ariadne’s Thread in Labyrinths of Hypotheses

“…He also developed a new technique for the meningeal lymphatic visualization using the intracisternal injection of mercury. Today Mascagni’s models of the meningeal lymphatic vessels are presented in the Josephinum Wax Models Museum in Vienna [48]. However, Mascagni’s discovery of the meningeal lymphatics was forgotten for two centuries because no one could repeat his experiments due to technical problems.…”