scholarly journals Leukocyte Trafficking via Lymphatic Vessels in Atherosclerosis

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1344
Author(s):  
Kim Pin Yeo ◽  
Hwee Ying Lim ◽  
Veronique Angeli

In recent years, lymphatic vessels have received increasing attention and our understanding of their development and functional roles in health and diseases has greatly improved. It has become clear that lymphatic vessels are critically involved in acute and chronic inflammation and its resolution by supporting the transport of immune cells, fluid, and macromolecules. As we will discuss in this review, the involvement of lymphatic vessels has been uncovered in atherosclerosis, a chronic inflammatory disease of medium- and large-sized arteries causing deadly cardiovascular complications worldwide. The progression of atherosclerosis is associated with morphological and functional alterations in lymphatic vessels draining the diseased artery. These defects in the lymphatic vasculature impact the inflammatory response in atherosclerosis by affecting immune cell trafficking, lymphoid neogenesis, and clearance of macromolecules in the arterial wall. Based on these new findings, we propose that targeting lymphatic function could be considered in conjunction with existing drugs as a treatment option for atherosclerosis.

Author(s):  
Michael Weiler ◽  
J. Brandon Dixon

The lymphatic vasculature is present in nearly every tissue of the body to serve essential functions in fluid homeostasis, immune cell trafficking, and lipid transport, and it has been implicated in the progression of several diseases. Despite the critical roles that this system performs, very little is known about the lymphatic vasculature in comparison to the blood vasculature, which can be attributed, in part, to the difficulty associated with imaging lymphatic vessels. With the growing interest in studying lymphatics, near-infrared (NIR) imaging has emerged in the literature as a novel lymphatic imaging modality to simultaneously improve spatial resolution to visualize small initial lymphatics and increase temporal resolution to capture the dynamic lymphatic pump function responsible for fluid propulsion.


PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0249256
Author(s):  
Esther Redder ◽  
Nils Kirschnick ◽  
Stefanie Bobe ◽  
René Hägerling ◽  
Nils Rouven Hansmeier ◽  
...  

Lymphatic vessels are indispensable for tissue fluid homeostasis, transport of solutes and dietary lipids and immune cell trafficking. In contrast to blood vessels, which are easily visible by their erythrocyte cargo, lymphatic vessels are not readily detected in the tissue context. Their invisibility interferes with the analysis of the three-dimensional lymph vessel structure in large tissue volumes and hampers dynamic intravital studies on lymphatic function and pathofunction. An approach to overcome these limitations are mouse models, which express transgenic fluorescent proteins under the control of tissue-specific promotor elements. We introduce here the BAC-transgenic mouse reporter strain Vegfr3-tdTomato that expresses a membrane-tagged version of tdTomato under control of Flt4 regulatory elements. Vegfr3-tdTomato mice inherited the reporter in a mendelian fashion and showed selective and stable fluorescence in the lymphatic vessels of multiple organs tested, including lung, kidney, heart, diaphragm, intestine, mesentery, liver and dermis. In this model, tdTomato expression was sufficient for direct visualisation of lymphatic vessels by epifluorescence microscopy. Furthermore, lymph vessels were readily visualized using a number of microscopic modalities including confocal laser scanning, light sheet fluorescence and two-photon microscopy. Due to the early onset of VEGFR-3 expression in venous embryonic vessels and the short maturation time of tdTomato, this reporter offers an interesting alternative to Prox1-promoter driven lymphatic reporter mice for instance to study the developmental differentiation of venous to lymphatic endothelial cells.


2017 ◽  
Vol 313 (3) ◽  
pp. E303-E313 ◽  
Author(s):  
Rachel J. Roth Flach ◽  
Marina T. DiStefano ◽  
Laura V. Danai ◽  
Ozlem Senol-Cosar ◽  
Joseph C. Yawe ◽  
...  

The blood vasculature responds to insulin, influencing hemodynamic changes in the periphery, which promotes tissue nutrient and oxygen delivery and thus metabolic function. The lymphatic vasculature regulates fluid and lipid homeostasis, and impaired lymphatic function can contribute to atherosclerosis and obesity. Recent studies have suggested a role for endothelial cell (EC) mitogen-activated protein kinase kinase kinase kinase 4 (Map4k4) in developmental angiogenesis and lymphangiogenesis as well as atherosclerosis. Here, we show that inducible EC Map4k4 deletion in adult mice ameliorates metabolic dysfunction in obesity despite the development of chylous ascites and a concomitant striking increase in adipose tissue lymphocyte content. Despite these defects, animals lacking endothelial Map4k4 were protected from skeletal muscle microvascular rarefaction in obesity, and primary ECs lacking Map4k4 displayed reduced senescence and increased metabolic capacity. Thus endothelial Map4k4 has complex and opposing functions in the blood and lymphatic endothelium postdevelopment. Whereas blood endothelial Map4k4 promotes vascular dysfunction and impairs glucose homeostasis in adult animals, lymphatic endothelial Map4k4 is required to maintain lymphatic vascular integrity and regulate immune cell trafficking in obesity.


Author(s):  
J. Brandon Dixon ◽  
Ryan Akin ◽  
Mike Weiler ◽  
Timothy Kassis

The lymphatic vasculature consists of a network of vessels that promote unidirectional transport of fluid, proteins, and cells from the interstitium back into the blood, providing functions essential for maintaining fluid balance, immune cell trafficking, and lipid absorption from the intestine. The lymphatics generate flow through both extrinsic pumping mechanisms, such as contraction of surrounding skeletal muscle, and through the intrinsic contractility of each lymphatic vessel unit known as a lymphangion. Specialized lymphatic muscle, working in coordination with uni-directional valves separating each lymphangion, serves to contract up to 80% of the vessel diameter and drive flow from the interstitium back to the venous circulation.


2021 ◽  
Vol 8 ◽  
Author(s):  
Takuro Miyazaki ◽  
Akira Miyazaki

Lymphatic vessels are necessary for maintaining tissue fluid balance, trafficking of immune cells, and transport of dietary lipids. Growing evidence suggest that lymphatic functions are limited under hypercholesterolemic conditions, which is closely related to atherosclerotic development involving the coronary and other large arteries. Indeed, ablation of lymphatic systems by Chy-mutation as well as depletion of lymphangiogenic factors, including vascular endothelial growth factor-C and -D, in mice perturbs lipoprotein composition to augment hypercholesterolemia. Several investigations have reported that periarterial microlymphatics were attracted by atheroma-derived lymphangiogenic factors, which facilitated lymphatic invasion into the intima of atherosclerotic lesions, thereby modifying immune cell trafficking. In contrast to the lipomodulatory and immunomodulatory roles of the lymphatic systems, the critical drivers of lymphangiogenesis and the details of lymphatic insults under hypercholesterolemic conditions have not been fully elucidated. Interestingly, cholesterol-lowering trials enable hypercholesterolemic prevention of lymphatic drainage in mice; however, a causal relationship between hypercholesterolemia and lymphatic defects remains elusive. In this review, the contribution of aberrant lymphangiogenesis and lymphatic cholesterol transport to hypercholesterolemic atherosclerosis was highlighted. The causal relationship between hypercholesterolemia and lymphatic insults as well as the current achievements in the field were discussed.


Development ◽  
2021 ◽  
Vol 148 (11) ◽  
Author(s):  
Mathias Francois ◽  
Anna Oszmiana ◽  
Natasha L. Harvey

ABSTRACT The lymphatic vasculature is an integral component of the cardiovascular system. It is essential to maintain tissue fluid homeostasis, direct immune cell trafficking and absorb dietary lipids from the digestive tract. Major advances in our understanding of the genetic and cellular events important for constructing the lymphatic vasculature during development have recently been made. These include the identification of novel sources of lymphatic endothelial progenitor cells, the recognition of lymphatic endothelial cell specialisation and heterogeneity, and discovery of novel genes and signalling pathways underpinning developmental lymphangiogenesis. Here, we review these advances and discuss how they inform our understanding of lymphatic network formation, function and dysfunction.


2019 ◽  
Author(s):  
Daniel Peña-Jimenez ◽  
Silvia Fontenete ◽  
Diego Megias ◽  
Coral Fustero-Torre ◽  
Osvaldo Graña-Castro ◽  
...  

AbstractLymphatic vessels (LV) are essential for skin fluid homeostasis and immune cell trafficking, but whether LV are associated with hair follicle (HF) regeneration is not known. Here, by using steady and live imaging approaches in mouse skin, we show that lymphatic capillaries distribute to the anterior permanent region of individual HF and interconnect neighboring HF at the level of the HF bulge, in a hair follicle stem cell (HFSC)-dependent manner. LV further connect individual HF in triads and dynamically flow across the skin. Interestingly, at the onset of the physiological HFSC activation, or upon pharmacological or genetic induction of HF growth, LV transiently expand their caliber suggesting an increased tissue drainage capacity. Interestingly, the physiological LV caliber increase is associated with a distinct gene expression correlated to ECM and cytoskeletal reorganization. Using mouse genetics, we show that the depletion of LV blocks the pharmacological induction of HF growth. Our findings define LV as components of the HFSC niche, coordinating HF connections at tissue-level, and provide insight into their functional contribution to HF regeneration.


2008 ◽  
Vol 20 (9) ◽  
pp. 56
Author(s):  
H. M. Brown ◽  
R. L. Robker ◽  
D. L. Russell

The lymphatic system is important for return of extra-vascular fluid to the blood circulation, conductance of hormones and immune cell trafficking. Delicate hormonal control of fluid conductance during reproductive cycles is exemplified by the ovarian hyperstimulation syndrome, a dangerous condition of hypovolemia caused by fluid accumulation in the abdomen and reproductive tissues, in response to hormonal hyperstimulation. This study is the first to investigate the relationship between ovarian lymphatic development and follicle growth. Quantitative morphometric analysis of vessel size and number in mouse ovary revealed, for the first time, that the ovarian lymphatic vasculature develops postnatally and in synchrony with the induction of ovarian CYP19a1 (Aromatase); the time when secondary follicles become FSH-responsive and estrogenic. Mechanistically, we found that the FSH-analogue eCG mediates induction of lymphatic vascular endothelial growth factor Vegfd and the receptor Vegfr3 (Flt4) in granulosa cells. Importantly, stimulation with eCG also enhanced ovarian lymphatic vessel number and size. However, formation of ovarian lymphatics also required the matrix-remodelling protease Adamts1, since ovaries from Adamts1−/− mice failed to undergo normal lymphatic vascular development. Treatment of Adamts1 null mice with eCG significantly increased the number and size of ovarian lymphatic vessels, however, the vessels were still smaller and fewer in number than wildtypes. These combined results indicate that the ovarian lymphatic system develops in response to hormonal signals, which promote folliculogenesis, through induction of lymphangiogenic factors in granulosa cells; as well as involving Adamts1-dependent mechanisms. This study is the first demonstration of the novel principle of hormonal regulation of lymphangiogenesis in any tissue and suggests a requirement for functional lymphatics during normal folliculogenesis. In addition our results inform the elucidation of the tightly regulated processes that control fluid dynamics and immune cell surveillance within reproductive tissues.


Author(s):  
J. Brandon Dixon

The lymphatic vasculature extends through most tissues of the body and plays an essential role in maintaining fluid balance, immune cell trafficking, and lipid transport. Nearly all dietary lipid is transported from the intestine to the circulation via the lymphatic system in the form of triglyceride-rich lipoproteins called chylomicrons. This process can be described through two different mechanisms: 1) entry of the chylomicron into the initial lymphatic vessels of the small intestine, known as lacteals, and 2) the transport of these chylomicrons through the larger collecting lymphatics by a complex and coordinated system of individual contracting vessel units (lymphangions) and valve leaflets. We describe here a set of in vitro and in vivo tools we have developed to study the mechanisms that modulate lipid transport under these two different paradigms and show how these tools are uncovering important biological features involved in these mechanisms. Lymphatic pump function is known to be sensitive to the mechanical load on the vessel as the contractility of isolated vessels has been shown to be both shear and stretch sensitive [1], yet whether these mechanisms are important in regulating contractile function in vivo remains uncertain.


Heart ◽  
2019 ◽  
Vol 105 (23) ◽  
pp. 1777-1784 ◽  
Author(s):  
Niklas Telinius ◽  
Vibeke Elisabeth Hjortdal

The lymphatic vasculature has traditionally been considered important for removal of excessive fluid from the interstitial space, absorption of fat from the intestine and the immune system. Advances in molecular medicine and imaging have provided us with new tools to study the lymphatics. This has revealed that the vessels are actively involved in regulation of immune cell trafficking and inflammation. We now know much about how new lymphatic vessels are created (lymphangiogenesis) and that this is important in, for example, wound healing and tissue repair. The best characterised pathway for lymphangiogenesis is the vascular endothelial growth factor C (VEGF-C)/VEGFR3 pathway. Over recent years, there has been an increasing interest in the role of the lymphatics in cardiovascular medicine. Preclinical studies have shown that lymphangiogenesis and immune cell trafficking play a role in cardiovascular conditions such as atherosclerosis, recovery after myocardial infarction and rejection of cardiac allografts. Targeting the VEGF-C/VEGFR3 pathway can be beneficial in these conditions. The clinical spectrum of lymphatic abnormalities and lymphoedema is wide and overlaps with congenital heart disease. Important long-term complications to the Fontan circulation involves the lymphatics. New and improved imaging modalities has improved our understanding and management of these patients. Lymphatic leaks and flow abnormalities can be successfully treated, minimally invasively, with percutaneous embolisation. Future research will prove if the preclinical findings that point to a role of the lymphatics in several cardiovascular conditions will result in new treatment options.


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