Lymphatic System in Cardiovascular Medicine

Abstract

Abstract:The mammalian circulatory system comprises both the cardiovascular system and the lymphatic system. In contrast to the blood vascular circulation, the lymphatic system forms a unidirectional transit pathway from the extracellular space to the venous system. It actively regulates tissue fluid homeostasis, absorption of gastrointestinal lipids, and trafficking of antigen-presenting cells and lymphocytes to lymphoid organs and on to the systemic circulation. The cardinal manifestation of lymphatic malfunction is lymphedema. Recent research has implicated the lymphatic system in the pathogenesis of cardiovascular diseases including obesity and metabolic disease, dyslipidemia, inflammation, atherosclerosis, hypertension, and myocardial infarction. Here, we review the most recent advances in the field of lymphatic vascular biology, with a focus on cardiovascular disease.

Hyperplasia, de novo lymphangiogenesis, and lymphatic regression in mice with tissue-specific, inducible overexpression of murine VEGF-D

“…This regression is in contrast to models of airway lymphatic hyperplasia, induced by either inflammation or VEGF-C/D expression methods, which exists even once the driver is removed (7,54). The ability to grow lymphatic vessels, the mechanism by which expansion occurs, and the potential for regression thus appear to be varying degrees of VEGFR-3, developmental period, and tissue dependent (3,25). The TRE-VD mouse, coupled with the array of cell-specific promoter mice available, allows for a future temporal examination of these mechanisms in nearly any vascularized tissue.…”

“…Some level of VEGFR-3 signaling and lymphangiogenesis, however, appears to be necessary to reduce inflammation under challenge (3,48). The role of lymphatics in regulating tissue inflammation is highly relevant to the global obesity epidemic, wherein adipose tissue inflammation, notably infiltrating immune cells, are thought to drive the metabolic syndrome (1, 33, 52).…”

Understanding the functions and relationships of the glymphatic system and meningeal lymphatics

“…In peripheral organs, lymphatic drainage contributes considerably to tissue fluid homeostasis and immune surveillance by facilitating the clearance of excess interstitial tissue fluid, macromolecules, and immune cells from the interstitium back into blood circulation. In the lymphatic network, fluid, cells, and macromolecules are first absorbed by blind-ended lymphatic capillaries (the initial lymphatic vessels), and the flow proceeds via precollector and collector lymphatic vessels and lymph nodes, ending in the thoracic duct and the right lymphatic trunk, which deliver lymph into subclavian veins in the neck region (2). The meninges that envelop the brain and spinal cord participate in forming the various fluid compartments of the CNS.…”

“…In peripheral organs, colloids are extravasated across a fenestrated capillary bed, and these proteins, as well as excess tissue fluid, are returned to the circulating blood through a dense network of lymphatic vessels (1,2). In the CNS, the blood-brain barrier prevents unregulated protein and fluid entry into brain (3,4); however, soluble waste products are still released into the brain's interstitial spaces as a consequence of its high metabolic rate.…”

Le système lymphatique cardiaque

“…La lymphangiogenèse postnatale a, par définition, été supposée provenir de vaisseaux lymphatiques préexistants. Cependant, des études récentes montrent que ce processus chez l'adulte pourrait avoir une origine non endothéliale [13]. En raison du manque d'approches de traçage de lignage, ce domaine de recherche reste encore en cours d'investigation.…”