The lymphatic vascular system: much more than just a sewer

Area of Science:

• Vascular Biology
• Physiology
• Cell Biology

Background:

• The lymphatic vascular system (LVS), rediscovered in 1628, remains enigmatic in its structure, function, development, and evolution.
• Historically, LVS research interest has been limited due to its low visibility and less immediately life-threatening diseases compared to the blood vascular system.
• Commonly attributed LVS functions include fluid homeostasis, chylomicron uptake, and immune cell circulation, but its molecular complexity suggests broader roles.

Purpose of the Study:

• To explore the multifaceted functions of the lymphatic vascular system beyond its traditionally recognized roles.
• To highlight the diverse physiological contributions of lymphatic endothelial cells and their implications in pathophysiology.
• To discuss site-specific characteristics, embryonic origins, and evolutionary aspects of the LVS.

Main Methods:

• Review and synthesis of existing literature on lymphatic vascular system structure, function, and development.
• Analysis of the molecular equipment of lymphatic endothelial cells.
• Comparative discussion of somatic and splanchnic lymphatics, including phylogenetic considerations.

Main Results:

• The LVS performs a wider array of functions than commonly appreciated, including hyaluronan turnover, salt balance, coagulation, extracellular matrix production, adipose tissue development, and potential appetite regulation.
• Hypoxia significantly influences the regulation of these diverse lymphatic functions.
• Significant differences exist in embryonic origin and molecular composition between somatic and splanchnic lymphatics.

Conclusions:

• The functions of the lymphatic vascular system are far more extensive than generally understood.
• Future lymphatic research promises numerous interesting and surprising discoveries.
• Understanding the LVS's broad roles is crucial for advancing physiological and pathological insights.