Department of Medicine, Université de Montréal/ Montreal Heart Institute Research Centre
Lymphatic vessel function in atherosclerosis
High blood cholesterol is an important risk factor for cardiovascular diseases such as atherosclerosis. High-density lipoprotein (HDL) is called “good cholesterol” because it transports cholesterol away from tissues, such as the blood vessel walls, carrying cholesterol through the blood circulation for eventual excretion through the intestines. Unfortunately, the clinical outcomes aiming at increasing levels of circulating HDL have not been as successful as expected, suggesting that raising HDL may not lead to an increased cholesterol clearance capacity or prevention of coronary heart disease. Expressed differently, more cargo ships (cholesterol transporter) leaving from the harbour docks (blood vessel wall), have not led to much merchandise delivered (cholesterol clearance). Thus, a better understanding of the cholesterol clearance process has become necessary to efficiently modulate the progression of atherosclerosis.
In a recent study, Dr Martel and others (JCI 2013) provided new insight into the path that cholesterol takes from peripheral tissues to eventual excretion. They demonstrated that cholesterol (merchandise) gets out of tissues (harbour docks) and reaches the bloodstream (sea) by first entering so-called lymphatic vessels (canals). As the lymphatic system – lymph, from Latin lympha, meaning water – generally governs the transport of macromolecules from the tissues to the blood, and peripheral lymph contains cholesterol transporters (HDL), a role in cholesterol transport seemed logical. They theorized that enhancing the navigation conditions rather than increasing the number of cargo ships could result in improvement of cholesterol delivery efficiency. Dr Martel’s emerging research team aims to understand the mechanisms connecting abnormal lymphatic function and atherosclerosis progression, to ultimately lead to identification of new therapeutic targets that would favour atherosclerotic plaque regression and impact favourably the health and quality of life of people with heart disease.