The glycocalyx core protein Glypican 1 protects vessel wall endothelial cells from stiffness-mediated dysfunction and disease

Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Aims</jats:title> <jats:p>Arterial stiffness is an underlying risk factor and a hallmark of cardiovascular diseases. The endothelial cell (EC) glycocalyx is a glycan rich surface layer that plays a key role in protecting against EC dysfunction and vascular disease. However, the mechanisms by which arterial stiffness promotes endothelial cell dysfunction and vascular disease are not fully understood, and whether the mechanism involves the protective endothelial glycocalyx is yet to be determined. We hypothesized that endothelial glycocalyx protects the endothelial cells lining the vascular wall from dysfunction and disease in response to arterial stiffness.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods and Results</jats:title> <jats:p>Cells cultured on polyacrylamide (PA) gels of substrate stiffness 10 kPa (mimicking the subendothelial stiffness of aged, unhealthy arteries) showed a significant inhibition of glycocalyx expression compared to cells cultured on softer PA gels (2.5 kPa, mimicking the subendothelial stiffness of young, healthy arteries). Specifically, gene and protein analyses revealed that a glycocalyx core protein Glypican 1 was inhibited in cells cultured on stiff PA gels. These cells had enhanced endothelial cell dysfunction as determined by enhanced cell inflammation (enhanced inflammatory gene expression, monocyte adhesion and inhibited nitric oxide expression), proliferation and EndMT. Removal of Glypican 1 using gene-specific silencing with siRNA or gene overexpression using a plasmid revealed that Glypican 1 is required to protect against stiffness-mediated endothelial cell dysfunction. Consistent with this, using a model of age-mediated stiffness, older mice exhibited a reduced expression of Glypican 1 and enhanced endothelial cell dysfunction compared to young mice. Glypican1 gene deletion in knockout mice (GPC1 -/-) exacerbated endothelial dysfunction in young mice, which normally had high endothelial expression, but not in old mice that normally expressed low levels.</jats:p> <jats:p>Endothelial cell dysfunction was exacerbated in young, but not aged, Glypican 1 knockout mice (GPC1 -/-).</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Arterial stiffness promotes EC dysfunction and vascular disease at least partly through the suppression of the glycocalyx protein Glypican 1. Glypican 1 contributes to the protection against endothelial cell dysfunction and vascular disease in endothelial cells.</jats:p> </jats:sec> <jats:sec> <jats:title>Translational Perspective</jats:title> <jats:p>This work reveals for the first time the effect of arterial stiffness on the glycocalyx protein Glypican 1 in endothelial cell function. Stiffness promotes endothelial cell dysfunction and subsequently vascular disease at least partly through the suppression of Glypican 1. Thus, Glypican 1 could be a novel therapeutic candidate for the treatment/reversal of arterial stiffness-mediated vascular disease.</jats:p> </jats:sec>

The Glycocalyx and Its Role in Vascular Physiology and Vascular Related Diseases

“…In a recent study, Mahmoud et al . 120 showed that EC grown on polyacrylamide (PA) gels of substrate stiffness 10 kPa (mimicking the subendothelial stiffness of aged, unhealthy arteries) displayed a significant inhibition of GCX expression compared to cells cultured on softer PA gels (2.5 kPa, mimicking the subendothelial stiffness of young, healthy arteries). The effect of stiffness on HS immunostaining is displayed in Fig.…”

“…In Part B we emphasize that it is now recognized that artery wall stiffness associated with hypertension and aging induces GCX degradation, endothelial dysfunction and vascular disease. 120 In addition to atherosclerosis and cardiovascular diseases, the GCX plays an important role in lifestyle related diseases (e.g., diabetes) and cancer. 200 Infectious diseases including sepsis, Dengue, Zika and Corona viruses, and malaria also involve the GCX.…”

The Mechanobiology of Endothelial-to-Mesenchymal Transition in Cardiovascular Disease

“…In a model of age-mediated stiffness, there was reduced expression of Glypican 1 and greater EC dysfunction in older mice compared to young mice. Furthermore, Glypican 1 gene deletion exacerbated EC dysfunction in young mice but not aged mice ( Mahmoud et al, 2020 ). These results suggest that the glycocalyx layer of ECs plays an important protective role against EndMT associated with increasing stiffness of the endothelial microenvironment present in age-mediated arterial stiffening.…”

Special Issue on Professor John M. Tarbell’s Contribution to Cardiovascular Engineering

“…3 And most recently, with post doc Marwa Mahmoud, we showed that endothelial substrate stiffness that is associated with hypertension and aging, leads to glycocalyx suppression and endothelial dysfunction being mediated by a loss of glypican 1. 23 At the time of this writing my lab continues to work on substrate stiffness effects mediated by the glycocalyx with Marwa Mahmoud, methods to suppress cancer metastasis through glycocalyx modification with Limary Cancel, Heriberto Moran and Lance Munn, and transport properties of the blood-brain barrier associated with transcranial direct current stimulation in collaboration with Limary Cancel, Bingmei Fu and my neural engineering colleague, Marom Bikson. 5 As I look back on my career, which I am pleased to say is not yet over, I realize that I have worked on many problems, some would say too many.…”