Endothelium, a crucial homeostatic organ, regulates vascular permeability and tone. Under physiological conditions, endothelial stimulation induces vasodilator endothelial nitric oxide (eNO) release and prevents adhesion molecule accessibility and leukocyte adhesion and migration into vessel walls. Endothelium dysfunction is a principal event in cardiovascular disorders, including atherosclerosis. Hence, current therapies focus on endothelium repair to prevent downstream cardiovascular events. However, minimal attention is given to the restoration of mechanotransducer endothelial glycocalyx (GCX), a negatively charged heterogeneous polysaccharide, which covers and protects endothelial cells. Endothelial GCX shedding plays a role in endothelial dysfunction, increasing vascular permeability and decreasing vessel tone. Diosmin, a flavone glycoside of diosmetin, downregulates adhesive molecule expression, decreases inflammation and capillary permeability, and upregulates eNO expression. Due to these pleiotropic effects of diosmin on the vasculature, a possible unidentified mechanism of action is through GCX restoration. Diosmin effect on GCX and endothelial function were assessed in a partial ligation left carotid artery (LCA) mouse model where the right carotid artery was the control for each mouse. Diosmin (50 mg/kg) was administered daily for 7 days, 48 hours after ligation. Within the ligated mice LCAs, diosmin treatment elevated the activated eNO synthase level, inhibited inflammatory cell uptake, decreased vessel wall thickness, increased vessel diameter, and increased GCX coverage of the vessel wall. ELISA showed a decrease in hyaluronan concentration in plasma samples of diosmin-treated mice, signifying reduced GCX shedding. In summary, diosmin supported endothelial GCX integrity, which preserved endothelial function by attenuating expression of inflammatory factors and restoring vascular tone.

ImageJ was utilized to quantify all immunohistochemical images, while GraphPad Prism was utilized to create graphs and conduct statistical analysis. 

Sheet one describes average percent area coverage of p-eNOS (active) in mouse carotid arteries. Sheet two describes average percent area coverage of total eNOS in mouse carotid arteries. Sheet three describes active/total eNOS (%) of each mouse, which is then normalized by the control group (diosmin:control). Sheet four describes vessel diameter and vessel wall thickness of each mouse. Sheet five describes macrophage uptake (CD68) within vessel walls of each mouse. Sheet six describes ELISA analysis of hyaluronic acid of plasma blood samples of mice. Sheet seven and eight describes glyocalyx expression via wheat germ agglutinin (WGA) which was used to calculate percent area coverage of glycocalyx in mouse vessel. Sheet nine describes WGA transversal thickness on the endothelium. Sheet ten describes hyaluronic acid (HA), component of the glycocalyx, expression on the endothelium. Sheet eleven describes the transversal thickness of HA on the endothelium. Sheet twelve describes the percent area coverage (%) of core protein syndecan-1 on the endothelium. Sheet thirteen describes the transversal thickness of synedcan-1 present on the endothelium.