High TG/low HDL-C ratio-mimetic lipid stress drives diabetic atherosclerotic endothelial-macrophage dysfunction through glycocalyx disruption and CD36/ABCA1 imbalance.

A high triglyceride/high-density lipoprotein cholesterol (TG/HDL-C) ratio is strongly associated with insulin resistance and atherosclerotic cardiovascular risk, but the cellular mechanisms linking this lipid imbalance to vascular injury remain incompletely defined. This study established a combined hyperglycemic/high TG/low HDL-C ratio-mimetic in vitro model using human coronary artery endothelial cells and THP-1-derived macrophages to investigate endothelial inflammation, glycocalyx disruption, monocyte recruitment, foam-cell formation, oxidative stress, and cholesterol efflux. High TG/low HDL-C ratio-mimetic stress significantly reduced endothelial viability, increased cytotoxicity, impaired transendothelial resistance, increased fluorescein isothiocyanate (FITC)-dextran permeability, and promoted syndecan-1 shedding. The lipid-stress condition induced endothelial inflammatory activation, with increased vascular cell adhesion molecule 1 (VCAM1), intercellular adhesion molecule 1 (ICAM1), E-selectin (SELE), C-C motif chemokine ligand 2 (CCL2), interleukin 6 (IL6), and C-X-C motif chemokine ligand 8 (CXCL8) expression, accompanied by enhanced THP-1 adhesion and transmigration. Glycocalyx and junctional injury were supported by increased heparanase (HPSE) expression and reduced syndecan-1 (SDC1), tight junction protein 1 (TJP1), cadherin 5 (CDH5), wheat germ agglutinin (WGA) staining, zonula occludens-1 (ZO-1) continuity, and vascular endothelial cadherin (VE-cadherin) integrity. Endothelial-conditioned lipid stress promoted macrophage foam-cell formation, increased CD36 scavenger receptor (CD36), oxidized low-density lipoprotein receptor 1 (OLR1), and peroxisome proliferator-activated receptor gamma (PPARG) expression, enhanced cholesterol accumulation, and suppressed ATP-binding cassette transporter A1 (ABCA1)-, ATP-binding cassette transporter G1 (ABCG1)-, scavenger receptor class B member 1 (SCARB1)-, and apolipoprotein E (APOE)-associated cholesterol efflux pathways. HDL rescue broadly attenuated endothelial inflammation, oxidative stress, barrier disruption, and macrophage foam-cell formation, whereas ApoA-I exerted protective effects across the selected endothelial and macrophage endpoints in which it was evaluated. CD36 inhibition reduced macrophage lipid accumulation, whereas heparanase inhibition preserved glycocalyx integrity. These findings identify the endothelial glycocalyx-nuclear factor kappa B (NF-κB)-CD36/ABCA1 axis as a mechanistic link between the high TG/low HDL-C ratio and diabetic atherosclerotic vascular dysfunction.