Ceramides in peripheral arterial plaque lead to endothelial cell dysfunction

Area of Science:

• Lipidomics
• Vascular Biology
• Diabetic Complications

Background:

• Peripheral arterial disease (PAD) and its severe form, chronic limb-threatening ischemia (CLTI), are prevalent, particularly in individuals with diabetes.
• Bioactive lipids are altered in arterial tissue of diabetic patients with advanced PAD.

Purpose of the Study:

• To evaluate the role of sphingolipid ceramide 18:1/16:0 (C16) as a cellular regulator in endothelial cells and peripheral tibial arteries of diabetic individuals.
• To investigate the association between C16 levels, arterial disease severity, and endothelial cell function in diabetes.

Main Methods:

• Analysis of ceramide C16 levels in tibial arterial tissue from patients with and without diabetes.
• Assessment of sphingomyelin phosphodiesterase (SMPD) and ceramide synthase (CERS) gene expression.
• In vitro studies using human umbilical vein endothelial cells (HUVECs) exposed to C16, including proliferation, apoptosis, and autophagy assays.
• Selective knockdown of SMPD2 and SMPD4 in HUVECs.

Main Results:

• Ceramide C16 was the most elevated ceramide in tibial arteries of diabetic patients (11% increase).
• C16 levels correlated positively with sphingomyelin (SPM) content.
• Elevated SMPD expression, particularly SMPD4, was observed in diseased tibial arteries.
• Exogenous C16 reduced HUVEC proliferation, increased apoptosis, and decreased autophagy.
• SMPD4 knockdown rescued cellular proliferation after C16 exposure.

Conclusions:

• Ceramide C16 serves as a tissue biomarker for PAD severity in diabetes.
• C16 significantly impacts endothelial cell viability and function, highlighting its role in diabetic vascular complications.