Toll-like receptors in atherosclerosis

Area of Science:

• Immunology
• Cardiovascular Research
• Molecular Biology

Background:

• Atherosclerosis is now understood as a chronic inflammatory disease of the arterial wall, not merely a lipid storage issue.
• Innate immune mechanisms, particularly Toll-like receptors (TLRs), are implicated in atherosclerosis due to links with hyperlipidaemia and infection.
• Oxidized lipids and infectious agents can act as ligands for TLRs, potentially initiating or exacerbating inflammation in atherosclerosis.

Purpose of the Study:

• To investigate the role of Toll-like receptor 2 (TLR2) in the development of atherosclerosis.
• To identify the cellular sources of proatherogenic TLR2 responses in hyperlipidaemic conditions.
• To differentiate TLR2-mediated inflammatory pathways involving bone-marrow-derived cells (BMDC) versus non-BMDC.

Main Methods:

• Utilized murine models of atherosclerosis, specifically mice deficient in low-density lipoprotein receptor.
• Administered defined synthetic agonists (Pam3 CSK4) and studied responses to unknown endogenous/exogenous agonists.
• Differentiated cellular contributions by analyzing responses in bone-marrow-derived cells (BMDC) and non-BMDC, including endothelial cells.

Main Results:

• Demonstrated a significant role for TLR2 in promoting atherosclerosis in hyperlipidaemic mice.
• Showed that proatherogenic TLR2 responses to endogenous or unknown exogenous agonists are mediated by non-BMDC.
• Identified that TLR2 responses to the synthetic agonist Pam3 CSK4 are partly mediated by BMDC, including monocytes/macrophages and dendritic cells.

Conclusions:

• TLR2 activation by both endogenous and exogenous agents contributes to atherosclerosis in hyperlipidaemic mice.
• Both bone-marrow-derived cells and non-bone-marrow-derived cells, such as endothelial cells, mediate proatherogenic TLR2 signaling.
• Targeting TLR2 pathways presents a potential therapeutic strategy for atherosclerosis prevention and treatment.