TLR2 Promotes Vascular Smooth Muscle Cell Chondrogenic Differentiation and Consequent Calcification Via the Concerted Actions of Osteoprotegerin Suppression and IL-6-Mediated RANKL Induction

Guan-Lin Lee, Chang-Ching Yeh, Jing-Yiing Wu, Hui-Chen Lin, Yi-Fu Wang, Ya-Yi Kuo, Yi-Ting Hsieh, Yu-Juei Hsu, Cheng-Chin Kuo
Arteriosclerosis, Thrombosis, and Vascular Biology 2019 January 10, : ATVBAHA118311874
Objective- Vascular smooth muscle cell (VSMC) transformation to an osteochondrogenic phenotype is an initial step toward arterial calcification, which is highly correlated with cardiovascular disease-related morbidity and mortality. TLR2 (Toll-like receptor 2) plays a pathogenic role in the development of vascular diseases, but its regulation in calcification of arteries and VSMCs remains unclear. We postulate that TLR2-mediated inflammation participates in mediating atherosclerotic arterial calcification and VSMC calcification. Approach and Result s-We found that ApoE-/- Tlr2-/- genotype in mice suppressed high-fat diet-induced atherosclerotic plaques formation during initiation but progressively lost its preventative capacity, compared with ApoE-/- mice. However, TLR2 deficiency prohibited high-fat diet-induced advanced atherosclerotic calcification, chondrogenic metaplasia, and OPG (osteoprotegerin) downregulation in the calcified lesions. Incubation of VSMCs in a calcifying medium revealed that TLR2 agonists significantly increased VSMC calcification and chondrogenic differentiation. Furthermore, TLR2 deficiency suppressed TLR2 agonist-mediated VSMC chondrogenic differentiation and consequent calcification, which were triggered via the concerted actions of IL (interleukin)-6-mediated RANKL (receptor activator of nuclear factor κB ligand) induction and OPG suppression. Inhibition experiments with pharmacological inhibitors demonstrated that IL-6-mediated RANKL induction is signaled by p38 and ERK1/2 pathways, whereas the OPG is suppressed via NF-κB (nuclear factor κB) dependent signaling mediated by ERK1/2. Conclusions- We concluded that on ligand binding, TLR2 activates p38 and ERK1/2 signaling to selectively modulate the upregulation of IL-6-mediated RANKL and downregulation of OPG. These signaling pathways act in concert to induce chondrogenic transdifferentiation of VSMCs, which in turn leads to vascular calcification during the pathogenesis of atherosclerosis.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"