Dihydrotanshinone I attenuates plaque vulnerability in ApoE-/- mice: role of RIP3.

Vulnerable plaque disruption in advanced atherosclerosis leads to acute thrombus and subsequent myocardial infarction and severely threatens human health. Necroptosis of macrophage involved in the necrotic core is one key factor for plaque vulnerability. Dihydrotanshinone I (DHT) is a natural diterpenoid isolated from Danshen demonstrating effective anti-inflammatory property. It is accepted that inflammation plays a crucial role in the process of atherogenesis. However, whether DHT prevents atherosclerosis is poorly understood. Here, we investigated the effect of DHT on vulnerable plaque in ApoE-/- mice model of atherosclerosis and the underlying protective mechanisms.In the in vitro experiment, firstly LPS/ZVAD (LPS, lipopolysaccharide; ZVAD, ZVAD-FMK, a cell-permeable pan-caspase inhibitor) stimulated necroptosis of macrophage in a RIP3-dependent pathway which was regulated by TLR4 dimerization. Further study illustrated that activated RIP3 evoked endoplasmic reticulum (ER) stress as well as reactive oxygen species (ROS) generation. Both DHT and RIP3 silence reversed above phenomena. In the in vivo experiment, aorta and serum samples were collected to determine features of plaque stability including plaque size, necrotic core area as well as collagen content in fibrous cap and the expression of related protein molecules. Both DHT and RIP3 inhibitor GSK872 significantly enhanced plaque stability in ApoE-/- mice by reducing oxidative stress, shrinking necrotic core area, increasing collagen content and decreasing RIP3 expression. Innovation and Conclusion: Our study showed that DHT may stabilize vulnerable plaque by suppressing RIP3-mediated necroptosis of macrophage which indicates its potential application as a lead compound for cardiovascular treatments, especially for advanced atherosclerosis.