Ligustilide Targets SMAD3, Showing Immunomodulatory Effects in Improving Atherosclerosis

Backgrounds: Atherosclerosis is initiated by the local immune response to lipid deposition, and the most commonly administered antiatherogenic drugs are lipid regulators, particularly statins. However, statins appear to be weak in regulating immunity. Based on traditional ethnopharmacological evidence, in this paper, we aimed to find effective therapeutic agents other than statins and to elucidate their potential action mechanisms.   Methods: A traditional Chinese Medicine (TCM), Suxiao Jiuxin Pill (SX) has been widely used in curing cardiovascular diseases for thirty years. With a combination of pharmacologic studies on atherosclerosis and RNA-Seq transcriptomics were employed to explore the pharmacodynamic differences of SX and atorvastatin in the ApoE-/- mouse. The active ingredients in SX, were screened by biomarker CD137, which is closely associated with anti-atherosclerosis. Then, chemical proteomics based on a ligustilide-derived photoaffinity probe were applied to identify potential targets and active mechanism for developing the therapeutic effects of SX. Findings: Differentially expressed genes (DEGs) that were modulated by SX to a greater degree than atorvastatin were primarily involved in immunomodulation, and secondarily in cholesterol export. Ligustlide was the active ingredient in SX and its potential target was SMAD3. Ligustilide suppressed the phosphorylation and nuclear translocation of SMAD3 by blocking the mutual interaction of SMAD3 and transforming growth factor-β (TGF-β) receptor І. Interpretation: Ligustilide suppresses local lipid accumulation and achieves immunomodulation by targeting SMAD3 and the TGF-β1/SMAD3 pathway, thereby improving atherosclerosis. Developing a novel SMAD3 inhibitor may be a therapeutic option for preventing atherosclerosis in combination therapy with statins   Funding Statement: This work was financially supported by National Key Research and Development Program of China (No. 2018YFC1704805, 2018YFC1704505) and International Cooperation and Exchange of the National Natural Science Foundation of China (No. 81761168039). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: All animal procedures conformed to the Council of Europe Convention Directive (2010/63/EU) for the protection of vertebrate animals used for scientific purposes. And all animal procedures were performed strictly according to the guidelines for the care and use of laboratory animals, which was approved by Tianjin University of Traditional Chinese Medicine (TCM-LAEC2016032).