Inflammation inhibition and gut microbiota regulation by TSG to combat atherosclerosis in ApoE-/- mice

Abstract

Ethnopharmacological relevance: 2,3,5,4'-Tetrahydroxy-stilbene-2-O-β-D-glucoside (TSG) is the main active component of Polygoni Multiflori Radix, a root of the homonymous plant widely used in traditional Chinese medicine. TSG has protective effects on the liver, reduces cholesterol and possesses anti-oxidant, anti-tumor, and anti-atherosclerotic properties. However, the pharmacological effects and mechanisms of action of Polygonum multiflorum on atherosclerosis (AS) have not been studied yet.

Purpose: The aim of this research was to study the effects of Polygoni Multiflori Radix Praeparata (PMRP) and its major active chemical constituent TSG on AS in ApoE-deficient (ApoE^-/-) mice fed with high fat diets to provide a scientific basis in the use of PMRP and TSG against cardiovascular diseases.

Methods: High fat diet induced AS in ApoE^-/- mice were treated with PMRP, TSG (low and high doses), and simvastatin (SIM) for 8 weeks. At the end of the treatment, mouse serum lipid levels, triglycerides (TG), and total cholesterol (TC) were measured by an oxidase method (other indicators were determined by ELISA), while the content in oxidized low density lipoprotein (ox-LDL) and the expression of inflammatory factors such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), vascular cell adhesion molecule-1 (VCAM-1), and monocyte chemotactic protein-1 (MCP-1) in the serum and aortic samples were measured by ELISA. Atherosclerotic plaque morphology was evaluated by oil red O in thoracic aorta. In addition, 16S rDNA-V4 hypervariable region genome sequence of all microbes in the fecal sample from each group was analyzed to evaluate potential structure changes in the gut microbiota after treatment with PMRP and TSG.

Results: TSG markedly inhibited AS plaque formation in ApoE^-/- mice. Furthermore, PMRP and TSG improved lipid accumulation by reducing TG and ox-LDL levels. TSG inhibited inflammation by the down-regulation of IL-6, TNF-α, VCAM-1 and MCP-1 expression in serum, and PMRP inhibited inflammation by reducing VCAM-1, ICAM-1 and CCRA expression in aortic tissue. In addition, TSG reduced or prevented AS by the regulation of the composition of the overall gut microbiota, such as Firmicutes, Bacteroidetes, Tenericutes, Proteobacteria phyla, Akkermensia genera and Helicobacter pylori.

Conclusion: PMRP and TSG improved lipid accumulation and inflammation, and regulated the intestinal microbial imbalance in ApoE^-/- mice. TSG exerted a preventive effect in the development and progression of AS.

Keywords: 2,3,5,4′-Tetrahydroxy-stilbene- 2-O-β-D-glucoside; ApoE(−/-) mice; Atherosclerosis; Gut microbiota; Inflammation; Polygoni multiflori radix praeparata.