Tribulus terrestris L. Extract Alleviates Atherosclerosis by Suppressing TNF-α-Mediated Macrophage Inflammation

Atherosclerosis (AS) is a major contributor to cardiovascular disease. In traditional Chinese medicine, Tribulus terrestris L., or Baijili (BJL), has shown therapeutic effects on inflammation and cardiovascular issues. Our prior research indicated that BJL inhibited LPS-induced inflammatory factor expression in macrophages, but this does not confirm its anti-atherosclerotic effects. To model AS, ApoE^-/- mice were fed a high-fat diet (HFD) and treated with Lipitor or BJL (50, 100, or 200 mg/kg/day). Assessments included aortic plaque area, serum lipid profiles, and serum cytokine levels. Bioinformatics, WGCNA, and machine learning were used to identify macrophage-associated AS key functional genes (ASKFGs). Molecular docking and dynamics simulations assessed interactions of BJL's components, Hecogenin (Heco) and Tigogenin (Tigo), with proteins like MMP-9 and TNF-α. In vitro, LPS-stimulated RAW264.7 macrophages were used to evaluate the effects of BJL, Heco, and Tigo on inflammatory gene and protein expression via RT-qPCR and Western blot. Results showed that BJL administration, particularly at 50 mg/kg/day, significantly reduced aortic plaque area, decreased serum TC and LDL-C levels, and lowered inflammatory cytokines in HFD-fed ApoE^-/- mice. Computational analyses identified 202 macrophage-related AS disease genes, with TNF, MMP-9, CXCR2, and CD36 validated as key targets. Molecular modeling showed both Heco and Tigo have favorable ADMET properties and stable interactions with MMP-9 and TNF-α. Tigo demonstrated potent binding activity with a peak energy of approximately -26 kcal/mol for TNF-α and -20 kcal/mol for MMP-9. In vitro, Tigo markedly inhibited LPS-induced expression of TNF-α, MMP-9, and CXCR2 in macrophages. Mechanistically, Tigo suppressed inflammation by inhibiting the TNF-α/NF-κB signaling pathway, as evidenced by the reduced phosphorylation of p65 and IκBα. In conclusion, BJL alleviates atherosclerosis in ApoE^-/- mice by suppressing macrophage-mediated inflammation, partly through downregulation of CD36 and CXCR2. Tigogenin, a key saponin in BJL, contributes to these anti-inflammatory effects by inhibiting TNF-α production and the NF-κB signaling pathway in macrophages. These findings suggest Tigo may be a promising candidate for targeting inflammatory mechanisms in atherosclerosis.