Combination of the LPS/TLR4 Pathway and Fecal Metabolomics Analysis Reveals the Chronic Inflammatory Mechanism of Early Atherosclerosis in Tibetan Miniature Pigs

Abstract. Objective:. This study aimed to elucidate the effect of the lipopolysaccharides/toll-like receptor 4 (LPS/TLR4) pathway on early atherosclerosis (AS) development and its associated changes in fecal metabolites, thereby providing an experimental foundation for strategies to prevent and treat early AS. Methods:. Twelve Tibetan miniature pigs aged 4–5 months were divided into normal control (NC) group and AS group (6 pigs in each). The group assignment was primarily based on body weight; Secondary criteria, including glucose, lipid profiles, and inflammatory indices, were considered to ensure balanced baseline characteristics between the 2 groups (all P > 0.05). AS group received a high-fat diet for 16 weeks to establish an AS model, while the NC group received a normal diet. Subsequently, serum levels of lipids and various inflammation and oxidative stress markers were measured. Pathological changes in the aorta and colon tissue, LPS/TLR4 pathway-associated protein expressions in the aorta, as well as occludin and zonula occludens-1 in the colon were also assessed. Proton nuclear magnetic resonance spectra technology was employed for the metabolomic analysis of fecal extracts. Results:. The lipid metabolism was disrupted in AS group, with significantly higher total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels ((12.24 ± 5.24) mmol/L vs. (1.86 ± 0.27) mmol/L, P = 0.004,6; (2.39 ± 0.50) mmol/L vs. (0.83 ± 0.07) mmol/L, P = 0.000,5; (6.94 ± 2.87) mmol/L vs. (0.77 ± 0.18) mmol/L, P = 0.003,3), as compared to that in NC group. Serum factors, including LPS, tumor necrosis factor-α, and malondialdehyde levels of AS group were significantly higher than that of NC group ((1,230.00 ± 192.70) EU/L vs. (695.70 ± 213.70) EU/L), P = 0.001,1; (424.20 ± 176.90) ng/L vs. (51.20 ± 26.61) ng/L, P = 0.023,5; (3.60 ± 0.77) nmol/mL vs. (2.62 ± 0.21) nmol/mL, P = 0.025,4). Pathological evaluations revealed prominent lipid deposition area in the aortic arch, thoracic aorta, and abdominal aorta of the AS group compared with that of the NC group (4.17% ± 2.30% vs. 0, P = 0.006,7; 6.23% ± 2.95% vs. 0, P = 0.003,6; 3.78% ± 2.18% vs. 0, P = 0.008,1). TLR4, nuclear factor kappa-B p65, and tumor necrosis factor-α expression in the aorta tissue of the AS group were upregulated, whereas occludin and zonula occludens-1 expression in colon tissues was downregulated. Additionally, metabolomics identified significant differences in 21 metabolites in the feces of the AS group compared to the NC group, with further analysis linking these differences to amino acid metabolism. Conclusions:. The Tibetan miniature pig model of early AS induced by high-fat intake displayed pronounced chronic inflammation. Preliminary findings suggest that the underlying mechanisms may be associated with the LPS/TLR4 pathway and intestinal metabolic disorders.