Paeonol reduces microbial metabolite α-hydroxyisobutyric acid to alleviate the ROS/TXNIP/NLRP3 pathway-mediated endothelial inflammation in atherosclerosis mice / 中国天然药物

Gut microbiota dysbiosis is an avenue for the promotion of atherosclerosis (AS) and this effect is mediated partly via the circulating microbial metabolites. More microbial metabolites related to AS vascular inflammation, and the mechanisms involved need to be clarified urgently. Paeonol (Pae) is an active compound isolated from Paeonia suffruticoas Andr. with anti-AS inflammation effect. However, considering the low oral bioavailability of Pae, it is worth exploring the mechanism by which Pae reduces the harmful metabolites of the gut microbiota to alleviate AS. In this study, ApoE-/- mice were fed a high-fat diet (HFD) to establish an AS model. AS mice were administrated with Pae (200 or 400 mg·kg-1) by oral gavage and fecal microbiota transplantation (FMT) was conducted. 16S rDNA sequencing was performed to investigate the composition of the gut microbiota, while metabolomics analysis was used to identify the metabolites in serum and cecal contents. The results indicated that Pae significantly improved AS by regulating gut microbiota composition and microbiota metabolic profile in AS mice. We also identified α-hydroxyisobutyric acid (HIBA) as a harmful microbial metabolite reduced by Pae. HIBA supplementation in drinking water promoted AS inflammation in AS mice. Furthermore, vascular endothelial cells (VECs) were cultured and stimulated by HIBA. We verified that HIBA stimulation increased intracellular ROS levels, thereby inducing VEC inflammation via the TXNIP/NLRP3 pathway. In sum, Pae reduces the production of the microbial metabolite HIBA, thus alleviating the ROS/TXNIP/NLRP3 pathway-mediated endothelial inflammation in AS. Our study innovatively confirms the mechanism by which Pae reduces the harmful metabolites of gut microbiota to alleviate AS and proposes HIBA as a potential biomarker for AS clinical judgment.

Trichostatin C attenuates TNFα-induced inflammation in endothelial cells by up-regulating Krüppel-like factor 2 / 药学学报

Krüppel-like transcription factor 2 (KLF2) plays a key regulatory role in endothelial inflammation, thrombosis, angiogenesis and macrophage inflammation and polarization, and up-regulation of KLF2 expression has the potential to prevent and treatment atherosclerosis. In this study, trichostatin C (TSC) was obtained from the secondary metabolites of rice fermentation of Streptomyces sp. CPCC 203909 as a KLF2 up-regulator by using a high throughput screening model based on a KLF2 promoter luciferase reporter assay. TSC significantly inhibited the adhesion of tumor necrosis factor-α (TNFα) induced monocytes (THP-1) to human umbilical vein endothelial cells (HUVECs). Western blot results showed that TSC decreased TNFα induced the protein expression increase of vascular cell adhesion molecule-1 (VCAM-1), and thereby inhibited endothelial inflammation. The results of histone deacetylase (HDAC) overexpression and molecular docking experiments showed that TSC upregulated the expression of KLF2 by inhibiting subtypes of HDAC 4/5/7. In conclusion, this study suggests that TSC up-regulates the expression of KLF2 through inhibiting HDAC 4/5/7 and thus inhibits TNFα induced endothelial inflammation, and it has the potential to prevent and treat atherosclerosis.

Glycemic index of dietary formula may not be predictive of postprandial endothelial inflammation: a double-blinded, randomized, crossover study in non-diabetic subjects

The emerging role of endothelial inflammation in diabetes has stimulated research interest in the effects of nutrition on related indices. In the current study we investigated whether the nutrient composition of dietary formula as reflected in glycemic index (GI) may be predictive of postprandial endothelial inflammation in non-diabetic subjects. A double-blinded, randomized, crossover study was conducted in non-diabetic subjects (n = 8/group). Each subject consumed three types of diabetes-specific dietary formulas (high-fiber formula [FF], high-monounsaturated fatty acid (MUFA) formula [MF] and control formula [CF]) standardized to 50 g of available carbohydrates with a 1-week interval between each. The mean glycemic index (GI) was calculated and 3-hour postprandial responses of insulin, soluble intercellular adhesion molecule-1 (sICAM-1), nitrotyrosine (NT) and free fatty acids (FFA) were measured. The MF showed the lowest mean GI and significantly low area under the curve (AUC) for insulin (P = 0.038), but significantly high AUCs for sICAM-1 (P < 0.001) and FFA (P < 0.001) as compared to the CF and FF. The FF showed intermediate mean GI, but significantly low AUC for NT (P < 0.001) as compared to the CF and MF. The mean GI was not positively correlated to any of the inflammatory markers evaluated, and in fact negatively correlated to changes in FFA (r = -0.473, P = 0.006). While the MF with the lowest GI showed the highest values in most of the inflammatory markers measured, the FF with intermediate GI had a modest beneficial effect on endothelial inflammation. These results suggest that nutrient composition of dietary formula as reflected in the GI may differently influence acute postprandial inflammation in non-diabetic subjects.