Background and Purpose: The gut microbial metabolite butyrate is linked to the modulation of metabolic disease. The mechanism by which butyrate effects in atherosclerosis is unknown. Hence, the present investigation into effects of butyrate on high‐fat diet‐fed ApoE^−/− mice after 16 weeks' administration.Experimental Approach: Gut microbiota composition was analysed via 16S rRNA gene sequencing of caecal contents. The effects of butyrate on atherosclerosis were evaluated in vivo using the ApoE^−/− mice model. Serum lipids and glucose were analysed for physiological changes and differentially expressed genes in liver samples were identified by hepatic transcriptome profiling. The proteins involved in reverse cholesterol transport were quantified by Western blot and immunohistochemical staining. Finally, the up‐regulatory effects of butyrate on ATP‐binding cassette sub‐family A member 1 (ABCA1) were further evaluated in RAW 264.7 cells along with role of specificity protein 1 by inhibition and silencing.Key Results: Oral gavage of butyrate altered microbiota composition and enhanced gut microbial diversity that was decreased by high fat diet (HFD). Butyrate treatment significantly inhibited the HFD‐induced atherosclerosis as well as hepatic steatosis without changing body weight gain in ApoE^−/− mice. Butyrate had metabolic effects on the liver by regulation of gene expression involved in lipid/glucose metabolism. Furthermore, ABCA1 was significantly induced by butyrate in vivo, ex vivo and in vitro and Sp1 pathway was identified as a potential mechanism.Conclusion and Implications: Butyrate ameliorates HFD‐induced atherosclerosis in ApoE^−/− mice via ABCA1‐mediated cholesterol efflux in macrophages, which suggesting a promising therapeutic strategy for protecting against atherosclerosis.

Trimethylamine-N-oxide (TMAO), a gut-microbiota-dependent metabolite generated from its dietary precursors such as choline, has been identified as an independent risk factor for atherosclerosis. Metformin is the most widely used drug for the treatment of type 2 diabetes (T2D), which has therapeutic effects on hyperglycemia accelerated atherosclerosis. A growing body of evidence suggest that metformin plays a therapeutic role by regulating the structure and metabolic function of gut microbiota. However, whether metformin has an impact on gut-microbiota-mediated TMAO production from choline remains obscure. In this study, the oral administration of metformin significantly reduced choline diet-increased serum TMAO in choline diet-fed C57BL/6J mice. The diversity analysis based on 16S rRNA gene sequencing of C57BL/6J mice fecal samples indicated that metformin markedly changed the gut-microbiota composition. Metformin was positively correlated with the enrichment of different intestinal bacteria such as Bifidobacterium and Akkermansia and a lower cutC (a choline utilization gene) abundance. Furthermore, the ex vivo and in vitro inhibitory effects of metformin on choline metabolism of TMA-producing bacteria were confirmed under anaerobic condition. The results suggested that metformin suppresses serum TMAO level by remodeling gut microbiota involved in TMA generation from choline.

Objective: Reverse cholesterol transport, removing excess cholesterol from peripheral tissues, is an important therapeutic target for atherosclerosis treatment. In this study, we propose a new small molecule, E17241, that may be used to treat atherosclerosis by promoting reverse cholesterol transport via ABCA1 (ATP-binding cassette transporter A1) upregulation. Approach and Results: E17241 (4-(1,3-dithiolan-2-yl)-N-(3-hydroxypyridin-2-yl)benzamide) was first identified as an ABCA1 upregulator using a cell-based reporter assay. E17241 significantly increases the mRNA and protein expression levels of ABCA1 in both hepatic cells and macrophages. It promotes cholesterol efflux to apo AI in macrophage cells, and this effect depends on ABCA1. It also decreases total cholesterol content in Ox-LDL (oxidized low-density lipoprotein) loading macrophage cells. E17241 treatment increases the content of ³ H-labeled cholesterol in the feces of male C57BL/6J mice intraperitoneally injected with ³ H-cholesterol-labeled macrophage J774 cells, indicating that it could promote in vivo macrophage reverse cholesterol transport. Compared with the western diet group (western diet–fed male ApoE ^−/− mice), the E17241 group (western diet+E17241 treatment) shows decreased plasma cholesterol, liver cholesterol, and triglyceride levels, with increased fecal cholesterol content. Importantly, E17241 reduces atherosclerotic lesion areas in the en face aorta and aortic sinus while increasing ABCA1 protein levels in both liver and macrophages. Human proteome microarray, coimmunoprecipitation, and other assays demonstrate that PKCζ (protein kinase C zeta) is a binding target of E17241, and this small molecule increases ABCA1 expression in macrophages via the PKCζ-NR (nuclear receptor) pathway. Conclusions: E17241 may be developed as a new lead or drug candidate for the treatment of atherosclerosis by upregulating ABCA1.