Sini Decoction Intervention on Atherosclerosis via PPARγ-LXRα-ABCA1 Pathway in Rabbits

Tiaogan daozhuo formula attenuates atherosclerosis via activating AMPK -PPARγ-LXRα pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Tiaogan Daozhuo Formula (TGDZF) is a common formulation against atherosclerosis, however, there is limited understanding of its therapeutic mechanism.

AIM OF THIS STUDY

To examine the effectiveness of TGDZF in the treatment of atherosclerosis and to explore its mechanisms.

MATERIALS AND METHODS

In ApoE-/- mice, atherosclerosis was induced by a high-fat diet for 12 weeks and treated with TGDZF at different doses. The efficacy of TGDZF in alleviating atherosclerosis was evaluated by small animal ultrasound and histological methods. Lipid levels were measured by biochemical methods. The capacity of cholesterol efflux was tested with a cholesterol efflux assay in peritoneal macrophage, and the expression of AMPKα1, PPARγ, LXRα, and ABCA1 was examined at mRNA and protein levels. Meanwhile, RAW264.7-derived macrophages were induced into foam cells by ox-LDL, and different doses of TGDZF-conducting serum were administered. Similarly, we examined differences in intracellular lipid accumulation, cholesterol efflux rate, and AMPKα1, PPARγ, LXRα, and ABCA1 levels following drug intervention. Finally, changes in the downstream molecules were evaluated following the inhibition of AMPK by compound C or PPARγ silencing by small interfering RNA.

RESULTS

TGDZF administration reduced aortic plaque area and lipid accumulation in aortic plaque and hepatocytes, and improved the serum lipid profiles of ApoE-/- mice. Further study revealed that its efficacy was accompanied by an increase in cholesterol efflux rate and the expression of PPARγ, LXRα, and ABCA1 mRNA and protein, as well as the promotion of AMPKα1 phosphorylation. Moreover, similar results were caused by the intervention of TGDZF-containing serum in vitro experiments. Inhibition of AMPK and PPARγ partially blocked the regulatory effect of TGDZF, respectively.

CONCLUSIONS

TGDZF alleviated atherosclerosis and promoted cholesterol efflux from macrophages by activating the AMPK-PPARγ-LXRα-ABCA1 pathway.

Natural products in atherosclerosis therapy by targeting PPARs: a review focusing on lipid metabolism and inflammation

Inflammation and dyslipidemia are critical inducing factors of atherosclerosis. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors and control the expression of multiple genes that are involved in lipid metabolism and inflammatory responses. However, synthesized PPAR agonists exhibit contrary therapeutic effects and various side effects in atherosclerosis therapy. Natural products are structural diversity and have a good safety. Recent studies find that natural herbs and compounds exhibit attractive therapeutic effects on atherosclerosis by alleviating hyperlipidemia and inflammation through modulation of PPARs. Importantly, the preparation of natural products generally causes significantly lower environmental pollution compared to that of synthesized chemical compounds. Therefore, it is interesting to discover novel PPAR modulator and develop alternative strategies for atherosclerosis therapy based on natural herbs and compounds. This article reviews recent findings, mainly from the year of 2020 to present, about the roles of natural herbs and compounds in regulation of PPARs and their therapeutic effects on atherosclerosis. This article provides alternative strategies and theoretical basis for atherosclerosis therapy using natural herbs and compounds by targeting PPARs, and offers valuable information for researchers that are interested in developing novel PPAR modulators.

Recent advances of traditional Chinese medicine for the prevention and treatment of atherosclerosis

ETHNOPHARMACOLOGICAL RELEVANCE

Atherosclerosis (AS) is a common systemic disease with increasing morbidity and mortality worldwide. Traditional Chinese medicine (TCM) with characteristics of multiple pathways and targets, presents advantages in the diagnosis and treatment of atherosclerosis.

AIM OF THE STUDY

With the modernization of TCM, the active ingredients and molecular mechanisms of TCM for AS treatment have been gradually revealed. Therefore, it is necessary to examine the existing studies on TCM therapies aimed at regulating AS over the past two decades.

MATERIALS AND METHODS

Using "atherosclerosis" and "Traditional Chinese medicine" as keywords, all relevant TCM literature published in the last 10 years was collected from electronic databases (such as Elsevier, Springer, PubMed, CNKI, and Web of Science), books and papers until March 2022, and the critical information was statistically analyzed.

RESULTS

In this review, we highlighted extracts of 8 single herbs, a total of 41 single active ingredients, 20 TCM formulae, and 25 patented drugs, which were described with chemical structure, source, model, efficacy and potential mechanism.

CONCLUSION

We summarized the cytopathological basis for the development of atherosclerosis involving vascular endothelial cells, macrophages and vascular smooth muscle cells, and categorically elaborated the medicinal TCM used for AS, all of which provide the current evidence on the better management of atherosclerosis by TCM.

Role of ABCA1 in Cardiovascular Disease

Cholesterol homeostasis plays a significant role in cardiovascular disease. Previous studies have indicated that ATP-binding cassette transporter A1 (ABCA1) is one of the most important proteins that maintains cholesterol homeostasis. ABCA1 mediates nascent high-density lipoprotein biogenesis. Upon binding with apolipoprotein A-I, ABCA1 facilitates the efflux of excess intracellular cholesterol and phospholipids and controls the rate-limiting step of reverse cholesterol transport. In addition, ABCA1 interacts with the apolipoprotein receptor and suppresses inflammation through a series of signaling pathways. Thus, ABCA1 may prevent cardiovascular disease by inhibiting inflammation and maintaining lipid homeostasis. Several studies have indicated that post-transcriptional modifications play a critical role in the regulation of ABCA1 transportation and plasma membrane localization, which affects its biological function. Meanwhile, carriers of the loss-of-function ABCA1 gene are often accompanied by decreased expression of ABCA1 and an increased risk of cardiovascular diseases. We summarized the ABCA1 transcription regulation mechanism, mutations, post-translational modifications, and their roles in the development of dyslipidemia, atherosclerosis, ischemia/reperfusion, myocardial infarction, and coronary heart disease.