Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis

The Role of Punicalagin and Its Metabolites in Atherosclerosis and Risk Factors Associated with the Disease

Atherosclerotic cardiovascular disease (ACVD) is the leading cause of death worldwide. Although current therapies, such as statins, have led to a marked reduction in morbidity and mortality from ACVD, they are associated with considerable residual risk for the disease together with various adverse side effects. Natural compounds are generally well-tolerated; a major recent goal has been to harness their full potential in the prevention and treatment of ACVD, either alone or together with existing pharmacotherapies. Punicalagin (PC) is the main polyphenol present in pomegranates and pomegranate juice and demonstrates many beneficial actions, including anti-inflammatory, antioxidant, and anti-atherogenic properties. The objective of this review is to inform on our current understanding of the pathogenesis of ACVD and the potential mechanisms underlying the beneficial actions of PC and its metabolites in the disease, including the attenuation of dyslipidemia, oxidative stress, endothelial cell dysfunction, foam cell formation, and inflammation mediated by cytokines and immune cells together with the regulation of proliferation and migration of vascular smooth muscle cells. Some of the anti-inflammatory and antioxidant properties of PC and its metabolites are due to their strong radical-scavenging activities. PC and its metabolites also inhibit the risk factors of atherosclerosis, including hyperlipidemia, diabetes mellitus, inflammation, hypertension, obesity, and non-alcoholic fatty liver disease. Despite the promising findings that have emerged from numerous in vitro, in vivo, and clinical studies, deeper mechanistic insights and large clinical trials are required to harness the full potential of PC and its metabolites in the prevention and treatment of ACVD.

The relationship between co-exposure to multiple heavy metals and liver damage

BACKGROUND

The impact of heavy metal exposure on human health has attracted widespread attention of researchers, and the impact of heavy metal exposure on liver function has also been confirmed, however, more attention is paid to the impact of single or two heavy metal exposures, and most epidemiological studies focus on heavy metal pollution areas. In this study, rural residents in non-heavy metal-contaminated areas in Northwest China were selected as the research objects to explore the comprehensive effects of co-exposure to multiple heavy metals on the liver, which can provide certain reference and support for related research.

OBJECTIVES

This study used a Bayesian nuclear machine model (BKMR) to evaluate the relationship between exposure to heavy metal mixtures and indicators of liver function in a population in rural Northwest China.

RESULTS

Exposure to higher concentrations of metal mixtures was positively correlated with total bilirubin, direct bilirubin, and aspartate aminotransferase, and negatively correlated with alanine aminotransferase, with Pb contributing the most to indicators of liver function. We also observed a possible interaction of Cd with other heavy metals in the effect of heavy metal mixtures on DB levels.

CONCLUSIONS

Concurrent exposure to higher concentrations of heavy metal mixtures (Cr, Co, Cd, and Pb) in rural China was associated with indicators representing poor liver function, of which the effect of lead on liver function should be focused. More prospective epidemiological studies and animal experiments need to be carried out to determine this relationship and possible mechanism.

Association of 24 h Behavior Rhythm with Non-Alcoholic Fatty Liver Disease among American Adults with Overweight/Obesity

Emerging evidence suggests that in addition to metabolic, genetic and environmental factors, circadian rhythm also plays a role in non-alcoholic fatty liver disease (NAFLD). This study aimed to explore the association of 24 h behavior rhythm (activity-rest and feeding-fasting rhythm) with NAFLD. A total of 4502 adult participants with overweight/obesity from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 were included in the current study. The behavior rhythm indices were calculated and divided into quintiles for logistic regression models. Compared to those in the lowest quintile, participants in the highest quintile of relative amplitude (RA) had a lower risk of NAFLD (OR = 0.71, 95% CI, 0.55-0.91); participants in the highest quintile of the average activity of the least active continuous 5 h period (L5) were associated with a higher risk of NAFLD (OR = 1.35, 95% CI, 1.07-1.71). Additionally, participants in the highest quintile of fasting duration and feeding rhythm score were associated with a lower risk of NAFLD relative to those in the lowest quintile (OR = 0.76, 95% CI, 0.59-0.98 for fasting duration, OR = 0.74, 95% CI, 0.58-0.95 for feeding rhythm score). The associations were stronger among participants with obesity. No significant associations were found in the relationship of other behavior rhythm indices with NAFLD. This study indicated a significant association of 24 h behavior rhythm with NAFLD among American adults with overweight/obesity.

Lycium barbarum Oligosaccharides Alleviate Hepatic Steatosis by Modulating Gut Microbiota in C57BL/6J Mice Fed a High-Fat Diet

High-fat diets (HFD) can promote the development of hepatic steatosis by altering the structure and composition of gut flora. In this study, the potential therapeutic mechanism of Lycium barbarum oligosaccharide (LBO) against hepatic steatosis was investigated by analyzing the changes in the intestinal flora and metabolites in mice. Mice on an HFD were administered LBO by gavage once daily for a continuous period of eight weeks. Compared with the HFD group, the levels of triglyceride (TG), alanine aminotransferase (ALT) in the serum, and hepatic TG were significantly reduced in the LBO group, and liver lipid accumulation was obviously improved. In addition, LBO could regulate the HFD-induced alteration of intestinal flora. The HFD increased the proportion of Barnesiellaceae, Barnesiella, and CHKCI001. LBO increased the proportion of Dubosiella, Eubacterium, and Lactobacillus. LBO also altered the fecal metabolic profile. Significantly different metabolites between LBO and the HFD, such as taurochenodeoxycholate, taurocholate, fluvastatin, and kynurenic acid, were related to the cholesterol metabolism, bile acid metabolism, and tryptophan metabolic pathways. In light of the above, LBO can alleviate HFD-induced NAFLD by modulating the components of the intestinal flora and fecal metabolites.

Rab7a-mTORC1 signaling-mediated cholesterol trafficking from the lysosome to mitochondria ameliorates hepatic lipotoxicity induced by aflatoxin B1 exposure

Aflatoxin B1 (AFB1) is a common contaminant in many foodstuffs and is considered a public health concern worldwide due to its hepatotoxicity caused by lipid metabolism disorders. However, the molecular mechanism underlying AFB1-induced lipotoxicity-dependent liver injury via regulating cholesterol metabolism remains unclear. We established a cholesterol trafficking disorder-mediated hepatic lipotoxicity model with AFB1 mixture exposure in vitro (HepaRG and HepG2 cells, 1.6 μM for 36 h) and in vivo (C57BL/6 mice, 3 mg kg^-1, i.g., every other day for 6 weeks). In vitro, the interaction between lysosomal Niemann-Pick type C1 (NPC1) protein and mitochondrial translocator protein (TSPO) regulated lipotoxicity induced by AFB1 mixture exposure, including lysosomal membrane permeabilization and mitochondria-dependent necroptosis. Moreover, the downregulation of lysosomal Ras-associated protein 7a (Rab7a) enhanced the mammalian target of rapamycin complex 1 (mTORC1)-mediated disorders of cholesterol trafficking from the lysosome to mitochondria. Furthermore, cholesterol trafficking disorder-mediated hepatic lipotoxicity induced by the low-dose level of AFB1 exposure was relieved by genetic or pharmaceutic activation of Rab7a to inhibit mTORC1 in vitro and ex vivo. In vivo, mTORC1 inhibitor (Torin1, 4 mg kg^-1, i.p., every other day for 3 weeks) alleviated the cholesterol trafficking disorder-mediated hepatic lipotoxicity via upregulating the molecular machinery of lysosomes and mitochondria contact mediated by NPC1 and TSPO interaction in the low dose of AFB1 exposure. Altogether, our data suggested a novel mechanism that lysosomal Rab7a-mTORC1 signaling determined the cholesterol trafficking regulated by NPC1-TSPO from the lysosome to mitochondria, which promoted hepatic lipotoxicity via lysosomal quality control and mitochondria-dependent necroptosis signaling pathways in chemical mixture exposure.

Quince extract resists atherosclerosis in rats by down-regulating the EGFR/PI3K/Akt/GSK-3β pathway

We identified the effective components and the underlying mechanisms of Quince (Cydonia oblonga Mill, COM) extract against atherosclerosis. The effective components of COM extract were identified with UHPLC-Q-TOF-MS/MS. Network pharmacology was performed. A rat model of atherosclerosis induced by high-fat emulsion combined with vitamin D₃ was established. The anti-atherosclerosis effect of COM extract was evaluated from various aspects such as blood lipid regulation, anti-oxidative stress, anti-inflammatory response, and vascular protection function. We identified 14 serum components of COM extract using UHPLC-Q-TOF-MS/MS. Through prediction, 573 targets were obtained, among which 224 targets were atherosclerosis specific targets. The key targets included GSK3β, ESR1, EGFR, and HSP90AA1. The key signaling pathway was PI3K-Akt signaling pathway. Pharmacodynamics analysis showed that COM extract reduced the levels of TC, TG, and LDL-C as well as ALT and AST, while increased the level of HDL-C. Mechanistically, COM extract significantly increased serum SOD and GSH-Px activities, but decreased MDA content in atherosclerosis rats, showing antioxidant effects. Meanwhile, COM extract significantly down-regulated the levels of pro-inflammatory factors IL-1β, IL-6, TNF-α and CRP, but up-regulated anti-inflammatory factor IL-10. Additionally, COM extract increased the levels of NO, eNOS, and 6-keto-PGF1α; whereas, decreased the levels of ET-1 and TXB₂. Furthermore, COM extract significantly inhibited the mRNA and protein levels of EGFR, p-PI3K, p-AKT, GSK-3β, Bax, and Caspase-3 as well as the Bax/Bcl-2 ratio. Conclusively, COM extract exerts hypolipidemic, anti-oxidative, anti-inflammatory, anti-thrombotic and vascular endothelium protective effects on atherosclerosis rat model, which may be related to the inhibition of EGFR/PI3K/AKT/GSK-3β signaling pathway.

Dietary cholesterol in alcohol-associated liver disease

There is an increasing prevalence of alcohol-associated liver disease (ALD) worldwide. In addition to excessive alcohol consumption, other nutritional factors have been shown to affect the initiation and progression of ALD. The emerging role of cholesterol in exacerbating ALD has been reported recently and the underlying mechanisms are discussed. In addition, the interplay between dietary cholesterol and alcohol on cholesterol metabolism is reviewed. Furthermore, we highlight the therapeutic potential of cholesterol-lowering drugs in managing the onset and severity of ALD. Finally, we suggest the future mechanistic investigation of the effect of cholesterol on insulin resistance and intestinal inflammation in the exacerbation of alcohol-induced cellular and systemic dysfunction.

CTRP1: A novel player in cardiovascular and metabolic diseases

Cardiovascular diseases (CVDs) are a series of diseases induced by inflammation and lipid metabolism disorders, among others. Metabolic diseases can cause inflammation and abnormal lipid metabolism. C1q/TNF-related proteins 1 (CTRP1) is a paralog of adiponectin that belongs to the CTRP subfamily. CTRP1 is expressed and secreted in adipocytes, macrophages, cardiomyocytes, and other cells. It promotes lipid and glucose metabolism but has bidirectional effects on the regulation of inflammation. Inflammation can also inversely stimulate CTRP1 production. A vicious circle may exist between the two. This article introduces CTRP1 from the structure, expression, and different roles of CTRP1 in CVDs and metabolic diseases, to summarize the role of CTRP1 pleiotropy. Moreover, the proteins which may interact with CTRP1 are predicted through GeneCards and STRING, speculating their effects, to provide new ideas for the study of CTRP1.

Protective Effects of Hydroxyphenyl Propionic Acids on Lipid Metabolism and Gut Microbiota in Mice Fed a High-Fat Diet

Gut microbiota imbalances lead to the pathogenesis of non-alcoholic fatty liver disease (NAFLD), which is primarily accompanied by hepatic steatosis. Hydroxyphenyl propionic acids (HPP) have shown great potential in inhibiting lipid accumulation but their protective effects concerning NAFLD and intestinal microbiota have remained unclear. In this paper, we investigated the efficacies of 3-HPP and 4-HPP on hepatic steatosis and gut flora in mice fed a high-fat diet (HFD). We found that 3-HPP and 4-HPP administration decreased body weight and liver index, ameliorated dyslipidemia, and alleviated hepatic steatosis. Furthermore, 3-HPP and 4-HPP enhanced the multiformity of gut microbiota; improved the relative abundance of GCA-900066575, unidentified_Lachnospiraceae, and Lachnospiraceae_UCG-006 at genus level; increased concentration of acetic acid, propionic acid and butanoic acid in faeces; and reduced systemic endotoxin levels in NAFLD mice. Moreover, 4-HPP upregulated the relative abundance of genera Rikenella and downregulated the relative abundance of Faecalibaculum. Furthermore, 3-HPP and 4-HPP regulated lipid metabolism and ameliorated gut dysbiosis in NAFLD mice and 4-HPP was more effective than 3-HPP.

Analysis of the Genetic Relationship between Atherosclerosis and Non-Alcoholic Fatty Liver Disease through Biological Interaction Networks

Non-alcoholic fatty liver disease (NAFLD) seems to have some molecular links with atherosclerosis (ATH); however, the molecular pathways which connect both pathologies remain unexplored to date. The identification of common factors is of great interest to explore some therapeutic strategies to improve the outcomes for those affected patients. Differentially expressed genes (DEGs) for NAFLD and ATH were extracted from the GSE89632 and GSE100927 datasets, and common up- and downregulated DEGs were identified. Subsequently, a protein-protein interaction (PPI) network based on the common DEGs was performed. Functional modules were identified, and the hub genes were extracted. Then, a Gene Ontology (GO) and pathway analysis of common DEGs was performed. DEGs analysis in NAFLD and ATH showed 21 genes that were regulated similarly in both pathologies. The common DEGs with high centrality scores were ADAMTS1 and CEBPA which appeared to be down- and up-regulated in both disorders, respectively. For the analysis of functional modules, two modules were identified. The first one was oriented to post-translational protein modification, where ADAMTS1 and ADAMTS4 were identified, and the second one mainly related to the immune response, where CSF3 was identified. These factors could be key proteins with an important role in the NAFLD/ATH axis.

Hepatic Nampt Deficiency Aggravates Dyslipidemia and Fatty Liver in High Fat Diet Fed Mice

Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme in the salvage pathway of nicotinamide adenine dinucleotide (NAD) biosynthesis. Thus far, hepatic Nampt has not been extensively explored in terms of its effects on serum lipid stability and liver lipids metabolism. In this study, hepatocyte-specific Nampt knockout (HC-Nampt^-/-) mice were generated by Cre/loxP system. Nampt mRNA expression was reduced in the liver, but not in other tissues, in HC-Nampt^-/- mice compared with wild-type (WT) mice. Hepatic Nampt deficiency had no effect on body weight and fasting blood glucose, and it did not induce atherosclerosis in mice under both normal chow diet (NCD) and high fat diet (HFD). At baseline state under NCD, hepatic Nampt deficiency also did not affect liver weight, liver function index, including alanine aminotransferase, aspartate aminotransferase, albumin and alkaline phosphatase, and serum levels of lipids, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and non-esterified fatty acids (NEFA). However, under HFD, deficiency of hepatic Nampt resulted in increased liver weight, liver function index, and serum levels of TG, TC, HDL-C, and NEFA. Meanwhile, histopathological examination showed increased fat accumulation and fibrosis in the liver of HC-Nampt^-/- mice compared with WT mice. Taken together, our results show that hepatic Nampt deficiency aggravates dyslipidemia and liver damage in HFD fed mice. Hepatocyte Nampt can be a protective target against dyslipidemia and fatty liver.

Therapeutic Potential of Resveratrol and Atorvastatin Following High-Fat Diet Uptake-Induced Nonalcoholic Fatty Liver Disease by Targeting Genes Involved in Cholesterol Metabolism and miR33

The present study was designed to evaluate the effects of resveratrol, atorvastatin, and a combination of resveratrol and atorvastatin on expression levels of genes involved in the cholesterol metabolic pathway in the fatty liver of C57/BL6 mice. A high-fat diet was used to induce fatty liver in C57/BL6 mice treated with resveratrol, atorvastatin, or a combination of resveratrol and atorvastatin. Pathological and biochemical studies were performed. In addition, hepatic gene expressions of ATP-binding cassette transporter A1 (ABCA1), ABCG1, liver X receptor (LXR)α, scavenger receptor B1 (SR-B1), low-density lipoprotein receptor (LDLR), and miR33 were evaluated by the real-time PCR method, and the Western blot method was used to measure the ABCA1, ABCG1, and LXRα protein levels. Resveratrol and atorvastatin reduced fat accumulation in the liver of mice with fatty liver, and this effect was correlated with decreased blood glucose levels, triglyceride, cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol blood levels compared with the positive control (PC) group. In contrast to the animals of the PC group, fatty liver groups that received resveratrol and atorvastatin had a significant effect on the mRNA levels of the ABCA1, ABCG1, LXRα, SR-B1, LDLR, and miR33 genes. Moreover, resveratrol and atorvastatin administration elevated ABCA1 and ABCG1 and reduced LXRα protein expression. Obtained results showed that resveratrol and atorvastatin combination therapy can improve nonalcoholic fatty liver disease by targeting genes involved in cholesterol metabolism and miR33.

Beneficial Effects of Moderate Hepatic Activin A Expression on Metabolic Pathways, Inflammation, and Atherosclerosis

BACKGROUND

Atherosclerosis is an inflammatory vascular disease marked by hyperlipidemia and hematopoietic stem cell expansion. Activin A, a member of the Activin/GDF/TGFβ/BMP (growth/differentiation factor/transforming growth factor beta/bone morphogenetic protein) family is broadly expressed and increases in human atherosclerosis, but its functional effects in vivo in this context remain unclear.

METHODS

We studied LDLR^-/- mice on a Western diet for 12 weeks and used adeno-associated viral vectors with a liver-specific TBG (thyroxine-binding globulin) promoter to express Activin A or GFP (control). Atherosclerotic lesions were analyzed by oil red staining. Blood lipid profiling was performed by high-performance liquid chromatography, and immune cells were evaluated by flow cytometry. Liver RNA-sequencing was performed to explore the underlying mechanisms.

RESULTS

Activin A expression decreased in both livers and aortae from LDLR^-/- mice fed a Western diet compared with standard laboratory diet. Adenoassociated virus-TBG-Activin A increased Activin A hepatic expression ≈10-fold at 12 weeks; P<0.001) and circulating Activin A levels ≈2000 pg/ml versus ≈50 pg/ml; P<0.001, compared with controls). Hepatic Activin A expression decreased plasma total and LDL (low-density lipoprotein) cholesterol ≈60% and ≈40%, respectively), reduced inflammatory cells in aortae and proliferating hematopoietic stem cells in bone marrow, and reduced atherosclerotic lesion and necrotic core area in aortae. Activin A also attenuated liver steatosis and expression of the lipogenesis genes, Srebp1 and Srebp2. RNA sequencing revealed Activin A not only blocked expression of genes involved in hepatic de novo lipogenesis but also fatty acid uptake and liver inflammation. In addition, Activin A expressed in the liver also reduced white fat tissue accumulation, decreased adipocyte size, and improved glucose tolerance.

CONCLUSIONS

Our studies reveal hepatic Activin A expression reduces inflammation, hematopoietic stem cell expansion, liver steatosis, circulating cholesterol, and fat accumulation, which likely all contribute to the observed protection against atherosclerosis. The reduced Activin A observed in LDLR^-/- mice on a Western diet seems maladaptive and deleterious for atherogenesis.

Development of the Rabbit NASH Model Resembling Human NASH and Atherosclerosis

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease which may progress into liver fibrosis and cancer. Since NASH patients have a high prevalence of atherosclerosis and ensuing cardiovascular diseases, simultaneous management of NASH and atherosclerosis is required. Currently, rodents are the most common animal models for NASH and accompanying liver fibrosis, but there are great differences in lipoprotein profiles between rodents and humans, which makes it difficult to reproduce the pathology of NASH patients with atherosclerosis. Rabbits can be a promising candidate for assessing NASH and atherosclerosis because lipoprotein metabolism is more similar to humans compared with rodents. To develop the NASH model using rabbits, we treated the Japanese White rabbit with a newly developed high-fat high-cholesterol diet (HFHCD) containing palm oil 7.5%, cholesterol 0.5%, and ferrous citrate 0.5% for 16 weeks. HFHCD-fed rabbits exhibited NASH at 8 weeks after commencing the treatment and developed advanced fibrosis by the 14th week of treatment. In addition to hypercholesterolemia, atherosclerotic lesion developed in the aorta after 8 weeks. Therefore, this rabbit NASH model might contribute to exploring the concurrent treatment options for human NASH and atherosclerosis.

Integrative multi-omics unravels the amelioration effects of Zanthoxylum bungeanum Maxim. on non-alcoholic fatty liver disease

BACKGROUND

The effect of Zanthoxylum bungeanum Maxim. (ZBM) on anti-obesity, lipid-lowering and liver protection has been identified, but the effect on the development of NAFLD induced by high-fat diet remains unclear.

PURPOSE

To evaluate the alleviation effect of ZBM on NAFLD in vivo and explore the mechanisms by analyzing the liver transcriptome, microbiota and fecal metabolites.

METHODS

NAFLD model was induced in C57BL/6J mice by feeding with high-fat diet (HFD). The potential mechanism of ZBM in improving NAFLD was studied by liver transcriptome analysis, real-time PCR, immunofluorescence, 16s rRNA sequencing and non-targeted metabonomics.

RESULTS

ZBM has alleviation effects on HFD-induced NAFLD. The liver transcriptome, real-time PCR and immunofluorescence analysis showed that ZBM could efficiently regulate fatty acid and cholesterol metabolism. The 16S rRNA sequencing and LC-MS based metabonomic demonstrated that ZBM could rebalance gut microbiota dysbiosis and regulate metabolic profiles in HFD-induced NAFLD mice. Spearman correlation analysis revealed a strong correlation between gut microbiota and biochemical, pathological indexes and differential metabolic biomarkers.

CONCLUSION

ZBM ameliorates HFD-induced NAFLD by regulating fatty acid and cholesterol metabolism, gut microbiota and metabolic profile.

Emerging trends and hotspots in metabolic dysfunction-associated fatty liver disease (MAFLD) research from 2012 to 2021: A bibliometric analysis

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become the most common chronic liver disease. MAFLD is a major risk factor for end-stage liver disease including cirrhosis and primary liver cancer. The pathogenesis of MAFLD is complex and has not yet been clarified. To the best of our knowledge, few studies have conducted quantitative bibliometric analysis to evaluate published MAFLD research. In this study, we conducted a comprehensive analysis of MAFLD publications over the past decade to summarize the current research hotspots and predict future research directions in this field.

METHODS

Articles into MAFLD published from 2012 to 2021 were identified from the Science Citation Index-Expanded of Web of Science Core Collection. CiteSpace software, VOSviewer, the "bibliometrix" R package, and the Online Analysis Platform of Literature Metrology were used to analyze the current publication trends and hotspots.

RESULTS

We retrieved 13959 English articles about MAFLD published from 2012 to 2021. Primary sites of publication were dominated by the United States until 2014, when China became the source of most published MAFLD-related research papers. The United States was found to be the most engaged country in international cooperative efforts. Shanghai Jiao Tong University was the most productive institution. Loomba R was the most productive author with 123 articles. The co-cited keyword cluster tag showed ten main clusters: #0 liver fibrosis, #1 hemoglobin, #2 metabolic associated fatty liver disease, #3 egcg, #4 myocardial infarction, #5 heart disease, #6 pnpla3, #7 hepatocellular carcinoma, #8 noninvasive marker, and #9 children. Keyword burst analysis showed that gut microbiota was the highest-intensity research hotspot.

CONCLUSION

In the past decade, the number of publications on MAFLD increased dramatically, especially in the last three years. Gut microbiota became an important research direction for etiological and therapeutic investigations into MAFLD. Insulin resistance was also a key factor in studying the development of MAFLD in recent years. Liver fibrosis was an important focus of disease development. This study provides systematic information, helps guide future research, and helps to identify mechanisms and new treatment methods for MAFLD.

Alleviation Effects of Microbial Metabolites from Resveratrol on Non-Alcoholic Fatty Liver Disease

Resveratrol (RSV), a polyphenolic stilbene, has been widely studied for its protective effects against non-alcoholic fatty liver disease (NAFLD) by modulating intestinal microbiota. The microbial metabolites after RSV supplement would contribute to the bioeffects of RSV, while their impacts on NAFLD were unclear. Therefore, this study aimed to investigate the beneficial effects of the main microbial metabolites from RSV on lipid metabolism by combining in vitro and in vivo models. The mice were fed a high-fat diet and injected with RSV, 3-hydroxyphenyl propionic acid (3-HPP), and 4-HPP for 13 weeks (n = 6). Body weight, serum parameters, histological analysis, and gene expression involved in lipid metabolism were quantified. Our results suggested that 100 μM of 3-HPP and 4-HPP inhibited lipid accumulation more significantly than parent RSV in an oleic acid-induced HepG2 cell line. Furthermore, 3-HPP, 4-HPP, and RSV effectively reduced liver weight and body weight, improved hepatic steatosis, and alleviated systemic inflammation in NAFLD mice. In addition, the results of quantitative real-time PCR showed that 3-HPP and 4-HPP altered the expression of cholesterol influx and efflux genes to a stronger extent than RSV. These results indicate that 3-HPP and 4-HPP are effective in regulating hepatic lipid metabolism.

Utility of Human Relevant Preclinical Animal Models in Navigating NAFLD to MAFLD Paradigm

Fatty liver disease is an emerging contributor to disease burden worldwide. The past decades of work established the heterogeneous nature of non-alcoholic fatty liver disease (NAFLD) etiology and systemic contributions to the pathogenesis of the disease. This called for the proposal of a redefinition in 2020 to that of metabolic dysfunction-associated fatty liver disease (MAFLD) to better reflect the current understanding of the disease. To date, several clinical cohort studies comparing NAFLD and MAFLD hint at the relevancy of the new nomenclature in enriching for patients with more severe hepatic injury and extrahepatic comorbidities. However, the underlying systemic pathogenesis is still not fully understood. Preclinical animal models have been imperative in elucidating key biological mechanisms in various contexts, including intrahepatic disease progression, interorgan crosstalk and systemic dysregulation. Furthermore, they are integral in developing novel therapeutics against MAFLD. However, substantial contextual variabilities exist across different models due to the lack of standardization in several aspects. As such, it is crucial to understand the strengths and weaknesses of existing models to better align them to the human condition. In this review, we consolidate the implications arising from the change in nomenclature and summarize MAFLD pathogenesis. Subsequently, we provide an updated evaluation of existing MAFLD preclinical models in alignment with the new definitions and perspectives to improve their translational relevance.

NUDT7 regulates total hepatic CoA levels and the composition of the intestinal bile acid pool in male mice fed a Western diet

Nudix hydrolase 7 (NUDT7) is an enzyme that hydrolyzes CoA species, is highly expressed in the liver, and resides in the peroxisomes. Peroxisomes are organelles where the preferential oxidation of dicarboxylic fatty acids occurs and where the hepatic synthesis of the primary bile acids cholic acid and chenodeoxycholic acid is completed. We previously showed that liver-specific overexpression of NUDT7 affects peroxisomal lipid metabolism but does not prevent the increase in total liver CoA levels that occurs during fasting. We generated Nudt7^-/- mice to further characterize the role that peroxisomal (acyl-)CoA degradation plays in the modulation of the size and composition of the acyl-CoA pool and in the regulation of hepatic lipid metabolism. Here, we show that deletion of Nudt7 alters the composition of the hepatic acyl-CoA pool in mice fed a low-fat diet, but only in males fed a Western diet does the lack of NUDT7 activity increase total liver CoA levels. This effect is driven by the male-specific accumulation of medium-chain dicarboxylic acyl-CoAs, which are produced from the β-oxidation of dicarboxylic fatty acids. We also show that, under conditions of elevated synthesis of chenodeoxycholic acid derivatives, Nudt7 deletion promotes the production of tauromuricholic acid, decreasing the hydrophobicity index of the intestinal bile acid pool and increasing fecal cholesterol excretion in male mice. These findings reveal that NUDT7-mediated hydrolysis of acyl-CoA pathway intermediates in liver peroxisomes contributes to the regulation of dicarboxylic fatty acid metabolism and the composition of the bile acid pool.

Lactobacillus reuteri MJM60668 Prevent Progression of Non-Alcoholic Fatty Liver Disease through Anti-Adipogenesis and Anti-inflammatory Pathway

Non-alcoholic fatty liver disease (NALFD) is a disease characterized by liver steatosis. The liver is a key organ involved in the metabolism of fat, protein, and carbohydrate, enzyme activation, and storage of glycogen, which is closely related to the intestine by the bidirectional relation of the gut-liver axis. Abnormal intestinal microbiota composition can affect energy metabolism and lipogenesis. In this experiment, we investigated the beneficial effect of Lactobacillus reuteri MJM60668 on lipid metabolism and lipogenesis. C57BL/6 mice were fed a high-fat diet (HFD) and orally administrated with MJM60668. Our results showed that mice treated with MJM60668 significantly decreased liver weight and liver/body weight ratio, without affecting food intake. Serum levels of ALT, AST, TG, TCHO, and IL-1β in mice fed with MJM60668 were decreased compared to the HFD group. Investigation of gene and protein expression on the lipogenesis and lipid metabolism showed that the expression of ACC, FAS, and SREBP was decreased, and PPARα and CPT was increased. Furthermore, an increase of adiponectin in serum was shown in our experiment. Moreover, serum IL-1β level was also significantly decreased in the treated mice. These results suggested that MJM60668 can strongly inhibit lipogenesis, enhance fatty acid oxidation, and suppress inflammation. Additionally, supplementation of MJM60668 increased the proportion of Akkermansiaceae and Lachnospiracea, confirming a potential improvement of gut microbiota, which is related to mucus barrier and decrease of triglycerides levels.

G protein-coupled receptor 35 attenuates nonalcoholic steatohepatitis by reprogramming cholesterol homeostasis in hepatocytes

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Fat accumulation "sensitizes" the liver to insult and leads to nonalcoholic steatohepatitis (NASH). G protein-coupled receptor 35 (GPR35) is involved in metabolic stresses, but its role in NAFLD is unknown. We report that hepatocyte GPR35 mitigates NASH by regulating hepatic cholesterol homeostasis. Specifically, we found that GPR35 overexpression in hepatocytes protected against high-fat/cholesterol/fructose (HFCF) diet-induced steatohepatitis, whereas loss of GPR35 had the opposite effect. Administration of the GPR35 agonist kynurenic acid (Kyna) suppressed HFCF diet-induced steatohepatitis in mice. Kyna/GPR35 induced expression of StAR-related lipid transfer protein 4 (STARD4) through the ERK1/2 signaling pathway, ultimately resulting in hepatic cholesterol esterification and bile acid synthesis (BAS). The overexpression of STARD4 increased the expression of the BAS rate-limiting enzymes cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and CYP8B1, promoting the conversion of cholesterol to bile acid. The protective effect induced by GPR35 overexpression in hepatocytes disappeared in hepatocyte STARD4-knockdown mice. STARD4 overexpression in hepatocytes reversed the aggravation of HFCF diet-induced steatohepatitis caused by the loss of GPR35 expression in hepatocytes in mice. Our findings indicate that the GPR35-STARD4 axis is a promising therapeutic target for NAFLD.

The role of cholesterol in invasion and growth of malaria parasites

Malaria parasites are unicellular eukaryotic pathogens that develop through a complex lifecycle involving two hosts, an anopheline mosquito and a vertebrate host. Throughout this lifecycle, the parasite encounters widely differing conditions and survives in distinct ways, from an intracellular lifestyle in the vertebrate host to exclusively extracellular stages in the mosquito. Although the parasite relies on cholesterol for its growth, the parasite has an ambiguous relationship with cholesterol: cholesterol is required for invasion of host cells by the parasite, including hepatocytes and erythrocytes, and for the development of the parasites in those cells. However, the parasite is unable to produce cholesterol itself and appears to remove cholesterol actively from its own plasma membrane, thereby setting up a cholesterol gradient inside the infected host erythrocyte. Overall a picture emerges in which the parasite relies on host cholesterol and carefully controls its transport. Here, we describe the role of cholesterol at the different lifecycle stages of the parasites.

PLK1 promotes cholesterol efflux and alleviates atherosclerosis by up-regulating ABCA1 and ABCG1 expression via the AMPK/PPARγ/LXRα pathway

Polo-like kinase 1 (PLK1) is a serine/threonine kinase involving lipid metabolism and cardiovascular disease. However, its role in atherogenesis has yet to be determined. The aim of this study was to observe the impact of PLK1 on macrophage lipid accumulation and atherosclerosis development and to explore the underlying mechanisms. We found a significant reduction of PLK1 expression in lipid-loaded macrophages and atherosclerosis model mice. Lentivirus-mediated overexpression of PLK1 promoted cholesterol efflux and inhibited lipid accumulation in THP-1 macrophage-derived foam cells. Mechanistic analysis revealed that PLK1 stimulated the phosphorylation of AMP-activated protein kinase (AMPK), leading to activation of the peroxisome proliferator-activated receptor γ (PPARγ)/liver X receptor α (LXRα) pathway and up-regulation of ATP binding cassette transporter A1 (ABCA1) and ABCG1 expression. Injection of lentiviral vector expressing PLK1 increased reverse cholesterol transport, improved plasma lipid profiles and decreased atherosclerotic lesion area in apoE-deficient mice fed a Western diet. PLK1 overexpression also facilitated AMPK and HSL phosphorylation and enhanced the expression of PPARγ, LXRα, ABCA1, ABCG1 and LPL in the aorta. In summary, these data suggest that PLK1 inhibits macrophage lipid accumulation and mitigates atherosclerosis by promoting ABCA1- and ABCG1-dependent cholesterol efflux via the AMPK/PPARγ/LXRα pathway.

Regulation of cholesterol homeostasis in health and diseases: from mechanisms to targeted therapeutics

Disturbed cholesterol homeostasis plays critical roles in the development of multiple diseases, such as cardiovascular diseases (CVD), neurodegenerative diseases and cancers, particularly the CVD in which the accumulation of lipids (mainly the cholesteryl esters) within macrophage/foam cells underneath the endothelial layer drives the formation of atherosclerotic lesions eventually. More and more studies have shown that lowering cholesterol level, especially low-density lipoprotein cholesterol level, protects cardiovascular system and prevents cardiovascular events effectively. Maintaining cholesterol homeostasis is determined by cholesterol biosynthesis, uptake, efflux, transport, storage, utilization, and/or excretion. All the processes should be precisely controlled by the multiple regulatory pathways. Based on the regulation of cholesterol homeostasis, many interventions have been developed to lower cholesterol by inhibiting cholesterol biosynthesis and uptake or enhancing cholesterol utilization and excretion. Herein, we summarize the historical review and research events, the current understandings of the molecular pathways playing key roles in regulating cholesterol homeostasis, and the cholesterol-lowering interventions in clinics or in preclinical studies as well as new cholesterol-lowering targets and their clinical advances. More importantly, we review and discuss the benefits of those interventions for the treatment of multiple diseases including atherosclerotic cardiovascular diseases, obesity, diabetes, nonalcoholic fatty liver disease, cancer, neurodegenerative diseases, osteoporosis and virus infection.

Epigenetic Control of Vascular Smooth Muscle Cell Function in Atherosclerosis: A Role for DNA Methylation

Atherosclerosis is a complex vascular inflammatory disease in which multiple cell types are involved, including vascular smooth muscle cells (VSMCs). In response to vascular injury and inflammatory stimuli, VSMCs undergo a "phenotypic switching" characterized by extracellular matrix secretion, loss of contractility, and abnormal proliferation and migration, which play a key role in the progression of atherosclerosis. DNA methylation modification is an important epigenetic mechanism that plays an important role in atherosclerosis. Studies investigating abnormal DNA methylation in patients with atherosclerosis have determined a specific DNA methylation profile, and proposed multiple pathways and genes involved in the etiopathogenesis of atherosclerosis. Recent studies have also revealed that DNA methylation modification controls VSMC function by regulating gene expression involved in atherosclerosis. In this review, we summarize the recent advances regarding the epigenetic control of VSMC function by DNA methylation in atherosclerosis and provide insights into the development of VSMC-centered therapeutic strategies.

Beneficial Effects of Theaflavins on Metabolic Syndrome: From Molecular Evidence to Gut Microbiome

In recent years, many natural foods and herbs rich in phytochemicals have been proposed as health supplements for patients with metabolic syndrome (MetS). Theaflavins (TFs) are a polyphenol hydroxyl substance with the structure of diphenol ketone, and they have the potential to prevent and treat a wide range of MetS. However, the stability and bioavailability of TFs are poor. TFs have the marvelous ability to alleviate MetS through antiobesity and lipid-lowering (AMPK-FoxO3A-MnSOD, PPAR, AMPK, PI3K/Akt), hypoglycemic (IRS-1/Akt/GLUT4, Ca2+/CaMKK2-AMPK, SGLT1), and uric-acid-lowering (XO, GLUT9, OAT) effects, and the modulation of the gut microbiota (increasing beneficial gut microbiota such as Akkermansia and Prevotella). This paper summarizes and updates the bioavailability of TFs, and the available signaling pathways and molecular evidence on the functionalities of TFs against metabolic abnormalities in vitro and in vivo, representing a promising opportunity to prevent MetS in the future with the utilization of TFs.

GOS Ameliorates Nonalcoholic Fatty Liver Disease Induced by High Fat and High Sugar Diet through Lipid Metabolism and Intestinal Microbes

The treatment of nonalcoholic fatty liver disease (NAFLD) remains very challenging. This study investigated the therapeutic effect of galactose oligosaccharide (GOS), an important prebiotic, on NAFLD through in vivo and in vitro experiments and preliminarily explored the mechanism by which GOS improves liver lipid metabolism and inflammation through liver and intestinal microbiological analysis. The results of mouse liver lipidomics showed that GOS could promote body thermogenesis in mice with high-fat and high-sugar diet (HFHSD)-induced NAFLD, regulate lipolysis in liver fat cells, and accelerate glycine and cholesterol metabolism. GOS dose-dependently reduced the contents of total cholesterol (TC) and triglyceride (TG) in cells and reduced the accumulation of lipid droplets in cells. GOS also reduced the Firmicutes/Bacteroidetes ratio and altered the composition of the intestinal microbiota in mice fed a HFHSD. GOS can improve liver lipid metabolism and intestinal structure of NAFLD. These results provide a theoretical and experimental basis supporting the use of GOS as a health food with anti-NAFLD functions.

Sterol carrier protein 2 in lipid metabolism and non-alcoholic fatty liver disease: Pathophysiology, molecular biology, and potential clinical implications

Non-alcoholic fatty liver disease (NAFLD) is considered as the most common chronic liver disease and has become a rapidly global public health problem. Sterol carrier protein 2 (SCP-2), also called non-specific lipid-transfer protein, is predominantly expressed by the liver. SCP-2 plays a key role in intracellular lipid transport and metabolism. SCP-2 has been closely implicated in the development of NAFLD-related metabolic disorders, such as obesity, atherosclerosis, Type 2 diabetes mellitus (T2DM), and gallstones. Recent studies indicate that SCP-2 plays a beneficial role in NAFLD by regulating cholesterol-, endocannabinoid-, and fatty acid-related aspects of lipid metabolism. Hence, in this paper, we summarize the latest findings about the roles of SCP-2 in hepatic steatosis and further describe its molecular function in the pathogenesis of NAFLD.

PREX1 depletion ameliorates high-fat diet-induced non-alcoholic fatty liver disease in mice and mitigates palmitic acid-induced hepatocellular injury via suppressing the NF-κB signaling pathway

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver diseases worldwide. Oxidative stress has been considered a key factor in the pathogenesis of NAFLD. Phosphatidylinositol (3,4,5)-trisphosphate-dependent Rac exchanger 1 (PREX1), a guanine nucleotide exchange factor for Rac, has been associated with inflammation and oxidative stress. This study aimed to investigate the biological function of PREX1 in the progression of NAFLD. Male C57BL/6 mice were fed a high-fat diet for 12 weeks to induce NAFLD in vivo. Adeno-associated virus type 8-mediated liver-specific PREX1 depletion was employed to investigate the role of PREX1 in the progression of high-fat diet-induced NAFLD. Murine hepatocyte cell line AML-12 was stimulated with palmitic acid for 24 h to induce steatosis in vitro. PREX1 depletion was carried out by transfection with PREX1 small interfering RNA. Results showed that PREX1 depletion exerted protective effects against lipid accumulation, oxidative stress and inflammation and inhibited activation of the nuclear factor-κB (NF-κB) signaling pathway in vivo and in vitro. Subsequently, NF-κB inhibitor BAY11-7082 was applied to investigate the role of the NF-κB signaling pathway in the protective effect of PREX1 inhibition against NAFLD. We confirmed that PREX1 inhibition mitigated palmitic acid-induced hepatocellular inflammation mainly via the NF-κB signaling pathway and lipid accumulation and oxidative stress at least partly via the NF-κB signaling pathway. This study highlights the biological function of PREX1 in the pathogenesis of NAFLD.

Ficus hirta Vahl. Ameliorates Nonalcoholic Fatty Liver Disease through Regulating Lipid Metabolism and Gut Microbiota

Nonalcoholic fatty liver disease (NAFLD) has gradually become one of the most serious liver diseases threatening human health in the world. Currently, Chinese herbal medicine is a potentially important treatment option for NAFLD, and the development of effective Chinese herbal medicine has a good prospect. Previous studies have suggested that Ficus hirta Vahl. (FV) has various protective effects on the liver. In this study, we investigated the therapeutic outcomes of FV treatment for the liver disease and its underlying mechanism using HepG2 cell lines induced by palmitate (PA) and mouse model fed with high-fat diet (HFD). FV mainly exerts pharmacological effects by mediating lipid metabolism and inflammation. During the lipid metabolism regulation process, CD36, SREBP-1, SCD1, PPAR γ, ACOX1, and CPT1α are the key factors related to the healing effects of FV on NAFLD. During the inflammation process, the downregulation of IL-6, IL-1β, and TNF-α is involved in alleviation of NAFLD. Furthermore, CD36 overexpression promotes lipid abnormal metabolism and inflammation in PA-induced HepG2 cells, while CD36 knockdown and FV supplementation reverse these responses. In addition, FV also modulates gut microbiota composition, such as Allobaculum, Faecalibaculum, and Butyricicoccus in HFD-fed mice. In summary, our findings demonstrated that FV exerted a beneficial preventive and therapeutic effect on NAFLD by improving lipid metabolism and inflammation as well as regulating the structure of gut microbiota, and therefore, FV may be a candidate for the treatment of NAFLD.

From Dietary Cholesterol to Blood Cholesterol, Physiological Lipid Fluxes, and Cholesterol Homeostasis

Dietary cholesterol (C) is a major contributor to the endogenous C pool, and it affects the serum concentration of total C, particularly the low-density lipoprotein cholesterol (LDL-C). A high serum concentration of LDL-C is associated with an increased risk for atherosclerosis and cardiovascular diseases. This concentration is dependent on hepatic C metabolism creating a balance between C input (absorption and synthesis) and C elimination (conversion to bile acids and fecal excretion). The daily C absorption rate is determined by dietary C intake, biliary C secretion, direct trans-intestinal C excretion (TICE), and the fractional C absorption rate. Hepatic C metabolism coordinates C fluxes entering the liver via chylomicron remnants (CMR), LDL, high-density lipoproteins (HDL), hepatic C synthesis, and those leaving the liver via very low-density lipoproteins (VLDL), biliary secretion, and bile acid synthesis. The knowns and the unknowns of this C homeostasis are discussed.

Characterization and Roles of Membrane Lipids in Fatty Liver Disease

Obesity has reached global epidemic proportions and it affects the development of insulin resistance, type 2 diabetes, fatty liver disease and other metabolic diseases. Membrane lipids are important structural and signaling components of the cell membrane. Recent studies highlight their importance in lipid homeostasis and are implicated in the pathogenesis of fatty liver disease. Here, we discuss the numerous membrane lipid species and their metabolites including, phospholipids, sphingolipids and cholesterol, and how dysregulation of their composition and physiology contribute to the development of fatty liver disease. The development of new genetic and pharmacological mouse models has shed light on the role of lipid species on various mechanisms/pathways; these lipids impact many aspects of the pathophysiology of fatty liver disease and could potentially be targeted for the treatment of fatty liver disease.

CTRP15 promotes macrophage cholesterol efflux and attenuates atherosclerosis by increasing the expression of ABCA1

C1q tumor necrosis factor-related protein 15 (CTRP15), a newly identified myokine, is closely implicated in cardiovascular disease. However, the role of CTRP15 in atherosclerosis is still unclear. This study aims to determine the role of CTRP15 in atherosclerosis and explore the underlying mechanisms. Our findings revealed that lentivirus-mediated CTRP15 overexpression significantly decreased atherosclerotic plaque lesions and increased reverse cholesterol transport (RCT) efficiency and circulating HDL-C levels in apolipoprotein E-deficient (apoE^-/-) mice. Consistently, in vitro, overexpression of CTRP15 also inhibited intracellular lipid accumulation and promoted cholesterol efflux from macrophages. Mechanistically, CTRP15 decreased the expression of miR-101-3p by upregulating T-cadherin, thereby facilitating ABCA1 expression and cholesterol efflux. In summary, these data indicate that CTRP15 inhibits the development of atherosclerosis by enhancing RCT efficiency and increasing plasma HDL-C levels via the T-cadherin/miR-101-3p/ABCA1 pathway. Targeting CTRP15 may serve as a novel and promising therapeutic strategy for atherosclerotic cardiovascular diseases.

C1q tumor necrosis factor-related protein 1: a promising therapeutic target for atherosclerosis

ABSTRACT

Atherosclerosis serves as the pathological basis of most cardiovascular and cerebrovascular diseases. C1q tumor necrosis factor-related protein (CTRP1) is a 35-kDa glycoprotein synthesized by various tissues and cells, such as adipose tissue and macrophages. As an adiponectin paralog, CTRP1 signals through adiponectin receptor 1 (AdipoR1) and participates in a variety of pathophysiological processes. Circulating CTRP1 levels are significantly increased in patients with coronary artery disease. Importantly, CTRP1 was shown to accelerate the development of atherosclerosis by promoting vascular inflammation, macrophage foam cell formation and endothelial barrier dysfunction. This review focused on recent advances regarding the role of CTRP1 in atherogenesis with an emphasis on its potential as a novel biomarker and a promising therapeutic target for atherosclerosis-related diseases.

Interleukin-22: a potential therapeutic target in atherosclerosis

BACKGROUND

Atherosclerosis is recognized as a chronic immuno-inflammatory disease that is characterized by the accumulation of immune cells and lipids in the vascular wall. In this review, we focus on the latest advance regarding the regulation and signaling pathways of IL-22 and highlight its impacts on atherosclerosis.

MAIN BODY

IL-22, an important member of the IL-10 family of cytokines, is released by cells of the adaptive and innate immune system and plays a key role in the development of inflammatory diseases. The binding of IL-22 to its receptor complex can trigger a diverse array of downstream signaling pathways, in particular the JAK/STAT, to induce the expression of chemokines and proinflammatory cytokines. Recently, numerous studies suggest that IL-22 is involved in the pathogenesis of atherosclerosis by regulation of VSMC proliferation and migration, angiogenesis, inflammatory response, hypertension, and cholesterol metabolism.

CONCLUSION

IL-22 promotes the development of atherosclerosis by multiple mechanisms, which may be a promising therapeutic target in the pathogenesis of atherosclerosis.

Midkine: A multifaceted driver of atherosclerosis

Atherosclerosis constitutes the pathological basis of life-threatening events, including heart attack and stroke. Midkine is a heparin-binding growth factor and forms a small protein family with pleiotrophin. Under inflammatory or hypoxic conditions, midkine expression is up-regulated. Upon binding to its receptors, midkine can activate multiple signal pathways to regulate cell survival and migration, epithelial-to-mesenchymal transition, and oncogenesis. Circulating midkine levels are significantly increased in patients with essential hypertension, obesity or severe peripheral artery disease. Importantly, midkine exerts a proatherogenic effect by altering multiple pathophysiological processes involving atherogenesis, including macrophage lipid accumulation, vascular inflammation, neointima formation, insulin resistance and macrophage apoptosis. Midkine represents a potential therapeutic target for atherosclerosis-associated diseases. This review described the structure characteristics, expression patterns and signal transduction pathways of midkine with an emphasis on its role in atherosclerosis.

Microtubule affinity regulating kinase 4: A promising target in the pathogenesis of atherosclerosis

Microtubule affinity regulating kinase 4 (MARK4), an important member of the serine/threonine kinase family, regulates the phosphorylation of microtubule-associated proteins and thus modulates microtubule dynamics. In human atherosclerotic lesions, the expression of MARK4 is significantly increased. Recently, accumulating evidence suggests that MARK4 exerts a proatherogenic effect via regulation of lipid metabolism (cholesterol, fatty acid, and triglyceride), inflammation, cell cycle progression and proliferation, insulin signaling, and glucose homeostasis, white adipocyte browning, and oxidative stress. In this review, we summarize the latest findings regarding the role of MARK4 in the pathogenesis of atherosclerosis to provide a rationale for future investigation and therapeutic intervention.