Gut microbiome and metabolomic profiles reveal the antiatherosclerotic effect of indole-3-carbinol in high-choline-fed ApoE-/- mice.

BACKGROUND: The metabolites produced from choline contribute to atherosclerosis (AS) pathogenesis, and the gut microbiota is redundantly essential for this process. Indole-3-carbinol (I3C), found in cruciferous vegetables such as broccoli, cabbage, cauliflower and brussels sprouts, helps prevent hyperlipidemia, maintain the gut microbiota balance, and decrease the production of trimethylamine-N-oxide (TMAO) from choline in the diet. PURPOSE: The objective of this research was to investigate the impact of I3C on choline-induced AS and to further elucidate the underlying mechanism involved. METHODS: AS models of high-choline-induced ApoE-/- mice and TMAO-promoted foamy macrophages were established to observe the effect of I3C on the formation of atherosclerotic plaques and foam cells and changes in AS-related indicators (including blood biochemical indicators, TMA, TMAO, SRA, and SRB1), and integrated analyses of the microbiome and metabolome were used to reveal the mechanism of action of I3C. RESULTS: We found that I3C inhibited high-choline-induced atheroma formation (50-100 mg/kg/d, in vivo) and slightly improved the lipid profile (15 mg/kg/d, in vivo). Moreover, I3C suppressed lipid influx at a concentration of 40 µmol/L in vitro, enhanced the diversity of the gut microbiota and the abundance of the phylum Verrucomicrobia, and consequently modified the gut microbial metabolites at a dosage of 50 mg/kg/d in the mice. Associative analyses based on microbiome and metabolomics revealed that 1-methyladenosine was a key modulator of the protective effect of I3C against AS in high-choline-induced ApoE-/- mice. CONCLUSION: These findings demonstrate for the first time that I3C ameliorates AS progression through remodeling of the gut microbiome and metabolomics, which paves the way for the possible therapeutic use of this vegetable-derived natural compound and may reduce the clinical severity of AS-related cardiovascular diseases.

The potential of aryl hydrocarbon receptor as receptors for metabolic changes in tumors.

Cancer cells can alter their metabolism to meet energy and molecular requirements due to unfavorable environments with oxygen and nutritional deficiencies. Therefore, metabolic reprogramming is common in a tumor microenvironment (TME). Aryl hydrocarbon receptor (AhR) is a ligand-activated nuclear transcription factor, which can be activated by many exogenous and endogenous ligands. Multiple AhR ligands can be produced by both TME and tumor cells. By attaching to various ligands, AhR regulates cancer metabolic reprogramming by dysregulating various metabolic pathways, including glycolysis, lipid metabolism, and nucleotide metabolism. These regulated pathways greatly contribute to cancer cell growth, metastasis, and evading cancer therapies; however, the underlying mechanisms remain unclear. Herein, we review the relationship between TME and metabolism and describe the important role of AhR in cancer regulation. We also focus on recent findings to discuss the idea that AhR acts as a receptor for metabolic changes in tumors, which may provide new perspectives on the direction of AhR research in tumor metabolic reprogramming and future therapeutic interventions.

Aryl hydrocarbon receptor: An emerging player in breast cancer pathogenesis and its potential as a drug target (Review).

Breast cancer is the most common malignancy in women. Metastatic breast cancer is incurable and is a major cause of shortened patient survival. The different molecular types of breast cancer make targeted therapy difficult and a complex challenge. Aryl hydrocarbon receptor (AhR) is an evolutionarily conserved transcription factor that has been implicated in the metabolism of xenobiotic ligands. AhR is activated by numerous exogenous and endogenous ligands and participates in multiple physiological processes, including proliferation, migration, invasion and apoptosis. AhR expression is upregulated in certain breast cancer subtypes, including estrogen receptor­positive breast cancer, and has been implicated in the development and progression of breast cancer. Over the last two decades, AhR and its ligands have emerged as novel biological targets for the treatment of breast cancer. Both AhR agonists and antagonists may be effective in inhibiting critical activities of breast cancer. The present review evaluates the role and underlying mechanisms of AhR and its ligands in breast cancer and demonstrates the potential of exploiting AhR as a novel target for breast cancer therapy.

Insights into the relationship between serum uric acid and pulmonary hypertension (Review).

Pulmonary hypertension (PH) is a progressive lethal disease, which is characterized by abnormal vascular remodeling and persistently elevated pulmonary artery pressure, eventually leading to right heart failure and even death. Although great progress has been made in treating PH, the mortality rate remains high. Metabolic disorders are one of the important hallmarks of PH. Obesity, lipids, glucose tolerance and insulin resistance are risk factors for numerous cardiovascular diseases and are often accompanied by a considerable increase in serum uric acid (SUA) concentrations. Uric acid (UA) is the end product of purine nucleotide metabolism and is closely related to cardiovascular diseases including PH. Hyperuricemia promotes the development and progression of PH through endothelial dysfunction, oxidative stress, inflammatory responses and activation of the renin­angiotensin system. In the present review, the advancements in knowledge about UA metabolism and PH, and the current understanding of the potential interactions and mechanisms of SUA in PH were systematically summarized, which may provide new insights into the pathogenesis of PH.

Aryl hydrocarbon receptor: A bridge linking immuno-inflammation and metabolism in atherosclerosis.

Cardiovascular disease is the leading cause of death worldwide, and atherosclerosis is a major contributor to this etiology. The ligand-activated transcription factor, known as the aryl hydrocarbon receptor (AhR), plays an essential role in the interactions between genes and the environment. In a number of human diseases, including atherosclerosis, the AhR signaling pathway has recently been shown to be aberrantly expressed and activated. It's reported that AhR can regulate the immuno-inflammatory response and metabolism pathways in atherosclerosis, potentially serving as a bridge that links these processes. In this review, we highlight the involvement of AhR in atherosclerosis. From the literature, we conclude that AhR is a potential target for controlling atherosclerosis through precise interventions.

The potential relationship of coronary artery disease and hyperuricemia: A cardiometabolic risk factor.

Coronary arterial disease (CAD) is the leading cause of mortality in the world. Hyperuricemia has recently emerged as a novel independent risk factor of CAD, in addition to the traditional risk factors such as hyperlipidemia, smoking, and obesity. Several clinical studies have shown that hyperuricemia is strongly associated with the risk, progression and poor prognosis of CAD, as well as verifying an association with traditional CAD risk factors. Uric acid or enzymes in the uric acid production pathway are associated with inflammation, oxidative stress, regulation of multiple signaling pathways and the renin-angiotensin-aldosterone system (RAAS), and these pathophysiological alterations are currently the main mechanisms of coronary atherosclerosis formation. The risk of death from CAD can be effectively reduced by the uric acid-lowering therapy, but the interventional treatment of uric acid levels in patients with CAD remains controversial due to the diversity of co-morbidities and the complexity of causative factors. In this review, we analyze the association between hyperuricemia and CAD, elucidate the possible mechanisms by which uric acid induces or exacerbates CAD, and discuss the benefits and drawbacks of uric acid-lowering therapy. This review could provide theoretical references for the prevention and management of hyperuricemia-associated CAD.

Erratum: "Baicalin prevents pulmonary arterial remodeling in vivo via the AKT/ERK/NF-κB signaling pathways".

[This corrects the article DOI: 10.1177/2045894019878599.].

Gut microbiota metabolites as integral mediators in cardiovascular diseases (Review).

Cardiovascular diseases (CVDs), such as atherosclerosis, hypertension, myocardial infarction and diabetic heart disease, are associated with high morbidity and mortality rates worldwide, and may also induce multiple organ failure in their later stages, greatly reducing the long­term survival of the patients. There are several causes of CVDs, but after nearly a decade of investigation, researchers have found that CVDs are usually accompanied by an imbalance of gut microbiota and a decreased abundance of flora. More importantly, the metabolites produced by intestinal flora, such as trimethylamine and trimethylamine N­oxide, bile acids, short­chain fatty acids and aromatic amino acids, exert different effects on the occurrence and development of CVDs, as observed in the relevant pathways in the cells, which may either promote or protect against CVD occurrence. It is known that changes in the intestinal flora following antibiotic administration, diet supplementation with probiotics, or exercise, can interfere with the composition of the intestinal flora and may represent an effective approach to preventing or treating CVDs. The focus of this review was the analysis of gut microbiota metabolites to elucidate their effects on CVDs and to identify the most cost­effective and beneficial methods for treating CVDs with minimal side effects.

Heart­lung crosstalk in pulmonary arterial hypertension following myocardial infarction (Review).

Left heart disease is the main cause of clinical pulmonary arterial hypertension (PAH). Common types of left heart disease that result in PAH include heart failure, left ventricular systolic dysfunction, left ventricular diastolic dysfunction and valvular disease. It is currently believed that mechanical pressure caused by high pulmonary venous pressure is the main cause of myocardial infarction (MI) in individuals with ischemic cardiomyopathy and left ventricular systolic dysfunction. In the presence of decreased cardiac function, vascular remodeling of pulmonary vessels in response to long­term stimulation by high pressure in turn leads to exacerbation of PAH. However, the underlying pathological mechanisms remain unclear. Elucidating the association between the development of MI and PAH may lead to a better understanding of potential risk factors and better disease treatment. In this article, the pathophysiological effects of multiple systems in individuals with MI and PAH were reviewed in order to provide a general perspective on various potential interactions between cardiomyocytes and pulmonary vascular cells.

Baicalin prevents pulmonary arterial remodeling in vivo via the AKT/ERK/NF-κB signaling pathways.

Pulmonary arterial hypertension is a rapidly progressive and often fatal disease. As the pathogenesis of pulmonary arterial hypertension remains unclear, there is currently no good drug for pulmonary arterial hypertension and new therapy is desperately needed. This study investigated the effects and mechanism of baicalin on vascular remodeling in rats with pulmonary arterial hypertension. A rat pulmonary arterial hypertension model was constructed using intraperitoneal injection of monocrotaline, and different doses of baicalin were used to treat these rats. The mean pulmonary arterial pressure (mPAP) and right ventricular systolic pressure (RVSP) were measured with a right heart catheter. Moreover, the hearts were dissected to determine the right ventricular hypertrophy index (RVHI). The lung tissues were stained with H&E and Masson's staining to estimate the pulmonary vascular remodeling and collagen fibrosis, and the expression of proteins in the AKT, ERK, and NF-κB p65 phosphorylation (p-AKT, p-ERK, p-p65) was examined by Western blot analysis. We found that compared with untreated pulmonary arterial hypertension rats, baicalin ameliorated pulmonary vascular remodeling and cardiorespiratory injury, inhibited p-p65 and p-ERK expression, and promoted p-AKT and p-eNOS expression. In conclusion, baicalin interfered with pulmonary vascular remodeling and pulmonary arterial hypertension development in rats through the AKT/eNOS, ERK and NF-κB signaling pathways.

ITE promotes hypoxia-induced transdifferentiation of human pulmonary arterial endothelial cells possibly by activating transforming growth factor-ß/Smads and MAPK/ERK pathways.

This study aimed to investigate the transdifferentiation of human pulmonary arterial endothelial cells (HPAECs) into smooth muscle like (SM-like) cells under hypoxic conditions and reveal the role of endogenous small molecular compound 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylicacid methyl ester (ITE) in this process. HPAECs were treated by hypoxia and hypoxia + ITE with different durations. The endothelial markers (CD31 and VE-cad) and smooth muscle markers (α-SMA, SM22α, and OPN) were investigated by immunofluorescence double staining, and their expressions, along with the differentiation regulators transforming growth factor-ß (TGF-ß) ligands and downstream signals including TGF-ß1, bone morphogenetic protein (BMP2), BMP9, Samd2/3, ERK, and p38 MAPK, were determined by Western blot analysis. The viability and proliferation of HPAECs were detected by Cell Counting Kit-8 (CCK-8) method and bromodeoxyuridine (BrdU) assays. As a result, hypoxia induced HPAECs transdifferentiation from paving-stone-like into polygonal or spindle cells, whose number increased greatly after additional ITE stimulation for 7 days. Compared with the normoxic HPAECs, the expression of endothelial markers reduced and smooth muscle markers were enhanced with the extension of hypoxia + ITE treatment, and meanwhile the cell viability increased significantly. Hypoxia could promote expression of TGF-ß1 protein rather than BMP2 and BMP9, and regulate phosphorylation levels of Samd2/3, ERK and p38 MAPK in different manners. In conclusion, ITE can promote the hypoxia-induced transdifferentiation of HPAECs into SM-like cells via TGF-ß/Smads and MAPK/ERK pathways.

MicroRNA-1 Regulates the Differentiation of Adipose-Derived Stem Cells into Cardiomyocyte-Like Cells.

Stem cell transplantation is one of most valuable methods in the treatment of myocardial infarction, and adipose-derived stem cells (ASCs) are becoming a hot topic in medical research. Previous studies have shown that ASCs can be differentiated into cardiomyocyte-like cells, but the efficiency and survival rates are low. We investigated the role and mechanism of microRNA-1 (miR-1) in the differentiation of ASCs into cardiomyocyte-like cells. ASCs and cardiomyocytes were isolated from neonatal rats. We constructed lentivirus for overexpressing miR-1 and used DAPT, an antagonist of the Notch1 pathway, for in vitro analyses. We performed cocultures with ASCs and cardiomyocytes. The differentiation efficiency of ASCs was detected by cell-specific surface antigens. Our results showed that miR-1 can promote the expression of Notch1 and reduce the expression of Hes1, a Notch pathway factor, and overexpression of miR-1 can promote the differentiation of ASCs into cardiomyocyte-like cells, which may occur by regulating Notch1 and Hes1.

Aryl Hydrocarbon Receptor: A New Player of Pathogenesis and Therapy in Cardiovascular Diseases.

The aryl hydrocarbon receptor (AhR) is a DNA binding protein that acts as a nuclear receptor mediating xenobiotic metabolism and environmental responses. Owing to the evolutionary conservation of this gene and its widespread expression in the immune and circulatory systems, AhR has for many years been almost exclusively studied by the pharmacological/toxicological field for its role in contaminant toxicity. More recently, the functions of AhR in environmental adaption have been examined in the context of the occurrence, development, and therapy of cardiovascular diseases. Increasing evidence suggests that AhR is involved in maintaining homeostasis or in triggering pathogenesis by modulating the biological responses of critical cell types in the cardiovascular system. Here, we describe the structure, distribution, and ligands of AhR and the AhR signaling pathway and review the impact of AhR on cardiovascular physiology. We also discuss the potential contribution of AhR as a new potential factor in the targeted treatment of cardiovascular diseases.

Quercetin Inhibits Pulmonary Arterial Endothelial Cell Transdifferentiation Possibly by Akt and Erk1/2 Pathways.

This study aimed to investigate the effects and mechanisms of quercetin on pulmonary arterial endothelial cell (PAEC) transdifferentiation into smooth muscle-like cells. TGF-ß1-induced PAEC transdifferentiation models were applied to evaluate the pharmacological actions of quercetin. PAEC proliferation was detected with CCK8 method and BurdU immunocytochemistry. Meanwhile, the identification and transdifferentiation of PAECs were determined by FVIII immunofluorescence staining and α-SMA protein expression. The related mechanism was elucidated based on the levels of Akt and Erk1/2 signal pathways. As a result, quercetin effectively inhibited the TGF-ß1-induced proliferation and transdifferentiation of the PAECs and activation of Akt/Erk1/2 cascade in the cells. In conclusion, quercetin is demonstrated to be effective for pulmonary arterial hypertension (PAH) probably by inhibiting endothelial transdifferentiation possibly via modulating Akt and Erk1/2 expressions.

Elevated circulating miR-126-3p expression in patients with acute myocardial infarction: its diagnostic value.

Acute myocardial infarction (AMI) therapy has not remarkably improved due to delay in the diagnosis to a great extent. Circulating microRNAs have shown some potential for diagnosis of cardiovascular diseases. The aim of this study was to estimate the diagnostic value of circulating miR-126-3p for AMI. In our study, circulating miR-126-3p levels were determined by quantitative polymerase chain reaction and the results showed it was 106-fold higher than that in controls, and elevated miR-126-3p was associated with aging through logistic correlation analyses. Receiver-operator characteristic curve was used to evaluate the sensitivity and specificity of miR-126-3p for diagnosis of AMI, indicating that its diagnostic effect was superior to the current clinical markers such as CK, CK-MB, hs-TnI, and MYO. Our results indicate that miR-126-3p in circulation is a potential novel diagnostic biomarker for AMI.

Expression and analyses of the HIF-1 pathway in the lungs of humans with pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is characterized by endothelial dysfunction and structural remodeling of the pulmonary vasculature, mediated initially by reduced oxygen availability in the lungs. Hypoxia inducible factor (HIF), consisting of the functional subunit, HIF­1α, and the constitutively expressed HIF­1ß, is involved in the pathological processes associated with hypoxia. In the current study, the sequences of cDNAs and amino acids of HIF were characterized and analyzed using online bioinformatics tools. To further evaluate whether HIF accounts for the occurrence of PAH, the present study determine the expression and phosphorylation levels of HIF and its associated pathways, including extracellular signal­regulated kinase (Erk)1/2 and phosphoinositide 3­kinase (PI3K)/Akt, in the lungs of patients with PAH by reverse transcription­quantitative polymerase chain reaction and western blotting. The mRNA expression levels of PI3K, Erk2, and HIF­1α in the patients with PAH were significantly higher, compared with those in the control group, by 3.6­fold (P<0.01), 4.06­fold and 2.64­fold (P<0.05), respectively. No significant differences were found in the mRNA and protein levels of Akt between the two groups (P>0.05). The protein levels of phosphorylated (p­)Akt, Erk1/2, p­Erk1/2, HIF­1α and HIF­1ß were significantly increased by 5.89­, 0.5­, 0.59­, 1.46­ and 0.92­fold, respectively, in the patients with PAH, compared with those in the controls group (P<0.01 for p­Akt, Erk1/2; P<0.05 for p­Erk1/2, HIF­1α and HIF­1ß). These findings suggested that the mitogen­activated protein kinase and PI3K/Akt signaling pathways, and HIF­1 may perform a specific function in the pathogenesis of PAH.

Baicalin inhibits inflammation and attenuates myocardial ischaemic injury by aryl hydrocarbon receptor.

OBJECTIVES: Recent evidence indicates that suppressing inflammation by specific drug target and treatment measures contributes to attenuate ischaemic injury and the related heart diseases. This study aimed to investigate the potential effect of baicalin on myocardial ischaemic injury through inhibition of inflammation by inactivating the aryl hydrocarbon receptor (AhR). METHODS: The mouse model with myocardial ischaemic injury was prepared by the left anterior descending coronary artery-amputation and then treated using baicalin. After observing the expression of AhR by immunohistochemical staining, the AhR and inflammatory mediators in circulation and myocardial tissues, including high-sensitive C-reactive protein (hsCRP), interleukin (IL)-1ß and IL-6, were detected based on enzyme-linked immunosorbent assay, real-time polymerase chain reaction and Western blot methods. KEY FINDINGS: The results showed that (1) substantial expression of AhR was observed in myocardial tissues; (2) ischaemic injury caused myocardial necrosis and remodelling, and stimulated hsCRP, IL-1ß and IL-6 by activation of AhR; and (3) baicalin alleviated the myocardial injury and inflammatory response by inhibiting the expression of AhR. CONCLUSION: Our findings extend the list of AhR ligands beyond exogenous toxins and endogenous molecules to cardiac immunological factors, and moreover it could be considered potential drug targets due to its pathological modulatory properties, while baicalin demonstrated promise as a novel vehicle for ischaemic heart disease.

AhR expression and polymorphisms are associated with risk of coronary arterial disease in Chinese population.

The aryl hydrocarbon receptor (AhR) mediates the control of environmental toxicity, and modulates the development and pathogenesis of the cardiovascular system. However, little is known about the role of AhR in coronary arterial disease (CAD) susceptibility. We therefore conducted a case-control study in a Chinese population, and assessed the potential association between AhR variants and CAD susceptibility. Compared with the controls, circulating AhR expression was found to be significantly increased in patients with CAD and its subtypes including ST-segment and non-ST-segment elevation myocardial infarction, and stable and unstable angina pectoris. Receiver operating characteristic (ROC) analysis to evaluate the effect of AhR on CAD progression showed it to be a potent biomarker for CAD. Genotype frequencies of AhR rs2066853 differed significantly between CAD and control subjects, while smoking and hyperlipidemia markedly promoted CAD risk relative to the AhR polymorphism. Moreover, a significant difference in AhR variant distribution was observed between the four CAD subtypes with different severities. The expression level and functional polymorphisms of circulating AhR may affect the susceptibility and progression of CAD in Chinese populations. This provides a novel view of the etiology and epidemiology of CAD, and will contribute to the diagnosis and therapy of this severe disease.

Circulating microRNA-19a as a potential novel biomarker for diagnosis of acute myocardial infarction.

Acute myocardial infarction (AMI) is a serious cardiovascular disease. Investigating new susceptibility genes for effective methods of early diagnosis of AMI is important. In the current study, peripheral blood miR-19a levels were detected by real-time polymerase chain reaction. Significant differences and logistic correlation analyses were carried out by grouping of disease types and stratification of risk factors. Receiver-operator characteristic curve analysis was used to compare the current common clinical biochemical markers and evaluate the sensitivity and specificity of miR-19a for diagnosing AMI. Circulating miR-19a expression in the AMI group was higher than that in controls. The diagnostic effect of circulating miR-19a levels was superior to current clinical biochemical indices, such as CK, CK-MB, MYO, hs-TnI, and BNP. Our results show that there is a close association of circulating miR-19a levels with susceptibility to AMI. Circulating miR-19a levels could be a candidate diagnostic biomarker for AMI.

Roles of microRNA in vascular diseases in cardiac and pulmonary systems.

Coronary artery disease (CAD) and pulmonary arterial hypertension (PAH) are two of the most dangerous vascular diseases. Their etiology and pathogenesis are not yet fully understood, thus it remains difficult to achive great advance in the diagnose, therapy and prognosis techniques. microRNAs (miRNAs), a class of highly conserved, small, noncoding RNAs, critically mediate the post-transcriptional gene modulation, which regulates an array of important physiopathological processes including those occurring in cardiac and pulmonary systems. Thereby manipulation of miRNA expression could potentially be applied therapeutically. In this review, we summarize the current knowledge on the roles of miRNAs in the development of vascular diseases, especially in CAD and PAH, providing a theoretical basis for potential uses of miRNA in diagnosis, prognosis, and therapy in these cardiovascular diseases.