Emodin attenuates systemic and liver inflammation in hyperlipidemic mice administrated with lipopolysaccharides

Recent advances in anti-inflammatory active components and action mechanisms of natural medicines

Inflammation is a series of reactions caused by the body's resistance to external biological stimuli. Inflammation affects the occurrence and development of many diseases. Anti-inflammatory drugs have been used widely to treat inflammatory diseases, but long-term use can cause toxic side-effects and affect human functions. As immunomodulators with long-term conditioning effects and no drug residues, natural products are being investigated increasingly for the treatment of inflammatory diseases. In this review, we focus on the inflammatory process and cellular mechanisms in the development of diseases such as inflammatory bowel disease, atherosclerosis, and coronavirus disease-2019. Also, we focus on three signaling pathways (Nuclear factor-kappa B, p38 mitogen-activated protein kinase, Janus kinase/signal transducer and activator of transcription-3) to explain the anti-inflammatory effect of natural products. In addition, we also classified common natural products based on secondary metabolites and explained the association between current bidirectional prediction progress of natural product targets and inflammatory diseases.

Advances in the pharmacological effects and molecular mechanisms of emodin in the treatment of metabolic diseases

Rhubarb palmatum L., Polygonum multijiorum Thunb., and Polygonum cuspidatum Sieb. Et Zucc. are traditional Chinese medicines that have been used for thousands of years. They are formulated into various preparations and are widely used. Emodin is a traditional Chinese medicine monomer and the main active ingredient in Rhubarb palmatum L., Polygonum multijiorum Thunb., and Polygonum cuspidatum Sieb. Et Zucc. Modern research shows that it has a variety of pharmacological effects, including promoting lipid and glucose metabolism, osteogenesis, and anti-inflammatory and anti-autophagy effects. Research on the toxicity and pharmacokinetics of emodin can promote its clinical application. This review aims to provide a basis for further development and clinical research of emodin in the treatment of metabolic diseases. We performed a comprehensive summary of the pharmacology and molecular mechanisms of emodin in treating metabolic diseases by searching databases such as Web of Science, PubMed, ScienceDirect, and CNKI up to 2023. In addition, this review also analyzes the toxicity and pharmacokinetics of emodin. The results show that emodin mainly regulates AMPK, PPAR, and inflammation-related signaling pathways, and has a good therapeutic effect on obesity, hyperlipidemia, non-alcoholic fatty liver disease, diabetes and its complications, and osteoporosis. In addition, controlling toxic factors and improving bioavailability are of great significance for its clinical application.

A Review of Herbal Resources Inducing Anti-Liver Metastasis Effects in Gastrointestinal Tumors via Modulation of Tumor Microenvironments in Animal Models

Liver metastases remain a major obstacle for the management of all types of tumors arising from digestive organs, and the tumor microenvironment has been regarded as an important factor in metastasis. To discover herbal candidates inhibiting the liver metastasis of tumors originating from the digestive system via the modulation of the tumor microenvironment and liver environment, we searched three representative public databases and conducted a systematic review. A total of 21 studies that employed experimental models for pancreatic (9), colon (8), and stomach cancers (4) were selected. The herbal agents included single-herb extracts (5), single compounds (12), and multiherbal decoctions (4). Curcuma longa Linn was most frequently studied for its anti-colon-liver metastatic effects, and its possible mechanisms involved the modulation of tumor microenvironment components such as vascular endothelial cells and immunity in both tumor tissues and circulating cells. The list of herbal agents and their mechanisms produced in this study is helpful for the development of anti-liver metastasis drugs in the future.

Traditional Chinese medicines and natural products targeting immune cells in the treatment of metabolic-related fatty liver disease

MAFLD stands for metabolic-related fatty liver disease, which is a prevalent liver disease affecting one-third of adults worldwide, and is strongly associated with obesity, hyperlipidemia, and type 2 diabetes. It encompasses a broad spectrum of conditions ranging from simple liver fat accumulation to advanced stages like chronic inflammation, tissue damage, fibrosis, cirrhosis, and even hepatocellular carcinoma. With limited approved drugs for MAFLD, identifying promising drug targets and developing effective treatment strategies is essential. The liver plays a critical role in regulating human immunity, and enriching innate and adaptive immune cells in the liver can significantly improve the pathological state of MAFLD. In the modern era of drug discovery, there is increasing evidence that traditional Chinese medicine prescriptions, natural products and herb components can effectively treat MAFLD. Our study aims to review the current evidence supporting the potential benefits of such treatments, specifically targeting immune cells that are responsible for the pathogenesis of MAFLD. By providing new insights into the development of traditional drugs for the treatment of MAFLD, our findings may pave the way for more effective and targeted therapeutic approaches.

Emodin attenuates high lipid-induced liver metastasis through the AKT and ERK pathways in vitro in breast cancer cells and in a mouse xenograft model

Emodin, a natural anthraquinone derivative, can inhibit lipid synthesis and breast cancer cell proliferation. We previously found that emodin decreased breast cancer liver metastasis via epithelial-to-mesenchymal transition (EMT) inhibition. However, the mechanism through which emodin affects breast cancer liver metastasis in high-fat diet-induced obese and hyperlipidemic mice has not been elucidated. Bioinformatics analysis was used to reveal the potential targets and pathways of emodin. The mouse model of liver metastasis was established by injecting breast cancer cells into the left ventricle in high-fat diet-induced obese mice. The effect of emodin on inhibiting liver metastasis of breast cancer was evaluated by animal experiments. The mechanisms through which emodin inhibits liver metastasis of breast cancer were studied by cell and molecular biological methods. Emodin reduced lipid synthesis by inhibiting the expression of triglyceride (TG) synthesis-related genes, such as fatty acid synthase (Fasn), glycerol-3-phosphate acyltransferase 1 (Gpat1), and stearoyl-CoA desaturase (Scd1), and ultimately reduced liver metastasis in breast cancer. In addition, emodin inhibited breast cancer cell proliferation and invasion through the serine/threonine kinase (AKT) signaling and extracellular-regulated protein kinase (ERK) pathways by interacting with CSNK2A1, ESR1, ESR2, PIM1 and PTP4A3. Our results indicate that emodin may have therapeutic potential in the prevention or treatment of breast cancer liver metastasis.

Emodin suppresses oxaliplatin-induced neuropathic pain by inhibiting COX2/NF-κB mediated spinal inflammation

Oxaliplatin (OXA) is a common chemotherapy drug for colorectal, gastric, and pancreatic cancers. The anticancer effect of OXA is often accompanied by neurotoxicity and acute and chronic neuropathy. The symptoms present as paresthesia and pain which adversely affect patients' quality of life. Herein, five consecutive intraperitoneal injections of OXA at a dose of 4 mg/kg were used to mimic chemotherapy. OXA administration induced mechanical allodynia, activated spinal astrocytes, and increased inflammatory response. To develop an effective therapeutic measure for OXA-induced neuropathic pain, emodin was intrathecally injected into OXA rats. Emodin developed an analgesic effect, as demonstrated by a significant increase in the paw withdrawal threshold of OXA rats. Moreover, emodin treatment reduced the pro-inflammatory cytokines (tumor necrosis factor-α and interleukin-1β) which upregulated in OXA rats. Furthermore, autodock data showed four hydrogen bonds were formed between emodin and cyclooxygenase-2 (COX2), and emodin treatment decreased COX2 expression in OXA rats. Cell research further proved that emodin suppressed nuclear factor κB (NF-κB)-mediated inflammatory signal and reactive oxygen species level. Taken together, emodin reduced spinal COX2/NF-κB mediated inflammatory signal and oxidative stress in the spinal cord of OXA rats which consequently relieved OXA-induced neuropathic pain.

Highly efficient decontamination of tetracycline and pathogen by a natural product-derived Emodin/HAp photocatalyst

To address the water pollution induced by pharmaceuticals, especially antibiotics, and pathogens, natural product emodin, a traditional Chinese medicine with the characteristic large π-conjugation anthraquinone structure, was used to rationally develop a novel Emodin/HAp photocatalyst by integrating with a thermally stable and recyclable support material hydroxyapatite (HAp) through a simple preparation method. It was found that its photocatalytic activity to generate reactive oxygen species (ROS) was greatly improved due to the migration of photogenerated electrons and holes between emodin and HAp upon visible light irradiation. Thus, this Emodin/HAp photocatalyst not only quickly photodegraded tetracycline with 99.0% removal efficiency but also exhibited complete photodisinfection of pathogenic bacteria Staphylococcus aureus upon visible light irradiation. Therefore, this study offers a new route for the design and preparation of multifunctional photocatalysts using widely available natural products for environmental remediation.

Network pharmacology analysis on mechanism of Jian Pi Qing Gan Yin decoction ameliorating high fat diet-induced non-alcoholic fatty liver disease and validated in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Jian Pi Qing Gan Yin (JPQGY) has been used clinically to relieve non-alcoholic fatty liver disease (NAFLD) in China for decades; however, the underlying mechanisms of JPQGY remain unclear.

AIM OF THE STUDY

We evaluated the effects and mechanisms of JPQGY and hepatic steatosis caused by the middle stage of 13-week-high-fat-diet-induced NAFLD in mice.

MATERIALS AND METHODS

Different dosages of JPQGY (5.5, 11, and 22 g/kg/day) were administered to NAFLD mice simultaneously. Body weight, body mass index (BMI), and liver lipid- and inflammation-related serum indicators were measured enzymatically. Liver samples were stained with Oil Red O and hematoxylin and eosin (H&E). Next, we performed a network pharmacology analysis and verified eight target genes mapping to NAFLD-related lipid metabolism pathways. The mRNA/protein expression was analyzed by real-time polymerase chain reaction (PCR) and western blotting.

RESULTS

JPQGY significantly relieved histological damage (steatosis-inflammation-fibrosis), prevented the downregulation of AMPK and Pparα, and upregulated LXRα, Srebp-1c, F4/80, Nf-κb, and Cyp2e1 in the HFD-induced NAFLD mouse model.

CONCLUSIONS

The present results suggest that chronic treatment with JPQGY ameliorated HFD-induced NAFLD in mice by targeting the first and second phases of hepatic steatosis by stimulating the AMPK/PPARα pathway and inhibiting the LXRα/Srebp1/Nf-κb pathway. Our findings provide evidence that supports the clinical use of this formula for high-fat diet-induced fatty liver disease.

The Pathogenesis of HCC Driven by NASH and the Preventive and Therapeutic Effects of Natural Products

Nonalcoholic steatohepatitis (NASH) is a clinical syndrome with pathological changes that are similar to those of alcoholic hepatitis without a history of excessive alcohol consumption. It is a specific form of nonalcoholic fatty liver disease (NAFLD) that is characterized by hepatocyte inflammation based on hepatocellular steatosis. Further exacerbation of NASH can lead to cirrhosis, which may then progress to hepatocellular carcinoma (HCC). There is a lack of specific and effective treatments for NASH and NASH-driven HCC, and the mechanisms of the progression of NASH to HCC are unclear. Therefore, there is a need to understand the pathogenesis and progression of these diseases to identify new therapeutic approaches. Currently, an increasing number of studies are focusing on the utility of natural products in NASH, which is likely to be a promising prospect for NASH. This paper reviews the possible mechanisms of the pathogenesis and progression of NASH and NASH-derived HCC, as well as the potential therapeutic role of natural products in NASH and NASH-derived HCC.

Protective Effects and Mechanisms of Yinchen Linggui Zhugan Decoction in HFD-Induced Nonalcoholic Fatty Liver Disease Rats Based on Network Pharmacology and Experimental Verification

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease, characterized by excessive accumulation of hepatocyte fat. However, there is no exact and effective pharmacotherapy for NAFLD. Yinchen linggui zhugan decoction (YLZD) has been widely used to treat NAFLD. Nevertheless, its pharmacological and molecular mechanisms have not been clearly elucidated. This study was carried out to investigate the active components of YLZD and explore its potential mechanisms for treating NAFLD by network pharmacology and experimental verification. The results showed that a total of 120 active components of YLZD and 365 targets were retrieved through databases, and the main active ingredients of YLZD consisted of chlorogenic acid, emodin, aloe-emodin, rhein, and geniposide. KEGG enrichment analysis revealed fundamental roles of TNF, PI3K/AKT, HIF-1α, and insulin resistance signaling pathways in the treatment of NAFLD by YLZD. Moreover, our experimental verification results showed that YLZD improved the liver pathological and cholesterol level, and reduced the expressions of TNF-α, IL-1β, IL-6, NF-κB, CCL2, and CXCL10 in NAFLD rats, which all belonged to TNF signaling pathway. The molecular docking confirmed the correlation between the four core components (chlorogenic acid, emodin, rhein, and geniposide) and key factors (TNF-α, IL-6, and NF-κB) in TNF signaling pathway. In conclusion, the present study systematically clarified the protective mechanisms of YLZD against NAFLD through targeting the TNF signaling pathway, and provided new ideas for the drug research of this disease.

Effects of Anthraquinones on Immune Responses and Inflammatory Diseases

The anthraquinones (AQs) and derivatives are widely distributed in nature, including plants, fungi, and insects, with effects of anti-inflammation and anti-oxidation, antibacterial and antiviral, anti-osteoporosis, anti-tumor, etc. Inflammation, including acute and chronic, is a comprehensive response to foreign pathogens under a variety of physiological and pathological processes. AQs could attenuate symptoms and tissue damages through anti-inflammatory or immuno-modulatory effects. The review aims to provide a scientific summary of AQs on immune responses under different pathological conditions, such as digestive diseases, respiratory diseases, central nervous system diseases, etc. It is hoped that the present paper will provide ideas for future studies of the immuno-regulatory effect of AQs and the therapeutic potential for drug development and clinical use of AQs and derivatives.

Emodin Protects Against Lipopolysaccharide-Induced Acute Lung Injury via the JNK/Nur77/c-Jun Signaling Pathway

Background: Acute lung injury (ALI) is a serious inflammatory disease with clinical manifestations of hypoxemia and respiratory failure. Presently, there is no effective treatment of ALI. Although emodin from Rheum palmatum L. exerts anti-ALI properties, the underlying mechanisms have not been fully explored.

Purpose: This study aimed to investigate the therapeutic effect and mechanism of emodin on LPS-induced ALI in mice.

Methods: RAW264.7 cells and zebrafish larvae were stimulated by LPS to establish inflammatory models. The anti-inflammatory effect of emodin was assessed by ELISA, flow cytometric analysis, and survival analysis. In vitro mechanisms were explored by using Western blotting, luciferase assay, electrophoretic mobility shift assay (EMSA), and small interfering RNA (siRNA) approach. The acute lung injury model in mice was established by the intratracheal administration of LPS, and the underlying mechanisms were assessed by detecting changes in histopathological and inflammatory markers and Western blotting in lung tissues.

Results: Emodin inhibited the inflammatory factor production and oxidative stress in RAW264.7 cells, and prolonged the survival of zebrafish larvae after LPS stimulation. Emodin suppressed the expression levels of phosphorylated JNK at Thr183/tyr182 and phosphorylated Nur77 at Ser351 and c-Jun, and increased the expression level of Nur77 in LPS-stimulated RAW264.7 cells, while these regulatory effects of emodin on Nur77/c-Jun were counteracted by JNK activators. The overexpression of JNK dampened the emodin-mediated increase in Nur77 luciferase activity and Nur77 expression. Moreover, the inhibitory effect of emodin on c-Jun can be attenuated by Nur77 siRNA. Furthermore, emodin alleviated LPS-induced ALI in mice through the regulation of the JNK/Nur77/c-Jun pathway.

Conclusions: Emodin protects against LPS-induced ALI through regulation on JNK/Nur77/c-Jun signaling. Our results indicate the potential of emodin in the treatment of ALI.

Herbal compounds in the treatment of pulmonary silicosis

Herbal compounds including those already well-established in traditional Chinese medicine have been increasingly tested in the treatment of various diseases. Recent studies have shown that herbal compounds can be of benefit also for pulmonary silicosis as they can diminish changes associated with silica-induced inflammation, fibrosis, and oxidative stress. Due to a lack of effective therapeutic strategies, development of novel approaches which may be introduced particularly in the early stage of the disease, is urgently needed. This review summarizes positive effects of several alternative plant-based drugs in the models of experimental silicosis with a potential for subsequent clinical investigation and use in future.

Herbal Compounds in the Treatment of Pulmonary Silicosis

Herbal compounds including those already well-established in traditional Chinese medicine have been increasingly tested in the treatment of various diseases. Recent studies have shown that herbal compounds can be of benefit also for pulmonary silicosis as they can diminish changes associated with silica-induced inflammation, fibrosis, and oxidative stress. Due to a lack of effective therapeutic strategies, development of novel approaches which may be introduced particularly in the early stage of the disease, is urgently needed. This review summarizes positive effects of several alternative plant-based drugs in the models of experimental silicosis with a potential for subsequent clinical investigation and use in future.

Jiangzhi Granule attenuates non-alcoholic steatohepatitis by suppressing TNF/NFκB signaling pathway-a study based on network pharmacology

Jiangzhi Granule is a commonly used traditional Chinese medicine for treating non-alcoholic fatty liver disease. However, its key ingredients and underlying mechanisms for attenuating nonalcoholic steatohepatitis (NASH) remain unclear. To address this issue, UPLC-TOF-MS based chemical profiling, network pharmacology and animal experimental validation were employed. First, a total of 56 main ingredients of Jiangzhi Granule and 38 ingredients in the blood and liver (after oral administration) were identified. Then, 170 potential targets of the absorbed ingredients and 50 targets of NASH were identified, and 10 overlapped genes were identified as candidate targets of Jiangzhi Granule for NASH treatment. A Jiangzhi Granule-ingredients-targets-disease network was constructed using Cytoscape software, which included eight main ingredients (such as emodin, resveratrol and quercetin) and 10 candidate targets (such as TNF, IL6 and CCL2). Functional enrichment indicated that the candidate targets were enriched in multiple pathways (such as the TNF signaling pathway). Furthermore, a NASH mice model was constructed and intervened with Jiangzhi Granule. The results revealed that Jiangzhi Granule could ameliorate NASH characteristics, such as histopathological changes and liver cholesterol level. Meanwhile, Jiangzhi Granule significantly decreased the mRNA and protein expression of TNFα in NASH mice liver, suppressed NFκB activation, and inhibited the expression of macrophage activation marker F4/80 and M1-type polarization marker CD11b/CD11c. ELISA assay indicated that Jiangzhi Granule reduced pro-inflammatory cytokines (including TNFα, IL-1β and IL-6) in the liver. Collectively, our results suggested that Jiangzhi Granule could attenuate NASH by suppressing TNF/NFκB signaling mediated macrophage M1-type polarization.

Deletion of TLR4 attenuates lipopolysaccharide-induced acute liver injury by inhibiting inflammation and apoptosis

Septic acute liver injury is one of the leading causes of fatalities in patients with sepsis. Toll-like receptor 4 (TLR4) plays a vital role in response to lipopolysaccharide (LPS) challenge, but the mechanisms underlying TLR4 function in septic injury remains unclear. In this study, we investigated the role of TLR4 in LPS-induced acute liver injury (ALI) in mice with a focus on inflammation and apoptosis. Wild-type (WT) and TLR4-knockout (TLR4-/-) mice were challenged with LPS (4 mg/kg) for 6 h. TLR4 signaling cascade markers (TLR4, MyD88, and NF-κB), inflammatory markers (TNFα, IL-1β, and IL-6), and apoptotic markers (Bax, Bcl-2, and caspase 3) were evaluated. We showed that LPS challenge markedly increased the levels of serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST) and other liver pathological changes in WT mice. In addition, LPS challenge elevated the levels of liver carbonyl proteins and serum inflammatory cytokines, upregulated the expression of TLR4, MyD88, and phosphorylated NF-κB in liver tissues. Moreover, LPS challenge significantly increased hepatocyte apoptosis, caspase 3 activity, and Bax level while suppressing Bcl-2 expression in liver tissues. These pathological changes were greatly attenuated in TLR4-/- mice. Similar pathological responses were provoked in primary hepatic Kupffer cells isolated from WT and TLR4-/- mice following LPS (1 μg/mL, 6 h) challenge. In summary, these results demonstrate that silencing of TLR4 attenuates LPS-induced liver injury through inhibition of inflammation and apoptosis via TLR4/MyD88/NF-κB signaling pathway. TLR4 deletion confers hepatoprotection against ALI induced by LPS, possibly by repressing macrophage inflammation and apoptosis.

Emodin inhibits lipid accumulation and inflammation in adipose tissue of high-fat diet-fed mice by inducing M2 polarization of adipose tissue macrophages

Adipose tissue macrophages (ATMs) represent the most abundant leukocytes in adipose tissue (AT). An increase in number and a phenotypical switch of ATMs during the development of obesity contribute to chronic inflammation and metabolic disorders, which have been regarded as potential therapeutic targets to restore AT homeostasis. Emodin has been shown to exert strong anti-inflammatory property via acting on macrophages in a range of disease models. However, whether emodin exerts a beneficial effect on obesity via modulating ATMs has not been reported. In high-fat diet (HFD)-induced obese mice, emodin significantly inhibited the increase of body weight and lipid accumulation in ATs. Emodin apparently reduced glucose and insulin levels and ameliorated serum lipid profiles in HFD-fed mice. Moreover, the local and systemic inflammation was dramatically alleviated by emodin. We next discovered that M2 macrophage percentage was greatly increased by emodin although total ATMs was not altered, which resulted in a net increase of M2 macrophages in AT. In vitro studies confirmed that emodin promoted the polarization of macrophages towards M2. Gene ontology (GO) analysis showed that myeloid leukocyte differentiation and activation were among the most significant biological processes in emodin-treated ATMs. We further identified that TREM2 was the most dramatically upregulated molecule by emodin and emodin-induced M2 macrophage polarization was dependent on TREM2. Furthermore, silencing TREM2 apparently abrogated the effect of emodin on AT inflammation and adipogenesis. We, for the first time, disclosed that emodin inhibited obesity by promoting M2 macrophage polarization via TREM2, suggesting that emodin may be explored as a clinical and translational candidate in preventing obesity and its related metabolic diseases.

Is Emodin with Anticancer Effects Completely Innocent? Two Sides of the Coin

Many anticancer active compounds are known to have the capacity to destroy pathologically proliferating cancer cells in the body, as well as to destroy rapidly proliferating normal cells. Despite remarkable advances in cancer research over the past few decades, the inclusion of natural compounds in researches as potential drug candidates is becoming increasingly important. However, the perception that the natural is reliable is an issue that needs to be clarified. Among the various chemical classes of natural products, anthraquinones have many biological activities and have also been proven to exhibit a unique anticancer activity. Emodin, an anthraquinone derivative, is a natural compound found in the roots and rhizomes of many plants. The anticancer property of emodin, a broad-spectrum inhibitory agent of cancer cells, has been detailed in many biological pathways. In cancer cells, these molecular mechanisms consist of suppressing cell growth and proliferation through the attenuation of oncogenic growth signaling, such as protein kinase B (AKT), mitogen-activated protein kinase (MAPK), HER-2 tyrosine kinase, Wnt/-catenin, and phosphatidylinositol 3-kinase (PI3K). However, it is known that emodin, which shows toxicity to cancer cells, may cause kidney toxicity, hepatotoxicity, and reproductive toxicity especially at high doses and long-term use. At the same time, studies of emodin, which has poor oral bioavailability, to transform this disadvantage into an advantage with nano-carrier systems reveal that natural compounds are not always directly usable compounds. Consequently, this review aimed to shed light on the anti-proliferative and anti-carcinogenic properties of emodin, as well as its potential toxicities and the advantages of drug delivery systems on bioavailability.

Research progress in use of traditional Chinese medicine monomer for treatment of non-alcoholic fatty liver disease

With the improvement of people's living standards and the change of eating habits, non-alcoholic fatty liver disease (NAFLD) has gradually become one of the most common chronic liver diseases in the world. However, there are no effective drugs for the treatment of NAFLD. Therefore, it is urgent to find safe, efficient, and economical anti-NAFLD drugs. Compared with western medicines that possess fast lipid-lowering effect, traditional Chinese medicines (TCM) have attracted increasing attention for the treatment of NAFLD due to their unique advantages such as multi-targets and multi-channel mechanisms of action. TCM monomers have been proved to treat NAFLD through regulating various pathways, including inflammation, lipid production, insulin sensitivity, mitochondrial dysfunction, autophagy, and intestinal microbiota. In particular, peroxisome proliferator-activated receptor α (PPAR-α), sterol regulatory element-binding protein 1c (SREBP-1c), nuclear transcription factor kappa (NF-κB), phosphoinositide 3-kinase (PI3K), sirtuin1 (SIRT1), AMP-activated protein kinase (AMPK), p53 and nuclear factor erythroid 2-related factor 2 (Nrf2) are considered as important molecular targets for ameliorating NAFLD by TCM monomers. Therefore, by searching PubMed, Web of Science and SciFinder databases, this paper updates and summarizes the experimental and clinical evidence of TCM monomers for the treatment of NAFLD in the past six years (2015-2020), thus providing thoughts and prospects for further exploring the pathogenesis of NAFLD and TCM monomer therapies.

Safety of natural anthraquinone emodin: an assessment in mice

BACKGROUND

Emodin, a natural anthraquinone, has shown potential as an effective therapeutic agent in the treatment of many diseases including cancer. However, its clinical development is hindered by uncertainties surrounding its potential toxicity. The primary purpose of this study was to uncover any potential toxic properties of emodin in mice at doses that have been shown to have efficacy in our cancer studies. In addition, we sought to assess the time course of emodin clearance when administered both intraperitoneally (I.P.) and orally (P.O.) in order to begin to establish effective dosing intervals.

METHODS

We performed a subchronic (12 week) toxicity study using 3 different doses of emodin (~ 20 mg/kg, 40 mg/kg, and 80 mg/kg) infused into the AIN-76A diet of male and female C57BL/6 mice (n = 5/group/sex). Body weight and composition were assessed following the 12-week feeding regime. Tissues were harvested and assessed for gross pathological changes and blood was collected for a complete blood count and evaluation of alanine transaminase (ALT), aspartate transaminase (AST) and creatinine. For the pharmacokinetic study, emodin was delivered intraperitoneally I.P. or P.O. at 20 mg/kg or 40 mg/kg doses to male and female mice (n = 4/group/sex/time-point) and circulating levels of emodin were determined at 1, 4 and 12 h following administration via liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis.

RESULTS

We found that 12 weeks of low (20 mg/kg), medium (40 mg/kg), or high (80 mg/kg) emodin feeding did not cause pathophysiological perturbations in major organs. We also found that glucuronidated emodin peaks at 1 h for both I.P. and P.O. administered emodin and is eliminated by 12 h. Interestingly, female mice appear to metabolize emodin at a faster rate than male mice as evidenced by greater levels of glucuronidated emodin at the 1 h time-point (40 mg/kg for both I.P. and P.O. and 20 mg/kg I.P.) and the 4-h time-point (20 mg/kg I.P.).

CONCLUSIONS

In summary, our studies establish that 1) emodin is safe for use in both male and female mice when given at 20, 40, and 80 mg/kg doses for 12 weeks and 2) sex differences should be considered when establishing dosing intervals for emodin treatment.

A Double-Edged Sword: The Anti-Cancer Effects of Emodin by Inhibiting the Redox-Protective Protein MTH1 and Augmenting ROS in NSCLC

Background: Reactive oxygen species (ROS), playing a two-fold role in tumorigenesis, are responsible for tumor formation and progression through the induction of genome instability and pro-oncogenic signaling. The same ROS is toxic to cancer cells at higher levels, oxidizing free nucleotide precursors (dNTPs) as well as damaging DNA leading to cell senescence. Research has highlighted the tumor cell-specific expression of a redox-protective phosphatase, MutT homolog 1 (MTH1), that performs the enzymatic conversion of oxidized nucleotides (like 8-oxo-dGTP) to their corresponding monophosphates, up-regulated in numerous cancers, circumventing their misincorporation into the genomic DNA and preventing damage and cell death. Methods: To identify novel natural small molecular inhibitors of MTH1 to be used as cancer therapeutic agents, molecular screening for MTH1 active site binders was performed from natural small molecular libraries. Emodin was identified as a lead compound for MTH1 active site functional inhibition and its action on MTH1 inhibition was validated on non-small cell lung cancer cellular models (NSCLC). Results: Our study provides strong evidence that emodin mediated MTH1 inhibition impaired NSCLC cell growth, inducing senescence. Emodin treatment enhanced the cellular ROS burdens, on one hand, damaged dNTP pools and inhibited MTH1 function on the other. Our work on emodin indicates that ROS is the key driver of cancer cell-specific increased DNA damage and apoptosis upon MTH1 inhibition. Consequently, we observed a time-dependent increase in NSCL cancer cell susceptibility to oxidative stress with emodin treatment. Conclusions: Based on our data, the anti-cancer effects of emodin as an MTH1 inhibitor have clinical potential as a single agent capable of functioning as a ROS inducer and simultaneous blocker of dNTP pool sanitation in the treatment of NSCL cancers. Collectively, our results have identified for the first time that the potential molecular mechanism of emodin function, increasing DNA damage and apoptosis in cancer cells, is via MTH1 inhibition.

Emodin in atherosclerosis prevention: Pharmacological actions and therapeutic potential

Atherosclerotic plaque formation, destabilization and eventual rupture leads to the acute cardiovascular events including myocardial infarction and stroke. Emodin (PubChem CID#3220), (1,3,8-trihydroxy-6-methylanthracene-9,10-dione) is a pharmacologically bioactive constituent isolated from the traditional Chinese medicinal herb Radix rhizoma Rhei. This molecule has anti-oxidant, anti-inflammatory, anti-proliferative, anti-apoptotic and lipid-modulating effects. Experimental studies have demonstrated that emodin attenuates and stabilizes atherosclerotic plaques. In this mini-review, we provide a summary of the pharmacological actions of emodin in regulating vascular function and atherosclerosis, highlighting the therapeutic potential of this phytochemical in patients with cardiovascular disease.

Emodin 8-O-glucoside primes macrophages more strongly than emodin aglycone via activation of phagocytic activity and TLR-2/MAPK/NF-κB signalling pathway

Emodin (Emo) is a natural plant anthraquinone derivative with a wide spectrum of pharmacological properties, including anticancer, antioxidant, and hepatoprotective activities. Glycosylation of natural anthraquinones with various sugar moieties can affect their physical, chemical, and biological functions. In this study, the potential immunomodulatory activities of Emo and its glycosylated derivative, emodin 8-O-glucoside (E8G), were evaluated and compared using murine macrophage RAW264.7 cells and human monocytic THP-1 cells. The results showed that E8G (20 μM) induced the secretion of TNF-α and IL-6 from RAW264.7 cells more effectively than unglycosylated Emo aglycone, by 4.9- and 1.6-fold, respectively, with no significant cytotoxicity in the concentration range tested (up to 20 μM). E8G (2.5-20 μM) significantly and dose-dependently induced inducible nitric oxide synthase (iNOS) expression by up to 3.2-fold compared to that of untreated control following a remarkable increase in nitric oxide (NO) production. E8G also significantly increased the expression of TLR-2 mRNA and the phosphorylation of MAPKs (JNK and p38). The activation and subsequent nuclear translocation of NF-κB was substantially enhanced upon treatment with E8G (2.5-20 μM). Moreover, E8G markedly induced macrophage-mediated phagocytosis of apoptotic Jurkat T cells. These results demonstrated that E8G far more strongly stimulates the secretion of proinflammatory cytokines, such as TNF-α and IL-6, and NO production from macrophages through upregulation of the TLR-2/MAPK/NF-κB signalling pathway than its nonglycosylated form, Emo aglycone. These results suggest for the first time that E8G may represent a novel immunomodulator, enhancing the early innate immunity.

The effect of emodin on liver disease -- comprehensive advances in molecular mechanisms

Liver injury could be caused by a variety of causes, including alcohol, drug poisoning, autoimmune overreaction, etc. In the period of liver injury, hepatic stellate cells (HSCs) will be activated and produce excessive extracellular matrix (ECM). If injury cannot be suppressed, liver injury will develop into fibrosis, even cirrhosis and liver cancer. It is reported that some monomer components extracted from traditional Chinese medicine have better effects on protecting liver. Emodin, an anthraquinone compound extracted from the traditional Chinese medicine RHEI RADIX ET RHIZOMA, has anti-inflammatory, antioxidant, liver protection and anti-cancer effects, and can prevent liver injury induced by a variety of factors. By searching literatures related to the liver protection of emodin in PUBMED, SINOMED, EBM and CNKI databases, it was found that emodin could inhibit the production and promote the secretion of bile acids, and have a protective effect on intrahepatic cholestasis. Also, emodin reduce collagen synthesis and anti-hepatic fibrosis by inhibiting oxidative stress, TGF-β/Smad pathway and HSCs proliferation, and promoting apoptosis of HSCs. Emodin can also regulate lipid metabolism and regulate the synthesis and oxidation of lipids and cholesterol to protect the nonalcoholic fatty liver. Besides, emodin can induce the apoptosis of hepatocellular carcinoma cells by acting on the death receptor pathway and mitochondrial apoptosis pathway, thus inhibiting the development of hepatocellular carcinoma. Moreover, emodin can modulate immunity and improve immune rejection in liver transplantation animals. In conclusion, emodin has a good effect on liver protection, but further experimental data are needed to verify it.

A Candidate Drug for Nonalcoholic Fatty Liver Disease: A Review of Pharmacological Activities of Polygoni Multiflori Radix

Nonalcoholic fatty liver disease, a type of metabolic syndrome, continues to rise globally. Currently, there is no approved drug for its treatment. Improving lifestyle and exercise can alleviate symptoms, but patients' compliance is poor. More and more studies have shown the potential of Polygoni Multiflori Radix (PMR) in the treatment of NAFLD and metabolic syndrome. Therefore, this paper reviews the pharmacological effects of PMR and its main chemical components (tetrahydroxystilbene glucoside, emodin, and resveratrol) on NAFLD. PMR can inhibit the production of fatty acids and promote the decomposition of triglycerides, reduce inflammation, and inhibit the occurrence of liver fibrosis. At the same time, it maintains an oxidation equilibrium status in the body, to achieve the therapeutic purpose of NAFLD and metabolic syndrome. Although more standardized studies and clinical trials are needed to confirm its efficacy, PMR may be a potential drug for the treatment of NAFLD and its complications. However, the occurrence of adverse reactions of PMR has affected its extensive clinical application. Therefore, it is necessary to further study its toxicity mechanism, enhance efficacy and control toxicity, and even reduce toxicity, which will contribute to the safe clinical use of PMR.

Biosynthesis of Rhamnosylated Anthraquinones in Escherichia coli

Rhamnose is a naturally occurring deoxysugar present as a glycogenic component of plant and microbial natural products. A recombinant mutant Escherichia coli strain was developed by overexpressing genes involved in the TDP-L-rhamnose biosynthesis pathway of different bacterial strains and Saccharothrix espanaensis rhamnosyl transferase to conjugate intrinsic cytosolic TDP-L-rhamnose with anthraquinones supplemented exogenously. Among the five anthraquinones (alizarin, emodin, chrysazin, anthrarufin, and quinizarin) tested, quinizarin was biotransformed into a rhamoside derivative with the highest conversion ratio by whole cells of engineered E. coli. The quinizarin glycoside was identified by various chromatographic and spectroscopic analyses. The anti-proliferative property of the newly synthesized rhamnoside, quinizarin-4-O-α-L-rhamnoside, was assayed in various cancer cells.

Systematic investigation on the chemical basis of anti-NAFLD Qushi Huayu Fang. Part 1: A study of metabolic profiles in vivo and in vitro by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Qushi Huayu Fang (QHF) is a clinic-empirical prescription for treating non-alcoholic fatty liver disease (NAFLD) in China, which is composed of five herbs. However, the bioactive constituents responsible for the efficacy of QHF remain unclear. Thus, a high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry method was established and adopted to identify the constituents of QHF, and profile its metabolism in vivo and in vitro. Among the 66 constituents in QHF, only 14 compounds of six structural types were absorbed, and 34 metabolites were generated through eight metabolic pathways. A total of 20 metabolites were first reported, including four organic acids, one iridoid, two flavones, five naphthols, three anthraquinones, and five stilbenes. Glucuronidation and sulfation were the main metabolic pathways, and the intestinal metabolism played an important role in the biotransformation of QHF. Many compounds, especially those detected in the liver, the target organ of QHF, were reported to display the anti-NAFLD activity. This is the first study to explore the constituents of QHF and its metabolism in vivo and in vitro, thus realizing the first step to clarify the chemical basis of QHF qualitatively, and laying the foundation for further research on the anti-NAFLD mechanism of QHF.

Chinese Medicinal Herbs Targeting the Gut-Liver Axis and Adipose Tissue-Liver Axis for Non-Alcoholic Fatty Liver Disease Treatments: The Ancient Wisdom and Modern Science

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. The pathogenesis of NAFLD is complex. Frontline western medicines only ameliorate the symptoms of NAFLD. On the contrary, the uniqueness of Chinese medicine in its interpretation of NAFLD and the holistic therapeutic approach lead to a promising therapeutic efficacy. Recent studies reveal that the gut-liver axis and adipose tissue-liver axis play important roles in the development of NAFLD. Interestingly, with advanced technology, many herbal formulae are found to target the gut-liver axis and adipose tissue-liver axis and resolve the inflammation in NAFLD. This is the first review summarizes the current findings on the Chinese herbal formulae that target the two axes in NAFLD treatment. This review not only demonstrates how the ancient wisdom of Chinese medicine is being interpreted by modern pharmacological studies, but also provides valuable information for the further development of the herbal-based treatment for NAFLD.

Anticancer activity of emodin is associated with downregulation of CD155

Emodin is a Chinese herb-derived compound that exhibits a variety of pharmacological benefits. Although emodin has been shown to inhibit growth of cancer cells, its antineoplastic function is incompletely understood. CD155 is a member of poliovirus receptor-related (PRR) family of adhesion molecules; it is constitutively expressed on many tumor cell lines and tissues and has diverse functions. CD155 has been reported to mediate activation of T cells via CD226 or inhibition of T cells via T-cell immunoreceptor with Ig and ITIM domains (TIGIT). In addition, CD155 may play a critical role through non-immunological mechanisms in cancer. In this study, we tested the ability of emodin to modulate CD155 expression in cancer cells. We found that emodin significantly decreased the expression of CD155 in tumor cells and inhibited tumor cell proliferation and migration, and induced cell-cycle arrest at G2/M phase. The tumor inhibitory effects of emodin were lost with CD155 knockdown. Furthermore, emodin was used to treat mice bearing B16 melanoma. It was shown that emodin attenuated tumor growth accompanied by suppressing CD155 expression. Therefore, we propose that emodin could inhibit tumor growth, and the antineoplastic properties of emodin are at least partially CD155 dependent. Our study provides new insights into the mechanisms by which emodin inhibits tumor growth.

Emodin Attenuates Lipopolysaccharide-Induced Acute Liver Injury via Inhibiting the TLR4 Signaling Pathway in vitro and in vivo

Aims: Emodin is an anthraquinone with potential anti-inflammatory properties. However, the possible molecular mechanisms and protective effects of emodin are not clear. The objective of this study was to investigate the possible molecular mechanisms and protective effects of emodin on lipopolysaccharide (LPS)-induced acute liver injury (ALI) via the Toll-like receptor 4 (TLR4) signaling pathway in the Raw264.7 cell line and in Balb/c mice. Methods: This study established an inflammatory cellular model and induced an ALI animal model. TLR4 was overexpressed by lentivirus and downregulated by small interfering RNA (siRNA) technology. The mRNA and protein levels of TLR4 and downstream molecules were detected in cells and liver tissue. The tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 levels in supernatant and serum were determined by ELISA. The distribution and expression of mannose receptor C type 1 (CD206) and arginase 1 (ARG1) in the liver were tested by immunofluorescence. Mouse liver function and histopathological observations were assessed. Results: Administration of emodin reduced the protein and/or mRNA levels of TLR4 and its downstream molecules following LPS challenge in Raw264.7 cells and in an animal model. Additionally, emodin suppressed the expression of TNF-α and IL-6 in cell culture supernatant and serum. The inhibitory effect of emodin was also confirmed in RAW264.7 cells, in which TLR4 was overexpressed or knocked down. Additionally, ARG1 and CD206 were elevated in the emodin groups. Emodin also decreased serum ALT and AST levels and alleviated the liver histopathological damage induced by LPS. Conclusion: Emodin showed excellent hepatoprotective effects against LPS-induced ALI, possibly by inhibiting TLR4 signaling pathways.

Emodin: A Review of its Pharmacology, Toxicity and Pharmacokinetics

Emodin is a natural anthraquinone derivative that occurs in many widely used Chinese medicinal herbs, such as Rheum palmatum, Polygonum cuspidatum and Polygonum multiflorum. Emodin has been used as a traditional Chinese medicine for over 2000 years and is still present in various herbal preparations. Emerging evidence indicates that emodin possesses a wide spectrum of pharmacological properties, including anticancer, hepatoprotective, antiinflammatory, antioxidant and antimicrobial activities. However, emodin could also lead to hepatotoxicity, kidney toxicity and reproductive toxicity, particularly in high doses and with long-term use. Pharmacokinetic studies have demonstrated that emodin has poor oral bioavailability in rats because of its extensive glucuronidation. This review aims to comprehensively summarize the pharmacology, toxicity and pharmacokinetics of emodin reported to date with an emphasis on its biological properties and mechanisms of action. Copyright © 2016 John Wiley & Sons, Ltd.

Emodin Inhibits Breast Cancer Growth by Blocking the Tumor-Promoting Feedforward Loop between Cancer Cells and Macrophages

Macrophage infiltration correlates with severity in many types of cancer. Tumor cells recruit macrophages and educate them to adopt an M2-like phenotype through the secretion of chemokines and growth factors, such as MCP1 and CSF1. Macrophages in turn promote tumor growth through supporting angiogenesis, suppressing antitumor immunity, modulating extracellular matrix remodeling, and promoting tumor cell migration. Thus, tumor cells and macrophages interact to create a feedforward loop supporting tumor growth and metastasis. In this study, we tested the ability of emodin, a Chinese herb-derived compound, to inhibit breast cancer growth in mice and examined the underlying mechanisms. Emodin was used to treat mice bearing EO771 or 4T1 breast tumors. It was shown that emodin attenuated tumor growth by inhibiting macrophage infiltration and M2-like polarization, accompanied by increased T-cell activation and reduced angiogenesis in tumors. The tumor inhibitory effects of emodin were lost in tumor-bearing mice with macrophage depletion. Emodin inhibited IRF4, STAT6, and C/EBPβ signaling and increased inhibitory histone H3 lysine 27 tri-methylation (H3K27m3) on the promoters of M2-related genes in tumor-associated macrophages. In addition, emodin inhibited tumor cell secretion of MCP1 and CSF1, as well as expression of surface anchoring molecule Thy-1, thus suppressing macrophage migration toward and adhesion to tumor cells. These results suggest that emodin acts on both breast cancer cells and macrophages and effectively blocks the tumor-promoting feedforward loop between the two cell types, thereby inhibiting breast cancer growth and metastasis. Mol Cancer Ther; 15(8); 1931-42. ©2016 AACR.

Emodin Bidirectionally Modulates Macrophage Polarization and Epigenetically Regulates Macrophage Memory

Macrophages are pleiotropic cells capable of performing a broad spectrum of functions. Macrophage phenotypes are classified along a continuum between the extremes of proinflammatory M1 macrophages and anti-inflammatory M2 macrophages. The seemingly opposing functions of M1 and M2 macrophages must be tightly regulated for an effective and proper response to foreign molecules or damaged tissue. Excessive activation of either M1 or M2 macrophages contributes to the pathology of many diseases. Emodin is a Chinese herb-derived compound and has shown potential to inhibit inflammation in various settings. In this study, we tested the ability of emodin to modulate the macrophage response to both M1 and M2 stimuli. Primary mouse macrophages were stimulated with LPS/IFNγ or IL4 with or without emodin, and the effects of emodin on gene transcription, cell signaling pathways, and histone modifications were examined by a variety of approaches, including microarray, quantitative real-time PCR, Western blotting, chromatin immunoprecipitation, and functional assays. We found that emodin bidirectionally tunes the induction of LPS/IFNγ- and IL4-responsive genes through inhibiting NFκB/IRF5/STAT1 signaling and IRF4/STAT6 signaling, respectively. Thereby, emodin modulates macrophage phagocytosis, migration, and NO production. Furthermore, emodin inhibited the removal of H3K27 trimethylation (H3K27m3) marks and the addition of H3K27 acetylation (H3K27ac) marks on genes required for M1 or M2 polarization of macrophages. In conclusion, our data suggest that emodin is uniquely able to suppress the excessive response of macrophages to both M1 and M2 stimuli and therefore has the potential to restore macrophage homeostasis in various pathologies.

Subclinical-Dose Endotoxin Sustains Low-Grade Inflammation and Exacerbates Steatohepatitis in High-Fat Diet-Fed Mice

Subclinical circulating bacterial endotoxin LPS has been implicated as an important cofactor in the development and progression of nonalcoholic steatohepatitis, but the underlying mechanisms remain unclear. In this study, we demonstrated that 4-wk injection with superlow-dose LPS significantly promoted neutrophil infiltration and accelerated nonalcoholic steatohepatitis progression, including exacerbated macrovesicular steatosis, inflammation, and hepatocyte ballooning in high-fat diet-fed apolipoprotein E knockout mice. This effect could sustain for a month after stoppage of LPS injection. LPS also significantly increased numbers of apoptotic nuclei in hepatocytes and expressions of proapoptotic regulators. Moreover, LPS sustained the low-grade activation of p38 MAPK and inhibited the expression of the upstream MAPK phosphatase 7. By applying selective inhibitors, we demonstrated that the activation of p38 MAPKs is required for neutrophil migration induced by superlow-dose LPS in vitro. Together, these data suggest that superlow-dose LPS may sustain the low-grade activation of p38 MAPKs and neutrophil infiltration, leading to the exacerbation of steatohepatitis.

Development of phenylboronic acid-functionalized nanoparticles for emodin delivery

Stable and monodisperse phenylboronic acid-functionalized nanoparticles (PBA-NPs) were fabricated using 3-((acrylamido)methyl)phenylboronic acid homopolymer (PBAH) via solvent displacement technique. The effect of operating parameters, including stirring time, initial polymer concentration and the proportion of methanol on the self-assembly process were systematically investigated. The diameters of the PBA-NPs were increased as increasing the initial PBAH concentration and the proportion of methanol. Likewise, there was a linear dependence between the size of self-assembled nanoparticles and the polymer concentration. Moreover, the dissipative particle dynamics (DPD) simulation technique was used to investigate the mechanism of self-assembly behavior of PBAH, which indicated that the interior of PBA-NPs was hydrophobic and compact, and the boronic acid groups were displayed on both the outermost and interior of PBA-NPs. The resulting PBA-NPs could successfully encapsulate emodin through PBA-diol interaction and the encapsulation efficiency (EE%) and drug loading content (DLC%) of drug-loaded PBA-NPs were 78% and 2.1%, respectively. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the disassociation of the boronate ester bonds, which could accelerate the drug release from PBA-Emodin-NPs. Besides, PBA-Emodin-NPs showed a much higher cytotoxicity to HepG2 cells (cancer cells) than that to MC-3T3-E1 cells (normal cells). These results imply that PBA-NPs would be a promising scaffold for the delivery of polyphenolic drugs.

Emodin suppresses pulmonary metastasis of breast cancer accompanied with decreased macrophage recruitment and M2 polarization in the lungs

Breast cancer is the leading cause of death in female cancer patients due to the lack of effective treatment for metastasis. Macrophages are the most abundant immune cells in the primary and metastatic tumors, and contribute to tumor initiation, progression, and metastasis. Emodin has been found to exert anti-tumor effects through promoting cell cycle arrest and apoptosis, and inhibiting angiogenesis, but its effects on tumor-associated macrophages during cancer metastasis have not been investigated. Mice inoculated with 4T1 or EO771 breast cancer cells orthotopically were treated with Emodin after the primary tumors reached 200 mm3 in size. Primary tumor growth, lung metastasis, and macrophage infiltration in the lungs were analyzed. In vitro experiments were performed to examine the effects of Emodin on macrophage migration and M2 polarization, and the underlying mechanisms. Emodin significantly suppressed breast cancer lung metastasis in both orthotopic mouse models without apparent effects on primary tumors. Reduced infiltration of F4/80+ macrophages and Ym1+ M2 macrophages in lungs was observed in Emodin-treated mice. In vitro experiments demonstrated that Emodin decreased the migration of macrophages toward tumor cell-conditioned medium (TCM) and inhibited macrophage M2 polarization induced by TCM. Mechanistically, Emodin suppressed STAT6 phosphorylation and C/EBPβ expression, two crucial signaling events in macrophage M2 polarization, in macrophages treated with IL-4 or TCM. Taken together, our study, for the first time, demonstrated that Emodin suppressed pulmonary metastasis of breast cancer probably through inhibiting macrophage recruitment and M2 polarization in the lungs by reducing STAT6 phosphorylation and C/EBPβ expression.