Protective effect of emodin against airway inflammation in the ovalbumin-induced mouse model

Emodin ameliorates matrix degradation and apoptosis in nucleus pulposus cells and attenuates intervertebral disc degeneration through LRP1 in vitro and in vivo

Low back pain (LBP) is the leading cause of disability worldwide, with a strong correlation to intervertebral disc degeneration (IDD). Inflammation-induced extracellular matrix (ECM) degradation plays a major role in IDD's progression. Emodin, known for its anti-inflammatory effects and ability to inhibit ECM degradation in osteoarthritis, but its role in IDD is unclear. Our study aimed to explore emodin's role and mechanisms on IDD both in vivo and in vitro. We discovered that emodin positively regulated anabolic markers (COL2A1, aggrecan) and negatively impacted catabolic markers (MMP3, MMP13) in nucleus pulposus cells, while also inhibiting cell apoptosis under inflammation environment. We revealed that emodin inhibits inflammation-induced NF-ĸB activation by suppressing the degradation of LRP1 via the proteasome pathway. Additionally, LRP1 was validated as essential to emodin's regulation of ECM metabolism and apoptosis, both in vitro and in vivo. Ultimately, we demonstrated that emodin effectively alleviates IDD in a rat model. Our findings uncover the novel pathway of emodin inhibiting ECM degradation and apoptosis through the inhibition of NF-κB via LRP1, thus alleviating IDD. This study not only broadens our understanding of emodin's role and mechanism in IDD treatment but also guides future therapeutic interventions.

Fallopia japonica Root Extract Ameliorates Ovalbumin-Induced Airway Inflammation in a CARAS Mouse Model by Modulating the IL-33/TSLP/NF-κB Signaling Pathway

Fallopia japonica (Asian knotweed) is a medicinal herb traditionally used to treat inflammation, among other conditions. However, the effects of F. japonica root extract (FJE) on airway inflammation associated with combined allergic rhinitis and asthma (CARAS) and the related mechanisms have not been investigated. This study examined the effect of FJE against CARAS in an ovalbumin (OVA)-induced CARAS mouse model. Six-week-old male BALB/c mice were randomly segregated into six groups. Mice were sensitized intraperitoneally with OVA on days 1, 8, and 15, and administered saline, Dexamethasone (1.5 mg/kg), or FJE (50, 100, or 200 mg/kg) once a day for 16 days. Nasal symptoms, inflammatory cells, OVA-specific immunoglobulins, cytokine production, mast cell activation, and nasal histopathology were assessed. Administration of FJE down-regulated OVA-specific IgE and up-regulated OVA-specific IgG2a in serum. FJE reduced the production of T helper (Th) type 2 cytokines, and the Th1 cytokine levels were enhanced in nasal and bronchoalveolar lavage fluid. Moreover, FJE positively regulated allergic responses by reducing the accumulation of inflammatory cells, improving nasal and lung histopathological characteristics, and inhibiting inflammation-associated cytokines. FJE positively modulated the IL-33/TSLP/NF-B signaling pathway, which is involved in regulating inflammatory cells, immunoglobulin levels, and pro-inflammatory cytokines at the molecular level.

Recent advances in the therapeutic potential of emodin for human health

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a bioactive compound, a natural anthraquinone aglycone, present mainly in herbaceous species of the families Fabaceae, Polygonaceae and Rhamnaceae, with a physiological role in protection against abiotic stress in vegetative tissues. Emodin is mainly used in traditional Chinese medicine to treat sore throats, carbuncles, sores, blood stasis, and damp-heat jaundice. Pharmacological research in the last decade has revealed other potential therapeutic applications such as anticancer, neuroprotective, antidiabetic, antioxidant and anti-inflammatory. The present study aimed to summarize recent studies on bioavailability, preclinical pharmacological effects with evidence of molecular mechanisms, clinical trials and clinical pitfalls, respectively the therapeutic limitations of emodin. For this purpose, extensive searches were performed using the PubMed/Medline, Scopus, Google scholar, TRIP database, Springer link, Wiley and SciFinder databases as a search engines. The in vitro and in vivo studies included in this updated review highlighted the signaling pathways and molecular mechanisms of emodin. Because its bioavailability is low, there are limitations in clinical therapeutic use. In conclusion, for an increase in pharmacotherapeutic efficacy, future studies with carrier molecules to the target, thus opening up new therapeutic perspectives.

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.

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.

Advances in the study of emodin: an update on pharmacological properties and mechanistic basis

Rhei Radix et Rhizoma, also known as rhubarb or Da Huang, has been widely used as a spice and as traditional herbal medicine for centuries, and is currently marketed in China as the principal herbs in various prescriptions, such as Da-Huang-Zhe-Chong pills and Da-Huang-Qing-Wei pills. Emodin, a major bioactive anthraquinone derivative extracted from rhubarb, represents multiple health benefits in the treatment of a host of diseases, such as immune-inflammatory abnormality, tumor progression, bacterial or viral infections, and metabolic syndrome. Emerging evidence has made great strides in clarifying the multi-targeting therapeutic mechanisms underlying the efficacious therapeutic potential of emodin, including anti-inflammatory, immunomodulatory, anti-fibrosis, anti-tumor, anti-viral, anti-bacterial, and anti-diabetic properties. This comprehensive review aims to provide an updated summary of recent developments on these pharmacological efficacies and molecular mechanisms of emodin, with a focus on the underlying molecular targets and signaling networks. We also reviewed recent attempts to improve the pharmacokinetic properties and biological activities of emodin by structural modification and novel material-based targeted delivery. In conclusion, emodin still has great potential to become promising therapeutic options to immune and inflammation abnormality, organ fibrosis, common malignancy, pathogenic bacteria or virus infections, and endocrine disease or disorder. Scientifically addressing concerns regarding the poor bioavailability and vague molecular targets would significantly contribute to the widespread acceptance of rhubarb not only as a dietary supplement in food flavorings and colorings but also as a health-promoting TCM in the coming years.

Active ingredients from Chinese medicine plants as therapeutic strategies for asthma: Overview and challenges

Although considerable advance has been made in diagnosing and treating, asthma is still a serious public health challenge. Traditional Chinese medicine (TCM) is an effective therapy of complementary and alternative medicine. More and more scientific evidences support the use of TCM for asthma treatment, and active ingredients from Chinese medicine plants are becoming a hot issue.

PURPOSE OF REVIEW

To summarize the frontier knowledge on the function and underlying mechanisms of the active ingredients in asthma treatments and provide a fully integrated, reliable reference for exploring innovative treatments for asthma.

METHODS

The cited literature was obtained from the PubMed and CNIK databases (up to September 2020). Experimental studies on the active ingredients of Chinese medicine and their therapeutic mechanisms were identified. The key words used in the literature retrieval were "asthma" and "traditional Chinese medicine" or "Chinese herbal medicine". The literature on the active ingredients was then screened manually.

RESULTS

We summarized the effect of these active ingredients on asthma, primarily including the effect through which these ingredients can regulate the immunologic equilibrium mechanism by acting on a number of signalling pathways, such as Notch, JAK-STAT-MAPK, adiponectin-iNOS-NF-κB, PGD2-CRTH2, PI3K/AKT, Keap1-Nrf2/HO-1, T-bet/Gata-3 and Foxp3-RORγt, thereby regulating the progression of asthma.

CONCLUSION

The active ingredients from Chinese medicine have multilevel effects on asthma by regulating the immunologic equilibrium mechanism or signalling pathways, giving them great clinical value. However, the safety and functional mechanism of these ingredients still must be further determined.

Emodin attenuates silica-induced lung injury by inhibition of inflammation, apoptosis and epithelial-mesenchymal transition

Silicosis is a fatal pulmonary disease caused by the inhalation of silica dust, and characterized by inflammation and fibrosis of the lung, with no effective treatment to date. Here we investigate the effect of emodin, an anthraquinone derivative isolated from rhubarb using a mouse silicosis model and in vitro cultured human macrophages and alveolar epithelial cells. Results from histological examination indicated that emodin reduced the degree of alveolitis and fibrosis in the lungs of mice exposed to silica particles. We also demonstrated that emodin effectively inhibited the phosphorylation of Smad3 and NF-κB and reduced the levels of inflammatory factors in the lung tissue of mice treated with silica particles. In addition, we found that emodin inhibited apoptosis and demonstrated an anti-fibrotic effect by down-regulating the pro-apoptotic protein Bax and up-regulating the anti-apoptotic protein Bcl-2. Furthermore, emodin increased E-cadherin levels, reduced the expression of Vimentin, α-SMA and Col-I, as well as pro-inflammatory factors TGF-β1, TNF-α and IL-1β in vivo and in vitro. These results suggested that emodin can regulate epithelial-mesenchymal transition (EMT) through the inhibition of the TGF-β1/Smad3 signaling pathway and the NF-κB signaling pathway to prevent alveolar inflammation and apoptotic process. Overall, this study showed that emodin can alleviate pulmonary fibrosis in silicosis through regulating the inflammatory response and fibrotic process at multiple levels.

Emodin relieved lipopolysaccharide-evoked inflammatory damage in WI-38 cells by up-regulating taurine up-regulated gene 1

BACKGROUND

Neonatal pneumonia (NP) has a high fatality rate in neonatal illness. This research investigated the functions of emodin on lipopolysaccharide (LPS)-evoked inflammatory injury in WI-38 cells.

METHODS

Cell counting kit-8 (CCK-8) assay and flow cytometry were utilized for examining the impacts of LPS and emodin on viability and apoptosis, respectively. Taurine up-regulated gene 1 (TUG1) level was altered through cell transfection and investigated by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Moreover, RT-qPCR, western blot and enzyme-linked immunosorbent assay (ELISA) were utilized for investigating expressions of monocyte chemoattractant protein-1 (MCP-1) and interleukin (IL)-6. Western blot was carried out for investigating the levels of Bcl-2, Bax, pro-Caspase-3, cleaved-Caspase-3 and NF-κB and p38MAPK pathway-related proteins.

RESULTS

LPS treatment restrained cell viability, enhanced apoptosis, and expressions of inflammation-related IL-6 and MCP-1. Emodin alleviated LPS-evoked inflammatory injury and restrained the NF-κB and p38MAPK pathways. Furthermore, emodin positively regulated TUG1 expression and TUG1 silencing could reverse the efficacy of emodin on IL-6 and MCP-1 expressions. Finally, TUG1 regulates the expression of inflammatory factors through NF-κB and p38MAPK pathways.

CONCLUSION

Emodin alleviated LPS-evoked inflammatory injury by raising TUG1 expression via NF-κB and p38MAPK pathways in WI-38 cells.

Emodin ameliorates ovalbumin-induced airway remodeling in mice by suppressing airway smooth muscle cells proliferation

Increased number of airway smooth muscle cells (ASMCs) is a characteristic of airway remodeling in asthma. In this study we investigated whether emodin alleviated airway remodeling in a murine asthma model and reduced the proliferation of ASMCs in vitro. We provided in vivo evidence suggesting that intraperitoneal injection of emodin (20 mg/kg) 1 h prior to OVA challenge apparently alleviated the thickness of airway smooth muscle, the mass of alpha-smooth muscle actin (α-SMA), collagen deposition, epithelial damage, goblet cell hyperplasia, airway inflammation and airway hyperresponsiveness (AHR) in lung tissue. Meanwhile, we found that emodin suppressed the activation of the Akt pathway in lungtissue of allergic mouse models. Additionally, we found that emodin inhibited cellular proliferation and Akt activation in a dose-dependent manner in vitro. Furthermore, LY294002, an inhibitor for PI3K, abrogated serum-induced phosphorylation of Akt, and decreased the proliferation of ASMCs. These findings indicated that emodin alleviated ASMCs proliferation by inhibiting PI3K/Akt pathway in vivo and in vitro, which may provide a potential therapeutic option for airway smooth muscle remodeling in asthma.

Folium Sennae and emodin reverse airway smooth muscle contraction

The objective of this project was to find a bronchodilatory compound from herbs and clarify the mechanism. We found that the ethanol extract of Folium Sennae (EEFS) can relax airway smooth muscle (ASM). EEFS inhibited ASM contraction, induced by acetylcholine, in mouse tracheal rings and lung slices. High-performance liquid chromatography assay showed that EEFS contained emodin. Emodin had a similar reversal action. Acetylcholine-evoked contraction was also partially reduced by nifedipine (a selective inhibitor of L-type voltage-dependent Ca²⁺ channels, LVDCCs), YM-58483 (a selective inhibitor of store-operated Ca²⁺ entry, SOCE), as well as Y-27632 (an inhibitor of Rho-associated protein kinase). In addition, LVDCC- and SOCE-mediated currents and cytosolic Ca²⁺ elevations were inhibited by emodin. Emodin reversed acetylcholine-caused increases in phosphorylation of myosin phosphatase target subunit 1. Furthermore, emodin, in vivo, inhibited acetylcholine-induced respiratory system resistance in mice. These results indicate that EEFS-induced relaxation results from emodin inhibiting LVDCC, SOCE, and Ca²⁺ sensitization. These findings suggest that Folium Sennae and emodin may be new sources of bronchodilators.

Emodin Attenuates Severe Acute Pancreatitis via Antioxidant and Anti-inflammatory Activity

There is no specific drug to treat severe acute pancreatitis (SAP), which induces substantial medical and social burden. Many studies have reported the beneficial effects of emodin against SAP in vivo and in vitro. However, the underlying mechanism has been unclear. This paper described the design and implementation of anti-inflammatory and antioxidant activity of emodin. Emodin restored the pathological damage of SAP and simultaneously decreased the high levels of serum amylase, lipase, TNF-α, and IL-18 in the peripheral blood of SAP rat. Emodin reversed reactive oxygen species (ROS) in neutrophils derived from SAP rat. The levels of voltage-dependent anion channel 1 (VDAC1), NOD-like receptor protein 3 (NLRP3), caspase-1, and IL-18 were examined to analyze the change of inflammasome-related mediators between SAP and emodin treatment. These findings suggest that emodin plays its protective role on SAP against oxidative stress and inflammasome signals.

Emodin alleviates alternatively activated macrophage and asthmatic airway inflammation in a murine asthma model

Alternatively activated macrophages (AAMs) are not only associated with asthma but also lead to asthmatic airway inflammation and remodeling. Inhibition of AAMs is an alternative therapeutic strategy for treating asthma. In this study we investigated whether emodin (1,3,8-trihydroxy-6-methylanthraquinone), isolated from the rhizome of Rheum palmatum, alleviated asthmatic airway inflammation and reduced AAM polarization in a murine asthma model. Mice were sensitized with a triple allergen mix containing dust mite, ragweed and aspergillus (DRA). In mice with DRA-induced asthma, asthmatic inflammation was significantly enhanced. Intraperitoneal injection of emodin (20 mg·kg^-1·d^-1, ip) 1 h prior to DRA challenge on days 12-14 significantly decreased pulmonary eosinophil and lymphocyte infiltration, mucus secretion and serum IgE production, as well as IL-4 and IL-5 production in bronchoalveolar lavage fluid. In response to emodin treatment, activated markers of AAM Ym-1, Fizz-1 and arginase-1 in the lung tissues were remarkably decreased. In mouse bone marrow-derived macrophages (BMDMs) in vitro, emodin (2-50 μmol/L) dose-dependently inhibited IL-4-induced AAM polarization and STAT6 phosphorylation. Collectively, our results suggest that emodin effectively ameliorates asthmatic airway inflammation and AAM polarization, and it may therefore become a potential agent for the treatment of asthma.

Anti-inflammatory effects of Shufengjiedu capsule for upper respiratory infection via the ERK pathway

BACKGROUND

Shufengjiedu Capsule (SFJD) is a type of Chinese traditional medicine compound for the treatment of acute upper respiratory tract infection. The present work aims to decipher the mechanism of SFJD.

METHODS

In this study, we used target prediction and RNA sequence (RNA-Seq) based on transcriptome analysis to clarify the inflammation-eliminating mechanism of SFJD. Firstly, Pseudomonas aeruginosa (PAK) was used to induce acute lung injury in KM mice. After being treated by SFJD, the differently expressed genes were analyzed by RNA-Seq. Secondly, the chemical constituents of SFJD were identified by ultra-performance liquid chromatography quadrupole/time of flight mass spectrometry (UPLC/Q-TOF-MS) and submitted to PharmMapper to predict targets. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and String 9.1 websites were employed to establish the interaction network of inflammation of these targets.

RESULTS

The results indicated that SFJD alleviated PAK induced lung injury in KM mice. We infer that the mechanism is a complex network containing 15 pathways related to inflammation regulated by 16 types of components from six types of herbs via 29 proteins. The ERK signaling pathway was a key pathway among them, which was predicted to be regulated by 14 types of components in SFJD. Phillyrin, emodin, and verbenalin were screened out by binding capacity, and the synergistic effect of them was further confirmed.

CONCLUSIONS

Various components of SFJD ameliorated PAK induced upper respiratory tract infection via multiple targets, of which ERK phosphorylation might be the key event regulated specifically by verbenalin, phillyrin and emodin.

San-Huang-Xie-Xin-Tang Constituents Exert Drug-Drug Interaction of Mutual Reinforcement at Both Pharmacodynamics and Pharmacokinetic Level: A Review

Inflammatory disorders underlie varieties of human diseases. San-Huang-Xie-xin-Tang (SHXXT), composed with Rhizoma Rhei (Rheum palmatum L.), Rhizoma Coptidis (Coptis chinensis Franch), and Radix Scutellaria (Scutellaria baicalensis Georgi), is a famous formula which has been widely used in the fight against inflammatory abnormalities. Mutual reinforcement is one of the basic theories of traditional Chinese medicine. Here this article reviewed and analyzed the recent research on (1) How the main constituents of SHXXT impact on inflammation-associated signaling pathway molecules. (2) The interaction between the main constituents and efflux pumps or intestinal transporters. The goal of this work was to, (1) Provide evidence to support the theory of mutual reinforcement. (2) Clarify the key targets of SHXXT and suggest which targets need further investigation. (3) Give advice for the clinical use of SHXXT to elevated the absorption of main constituents and eventually promote oral bioavailability. We search literatures in scientific databases with key words of “each main SHXXT constituent,” in combination with “each main inflammatory pathway target molecule” or each main intestinal transporter, respectively. We report the effect of five main constituents on target molecules which lies in three main inflammatory signaling pathways, we as well investigate the interaction between constituents and intestinal transporter. We conclude, (1) The synergistic effect of constituents at both levels confirm the mutual reinforcement theory of TCM as it is proven in this work. (2) The effect of main constituents on downstream targets in nuclear need more further investigation. (3) Drug elevating the absorption of rhein, berberine and baicalein can be employed to promote oral bioavailability of SHXXT.

Emodin suppresses silica-induced lung fibrosis by promoting Sirt1 signaling via direct contact

Pulmonary silicosis is characterized by lung fibrosis, which leads to impairment of pulmonary function; the specific mechanism remains to be fully elucidated Emodin shows antifibrotic effects in several organs with fibrosis, however, it has not been investigated in pulmonary silicosis. In the present study, the possible mechanism of lung fibrosis and the antifibrotic effect of emodin in silica inhalation‑induced lung fibrosis were investigated. Pulmonary silica particle inhalation was used to induce lung fibrosis in mice. Emodin and or the sirtuin 1 (Sirt1) inhibitor, nicotinamide, were used to treat the modeled animals. Pulmonary function was assessed using an occlusion method. The deposition of collagen I and α‑smooth muscle actin (SMA) in the lung tissue were detected using fluorescence staining; transforming growth factor‑β1 (TGF‑β1) in the bronchoalveolar lavage fluid (BALF) was examined using an enzyme‑linked immunosorbent assay; TGF-β1/Sirt1/small mothers against decapentaplegic (Smad) signaling activation in lung tissue was also examined. The molecular contacts between emodin were evaluated using liquid chromatography‑mass spectrometry analysis. The deposition of collagen I and α‑SMA in lung tissues were found to be elevated following silica exposure, however, this was relieved by emodin treatment. The pulmonary function of the animals was impaired by silica inhalation, and this was improved by emodin administration. However, the therapeutic effects of emodin on lung fibrosis were impaired by nicotinamide administration. The levels of TGF‑β1 in the BALF and lung tissue were elevated by silica inhalation, however, they were not affected by either emodin or nicotinamide treatment. Additionally, emodin was found to increase the expression level of Sirt1, which decreased the level of deacetylated Smad3 to attenuate collagen deposition. Furthermore, the data suggested that there was direct binding between emodin and Sirt1. Sirt1‑regulated TGF‑β1/Smad signaling was involved in silica inhalation‑induced lung fibrosis. Emodin attenuated this lung fibrosis to improve pulmonary function by targeting Sirt1, which regulated TGF-β1/Smad fibrotic signaling.

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.

The evidence for natural therapeutics as potential anti-scarring agents in burn-related scarring

Though survival rate following severe thermal injuries has improved, the incidence and treatment of scarring have not improved at the same speed. This review discusses the formation of scars and in particular the formation of hypertrophic scars. Further, though there is as yet no gold standard treatment for the prevention or treatment of scarring, a brief overview is included. A number of natural therapeutics have shown beneficial effects both in vivo and in vitro with the potential of becoming clinical therapeutics in the future. These natural therapeutics include both plant-based products such as resveratrol, quercetin and epigallocatechin gallate as examples and includes the non-plant-based therapeutic honey. The review also includes potential mechanism of action for the therapeutics, any recorded adverse events and current administration of the therapeutics used. This review discusses a number of potential 'treatments' that may reduce or even prevent scarring particularly hypertrophic scarring, which is associated with thermal injuries without compromising wound repair.

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.