Isoliquiritigenin, a flavonoid from licorice, blocks M2 macrophage polarization in colitis-associated tumorigenesis through downregulating PGE2 and IL-6

Natural products with anti-tumorigenesis potential targeting macrophage

BACKGROUND

Inflammation is a risk factor for tumorigenesis. Macrophage, a subset of immune cells with high plasticity, plays a multifaceted role in this process. Natural products, which are bioactive compounds derived from traditional herbs or foods, have exhibited diverse effects on macrophages and tumorigenesis making them a valuable resource of drug discovery or optimization in tumor prevention.

PURPOSE

Provide a comprehensive overview of the various roles of macrophages in tumorigenesis, as well as the effects of natural products on tumorigenesis by modulating macrophage function.

METHODS

A thorough literature search spanning the past two decades was carried out using PubMed, Web of Science, Elsevier, and CNKI following the PRISMA guidelines. The search terms employed included "macrophage and tumorigenesis", "natural products, macrophages and tumorigenesis", "traditional Chinese medicine and tumorigenesis", "natural products and macrophage polarization", "macrophage and tumor related microenvironment", "macrophage and tumor signal pathway", "toxicity of natural products" and combinations thereof. Furthermore, certain articles are identified through the tracking of citations from other publications or by accessing the websites of relevant journals. Studies that meet the following criteria are excluded: (1) Articles not written in English or Chinese; (2) Full texts were not available; (3) Duplicate articles and irrelevant studies. The data collected was organized and summarized based on molecular mechanisms or compound structure.

RESULTS

This review elucidates the multifaceted effect of macrophages on tumorigenesis, encompassing process such as inflammation, angiogenesis, and tumor cell invasion by regulating metabolism, non-coding RNA, signal transduction and intercellular crosstalk. Natural products, including vitexin, ovatodiolide, ligustilide, and emodin, as well as herbal remedies, have demonstrated efficacy in modulating macrophage function, thereby attenuating tumorigenesis. These interventions mainly focus on mitigating the initial inflammatory response or modifying the inflammatory environment within the precancerous niche.

CONCLUSIONS

These mechanistic insights of macrophages in tumorigenesis offer valuable ideas for researchers. The identified natural products facilitate the selection of promising candidates for future cancer drug development.

Unlocking the potential of flavonoids: Natural solutions in the fight against colon cancer

Colorectal cancer (CRC) is a major cause of cancer-related deaths worldwide, underscoring the importance of understanding the diverse molecular and genetic underpinnings of CRC to improve its diagnosis, prognosis, and treatment. This review delves into the adenoma-carcinoma-metastasis model, emphasizing the "APC-KRAS-TP53" signature events in CRC development. CRC is categorized into four consensus molecular subtypes, each characterized by unique genetic alterations and responses to therapy, illustrating its complexity and heterogeneity. Furthermore, we explore the role of chronic inflammation and the gut microbiome in CRC progression, emphasizing the potential of targeting these factors for prevention and treatment. This review discusses the impact of dietary carcinogens and lifestyle factors and the critical role of early detection in improving outcomes, and also examines conventional chemotherapy options for CRC and associated challenges. There is significant focus on the therapeutic potential of flavonoids for CRC management, discussing various types of flavonoids, their sources, and mechanisms of action, including their antioxidant properties, modulation of cell signaling pathways, and effects on cell cycle and apoptosis. This article presents evidence of the synergistic effects of flavonoids with conventional cancer therapies and their role in modulating the gut microbiome and immune response, thereby offering new avenues for CRC treatment. We conclude by emphasizing the importance of a multidisciplinary approach to CRC research and treatment, incorporating insights from genetic, molecular, and lifestyle factors. Further research is needed on the preventive and therapeutic potential of natural compounds, such as flavonoids, in CRC, underscoring the need for personalized and targeted treatment strategies.

Isoliquiritigenin limits inflammasome activation of macrophage via docking into Syk to alleviate murine non-alcoholic fatty liver disease

Isoliquiritigenin (ISL) is a chalcone-type flavonoid derived from the root of licorice with antioxidant, anti-inflammatory, anti-tumour and neuroprotective properties. ISL has been proven to downregulate the productions of IL-1β, TNF-α and IL-6 by macrophages. However, detailed molecular mechanisms of this modulation remain elusive. Here, ISL suppressed Syk phosphorylation and CD80, CD86, IL-1β, TNF-α and IL-6 expressions in lipopolysaccharide-stimulated macrophages ex vivo. ApoC3-transgenic (ApoC3TG) mice had more activated macrophages. ISL was also able to downregulate the inflammatory activities of macrophages from ApoC3TG mice. Administration of ISL inhibited Syk activation and inflammatory activities of macrophages in ApoC3TG mice in vivo. The treatment of ISL further alleviated MCD-induced non-alcoholic fatty liver disease (NAFLD) in wild-type and ApoC3TG mice, accompanied by less recruitment and activation of liver macrophages. Due to the inhibition of Syk phosphorylation, ISL-treated macrophages displayed less production of cytoplasmic ROS, NLRP3, cleaved-GSDMD and cleaved-IL-1β, suggesting less inflammasome activation. Finally, the molecular docking study demonstrated that ISL bound to Syk directly with the Kd of 1.273 × 10-8 M. When the Syk expression was knocked down by its shRNA, the inhibitory effects of ISL on activated macrophages disappeared, indicating that Syk was at least one of key docking-molecules of ISL. Collectively, ISL could alleviate MCD-induced NAFLD in mice involved with the inhibition of macrophage inflammatory activity by the blockade of Syk-induced inflammasome activation.

Dietary flavonoids-microbiota crosstalk in intestinal inflammation and carcinogenesis

Colorectal cancer (CRC) is currently the third leading cancer and commonly develops from chronic intestinal inflammation. A strong association was found between gut microbiota and intestinal inflammation and carcinogenic risk. Flavonoids, which are abundant in vegetables and fruits, can inhibit inflammation, regulate gut microbiota, protect gut barrier integrity, and modulate immune cell function, thereby attenuating colitis and preventing carcinogenesis. Upon digestion, about 90% of flavonoids are transported to the colon without being absorbed in the small intestine. This phenomenon increases the abundance of beneficial bacteria and enhances the production of short-chain fatty acids. The gut microbe further metabolizes these flavonoids. Interestingly, some metabolites of flavonoids play crucial roles in anti-inflammation and anti-tumor effects. This review summarizes the modulatory effect of flavonoids on gut microbiota and their metabolism by intestinal microbe under disease conditions, including inflammatory bowel disease, colitis-associated cancer (CAC), and CRC. We focus on dietary flavonoids and microbial interactions in intestinal mucosal barriers as well as intestinal immune cells. Results provide novel insights to better understand the crosstalk between dietary flavonoids and gut microbiota and support the standpoint that dietary flavonoids prevent intestinal inflammation and carcinogenesis.

Roles of PPAR activation in cancer therapeutic resistance: Implications for combination therapy and drug development

Therapeutic resistance is a major obstacle to successful treatment or effective containment of cancer. Peroxisome proliferator-activated receptors (PPARs) play an essential role in regulating energy homeostasis and determining cell fate. Despite of the pleiotropic roles of PPARs in cancer, numerous studies have suggested their intricate relationship with therapeutic resistance in cancer. In this review, we provided an overview of the roles of excessively activated PPARs in promoting resistance to modern anti-cancer treatments, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The mechanisms through which activated PPARs contribute to therapeutic resistance in most cases include metabolic reprogramming, anti-oxidant defense, anti-apoptosis signaling, proliferation-promoting pathways, and induction of an immunosuppressive tumor microenvironment. In addition, we discussed the mechanisms through which activated PPARs lead to multidrug resistance in cancer, including drug efflux, epithelial-to-mesenchymal transition, and acquisition and maintenance of the cancer stem cell phenotype. Preliminary studies investigating the effect of combination therapies with PPAR antagonists have suggested the potential of these antagonists in reversing resistance and facilitating sustained cancer management. These findings will provide a valuable reference for further research on and clinical translation of PPAR-targeting treatment strategies.

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

Macrophage metabolism, phenotype, function, and therapy in hepatocellular carcinoma (HCC)

The pivotal role of the tumor microenvironment (TME) in the initiation and advancement of hepatocellular carcinoma (HCC) is widely acknowledged, as it fosters the proliferation and metastasis of HCC cells. Within the intricate TME of HCC, tumor-associated macrophages (TAMs) represent a significant constituent of non-malignant cells. TAMs engage in direct communication with cancer cells in HCC, while also exerting influence on other immune cells to adopt a tumor-supportive phenotype that facilitates tumor progression. Among the multifaceted mechanisms at play, the metabolic reprogramming of both tumor cells and macrophages leads to phenotypic alterations and functional modifications in macrophages. This comprehensive review elucidates the intricate interplay between cellular metabolism and macrophage phenotype/polarization, while also providing an overview of the associated signaling molecules and potential therapeutic strategies for HCC.

Diosmetin inhibits the growth and invasion of gastric cancer by interfering with M2 phenotype macrophage polarization

Overturning M2 phenotype macrophage polarization is a promising therapeutic strategy for gastric cancer (GC). Diosmetin (DIO) is a natural flavonoid with antitumor effect. The aim of this study was to investigate the effect of DIO on polarization of M2 phenotype macrophages in GC. THP-1 cells were induced to M2 phenotype macrophages and co-cultured with AGS cells. The effects of DIO were determined by flow cytometry, qRT-PCR, CCK-8, Transwell, and western blot. To explore the mechanisms, THP-1 cells were transfected with adenoviral vectors containing tumor necrosis factor receptor-associated factor 2 (TRAF2) or si-TRAF2. DIO (0, 5, 10, and 20 μM) restrained the M2 phenotype macrophage polarization. In addition, DIO (20 μM) reversed the increased viability and invasion of AGS cells induced by the co-culture of M2 macrophages. Mechanistically, TRAF2 knockdown inhibited the effect of M2 phenotype macrophages on AGS cells' growth and invasion. Furthermore, DIO (20 μM) was found to decrease TRAF2/NF-κB activity in GC cells. However, TRAF2 overexpressed reversed the inhibitory effect of DIO on the co-culture system. The in vivo study confirmed that DIO treatment (50 mg/kg) could repress the growth of GC. DIO treatment markedly reduced the expressions of Ki-67 and N-cadherin, and decreased the protein levels of TRAF2 and p-NF-κB/NF-κB. In conclusion, DIO inhibited the growth and invasion of GC cells by interfering with M2 phenotype macrophage polarization through repression of the TRAF2/NF-κB signaling pathway.

Chalcones and Gastrointestinal Cancers: Experimental Evidence

Colorectal (CRC) and gastric cancers (GC) are the most common digestive tract cancers with a high incidence rate worldwide. The current treatment including surgery, chemotherapy or radiotherapy has several limitations such as drug toxicity, cancer recurrence or drug resistance and thus it is a great challenge to discover an effective and safe therapy for CRC and GC. In the last decade, numerous phytochemicals and their synthetic analogs have attracted attention due to their anticancer effect and low organ toxicity. Chalcones, plant-derived polyphenols, received marked attention due to their biological activities as well as for relatively easy structural manipulation and synthesis of new chalcone derivatives. In this study, we discuss the mechanisms by which chalcones in both in vitro and in vivo conditions suppress cancer cell proliferation or cancer formation.

Roles of macrophages on ulcerative colitis and colitis-associated colorectal cancer

Colitis-associated colorectal cancer is the most serious complication of ulcerative colitis. Long-term chronic inflammation increases the incidence of CAC in UC patients. Compared with sporadic colorectal cancer, CAC means multiple lesions, worse pathological type and worse prognosis. Macrophage is a kind of innate immune cell, which play an important role both in inflammatory response and tumor immunity. Macrophages are polarized into two phenotypes under different conditions: M1 and M2. In UC, enhanced macrophage infiltration produces a large number of inflammatory cytokines, which promote tumorigenesis of UC. M1 polarization has an anti-tumor effect after CAC formation, whereas M2 polarization promotes tumor growth. M2 polarization plays a tumor-promoting role. Some drugs have been shown to that prevent and treat CAC effectively by targeting macrophages.

Phenolic Phytochemicals for Prevention and Treatment of Colorectal Cancer: A Critical Evaluation of In Vivo Studies

Colorectal cancer (CRC) is the third most diagnosed and second leading cause of cancer-related death worldwide. Limitations with existing treatment regimens have demanded the search for better treatment options. Different phytochemicals with promising anti-CRC activities have been reported, with the molecular mechanism of actions still emerging. This review aims to summarize recent progress on the study of natural phenolic compounds in ameliorating CRC using in vivo models. This review followed the guidelines of the Preferred Reporting Items for Systematic Reporting and Meta-Analysis. Information on the relevant topic was gathered by searching the PubMed, Scopus, ScienceDirect, and Web of Science databases using keywords, such as "colorectal cancer" AND "phenolic compounds", "colorectal cancer" AND "polyphenol", "colorectal cancer" AND "phenolic acids", "colorectal cancer" AND "flavonoids", "colorectal cancer" AND "stilbene", and "colorectal cancer" AND "lignan" from the reputed peer-reviewed journals published over the last 20 years. Publications that incorporated in vivo experimental designs and produced statistically significant results were considered for this review. Many of these polyphenols demonstrate anti-CRC activities by inhibiting key cellular factors. This inhibition has been demonstrated by antiapoptotic effects, antiproliferative effects, or by upregulating factors responsible for cell cycle arrest or cell death in various in vivo CRC models. Numerous studies from independent laboratories have highlighted different plant phenolic compounds for their anti-CRC activities. While promising anti-CRC activity in many of these agents has created interest in this area, in-depth mechanistic and well-designed clinical studies are needed to support the therapeutic use of these compounds for the prevention and treatment of CRC.

Network analysis and experimental pharmacology study explore the protective effects of Isoliquiritigenin on 5-fluorouracil-Induced intestinal mucositis

5-fluorouracil (5-FU) is one of the most widely used chemotherapy drugs for malignant tumors. However, intestinal mucositis caused by 5-FU is a severe dose-limiting toxic effect and even leads to treatment interruption. Isoliquiritigenin (ISL) is one of the main active compounds of licorice, which is a traditional Chinese herbal medicine commonly used in inflammation and gastrointestinal diseases. It is speculated that ISL have protective effects on intestinal mucositis. However, no such studies have been reported. Therefore, to investigate the impact of ISL on 5-Fu-induced intestinal mucositis, a strategy based on network prediction and pharmacological experimental validation was proposed in this study. Firstly, the targets and mechanism of ISL in alleviating 5-Fu-induced gastrointestinal toxicity were predicted by network analysis. And the results were further confirmed by molecular docking. Then, a mouse model of intestinal mucositis was established by intraperitoneal injection of 5-FU (384 μmol/kg) to verify the prediction of network analysis. The network analysis results suggested that PTGS2 (Prostaglandin G/H synthase 2) and NOS2 (Nitric oxide synthase, inducible) might be the critical targets of ISL for reducing the intestinal toxicity of 5-FU. In addition, KEGG and GO enrichment analysis revealed that the HIF-1, TNF, MAPK, IL-17, PI3K-Akt, Ras, NF-kappa B signaling pathway, and biological processes of the inflammatory response, apoptosis regulation, NO production and NF-kappa B transcription factor activity might be involved in the mechanism of ISL against intestinal mucositis. Subsequent animal experiments showed that ISL could reduce the weight loss, leukopenia and mucosal damage caused by 5-FU. Compared with the intestinal mucositis model, the protein expressions of PTGS2, NOS2, TNFα (Tumor necrosis factor-alpha) and NF-κB p65 (nuclear factor kappa-B P65) were decreased after ISL treatment. In conclusion, this study is the fist time to find that ISL can attenuate 5-FU-induced intestinal mucositis in mice. Its anti-mucositis effect may be through regulating TNF/NF-κB pathway and inhibiting inflammatory mediators PTGS2 and NOS2. It will provide a potential candidate for the prevention and treatment of chemotherapy-induced intestinal mucositis.

Preclinical studies of licorice in ulcerative colitis: A systematic review with meta-analysis and network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice, as a traditional Chinese herbal medicine, possessing the efficacies of invigorating spleen and replenishing qi, heat-clearing and detoxicating, phlegm-resolving and cough suppressant, relieving spasm and pain, and hamonizing actions of various medicines.

AIM OF THE STUDY

The goal of this systematic review, which includes meta-analysis and network pharmacology in preclinical studies, is to investigate the multiple efficacies of licorice on ulcerative colitis (UC).

MATERIALS AND METHODS

We searched several databases, e.g., Web of Science, Elsevier ScienceDirect and PubMed until Januanry 2022 for literature collection, and the Review Manager 5.3 was used to analyze the data. To synthesize the retrieved data, the fixed and random-effects models were utilized, respectively, and network pharmacology was applied to confirm the mechanisms.

RESULTS

Based on the result of meta-analysis, it suggested that the treatments of licorice extract and its active compounds showed strong therpeutic effects, which not only reflected the declining histological score, a index of the colitis severity [SMD = -2.86, 95% CI (-3.65, -2.08); P < 0.00001], but also reversed colonic shortness [WMD = 1.67, 95% CI (1.16, 2.19); P < 0.00001] between experimental UC model and licorice-treatment groups. In addition, it suggested the significant reduction of TNF-α level [SMD = -2.70, 95% CI (-3.23, -2.16); P < 0.00001], which acted as a crucial role in inflammatory response. Furthermore, from the results of network pharmacology, it indicated that anti-inflammation, anti-oxidative stress, immunomodulatory effect and microbiota homeostasis were the predominant therapeutic mechanisms of licorice extract and its active compounds treating UC.

CONCLUSION

This systematic review with meta-analysis and network pharmacology demonstrates an efficient role of licorice extract and its active compounds in preclinical studies of UC, which provides supporting evidence for clinical trial implementation. However, there exist some limitations, such as technique quality decificency, missed reports due to negative outcome, failure to calculate sample size, and the risk of bias.

Molecular and Cellular Mechanisms of Propolis and Its Polyphenolic Compounds against Cancer

In recent years, interest in natural products such as alternative sources of pharmaceuticals for numerous chronic diseases, including tumors, has been renewed. Propolis, a natural product collected by honeybees, and polyphenolic/flavonoid propolis-related components modulate all steps of the cancer progression process. Anticancer activity of propolis and its compounds relies on various mechanisms: cell-cycle arrest and attenuation of cancer cells proliferation, reduction in the number of cancer stem cells, induction of apoptosis, modulation of oncogene signaling pathways, inhibition of matrix metalloproteinases, prevention of metastasis, anti-angiogenesis, anti-inflammatory effects accompanied by the modulation of the tumor microenvironment (by modifying macrophage activation and polarization), epigenetic regulation, antiviral and bactericidal activities, modulation of gut microbiota, and attenuation of chemotherapy-induced deleterious side effects. Ingredients from propolis also "sensitize" cancer cells to chemotherapeutic agents, likely by blocking the activation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). In this review, we summarize the current knowledge related to the the effects of flavonoids and other polyphenolic compounds from propolis on tumor growth and metastasizing ability, and discuss possible molecular and cellular mechanisms involved in the modulation of inflammatory pathways and cellular processes that affect survival, proliferation, invasion, angiogenesis, and metastasis of the tumor.

Colon-specific delivery of isoliquiritigenin by oral edible zein/caseate nanocomplex for ulcerative colitis treatment

Although a natural anti-inflammatory ingredient, isoliquiritigenin (ISL), plays an effective role in ulcerative colitis (UC) treatment, a series of drawbacks still limit its clinical application, including the poor solubility, instability in gastrointestinal tract, and rapid elimination rate of ISL. Zein-based NPs display the benefits on drug loading and delivery, whereas with the poor stability. In this study, an edible nano-system composed by zein/caseinate complex was fabricated for the colon-targeting delivery of ISL, to improve its colon retention and anti-UC effects. The optimized ISL loaded zein/caseinate NPs (ISL@NPs) were prepared by single-factor design by anti-solvent precipitation method, and then characterized. The improved cellular uptake of ISL@NPs on NCM460 and RAW 264.7 cells was evaluated in vitro. The colon tissue permeability and retention capacity in vivo, and the anti-UC efficacy of ISL@NPs in DSS-induce UC were implemented. As a result, ISL@NPs with the high drug loading efficiency of 9.39% ± 0.26%, the average particle diameter of 137.32 ± 2.54 nm, exhibited the pH-sensitive stability in the different simulated gastrointestinal buffer. Compared with free ISL, ISL@NPs showed significantly higher cellular uptake ability in NCM460 and RAW 264.7 cells. Based on in vivo imaging system, zein/caseinate NPs showed the prolonged colonic retention and the enhanced penetration into the colonic epithelium. Finally, the oral administration of ISL@NPs could effectively alleviate the UC-related symptoms, down-regulate the production of pro-inflammatory factors, and reduce the infiltration of macrophages and neutrophils in colon tissues. In this study, an oral colon-specific nano-system, composed with the natural compound and edible materials, was developed as the promising alternatives in the prevention and treatment of UC.

Flavonoids regulate tumor-associated macrophages - From structure-activity relationship to clinical potential (Review)

In recent years, the strategy for tumor therapy has changed from focusing on the direct killing effect of different types of therapeutic agents on cancer cells to the new mainstream of multi-mode and -pathway combined interventions in the microenvironment of the developing tumor. Flavonoids, with unique tricyclic structures, have diverse and extensive immunomodulatory and anti-cancer activities in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant immunosuppressive cells in the TME. The regulation of macrophages to fight cancer is a promising immunotherapeutic strategy. This study covers the most comprehensive cognition of flavonoids in regulating TAMs so far. Far more than a simple list of studies, we try to dig out evidence of crosstalk at the molecular level between flavonoids and TAMs from literature, in order to discuss the most relevant chemical structure and its possible relationship with the multimodal pharmacological activity, as well as systematically build a structure-activity relationship between flavonoids and TAMs. Additionally, we point out the advantages of the macro-control of flavonoids in the TME and discuss the potential clinical implications as well as areas for future research of flavonoids in regulating TAMs. These results will provide hopeful directions for the research of antitumor drugs, while providing new ideas for the pharmaceutical industry to develop more effective forms of flavonoids.

Hybrid Membrane-Derived Nanoparticles for Isoliquiritin Enhanced Glioma Therapy

Due to the obstruction and heterogeneity of the blood-brain barrier, the clinical treatment of glioma has been extremely difficult. Isoliquiritigenin (ISL) exhibits antitumor effects, but its low solubility and bioavailability limit its application potential. Herein, we established a nanoscale hybrid membrane-derived system composed of erythrocytes and tumor cells. By encapsulating ISL in hybrid membrane nanoparticles, ISL is expected to be enhanced for the targeting and long-circulation in gliomas therapy. We fused erythrocytes with human glioma cells U251 and extracted the fusion membrane via hypotension, termed as hybrid membrane (HM). HM-camouflaged ISL nanoparticles (ISL@HM NPs) were prepared and featured with FT-IR, SEM, TEM, and DLS particle analysis. As the results concluded, the ISL active pharmaceutical ingredients (APIs) were successfully encapsulated with HM membranes, and the NPs loading efficiency was 38.9 ± 2.99% under maximum entrapment efficiency. By comparing the IC50 of free ISL and NPs, we verified that the solubility and antitumor effect of NPs was markedly enhanced. We also investigated the mechanism of the antitumor effect of ISL@HM NPs, which revealed a marked inhibition of tumor cell proliferation and promotion of senescence and apoptosis of tumor cells of the formulation. In addition, the FSC and WB results examined the effects of different concentrations of ISL@HM NPs on tumor cell disruption and apoptotic protein expression. Finally, it can be concluded that hybridized membrane-derived nanoparticles could prominently increase the solubility of insoluble materials (as ISL), and also enhance its targeting and antitumor effect.

Therapeutic Intervention in Cancer by Isoliquiritigenin from Licorice: A Natural Antioxidant and Redox Regulator

Oxidative stress could lead to a variety of body dysfunctions, including neurodegeneration and cancer, which are closely associated with intracellular signal transducers such as reactive oxygen species (ROS). It has been suggested that ROS is the upstream regulator of autophagy, and that it provides a negative feedback regulation to remove oxidative damage. Defects in the ROS-autophagic redox homeostasis could lead to the increased production of ROS and the accumulation of damaged organelles that in turn promote metabolic reprogramming and induce tumorigenesis. One significant characteristic of pancreatic cancer is the reprogramming of cellular energy metabolism, which facilitates the rapid growth, invasiveness, and the survival of cancer cells. Thus, the rectification of metabolic dysfunction is essential in therapeutic cancer targeting. Isoliquiritigenin (ISL) is a chalcone obtained from the plant Glycyrrhiza glabra, which is a powdered root licorice that has been consumed for centuries in different regions of the world. ISL is known to be a natural antioxidant that possesses diversified functions, including redox regulation in cells. This review contains discussions on the herbal source, biological properties, and anticancer potential of ISL. This is the first time that the anticancer activities of ISL in pancreatic cancer has been elucidated, with a coverage of the involvement of antioxidation, metabolic redox regulation, and autophagy in pancreatic cancer development. Furthermore, some remarks on related compounds of the isoflavonoid biosynthetic pathway of ISL will also be discussed.

Cellular Carcinogenesis: Role of Polarized Macrophages in Cancer Initiation

Simple Summary

Inflammation is a hallmark of many cancers. Macrophages are key participants in innate immunity and important drivers of inflammation. When chronically polarized beyond normal homeostatic responses to infection, injury, or aging, macrophages can express several pro-carcinogenic phenotypes. In this review, evidence supporting polarized macrophages as endogenous sources of carcinogenesis is discussed. In addition, the depletion or modulation of macrophages by small molecule inhibitors and probiotics are reviewed as emerging strategies in cancer prevention.

Abstract

Inflammation is an essential hallmark of cancer. Macrophages are key innate immune effector cells in chronic inflammation, parainflammation, and inflammaging. Parainflammation is a form of subclinical inflammation associated with a persistent DNA damage response. Inflammaging represents low-grade inflammation due to the dysregulation of innate and adaptive immune responses that occur with aging. Whether induced by infection, injury, or aging, immune dysregulation and chronic macrophage polarization contributes to cancer initiation through the production of proinflammatory chemokines/cytokines and genotoxins and by modulating immune surveillance. This review presents pre-clinical and clinical evidence for polarized macrophages as endogenous cellular carcinogens in the context of chronic inflammation, parainflammation, and inflammaging. Emerging strategies for cancer prevention, including small molecule inhibitors and probiotic approaches, that target macrophage function and phenotype are also discussed.

Can Natural Products be Used to Overcome the Limitations of Colorectal Cancer Immunotherapy?

Colorectal cancer (CRC) is a common cancer of the digestive system that endangers human health. Immunotherapy is widely used in the treatment of patients with cancer. Some patients with dMMR/MSI-H CRC benefit from treatments that use immune checkpoint inhibitors, but most CRC patients are not sensitive to immunotherapy. Furthermore, internal resistance and immune escape lead to a reduced immunotherapy response. Therefore, the development of an effective combination therapy to improve the response rate to immunotherapy is a goal of cancer research. Natural products are potential candidates for comprehensive cancer treatments due to their wide range of immunomodulatory effects through multifactorial underlying mechanisms. In this review, we summarize the challenges in the treatment of CRC and assess the immunomodulatory effects of natural products and their active components. Our work suggests that natural products represent potential options for combined CRC immunotherapy.

Research progress of phenolic compounds regulating IL-6 to exert antitumor effects

Cytokine therapy, which activates the host immune system, has become an important and novel therapeutic approach to treat various cancers. Recent studies have shown that IL-6 is an important cytokine that regulates the homeostasis in vivo. However, excessive IL-6 plays a pathological role in a variety of acute and chronic inflammatory diseases, especially in cancer. IL-6 can transmit signals through JAK/STAT, RAS /MAPK, PI3K/ Akt, NF-κB, and other pathways to promote cancer progression. Phenolic compounds can effectively regulate the level of IL-6 in tumor cells and improve the tumor microenvironment. This article focuses on the phenolic compounds through the regulation of IL-6, participate in the prevention of cancer, inhibit the proliferation of cancer cells, reduce angiogenesis, improve therapeutic efficacy, and reduce side effects and other aspects. This will help to further advance research on cytokine therapy to reduce the burden of cancer and improve patient prognosis. However, current studies are mostly limited to animal and cellular experiments, and high-quality clinical studies are needed to further determine their antitumor efficacy in humans.

Tumor Associated Macrophages, as the Dominant Immune Cells, Are an Indispensable Target for Immunologically Cold Tumor-Glioma Therapy?

Tumor microenvironment (TME) is the cornerstone of the occurrence, development, invasion and diffusion of the malignant central nerve system (CNS) tumor, glioma. As the largest number of inflammatory cells in glioma TME, tumor associated macrophages (TAMs) and their secreted factors are indispensable to the progression of glioma, which is a well-known immunologically “cold” tumor, including the growth of tumor cells, invasion, migration, angiogenesis, cancer immunosuppression and metabolism. TAMs intimately interface with the treatment failure and poor prognosis of glioma patients, and their density increases with increasing glioma grade. Recently, great progress has been made in TAM-targeting for anti-tumor therapy. According to TAMs’ function in tumorigenesis and progression, the major anti-tumor treatment strategies targeting TAMs are to hinder macrophage recruitment in TME, reduce TAMs viability or remodel TAMs phenotype from M2 to M1. Different approaches offer unique and effective anti-tumor effect by regulating the phagocytosis, polarization and pro-tumor behaviors of macrophages in the therapy of glioma. The present review summarizes the significant characteristics and related mechanisms of TAMs and addresses the related research progress on targeting TAMs in glioma.

Natural Products for Regulating Macrophages M2 Polarization

Macrophages M2 polarization have been taken as an anti-inflammatory progression during inflammation. Natural plant-derived products, with potential therapeutic and preventive activities against inflammatory diseases, have received increasing attention in recent years because of their whole regulative effects and specific pharmacological activities. However, the molecular mechanisms about how different kinds of natural compounds regulate macrophages polarization still unclear. Therefore, in the current review, we summarized the detailed research progress on the active compounds derived from herbal plants with regulating effects on macrophages, especially M2 polarization. These natural occurring compounds including flavonoids, terpenoids, glycosides, lignans, coumarins, alkaloids, polyphenols and quinones. In addition, we extensively discussed the cellular mechanisms underlying the M2 polarization for each compound, which could provide potential therapeutic strategies aiming macrophages M2 polarization.

Arachidonic Acid Metabolism Controls Macrophage Alternative Activation Through Regulating Oxidative Phosphorylation in PPARγ Dependent Manner

Macrophage polarization is mainly steered by metabolic reprogramming in the tissue microenvironment, thus leading to distinct outcomes of various diseases. However, the role of lipid metabolism in the regulation of macrophage alternative activation is incompletely understood. Using human THP-1 and mouse bone marrow derived macrophage polarization models, we revealed a pivotal role for arachidonic acid metabolism in determining the phenotype of M2 macrophages. We demonstrated that macrophage M2 polarization was inhibited by arachidonic acid, but inversely facilitated by its derived metabolite prostaglandin E2 (PGE2). Furthermore, PPARγ bridges these two seemingly unrelated processes via modulating oxidative phosphorylation (OXPHOS). Through inhibiting PPARγ, PGE2 enhanced OXPHOS, resulting in the alternative activation of macrophages, which was counterweighted by the activation of PPARγ. This connection between PGE2 biosynthesis and macrophage M2 polarization also existed in human and mouse esophageal squamous cell carcinoma. Our results highlight the critical role of arachidonic acid and metabolic PGE2 as immune regulators in modulating tissue homeostasis and pathological process.

Luteolin Promotes Apoptosis of Endometriotic Cells and Inhibits the Alternative Activation of Endometriosis-Associated Macrophages

Luteolin, a flavonoid present in several fruits, vegetables, nuts, and herbs reportedly exhibits anti-cancer and anti-inflammatory properties. However, the effect of luteolin on endometriosis, a painful condition characterized by the ectopic growth of endometrial tissue and pelvic inflammation, remains elusive. Herein, we observed that luteolin inhibited cell growth and induced apoptosis of 12Z human endometriotic cells by activating caspase-3, -8, and -9. Additionally, luteolin significantly inhibited the expression of key chemokines, C-C motif chemokine ligand 2 (CCL2) and CCL5, required for monocyte/macrophage influx at endometriotic sites. In macrophages stimulated by endometriotic cells, luteolin treatment suppressed the intracellular expression of M2 markers and endometriosis-promoting factors. Collectively, our data suggest that luteolin exerts anti-endometriotic effects by stimulating endometriotic cell apoptosis and hindering the alternative activation of macrophages.

Total Flavonoids of Glycyrrhiza uralensis Alleviates Irinotecan-Induced Colitis via Modification of Gut Microbiota and Fecal Metabolism

Irinotecan (CPT-11)-induced gastrointestinal toxicity strongly limits its anticancer efficacy. Glycyrrhiza uralensis Fisch., especially flavonoids, has strong anti-inflammatory and immunomodulatory activities. Herein, we investigate the protective effect of the total flavonoids of G. uralensis (TFGU) on CPT-11-induced colitis mice from the perspective of gut microbiota and fecal metabolism. The body weight and colon length of mice were measured. Our results showed that oral administration of TFGU significantly attenuated the loss of body weight and the shortening of colon length induced by CPT-11. The elevated disease activity index and histological score of colon as well as the up-regulated mRNA and protein levels of TNF-α, IL-1β, and IL-6 in the colonic tissue of CPT-11-treated mice were significantly decreased by TFGU. Meanwhile, TFGU restored the perturbed gut microbial structure and function in CPT-11-treated mice to near normal level. TFGU also effectively reversed the CPT-11-induced fecal metabolic disorders in mice, mainly call backing the hypoxanthine and uric acid in purine metabolism. Spearman's correlation analysis further revealed that Lactobacillus abundance negatively correlated with fecal uric acid concentration, suggesting the pivotal role of gut microbiota in CPT-11-induced colitis. Since uric acid is a ligand of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, TFGU was further validated to inhibit the activation of NLRP3 inflammasome by CPT-11. Our findings suggest TFGU can correct the overall gut microbial dysbiosis and fecal metabolic disorders in the CPT-11-induced colitis mice, underscoring the potential of using dietary G. uralensis as a chemotherapeutic adjuvant.

The role of tumor-associated macrophages (TAMs) in tumor progression and relevant advance in targeted therapy

Macrophages have a leading position in the tumor microenvironment (TME) which paves the way to carcinogenesis. Initially, monocytes and macrophages are recruited to the sites where the tumor develops. Under the guidance of different microenvironmental signals, macrophages would polarize into two functional phenotypes, named as classically activated macrophages (M1) and alternatively activated macrophages (M2). Contrary to the anti-tumor effect of M1, M2 exerts anti-inflammatory and tumorigenic characters. In progressive tumor, M2 tumor-associated macrophages (TAMs) are in the majority, being vital regulators reacting upon TME. This review elaborates on the role of TAMs in tumor progression. Furthermore, prospective macrophage-focused therapeutic strategies, including drugs not only in clinical trials but also at primary research stages, are summarized followed by a discussion about their clinical application values. Nanoparticulate systems with efficient drug delivery and improved antitumor effect are also summed up in this article.

Phytotherapy for Cachexia: Where Do We Stand?

Background

In contrast to Western medicine which currently offers no approved pharmacotherapy options for cachexia, in Japan multi-component extracts of medicinal plants are used with coverage by the national health insurance. This so called “Kampo” medicine is an example of the modern concept of multi-component/multi-target therapy. For the three traditional preparations Hochuekkito (補中益気湯), Juzentaihoto (十全大補湯), and Rikkunshito (六君子湯), a multitude of clinical research data relating to cachexia has been published. These preparations are also referred to as “Hozai” (補剤). A similar concept is found in Russian herbal medicine, where the term “Adaptogen” was coined for pharmacologically active substances which enhance adaptive stress repose.

Methods

Scientific literature—including original Japanese articles—was reviewed regarding the effects of these herbal preparations on cachexia. Cachexia is a complex set of symptoms including muscle atrophy with loss of weight, fatigue, and weakness.

Results

In a 1985 study by Kuroda et al., Hochuekkito showed efficacy in involuntary weight loss and fatigue in 63% of 162 patients with genitourinary cancer. For cancer-related fatigue, a significant improvement was reported within 2 weeks by Jeong et al. in 2010. In patients with chronic fatigue syndrome, Hochuekkito showed an overall improvement with 8–12 weeks of therapy in a 1997 study by Kuratsune et al. In a 2005 randomized placebo-controlled trial by Satoh et al. on 13 geriatric Q1 patients in a 16-week treatment protocol, Hochuekkito showed significant improvement of general health, physical functioning and the Profile of Mood States (POMS). In 71 geriatric COPD patients in a 2009 placebo-controlled randomized study, Tatsumi et al. found a significant body weight increase and a CRP, TNF-α, IL-6 decrease over 6 months of therapy. For Juzentaihoto in 48 hepatocellular carcinoma patients, Tsuchiya et al. 2008 documented a significantly longer recurrence-free survival (49 vs. 24 months) as compared to the control group (p=0.023). For the much simpler Rikkunshito prescription, a 2011 retrospective study by Fujitsuka et al. on 39 Stage III/IV pancreatic cancer patients treated with Gemcitabine (n=33) or Gemcitabine/Rikkunshito (n=6) showed a significantly prolonged median survival with 224 vs. 378.5 days (p < 0.05). In a 2011 open-label clinical study by Utumi et al. on geriatric cachexia in 6 dementia patients, treatment with Rikkunshito for 4 weeks resulted in a significant body weight increase. In all the above studies, the standardized dosage of 3x2.5 g/d extract granules for most Japanese health insurance-covered Kampo extract-preparations was applied.

Conclusion

As there is currently no accepted pharmacotherapy option for cachexia available in the West, a transfer of these East Asian gold standard prescriptions into the European market would be desirable. We were further able to demonstrate that the mTOR, interleucin, and melatonin pathways are modified by herbal compounds which thus counteract cachexia. More research in this field is urgently needed in order to provide new, effective treatments for cachexia patients.

Asaronic Acid Inhibited Glucose-Triggered M2-Phenotype Shift Through Disrupting the Formation of Coordinated Signaling of IL-4Rα-Tyk2-STAT6 and GLUT1-Akt-mTOR-AMPK

Macrophage polarization has been implicated in the pathogenesis of metabolic diseases such as obesity, diabetes, and atherosclerosis. Macrophages responsiveness to polarizing signals can result in their functional phenotype shifts. This study examined whether high glucose induced the functional transition of M2 macrophages, which was inhibited by asaronic acid, one of purple perilla constituents. J774A.1 murine macrophages were incubated with 40 ng/mL interleukin (IL)-4 or exposed to 33 mM glucose in the presence of 1-20 μΜ asaronic acid. In macrophages treated with IL-4 for 48 h, asaronic acid further accelerated cellular induction of the M2 markers of IL-10, arginase-1, CD163, and PPARγ via increased IL-4-IL-4Rα interaction and activated Tyk2-STAT6 pathway. Asaronic acid promoted angiogenic and proliferative capacity of M2-polarized macrophages, through increasing expression of VEGF, PDGF, and TGF-β. In glucose-loaded macrophages, there was cellular induction of IL-4, IL-4 Rα, arginase-1, and CD163, indicating that high glucose skewed naïve macrophages toward M2 phenotypes via an IL-4-IL-4Rα interaction. However, asaronic acid inhibited M2 polarization in diabetic macrophages in parallel with inactivation of Tyk2-STAT6 pathway and blockade of GLUT1-mediated metabolic pathway of Akt-mTOR-AMPKα. Consequently, asaronic acid deterred functional induction of COX-2, CTGF, α-SMA, SR-A, SR-B1, and ABCG1 in diabetic macrophages with M2 phenotype polarity. These results demonstrated that asaronic acid allayed glucose-activated M2-phenotype shift through disrupting coordinated signaling of IL-4Rα-Tyk2-STAT6 in parallel with GLUT1-Akt-mTOR-AMPK pathway. Thus, asaronic acid has therapeutic potential in combating diabetes-associated inflammation, fibrosis, and atherogenesis through inhibiting glucose-evoked M2 polarization.

Anticancer activities of phytoconstituents and their liposomal targeting strategies against tumor cells and the microenvironment

Various bioactive ingredients have been extracted from Chinese herbal medicines (CHMs) that affect tumor progression and metastasis. To further understand the mechanisms of CHMs in cancer therapy, this article summarizes the effects of five categories of CHMs and their active ingredients on tumor cells and the tumor microenvironment. Despite their treatment potential, the undesirable physicochemical properties (poor permeability, instability, high hydrophilicity or hydrophobicity, toxicity) and unwanted pharmacokinetic profiles (short half-life in blood and low bioavailability) restrict clinical studies of CHMs. Therefore, development of liposomes through relevant surface modifying techniques to achieve targeted CHM delivery for cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature, have been reviewed. Current challenges of liposomal targeting of these phytoconstituents and future perspective of CHM applications are discussed to provide an informative reference for interested readers.

β-Carotene exerts anti-colon cancer effects by regulating M2 macrophages and activated fibroblasts

The tumor microenvironment (TME), consisting of stromal fibroblasts, immune cells, cancer cells and other cell types, plays a crucial role in cancer progression and metastasis. M2 macrophages and activated fibroblasts (AFs) modulate behavior of cancer cells in the TME. Since nutritional effects on cancer progression, including colorectal cancer (CRC), may be mediated by alterations in the TME, we determined the ability of β-carotene (BC) to mediate anti-cancer effects through regulation of macrophage polarization and fibroblast activation in CRC. The M2 macrophage phenotype was induced by treating U937 cells with phorbol-12-myristate-13-acetate and interleukin (IL)-4. Treatment of these M2 macrophages with BC led to suppression of M2-type macrophage-associated markers and of the IL-6/STAT3 signaling pathway. In separate experiments, AFs were induced by treating CCD-18Co cells with transforming growth factor-β1. BC treatment suppressed expression of fibroblast activation markers. In addition, conditioned media from BC-treated M2 macrophages and AF inhibited cancer stem cell markers, colon cancer cell invasiveness and migration, and the epithelial-mesenchymal transition (EMT). In vivo, BC supplementation inhibited tumor formation and the expression of M2 macrophage markers in an azoxymethane/dextran sodium sulfate-induced colitis-associated CRC mouse model. To our knowledge, the present findings provide the first evidence suggesting that the potential therapeutic effects of BC on CRC are mediated by the inhibition of M2 macrophage polarization and fibroblast activation.

The active fraction of Garcinia yunnanensis suppresses the progression of colorectal carcinoma by interfering with tumorassociated macrophage-associated M2 macrophage polarization in vivo and in vitro

Colorectal cancer (CRC) is the third most common solid tumor worldwide and has shown resistance to several immunotherapies, particularly immune checkpoint blockade therapy, which is effective in many other types of cancer. Our previous studies indicated that the active fraction of Garcinia yunnanensis (YTE-17), had potent anticancer activities by regulating multiple signaling pathways. However, knowledge regarding the mechanism and effect of YTE-17 in the prevention of CRC is limited. This study tested the effects of YTE-17 on colon cancer development in vivo by using two murine models: the carcigenic azoxymethane/dextran sulfate sodium (AOM/DSS)-induced CRC model and a genetically induced model using Apc^Min/+ mice. Here, the tumor load, tumor number, histology, and even some oncogenes were used to evaluate the effect of YTE-17. The intragastric administration of YTE-17 for 12 weeks significantly decreased CRC incidence, tumor number and size, immunity, and some tumor-associated macrophage (TAM) markers, including CD206, Arg-1, IL-10, and TGF-β. Importantly, the macrophages depletion by clodronate (CEL) also played a role in reducing the tumor burden and inhibiting tumor development, which were not affected by YTE-17 in the Apc^Min/+ mice. Moreover, the YTE-17 treatment attenuated CRC cell growth in a co-culture system in the presence of macrophages. Consistently, YTE-17 effectively reduced the tumor burden and macrophage infiltration and enhanced immunity in the AOM/DSS and Apc^Min/+ colon tumor models. Altogether, we demonstrate that macrophages in the microenvironment may contribute to the development and progression of CRC cells and propose YTE-17 as a new potential drug option for the treatment of CRC.

Ligand-Mediated Targeting of Cytokine Interleukin-27 Enhances Its Bioactivity In Vivo

We have examined the role of a novel targeted cytokine, interleukin-27 (IL-27), modified at the C terminus with a dual targeting and therapeutic heptapeptide, in treating prostate cancer. IL-27 has shown promise in halting tumor growth and mediating tumor regression in several cancer models, including prostate cancer. We describe our findings on the effects of targeted IL-27 gene delivery on prostate cancer cells in vitro and in vivo and how the targeting enhances bioactivity of the IL-27 cytokine. We applied the IL-27 gene delivery protocol utilizing sonoporation (sonodelivery) with the goal of reducing prostate tumor growth in an immunocompetent TC2R C57/BL6 model. The reduction in tumor growth and effector cellular profiles implicate targeted IL-27 as more effective than an untargeted version of IL-27 in promoting bioactivity, as assessed by STAT1 and IFN-γ reporter genes. Moreover, enhanced antitumor effects and significantly higher accumulation of natural killer T (NKT) and CD8 effector cells in the tumors were observed. These results support a novel IL-27-based targeting strategy that is promising since it shows improved therapeutic efficacy while utilizing simple and effective sonodelivery methods.

Multi-walled carbon nanotubes exacerbate doxorubicin-induced cardiotoxicity by altering gut microbiota and pulmonary and colonic macrophage phenotype in mice

Epidemiologic studies show that the levels of air pollutants and particulate matter are positively associated with the morbidity and mortality of cardiovascular diseases. Here we demonstrate that the intratracheal instillation of multi-walled carbon nanotubes (MWCNTs), a standard fine particle, exacerbate doxorubicin (DOX)-induced cardiotoxicity in mice through altering gut microbiota and pulmonary and colonic macrophage phenotype. MWCNTs (25 μg/kg per day, 5 days a week for 3 weeks) promoted cardiotoxicity and apoptosis in the DOX (2 mg/kg, twice a week for 5 weeks)-treated C57BL/6 mice. MWCNTs exaggerated DOX-induced gut microbiota dysbiosis characterized by the increased abundances of Helicobacteraceae and Coriobacteriaceae. In addition, MWCNTs promoted DOX-induced M1-like polarization of colonic macrophages with an increase in TNF-α, IL-1β and CC chemokine ligand 2 in peripheral blood. Importantly, treatment with the antibiotics attenuated MWCNTs plus DOX-induced apoptosis of cardiomyocytes and M1-like polarization of colonic macrophages. The fecal microbiota transplantation demonstrated that MWCNTs exaggerated DOX-induced cardiotoxicity with M1-like polarization of colonic macrophages. The conditioned medium from MWCNTs-treated pulmonary macrophages promoted DOX-induced gut microbiota dysbiosis and colonic macrophage polarization. Furthermore, the co-culture of macrophages and fecal bacteria promoted M1-like macrophage polarization and their production of TNF-α and IL-1β, and thereby exacerbated the effects of MWCNTs. Moreover, IL-1β and TNF-α blockade, either alone or in combination attenuated MWCNTs-exacerbated cardiotoxicity. In summary, MWCNTs exacerbate DOX-induced cardiotoxicity in mice through gut microbiota and pulmonary and colonic macrophage interaction. Our findings identify a novel mechanism of action of inhaled particle-driven cardiotoxicity.

Phytochemical drug candidates for the modulation of peroxisome proliferator-activated receptor γ in inflammatory bowel diseases

Plant-based compounds or phytochemicals such as alkaloids, glycosides, flavonoids, volatile oils, tannins, resins, and polyphenols have been used extensively in traditional medicine for centuries and more recently in Western alternative medicine. Extensive evidence suggests that consumption of dietary polyphenolic compounds lowers the risk of inflammatory diseases. The anti-inflammatory properties of several phytochemicals are mediated through ligand-inducible peroxisome proliferator-activated receptors (PPARs), particularly the PPARγ transcription factor. Inflammatory bowel disease (IBD) is represented by ulcerative colitis, which occurs in the mucosa of the colon and rectum, and Crohn's disease (CD) that can involve any segment of gastrointestinal tract. Because of the lack of cost-effective pharmaceutical treatment options, many IBD patients seek and use alternative and unconventional therapies to alleviate their symptoms. PPARγ plays a role in the inhibition of inflammatory cytokine expression and activation of anti-inflammatory immune cells. The phytochemicals reported here are ligands that activate PPARγ, which in turn modulates inflammatory responses. PPARγ is highly expressed in the gut making it a potential therapeutic target for IBDs. This review summarizes the effects of the currently published phytochemicals that modulate the PPARγ pathway and reduce or eliminate colonic inflammation.

Effects of Steady Low-Intensity Exercise on High-Fat Diet Stimulated Breast Cancer Progression Via the Alteration of Macrophage Polarization

Physical inactivity and high-fat diet, especially high saturated fat containing diet are established risk factors for breast cancer that are amenable to intervention. High-fat diet has been shown to induce tumor growth and metastasis by alteration of inflammation but steady exercise has anti-tumorigenic effects. However, the mechanisms underlying the effects of physical activity on high-fat diet stimulated breast cancer initiation and progression are currently unclear. In this study, we examined how the intensity of physical activity influences high fat diet-stimulated breast cancer latency and progression outcomes, and the possible mechanisms behind these effects. Five-week-old female Balb/c mice were fed either a control diet or a high-fat diet for 8 weeks, and then 4T1 mouse mammary tumor cells were inoculated into the mammary fat pads. Exercise training occurred before tumor cell injection, and tumor latency and tumor volume were measured. Mice with a high-fat diet and low-intensity exercise (HFLE) had a longer tumor latency period, slower tumor growth, and smaller tumor volume in the final tumor assessment compared with the control, high-fat diet control (HFDC), and high-fat diet with moderate-intensity exercise (HFME) groups. Steady low- and moderate-intensity exercise had no effect on cell proliferation but induced apoptosis by activating caspase-3 through the alteration of Bcl-2, Bcl-xL, and Bax expression. Furthermore, steady exercise reduced M2 macrophage polarization in breast tumor tissue, which has been linked to tumor growth. The myokine, myostatin, reduced M2 macrophage polarization through the inhibition of the JAK-STAT signaling pathway. These results suggest that steady low-intensity exercise could delay breast cancer initiation and growth and reduce tumor volume through the induction of tumor cell apoptosis and the suppression of M2 macrophage polarization.

Asaronic Acid Attenuates Macrophage Activation toward M1 Phenotype through Inhibition of NF-κB Pathway and JAK-STAT Signaling in Glucose-Loaded Murine Macrophages

Macrophage polarization has been implicated in the pathogenesis of obesity and type 2 diabetes, which are recognized as chronic proinflammatory diseases. This study investigated that high level of glucose, similar to lipopolysaccharide (LPS), activated macrophages toward M1 phenotypes and 1-20 μM asaronic acid (AA) counteracted diabetic macrophage activation. AA reduced the LPS-promoted secretion of proinflammatory interleukin (IL)-6 and monocyte chemoattractant protein-1. The LPS markedly elevated the macrophage induction of the M1 markers of Toll-like receptor 4 (TLR4), CD36, and CD68, which was attenuated by AA. Also, the LPS significantly enhanced the nuclear factor (NF)-κB transactivation, signal transducers, and activators of transcription 1 (STAT1)/STAT3 activation and suppressor of cytokine signaling 3 (SOCS3) induction in macrophages. However, AA highly suppressed the aforementioned effects of LPS. Glucose-stimulated macrophages expressed advanced glycation end products (AGEs) and receptor for AGE (RAGE). Administration of 20 μM AA to macrophages partly but significantly attenuated such effects (1.65 ± 0.12 vs 0.95 ± 0.25 times glucose control for AGE; 2.33 ± 0.31 vs 1.40 ± 0.22 times glucose control for RAGE). Furthermore, glucose enhanced the macrophage induction of TLR4 and inducible nitric oxide synthase and IL-6 production, while it demoted the production of anti-inflammatory arginase-1 and IL-10. In contrast, AA reversed the induction of these markers in glucose-loaded macrophages. AA dose-dependently and significantly encumbered NF-κB transactivation, Janus kinase 2 (JAK2) and STAT1/STAT3 activation, and SOCS3 induction upregulated in glucose-supplemented macrophages. These results demonstrated for the first time that AA may limit diabetic macrophage activation toward the M1 phenotype through the inhibition of TLR4-/IL-6-mediated NF-κB/JAK2-STAT signaling entailing AGE-RAGE interaction.

Salivary Glycine Is a Significant Predictor for the Attenuation of Polyp and Tumor Microenvironment Formation by Fucoxanthin in AOM/DSS Mice

Background/ Aim: A high polar xanthophyll of Fucoxanthin (Fx) is abundantly contained in edible brown algae, and it has chemopreventive effects in mouse cancer models, however, the underlying mechanisms of these effects are not well understood. Thus, we aimed to investigate the effects of Fx on the tumor microenvironment in cancer model mice.

MATERIALS AND METHODS

We investigated the effect of Fx (30 mg/kg body weight) in a variety of cell types within the tumor microenvironment of α mouse preclinical colorectal cancer model and analyzed the mouse saliva in search of predictors for cancer chemopreventive effects.

RESULTS

Fx administration significantly decreased the number of colorectal polyps and tended to decrease colonic lesions compared to untreated control mice. In addition, Fx administration showed significantly lower numbers of colorectal cancer stem cells-like CD44^high/EpCAM^high cells, cancer-associated fibroblasts-like αSMA^high cells, tumor-associated macrophages-like and dendritic cells-like CD206^high cells by 0.6-, 0.5- and 0.6-fold, respectively, compared to untreated control mice. Moreover, the treatment also showed significantly lower levels of salivary glycine by 0.5-fold.

CONCLUSION

Our results suggest that salivary glycine may be a predictor representing the chemopreventive effect of Fx in mice.

M1 and M2 macrophage polarization and potentially therapeutic naturally occurring compounds

Macrophages, as crucial cellular components of innate immunity, are characterized by possessing high plasticity and an abnormal ability to differentiate in response to numerous stimuli. Given this, macrophages show extreme heterogeneity under both physiological and pathological conditions. Typically, macrophages can be polarized into classically activated macrophages (M1) and alternatively activated macrophages (M2) depending on their environment. The relative functions of these two subtypes are almost exactly opposed to one another. Recent studies have suggested that some naturally occurring compounds can exert regulatory effects on the progression of macrophage polarization, which implies that they could be promising therapeutic tools to treat relevant diseases. Therefore, in our current review, we summarize recent studies on several naturally occurring compounds that may possess the ability to regulate macrophage polarization and explore the associated molecular mechanisms.

Isoliquiritigenin attenuates spinal tuberculosis through inhibiting immune response in a New Zealand white rabbit model

Spinal tuberculosis (ST) is the tuberculosis caused by Mycobacterium tuberculosis (Mtb) infections in spinal curds. Isoliquiritigenin 4,2′,4′-trihydroxychalcone, ISL) is an anti-inflammatory flavonoid derived from licorice (Glycyrrhiza uralensis), a Chinese traditional medicine. In this study, we evaluated the potential of ISL in treating ST in New Zealand white rabbit models. In the model, rabbits (n=40) were infected with Mtb strain H37Rv or not in their 6^th lumbar vertebral bodies. Since the day of infection, rabbits were treated with 20 mg/kg and 100 mg/kg of ISL respectively. After 10 weeks of treatments, the adjacent vertebral bone tissues of rabbits were analyzed through Hematoxylin-Eosin staining. The relative expression of Monocyte chemoattractant protein-1 (MCP-1/CCL2), transcription factor κB (NF-κB) p65 in lymphocytes were verified through reverse transcription quantitative real-time PCR (RT-qPCR), western blotting and enzyme-linked immunosorbent assays (ELISA). The serum level of interleukin (IL)-2, IL-4, IL-10 and interferon γ (IFN-γ) were evaluated through ELISA. The effects of ISL on the phosphorylation of IκBα, IKKα/β and p65 in NF-κB signaling pathways were assessed through western blotting. In the results, ISL has been shown to effectively attenuate the granulation inside adjacent vertebral tissues. The relative level of MCP-1, p65 and IL-4 and IL-10 were retrieved. NF-κB signaling was inhibited, in which the phosphorylation of p65, IκBα and IKKα/β were suppressed whereas the level of IκBα were elevated. In conclusion, ISL might be an effective drug that inhibited the formation of granulomas through downregulating MCP-1, NF-κB, IL-4 and IL-10 in treating ST.

IL-6 family cytokines: Key inflammatory mediators as biomarkers and potential therapeutic targets

IL-6 is a critical cytokine in acute phase response and involved in the pathogenesis of several chronic inflammatory diseases including cancer. Studies have highlighted that levels of IL-6 and its family members can be useful for diagnosis, prognosis of relapse-free survival and recurrence. IL-6 family cytokines have been identified as cancer biomarkers through screening of inflammatory mediators in different fluids including saliva, serum, and bronchoalveolar lavage fluid (BALF). IL-6 can be modulated by chemopreventive drugs, small molecules, monoclonal antibodies and immune checkpoint inhibitors. Unveiling the different sources of IL-6, the interaction between IL-6 and its cellular targets, the IL-6-dependent tumor resistance mechanisms, and the identification of novel regulators of IL-6 are some of the highly complex topics included in this review and their understanding could aid cancer biomarkers and therapy development.

Isoliquiritigenin decreases the incidence of colitis-associated colorectal cancer by modulating the intestinal microbiota

Imbalances in intestinal bacteria correlate with colitis-associated colorectal cancer (CAC). Traditional Chinese medicines have been used to adjust the gut microbiota, and isoliquiritigenin (ISL), a flavonoid extracted from licorice, has shown antitumor efficacy. In this study, the effects of ISL on CAC development and the gut microbiota were evaluated using an azoxymethane and dextran sulphate sodium (AOM/DSS)-induced mouse model of CAC (CACM). Histopathological analysis suggested that ISL reduced tumor incidence in vivo. Moreover, high-throughput sequencing and terminal restriction fragment length polymorphism (T-RFLP) studies of the bacterial 16S rRNA gene revealed that the structure of the gut microbial community shifted significantly following AOM/DSS treatment, and that effect was alleviated by treatment with high-dose ISL (150 mg/kg). Compared to the microbiota in the control mice (CK), the levels of Bacteroidetes decreased and the levels of Firmicutes increased during CAC development. ISL reversed the imbalance at the phylum level and altered the familial constituents of the gut microbiota. Specifically, the abundance of Helicobacteraceae increased after treatment with high-dose ISL, while the abundance of Lachnospiraceae and Rikenellaceae decreased. At the genus level, ISL reduced the abundance of opportunistic pathogens (Escherichia and Enterococcus), and increased the levels of probiotics, particularly butyrate-producing bacteria (Butyricicoccus, Clostridium, and Ruminococcus). Thus, ISL protects mice from AOM/DSS-induced CAC, and ISL and the gut microbiota may have synergistic anti-cancer effects.

Melanoma exosomes promote mixed M1 and M2 macrophage polarization

Macrophages are key participants in melanoma growth and survival. In general, macrophages can be classified as M1 or M2 activation phenotypes. Increasing evidence demonstrates that melanoma exosomes also facilitate tumor survival and metastasis. However, the role of melanoma exosomes in directly influencing macrophage function is poorly understood. Herein, we investigated the hypothesis that natural melanoma exosomes might directly influence macrophage polarization. To explore this hypothesis, ELISA, RT-qPCR, and macrophage functional studies were performed in vitro using an established source of melanoma exosomes (B16-F10). ELISA results for melanoma exosome induction of common M1 and M2 cytokines in RAW 264.7 macrophages, revealed that melanoma exosomes do not polarize macrophages exclusively in the M1 or M2 direction. Melanoma exosomes induced the M1 and M2 representative cytokines TNF-α and IL-10 respectively. Further assessment, using an RT-qPCR array with RAW 264.7 and primary macrophages, confirmed and extended the ELISA findings. Upregulation of markers common to both M1 and M2 polarization phenotypes included CCL22, IL-12B, IL-1β, IL-6, i-NOS, and TNF-α. The M2 cytokine TGF-β was upregulated in primary but not RAW 264.7 macrophages. Pro-tumor functions have been attributed to each of these markers. Macrophage functional assays demonstrated a trend toward increased i-NOS (M1) to arginase (M2) activity. Collectively, the results provide the first evidence that melanoma exosomes can induce a mixed M1 and M2 pro-tumor macrophage activation phenotype.

Macrophage depletion using clodronate liposomes decreases tumorigenesis and alters gut microbiota in the AOM/DSS mouse model of colon cancer

We examined the role of macrophages in inflammation associated with colorectal cancer (CRC). Given the emerging evidence on immune-microbiota interactions in CRC, we also sought to examine the interaction between macrophages and gut microbiota. To induce CRC, male C57BL/6 mice ( n = 32) received a single injection of azoxymethane (AOM), followed by three cycles of dextran sodium sulfate (DSS)-supplemented water in weeks 1, 4, and 7. Prior to the final DSS cycle ( week 7) and twice weekly until euthanasia, mice ( n = 16/group) received either 200 μl ip of clodronate-filled liposomes (CLD) or phosphate-buffered saline (PBS) encapsulated liposomes to deplete macrophages. Colon tissue was analyzed for polyp burden, macrophage markers, transcription factors, and inflammatory mediators. Stool samples were collected, and DNA was isolated and subsequently sequenced for 16S rRNA. Clodronate liposomes decreased tumor number by ∼36% and specifically large (≥1 mm) tumors by ∼36% ( P < 0.05). This was consistent with a decrease in gene expression of EMR1 in the colon tissue and polyp tissue as well as expression of select markers associated with M1 (IL-6) and M2 macrophages (IL-13, IL-10, TGFβ, CCL17) in the colon tissue ( P < 0.05). Similarly, there was a decrease in STAT3 and p38 MAPK and ERK signaling in colon tissue. Clodronate liposomes increased the relative abundance of the Firmicutes phylum ( P < 0.05) and specifically Lactobacillaceae and Clostridiaceae families, which have been associated with reduced CRC risk. Overall, these data support the development of therapeutic strategies to target macrophages in CRC and provide support for further evaluation of immune-microbiota interactions in CRC. NEW & NOTEWORTHY We found that macrophage depletion during late-stage tumorigenesis is effective at reducing tumor growth. This was associated with a decrease in macrophage markers and chemokines in the colon tissue and a decrease in transcription factors that are linked to colorectal cancer. The macrophage-depleted group was found to have an increased abundance of Firmicutes, a phylum with documented anti-tumorigenic effects. Overall, these data support the development of therapeutic strategies to target macrophages in colorectal cancer.

Immunolocalization of CD163+ Tumor-Associated Macrophages and Symmetric Proliferation of Ki-67 as Biomarkers to Differentiate New Different Grades of Laryngeal Dysplasia

OBJECTIVES

To evaluate CD163+ tumor-associated macrophages (TAMs), Ki-67, and cyclin D1 to differentiate laryngeal dysplasia in the 2017 World Health Organization classification.

METHODS

Immunohistochemistry for CD163, Ki-67, and cyclin D1 was performed using paraffin-embedded specimens. CD163+ TAMs infiltrating the epithelium were estimated. Ki-67 and cyclin D1 were evaluated in four parts of the epithelium-basal, parabasal, middle third, and upper third layers.

RESULTS

In total, 133 specimens were analyzed, including low-grade dysplasia (n = 31), high-grade dysplasia (n = 49), carcinoma in situ (n = 23), and normal mucosa (n = 30). CD163+ TAMs infiltrating the epithelium were significantly higher in high-grade dysplasia than in low-grade dysplasia. In the basal layer, Ki-67+ and cyclin D1+ cells were overexpressed in high-grade dysplasia (P < .0001). The area under the curve was 0.958 for Ki-67 and 0.909 for CD163+ TAMs (P < .0001).

CONCLUSIONS

CD163+ TAMs infiltrating the epithelium and Ki-67 overexpression in the basal layer may serve as biomarkers to differentiate low-grade dysplasia from high-grade dysplasia of the larynx. A symmetric proliferative pattern was observed during laryngeal carcinogenesis following Ki-67 overexpression.

Anthocyanins/anthocyanidins and colorectal cancer: What is behind the scenes?

Colorectal cancer (CRC) is one of the most common cause of cancer death. Phytochemicals, especially anthocyanins/anthocyanidins (A/A), have gathered attention of the scientific community owing to their anti-inflammatory, antioxidant, and cancer-inhibitory properties. In this review, we discussed the possible mechanisms whereby A/A exhibit intestinal anticarcinogenic characteristics. Anthocyanins/anthocyanidins inhibit the pro-inflammatory NF-κB pathway, attenuate Wnt signaling and suppress abnormal epithelial cell proliferation. In addition, A/A induce mitochondrial-mediated apoptosis and downregulate Akt/mTOR (mammalian target of rapamycin) pathway. Furthermore, activation of AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1) also contributes to the anti-carcinogenic effects of A/A. Finally, downregulation of metalloproteinases (MMPs) by A/A inhibits tumor invasion and metastasis. In conclusion, A/A exert their anti-tumor effects against colorectal carcinogenesis via multiple mechanisms, providing insights into the use of A/A as a natural chemopreventive intervention on major colorectal carcinogenesis.

Targeting tumor-associated macrophages by anti-tumor Chinese materia medica

Tumor-associated macrophages (TAMs) play a key role in all stages of tumorigenesis and tumor progression. TAMs secrete different kinds of cytokines, chemokines, and enzymes to affect the progression, metastasis, and resistance to therapy depending on their state of reprogramming. Therapeutic benefit in targeting TAMs suggests that macrophages are attractive targets for cancer treatment. Chinese materia medica (CMM) is an important approach for treating cancer in China and in the Asian region. According to the theory of Chinese medicine (CM) and its practice, some prescriptions of CM regulate the body's internal environment possibly including the remodeling the tumor microenvironment (TME). Here we briefly summarize the pivotal effects of TAMs in shaping the TME and promoting tumorigenesis, invasion, metastasis and immunosuppression. Furthermore, we illustrate the effects and mechanisms of CMM targeting TAMs in antitumor therapy. Finally, we reveal the CMM's dual-regulatory and multi-targeting functions on regulating TAMs, and hopefully, provide the theoretical basis for CMM clinical practice related to cancer therapy.