Cyclic sulfur compounds targeting macrophage polarization into M2/protumor phenotype and their anti-tumor effects.

Tumor-associated macrophages (TAMs), especially the M2-like phenotype, promote tumor progression, making them candidate targets for anti-tumor therapy. We previously discovered a cyclic sulfur compound, Onionin A (ONA), which suppresses tumor progression by inhibiting the M2-polarization of TAMs. In the present study, we sought to find new candidate compounds possessing a stronger effect compared to ONA by exploring compounds with structures similar to those of ONA among several cyclic sulfur compounds. A total of 81 cyclic sulfur compounds were screened, and their effects on macrophage polarization toward an M2-like phenotype were tested using human monocyte-derived macrophages (HMDMs). The anti-tumor effects of the identified candidate compounds were examined in a tumor-bearing mouse model. Three candidate compounds inhibited both IL-10- and tumor culture supernatant (TCS)-induced M2-polarization of HMDMs. These compounds also suppressed STAT3 activation in HMDMs stimulated by IL-10 and TCS, whereas these compounds had no effect on STAT3 activation in tumor cells. Furthermore, these compounds inhibited tumor cell proliferation under co-culture conditions with HMDMs, indicating that the three candidate compounds suppress tumor proliferation by regulating cell-cell interactions between tumor cells and macrophages. In addition, two of these candidate compounds had inhibitory effects on tumor growth and lung metastasis in the LM8 tumor-bearing mouse model. Our study identified new candidate cyclic sulfur compounds for anti-tumor therapy targeting the M2-polarization of TAMs.

Mast cell histamine-mediated transient inflammation following exposure to nickel promotes nickel allergy in mice.

We previously reported that allergic responses to nickel (Ni) were minimal in mice deficient in the histamine-forming enzyme histidine decarboxylase (HDC-KO), suggesting an involvement of histamine in allergic responses to Ni. However, it remains unclear how histamine is involved in the process of Ni allergy. Here, we examined the role of histamine in Ni allergy using a murine model previously established by us. Mice were sensitized to Ni by intraperitoneal injection of a NiCl2 -lipopolysaccharide (LPS) mixture. Ten days later, allergic inflammation was elicited by challenging ear-pinnas intradermally with NiCl2 . Then, ear-swelling was measured. Pyrilamine (histamine H1-receptor antagonist) or cromoglicate (mast cell stabilizer) was intravenously injected 1 h before the sensitization or the challenge. In cell-transfer experiments, spleen cells from Ni-sensitized donor mice were intravenously transferred into non-sensitized recipient mice. In both sensitized and non-sensitized mice, 1 mm or more NiCl2 (injected into ear-pinnas) induced transient non-allergic inflammation (Ni-TI) with accompanying mast cell degranulation. LPS did not affect the magnitude of this Ni-TI. Pyrilamine and cromoglicate reduced either the Ni-TI or the ensuing allergic inflammation when administered before Ni-TI (at either the sensitization or elicitation step), but not if administered when the Ni-TI had subsided. Experiments on HDC-KO and H1-receptor-KO mice, and also cell-transfer experiments using these mice, demonstrated histamine's involvement in both the sensitization and elicitation steps. These results suggest that mast cell histamine-mediated Ni-TI promotes subsequent allergic inflammatory responses to Ni, raising the possibility that control of Ni-TI by drugs may be effective at preventing or reducing Ni allergy.

Glucagon-like peptide-1 (GLP-1) induces M2 polarization of human macrophages via STAT3 activation.

It is known that glucagon-like peptide-1 (GLP-1) is a hormone secreted postprandially from the L-cells of the small intestine and regulates glucose homeostasis. GLP-1 is now used for the treatment of diabetes because of its beneficial role against insulin resistance. The GLP-1 receptor (GLP-1R) is expressed on many cell types, including macrophages, and GLP-1 suppresses the development of atherosclerosis by inhibiting macrophage function. However, there have so far been few studies that have investigated the significance of GLP-1/GLP-1R signaling in macrophage activation. In the present study, we examined the effect of GLP-1 and exenatide, a GLP-1R agonist, on human monocyte-derived macrophage (HMDM) activation. We found that GLP-1 induced signal transducer and activator of transcription 3 (STAT3) activation. Silencing of GLP-1R suppressed the GLP-1-induced STAT3 activation. In addition, alternatively activated (M2) macrophage-related molecules, such as IL-10, CD163, and CD204 in HMDM, were significantly upregulated by GLP-1. Furthermore, the co-culture of 3T3-L1 adipocytes with GLP-1-treated RAW 264.7 macrophages increased the secretion of adiponectin compared to co-culture of the 3T3-L1 adipocytes with untreated RAW 264.7 macrophages. Our results demonstrate that GLP-1 induces macrophage polarization toward the M2 phenotype, which may contribute to the protective effects of GLP-1 against diabetes and cardiovascular diseases.

Flavonoid Compounds Contained in Epimedii Herba Inhibit Tumor Progression by Suppressing STAT3 Activation in the Tumor Microenvironment.

M2-like tumor-associated macrophages (TAMs) in the tumor tissues promote tumor progression by various mechanisms and represent possible targets of antitumor therapy. In the present study, we tested whether compounds from Epimedii Herba inhibit macrophage polarization to the M2/protumorigenic phenotype and prevent tumor progression, using human monocyte-derived macrophages (HMDMs) and an animal sarcoma model. Four Epimedii Herba-derived flavonoid compounds, namely, limonianin, epimedokoreanin B, icaritin, and desmethylicaritin, inhibited CD163 expression and interleukin (IL)-10 production, which are known M2 markers, suggesting that these compounds inhibit M2 polarization. Among these compounds, epimedokoreanin B and limonianin suppressed STAT3 activation in HMDMs. Notably, epimedokoreanin B also suppressed cell proliferation by blocking STAT3 activation in Saos-2 human sarcoma and LM8 mouse sarcoma cell lines. Furthermore, oral administration of epimedokoreanin B inhibited tumor growth in an LM8 tumor-bearing murine model. These results indicate that Epimedii Herba and Epimedii Herba-derived compounds, such as epimedokoreanin B, may be potentially new agents that can be used for the treatment and prevention of various malignant tumors. They may also be promising compounds for targeting the tumor microenvironment by inhibiting M2 polarization of the TAMs.

CD163 deficiency facilitates lipopolysaccharide-induced inflammatory responses and endotoxin shock in mice.

OBJECTIVES: Septic (or endotoxin) shock is a severe systemic inflammatory disease caused by bacteraemia or endotoxaemia. Although it is known that increased serum levels of CD163 are observed in septic/endotoxin shock patients, the exact function and significance of CD163 in macrophage activation remain unclear. Therefore, in the current study, we tested whether CD163 contributes to the pathogenesis of endotoxin shock in mice. METHODS AND RESULTS: In samples obtained from autopsy, the number of CD163-positive macrophages was increased in the kidney, liver, heart, bone marrow and spleen of patients who had died from septic/endotoxin shock when compared to patients who had died from other causes. The animal study revealed a significantly lower survival rate in CD163-deficient mice after lipopolysaccharide (LPS) injection. Several cytokines and oxidative stress-related molecules were significantly elevated in the sera of LPS-induced endotoxin shock mice models. Higher concentrations of IL-6, TNF-α, IL-1ß, nitrite ( NO 2 - ) and nitrate ( NO 3 - ) and a lower concentration of IL-10 were observed in CD163-deficient mice treated with LPS. Similar results were observed in CD163-deficient LPS-stimulated macrophages. Furthermore, in an antitype II collagen antibody-induced arthritis (CAIA), rheumatoid arthritis model, inflammation and bone erosion scores as well as the expression of IL-6 and IL-1ß were significantly increased in CD163-deficient mice. CONCLUSIONS: CD163 was suggested to be involved in the regulation of inflammatory cytokine expression in septic/endotoxin shock and CAIA.

CD163 Is Required for Protumoral Activation of Macrophages in Human and Murine Sarcoma.

Recent findings have shown the significance of CD163-positive macrophages in tumor progression, yet there have been few studies on the function of CD163 in macrophages. Here, we uncover the role of CD163 in macrophage activation using CD163-deficient mice and human samples. We detected CD163 in 62 undifferentiated pleomorphic sarcoma samples, in which a high percentage of CD163-positive macrophages was associated with decreased overall survival and higher histologic grade. We observed macrophage-induced tumor cell proliferation in cocultures of human monocyte-derived macrophages and leiomyosarcoma (TYLMS-1) and myxofibrosarcoma (NMFH-1) cell lines, which was abrogated by silencing of CD163. Tumor development of sarcoma (MCA205 and LM8) cells in CD163-deficient mice was significantly abrogated in comparison with wild-type (WT) mice. Coculture with WT peritoneal macrophages significantly increased proliferation of MCA205 cells but decreased in the presence of CD163-deficient macrophages. Production of IL6 and CXCL2 in CD163-deficient macrophages was suppressed in comparison with WT macrophages, and overexpression of CD163 in CD163-deficient macrophages induced production of IL6 and CXCL2. Silencing of IL6 but not CXCL2 abrogated macrophage-induced proliferation of MCA205 cells. Taken together, our results show that CD163 is involved in protumoral activation of macrophages and subsequent development and progression of tumors in mice and humans.Significance: Macrophage CD163-mediated induction of IL6 promotes tumor development and progression in murine and human malignant tumors. Cancer Res; 78(12); 3255-66. ©2018 AACR.

Contribution of Macrophage Polarization to Metabolic Diseases.

Macrophage activation is one of the major immunological events in the pathogenesis of various diseases. Recent studies have disclosed that complicated mechanisms are involved in macrophage activation and polarization, and many published research articles have been based on the M1/M2 polarization concept. It is considered that M1- and M2-like macrophages are associated with T helper (Th)1-type and Th2-type immune responses, respectively, via several immune mediators. In this article, we summarize the correlations between macrophage polarization and metabolic disorders in both humans and mice and discuss the contribution of macrophage polarization to the pathogenic process of metabolic diseases.

Onionin A, a sulfur-containing compound isolated from onions, impairs tumor development and lung metastasis by inhibiting the protumoral and immunosuppressive functions of myeloid cells.

SCOPE: Recent studies have demonstrated that myeloid lineage cells, such as macrophages and myeloid suppressor cells (MDSCs), are major components exhibiting protumoral functions in the setting of tumor progression. Tumor-associated macrophages polarized to the protumoral M2 phenotype promote tumor proliferation and are considered to be a therapeutic target in patients with malignant tumors. METHODS AND RESULTS: We identified a new candidate compound, called onionin A (ONA) isolated from onions, that inhibits macrophage polarization into the M2 phenotype, as well as the immunosuppressive activity of MDSCs and tumor proliferation, by suppressing signal transducer and activator of transcription-3 (Stat3) activation. Furthermore, ONA administration was found to significantly suppress subcutaneous tumor development and lung metastasis in tumor-bearing mice. ONA administration also inhibited Stat3 activation and increased the number of infiltrating lymphocytes in tumor tissues, and an ex vivo analysis showed that the immunosuppressive effect of MDSCs in tumor-bearing mice is impaired by ONA. Moreover, ONA regulated tumor proliferation by inhibiting cell-cell interactions between macrophages and tumor cells, and ONA administration enhanced the antitumor effects of cisplatin in the tumor-bearing mice. CONCLUSIONS: These findings demonstrate that ONA may be a potential new tool for antitumor therapy and also for tumor prevention.

Onionin A inhibits ovarian cancer progression by suppressing cancer cell proliferation and the protumour function of macrophages.

It is well known that tumour-associated macrophages (TAMs) play an important role in tumour development by modulating the tumour microenvironment, and targeting of protumour activation or the M2 polarization of TAMs is expected to be an effective therapy for cancer patients. We previously demonstrated that onionin A (ONA), a natural low molecular weight compound isolated from onions, has an inhibitory effect on M2 macrophage polarization. In the present study, we investigated whether ONA had a therapeutic anti-ovarian cancer effect using in vitro and in vivo studies. We found that ONA reduced the extent of ovarian cancer cell proliferation induced by co-culture with human macrophages. In addition, we also found that ONA directly suppressed cancer cell proliferation. A combinatorial effect with ONA and anti-cancer drugs was also observed. The activation of signal transducer and activator of transcription 3 (STAT3), which is involved in cell proliferation and chemo-resistance, was significantly abrogated by ONA in ovarian cancer cells. Furthermore, the administration of ONA suppressed cancer progression and prolonged the survival time in a murine ovarian cancer model under single and combined treatment conditions. Thus, ONA is considered useful for the additional treatment of patients with ovarian cancer owing to its suppression of the protumour activation of TAMs and direct cytotoxicity against cancer cells.