Alternatively activated RAW264.7 macrophages enhance tumor lymphangiogenesis in mouse lung adenocarcinoma

M1 macrophages as promising agents for cell therapy of endometriosis

Endometriosis is a chronic estrogen-dependent disease characterized by the presence of endometrial glands and stroma outside their normal anatomical location. While laparoscopic removal of foci remains the gold standard therapy, it has limited efficacy and certain risks. However, cell therapy using pro-inflammatory M1 macrophages presents a promising and minimally invasive alternative for treating endometriosis. This approach showcases the potential for innovative and effective treatments for this condition. This study aims to explore the anti-endometriosis properties of M1 macrophages. A reproducible syngeneic mouse model of endometriosis was utilized, revealing that formed foci are primarily composed of macrophages with an anti-inflammatory M2 phenotype rather than M1 macrophages. To investigate further, chemically reprogrammed M1 macrophages were labeled with the membrane fluorescent tag PKH26 and administered to animals with endometriosis. Therapy resulted in a decrease in the number and size of foci, accompanied by a shift in the phenotypic composition of peritoneal macrophages. Specifically, the content of M2 macrophages decreased while that of M1 macrophages increased, resembling the composition of healthy animals. Our study conclusively demonstrates the anti-endometriosis properties of M1 macrophages, providing a strong foundation for future research in the cell therapy of endometriosis.

PPAR-γ/NF-kB/AQP3 axis in M2 macrophage orchestrates lung adenocarcinoma progression by upregulating IL-6

Aquaporin 3 (AQP3), which is mostly expressed in pulmonary epithelial cells, was linked to lung adenocarcinoma (LUAD). However, the underlying functions and mechanisms of AQP3 in the tumor microenvironment (TME) of LUAD have not been elucidated. Single-cell RNA sequencing (scRNA-seq) was used to study the composition, lineage, and functional states of TME-infiltrating immune cells and discover AQP3-expressing subpopulations in five LUAD patients. Then the identifications of its function on TME were examined in vitro and in vivo. AQP3 was associated with TNM stages and lymph node metastasis of LUAD patients. We classified inter- and intra-tumor diversity of LUAD into twelve subpopulations using scRNA-seq analyses. The analysis showed AQP3 was mainly enriched in subpopulations of M2 macrophages. Importantly, mechanistic investigations indicated that AQP3 promoted M2 macrophage polarization by the PPAR-γ/NF-κB axis, which affected tumor growth and migration via modulating IL-6 production. Mixed subcutaneous transplanted tumor mice and Aqp3 knockout mice models were further utilized, and revealed that AQP3 played a critical role in mediating M2 macrophage polarization, modulating glucose metabolism in tumors, and regulating both upstream and downstream pathways. Overall, our study demonstrated that AQP3 could regulate the proliferation, migration, and glycometabolism of tumor cells by modulating M2 macrophages polarization through the PPAR-γ/NF-κB axis and IL-6/IL-6R signaling pathway, providing new insight into the early detection and potential therapeutic target of LUAD.

Advantages and disadvantages of treatment of experimental ARDS by M2-polarized RAW 264.7 macrophages

Innate immunity reactions are core to any immunological process, including systemic inflammation and such extremes as acute respiratory distress syndrome (ARDS) and cytokine storm. Macrophages, the key cells of innate immunity, show high phenotypic plasticity: depending on microenvironmental cues, they can polarize into M1 (classically activated, pro-inflammatory) or M2 (alternatively activated, anti-inflammatory). The anti-inflammatory M2 macrophage polarization-based cell therapies constitute a novel prospective modality. Systemic administration of 'educated' macrophages is intended at their homing in lungs in order to mitigate the pro-inflammatory cytokine production and reduce the risks of 'cytokine storm' and related severe complications. Acute respiratory distress syndrome (ARDS) is the main mortality factor in pneumonia including SARS-CoV-associated cases. This study aimed to evaluate the influence of infusions of RAW 264.7 murine macrophage cell line polarized towards M2 phenotype on the development of LPS-induced ARDS in mouse model. The results indicate that the M2-polarized RAW 264.7 macrophage infusions in the studied model of ARDS promote relocation of lymphocytes from their depots in immune organs to the lungs. In addition, the treatment facilitates expression of M2-polarization markers Arg1, Vegfa and Tgfb and decreases of M1-polarization marker Cd38 in lung tissues, which can indicate the anti-inflammatory response activation. However, treatment of ARDS with M2-polarized macrophages didn't change the neutrophil numbers in the lungs. Moreover, the level of the Arg1 protein in lungs decreased throughtout the treatment with M2 macrophages, which is probably because of the pro-inflammatory microenvironment influence on the polarization of macrophages towards M1. Thus, the chemical polarization of macrophages is unstable and depends on the microenvironment. This adverse effect can be reduced through the use of primary autologous macrophages or some alternative methods of M2 polarization, notably siRNA-mediated.

Simultaneous Delivery of Doxorubicin and EZH2-Targeting siRNA by Vortex Magnetic Nanorods Synergistically Improved Anti-Tumor Efficacy in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), one of the most aggressive types of breast cancer, currently lacks a targeted therapy and has a high clinical recurrence rate. The present study reports an engineered magnetic nanodrug based on Fe3 O4 vortex nanorods coated with a macrophage membrane loaded with doxorubicin (DOX) and Enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) siRNA. This novel nanodrug displays excellent tissue penetration and preferential tumor accumulation. More importantly, it significantly increases tumor suppression compared to chemotherapy, suggesting the synergistic activity of the combination of doxorubicin and EZH2-inhibition. Importantly, owing to tumor-targeted delivery, nanomedicine shows an excellent safety profile after systemic delivery, unlike conventional chemotherapy. In summary, chemotherapy and gene therapy are combined into a novel magnetic nanodrug carrying doxorubicin and EZH2 siRNA, which shows promising clinical application potential in TNBC therapy.

Epigenetic therapy reprograms M2-type tumor-associated macrophages into an M1-like phenotype by upregulating miR-7083-5p

Reprogramming M2-type, pro-tumoral tumor-associated macrophages (TAMs) into M1-type, anti-tumoral macrophages is a key strategy in cancer therapy. In this study, we exploited epigenetic therapy using the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) and the histone deacetylation inhibitor trichostatin A (TSA), to reprogram M2-type macrophages into an M1-like phenotype. Treatment of M2-type macrophages with the combination of 5-aza-dC and TSA decreased the levels of M2 macrophage cytokines while increasing those of M1 macrophage cytokines, as compared to the use of either therapy alone. Conditioned medium of M2 macrophages treated with the combination of 5-aza-dC and TSA sensitized the tumor cells to paclitaxel. Moreover, treatment with the combination inhibited tumor growth and improved anti-tumor immunity in the tumor microenvironment. Depletion of macrophages reduced the anti-tumor growth activity of the combination therapy. Profiling of miRNAs revealed that the expression of miR-7083-5p was remarkably upregulated in M2 macrophages, following treatment with 5-aza-dC and TSA. Transfection of miR-7083-5p reprogrammed the M2-type macrophages towards an M1-like phenotype, and adoptive transfer of M2 macrophages pre-treated with miR-7083-5p into mice inhibited tumor growth. miR-7083-5p inhibited the expression of colony-stimulating factor 2 receptor alpha and CD43 as candidate targets. These results show that epigenetic therapy upon treatment with the combination of 5-aza-dC and TSA skews M2-type TAMs towards the M1-like phenotype by upregulating miR-7083-5p, which contributes to the inhibition of tumor growth.

Th2 cytokines IL-4, IL-13, and IL-10 promote differentiation of pro-lymphatic progenitors derived from bone marrow myeloid precursors

Myeloid-lymphatic endothelial cell progenitors (M-LECP) are a subset of bone marrow (BM)-derived cells characterized by expression of M2-type macrophage markers. We previously showed significant contribution of M-LECP to tumor lymphatic formation and metastasis in human clinical breast tumors and corresponding mouse models. Since M2-type is induced in macrophages by immunosuppressive Th2 cytokines IL-4, IL-13, and IL-10, we hypothesized that these factors might promote pro-lymphatic specification of M-LECP during their differentiation from BM myeloid precursors. To test this hypothesis, we analyzed expression of Th2 cytokines and their receptors in mouse BM cells under conditions leading to M-LECP differentiation, namely, CSF-1 treatment followed by activation of TLR4. We found that under these conditions, all three Th2 receptors were strongly upregulated in >95% of the cells that also secrete endogenous IL-10 but not IL-4 or IL-13 ligands. However, addition of any of the Th2 factors to CSF-1 primed cells significantly increased generation of myeloid-lymphatic progenitors as indicated by co-induction of lymphatic-specific (e.g., Lyve-1, integrin-a9, collectin-12, and stabilin-1) and M2-type markers (e.g., CD163, CD204, CD206, and PD-L1). Antibody-mediated blockade of either IL-10 receptor (IL-10R) or IL-10 ligand significantly reduced both immunosuppressive and lymphatic phenotypes. Moreover, tumor-recruited Lyve-1+ lymphatic progenitors in vivo expressed all Th2 receptors as well as corresponding ligands including IL-4 and IL-13 that were absent in BM cells. This study presents original evidence for the significant role of Th2 cytokines in co-development of immunosuppressive and lymphatic phenotypes in tumor-recruited M2-type myeloid cells. Progenitor-mediated increase in lymphatic vessels can enhance immunosuppression by physical removal of stimulatory immune cells. Thus, targeting Th2 pathways might simultaneously relieve immunosuppression and inhibit differentiation of pro-lymphatic progenitors that ultimately promote tumor spread.

Oxygen and metabolic reprogramming in the tumor microenvironment influences metastasis homing

Tumor metastasis is the leading cause of cancer mortality, often characterized by abnormal cell growth and invasion to distant organs. The cancer invasion due to epithelial to mesenchymal transition is affected by metabolic and oxygen availability in the tumor-associated micro-environment. A precise alteration in oxygen and metabolic signaling between healthy and metastatic cells is a substantial probe for understanding tumor progression and metastasis. Molecular heterogeneity in the tumor microenvironment help to sustain the metastatic cell growth during their survival shift from low to high metabolic-oxygen-rich sites and reinforces the metastatic events. This review highlighted the crucial role of oxygen and metabolites in metastatic progression and exemplified the role of metabolic rewiring and oxygen availability in cancer cell adaptation. Furthermore, we have also addressed potential applications of altered oxygen and metabolic networking with tumor type that could be a signature pattern to assess tumor growth and chemotherapeutics efficacy in managing cancer metastasis.

MicroRNA-200c restoration reveals a cytokine profile to enhance M1 macrophage polarization in breast cancer

Many immune suppressive mechanisms utilized by triple negative breast cancer (TNBC) are regulated by oncogenic epithelial-to-mesenchymal transition (EMT). How TNBC EMT impacts innate immune cells is not fully understood. To determine how TNBC suppresses antitumor macrophages, we used microRNA-200c (miR-200c), a powerful repressor of EMT, to drive mesenchymal-like mouse mammary carcinoma and human TNBC cells toward a more epithelial state. MiR-200c restoration significantly decreased growth of mouse mammary carcinoma Met-1 cells in culture and in vivo. Cytokine profiling of Met-1 and human BT549 cells revealed that miR-200c upregulated cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), promoted M1 antitumor macrophage polarization. Cytokines upregulated by miR-200c correlated with an epithelial gene signature and M1 macrophage polarization in BC patients and predicted a more favorable overall survival for TNBC patients. Our findings demonstrate that immunogenic cytokines (e.g., GM-CSF) are suppressed in aggressive TNBC, warranting further investigation of cytokine-based therapies to limit disease recurrence.

Macrophage CCL22 expression promotes lymphangiogenesis in patients with tongue squamous cell carcinoma via IL-4/STAT6 in the tumor microenvironment

The C-C motif chemokine ligand 22 (CCL22) chemokine is produced by M2-like tumor-associated macrophages (TAMs) in the tumor microenvironment. Chemokine C-C motif receptor 4 (CCR4), the CCL22 receptor, on T helper2 (Th2) cells leads to a Th2 cytokine-dominant environment. In our previous study, lymph node metastasis was the main predictor of tongue squamous cell carcinoma (SCC) via CCL22. Therefore, the present study aimed to investigate the effects of CCL22 and a Th2 cytokine-predominant tumor microenvironment on vascular endothelial growth factor (VEGF)-C expression and lymphangiogenesis. The post-operative courses of 110 patients with early-stage tongue SCC with a histopathological diagnosis based on the 8th TNM classification were followed up (mean/median follow-up time, 47.1/42.0 months) from surgery until death or the last follow-up visit, and subsequent lymph node relapse was assessed. Lymphangiogenesis and the immunohistochemical expression of several markers (CCL22, CCR4 and VEGF-C) were evaluated. The Kaplan-Meier method was used to plot lymph node relapse-free survival and overall survival curves, which were compared using the log-rank test. In vitro, the association between CCL22 and VEGF-C by interleukin (IL)-4/signal transducer and activator of transcription 6 (STAT6) stimulation was examined. Lymphangiogenesis was significantly associated with lymph node relapse (P<0.001) and a CCL22⁺ macrophage ratio (P<0.001). CCL22⁺ TAMs were positive for VEGF-C and surrounded by CCR4⁺ cells. Additionally, VEGF-C expression was increased in IL-4/STAT6-stimulated macrophages. In addition, the STAT6 signaling pathway was activated in the SCC cells in the deeply invaded part of the tumor along with the aggregated macrophages. In conclusion, TAM CCL22 expression led to lymph node relapse via VEGF-C expression within the tumor microenvironment and the IL-4/STAT6 signaling pathway in early stage tongue SCC. Additionally, the worst pattern of invasion and depth of invasion were revealed to be useful parameters for lymph node relapse in patients with tongue SCC. The present study suggested that CCL22 contributed to the role of M2-like differentiated TAMs in prognosis and lymph node relapse via IL-4/STAT6 and VEGF. The IL-4/STAT6 signaling pathway may be a new molecular target for tongue SCC.

Novel invasion indices quantify the feed-forward facilitation of tumor invasion by macrophages

Quantitative and reliable measurement of cellular invasion is important to understand a range of biological processes such as cancer metastasis and angiogenesis. Spheroid invasion assays are an attractive in vitro platform because they effectively mimic the tumor cell invasion of solid tissues. Here, we developed an image analysis–based method to quantify the invasiveness of HT1080 human fibrosarcoma tumor cell spheroids. We segmented a cell-covered area into three subareas using objectively set threshold pixel intensities and calculated invasion indices using these subareas. Comparison with conventional parameters for spheroid invasion assays, such as area, length, and detached cells, showed that our indices present the invasion event at an early time and without being convoluted by proliferation. As an application, we then examined paracrine interactions between LLC1 mouse lung carcinoma cells and Raw264.7 mouse macrophage cells with our developed analysis method. We found that the invasion of tumor spheroids was increased by a macrophage-conditioned medium, concomitantly with a decrease in tumor cell proliferation. Importantly, invasion was further enhanced by a conditioned medium from activated macrophages by co-culture with tumor cells. Thus, our indices reveal that tumor cell invasion is facilitated in a feed-forward manner by communication between tumor cells and macrophages in the tumor microenvironment.

A novel macrophage-mediated biomimetic delivery system with NIR-triggered release for prostate cancer therapy

Background

Macrophages with tumor-tropic migratory properties can serve as a cellular carrier to enhance the efficacy of anti neoplastic agents. However, limited drug loading (DL) and insufficient drug release at the tumor site remain the main obstacles in developing macrophage-based delivery systems. In this study, we constructed a biomimetic delivery system (BDS) by loading doxorubicin (DOX)-loaded reduced graphene oxide (rGO) into a mouse macrophage-like cell line (RAW264.7), hoping that the newly constructed BDS could perfectly combine the tumor-tropic ability of macrophages and the photothermal property of rGO.

Results

At the same DOX concentration, the macrophages could absorb more DOX/PEG-BPEI-rGO than free DOX. The tumor-tropic capacity of RAW264.7 cells towards RM-1 mouse prostate cancer cells did not undergo significant change after drug loading in vitro and in vivo. PEG-BPEI-rGO encapsulated in the macrophages could effectively convert the absorbed near-infrared light into heat energy, causing rapid release of DOX. The BDS showed excellent anti-tumor efficacy in vivo.

Conclusions

The BDS that we developed in this study had the following characteristic features: active targeting of tumor cells, stimuli-release triggered by near-infrared laser (NIR), and effective combination of chemotherapy and photothermotherapy. Using the photothermal effect produced by PEG-BPEI-rGO and DOX released from the macrophages upon NIR irradiation, MAs-DOX/PEG-BPEI-rGO exhibited a significant inhibitory effect on tumor growth.

In situ detecting changes in membrane lipid phenotypes of macrophages cultured in different cancer microenvironments using mass spectrometry

Macrophages, the important cells of immune system, have exhibited distinct gene phenotypes with diverse functions in different microenvironments. In the present study, macrophages RAW264.7 (M0 macrophages) and lipopolysaccharide (LPS) plus interferon gamma (INF-γ)-treated M0 macrophages (M1 macrophages) were cultured in different lung cell-derived culture supernatants (CSs) as imitative tumor microenvironments. The lipids (mainly from cell membrane) of intact macrophages were in situ detected by matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry. Approximately 300 of small molecules were observed in negative ion mode. Partial least square-discriminant analysis (PLS-DA) suggested that two types of the macrophages have different membrane lipid phenotypes. Changes in the levels of phosphatidylethanolamine PE(16:1/18:0), PE(18:1/18:0), PE(36:2), PE-Cer(d36:1), and PE(P-16:0/18:1) were closely associated with membrane phenotypes of macrophages. The heatmap also revealed that directional induction to classically activated macrophages (M1 macrophages) in vitro had greater impact on the membrane lipid phenotypes of macrophages than different lung cell-derived CSs. The results are consistent with the data obtained by biological technologies.

Interactions between fibroblastic reticular cells and B cells promote mesenteric lymph node lymphangiogenesis

Lymphatic growth (lymphangiogenesis) within lymph nodes functions to promote dendritic cell entry and effector lymphocyte egress in response to infection or inflammation. Here we demonstrate a crucial role for lymphotoxin-beta receptor (LTβR) signaling to fibroblastic reticular cells (FRCs) by lymphotoxin-expressing B cells in driving mesenteric lymph node lymphangiogenesis following helminth infection. LTβR ligation on fibroblastic reticular cells leads to the production of B-cell-activating factor (BAFF), which synergized with interleukin-4 (IL-4) to promote the production of the lymphangiogenic factors, vascular endothelial growth factors (VEGF)-A and VEGF-C, by B cells. In addition, the BAFF-IL-4 synergy augments expression of lymphotoxin by antigen-activated B cells, promoting further B cell–fibroblastic reticular cell interactions. These results underlie the importance of lymphotoxin-dependent B cell–FRC cross talk in driving the expansion of lymphatic networks that function to promote and maintain immune responsiveness.

The growth of lymph nodes in response to infection requires lymphangiogenesis. Dubey et al. show that the mesenteric lymph node lymphangiogenesis upon helminth infection depends on the signaling loop between the B and fibroblastic reticular cells (FRCs), whereby the FRCs respond to lymphotoxin secreted by B cells by releasing B cell activating factor.

Mannosylated liposomes improve therapeutic effects of paclitaxel in colon cancer models

Mannose receptor (MR) is a highly effective endocytic receptor. It is closely related to tumour immune escape and metastasis. We found that MR was highly expressed in some colon cancer cell lines such as CT26 and HCT116 cells. Therefore, MR might be a potential target in colon cancer therapy. In this study, we aimed to develop mannosylated liposomes containing anticancer drug paclitaxel and investigate the potential effects on targeted therapy for colon cancer. Mannosylated liposomes were prepared by film dispersion method. Characterisation, drug release behaviour, cytotoxicity, cellular uptake, anti-tumour efficacy and safety profiles of liposomes were investigated. The results showed that mannosylated liposomes had a higher CT26 cells uptake efficiency and tumour inhibition rate, which might be due to the target effect to MR. And no notable toxicity was observed. Taken together, these data demonstrated that mannosylated liposomes could target colon cancer and improve the efficacy of chemotherapy.

Immunoglobulin G (IgG)-Based Imaging Probe Accumulates in M1 Macrophage-Infiltrated Atherosclerotic Plaques Independent of IgG Target Molecule Expression

PURPOSE

Vulnerable plaques are key factors for ischemic diseases. Thus, their precise detection is necessary for the diagnosis of such diseases. Immunoglobulin G (IgG)-based imaging probes have been developed for imaging biomolecules related to plaque formation for the diagnosis of atherosclerosis. However, IgG accumulates nonspecifically in atherosclerotic regions, and its accumulation mechanisms have not yet been clarified in detail. Therefore, we explored IgG accumulation mechanisms in atherosclerotic lesions and examined images of radiolabeled IgG for the diagnosis of atherosclerosis.

PROCEDURES

Mouse IgG without specificity to biomolecules was labeled with technetium-99m via 6-hydrazinonicotinate to yield [^99mTc]IgG. ApoE^-/- or C57BL/6J mice were injected intravenously with [^99mTc]IgG, and their aortas were excised 24 h after injection. After radioactivity measurement, serial aortic sections were autoradiographically and histopathologically examined. RAW264.7 macrophages were polarized into M1 or M2 and then treated with [^99mTc]IgG. The radioactivities in the cells were measured after 1 h of incubation. [^99mTc]IgG uptake in M1 macrophages was also evaluated after the pretreatment with an anti-Fcγ receptor (FcγR) antibody. The expression levels of FcγRs in the cells were measured by western blot analysis.

RESULTS

[^99mTc]IgG accumulation levels in the aortas were significantly higher in apoE^-/- mice than in C57BL/6J mice (5.1 ± 1.4 vs 2.8 ± 0.5 %ID/g, p < 0.05). Autoradiographic images showed that the accumulation areas highly correlated with the macrophage-infiltrated areas. M1 macrophages showed significantly higher levels of [^99mTc]IgG than M2 or M0 (nonpolarized) macrophages [2.2 ± 0.3 (M1) vs 0.5 ± 0.1 (M2), 0.4 ± 0.1 (M0) %dose/mg protein, p < 0.01] and higher expression levels of FcγRI and FcγRII. [^99mTc]IgG accumulation in M1 macrophages was suppressed by pretreatment with the anti-FcγR antibody [2.2 ± 0.3 (nonpretreatment) vs 1.2 ± 0.2 (pretreatment) %ID/mg protein, p < 0.01].

CONCLUSIONS

IgG accumulated in pro-inflammatory M1 macrophages via FcγRs in atherosclerotic lesions. Thus, the target biomolecule-independent imaging of active inflammation should be taken into account in the diagnosis of atherosclerosis using IgG-based probes.

Paeoniflorin inhibits macrophage-mediated lung cancer metastasis

Alternatively activated macrophages are more frequently involved in tumor growth, angiogenesis, and immunosuppression. A previous study showed that paeoniflorin, the major active constituent of Paeonia lactiflora Pallas, can inhibit tumor growth and lung metastases of Lewis lung tumor-bearing mice. This study tried to investigate whether paeoniflorin inhibited lung cancer metastasis by inhibiting the alternative activation of macrophages (M2 macrophage). Using a viability assay, the cytotoxicity of paeoniflorin on Lewis lung cancer cells and peritoneal macrophages were investigated. In vitro scratch wound and in vivo lung metastasis experiments were used to test the ability to inhibit the migration of paeoniflorin and the function of M2 macrophages. Flow cytometry was performed to test the cell cycle of Lewis lung cancer cells, and to test the M2 macrophages in peritoneal macrophages and subcutaneous transplantable tumor. It was found that paeoniflorin showed no inhibitory effect on the growth of Lewis lung cancer cells and peritoneal macrophages of mouse in vitro. Paeoniflorin could attenuate the migration of LLC stimulated by alternatively activated macrophages (stimulated for 24 h and 48 h, paeoniflorin 1, 3, 10, 30, 100 μmol·L(-1), P < 0.01 or P < 0.05 vs control group). Paeoniflorin could decrease the cell populations at S phases (paeoniflorin 10, 30, 100 μmol·L(-1), P < 0.05 vs control group) and increase the cell populations at G0-G1 phases of Lewis lung cancer cells (paeoniflorin 100 μmol·L(-1), P < 0.05 vs control group) and reduce the numbers of M2 macrophages in peritoneal macrophages induced by IL-4 (paeoniflorin 1, 3, 10, 30, 100 μmol·L(-1), P < 0.01 vs Control group). Paeoniflorin could reduce lung metastasis of Lewis lung cancer cells xenograft and decrease the numbers of M2 macrophages in subcutaneous xenograft tumour in vivo (paeoniflorin 20, 40 mg·kg(-1), P < 0.01 vs control group). These results suggest that paeoniflorin could reduce lung metastasis of Lewis lung cancer cells xenograft partly through inhibiting the alternative activation of macrophages.

Prominent Lymphatic Vessel Hyperplasia with Progressive Dysfunction and Distinct Immune Cell Infiltration in Lymphedema

Lymphedema is a common complication that occurs after breast cancer treatment in up to 30% of the patients undergoing surgical lymph node excision. It is associated with tissue swelling, fibrosis, increased risk of infection, and impaired wound healing. Despite the pronounced clinical manifestations of the disease, little is known about the morphological and functional characteristics of the lymphatic vasculature during the course of lymphedema progression. We used an experimental murine tail lymphedema model where sustained fluid stasis was generated on disruption of lymphatic flow, resulting in chronic edema formation with fibrosis and adipose tissue deposition. Morphological analysis of the lymphatic vessels revealed a dramatic expansion during the course of the disease, with active proliferation of lymphatic endothelial cells at the early stages of lymphedema. The lymphatic capillaries exhibited progressively impaired tracer filling and retrograde flow near the surgery site, whereas the collecting lymphatic vessels showed a gradually decreasing contraction amplitude with unchanged contraction frequency, leading to lymphatic contraction arrest at the later stages of the disease. Lymphedema onset was associated with pronounced infiltration by immune cells, predominantly Ly6G(+) and CD4(+) cells, which have been linked to impaired lymphatic vessel function.

Visualization of the Biological Behavior of Tumor-Associated Macrophages in Living Mice with Colon Cancer Using Multimodal Optical Reporter Gene Imaging

We sought to visualize the migration of tumor-associated macrophages (TAMs) to tumor lesions and to evaluate the effects of anti-inflammatory drugs on TAM-modulated tumor progression in mice with colon cancer using a multimodal optical reporter gene system. Murine macrophage Raw264.7 cells expressing an enhanced firefly luciferase (Raw/effluc) and murine colon cancer CT26 cells coexpressing Rluc and mCherry (CT26/Rluc-mCherry, CT26/RM) were established. CT26/RM tumor-bearing mice received Raw/effluc via their tail veins, and combination of bioluminescence imaging (BLI) and fluorescence imaging (FLI) was conducted for in vivo imaging of TAMs migration and tumor progression. Dexamethasone (DEX), a potent anti-inflammatory drug, was administered intraperitoneally to tumor-bearing mice following the intravenous transfer of Raw/effluc cells. The migration of TAMs and tumor growth was monitored by serial FLI and BLI. The migration of Raw/effluc cells to tumor lesions was observed at day 1, and BLI signals were still distinct at tumor lesions on day 4. Localization of BLI signals from migrated Raw/effluc cells corresponded to that of FLI signals from CT26/RM tumors. In vivo FLI of tumors demonstrated enhanced tumor growth associated with macrophage migration to tumor lesions. Treatment with DEX inhibited the influx of Raw/effluc cells to tumor lesions and abolished the enhanced tumor growth associated with macrophage migration. These findings suggest that molecular imaging approach for TAM tracking is a valuable tool for evaluating the role of TAMs in the tumor microenvironment as well as for the development of new drugs to control TAM involvement in the modulation of tumor progression.

IGFBP7 functions as a potential lymphangiogenesis inducer in non-small cell lung carcinoma

Lymphangiogenesis is not only involved in the processes of embryonic development, tissue repair and chronic inflammation, but also in tumor lymphatic metastasis. Metastatic tumor cells spreading through lymphatic vessels occur in non-small cell lung carcinoma (NSCLC), with regional lymph node metastasis often being the most important prognostic factor for carcinoma patients. Recent research has identified a range of lymphangiogenic growth factors that could conceivably play a great role in promoting tumor lymphangiogenesis and lymphatic metastasis. The most extensively accepted signaling pathways promoting lymphangiogenesis in tumors include the secreted lymphangiogenic proteins: vascular endothelial growth factor-C (VEGF-C) and VEGF-D, and their cognate receptor on lymphatic endothelium VEGF receptor-3 (VEGFR-3). Targeting VEGF pathway strategy sometimes failed to decrease tumor metastasis in vivo experiments and clinical trials. It is unclear whether the tumor cells induced the lymphangiogenesis process, while VEGF pathway could not completely illustrate the mechanism of tumor cell lymphatic metastasis. To explore the novel tumor lymphangiogenesis targets, we screened 181 candidate genes between high lymphatic vascular density (LVD) and low LVD in lung adenocarcinomas using Human Genome U133 Plus 2.0 Microarray. Insulin-like growth factor binding protein 7 (IGFBP7) was proven to be associated with metastatic clinicopathological features and high LVD. Furthermore, by assessing the capability of lymphatic endothelial cell forming lymphatic vessel-like structures in vitro, it appears to enhance lymphangiogenesis.

Siglec-9 modulated IL-4 responses in the macrophage cell line RAW264

Siglecs, an immunoglobulin-like lectin family that recognizes the sialic acid moiety, regulate various aspects of immune responses. In the present study, we investigated the effects of Siglecs on the macrophage cell line RAW264, which was stimulated with interleukin-4 (IL-4). The induction of arginase-1 (Arg1) by IL-4 was stronger in Siglec-9-expressing cells than in mock cells. Mutations in the cytoplasmic tyrosine-based inhibitory motifs in Siglec-9 markedly reduced the expression of Arg1. The phosphorylation of Akt by IL-4 and extracellular signal-regulated kinase (ERK) without IL-4 was stronger in Siglec-9-expressing cells, indicating the enhanced activation of the phosphatidylinositol 3 kinase (PI-3K) and mitogen-activated protein kinase kinase (MEK)/ERK pathways, respectively. The enhanced expression of Arg1 was inhibited by MEK inhibitors, but not by PI-3K inhibitor. These results indicate that Siglec-9 affects several different signaling pathways in IL-4-stimulated macrophages, which resulted in enhanced induction of Arg1 in Siglec-9-expressing RAW264 cells.

Opposite Effects of M1 and M2 Macrophage Subtypes on Lung Cancer Progression

Macrophages in a tumor microenvironment have been characterized as M1- and M2-polarized subtypes. Here, we discovered the different macrophages' impacts on lung cancer cell A549. The M2a/M2c subtypes promoted A549 invasion and xenograft tumor growth. The M1 subtype suppressed angiogenesis. M1 enhanced the sensitivity of A549 to cisplatin and decreased the tube formation activity and cell viability of A549 cells by inducing apoptosis and senescence. Different macrophage subtypes regulated genes involved in the immune response, cytoskeletal remodeling, coagulation, cell adhesion, and apoptosis pathways in A549 cells, which was a pattern that correlated with the altered behaviors of the A549 cells. Furthermore, we found that the identified M1/M2 gene signatures were significantly correlated with the extended overall survival of lung cancer patients. These results suggest that M1/M2 gene expression signature may be used as a prognostic indicator for lung cancer patients, and M1/M2 polarization may be a target of investigation of immune-modulating therapies for lung cancer in the future.

Tumor hypoxia enhances Non-Small Cell Lung Cancer metastasis by selectively promoting macrophage M2 polarization through the activation of ERK signaling

Hypoxia is a common phenomenon occurring in the majority of human tumors and has been proved to play an important role in tumor progression. However, it remains unclear that whether the action of hypoxia on macrophages is a main driving force of hypoxia-mediated aggressive tumor behaviors. In the present study, we observe that high density of M2 macrophages is associated with metastasis in adenocarcinoma Non-Small Cell Lung Cancer (NSCLC) patients. By applying the in vivo hypoxia model, the results suggest that intermittent hypoxia significantly promotes the metastasis of Lewis lung carcinoma (LLC), accompanied with more CD209⁺ macrophages infiltrated in primary tumor tissue. More intriguingly, by skewing macrophages polarization away from the M1- to a tumor-promoting M2-like phenotype, hypoxia and IL-6 cooperate to enhance the LLC metastasis both in vitro and in vivo. In addition, we also demonstrate that skewing of macrophage M2 polarization by hypoxia relies substantially on activation of ERK signaling. Collectively, these observations unveil a novel tumor hypoxia concept involving the macrophage phenotype shift and provide direct evidence for lung cancer intervention through modulating the phenotype of macrophages.

Macrophage mediated biomimetic delivery system for the treatment of lung metastasis of breast cancer

The biomimetic delivery system (BDS) based on special types of endogenous cells like macrophages and T cells, has been emerging as a novel strategy for cancer therapy, due to its tumor homing property and biocompatibility. However, its development is impeded by complicated construction, low drug loading or negative effect on the cell bioactivity. The present report constructed a BDS by loading doxorubicin (DOX) into a mouse macrophage-like cell line (RAW264.7). It was found that therapeutically meaningful amount of DOX could be loaded into the RAW264.7 cells by simply incubation, without significantly affecting the viability of the cells. Drug could release from the BDS and maintain its activity. RAW264.7 cells exhibited obvious tumor-tropic capacity towards 4T1 mouse breast cancer cells both in vitro and in vivo, and drug loading did not alter this tendency. Importantly, the DOX loaded macrophage system showed promising anti-cancer efficacy in terms of tumor suppression, life span prolongation and metastasis inhibition, with reduced toxicity. In conclusion, it is demonstrated that the BDS developed here seems to overcome some of the main issues related to a BDS. The DOX loaded macrophages might be a potential BDS for targeted cancer therapy.

Regulation of inflammation and fibrosis by macrophages in lymphedema

Lymphedema, a common complication of cancer treatment, is characterized by inflammation, fibrosis, and adipose deposition. We have previously shown that macrophage infiltration is increased in mouse models of lymphedema. Because macrophages are regulators of lymphangiogenesis and fibrosis, this study aimed to determine the role of these cells in lymphedema using depletion experiments. Matched biopsy specimens of normal and lymphedema tissues were obtained from patients with unilateral upper extremity breast cancer-related lymphedema, and macrophage accumulation was assessed using immunohistochemistry. In addition, we used a mouse tail model of lymphedema to quantify macrophage accumulation and analyze outcomes of conditional macrophage depletion. Histological analysis of clinical lymphedema biopsies revealed significantly increased macrophage infiltration. Similarly, in the mouse tail model, lymphatic injury increased the number of macrophages and favored M2 differentiation. Chronic macrophage depletion using lethally irradiated wild-type mice reconstituted with CD11b-diphtheria toxin receptor mouse bone marrow did not decrease swelling, adipose deposition, or overall inflammation. Macrophage depletion after lymphedema had become established significantly increased fibrosis and accumulation of CD4(+) cells and promoted Th2 differentiation while decreasing lymphatic transport capacity and VEGF-C expression. Our findings suggest that macrophages home to lymphedematous tissues and differentiate into the M2 phenotype. In addition, our findings suggest that macrophages have an antifibrotic role in lymphedema and either directly or indirectly regulate CD4(+) cell accumulation and Th2 differentiation. Finally, our findings suggest that lymphedema-associated macrophages are a major source of VEGF-C and that impaired macrophage responses after lymphatic injury result in decreased lymphatic function.

M2-polarized macrophages contribute to the decreased sensitivity of EGFR-TKIs treatment in patients with advanced lung adenocarcinoma

Previous study has revealed that tumor-associated macrophages (TAMs) correlate with response to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in advanced non-small cell lung cancer (NSCLC). In the present study, we further determined that M2-TAMs, but not M1-TAMs, are related to the treatment response to EGFR-TKIs in advanced NSCLC and may be an independent predictor of survival. Eighty-eight advanced lung adenocarcinoma patients treated with a second-line EGFR-TKI were involved in this study. M2-TAMs counts but not M1-TAMs were significantly higher in patients with progressive disease than in those without (P < 0.001). A trend also remained in patients with known EGFR status (n = 61) and those with mutant EGFR (n = 49). High M2-TAMs counts were shown to be significantly related to poor progression-free survival (PFS) and overall survival (OS) in all patients, or subsets of patients with known EGFR status or patients with EGFR mutation (all P < 0.05). Multivariate Cox analyses showed that high M2-TAMs counts and EGFR mutations were both independent factors associated with PFS and OS (P < 0.05). Overall, we revealed that M2- but not M1-TAMs are related to the response of EGFR-TKIs treatment irrespective of EGFR mutation and can independently predict survival in advanced lung adenocarcinoma treated with a second-line EGFR-TKI.

Emerging Role of Sphingosine-1-phosphate in Inflammation, Cancer, and Lymphangiogenesis

The main function of the lymphatic system is to control and maintain fluid homeostasis, lipid transport, and immune cell trafficking. In recent years, the pathological roles of lymphangiogenesis, the generation of new lymphatic vessels from preexisting ones, in inflammatory diseases and cancer progression are beginning to be elucidated. Sphingosine-1-phosphate (S1P), a bioactive lipid, mediates multiple cellular events, such as cell proliferation, differentiation, and trafficking, and is now known as an important mediator of inflammation and cancer. In this review, we will discuss recent findings showing the emerging role of S1P in lymphangiogenesis, in inflammation, and in cancer.

Metastatic potential of B16-F10 melanoma cells is enhanced by extracellular S100A4 derived from RAW264.7 macrophages

S100A4, synthesized and secreted from both tumor and stroma cells, modulates an aggressive tumor phenotype in various cancers by intracellular and extracellular interactions which are not completely understood. Because of the high content of tumor-associated macrophages in melanoma, here, a syngeneic model (coculture of mouse B16-F10 melanoma cells (Mel) and RAW264.7 macrophages (Mϕ); administration (i.v.) of Mel and Mϕ/Mel in NMRI nu/nu mice) was used to investigate synthesis and secretion of (a) S100A4, (b) S100A4-mediated signaling and activation of NFκB, and (c) S100A4-mediated modulation of Mel invasiveness in vitro (transwell assay, transwell matrigel assay) and in vivo (metastatic lung colonization), respectively. In this model substantial S100A4 synthesis and secretion is demonstrated in Mϕ. Macrophage-derived S100A4 promotes Mel invasiveness in a paracrine manner in vitro, which is further substantiated in control experiments using recombinant human S100A4 and Mel stably transfected with mouse S100A4. Moreover, the participation of S100A4-mediated signaling, e.g., via the receptor for advanced glycation endproducts (RAGE), resulting in activation of NFκB was demonstrated in all experimental settings. Finally, we demonstrated that interaction of macrophage-derived S100A4 with Mel results in increased metastatic lung colonization in vivo.

Inflammation-driven dermal lymphangiogenesis in atopic dermatitis is associated with CD11b+ macrophage recruitment and VEGF-C up-regulation in the IL-4-transgenic mouse model

OBJECTIVE

To investigate the presence and extent of inflammatory lymphangiogenesis in AD and determine the role of IL-4 in lymphatic proliferation in both K14-IL-4 Tg mouse model of AD and cultured human epidermal cells.

METHODS

Skin tissues from Tg mice were collected for immunostaining against PDPN, LYVE-1, CD11b and VEGF-C. The regulation of specific lymphatic biomarkers and growth factors were determined using qPCR and Western Blot analyses. Dermal lymphatic uptake and drainage were assessed using intradermal EB dye micro-injections. Total RNA from IL-4-stimulated HaCaT cells was analyzed in a PCR array to evaluate the regulation of lymphangiogenic-related genes.

RESULTS

Prominent dermal microvascular lymphangiogenesis occurs in the Tg mice, characterized by a significant increase in number and caliber of the vasculature. The extent of both lymphatic proliferation and drainage parallels the progression of lesion severity, as does the up-regulation of pro-lymphangiogenic factors VEGF-C, VEGFR-3, ANG-1, and ANG-2. IL-4-stimulated HaCaT cells express high levels of MCP-1, a strong macrophage chemo-attractant. Additionally, Tg mice show significantly increased number of dermal CD11b+ macrophages expressing VEGF-C in the skin.

CONCLUSIONS

Our results provide the first demonstration of inflammation-mediated lymphangiogenesis in AD and that IL-4 triggered macrophage recruitment may be closely linked to this phenomenon.

Lymphatic microvessel density and vascular endothelial growth factor-C and -D as prognostic factors in breast cancer: a systematic review and meta-analysis of the literature

The use of lymphatic microvessel density (LVD) and pro-lymphangiogenic mediators as prognostic factors for survival in breast cancer remains controversial. We searched the electronic databases PubMed and EMBASE without language restrictions for relevant literature to aggregate the survival results. To be eligible, every study had to include the assessment of the LVD or the expression of vascular endothelial growth factor (VEGF)-C or -D in patients with breast cancer and provide a survival comparison, including disease-free survival (DFS) or overall survival (OS), according to the LVD, VEGF-C or VEGF-D status. Across all studies, 56.64 % of patients were considered to have a VEGF-C-positive tumor, and 65.54 % of patients had VEGF-D-positive tumors. High LVD had an unfavorable impact on DFS, with a pooled hazard ratio (HR) of 2.222 (95 % CI 1.579-3.126) and an OS with a HR of 2.493 (95 % CI 1.183-5.25). According to the different lymphatic makers, the subgroup HR in the D2-40 studies was 2.431 (95 % CI 1.622-3.644) for DFS and 4.085 (95 % CI 1.896-8.799) for OS. VEGF-C overexpression, as assessed by immunochemistry, was a prognostic factor for decreased DFS (HR 2.164; 95 % CI 1.256-3.729) and for decreased OS (HR 2.613; 95 % CI 1.637-4.170). VEGF-D overexpression was a significant although weak prognostic factor for DFS only when assessed by immunochemistry, with a HR of 2.108 (95 % CI 1.014-4.384). Our meta-analysis demonstrated that LVD, VEGF-C and VEGF-D could predict poor prognosis in patients with breast cancer. However, standardization of the assessment of LVD and for the expression of lymphangiogenesis factors is needed.

Deciphering the roles of macrophages in developmental and inflammation stimulated lymphangiogenesis

Lymphatic vessels share an intimate relationship with hematopoietic cells that commences during embryogenesis and continues throughout life. Lymphatic vessels provide a key conduit for immune cell trafficking during immune surveillance and immune responses and in turn, signals produced by immune lineage cells in settings of inflammation regulate lymphatic vessel growth and activity. In the majority of cases, the recruitment and activation of immune cells during inflammation promotes the growth and development of lymphatic vessels (lymphangiogenesis) and enhances lymph flow, effects that amplify cell trafficking to local lymph nodes and facilitate the mounting of effective immune responses. Macrophages comprise a major, heterogeneous lineage of immune cells that, in addition to key roles in innate and adaptive immunity, perform diverse tasks important for tissue development, homeostasis and repair. Here, we highlight the emerging roles of macrophages in lymphangiogenesis, both during development and in settings of pathology. While much attention has focused on the production of pro-lymphangiogenic stimuli including VEGF-C and VEGF-D by macrophages in models of inflammation including cancer, there is ample evidence to suggest that macrophages provide additional signals important for the regulation of lymphatic vascular growth, morphogenesis and function.

M2-polarized macrophages promote metastatic behavior of Lewis lung carcinoma cells by inducing vascular endothelial growth factor-C expression

OBJECTIVES

Tumor-associated macrophages that generally exhibit an alternatively activated (M2) phenotype have been linked to tumor progression and metastasis. However, the role of M2-polarized macrophages in the growth and metastasis of lung adenocarcinoma remains enigmatic. The aim of this study was to explore the effect of M2 macrophages on the proliferation and migration of mouse Lewis lung carcinoma cells and tumor-induced lymphangiogenesis.

METHODS

Trypan blue staining and the Transwell migration assay were performed to evaluate the effects of activated (M1 or M2) macrophages on the proliferation and migration of Lewis cells. Furthermore, vascular endothelial growth factor-C expression in Lewis cells and nitric oxide secretion from activated macrophages were detected during the co-culture assay. Following treatment with activated macrophages, lymphatic endothelial cells differentiated into capillary-like structures, and the induction of Lewis cell migration was assessed using a two-dimensional Matrigel-based assay.

RESULTS

In the co-culture Transwell system, the proliferation and migration of Lewis cells were promoted by M2 macrophages. Moreover, the co-culture significantly increased the expression of vascular endothelial growth factor-C by Lewis cells and reduced the secretion of nitric oxide from M2 macrophages, which subsequently led to the capillary morphogenesis of lymphatic endothelial cells. Interestingly, following co-culture with Lewis cells, the function of RAW264.7 cells was polarized toward that of the M2 macrophage phenotype.

CONCLUSION

M2-polarized macrophages promoted the metastatic behavior of Lewis cells by inducing vascular endothelial growth factor-C expression. Thus, the interruption of signaling between M2 macrophages and Lewis cells may be considered to be a new therapeutic strategy.

Bone marrow-derived, alternatively activated macrophages enhance solid tumor growth and lung metastasis of mammary carcinoma cells in a Balb/C mouse orthotopic model

INTRODUCTION

Tumor-associated macrophages, which are derived from the infiltration of circulating bone marrow-derived monocytes, consist primarily of a polarized M2 macrophage (M2-Mϕ) population and are associated with poor prognosis in various cancers. In the present study, we attempted to assess whether M2-Mϕs derived from bone marrow stimulate the promotion and progression of mammary tumors.

METHODS

4T1 murine mammary carcinoma cells were injected either alone or coupled with M2-Mϕs into the mammary fat pads of syngeneic female Balb/C mice. M2-Mϕs were prepared by treating monocytes isolated from female Balb/C mouse bone marrow with IL-4. Tumor cell growth was determined using an in vivo imaging system and the expression of cell proliferation-related, angiogenesis-related, and lymphangiogenesis-related proteins in tumor tissues was immunohistochemically analyzed. To evaluate the effects of the crosstalk between 4T1 cells and M2-Mϕs on the secretion and mRNA expression of cytokines and the migration of monocytes, 4T1 cells and M2-Mϕs were co-cultured and cytokine antibody array, real-time RT-PCR, and trans-well migration assays were conducted.

RESULTS

The co-injection of M2-Mϕs into the mammary fat pads of mice increased solid tumor growth and lung metastasis of 4T1 cells as well as the infiltration of CD45+ leukocytes into tumor tissues. The proportions of Ki-67+ proliferating cells and the expression of hypoxia inducible factor-1α, vascular endothelial cell growth factor A, CD31, vascular endothelial cell growth factor C, and lymphatic vessel endothelial receptor-1 were increased significantly in the tumor tissues of mice co-injected with 4T1 cells and M2-Mϕs. The in vitro results revealed that the proliferation of 4T1 cells, the migration of monocytes, and the secretion of granulocyte colony-stimulating factor, IFNγ, IL-1α, IL-2, IL-16, IFNγ-induced protein-10, keratinocyte-derived chemokine, macrophage colony-stimulating factor, monocyte chemotactic protein-1, macrophage inflammatory protein-1α, and RANTES were increased when 4T1 cells were co-cultured with M2-Mϕs, as compared with when the 4T1 cells were cultured alone.

CONCLUSION

The crosstalk between 4T1 cells and M2-Mϕs increased the production of cytokines, which may have induced immune cell infiltration into tumor tissues, tumor cell proliferation, angiogenesis, and lymph angiogenesis, thereby increasing solid tumor growth and lung metastasis.

Tumor-associated macrophages promote angiogenesis and lymphangiogenesis of gastric cancer

BACKGROUND AND OBJECTIVES

This study was conducted to investigate whether and how macrophages recruited to tumor microenvironments (tumor-associated macrophages, TAMs) were involved in angiogenesis and lymphangiogenesis of gastric cancer (GC).

METHODS

TAMs, microvessel density (MVD), and lymphatic vessel density (LVD) in 115 cases of GC tissue were assessed by immunohistochemistry (IHC) staining of CD68, CD34, and D2-40, respectively. Preoperative blood samples from 43 patients were obtained to detect serum levels of vascular endothelial growth factor (VEGF) and VEGF-C. A co-culture system was also developed to study effects and underlying mechanisms of THP-1 macrophages on SGC7901 GC cells.

RESULTS

TAMs numbers were closely related to serosa invasion, lymph node metastasis and tumor, nodes, and metastases stage and a positive correlation existed between the TAMs count and MVD and LVD. Additionally, TAMs were associated with preoperative serum levels of VEGF and VEGF-C, the expression of VEGF and VEGF-C protein in macrophages was up-regulated in the co-culture system, and inhibition of the NF-κB pathway in macrophages induced a significant reduction in the expression of VEGF and VEGF-C in both macrophages and GC cells (all P<0.05).

CONCLUSIONS

TAMs may promote angiogenesis and lymphangiogenesis of GC, possibly by enhancing VEGF and VEGF-C expression.

Activation state of stromal inflammatory cells in murine metastatic pancreatic adenocarcinoma

The histologic presence of macrophages (tumor-associated macrophages, TAMs) and neutrophils (tumor-associated neutrophils, TANs) has been linked to poor clinical outcomes for solid tumors. The exact mechanism for this association with worsened prognosis is unclear. It has been theorized that TAMs are immunomodulated to an alternatively activated state and promote tumor progression. Similarly, TANs have been shown to promote angiogenesis and tumor detachment. TAMs and TANs were characterized for activation state and production of prometastatic mediators in an immunocompetent murine model of pancreatic adenocarcinoma. Specimens from liver metastases were evaluated by immunofluorescence and immunoblotting. TAMS have upregulated expression of CD206 and CD163 markers of alternative activation, (4.14 ± 0.55-fold and 7.36 ± 1.13-fold over control, respectively, P < 0.001) but do not have increased expression of classically activated macrophage markers CCR2 and CCR5. TAMs also express oncostatin M (OSM). We found that TANs, not TAMs, predominantly produce matrix metalloproteinase-9 (MMP-9) in this metastatic tumor microenvironment, while MMP-2 production is pan-tumoral. Moreover, increased expression of VEGF colocalized with TAMs as opposed to TANs. TAMs and TANs may act as distinct effector cells, with TAMs phenotypically exhibiting alternative activation and releasing OSM and VEGF. TANs are localized at the invasive front of the metastasis, where they colocalize with MMP-9. Improved understanding of these interactions may lead to targeted therapies for pancreas adenocarcinoma.

Peritumoral lymphatic microvessel density is related to poor prognosis in lung adenocarcinoma: A retrospective study of 65 cases

Although recent investigations have identified that lymphangiogenesis is associated with regional lymph node metastasis and tumor prognosis in non-small cell lung cancer (NSCLC), peritumoral lymphatic microvessel density (LMVD) and its prognostic significance in lung adenocarcinoma remain unknown. In the present study, we assessed peritumoral LMVD in lung adenocarcinoma and investigated its correlation with patient prognosis. Using immunohistochemistry (SP method), the D2-40-positive peritumoral LMVD count in lung adenocarcinoma was found to be 11.56±10.73, which was higher than intratumoral LMVD (P<0.001), and was found to be associated with lymphatic metastasis (P=0.003) and pTNM staging (P=0.046). Furthermore, a significant difference in the patient overall survival time was demonstrated between tumors with a high peritumoral LMVD and those with a low peritumoral LMVD (P=0.005). Finally, using multivariate analysis, it was determined that peritumoral LMVD, lymphatic metastasis and pTNM staging were independent prognostic factors. In conclusion, the results suggest that D2-40-positive peritumoral LMVD may predict the prognosis of lung adenocarcinoma.

Autocrine CSF-1 and CSF-1 receptor coexpression promotes renal cell carcinoma growth

Renal cell carcinoma is increasing in incidence but the molecular mechanisms regulating its growth remain elusive. Coexpression of the monocytic growth factor colony-stimulating factor (CSF)-1 and its receptor CSF-1R on renal tubular epithelial cells (TEC) will promote proliferation and antiapoptosis during regeneration of renal tubules. Here, we show that a CSF-1-dependent autocrine pathway is also responsible for the growth of renal cell carcinoma (RCC). CSF-1 and CSF-1R were coexpressed in RCCs and TECs proximally adjacent to RCCs. CSF-1 engagement of CSF-1R promoted RCC survival and proliferation and reduced apoptosis, in support of the likelihood that CSF-1R effector signals mediate RCC growth. In vivo CSF-1R blockade using a CSF-1R tyrosine kinase inhibitor decreased RCC proliferation and macrophage infiltration in a manner associated with a dramatic reduction in tumor mass. Further mechanistic investigations linked CSF-1 and epidermal growth factor signaling in RCCs. Taken together, our results suggest that budding RCC stimulates the proximal adjacent microenvironment in the kidney to release mediators of CSF-1, CSF-1R, and epidermal growth factor expression in RCCs. Furthermore, our findings imply that targeting CSF-1/CSF-1R signaling may be therapeutically effective in RCCs.

The interaction between different types of activated RAW 264.7 cells and macrophage inflammatory protein-1 alpha

Background

Two major ways of macrophage (MΦ) activation can occur in radiation-induced pulmonary injury (RPI): classical and alternative MΦ activation, which play important roles in the pathogenesis of RPI. MΦ can produce chemokine MΦ inflammatory protein-1α (MIP-1α), while MIP-1α can recruit MΦ. The difference in the chemotactic ability of MIP-1α toward distinct activated MΦ is unclear. We speculated that there has been important interaction of MIP-1α with different activated MΦ, which might contribute to the pathogenesis of RPI.

Methods

Classically and alternatively activated MΦ were produced by stimulating murine MΦ cell line RAW 264.7 cells with three different stimuli (LPS, IL-4 and IL-13); Then we used recombinant MIP-1α to attract two types of activated MΦ. In addition, we measured the ability of two types of activated MΦ to produce MIP-1α at the protein or mRNA level.

Results

Chemotactic ability of recombinant MIP-1α toward IL-13-treated MΦ was the strongest, was moderate for IL-4-treated MΦ, and was weakest for LPS-stimulated MΦ (p < 0.01). The ability of LPS-stimulated MΦ to secrete MIP-1α was significantly stronger than that of IL-4-treated or IL-13-treated MΦ (p < 0.01). The ability of LPS-stimulated MΦ to express MIP-1α mRNA also was stronger than that of IL-4- or IL-13-stimulated MΦ (p < 0.01).

Conclusions

The chemotactic ability of MIP-1α toward alternatively activated MΦ (M2) was significantly greater than that for classically activated MΦ (M1). Meanwhile, both at the mRNA and protein level, the capacity of M1 to produce MIP-1α is better than that of M2. Thus, chemokine MIP-1α may play an important role in modulating the transition from radiation pneumonitis to pulmonary fibrosis in vivo, through the different chemotactic affinity for M1 and M2.

Croix CM, Ray A, Ray P. Rapid host defense against Aspergillus fumigatus involves alveolar macrophages with a predominance of alternatively activated phenotype

The ubiquitous fungus Aspergillus fumigatus is associated with chronic diseases such as invasive pulmonary aspergillosis in immunosuppressed patients and allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis or severe asthma. Because of constant exposure to this fungus, it is critical for the host to exercise an immediate and decisive immune response to clear fungal spores to ward off disease. In this study, we observed that rapidly after infection by A. fumigatus, alveolar macrophages predominantly express Arginase 1 (Arg1), a key marker of alternatively activated macrophages (AAMs). The macrophages were also found to express Ym1 and CD206 that are also expressed by AAMs but not NOS2, which is expressed by classically activated macrophages. The expression of Arg1 was reduced in the absence of the known signaling axis, IL-4Rα/STAT6, for AAM development. While both Dectin-1 and TLR expressed on the cell surface have been shown to sense A. fumigatus, fungus-induced Arg1 expression in CD11c⁺ alveolar macrophages was not dependent on either Dectin-1 or the adaptor MyD88 that mediates intracellular signaling by most TLRs. Alveolar macrophages from WT mice efficiently phagocytosed fungal conidia, but those from mice deficient in Dectin-1 showed impaired fungal uptake. Depletion of macrophages with clodronate-filled liposomes increased fungal burden in infected mice. Collectively, our studies suggest that alveolar macrophages, which predominantly acquire an AAM phenotype following A. fumigatus infection, have a protective role in defense against this fungus.

M2-polarized tumor-associated macrophages are associated with poor prognoses resulting from accelerated lymphangiogenesis in lung adenocarcinoma

OBJECTIVES

Tumor-associated macrophages have been implicated in promoting tumor growth, progression and metastasis. However, the activated phenotype (M1 or M2) of tumor-associated macrophages remains unknown in solid tumors. Therefore, this study examined the density and prognostic significance of M2-polarized tumor-associated macrophages in lung adenocarcinoma.

METHODS

Tumor specimens from 65 lung adenocarcinoma patients were assessed by ELISA for Th1/Th2 cytokine concentrations. The activated phenotype (M1 or M2) of tumor-associated macrophages was determined utilizing immunofluorescence staining. Additionally, to evaluate lymphangiogenesis, peritumoral lymphatic microvessel density was measured using D2-40. The correlation between tumor-associated macrophage subtype and overall patient survival was analyzed using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

A shift toward Th2 cytokine expression was detected within lung adenocarcinoma microenvironments. Approximately 79.71±16.27% of tumor-associated macrophages were M2 polarized; the remaining 20.35±5.31% were M1 polarized. The infiltration of M2-polarized macrophages was significantly associated with P-TNM staging and lymph node metastasis. The peritumoral lymphatic microvessel density was significantly higher in the high M2-polarized tumor-associated macrophage group than in the low M2-polarized tumor-associated macrophage group. A significant difference in overall patient survival was detected not only between patients with tumors with high and low macrophage counts but also between patients with tumors with high and low counts of M2-polarized macrophages.

CONCLUSION

Tumor-associated macrophages in lung adenocarcinoma have an M2-polarized subtype and are associated with poor prognoses, perhaps resulting from accelerated lymphangiogenesis and lymph node metastasis.

Gender-specific transfusion affects tumor-associated neutrophil: macrophage ratios in murine pancreatic adenocarcinoma

INTRODUCTION

Perioperative blood transfusion has been linked to decreased survival for pancreas cancer. Noting clinical data associating female blood products with increased morbidity, our lab has demonstrated that transfusion of female blood augments metastatic events compared to male blood in an immunocompetent murine pancreatic cancer model. It has been suggested that tumor-associated macrophages correlate with tumor progression by promoting angiogenesis. More recently, tumor-associated neutrophils have been implicated in aggressive tumor behavior. We hypothesize that differences in gender-specific transfusion-mediated pancreatic cancer progression are due to microenvironmental changes within the tumor. To test this hypothesis, we examined tumor-associated neutrophils and macrophage ratios in male and female mice with pancreatic cancer receiving blood transfusion from male or female donors.

METHODS

C57/BL6 mice, age 7-9 weeks, underwent splenic inoculation with 2.5 × 10(5) PanO2 murine pancreatic adenocarcinoma cells. Mice were transfused on post-op day 7 with 1 ml/kg supernatant from day 42 male or female packed red cells. Necropsy was performed at 5 weeks or earlier for clinical deterioration, and tumors harvested. Frozen sections (5 µm) were stained for neutrophils and macrophages by immunofluorescence. Data were analyzed using ANOVA; p ≤ 0.05 was used to determine significance; N ≥ 3 per group.

RESULTS

Clinically, male mice had greater morbidity and mortality than female mice when receiving female blood products, with roughened hair coat, development of ascites and death due to bowel obstruction. In evaluating the tumor microenvironment from mice receiving female blood products, male mice were noted to have a greater neutrophil to macrophage ratio than female mice, 0.176 ± 0.028 vs. 0.073 ± 0.012, p = 0.03. When examining neutrophil to macrophage ratio in mice receiving male blood products, no difference was noted (p = 0.48).

CONCLUSIONS

Male mice with pancreas cancer have greater morbidity than female mice when receiving female blood products. Furthermore, the difference in neutrophil to macrophage ratio suggests that gender-specific blood transfusion promotes aggressive tumor behavior in male mice via microenvironmental changes. These data warrant further study to delineate sex-related differences in pancreatic cancer progression.

Reciprocal activation of macrophages and breast carcinoma cells by nitric oxide and colony-stimulating factor-1

Induction of inducible nitric oxide synthase (iNOS) gene expression, nitric oxide (NO) production and migration of RAW264.7 macrophages by coculture with breast cancer MDA-MB-231 cells or the addition of conditioned medium derived from MDA-MB-231 cells (MDA-CM) was identified. Increased iNOS/NO induction and migration of macrophages by MDA-CM were significantly blocked by adding the c-Jun-N-terminal protein kinase (JNK) inhibitor, SP600125, the nuclear factor-kappa B (NF-κB) inhibitor, BAY117082 and pyrrolidine dithiocarbamic acid and a dominant-negative JNK. The addition of an NO donor, Diethylenetriamine-NONOate, significantly activated expressions of MMP-9 and VEGF-A genes in breast carcinoma MDA-MD-231 cells and invasion of MDA-MB-231 cells in coculture with RAW264.7 macrophages as determined using Transwell systems, but that was inhibited by adding SP600125, BAY117082 and the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester. Induction of heme oxygenase-1 in macrophages reduced MDA-CM-induced iNOS/NO, JNK and NF-κB activations in accordance with inhibiting VEGF-A and MMP-9 gene expressions by MDA-MB-231 cells via Transwell assays. Furthermore, VEGF, sRANKL, TNF-α, IL-1α, TGF-β, CSF-1 and MCP-1 were applied, and CSF-1 showed the most potent stimulation of iNOS/NO production and migration of macrophages. MCF-7 cells with lower CSF-1 expression than MDA-MB-231 cells showed a poor stimulatory effect on iNOS/NO production and migration of macrophages. Neutralization of CSF-1 in MDA-CM using CSF-1 antibody inhibited MDA-CM-induced iNOS protein expression and migration of macrophages, and CSF-1-induced iNOS protein and migration was blocked by adding JNK inhibitor SP and NF-κB inhibitor BAY. The reciprocal activation of breast cancer and macrophages via NO-CSF-1 is first elucidated herein.

Fra-1 protooncogene regulates IL-6 expression in macrophages and promotes the generation of M2d macrophages

The tumor microenvironment (TME) plays a prominent role in the growth of tumor cells. As the major inflammatory component of the TME, M2d macrophages are educated by the TME such that they adopt an immunosuppressive role that promotes tumor metastasis and progression. Fra-1 forms activator protein-1 heterodimers with Jun partners and drives gene transcription. Fra-1 is thought to drastically induce tumorigenesis and progression. However, the functional role of Fra-1 in the generation of M2d macrophages is poorly understood to date. Here, we demonstrate that 4T1 mammary carcinoma cells, when co-cultured with RAW264.7 macrophage cells, skew the RAW264.7 macrophage cell differentiation into M2d macrophages. The 4T1 cells stimulate de novo overexpression of Fra-1 in RAW264.7 cells, and then Fra-1 binds to the interleukin 6 (IL-6) promoter to increase the production of the cytokine IL-6 in RAW264.7 cells. IL-6 acts in an autocrine fashion to skew RAW264.7 macrophage cell differentiation into M2d macrophages. These findings open new insights into how to reverse M2d macrophage-induced immune tolerance to improve the efficacy of immunotherapeutic approaches.