Stimulated Macrophage Polarization Research Articles

Dexamethasone Long-Term Controlled Release from Injectable Dual-Network Hydrogels with Porous Microspheres Immunomodulation Promotes Bone Regeneration.

Long-lasting, controlled-release, and minimally invasive injectable platforms that provide a stable blood concentration to promote bone regeneration are less well developed. Using hexagonal mesoporous silica (HMS) loaded with dexamethasone (DEX) and poly(lactic-co-glycolic acid) (PLGA), we prepared porous DEX/HMS/PLGA microspheres (PDHP). In contrast to HMS/PLGA microspheres (HP), porous HMS/PLGA microspheres (PHP), DEX/PLGA microspheres (DP), and DEX/HMS/PLGA microspheres (DHP), PDHP showed notable immuno-coordinated osteogenic capabilities and were best at promoting bone mesenchymal stem cell proliferation and osteogenic differentiation. PDHP were combined with methacrylated silk (SilMA) and sodium alginate (SA) to form an injectable photocurable dual-network hydrogel platform that could continuously release the drug for more than 4 months. By adjusting the content of the microspheres in the hydrogel, a zero-order release hydrogel platform was obtained in vitro for 48 days. When the microsphere content was 1%, the hydrogel platform exhibited the best biocompatibility and osteogenic effects. The expression levels of the osteogenic gene alkaline phosphatases, BMP-2 and OPN were 10 to 15 times higher in the 1% group than in the 0% group, respectively. In addition, the 1% microsphere hydrogel strongly stimulated macrophage polarization to the M2 phenotype, establishing an immunological milieu that supports bone regrowth. The aforementioned outcomes were also observed in vivo. The most successful method for correcting cranial bone abnormalities in SD rats was to use a hydrogel called SilMA/SA containing 1% drug-loaded porous microspheres (PDHP/SS). The angiogenic and osteogenic effects of this treatment were also noticeably greater in the PDHP/SS group than in the control and blank groups. In addition, PDHP/SS polarized M2 macrophages and suppressed M1 macrophages in vivo, which reduced the local immune-inflammatory response, promoted angiogenesis, and cooperatively aided in situ bone healing. This work highlights the potential application of an advanced hydrogel platform for long-term, on-demand, controlled release for bone tissue engineering.

Ficolin-A induces macrophage polarization to a novel pro-inflammatory phenotype distinct from classical M1

BackgroundMacrophages are key inflammatory immune cells that orchestrate the initiation and progression of autoimmune diseases. The characters of macrophage in diseases are determined by its phenotype in response to the local microenvironment. Ficolins have been confirmed as crucial contributors to autoimmune diseases, with Ficolin-2 being particularly elevated in patients with autoimmune diseases. However, whether Ficolin-A stimulates macrophage polarization is still poorly understood.MethodsWe investigated the transcriptomic expression profile of murine bone marrow-derived macrophages (BMDMs) stimulated with Ficolin-A using RNA-sequencing. To further confirm a distinct phenotype activated by Ficolin-A, quantitative RT-PCR and Luminex assay were performed in this study. Additionally, we assessed the activation of underlying cell signaling pathways triggered by Ficolin-A. Finally, the impact of Ficolin-A on macrophages were investigated in vivo through building Collagen-induced arthritis (CIA) and Dextran Sulfate Sodium Salt (DSS)-induced colitis mouse models with Fcna-/- mice.ResultsFicolin-A activated macrophages into a pro-inflammatory phenotype distinct to LPS-, IFN-γ- and IFN-γ + LPS-induced phenotypes. The transcriptomic profile induced by Ficolin-A was primarily characterized by upregulation of interleukins, chemokines, iNOS, and Arginase 1, along with downregulation of CD86 and CD206, setting it apart from the M1 and M2 phenotypes. The activation effect of Ficolin-A on macrophages deteriorated the symptoms of CIA and DSS mouse models, and the deletion of Fcna significantly alleviated the severity of diseases in mice.ConclusionOur work used transcriptomic analysis by RNA-Seq to investigate the impact of Ficolin-A on macrophage polarization. Our findings demonstrate that Ficolin-A induces a novel pro-inflammatory phenotype distinct to the phenotypes activated by LPS, IFN-γ and IFN-γ + LPS on macrophages.

Tumor-derived extracellular vesicles regulate macrophage polarization: role and therapeutic perspectives.

Extracellular vesicles (EVs) are important cell-to-cell communication mediators. This paper focuses on the regulatory role of tumor-derived EVs on macrophages. It aims to investigate the causes of tumor progression and therapeutic directions. Tumor-derived EVs can cause macrophages to shift to M1 or M2 phenotypes. This indicates they can alter the M1/M2 cell ratio and have pro-tumor and anti-inflammatory effects. This paper discusses several key points: first, the factors that stimulate macrophage polarization and the cytokines released as a result; second, an overview of EVs and the methods used to isolate them; third, how EVs from various cancer cell sources, such as hepatocellular carcinoma, colorectal carcinoma, lung carcinoma, breast carcinoma, and glioblastoma cell sources carcinoma, promote tumor development by inducing M2 polarization in macrophages; and fourth, how EVs from breast carcinoma, pancreatic carcinoma, lungs carcinoma, and glioblastoma cell sources carcinoma also contribute to tumor development by promoting M2 polarization in macrophages. Modified or sourced EVs from breast, pancreatic, and colorectal cancer can repolarize M2 to M1 macrophages. This exhibits anti-tumor activities and offers novel approaches for tumor treatment. Therefore, we discovered that macrophage polarization to either M1 or M2 phenotypes can regulate tumor development. This is based on the description of altering macrophage phenotypes by vesicle contents.

Urchin-like Fe3O4@Bi2S3 Nanospheres Enable the Destruction of Biofilm and Efficiently Antibacterial Activities.

Biofilm-associated infections (BAIs) have been considered a major threat to public health, which induce persistent infections and serious complications. The poor penetration of antibacterial agents in biofilm significantly limits the efficiency of combating BAIs. Magnetic urchin-like core-shell nanospheres of Fe3O4@Bi2S3 were developed for physically destructing biofilm and inducing bacterial eradication via reactive oxygen species (ROS) generation and innate immunity regulation. The urchin-like magnetic nanospheres with sharp edges of Fe3O4@Bi2S3 exhibited propeller-like rotation to physically destroy biofilm under a rotating magnetic field (RMF). The mild magnetic hyperthermia improved the generation of ROS and enhanced bacterial eradication. Significantly, the urchin-like nanostructure and generated ROS could stimulate macrophage polarization toward the M1 phenotype, which could eradicate the persistent bacteria with a metabolic inactivity state through phagocytosis, thereby promoting the recovery of implant infection and inhibiting recurrence. Thus, the design of magnetic-driven sharp-shaped nanostructures of Fe3O4@Bi2S3 provided enormous potential in combating biofilm infections.

Multifunctional PtCuTe Nanosheets with Strong ROS Scavenging and ROS-Independent Antibacterial Properties Promote Diabetic Wound Healing.

Nanozymes, as one of the most efficient reactive oxygen species (ROS)-scavenging biomaterials, are receiving wide attention in promoting diabetic wound healing. Despite recent attempts at improving the catalytic efficiency of Pt-based nanozymes (e.g., PtCu, one of the best systems), they still display quite limited ROS scavenging capacity and ROS-dependent antibacterial effects on bacteria or immunocytes, which leads to uncontrolled and poor diabetic wound healing. Hence, a new class of multifunctional PtCuTe nanosheets with excellent catalytic, ROS-independent antibacterial, proangiogenic, anti-inflammatory, and immuno-modulatory properties for boosting the diabetic wound healing, is reported. The PtCuTe nanosheets show stronger ROS scavenging capacity and better antibacterial effects than PtCu. It is also revealed that the PtCuTe can enhance vascular tube formation, stimulate macrophage polarization toward the M2 phenotype and improve fibroblast mobility, outperforming conventional PtCu. Moreover, PtCuTe promotes crosstalk between different cell types to form a positive feedback loop. Consequently, PtCuTe stimulates a proregenerative environment with relevant cell populations to ensure normal tissue repair. Utilizing a diabetic mouse model, it is demonstrated that PtCuTe significantly facilitated the regeneration of highly vascularized skin, with the percentage of wound closure being over 90% on the 8th day, which is the best among the reported comparable multifunctional biomaterials.

Abstract C172: PTX3 blockade restores anti-tumor immunity through suppressing M2-like macrophages phenotypes in colon cancer

Abstract The tumor microenvironment is a chronic inflammatory condition which is composed of various types of stromal cells, immune cells, and cytokines. Cancer-associated fibroblasts and M2-like macrophages are involved in enhancing malignancy of colon cancer progression, such as tumor growth and immunosuppression. Identifying the cross-talk mechanisms among cancer cells, cancer-associated fibroblasts, and M2-like macrophages is important for development of cancer therapy. Pentraxin 3 (PTX3) is a secretory factor that is rapidly responsive to exposure of proinflammatory cytokines. The function of PTX3 is known to regulate innate immunity and tissue remodeling. However, its role in tumor progression appears to be context-dependent and unclear. In this study, we found that PTX3 is silenced in colon cancer cells due to epigenetic regulation but is primarily expressed by fibroblasts in colon tumors. Clinically, higher PTX3 expression is positively correlated with fibroblast and inflammatory response signatures and associated with a poor survival outcome in colon cancer patients. Our results showed that PTX3 had no effect on cellular proliferation of fibroblasts or cancer cells in vitro, but blockade of PTX3 by specific monoclonal antibody significantly reduced stroma cell-mediated tumor growth in vivo. In addition, blockade of PTX3 reduced MC38 tumor growth in immunocompetent mice but had no effect in immunodeficient mice, suggesting the role of PTX3 in regulating tumor-immunity. Indeed, inhibition of PTX3 resulted in reduced numbers of M2-like macrophages and increased numbers of cytotoxic CD8 T cells in MC38 tumors. The expressions of cytotoxic markers in T cells were suppressed under exposure to conditioned media from PTX3-stimulated macrophages in vitro. We further revealed that PTX3 stimulated macrophage polarization toward an M2-like phenotype through activation of CREB/CEBPB axis. These findings suggest that PTX3 is involved in stroma cell-mediated protumoral immunity and targeting PTX3 by monoclonal antibody can be a potential therapeutic strategy in colon cancer treatment. Citation Format: Feng-Wei Chen. PTX3 blockade restores anti-tumor immunity through suppressing M2-like macrophages phenotypes in colon cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C172.

Placenta exosomal miRNA-30d-5p facilitates decidual macrophage polarization by targeting HDAC9.

Pregnancy involves a wide range of adaptations in the maternal body. Maternal immune tolerance toward the foreign fetus is critical for a successful pregnancy. Decidual macrophages are the primary antigen-presenting and phagocytic cells responsible for antigen presentation and apoptotic cell removal. Their phenotype changes dynamically during pregnancy. Placenta-derived exosomes are small vesicles carrying active biological molecules such as microRNAs, proteins, and lipids. The placenta-derived exosomes have been implicated in endothelial cell activation, smooth muscle cell migration, and T-cell apoptosis, but it is unknown whether placenta-derived exosomes would affect the development and functions of decidual macrophages. In this study, we reported that placenta-derived exosomes stimulated macrophage polarization into alternatively activated (M2) macrophages. Mechanistically, miRNA-30d-5p from the placenta-derived exosomes induced macrophage polarization to the M2 phenotype by targeting histone deacetylase 9. Furthermore, the conditioned medium of placenta-derived exosome-treated macrophages promoted trophoblast migration and invasion. By contrast, the conditioned medium impaired the ability of endothelial cell tube formation and migration. Placenta-derived exosome-treated macrophages had no impact on T-cell proliferation. Together, we demonstrated that placenta-derived exosomes polarize macrophages to acquire a decidua-like macrophage phenotype to modulate trophoblast and endothelial cell functions.

Synergy of antioxidant and M2 polarization in polyphenol-modified konjac glucomannan dressing for remodeling wound healing microenvironment.

Effective skin wound healing and tissue regeneration remain a challenge. Excessive/chronic inflammation inhibits wound healing, leading to scar formation. Herein, we report a wound dressing composed of KGM-GA based on the natural substances konjac glucomannan (KGM) and gallic acid (GA) that accelerates wound healing without any additional drugs. An in vitro study showed that KGM-GA could not only stimulate macrophage polarization to the anti-inflammatory M2 phenotype but also decrease reactive oxygen species (ROS) levels, indicating excellent anti-inflammatory properties. Moreover, in vivo studies of skin wounds demonstrated that the KGM-GA dressing significantly improved wound healing by accelerating wound closure, collagen deposition, and angiogenesis. In addition, it was observed that KGM-GA regulated M2 polarization, reducing the production of intracellular ROS in the wound microenvironment, which was consistent with the in vitro experiments. Therefore, this study designed a multifunctional biomaterial with biological activity, providing a novel dressing for wound healing.

An Herbal Product Alleviates Bleomycin-Induced Pulmonary Fibrosis in Mice via Regulating NF-κB/TNF-α Signaling in Macrophages.

Background and aim: Pro-inflammatory macrophages aggravated progress of pulmonary fibrosis (PF) both in patients and animal models. Fuzheng Huayu (FZHY) formula, a Chinese herbal product, is effective in treating pulmonary fibrosis in our previous study. But its action mechanism against PF relating to macrophage activation was unclear. This study was designed to evaluate the anti-fibrotic and anti-inflammatory roles of FZHY in pulmonary fibrosis and to elucidate the potential mechanisms. Methods: Network pharmacology was employed to identify the interrelationships among compounds of FZHY, potential targets and putative pathways on anti-pulmonary fibrosis. According to the data of bioinformatics analysis, the key pharmacological target for FZHY against PF was screened. The network pharmacological prediction was validated by a series of experimental assays, including CCK8, western blot and immunofluorescence staining. Then molecular mechanism of FZHY on relating to the predictive target were studied in bleomycin induced pulmonary fibrosis in mice with methylprednisolone as a positive control, and in lipopolysaccharide (LPS) stimulated cultured macrophages in culture, respectively. Results: The network pharmacology analysis reveal that a total of 12 FZHY–PF crossover proteins were filtered into a protein-protein interaction network complex and designated as the potential targets of FZHY against pulmonary fibrosis, while TNF-α signal pathway ranked at the top. FZHY and methylprednisolone could attenuate the lung fibrosis and decrease pulmonary TNF-α expression in bleomycin induced fibrotic mice, without difference between two treatments. While TNF-α was mainly originated from macrophages identified by double fluorescent staining of TNF-α and F4/80. LPS stimulated cultured macrophage polarization and activation demonstrated by the enhance contents of TNF-α and iNOS but decreased level of Arg-1. FZHY could alleviate the LPS stimulated macrophage polarization and activation demonstrated by decreasing TNF-α and iNOS and increasing Arg-1. In particular, FZHY could significantly reduce the production of p65 and the nuclear translocation of phosphorylated p65. Conclusion: Fuzheng Huayu formula has a good effect against pulmonary fibrosis induced by bleomycin in mice, whose action mechanism was associated with down-regulation of NF-κB/TNF-α signaling pathway in pro-inflammatory macrophages. These findings provided an important strategy for developing new agents against lung fibrosis and accelerated FZHY product application on patients with lung fibrosis.

Application of nanomaterials in antitumor immune response enhancement

Cancer cells are well recognized by immunotolerance characteristics, which include low immunogenicity, weak antigen presentation, low T cell infiltration, and high expression of inhibitory receptors and cytokines. This typical mechanism allows cancer cells to easily avoid the attack by immune cells, resulting in immune escape. Due to unique properties, such as adjustable size, unique surface properties, and ease of modification, nanomaterials have shown great potential in the field of immunotherapy. In this review, we summarize several ways in which nanomaterials can enhance the immune response against tumor cells. Therefore, we presently discuss the potential mechanisms involved in the induction of immune response by a series of nanomaterials. As a result, we also propose the generation of more advanced and tumor-driven nanomaterials, as well as their potential applications in tumor immunotherapy. According to the route of tumor immunity, we have currently classified nanomaterials into three categories: (1) Nanomaterials with inherent immunoregulatory functions, (2) nanomaterials that, upon an exogenous response, trigger immunogenic cell death and/or enhance immune responses, and (3) nanomaterials that are used as delivery vehicles to unload other immune-activating molecules (e.g., chemical drugs, photosensitizers, proteins and DNA plasmids) to tumors or immune cells as well as immune-activating molecules that may enhance an immune response. Some natural or synthetic nanomaterials can inherently stimulate macrophage polarization and enhance immune response. As such, nanomaterials may polarize M2 macrophages into M1 macrophages by regulating the cellular phenotype, reversing the tumor immune microenvironment and, ultimately, improving an immune cell killing activity. Cytokines or compounds with immune stimulating functions can enhance an immune response by promoting the proliferation of immune cells such as T lymphocytes and NK cells. Moreover, some nanomaterials rely on their own electrical properties or responsiveness to the tumor microenvironment, leading to tumor cell immunogenic death and/or enhancing anti-tumor immune responses. Nanomaterials have been widely used in photothermal, magnetocaloric and radiation therapies as well as into other fields, due to their unique optical, electrical, and magnetic properties. Recently, it has been discovered that some of these properties may “switch” tumor cells from non-immunogenic to immunogenic cells (i.e., immunogenic cell death) and, consequently, enhance an anti-tumor immune response. Compared with an endogenous response that mostly relies on characteristics of the tumor microenvironment, rationally designed nanomaterials that are responsive to exogenous responses can more effectively enhance the immune response at the tumor site and then achieve a more precise and tractable treatment. Hence, here we introduce the notion of an enhanced immune response, dependent on the use of nanomaterials co-stimulated by exogenous responses such as near-infrared light response, magnetic field response and others. Lastly, some substances, such as drugs, photosensitizers, proteins, plasmids, are unable to elicit a robust immune response when used without a carrier. In addition, some agents can also cause tissue damage and/or local toxicity when solely used for treatment. Thus, these substances often need to be combined with nanomaterials to achieve high biological loads, targeted delivery, controllable release and other functions to safely and efficiently enhance the anti-tumor immune response. Nevertheless, current research on nanomaterial-based immunotherapy is still under development, and the translation for clinical application is still challenging. Therefore, advances in the development of innovative therapeutic nanomaterials will offer great potential for improving the effectiveness of immunotherapy.

Abstract 3133: Reprogramming of tumor-associated macrophages by a short synthetic peptide eradicates ovarian cancer

Abstract Purpose: Ovarian cancer is the deadliest gynecologic malignancy with limited treatment options and novel therapies urgently needed. Immunosuppressive microenvironment is critical for tumor progression and immune checkpoint inhibitors, which enable T-cell anticancer immunity revolutionized the outcomes in multiple cancer types. However, this approach had limited success in ovarian cancer. Our small therapeutic peptides, derived from an endogenous type 2 tumor suppressor, Pigment Epithelium-Derived Factor (PEDF), act through an alternative immune mechanism, repolarization of tumor-associated macrophages (TAMs) to the tumor-suppressive phenotype.Experimental Design: Short peptides based on the PEDF's active domain were modified for improved stability and efficacy. Two peptides (PMD-427, PMD-336) were tested in preclinical ovarian cancer models using the human chemoresistant cell line, OvCar-3, and transformed mouse cell line ID8. We also performed mechanistic analysis of the peptides' anti-tumor action, including effects on macrophages cytotoxic, cytokine secretion and migratory activity in vitro and in vivo. Results: PEDF peptide PMD-427 caused > 20-fold reduction in tumor burden. PMD-427 induced selective apoptosis in ovarian cancer cells but not in normal ovarian epithelium. This selectivity was based on context-specific modulation of extrinsic death cascades, Fas and FasL. More importantly, PMD-427 peptides also stimulated macrophage polarization from M2 to M1 phenotype as was evidenced by the shift in cytokine profile (decreased IL-10 and increased IL-12 expression), altered morphology (increased number of dendrite-like-processes) and other changes in M2 markers (attenuated PD-L1 expression). M2/M1 macrophage polarization was also evident by tumor immunostaining. Critically, PMD peptides ovarian cancer cell killing by macrophages as was determined in co-culture studies; this fratricidal activity was reliant on the expression of TRAIL by the macrophages and of its cognate receptor, DR5 by ovarian cancer cells, respectively. Combined with enhanced macrophage motility as observed by time-lapse micropscopy, these changes resulted in increased macrophage recruitment to the tumors and enhance killing of the cancer cells in vivo. The key role of macrophages in the anti-cancer effects of PMD peptides was confirmed by depletion of macrophages in ovarian tumor bearing mice using clodronate liposomes. Conclusions: We have generated a first-in-class multi-targeted peptide drug, which promotes macrophage polarization that results in eradication of ovarian tumors in mice. Citation Format: Reshma Bhowmick, Elena Vinokour, Michael Paul Plebanek, Marisol Villanueva, Victor Shifrin, Jack Henkin, Ignacio Melgar-Asensio, James Petrik, Raghu Kallurie, Olga V. Volpert. Reprogramming of tumor-associated macrophages by a short synthetic peptide eradicates ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3133.

Dual-inflammatory cytokines on TiO2 nanotube-coated surfaces used for regulating macrophage polarization in bone implants.

Excessive immune responses following the use of implantable, biomaterial-based medical devices represent a substantial challenge for treatment efficacy and patient well-being. Specifically, after implantation, pro-inflammatory M1 macrophages are activated by cytokines such as interferon-γ (IFN-γ) followed by anti-inflammatory M2 macrophages polarized by cytokines including interleukin-4 (IL-4), leading to healing and long-term stability of implants. Here, we report the loading of an immunomodulatory cytokine,IL-4, into TiO2 nanotubes (TNTs) followed by hydrogel coating on the TNTs for subsequent release of IL-4. Finally, IFN-γ was added onto the gel layer to effect rapid release. The release rates of both cytokines from the samples were monitored using an immersion test in phosphate-buffered solution. The cytocompatibility of the sample was evaluated using cultures of osteoblasts and macrophages. Macrophage phenotype switching in vitro was examined via cytokine secretion and gene expression analyses. In vitro testing showed that the sample could stimulate macrophage polarization from the M1 to M2 phenotype at the desired period owing to temporal release of IFN-γ and IL-4. Another biomaterial containing only IL-4 in TNTs was also able to modulate the transformation of M1 to M2 although with weaker effect than that containing IFN-γ and IL-4. The biomaterial may be useful as an osteoimplant in vivo owing to the inflammation caused by a wound or implantation. This study provided biomaterials capable of facilitating smooth M1 to M2 macrophages switching, which might be helpful to research immune responses of tissues to implants and will likely contribute to the development of bone substitute materials. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1878-1886, 2018.

Complement 5a stimulates macrophage polarization and contributes to tumor metastases of colon cancer

Inflammatory cells such as macrophages can play a pro-tumorigenic role in the tumor stroma. Tumor-associated macrophages (TAMs) generally display an M2 phenotype with tumor-promoting activity; however, the mechanisms regulating the TAM phenotype remain unclear. Complement 5a (C5a) is a cytokine-like polypeptide that is generated during complement system activation and is known to promote tumor growth. Herein, we investigated the role of C5a on macrophage polarization in colon cancer metastasis in mice. We found that deficiency of the C5a receptor (C5aR) severely impairs the metastatic ability of implanted colon cancer cells. C5aR was expressed on TAMs, which exhibited an M2-like functional profile in colon cancer liver metastatic lesions. Furthermore, C5a mediated macrophage polarization and this process relied substantially on activation of the nuclear factor-kappa B (NF-κB) pathway. Finally, analysis of human colon carcinoma indicated that C5aR expression is negatively associated with tumor differentiation grade. Our results demonstrate that C5aR has a central role in regulating the M2 phenotype of TAMs, which in turn, contributes to hepatic metastasis of colon cancer through NF-κB signaling. C5a is a potential novel marker for cancer prognosis and drugs targeting complement system activation, specifically the C5aR pathway, may offer new therapeutic opportunities for colon cancer management.

Breast cancer cell-derived exosomes and macrophage polarization are associated with lymph node metastasis.

Crosstalk between breast cancer and macrophages has potential implications for tumor metastasis. This study investigates macrophage polarization induced by triple-negative breast cancer (TNBC) cell-derived exosomes that promote lymph node (LN) metastasis in orthotopic TNBC models. The MDA-MB-231 cancer cell line expressing the exosomal CD63-red fluorescence (RFP) fusion protein was generated to noninvasively visualize exosome transfer into cancer cells and macrophages. Administration of RFP-tagged exosomes enhanced migration of macrophages and induced macrophage polarization in vitro. In orthotopic TNBC models, noninvasive bioluminescent imaging, ultrasound-guided photoacoustic imaging, and histological analysis revealed that intravenous injection of RFP-tagged exosomes promoted primary tumor growth and axillary LN metastasis in which expression of CD206, a marker or alternatively activated type 2 (M2) macrophages, was significantly higher than expression of NOS2, a marker of classically activated type 1 (M1) macrophages. These results suggest breast cancer cell-derived exosomes stimulate macrophage polarization that creates favorable conditions for LN metastatic processes in TNBC.

Oxysterol mixture and, in particular, 27-hydroxycholesterol drive M2 polarization of human macrophages.

Macrophages play a crucial role in atherosclerosis progression. Classically activated M1 macrophages have been found in rupture-prone atherosclerotic plaques whereas alternatively activated macrophages, M2, localize in stable plaque. Macrophage accumulation of cholesterol and of its oxidized derivatives (oxysterols) leads to the formation of foam cells, a hallmark of atherosclerotic lesions. In this study, the effects of oxysterols in determining the functional polarization of human macrophages were investigated. Monocytes, purified from peripheral blood mononuclear cells of healthy donors, were differentiated into macrophages (M0) and treated with an oxysterol mixture, cholesterol, or ethanol, every 4 H for a total of 4, 8, and 12 H. The administration of the compounds was repeated in order to maintain the levels of oxysterols constant throughout the treatment. Compared with ethanol treatment, the oxysterol mixture decreased the surface expression of CD36 and CD204 scavenger receptors and reduced the amount of reactive oxygen species whereas it did not affect either cell viability or matrix metalloprotease-9 activity. Moreover, the oxysterol mixture increased the expression of both liver X receptor α and ATP-binding cassette transporter 1. An enhanced secretion of the immunoregulatory cytokine IL-10 accompanied these events. The results supported the hypothesis that the constant levels of oxysterols and, in particular, of 27-hydroxycholesterol stimulate macrophage polarization toward the M2 immunomodulatory functional phenotype, contributing to the stabilization of atherosclerotic plaques.

Inhibition of myostatin in mice improves insulin sensitivity via irisin-mediated cross talk between muscle and adipose tissues.

Background/ObjectiveIn mice, a high fat diet (HFD) induces obesity, insulin resistance and myostatin production. We tested whether inhibition of myostatin in mice can reverse these HFD-induced abnormalities.Subjects/MethodsC57BL/6 mice were fed a HFD for 16 weeks including the final 4 weeks some mice were treated with an anti-myostatin peptibody. Body composition, the respiratory exchange ratio plus glucose and insulin tolerance tests were examined. Myostatin knock down in C2C12 cells was performed using ShRNA lentivirus. Adipose tissue-derived stem cells were cultured to measure their reponses to conditioned media from C2C12 cells lacking myostatin, or to recombinant myostatin or Irisin. Isolated peritoneal macrophages were treated with myostatin or Irisin to determine if myostatin or Irisin induce inflammatory mechanisms.ResultsIn HFD-fed mice, peptibody treatment stimulated muscle growth and improved insulin resistance. The improved glucose and insulin tolerances were confirmed when we found increased muscle expression of p-Akt and the glucose transporter, Glut4. In mice fed the HFD, the peptibody suppressed macrophage infiltration and the expression of proinflammatory cytokines in both muscle and adipocytes. Inhibition of myostatin caused the conversion of white (WAT) to brown adipose tissue (BAT) while stimulating fatty acid oxidation and increasing energy expenditure. The related mechanism is a muscle-to-fat cross talk mediated by Irisin. Myostatin inhibition increased PGC-1α expression and Irisin production in muscle. Irisin then stimulated WAT browning. Irisin also suppresses inflammation and stimulates macrophage polarization from M1 to M2 types.Concusionthese results uncover a metabolic pathway from an increase in myostatin that suppresses Irisin leading to activation of inflammatory cytokines and insulin resistance. Thus, myostatin is a potential therapeutic target to treat insulin resistance of type II diabetes as well as the shortage of brown/beige fat in obesity.

AB0210 Effects of Endothelin-1 on M2 Macrophage Polarization in Cultured Human Macrophages

BackgroundMacrophage lineage may undergo two different polarization states: classically activated (M1) and alternatively activated (M2) macrophages: both macrophage populations represent the extremes of a continuum of functional states (1, 2)....