Macrophage-derived Microvesicles Research Articles

Pyroptotic Macrophage-Derived Microvesicles Accelerate Formation of Neutrophil Extracellular Traps via GSDMD-N-expressing Mitochondrial Transfer during Sepsis.

Macrophage pyroptosis and neutrophil extracellular traps (NETs) play a critical role in sepsis pathophysiology; however, the role of macrophage pyroptosis in the regulation of NETs formation during sepsis is unknown. Here, we showed that macrophages transfer mitochondria to neutrophils through microvesicles following pyroptosis; this process induces mitochondrial dysfunction and triggers the induction of NETs formation through mitochondrial reactive oxygen species (mtROS)/Gasdermin D (GSDMD) axis. These pyroptotic macrophage-derived microvesicles can induce tissues damage, coagulation, and NETs formation in vivo. Disulfiram partly inhibits these effects in a mouse model of sepsis. Pyroptotic macrophage-derived microvesicles induce NETs formation through mitochondrial transfer, both in vitro and in vivo. Microvesicles-mediated NETs formation depends on the presence of GSDMD-N-expressing mitochondria in the microvesicles. This study elucidates a microvesicles-based pathway for NETs formation during sepsis and proposes a microvesicles-based intervention measure for sepsis management.

131 Alveolar Macrophage Degranulation Initiates the Spatially Restricted Innate Immune Response During Ventilator-Assisted Nanoparticle Inhalation

Abstract To visualize and measure in real-time the cellular pulmonary innate immune response elicited by inhaled NPs, we apply state-of-the-art intravital microscopy on the alveolar region of the murine lung. Fluorescent carboxyl-quantum-dot-NPs (deposited dose of 16 cm2/g) applied via ventilator-assisted inhalation accumulated within seconds as distinct fluorescent spots at the alveolar walls. Already at 30min, cQD-NPs elicited an increase in microvascular neutrophil numbers as compared to controls, which subsequently transmigrated into the alveolar space. This early immune response was not specific to cQD-NPs, since a comparable increase in neutrophil numbers was also observed upon inhalation of a bioequivalent dose of carbon black NPs, a typical component of urban air pollution. AMs actively accumulated cQD-NPs over time, starting few minutes after inhalation. Significantly more neutrophils were attracted in proximity to cQD-NP-laden AMs, as compared to NP-free AMs or control areas with epithelial associated cQD-NP. Prior airway application of a cellular degranulation inhibitor prevented cQD-NP and CNP induced neutrophil recruitment at 2h and 24 h after inhalation. Inhibition of Fcγ-receptor mediated AM cQD-NP uptake by prior application of anti-CD64 mAbs or neutralizing of TNFα by anti-TNFα mAbs in the airspace, abolished this early immune response. Importantly, initial ImageStream flow cytometry analysis of BAL samples indicated an increase of macrophage-derived microvesicles upon NP inhalation. Taken together, our data links NP-induced AM degranulation and cytokine release to the rapid and site-specific recruitment of neutrophils, suggesting this process to be a key event in mounting the immune response upon NP inhalation.

CD169+ subcapsular sinus macrophage-derived microvesicles are associated with light zone follicular dendritic cells.

Follicular dendritic cells (FDCs) are a specialized type of stromal cells that exclusively reside in B-cell follicles. When inflammation occurs, the FDC network is reorganized to support germinal center (GC) polarization into the light zone (LZ) and dark zone (DZ). Despite the indispensable role of FDCs in supporting humoral responses, the FDC regulatory requirements remain incompletely defined. In this study, we unexpectedly observed an accumulation of CD169+ subcapsular sinus macrophage (SSM)-derived microvesicles (MVs) in the B-cell zone, which were tightly associated with the FDC network. Interestingly, a selective deposition of CD169+ MVs was detected in both GC LZ FDCs in secondary follicles and on predetermined LZ FDCs in primary follicles. The ablation of CD169+ MVs, resulting from SSM depletion, resulted in significantly decreased expression of LZ-related genes in FDCs. In addition, we found that CD169+ MVs could colocalize with fluorescently tagged antigen-containing immune complexes (ICs), supporting a possible role of CD169+ MVs in transporting antigens to the FDC network. Thus, our data reveal intimate crosstalk between FDCs and SSMs located outside B-cell follicles via SSM-released MVs, providing a novel perspective on the mechanisms underlying the regulation of FDC maturation and polarization.

ZIF-8 nanoparticles coated with macrophage-derived microvesicles for sustained, targeted delivery of dexamethasone to arthritic joints

Dexamethasone sodium phosphate (Dex) is widely used in the clinic for the treatment of rheumatoid arthritis. However, it circulates in the blood for a short time and it is linked to a high risk of severe side effects caused by repeated dosing. Here, we encapsulated Dex onto zeolitic imidazolate framework-8 (ZIF-8) to prepare metal–organic framework nanoparticles with high drug loading efficiency. To prevent clearance by the mononuclear phagocyte system and extend time in circulation, the nanoparticles were also camouflaged with macrophage-derived microvesicles (MV) to obtain the biomimetic drug delivery system MV/Dex/ZIF-8. In vitro and in vivo experiments showed that the nanosystem had high drug loading and encapsulation efficiency, high stability, and long circulation time, and it permitted sustained drug release longer in inflamed joint tissues. Our study provides new insights into designing camouflaged drug carriers to prevent their phagocytosis and prolong their time in circulation.

Inflammatory alveolar macrophage-derived microvesicles damage lung epithelial cells and induce lung injury

Emerging evidence has demonstrated that several microvesicles (MVs) are secreted in bronchoalveolar lavage fluid (BALF) during the pathogenesis of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). However, the impact of alveolar macrophage (AM)-derived MVs on epithelial cells and their in vivo effects on ALI/ARDS require further exploration. In this study, MVs were isolated from BALF of mice or mouse alveolar macrophage (MHS) cells by sequential centrifugation and then delivered to epithelial cells or mice. Enzyme-linked immunosorbent assay revealed that BALF-derived MVs (BALF-MVs) and MHS-derived MVs (AM-MVs) were rich in tumor necrosis factor-α (TNF-α) at the early stage of lung injury. In vitro, both inflammatory BALF-MVs and AM-MVs decreased the expression of α subunit of epithelial sodium channel (α-ENaC), γ-ENaC, and Na+,K+-ATPase α1 and β1 in lung epithelial cells. However, antibodies against TNF-α inhibited the effects of inflammatory AM-MVs in epithelial cells. In vivo, the inflammatory AM-MVs, delivered intratracheally to mice, impaired lung tissues and increased the injury score. They also resulted in decreased alveolar fluid clearance and increased lung wet weight/dry weight ratio. Furthermore, inflammatory AM-MVs downregulated the α-ENaC, γ-ENaC, and Na+,K+-ATPase α1 and β1 levels in lung tissues. According to our results, inflammatory AM-derived MVs may potentially contribute to lung injury and pulmonary edema, thereby indicating a potential novel therapeutic approach against ALI/ARDS based on AM-MVs.

Microvesicles produced by monocytes affect the phenotype and functions of endothelial cells

<abstract> Monocytes\macrophages regulate angiogenesis via cytokine production and contact interactions with endothelial cells (ECs). The biological effects of macrophage-derived microvesicles (MVs) are studied using cell lines, such as monocytic leukemia THP-1 cell line. The effect of MVs produced by THP-1 cells on EC phenotype and functions remain understudied. In this research, we studied the effect of MVs produced by THP-1 cells on the phenotype, proliferation, migration, and vascular formation of EA.Hy926 ECs. MVs produced by THP-1 cells express CD54, CD18, CD11a, CD11b, CD29, CD120a, CD120b, VEGFR1, VEGFR2, CD105, CD119, TGFR2 on the surface and contain ERK1/2, pERK1/2 Akt, FGF10, endothelin-2. The transfer of an intracellular protein labeled with a fluorescent dye from MVs produced by THP-1 cells to EA.Hy926 ECs was established. It was found that MVs derived from THP-1 cells inhibit EC proliferation. In high concentrations, MVs reduce EC migration, increase the length but decrease the number of vessels formed by ECs, promoting the development of non-branching angiogenesis. On the contrary, in low concentrations, MVs increase EC migration, reduce the length, and increase the number of vessels formed by ECs, promoting the development of branching angiogenesis. Thus, the fundamental possibility of the influence of MVs produced by THP-1 cells on the processes of angiogenesis has been established. Proteins found in the MVs composition may be responsible for the observed effects of MVs on ECs. </abstract>

Proinflammatory macrophage-derived microvesicles exhibit tumor tropism dependent on CCL2/CCR2 signaling axis and promote drug delivery via SNARE-mediated membrane fusion.

Background: Exosome (Exo)-based chemotherapeutic drug delivery systems have been extensively investigated; however, the therapeutic potential of other subtypes of extracellular vesicles (EVs), in particular microvesicles (MiV), seem to be overlooked. Moreover, despite a general agreement on organ tropism of EVs, few studies have clearly demonstrated that EVs specifically target tumor tissue.Methods: Proinflammatory macrophage-derived EV subpopulations comprising apoptotic bodies (ApB), MiV and Exo were isolated under differential ultracentrifugation, and further analyzed using comparative proteomic and lipid approach.Results: On the basis of EV biogenesis pathways, our data demonstrated that MiV acquire the tumor-targeting capacity probably through inheritance of CCR2-enriched cell membrane which also drives the recruitment of donor cells to tumor sites. Further, our data validate MiV utilize SNARE-mediated membrane fusion to directly discharge doxorubicin to nucleus and bypass endocytic degradation.Conclusions: Compared with other EV subtypes, MiV loaded with doxorubicin gain significant benefits in chemotherapeutic outcomes including survival rate improvements in metastatic ovarian cancer. Therefore, MiV represent a potent alterative to Exo and synthetic liposomes (Lipo) for tumor-targeting drug delivery.

Macrophages Tell the Non-Professionals What to Do

Phagocytosis by professional and non-professional phagocytes plays a critical role in tissue homeostasis and the immune response. Using an airway inflammation model, Han etal. (2016) report in Nature that macrophages secrete IGF-1 to signal epithelial cells to stop ingesting apoptotic cells while increasing the uptake of anti-inflammatory macrophage-derived microvesicles.

Alveolar macrophage-derived microvesicles mediate acute lung injury

BackgroundMicrovesicles (MVs) are important mediators of intercellular communication, packaging a variety of molecular cargo. They have been implicated in the pathophysiology of various inflammatory diseases; yet, their role in acute...

Macrophage-derived microvesicles promote proliferation and migration of Schwann cell on peripheral nerve repair

BackgroundMacrophages have been implicated in peripheral nerve regeneration. However, whether macrophages-derived microvesicles (MVs) are involved in this process remains unknown. In the present study, the effects of macrophages-derived MVs on proliferation and migration of Schwann cells (SCs) were evaluated in both in vitro and in vivo. MethodsHuman monocytic leukaemia cell line (THP-1) was successfully driven to M1 and M2 phenotypes by delivery of either IFN-γ or IL-4, respectively. SCs incubated with M1 or M2 macrophages-derived MVs, the cell migration and proliferation were assessed, and expression levels of nerve growth factor (NGF) and Laminin were measured. A rat model of sciatic nerve was established and the effects of macrophages-derived MVs on nerve regeneration were investigated. ResultsM2-derived MVs elevated migration, proliferation, NFG and Laminin protein levels of SCs compared with M1-or M0-derived MVs. The relative expression levels of miR-223 were also increased in M2 macrophages and M2-derived MVs. Transfected M2 macrophages with miR-223 inhibitor then co-incubated with SCs, an inhibition of cell migration and proliferation and a down-regulated levels of NFG and Laminin protein expression were observed. In vivo, M2-derived MVs significantly increased the infiltration and axon number of SCs. ConclusionM2-derived MVs promoted proliferation and migration of SCs in vitro and in vivo, which provided a therapeutic strategy for nerve regeneration.

Inflamed macrophage microvesicles induce insulin resistance in human adipocytes.

BackgroundCytokines secreted by adipose tissue macrophages (ATMs) significantly alter adipocyte function, inducing inflammatory responses and decreasing insulin sensitivity. However, little relevant information is available regarding the role of microvesicles (MVs) derived from ATMs in macrophage-adipocyte crosstalk.MethodsMVs were generated by stimulation of M1 or M2 phenotype THP-1 macrophages and incubated with human primary mature adipocytes and differentiated adipocytes. Subsequently, insulin-stimulated phosphorylation of Akt (pAkt) and glucose uptake were determined. Glucose transporter 4 (GLUT4) translocation and nuclear translocation of nuclear factor (NF)-kappa B were also analyzed in treated adipocytes.ResultsM1 macrophage-derived MVs (M1 MVs) significantly reduced protein abundance of insulin-induced Akt phosphorylation in human primary mature adipocytes and differentiated adipocytes, when compared with the same concentration of M2 macrophage-derived MVs (M2 MVs). In contrast to M2 MVs, which enhanced the insulin-induced glucose uptake measured by 2-NBDG, M1 MVs decreased this effect in treated adipocytes. M1 MVs treatment also brought about a significant increase in the nuclear translocation of nuclear factor (NF)-kappa B, coupled with a decrease in pAkt level and GLUT4 translocation compared with M2 MVs-treated adipocytes. These effects were reversed by BAY 11–7085, a NF- kappa B specific inhibitor.ConclusionsMVs derived from proinflammatory (M1) macrophages may, at least in part, contribute to the pathogenesis of obesity-induced insulin resistance, reducing insulin signal transduction and decreasing glucose uptake in human adipocytes, through NF-kappa B activation. Therefore, these MVs may be potential therapy candidates for the management of type 2 diabetes mellitus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12986-015-0016-3) contains supplementary material, which is available to authorized users.

WITHDRAWN: Macrophage-derived microvesicles promote proliferation and migration of Schwann cells on peripheral nerve repair

WITHDRAWN: Macrophage-derived microvesicles promote proliferation and migration of Schwann cells on peripheral nerve repair

Combining magnetic nanoparticles with cell derived microvesicles for drug loading and targeting

Inspired by microvesicle-mediated intercellular communication, we propose a hybrid vector for magnetic drug delivery. It consists of macrophage-derived microvesicles engineered to enclose different therapeutic agents together with iron oxide nanoparticles. Here, we investigated in vitro how magnetic nanoparticles may influence the vector effectiveness in terms of drug uptake and targeting. Human macrophages were loaded with iron oxide nanoparticles and different therapeutic agents: a chemotherapeutic agent (doxorubicin), tissue-plasminogen activator (t-PA) and two photosensitizers (disulfonated tetraphenyl chlorin-TPCS2a and 5,10,15,20-tetra(m-hydroxyphenyl)chlorin-mTHPC). The hybrid cell microvesicles were magnetically responsive, readily manipulated by magnetic forces and MRI-detectable. Using photosensitizer-loaded vesicles, we showed that the uptake of microvesicles by cancer cells could be kinetically modulated and spatially controlled under magnetic field and that cancer cell death was enhanced by the magnetic targeting. From the Clinical EditorIn this article, the authors devised a biogenic method using macrophages to produce microvesicles containing both iron oxide and chemotherapeutic agents. They showed that the microvesicles could be manipulated by magnetic force for targeting and subsequent delivery of the drug payload against cancer cells. This smart method could provide a novel way for future fight against cancer.

Macrophage microvesicles induce macrophage differentiation and miR-223 transfer

AbstractMicrovesicles are small membrane-bound particles comprised of exosomes and various-sized extracellular vesicles. These are released by several cell types. Microvesicles have a variety of cellular functions from communication to mediating growth and differentiation. Microvesicles contain proteins and nucleic acids. Previously, we showed that plasma microvesicles contain microRNAs (miRNAs). Based on our previous report, the majority of peripheral blood microvesicles are derived from platelets, while mononuclear phagocytes, including macrophages, are the second most abundant population. Here, we characterized macrophage-derived microvesicles and explored their role in the differentiation of naive monocytes. We also identified the miRNA content of the macrophage-derived microvesicles. We found that RNA molecules contained in the macrophage-derived microvesicles were transported to target cells, including mono cytes, endothelial cells, epithelial cells, and fibroblasts. Furthermore, we found that miR-223 was transported to target cells and was functionally active. Based on our observations, we hypothesize that microvesicles bind to and activate target cells. Furthermore, we find that microvesicles induce the differentiation of macrophages. Thus, defining key components of this response may identify novel targets to regulate host defense and inflammation.

Dissecting Macrophage-Derived Microvesicles' Content and Function.

AbstractAbstract 3785Microvesicles (MVs) are small membrane-bound vesicles released under normal homeostatic and stimulatory conditions by a wide variety of cell types. Microvesicles are collectively referred to as exosomes and microparticles which vary in size due to different cellular mechanisms responsible for their production. These microvesicles have a wide range of functions from facilitating communication to regulating cellular growth and differentiation. During their production; microvesicles become enriched in various molecules including proteins and nucleic acids. Previously, we have shown that plasma microvesicles derived from many cell lineages contain microRNAs (miRNAs). We also found that the majority of the peripheral blood microvesicles are derived from platelets while those originating from monocytic cells including macrophages represent the second largest population. Since microvesicles derived from mononuclear phagocytes are a large subpopulation in the plasma; we were interested in understanding their content and function. We hypothesized that the content and/or quantity of macrophage-derived microvesicles could induce the maturation of monocytes. To address our hypothesis, peripheral blood monocytes were treated in vitro for 4hr with GM-CSF; washed and cultured in media devoid of cytokines for 24 h then microvesicles were collected. Flow cytometry and electron)confocal microscropy were used to quantify and visualize microvesicles production. To examine the function of the microvesicles on macrophage maturation, the purified microvesicles were then cultured with freshly isolated monocytes. Macrophage differentiation was determined by cellular adherence using a crystal violet uptake assay and changes in surface antigen expression by flow cytometry. We also examined the genetic changes induced in monocytes incubated with the microvesicles compared to GM-CSF-treated cells. We found that freshly isolated monocytes treated with microvesicles from macrophages acquired phenotypic characteristics of a macrophage such as cellular adherence and surface antigen expression. We also found that treatment of naïve monocytes with the microvesicles induced molecular changes similar to GM-CSF treated monocytes. We found more than 7985 mRNAs that were similarly expressed between the two culture conditions. Notably, we observed the unique expression of 1324 and 1079 genes in the GM-CSF-treated compared to the microvesicle-treated cells, respectively. To begin dissecting the molecules contained in the microvesicles responsible for these changes, we performed mass-spectrometry and miRNA profiling. We observed the expression of miRs-223, -222,-191, -484, -016, -026a, and -155 in GM-CSF-derived microvesicles. Notably, these miRNAs were also expressed in the cells from which the microvesicles were released. We have begun bioinformatics analyses to predict whether the expression of the miRNAs may account for the decrease expression of specific genes in cells treated with the microvesicles that undergo differentiation. Many of the proteins found in the vesicles are important in facilitating protein:protein interactions and nucleic acid binding. Based on our observations; we postulate that microvesicles in areas of inflammation may contribute to the inflammatory response through the maturation of immune cells and activation of cells responsible for tissue repair. Thus, defining key components of this response may identify targets to regulate inflammation. Disclosures:No relevant conflicts of interest to declare.