Project description:Microvesicles (MV) are small membrane-bound particles comprised of exosomes and various sized extracellular vesicles. These are released by a number of 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 whether they influenced the differentiation of naM-CM-/ve 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 monocytes, 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. We used GeneChip microarrays to examine changes in gene expression induced by MV in primary monocyte-derived macrophages (MDM) and in THP1 cells, and compare this to cells treated with GM-CSF and PMA, respectively. All experiments were done in triplicates. Primary monocytes were collected from buffy coats (BC). The freshly isolated monocytes from three donors (Mono1-3) were either treated with GM-CSF or subjected to RNA isolation. Following treatment, MVs were isolated from the GM-CSF-treated macrophage cultures. RNA was isolated from the remaining cells for profiling (GM1-3). The isolated MVs were then used to treat new BC monocytes for 24 h (BC-GMCSF-MV24). A fraction of the new BC monocytes was subjected to RNA extraction for profiling (BC1-3). For THP1 cells, they were treated with either DMSO or PMA to produce MVs. The MVs were collected and the remaining cells lyzed for RNA extraction and profiling (DMSO1-3 and PMA1-3). The collected MVs from the DMSO or PMA-treated THP1 cells were incubated with new THP1 for 24 h and designated DMSO-MV24 or PMA-MV24. We had a total of 24 samples.

Project description:Acute lung injury (ALI) is characterized by acute respiratory failure in the setting of non-cardiogenic pulmonary edema, causing acute respiratory distress syndrome (ARDS) in patients and contributes significantly to mortality of critically illness. The main goal of our study is to elucidate the role of miRNAs in neutrophil-epithelial communication during pulmonary inflammation and thereby identifying novel targets for therapy of acute lung injury (ALI). In our studies we identified a miR-223-dependent neutrophil-epithelial crosstalk during ALI. Activated neutrophils (PMN) and pulmonary epithelial cells come into a close spatial relationship during ALI. And, since previous studies had indicated the possibility that inflammatory cell-dependent release of miRNA-containing microvesicles could function as a means of exchanging genetic information from a donor to a target cell, we assessed PMN-elicited alterations of pulmonary epithelial miRNA expression in an experimental co-culture setup. This approach provided a selective and extremely robust readout: While other miRNAs were not or only moderately altered in their expression, pulmonary-epithelial-expressed miR-223 was significantly induced after 4 or 6h of co-incubation. Additional in vitro and in vivo studies clearly demonstrate that this increase of epithelial miR-223 is not due to miR-223 transcriptional induction, but instead PMN-dependent and caused by shuttling miR-223 from PMN into pulmonary epithelial cells. To address the functional role of miR-223-dependent neutrophil-epithelial crosstalk during ALI, we exposed mice to ventilator-induced ALI and observed robust induction of pulmonary miR-223 during ALI, while increases of miR-223 were completely abolished after antibody-depletion of PMN. Moreover, studies of alveolar epithelial cells isolated from mice with ALI showed robust increases of miR-223, indicating that miR-223 is shuttled from PMN towards alveolar epithelia during ALI in vivo. Functional studies revealed that gene-targeted mice for miR-223 experience a more severe phenotype during ALI as compared to controls, while their phenotype could be resuscitated by nanoparticle-mediated overexpression of miR-223 in the lungs. In summary, these studies reveal a novel role of miR-223-dependent neutrophil-epithelial crosstalk representing an anti-inflammatory pathway that can be targeted for ALI treatment.

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