SUMMARY
Developing strategies that promote the resolution of vascular inflammation and atherosclerosis remains a major therapeutic challenge. Here, we show that exosomes produced by naive bone marrow-derived macrophages (BMDM-exo) contain anti-inflammatory microRNA-99a/146b/378a that are further increased in exosomes produced by BMDM polarized with IL-4 (BMDM-IL-4-exo). These exosomal microRNAs suppress inflammation by targeting NF-κB and TNF-α signaling and foster M2 polarization in recipient macrophages. Repeated infusions of BMDM-IL-4-exo into
Apoe
−/−
mice fed a Western diet reduce excessive hematopoiesis in the bone marrow and thereby the number of myeloid cells in the circulation and macrophages in aortic root lesions. This also leads to a reduction in necrotic lesion areas that collectively stabilize atheroma. Thus, BMDM-IL-4-exo may represent a useful therapeutic approach for atherosclerosis and other inflammatory disorders by targeting NF-κB and TNF-α via microRNA cargo delivery.
The intestinal microbiota influences mammalian host physiology in health and disease locally in the gut but also in organs devoid of direct contact with bacteria such as the liver and brain. Extracellular vesicles (EVs) or outer membrane vesicles (OMVs) released by microbes are increasingly recognized for their potential role as biological shuttle systems for inter‐kingdom communication. However, physiologically relevant evidence for the transfer of functional biomolecules from the intestinal microbiota to individual host cells by OMVs in vivo is scarce. By introducing
Escherichia coli
engineered to express Cre‐recombinase (
E. coli
Cre
) into mice with a
Rosa26.tdTomato
‐reporter background, we leveraged the Cre‐LoxP system to report the transfer of bacterial OMVs to recipient cells in vivo. Colonizing the intestine of these mice with
E. coli
Cre
, resulted in Cre‐recombinase induced fluorescent reporter gene‐expression in cells along the intestinal epithelium, including intestinal stem cells as well as mucosal immune cells such as macrophages. Furthermore, even far beyond the gut, bacterial‐derived Cre induced extended marker gene expression in a wide range of host tissues, including the heart, liver, kidney, spleen, and brain. Together, our findings provide a method and proof of principle that OMVs can serve as a biological shuttle system for the horizontal transfer of functional biomolecules between bacteria and mammalian host cells.
Summary
We investigated whether extracellular vesicles (EVs) produced under hyperglycemic conditions could communicate signaling to drive atherosclerosis. We did so by treating Apoe
−/−
mice with exosomes produced by bone marrow-derived macrophages (BMDM) exposed to high glucose (BMDM–HG-exo) or control. Infusions of BMDM–HG-exo increased hematopoiesis, circulating myeloid cell numbers, and atherosclerotic lesions with an accumulation of macrophage foam and apoptotic cells. Transcriptome-wide analysis of cultured macrophages treated with BMDM–HG-exo or plasma EVs isolated from subjects with type II diabetes revealed a reduced inflammatory state and increased metabolic activity. Furthermore, BMDM–HG-exo induced cell proliferation and reprogrammed energy metabolism by increasing glycolytic activity. Lastly, profiling microRNA in BMDM–HG-exo and plasma EVs from diabetic subjects with advanced atherosclerosis converged on miR-486-5p as commonly enriched and recognized in dysregulated hematopoiesis and
Abca1
control. Together, our findings show that EVs serve to communicate detrimental properties of hyperglycemia to accelerate atherosclerosis in diabetes.
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