An Endocrine Genetic Signal Between Blood Cells and Vascular Smooth Muscle Cells

Abstract

BACKGROUND MicroRNA-223 (miR-223) is a hematopoietic lineage cell-specific microRNA. However, a significant amount of miR-223 has been identified in vascular smooth muscle cells (VSMCs) and vascular walls that should not have endogenous miR-223. OBJECTIVES This study sought to determine the sources of miR-223 in normal and atherosclerotic arteries and the role of miR-223 in atherogenesis. METHODS The levels and sources of miR-223 in blood cells (leukocytes and platelets), serum, blood microparticles, VSMCs, and vascular walls were determined. Both in vivo and in vitro studies were conducted to evaluate miR-223 secretion by blood cells and the ability of miR-223 to enter VSMCs and vascular walls. Subsequent changes in and the effects of miR-223 levels on serum and arteries in atherosclerotic animals and patients were investigated. RESULTS Blood cells were able to secrete miR-223 into serum. MicroRNA-223 from blood cells was the most abundant cell-free miRNA in blood. Blood cell-secreted miR-223 could enter VSMCs and vascular walls, which produced strong biological effects via its target genes. In both atherosclerotic apolipoprotein-E knockout mice and patients with atherosclerosis, miR-223 levels were significantly increased in serum and atherosclerotic vascular walls. The atherosclerotic lesions in apolipoprotein-E knockout mice were exacerbated by miR-223 knockdown. The effect of miR-223 on atherogenesis was verified using miR-223 knockout mice. CONCLUSIONS Blood cell-secreted miR-223 enters vascular cells and walls, and appears to play important roles in VSMC function and atherogenesis. As a novel endocrine genetic signal between blood cells and vascular cells, miR-223 may provide a novel mechanism and new therapeutic target for atherosclerosis.

Bone Marrow–Derived MicroRNA‐223 Works as an Endocrine Genetic Signal in Vascular Endothelial Cells and Participates in Vascular Injury From Kawasaki Disease

“…In brief, the medium was centrifuged at 1600 g for 15 minutes at 4°C. This technique removed all cells, but the microparticles or exosomes remained; removal of these smaller entities requires centrifuging at a higher speed for a longer time, as we showed previously . The levels of miR‐223 in collected medium were determined and were increased with the increased THP‐1 macrophages .…”

“…RNAs were isolated with TRIzol . Levels of miRNAs and mRNAs were determined by quantitative reverse transcriptase–polymerase chain reaction (qRT‐PCR).…”

“…The chimeric mice were generated in our laboratory by transplantation of bone marrow from miR‐223 knockout mice into lethally irradiated wild‐type mice, as described previously . The well‐established leukocyte depletion model in male wild‐type C57BL/6 mice (aged 3 months) was applied in some mice, as described previously, in which neutrophils in blood were depleted by vinblastine (2.5 mg/kg IP) . Platelets in blood were depleted by anti–mouse thrombocyte serum (50 μL IP) .…”

“…More recently, we noted that miR‐223 could be secreted into the circulating blood by bone marrow–derived blood cells such as platelets and leukocytes. The blood cell–secreted miR‐223 could then enter into vascular smooth muscle cells (VSMCs) as a novel endocrine genetic signal to regulate their functions and atherogenesis via its target genes . The sources of miR‐223 in vascular ECs and its biological functions are still unclear.…”

Unlocking the Many Secrets of Noncoding RNA∗

“…We now know that hepatocytes also produce miR-223 (10); its production, however, had not been demonstrated binds to insulin-like growth factor 1 receptors, leading to inhibition of the PI3K-Akt pathway (known to be associated with the cell cycle, quiescence, and proliferation); and 6) miR-223 inhibition in vivo leads to increased atherogenesis and increased neointimal formation after arterial injury (8).…”