© 2017 American Heart Association, Inc. OBJECTIVE: Blood vessel wall damage often results in the formation of a fibrin clot that traps inflammatory cells, including monocytes. The effect of clot formation and subsequent lysis on the expression of monocyte-derived genes involved in the development and progression of ischemic stroke and other vascular diseases, however, is unknown. Determine whether clot formation and lysis regulates the expression of human monocyte-derived genes that modulate vascular diseases. APPROACH AND RESULTS: We performed next-generation RNA sequencing on monocytes extracted from whole blood clots and using a purified plasma clot system. Numerous mRNAs were differentially expressed by monocytes embedded in clots compared with unclotted controls, and IL-8 (interleukin 8) and MCP-1 (monocyte chemoattractant protein-1) were among the upregulated transcripts in both models. Clotted plasma also increased expression of IL-8 and MCP-1, which far exceeded responses observed in lipopolysaccharide-stimulated monocytes. Upregulation of IL-8 and MCP-1 occurred in a thrombin-independent but fibrin-dependent manner. Fibrinolysis initiated shortly after plasma clot formation (ie, 1-2 hours) reduced the synthesis of IL-8 and MCP-1, whereas delayed fibrinolysis was far less effective. Consistent with these in vitro models, monocytes embedded in unresolved thrombi from patients undergoing thrombectomy stained positively for IL-8 and MCP-1. CONCLUSIONS: These findings demonstrate that clots are potent inducers of monocyte gene expression and that timely fibrinolysis attenuates inflammatory responses, specifically IL-8 and MCP-1. Dampening of inflammatory gene expression by timely clot lysis may contribute to the clinically proven efficacy of fibrinolytic drug treatment within hours of stroke onset.
CITATION STYLE
Campbell, R. A., Vieira-de-Abreu, A., Rowley, J. W., Franks, Z. G., Manne, B. K., Rondina, M. T., … Weyrich, A. S. (2017). Clots Are Potent Triggers of Inflammatory Cell Gene Expression. Arteriosclerosis, Thrombosis, and Vascular Biology, 37(10), 1819–1827. https://doi.org/10.1161/atvbaha.117.309794
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