MicroRNAs are Transported in Plasma and Delivered to Recipient Cells by High-Density Lipoproteins (Human HDL miRNA Signatures)

Circulating microRNAs (miRNA) are relatively stable in plasma and are a new class of disease biomarkers. Here we present evidence that human high-density lipoprotein (HDL) transports endogenous miRNAs and delivers them to recipient cells with functional targeting capabilities. Highly-purified fractions of human HDL contain small RNAs, and the HDL-miRNA profile from normal subjects is significantly different than familial hypercholesterolemia subjects. miRNAs were demonstrated to associate with both native and reconstituted HDL particles, and reconstituted HDL injected into mice retrieved distinct miRNA profiles from normal and atherogenic models. Cellular export of miRNAs to HDL was demonstrated to be regulated by neutral sphingomyelinase. HDL-mediated delivery of miRNAs to recipient cells was demonstrated to be scavenger receptor BI-dependent. Furthermore, HDL delivery of both exogenous and endogenous miRNAs resulted in the direct targeting of mRNA reporters. Notably, HDL-miRNA from atherosclerotic subjects induced differential gene expression, with significant loss of conserved mRNA targets in cultured hepatocytes. Collectively, these observations suggest that HDL participates in a novel mechanism of intercellular communication involving the transport and delivery of miRNAs. Human HDL miRNA Signatures Profiled miRNA Signatures from N=6 Normal Human HDL; n=5 FH Human HDL