A Chinese group has recently published  their interesting findings: in atherosclerosis β-CD (probaly methyl beta-cyclodextrin, but not specified) was found to be a shuttle of cholesterol at low β-CD concentration and a sink of cholesterol at high concentration.
It is reported that a low concentration of β-CD can function as a cholesterol shuttle to promote cholesterol efflux from cells to the extracellular acceptors (cholesterol sink, such as high density lipoprotein, HDL, particles). Simvastatin-loaded discoidal reconstituted high density lipoprotein (ST-d-rHDL) was combined with different concentrations of β-CD. Compared with ST-d-rHDL alone, the cholesterol removal ability of ST-d-rHDL combined with 0.5 mM of β-CD increased by 31-fold after incubation for 6 h and the cumulative drug release of ST-d-rHDL increased by two-fold during the initial 1 h in an acellular mimetic system. In macrophage/foam cells, 0.5 mM of β-CD showed superior promoting effects in the cholesterol removal ability and remodeling of ST-d-rHDL compared to 0.1 mM of β-CD. The high concentration of β-CD at 2 mM, however, displayed a low efficiency for accelerating cholesterol efflux, which might function as a cholesterol sink rather than a cholesterol shuttle. Moreover, the permeability and fluidity of the cell membrane were improved by combining 0.5 mM of β-CD with ST-d-rHDL, which exhibited an enhanced cellular drug uptake and inhibiting effect on the intracellular lipid deposition and secretion of inflammatory cytokine. Collectively, combination of β-CD and ST-d-rHDL as a shuttle/sink model could enhance cholesterol efflux and drug uptake to suppress inflammation in macrophage/foam cells.
 He, J., Yang, Y., Zhou, X., Zhang, W., & Liu, J. (2020). Shuttle/sink model composed of β-cyclodextrin and simvastatin-loaded discoidal reconstituted high-density lipoprotein for enhanced cholesterol efflux and drug uptake in macrophage/foam cells. Journal of Materials Chemistry B. https://doi.org/10.1039/c9tb02101a