The hallmark features of
atherosclerosis include accumulation of
low-density lipoprotein (
LDL) carrying
cholesterol in the vessel wall, formation of
lipid-laden foam cells, and the creation of a pro-inflammatory microenvironment. To date, no effective treatments are clinically available for increasing
cholesterol efflux from vascular macrophages and inducing reverse
cholesterol transport (RCT). In an article published recently in Clinical Science (vol 132, issue 6, 1199-1213), Zhang and colleagues identified the
extracellular matrix protein mindin/spondin 2 as a positive regulator of
atherosclerosis. Genetic knockout of
mindin in
apolipoprotein-E (
apoE)-/- mice attenuated
atherosclerosis, foam cell formation, and
inflammation within the vessel wall. Conversely, selective overexpression of
mindin in macrophages in
apoE-/- mice was sufficient to promote the greater severity of
atherosclerosis. Interestingly, foam cell formation was closely associated with the expression of
cholesterol transporters (ABCA1 and ACBG1) that facilitate
cholesterol efflux.
Liver X receptor (LXR)-β is a key modulator of
cholesterol transporter expression and formed direct interactions with
mindin. Furthermore, the protective effects of
mindin deficiency on foam cell formation were blocked by inhibition of LXR-β. This article highlights a novel role of
mindin in modulating foam cell formation and
atherosclerosis development in mice through direct regulation of LXR-β. Thus far, direct targetting of LXR-β via pharmacological agonists has proven to be problematic due to the lack of subtype selective inhibitors and associated adverse effects. Indirect targetting of LXR-β, therefore, via
mindin inhibition offers a new therapeutic strategy for increasing LXR-β induced
cholesterol efflux, reducing foam cell formation, and preventing or treating
atherosclerosis.