Fig. 1.

Lipids from SMase-LDL rapidly accumulate in human macrophages and colocalise with lysosomes.

THP-1 macrophage-like cells and HMDM cells were incubated with SMase-LDL (200 μg protein/ml) for 4 or 24 h, respectively. The uptake of aggregated LDL by cells was detected by Oil Red O staining and transmitted-light microscopy. THP-1 macrophages were incubated (A) alone, (B) with native LDL or (C) SMase-LDL. Scale bar: 30 μm. (D) Intracellular lipids in THP-1 macrophage-like cells, measured as intensity of red pixels, were quantified using ImageJ. Mean ± SEM of 3 independent experiments. p < 0.001 ANOVA; followed by Tukey's post-hoc test, *p < 0.01 compared to others. Lysosomes in HMDM were labelled with anti-LAMP2 antibody (E) whilst intracellular lipids were stained with LipidTOX™ Red (F). Their colocalisation appeared yellow in an overlaid confocal image (G). Scale bar: 30 μm.