Fig. 2

Cellular uptake of DS-Ce6 and induction of apoptotic cell death and autophagy flux by photoactivation. a Immunofluorescence staining of SR-A on macrophages, LPS-activated macrophages, and foam cells. The activated macrophages and foam cells were strongly positive for SR-A (green) compared to the control cells. Blue: nucleus stained with DAPI. Scale bar = 50 μm. b Western blot analysis of the protein expression of SR-A in control macrophages, activated macrophages, and foam cells. Quantification of SR-A normalized to cofilin, presented as fold change over controls. c Dose-dependent cellular uptake of DS-Ce6 in the foam cells. Scale bar = 30 μm. ^*P < 0.05, ^***P < 0.001. d Comparison of the intracellular uptake of free Ce6 (5 μM) and DS-Ce6 (equiv. 5 μM Ce6) in foam cells. To evaluate receptor-mediated endocytosis, the SR-A ligand DS was pre-treated for 1 h before DS-Ce6 incubation (DS + DS-Ce6). Scale bar = 50 μm. e, f Cell viability of the foam cells treated with different concentrations of DS-Ce6, DS, and Ce6 without e and with laser irradiation f (670 nm, 50 mW). ^***P < 0.001. g In vitro phototoxicity of DS-Ce6 in endothelial cells (ECs), smooth muscle cells (SMCs), and macrophages treated with LPS or LPS with LDL under laser irradiation. h Annexin V (green) and DAPI (blue)-stained images of foam cells treated with DS-Ce6 (equiv. 5 μM Ce6) after laser irradiation (670 nm, 50 mW). Scale bar = 50 μm. i Immunofluorescence staining of LC3 (green), p62 (red), and DAPI (blue) in foam cells treated with DS-Ce6 (equiv. 5 μM Ce6) after laser irradiation (670 nm, 50 mW). Scale bar = 25 μm. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001