IGFBPL1 inhibits macrophage lipid accumulation by enhancing the activation of IGR1R/LXRα/ABCG1 pathway

Figures

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  Figure 1. IGFBPL1 inhibits PA-induced lipid accumulation in macrophages. (A) Different expression gene in control samples and unstable atherosclerosis plaque human. Normal: the abdominal aortas intima of three patients without atherosclerosis. Atherosclerosis: aortic plaques of patients diagnosed with grade V or VI atherosclerosis. (B) Relative IGFBPL1 protein level (n=3). (C) Relative mRNA level of IGFBPL1 in PA or ox-LDL treated THP-1 macrophages (n=3). (D) Relative protein level of IGFBPL1 (n=3). (E) Relative IGFBPL1 mRNA level (n=3). (F) Representative images of oil red O staining. PA: palmitic acid, THP-1 macrophages were incubated with 100 μM PA for 48 h. ox-LDL: oxidized low density lipoprotein, THP-1 macrophages were treated with 100 μg/mL ox-LDL for 72 h. PA + ov-IGFBPL1, THP-1 was transfected with over-expression plasmid of IGFBPL1 for 24 h and then incubated with 100 μM PA for 48 h. P<0.05 represents a significant statistical difference; Scale indicates 25 μm.

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  Figure 2. IGFBPL1 increases macrophage cholesterol efflux through ABCG1. (A) Relative mRNA level of genes relative to cholesterol uptake and efflux (n=3). (B) WB was used to detect the protein level of ABCG1. (C) Quantitative statistics on WB results by ImageJ (n=3). (D) Representative images of NBD cholesterol fluorescence staining of macrophages. (E) Quantitative results of average fluorescence intensity of per THP-1 macrophage cell (n=3). PA: palmitic acid, THP-1 macrophages were incubated with 100 μM PA for 48 h. PA + ov-IGFBPL1, THP-1 was transfected with over-expression plasmid of IGFBPL1 for 24 h and then incubated with 100 μM PA for 48 h. P<0.05 represents a significant statistical difference; Scale indicates 25 μm.

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  Figure 3. LXR meditated the regulation effect of IGFBPL1 on ABCG1 expression and macrophage lipid accumulation. (A) Relative mRNA level of LXR (n=3). (B) WB was used to detect the protein level of LXR. (C) Quantitative statistics on WB results by ImageJ (n=3). (D) CCK-8 was used to detect the cell viability (n=3). (E) Relative mRNA level of IGFBPL1, IGBPL1, LXR and ABCG1 (n=3). (F) Representative images of oil red O staining. (G) WB was used to detect the protein level of IGFBPL1, LXR and ABCG1. (H) Quantitative statistics on WB results by ImageJ (n=3). PA: palmitic acid, SR9238: LXRα antagonist. PA + ov-IGFBPL1 + SR9238, T THP-1 was transfected for 24 h and then incubated with PA (100 μM) and SR9238 (1 μM) for 48 h. P<0.05 represents a significant statistical difference; Scale indicates 25 μm.

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  Figure 4. IGF-1R is critical for the anti-lipid accumulation effect of IGFBPL1 in macrophages. (A) Cell viability of THP-1 macrophages treated with PPP was detected by CCK-8. (B) Relative mRNA level of IGFBPL1, LXR and ABCG1 in THP-1 macrophages. (C) Representative images of oil red O staining. (D) WB was used to detect the protein level of LXR, ABCG1 and IGFBPL1 (n=3). (E) Quantitative statistics on WB results by ImageJ (n=3). PA: palmitic acid, PPP: picropodophyllin. PA + ov-IGFBPL1 + PPP, THP-1 was transfected for 24 h and then incubated with PA (100 μM) and PPP (1 μM) for 48 h. P<0.05 represents a significant statistical difference; Scale indicates 25 μm.

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  Figure 5. Summary model of IGFBPL1 inhibits macrophage lipid accumulation.