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Effects of Porphyromonas gingivalis lipopolysaccharide on the expression of key genes involved in cholesterol metabolism in macrophages

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Cardiovascular diseases are positively correlated with periodontal disease. However, the molecular mechanisms linking atherosclerosis and periodontal infection are not clear. This study aimed to determine whether Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) altered the expression of genes regulating cholesterol metabolism in macrophages in the presence of low-density lipoprotein (LDL).

Material and methods: THP-1-derived macrophages were exposed to different concentrations (0.1, 1, 10 µg/ml) of LPS in the presence of 50 µg/ml native LDL. Macrophages were also incubated with 1 µg/ml LPS for varying times (0, 24, 48, or 72 h) in the presence of native LDL. Foam cell formation was determined by oil red O staining and cholesterol content quantification. CD36, lectin-like oxidized LDL receptor-1 (LOX-1), ATP-binding cassette G1 (ABCG1), and acetyl CoA acyltransferase 1 (ACAT1) expression levels were measured by western blot and qRT-PCR.

Results: Foam cell formation was induced in a time- and concentration-dependent manner as assessed by both morphological and biochemical criteria. Pg-LPS caused downregulation of CD36 and ABCG1 but upregulation of ACAT1, while LOX-1 expression was not affected (p = 0.137).

Conclusions: Pg-LPS appears to be an important link in the development of atherosclerosis by mechanisms targeting cholesterol homeostasis, namely, excess cholesterol ester formation via ACAT1 and reduced cellular cholesterol efflux via ABCG1.

No MeSH data available.


Pg-LPS induced foam cell formation, according to morphological criteria. THP-1-derived macrophages were cultured with or without increasing concentrations of Pg-LPS in the presence of 50 µg/ml LDL for 48 h. A – Untreated macrophages as a control; B – 0.1 µg/ml; C – 1.0 µg/ml; D – 10.0 µg/ml. I – The number of foam cells induced by different concentrations of LPS. Moreover, incubation of macrophages with LDL (50 µg/ml) and Pg-LPS (1.0 µg/ml) was performed for different durations. E – 0 h as a control; F – 24 h; G – 48 h; H – 72 h. J – The number of foam cells induced by LPS for different durations. Black arrows indicate representative Oil Red O stained lipid droplets. Original magnification of microphotographs: 400×; scale bar = 20 µm
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Figure 0001: Pg-LPS induced foam cell formation, according to morphological criteria. THP-1-derived macrophages were cultured with or without increasing concentrations of Pg-LPS in the presence of 50 µg/ml LDL for 48 h. A – Untreated macrophages as a control; B – 0.1 µg/ml; C – 1.0 µg/ml; D – 10.0 µg/ml. I – The number of foam cells induced by different concentrations of LPS. Moreover, incubation of macrophages with LDL (50 µg/ml) and Pg-LPS (1.0 µg/ml) was performed for different durations. E – 0 h as a control; F – 24 h; G – 48 h; H – 72 h. J – The number of foam cells induced by LPS for different durations. Black arrows indicate representative Oil Red O stained lipid droplets. Original magnification of microphotographs: 400×; scale bar = 20 µm

Mentions: After treatment with 0.1 µg/ml Pg-LPS and LDL (Figure 1 B), foam cell formation was minimal, but was obviously higher than that obtained for the control (LDL alone), as demonstrated by Oil Red O staining of lipid droplets (Figure 1 A). However, in cells treated with higher Pg-LPS and LDL concentrations, large lipid droplet masses were observed (Figure 1 C and D). The number of foam cells significantly increased in all the Pg-LPS treated groups (Figure 1 I). These results indicated that LPS exposure caused foam cell formation in a concentration-dependent manner.


Effects of Porphyromonas gingivalis lipopolysaccharide on the expression of key genes involved in cholesterol metabolism in macrophages
Pg-LPS induced foam cell formation, according to morphological criteria. THP-1-derived macrophages were cultured with or without increasing concentrations of Pg-LPS in the presence of 50 µg/ml LDL for 48 h. A – Untreated macrophages as a control; B – 0.1 µg/ml; C – 1.0 µg/ml; D – 10.0 µg/ml. I – The number of foam cells induced by different concentrations of LPS. Moreover, incubation of macrophages with LDL (50 µg/ml) and Pg-LPS (1.0 µg/ml) was performed for different durations. E – 0 h as a control; F – 24 h; G – 48 h; H – 72 h. J – The number of foam cells induced by LPS for different durations. Black arrows indicate representative Oil Red O stained lipid droplets. Original magnification of microphotographs: 400×; scale bar = 20 µm
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016584&req=5

Figure 0001: Pg-LPS induced foam cell formation, according to morphological criteria. THP-1-derived macrophages were cultured with or without increasing concentrations of Pg-LPS in the presence of 50 µg/ml LDL for 48 h. A – Untreated macrophages as a control; B – 0.1 µg/ml; C – 1.0 µg/ml; D – 10.0 µg/ml. I – The number of foam cells induced by different concentrations of LPS. Moreover, incubation of macrophages with LDL (50 µg/ml) and Pg-LPS (1.0 µg/ml) was performed for different durations. E – 0 h as a control; F – 24 h; G – 48 h; H – 72 h. J – The number of foam cells induced by LPS for different durations. Black arrows indicate representative Oil Red O stained lipid droplets. Original magnification of microphotographs: 400×; scale bar = 20 µm
Mentions: After treatment with 0.1 µg/ml Pg-LPS and LDL (Figure 1 B), foam cell formation was minimal, but was obviously higher than that obtained for the control (LDL alone), as demonstrated by Oil Red O staining of lipid droplets (Figure 1 A). However, in cells treated with higher Pg-LPS and LDL concentrations, large lipid droplet masses were observed (Figure 1 C and D). The number of foam cells significantly increased in all the Pg-LPS treated groups (Figure 1 I). These results indicated that LPS exposure caused foam cell formation in a concentration-dependent manner.

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Cardiovascular diseases are positively correlated with periodontal disease. However, the molecular mechanisms linking atherosclerosis and periodontal infection are not clear. This study aimed to determine whether Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) altered the expression of genes regulating cholesterol metabolism in macrophages in the presence of low-density lipoprotein (LDL).

Material and methods: THP-1-derived macrophages were exposed to different concentrations (0.1, 1, 10 µg/ml) of LPS in the presence of 50 µg/ml native LDL. Macrophages were also incubated with 1 µg/ml LPS for varying times (0, 24, 48, or 72 h) in the presence of native LDL. Foam cell formation was determined by oil red O staining and cholesterol content quantification. CD36, lectin-like oxidized LDL receptor-1 (LOX-1), ATP-binding cassette G1 (ABCG1), and acetyl CoA acyltransferase 1 (ACAT1) expression levels were measured by western blot and qRT-PCR.

Results: Foam cell formation was induced in a time- and concentration-dependent manner as assessed by both morphological and biochemical criteria. Pg-LPS caused downregulation of CD36 and ABCG1 but upregulation of ACAT1, while LOX-1 expression was not affected (p = 0.137).

Conclusions: Pg-LPS appears to be an important link in the development of atherosclerosis by mechanisms targeting cholesterol homeostasis, namely, excess cholesterol ester formation via ACAT1 and reduced cellular cholesterol efflux via ABCG1.

No MeSH data available.