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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.


Related in: MedlinePlus

Pg-LPS induced foam cell formation, according to biochemical criteria. Macrophages were exposed to increasing concentrations (0, 0.1, 1, 10 µg/ml) of Pg-LPS for 48 h in the presence of 50 µg/ml LDL (A and B). To measure time-dependent effects, cells were incubated with Pg-LPS (1.0 µg/ml) in the presence of LDL (50 µg/ml) for 0, 24, 48, or 72 h (C and D). A and C – The content of intracellular total cholesterol (TC) and cholesterol ester (CE) was normalized to protein levels and expressed as µg/mg. B and D – The ratios of CE to TC. Data are presented as means ± SDs; *P < 0.05
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Figure 0002: Pg-LPS induced foam cell formation, according to biochemical criteria. Macrophages were exposed to increasing concentrations (0, 0.1, 1, 10 µg/ml) of Pg-LPS for 48 h in the presence of 50 µg/ml LDL (A and B). To measure time-dependent effects, cells were incubated with Pg-LPS (1.0 µg/ml) in the presence of LDL (50 µg/ml) for 0, 24, 48, or 72 h (C and D). A and C – The content of intracellular total cholesterol (TC) and cholesterol ester (CE) was normalized to protein levels and expressed as µg/mg. B and D – The ratios of CE to TC. Data are presented as means ± SDs; *P < 0.05

Mentions: Given that excessive CE accounted for the elevated amount of lipid droplets, the cellular CE content was measured to investigate foam cell formation according to biochemical criteria. Incubation of LDL-treated macrophages with Pg-LPS caused a concentration-dependent increase in CE and TC accumulation (Figure 2 A). Moreover, treatment with 1 or 10 µg/ml LPS significantly induced foam cell formation (Figure 2 B), as assessed when using CE/TC > 50% for identification of foam cells [18]. As shown in Figure 2 C, Pg-LPS exposure induced a time-dependent increase in CE and TC content, and the CE/TC ratio was greater than 50% after 24 h of LPS exposure (Figure 2 D), which indicated foam cell formation according to biochemical criteria.


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 biochemical criteria. Macrophages were exposed to increasing concentrations (0, 0.1, 1, 10 µg/ml) of Pg-LPS for 48 h in the presence of 50 µg/ml LDL (A and B). To measure time-dependent effects, cells were incubated with Pg-LPS (1.0 µg/ml) in the presence of LDL (50 µg/ml) for 0, 24, 48, or 72 h (C and D). A and C – The content of intracellular total cholesterol (TC) and cholesterol ester (CE) was normalized to protein levels and expressed as µg/mg. B and D – The ratios of CE to TC. Data are presented as means ± SDs; *P < 0.05
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 0002: Pg-LPS induced foam cell formation, according to biochemical criteria. Macrophages were exposed to increasing concentrations (0, 0.1, 1, 10 µg/ml) of Pg-LPS for 48 h in the presence of 50 µg/ml LDL (A and B). To measure time-dependent effects, cells were incubated with Pg-LPS (1.0 µg/ml) in the presence of LDL (50 µg/ml) for 0, 24, 48, or 72 h (C and D). A and C – The content of intracellular total cholesterol (TC) and cholesterol ester (CE) was normalized to protein levels and expressed as µg/mg. B and D – The ratios of CE to TC. Data are presented as means ± SDs; *P < 0.05
Mentions: Given that excessive CE accounted for the elevated amount of lipid droplets, the cellular CE content was measured to investigate foam cell formation according to biochemical criteria. Incubation of LDL-treated macrophages with Pg-LPS caused a concentration-dependent increase in CE and TC accumulation (Figure 2 A). Moreover, treatment with 1 or 10 µg/ml LPS significantly induced foam cell formation (Figure 2 B), as assessed when using CE/TC > 50% for identification of foam cells [18]. As shown in Figure 2 C, Pg-LPS exposure induced a time-dependent increase in CE and TC content, and the CE/TC ratio was greater than 50% after 24 h of LPS exposure (Figure 2 D), which indicated foam cell formation according to biochemical criteria.

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 &micro;g/ml) of LPS in the presence of 50 &micro;g/ml native LDL. Macrophages were also incubated with 1 &micro;g/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.


Related in: MedlinePlus