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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

Measurement of concentration-dependent ACAT1 and ABCG1 expression in Pg-LPS-treated macrophages. 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 – ACAT1 and ABCG1 mRNA levels are presented as fold changes relative to the untreated control (0 µg/ml). B – Western blot analysis of ACAT1 and ABCG1 protein expression. The protein levels were normalized against b-actin as an internal control. Data are presented as means ± SDs. *P < 0.05
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Figure 0005: Measurement of concentration-dependent ACAT1 and ABCG1 expression in Pg-LPS-treated macrophages. 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 – ACAT1 and ABCG1 mRNA levels are presented as fold changes relative to the untreated control (0 µg/ml). B – Western blot analysis of ACAT1 and ABCG1 protein expression. The protein levels were normalized against b-actin as an internal control. Data are presented as means ± SDs. *P < 0.05

Mentions: In order to determine the effects of Pg-LPS on the esterification of FC into CE and the efflux of FC [7] from macrophages co-cultured with LDL, the expression levels of ACAT1 and ABCG1 were analyzed. As shown in Figure 5 A, 10 µg/ml Pg-LPS upregulated ACAT1 mRNA expression to 2.3-fold that of the control, and this effect was concentration dependent. However, ABCG1 expression decreased to only 43% of that of the control when used at the highest concentration (10 µg/ml). Similar patterns of protein expression were observed by western blotting. At 0.1 µg/ml Pg-LPS, no changes in either ABCG1 or ACAT1 levels were observed (p > 0.05). However, the highest concentration of Pg-LPS resulted in approximately 2-fold upregulation in ACAT1 expression and 50% downregulation of ABCG1 expression (Figure 5 B).


Effects of Porphyromonas gingivalis lipopolysaccharide on the expression of key genes involved in cholesterol metabolism in macrophages
Measurement of concentration-dependent ACAT1 and ABCG1 expression in Pg-LPS-treated macrophages. 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 – ACAT1 and ABCG1 mRNA levels are presented as fold changes relative to the untreated control (0 µg/ml). B – Western blot analysis of ACAT1 and ABCG1 protein expression. The protein levels were normalized against b-actin as an internal control. Data are presented as means ± SDs. *P < 0.05
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 0005: Measurement of concentration-dependent ACAT1 and ABCG1 expression in Pg-LPS-treated macrophages. 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 – ACAT1 and ABCG1 mRNA levels are presented as fold changes relative to the untreated control (0 µg/ml). B – Western blot analysis of ACAT1 and ABCG1 protein expression. The protein levels were normalized against b-actin as an internal control. Data are presented as means ± SDs. *P < 0.05
Mentions: In order to determine the effects of Pg-LPS on the esterification of FC into CE and the efflux of FC [7] from macrophages co-cultured with LDL, the expression levels of ACAT1 and ABCG1 were analyzed. As shown in Figure 5 A, 10 µg/ml Pg-LPS upregulated ACAT1 mRNA expression to 2.3-fold that of the control, and this effect was concentration dependent. However, ABCG1 expression decreased to only 43% of that of the control when used at the highest concentration (10 µg/ml). Similar patterns of protein expression were observed by western blotting. At 0.1 µg/ml Pg-LPS, no changes in either ABCG1 or ACAT1 levels were observed (p > 0.05). However, the highest concentration of Pg-LPS resulted in approximately 2-fold upregulation in ACAT1 expression and 50% downregulation of ABCG1 expression (Figure 5 B).

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