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Sensitivity of mice to lipopolysaccharide is increased by a high saturated fat and cholesterol diet.

Huang H, Liu T, Rose JL, Stevens RL, Hoyt DG - J Inflamm (Lond) (2007)

Bottom Line: Despite the hepatic effects of HCD, diet had no effect on the LPS plasma concentration-time profile.HCD alone did not affect circulating levels of plasma apolipoprotein A1 or LPS binding protein.Although increased serum amyloid A and CD14 in the circulation may inhibit LPS actions, their overexpression, along with hepatic toll-like receptor-4 or other factors, may contribute to the heightened sensitivity to LPS.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Pharmacology, The Ohio State University College of Pharmacy, Columbus, OH, 43210, USA. hoyt.27@osu.edu.

ABSTRACT

Background: It was hypothesized that a pro-atherogenic, high saturated fat and cholesterol diet (HCD) would increase the inflammatory response to E. coli endotoxin (LPS) and increase its concentration in plasma after administration to mice.

Methods: C57Bl/6 mice were fed a HCD or a control diet (CD) for 4 weeks, and then treated with saline, 0.5, 1 or 2 mg LPS/kg, ip. Liver injury (alanine:2-oxoglutarate aminotransferase and aspartate aminotransferase, collagen staining), circulating cytokines (tumor necrosis factor-alpha, interleukin-6 and interferon-gamma), factors that can bind LPS (serum amyloid A, apolipoprotein A1, LPS binding protein, and CD14), and plasma levels of LPS were measured. The hepatic response was assessed by measuring vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase (iNOS) and signal transducer and activator of transcription-1 proteins, and VCAM-1 and iNOS mRNAs. Hepatic mRNA encoding the LPS receptor, Toll like receptor 4, was also determined.

Results: Two mg LPS/kg killed 100% of mice fed HCD within 5 d, while no mice fed CD died. All mice treated with 0 to 1 mg LPS/kg survived 24 h. HCD increased plasma alanine:2-oxoglutarate aminotransferase and aspartate aminotransferase, and the enzymes were increased more by LPS in HCD than CD mice. Induction of plasma tumor necrosis factor-alpha, interleukin-6, and interferon-gamma by LPS was greater with HCD than CD. Hepatic VCAM-1 and iNOS protein and mRNA were induced by LPS more in mice fed HCD than CD. Tyrosine phosphorylation of signal transducer and activator of transcription-1 caused by LPS was prolonged in HCD compared with CD mice. Despite the hepatic effects of HCD, diet had no effect on the LPS plasma concentration-time profile. HCD alone did not affect circulating levels of plasma apolipoprotein A1 or LPS binding protein. However, plasma concentrations of serum amyloid A and CD14, and hepatic toll-like receptor-4 mRNA were increased in mice fed HCD.

Conclusion: HCD increased the sensitivity of mice to LPS without affecting its plasma level. Although increased serum amyloid A and CD14 in the circulation may inhibit LPS actions, their overexpression, along with hepatic toll-like receptor-4 or other factors, may contribute to the heightened sensitivity to LPS.

No MeSH data available.


Related in: MedlinePlus

The effect of diet and LPS on hepatic TLR4 mRNA. Representative images of ethidium-stained agarose electrophoresis gels of RT-PCR products of RNA extracted from livers of mice fed CD or HCD for 4 weeks (A). MW is a Lambda HindIII molecular weight marker. Signal intensities were measured as in figure 4A and normalized to the RT-PCR signal for β-actin in each sample (B). Bars depict mean normalized signal ratios + SE for 5 mice fed each diet, relative to the CD group, represented by 1 on the y-axis. *: p < 0.05 for comparison with CD.
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Figure 9: The effect of diet and LPS on hepatic TLR4 mRNA. Representative images of ethidium-stained agarose electrophoresis gels of RT-PCR products of RNA extracted from livers of mice fed CD or HCD for 4 weeks (A). MW is a Lambda HindIII molecular weight marker. Signal intensities were measured as in figure 4A and normalized to the RT-PCR signal for β-actin in each sample (B). Bars depict mean normalized signal ratios + SE for 5 mice fed each diet, relative to the CD group, represented by 1 on the y-axis. *: p < 0.05 for comparison with CD.

Mentions: The effect of diet on proteins known to bind LPS was investigated. Plasma SAA was increased 84-fold in HCD compared with CD mice (mean ± SE was 1.5 ± 0.9 μg/ml in mice fed the CD, and 126.7 ± 23.9 μg/ml in mice fed HCD, p < 0.0001). Twelve h after treatment with 0.5 mg LPS/kg, SAA was 3912 ± 821 μg/ml in CD and 5424 ± 628 μg/ml in HCD mice. Plasma CD14 w as increased 4.1-fold in HCD compared with CD mice (figure 8A). Plasma LBP and ApoA1, however, were unaffected by diet (Figure 8B, C). Finally, reverse transcription-polymerase chain reaction (RT-PCR) products of TLR4 mRNA were increased in livers of mice fed HCD in comparison with CD mice (Figure 9). Although it would be desirable to assess hepatic TLR4 in mouse liver, several commercially available antibodies identified multiple bands of varying size on western blots of murine samples (not shown).


Sensitivity of mice to lipopolysaccharide is increased by a high saturated fat and cholesterol diet.

Huang H, Liu T, Rose JL, Stevens RL, Hoyt DG - J Inflamm (Lond) (2007)

The effect of diet and LPS on hepatic TLR4 mRNA. Representative images of ethidium-stained agarose electrophoresis gels of RT-PCR products of RNA extracted from livers of mice fed CD or HCD for 4 weeks (A). MW is a Lambda HindIII molecular weight marker. Signal intensities were measured as in figure 4A and normalized to the RT-PCR signal for β-actin in each sample (B). Bars depict mean normalized signal ratios + SE for 5 mice fed each diet, relative to the CD group, represented by 1 on the y-axis. *: p < 0.05 for comparison with CD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2186306&req=5

Figure 9: The effect of diet and LPS on hepatic TLR4 mRNA. Representative images of ethidium-stained agarose electrophoresis gels of RT-PCR products of RNA extracted from livers of mice fed CD or HCD for 4 weeks (A). MW is a Lambda HindIII molecular weight marker. Signal intensities were measured as in figure 4A and normalized to the RT-PCR signal for β-actin in each sample (B). Bars depict mean normalized signal ratios + SE for 5 mice fed each diet, relative to the CD group, represented by 1 on the y-axis. *: p < 0.05 for comparison with CD.
Mentions: The effect of diet on proteins known to bind LPS was investigated. Plasma SAA was increased 84-fold in HCD compared with CD mice (mean ± SE was 1.5 ± 0.9 μg/ml in mice fed the CD, and 126.7 ± 23.9 μg/ml in mice fed HCD, p < 0.0001). Twelve h after treatment with 0.5 mg LPS/kg, SAA was 3912 ± 821 μg/ml in CD and 5424 ± 628 μg/ml in HCD mice. Plasma CD14 w as increased 4.1-fold in HCD compared with CD mice (figure 8A). Plasma LBP and ApoA1, however, were unaffected by diet (Figure 8B, C). Finally, reverse transcription-polymerase chain reaction (RT-PCR) products of TLR4 mRNA were increased in livers of mice fed HCD in comparison with CD mice (Figure 9). Although it would be desirable to assess hepatic TLR4 in mouse liver, several commercially available antibodies identified multiple bands of varying size on western blots of murine samples (not shown).

Bottom Line: Despite the hepatic effects of HCD, diet had no effect on the LPS plasma concentration-time profile.HCD alone did not affect circulating levels of plasma apolipoprotein A1 or LPS binding protein.Although increased serum amyloid A and CD14 in the circulation may inhibit LPS actions, their overexpression, along with hepatic toll-like receptor-4 or other factors, may contribute to the heightened sensitivity to LPS.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Pharmacology, The Ohio State University College of Pharmacy, Columbus, OH, 43210, USA. hoyt.27@osu.edu.

ABSTRACT

Background: It was hypothesized that a pro-atherogenic, high saturated fat and cholesterol diet (HCD) would increase the inflammatory response to E. coli endotoxin (LPS) and increase its concentration in plasma after administration to mice.

Methods: C57Bl/6 mice were fed a HCD or a control diet (CD) for 4 weeks, and then treated with saline, 0.5, 1 or 2 mg LPS/kg, ip. Liver injury (alanine:2-oxoglutarate aminotransferase and aspartate aminotransferase, collagen staining), circulating cytokines (tumor necrosis factor-alpha, interleukin-6 and interferon-gamma), factors that can bind LPS (serum amyloid A, apolipoprotein A1, LPS binding protein, and CD14), and plasma levels of LPS were measured. The hepatic response was assessed by measuring vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase (iNOS) and signal transducer and activator of transcription-1 proteins, and VCAM-1 and iNOS mRNAs. Hepatic mRNA encoding the LPS receptor, Toll like receptor 4, was also determined.

Results: Two mg LPS/kg killed 100% of mice fed HCD within 5 d, while no mice fed CD died. All mice treated with 0 to 1 mg LPS/kg survived 24 h. HCD increased plasma alanine:2-oxoglutarate aminotransferase and aspartate aminotransferase, and the enzymes were increased more by LPS in HCD than CD mice. Induction of plasma tumor necrosis factor-alpha, interleukin-6, and interferon-gamma by LPS was greater with HCD than CD. Hepatic VCAM-1 and iNOS protein and mRNA were induced by LPS more in mice fed HCD than CD. Tyrosine phosphorylation of signal transducer and activator of transcription-1 caused by LPS was prolonged in HCD compared with CD mice. Despite the hepatic effects of HCD, diet had no effect on the LPS plasma concentration-time profile. HCD alone did not affect circulating levels of plasma apolipoprotein A1 or LPS binding protein. However, plasma concentrations of serum amyloid A and CD14, and hepatic toll-like receptor-4 mRNA were increased in mice fed HCD.

Conclusion: HCD increased the sensitivity of mice to LPS without affecting its plasma level. Although increased serum amyloid A and CD14 in the circulation may inhibit LPS actions, their overexpression, along with hepatic toll-like receptor-4 or other factors, may contribute to the heightened sensitivity to LPS.

No MeSH data available.


Related in: MedlinePlus