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Decreased paraoxonase-1 activity is associated with alterations of high-density lipoprotein particles in chronic liver impairment.

Marsillach J, Aragonès G, Mackness B, Mackness M, Rull A, Beltrán-Debón R, Pedro-Botet J, Alonso-Villaverde C, Joven J, Camps J - Lipids Health Dis (2010)

Bottom Line: These changes were associated with an increased plasma concentration of markers of oxidative stress, inflammation and fibrogenesis.Abnormalities in the composition of lipids and proteins of HDL particles, including PON1 glycosylation, are associated with the decrease in serum PON1 activity in patients with liver disease.These alterations may adversely affect the protective role of HDL against oxidative stress and inflammation in these patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recerca Biomèdica, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, C, Sant Joan s/n, 43201 Reus, Catalunya, Spain.

ABSTRACT

Background: Paraoxonase-1 (PON1), a lactonase synthesized by the liver, circulates in blood bound to high-density lipoproteins (HDL). This enzyme is thought to degrade oxidized phospholipids and play an important role in the organism's antioxidant and anti-inflammatory system. Chronic liver diseases are characterized by decreased serum PON1 activity. The aim of the present study was to investigate the compositional changes in HDL that could influence PON1 activity in liver impairment.

Methods: The study was performed in samples from five patients with advanced liver cirrhosis and with preserved renal function, chosen on the basis of having low serum PON1 activity and high serum PON1 concentration. As a control group, we accessed five healthy volunteers from among our hospital staff. Lipid and protein compositional analysis of lipoprotein particles were done by high-performance liquid chromatography, gel electrophoresis, and Western-Blot.

Results: HDL particles from cirrhotic patients had an increased phospholipid content that was inversely correlated to PON1 activity. The HDL particles contained high levels of PON1 that corresponded, in part, to an immunoreactive protein of high molecular weight (55 kDa) not present in control subjects. This protein was identified as glycosylated PON1 and was also present in biopsies from patients with steatosis and from rats with CCl(4)-induced hepatic impairment. These changes were associated with an increased plasma concentration of markers of oxidative stress, inflammation and fibrogenesis.

Conclusion: Abnormalities in the composition of lipids and proteins of HDL particles, including PON1 glycosylation, are associated with the decrease in serum PON1 activity in patients with liver disease. These alterations may adversely affect the protective role of HDL against oxidative stress and inflammation in these patients.

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(A) Western blot analysis of HDL particles in control subjects and patients with liver cirrhosis. HDL from the patients had an immunoreactive band (very light in the case #3) of about 55 kDa. (B) Western blot analysis of liver homogenates from control rats, CCl4-administered rats over a period of 6, 8 and 12 weeks, and liver biopsy samples from human patients with liver steatosis. A band at the relative molecular weight of 55 kDa increased progressively over the time-course of CCl4 administration. A similar, very intense band was observed in patients with steatosis. (C) Western blot analysis of HDL particles from a control subject (CS), a patient with cirrhosis (P), and normal HDL incubated in vitro with a liver homogenate from a patient with steatosis. (D) Western blot analysis of HDL particles from a patient with liver cirrhosis, with and without pre-incubated with PNGase F.
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Figure 4: (A) Western blot analysis of HDL particles in control subjects and patients with liver cirrhosis. HDL from the patients had an immunoreactive band (very light in the case #3) of about 55 kDa. (B) Western blot analysis of liver homogenates from control rats, CCl4-administered rats over a period of 6, 8 and 12 weeks, and liver biopsy samples from human patients with liver steatosis. A band at the relative molecular weight of 55 kDa increased progressively over the time-course of CCl4 administration. A similar, very intense band was observed in patients with steatosis. (C) Western blot analysis of HDL particles from a control subject (CS), a patient with cirrhosis (P), and normal HDL incubated in vitro with a liver homogenate from a patient with steatosis. (D) Western blot analysis of HDL particles from a patient with liver cirrhosis, with and without pre-incubated with PNGase F.

Mentions: The HDL particles from cirrhotic patients contained high levels of a protein which reacted against anti-PON1 antibody and had an estimated weight of 55 kDa. This protein was not present in the control subjects (Fig. 4A). To further characterize this protein, we performed Western blot analysis of the liver homogenates of biopsies obtained from patients with hepatic steatosis, as well as from rats with CCl4-induced hepatic impairment. We observed that the livers from both sources, the patients and the CCl4-administered animals, had a similar immunoreactive band (Fig. 4B). However, when a liver homogenate from a patient with steatosis was incubated in vitro with normal human HDL and then subjected to Western blot analysis, we did not observe any abnormal immunoreactive band (Fig. 4C). Further, this protein band disappeared when HDL was incubated with PNGase F; suggesting that it consisted of glycosylated PON1 (Fig. 4D).


Decreased paraoxonase-1 activity is associated with alterations of high-density lipoprotein particles in chronic liver impairment.

Marsillach J, Aragonès G, Mackness B, Mackness M, Rull A, Beltrán-Debón R, Pedro-Botet J, Alonso-Villaverde C, Joven J, Camps J - Lipids Health Dis (2010)

(A) Western blot analysis of HDL particles in control subjects and patients with liver cirrhosis. HDL from the patients had an immunoreactive band (very light in the case #3) of about 55 kDa. (B) Western blot analysis of liver homogenates from control rats, CCl4-administered rats over a period of 6, 8 and 12 weeks, and liver biopsy samples from human patients with liver steatosis. A band at the relative molecular weight of 55 kDa increased progressively over the time-course of CCl4 administration. A similar, very intense band was observed in patients with steatosis. (C) Western blot analysis of HDL particles from a control subject (CS), a patient with cirrhosis (P), and normal HDL incubated in vitro with a liver homogenate from a patient with steatosis. (D) Western blot analysis of HDL particles from a patient with liver cirrhosis, with and without pre-incubated with PNGase F.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2877049&req=5

Figure 4: (A) Western blot analysis of HDL particles in control subjects and patients with liver cirrhosis. HDL from the patients had an immunoreactive band (very light in the case #3) of about 55 kDa. (B) Western blot analysis of liver homogenates from control rats, CCl4-administered rats over a period of 6, 8 and 12 weeks, and liver biopsy samples from human patients with liver steatosis. A band at the relative molecular weight of 55 kDa increased progressively over the time-course of CCl4 administration. A similar, very intense band was observed in patients with steatosis. (C) Western blot analysis of HDL particles from a control subject (CS), a patient with cirrhosis (P), and normal HDL incubated in vitro with a liver homogenate from a patient with steatosis. (D) Western blot analysis of HDL particles from a patient with liver cirrhosis, with and without pre-incubated with PNGase F.
Mentions: The HDL particles from cirrhotic patients contained high levels of a protein which reacted against anti-PON1 antibody and had an estimated weight of 55 kDa. This protein was not present in the control subjects (Fig. 4A). To further characterize this protein, we performed Western blot analysis of the liver homogenates of biopsies obtained from patients with hepatic steatosis, as well as from rats with CCl4-induced hepatic impairment. We observed that the livers from both sources, the patients and the CCl4-administered animals, had a similar immunoreactive band (Fig. 4B). However, when a liver homogenate from a patient with steatosis was incubated in vitro with normal human HDL and then subjected to Western blot analysis, we did not observe any abnormal immunoreactive band (Fig. 4C). Further, this protein band disappeared when HDL was incubated with PNGase F; suggesting that it consisted of glycosylated PON1 (Fig. 4D).

Bottom Line: These changes were associated with an increased plasma concentration of markers of oxidative stress, inflammation and fibrogenesis.Abnormalities in the composition of lipids and proteins of HDL particles, including PON1 glycosylation, are associated with the decrease in serum PON1 activity in patients with liver disease.These alterations may adversely affect the protective role of HDL against oxidative stress and inflammation in these patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recerca Biomèdica, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, C, Sant Joan s/n, 43201 Reus, Catalunya, Spain.

ABSTRACT

Background: Paraoxonase-1 (PON1), a lactonase synthesized by the liver, circulates in blood bound to high-density lipoproteins (HDL). This enzyme is thought to degrade oxidized phospholipids and play an important role in the organism's antioxidant and anti-inflammatory system. Chronic liver diseases are characterized by decreased serum PON1 activity. The aim of the present study was to investigate the compositional changes in HDL that could influence PON1 activity in liver impairment.

Methods: The study was performed in samples from five patients with advanced liver cirrhosis and with preserved renal function, chosen on the basis of having low serum PON1 activity and high serum PON1 concentration. As a control group, we accessed five healthy volunteers from among our hospital staff. Lipid and protein compositional analysis of lipoprotein particles were done by high-performance liquid chromatography, gel electrophoresis, and Western-Blot.

Results: HDL particles from cirrhotic patients had an increased phospholipid content that was inversely correlated to PON1 activity. The HDL particles contained high levels of PON1 that corresponded, in part, to an immunoreactive protein of high molecular weight (55 kDa) not present in control subjects. This protein was identified as glycosylated PON1 and was also present in biopsies from patients with steatosis and from rats with CCl(4)-induced hepatic impairment. These changes were associated with an increased plasma concentration of markers of oxidative stress, inflammation and fibrogenesis.

Conclusion: Abnormalities in the composition of lipids and proteins of HDL particles, including PON1 glycosylation, are associated with the decrease in serum PON1 activity in patients with liver disease. These alterations may adversely affect the protective role of HDL against oxidative stress and inflammation in these patients.

Show MeSH
Related in: MedlinePlus