Interrelationships between paraoxonase-1 and monocyte chemoattractant protein-1 in the regulation of hepatic inflammation. Adv Exp Med Biol. 2010;660:5-18. [PMID: 20221866 DOI: 10.1007/978-1-60761-350-3_2]

Alteration of the intestinal microbiota and serum metabolites in a mouse model of Pon1 gene ablation

Mutations in the Paraoxonase 1 (Pon1) gene underlie aging, cardiovascular disease, and impairments of the nervous and gastrointestinal systems and are linked to the intestinal microbiome. The potential role of Pon1 in modulating the intestinal microbiota and serum metabolites is poorly understood. The present study demonstrated that mice with genomic excision of Pon1 by a multiplexed guide RNA CRISPR/Cas9 approach exhibited disrupted gut microbiota, such as significantly depressed alpha-diversity and distinctly separated beta diversity, accompanied by varied profiles of circulating metabolites. Furthermore, genomic knock in of Pon1 exerted a distinct effect on the intestinal microbiome and serum metabolome, including dramatically enriched Aerococcus, linoleic acid and depleted Bacillus, indolelactic acid. Specifically, a strong correlation was established between bacterial alterations and metabolites in Pon1 knockout mice. In addition, we identified metabolites related to gut bacteria in response to Pon1 knock in. Thus, the deletion of Pon1 affects the gut microbiome and functionally modifies serum metabolism, which can lead to dysbiosis, metabolic dysfunction, and infection risk. Together, these findings put forth a role for Pon1 in microbial alterations that contribute to metabolism variations. The function of Pon1 in diseases might at least partially depend on the microbiome.

Serum Activities of Paraoxonase 1 (PON1) in Predicting Liver Damage Among Patients Diagnosed With Hepatocellular Carcinoma: A Case-Control Study

Introduction Hepatocellular carcinoma (HCC) is one of the most common cancers in the world and unless diagnosed timely has limited options for treatment. Paraoxonase (PON) is a glycosylated protein that has been implicated in antioxidant and other biochemical functions. Paraoxonase 1 (PON1) is an esterase associated with high-density lipoprotein (HDL) particles. The present study was carried out to assess the PON1 activity and compare it with the standard liver function tests (LFTs) in assessing the predictability of liver damage among patients diagnosed with HCC. Methods This case-control study was carried out in the Department of Biochemistry attached to Great Eastern Medical School and Hospital, Srikakulam, Andhra Pradesh. Serum PON1 activities and LFTs like total bilirubin, direct bilirubin, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total protein, and albumin were estimated in 30 patients diagnosed with HCC and 30 healthy persons. All the parameters were estimated using standard biochemical methods. The data was analyzed using GraphPad Prism version 6.0 (GraphPad Software, Inc). A probability (p) value <0.05 was considered to be statistically significant. Receiver operating characteristic curve (ROC) analysis was performed to assess the area under the curve (AUC) for accuracy, sensitivity, specificity, and diagnostic efficiency. Results The serum activities of PON1 had identical sensitivity (70%) to albumin (70%) and were superior to other tested parameters. Additionally, PON1 activities showed lower specificity (86.67%) than the other tested parameters. ROC analysis showed increased diagnostic efficacy (DE) of PON1 (DE=78.3%; p<0.0001) when compared with total bilirubin (DE=76.6%; p=0.0039), direct bilirubin (DE=74.9%; p=0.04), ALT (DE=73.30%; p=0.0006), and total protein (DE=71.6%; p=0.0005). However, the DE of PON1 was comparable with AST (DE=81.60%; p<0.0001), ALP (DE=79.9%; p<0.0001), and albumin (DE=83.30%, p<0.0001). Conclusions Serum activities of PON1 could be used as a diagnostic marker for assessing liver damage among HCC patients.

Association between axial length and HDL in children: a hospital-based cross-sectional study

BACKGROUND

To analyze the relationship between axial length and levels of high-density lipoprotein (HDL) cholesterol in children.

METHODS

A retrospective, hospital-based cross-sectional research with 69 right eyes from 69 children who underwent health examination by Zhejiang Provincial People's Hospital was carried out. The participants were split into three groups: Group A (axial length < = 23 mm), Group B (axial length 23-24 mm), and Group C (axial length > 24 mm). Demographic epidemiological information, blood biochemical parameters and ophthalmic characteristics including refractive status and ocular geometric parameters were obtained and analyzed.

RESULTS

69 right eyes from 69 patients (25 males and 44 females) with a median age of 10.00 years old (IQR: 8.00-11.00 years) were included in the study. Within Group A, there were a total of 17 individuals; Group B consisted of 22 individuals; Group C included 30 individuals. The mean axial length of three groups was 22.148(0.360), 23.503(0.342) and 24.770(0.556) mm, respectively (p < 0.0001). The mean HDL levels were significantly different in three groups are 1.824(0.307), 1.485(0.253) and 1.507 (0.265) mmol/L, respectively. By applying a Pearson Coefficient, we evaluated the association between axial length and HDL and discovered that there was a statistically significant (p = 0.00025) and adverse (R = -0.43) association between axial length and HDL.

CONCLUSIONS

We concluded from our study that there was a significantly inverse relationship between axial length and the levels of HDL in children.

Role of Apolipoprotein A1 in PPAR Signaling Pathway for Nonalcoholic Fatty Liver Disease

Peroxisome proliferator-activated receptors (PPARs) have been suggested to play crucial roles in the pathology of NAFLD with a vague understanding of the underlying mechanism. Here, we integrated large-scale literature data and clinical data to explore the potential role of the PPAR-APOA1 signaling pathway in the pathology of NAFLD. First, the signaling pathway connecting PPARs, APOA1, and NAFLD was constructed. Then, we employed clinical data to explore the association between APOA1 levels and NAFLD. In addition, we built the APOA1-driven pathway analysis to explore the potential mechanism of the APOA1-NAFLD association. Pathway analysis showed that APOA1 serves as a hubprotein connecting PPARs and NAFLD through a beneficial modulation of 16 out of 21 NAFLD upstream regulators. Each relationship within the composed pathway was supported by results from multiple previous studies. Clinical data analysis showed that an increase of APOA1 level was associated with a significantly decreased NAFLD prevalence (χ² = 292.109; P < 0.001). When other confounding factors were adjusted, serum APOA1 level was shown as an independent risk factor for the prevalence of NAFLD (P value<.0001; OR = 0.562). Our results suggested that the three PPARs (PPARA, PPARD, and PPARG) might promote the expression and molecular transportation of APOA1 to form a PPAR-APOA1 signaling pathway that demonstrated a beneficial role in the pathogenesis of NAFLD.

Analysis of Serum Paraoxonase 1 Using Mass Spectrometry and Lectin Immunoassay in Patients With Alpha-Fetoprotein Negative Hepatocellular Carcinoma

The diagnosis of AFP (alpha-fetoprotein)-negative HCC (hepatocellular carcinoma) mostly relies on imaging and pathological examinations, and it lacks valuable and practical markers. Protein N-glycosylation is a crucial post-translation modifying process related to many biological functions in an organism. Alteration of N-glycosylation correlates with inflammatory diseases and infectious diseases including hepatocellular carcinoma. Here, serum N-linked intact glycopeptides with molecular weight (MW) of 40–55 kDa were analyzed in a discovery set (n = 40) including AFP-negative HCC and liver cirrhosis (LC) patients using label-free quantification methodology. Quantitative lens culinaris agglutin (LCA) ELISA was further used to confirm the difference of glycosylation on serum PON1 in liver diseases (n = 56). Then, the alteration of site-specific intact N-glycopeptides of PON1 was comprehensively assessed by using Immunoprecipitation (IP) and mass spectrometry based ¹⁶O/¹⁸O C-terminal labeling quantification method to distinguish AFP-negative HCC from LC patients in a validation set (n = 64). Totally 195 glycopeptides were identified using a dedicated search engine pGlyco. Among them, glycopeptides from APOH, HPT/HPTR, and PON1 were significantly changed in AFP-negative HCC as compared to LC. In addition, the reactivity of PON1 with LCA in HCC patients with negative AFP was significantly elevated than that in cirrhosis patients. The two glycopeptides HAN²⁵³WTLTPLK (H5N4S2) and (H5N4S1) corresponding to PON1 were significantly increased in AFP-negative HCC patients, as compared with LC patients. Variations in PON1 glycosylation may be associated with AFP-negative HCC and might be helpful to serve as potential glycomic-based biomarkers to distinguish AFP-negative HCC from cirrhosis.

Importance of paraoxonase 1 (PON1) as an antioxidant and antiatherogenic enzyme in the cardiovascular complications of type 2 diabetes: Genotypic and phenotypic evaluation

Oxidant-antioxidant imbalance is involved in the etiology of different diseases, including cardiovascular diseases (CVDs), liver disorders, kidney diseases, cancers and diabetes mellitus. Antioxidant enzymes play a key role in striking an oxidant-antioxidant balance. Moreover, paraoxonase 1 (PON1) is an antioxidant enzyme that binds with high-density lipoprotein (HDL) in the circulation, and antioxidant and antiaterogenic properties of this lipoprotein are significantly associated with PON1. Research suggests PON1 contributes to the pathogenesis of certain human diseases such as type 2 diabetes (T2D). The association between PON1 and T2D appear to be reciprocal so that the disease significantly decreases PON1 levels and in turn, the genetics of PON1 may have a role the risk of susceptibility to T2D. Several factors that reduce the activity and concentration of PON1 in patients with T2D include increased glycation and loss-of-function polymorphisms. The genotypic and phenotypic evaluations of PON1 are therefore crucial for assessing the risk of cardiovascular complications in these patients, and strategies for increasing or restoring PON1 levels are useful for reducing or preventing their cardiovascular complications as their main cause of mortality. The present review aimed at discussing and emphasizing the key role of PON1 in T2D as a silent and dangerous disease.

Activity of Antioxidant Enzymes and Their Association with Lipid Profile in Mexican People without Cardiovascular Disease: An Analysis of Interactions

Dyslipidemia and oxidative stress are both considered to be factors involved in cardiovascular disease; however, the relationship between them has been little explored. In this work, we studied the association between the lipid profile and the activity of antioxidant enzymes such as paraoxonase-1 (PON1), superoxide dismutase 1 (SOD1), ceruloplasmin, and catalase, as well as total antioxidant capacity (the ferric-reducing ability of plasma (FRAP)), in 626 volunteers without cardiovascular disease. Their lipid profile was evaluated, and they were classified as having or not having high triglycerides (↑TG), high low-density cholesterol (↑LDLC), and low high-density cholesterol (↓HDLC), resulting in eight groups: Without dyslipidemia, ↑TG, ↑LDLC, ↓HDLC, ↑TG↑LDLC, ↑TG↓HDLC, ↑LDLC↓HDLC, and ↑TG↑LDLC↓HDLC. When comparisons by group were made, no significant differences in the activity of antioxidant enzymes were obtained. However, the linear regression analysis considering the potential interactions between ↑TG, ↑LDLC, and ↓HDLC suggested a triple interaction between the three lipid profile alterations on the activity of PON1 and a double interaction between ↑TG and ↑LDLC on ferroxidase-ceruloplasmin activity. The analysis presented in this work showed an association between the lipid profile and antioxidant-enzyme activity and highlighted the importance of considering the interactions between the components of a phenomenon instead of studying them individually. Longitudinal studies are needed to elucidate the nature of these associations.

The role of paraoxonase 1 in regulating high-density lipoprotein functionality during aging

Pharmacological interventions to increase the concentration of high-density lipoprotein (HDL) have led to disappointing results and have contributed to the emergence of the concept of HDL functionality. The anti-atherogenic activity of HDLs can be explained by their functionality or quality. The capacity of HDLs to maintain cellular cholesterol homeostasis and to transport cholesterol from peripheral cells to the liver for elimination is one of their principal anti-atherogenic activities. However, HDLs possess several other attributes that contribute to their protective effect against cardiovascular diseases. HDL functionality is regulated by various proteins and lipids making up HDL particles. However, several studies investigated the role of paraoxonase 1 (PON1) and suggest a significant role of this protein in the regulation of the functionality of HDLs. Moreover, research on PON1 attracted much interest following several studies indicating that it is involved in cardiovascular protection. However, the mechanisms by which PON1 exerts these effects remain to be elucidated.

The effects of green cardamom on blood glucose indices, lipids, inflammatory factors, paraxonase-1, sirtuin-1, and irisin in patients with nonalcoholic fatty liver disease and obesity: study protocol for a randomized controlled trial

BACKGROUND

The relationship between dietary components and nonalcoholic fatty liver disease (NAFLD) needs to be further investigated. The potential health benefits of cardamom have been found in some studies. Cardamom showed beneficial effect on hepatomegaly, dyslipidemia, and fasting hyperglycemia in animals. However, some adverse effects of cardamom have been reported in animals. No previous human study had been conducted on the effects of cardamom in NAFLD. This study aims to determine the effects of green cardamom (Elettaria cardamomum) supplementation on blood glucose indices, lipids, inflammatory profiles, and liver function, especially by examining irisin, paraxonase-1 (PON1) and sirtuin-1 (Sirt1) in obese patients with NAFLD.

METHODS

This trial is to be conducted at the polyclinic of the National Iranian Oil Company (NIOC) Central Hospital, Tehran. Eighty obese patients with NAFLD will be selected according to the eligibility criteria. The NAFLD diagnosis method is ultrasonography. Patients will be randomly divided into two groups by a random-number table (cardamom and placebo groups, two 500-mg capsules, three times/day, taken with meals for 3 months, follow-up monthly). General characteristics, dietary intakes (at the beginning, middle, and end), and physical activity (at the beginning and end) will be assessed using a general, 24-h food recall, and short-form International Physical Activity Questionnaires (IPAQ), respectively. Lifestyle advice will be presented to both groups identically. At the beginning and the end, anthropometrics (weight, height, and waist circumference), blood pressure, extent of fatty liver, and blood biomarkers, including serum glucose indices (fasting blood sugar (FBS)) and insulin (FBI), homeostasis model assessment-insulin resistance (HOMA-IR), Quantitative Insulin Sensitivity Check Index (QUICKI)), lipids (triglyceride (TG), low-density lipoprotein-cholesterol (LDL-c), high-density lipoprotein-cholesterol (HDL-c), total cholesterol (TC)), inflammatory markers (highly sensitive C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6)), liver enzymes (alanine transaminase (ALT), aspartate transaminase (AST)), irisin, PON1, and Sirt1, will be determined.

DISCUSSION

This trial would be the first to assess the effects of green cardamom on several blood factors, including glucose indices, lipids, inflammatory markers, liver enzymes, irisin, PON1, and Sirt1, and blood pressure and anthropometry in obese patients with NAFLD. Further study of cardamom's potential in improving NAFLD is suggested.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (IRCT), ID number: IRCT2015121317254N4 . Registered on 27 December 2015.

Chemokine ligand 2 and paraoxonase-1 in non-alcoholic fatty liver disease: The search for alternative causative factors

The incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) is constantly increasing. Despite this is apparently associated with the growing increase in obesity, insulin resistance and obesity-related metabolic disturbances their presence is not a necessary or sufficient condition to explain the accumulation of fat in the liver. Conversely, NAFLD is a predictor of other metabolic risks. NAFLD is currently the most frequent chronic liver disease but should not be considered benign or anecdotic because a considerable proportion of patients with NAFLD progress to cirrhosis and end-stage liver disease. Consequently, the search for alternative molecular mechanisms with therapeutic implications in NAFLD and associated disorders deserves a careful consideration. Mitochondria are possible targets as these organelles generate energy from nutrient oxidation. Some findings, generated in patients with extreme obesity and in murine models, support the notion that NAFLD could be a mitochondrial disease. This is plausible because mitochondrial dysfunction affects the accumulation of lipids in hepatocytes and promotes lipid peroxidation, the production of reactive oxygen species, the release of cytokines causing inflammation and cell death. Here we discuss basic research and mechanistic studies targeting the role of chemokine ligand 2 in liver inflammation and that of the paraoxonases in the oxidative stress. Their combination and association with mitochondrial dysfunction may uncover mechanisms underlying the progression of NAFLD and may help to identify novel therapeutic targets.

Paraoxonases and chemokine (C-C motif) ligand-2 in noncommunicable diseases

Oxidative stress and inflammation underpin most diseases; their mechanisms are inextricably linked. Chronic inflammation is associated with oxidation, anti-inflammatory cascades are linked to decreased oxidation, increased oxidative stress triggers inflammation, and redox balance inhibits the inflammatory cellular response. Whether or not oxidative stress and inflammation represent the cause or consequence of cellular pathology, they contribute significantly to the pathogenesis of noncommunicable diseases (NCD). The incidence of obesity and other related metabolic disturbances are increasing, as are age-related diseases due to a progressively aging population. Relationships between oxidative stress, inflammatory signaling, and metabolism are, in the broad sense of energy transformation, being increasingly recognized as part of the problem in NCD. In this chapter, we summarize the pathologic consequences of an imbalance between circulating and cellular paraoxonases, the system for scavenging excessive reactive oxygen species and circulating chemokines. They act as inducers of migration and infiltration of immune cells in target tissues as well as in the pathogenesis of disease that perturbs normal metabolic function. This disruption involves pathways controlling lipid and glucose homeostasis as well as metabolically driven chronic inflammatory states that encompass several response pathways. Dysfunction in the endoplasmic reticulum and/or mitochondria represents an important feature of chronic disease linked to oxidation and inflammation seen as self-reinforcing in NCD. Therefore, correct management requires a thorough understanding of these relationships and precise interpretation of laboratory test results.

Paraoxonase-1 deficiency is associated with severe liver steatosis in mice fed a high-fat high-cholesterol diet: a metabolomic approach

Oxidative stress is a determinant of liver steatosis and the progression to more severe forms of disease. The present study investigated the effect of paraoxonase-1 (PON1) deficiency on histological alterations and hepatic metabolism in mice fed a high-fat high-cholesterol diet. We performed nontargeted metabolomics on liver tissues from 8 male PON1-deficient mice and 8 wild-type animals fed a high-fat, high-cholesterol diet for 22 weeks. We also measured 8-oxo-20-deoxyguanosine, reduced and oxidized glutathione, malondialdehyde, 8-isoprostanes and protein carbonyl concentrations. Results indicated lipid droplets in 14.5% of the hepatocytes of wild-type mice and in 83.3% of the PON1-deficient animals (P < 0.001). The metabolomic assay included 322 biochemical compounds, 169 of which were significantly decreased and 16 increased in PON1-deficient mice. There were significant increases in lipid peroxide concentrations and oxidative stress markers. We also found decreased glycolysis and the Krebs cycle. The urea cycle was decreased, and the pyrimidine cycle had a significant increase in orotate. The pathways of triglyceride and phospholipid synthesis were significantly increased. We conclude that PON1 deficiency is associated with oxidative stress and metabolic alterations leading to steatosis in the livers of mice receiving a high-fat high-cholesterol diet.

Paraoxonase-1 status in patients with hereditary hemochromatosis

Hereditary hemochromatosis (HH) is characterized by accumulation of iron, oxidative stress, inflammation, and fibrogenesis in liver tissue. In this setting, research on the protection afforded by intracellular antioxidants is of clinical relevance. Paraoxonase-1 (PON1) is an enzyme that degrades lipid peroxides. This study investigates the alterations in serum PON1 status, PON1 gene polymorphisms, and PON1 hepatic expression in patients with HH. We performed a case-control study in 77 patients with HH (80.5% men, 22-70 years of age) and 408 healthy individuals (43.1% men, 26-74 years of age). Serum PON1 activities against different substrates and PON1192 and PON155 polymorphisms were analyzed. PON1 protein expression was investigated in 20 liver biopsies. HH patients had significantly lower serum PON1 activity, which was inversely correlated with ferritin (marker of iron stores) and serum 8-isoprostane concentrations (index of oxidative stress). PON1 protein expression in liver tissue was higher in patients and showed stronger staining in hepatocytes surrounding the areas of inflammation. Our study provides preliminary evidence that PON1 may play a role in protecting against iron-induced oxidative stress in hereditary hemochromatosis.

Relationship between vitamin D and IL-23, IL-17 and macrophage chemoattractant protein-1 as markers of fibrosis in hepatitis C virus Egyptians

AIM

To assess vitamin D in hepatitis C patients and its relationship to interleukin (IL)-23, IL-17, and macrophage chemoattractant protein-1 (MCP-1).

METHODS

The study was conducted on 50 Egyptian hepatitis C virus (HCV) genotype number IV-infected patients and 25 age- and gender-matched healthy subjects. Venous blood samples were obtained. Samples were allowed to clot and sera were separated by centrifugation and stored at -20 °C. A 25 hydroxy vitamin D assay was carried out using solid phase RIA. A 1,25 dihydroxy vitamin D assay was carried out using a commercial kit purchased from Incstar Corporation. IL-17 and -23 and MCP-1 were assayed by an enzyme immunoassay. Quantitative and qualitative polymerase chain reaction for HCV virus were done by TaqMan technology. Only HCV genotype IV-infected subjects were included in the study. The mean ± SD were determined, a t-test for comparison of means of different parameters was used. Correlation analysis was done using Pearson's correlation. Differences among different groups were determined using the Kruskal-Wallis test.

RESULTS

The mean vitamin D level in HCV patients (group I) was 15 ± 5.2 ng/mL while in control (group II) was 39.7 ± 10.8. For active vitamin D in group I as 16.6 ± 4.8 ng/mL while in group II was 41.9 ± 7.9. IL-23 was 154 ± 97.8 in group I and 6.7 ± 2.17 in group II. IL-17 was 70.7 ± 72.5 in cases and 1.2 ± 0.4 in control. MCP-1 was 1582 ± 794.4 in group I and 216.1 ± 5.38 in group II. Vitamin D deficiency affected 72% of HCV-infected patients and 0% of the control group. Vitamin D insufficiency existed in 28% of HCV-infected patients and 12% of the control group. One hundred percent of the cirrhotic patients and 40% of non cirrhotic HCV-infected patients had vitamin D deficiency. IL-23, IL-17, and MCP-1 were markedly increased in HCV-infected patients in comparison to controls.A significant negative correlation between vitamin D and IL-17 and -23 and MCP-1 was detected. HCV-infected males and females showed no differences with respect to viral load, vitamin D levels, IL-17, IL-23 and MCP-1. The viral load was negatively correlated with vitamin D and active vitamin D (P = 0.0001 and P = 0.001, respectively), while positively correlated with IL-23, IL-17, and MCP-1. We classified the patients according to sonar findings into four groups. Group Ia with bright hepatomegaly and included 14 patients. Group Ib with perihepatic fibrosis and included 11 patients. Group Ic with liver cirrhosis and included 11 patients. Group Id with hepatocellular carcinoma (HCC) and included 14 patients. Vitamin D and active vitamin D were shown to be lower in cirrhotic patients and much lower in patients with HCC, and this difference was highly significant (P = 0.0001). IL-17 and -23 and MCP-1 were higher in advanced liver disease) and the differences were highly significant (P = 0.0001).

CONCLUSION

Whether the deficiency of vitamin D is related to HCV-induced chronic liver disease or predisposing factor for higher viral load is a matter of debate.

Regulation of hepatic paraoxonase-1 expression

Serum paraoxonase-1 (PON1) is a member of the paraoxonases family (PON1, PON2, and PON3). PON1 is synthesized and secreted by the liver, and in circulation it is associated with HDL. PON1 has antioxidative properties, which are associated with the enzyme's capability to decrease oxidative stress in atherosclerotic lesions and to attenuate atherosclerosis development. Epidemiological evidence demonstrates that low PON1 activity is associated with increased risk of cardiovascular events and cardiovascular disease and is an independent risk factor for coronary artery disease. Therefore, pharmacological modulation of PON1 activity or PON1 gene expression could constitute a useful approach for preventing atherosclerosis. A primary determinant of serum PON1 levels is the availability of the enzyme for release by the liver, the principal site of PON1 production. Together with the enzyme secretion rate, enzymatic turnover, and protein stability, the level of PON1 gene expression is a major determinant of PON1 status. This paper summarizes recent progress in understanding the regulation of PON1 expression in hepatocytes.

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

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 CCl₄-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.