Protective effect of soy isoflavones and activity levels of plasma paraoxonase and arylesterase in the experimental nonalcoholic steatohepatitis model

Aloe vera gel relieves cadmium triggered hepatic injury via antioxidative, anti-inflammatory, and anti-apoptotic routes

Aloe vera (AV) gel extracted from fresh AV leaves was chosen in this study to evaluate its antioxidant, anti-inflammatory, and antiapoptotic activities against cadmium (Cd) -induced liver injury. Forty Wistar male adult rats were equally divided into four groups. Group I (standard control) ingested with 2.5 ml/kg b.w. of physiological saline. Group II (Cd-intoxicated) received 3 mg/kg b.w./day of CdCl2 dissolved in saline. Group III (AV) received 200 mg/kg b.w./day of AV gel dissolved in saline. Group IV (Cd+AV) ingested with 200 mg/kg b.w./day of AV gel solution along with 3 mg/kg b.w. CdCl2. All groups were ingested orally by gavage for 3 consecutive weeks. Paraoxonase-1 (PON-1) and HSP70 were measured in serum. The deposited Cd level, nitric oxide content, lipid peroxidation, collagen-1 (COL-1), and metalloproteinase-9 (MMP-9) levels were all determined in liver tissue homogenates. Gene expression of NF-κB and IL-6, Bax, and Bcl2, as well as immunohistochemistry analysis of activated caspase-3, was performed. Results showed that ingestion of AV gel greatly relieved all oxidative stress due to Cd exposure, modulated the NF-κB, IL-6, Bax, and Bcl2 expression levels, and improved the apoptotic state. In conclusion, AV gel confirmed its potential ameliorating effect against liver injury induced due to Cd exposure.

Synthesis, characterization and hypolipidemic effects of urazine derivatives on rat: Study of molecular modeling and enzyme inhibition

The prevalence of hyperlipidemia has increased dramatically worldwide. It is a major public health threat, characterized by the presence of an abnormal lipid profile, primarily with elevated serum total cholesterol (TC), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL) levels, and reduced high-density lipoprotein (HDL) level. Genetic factors, dietary and lifestyle habits play important roles in hyperlipidemia. It can increase the risk of chronic metabolic disorders, such as obesity, cardiovascular disease, and type II diabetes. The main objective of the present study was to evaluate the effect of urazine derivatives on serum triglyceride, cholesterol, LDL, HDL, and nitric oxide (NO) levels in high-fat diet (HFD)-induced hyperlipidemic rats. Synthetic compounds were prepared and confirmed by spectroscopic methods. Then, 88 male Sprague-Dawley rats were divided into 11 groups: control, HFD-treated group, HFD plus atorvastatin-treated group, and HFD plus 8 synthetic compounds-treated groups. The body weight, triglyceride, cholesterol, LDL, HDL, and NO levels were measured. The data with p < 0.05 were considered significant. The results indicated that HFD significantly increased cholesterol, triglyceride, and LDL levels and decreased NO concentration and HDL level compared to the control group (p < 0.05). However, HFD plus urazine derivatives significantly decreased NO, cholesterol, and triglyceride levels and increased HDL levels compared to the HFD-treated group (p < 0.05). Urazine derivatives may improve liver dysfunction in HFD-induced hyperlipidemic rats by modulation of detoxification enzymes and their anti-oxidant effects and also blood lipid profile.

The effects of Mediterranean diet on hepatic steatosis, oxidative stress, and inflammation in adolescents with non-alcoholic fatty liver disease: A randomized controlled trial

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver disease in children and adolescents. The optimal dietary strategy to improve hepatic stetatosis and reduce oxidative stress and inflammation in adolescents is unknown.

OBJECTIVE

This study was conducted to evaluate the effect of Mediterranean diet (MD) versus low-fat diet (LFD) on hepatic steatosis, inflammation, and oxidative stress in adolescents with obesity and NAFLD.

METHODS

Adolescents diagnosed with NAFLD between the ages of 11-18 years were randomized to either a MD or conventional LFD (control diet) for 12 weeks. Dietary status, anthropometry, body composition, and biochemical parameters were evaluated. Hepatic steatosis was determined by ultrasonography.

RESULTS

A total of 44 participants completed the study. At the end of the study, severity of hepatic steatosis, serum transaminase levels, and insulin resistance decreased significantly in both groups with no significant differences between groups except for aspartate aminotransferase (AST). The amount of decrease in AST levels in the MD group was greater than the LFD group (p < 0.05). In the MD group, serum total antioxidant capacity, paraoxanase-1, and glutathione peroxidase levels increased (p < 0.05); it did not change in the LFD group compared to baseline (p > 0.05). C-Reactive Protein (CRP) levels decreased only in the MD group (p = 0.008), interleukine-6 decreased only in the LFD group (p = 0.031).

CONCLUSION

Consumption of MD and LFD for 12 weeks in adolescents with obesity and NAFLD reduced BMI, fat mass, hepatic steatosis, and insulin resistance, improved high transaminase levels, and had positive effects on inflammation and oxidative stress. Registered under ClinicalTrials.gov Identifier no. NCT04845373.

Influence of dietary genistein and polyunsaturated fatty acids on lipid peroxidation and fatty acid composition of meat in quail exposed to heat stress

This experiment was conducted to investigate the effects of polyunsaturated fatty acids (PUFA) and genistein on performance and meat fatty acid profiles in quail exposed to heat stress. A total of 360 Japanese quail were divided into 12 groups in a 2 × 2 × 3 factorial design; each group comprised 30 quail with five replicates and were kept either at 22 ± 2 °C for 24 h/day (Thermoneutral, TN) or 34 ± 2 °C for 8 h/day (08:00 to 17:00 h) followed by 22 °C for 16 h (heat stress, HS) conditions. The diet contained either two levels of PUFA at 15 or 45% of total fat or three levels of genistein at 0, 400, or 800 mg/kg. Bodyweight gain, feed intake, and feed efficiency were lower (p ≥ 0.01) for quail reared under heat stress and fed low PUFA. Increasing dietary genistein in a linear manner improved the productive performance (p < 0.001). Heat stress caused increases in serum and thigh meat malondialdehyde (MDA) concentrations and decreases in genistein and vitamin E and A concentrations in serum and thigh meat (p < 0.001). High PUFA (PUFA45) in the diet of quail caused greater 18:2, 18:3 ALA, EPA, DHA, n-6, and n-3 PUFA as well as total PUFA and total USFA percentages (p < 0.001) in the thigh muscle, some of which decreased with heat stress (p ≥ 0.006) with no regard to genistein supplementation. This study revealed that genistein with greater doses along with greater PUFA inclusion to the diet of quail reared under heat stress is recommended for alleviating adverse effects of heat stress and for yielding healthier meat for human consumption.

Effects of phytochemicals on macrophage cholesterol efflux capacity: Impact on atherosclerosis

High-density lipoprotein cholesterol (HDL) is the major promoter of reverse cholesterol transport and efflux of excess cellular cholesterol. The functions of HDL, such as cholesterol efflux, are associated with cardiovascular disease rather than HDL levels. We have reviewed the evidence base on the major classes of phytochemicals, including polyphenols, alkaloids, carotenoids, phytosterols, and fatty acids, and their effects on macrophage cholesterol efflux and its major pathways. Phytochemicals show the potential to improve the efficiency of each of these pathways. The findings are mainly in preclinical studies, and more clinical research is warranted in this area to develop novel clinical applications.

The Effects of Anthocyanins and Their Microbial Metabolites on the Expression and Enzyme Activities of Paraoxonase 1, an Important Marker of HDL Function

High circulating HDL concentrations and measures of various HDL functions are inversely associated with cardiovascular disease (CVD) risk. Paraoxonase 1 (PON1) contributes to many of the athero-protective functions of HDL, such as promoting the reverse cholesterol transport process and reducing the levels of oxidized LDL. PON1 activities are influenced by several factors, the most important being diet and genetic polymorphisms. Reported data from randomized controlled trials have shown that anthocyanin consumption increased PON1 activity. However, the underlying molecular mechanisms by which anthocyanins increase PON1 activity are not understood. Therefore, the aim of this research was to investigate the ability of anthocyanins and their metabolites to increase PON1 gene expression and/or enzyme activities as potential mechanisms. The effect of the two predominant dietary anthocyanins and 18 of their recently identified microbial metabolites including their phase-II conjugates on PON1 gene expression was studied using a PON1-Huh7 stably-transfected cell line and reporter gene assay. The effects of these compounds on PON1 arylesterase and lactonase activities were investigated using two isoforms of the PON1 enzyme that are the phenotypes of the 192Q/R polymorphism. None of the compounds caused even modest changes in PON1 promoter activity (p ≥ 0.05). Further, none of the compounds at physiological concentrations caused any significant changes in the arylesterase or lactonase activity of either of the iso-enzymes. Cyanidin reduced the lactonase activity of the PON1-R192R enzyme at high concentrations (−22%, p < 0.001), but not at physiologically achievable concentrations. In conclusion, none of the data reported here support the notion that anthocyanins or their metabolites affect PON1 transactivation or enzyme activities.

Paraoxonases: metabolic role and pharmacological projection

Atherosclerosis is one of the leading causes of death in Western countries, with high-density lipoproteins (HDL) playing an important protective role due to their ability to inhibit oxidation of low-density lipoproteins (LDL), thus relieving vascular subendothelial damage. One of the proteins constituting HDL particles is paraoxonase-1 (PON1), an enzyme able to hydrolyze aryl esters, lactones, and organophosphates. Other closely related paraoxonases are designated as PON2, which is a protein localized inside many different kinds of cells, and PON3, not only present in HDL but also in mitochondria and endoplasmic reticulum, as well. Given that the amount and the activity of PON1 in human serum are significantly lower in people suffering from cardiovascular diseases, enhancing both parameters might contribute to their treatment and prevention. One of the physiologically interesting substrates for the abovementioned hydrolytic cleavage is homocysteine thiolactone (HTL), an atherothrombotic active form of homocysteine. Although it was therefore postulated that PON1 would participate in preventing the HTL-mediated lipid peroxidation, some attention is recently paid to other enzymes, like biphenyl hydrolase-like protein, that seem to more selectively involved in lowering this risk factor. The aim of this paper is to elucidate the role of paraoxonases, especially PON1, by reviewing the latest studies in order to understand both its physiological role and modulation by drugs, nutrients, and plant extracts.

Effects of Dietary Flavonoids on Reverse Cholesterol Transport, HDL Metabolism, and HDL Function

Strong experimental evidence confirms that HDL directly alleviates atherosclerosis. HDL particles display diverse atheroprotective functions in reverse cholesterol transport (RCT), antioxidant, anti-inflammatory, and antiapoptotic processes. In certain inflammatory disease states, however, HDL particles may become dysfunctional and proatherogenic. Flavonoids show the potential to improve HDL function through their well-documented effects on cellular antioxidant status and inflammation. The aim of this review is to summarize the basic science and clinical research examining the effects of dietary flavonoids on RCT and HDL function. Based on preclinical studies that used cell culture and rodent models, it appears that many flavonoids (e.g., anthocyanidins, flavonols, and flavone subclasses) influence RCT and HDL function beyond simple HDL cholesterol concentration by regulating cellular cholesterol efflux from macrophages and hepatic paraoxonase 1 expression and activity. In clinical studies, dietary anthocyanin intake is associated with beneficial changes in serum biomarkers related to HDL function in a variety of human populations (e.g., in those who are hyperlipidemic, hypertensive, or diabetic), including increased HDL cholesterol concentration, as well as HDL antioxidant and cholesterol efflux capacities. However, clinical research on HDL functionality is lacking for some flavonoid subclasses (e.g., flavanols, flavones, flavanones, and isoflavones). Although there has been a tremendous effort to develop HDL-targeted drug therapies, more research is warranted on how the intake of foods or specific nutrients affects HDL function.

Review article: novel methods for the treatment of non-alcoholic steatohepatitis - targeting the gut immune system to decrease the systemic inflammatory response without immune suppression

BACKGROUND

The systemic immune system plays a role in inflammation and fibrogenesis associated with non-alcoholic steatohepatitis (NASH) and has become a potential target for drug development. In particular, the gut immune system has been suggested as a means for generating signals that can target the systemic immune system.

AIM

To describe seven novel methods being developed for the treatment of NASH that target the gut immune system for alleviation of the systemic inflammatory response, including oral administration of fatty-liver-derived proteins, anti-CD3 antibodies, tumour necrosis factor fusion protein, anti-lipopolysaccharide antibodies, glucosylceramide, delayed-release mercaptopurine, and soy-derived extracts.

METHODS

A search for these methods for oral immunotherapy for NASH was conducted.

RESULTS

Oral administration of these compounds provides an opportunity for immune modulation without immune suppression, with the advantage of being independent of a single molecular/inflammatory pathway. These modes of oral immune therapy demonstrate superior safety profiles, such that the patient is not exposed to general immune suppression. Moreover, these approaches target the whole spectrum of the disease and may serve as adjuvants to other therapies, such that they provide a platform for treatment of concomitant disorders in patients with NASH, including diabetes and hyperlipidaemia. Most of the compounds reviewed are currently in phase II trials, and it is anticipated that the acquisition of more clinical data in the next few years will enable the use of this new class of drugs for the treatment of NASH.

CONCLUSION

Oral immunotherapy may provide a novel platform for the treatment of NASH.

Genistein protects dermal fibrosis in bleomycin-induced experimental scleroderma

OBJECTIVE

Genistein, a phytoestrogen, has anti-oxidant, anti-inflammatory, and anti-angiogenic properties. The aim of the present study is to evaluate the protective effect of genistein in bleomycin (BLM)-induced dermal fibrosis.

MATERIAL AND METHODS

This study involved four groups of Balb/c mice (n=10 per group). Mice in three groups were administered BLM [100 μg/day in 100 μL phosphate-buffered saline (PBS)] subcutaneously for 4 weeks; the remaining (control) group received only 100 μL/day of PBS subcutaneously. PBS or BLM was injected into the shaved upper back. Two of the BLM-treated groups also received genistein (1 or 3 mg/kg/day, subcutaneously, to the dorsal front of neck). At the end of the fourth week, all mice were sacrificed and blood and tissue samples were obtained.

RESULTS

The BLM applications increased the dermal thicknesses, tissue hydroxyproline contents, α-smooth muscle actin-positive cell counts, and led to histopathologically prominent dermal fibrosis. The genistein treatments decreased the tissue hydroxyproline contents and dermal thicknesses, in the BLM-injected mice.

CONCLUSION

Genistein has antifibrotic potential in BLM-induced dermal fibrosis model. However, its therapeutic potentials on human scleroderma require evaluation in future studies.

Açai (Euterpe oleracea Mart.) Upregulates Paraoxonase 1 Gene Expression and Activity with Concomitant Reduction of Hepatic Steatosis in High-Fat Diet-Fed Rats

Açai (Euterpe oleracea Mart.), a fruit from the Amazon region, has emerged as a promising source of polyphenols. Açai consumption has been increasing owing to ascribed health benefits and antioxidant properties; however, its effects on hepatic injury are limited. In this study, we evaluated the antioxidant effect of filtered açai pulp on the expression of paraoxonase (PON) isoforms and PON1 activity in rats with nonalcoholic fatty liver disease (NAFLD). The rats were fed a standard AIN-93M (control) diet or a high-fat (HF) diet containing 25% soy oil and 1% cholesterol with or without açai pulp (2 g/day) for 6 weeks. Our results show that açai pulp prevented low-density lipoprotein (LDL) oxidation, increased serum and hepatic PON1 activity, and upregulated the expression of PON1 and ApoA-I in the liver. In HF diet-fed rats, treatment with açai pulp attenuated liver damage, reducing fat infiltration and triglyceride (TG) content. In rats receiving açai, increased serum PON1 activity was correlated with a reduction in hepatic steatosis and hepatic injury. These findings suggest the use of açai as a potential therapy for liver injuries, supporting the idea that dietary antioxidants are a promising approach to enhance the defensive systems against oxidative stress.

Altered distribution of regulatory lymphocytes by oral administration of soy-extracts exerts a hepatoprotective effect alleviating immune mediated liver injury, non-alcoholic steatohepatitis and insulin resistance

AIM

To determine the immune-modulatory and the hepatoprotective effects of oral administration of two soy extracts in immune mediated liver injury and non-alcoholic steatohepatitis (NASH).

METHODS

Two soy extracts, M1 and OS, were orally administered to mice with concanavalin A (ConA) immune-mediated hepatitis, to high-fat diet (HFD) mice and to methionine and choline reduced diet combined with HFD mice. Animals were followed for disease and immune biomarkers.

RESULTS

Oral administration of OS and M1 had an additive effect in alleviating ConA hepatitis manifested by a decrease in alanine aminotransferase and aspartate aminotransferase serum levels. Oral administration of the OS and M1 soy derived fractions, ameliorated liver injury in the high fat diet model of NASH, manifested by a decrease in hepatic triglyceride levels, improvement in liver histology, decreased serum cholesterol and triglycerides and improved insulin resistance. In the methionine and choline reduced diet combined with the high fat diet model, we noted a decrease in hepatic triglycerides and improvement in blood glucose levels and liver histology. The effects were associated with reduced serum tumor necrosis factor alpha and alteration of regulatory T cell distribution.

CONCLUSION

Oral administration of the combination of OS and M1 soy derived extracts exerted an adjuvant effect in the gut-immune system, altering the distribution of regulatory T cells, and alleviating immune mediated liver injury, hyperlipidemia and insulin resistance.

PON1 and Mediterranean Diet

The Mediterranean diet has been proven to be highly effective in the prevention of cardiovascular diseases. Paraoxonase 1 (PON1) has been implicated in the development of those conditions, especially atherosclerosis. The present work describes a systematic review of current evidence supporting the influence of Mediterranean diet and its constituents on this enzyme. Despite the differential response of some genetic polymorphisms, the Mediterranean diet has been shown to exert a protective action on this enzyme. Extra virgin olive oil, the main source of fat, has been particularly effective in increasing PON1 activity, an action that could be due to low saturated fatty acid intake, oleic acid enrichment of phospholipids present in high-density lipoproteins that favor the activity, and increasing hepatic PON1 mRNA and protein expressions induced by minor components present in this oil. Other Mediterranean diet constituents, such as nuts, fruits and vegetables, have been effective in modulating the activity of the enzyme, pomegranate and its compounds being the best characterized items. Ongoing research on compounds isolated from all these natural products, mainly phenolic compounds and carotenoids, indicates that some of them are particularly effective, and this may enhance the use of nutraceuticals and functional foods capable of potentiating PON1 activity.

Chicory (Cichorium intybus L.) root extract regulates the oxidative status and antioxidant gene transcripts in CCl4-induced hepatotoxicity

The ability of Cichorium intybus root extract (chicory extract) to protect against carbon tetrachloride (CCl4)-induced oxidative stress and hepatotoxicity was evaluated in male rats. The rats were divided into four groups according to treatment: saline (control); chicory extract (100 mg/kg body weight daily, given orally for 2 weeks); CCl4 (1 ml/kg body weight by intraperitoneal injection for 2 consecutive days only); or chicory extract (100 mg/kg body weight daily for 2 weeks) + CCl4 injection on days 16 and 17. The levels of hepatic lipid peroxidation, antioxidants, and molecular biomarkers were estimated twenty-four hours after the last CCl4 injection. Pretreatment with chicory extract significantly reduced CCl4-induced elevation of malondialdehyde levels and nearly normalized levels of glutathione and activity of glutathione S-transferase, glutathione peroxidase (GPx), glutathione reductase, catalase (CAT), paraoxonase-1 (PON1), and arylesterase in the liver. Chicory extract also attenuated CCl4-induced downregulation of hepatic mRNA expression levels of GPx1, CAT and PON1 genes. Results of DNA fragmentation support the ability of chicory extract to ameliorate CCl4-induced liver toxicity. Taken together, our results demonstrate that chicory extract is rich in natural antioxidants and able to attenuate CCl4-induced hepatocellular injury, likely by scavenging reactive free radicals, boosting the endogenous antioxidant defense system, and overexpressing genes encoding antioxidant enzymes.

Novel insights into the mechanisms whereby isoflavones protect against fatty liver disease

Fatty liver disease (FLD) is a growing public health problem worldwide. There is an urgent requirement for alternative and natural medicine to treat this disease. As phytochemicals, isoflavones have attracted considerable attention for the prevention of FLD. Numerous studies have revealed that isoflavones protect against FLD through various pathways which modulate fatty acid β-oxidation, lipid synthesis, and oxidative stress. Recently, the aldose reductase (AR)/polyol pathway has been reported to be involved in the development of FLD by modulating hepatic fructose production, peroxisome proliferator-activated receptor (PPAR)α activity, cytochrome P450 (CYP)2E1 expression, and gut bacterial endotoxin-induced cytokine release. It has been reported that some isoflavones are potent AR inhibitors. Here, we review the anti-FLD actions of isoflavones and the proposed mechanism whereby isoflavones protect against FLD, with regard to the AR/polyol pathway. We propose that isoflavones block the AR/polyol pathway and in turn reduce fructose production and subsequent fat accumulation in the liver in diabetic or high-glucose-diet mice. In addition, in rodents with alcoholic liver disease or nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, inhibition of AR by isoflavones may improve PPARα-mediated fatty acid oxidation, reduce hepatic steatosis, and attenuate CYP2E1-mediated oxidative stress or AR/gut bacterial endotoxin-mediated cytokine overproduction, to alleviate progression of FLD.

Prevention of nonalcoholic steatohepatitis in rats by two manganese-salen complexes

BACKGROUND

Nonalcoholic steatohepatitis (NASH), a progressive stage of nonalcoholic fatty liver disease (NAFLD), is characterized by steatosis with inflammation. Investigations have suggested that oxidative stress may play an important role in the progress of NAFLD to NASH. To provide further insights into beneficial effects of antioxidants in NASH prevention, we employed two manganese-superoxide dismutase/catalase mimetics, manganese N,N`-bis(salicyldene) ethylene diamine chloride (EUK-8) and manganese-3-methoxy N,N`-bis(salicyldene)ethylenediamine chloride (EUK-134), as two salen representatives and vitamin C as the standard antioxidant.

METHODS

Experimental NASH was induced in Male N-Mary rats by feeding a methionine/choline-deficient (MCD) diet to rats for 10 weeks. The rats (n = 5, 30 mg/kg/day) were randomly assigned to receive vitamin C, EUK-8, EUK-134 or vehicle orally.

RESULTS

Administration of salens together with the MCD diet reduced the serum aminotransferases, glutathione transferase and alkaline phosphatase, cholesterol, and LDL contents. In addition, the EUK-8 and EUK-134 improved NASH pathological features in liver of MCD-fed rats.

CONCLUSION

EUK-8 and EUK-134 supplementation reduces NASH-induced abnormalities, pointing out that antioxidant strategy could be beneficial for prevention of NASH.

Soybean greatly reduces valproic acid plasma concentrations: a food-drug interaction study

The aim of this study was to investigate the effects of soy on the pharmacokinetics and pharmacodynamics of valproic acid (VPA). In a preclinical study, rats were pretreated with two different amounts of soy extract for five days (150 mg/kg and 500 mg/kg), which resulted in decreases of 57% and 65% in the Cmax of VPA, respectively. AUC of VPA decreased to 83% and 70% in the soy pretreatment groups. Interestingly, the excretion rate of VPA glucuronide (VPAG) was higher in the soy-fed groups. Levels of UDP-glucuronosyltransferase (UGT) UGT1A3, UGT1A6, UGT2B7 and UGT2B15 were elevated in the soy-treated group, and GABA concentrations were elevated in the brain after VPA administration. However, this was less pronounced in soy extract pretreated group than for the untreated group. This is the first study to report the effects of soy pretreatment on the pharmacokinetics and pharmacodynamics of VPA in rodents.

Paraoxonase 1 and oxidative stress in paediatric non-alcoholic steatohepatitis

BACKGROUND & AIMS

Non-alcoholic steatohepatitis (NASH) in children is a significant public health concern. Oxidative stress is an important component in the pathophysiology of NASH. Several enzymatic antioxidant mechanisms protect the liver from oxidative injury. Examination of the expression of these enzymes in NASH livers may provide insight on the roles for these antioxidant mechanisms in the pathophysiology of NASH.

METHODS

The mRNA expression of catalase, glutathione peroxidase 1 (GPX1), glutathione reductase (GSR), paraoxonase 1 (PON1) and other reactive oxygen species-related genes was evaluated by microarray and quantitative real-time PCR analyses. The PON1 protein levels were evaluated in liver and serum by Western blot analyses. Serum enzymatic activities of GPX, GSR and PON1 (paraoxonase and arylesterase activities) were examined.

RESULTS

NASH livers exhibited elevated mRNA expression of catalase and PON1, but not GPX1 or GSR. No difference in serum GPX or GSR activity was detected between NASH patients and controls. Elevated expression of PON1 mRNA and protein was detected in NASH livers, but serum PON1 protein and activities were not elevated.

CONCLUSIONS

Elevated expression of catalase and PON1 suggests protective roles for these antioxidants in NASH livers. Given the importance of oxidative stress in the pathophysiology of NASH, future studies focusing on these enzymes could identify important targets for therapeutic or preventive interventions for NASH patients.

Functionally defective high-density lipoprotein and paraoxonase: a couple for endothelial dysfunction in atherosclerosis

The endothelium is the primary target for biochemical or mechanical injuries caused by the putative risk factors of atherosclerosis. Endothelial dysfunction represents the ultimate link between atherosclerotic risk factors that promote atherosclerosis. HDL-C is thought to exert at least some parts of its antiatherogenic facilities via stimulating endothelial NO production, nearby inhibiting oxidative stress and inflammation. HDL-C is capable of opposing LDL's inductive effects and avoiding the ox-LDL's inhibition of eNOS. Paraoxonase 1 (PON1) is an HDL-associated enzyme esterase which appears to contribute to the antioxidant and antiatherosclerotic capabilities of HDL-C. "Healthy HDL," namely the particle that contains the active Paraoxonase 1, has the power to suppress the formation of oxidized lipids. "Dysfunctional HDL," on the contrary, has reduced Paraoxonase 1 enzyme activity and not only fails in its mission but also potentially leads to greater formation of oxidized lipids/lipoproteins to cause endothelial dysfunction. The association of HDL-C PON1 and endothelial dysfunction depends largely on the molecules with exact damaging effect on NO synthase coupling. Loss of nitric oxide bioavailability has a pivotal role in endothelial dysfunction preceding the appearance of atherosclerosis. Analyses of HDL-C and Paraoxonase1 would be more important in the diagnosis and treatment of atherosclerosis in the very near future.

Phyto-power dietary supplement potently inhibits dimethylnitrosamine-induced liver fibrosis in rats

Curcumin has been extensively studied for its therapeutic effects in a variety of disorders. Fermented soy consumption is associated with a low incidence rate of chronic diseases in many Asian countries. The aim of this study was to investigate the potential underlying mechanisms of the effect of a phyto-power dietary supplement on liver fibrosis. Sprague-Dawley rats were intraperitoneally injected with dimethylnitrosamine (DMN; 10 mg kg(-1)) three times a week for four consecutive weeks. A phyto-power dietary supplement (50 or 100 mg kg(-1)) was administered by oral gavage daily for four weeks. Liver morphology, function, and fibrotic status were examined in DMN induced hepatic fibrogenesis. However, a phyto-power dietary supplement alleviated liver damage as indicated by histopathological examination of the α-smooth muscle actin (α-SMA) and collagen I, accompanied by the concomitant reduction of transforming growth factor-β1 (TGF-β1) and matrix metalloproteinase 2 (MMP2). These data indicate that the phyto-power dietary supplement may inhibit the TGF-β1/Smad signaling and relieve liver damage in experimental fibrosis.

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.

The Past and Present of Paraoxonase Enzyme: Its Role in the Cardiovascular System and Some Diseases

Although paraoxonase is synthesized in many tissues including the heart, colon, kidneys, lungs, small intestines and brain, its major locus of synthesis is the liver. PON1 is in close association with apolipoproteins and protects LDL against oxidation. It was reported that PON1 quantities dropped to 40 times lower than normal in cardiovascular diseases and diseases like diabetes, ulcerative colitis, Crohn's disease, chronic renal failure, SLE, Behcet's disease, cancer, hepatitis B, obesity, metabolic syndrome, Alzheimer's and dementia. It is speculated that the concerning decline in serum PON1 amount results from single nucleotide polymorphism in the coding (Q192R, L55M) and promoter (T-108C) sites of the PON1 gene. Additionally, circulating amounts of PON1 are affected by vitamins, antioxidants, fatty acids, dietary factors, drugs, age and lifestyle. This collection attempts to review and examine the past and present studies of paraoxonase and its relation with the cardiovascular system and some relevant diseases.

Naringenin is an inhibitor of human serum paraoxonase (PON1): an in vitro study

BACKGROUND

Inhibition studies on PON1 as an organophosphate-hydrolyzing and atheroprotective enzyme could be useful in elucidating the function of PON1. This study is aimed at examining the in vitro effects of the flavonoid naringenin on PON1 activity in human serum and purified enzyme.

METHODS

The inhibition kinetics of the interaction of naringenin with human PON1 in serum and purified enzyme was determined spectrophotometrically using paraoxon and phenylacetate as the substrates.

RESULTS

Naringenin could be introduced as an effective inhibitor on purified human PON1 activity for phenylacetate as the substrate with an IC(50) value of 10 µM. Paraoxonase and arylesterase activities of PON1, in the serum assay, were also inhibited by naringenin with IC(50) values of 37.9 and 34.6 µM, respectively. PON1, according to acompetitive-type inhibition pattern, was inhibited by naringenin with K(i) constant of 14.5 µM for serum paraoxonase activity. The results were compared with a known inhibitor of PON1, 2-hydroxyquinoline. We believe (to our knowledge) that this is the first reported study for kinetic parameters of PON1 inhibition by naringenin.

CONCLUSIONS

Lipophilic property appears to be an important feature of the structure in evaluating the inhibitor potential. Comparison of our findings and other authors showed that the induction of PON1 gene by naringenin and its inhibitory effects on the enzyme protein are probably two different mechanisms by which the flavonoid affects PON1. The in vitro data reported in this study could be useful in the development of structure-activity relationship for PON1 inhibition.

Amelioration of diet-induced nonalcoholic steatohepatitis in rats by Mn-salen complexes via reduction of oxidative stress

BACKGROUND

Nonalcoholic steatohepatitis (NASH), a progressive stage of nonalcoholic fatty liver disease (NAFLD), is characterized by steatosis (accumulation of triacylglycerols within hepatocytes) along with inflammation and ballooning degeneration. It has been suggested that oxidative stress may play an important role in the progress of NAFLD to NASH. The aim of present study was to determine whether antioxidant supplementations using EUK-8, EUK-134 and vitamin C could improve the biochemical and histological abnormalities associated with diet-induced NASH in rats.

METHODS

NASH was induced in male N-Mary rats by feeding a methionine - choline deficient (MCD) diet. The rats were fed either normal chow or MCD diet for 10 weeks. After NASH development, the MCD-fed rats were randomly divided into four groups of six: the NASH group that received MCD diet, the EUK-8 group which was fed MCD diet plus EUK-8, the EUK-134 group which was fed MCD diet plus EUK-134 and the vitamin C group which received MCD diet plus vitamin C. EUK-8, EUK-134 and vitamin C (30 mg/kg body weight/day) were administered by gavage for eight weeks.

RESULTS

Treatment of MCD-fed rats with salens reduced the sera aminotransferases, cholesterol, low density lipoprotein contents, the extent of lipid peroxidation and protein carbonylation whereas the HDL-C cholesterol levels were significantly increased. In addition, EUK-8 and EUK-134 improved steatosis, ballooning degeneration and inflammation in liver of MCD-fed rats.

CONCLUSION

Antioxidant (EUK-8, EUK-134 and vitamin C) supplementation reduces NASH-induced biochemical and histological abnormalities, pointing out that antioxidant strategy could be beneficial in treatment of NASH.

Anti-apoptotic and anti-inflammatory effects of Silybum marianum in treatment of experimental steatohepatitis

In this study, we were aimed to evaluate the probable effect of the crud extract of Silybum marianum, with high polyphenolic content, on experimental nonalcoholic steatohepatitis (NASH). To induce NASH, a methionine and choline deficient (MCD) diet was given to N-Mary rats for 8 weeks. After NASH development, MCD-fed rats were divided into two groups: MCD groups received MCD diet and MCD+S group was fed MCD diet plus crude extract of S. marianum orally for 3 weeks. Control group was fed a normal diet for 11 weeks. Finally, all rats were sacrificed. Plasma alanine amino transferase (ALT) and aspartate amino transferase (AST) levels were evaluated. In addition, the following hepatic factors were also evaluated: liver histology, malondialdehyde (MDA) and reduced glutathione (GSH) contents, gene expressions of TNF-α and TGF-β and immunoblot evaluations of caspase-3, ERK/p-ERK, JNK/pJNK and p38/pp38. Histopathological evaluations of the liver samples revealed that treatment with the S. marianum extract has abated the severity of NASH among the MCD-fed rats. Also, a significant reduction was observed in the sera ALT and AST activities. In addition, the extract caused dramatic reduction in the elevated hepatic TNF-α and TGF-β mRNA and MDA levels along with an increase in the GSH content. Moreover, the plant extract treatments significantly lowered activation of procaspase-3 to active caspase-3 and also lowered the phosphorylated form of JNK among the same group of rats. These results suggest that the S. marianum crude extract beneficial effects on NASH are mainly due to its antioxidant and anti-inflammatory activities.

Soy isoflavone delays the progression of thioacetamide-induced liver fibrosis in rats

OBJECTIVE

Our aim was to investigate the effect of soy isoflavone (SI) on liver fibrosis in a thioacetamide (TAA)-induced rat model.

MATERIALS AND METHODS

Twenty-eight rats were assigned to four groups: sham group, fibrosis group, low-dose treatment group (LDg) and high-dose treatment group (HDg). SI (90 or 270 mg/kg) was administered daily during the model development by TAA. Standard liver tests, platelet derived growth factor-BB (PDGF-BB) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were measured. The expression of collagen, α-smooth muscle actin (α-SMA) and transforming growth factor-β1 (TGF-β1) in liver tissue was determined. Electron microscopy was used to perform ultrastructural analysis of the livers.

RESULTS

Hepatic fibrosis was induced by 8 weeks of TAA administration. However, following the administration of SI, collagen staining significantly declined as compared with the fibrosis group (p < 0.01). Less collagen fibers around the hepatic stellate cells (HSCs) were observed in HDg as compared to the fibrosis group and LDg. There was no significant difference in standard liver tests between the fibrosis group and the two treatment groups. The levels of PDGF-BB and TIMP-1 in the two SI-treated groups were significantly lower than in the fibrosis group (p < 0.01). The expression of α-SMA and TGF-β1 in HDg was less than that in the fibrosis group and LDg (p < 0.01).

CONCLUSION

Administration of a high dose of SI resulted in an obvious inhibitory effect on liver fibrosis induced by TAA in rats. One hypothesis is that the effect may be related to the inhibition of HSC activation and proliferation.

Pharmacological and dietary modulators of paraoxonase 1 (PON1) activity and expression: the hunt goes on

Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated enzyme displaying esterase and lactonase activity. PON1 hydrolyzes several organophosphorus (OP) insecticides and nerve agents, a number of exogenous and endogenous lactones, and metabolizes toxic oxidized lipids of low density lipoproteins (LDL) and HDL. As such, PON1 plays a relevant role in determining susceptibility to OP toxicity, cardiovascular diseases and several other diseases. Serum PON1 activity in a given population can vary by at least 40-fold. Most of this variation can be accounted for by genetic polymorphisms in the coding region (Q192R, L55M) and in the promoter region (T-108C). However, exogenous factors may also modulate PON1 activity and/or level of expression. This paper examines various factors that have been found to positively modulate PON1. Certain drugs (e.g. hypolipemic and anti-diabetic compounds), dietary factors (antioxidants, polyphenols), and life-style factors (moderate alcohol consumption) appear to increase PON1 activity. Given the relevance of PON1 in protecting from certain environmental exposure and from cardiovascular and other diseases, there is a need for further mechanistic, animal, and clinical research in this area, and for consideration of possible alternative strategies for increasing the levels and activity of PON1.

Teucrium polium reversed the MCD diet-induced liver injury in rats

In the present study, we evaluated the ability of Teucrium polium ethyl acetate fraction, with high antioxidant activity, in the treatment of nonalcoholic steatohepatitis (NASH) in rats and its possible effect on factors involved in pathogenesis of the disease. To induce NASH, a methionine and choline deficient (MCD) diet was given to N-Mary rats for 8 weeks. After NASH development, MCD-fed rats were divided into 2 groups: NASH group that received MCD diet and NASH + T group which was fed MCD diet plus ethyl acetate fraction of T. polium orally for 3 weeks. Histopathological evaluations revealed that treatment with the extract has abated the severity of NASH among the MCD-fed rats. In addition, the fraction reduced the elevated levels of hepatic tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) gene expression and also the elevated level of malondialdehyde (MDA). In addition, the extract increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and enhanced the level of hepatic glutathione (GSH). Moreover, the fraction treatments lowered caspase-3 level and the phosphorylated form of C-Jun N-terminal kinase (JNK) and augmented the phosphorylated level of extracellular regulated kinase1/2 (ERK1/2). These results indicate that the ethyl acetate fraction of T. poium effectively reversed NASH, mainly due to its strong antioxidant and anti-inflammatory properties.

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.

Teucrium polium in prevention of steatohepatitis in rats

BACKGROUND

In this study, we tried to evaluate whether the ethyl acetate (EtOAc) extract of Teucrium polium, with a high antioxidant activity, is able to prevent the incidence of nonalcoholic steatohepatitis.

METHODS

Nonalcoholic steatohepatitis was induced in male N-Mary rats using a methionine/choline-deficient (MCD) diet. Rats were given normal diet (A), normal diet+EtOAc extract (B), MCD diet (C) and MCD diet+EtOAc (D).

RESULTS

The MCD diet led to grade 1 liver steatosis, inflammation and ballooning degeneration. In group D, these factors abated to grade 0 in 80% of the rats. In groups receiving the EtOAc extract, lipoprotein profiles had significantly improved relative to those not receiving the extract. Also, a dramatic reduction was observed in the sera alkaline phosphatase, aspartate aminotransferase and alanine aminoteransferase activities. The activities of the liver superoxide dismutase, glutathione peroxidase and glutathione reductase enzymes were also enhanced.

CONCLUSION

The EtOAc extract could reverse the adverse effects of the MCD diet.

Paraoxonase-1 is related to inflammation, fibrosis and PPAR delta in experimental liver disease

BACKGROUND

Paraoxonase-1 (PON1) is an antioxidant enzyme synthesized by the liver. It protects against liver impairment and attenuates the production of the pro-inflammatory monocyte chemoattractant protein-1 (MCP-1). We investigated the relationships between hepatic PON1 and MCP-1 expression in rats with liver disease and explored the possible molecular mechanisms involved.

METHODS

CCl4 was administered for up to 12 weeks to induce liver damage. Serum and hepatic levels of PON1 and MCP-1, their gene and protein expression, nuclear transcription factors, and histological and biochemical markers of liver impairment were measured.

RESULTS

High levels of PON1 and MCP-1 expression were observed at 12th week in the hepatocytes surrounding the fibrous septa and inflammatory areas. CCl4-administered rats had an increased hepatic PON1 concentration that was related to decreased gene transcription and inhibited protein degradation. Decreased PON1 gene transcription was associated with PPARdelta expression. These changes were accompanied by increased hepatic MCP-1 concentration and gene expression. There were significant direct relationships between hepatic PON1 and MCP-1 concentrations (P = 0.005) and between PON1 and the amount of activated stellate cells (P = 0.001).

CONCLUSION

Our results from this experimental model suggest a hepato-protective role for PON1 against inflammation, fibrosis and liver disease mediated by MCP-1.

Paraoxonase-1 is related to inflammation, fibrosis and PPAR delta in experimental liver disease

BACKGROUND

Paraoxonase-1 (PON1) is an antioxidant enzyme synthesized by the liver. It protects against liver impairment and attenuates the production of the pro-inflammatory monocyte chemoattractant protein-1 (MCP-1). We investigated the relationships between hepatic PON1 and MCP-1 expression in rats with liver disease and explored the possible molecular mechanisms involved.

METHODS

CCl4 was administered for up to 12 weeks to induce liver damage. Serum and hepatic levels of PON1 and MCP-1, their gene and protein expression, nuclear transcription factors, and histological and biochemical markers of liver impairment were measured.

RESULTS

High levels of PON1 and MCP-1 expression were observed at 12th week in the hepatocytes surrounding the fibrous septa and inflammatory areas. CCl4-administered rats had an increased hepatic PON1 concentration that was related to decreased gene transcription and inhibited protein degradation. Decreased PON1 gene transcription was associated with PPARdelta expression. These changes were accompanied by increased hepatic MCP-1 concentration and gene expression. There were significant direct relationships between hepatic PON1 and MCP-1 concentrations (P = 0.005) and between PON1 and the amount of activated stellate cells (P = 0.001).

CONCLUSION

Our results from this experimental model suggest a hepato-protective role for PON1 against inflammation, fibrosis and liver disease mediated by MCP-1.

Administration of beta-glycolipids overcomes an unfavorable nutritional dependent host milieu: a role for a soy-free diet and natural ligands in intrahepatic CD8+ lymphocyte trapping and NKT cell redistribution

Soy-based diets are a major source of sphingolipids and play a complicated role in various aspects of the immune system. Administration of beta-glycolipids, including beta-glucosylceramide (GC), beta-lactosylceramide (LC) and a 1:1 combination of GC and LC (IGL) were shown to exert immune-modulatory effects.

AIM

To examine the effects of a soy-free diet, and several beta-glycolipids on concanavalin A (ConA)-induced hepatitis in the presence of an altered host glycolipid milieu.

METHODS

ConA hepatitis was induced in C57BL/6 mice that were fed a soy-free diet (glycolipid content 200 micromol/kg). Two hours prior to administration of ConA, animals were injected IP with GC, LC, IGL or PBS. Animals were sacrificed 6 h after ConA administration.

RESULTS

Both a soy-free diet and administration of beta-glycolipids were associated with significant alterations in the distribution of NKT cells. Specifically, there was a decrease in intrahepatic and an increase in intrasplenic NKT lymphocytes. beta-glycolipids prevented the ConA-induced intrahepatic CD8 lymphocyte trapping, not seen in mice with only a soy-free diet. Both a soy-free diet and beta-glycolipids alleviated ConA-induced hepatitis by inhibiting IL10 secretion and increasing IL12 serum levels. The effect of IGL was clinically and immunological superior to that of either glycolipid alone.

CONCLUSIONS

Both a soy-free diet and beta-glycolipids can overcome the unfavorable host milieu in the setting of ConA hepatitis. The host glycolipid milieu profoundly influenced the immune and clinical effects of various insults, and suggests that alteration of the glycolipid background of the host can serve as a novel therapeutic tool.

Down-regulation of a hepatic transporter multidrug resistance-associated protein 2 is involved in alteration of pharmacokinetics of glycyrrhizin and its metabolites in a rat model of chronic liver injury

Glycyrrhizin (GL) has been used to treat chronic hepatitis in Japan and Europe. It is thought to induce pseudoaldosteronism via inhibition of type 2 11beta-hydroxysteroid dehydrogenase (11beta-HSD2) by glycyrrhetinic acid (GA), a major metabolite of GL. A previous clinical study suggested that 3-monoglucuronyl-glycyrrhetinic acid (3MGA), another metabolite of GL, might play a more important role in the pathogenesis of pseudoaldosteronism. The present study evaluates the pharmacokinetics of GL and its metabolites in rats with chronic liver injury induced by a choline-deficient l-amino acid-defined (CDAA) diet to clarify the relationship between 3MGA and pseudoaldosteronism. In rats fed a CDAA diet, plasma concentrations and urinary eliminations of GL and 3MGA were markedly higher than in the rats fed the control diet; the plasma concentration of GA was unaffected when GL was orally administered. Immunohistochemical analysis revealed the suppression of levels of multidrug resistance-associated protein (Mrp) 2 and its localization in the hepatic tissue of rats fed a CDAA diet. When 3MGA was i.v. injected in rats fed a CDAA diet or injected in Mrp2-dysfunctional Eisai hyperbilirubinemic rats, plasma concentrations of 3MGA were higher, and biliary excretion of 3MGA was lower than in each control group. The results suggested that 3MGA would be excreted to bile via hepatic Mrp2 and that its dysfunction would reduce 3MGA clearance. 3MGA accumulated by liver fibrosis resulted in the increased excretion through renal tubule and might be strongly related to the pathogenesis of pseudoaldosteronism because 11beta-HSD2 is expressed in renal tubular epithelial cells.

The treatment with antibody of TNF-alpha reduces the inflammation, necrosis and fibrosis in the non-alcoholic steatohepatitis induced by methionine- and choline-deficient diet

To assess the effects of anti-TNF-alpha antibody (infliximab) in experimental steatohepatitis induced by methionine- and choline-deficient (MCD) diet. The study included thirty rats. One group received normal rat food, and two groups received MCD diet. The treatment group received a single dose intra-peritoneal infliximab (4 mg/kg), at week 8. MCD diet increased levels of AST, ALT, TNF-alpha, TGF-beta(1), tissue and plasma MDA (p < 0.05 for each). Moreover, it led to steatosis, ballooning degeneration, inflammation, fibrosis and increased actin expression, histopathologically (p < 0.05 for each). In this experimental steatohepatitis anti-TNF-alpha antibody decreased the levels of AST, ALT, TGF-beta(1) and plasma and tissue MDA (p < 0.05 for each). Moreover, inflammation, necrosis, actin expression and fibrosis decreased in anti-TNF-alpha group compared to placebo group (p < 0.05 for each). This study indicates that anti-TNF-alpha antibody is effective on necrosis, inflammation and fibrosis in the experimental model of non-alcoholic steatohepatitis, induced by MCD diet.