Liver Health

Endogenous vitamin E metabolites mediate allosteric PPARγ activation with unprecedented co-regulatory interactions

Sabine Willems, Leonie Gellrich, Apirat Chaikuad, Stefan Kluge, Oliver Werz, Jan Heering, Stefan Knapp, Stefan Lorkowski, Manfred Schubert-Zsilavecz, Daniel Merk

Cell Chem Biol . 2021 May 12;S2451-9456(21)00212-9. doi: 10.1016/j.chembiol.2021.04.019. Online ahead of print.

Abstract

Vitamin E exhibits pharmacological effects beyond established antioxidant activity suggesting involvement of unidentified mechanisms. Here, we characterize endogenously formed tocopherol carboxylates and the vitamin E mimetic garcinoic acid (GA) as activators of the peroxisome proliferator-activated receptor gamma (PPARγ). Co-stimulation of PPARγ with GA and the orthosteric agonist pioglitazone resulted in additive transcriptional activity. In line with this, the PPARγ-GA complex adopted a fully active conformation and interestingly contained two bound GA molecules with one at an allosteric site. A co-regulator interaction scan demonstrated an unanticipated co-factor recruitment profile for GA-bound PPARγ compared with canonical PPARγ agonists and gene expression analysis revealed different effects of GA and pioglitazone on PPAR signaling in hepatocytes. These observations reveal allosteric mechanisms of PPARγ modulation as an alternative avenue to PPARγ targeting and suggest contributions of PPARγ activation by α-13-tocopherolcarboxylate to the pharmacological effects of vitamin E.

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The effects of tocotrienols intake on obesity, blood pressure, inflammation, liver and glucose biomarkers: a meta-analysis of randomized controlled trials

Fengxiang Li, Biao Xu, Samira Soltanieh, Fernando Zanghelini, Ahmed Abu-Zaid, Jian Sun

Crit Rev Food Sci Nutr . 2021 Apr 28;1-14. doi: 10.1080/10408398.2021.1911926. Online ahead of print.

Abstract

The objective of this study is to accomplish a systematic review and meta-analysis of all randomized controlled trials that dissected the influence of tocotrienol supplementation on various anthropometric and cardiometabolic indices in all individuals, irrespective of health condition. This research was carried out in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines. 17 eligible articles were included in the final quantitative analysis. Current study revealed that tocotrienol consumption was not associated with CRP, WC, MDA, BMI, IL-6, HbA1C, ALT, AST, creatinine TNF-α, FPG, BW, DBP, and SBP. We did observe an overall increase in BW (SMD: 0.063 kg, 95% CI: -0.200, 0.327, p = 0.637) and DBP (SMD: 0.249 mmHg, 95% CI: 0.053, 0.446, p = 0.013). In addition, a significant reduction in SBP was observed (SMD: -0.616 mmHg, 95% CI: -1.123, -0.110, p = 0.017). In summary, our meta-analysis revealed that tocotrienol consumption was associated with increase in BW and DBP and decrease in SBP. Significant associations were not observed for other outcomes.

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Vitamin E and Lactobacillus Provide Protective Effects Against Liver Injury Induced by HgCl 2: Role of CHOP, GPR87, and mTOR Proteins

Ahlam Alhusaini, Shahad Alghilani, Waad Alhuqbani, Iman H Hasan

Dose Response . 2021 Apr 26;19(2):15593258211011360. doi: 10.1177/15593258211011360. eCollection Apr-Jun 2021.

Abstract

Background and objective: Mercury is one of the most harmful heavy metals and its toxicity causes severe multi-organ dysfunction. This study was designed to explore novel molecular pathways involved in the hepatoprotective effect of vitamin E (Vit-E) and Lactobacillius plantarum (Lac-B) against mercury toxicity.

Method: Acute hepatotoxicity was induced by administration of high dose of mercuric chloride (HgCl2) in male rats, Vit-E or/and Lac-B were given along with HgCl2 for 2 weeks. The effects of those antioxidants were studied focusing on their anti-apoptotic, anti-oxidative stress and anti-inflammatory eficacies. Histopathological examinations were also conducted.

Results: The administration of HgCl2 induced liver injury which manifested by elevation in serum ALT and AST. Liver MDA, caspase-3 and TNF-α levels were markedly increased; whereas, GSH level and SOD activity were declined. HgCl2 significantly elevated the expressions of hepatic CHOP, GPR87, NF-κB and mTOR. Histopathological examination revealed massive hepatocyte degeneration following HgCl2 administration. Treatment with Vit-E or/and Lac-B restored the normal levels of the previously mentioned parameters, as well as improved hepatic architecture.

Conclusion: Vit-E and Lac-B provided protective effect against HgCl2-induced hepatotoxicity via reduction of oxidative stress and inflammation, and downregulation of CHOP, GPR87, NF-κB and mTOR proteins’ expressions.

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The Combination of Berberine, Tocotrienols and Coffee Extracts Improves Metabolic Profile and Liver Steatosis by the Modulation of Gut Microbiota and Hepatic miR-122 and miR-34a Expression in Mice

Valentina Cossiga, Vincenzo Lembo, Cecilia Nigro, Paola Mirra, Claudia Miele, Valeria D'Argenio, Alessia Leone, Giovanna Mazzone, Iolanda Veneruso, Maria Guido, Francesco Beguinot, Nicola Caporaso, Filomena Morisco

Nutrients . 2021 Apr 13;13(4):1281. doi: 10.3390/nu13041281.

Abstract

Non-alcoholic-fatty liver disease (NAFLD) is spreading worldwide. Specific drugs for NAFLD are not yet available, even if some plant extracts show beneficial properties. We evaluated the effects of a combination, composed by Berberis Aristata, Elaeis Guineensis and Coffea Canephora, on the development of obesity, hepatic steatosis, insulin-resistance and on the modulation of hepatic microRNAs (miRNA) levels and microbiota composition in a mouse model of liver damage. C57BL/6 mice were fed with standard diet (SD, n = 8), high fat diet (HFD, n = 8) or HFD plus plant extracts (HFD+E, n = 8) for 24 weeks. Liver expression of miR-122 and miR-34a was evaluated by quantitativePCR. Microbiome analysis was performed on cecal content by 16S rRNA sequencing. HFD+E-mice showed lower body weight (p < 0.01), amelioration of insulin-sensitivity (p = 0.021), total cholesterol (p = 0.014), low-density-lipoprotein-cholesterol (p < 0.001), alanine-aminotransferase (p = 0.038) and hepatic steatosis compared to HFD-mice. While a decrease of hepatic miR-122 and increase of miR-34a were observed in HFD-mice compared to SD-mice, both these miRNAs had similar levels to SD-mice in HFD+E-mice. Moreover, a different microbial composition was found between SD- and HFD-mice, with a partial rescue of dysbiosis in HFD+E-mice. This combination of plant extracts had a beneficial effect on HFD-induced NAFLD by the modulation of miR-122, miR-34a and gut microbiome.

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Tocotrienols activate Nrf2 nuclear translocation and increase the antioxidant-related hepatoprotective mechanism in mice liver

Ahmed Atia, Nadia Salem Al-Rawaiq, Azman Abdullah

Curr Pharm Biotechnol . 2020 Sep 27. doi: 10.2174/1389201021666200928095950. Online ahead of print.

Abstract

Background: The most common preparation of tocotrienols is the tocotrienol-rich fraction (TRF). This study aimed to investigate whether TRF induced liver Nrf2 nuclear translocation and influenced the expression of Nrf2-regulated genes.

Methods: In the Nrf2 induction study, mice were divided into control, 2000 mg/kg TRF and diethyl maleate treated groups. After acute treatment, mice were sacrificed at specific time points. Liver nuclear extracts were prepared and Nrf2 nuclear translocation was detected through Western blotting. To determine the effect of increasing doses of TRF on the extent of liver nuclear Nrf2 translocation and its implication on the expression levels of several Nrf2-regulated genes, mice were divided into 5 groups (control, 200, 500 and 1000 mg/kg TRF, and butylated hydroxyanisole-treated groups). After 14 days, mice were sacrificed and liver RNA extracted for qPCR assay.

Results: 2000 mg/kg TRF administration initiated Nrf2 nuclear translocation within 30 min, reached maximum level around 1 h and dropped to half-maximal levels by 24 h. Incremental doses of TRF resulted in dose-dependent increases in liver Nrf2 nuclear levels, along with concomitant dose-dependent increases in the expressions of Nrf2-regulated genes.

Conclusion: TRF activated the liver Nrf2 pathway resulting in increased expression of Nrf2-regulated cytoprotective genes.

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4-HNE Immunohistochemistry and Image Analysis for Detection of Lipid Peroxidation in Human Liver Samples Using Vitamin E Treatment in NAFLD as a Proof of Concept

Maren C Podszun, Joon-Yong Chung, Kris Ylaya, David E Kleiner, Stephen M Hewitt, Yaron Rotman

J Histochem Cytochem . 2020 Sep;68(9):635-643. doi: 10.1369/0022155420946402.

Abstract

Lipid peroxidation is a common feature of liver diseases, especially non-alcoholic fatty liver disease (NAFLD). There are limited validated tools to study intra-hepatic lipid peroxidation, especially for small specimen. We developed a semi-quantitative, fully automated immunohistochemistry assay for the detection of 4-hydroxynoneal (4-HNE) protein adducts, a marker of lipid peroxidation, for adaptation to clinical diagnostics and research. We used Hep G2 cells treated with 4-HNE to validate specificity, sensitivity, and dynamic range of the antibody. Staining and semi-quantitative automated readout were confirmed in human needle-biopsy liver samples from subjects with NAFLD and normal liver histology. The ability to detect changes in lipid peroxidation was tested in paired liver biopsies from NAFLD subjects, obtained before and after 4 weeks of treatment with the antioxidant vitamin E (ClinicalTrials.gov NCT01792115, n=21). The cellular calibrator was linear and NAFLD patients had significantly higher levels of 4-HNE adducts compared to controls (p=0.02). Vitamin E treatment significantly decreased 4-HNE (p=0.0002). Our findings demonstrate that 4-HNE quantification by immunohistochemistry and automated image analysis is feasible and able to detect changes in hepatic lipid peroxidation in clinical trials. This method can be applied to archival and fresh samples and should be considered for use in assessing NAFLD histology.

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Dietary Intervention Accelerates NASH Resolution Depending on Inflammatory Status with Minor Additive Effects on Hepatic Injury by Vitamin E Supplementation

Julie Hviid Klaebel, Günaj Rakipovski, Birgitte Andersen, Jens Lykkesfeldt, Pernille Tveden-Nyborg

Antioxidants (Basel) . 2020 Sep 1;9(9):E808. doi: 10.3390/antiox9090808.

Abstract

Despite the lack of effective pharmacotherapy against nonalcoholic steatohepatitis (NASH) and liver fibrosis, vitamin E (vitE) supplementation and lifestyle modifications are recommended for the management of NASH due to promising clinical results. We recently reported a positive effect of supplementation with 800 IU vitE and atorvastatin on NASH resolution in guinea pigs. In the present study, we investigated the effect of high-dose vitE therapy combined with dietary intervention against progressive NASH and advanced fibrosis in the guinea pig model. Sixty-six guinea pigs received either high-fat (HF) or standard guinea pig chow diet (Control) for 25 weeks. Prior to eight weeks of intervention, HF animals were allocated into groups; dietary intervention (Chow) or dietary intervention with 2000 IU/d vitE supplementation (CvitE). Both Chow and CvitE reduced dyslipidemia, hepatic lipid accumulation and liver weight (p < 0.05), while CvitE further decreased hepatocellular ballooning (p < 0.05). Subanalyses of individual responses within intervention groups showed significant correlation between the hepatic hallmarks of NASH and lipid accumulation vs. inflammatory state (p < 0.05). Collectively, our results indicate that individual differences in sensitivity towards intervention and inflammatory status determine the potential beneficial effect of dietary intervention and high-dose vitE supplementation. Moreover, the study suggests that inflammation is a primary target in NASH treatment.

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Vitamin E treatment in NAFLD patients demonstrates that oxidative stress drives steatosis through upregulation of de-novo lipogenesis

Maren C Podszun, Ahmad S Alawad, Shilpa Lingala, Nevitt Morris, Wen-Chun A Huang, Shanna Yang, Megan Schoenfeld, Adam Rolt, Ronald Ouwerkerk, Kristin Valdez, Regina Umarova, Yanling Ma, Syeda Zaheen Fatima, Dennis D Lin, Lakshmi S Mahajan, Niharika Samala, Pierre-Christian Violet, Mark Levine, Robert Shamburek, Ahmed M Gharib, David E Kleiner, H Martin Garraffo, Hongyi Cai, Peter J Walter, Yaron Rotman

Redox Biol . 2020 Sep 1;37:101710. doi: 10.1016/j.redox.2020.101710. Online ahead of print.

Abstract

Oxidative stress (OS) in non-alcoholic fatty liver disease (NAFLD) promotes liver injury and inflammation. Treatment with vitamin E (α-tocopherol, αT), a lipid-soluble antioxidant, improves liver injury but also decreases steatosis, thought to be upstream of OS, through an unknown mechanism. To elucidate the mechanism, we combined a mechanistic human trial interrogating pathways of intrahepatic triglyceride (IHTG) accumulation and in vitro experiments. 50% of NAFLD patients (n = 20) treated with αT (200-800 IU/d) for 24 weeks had a ≥ 25% relative decrease in IHTG by magnetic resonance spectroscopy. Paired liver biopsies at baseline and week 4 of treatment revealed a decrease in markers of hepatic de novo lipogenesis (DNL) that strongly predicted week 24 response. In vitro, using HepG2 cells and primary human hepatocytes, αT inhibited glucose-induced DNL by decreasing SREBP-1 processing and lipogenic gene expression. This mechanism is dependent on the antioxidant capacity of αT, as redox-silenced methoxy-αT is unable to inhibit DNL in vitro. OS by itself was sufficient to increase S2P expression in vitro, and S2P is upregulated in NAFLD livers. In summary, we utilized αT to demonstrate a vicious cycle in which NAFLD generates OS, which feeds back to augment DNL and increases steatosis.

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Delta-tocotrienol supplementation improves biochemical markers of hepatocellular injury and steatosis in patients with nonalcoholic fatty liver disease: A randomized, placebo-controlled trial

Muhammad Amjad Pervez, Dilshad Ahmed Khan, Atiq Ur Rehman Slehria, Aamir Ijaz

Complement Ther Med . 2020 Aug;52:102494. doi: 10.1016/j.ctim.2020.102494. Epub 2020 Jun 23.

Abstract

Objective: The aim of this study was to examine the effects of delta-tocotrienol (δ-tocotrienol) supplementation on biochemical markers of hepatocellular injury and steatosis in patients with nonalcoholic fatty liver disease (NAFLD).

Design: The study design was a two-group, randomized, double-blind, placebo-controlled trial. The patients with NAFLD were randomly assigned to receive δ-tocotrienol 300 mg twice daily or placebo for 24 weeks.

Endpoints: The primary endpoints were change from baseline in fatty liver index (FLI) and homeostasis model of insulin resistance (HOMA-IR) after 24 weeks. Secondary endpoints included change from baseline in high sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), alanine transaminase (ALT), aspartate transaminase (AST) and grading of hepatic steatosis on ultrasound. Between-group differences were tested for significance using ANCOVA. Mean differences (MD) with 95 % CIs are reported.

Results: A total of 71 patients (tocotrienol=35, placebo=36) were randomized and included in the intention to treat analysis. Compared with placebo, δ-tocotrienol significantly reduced (MD [95 % CI]) FLI (-8.52 [-10.7, -6.3]; p < 0.001); HOMA-IR (-0.37 [-0.53, -0.21]; p < 0.001), hs-CRP (-0.61[-0.81, -0.42]; p < 0.001), MDA (-0.91 [-1.20, -0.63]; p < 0.001), ALT (-8.86 [-11.5, -6.2]; p < 0.001) and AST (-6.6 [-10.0, -3.08]; p < 0.001). Hepatic steatosis was also reduced by a significantly greater extent with tocotrienol than with placebo (p =0.047). No adverse events were reported.

Conclusion: δ-tocotrienol effectively improved biochemical markers of hepatocellular injury and steatosis in patients with NAFLD. δ-tocotrienol supplementation might be considered as a therapeutic option in the management of patients with NAFLD.

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Systematic review with meta-analysis: The effect of vitamin E supplementation in adult patients with non-alcoholic fatty liver disease

Andreas Vadarlis, Christina Antza, Dimitra Rafailia Bakaloudi, Ioannis Doundoulakis, Georgios Kalopitas, Myrto Samara, Theodoros Dardavessis, Theofanis Maris, Michael Chourdakis

J Gastroenterol Hepatol . 2020 Aug 18. doi: 10.1111/jgh.15221. Online ahead of print.

Abstract

Background: Νon-alcoholic fatty liver disease (NAFLD) is estimated to be the most common cause of end-stage liver disease in the next years. Vitamin E has shown beneficial effects as a possible “scavenger” of oxidative stress products, which play a major role in pathogenesis of the disease.

Aims: The purpose of the present meta-analysis is to investigate the effects of vitamin E supplementation in biochemical and histological parameters in adult patients with NAFLD.

Methods: Literature search was performed in major electronic databases (MEDLINE, CENTRAL and EMBASE) up to June 2020 for randomized clinical trials, which examined vitamin E versus placebo treatment in adults with NAFLD. Changes in liver enzymes were considered as primary outcomes, while changes in histology, biochemical and metabolic parameters as secondary. Quality of evidence was assessed through risk of bias according to the Cochrane risk of bias tool.

Results: Eight studies were included in qualitative analysis and seven in quantitative analysis. Vitamin E reduced the values of liver enzymes compared to placebo (-7.37 IU/L, 95% CI: -10.11 to -4.64 for ALT and -5.71 IU/L, 95% CI: -9.49 to -1.93 for AST) Additionally, vitamin E improved statistically significantly liver pathology in every individual histologic parameter as well LDL, FBG and serum leptin values.

Conclusions: Vitamin E can improve biochemical and histological characteristics of NAFLD patients, especially of NASH patients. The results indicate that vitamin E could be a promising choice and be considered as a treatment option in patients with NAFLD.

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