Blackcurrant (Ribes nigrum) Prevents Obesity-Induced Nonalcoholic Steatohepatitis in Mice

Dietary sugar kelp (Saccharina latissima) consumption did not attenuate atherosclerosis in low-density lipoprotein receptor knockout mice

We previously demonstrated the beneficial effects of U.S.-grown sugar kelp (Saccharina latissima), a brown seaweed, on reducing serum triglycerides (TG) and total cholesterol (TC) and protecting against inflammation and fibrosis in the adipose tissue of diet-induced obesity mice. In this current study, we aimed to explore whether the dietary consumption of sugar kelp can prevent atherosclerosis using low-density lipoprotein receptor knockout (Ldlr KO) mice fed an atherogenic diet. Eight-week-old male Ldlr KO mice were fed either an atherogenic high-fat/high-cholesterol control (HF/HC) diet or a HF/HC diet supplemented with 6% (w/w) sugar kelp (HF/HC-SK) for 16 weeks. Consumption of sugar kelp significantly increased the body weight gain without altering fat mass and lean mass. Also, there were no significant differences in energy expenditure and physical activities between the groups. The two groups did not show significant differences in serum and hepatic TG and TC levels or the hepatic expression of genes involved in cholesterol and lipid metabolism. Although serum alanine aminotransferase (ALT) activity did not differ significantly between the two groups, there were significant increases in the expression of macrophage markers, including adhesion G protein-coupled receptor E1 and cluster of differentiation 68, as well as tumor necrosis factor alpha in the HF/HC-SK group compared to the HF/HC mice. The consumption of sugar kelp did not elicit a significant effect on the development of aortic lesions. Moreover, lipopolysaccharide-stimulated splenocytes isolated from HF/HC-SK-fed mice showed no significant changes in the mRNA levels of pro-inflammatory genes compared with those from the HF/HC mice. In summary, the consumption of dietary sugar kelp did not elicit anti-atherogenic and hepatoprotective effects in Ldlr KO mice.

Anthocyanins: Potential phytochemical candidates for the amelioration of non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is described by too much hepatic fat deposition causing steatosis, which further develops into nonalcoholic steatohepatitis (NASH), defined by necroinflammation and fibrosis, progressing further to hepatic cirrhosis, hepatocellular carcinoma, and liver failure. NAFLD is linked to different aspects of the metabolic syndrome like obesity, insulin resistance, hypertension, and dyslipidemia, and its pathogenesis involves several elements including diet, obesity, disruption of lipid homeostasis, and a high buildup of triglycerides and other lipids in liver cells. It is therefore linked to an increase in the susceptibility to developing diabetes mellitus and cardiovascular diseases. Several interventions exist regarding its management, but the availability of natural sources through diet will be a benefit in dealing with the disorder due to the immensely growing dependence of the population worldwide on natural sources owing to their ability to treat the root cause of the disease. Anthocyanins (ACNs) are naturally occurring polyphenolic pigments that exist in the form of glycosides, which are the glucosides of anthocyanidins and are produced from flavonoids via the phenyl propanoid pathway. To understand their mode of action in NAFLD and their therapeutic potential, the literature on in vitro, in vivo, and clinical trials on naturally occurring ACN-rich sources was exhaustively reviewed. It was concluded that ACNs show their potential in the treatment of NAFLD through their antioxidant properties and their efficacy to control lipid metabolism, glucose homeostasis, transcription factors, and inflammation. This led to the conclusion that ACNs possess efficacy in the amelioration of NAFLD and the various features associated with it. However, additional clinical trials are required to justify the potential of ACNs in NAFLD.

Biological activities, therapeutic potential, and pharmacological aspects of blackcurrants (Ribes nigrum L): A comprehensive review

Blackcurrant possesses various health-endorsing attributes owing to its polyphenol profile. Recent studies have demonstrated its therapeutic potential against various health disorders. Various bioactives present in blackcurrants have different functional and pharmacological aspects including anti-inflammatory, antioxidant, and antimicrobial properties. The most dominant and important bioactive include anthocyanins, flavonols, phenolic acids, and polyunsaturated fatty acids. Food formats derived from blackcurrants comprise pomace, juice, powder, and extracts. All these food formats have industrial, prebiotic, and pharmacological benefits. In the current article, the nutritional composition, industrial applications, and therapeutic potential are discussed in the recent literature. Moreover, novel extraction techniques for the extraction of bioactive compounds present in blackcurrants and their safety concerns have been elaborated.

Effects of blackcurrant extract on indole and ammonia productions in an in vitro human fecal culture model

Blackcurrant is available as a traditional medicine in Europe. However, the detailed effects of blackcurrant on the human gut microbiota remain unknown. In this study, we investigated the prebiotic effects of a blackcurrant extract using a human fecal culture model in six healthy subjects. Feces were individually inoculated into a medium with or without the blackcurrant extract and then fermented for 48 hr under anaerobic conditions. The results obtained from analysis of samples from the fermented medium demonstrated that after 48 hr of fermentation, the pH of the medium with the blackcurrant extract was significantly decreased (control, 6.62 ± 0.20; blackcurrant extract, 6.41 ± 0.33; p=0.0312). A 16S rRNA gene sequencing analysis of the microbiota of the fermented medium showed a significant increase in the relative abundance of Bifidobacteriaceae. In measuring the concentrations of putrefactive components in the fermented medium, we found that the blackcurrant extract significantly reduced ammonia levels and displayed a tendency toward reduced indole levels. Our results suggest that blackcurrant extract could be a potential ingredient for relief of putrefactive components in the gut.

Blackcurrant Alleviates Dextran Sulfate Sodium (DSS)-Induced Colitis in Mice

Previous studies have reported that anthocyanin (ACN)-rich materials have beneficial effects on ulcerative colitis (UC). Blackcurrant (BC) has been known as one of the foods rich in ACN, while studies demonstrating its effect on UC are rare. This study attempted to investigate the protective effects of whole BC in mice with colitis using dextran sulfate sodium (DSS). Mice were orally given whole BC powder at a dose of 150 mg daily for four weeks, and colitis was induced by drinking 3% DSS for six days. Whole BC relieved symptoms of colitis and pathological changes in the colon. The overproduction of pro-inflammatory cytokines such as IL-1β, TNF-α, and IL-6 in serum and colon tissues was also reduced by whole BC. In addition, whole BC significantly lowered the levels of mRNA and protein of downstream targets in the NF-κB signaling pathway. Furthermore, BC administration increased the expression of genes related to barrier function: ZO-1, occludin, and mucin. Moreover, the whole BC modulated the relative abundance of gut microbiota altered with DSS. Therefore, the whole BC has demonstrated the potential to prevent colitis through attenuation of the inflammatory response and regulation of the gut microbial composition.

Dietary Intervention with Blackcurrant Pomace Protects Rats from Testicular Oxidative Stress Induced by Exposition to Biodiesel Exhaust

The exposure to diesel exhaust emissions (DEE) contributes to negative health outcomes and premature mortality. At the same time, the health effects of the exposure to biodiesel exhaust emission are still in scientific debate. The aim of presented study was to investigate in an animal study the effects of exposure to DEE from two types of biodiesel fuels, 1st generation B7 biodiesel containing 7% of fatty acid methyl esters (FAME) or 2nd generation biodiesel (SHB20) containing 7% of FAME and 13% of hydrotreated vegetable oil (HVO), on the oxidative stress in testes and possible protective effects of dietary intervention with blackcurrant pomace (BC). Adult Fisher344/DuCrl rats were exposed by inhalation (6 h/day, 5 days/week for 4 weeks) to 2% of DEE from B7 or SHB20 fuel mixed with air. The animals from B7 (n = 14) and SHB20 (n = 14) groups subjected to filtered by a diesel particulate filter (DPF) or unfiltered DEE were maintained on standard feed. The rats from B7+BC (n = 12) or SHB20+BC (n = 12), exposed to DEE in the same way, were fed with feed supplemented containing 2% (m/m) of BC. The exposure to exhaust emissions from 1st and 2nd generation biodiesel resulted in induction of oxidative stress in the testes. Higher concentration of the oxidative stress markers thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides (LOOHs), 25-dihydroxycholesterols (25(OH)2Ch), and 7-ketocholesterol (7-KCh) level), as well as decreased level of antioxidant defense systems such as reduced glutathione (GSH), GSH/GSSG ratio, and increased level of oxidized glutathione (GSSG)) were found. Dietary intervention reduced the concentration of TBARS, 7-KCh, LOOHs, and the GSSG level, and elevated the GSH level in testes. In conclusion, DEE-induced oxidative stress in the testes was related to the biodiesel feedstock and the application of DPF. The SHB20 DEE without DPF technology exerted the most pronounced toxic effects. Dietary intervention with BC in rats exposed to DEE reduced oxidative stress in testes and improved antioxidative defense parameters, however the redox balance in the testes was not completely restored.

MiR-192-5p Alleviated Fibrosis and Inflammatory Responses of Tendon Cells by Targeting NFAT5

Objective

To explore the effect of microRNA (miR)-192-5p on the inflammatory and fibrotic responses of tendon cells.

Methods

Tendon cells were treated with transforming growth factor-β1 (TGF-β1). The expression of miR-192-5p and nuclear factor of activated T cells 5 (NFAT5) in tendon cells were detected by RT-qPCR. The expressions of inflammatory and fibrosis-related factors were detected by RT-qPCR and Western blot. MiR-192-5p binds to NFAT5 targeting by TargetScan and dual-luciferase reporter gene assay. The expression of the NFAT5 gene was detected by RT-qPCR and Western blot. Detection of apoptosis in tendon cells by flow cytometry.

Results

MiR-192-5p was downregulated in tendon cells, and the expression level gradually decreased with the prolong of TGF-β1 treatment. The expression of NFAT5 increased with the treatment time of TGF-β1. The expression of miR-192-5p decreased collagen III (COLIII), α smooth muscle actin (α-SMA), matrix metalloproteinase- (MMP-) 1, and MMP-8 expression, thereby inhibiting TGF-β1-induced fibrosis in tendon cells. The expression of miR-192-5p decreased the expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β, thereby alleviating TGF-β1-induced inflammatory response and reduce apoptosis in tendon cells. NFAT5 is a direct target of miR-192-5p in tendon cells. The upregulation of NFAT5 reversed the effect of miR-192-5p on the fibrotic activity and inflammatory response of TGF-β1-stimulated tendon cells.

Conclusions

MiR-192-5p alleviates fibrosis and inflammatory responses of tendon cells by targeting NFAT5.

Macrophage Polarization and Its Role in Liver Disease

Macrophages are important immune cells in innate immunity, and have remarkable heterogeneity and polarization. Under pathological conditions, in addition to the resident macrophages, other macrophages are also recruited to the diseased tissues, and polarize to various phenotypes (mainly M1 and M2) under the stimulation of various factors in the microenvironment, thus playing different roles and functions. Liver diseases are hepatic pathological changes caused by a variety of pathogenic factors (viruses, alcohol, drugs, etc.), including acute liver injury, viral hepatitis, alcoholic liver disease, metabolic-associated fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Recent studies have shown that macrophage polarization plays an important role in the initiation and development of liver diseases. However, because both macrophage polarization and the pathogenesis of liver diseases are complex, the role and mechanism of macrophage polarization in liver diseases need to be further clarified. Therefore, the origin of hepatic macrophages, and the phenotypes and mechanisms of macrophage polarization are reviewed first in this paper. It is found that macrophage polarization involves several molecular mechanisms, mainly including TLR4/NF-κB, JAK/STATs, TGF-β/Smads, PPARγ, Notch, and miRNA signaling pathways. In addition, this paper also expounds the role and mechanism of macrophage polarization in various liver diseases, which aims to provide references for further research of macrophage polarization in liver diseases, contributing to the therapeutic strategy of ameliorating liver diseases by modulating macrophage polarization.

Sugar kelp (Saccharina latissima) inhibits hepatic inflammation and fibrosis in a mouse model of diet-induced nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH), closely associated with obesity, is a health concern worldwide. We investigated whether the consumption of U.S.-grown sugar kelp (Saccharina latissima), an edible brown alga, can prevent obesity-associated metabolic disturbances and NASH in a mouse model of diet-induced NASH. Male C57BL/6J mice were fed a low-fat diet, a high-fat/high-sucrose/high-cholesterol diet (HF), or a HF diet containing sugar kelp (HF-Kelp) for 14 weeks. HF-Kelp group showed lower body weight with increased O2 consumption, CO2 production, physical activity, and energy expenditure compared with the HF. In the liver, there were significant decreases in weight, triglycerides, total cholesterol, and steatosis with HF-Kelp. The HF-Kelp group decreased hepatic expression of a macrophage marker adhesion G protein-coupled receptor E1 (Adgre1) and an M1 macrophage marker integrin alpha x (Itgax). HF-Kelp group also exhibited decreased liver fibrosis, as evidenced by less expression of fibrogenic genes and collagen accumulation than those of HF group. In epididymal white adipose tissue (eWAT), HF-Kelp group exhibited decreases in eWAT weight and adipocyte size compared with those of the HF. HF-Kelp group showed decreased expression of collagen type VI alpha 1 chain, Adgre1, Itgax, and tumor necrosis factor α in eWAT. We demonstrated, for the first time, that the consumption of U.S-grown sugar kelp prevented the development of obesity and its associated metabolic disturbances, steatosis, inflammation, and fibrosis in the liver and eWAT of a diet-induced NASH mouse model.

A mouse model of the regression of alcoholic hepatitis: Monitoring the regression of hepatic steatosis, inflammation, oxidative stress, and NAD+ metabolism upon alcohol withdrawal

This study aimed to develop a well-characterized mouse model of alcoholic hepatitis (AH) regression. Male C57BL/6J mice were fed a Lieber-DeCarli (LD) control diet or LD containing 5% ethanol for ten days followed by one binge, which is the chronic-binge model of AH developed by the National Institute on Alcohol Abuse and Alcoholism. To determine AH regression, mice previously exposed to ethanol were put on LD control diet and metabolic and inflammatory features were monitored weekly for three weeks. Serum alcohol, total cholesterol, and alanine transaminase levels were increased in ethanol-fed mice, which declined to those of no ethanol controls within one and three weeks after ethanol withdrawal, respectively. Serum malondialdehyde was increased with ethanol feeding, but it was restored to no ethanol control levels within one week. Ethanol-induced changes in the hepatic expression of genes involved in lipogenesis, fatty acid oxidation, ethanol metabolism, and antioxidant response were restored to those of no ethanol controls after 3 weeks of ethanol withdrawal. Also, ethanol-induced hepatic inflammation was gradually decreased during the 3 weeks of ethanol withdrawal. Hepatic nicotinamide adenine dinucleotide (NAD⁺) levels and the expression of enzymes involved in the NAD⁺ salvage pathway were decreased by ethanol feeding, which was mitigated after ethanol withdrawal. Ethanol significantly lowered hepatic sirtuin 1 expression, but its levels were restored with ethanol cessation. This study established a mouse model of AH regression, which can be used as a preclinical model to study the potential of dietary bioactives or therapeutic agents on AH regression.

The loss of histone deacetylase 4 in macrophages exacerbates hepatic and adipose tissue inflammation in male but not in female mice with diet-induced non-alcoholic steatohepatitis

Epigenetic regulation in macrophages plays a crucial role in the inflammatory response of cells. We investigated the role of macrophage histone deacetylase 4 (HDAC4) in diet-induced obesity and non-alcoholic steatohepatitis using macrophage-specific Hdac4 knockout mice (Hdac4^MKO ). Hdac4 floxed control (Hdac4^fl/fl ) and Hdac4^MKO mice were fed a regular chow diet or an obesogenic high-fat/high-sucrose/high-cholesterol (HF/HS/HC) diet for 12 weeks. The loss of macrophage Hdac4, compared with Hdac4^fl/fl control, aggravated the diet-induced inflammation in the liver and white adipose tissue only in male mice. Splenic monocytes isolated from male mice fed the HF/HS/HC diet showed increased lipopolysaccharide (LPS) sensitivity and decreased Ly6C-/Ly6C+ ratios in male Hdac4^MKO mice, but not in females. Bone marrow-derived macrophages (BMMs) from male Hdac4^MKO mice had a lesser efferocytotic capacity but higher proinflammatory gene expression upon LPS stimulation than male Hdac4^fl/fl mice. However, female Hdac4^MKO BMMs exhibited the opposite responses. The induction of estrogen receptor α (ERα, Esr1) expression by LPS was less in male but more in female Hdac4^MKO BMMs than Hdac4^fl/fl BMMs. Moreover, overexpression of human HDAC4 decreased basal expression of Esr1 and abolished its induction by LPS. Inhibition of ERα increased Hdac4 with induction of inflammatory genes, whereas activation of ERα decreased Hdac4 with reduction of inflammatory genes in male and female Hdac4^fl/fl BMMs treated with LPS. However, regardless of the inhibition or activation of ERα, proinflammatory genes were induced by LPS more in male Hdac4^MKO BMMs than Hdac4^fl/fl cells, whereas cells in females showed opposite responses. In conclusion, this study suggests that the lack of macrophage Hdac4 aggravates hepatic and white adipose inflammation in male mice with diet-induced obesity and non-alcoholic steatohepatitis, and not in female mice. HDAC4 and ERα appear to counteract each other, but ERα may not be a major player in sex-dependent inflammatory responses in macrophages deficient in HDAC4. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hypocholesterolemic Effect of Blackcurrant (Ribes nigrum) Extract in Healthy Female Subjects: A Pilot Study

Blackcurrant extract (BCE) ameliorates dyslipidemia in menopausal model animals and in elderly women at a risk of dyslipidemia. However, it is unknown whether the daily intake of BCE can prevent lipid abnormalities in healthy individuals. Lipids are essential for the body, but they also cause arteriosclerosis. In this noncomparative pilot study, we examined the effects of BCE administered for 29 days on serum lipids in young healthy women. Blood samples were collected before and on days 4 and 29 after BCE intake, and 20 lipoprotein fractions in the serum were separated using a gel-permeation high-performance liquid chromatography method to measure the triacylglycerol and cholesterol levels in lipoproteins. There were no effects on lipids on day 4 of BCE intake, but the total cholesterol level decreased on day 29. Furthermore, the levels of total very-low-density lipoprotein (VLDL) cholesterol, small VLDL cholesterol, and large low-density lipoprotein cholesterol were significantly decreased. These results suggest that the daily intake of BCE has a hypocholesterolemic effect in healthy women, and that it is effective in preventing atherosclerosis.

Liver-spleen axis in nonalcoholic fatty liver disease

Introduction: NAFLD is often under-diagnosed, even though rates of its co-morbidities such as obesity and type2 diabetes mellitus, prominent statuses of inflammation, are significantly high. The spleen-liver axis is gaining much credit in the last years like other well-known organ axes.Areas covered: PubMed/MEDLINE was searched for relevant articles related to concomitant occurrence of NAFLD and spleen. Areas covered in this review include: (1) updated findings of spleen dimensions at ultrasonography, (2) discussion of current data on pathophysiological connections between obesity-related NAFLD and increased volume of the spleen, and (3) analysis of current immune-mediated mechanisms characterizing the so.called chronic low-grade inflammation leading to insulin resistance.Expert opinion: The advances in explaining mechanisms underlying the spleen involvement in immune regulation, coupled with research about the role of spleen in NAFLD, could impact real world outcomes through establishing better tools for a precocious diagnosis. Using both liver and spleen ultrasonography, technique largely dealt with in this review, could expand the possibility to cover an adequate diagnostic path toward NAFLD, reaching a good sensibility and specificity.

Lack of Multidrug Resistance-associated Protein 4 Prolongs Partial Hepatectomy-induced Hepatic Steatosis

Multidrug resistance-associated protein 4 (Mrp4) is an efflux transporter involved in the active transport of several endogenous and exogenous chemicals. Previously, we have shown that hepatic Mrp4 expression increases following acetaminophen overdose. In mice, these increases in Mrp4 expression are observed specifically in hepatocytes undergoing active proliferation. From this, we hypothesized that Mrp4 plays a key role in hepatocyte proliferation and that lack of Mrp4 impedes liver regeneration following liver injury and/or tissue loss. To evaluate the role of Mrp4 in these processes, we employed two-third partial hepatectomy (PH) as an experimental liver regeneration model. In this study, we performed PH-surgery on male wildtype (C57BL/6J) and Mrp4 knockout mice. Plasma and liver tissues were collected at 24, 48, and 72 h postsurgery and evaluated for liver injury and liver regeneration endpoints, and for PH-induced hepatic lipid accumulation. Our results show that lack of Mrp4 did not alter hepatocyte proliferation and liver injury following PH as evaluated by Ki-67 antigen staining and plasma alanine aminotransferase levels. To our surprise, Mrp4 knockout mice exhibited increased hepatic lipid content, in particular, di- and triglyceride levels. Gene expression analysis showed that lack of Mrp4 upregulated hepatic lipin1 and diacylglycerol O-acyltransferase 1 and 2 gene expression, which are involved in the synthesis of di- and triglycerides. Our observations indicate that lack of Mrp4 prolonged PH-induced hepatic steatosis in mice and suggest that Mrp4 may be a novel genetic factor in the development of hepatic steatosis.

Black Current Anthocyanins Improve Lipid Metabolism and Modulate Gut Microbiota in High-Fat Diet-Induced Obese Mice

SCOPE

This study aimed to explore the anti-obesity potential of blackcurrant anthocyanins (BCA) and investigate the correlation between the gut microbiota and the BCA-induced beneficial effects.

METHODS AND RESULTS

Male C57BL/6J mice (n = 36) are randomly assigned into low-fat diet group (LFD), high-fat diet group (HFD), and BCA group feeding HFD supplemented with BCA for 12 weeks. Body weight and food intake are monitored weekly. Obesity-related biochemical indexes and the expression levels of genes related to lipid metabolism are determined. Amplicon sequencing of the bacterial 16S rRNA gene is conducted to analyze the gut microbiota structure, and spearman correlation analysis is used to determine the correlations between gut microbiota and obesity-related indicators. The results showed that BCA treatment alleviated HFD-induced obesity, hyperlipemia, and hepatic steatosis. Moreover, BCA supplement improved hepatic lipid metabolism by regulating the expression of genes related to the synthesis and degradation of lipids and cholesterols. Microbial analysis revealed that BCA supplementation significantly changed the overall structure and composition of the gut microbiota, and resulted in an enrichment of Akkermansia_muciniphila, which is negatively correlated with the physical biomarkers.

CONCLUSION

This study demonstrated that BCA supplement could be a beneficial treatment for preventing HFD-induced obesity by targeting microbiota.

Emerging Role of MiR-192-5p in Human Diseases

MicroRNAs (miRNAs) are a type of small non-coding RNAs that play an essential role in numerous biological processes by regulating the post-transcriptional expression of target genes. Recent studies have demonstrated that miR-192-5p, a member of the miR-192 family, partakes in several human diseases, especially various cancers, including cancers of the lung, liver, and breast. Importantly, the levels of miR-192-5p are abundant in biofluids, including the serum and urine, and the exosomal levels of miR-192-5p in circulation can aid in the diagnosis and prognosis of various diseases, such as chronic hepatitis B (CHB) infection disease. Notably, recent studies suggest that miR-192-5p is regulated by long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs). However, there are no comprehensive overviews on the role of miR-192-5p in human diseases. This review discusses the significant studies on the role of miR-192-5p in various human diseases, with special emphasis on the diseases of the respiratory and digestive systems.

Comprehensive characterization of metabolic, inflammatory and fibrotic changes in a mouse model of diet-derived nonalcoholic steatohepatitis

The objective of this study was to develop a well-characterized mouse model of nonalcoholic steatohepatitis (NASH) with a strong manifestation of liver fibrosis. The progression of metabolic, inflammatory and fibrotic features of this mouse model was monitored by performing in vivo time-course study. Male C57BL/6J mice were fed a high-fat/high-sucrose/high-cholesterol diet (34% fat, 34% sucrose and 2.0% cholesterol, by weight) for 2, 4, 6, 8, 10, 12, 14 or 16 weeks to induce obesity-associated metabolic dysfunctions, inflammation and fibrosis in the liver and white adipose tissue (WAT). Body and liver weights were gradually increased with significant hepatic triglyceride accumulation, i.e., liver steatosis, and marked elevation of serum alanine transaminase levels at week 10. While hepatic inflammation was displayed with the highest expression of macrophage markers and M1 markers at week 6, liver fibrosis determined by collagen accumulation was continuously increased to week 16. In epididymal WAT, weights and adipocyte size peaked at week 6-8. The increased expression of fibrogenic genes preceded inflammatory features (week 2 to 6 vs. week 6 to 16), suggesting that early fibrosis may trigger inflammatory events in the WAT. This study established a mouse model of diet-induced NASH with a strong manifestation of liver fibrosis. This mouse model will be a valuable in vivo tool in studying the pathophysiology of NASH and also in testing preventive and therapeutic potentials of dietary components and drugs against NASH with liver fibrosis.

Blackcurrant (Ribes nigrum) Extract Prevents Dyslipidemia and Hepatic Steatosis in Ovariectomized Rats

Estrogen is involved in lipid metabolism. Menopausal women with low estrogen secretion usually gain weight and develop steatosis associated with abnormal lipid metabolism. A previous study showed that blackcurrant (Ribes nigrum L.) extract (BCE) had phytoestrogen activity. In this study, we examined whether BCE improved lipid metabolism abnormalities and reduced liver steatosis in ovariectomized rats, as a menopausal animal model. Twelve-week-old ovariectomized (OVX) rats were fed a regular diet (Ctrl) or a 3% BCE supplemented diet while sham rats were fed a regular diet for three months. Body weight, visceral fat weight, levels of serum triglycerides, total cholesterol, and LDL cholesterol decreased in the BCE-treated OVX and sham rats, but not in OVX Ctrl rats. The results of hematoxylin and eosin staining revealed that BCE decreased the diameters of adipocytes and the nonalcoholic fatty liver disease activity score. Furthermore, quantitative RTPCR indicated a decreased expression of hepatitis-related genes, such as tumor necrosis factor-α, IL-6, and IL-1β in OVX rats after BCE treatment. This is the first study that reported improvement of lipid metabolism abnormalities in OVX rats by BCE administration. These results suggest that the intake of BCE alleviated dyslipidemia and prevented nonalcoholic steatohepatitis during menopause in this animal model.

Nicotinamide riboside, an NAD+ precursor, attenuates the development of liver fibrosis in a diet-induced mouse model of liver fibrosis

OBJECTIVE

Liver fibrosis is part of the non-alcoholic fatty liver disease (NAFLD) spectrum, which currently has no approved pharmacological treatment. In this study, we investigated whether supplementation of nicotinamide riboside (NR), a nicotinamide adenine dinucleotide (NAD+) precursor, can reduce the development of liver fibrosis in a diet-induced mouse model of liver fibrosis.

METHODS

Male C57BL/6 J mice were fed a low-fat control (LF), a high-fat/high-sucrose/high-cholesterol control (HF) or a HF diet supplemented with NR at 400 mg/kg/day (HF-NR) for 20 weeks. Features of liver fibrosis were assessed by histological and biochemical analyses. Whole-body energy metabolism was also assessed using indirect calorimetry. Primary mouse and human hepatic stellate cells were used to determine the anti-fibrogenic effects of NR in vitro.

RESULTS

NR supplementation significantly reduced body weight of mice only 7 weeks after mice were on the supplementation, but did not attenuate serum alanine aminotransferase levels, liver steatosis, or liver inflammation. However, NR markedly reduced collagen accumulation in the liver. RNA-Seq analysis suggested that the expression of genes involved in NAD+ metabolism is altered in activated hepatic stellate cells (HSCs) compared to quiescent HSCs. NR inhibited the activation of HSCs in primary mouse and human HSCs. Indirect calorimetry showed that NR increased energy expenditure, likely by upregulation of β-oxidation in skeletal muscle and brown adipose tissue.

CONCLUSION

NR attenuated HSC activation, leading to reduced liver fibrosis in a diet-induced mouse model of liver fibrosis. The data suggest that NR may be developed as a potential preventative for human liver fibrosis.

Blackcurrant (Ribes nigrum) Extract Exerts an Anti-Inflammatory Action by Modulating Macrophage Phenotypes

Macrophages are polarized into different phenotypes depending on tissue microenvironment where they reside. In obesity-associated inflammation, M1-type macrophages are predominant in the inflamed tissue, exerting pro-inflammatory responses. Our previous studies demonstrate that blackcurrant consumption attenuates hepatic inflammation and lipopolysaccharide-stimulated inflammatory responses of splenocytes in obese mice. In this study, we determined whether blackcurrant modulates macrophage phenotypes to exert its anti-inflammatory action. Mouse bone marrow-derived macrophages (BMDM) and human THP-1 macrophages were polarized into M1 macrophages in the presence or absence of blackcurrant extract (BCE). BCE repressed M1 polarization of both murine and human macrophages. Also, to gain insight into the role of blackcurrant metabolites produced in vivo in the regulation of macrophage phenotypes, BMDM were treated with serum obtained from lean or obese mice fed blackcurrant. While serum from lean mice fed blackcurrant did not exert either anti-inflammatory actions or suppressive effects on M1 polarization, serum from obese mice fed blackcurrant reduced the expression of pro-inflammatory genes in BMDM. Our data demonstrate that BCE suppresses M1 polarization, with reduced pro-inflammatory responses. Moreover, this study suggests that blackcurrant metabolites may not exert their anti-inflammatory effect directly by altering macrophage phenotypes, but possibly by inhibiting the production of obesity-associated inflammatory factors.