Health Benefits of Carotenoids: A Role of Carotenoids in the Prevention of Non-Alcoholic Fatty Liver Disease

Carotenoids Improve Obesity and Fatty Liver Disease via Gut Microbiota: A Narrative Review

Carotenoids are natural micronutrients found in plants and microorganisms, but not synthesized by animals. Carotenoids show various biological activities, including antioxidant properties, regulation of cell growth, and modulation of gene expression and immune responses. The rising global incidence of fatty liver disease (FLD) and obesity highlights the importance of carotenoids in chronic progressive conditions. Gut microbiota (GM) dysbiosis is associated with the development and progression of obesity and FLD due to the effects of metabolites such as lipopolysaccharide (LPS), bile acids (BAs), and short-chain fatty acids (SCFAs). Furthermore, GM may affect intestinal barrier integrity. This review evaluates the potential impact of carotenoids on GM and intestinal barrier function, and their subsequent effects on obesity and FLD. We searched through a wide range of databases, such as Web of Science, Scopus, EMBASE, and PubMed, to collect data for our non-systematic review of English literature. Carotenoids such as lycopene, zeaxanthin, fucoxanthin, capsanthin, astaxanthin, and lutein can regulate GM composition and improve obesity and FLD by affecting energy expenditure, food intake, lipid profile, liver fat deposition, liver enzymes, inflammatory markers, glucose homeostasis, and bile acids. These carotenoids improve obesity and FLD through GM metabolites such as SCFAs and LPS. Our findings show that dietary supplementation of lycopene, zeaxanthin, fucoxanthin, capsanthin, astaxanthin, and lutein can positively affect obesity and FLD by regulating GM and intestinal barrier integrity.

The gut-liver axis links the associations between serum carotenoids and non-alcoholic fatty liver in a 7.8-year prospective study

Background

Many studies have shown that carotenoids are beneficial to non-alcoholic fatty liver disease (NAFLD). Therefore, we explored potential biomarkers of gut microbiota and fecal and serum metabolites linking the association between serum carotenoids and NAFLD in adults.

Methods

This 7.8-year prospective study included 2921 participants with serum carotenoids at baseline and determined NAFLD by ultrasonography (ULS-NAFLD) every 3 years. A total of 828 subjects additionally underwent magnetic resonance imaging to identify NAFLD (MRI-NAFLD). Gut microbiota was analyzed by 16S rRNA sequencing in 1,661 participants, and targeted metabolomics profiling in 893 feces and 896 serum samples was performed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in the middle term.

Results

A total of 2,522 participants finished follow-up visits. Of these participants, 770, 301, 474, and 977 were categorized into NAFLD-free, improved, new-onset, and persistent NAFLD groups based on their ULS-NAFLD status changes, respectively, and 342/828 were MRI-verified NALFD. Longitudinal analyses showed an inverse association between carotenoids and NALFD risk/presence (P-trend <0.05). Multivariable-adjusted odds ratios (ORs)/hazard ratio (HR) [95% confidence intervals (CIs)] of NAFLD for quartile 4 (vs. quartile 1) of total carotenoids were 0.63 (0.50, 0.80) for incident ULS-NAFLD, 0.20 (0.15, 0.27) for persistent ULS-NAFLD, 1.53 (1.10, 2.12) for improved-NAFLD, and 0.58 (0.39, 0.87) for MRI-NAFLD. The biomarkers in the gut-liver axis significantly associated with both serum carotenoids and NAFLD included sixteen microbial genera mainly in Ruminococcaceae and Veillonellaceae family, nineteen fecal metabolites containing medium-chain fatty acids (MCFAs), bile acids, and carnitines, and sixteen serum metabolites belonging to organic acids and amino acids. The total carotenoids-related scores of significant microbial genera, fecal and serum metabolites mediated the carotenoids-NAFLD association by 8.72%, 12.30%, and 16.83% (all P<0.05) for persistent NAFLD and 9.46%, 8.74%, and 15.7% for incident-NAFLD, respectively.

Conclusions

Our study reveals a beneficial association of serum carotenoids and incident and persistent NAFLD. The identified gut-liver axis biomarkers provided mechanistic linkage for the epidemiological association.

Association between the composite dietary antioxidant index and non-alcoholic fatty liver disease: evidence from National Health and Nutrition Examination Survey 2005-2016

Importance

Oxidative stress contributes to the progression of non-alcoholic fatty liver disease (NAFLD). Antioxidants from food can reduce NAFLD incidence, and the Composite Dietary Antioxidant Index (CDAI) measures total antioxidant capacity (TAC). However, the relationship between CDAI and NAFLD in the US adult population remains unclear.

Objective

To assess whether CDAI is associated with NAFLD in US adults.

Design setting and participants

This population-based cross-sectional study used data on US adults from the National Health and Nutrition Examination Survey (NHANES) 2005-2016 cycles. Data were analyzed from January to February 2024.

Exposures

CDAI obtained from the dietary intake questionnaire.

Main outcomes and measures

The main outcome was NAFLD which defined by the US fatty liver score (USFLI) ≥30. Sampling weights were calculated according to NHANES guidelines.

Results

Among 9,746 adults included in this study [mean age, 48.3 years; 4,662 (47.6%) males], 3,324 (33.0%) were classified as having NAFLD using USFLI. In the fully adjusted of multivariable logistic regression, CDAI was negatively associated with NAFLD (odds ratio [OR], 0.95; 95% CI, 0.93-0.98). Furthermore, individuals in the highest quartile of CDAI were 34% less likely to have NAFLD compared to those in the lowest quartile (OR, 0.66; 95% CI, 0.52-0.85). In subgroup analyses, CDAI was inversely associated with NAFLD among participants with a BMI <25 (OR, 0.89; 95% CI, 0.83-0.95) and without metabolic syndrome (OR, 0.93; 95% CI, 0.91-0.96). The interaction tests revealed significant differences in these subgroups (P for interaction = 0.04 for BMI and 0.003 for metabolic syndrome). Sensitivity analyses confirmed this association using the hepatic steatosis index (HSI) to define NAFLD, applying unweighted logistic regression, adjusting for physical activity or after excluding non-Hispanic Black participants, and after excluding medications known for their potential hepatotoxic effects.

Conclusions and relevance

In this cross-sectional study based on six cycles (2005-2016) of the NHANES, CDAI was negatively associated with NAFLD in US adult population. This association highlights the potential for dietary interventions to reduce NAFLD incidence and underscores the need for future research, including clinical trials and mechanistic studies, to further explore the role of dietary antioxidants in NAFLD prevention and management.

Multi-omics analysis provides new insights into mechanism of didymin on non-alcoholic fatty liver disease in rats

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases accompanied by lipid and glucose metabolism disorder. Didymin has been reported to have various hepatoprotective effects, however, its potential effects and mechanisms on NAFLD remain unclear from the perspective of the whole.

PURPOSE

To investigate the underlying mechanism of didymin against NAFLD using multi-omics technologies.

METHODS

Rats were fed with a high-fat diet (HFD) for 8 weeks to induce NAFLD, followed by didymin treatment for 8 weeks. Next, biochemical analysis and histopathological examinations were performed to evaluate the effects of didymin. The key regulating pathways were predicted using transcriptomics, metabolomics and proteomics, and the target pathways were then verified by detecting the key genes/proteins using various experiments.

RESULTS

Didymin markedly mitigated liver injury and excessive lipid droplet accretion. An integrative multi-omics analysis suggested that the PPAR signaling cascade and insulin signaling pathway might serve as pivotal mechanisms underlying the modulation of lipid and glucose homeostasis by didymin. Further dissection identified five pivotal genes (PPARα, PPARβ, FABP4, ANGPTL4, and PLIN2) and four genes (HK1, HK3, GCK, and PTPN1) as potential hubs within these pathways. Subsequent validation experiments, including qPCR and Western blot, demonstrated upregulated expression of PPARα and PPARβ, indicating the activation of the PPAR pathway by didymin. Concurrently, didymin appeared to modulate the insulin signaling pathway, as evidenced by the upregulated expression of HK1 and downregulated expression of PTPN1. Notably, the manipulation of PPARα, PPARβ, and PTPN1 expression in LO2 cells through silence or overexpression confirmed that didymin significantly reduced lipid accumulation, with its molecular targets likely being the PPAR and insulin pathways.

CONCLUSIONS

Our findings demonstrate that didymin has a protective effect on NAFLD, and its underlying mechanism may be associated with the regulation of the PPAR and insulin signaling pathways.

Metabolomic changes in Citrus reticulata peel after conventional and ultrasound-assisted solid-state fermentation with Aspergillus niger: A focus on flavonoid metabolism

This study explored the changes in nutrients, metabolites, and enzyme activity in Citrus reticulata peel powders (CRPP) under conventional or ultrasound-assisted solid-state fermentation (SSF) using Aspergillus niger CGMCC 3.6189. Compared to nonfermented CRPP (NF-CRPP), ultrasound-assisted fermented CRPP (UIS-CRPP) significantly increased total protein and carotenoid levels by 85.26 % and 179.68 %, respectively, surpassing conventionally-fermented CRPP (FO-CRPP). Among the 521 identified differential metabolites, organic acids, lipids, and flavonoids were predominant. Flavonoid accumulation was primarily driven by the flavone and flavonol biosynthesis pathway, with 90.47 % and 90.00 % of differential flavonoids upregulated in FO-CRPP and UIS-CRPP, respectively. SSF significantly increased phenylalanine, tyrosine, and methionine levels, and tyrosine ammonia-lyase and β-D-glucosidase activities, with higher levels in UIS-CRPP. These findings suggest that conventional and ultrasound-assisted fermentation enhances flavonoid levels in CRPP by modulating key enzyme activities in flavonoid biosynthesis and biotransformation. Our study offers a feasible approach for producing value-added products from citrus peel waste.

Effects of Marine Natural Products on Liver Diseases

The prevention and treatment of liver disease, a class of disease that seriously threatens human health, has always been a hot topic of medical research. In recent years, with the in-depth exploration of marine resources, marine natural products have shown great potential and value in the field of liver disease treatment. Compounds extracted and isolated from marine natural products have a variety of biological activities such as significant antiviral properties, showing potential in the management of alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD), protection of the liver from fibrosis, protection from liver injury and inhibition of the growth of hepatocellular carcinoma (HCC). This paper summarizes the progress of research on marine natural products for the treatment of liver diseases in the past decade, including the structural types of active substances from different natural products and the mechanisms underlying the modulation of different liver diseases and reviews their future prospects.

Influence of ultrasound on the microbiological, physicochemical properties, and sensory quality of different varieties of pumpkin juice

This study has investigated the effect of ultrasound (US) as an emerging non-thermal sterilization technique on microbial growth and quality changes in three freshly squeezed pumpkin juices (Cucurbita maxima Duchesne, Cucurbita moschata Duchesne, and Cucurbita pepo L.).The three pumpkin juices were ultrasonicated at different ultrasonic power (0-400 W), time (0-20 min), and temperature (0-30 °C), and the total colony counts of the treated pumpkin juices were less than 5 log CFU/mL, which complied with the food safety and consumption standards. Based on these results, we further investigated the effects of different ultrasonic power (25 kHz, 10 min, 20 °C, 0-400 W) on the physicochemical properties and sensory quality of the three pumpkin juices. The physicochemical properties (color, sugar content, organic acid content, soluble solids, and carotenoids) of treated pumpkin juice were retained or improved to some extent. The antioxidant capacity was also increased by 9.09%, 10.25%, and 16.9% compared to the untreated group. During sonication, the particle size of all samples decreased significantly, the microstructure broke down significantly, and the sensory qualities of pumpkin juice were well preserved after sonication.

Co-occurrence of Mycotoxin-Induced Hepatotoxicity in Mice Inhibited by Lycopene: Mitochondrial Impairment and Early Hepatic Fibrosis

SCOPE

Mycotoxins co-contamination of agricultural products poses a serious threat to human and animal health, especially hepatic dysfunction. Zearalenone (ZEN), deoxynivalenol (DON), and aflatoxin B1 (AFB1) are three commonly co-occurring mycotoxins. This study is to determine whether lycopene (LYC) can alleviate hepatic toxicity induced by the co-occurrence of ZEN, DON, and AFB1 in mice.

METHODS AND RESULTS

Eighty 6-week-old male ICR mice are divided into four groups: CON group (solvent control), LYC group (10 mg kg-1 LYC), Co-M group (10 mg kg-1 ZEN + 1 mg kg-1 DON + 0.5 mg kg-1 AFB1), and LYC+Co-M group (10 mg kg-1 LYC + 10 mg kg-1 ZEN + 1 mg kg-1 DON + 0.5 mg kg-1 AFB1). The results show that LYC can suppress the co-occurrence of mycotoxin-induced mitochondrial swelling and vacuolization accompanied by dysregulation of indices of mitochondrial dynamics (Mitofusin 1 (Mfn1), Mfn2, Optic atrophy 1 (Opa1), Dynamin-related protein 1 (Drp1), Fission 1 (Fis1) at the mRNA level; DRP1 and FIS1 at the protein level). LYC effectively inhibits co-occurrence of mycotoxin-induced activation of Cytochrome P450 2E1, and early fibrosis, as determined by staining with Masson's trichrome and α-SMA protein.

CONCLUSION

LYC successfully attenuates early hepatic fibrosis mainly through antioxidant activities and prevented mitochondrial injury.

Red and golden tomato administration improves fat diet-induced hepatic steatosis in rats by modulating HNF4α, Lepr, and GK expression

Introduction

Nonalcoholic fatty liver disease (NAFLD), characterized by lipid accumulation within hepatocytes exceeding 5% of liver weight, is strongly related to metabolic disorders, obesity, and diabetes and represents a health emergency worldwide. There is no standard therapy available for NAFLD. Lifestyle intervention, including phytonutrient intake, is key in preventing NAFLD development and progression.

Methods

We used a rat model of NAFLD to evaluate the effect of dietary supplementation with red tomato (RT) and golden tomato (GT)-a patented mix of fruit with varying degrees of ripeness and particularly rich in naringenin and chlorogenic acid-after steatosis development. We assessed the effects on body weight, metabolic profile, and hepatic steatosis.

Results and discussion

We found a correlation between the amelioration of all the parameters and the liver gene expression. Our results showed that, together with the reversion of steatosis, the consumption of RT and GT can cause a significant reduction in triglycerides, low-density lipoprotein-cholesterol, fasting glucose, and homeostasis model assessment index. Meanwhile, we observed an increase in high-density lipoprotein-cholesterol according to the amelioration of the general lipidic profile. Regarding hepatic gene expression, we found the upregulation of Gk and Hnf4α involved in metabolic homeostasis, Lepr involved in adipokine signaling, and Il6 and Tnf involved in inflammatory response. Taken together, our results suggest that dietary intake of red and golden tomatoes, as a nutraceutical approach, has potential in preventing and therapeutics of NAFLD.

Preventative and Therapeutic Effects of Astaxanthin on NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a significant public health issue owing to its high incidence and consequences, and its global prevalence is presently 30% and rising, necessitating immediate action. Given the current controversies related to NAFLD, the search for novel therapeutic interventions continues. Astaxanthin is a carotenoid that primarily originates from marine organisms. It is the best antioxidant among carotenoids and one of the most significant components in treating NAFLD. The use of astaxanthin, a xanthophyll carotenoid, as a dietary supplement to treat chronic metabolic diseases is becoming more evident. According to growing data, astaxanthin may be able to prevent or even reverse NAFLD by reducing oxidative stress, inflammation, insulin resistance, lipid metabolism, and fibrosis. Astaxanthin might become a viable therapeutic or treatment option for NAFLD in the upcoming years. Elucidating the impact and mechanism of astaxanthin on NAFLD would not only establish a scientific basis for its clinical application, but also potentially enhance the precision of experimental methodology for future investigations targeting NAFLD treatment. This review explores the potential preventive and therapeutic effects of astaxanthin on liver disorders, especially NAFLD.

The association of dietary phytochemical index and nonalcoholic fatty liver disease

Consumption of phytochemical-rich foods relates to the prevention of chronic diseases. In this study we assessed the dietary phytochemical index (PI) in metabolic parameters, liver enzymes, and severity of fibrosis among nonalcoholic fatty liver disease patients. This cross-sectional study was conducted on 210 patients with NAFLD. Fibrosis-4 index (FLB4), nonalcoholic fatty liver disease fibrosis score (NFS), FBS, lipids profile, AST, ALT, ALP, and GGT were measured. PI was calculated through the information obtained from a validated semi-quantitative food frequency. Multiple regression models were used to estimate mean difference changes in the evaluated variables associated with various dietary PI. Participants' mean ± SD of age and BMI were 39.23 ± 10.52 and 24.40 ± 2.64, respectively. We found that DPI is inversely associated with serum TG, TC, and LDL-C and directly associated with serum HDL-C and a higher score in DPI is associated with lower scores in NFS and FIB-4. Multivariate linear regression showed that there is an inverse association between DPI and AST, ALT, ALP, GGT, NFS, and FIB-4. Higher dietary PI could impact on reduction of NAFLD progression and improvement of metabolic parameters.

Macrophages and the development and progression of non-alcoholic fatty liver disease

The liver is the site of first pass metabolism, detoxifying and metabolizing blood arriving from the hepatic portal vein and hepatic artery. It is made up of multiple cell types, including macrophages. These are either bona fide tissue-resident Kupffer cells (KC) of embryonic origin, or differentiated from circulating monocytes. KCs are the primary immune cells populating the liver under steady state. Liver macrophages interact with hepatocytes, hepatic stellate cells, and liver sinusoidal endothelial cells to maintain homeostasis, however they are also key contributors to disease progression. Generally tolerogenic, they physiologically phagocytose foreign particles and debris from portal circulation and participate in red blood cell clearance. However as immune cells, they retain the capacity to raise an alarm to recruit other immune cells. Their aberrant function leads to the development of non-alcoholic fatty liver disease (NAFLD). NAFLD refers to a spectrum of conditions ranging from benign steatosis of the liver to steatohepatitis and cirrhosis. In NAFLD, the multiple hit hypothesis proposes that simultaneous influences from the gut and adipose tissue (AT) generate hepatic fat deposition and that inflammation plays a key role in disease progression. KCs initiate the inflammatory response as resident immune effectors, they signal to neighbouring cells and recruit monocytes that differentiated into recruited macrophages in situ. Recruited macrophages are central to amplifying the inflammatory response and causing progression of NAFLD to its fibro-inflammatory stages. Given their phagocytic capacity and their being instrumental in maintaining tissue homeostasis, KCs and recruited macrophages are fast-becoming target cell types for therapeutic intervention. We review the literature in the field on the roles of these cells in the development and progression of NAFLD, the characteristics of patients with NAFLD, animal models used in research, as well as the emerging questions. These include the gut-liver-brain axis, which when disrupted can contribute to decline in function, and a discussion on therapeutic strategies that act on the macrophage-inflammatory axis.

Structural characterization and anti-lipotoxicity effects of a pectin from okra (Abelmoschus esculentus (L.) Moench)

Okra (Abelmoschus esculentus (L.) Moench) is rich in various bioactive ingredients and used as a medicinal plant in traditional medicine. In the present study, to find the polysaccharide with anti-lipotoxicity effects from okra and clarify its structure, a pectin OP-1 was purified from okra, which had a backbone containing →4)-α-GalpA-(1 → residues, and 1,5-Ara linked the main chain through the O-3 of the residue →3,4)-α-GalpA-(1→, and the C-6 of residue 1, 4-α-GalpA replaced by methyl ester. In vitro experiments showed that OP-1 pretreatment alleviated oleic acid (OA)-induced lipid accumulation, ROS generation, apoptosis, transaminase leakage, and inflammatory cytokine secretion in HepG2 cells, resulting in reduced lipotoxicity. Further molecular results revealed that OP-1 increased Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation and affected the expression of AMPK downstream targets, including inhibit SREBP1c and FAS, as well as activate CPT-1A. Impressively, AMPK inhibitor dorsomorphin (Compound C) blocked the effects of OP-1 against lipotoxicity. The effects of OP-1 on lipid metabolism were also diminished by dorsomorphin. Our results demonstrated that OP-1 possesses a potent function in preventing lipotoxicity via regulating AMPK-mediated lipid metabolism and provide a novel insight into the future utilization of okra polysaccharide.

Potential role of inflammation in relation to dietary sodium and β-carotene with non-alcoholic fatty liver disease: a mediation analysis

Background

High sodium intake has been linked to the prevalence of non-alcoholic fatty liver disease (NAFLD), but underlying mechanism remains unclear. This study aims to explore the role of chronic inflammation in the association between sodium and NAFLD. We also observed whether β-carotene, which had a strong anti-inflammatory effect, lowers the odds of NAFLD.

Methods

We performed mediation analyses to assess the mediating effects of C-reactive protein (CRP) and red cell distribution width (RDW) on the relationship between dietary sodium and NAFLD defined by the hepatic steatosis index (HSI) and the fatty liver index (FLI), respectively.

Results

A total of 6725 participants were included in this study. Compared with the high sodium-low carotene group, participants in the high sodium-high carotene group had 16% and 26% lower odds for HSI and FLI-defined NAFLD, respectively. There were positive indirect effects of dietary sodium intake on the HSI-defined NAFLD (indirect effect: 0.0057, 95% CI: 0.0021–0.0091, P < 0.0001), as well as the FLI defined NAFLD (indirect effect: 0.0081, 95% CI: 0.0024–0.0162, P < 0.0001) when C-reactive protein (CRP) was considered as a mediator. The mediating effects were somewhat attenuated after further adjusting for dietary β-carotene intake. Similar results were found when RDW was considered as a mediator in the HSI-defined NAFLD analysis.

Conclusions

Higher sodium intake increases the odds of NAFLD by upregulating inflammation. Dietary β-carotene may attenuate this association by down regulating inflammation.

Crocetin Protected Human Hepatocyte LO2 Cell From TGF-β-Induced Oxygen Stress and Apoptosis but Promoted Proliferation and Autophagy via AMPK/m-TOR Pathway

Objective

To investigate the protective effects of crocetin against transforming growth factor-β (TGF-β)—induced injury in LO2 cells.

Methods

Human hepatocyte LO2 cells were pre-treated with crocetin (10 μM) for 6, 12, and 24 h, and then induced by TGF-β. Proliferation, oxidative stress, apoptosis, autophagy, and related proteins were assessed.

Results

Crocetin pre-treating promoted proliferation but suppressed apoptosis in TGF-β-induced LO2 cells. Crocetin protected LO2 cells from TGF-β-induced inflammation and oxygen stress by reducing reactive oxygen species (ROS) and malondialdehyde (MDA) but enhancing superoxide dismutase (SOD) and glutathione (GSH). Autophagy was suppressed in TGF-β but crocetin promoted autophagy in LO2 cells by mediating Adenosine 5'-monophosphate—activated protein kinase (AMPK)/mammalian target of rapamycin (m-TOR) signaling pathway via upregulating p-AMPK and p-Beclin-1 but downregulating p-mTOR.

Conclusions

Crocetin protected LO2 cells from TGF-β-induced damage by promoting proliferation and autophagy, and suppressing apoptosis and anti-inflammation via regulation of AMPK/m-TOR signaling pathway.

Protective Effect of Danshen Zexie Decoction Against Non-Alcoholic Fatty Liver Disease Through Inhibition of ROS/NLRP3/IL-1β Pathway by Nrf2 Signaling Activation

Lipid metabolism disorders are a prominent characteristic in the pathological development of non-alcoholic fatty liver disease (NAFLD). Danshen zexie decoction (DZD) is a Chinese herbal medicine that is based on zexie decoction and has an effect of regulating lipid mechanism. However, the anti-NAFLD effect and mechanism of DZD remain unclear. In this study, we observed the therapeutic effect of DZD on NAFLD rats and investigated its possible mechanisms. Sixty Sprague Dawley rats were randomly assigned to six groups: control group, model group, Yishanfu (polyene phosphatidylcholine) group, and low, medium and high-dose DZD groups. High-fat diet (HFD) was fed to the rats to establish an NAFLD model, and each treatment group was given corresponding drugs at the same time for eight consecutive weeks. The results revealed that the obvious lipid metabolism disorder and liver injury induced by HFD were alleviated by treatment with DZD, which was verified by decreased serum TC, TG, ALT, AST, liver TC, TG, and FFA, as well as the alleviation of hepatic steatosis. The production of ROS in rats was reduced after treatment with DZD. The SOD activity and GSH content were increased with DZD treatment, while the MDA level was decreased. The administration of DZD could decrease serum IL-1β and IL-18 contents. Moreover, DZD upregulated the expressions of Nrf2, HO-1, GCLC, and GCLM, while it suppressed the expressions of NLRP3, caspase-1, GSDMD, and GSDMD-N. In conclusion, the data showed that DZD can reduce lipid accumulation, alleviate oxidative stress and inflammation, and inhibit pyroptosis in NAFLD rats, which might be ascribed to suppression of the ROS/NLRP3/IL-1β signaling pathway by activation of Nrf2. Overall, these results indicated that DZD is expected to be a therapeutic drug for NAFLD.

Astaxanthin From Haematococcus pluvialis Prevents High-Fat Diet-Induced Hepatic Steatosis and Oxidative Stress in Mice by Gut-Liver Axis Modulating Properties

Scope

Evidence is mounting that astaxanthin (ATX), a xanthophyll carotenoid, used as a nutritional supplement to prevent chronic metabolic diseases. The present study aims to identify the potential function of ATX supplementation in preventing steatohepatitis and hepatic oxidative stress in diet-induced obese mice.

Methods and Results

In this study, ATX as dose of 0.25, 0.5, and 0.75% have orally administered to mice along with a high-fat diet (HFD) to investigate the role of ATX in regulating liver lipid metabolism and gut microbiota. The study showed that ATX dose-dependently reduces body weight, lipid droplet formation, hepatic triglycerides and ameliorated hepatic steatosis and oxidative stress. 0.75% ATX altered the levels of 34 lipid metabolites related to hepatic cholesterol and fatty acid metabolism which might be associated with downregulation of lipogenesis-related genes and upregulation of bile acid biosynthesis-related genes. The result also revealed that ATX alleviates HFD-induced gut microbiota dysbiosis by significantly inhibiting the growth of obesity-related Parabacteroides and Desulfovibrio while promoting the growth of Allobaculum and Akkermansia.

Conclusion

The study results suggested that dietary ATX may prevent the development of hepatic steatosis and oxidative stress with the risk of metabolic disease by gut-liver axis modulating properties.

Fucoxanthin Attenuates Free Fatty Acid-Induced Nonalcoholic Fatty Liver Disease by Regulating Lipid Metabolism/Oxidative Stress/Inflammation via the AMPK/Nrf2/TLR4 Signaling Pathway

Fucoxanthin, a xanthophyll carotenoid abundant in brown algae, is reported to have several biological functions, such as antioxidant, anti-inflammatory, and anti-tumor activities, in mice. We investigated the effects and mechanisms of fucoxanthin in the mixture oleate/palmitate = 2/1(FFA)-induced nonalcoholic fatty liver disease (NAFLD) cell model in this study. The results showed that the content of superoxide dismutase in the FFA group was 9.8 ± 1.0 U/mgprot, while that in the fucoxanthin high-dose (H-Fx) group (2 μg/mL) increased to 22.9 ± 0.6 U/mgprot. The content of interleukin-1β in the FFA group was 89.3 ± 3.6 ng/mL, while that in the H-Fx group was reduced to 53.8 ± 2.8 ng/mL. The above results indicate that fucoxanthin could alleviate the FFA-induced oxidative stress and inflammatory levels in the liver cells. Oil red-O staining revealed visible protrusions and a significant decrease in the number of lipid droplets in the cytoplasm of cells in the fucoxanthin group. These findings on the mechanisms of action suggest that fucoxanthin can repair FFA-induced NAFLD via the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway and nuclear factor erythroid-2-related factor 2-mediated (Nrf2) signaling pathway, as well as by downregulating the expression of the Toll-like receptor 4-mediated (TLR4) signaling pathway. Fucoxanthin exhibited alleviating effects in the FFA-induced NAFLD model and could be explored as a potential anti-NAFLD substance.

The Mediation Role of the Risk of Non-Alcoholic Fatty Liver Disease in Relationship between Lutein and Zeaxanthin and Cognitive Functions among Older Adults in the United States

Background: Previous studies showed lutein and zeaxanthin (L and Z) may influence cognitive function by different mechanisms. Our study aimed to be the first to examine whether the risk of non-alcoholic fatty liver disease (NAFLD) mediated the possible association between the dietary intake of L and Z and cognitive function. Methods: We conducted a cross-sectional analysis of participants aged 60 years or over in the National Health and Nutrition Examination Survey (NHANES) 2011–2014. Multivariable linear regression was used to investigate the association between the dietary intake of L and Z and cognitive function, and structural equation modeling tested the mediation effect. Results: The fatty liver index for the United States population (US FLI) acted as a mediator in the association between the higher intake of L and Z and the Animal Fluency Test, the Digit Symbol Substitution Test (DSST), and composite score and mediated 13.89%, 17.87%, and 13.79% of the total association in dietary L and Z intake (14.29%, 13.68%, and 10.34% of the total association in total L and Z intake), respectively. Conclusion: Our study indicated the potential role of the risk of NAFLD as a mediator of associations between the dietary intake of L and Z and cognitive function in the geriatric American population.

Effect of Ultrasound-Assisted Extraction of Carotenoids from Papaya (Carica papaya L. cv. Sweet Mary) Using Vegetable Oils

By-products from fruits and are of great interest for their potential use in the food industry due to their high content of bioactive compounds. Herein, we examined the ultrasound-assisted extraction (UAE) of carotenoid and carotenoid esters from papaya pulp and peel using soybean oil and sunflower oil as alternative green solvents. Response surface methodology (RSM) was established to optimize the UAE process. Three independent variables, ultrasonic amplitude (20–60%), time (10–60 min), and co-solvent percentage (ethanol) (5–20%, v/v), were applied. The highest total carotenoid content in the UAE extracts was obtained from papaya pulp extracts (58.7 ± 1.6 and 56.0 ± 1.5 μg carotenoids/g oil) using soybean oil and sunflower oil, respectively (60% amplitude/ 10 min/ 20% ethanol). On the other hand, the highest carotenoid content (52.0 ± 0.9 μg carotenoids/g oil) was obtained from papaya peel using soybean oil applying the UAE process (20% amplitude/ 77 min/ 20% ethanol); a minor content of 39.3 ± 0.5 μg carotenoids/g oil was obtained from papaya peel using sunflower oil at 60% amplitude/ 60 min/ 5% ethanol. Lycopene was the most abundant carotenoid among all individual carotenoids observed in papaya oil extracts, obtaining the highest yields of this carotenoid when papaya pulp and peel were extracted using soybean oil (94% and 81%, respectively) and sunflower oil (95% and 82%, respectively). Great extraction of xanthophyll esters was detected using 20% of ethanol in the vegetable oil extraction solvent (v/v). High correlations (>0.85) was obtained between total carotenoid content and color determination in the UAE oil extracts. UAE vegetable oil extracts enriched with carotenoids from papaya by-products could be useful to formulate new food ingredients based on emulsions with interesting potential health benefits.

Translatomics Probes Into the Role of Lycopene on Improving Hepatic Steatosis Induced by High-Fat Diet

Liver is an important organ for fat metabolism. Excessive intake of a high-fat/energy diet is a major cause of hepatic steatosis and its complications such as non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. Supplementation with lycopene, a natural compound, is effective in lowering triglyceride levels in the liver, although the underlying mechanism at the translational level is unclear. In this study, mice were fed a high-fat diet (HFD) to induce hepatic steatosis and treated with or without lycopene. Translation omics and transcriptome sequencing were performed on the liver to explore the regulatory mechanism of lycopene in liver steatosis induced by HFD, and identify differentially expressed genes (DEGs). We identified 1,358 DEGs at the translational level. Through transcriptomics and translatomics joint analysis, we narrowed the range of functional genes to 112 DEGs and found that lycopene may affect lipid metabolism by regulating the expression of LPIN1 at the transcriptional and translational levels. This study provides a powerful tool for translatome and transcriptome integration and a new strategy for the screening of candidate genes.

Lutein attenuates angiotensin II- induced cardiac remodeling by inhibiting AP-1/IL-11 signaling

RATIONALE

Oxidative stress plays a critical role in the development of cardiac remodeling and heart failure. Lutein, the predominant nonvitamin A carotenoid, has been shown to have profound effects on oxidative stress. However, the effect of lutein on angiotensin II (Ang II)-induced cardiac remodeling and heart failure remains unknown.

OBJECTIVE

The aim of this study was to determine whether lutein is involved in cardiac remodeling and to elucidate the underlying molecular mechanisms.

METHODS AND RESULTS

In vitro experiments with isolated neonatal rat cardiomyocytes (NRCMs) and cardiac fibroblasts (CFs) revealed that lutein significantly attenuated Ang II-induced collagen expression in CFs, and cardiomyocyte hypertrophy. The Ang II-induced increases in superoxide generation, inflammation and apoptosis in cultured CFs were strikingly prevented by lutein. In vivo, fibrosis, hypertrophic cardiomyocyte and superoxide generation were analyzed, and lutein was demonstrated to confer resistance to Ang II-induced cardiac remodeling in mice. Mechanistically, RNA sequencing revealed that interleukin-11 (IL-11) expression was significantly upregulated in mouse hearts in response to Ang II infusion and was significantly suppressed in the hearts of lutein-treated mice. Furthermore, IL-11 overexpression blocked the effects of lutein on fibrosis and oxidative stress in CFs and impaired the protective effect of lutein on cardiac remodeling. Notably, we discovered that lutein could reduce Ang II-induced IL-11 expression, at least partly through the regulation of activator protein (AP)-1 expression and activity.

CONCLUSIONS

Lutein has potential as a treatment for cardiac remodeling and heart failure via the suppression of IL-11 expression.

Hesperetin ameliorates hepatic oxidative stress and inflammation via the PI3K/AKT-Nrf2-ARE pathway in oleic acid-induced HepG2 cells and a rat model of high-fat diet-induced NAFLD

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disease. Dietary supplementation has become a promising strategy for managing NAFLD. Hesperetin, a citrus flavonoid, is mainly found in citrus fruits (oranges, grapefruit, and lemons) and possesses multiple pharmacological properties, including anti-cancer, anti-Alzheimer and anti-diabetic effects. However, the anti-NAFLD effect and mechanisms of hesperetin remain unclear. In this study, we investigated the therapeutic effect of hesperetin against NAFLD and the underlying mechanism in vitro and in vivo. In oleic acid (OA)-induced HepG2 cells, hesperetin upregulated antioxidant levels (SOD/GPx/GR/GCLC/HO-1) by triggering the PI3 K/AKT-Nrf2 pathway, alleviating OA-induced reactive oxygen species (ROS) overproduction and hepatotoxicity. Furthermore, hesperetin suppressed NF-κB activation and reduced inflammatory cytokine secretion (TNF-α and IL-6). More importantly, we revealed that this anti-inflammatory effect is attributed to reduced ROS overproduction by the Nrf2 pathway, as pre-treatment with Nrf2 siRNA or an inhibitor of superoxide dismutase (SOD) or/and glutathione peroxidase (GPx) abolished hesperetin-induced NF-κB inactivation and reductions in inflammatory cytokine secretion. In a rat model of high-fat diet (HFD)-induced NAFLD, we confirmed that hesperetin relieved hepatic steatosis, oxidative stress, inflammatory cell infiltration and fibrosis. Moreover, hesperetin activated the PI3 K/AKT-Nrf2 pathway in the liver, increasing antioxidant expression and inhibiting NF-κB activation and inflammatory cytokine secretion. In summary, our results demonstrate that hesperetin ameliorates hepatic oxidative stress through the PI3 K/AKT-Nrf2 pathway and that this antioxidative effect further suppresses NF-κB-mediated inflammation during NAFLD progression. Thus, our study suggests that hesperetin may be an effective dietary supplement for improving NAFLD by suppressing hepatic oxidative stress and inflammation.

Spinach consumption and nonalcoholic fatty liver disease among adults: a case-control study

BACKGROUND

Spinach has high antioxidants and polyphenols and showed protective effects against liver diseases in experimental studies. We aimed to assess the association between dietary intake of spinach and odds of nonalcoholic fatty liver disease (NAFLD) in a case-control study among Iranian adults.

METHODS

Totally 225 newly diagnosed NAFLD patients and 450 controls, aged 20-60 years, were recruited in this study. Participants' dietary intakes were collected using a valid and reliable 168-item semi-quantitative food frequency questionnaire (FFQ). The logistic regression test was used for assessing the association between total, raw, and boiled dietary spinach with the odds of NAFLD.

RESULTS

The mean (SD) age and BMI of participants (53% male) were 38.1 (8.8) years and 26.8 (4.3) kg/m², respectively. In the final adjusted model for potential confounders, the odds (95% CI) of NAFLD in individuals in the highest tertile of daily total and raw spinach intake was [0.36 (0.19-0.71), P_trend = 0.001] and [0.47 (0.24-0.89), P_trend = 0.008], respectively compared with those in the lowest tertile. Furthermore, in the adjusted analyses, an inverse association was observed between the highest yearly intake versus no raw spinach consumption and odds of NAFLD [(OR 0.41; 95% CI 0.18-0.96), P for trend = 0.013]. However, there was no significant association between higher boiled spinach intake and odds of NAFLD.

CONCLUSIONS

The present study found an inverse association between total and raw spinach intake with the odds of NAFLD.

Nutraceuticals: Transformation of Conventional Foods into Health Promoters/Disease Preventers and Safety Considerations

Nutraceuticals are essential food constituents that provide nutritional benefits as well as medicinal effects. The benefits of these foods are due to the presence of active compounds such as carotenoids, collagen hydrolysate, and dietary fibers. Nutraceuticals have been found to positively affect cardiovascular and immune system health and have a role in infection and cancer prevention. Nutraceuticals can be categorized into different classes based on their nature and mode of action. In this review, different classifications of nutraceuticals and their potential therapeutic activity, such as anti-cancer, antioxidant, anti-inflammatory and anti-lipid activity in disease will be reviewed. Moreover, the different mechanisms of action of these products, applications, and safety upon consumers including current trends and future prospect of nutraceuticals will be included.

Oxidative Stress in Non-alcoholic Fatty Liver Disease. An Updated Mini Review

Non-alcoholic fatty liver disease (NAFLD) is a challenging disease caused by multiple factors, which may partly explain why it remains still orphan of an adequate therapeutic strategy. Herein we focus on the interplay between oxidative stress (OS) and the other causal pathogenetic factors. Different reactive oxygen species (ROS) generators contribute to NAFLD inflammatory and fibrotic progression, which is quite strictly linked to the lipotoxic liver injury from fatty acids and/or a wide variety of their biologically active metabolites in the context of either a two-hit or a (more recent) multiple parallel hits theory. An antioxidant defense system is usually able to protect hepatic cells from damaging effects caused by ROS, including those produced into the gastrointestinal tract, i.e., by-products generated by usual cellular metabolic processes, normal or dysbiotic microbiota, and/or diet through an enhanced gut–liver axis. Oxidative stress originating from the imbalance between ROS generation and antioxidant defenses is under the influence of individual genetic and epigenetic factors as well. Healthy diet and physical activity have been shown to be effective on NAFLD also with antioxidant mechanisms, but compliance to these lifestyles is very low. Among several considered antioxidants, vitamin E has been particularly studied; however, data are still contradictory. Some studies with natural polyphenols proposed for NAFLD prevention and treatment are encouraging. Probiotics, prebiotics, diet, or fecal microbiota transplantation represent new therapeutic approaches targeting the gut microbiota dysbiosis. In the near future, precision medicine taking into consideration genetic or environmental epigenetic risk factors will likely assist in further selecting the treatment that could work best for a specific patient.

Anti-inflammatory effects of astaxanthin against fungal keratitis

AIM

To characterize effect of astaxanthin (ASX) in Aspergillus fumigatus (A. fumigatus) induced keratitis in mouse model.

METHODS

In vivo, fungal keratitis mouse model was established in C57BL/6 mice using A. fumigatus, followed by ASX or dimethyl sulfoxide (DMSO) treatment. Clinical responses were evaluated by clinical score and myeloperoxidase (MPO) assay. Inflammatory cytokines were assessed by reverse-transcription polymerase chain reaction (RT-PCR), Western blot, immunofluorescence, and enzyme-linked immuno sorbent assay (ELISA).

RESULTS

In animal model, ASX improved corneal transparency and clinical response, suppressed the expression of inflammatory cytokine like IL-1β, TNF-α, and HMGB-1. Neutrophil levels have been shown to decrease in ASX-treated cornea by immunofluorescence and MPO. TLR2 and TLR4 levels were lower in ASX-treated group than DMSO-treated.

CONCLUSION

ASX can suppress inflammatory response and reduce inflammatory cytokine production in mice model with A. fumigatus keratitis.

Association between serum β-carotene-to-retinol ratio and severity of hepatic steatosis in non-alcoholic fatty liver disease in Japan: A cross-sectional study

OBJECTIVES

Retinol and β-carotene have been reported to be involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, clinical studies are limited. The aim of this study was to investigate the relationship between serum the ratio of β-carotene to retinol (SC/SR) and hepatic steatosis in NAFLD diagnosed by ultrasonography.

METHODS

The participants were 606 Japanese adults who were enrolled in a health survey. Clinical profile, dietary nutrition intake, blood biochemistry, serum retinol, and carotenoids were analyzed. NAFLD was defined as fatty liver on ultrasonography in the absence of other causes of steatosis.

RESULTS

Women had higher daily intake of α- and β-carotene, although there were no differences in daily retinol and carotenoid intake between participants with or without NAFLD in both men and women. Women had a higher SC/SR ratio than men regardless of the presence or absence of NAFLD, and the SC/SR ratio in women decreased with exacerbation of hepatic steatosis, whereas the SC/SR ratio in men did not change despite exacerbation of hepatic steatosis. After adjusting for confounding factors, the likelihood of NAFLD among participants in the highest quartile of SC/SR ratio decreased by two-thirds compared with participants in the lowest quartile (adjusted odds ratio, 0.64; 95% confidence interval, 0.21-1.92; P = 0.041). The SC/SR ratio was positively correlated with serum high-density lipoprotein cholesterol level, and negatively correlated with serum triacylglycerol level.

CONCLUSIONS

The SC/SR ratio was lower in NAFLD with sex differences, and was associated with the severity of hepatic steatosis and lipid profile. Future studies are needed to expand on these findings.

Fucoxanthin inhibits hepatic oxidative stress, inflammation, and fibrosis in diet-induced nonalcoholic steatohepatitis model mice

Nonalcoholic steatohepatitis (NASH) is associated with hepatocyte injury, excessive oxidative stress, and chronic inflammation in fatty liver, and can progress to more severe liver diseases, such as cirrhosis and hepatocellular carcinoma. However, currently there are no effective therapies for NASH. Marine carotenoid, fucoxanthin (Fx), abundant in brown seaweeds, has variable biological properties, such as anti-cancer, anti-inflammatory, anti-oxidative and anti-obesity. However, the effect of Fx on the development of NASH has not been explored. We investigated the protective effects of Fx in diet-induced NASH model mice fed choline-deficient L-amino acid-defined high fat diet (CDAHFD). Fx administration significantly attenuated liver weight gain and hepatic fat accumulation, resulting in the alleviation of hepatic injury. Furthermore, the Fx-fed mice, not only exhibited reduced hepatic lipid oxidation, but also decreased mRNA expression levels of inflammation and infiltration-related genes compared to that of the CDAHFD-fed mice. Moreover, fucoxanthinol and amarouciaxanthin A, two Fx metabolites exerted anti-inflammatory effects in the liver via inhibiting the chemokine production in hepatocytes. In case of fibrosis, one of the features of advanced NASH, the expression of fibrogenic factors including activated-hepatic stellate cell marker was significantly decreased in the liver of Fx-fed mice. Thus, the present study elucidated that dietary Fx not only inhibited hepatic oxidative stress and inflammation but also prevented early phase of fibrosis in the diet-induced NASH model mice.

Hepatoprotection and hepatotoxicity of Chinese herb Rhubarb (Dahuang): How to properly control the "General (Jiang Jun)" in Chinese medical herb

Chinese herb Rhubarb (Dahuang), one of the most widely used traditional Chinese medicine in clinical application for over a thousand years and known as the "General (Jiang Jun)" in Chinese medical herb, currently used clinically for long-term treatment of gastrointestinal diseases and chronic liver diseases. Through previous researches, it has been identified that Rhubarb possessed a good hepatoprotective effect, which primarily protected liver from oxidation, fibrosis and cirrhosis, liver failure, hepatocellular carcinoma and various types of hepatitis. Meanwhile, it has been recently reported that long-term administration of Rhubarb preparation may undertake the risk of liver damage, which has aroused worldwide doubts about the safety of Rhubarb. Therefore, how to correctly understand the "two-way" effect of Rhubarb on liver protection and liver toxicity provides a basis for scientific evaluation of Rhubarb's efficacy on liver and side effects, as well as guiding clinical rational drug use. In this review, the mechanisms of Rhubarb how to play a role in hepatoprotection and why it causes hepatotoxic potential will be elaborated in detail and critically. In addition, some positive clinical guidances are also advised on how to reduce its hepatotoxicity in medical treatment.

Nutraceutical characteristics of the brown seaweed carotenoid fucoxanthin

Fucoxanthin (Fx), a major carotenoid found in brown seaweed, is known to show a unique and wide variety of biological activities. Upon absorption, Fx is metabolized to fucoxanthinol and amarouciaxanthin, and these metabolites mainly accumulate in visceral white adipose tissue (WAT). As seen in other carotenoids, Fx can quench singlet oxygen and scavenge a wide range of free radicals. The antioxidant activity is related to the neuroprotective, photoprotective, and hepatoprotective effects of Fx. Fx is also reported to show anti-cancer activity through the regulation of several biomolecules and signaling pathways that are involved in either cell cycle arrest, apoptosis, or metastasis suppression. Among the biological activities of Fx, anti-obesity is the most well-studied and most promising effect. This effect is primarily based on the upregulation of thermogenesis by uncoupling protein 1 expression and the increase in the metabolic rate induced by mitochondrial activation. In addition, Fx shows anti-diabetic effects by improving insulin resistance and promoting glucose utilization in skeletal muscle.

Carotenoids and carotenoid conversion products in adipose tissue biology and obesity: Pre-clinical and human studies

Antiobesity activities of carotenoids and carotenoid conversion products (CCPs) have been demonstrated in pre-clinical studies, and mechanisms behind have begun to be unveiled, thus suggesting these compounds may help obesity prevention and management. The antiobesity action of carotenoids and CCPs can be traced to effects in multiple tissues, notably the adipose tissues. Key aspects of the biology of adipose tissues appear to be affected by carotenoid and CCPs, including adipogenesis, metabolic capacities for energy storage, release and inefficient oxidation, secretory function, and modulation of oxidative stress and inflammatory pathways. Here, we review the connections of carotenoids and CCPs with adipose tissue biology and obesity as revealed by cell and animal intervention studies, studies addressing the role of endogenous retinoid metabolism, and human epidemiological and intervention studies. We also consider human genetic variability influencing carotenoid and vitamin A metabolism, particularly in adipose tissues, as a potentially relevant aspect towards personalization of dietary recommendations to prevent or manage obesity and optimize metabolic health. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

Astaxanthin anticancer effects are mediated through multiple molecular mechanisms: A systematic review

During the latest decades, the interest on the effectiveness of natural compounds and their impact on human health constantly increased, especially on those demonstrating to be effective on cancer. Molecules coming from nature are currently used in chemotherapy like Taxol, Vincristine or Vinblastine, and several other natural substances have been showed to be active in reducing cancer cell progression and migration. Among them, astaxanthin, a xanthophyll red colored carotenoid, displayed different biological activities including, antinflammatory, antioxidant, proapoptotic, and anticancer effects. It can induce apoptosis through downregulation of antiapoptotic protein (Bcl-2, p-Bad, and survivin) expression and upregulation of proapoptotic ones (Bax/Bad and PARP). Thanks to these mechanisms, it can exert anticancer effects towards colorectal cancer, melanoma, or gastric carcinoma cell lines. Moreover, it possesses antiproliferative activity in many experimental models and enhances the effectiveness of conventional chemotherapic drugs on tumor cells underling its potential future use. This review provides an overview of the current knowledge on the anticancer potential of astaxanthin by modulating several molecular targets. While it has been clearly demonstrated its multitarget activity in the prevention and regression of malignant cells in in vitro or in preclinical investigations, further clinical studies are needed to assess its real potential as anticancer in humans.

Rosiglitazone ameliorates bile duct ligation-induced liver fibrosis by down-regulating NF-κB-TNF-α signaling pathway in a PPARγ-dependent manner

Liver fibrosis is a major cause of morbidity and mortality worldwide. One of its therapeutic targets is peroxisome proliferator-activated receptor γ (PPARγ), with its ligands including rosiglitazone being tested in pre-clinical and clinical studies. However, the effects of rosiglitazone on bile duct ligation (BDL)-induced liver fibrosis and the involved mechanisms remain unknown. Herein, we used floxed control (PPARγ^fl/fl) and hepatocyte-specific PPARγ deficient (HepPPARγ KO) mice to conduct BDL to induce liver fibrosis and treated the animals with rosiglitazone. After one week of BDL, mice in BDL group displayed liver injury evidenced by increased collagen content, fibrosis area, necrosis area and apoptotic cells, and elevated alkaline phosphatase and alanine transaminase activities in serum. Interestingly, rosiglitazone ameliorated BDL-induced liver injury in PPARγ^fl/fl mice but not in HepPPARγ KO mice. Mechanistically, rosiglitazone reduced BDL-induced collagen content by downregulating fibrotic related genes including transforming growth factor β1, α-smooth muscle actin and collagen type I α1, and decreased inflammation cytokine tumor necrosis factor α level by inhibiting phosphorylation of nuclear factor-κB in a PPARγ-dependent manner. Based on findings above, we demonstrated that rosiglitazone can ameliorate BDL-induced liver fibrosis in mice and confirmed its critical functions on fibrosis by regulating NF-κB-TNF-α pathway in a PPARγ-dependent manner.